Podcasts about confocal

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.21.548930v1?rss=1 Authors: Xiao, S., Cunningham, W. J., Kondabolu, K., Lowet, E., Moya, M. V., Mount, R., Ravasio, C., Economo, M. N., Han, X., Mertz, J. Abstract: Voltage imaging with cellular specificity has been made possible by the tremendous advances in genetically encoded voltage indicators (GEVIs). However, the kilohertz rates required for voltage imaging lead to weak signals. Moreover, out-of-focus fluorescence and tissue scattering produce background that both undermines signal-to-noise ratio (SNR) and induces crosstalk between cells, making reliable in vivo imaging in densely labeled tissue highly challenging. We describe a microscope that combines the distinct advantages of targeted illumination and confocal gating, while also maximizing signal detection efficiency. The resulting benefits in SNR and crosstalk reduction are quantified experimentally and theoretically. Our microscope provides a versatile solution for enabling high-fidelity in vivo voltage imaging at large scales and penetration depths, which we demonstrate across a wide range of imaging conditions and different GEVI classes. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.09.548132v1?rss=1 Authors: Wang, Y. L., Fan, J., Chung, S. H. Abstract: Widefield fluorescence imaging has significant challenges in visualizing neuronal fibers near cell bodies. Specifically, out-of-focus and scattered light from the bright cellbody often obscures nearby dim fibers and degrades their signal-to-background ratio. Scanning techniques can solve this problem but are limited by reduced imaging speed and increased cost. We greatly reduce stray light by modulating the illumination intensity to different structures. We use a digital micromirror device in the illumination channel of a common widefield microscope and use real-time image processing to pattern the illumination. With the setup, we illuminate bright cell bodies with minimal light intensity, and illuminate in focus fiber-like structures with high light intensity to reveal weak signals. Thus, we minimize the background and enhance the visibility of fibers in the final image. This targeted illumination significantly improves fiber contrast while maintaining a fast-imaging speed and low cost. Using a targeted illumination setup in a widefield microscope, we demonstrate confocal quality imaging of complex neurons in live C. elegans and zebrafish larva, as well as in in vitro mice brain slice. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.06.30.547235v1?rss=1 Authors: Kang, S. S., Lee, E. J., Kim, K., Otgonnamjil, D., Shin, S. H. Abstract: The TRPV4 cation channel, is expressed in a broad range of tissues where it participates in generation of Ca2+ signal and/or depolarization of membrane potential. Here, we identified post synaptic density protein 95 (PSD95) as an interacting protein of this epithelial Ca2+ channel using confocal microscopy analysis and immunological assay. Using co-immunoprecipitation assays, we demonstrated that PSD95 was part of the TRPV4 protein complex. PSD95 protein was specifically associated with the C-terminal tail of TRPV4 to form a complex. A TRPV4 tail deletion mutant ({Delta}DAPL871: 4d) exhibited a diminished capacity to bind PSD95. Confocal microscopy analysis suggested that apical localization of TRPV4 required PSD95-TRPV4 interaction. Our data clearly suggest that formation of a complex between TRPV4 and PSD95 can regulate TRPV4 membrane localization. Both TRPV4 Ca2+ channel and its autophagy activity of 4d were reduced by more than 80% compared to those of the TRPV4 wild type. Our observation suggests that PSD95-TRPV4 complex plays crucial roles in routing TRPV4 to the apical plasma membrane and maintaining its authentic Ca2+ channel and biological function. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Cristian Navarrete-Dechent, MD interviewed by Maral Skelsey, MD, FAAD

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.22.529525v1?rss=1 Authors: Keramidioti, A., Schneid, S., Busse, C., Cramer von Laue, C., Bertulat, B., Salvenmoser, W., Hess, M., Alexandrova, O., Glauber, K., Steele, R., Hobmayer, B., Holstein, T. W., David, C. N. Abstract: The Hydra nervous system is the paradigm of a simple nerve net. Nerve cells in Hydra, as in many cnidarian polyps, are organized in a nerve net extending throughout the body column. This nerve net is required for control of spontaneous behavior: elimination of nerve cells leads to polyps that do not move and are incapable of capturing and ingesting prey (Campbell, 1976). We have re-examined the structure of the Hydra nerve net by immunostaining fixed polyps with a novel pan-neuronal antibody that stains all nerve cells. Confocal imaging shows that there are two distinct nerve nets, one in the ectoderm and one in the endoderm, with the unexpected absence of nerve cells in the endoderm of the tentacles. The nerve nets in the ectoderm and endoderm do not contact each other. High-resolution images show that the nerve nets consist of bundles of parallel overlapping neurites. Transmission and serial block face scanning electron microscopy show that nerve bundles in the ectoderm are closely associated with ectodermal muscle processes. Nerve bundles in the endoderm are separate from muscle processes. The occurrence of bundles of neurites supports a model for continuous growth and differentiation of the nerve net by lateral addition of new nerve cells to the existing net. This model was confirmed by tracking newly differentiated nerve cells. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.22.521645v1?rss=1 Authors: Tse, C. M., Rong, Y., Zhang, Z., Lin, R., Sarker, R., Donowitz, M., Singh, V. Abstract: Background and Aims Cholesterol-rich membrane domains, also called lipid rafts (LR), are specialized membrane domains that provide a platform for intracellular signal transduction. Membrane proteins often cluster in LR that further aggregate into larger platform-like structures that are enriched in ceramide and are called ceramide-rich platforms (CRPs). The role of CRPs in the regulation of intestinal epithelial functions remains unknown. Down Regulated in Adenoma (DRA) is an intestinal Cl-/HCO3- antiporter which is enriched in LR. However, little is known regarding the mechanisms involved in the regulation of DRA activity. Methods Air liquid interface (ALI) was created by removing apical media for a specified number of days from 12-14 days post confluency Caco-2/BBe cells or confluent colonoid monolayer grown as submerged cultures. Confocal imaging was used to examine the dimensions of membrane microdomains that contain DRA. Results DRA expression and activity were enhanced by culturing Caco-2/BBe cells and human colonoids using an ALI culture method. ALI causes an increase in acid sphingomyelinase (ASMase) activity, an enzyme responsible for enhancing ceramide content in the plasma membrane. ALI cultures expressed a larger number of DRA-containing platforms with dimensions greater than 2 um compared to cells grown as submerged cultures. ASMase inhibitor, desipramine disrupted CRPs and reduced the ALI-induced increase in DRA expression in the apical membrane. Exposing normal human colonoid monolayers to ALI increased the ASMase activity and enhanced differentiation of colonoids along with enhancing basal and forskolin-stimulated DRA activity. Conclusions ALI increases DRA activity and expression by increasing ASMase activity and platform formation in Caco-2/BBe cells and by enhancing the differentiation of normal human colonoids. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Dr. Stanley Lipkowitz and Dr. Yoshimi Endo Greer from the Women's Malignancies Branch at the National Cancer Institute discuss a research paper they co-authored that was published by Oncotarget in 2018, entitled, "ONC201 kills breast cancer cells in vitro by targeting mitochondria." DOI - https://doi.org/10.18632/oncotarget.24862 Correspondence to - lipkowis@mail.nih.gov Abstract We report a novel mechanism of action of ONC201 as a mitochondria-targeting drug in cancer cells. ONC201 was originally identified as a small molecule that induces transcription of TNF-related apoptosis-inducing ligand (TRAIL) and subsequently kills cancer cells by activating TRAIL death receptors. In this study, we examined ONC201 toxicity on multiple human breast and endometrial cancer cell lines. ONC201 attenuated cell viability in all cancer cell lines tested. Unexpectedly, ONC201 toxicity was not dependent on either TRAIL receptors nor caspases. Time-lapse live cell imaging revealed that ONC201 induces cell membrane ballooning followed by rupture, distinct from the morphology of cells undergoing apoptosis. Further investigation found that ONC201 induces phosphorylation of AMP-dependent kinase and ATP loss. Cytotoxicity and ATP depletion were significantly enhanced in the absence of glucose, suggesting that ONC201 targets mitochondrial respiration. Further analysis indicated that ONC201 indirectly inhibits mitochondrial respiration. Confocal and electron microscopic analysis demonstrated that ONC201 triggers mitochondrial structural damage and functional impairment. Moreover, ONC201 decreased mitochondrial DNA (mtDNA). RNAseq analysis revealed that ONC201 suppresses expression of multiple mtDNA-encoded genes and nuclear-encoded mitochondrial genes involved in oxidative phosphorylation and other mitochondrial functions. Importantly, fumarate hydratase deficient cancer cells and multiple cancer cell lines with reduced amounts of mtDNA were resistant to ONC201. These results indicate that cells not dependent on mitochondrial respiration are ONC201-resistant. Our data demonstrate that ONC201 kills cancer cells by disrupting mitochondrial function and further suggests that cancer cells that are dependent on glycolysis will be resistant to ONC201. Sign up for free Altmetric alerts about this article - https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.24862 Press release - https://www.oncotarget.com/index.php?journal=oncotarget&page=news&op=press&item=onc201-kills-breast-cancer-cells-in-vitro-by-targeting-mitochondria Keywords - ONC201, breast cancer, mitochondria About Oncotarget Oncotarget is a peer-reviewed, open access biomedical journal covering research on all aspects of oncology. To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: SoundCloud - https://soundcloud.com/oncotarget Facebook - https://www.facebook.com/Oncotarget/ Twitter - https://twitter.com/oncotarget Instagram - https://www.instagram.com/oncotargetjrnl/ YouTube - https://www.youtube.com/OncotargetYouTube LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Oncotarget is published by Impact Journals, LLC: https://www.ImpactJournals.com Media Contact MEDIA@IMPACTJOURNALS.COM 18009220957

This week Dr Paola Pasquali catches up with Prof. Salvador Gonzalez-Rodriguez. Considered one of the “fathers” of Reflectance Confocal Microscopy, Prof. Gonzalez speaks about the role of RCM in the universe of non-invasive imaging techniques. He also speaks about the most common uses in dermatology, its sensitivity for diagnosing malignancies and the learning curve for this procedure, and explains the potential uses in teledermatology and the future hand-held prototype.

In deze praattafel: Techniek vd week: Confocale laser scanning microscopieVergeten wetenschapper: Lise MeitnerIG Nobel: Houden duiven van Picasso?De Ongrijpbare Mens: IthyphallofobieOrganisme van de week: De Bombardeerkever... Nieuwtjes: Lichtgevende dieren? Waren vogelbekdieren nog maar het begin?Grienden imiteren geluid van orka's zodat ze niet opgegeten wordenKangoeroes communiceren met mensen! Links: "Confocal microscopy - Wikipedia." https://en.wikipedia.org/wiki/Confocal_microscopy. "What is Confocal Laser Scanning Microscopy? - Bitesize Bio." 22 apr.. 2014, https://bitesizebio.com/19958/what-is-confocal-laser-scanning-microscopy/ "Lise Meitner - Wikipedia." https://nl.wikipedia.org/wiki/Lise_Meitner. "Grote bombardeerkever - Wikipedia." https://nl.wikipedia.org/wiki/Grote_bombardeerkever "Bombardeerkevers - Wikipedia." https://nl.wikipedia.org/wiki/Bombardeerkevers. "ithyphallophobia - Wiktionary." https://en.wiktionary.org/wiki/ithyphallophobia  "Eurotofobie - definitie - Encyclo." https://www.encyclo.nl/begrip/Eurotofobie KV 231 Mozart: https://www.youtube.com/watch?v=aDhhPXP4V2U

Paul J. Wang: Welcome to the monthly podcast! On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr. Paul Wang, Editor-in-Chief. With some of the key highlights from this month's issue. Paul J. Wang: In our first paper, Demilade Adedinsewo and associates assess the accuracy of an artificial intelligence-enabled electrocardiogram [AI-ECG] to identify patients presenting with dyspnea who have left ventricular LV systolic function (defined as LV ejection fraction ≤35%) in the emergency department [ED]. Patients were included if they had at least one standard 12-lead electrocardiogram [ECG] acquired on the date of the ED visit and an echocardiogram performed within 30 days of presentation. Patients with prior LV systolic dysfunction were excluded. A total of 1,606 patients were included. Meantime from ECG echocardiogram was one day. The AI-ECG algorithm identified LV systolic dysfunction with an area under the curve [AUC] of 0.89 and accuracy of 85.9%. Sensitivity was 74%, specificity 87%, negative predictive value 97%, and positive predictive value 40%. To identify an ejection fraction less than 50%, the AUC was 0.85, sensitivity 86%, sensitivity 63%, and specificity 91%. NT-proBNP alone with a cutoff greater than 800 identified LV systolic function with an AUC of 0.80 by comparison. Paul J. Wang: In our next paper, Mahmood Alhusseini and associates hypothesize that convolutional neural networks [CNN] may enable objective analysis of intracardiac activation in atrial fibrillation [AF]. They perform panoramic recording of bi-atrial electrical signals in AF and use the Hilbert-transform to produce 175,000 image grids in 35 patients labeled for a rotational activation by experts who showed consistency, but with variability (kappa [κ]=0.79). In each patient, ablation terminated atrial fibrillation. A CNN was developed and trained on 100,000 AF image grids validated on 25,000 grids, and then tested on a separate 50,000 grids. They found in a separate test cohort of 50,000 grids, CNN reproducibly classified AF image grids into those with or without rotational sites with 95.0% accuracy. This accuracy exceeded that of support vector machines, traditional linear discriminant, and k-nearest neighbor statistical analyses. To probe the CNN, they applied gradient weighted class activation mapping, which revealed that the decision logic closely mimicked rules used by experts (C statistic 0.96). The authors concluded that convolutional neural networks improve the classification of intercardiac AF maps compared to other analyses and agreed with expert evaluation. Paul J. Wang: In our next paper, Kenji Okubo and associates examined whether late potential LP, abolition and ventricular tachycardia [VT] non-inclusive ability predicted long-term outcomes in patients with non-ischemic cardiomyopathy [NICM] undergoing VT ablation. The total 403 patients with NICM (523 procedures) who underwent VT ablation from 2010 to 2016 were included. The underlying structural disease consists of dilated cardiomyopathy (DCM, 49%), arrhythmogenic right ventricular cardiomyopathy (ARVD 17%), postmyocarditis (14%), valvular heart disease (8%), congenital heart disease (2%), hypertrophic cardiomyopathy (2%), and others (5%). Epicardial access was performed in 57% of patients. At baseline, the LPs were present in 60% of patients, and a VT was either inducible or sustained/incessant in 85% of the cases. At the end of the procedure LP abolition was achieved in 79% of cases in VT noninducability in 80%. After a multivariate analysis, the combination of LP abolition and VT noninducibility was independently associated with free survival from VT (hazard ratio, 0.45, p = 0.0002) and cardiac death (hazard ratio 0.38, P = 0.005). The benefit of LP abolition of preventing the VT recurrence in ARVD and postmyocarditis appeared superior to that observed for DCM. Paul J. Wang: In our next paper, Domenico Corradi, Jeffrey Saffitz and associates hypothesize that structural molecular changes in atrial myocardium that correlate with myocardial injury and precede and predict postoperative atrial fibrillation [POAF] may identify new molecular pathways and targets for prevention of this common morbid complication. Right atrial appendage [RAA] samples were prospectively collected during cardiac surgery from 239 patients enrolled in the OPERA trial. 35.2% of patients experienced POAF compared to the non-POAF group. They were significantly older and more likely to have chronic obstructive pulmonary disease or heart failure. They had a higher Euro score and more often underwent valve surgery. No differences in atrial size were observed between POAF and non-POAF patients. The extent of atrial interstitial fibrosis, cardiomyocyte myocytolysis, cardiomyocyte diameter, glycogen storage, or connection 43 distribution at the time of surgery, was not significantly associated with the incidents of POAF. None of these histopathological abnormalities were correlated with level of NT pro-BNP, hs-cTnT, CRP, or oxidative stress biomarkers. The authors concluded that in sinus rhythm patients undergoing cardiac surgery, histopathological changes in RAA do not predict POAF. They did not also correlate with biomarkers of cardiac function, inflammation, and oxidative stress. Paul J. Wang: In our next paper, Mark McCauley, Liang Hong, Arvind Sridhar, and associates hypothesize that obesity decreases sodium channel NAF 1.5 expression via enhanced oxidative stress, thus reducing the sodium current and enhancing susceptibility to atrial fibrillation [AF]. They studied a diet induced obese [DIO] mouse model. Pacing induced AF in 100% of DIO mice versus 25% in controls (P 20 ms shorter than the other sites, and/or induction of AF/atrial tachycardia during measurements. LVA ablation was performed in the LA-LVA patients during the follow-up period of a mean of 62 weeks, the EP test-guided group had a significantly lower recurrence rate (19%,11/57 versus 41%, 22/54, P=0.012) and a higher Kaplan-Meier AF/AT-free survival curve compared with controls (P=0.01). No significant differences in the recurrence, and AF/AT-free survival curves between PWI (positive EP test) and non-PWI (negative EP test) subgroups were observed. Therefore, PWI for positive EP tests reduced the AF/AT recurrence in the EP test-guided group. A stepwise Cox proportional hazard analysis identified EP test-guided ablation as a factor, reducing recurrence rates. The recurrence rates in LA-LVA ablation group and EP test-guided group were similar. Paul J. Wang: In our next study, Jinxuan Lin and associates assess whether simultaneous pacing of the left and right bundle branch areas may achieve more synchronous ventricular activation than just bundle pacing alone. In symptomatic bradycardia patients, the distal electrode of the bipolar pacing lead was placed at the left bundle branch area via a transventricular-septal approach. This was used to pace the left bundle branch area, while the ring electrode was used to pace the right bundle branch area. Bilateral bundle branch area pacing [BBBP] was achieved by stimulating the cathode and anode in various configurations. BBBP was successfully performed in 22 out of 36 patients. Compared with LBBP, BBBP resulted in greater shortening of QRS duration (109.3 vs 118.4 ms, P < 0.001). LBBP resulted in paced RBBB configuration with a DRVAT of 115 ms and interventricular conduction delay of 34.0 ms. BBBP fully resolved the RBBB morphology in 18 patients. In the remaining 4 patients, RBBP pacing partially corrected the right bundle branch block. Paul J. Wang: In our next paper, Ramanathan Parameswaran, Jonathan Kalman, Geoffrey Lee and associates recorded 2-minute long segments of simultaneous inter-operative mapping of endo- and epicardial lateral right atrial [RA] wall in patients with persistent atrial fibrillation [AF] using 2 high-density grid catheters (16 electrodes, 3 mm spacing). Filtered unipolar and bipolar electrograms [EGMS] of continuous 2-minute AF recordings and electrodes locations were exported for phase analysis. They defined endocardial-epicardial dissociation [EED] as phase differences of ≥20 ms between paired endo- and epi electrodes. Wavefronts [WF] were classified as single rotations, that is single wavefront, focal waves, or disorganized activity as per standard criteria. Endo-Epi wave fronts were simultaneously compared on dynamic phase maps. Complex fractionated electrograms were defined as bipolar electrograms with directional changes occupying at least 70% of the sample area. 14 patients with persistent AF underwent cardiac surgery are included. EED was seen in 50.3% of phase maps with significant temporal heterogeneity. Disorganized activity (endo 41.3%, epi 46.8%, P = 0.0194) and single wave (endo 31.3 versus epi 28.1, P = 0.129) were the dominant patterns. Transient rotations (endo 22%, epi 19.2%, P = 0.169, mean duration 590 ms) and non-sustained focal waves (endo 1.2% and epi 1.6%, P = 0.669) were also observed. Apparent transmural migration of rotational activations (n=6) from the epi- to the endocardium was seen in 2 patients. EGM fractionation was significantly higher in the epicardium than endocardium (61.2% versus 51.6%, P < 0.0001). The authors concluded that simultaneous endo-epi phase mapping of prolonged human persistent AF recordings showed significant EED marked temporal heterogeneity, discordant and transitioning wavefronts patterns and complex fractionations. No sustained focal activity was observed. Such complex 3-dimensional interactions provide insights into why endocardial mapping alone may not fully characterize the AF mechanism and why endocardial ablation may not be sufficient. Paul J. Wang: In our next paper, Andrew Beaser and associates hypothesize that intravascular ultrasound [IVUS] could accurately visualize and quantify intravascular lead adherence and degree of intravascular lead adherence correlates with transvenous lead extraction difficulty. Serial imaging of leads occurred prior to transvenous lead extraction using IVUS. Intravascular lead adherence areas were classified as high or low grade. Degree of extraction difficulty was assessed using 2 metrics and correlated with intravascular lead adherence grade. Lead extraction difficulty was calculated for each patient and compared to IVUS findings. 158 vascular segments in 60 patients were analyzed: 141 (89%) low grade versus 17 (11%) high grade. Median extraction time (low = 0 versus high grade 97 seconds, P < 0.001) and median laser pulsations delivered (low = zero versus high grade 5,852, P < 0.001) were significantly higher in the high-grade segments. Most patients with low lead extraction difficulty score had low intravascular lead adherence grades. 86% of patients with high lead extraction difficulty score had low IVUS grade, and the degree of transvenous lead extraction difficulty was similar to patients with low IVUS grades and lead extraction difficulty scores. Paul J. Wang: In our next paper, András Bratincsák, and associates sought to create the foundation of normative ECG standards in the young using Z-scores. 102 ECG variables were collected from a retrospective cohort of 27,085 study subjects with no known heart conditions, age zero to 39 years. The cohort was divided into 16 age groups by gender. Median interquartile range and range were calculated for each variable adjusted to body surface area. Normative standards were developed for all 102 ECG variables, including heart rate; P, R, and T axis; R-T axis deviation; PR interval, QS duration, QT, and QTc interval; P, Q, R, S, and T amplitudes in 12 leads; as well as QRS and T wave integrals. Incremental Z-score values between negative 2.5 and 2.5 were calculated to establish the upper and lower limits of normal. Historical ECG interpretive concepts were reassessed and new concepts observed. The author summarized that electronically acquired ECG values based on the largest pediatric and young adult cohort ever compiled provide the first detailed, standardized, quantitative foundation of traditional and novel ECG variables. Paul J. Wang: In our next paper, Jungmin Hwang and associates hypothesize that suppressing the late sodium current may counterbalance the reduced repolarization reserve in long QT syndrome [LQTS] and prevent early depolarization [EAD] and polymorphic ventricular tachycardia [PVT]. They tested the effects of selective late sodium channel blocker GS967 on polymorphic ventricular tachycardia [PVT] induction in a transgenic rabbit model of type two using intact heart optical mapping, cellular electrophysiology, and confocal calcium imaging and computer modeling. They found that GS967 reduced ventricular fibrillation [VF] induction under a rapid pacing protocol (7 out of 14 hearts in control versus 1 out of 14 at 100 nanomolar) without altering action potential duration [APD] or restitution and dispersion. GS967 suppressed PVT incidents by reducing calcium mediated EADs and focal activity during isoproterenol perfusion (at 30 nanomolar, 7 out of 12 and a 100 nanomolar, 8 out of 12 without EADs and PVTs). Confocal calcium imaging of LQT myocytes revealed GS967 shortened calcium transient duration by accelerating sodium calcium exchanger mediated calcium efflux from cytosol, thereby reducing EADs. Computer modeling revealed the inward late sodium current potentiates EADs in the LQT setting through providing additional depolarizing currents through action potential plateau phase, and increasing intracellular sodium that decreases the depolarizing sodium calcium exchanger, thereby suppressing the action potential plateau and delaying the activation of slowly activating delayed rectifier current, IKS. Suggesting important roles in the late sodium current in regulating intracellular sodium. Thus, the authors concluded that selective late sodium channel blockade by GS967 prevents EADs and abolishes PVT in LQT rabbits by counterbalancing the reduced repolarization reserve and normalizing intracellular sodium. Paul J. Wang: In our next paper, Pietro Lazzerini, Mohamed Boutjdir and associates, hypothesize that systemic inflammation per se can significantly prolong QTc during infection via cytokine-mediated changes in potassium channel expression. They found in patients with acute infections, regardless of concomitant QT-prolonging anti-microbial therapy, QTc was significantly prolonged but rapidly normalized in parallel to C-reactive protein [CRP] and cytokine level reduction. Consistently, in Torsades de Pointes cohort, concomitant acute infections were prevalent 30% despite only a minority (25%) of these cases were treated with QT-prolonging anti-microbials. KCN J2, potassium channel expression in peripheral blood mononuclear cells was strongly correlated to that in ventricles, inversely associated to CRP and interleukin one changes in acute infection patients. The authors concluded that acute infection, systemic inflammation rapidly induces cytokine-mediated ventricular electrical remodeling and significant QTc prolongation, regardless of concomitant antimicrobial therapy. Paul J. Wang: In a research letter, Christophe Beyls and associates examined the risk of bradycardia and critically ill COVID-19 patients treated with Lopinavir [LPV], a protease inhibitor of HIV-1, and Ritonavir [RTV], another protease inhibitor that strongly inhibits hepatic cytochrome P 450 [CYP3A4] activity in order to increase the Lopinavir plasma concentration. During the first month of the outbreak, patients admitted to the ICU with positive PCR for COVID-19 received LPV (200 mg)/RVT (50 mg) twice daily for 10 days. Bradycardia was defined as heart rate below 60 for a period of more than 24 hours. All patients were monitored 24 hours a day for all hemodynamic parameters, including heart rate with a five-lead ECG. Monitors were linked to a computerized system allowing to extract hemodynamic data. LPV/RTV plasma concentration was monitored using analytic method, combining high propensity performance, liquid chromatography and tandem mass spectrometry at 72 hours and every 72 hours. They prospectively included 41 COVID-19 patients who received LPV/RTV treatment. Nine or 22% patients experienced bradycardia. No patients had a pre-existing nodal pathology on the ECG on admission. Among the 9 patients with bradycardia, 8 or 88% were sinus bradycardia and one (12%) third-degree AV block. Causality may be considered as bradycardia occurred at least 48 hours after LPV/RTV initiation, bradycardia resolved after discontinuation or dose reduction and no alternative cause was found. Patients who presented with bradycardia were older, had a higher RTV plasma concentration and a lower lymphocyte count. In our study, no correlation was found between RTV plasma concentration, LPV plasma concentration, and mean heart rate at day three. No patient had bradycardia in the first 48 hours after LPV/RTV administration. For patients with LPV RTV plasma level overdose, the dose of LPV RTV was divided by two until the next dose. For the patient with third degree AV block LPV/RTV was stopped. None of the patients had any known cytochrome CYP3A4-inhibiting drugs. The authors concluded that the results suggest that RTV plasma overdose in elderly critical ill patients may increase the risk of bradycardia. Paul J. Wang: In a research letter, Emily Zeitler and associates surveyed cardiac implantable device [CID] patients. A total of 109 patients were approached to participate, nine declined. Most respondents were white (79%), male (60%) with a mean age of 73 years. The median number of correct responses to the 11 factual questions was six. Respondents held some common misconceptions. For example, 25% of respondents believe that FDA determines the cost of the device. Trust in the FDA was high; 67% of respondents agreed "I trust the FDA". Respondents mostly agreed "the FDA would not approve my device unless it was a hundred percent safe". Only 6% of respondents agreed, "we would be better off if there was no FDA," and a similarly small fraction disagreed with "when it comes to medical devices, the U.S. does the best job in the world at keeping people safe". Most respondents, 69% demonstrated fear of device recalls by agreeing with "if there was a recall of all are part of my device, I think I would be worried or scared." On average, respondents were comfortable sacrificing some privacy for device surveillance, 75% agreed with "once the device has been approved, the FDA should continue to monitor for signs that there are problems with the device even if it means that private health information about me is collected". Respondents seemed to believe that the FDA was risk averse; 56% believed that the FDA does not approve devices unless they're a hundred percent safe. This is in contrast to trends shifting the demonstration of safety to post-approval settings and expanding acceptable forms of data for regulatory approval. Paul J. Wang: In a research letter, Laura Rottner, Christoph Sinning and associates examined novel high resolution imaging system based on a wide band dielectric technology, and reports the first clinical experience of feasibility and reliability of cryoballoon [CB] occlusion tool as compared to fluoroscopic and 3D transesophogeal [TEE] assessment during pulmonary vein isolation [PVI]. In consecutive patients with symptomatic atrial fibrillation [AF], cryoballoon-based ablation was performed with a novel 3D wide-band dielectric imaging system. Pulmonary vein [PV] occlusion was assessed with fluoroscopy in 3D-TEE and concomitantly correlated with the novel CB occlusion tool. The endpoint was defined as persistent PV isolation verified by spiral mapping catheter recordings 30 minutes after the last CB application. A total of 36 (90%) of PVs in 10 patients with paroxysmal (40%) and persistent (60%) were analyzed. In all patients, a normal PV anatomy with four separate PVs was documented. Visualization via 3D-TEE was feasible in 80% septal PVs and 100% of lateral PVs. In 67% of PVs, total PV occlusion was confirmed by all 3 imaging modalities. In 17% of PVs, incomplete PV occlusion was initially demonstrated by TEE and 3D dielectric imaging, whereas fluoroscopy suggested complete occlusion in initial analysis. After repositioning of the CB at 3 PVs, complete PV occlusion was verified by all three modalities. In 3 out of 36 (8%), no occlusion was initially seen by any imaging modality, for which the CB was repositioned resulting in total PV occlusion as confirmed by all three modalities. Two out of 36 PVs (6%) were confirmed to be occluded via fluoroscopy in 3D-TEE, but not by the CB occlusion tool. There was only one out of 36 PVs (3%), which were confirmed to be included by the CB tool and 3D-TEE, but not by fluoroscopy. A negative and positive predictive value of 1.0 and 0.6 was seen when comparing PV occlusion by the novel occlusion tool compared to PV collusion, verified by fluoroscopy and 3D-TEE. Paul J. Wang: In a special report, Jun Hirokami, and associates aim to clarify the spatial correlations between fractionated potential detected by Lumipoint with non-PV trigger. They enrolled 30 symptomatic atrial fibrillation [AF] patients who underwent non pulmonary vein [PV] foci ablation. 4 patients underwent the first procedure, 17 underwent second procedure and eight underwent third procedure, and one underwent a fourth procedure. They highlighted the fractionated signal area in atrial muscle [FAAM] during sinus rhythm and atrial pacing, thereby producing a digital FAAM map. They retrospectively applied Lumipoint to 30 patients in order to clarify the relationship between FAAM and non-pulmonary vein [PV] foci. Non-PV foci were successfully identified in all patients. They identified four patients with multiple non-PV foci. Of these four patients, one had non-PV foci at the superior vena cava and left arterial anterior wall. One had non-PV foci at the SVC and LA bottom wall. And two had non-PV foci at the SVC and interatrial septum. They only analyze 30 non-PV foci unrelated to SVC because the SVC isolation was routinely performed for non-PVC foci at the SVC. In order to analyze the correlation between FAAM and location of non-PV triggers, they determined the cutoff points of peaks slider, which non-PV triggers were completely located within the FAAM in. The accuracy of predicting location of the non-PV triggers was summarized using area under the receiver operating curve, a UROC curve. The optimal cutoff point of peak sliders to predict the location of non-PV was determined by the Youden Index. The Youden Index established the optimal cutoff point of the maximum peaks slider was 7; sensitivity was 0.906 and specificity 0.770. The peaks slider 7 was the most accurate predictor fractionated signals location area to the location of non-PV triggers. (area under the curve 0.902). The mean area of peaks slider 7 was six centimeters squared or 4.3% of the atrium. The authors concluded that the proof-of-concept observational study demonstrated that novel visualization tool of FAAM map successfully identified non-PV triggers that did not induce atrial fibrillation and/or non-PV foci, which potentially serve as substrates for AF maintenance. Paul J. Wang: In a special report, Leslie Saxon and associates update their prior publication providing further detail on mitigation adoption rates for the entirety of the U.S. patient population with implanted cardiac rhythm management devices falling under FDA cyber security advisories from any device manufacturer. They also provided limited data on known cybersecurity mitigation adoption outside the U.S. They report a unique complication resulting for introducing firmware to already implanted devices. Discuss how evolving FDA policies towards firmware mitigation adoption may increasingly determine how and when updates occur. They found that patients under 50 years of age and those over 80 years were less likely to receive the software upgrades, and male versus females had greater rates of upgrades. The upgrade rates varied according to U.S. Region and date of implant. Resynchronization devices were less likely to receive the upgrade, as were pacemaker dependent patient. Those ICD patients initially falling under the battery advisers were upgraded more frequently. The number of advisory patients followed in clinic was a significant predictor for firmware upgrade adoption, particularly for pacemakers that were often upgraded in smaller size clinics. Overall, only 24% of devices for all groups, and 22% of devices not impacted by the battery advisory were upgraded. For Abbott devices, the home communicator cyber security vulnerabilities were mitigated with an automatic software patch that was updated using the Merlin network, and adoption rates were nearly a hundred percent. For the entire patient cohort with impacted pacemaker and ICDs, U.S. and global adoption rates remain low at 24 to 35% with a low rate of complications. Most reported complications for pacemakers and ICD were symptoms (transient palpitations, dizziness, or syncope) that resulted from the temporary change in mode to VVI or transient loss of programmer telemetry while performing the upgrade (pacemaker 0.05%; ICD 0.01%). Globally, a total of 9 pacemakers and 8 ICDs required replacement, as a result of performing the firmware upgrade due to irreversible reversion to a backup pacing mode and loss of defibrillation therapy (ICDs). Analysis of the returned ICD pulse generaotrs found at 7 cases, the cause related to a capacitor bond failure that was exposed only when extended telemetry as required by the upgrade. The failure mechanism was an isolated component failure in the remaining ICD. The programmer based test has recently been FDA approved and can be performed prior to firmware upgrade to identify ICD patients at risk for capacitor bond failure. A total of 256 ICDs were susceptible to loss of RF telemetry after receiving a firmware update, and this has since been mitigated with a software patch. For Medtronic programmers, the initial mitigation responses of cybersecurity advisory was to take the programmers off the network. The network connection was enhanced with one or more security protections provided to the programmers using a flash drive, so the programmers can now be secured from potential cyber intrusion when connected to the network. Medtronic ICDs are currently being upgraded. The upgrade is being provided to impacted patients automatically when the device is interrogated with the programmer during follow-up. Metronic is introducing upgrades in phased approach with all expected to be completed by the beginning of 2021. There are 9% or 55,000 ICDs under this advisory that cannot receive the update due to design or safety constraints. Since the 2017 Abbott advisories identify cybersecurity vulnerabilities in pacemakers and ICDs with the potential for exploits have been increased, including 2 additional FDA advisories issued for another manufacturer. Medtronic's connected communication product and implantable defibrillators in the past 12 months. The authors comment that a recent report and a smaller number of Abbott impacted pacemaker and ICD patients from Canada reported marked differences in mitigation adoption rates between pacemakers and ICDs. This was due to an increase incremental clinical familiarity and comfort with performing the updates as experience and education surrounding these issues evolve. The authors indicate that automating cybersecurity updates without process in place for determining safety, for alerting patients or clinicians that have been delivered, may also be associated with yet unknown risks. Newer generation devices and communication protocols may render cyber security, advisories less frequent as cybersecurity integration is considered an essential aspect of device design. Paul J. Wang: In a review article, Albert Feeny and associates discuss the use of artificial intelligence [AI] and machine learning [ML] in medicine, which are currently areas of intense exploration showing potential to automate human tasks or even perform tasks beyond human capabilities. The first objective of this review is to provide the novice reader with a literacy of AI/ML methods, and to provide a foundation of how one may conduct an ML study. The review provides a technical overview of some of the most commonly used terms, challenges in AI/ML studies with reference to recent studies in cardiac electrophysiology to illustrate key points. The second objective of this review is to use examples from the recent literature to discuss how AI and ML are changing clinical practice and research in cardiac electrophysiology with emphasis on disease detection and diagnosis, prediction, and patient outcomes and novel characterization of disease. The final objective is to highlight important considerations and challenges for appropriate variation, adoption, and deployment of AI technologies and practice. Paul J. Wang: That's it for this month! We hope that you will find the journal to be the go-to place for everyone interested in the field! See you next time! This program is copyright American Heart Association 2020. Thank you.  

Welcome back to EyePod and the third episode of the imaging series, where we will continue to interview Neil Lagali and Berit Byström from the last episode.  In the future episodes in the imaging series, we will talk about OCT and OCT-A in wet AMD, followed by Diabetic Retinopathy. Stay tuned!  eyepod@bayer.com   MA-M_AFL-DK-0021-1    

Welcome back to EyePod and the second episode of the imaging series, where we will continue to interview Neil Lagali from the last episode. Today we would also like to express a special welcome to a new guest, Berit Byström, assistant professor and consultant at the Eye Department at Umeå University.  This episode will focus on how we can apply confocal imaging technique in the clinic - When to use it and how to interpret the outcome of the examination. Enjoy! eyepod@bayer.com   MA-M_AFL-DK-0019-1    

Welcome back to EyePod Bayer! This exciting episode will be the first in a series of interesting interviews and discussions about imaging of the eye. We will start in the anterior part, with confocal microscopy of the cornea, and continue with imaging of the back of the eye and retina with OCT and OCT-A.With us today we have Neil Lagail, from the Institution for Biomedical and Clinical Sciences at Linköping University. Neil is professor and internationally recognized expert in confocal microscopy. This is his second visit to the EyePod and last time he shared his knowledge in angiogenesis in the eye. Today we are looking forward to discussing the background and technical aspects of confocal microscopy of the cornea. In a second episode, we will invite Dr Berit Byström, assistant professor and consultant at the Eye Department at Umeå University, to discuss the clinical application with this interesting imaging technique.      eyepod@bayer.com   MA-M_AFL-DK-0018    

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.14.336032v1?rss=1 Authors: van der Wee, E. B., Fokkema, J., Kennedy, C. L., del Pozo, M., de Winter, M., Speets, P. N. A. S., Gerritsen, H. C., van Blaaderen, A. Abstract: A multitude of samples is required to monitor and optimize the quality and reliability of quantitative measurements of (super-resolution) light microscopes. Here, we present a single sample to calibrate microscopes, align their laser beams and measure their point spread function (PSF) in 3D. The sample is composed of a refractive index matched colloidal crystal of silica beads with fluorescent and gold cores. The microscope can be calibrated in three dimensions using the periodicity of the crystal; the alignment of the laser beams can be checked using the reflection of the gold cores; and the PSF can be measured at multiple positions and depths using the fluorescent cores. It is demonstrated how this sample can be used to visualize and improve the quality of confocal and super-resolution images. The sample is adjustable to meet the requirements of different NA objectives and microscopy techniques and additionally can be used to evaluate refractive index mismatches as a function of depth quantitatively. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.25.266387v1?rss=1 Authors: Thiele, J. C., Helmerich, D., Oleksiievets, N., Tsukanov, R., Butkevich, E., Sauer, M., Nevskyi, O., Enderlein, J. Abstract: Fluorescence lifetime imaging microscopy (FLIM) is an important technique that adds another dimension to the intensity and colour information of conventional microscopy. In particular, it allows for multiplexing fluorescent labels that have otherwise similar spectral properties. Currently, the only super-resolution technique that is capable of recording super-resolved images with lifetime information is STimulated Emission Depletion (STED) microscopy. In contrast, all Single-Molecule Localisation Microscopy (SMLM) techniques that employ wide-field cameras completely lack the lifetime dimension. Here, we combine Fluorescence-Lifetime Confocal Laser-Scanning Microscopy (FL-CLSM) with SMLM for realising single-molecule localisation-based fluorescence-lifetime super-resolution imaging (FL-SMLM). Besides yielding images with a spatial resolution much beyond the diffraction limit, it determines the fluorescence lifetime of all localised molecules. We validate our technique by applying it to direct STochastic Optical Reconstruction Microscopy (dSTORM) and Points Accumulation for Imaging in Nanoscale Topography (PAINT) im-aging of fixed cells, and we demonstrate its multiplexing capability on samples with two different labels that differ only by fluorescence lifetime but not by their spectral properties Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.14.251363v1?rss=1 Authors: Shepherd, J., Lecinski, S., Wragg, J., Shashkova, S., MacDonald, C., Leake, M. C. Abstract: The physical and chemical environment inside cells is of fundamental importance to all life but has traditionally been difficult to determine on a subcellular basis. Here we combine cutting-edge genomically integrated FRET biosensing to readout localized molecular crowding in single live yeast cells. Confocal microscopy allows us to build subcellular crowding heatmaps using ratiometric FRET, while whole-cell analysis demonstrates crowding is reduced when yeast is grown in elevated glucose concentrations. Simulations indicate that the cell membrane is largely inaccessible to these sensors and that cytosolic crowding is broadly uniform across each cell over a timescale of seconds. Millisecond single-molecule optical microscopy was used to track molecules and obtain brightness estimates that enabled calculation of crowding sensor copy numbers. The quantification of diffusing molecule trajectories paves the way for correlating subcellular processes and the physicochemical environment of cells under stress. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.20.212142v1?rss=1 Authors: Bowen, J. D., Schloop, A. E., Reeves, G. T., Menegatti, S., Rao, B. M. Abstract: Small synthetic peptides capable of crossing biological membranes represent valuable tools in cell biology and drug delivery. While several cell-penetrating peptides (CPPs) of natural or synthetic origin have been reported, no peptide is currently known to cross both cytoplasmic and outer embryonic membranes. Here we describe a method to engineer membrane-permeating cyclic peptides (MPPs) with broad permeation activity by screening mRNA display libraries of cyclic peptides against embryos at different developmental stages. The proposed method was demonstrated by identifying peptides capable of permeating Drosophila melanogaster (fruit fly) embryos and mammalian cells. The selected peptide cyclo[Glut-MRKRHASRRE-K*] showed a strong permeation activity of embryos exposed to minimal permeabilization pretreatment, as well as human embryonic stem cells and a murine fibroblast cell line. Notably, in both embryos and mammalian cells, the cyclic peptide outperformed its linear counterpart and the control MPPs. Confocal microscopy and single cell flow cytometry analysis were utilized to assess the degree of permeation both qualitatively and quantitatively. These MPPs have potential application in studying and non-disruptively controlling intracellular or intraembryonic processes. Copy rights belong to original authors. Visit the link for more info

This interview is with Peter Drent (recorded 05/06/20), the CEO of Dutch microscopy company Confocal.nl (https://www.confocal.nl/), and @orangeboxNL on Twitter. Teledyne Photometrics Web: https://www.photometrics.com/ Twitter: https://twitter.com/Photometrics LinkedIn: https://www.linkedin.com/company/teledynephotometrics/

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.13.093435v1?rss=1 Authors: Cui, J., Turcotte, R., Hampson, K. M., Wincott, M., Schmidt, C. C., Emptage, N. J., Charalampaki, C., Booth, M. J. Abstract: Visual guidance at the cellular level during neurosurgical procedures is essential for complete tumour resection. We present a compact reflectance confocal microscope with a 20 mm working distance that provided

This is a segment of WIALD on the One thing Podcast. WIALD stands for "What I am Learning Daily". This is the attempt to take you along my learning journey. In this episode I review the clinical study “. Many Patients With Irritable Bowel Syndrome Have Atypical Food Allergies Not Associated With Immunoglobulin E. (Fritscher-Ravens et al., 2019). This is a very important study that looks at foods that can cause inflammation in IBS. Typically, IBS patients are given the Low Fodmap Diet which is a great starting point to control IBS symptoms ,however, there have long been assumed connections between specific foods triggering IBS. This study used an imaging technique called Confocal laser endomicroscopy (CLE) that imaged the small intestine upon introduction of Wheat, Dairy, Soy, and Yeast in confirmed IBS patients compared to controls. Listen to my takeaways and what I learned. See below for full paper link. Fritscher-Ravens, A., Pflaum, T., Mösinger, M., Ruchay, Z., Röcken, C., Milla, P. J., … Schuppan, D. (2019). Many Patients With Irritable Bowel Syndrome Have Atypical Food Allergies Not Associated With Immunoglobulin E. Gastroenterology, 157(1), 109-118.e5. https://doi.org/10.1053/j.gastro.2019.03.046 https://www.gastrojournal.org/article/S0016-5085(19)34636-0/fulltext #IBS#integrative#functionalmedicine#nutrition#IBS --- Support this podcast: https://anchor.fm/adam-rinde/support

Ep 1 - Plastics Makes Perfect In the first episode of Dr. Audrey Klenke's podcast, "Plastics Makes Perfect," you can learn about confocal microscopy technology.Interested in checking out the technology for yourself? You can visit Pinnacle Plastic Surgery in Bluffton!Links:Watch this episode on YouTube: https://youtu.be/FydAauXAQmoPinnacle Plastic Surgery: http://pinnacleplasticsurgery.com/

In this episode, we take a closer look at the Lasertec Optelics Hybrid Confocal Microscope, which features high resolution, wide FOV, nano-scale measurement, and wavelength selection.

In this tutorial on confocal imaging, you will learn how you can: - Capture weaker signals—and still get sound, reproducible data. - Reach faster volumetric imaging without sacrificing resolution - Increase data throughput for your imaging needs Learn about the new Multiplex mode for parallel pixel acquisition with the ZEISS LSM 9 family and Airyscan 2. You can now acquire up to 8 superresolution image lines with high signal-to-noise rate in a single sweep. Capture dynamic processes, cellular signaling, molecular trafficking, and diffusion events with real-time superresolution and high SNR. The new Multiplex mode for Airyscan 2 uses smart illumination and detection schemes for parallel pixel acquisition on a confocal microscope. Scientists can now capture weaker signals, keep their context, and get statistically sound data. Extending Airyscan imaging to larger model systems with lower expression levels, the new Multiplex mode increases acquisition speeds even further. You get superresolution and a 4 times higher SNR compared to traditional confocals. This novel concept allows rapid volumetric imaging with unprecedented resolution beyond what is available in traditional confocal systems today. Airyscan 2 provides new data handling concepts, providing 6.6 times smaller data sizes and 5 times faster image reconstruction times. Further, optimized real time acquisition strategies employed with the LSM 9 family enable faster scan speeds for Airyscan 2, allowing higher data throughput.

Alessandro Cometta, Zeiss Milano, Italy speaks on "Setup and technology of a confocal microscope". This movie has been recorded at ICGEB Trieste and is part of "Fluorescence Microscopy - FluoMicro@ICGEB" course, Trieste 2 - 4 October 2018.

Förster (Fluorescence) Resonance Energy Transfer (FRET) has become a powerful tool to study protein-protein interactions and signal transduction in living cells. FRET is commonly read out either by detecting the ratio of the donor and acceptor intensities (sensitized emission) or by detecting the excited state lifetime of the donor, which decreases with increasing FRET (Fluorescence Lifetime IMaging or FLIM). FLIM is robust, immune to bleaching and inherently quantitative. On confocal microscopes, FLIM is typically read out by Time-Correlated Single Photon Counting (TCSPC). This requires expensive add-on hardware and is inherently very slow, necessitating accumulation of many consecutive scans to arrive at low-noise lifetime images. For this reason fast lifetime changes, such as those encountered when reading out live-cell signaling events with FRET sensors, cannot be detected. Accumulation of images and/or very slow scanning can also cause morphological artifacts in the acquired images. We present the Leica SP8 FALCON, a new high-end confocal instrument with built-in very fast FLIM capabilities. The instrument applies a novel technology to records photon arrival times at up to 80 MHz (160 MHz if two detectors are used) using the built-in spectral HyD detectors. To arrive at such high counts rates, the instrument uses real-time 10 GHz sampling and analysis algorithms that render it largely immune to pulse pile-up. Falcon FLIM has been fully integrated in the LAS-X software, allowing convenient acquisition of FLIM time-lapses, stitched FLIM overview images, FLIM XYZ-stacks and spectral FLIM stacks, among others, as well as combinations thereof. We scrutinized the performance of the SP8 FALCON and applied it to record agonist-induced changes in concentration of second messengers such as cAMP and Ca2+ with sub-micrometer precision at high speed- on the order of several (512×512) frames per second (FPS). To detect cAMP by FLIM, we used our newest generation of EPAC-based dedicated FLIM sensors, which use mTurquoise2 as a donor and a tandem of two monomeric dark Venus proteins as acceptors. Reducing the image format to 128×128 pixels, we acquired good quality FLIM time-lapses at 25 FPS (83 FPS using resonant scanning), allowing detection of even very fast signaling events, including e.g. the activation of G-proteins and Ca2+ sparks. The large numbers of detected photons reduce pixel-to-pixel variability in the calculated lifetimes. Finally we demonstrate that the SP8-FALCON is ideal for fast FLIM screening applications in both fixed- and live-cell formats.

Dr. Paul Wang:           Welcome to the monthly podcast On the Beat for Circulation Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor-in-chief, with some of the key highlights for this month's issue. We'll also hear from Dr. Suraj Kapa reporting on new research from the latest journal articles in the field.                                                 In our first article, Barry Maron associates report on the long term clinical course of hypertrophic cardiomyopathy patients following ICD therapy for ventricular arrhythmias. They studied a cohort of 486 high-risk hypertrophic cardiomyopathy patients with ICDs from eight international centers. Of these 486 patients over 6.4 years, 94 patients or 19% experienced appropriate ICD interventions, terminating VT or VF. Of the 94 patients receiving appropriate ICD therapy, 87 were asymptomatic or only mildly symptomatic at the time of appropriate ICD interventions. Of these 87 patients, 74 or 85% remained in classes one or two without significant change in clinical status of the subsequent 5.9 years up to 22 years. Among the 94 patients, there was one sudden death in three patients who died from non arrhythmic hypertrophic cardiomyopathy related processes. Post ICD intervention, freedom from hypertrophic cardiomyopathy, mortality was 100% at one year, 97% at five years, and 92% at 10 years, distinctly lower than the risk of ischemic or non ischemic cardiomyopathy in ICD trials.                                                 Hypertrophic cardiomyopathy patients with ICDs interventions reported the heightened anxiety and expectation of future shocks. However, they did not affect general psychological well-being or quality of life. The authors concluded that in hypertrophic cardiomyopathy, unlike ischemic heart disease, prevention of sudden death with ICD therapies unassociated with a significant increase in cardiovascular morbidity and mortality, nor transformation into heart failure deterioration, ICD therapy does not substantially impair overall psychological and physical well-being. In our next article, Abdulla Damluji and associates examined the cost of hospitalizations for cardiac arrest using the US nationwide inpatient sample from 2003 to 2012. Using the log transformation of inflation adjusted costs the authors examined 1,387,396 patients who were hospitalized after cardiac arrest. They had a mean age of 66 years. Inpatient procedures included coronary angiography in 15%, PCI in 7%, intra-aortic balloon pump in 4.4%, therapeutic hypothermia in 1.1%, and mechanical circulatory support in 0.1% of patients.                                                 Notably the rates of therapeutic hypothermia increased from 0 in 2003 to 2.7 in 2012, p less than 0.001. Both hospital charges inflation adjusted costs linear increased over time. In a multi-variant analysis predictors of inflation adjusted costs included large hospitals size, urban teaching hospital, and length of stay. Among co-morbidities, atrial fibrillation or fluid and electrolytes imbalance were the most common associated with cost. The authors found that during the period between 2003 and 2012 post cardiac arrest, hospitalizations had a steady rise and associated healthcare costs likely related to increase length of stay, medical procedures and systems of care.                                                 In our next paper, Peter Huntjens and associates examined intrinsic interventricular dyssynchrony as a predictor of human dynamic response to cardiac resynchronization. The authors use a cardiovascular computational model CircAdapt to characterize the isolated effect of intrinsic interventricular or intraventricular activation on resynchronization therapy response that is the change in LV dP/dt max. The simulated change in LV dP to dt max had a range of 1.3 to 26.5% increased considerably with increasing inter ventricular dyssynchrony. In contrast, the isolated effect of intra ventricular dyssynchrony was limited with the change in the LV dP/dt max range and the left ventricle from 12.3 to 18.3% in the right ventricle from 14 to 15.7%.                                                 Secondly, electrocardiographic imaging derived activation characteristics of 51 CRT candidates were used to create individual models of ventricular activation in CircAdapt. The model predicted change in LV dP/dt max was close to the actual value in left bundle branch block patients with 2.7% difference between measured and simulated when only intrinsic interventricular dyssynchrony was personalized. Among non left bundle branch block patients a change in LV dP/dt max was systematically over predicted by CircAdapt with a 9.2% difference between measured and simulated. Adding intra ventricular activation to the model did not improve the accuracy of response prediction. The authors found that computer revealed intrinsic interventricular dyssynchrony is the dominant component of the electrical substrate driving the response to CRT.                                                 In the next paper Kenji Kuroki and associates examined the use of voltage limit adjustment of substrate mapping and fast Fourier transform analysis of local ventricular bipolar electrograms during sinus rhythm to predict VT isthmuses. They performed these studies and nine post infarction patients who underwent catheter ablation for total of 13 monomorphic ventricular tachycardias. Relatively higher voltage areas on electroanatomical map or defined as high voltage channels, which were further classified as full or partial if the entire or more than 30% of the high voltage channel was detectable. 12 full high voltage channels were identified in seven of nine patients. Relatively higher fast Fourier transform areas were defined as high frequency channels, which were located on seven of 12 full high voltage channels. Five VT isthmuses or 71% were included in the seven full high voltage channels positive in high frequency channel positive sites.                                                 While no VT isthmuses were found in five full high voltage channel positive but high frequency channel negative sites, high frequency channels were identical to 9 out of 16 partial high voltage channels. Eight VT isthmuses or 89% were included in nine partial high voltage channel positive in high frequency channel positive sites, whereas no VTs isthmuses were found in the seven partial high voltage channel positive and high frequency channel negative sites.                                                 All high voltage channel positive in high-frequency channel positive sites predicted VT isthmus with a sensitivity of 100% and specificity of 80%. The authors concluded that based on this small series that combined use of voltage, limited adjustment and fast Fourier transform analysis may be useful method to detect VT isthmuses.                                                 In the next study, John Whitaker and associates examined the use of lesion index, LSI index, a proprietary algorithm combining contact force, radio-frequency application duration, and RF current. Cardiac CT was used to assess atrial tissue thickness. Ablation lines two to three per animal were created in the right atrium in seven mini pigs with point lesions using 25 watts of energy. Two weeks after the ablation, serial sections of targeted atrial tissue or examine histologically to identify gaps and transmural ablation. LSI guidelines had a lower incidence of histological gaps. Four gaps in the 69 catheter moved or 5.8% compared to ablation using LSI plus two millimeter lines in which there is seven gaps in 33 catheter moves or 21.2% and using LSI plus four millimeter lines in which there are 15 gaps in 23 moves or 65.2% p less than 0.0. The change in LSI was calculated retrospectively is a distance between two adjacent lesions above the mean LSI of the two lesions. Changing LSI values of 1.5 or less were associated with no gaps in transmural ablation.                                                 The authors concluded that in this mod of chronic atrial ablation delivery of uninterrupted transmural linear lesions may be facilitated using LSI to guide catheter movement. When change in LSI between adjacent legions is 1.5 millimeters or lower, no gaps in atrial linear lesions should be expected.                                                 In our next paper, Matthew Bennett and associate examined whether their response to antitachycardia pacing in patients with ICD could further discriminate ventricular from super ventricular arrhythmias in patients receiving ATP in the RAFT trial. The RAFT trial randomized 1,798 patients with New York Heart Association class two or three heart failure, left ventricular ejection fraction less than or equal to 30%, in QRS duration 120 millisecond or greater, to an ICD plus or a minus cardiac resynchronization. Beginning with 10,916 ATP attempts for 8,150 tachycardia episodes in 924 patients, the author's excluded tachycardias where ATP terminated the episode or were the specific etiology tachycardia was uncertain. In this study, they analyzed 3,676 ATP attempts delivered to 2,046 tachycardia episodes in 541 patients. The authors found that a shorter difference between the post pacing interval is PPI minus TCL, was more likely to be associated with VT than SVT, mean of 138.1 milliseconds for VT and 277.4 milliseconds for SVT p, less than 0.001. A PPI minus TCL value of less than or equal to 300 milliseconds had a sensitivity in 97.4% and a specificity of 28.3% for VT.                                                 The authors concluded that specifically the PPI minus TCL following antitachycardia pacing may help distinguish ventricular from supraventricular arrhythmias.                                                 In the next study, Shailee Shah and Amr Barakat and associates examined the outcomes after repeat AF ablation. The authors examined 137 patients out of a total of 10,378 patients undergoing Afib ablation who had had initial long-term success defined from recurrent arrhythmias for greater than 36 months off anti-arrhythmic drugs in subsequent underwent repeat ablation for recurrent atrial fibrillation. The median arrhythmia free period that define long-term success was 52 months. In redo-ablations reconnection of at least one of the pulmonary veins was found in 111 or 81% of patients. Additional non PV ablations were performed in 127 or 92.7% of patients. After a mean follow-up of 17 months, 103 patients or 75% were arrhythmia-free, 79 off anti-arrhythmics, and 24 on arrhythmics. The authors found that repeat ablations with re-isolation to the point of veins and modifying the atrial substrate had a good success rate.                                                 In the next article Qiongling Wang and associates hypothesized that genetic inhibition of CaMKII oxidation in a mouse model of Duchenne muscular dystrophy can alleviate abnormal calcium homeostasis thus preventing ventricular arrhythmias. The authors tested whether the selective loss of oxidation of the CaMKII effects ventricular arrhythmias in the mouse model of Duchenne muscular dystrophy. Genetic inhibition of ox-CaM kinase II by knocking replacement of the regulatory domain methionines with valines, which we'll call MMVV, prevented ventricular tachycardia in the mdx mice. Confocal calcium imaging of ventricular myocytes, isolated from the mdx MMVV mice revealed normalization of intra-calcium release events compared to myocytes from the mdx mice. Abnormal action potentials as assessed by optical mapping mdx were also alleviated by genetic inhibition of ox-CaMK II. Knockout of the NADPH oxidase regulatory sub-unit P 47 Fox normalized elevated ox-CaMK II, repaired intracellular calcium hemostasis and rescued inducible ventricular arrhythmias in the mdx mice. The authors concluded that inhibition of ROS or ox-CaMK II protects against pro-arrhythmic intracellular calcium handling, preventing ventricular arrhythmias in a mouse model of Duchenne muscular dystrophy.                                                 In the next article, Kyohei Marume and Teruo Noguchi and associates examined whether the combination of QRS duration of 120 milliseconds or greater in late gadolinium enhancement is a precise prognostic indicator for the primary endpoint of all cause death and a composite of sudden cardiac death or aborted sudden cardiac death in 531 patients with dilated cardiomyopathy. They also analyzed the association between the combination of late gadolinium enhancement and increased QRS duration in these end points among patients with a class one indication for implantable defibrillator. The author's divided study patients in three groups according to late gadolinium enhancement in QRS duration. Two negative indices that is late gadolinium enhancement negative and narrow QRS, one positive index with either late gadolinium enhancement positive or wide QRS or two positive indices late gadolinium positive and wide QRS and followed them for 3.8 years. Multiple variable Cox regression analysis identified to positive indices as significant predictors of all cause death. A hazard ratio of 4.29 p equals 0.026. Among the 317 patients with a class one indication for ICD, the five year event rate of sudden cardiac death or aborted sudden cardiac death was lowest in the two negative indices groups, 1.4%. With propensity score matching cohorts the two negative indices group had a significant lower event rate of sudden cardiac death or aborted sudden cardiac death than to two other groups hazard ratio 0.2, p equals 0.046.                                                 The authors concluded that the combination of late gadolinium enhancement in wide QRS provides additional prognostic stratification compared to late gadolinium enhancement status alone.                                                 In the next study, Matthew Sulkin and associates examined whether a novel local impedance measurement on an ablation catheter identifies catheter tissue coupling and is predictive of lesion formation. The author's first studied explanted hearts, 10 swine, and then in vivo 10 swine, using an investigational electro anatomical mapping system that measures impedance from an ablation catheter with mini electrodes incorporated into the distal electrode. Rhythmia and Intellanav, Boston Scientific.                                                 Explanted tissue was placed in a warmed 37 degree celsius saline bath mounted on a scale, and the local impedance was measured 15 millimeters away from the tissue to five millimeters of catheter tissue compression at multiple catheter angles. Lesions were created for 31 and 50 watts from 5 to 45 seconds for an N of 70. During in vivo valuation of the local impedance measurements of the myocardium 90 and blood pool 30 were guided by intracardiac ultrasound while operators were blinded to the local impedance data. Lesions were created with 31 and 50 watts for 45 seconds in the ventricle with an n of 72. The local impedance of myocardium, which was 119.7 ohms, was significantly greater than in blood pool 67.6 ohms the p of less than 0.01. Models that incorporate local impedance drop to predict lesion size had better performance that models incorporate force time integral r squared of 0.75 versus r squared of 0.54 and generator impedance drop r squared of 0.2 versus r squared of 0.58. Steam pops displayed a significantly higher starting local impedance and a larger change in local impedance compared to successful RF applications, p less than 0.01.                                                 The authors concluded that local impedance recorded for miniature electrodes provides a valuable measure of catheter tissue coupling and the change in local impedance is predictive of lesion formation during RF ablation.                                                 In the next paper, Boaz Avitall and associates found that the rising impedance recorded from a ring electrode placed two millimeters from the cryoballoon signifies ice formation covering the balloon surface and indicates ice expansion. The authors studied 12 canines in a total of 57 pulmonary veins, which were targeted for isolation. Two cryoapplications were delivered per vein with a minimum of 90 and a maximum 180 second duration. Cryoapplications was terminated upon reaching a 500 ohm change from baseline. Animals recovered 38 plus or minus six days post procedure, and the veins were assessed electrically for isolation. Heart tissue was histological examined. Extra cardiac structures were examined for damage. Pulmonary vein isolation was achieved in 100% of veins if the impedance reached 500 ohms in 90 to 180 seconds. When the final impedance was between 200 and 500 ohms within 180 seconds of freeze time, pulmonary vein isolation was achieved in 86.8%. For impedance of less than 200 ohms pulmonary vein isolation was achieved in 14%. No extra cardiac damage was recorded. The authors found that impedance rise of 500 ohms at less than 90 seconds with a freeze time of 90 seconds resulted in 100% pulmonary vein isolation.                                                 In our final papers Sally-Ann Clur and associates examined left ventricular isovolumetric relaxation time as the potential diagnostic marker for fetal Long QT Syndrome. Left ventricular isovolumetric contraction time, ejection time, left ventricular isovolumetric relaxation time, cycle length, and fetal heart rate were measured using pulse doppler wave forms in fetuses. Time intervals were expressed as percentage of cycle length, and the left ventricular myocardium performance index was calculated. Single measurements were stratified and compared between Long QT Syndrome fetuses and controls. Receiver operator curves were reformed for fetal heart rate in normalized left ventricular isovolumetric relaxation time. A linear mixed effect model including multiple measurements was used to analyze fetal heart rate, the left ventricular iso volume metric relaxation time, and the left ventricular myocardial performance index. There were 33 Long QT fetuses in 469 controls. In Long QT fetuses the left ventricular isovolumetric relaxation time was prolonged in all groups, p less than 0.001, as was the left ventricular isovolumetric relaxation time.                                                 The best cutoff to diagnose Long QT syndrome was the normalized left ventricular isovolumetric relaxation time greater than equal to 11.3 at less than or equal to 20 weeks, giving a sensitivity in 92% and a specificity of 70%. Simultaneous analysis of the normalized left ventricular isovolumetric relaxation time and fetal heart rate improved the sensitivity and specificity of Long QT Syndrome, AUC of 0.96. The normalized left ventricular isovolumetric relaxation time, the left ventricular myocardial performance index, and fetal heart rate trends differed significantly between Long QT Syndrome fetuses and controls throughout gestation.                                                 The authors concluded that left ventricular volumetric relaxation time is Prolonged QT fetuses. Findings of a prolonged normalize left ventricular isovolumetric relaxation time, and sinus bradycardia can improve the prenatal detection of fetal Long QT Syndrome.                                                 That's it for this month, but keep listening. Suraj Kapa will be surveying all journals for the latest topics of interest in our field. Remember to download the podcasts On the Beat. Take it away Suraj. Suraj Kapa:                          Thank you, Paul and welcome back to On the Beat were we will be summarizing hard-hitting articles across the entire electrophysiologic literature. Today we'll be starting within the realm of atrial fibrillation where we're review an article within the realm of anticoagulation and stroke prevention. Quon et al. published in last month's issue of JACC cardiac electrophysiology on anticoagulant use and risk of ischemic stroke and bleeding in patients with secondary atrial fibrillation. It is well known that use of anticoagulation in atrial fibrillation can reduce overall thromboembolic outcomes. However, its role in secondary atrial fibrillation is unclear. Thus, the authors sought to evaluate the effects anticoagulant use on stroke and bleeding risk. Amongst those where atrial fibrillation occurred in the setting of acute coronary syndrome, pulmonary disease, or sepsis. Amongst around 2300 patients evaluated retrospectively there was no evidence of a lower incidence of ischemic stroke among those treated with anticoagulants compared to those who are not.                                                 However, anticoagulation was associated with a higher risk of bleeding in those with new onset AF associated with acute pulmonary disease. The authors suggest as a result that there is unclear overall benefit for long-term anticoagulation in patients with presumed secondary atrial fibrillation. The difficulty in assessing this is how to define secondary atrial fibrillation. However, in many studies patients who developed in the setting of acute illness still had a high risk of developing quote unquote clinically significant AF in long-term follow-up. However, this was not necessarily absolute as many patients not necessarily develop AF that could be considered clinically significant. Thus, the clinical question that arises is: how long should we treat a patient with anticoagulation when they have presumed secondary atrial fibrillation. These data seem to suggest that there may be no net overall benefits. In other words, all-comers with secondary atrial fibrillation should not necessarily be forever treated with anti-coagulation. However, this slightly requires clinical trials to evaluate further.                                                 Next we delve into the realm of cardiac mapping and ablation where we view an article by Gaita et al. entitled 'Very long-term outcome following transcatheter ablation of atrial fibrillation. Are results maintained after 10 years of follow-up?', published in Europace last month. While pulmonary vein isolation is a widely accepted approach for treatment of atrial fibrillation, most reported studies review outcomes in terms of freedom of AF over a relatively short time period, generally two to five years. However longer term follow up is inconsistently reported. Gaita et al. sought to review 10 year outcomes amongst 255 patients undergoing ablation in a single center. They noted 52% remainder arrhythmia-free amongst a mixed cohort of both paroxysmal and persistent patients while 10% progressed to permanent atrial fiBrillation. They found that absence of increases in blood pressure, BMI, and fasting glucose was protective against an arrhythmia recurrence.                                                 These findings suggest that in a relatively small cohort of patients limited to a single center that even long-term outcomes after pulmonary vein isolation are generally quite good, exceeding 50%. However, future freedom from atrial fibrillation is heavily tied to control of other risk factors. In other words, if a patient is going to have poor control of diabetes, blood pressure, or gain weight, the benefit of their pulmonary vein isolation over long-term follow-up is likely less. These data thus highlight both the potential long-term benefit of PVI, but also the importance of counseling patients regarding the need for continued management and control of future and existing risk factors.                                                 Staying within the realm of atrial fibrillation we next review an article by Weng et al. entitled 'Genetic Predisposition, Clinical Risk Factor Burden, and Lifetime Risk of Atrial Fibrillation' published in last month's issue of circulation. The probability of detecting atrial fibrillation in patients based on clinical factors and genetic risk is unknown. Weng et al. sought to clarify whether a combination of clinical and polygenic risk scores could be used to predict risk of developing atrial fibrillation over long-term followup in the Framingham Heart Study. Amongst 4,600 individuals, 580 developed incident atrial fibrillation and had an overall lifetime risk of developing atrial fibrillation of 37%. Those are the lowest risk tertile based on clinical risk factor burden and genetic predisposition had a lifetime risk of 22% versus 48% in the highest. Furthermore, a lower clinical risk factor burden was associated with delayed atrial fibrillation onset. In order to identify patients with atrial fibrillation, before negative sequelae such as stroke occur, patient and physician understanding of risk and monitoring needs is necessary. The fact is that it will be great to identify every single patient who has atrial fibrillation before they have a negative sequela of that atrial fibrillation such as ischemic stroke.                                                 However, performing continuous monitoring of all patients with potential negative sequelae of atrial fibrillation is extraordinarily difficult. The reason is it's excessively costly. We cannot monitor the entire population irrespective of whatever the risk factors are. However, if we're able to identify the highest risk cohorts early on before the atrial fibrillation onsets, this may offer opportunities for use of newer cheaper monitors. The work by Weng et al. suggests one such possible approach combines clinical and polygenic risk scores. Actionability of these data, however, remains to be seen and further validation other cohorts is necessary to clarify generalized ability.                                                 The next article we review is published in last month's issue of the Journal of American College of Cardiology by Lopes at al. entitled 'Digoxin and Mortality in Patients With Atrial Fibrillation. Lopes et al. sought to evaluate the impact of the Digoxin on mortality in patients with atrial fibrillation and the association with the Digoxin serum concentration and heart failure status. They value this association in over 17,000 patients. At baseline 32% were receiving Digoxin. Baseline Digoxin use did not associate with risk of death, but even in these patients a serum concentration of greater than 1.2 nanograms per milliliter was associated with a 56% increase in mortality risk. For each .5 nanogram per milliliter increase in oxygen concentration the hazard ratio increased by 19% for overall mortality. This was irrespective of heart failure status. Furthermore, in patients who are newly started in Digoxin over the follow-up period, the risk and death and sudden death was higher. These data suggests a significant risk associated with Digoxin use for management of atrial fibrillation irrespective of heart failure status. Furthermore, serum valleys above 1.2 require close consideration of dose de-escalation. Whether there is any optimal dose, however, from the study is unclear. These data amongst a host of prior data strongly suggest again strategic use of Digoxin  principally for the management of atrial fibrillation.                                                 Moving on within the realm of atrial fibrillation, we review an article published in last month's issue of Circulation Research by Yan et al. entitled Stress Signaling JNK2 Crosstalk with CaMKII Underlies Enhanced Atrial Arrhythmogenesis. In this more acellular based study the mechanism underlying atrial arrhythmogenesis associated with aging was evaluated. Yan et al. sought to figure out whether the stress response JNK in calcium mediated arrhythmias might contribute to atrial arrhythmogenesis in aged transgenic mouse models. They demonstrated significant increased activity of JNK2 and aging atria, those furthermore associated with rhythmic remodeling. This association was mediated through CaMKII and ryanodine receptor channel function, with activation of the former leading to increased calcium leak mediated by the ladder. This in turn related to increase atrial fibrillation likelihood. Identifying novel targets for atrial fibrillation therapy is critical. Given atrial fibrillation is a complex disease process related to a multitude of risk factors it can be assumed that the contribution of any single factor may be mediated through distinct mechanisms.                                                 Aging in particular as well regarded, but considered to be non-modifiable risk factor for atrial fibrillation. Identifying genes or pathways, the immediate aging associated fibrillation, may take the risk of aging as no longer a non-modifiable thing. The finding of the significance of JNK2 and associate downstream effects with AF risks and aging hearts may hold potential in offering unique therapeutic targets.                                                 Finally, within the realm of atrial fibrillation, we're viewing article by Chen et al. in last month's issue of the Journal of the American Heart Association entitled Association of Atrial Fibrillation With Cognitive Decline and Dementia Over 20 Years: The ARIC-NCS Study. Multiple studies have suggested a significant association between atrial fibrillation risk of dementia. However, these studies have limited time follow-up and were often done and predominantly white patients. Thus, the authors sought to use the data from ARIC, the Atherosclerosis Risk in Communities Neurocognitive Study, to assess the risk of cognitive decline associated with atrial fibrillation. Amongst over 12,000 participants, a quarter of whom are black and half of whom are white, they noted 2100 patients developed atrial fibrillation and 1,150 develop dementia over a 20 year follow up period.                                                 There was a significantly greater risk of cognitive decline amongst those who developed atrial fibrillation. In turn incident atrial fibrillation for the follow-up period was associated with a higher risk of dementia even after adjusting for other clinical and cardiovascular risk factors such as incidents that ischemic stroke. These data further strengthened prior evidence of a direct link between atrial fibrillation and risk of cognitive decline and dementia. Understanding this long-term risk raises the need to additionally identify approaches to prevent this occurrence, which in turn is dependent on understanding the underlying mechanisms. The finding that the risk of cognitive decline dementias independent of ischemic stroke events raises concern that either subclinical micro-embolic events or other factors may be playing a role in this risk and in turn raises question as to how best to prevent them. Until better understood, however, the question of whether the association is causal remains to be seen.                                                 Changing gears yet again, we now delve into the realm of ICDs, pacemakers and CRT. Published in last month, issue of Heart Rhythm Tarakji et al. published a paper entitled 'Unrecognized venous injuries after cardiac implantable electronic device transvenous lead extraction.' Overall risk of transvenous lead extraction includes that of potentially fatal venous laceration. The authors sought to evaluate the incidence of venous injury that may be unrecognized based on microscopic study of extracted leads. Amongst 861 leads obtained from 461 patients they noted 80 leads or almost 9%. Amongst 15% of patients showed segments vein on the lead body, most of which were transmural including the tissue layer. However, in terms of clinical significance, only 1% had need for emergent surgical intervention for clinically significant venous laceration. Risk factors for having the entire vein on the lead included age of lead, ICD leads, and the use of the laser sheath.                                                 These findings suggest that there may be a high incidence of subclinical venous injury after lead extraction though rarely resulting clinically apparent sequelae. As would be expected, venous injury, including transmural removal of portions of the vein traversed by the lead, was more common amongst older leads, which generally more often require laser sheets and ICD leads. The question is however, whether this carries any direct clinical implications. One they may be considered is the potential additive risk of an advancing new lead through the same venous channel, particularly in the setting of potential transmural venous injury that already exists.                                                 Next in last month's issue of Heart Rhythm we review an article by Sharma at al. entitled 'Permanent His-bundle pacing as an alternative to biventricular pacing for cardiac resynchronization therapy: A multicenter experience.' The use of resynchronization therapy for treatment of patients with heart failure and wide QRS has been shown to offer morbidity and mortality benefits. However, many patients maybe non-responders, and recent studies on His bundle pacing of suggested potential clinical benefits. His bundle pacing essentially only requires one pacing catheter attached within the region of the His bundle Sharma et al. sought to evaluate the safety and success rates of His bundle pacing for patients who have either failed standard resynchronization therapy or in whom most tried as a primary intervention. They noted His bundle pacing was successful in 90% of patients with reasonable myocardial and His bundle capture thresholds. Patients in both groups exhibits significant narrowing of QRS morphology and improvement in left ventricular ejection fraction from a mean of 30 to 43%. However, a total of seven patients had lead related complications.                                                 These database on a retrospective analysis of two types of patients, those failing standard biventricular therapy, and those on whom his bundle pacing was attempted as a primary modality suggest overall safety and efficacy in a handful of experienced centers. The promise of His bundle pacing is that a may allow for more effective resynchronization than standard approaches. The high rate of success suggests that His bundle pacing maybe both safe and reasonable to pursue. However randomized trials across more centers are needed to fully prove its benefit, particularly as a primary modality of treatments.                                                 Next we review ICDs and chronic kidney disease. In last month's issue of JAMA cardiology by Bansal at al. entitled 'Long-term Outcomes Associated With Implantable Cardioverter Defibrillator in Adults With Chronic Kidney Disease.' While the benefit of ICDs in patients with low EF is widely recognized, modifying factors that may increase risk of death are not as well defined. These include things like advanced age and chronic kidney disease. Bansal et al. sought to evaluate long-term outcomes and ICD therapy in patients with chronic kidney disease. In retrospective study of almost 5,900 ambulatory patients amongst whom 1550 had an ICD, they found no difference in all cause mortality. However, ICD placement was associated with an increased risk of subsequent hospitalization due to heart failure or any cause hospitalization.                                                 In light of recent studies such as DANISH the robust sense of ICD benefit is being questioned. One of the thoughts for the absence of similar benefit to prior studies lies in the improving care of ambulatory heart failure patients. In patients with chronic kidney disease several questions rises to the risk with ICD, including infectious risk in dialysis patients and the concomitant mortality risk with renal dysfunction. The author suggested in retrospective study, no incremental benefit of ICDs in patients with chronic kidney disease and perhaps some element of added risk is related to hospitalization. However, this study has several limitations. It is retrospective and many patients received ICDs may have been perceived to be sicker in some way. Thus care must be taken in interpretation, but consideration of randomized studies to adjudicate benefit are likely necessary.                                                 Finally, within the realm of devices, we reviewed an article by Tayal et al. entitled "Cardiac Resynchronization Therapy in Patients With Heart Failure and Narrow QRS Complexes.' publishing the Journal of American College of Cardiology last month. Several parameters have been stressed to identify benefit of resynchronization therapy in patients with wide QRS include cross correlation analysis with tissue doppler imaging. However, many patients may have evidence in mechanical dyssynchrony even in the absence of an apparent wide QRS thus Tayal et al. sought to evaluate the benefit of resynchronization therapy amongst 807 patients with heart failure and a narrow QRS mean criteria in a randomized study. Of the 807 46% had delayed mechanical activation. Those without delay mechanical activation had underwent we standardization therapy and were associated with worse overall outcomes likely due to new delayed mechanical activation potentially related to CRT pacing. These data support the absence of a role for resynchronization therapy in patients with a narrow QRS. This is expected as resynchronization therapy likely offers the most benefit in patients with mechanical dyssynchrony that results from electrical dyssynchrony.                                                 Since by its very nature resynchronization therapy relies on non physiologic cardiac pacing thus compared to normal cardiac activation the nature of resynchronization pacing is desynchronization. These data support the absence of a role for resynchronization therapy in patients with heart failure and narrow QRS complexes.                                                 Moving on to cellular electrophysiology we review an article by Kozasa et al. published in last month's issue of Journal of Physiology entitled 'HCN4 pacemaker channels attenuate the parasympathetic response and stabilize the spontaneous firing of the sinoatrial node.' Heart rate is controlled by an interplay between sympathetic and parasympathetic components. In turn HCN4 abnormalities have been implicated in congenital sick sinus syndrome. The authors sought to clarify the contribution of HCN4 to sinus node autonomic regulation. They created a novel gain-of-function mouse where the HCN4 activity could be modulating from zero to three times normal. They then evaluated ambulatory heart-rate variability and responsive heart rate to vagus nerve stimulation. They found HCN4 over-expression did not increase heart rate, but attenuated heart-rate variability. It also attenuated bradycardic response to vagus nerve stimulation. Knockdown of HCN4 in turn lead to sinus arrhythmia and enhanced parasympathetic response. These data suggest HCN4 attenuates sinus node response to vagal stimuli thus stabilizing spontaneous firing of the node. The clinical application of this remain to be seen but are maybe important in that they highlight a mechanism for a heretofore poorly understood mechanism for how exactly HCN4 abnormalities may lead to sick sinus syndrome.                                                 Within the realm of ventricular arrhythmias we highlighted a number of articles published this past month. The first article we review was published in last month's issue of JACC clinical electrophysiology, entitled characterization of the electrode atomic substrate and cardiac sarcoidosis: correlation with imaging findings of scarring inflammation published by [inaudible 00:41:40] et al. In patients with cardiac sarcoidosis one of the questions is how to define the electronic atomic substrate, particularly before we entered the electrophysiology laboratory. Both active inflammation and replacement fibrosis maybe be seen in patients. The authors evaluated in 42 patients with cardiac sarcoidosis, the association between an abnormal electrograms and cardiac imaging findings including PET and Computed Tomography, as well as Cardiac MRI. They noted that amongst these 40 patients, a total of 21,000 electrograms were obtained, and a total of 19% of these were classified as abnormal. Most of the abnormalities occurred in the basal paravalvular segments and intraventricular septum. They further noted that many of these abnormalities in terms of electrograms were located outside the low voltage areas, particularly as it relates to fractionation. In about 90% of patients they notice late gadolinium enhancements and they noted abnormal FDG uptakes suggesting active inflammation in about 48%.                                                 However, it should be noted that only 29 of the 42 patients underwent cardiac imaging. Segments with abnormal electrograms tended to have more late gadolinium enhancement evidence scar transmurality, and also they noted that the association of abnormal PET scan did not necessarily occur with abnormal electrograms. Thus, they concluded that in patients with cardiac sarcoidosis and ventricular tachycardia pre-procedural imaging with cardiac MRI could be useful in detecting electroanatomic map abnormalities that may in turn be potential targets for substrate ablation. However, they were more likely associated with more scar transmurality and lower degrees of inflammation on PET scanning. These data are important in that they highlight potential non-invasive means by which to understand where substrate might occur in patients with the cardiac sarcoidosis. It is well recognized that cardiac sarcoidosis is associated with increased risk of ventricular arrhythmias. These risks have increased ventricular arrhythmias, might be targetable with ablation. Newer therapies might even offer non invasive means by which to perform ablation in patients best. Thus if we could identify non based on mechanisms of identifying the substrate, this will be even more critical.                                                 The critical findings of this particular paper lie in noting that most of the abnormalities still is in intra ventricular sePtum in basal segments, and also that it is MRI in late gadolinium enhancement and associates more with the abnormal electrograms. Interestingly, the absence of inflammation correlating with the presence of more abnormal electrograms suggests that it is not so much the act of inflammation as being reflected in the endocardial map, but the existence of scar.                                                 Next, again within JACC clinical electrophysiology we review an article by Porta-Sánchez et al. entitled 'Multicenter Study of Ischemic Ventricular Tachycardia Ablation With Decrement Evoked Potential Mapping With Extra Stimulus.' The authors sought to conduct a multicenter study of decrement evoked potential base functional tech ventricular tachycardia substrate modification to see if such mechanistic and physiologic strategies could result in reduction in VT burden. It is noted that really only a fraction of the myocardium in what we presume to be substrate based on the presence of low voltage areas are actually involved in the initiation and perpetuation of VT. Thus if we can identify the critical areas within the presumed substrate for ablation, this would be even a better way of potentially honing in on our targets. They included 20 consecutive patients with ischemic cardiomyopathy. During substrate mapping fractionated late potentials were targeted and an extra stimulus was provided to determine which display decrements. All patients underwent DEEP focus ablation with elimination being correlated with VT non-inducibility after radio-frequency ablation. Patients were predominantly male, and they noted that the specificity of these decrement evoked potentials to detect the cardiac isthmus for VT was better than that of using late potentials alone. They noted 15 of 20 patients were free of any VT after ablation of these targets over six months of follow-up, and there was a strong reduction in VT burden compared to six months pre ablation.                                                 They concluded that detriment evoked potential based strategies towards ablation for ventricular tachycardia might identify the functional substrate and those areas most critical to ablation. They in turn regarded that by its physiologic nature it offers greater access to folks to ablation therapies.                                                 This publication is important in that it highlights another means by which we can better hone in on the most critical regions for substrate evaluation in patients with ventricular tachycardia. The fact is more extensive ablation is not necessarily better and might result in increased risk of harm if we think about the potential effects of longer ablations or more ablation lesions. Thus if we could identify ways of only targeting those areas that are most critical to the VT circuits, we could perhaps short and ablation procedural time, allow for novel ways of approaching targeted ablation with limited amounts of ablation performed, or perhaps even improve overall VT outcomes by knowing the areas that are most critical to ensure adequate ablation therapy provided. However, we need to understand that this is still a limited number of patients evaluated in a non randomized manner. Thus whether or not more extensive ablation performed might have been better is as of yet unclear                                                 Staying within the realm of ventricular tachycardia we review an article published in last month's issue of Heart Rhythm by Winterfield et al. entitled the 'Impact of ventricular tachycardia ablation on healthcare utilization.' Catheter ablation of atrial tachycardia has been well accepted to reduce recurrent shocks in patients with ICDs. However, this is a potentially costly procedure, and thus effect on overall long-term health care utilization remains to be seen. The authors sought to evaluate in a large scale real world retrospective study the effect of VT ablation on overall medical expenditures in healthcare utilization. A total 523 patients met study inclusion criteria from the market scan database. After VT ablation median annual cardiac rhythm related medical expenditures actually decreased by over $5,000. Moreover the percentage of patients with at least one cardiac rhythm related hospitalization an ER visit decreased from 53 and 41% before ablation respectively, to 28 and 26% after ablation. Similar changes we're seeing in number of all cause hospitalizations and ER visits. During the year before VT ablation interestingly there was an increasing rate of healthcare resource utilization, but a drastic slowing after ablation.                                                 These data suggests that catheter ablation may lead to reduced hospitalization in overall healthcare utilization. The importance of these findings lies in understanding why we do the things we do. We can provide a number of therapies to patients, but we seek two different effects. One is the individual effect of improving their particular health. The second thing is trying to avoid increasing healthcare expenditures on a population level and making sure resources are utilized. If we can reduce recurrent hospitalizations and overall healthcare expenditure in patients by providing a therapy in addition to provide individual benefit, this is the optimal situation. These data suggests that VT ablation might provide such a benefits, that in fact it reduces overall healthcare utilization while improving overall outcomes.                                                 Next and finally within the realm of ventricular arrhythmias, we review more on the basic side the role of Titin cardiomyopathy leads to altered mitochondrial energetics, increased fibrosis and long-term life-threatening arrhythmias, published by Verdonschot et al. in last month's issue of European Heart Journal. It is known now that truncating Titin variants might be the most prevalent genetic cause of dilated cardiomyopathy. Thus, the authors sought to study clinical parameters and long term outcomes related to Titin abnormalities in dilated cardiomyopathy. They reviewed 303 consecutive and extensively phenotype dilated cardiomyopathy patients who underwent cardiac imaging, Holter monitoring, and endomyocardial biopsy and in turn also underwent DNA sequencing of 47 cardiomyopathy associated genes. 13% of these patients had Titin abnormalities. Over long-term followup they noted that these patients had increased ventricular arrhythmias compared to other types of dilated cardiomyopathy, but interestingly, they had similar survival rates. Arrhythmias in those Titin abnormal patients were most prominent in those who were subjected to an additional environmental trigger, including viral infection, cardiac inflammation, other systemic disease or toxic exposure. They also noted the cardiac mass was relatively reduced in titan admirable patients.                                                 They felt that all components of the mitochondrial electron transport chain we're simply up-regulated in Titin abnormal patients during RNA sequencing and interstitial fibrosis was also augmented. As a result, they concluded that Titin variant associated dilated cardiomyopathy was associated with an increased risk of ventricular arrhythmias, and also with more interstitial fibrosis. For a long time we have reviewed all non ischemic cardiomyopathy as essentially equal. However, more recent data has suggested that we can actually hone in on the cause. In turn, if we hone in on the cause, we might be able to understand the effects of specific therapies for ventricular arrhythmias based on that underlying cause. Patchy fibrosis might not be as amenable, for example, to ablation as discreet substrate that we might see in infarct related VT. Understanding the relative benefit in very specific types of myopathies might hold benefit in understanding how to, one, risk stratify these patients, and two, understand what type of therapy, whether pharmacologic or ablative, might result in greatest benefit to the patients.                                                 Changing gears entirely now to the role of genetics, we review multiple articles in various genetic syndromes published this past month. First, we reviewed an article by Providência et al. published in the last month's issue of heart entitled 'Impact of QTc formulae in the prevalence of short corrected QT interval and impact on probability and diagnosis of short QT syndrome.' The authors sought to assess the overall prevalence of short corrected QT intervals and the impact on diagnosis of short QT syndrome using different methods for correcting the QT interval. In this observational study they reviewed the sudden cardiac death screening of risk factors cohorts. They then applied multiple different correction formulae to the ECGs. They noted that the prevalence of individuals with the QTc less than 330 and 320 was extremely low, namely less than .07 and .02% respectively. They were also more frequently identified using the Framingham correction. The different QTc correction formulae could lead to a shift of anywhere from 5 to 10% of individuals in the cohort overall.                                                 They further noted, that based on consensus criteria, instead of 12 individuals diagnosed with short gut syndrome using the Bazett equation, a different number of individuals would have met diagnostic criteria with other formulae, 11 using Fridericia, 9 with Hodges, and 16 using the Framingham equation. Thus, they noted that overall the prevalence of short QT syndrome exceedingly low and an apparently healthy adult population. However, reclassification as meeting criteria might be heavily dependent on which QT correction formula is used. The importance of these findings is that not all QTs are created equal.                                                 Depending on how you compute the QT interval in which formula to use may affect how you actually risk characterize a patient. Unfortunately, these data do not necessarily tell us which is the right formula, but this highlights that it might be relevant to in the future evaluate the role of different formulae and identifying which is the most necessary to classify a patient.                                                 Moving on to an article published in last month's issue of the journal of clinical investigation by Chai et al. we review an article entitled 'Physiological genomics identifies genetic modifiers of Long QT Syndrome type 2 severity.' Congenital Long QT Syndrome is a very well recognized, inherited channelopathy associated life-threatening arrhythmias. LQTS type 2 is specifically caused by mutations in casein to encoding the potassium channel hERG. However, even with the mutation not all patients exhibit the same phenotype. Namely some patients are more at risk of life threatening arrhythmias in spite of having the same mutation as others who do not exhibit the same severity phenotype. The authors sought to evaluate whether specific modifiable factors within the remaining genetic code might be modifying the existing mutation. Thus, they sought to identify contributors to variable expressivity in an LQT 2 family by using induced pluripotent stem cell derived cardiomyocytes and whole exome sequencing in a synergistic manner.                                                 They found that patients with severely effected LQT 2 displayed prolonged action potentials compare to sales from mildly effected first-degree relatives. Furthermore, stem cells derived from patients were different in terms of how much L-type calcium current they exhibited. They noted that whole exome sequencing identified variants of KCNK17 and the GTP-binding protein REM2 in those patients with more severe phenotypes in whom greater L-type calcium current was seen. This suggests that abnormalities or even polymorphisms in other genes might be modifying the risk attributed to by mutations in the primary gene. This showcases the power of combining complimentary physiological and genomic analysis to identify genetic modifiers and potential therapeutic targets of a monogenic disorder. This is extraordinarily critical as we understand on one level that when we sequence a monogenic disorder that there might exist variants of uncertain significance, namely they have not been classified as disease causing, but could be. In turn, we also recognize that mutations in a family might effect different relatives differently. However, why this is has been relatively unclear.                                                 If we can understand and identify those patients who are most at risk of dangerous abnormal rhythms, this will be useful in how much to follow them, and what type of therapy to use in them. The fact that other genes might modify the risk even in the absence of specific mutations, suggests that novel approaches to characterizing the risk might help for the risk modified patients classification in general. Clinical use, however, remains to be seen.                                                 Moving on from long QT, we evaluate 'The Diagnostic Yield of Brugada Syndrome After Sudden Death With Normal Autopsy' noted in last month's issue of the Journal of American College of Cardiology and published by Papadakis et al. It is well known, the negative autopsies are not uncommon in patients, however, families might be wondering how at risk they are. Thus, the authors sought to assess the impact of systematic ajmaline provocation testing using high right precordial leads on the diagnostic yield Brugada syndrome in a large cohort of Sudden Arrhythmic Death syndrome families. Amongst 303 families affected by Sudden Arrhythmic Death Syndrome evaluation was done to determine whether or not there was a genetic inherited channelopathy cause. An inherited cardiac disease was diagnosed in 42% of the families and 22% of relatives Brugada syndrome was the most prevalent diagnosis overall amongst 28% of families. Ajmaline testing was required, however, to unmask the Brugada Syndrome in 97% of diagnosed individuals. Furthermore, they use of high right precordial leads showed a 16% incremental diagnostic yield of ajmaline testing for diagnosing Brugada syndrome.                                                 They further noted that a spontaneous type 1 regard or pattern or a clinically significant rhythmic event developed in 17% of these concealed regardless syndrome patients. The authors concluded the systematic use of ajmaline testing with high right precordial leads increases the yield of Brugada Syndrome testing in Sudden Arrhythmic Death Syndrome families. Furthermore, they noted that assessments should be performed in expert centers or patients could also be counseled appropriately. These findings are important and one of the big questions always becomes how aggressively to test family members of patients or of deceased individuals who experienced sudden arrhythmic death. Many of these patients have negative autopsies, and genetic autopsy might not be possible due to lack of tissue or blood products that can be adequately tested.                                                 The data here suggest that amongst a group of 303 sudden arrhythmic death, families that Brugada Syndrome is by far the most frequent diagnosis. If an inherited cardiac disease was identified. In turn, it is not ECG alone or echo alone that helps identify them, but requires drug provocation testing in addition to different electrode placements. Whether or not this will consistently offer benefit in patients in general or my result in overcalling remains to be seen next within the realm of genetic predisposition.                                                 We view an area where we don't know if there's a genetic predisposition in article published by Tester et al. entitled Cardiac Genetic Predisposition in Sudden Infant Death Syndrome in last month's issue of the journal of american college of cardiology. Sudden Infant Death Syndrome is the leading cause of post-neonatal mortality and genetic heart diseases might underlie some cases of SIDS. Thus the authors sought to determine the spectrum and prevalence of genetic heart disease associated mutations as a potential monogenic basis for Sudden Infant Death Syndrome. They study the largest cohort to date of unrelated SIDS cases, including a total of 419 individuals who underwent whole exome sequencing and targeted analysis for 90 genetic heart disease susceptibility genes. Overall, 12.6% of these cases had at least one potentially informative genetic heart disease associated variants. The yield was higher in those mixed European ancestry than those of European ancestry.                                                 Infants older than four months were more likely to host a potentially informative gene. Furthermore, they noted that only 18 of the 419 SIDS cases hold a [inaudible 01:01:26] or likely pathogenic variant. So in other words, only 4% of cases really had a variant that they could say was distinctly pathogenic or likely pathogenic. Thus, overall, the minority of SIDS cases have potentially informative variant in genetic heart disease susceptibility gene, and these individuals were mostly in the 4 to 12 month age group. Also, only 4% of cases had immediately clinically actionable variance, namely a variant, which is well recognized as pathogenic and where we could actually say that a specific therapy might have had some effect. These findings can have major implications for how best to investigate SIDS cases in families. It might suggest that SIDS cases where the individual was older, nearly 4 to 12 months of age might have a greater yield in terms of identifying variance.                                                 While this might not affect the deceased in fit, it might affect, families are planning on having another child in whom a variant can be identified.                                                 Finally, within the realm of genetics, we review an article published in last month's issue of Science Advances by Huang. et al. entitled 'Mechanisms of KCNQ1 Channel Dysfunction in Long QT Syndrome Involving Voltage Sensor Domain Mutations'. Mutations that induce loss of function of human KCNQ1 underlie the Long QT Syndrome type 1. While hundreds of mutations have been identified the molecular mechanism by which they result in impaired function are not as well understood. The authors sought to investigate impact of 51 specific variants located within the voltage sensor domain and emphasized effect on cell surface expression, protein folding, and structure. For each variant efficiency of trafficking of the plasma membrane, impact of proteasome inhibition, and protein stability were evaluated. They noted that more than half of the loss of function mutations were seen to destabilized structure of the voltage sensor domain, generally accompanied by mistrafficking and degradation by the proteasome.                                                 They also noted that five of the folding defective Long QT Syndrome mutant sites were located in the S0 helix, where they tend to interact with a number of other loss of function mutation sites in other segments of the voltage sensor domain. They suggested these observations reveal a critical role for the S0 helix as a central scaffold to help organize and stabilized KCNQ1 overall. They also note the importance of these findings is that mutation-induced destabilization of membrane proteins may be a more common cause of disease functioning in humans. The importance of these findings lies in better understanding why specific mutations lead to appa

25 August 2015: In this Skinpod episode, Dr. Adaobi Nwaneshiudu, University of Chicago, discusses her Research Techniques Made Simple article on confocal microscopy.

Alessandro Cometta, Zeiss Milano, Italy speaks on "Setup and technology of a confocal microscope". This movie has been recorded at ICGEB Trieste.

Living cells and organisms often suffer from the high light intensities that are used in conventional imaging. Light sheet microscopy reduces phototoxic effects and bleaching, by only illuminating a specimen in a single plane at a time whilst the signal is detected in a perpendicular direction. In combination with high-speed cameras for image acquisition, light sheet microscopy is a very gentle method to observe fast biological processes in sensitive organisms over an extended time period. By moving the sample along this plane, specimens are optically sectioned and imaged in 3D. These exciting possibilities led Nature Methods to cite light sheet imaging as their Method of the Year for 2014. Learn more at http://bitesizebio.com/webinar/24339/the-best-of-both-worlds-combining-light-sheet-and-confocal-microscopy/

Confocal microscopy is known for its capability to produce exceptional 3D images, even in living tissue. At the same time, it is a powerful spectroscopic tool, facilitating fluores- cence methods such as Fluorescence Correlation Spectroscopy (FCS) or single-molecule Förster Resonance Energy Transfer (FRET). It is heavily used to investigate a wide range of biological problems. This holds true especially for protein properties such as ligand binding, complex formation, conformational changes, or the intracellular distribution of the species in question. In this work, I will describe the assembly of two instruments: The first is a multi- parameter fluorescence detection (MFD) setup. It is a purely spectroscopic tool that offers the capability to characterize a fluorescent molecule, delivering information like fluorescence lifetime, anisotropy or the speed of its diffusion in free solution. When the molecule of interest is labelled with two fluorophores, additional information, like the energy transfer in-between them, becomes accessible and the correct distance between these two fluorophores can be calculated. If the two fluorophores are attached to different molecules, the MFD setup can detect interactions of these molecules in the range from pM up to μM with the help of Fluorescence Cross-Correlation Spectroscopy (FCCS). The second instrument, a stimulated emission depletion setup, combines some of the mentioned techniques, like FCS, with the superior image capability of a confocal micro- scope. One particular problem of fluorescent microscopes, though, is that image resolution is always restricted to the diffraction limit of the wavelength of the laser light. The STED setup utilizes the effect of stimulated emission in order to circumvent the diffraction bar- rier and allows images with a three-fold resolution increase, down to 75nm. These two setups will be used for several applications: The first will be centered around the molecular conformation of proteins, which are sensitive to the nature of the aqueous environment. In particular, the presence of ions can stabilize or destabilize (denature) protein secondary structure. The underlying mechanisms of these actions are still not fully understood. I will apply single-pair FRET to a small 29 amino acid long model peptide to investigate unfolding mechanisms of different unfolding reagents from the Hofmeister series, like sodium perchlorate or guanidinium chloride. The results show that certain salts, which are commonly summarized as denaturing agents, achieve the unfolding by either collapsing the molecule to a compressed state or swelling it to a denatured state. 7 The second application of the MFD setup is the investigation of the enhanced green fluorescent protein (EGFP). Although highly used in biochemistry and biophysics, for example to read out the expression level of genes, it is still not fully known what percentage of EGFP is fluorescent. This lack of knowledge makes it nearly impossible to make quantitative statements. With the help of FCCS, it is shown that the folding efficiencies range from 40 − 90%, depending on the environment of the fluorescent protein and which particular mutant is used. In the third application, the focus will be shifted to nucleation- and polymerization- behavior of actin. The actin cytoskeleton is a central mediator of cellular morphogenesis, and rapid actin reorganization drives essential processes such as cell migration and cell di- vision. In order to compare results of confocal spectroscopy methods with well-established bulk essays, we successfully ported the standard bulk essay to the confocal microscope, allowing for the first time to follow the decrease of monomer concentration and appear- ance of small filaments. Also, the formation of dimers or other small oligomers below the critical concentration is proven for the first time, using FCCS. The last application will utilize the STED setup in order to carry out the first steps towards the investigation of the nucleation and branching behavior of actin in cooperation with the actin related protein 2/3 (ARP2/3). This protein complex preferentially attaches to actin filaments that are located at the leading edge of a cell and forms branched filamentous structures. The exact conditions under which this process occurs are not well characterized. This part of the work will deal with the steps that are necessary to follow the polymerization process on the STED setup.

In the in vitro production of embryos in humans and animals it is aimed to produce embryos of good quality in order to reach a high pregnancy rate after the transfer on a recipient. Nevertheless, data until 2007 show that in Europe the pregnancy rate after the transfer of human IVF embryos was only 33% (de Mouzon et al., 2012). Recently time-lapse imaging of early embryonic cleavage was found to be a helpful and non-invasive tool to predict the developmental capacity of embryos and select embryos of good quality (Wong et al., 2010, Sugimura et al., 2012). As the morphokinetic parameters of the first and second cleavage were the most predictive values, the fate of an embryo seems to be, at least partly, already determined very early in embryogenesis. This determination of the developmental competence might even go back further namely until oocyte maturation. In this experiment we used bovine embryos as an animal model to study the reasons for success and failure of mitotic cleavage during early embryo development. First a live monitoring system for the observation of bovine embryos was applied in order to search for the values that are highly predictable for the developmental competence to the blastocyst stage. To consider the effect of the oocyte maturation onto the further development, we observed embryos from oocytes after in vitro (n=398) versus in vivo maturation (n=143). In average embryos that developed to the blastocyst stage showed an earlier timing of the first, second and third cleavage than embryos that arrested (p

Purpose of review Confocal laser endomicroscopy (CLE) is a novel, noninvasive technique used to obtain microanatomical images of the inner lining of hollow organs. It has been used in a variety of clinical specialties to aid in the diagnosis and treatment planning of inflammatory and neoplastic processes. Our intent is to provide an up-to-date review of the literature in the setting of head and neck diseases as well as describing our own initial results and areas of future research. Recent findings With increasing experience using CLE in the upper aerodigestive tract (UADT), evidence is mounting that this method can be a useful adjunct to standard endoscopy and other diagnostic techniques. Recent publications have shown that by using CLE, microanatomical structures of healthy and diseased mucosa can easily be identified, allowing for a differentiation of dysplastic/neoplastic and benign mucosal lesions. Standardized diagnostic protocols as well as clinically relevant classification systems for the UADT have not yet been described. Summary CLE is an imaging modality that allows real-time visualization of mucosal cellular architecture and other histologic characteristics. First reports on its use in the UADT have yielded promising results, but the true value of this method is yet to be determined.

Rare earth ions are nowadays regarded as one of the most versatile luminescent systems capable of producing light in a wide spectral range covering from the depth UV up to the medium infrared with a quantum efficiency almost reaching 100%. They, indeed, have been the basis of past solid state lasers that still play a relevant role in medicine, industry and science. During the last few years, rare earth ions, through its luminescence, are being used as optical probes capable of giving us information at the micro and sub-micrometric scale when combined with high resolution confocal fluorescence microscopy. In this talk Professor Daniel Jaque (Universidad Antonoma de Madrid) will briefly explain the basic principles and mechanisms of rare earth fluorescence, paying special attention to the information that fluorescence provides about the ion's environment. He will show some very simple examples about how the presence of rare earth ions opens an unexplored window to understand and control the physics of micro luminescent systems. The examples shown cover from material science (fluorescence imaging of ultrafast laser written photonic devices in crystals and chalcogenide micro-spheres) up to live sciences (cancer cell imaging).

Kupffer cells, the resident macrophages of the liver, play an important role in host defense and immune system. Moreover, they are also involved in several pathological conditions, like the hepatic ischemia/reperfusion injury. The transcription factor NF-kB is activated during this event. However, to date it was not possible to evaluate the consequence of this upregulation, as NF-kB possesses both detrimental and beneficial properties, regarding of the liver cell type affected. An activation in Kupffer cells is thought to lead to an increased inflammatory response. This hypothesis could not be proven in vivo, as a selective inhibition of NF-kB in Kupffer cells was not possible due to technical difficulties. In this work, solid nanoparticles made of gelatin were chosen to deliver NF-kB inhibiting decoy oligonucleotides exclusively to Kupffer cells in order to block the activation of NF-kB. Confocal scanning laser microscopy showed selective uptake of gelatin nanoparticles into the Kupffer cells without affecting hepatocytes. An increase in NF-kB binding activity during postischemic reperfusion could be diminished by the delivery of decoy oligonucleotides to the resident liver macrophages. In addition, a rise in TNF-alpha mRNA expression assessed by real time RT-PCR was also reduced, thus providing evidence for the effectiveness of this selective targeting. Thus, this work established a novel carrier for a specific Kupffer cell targeting.

The potential of two small poly-L-lysines ( sPLLs), low molecular weight sPLL ( LMW-L) containing 7 - 30 lysine residues and L18 with 18 lysine repeats, to enhance the efficiency of liposome-mediated gene transfer ( GT) with cationic lipid DOCSPER {[}1,3- dioleoyloxy- 2-( N-5-carbamoyl-spermine)-propane] in vascular smooth muscle cells ( SMCs) was investigated. Dynamic light scattering was used for determination of particle size. Confocal microscopy was applied for colocalization studies of sPLLs and plasmid DNA inside cells. GT was performed in proliferating and quiescent primary porcine SMCs in vitro and in vivo in porcine femoral arteries. At low ionic strength, sPLLs formed small complexes with DNA ( 50 100 nm). At high ionic strength, large complexes ( 11 mu m) were observed without any significant differences in particle size between lipoplexes ( DOCSPER/ DNA) and lipopolyplexes ( DOCSPER/ sPLL/ DNA). Both sPLLs were colocalized with DNA inside cells 24 h after transfection, protecting DNA against degradation. DOCSPER/ sPLL/ DNA formulations enhanced GT in vitro up to 5- fold, in a porcine model using local periadventitial application up to 1.5- fold. Both sPLLs significantly increased liposome- mediated GT. Poly-L-lysine L18 was superior to LMW-L since it enabled maximal GT at a 10-fold lower concentration. Thus, sPLLs may serve as enhancers for GT applications in SMCs in vitro and in vivo using local delivery. Copyright (c) 2007 S. Karger AG, Basel.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.21.053603v1?rss=1 Authors: Barkley, C., Serra, R., Nguyen, K., Peters, S. B. Abstract: Transforming growth factor {beta} (TGF{beta}) plays an important role in tooth morphogenesis and mineralization. Our laboratory established a mouse model in which Tgfbr2 was conditionally deleted in the dental pulp (DP) mesenchyme using an Osterix promoter-driven Cre recombinase (Tgfbr2cko). These mice survived postnatally, but had significant defects in bones and teeth, including reduced mineralization and short roots. H&E staining revealed reduced axon-like structures in the mutant mice. Reporter imaging demonstrated that Osterix-Cre activity was localized within the tooth and was active in the DP and derivatives, but not in neurons. Previous research has established that paracrine signals from the dental pulp attract trigeminal axons toward and into the tooth during postnatal development, yet very little is known about the signals that regulate tooth innervation. Immunofluorescent staining for a neuronal marker, {beta}3 tubulin, was performed on serial cryosections from control and mutant molars at two different postnatal stages. Confocal imaging and pixel quantification of {beta}3 tubulin demonstrated reduced innervation in P7 and P24 Tgfbr2cko first molars compared to controls, indicating that the signals necessary to promote neurite outgrowth were disrupted by Tgfbr2 deletion. Quantitative real time PCR showed that the mRNA expression levels of several neuronal genes were reduced. Lastly, trigeminal neurons were co-cultured atop Transwell filters overlying primary Tgfbr2f/f DP cells. Tgfbr2 in the DP was deleted with an adenovirus expressing Cre recombinase. Confocal imaging of axons through the filter pores showed increased axonal sprouting from neurons cultured in the presence of Tgfbr2-positive DP cells compared to neurons cultured alone. Further, axon sprouting was reduced when Tgfbr2 was knocked down in the DP cells. These results indicate that Tgfbr2 in the DP mesenchyme regulates paracrine signals that guide sensory innervation of the tooth. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.04.19.048926v1?rss=1 Authors: McCarron, M. E., Weinberg, R. L., Izzi, J. M., Queen, S. E., Misra, S. L., Russakoff, D. B., Oakley, J., Mankowski, J. Abstract: Purpose: To characterize corneal subbasal nerve plexus morphologic features using in vivo corneal confocal microscopy (IVCM) in normal and SIV-infected macaques and to implement automated assessments using novel deep learning-based methods customized for macaque studies. Methods: In vivo corneal confocal microscopy images were collected from both male and female age-matched specific-pathogen free rhesus and pigtailed macaques housed at the Johns Hopkins University breeding colony using the Heidelberg HRTIII with Rostock Corneal Module. We also obtained repeat IVCM images of 12 SIV-infected animals including pre-infection and 10 day post-SIV infection time-points. All IVCM images were analyzed using a novel deep convolutional neural network architecture developed specifically for macaque studies. Results: Deep learning-based segmentation of subbasal nerves in IVCM images from macaques demonstrated that corneal nerve fiber length (CNFL) and fractal dimension measurements did not differ between species, but pigtailed macaques had significantly higher baseline corneal nerve fiber tortuosity than rhesus macaques (P = 0.005). Neither sex nor age of macaques was associated with differences in any of the assessed corneal subbasal nerve parameters. In the SIV/macaque model of HIV, acute SIV infection induced significant decreases in both corneal nerve fiber length and fractal dimension (P= 0.01 and P= 0.008 respectively). Conclusions: The combination of IVCM and objective, robust, and rapid deep-learning analysis serves as a powerful noninvasive research and clinical tool to track sensory nerve damage, enabling early detection of neuropathy. Adapting the deep-learning analyses to human corneal nerve assessments will refine our ability to predict and monitor damage to small sensory nerve fibers in a number of clinical settings including HIV, multiple sclerosis, diabetes, and chemotherapeutic neurotoxicity. Copy rights belong to original authors. Visit the link for more info