Podcasts about EC50

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: A primer on why computational predictive toxicology is hard, published by Abhishaike Mahajan on August 19, 2024 on LessWrong. Introduction There are now (claimed) foundation models for protein sequences, DNA sequences, RNA sequences, molecules, scRNA-seq, chromatin accessibility, pathology slides, medical images, electronic health records, and clinical free-text. It's a dizzying rate of progress. But there's a few problems in biology that, interestingly enough, have evaded a similar level of ML progress, despite there seemingly being all the necessary conditions to achieve it. Toxicology is one of those problems. This isn't a new insight, it was called out in one of Derek Lowe's posts, where he said: There are no existing AI/ML systems that mitigate clinical failure risks due to target choice or toxicology. He also repeats it in a more recent post: '…the most badly needed improvements in drug discovery are in the exact areas that are most resistant to AI and machine learning techniques. By which I mean target selection and predictive toxicology.' Pat Walters also goes into the subject with much more depth, emphasizing how difficult the whole field is. As someone who isn't familiar at all with the area of predictive toxicology, that immediately felt strange. Why such little progress? It can't be that hard, right? Unlike drug development, where you're trying to precisely hit some key molecular mechanism, assessing toxicity almost feels…brutish in nature. Something that's as clear as day, easy to spot out with eyes, easier still to do with a computer trained to look for it. Of course, there will be some stragglers that leak through this filtering, but it should be minimal. Obviously a hard problem in its own right, but why isn't it close to being solved? What's up with this field? Some background One may naturally assume that there is a well-established definition of toxicity, a standard blanket definition to delineate between things that are and aren't toxic. While there are terms such as LD50, LC50, EC50, and IC50, used to explain the degree by which something is toxic, they are an immense oversimplification. When we say a substance is "toxic," there's usually a lot of follow-up questions. Is it toxic at any dose? Only above a certain threshold? Is it toxic for everyone, or just for certain susceptible individuals (as we'll discuss later)? The relationship between dose and toxicity is not always linear, and can vary depending on the route of exposure, the duration of exposure, and individual susceptibility factors. A dose that causes no adverse effects when consumed orally might be highly toxic if inhaled or injected. And a dose that is well-tolerated with acute exposure might cause serious harm over longer periods of chronic exposure. The very definition of an "adverse effect" resulting from toxicity is not always clear-cut either. Some drug side effects, like mild nausea or headache, might be considered acceptable trade-offs for therapeutic benefit. But others, like liver failure or birth defects, would be considered unacceptable at any dose. This is particularly true when it comes to environmental chemicals, where the effects may be subtler and the exposure levels more variable. Is a chemical that causes a small decrease in IQ scores toxic? What about one that slightly increases the risk of cancer over a lifetime (20+ years)? And this is one of the major problems with applying predicting toxicology at all - defining what is and isn't toxic is hard! One may assume the FDA has clear stances on all these, but even they approach it on a 'vibe-based' perspective. They simply collate the data from in-vitro studies, animal studies, and human clinical trials, and arrive to an approval/no-approval conclusion that is, very often, at odds with some portion of the medical comm...

Link to original articleWelcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: A primer on why computational predictive toxicology is hard, published by Abhishaike Mahajan on August 19, 2024 on LessWrong. Introduction There are now (claimed) foundation models for protein sequences, DNA sequences, RNA sequences, molecules, scRNA-seq, chromatin accessibility, pathology slides, medical images, electronic health records, and clinical free-text. It's a dizzying rate of progress. But there's a few problems in biology that, interestingly enough, have evaded a similar level of ML progress, despite there seemingly being all the necessary conditions to achieve it. Toxicology is one of those problems. This isn't a new insight, it was called out in one of Derek Lowe's posts, where he said: There are no existing AI/ML systems that mitigate clinical failure risks due to target choice or toxicology. He also repeats it in a more recent post: '…the most badly needed improvements in drug discovery are in the exact areas that are most resistant to AI and machine learning techniques. By which I mean target selection and predictive toxicology.' Pat Walters also goes into the subject with much more depth, emphasizing how difficult the whole field is. As someone who isn't familiar at all with the area of predictive toxicology, that immediately felt strange. Why such little progress? It can't be that hard, right? Unlike drug development, where you're trying to precisely hit some key molecular mechanism, assessing toxicity almost feels…brutish in nature. Something that's as clear as day, easy to spot out with eyes, easier still to do with a computer trained to look for it. Of course, there will be some stragglers that leak through this filtering, but it should be minimal. Obviously a hard problem in its own right, but why isn't it close to being solved? What's up with this field? Some background One may naturally assume that there is a well-established definition of toxicity, a standard blanket definition to delineate between things that are and aren't toxic. While there are terms such as LD50, LC50, EC50, and IC50, used to explain the degree by which something is toxic, they are an immense oversimplification. When we say a substance is "toxic," there's usually a lot of follow-up questions. Is it toxic at any dose? Only above a certain threshold? Is it toxic for everyone, or just for certain susceptible individuals (as we'll discuss later)? The relationship between dose and toxicity is not always linear, and can vary depending on the route of exposure, the duration of exposure, and individual susceptibility factors. A dose that causes no adverse effects when consumed orally might be highly toxic if inhaled or injected. And a dose that is well-tolerated with acute exposure might cause serious harm over longer periods of chronic exposure. The very definition of an "adverse effect" resulting from toxicity is not always clear-cut either. Some drug side effects, like mild nausea or headache, might be considered acceptable trade-offs for therapeutic benefit. But others, like liver failure or birth defects, would be considered unacceptable at any dose. This is particularly true when it comes to environmental chemicals, where the effects may be subtler and the exposure levels more variable. Is a chemical that causes a small decrease in IQ scores toxic? What about one that slightly increases the risk of cancer over a lifetime (20+ years)? And this is one of the major problems with applying predicting toxicology at all - defining what is and isn't toxic is hard! One may assume the FDA has clear stances on all these, but even they approach it on a 'vibe-based' perspective. They simply collate the data from in-vitro studies, animal studies, and human clinical trials, and arrive to an approval/no-approval conclusion that is, very often, at odds with some portion of the medical comm...

COMMON EARTH, Season 4 , Episode 1CLICK HERE to watch the video replay Can habitats & environments be returned to their wild, natural state while taking into consideration the requirements of human communities?Join us for this interview with Manoj Gautam, community-based conservation activist, former executive director of the Jane Goodall Institute of Nepal, and 2014 recipient of the Future for Nature prize.This year, Manoj was named to the elite Explorers Club 50. Each year, The Explorers Club 50 recognizes fifty extraordinary individuals changing the world. Naming these global exploration leaders to the EC50 shines a bright light on their extraordinary work, amplifies their voices, and redefines that field of exploration as we know it.Current Projects:bardia.travel - Ecotours & expeditions in Bardia National Park, Nepalnepalconservation.travel - Ecotours & conservation expeditions om Nepal planetperegrine.org - Research expeditions & travel for conservation professionalsschoolsforsdg.org - Schools for Sustainable Development - Educational stays & travel in Nepal

COMMON EARTH, Season 4 , Episode 1CLICK HERE to watch the video replayJoin us for this interview with Manoj Gautam, community-based conservation activist, former executive director of the Jane Goodall Institute of Nepal, and 2014 recipient of the Future for Nature prize."Rewilding" is not just about bringing back endangered species and habitats, it's about restoring balance to our planet. Pierce Press author Manoj Gautam's innovative community-based approach to conservation has made a real impact in Nepal and beyond. In this discussion, we talk about how and to what extent habitats & environments can be returned to their wild, natural state while taking into consideration the requirements of human communities.This year, Manoj was named to the elite Explorers Club 50. Each year, The Explorers Club 50 recognizes fifty extraordinary individuals changing the world. Naming these global exploration leaders to the EC50 shines a bright light on their extraordinary work, amplifies their voices, and redefines that field of exploration as we know it.Current Projects:bardia.travel - Ecotours & expeditions in Bardia National Park, Nepalnepalconservation.travel - Ecotours & conservation expeditions om Nepalplanetperegrine.org - Research expeditions & travel for conservation professionalsschoolsforsdg.org - Schools for Sustainable Development - Educational stays & travel in Nepal

Karina Oliani é uma atleta, médica, aventureira e apresentadora de TV brasileira. Especializada em medicina de emergência e resgate em áreas remotas, ela foi a primeira brasileira a subir o K2, e primeira sul-americana a escalar as duas faces do Everest. Oliani nasceu em 1982, em São Paulo. Interessada por esportes radicais desde a infância, Karina pulou de paraquedas pela primeira vez aos 12 anos, e aos 17 já era bicampeã brasileira de wakeboard. Tornou-se tricampeã brasileira de snowboard e recordista em mergulho livre (apneia), além de ter licença da ANAC para pilotar helicópteros, ter trabalhado como instrutora de mergulho e organizar expedições ao Campo Base do Everest. Formada em Medicina, a atleta foi para os Estados Unidos se especializar em “wilderness medicine” – medicina em áreas selvagens. Desde então, fundou o Instituto Dharma, que oferece atendimento médico voluntário em áreas remotas do Brasil e partes isoladas de países africanos e asiáticos, e a Abmar (Associação Brasileira de Medicina de Áreas Remotas), que introduziu o conceito de ‘wilderness medicine' nas principais universidades do Brasil. Desde dos anos 2000, Karina Oliani trabalha como apresentadora de TV em canais como o Discovery Channel, SporTV, Canal Off e Multishow. Este ano, Karina Oliani foi reconhecida pela Explorers Club 50 (EC50), associação que elege, anualmente, 50 exploradores e aventureiros que ajudam a mudar o mundo para melhor. Foi tb mencionada no Livro dos Recordes da Guinness por ter atravessado a tirolesa mais longa do mundo, acima de um lago de lava de um vulcão ativo na Etiópia. Karina Oliani se tornou mãe: com apenas onze meses, a pequena Kora já tinha visitado oito países do mundo, dentre eles Nepal, Bolívia e Omã. Karina Oliani torce para que mais mulheres sejam reconhecidas, sem preconceitos, por seus méritos – seja na aventura ou na medicina

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.15.520648v1?rss=1 Authors: Miller, M. W., Vicente, L. C., Behra, M., Torres, A., Mendez, P., Rosa-Casillas, M., Bracho, D. P., Rosenthal, J. J. Abstract: The neglected tropical disease schistosomiasis impacts the lives of over 700 million people globally. Schistosoma mansoni, the trematode parasite that causes the most common type of schistosomiasis, requires planorbid pond snails of the genus Biomphalaria to support its larval development and transformation to the form that can infect humans. A greater understanding of neural signaling systems that are specific to the Biomphalaria intermediate host could lead to novel strategies for parasite or snail control. This study characterized a Biomphalaria glabrata neural receptor that is gated by the molluscan neuropeptide FMRF-NH2. The Biomphalaria glabrata FMRF-NH2 gated sodium channel (Bgl-FaNaC) amino acid sequence was highly conserved with FaNaCs found in related gastropods, especially the planorbid Planorbella trivolvis (91% sequence identity). In common with the P. trivolvis FaNaC, the B. glabrata receptor exhibited a low affinity (EC50: 3 x 10-4 M) and high specificity for the FMRF-NH2 agonist. Its expression in the central nervous system, detected by immunohistochemistry and in situ hybridization, was widespread, with the protein localized mainly to neuronal fibers and the mRNA confined to cell bodies. Colocalization was observed with the FMRF-NH2 tetrapeptide precursor in some neurons associated with male mating behavior. At the mRNA level, Bgl-FaNaC expression in the visceral and left parietal ganglia decreased at 20 days post infection by S. mansoni and in the shedding phase. Altered FMRF-NH2 signaling could be vital for parasite survival and proliferation in its snail intermediate host. 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/2020.10.30.361790v1?rss=1 Authors: Li, S., Zou, Y., Zhao, D., Yin, Y., Song, J., He, N., Liu, H., Li, L., Huang, H. Abstract: Protein engineering through directed evolution is an effective way to obtain proteins with novel functions with the potential applications as tools for diagnosis or therapeutics. Many natural proteins, largely antibodies as well as some non-antibody proteins, have undergone directed evolution in vitro in the test tubes in the laboratories around the world, resulted in the numerous protein variants with novel or enhanced functions. In this study, we constructed a Fyn SH2 variant library by randomizing the 8 variable residues in its phosphotyrosine (pTyr) binding pocket. Selection of this library by a pTyr peptide from MidT antigen led to the identification of SH2 variants with enhanced affinities to the peptide, compared to the wild type SH2, by EC50 assay. Fluorescent polarization (FP) was then applied to quantify the binding affinity of the newly identified SH2 variants. As a result, three SH2 variants, named V3, V13 and V24, have comparable binding affinities with the previously identified SH2 triple-mutant superbinder (refer to Trm). Biolayer Interferometry (BLI) assay was employed to disclose the kinetics of the binding of these SH2 superbinders, in addition to the wild type SH2, to the phosphotyrosine peptide. The results indicated that all the SH2 superbinders have two-orders increase of the dissociation rate when binding the pTyr peptide while there was no significant change in their associate rates. The previously identified SH2 superbinder Trm as well as the V13 and V24 discovered in this study have cross-reactivity with the sulfotyrosine (sTyr) containing peptide while the wild type SH2 does not. Intriguingly, though binding the pTyr peptide with comparable affinity with other SH2 superbinders, the V3 does not bind to the sTyr peptide, implying it binds to the pTyr peptide with a different pattern from the other superbinders. The newly identified superbinders could be utilized as tools for the identification of pTyr-containing proteins from tissues under different physiological or pathophysiological conditions and may have the potential in the therapeutics. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.23.347534v1?rss=1 Authors: Mellott, D., Tseng, C.-T., Drelich, A., Fajtova, P., Chenna, B. C., Kostomiris, D., Hsu, J. C., Zhu, J., Taylor, Z., Tat, V., Katzfuss, A., Li, L., Giardini, M. A., Skinner, D., Hirata, K., Beck, S., Carlin, A. F., Clark, A. E., Berreta, L., Maneval, D., Frueh, F., Hurst, B. L., Wang, H., Kocurek, K. I., Raushel, F. M., O'Donoghue, A., Siqueira-Neto, J. L., Meek, T. D., McKerrow, J. H. Abstract: K777 is a di-peptide analog that contains an electrophilic vinyl-sulfone moiety and is a potent, covalent inactivator of cathepsins. Vero E6, HeLa/ACE2, Caco-2, A549/ACE2, and Calu-3, cells were exposed to SARS-CoV-2, and then treated with K777. K777 reduced viral infectivity with EC50 values of inhibition of viral infection of: 74 nM for Vero E6,

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.13.337410v1?rss=1 Authors: Indurthi, D., Auerbach, A. Abstract: Concentration-response curves (CRCs) are characterized by a midpoint (EC50) and a high-concentration asymptote (POmax) that relate to agonist affinity and efficacy. A third agonist attribute, efficiency, is the fraction of binding energy that is applied to the conformational change that activates the receptor. Here we show that agonist efficiency can be calculated from EC50 and POmax, and estimate the efficiencies of 17 agonists of adult muscle nicotinic acetylcholine receptors (AChRs). The distribution of efficiency values was bi-modal with mean{+/-}s.d of 52{+/-}2% (n=11) and 41{+/-}3% (n=6). Efficiency is correlated inversely with the volume of the agonists' head-group. For 22 binding site mutations only aY190A affects significantly ACh efficiency, switching it from the high- to the low-efficiency population. If agonist efficiency is known, EC50 can be estimated from POmax and the receptor's level of constitutive activity can be calculated from a CRC. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.16.154740v1?rss=1 Authors: Fullerton, E. F., Rubaharan, M., Karom, M. C., Hanberry, R. L., Murphy, A. Z. Abstract: The present study investigated the impact of advanced age on morphine modulation of persistent inflammatory pain in male and female rats. The impact of age, sex, and pain on mu-opioid receptor (MOR) expression and binding in the ventrolateral PAG (vlPAG) was also examined using immunohistochemistry and receptor autoradiography. Intraplantar administration of Complete Freund's adjuvant induced comparable levels of edema and hyperalgesia in adult (2-3mos) and aged (16-18mos) male and female rats. Morphine potency was highest in adult males, with a two-fold decrease in morphine EC50 observed in aged versus adult males (10.22mg/kg versus 5.19mg/kg). Adult and aged female rats also exhibited significantly higher EC50 values (10.69 mg/kg and 9.00 mg/kg, respectively) compared to adult males. The upward shift in EC50 from adult to aged males was paralleled by a reduction in vlPAG MOR expression and binding. The observed age-related reductions in morphine potency and vlPAG MOR expression and binding have significant implications in pain management in the aged population. Copy rights belong to original authors. Visit the link for more info

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 from this month's issue. In our first paper this month, Shaan Khurshid and associates determine the frequency of rhythm abnormalities in 502,627 adults in the UK Biobank, a national prospective cohort. They found that 2.35% had a baseline rhythm abnormality. The prevalence increased with age, with 4.84% of individuals aged 65 to 73 years having rhythm abnormalities. During over three million person- years of follow up, nearly 16,000 new rhythm abnormalities were detected. Atrial fibrillation was the most frequent with three per thousand person-years. Bradyarrhythmia with almost one per thousand person-years. Conduction system disease is about one per one thousand years. Supraventricular and ventricular arrhythmias, each about one half per one thousand person-years. Older age was associated with a hazard ratio of 2.35 for each 10 year increase. Male sex, hypertension, chronic kidney disease and heart failure were all associated with new rhythm abnormalities. In our next paper, Fabien Squara and associates evaluated a method of determining the septal or free wall positioning of pacemaker or ICD leads during fluoroscopy. They compared in 50 patients a classical approach using posterior anterior, right anterior oblique 30 degrees, and left anterior oblique 40 degrees fluoroscopic imaging’s to 50 patients undergoing an individualized left anterior oblique or LAO approach. This individualized LAO approach view provided a true view of the interventricular septum. This angle was defined by the degree of LAO that allowed the perfect superimposition of the RV apex, using the tip of the right ventricular lead, temporarily placed at the apex, and one of the superior vena cava, inferior vena cava access using a guide wire. Transthoracic echo was used to confirm position of the right ventricular lead. Septal, or free wall, right ventricular lead positioning was correctly identified in 96% of patients in the individualized group, versus 76% in the classical group. P equals 0.004. For septal lead positioning fluoroscopy had 100% sensitivity, and an 89.5 specificity in an individualized group, versus 91.4% sensitivity, and a 40% specificity in the classical group. In our next paper, Elsayed Soliman and associates examined the lifetime risk of atrial fibrillation based on race and socioeconomic status. In the atherosclerosis risk in communities, ARIC, cohort, of 15,343 participants without atrial fibrillation, patients were recruited in 1987 to 1989, when they were 45 to 64 years of age, and followed through 2014. The authors identify 2,760 atrial fibrillation cases during a mean follow up of 21 years. The authors found that the lifetime risk of atrial fibrillation in the ARIC cohort was approximately one in three among whites, and one in five among African Americans. And, the socioeconomic status was inversely associated with cumulative incidents of atrial fibrillation before the last decades of life. In our next paper, Jonathan Steinberg and associates sought to determine the impact of atrial fibrillation episode duration threshold on atrial fibrillation incidents and burden in pacemaker patients in a prospective registry. In 615 pacemaker patients was device detected atrial fibrillation over a mean follow up of 3.7 years, 599 had one or more atrial fibrillation episodes of 30 seconds duration, with a mean number of 22 episodes. At 12 months, freedom from atrial fibrillation ranged from 25.5% to 73.1%, based on a duration threshold from 30 seconds up to 24 hours. Of patients with a first episode of 30 seconds to two minutes, 35.8% were free from subsequent episodes greater than two minutes at 180 days. The mean atrial fibrillation burden of 0.2% for patients with first episodes between 30 seconds and 3.8 hours, was significantly less than the 9.5% burden for those with greater than 3.8 hours. The authors concluded that small differences in atrial fibrillation episode duration definition can significantly affect the perceived incidents of atrial fibrillation impact reported outcomes, including atrial fibrillation success. An initial atrial fibrillation episode of 30 seconds does not predict clinically meaningful atrial fibrillation burden. In the next paper, Hongwu Chen and Linsheng Shi and associates examined the distinct electrophysiologic features of bundle branch reentrant ventricular tachycardia in patients without structural heart disease. They described nine patients, mean age 29.6 years, with normal left ventricular function and bundle branch reentrant ventricular tachycardia, with a right bundle branch block pattern in one patient, and left bundle branch block patterns in nine patients. In all left bundle branch block pattern ventricular tachycardia, the mean ventricular tachycardia cycling was 329.3 milliseconds, and the median HV interval during tachycardia was longer than that of baseline, 78 versus 71 milliseconds. The H to right bundle interval during ventricular tachycardia was slightly shorter, however, the right bundle to ventricular interval was markedly longer than that during sinus rhythm, 50 versus 30 milliseconds. In six patients with three dimensional mapping of the left ventricle, a slow anterograde, or retrograde conduction over the left His-Purkinje system with normal myocardial voltage was identified. In addition, Purkinje related ventricular tachycardias were also induced in five patients. Ablation was applied to the distal left bundle branch block in patients with baseline left bundle branch block, and in one narrow QRS patient with sustained Purkinje related ventricular tachycardia, while right bundle branch was targeted in other patients. During a mean follow up at 31.4 months, frequent premature ventricular contractions occurred in one patient, and new ventricular tachycardia developed in the other patient. In the next paper, Michel Haissaguerre and associates examined detailed mapping in 24 patients who survived idiopathic ventricular fibrillation. They used multi-electrode body surface recordings to identify the drivers maintaining ventricular fibrillation, and analyze electrograms in the driver regions, using endocardial and epicardial catheter mapping during sinus rhythm. Ventricular fibrillation occurred spontaneous in three patients, and was induced in 16, while VF was non-inducible in five. Ventricular fibrillation mapping demonstrated reentrant and focal activities, 87% and 13% respectively. The activities were dominant in one ventricle in nine patients, while they were biventricular in the others. During sinus rhythm, areas of abnormal electrograms were identified in 15 out of 24 patients, or 62.5%, revealing localized structural alterations, in the right ventricle in 11, the left ventricle in one, in both in three. They covered a limited surface, 13 centimeters squared, representing 5% of the total surface, and recorded predominantly on the epicardium. 76% of these areas were co-located with ventricular fibrillation drivers. In nine patients without structural alterations, the authors observed a high incidence of Purkinje triggers, seven out of nine, versus four out of 15. Catheter ablation resulted in arrhythmia-free outcomes in 15 out of 18 patients at a 17 month follow up. In our next paper, David Spar and associates describe the effectiveness, safety, and compliance of the wearable cardioverter defibrillator in the identification and treatment of life-threatening ventricular arrhythmias in all US pediatric patients who wore a wearable defibrillator from 2009 to 2016, ages less than 18 years. The 455 patients had a median age of 15 years, median duration of wearable cardioverter defibrillator use of 33 days, and median patient wear time of 20.6 hours per day. The study population was divided into two groups, 63 patients with an ICD problem, or 392 patients without an ICD problem. The wear time was greater than 20 hours in both groups. There were seven deaths, or 1.5%. All patients were not wearing the wearable cardioverter defibrillator at the time of death. Eight patients, 1.8%, received at least one wearable cardioverter defibrillator shock treatment. Of the six patients who had appropriate therapy, there were seven episodes of either polymorphic ventricular tachycardia, or ventricular fibrillation, with a total of 13 treatments delivered. All episodes were successfully converted, and the patient survived. In our next paper, Marc Lemoine and associates used human-induced pluripotential stem cell-derived cardiomyocytes to examine differences in repolarization reserve. The authors compared the contribution of IKs and IKr on action potential durations in human left ventricular tissue, and the human induced pluripotential stem cell derived cardiomyocytes, or IPS-derived engineered heart tissue. They found that the IPS-derived heart tissue showed spontaneous diastolic depolarization in action potential duration, which were sensitive to low concentrations of Ivabradine. IKr block by E-4031 prolonged action potential duration 90 with similar EC50 in both the IPS-derived heart tissue and the human left ventricular tissue. But a larger effect size in the IPS-derived heart tissue, 281 milliseconds versus 110 milliseconds, in the human left ventricular tissue. While IKr block alone evoked early after depolarizations, it triggered activity in 50% of the IPS-derived heart tissue. Slow pacing reduced extracellular potassium blocking of IKr, IKs and IK1 were necessary to induce early after depolarizations in human left ventricular tissue. In accordance with their clinical safety, Moxifloxacin and Verapamil did not induce EADs in IPS-derived heart tissue. In both IPS-derived heart tissue and human left ventricular tissue, IKs block by HMR 1556 prolonged action potential duration 90 slightly in the combined presence of E-4031 and isoprenaline. In our next paper, Elizabeth Saarel and associates sought to obtain contemporary digital ECG measurements in healthy children from North America to evaluate the effects of sex and race, and to compare the results to commonly published data sets, using 2400 digital ECGs, collected for children less than 18 years of age with normal electrocardiograms at 19 centers in the pediatric heart network. The authors found that the QTc in lead II was greater for females compared to males for age groups three years or older, for whites compared to African Americans, for ages 12 years or older. The R wave amplitude in V6 was greater for males compared to females for age groups 12 years and greater; for African Americans compared to white or other race categories for age groups three years or greater; and greater compared to commonly used public data set groups for ages 12 years and greater. In our next paper, Pyotr Platonov and associates examined T-wave morphology as a possible predictor of cardiac events in patients with type 2 long QT syndrome mutation carriers with normal QTc intervals. The authors compared 154 LQT2 mutation carriers with QTc less than 360 milliseconds in men, and less than 470 milliseconds in women, with 1007 unaffected family members. Flat, notched, or negative T-waves in leads II or V5 on baseline ECG were considered abnormal. Using Cox regression analysis, the associations between T-wave morphology, the presence in mutations in the poor region of KCNH2, and the risk of cardiac events defined that syncope aborted cardiac arrest, defibrillator therapy, or sudden cardiac arrests were assessed. The authors found that LQT2 female carriers with abnormal T-wave morphology had a threefold increased risk of cardiac events compared to LQT2 female carriers with normal T-waves, while this association was not seen in males. LQT2 males with poor location of mutations had a six-fold increased risk of cardiac events than non-poor location males, while no such association was found in females. In our last paper, Yaniv Bar-Cohen and associates describe a percutaneous pacemaker entirely implanted in the pericardium, using a sheath for sub-xiphoid access to the pericardial space, and a miniaturized camera with fiber optic illumination, the micro-pacemakers were successfully implanted in six pigs. All animals were studied during follow up, survived without symptoms. That's it for this month. We hope that you'll find the Journal to be the go-to place for everyone interested in the field. See you next time!  

Author: Rachael Duncan, PharmD Educational Pearls A NEJM study report in July 2016 discussed a situation in New York during which 30 people became “zombie-like” after ingesting synthetic cannabinoids (aka “Spice). The ER managed to coordinate with the CDC to evaluate  blood samples from 18 patients who were transported to the hospital. Of those who went to the ER, the mean age was 36.8, many  of them were homeless, all of them were male. Mass spectrometry was used to confirm the presence of synthetic cannabinoid in their blood. Compared to normal THC, synthetic cannabinoids have a much lower EC50 and LD50. Spice intoxication presents in a variety of ways -patients may be hyperthermic, combative, delirious and/or seizing. Treatment  is supportive, including fluids, cooling, electrolyte management, and sedatives. References: Adams, A. J., Banister, S. D., Irizarry, L., Trecki, J., Schwartz, M., & Gerona, R. (2017). “Zombie” Outbreak Caused by the Synthetic Cannabinoid AMB-FUBINACA in New York. New England Journal of Medicine, 376(3), 235-242. doi:10.1056/nejmoa1610300

The purpose of the study reported here was to compare the antiviral efficacy against feline immunodeficiency virus (FIV) and cytotoxicity in feline peripheral blood mononuclear (PBM) cells of 9 nucleoside reverse transcriptase inhibitors (NRTIs), three of which had not been evaluated against FIV in feline cells before. PBM cells were isolated from the blood of three specific pathogen-free (SPF) cats. The cytotoxic effects of the test compounds were determined by colorimetric quantification of a formazan product resulting from bioreduction of a tetrazolium reagent by viable PBM cells. Each compound was tested in 12 concentrations ranging from 0.001 to 500 M. Uninfected cells from one SPF cat were used in these assays. PBM cells (from all three SPF cats) were infected with the molecular clone FIV pPPR and the antiviral efficacy of the test compounds was assessed using a FIV p24 antigen capture enzyme-linked immunosorbent assay. Each compound was tested in 5 concentrations ranging from 0.1 to 10 M. Cytotoxic effects in feline PBM cells were observed only at concentrations over 10 M for all 9 NRTIs. Comparison of the cytotoxic effect at the highest concentration investigated (500 M) revealed that didanosine and amdoxovir were significantly less toxic than abacavir. As no cytotoxicity was noted up to a concentration of 10 M, this was set as the highest concentration for the second part of this study investigating the anti-FIV efficacy of the test compounds. All drugs induced a dose-dependent reduction of FIV replication. When compared at the highest concentration investigated, there was no significant difference in the antiviral efficacy among the test compounds. The EC50 could not be determined as none of the test compounds achieved 50% viral inhibition. The evaluated NRTIs had low cytotoxicity against feline PBM cells and appear to be safe options for further in vivo evaluation for the treatment of FIV-infected cats. There was no evidence suggesting that the newly evaluated compounds would be superior to the existing NRTIs for reducing the FIV burden of infected cats.

EPISODE 29 - Gare de Lille, France, Fitz on the Eurostar. As the tea trollies are rolling by, our big guy compiles this short, sweet selection, to follow the Croque Monsieur. DJs 1/ Atomic Forest - "Locomotive Breath" 2/ Mät Tròi Den - "Black Sun" DJs 3/ Novos Bahianos - "Globo Do Morto" 4/ O Bando - "Alegria" 5/ Os Brazoes - Tao Longe De Mim DJs 6/ Messieurs Richard De Bordeux & Daniel Beretta - "Le Drogue" 7/ Catherine Ribeiro and Alpes - "Jusqu'à Ce Que La Force Me Manque" 8/ Pierre Henry - "Psyche Rock" DJs 9/ Semi-Colon - "Nekwaha" 10/ Strangers - "Love Rock" 11/ Bongos Ikwue and the Groovies - "Sitting On the Beach" DJs 12/ Los Amaya - "Bailen Mi Rumbita" 13/ Rumba Brava - "Baila, Canta y Rie" 14/ Reto Gitano - "Tú Me Gusta Más y Más" DJs 15/ Chango - "Chivato" DJs

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is a hallmark of complex and multifactorial psychiatric diseases such as anxiety and mood disorders. The 41-amino acid neuropeptide Corticotropin Releasing Hormone (CRH) is a major regulator of the mammalian stress response. Upon stressful stimuli, it binds to the Corticotropin Releasing Hormone Receptor 1 (CRHR1), a typical member of the class B GPCRs and a potential novel target for the therapeutic intervention in major depressive disorder. A precise understanding of the peptide-receptor interactions is an essential prerequisite towards the development of efficient CRHR1 specific antagonists. To chemically probe the molecular interaction of CRH with its cognate receptor, a high-throughput conjugation approach which mimics the natural activation mechanism for class B GPCRs was developed. Acetylene-tagged peptide libraries were synthesized and conjugated to high-affinity azide-modified carrier peptides using copper-catalyzed dipolar cycloaddition. The resulting conjugates reconstitute potent ligands and were tested in situ for modulation of the CRHR1 activity in a cell-based assay. This approach allows to (i) define the sequence motifs which are required for receptor activation or inhibition, (ii) identify the critical functional groups and investigate structure-activity-relationships, and (iii) develop novel optimized, highly potent peptide probes which are specific for the transmembrane domain of the receptor. The membrane recruitment by a high-affinity carrier peptide enhances the potency of tethered peptides and allows the initial testing of weak fragments that otherwise would be inactive. The biomimetic screening led to the discovery of transtressin, a highly modified and potent CRHR1 transmembrane domain-specific optimized agonist (EC50 = 4 nM). Beyond its intrinsic agonistic activity, transtressin is an essential tool for the pharmacological characterization of CRHR1 antagonists in competition assays.

On the 31st of January 2009 Lado made the trip to Dublin from Tbilisi to play the FVF label night at Pogo in the Twisted Pepper. On the warm up was local rising star, Hugo Johnson. Lado quite simply rocked the place and his set was recorded live from the club. This set was also broadcast on RTE Pulse Radio by Will Kinsella on his show Ceoltronic which also features an exclusive interview with Lado, Sjaakflut and Matt from FVF. This set comes as our new VA release, FVF007 Fiends & Family Volume II, hits Beatport. This bumper VA features a multitude of tracks from the likes of Sjaakflut, Siphon, Pheek, Alexx Wolfe & Sabb, Donk Boys, Metrotek, EC50, QiK & Station F. Watch out for upcoming tracks and releases from EC50, Alexx Wolfe, Heron, Miro Pajic and Marc Ashken... Let the good times roll.

Regulation of adenylate cyclases and extracellular signal-regulated protein kinases by delta-opioid receptors in HEK293 cells Stimulation of G protein coupled opioid receptors result in both inhibition of adenylate cyclases and stimulation of extracellular signal-regulated protein kinases ERK1/2. As regulation of cellular effectors may be accomplished by various G proteins as well as by the different G protein subunits (G alpha, G betagamma), delta-opioid receptors were thus examined for activating different G proteins underlying different regulation of these cellular effectors. In transfected HEK293 cells, activation of delta-opioid receptors by peptidergic opioids (DADLE, DPDPE) and alkaloids (etorphine, morphine) brought about concentration-dependent inhibition of adenylate cyclases and stimulation of the ERKs, respectively. Since the high-affinity opioids DADLE, DPDPE and etorphine accomplished regulation of respective effector molecules already at nanomolar ligand concentrations, a 1000-fold higher dose of low-affinity agonist morphine was required for both inhibition of adenylate cyclases and ERK activation. However, for all tested opioids, a higher EC50 could have been determined for inhibition of adenylate cyclases than for stimulation of the ERKs. Thus, adenylate cyclases expressed in HEK cells seems to be more sensitive to delta-opioid receptor activation than the ERKs. As previously shown, exposure of HEK-DOR cells to pertussis toxin (PTX) resulted in incomplete inhibition of adenylate cyclases by DADLE and DPDPE, whereas etorphine and morphine totally lost their ability to inhibit the cyclases under these conditions. In contrast, activation of ERKs by all tested opioids was abolished by PTX treatment. However, PTX also blocked ERK activation by Gq-coupled receptors and receptor tyrosine kinases, both regulating ERKs independent from PTX-sensitive Gi proteins. Thus, PTX is suggested to inhibit ERK activation also independent from affecting G protein activation. Since inhibition of G alpha q subunits by the G alpha q-binding protein EBP50 did not affect effector regulation, inhibition of G alpha q and G alpha 12 mediated signaling by neomycin and 1-butanol brought about partial blockade of ERK activation by all tested opioids. Exposure of HEK-DOR cells with neomycin and 1-butanol together even totally blocked ERK activation by respective opioids. In contrast, inhibition of G alpha 11 signaling partially blocked inhibition of adenylate cyclases by DADLE and DPDPE, whereas regulation of the cyclases by the alkaloids was not affected under this condition. Since inhibition of G betagamma signaling by phosducin did not affect regulation of adenylate cyclases and ERKs by opioids, delta-opoioid receptors are supposed to regulate these cellular effectors by G alpha subunits. Although the tested cellular effectors are regulated differently, inhibition of adenylate cyclases seems to support activation of ERKs, since simultaneous stimulation of the cyclases by forskolin impairs ERK activation by DPDPE and etorphin. In contrast, activation of ERKs did not affect regulation of the cyclases by delta-opioid receptors. Together the findings let suppose that different G alpha subunits might be involved in regulation of adenylate cyclases and ERKs by delta-opioid receptors. Since stimulation of delta-receptors might be supposed to bring about inhibition of adenylate cyclases by G alpha i and G alpha 11 subunits, alkaloids seems to regulate cyclases by G alpha i subunits. In contrast, both peptide and alkaloid opioids seem to stimulate ERKs by G alpha 11- and G alpha 12-mediated signaling.

Changes in ATP-induced increase in {[}Ca2+], during collecting duct ontogeny were studied in primary monolayer cultures of mouse ureteric bud (UB) and cortical collecting duct (CCD) cells by Fura-PE3 fluorescence ratio imaging. In UB (embryonic day E14 and postnatal day P1) the ATIP-stimulated increase (EC50 approximate to 1 muM) in fluorescence ratio (DeltaR(ATP)) was independent of extracellular Ca2+ and insensitive to the P2 purinoceptor-antagonist suramin (1 mM). From day P7 onward when CCD morphogenesis had been completed DeltaR(ATP) increased and became dependent on extracellular Ca2+. This ATP-stimulated Ca2+ entry into CCD cells was non-capacitative and suramin (11 mM)insensitive, but sensitive to nifedipine (30 muM) and enhanced by Bay K8644 (15 muM), a blocker and an agonist of L-type Ca2+ channels, respectively. Quantitative RT-PCR demonstrated similar mRNA expression of L-type Ca2+ channel alpha1-subunit, P2Y(1), P2Y(2), and P2X(4b) purinoceptors in UB and CCD monolayers while the abundance of P2X(4) mRNA increased with CCD morphogenesis. In conclusion, both embryonic and postnatal cells express probably P2Y(2)-stimulated Ca2+ release from intracellular stores. With development, the CCD epithelium acquires ATP-stimulated Ca2+ entry via L-type Ca2+ channels. This pathway might by mediated by the increasing expression of P2X(4)-receptors resulting in an increasing ATP-dependent membrane depolarization and activation of L-type Ca2+ channels. Copyright (C) 2002 S. Karger AG, Basel.

Background/Aim: Patients with idiopathic focal segmental glomerulosclerosis (FSGS) often develop a recurrence of the disease after kidney transplantation. In a number of FSGS patients, plasmapheresis and immunoadsorption procedures have been shown to transiently reduce proteinuria and are thought to do this by eliminating a circulating factor. Direct cellular effects of eluates from immunoadsorption procedures on podocytes, the primary target of injury in FSGS, have not yet been reported. Methods: Eluates were derived from antibody-based immunoadsorption of a patient suffering from primary FSGS, a patient with systemic lupus erythematosus, and a healthy volunteer. The cytosolic free Ca2+ concentration ({[}Ca2+](i)) of differentiated podocytes was measured by single-cell fura-2 microfluorescence measurements. Free and total immunoreactive kinin levels were measured by radioimmunoassay. Results: FSGS eluates increased the {[}Ca2+](i) levels concentration dependently (EC50 0.14 mg/ml; n = 3-19). 1 mg/ml eluate increased the {[}Ca2+](i) values reversibly from 82 +/- 12 to 1,462 +/- 370 nmol/l, and then they returned back to 100 16 nmol/l (n = 19). The eluate-induced increase of {[}Ca2+](i) consisted of an initial Ca2+ peak followed by a Ca2+ plateau which depended on the extracellular Ca2+ concentration. The eluate-induced increase of {[}Ca2+](i) was inhibited by the specific B-2 kinin receptor antagonist Hoe 140 in a concentration-dependent manner (IC50 2.47 nmol/l). In addition, prior repetitive application of bradykinin desensitized the effect of eluate on {[}Ca2+](i). A colonic epithelial cell line not reacting to bradykinin did not respond to eluate either (n = 6). Similar to FSGS eluates, the eluate preparations of both the systemic lupus patient and the healthy volunteer led to a biphasic, concentration-dependent {[}Ca2+](i) increase in poclocytes which again was inhibited by Hoe 140. Free kinins were detected in all eluate preparations. Conclusion: The procedure of antibody-based immunoadsorption leads to kinin in the eluate which elevates the {[}Ca2+](i) level of podocytes via B-2 kinin receptors. Copyright (C) 2002 S. Karger AG, Basel.

Encapsulation of oligonucleotides in antibody-targeted liposomes (immunoliposomes) which bind to target cells permits intracellular delivery of the oligonucleotides. This approach circumvents problems of extracellular degradation by nucleases and poor membrane permeability which free phosphodiester oligonucleotides are subject to, but leaves unresolved the inefficiency of encapsulation of oligonucleotides in liposomes. We have coupled oligonucleotides to cholesterol via a reversible disulfide bond. This modification of oligonucleotides improved their association with immunoliposomes by a factor of about 10 in comparison to unmodified oligonucleotides. The presence of cholesteryl-modified oligonucleotides incorporated in the bilayer of liposomes did not interfere with the coupling of the targeting protein to the liposome surface. Free or cholesterol coupled oligonucleotides associated with liposomes and directed against the tat gene of HIV-1 were tested for inhibition of HIV-1 proliferation in acutely infected cells. We demonstrate that the cholesteryl-modified as well as unmodified oligonucleotides acquire the target specificity of the antibody on the liposome. Their antiviral activity when delivered into cells is sequence-specific. The activity of these modified or unmodified oligonucleotides to inhibit the replication of HIV was the same on an equimolar basis (EC50 around 0.1 μM). Cholesterol coupled oligonucleotides thus offer increased liposome association without loss of antiviral activity.

There is increasing evidence for rapid steroid action on electrolyte transport in human mononuclear leukocytes (HML). In HML, aldosterone stimulates the Na+/H+ antiporter within a few minutes. Because a variety of hormones and growth factors activate the Na+/H+ antiporter via protein kinase C and inositol phospholipids, a possible involvement of inositol-1,4,5-trisphosphate (IP3) in the rapid effects of aldosterone in HML was investigated. The stimulation of IP3 generation was started by the addition of aldosterone, concanavalin A, or other steroids. A significant increase in IP3 levels by aldosterone (1 nmol/L, P < 0.05) was found after 1 min, similar to that found after concanavalin A (25 micrograms/mL). Aldosterone caused a concentration-dependent elevation of IP3 levels, with an apparent EC50 of approximately 0.1 nmol/L. Fludrocortisone stimulated IP3 generation at similar concentrations, whereas a weaker IP3 stimulation by glucocorticoids (hydrocortisone, dexamethasone) occurred at micromolar concentrations only. Canrenone, a potent inhibitor of classical aldosterone action, was not effective up to a concentration of 100 nmol/L. These findings show kinetic and pharmacological similarities with both the functional data on Na+/H+ antiport stimulation by aldosterone and the studies of 125I-aldosterone binding to plasma membranes of HML. Thus, these data are the first to indicate an involvement of the phosphoinositide pathway in the rapid membrane effects of aldosterone.

The actions of the phosphodiesterase inhibitor denbufylline on the excitability of hippocampal neurons were investigated by means of extracellular and intracellular recordings. Denbufylline, which has been shown to selectively inhibit a low KM, Ca2+/calmodulin-independent phosphodiesterase isozyme, concentration-dependently increased the amplitude of the extracellularly recorded CAI population spike evoked by electrical stimulation of the Schaffer collateral/commissural pathway. Concentration-response-curves yielded an EC50 for denbufylline of 0.76 M. In comparison, the nonselective phosphodiesterase inhibitor 3-isobutyl-lmethylxanthine (IBMX) also produced an increase in the amplitude of the population spike. From the concentration-response-curve, which was steeper than that of denbufylline, an EC50 for IBMX of 1.04 M was obtained. However, despite their similar EC50 values, denbufylline was found to be significantly more potent at lower concentrations (

1. Intracellular recordings were obtained from neurones in layers 2 and 3 of the rat frontal neocortex in an in vitro slice preparation. Three distinct types of stimulation-evoked post-synaptic potentials were recorded in these neurones: excitatory post-synaptic potentials (e.p.s.p.s); bicuculline-sensitive, chloride-dependent inhibitory post-synaptic potentials (i.p.s.p.s) with times to peak of 20-25 ms (fast(f)-i.p.s.p.s); bicuculline-insensitive, potassium-dependent i.p.s.p.s with bicuculline-insensitive, potassium-dependent i.p.s.p.s with times to peak of 150-250 ms (long(l)-i.p.s.p.s). 2. The effects of baclofen were investigated on seventy-one neurones. Baclofen was applied by ionophoresis or pressure ejection from micropipettes or was added to the superfusion medium. 3. Baclofen depressed stimulation-evoked e.p.s.p.s in fifty-seven of the sixty neurones tested. This effect was associated with an increase in the stimulation intensity required to produce a synaptically evoked action potential for thirty-nine of forty-four neurones. 4. Baclofen depressed f-i.p.s.p.s in thirty-seven of the thirty-nine neurones tested and l-i.p.s.p.s in each one of the seventeen neurones tested. Reversal potential values for each type of i.p.s.p. were not changed by baclofen and its depressions of each were independent of membrane potential (Em). Baclofen reduced the magnitude and the duration of the conductance increases that were associated with f- and l-i.p.s.p.s. 5. Baclofen hyperpolarized forty of seventy-one neurones and produced outward currents in three of four neurones recorded in voltage clamp at holding potentials between -55 and -65 mV. These actions were associated with 10-58% reductions of neuronal input resistance (RN) and 10-20% increases in neuronal input conductance (gN), respectively. Baclofen decreased the direct excitability of twenty-three of twenty-seven neurones tested. Determinations of the reversal potential for baclofen-induced changes of Em indicate that baclofen increases the conductance of rat neocortical neurones to potassium ions. 6. The EC50 for each action of DL-baclofen was approximately 1 microM. L-Baclofen was greater than 100 times more potent than D-baclofen. 7. Concentrations of bicuculline that blocked f-i.p.s.p.s and responses to ionophoretically applied gamma-aminobutyric acid (GABA) had no effect on the depressions of e.p.s.p.s or the hyperpolarizations and decreases in RN that baclofen produced. 8. Baclofen did not reduce the duration of action potentials that were prolonged with intracellular injections of caesium ions or by superfusions with medium that contained 10 mM-tetraethylammonium (TEA).