Podcasts about Fibronectin

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.15.528696v1?rss=1 Authors: Balic, A., Perver, D., Pagella, P., Rehrauer, H., Stadlinger, B., Moor, A. E., Vogel, V., Mitsiadis, T. Abstract: The carious lesion is a bacteria caused destruction of tooth mineralized matrices marked by concurrent tissue reparative and immune responses in the dental pulp. While major molecular players in tooth pulp decay have been uncovered, a detailed map of the molecular and cellular landscape of the diseased pulp is still missing. Here we used single-cell RNA sequencing analysis, to generate a comprehensive single-cell atlas of the carious human dental pulp tissue. Our data demonstrated modifications in various cell clusters of the carious pulp, such as immune cells, mesenchymal stem cells (MSC) and fibroblasts, when compared to the healthy dental pulp. These changes include upregulation of genes encoding extracellular matrix (ECM) components and the enrichment of the fibroblast cluster with myofibroblasts. Assessment of the Fibronectin fibres' mechanical strain showed a significant tension reduction in the carious human pulp, compared to the healthy one. Collectively, the present data demonstrate molecular, cellular and biomechanical alterations in the carious pulp tissue, indicative of extensive ECM remodelling and reminiscent of fibrosis observed in other organs. 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/2022.11.16.516843v1?rss=1 Authors: Melamed, S., Zaffryar-Eilot, S., Nadjar-Boger, E., Aviram, R., Zhao, H., Yaseen-Badarne, W., Kalev-Altman, R., Sela-Donenfeld, D., Lewinson, O., Astrof, S., Hasson, P., Wolfenson, H. Abstract: Fibronectin fibrillogenesis and mechanosensing both depend on integrin-mediated force transmission to the extracellular-matrix. However, force transmission is in itself dependent on fibrillogenesis, and fibronectin fibrils are found in soft embryos where sufficient force cannot be applied, demonstrating that force cannot be the sole initiator of fibrillogenesis. Here we identify a novel nucleation step prior to force generation, driven by fibronectin oxidation mediated by lysyl-oxidase enzyme family members. This oxidation induces fibronectin clustering that promotes early adhesion, alters cellular response to soft matrices, and enhances force transmission to the matrix. In contrast, absence of fibronectin oxidation abrogates fibrillogenesis, perturbs cell-matrix adhesion, and compromises mechanosensation. Moreover, FN oxidation promotes cancer cells colony formation in soft agar as well as collective and single-cell migration. These results reveal a yet unidentified, force-independent enzyme-dependent mechanism that initiates fibronectin fibrillogenesis, establishing a critical step in cell adhesion and mechanosensing. 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/2020.07.21.213397v1?rss=1 Authors: Park, J. E., Guo, X., Liou, K. C. K., Lynn, S. E., Ng, S. S., Meng, W., Lim, S. C., Leow, M. K.-S., Richards, A. M., Pennington, D. J., McCarthy, N. E., de Kleijn, D. P. V., Sorokin, V., Ho, H. H., Sze, S. K. Abstract: Abnormal matrix deposition on vessels and recruitment of inflammatory cells into the arterial wall are critical events in atherosclerotic plaque formation. Fibronectin protein is a key matrix component that exhibits high levels of deamidation in atherosclerotic plaques and blood plasma, but it is unclear how this structural change impacts on endothelial function or modifies interactions with recruited leukocytes. This study aimed to determine how deamidation-induced isoDGR motifs in fibronectin influence extracellular matrix accumulation on endothelial cells, and to investigate possible effects on integrin outside-in signalling in matrix-bound monocytes which are key mediators of human atherosclerosis. Blood plasma fibrinogen and fibronectin displayed marked accumulation of isoDGR motifs in ischemic heart disease (IHD) as determined by ELISA analysis of patients undergoing coronary artery bypass grafting compared with age-matched healthy controls. Biochemical and functional assays confirmed that isoDGR-containing fibronectin promoted activation of integrin {beta}1 in monocytes and facilitated protein deposition and fibrillogenesis on endothelial cell layers. In addition, isoDGR interactions with integrins on the monocyte cell surface triggered an ERK:AP-1 signalling cascade that induced potent secretion of chemotactic mediators (including CCL2, CCL4, IL-8, and TNF), that promoted further leukocyte recruitment to the assembling plaque. Fibronectin deamidation forms isoDGR motifs that increase binding to {beta}1 integrins on the surface of endothelial cells and monocytes. Subsequent activation of integrin outside-in signalling pathways elicits a range of potent cytokines and chemokines that drive additional leukocyte recruitment to the developing atherosclerotic matrix and likely constitutes a key early event in progression to IHD. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.22.215327v1?rss=1 Authors: Basu, S., Gorai, B., Basu, B., Maiti, P. K. Abstract: In experimental research driven biomaterials science, the influence of different material properties (elastic stiffness, surface energy, etc.), and to a relatively lesser extent, the biophysical stimulation (electric/magnetic) on the cell-material interaction has been extensively investigated. Considering the central importance of the protein adsorption on cell-material interaction, the role of physiochemical factors on the protein adsorption is also probed. Despite its significance, the quantitative analysis of many such aspects remains largely unexplored in biomaterials science. In recent studies, the critical role of electric field stimulation towards modulation of cell functionality on implantable biomaterials has been experimentally demonstrated. Given this background, we investigated the influence of external electric field stimulation (upto 1.00 V/nm) on fibronectin (FN) adsorption on hydroxyapatite, HA (100) surface at 300K using all-atom MD simulation method. Fibronectin adsorption was found to be governed by the attractive electrostatic interaction, which changed with the electric field strength. Non-monotonous changes in structural integrity of fibronectin were recorded with the change in field strength and direction. This can be attributed to the spatial rearrangement of local charges and global structural changes of the protein. The dipole moment vectors of fibronectin, water and HA quantitatively exhibited similar pattern of orienting themselves parallel to the field direction, with field strength dependent increase in their magnitudes. No significant change has been recorded for radial distribution function of water surrounding fibronectin. Field dependent variation in the salt bridge nets and number of hydrogen bonds between fibronectin and hydroxyapatite were also examined. One of the important results in the context of the cell-material interaction is that the RGD sequence of FN was exposed to solvent side, when the field was applied along a direction outward perpendicular to HA (001) surface. Summarizing, the present study provides quantitative insights into the influence of electric field stimulation on biomolecular interactions involved in fibronectin adsorption on hydroxyapatite surface. Copy rights belong to original authors. Visit the link for more info

On today's episode, Dr Joseph Sgroi (OBGYN) talks with Jess about her birth story. Jess' birth story features discussions around fertility, cervical shortening, steroid injections, Fetal fibronectin (fFN), caesarean section, micro preemie & NICU.Dr Joseph Sgroi is a highly experienced obstetrician, gynaecologist and fertility specialist in Melbourne. You can find Dr Joseph Sgroi on Instagram @drjosephsgroi or his website at www.drjoseph.com.au.This episode is proudly brought to you by Tiny Hearts Education; our mission is to bring education to all Australian parents through first aid and birthing courses so they can move through pregnancy, childbirth and parenthood with confidence. Visit www.tinyheartseducation.com for more information.

Dr Carolyn Lam:                Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr Carolyn Lam, associate editor from the National Heart Center and Duke National University of Singapore. This week's journal features two papers that deal with genetic testing in young athletes and for sudden arrhythmic death, and with findings that may surprise you. They really show the complexities of this era of genetic testing and cardiovascular medicine, and in fact are discussed as growing pains in cardiovascular genetics. You must listen to our feature discussion, which is coming right up after these summaries.                                                 The first original paper this week suggests that targeting fibronectin polymerization may be a new therapeutic strategy for treating cardiac fibrosis. Fibronectin polymerization is necessary for collagen matrix deposition and is a key contributor to increased abundance of cardiac myofibroblast following cardiac injury. In today's paper, first author Dr Valiente-Alandi, corresponding author Dr Blaxall from University of Cincinnati College of Medicine and Heart Institute, and their colleagues hypothesized that interfering with fibronectin polymerization, or its genetic ablation and fibroblasts, would attenuate myocardial fibrosis and improve cardiac function following ischemia reperfusion injury. Using mouse and human cardiac myofibroblasts, authors found that the fibronectin polymerization inhibitor pUR4 attenuated the pathological phenotype exhibited by mouse and human myofibroblasts by decreasing fibronectin polymerization and collagen deposition into the extracellular matrix as well as by myofibroblast proliferation and migration.                                                 Inhibiting fibronectin matrix deposition by pUR4 treatment or by deleting fibronectin gene expression in cardiac fibroblasts confirmed cardioprotection against ischemia reperfusion-induced injury by attenuating at first left ventricular remodeling and cardiac fibrosis, thus preserving cardiac function. In summary, interfering with fibronectin polymerization may be a new therapeutic strategy for treating cardiac fibrosis and heart failure.                                                 The Insulin Resistance Intervention after Stroke, or IRIS trial, demonstrated that pioglitazone reduced the risk of both cardiovascular events and diabetes in insulin-resistant patients. However, concern remains that pioglitazone may increase the risk of heart failure in susceptible individuals. To address this, Dr Young from Yale Cardiovascular Research Center and the IRIS investigators performed a secondary analysis of the IRIS trial. They found that older age, atrial fibrillation, hypertension, obesity, edema, high CRP, and smoking were risk factors for heart failure.                                                 Pioglitazone did not increase the risk of incident heart failure, and the effect of pioglitazone did not differ across levels of baseline risk. It should however be noted that in the IRIS trial, the study drug dose could be reduced for symptoms of edema or excessive weight gain, which occurred more often in the pioglitazone arm. Overall, pioglitazone reduced the composite outcome of stroke, MI, or hospitalized heart failure in the IRIS trial.                                                 The next study highlights the importance of genetic variation in cardiac fibrosis and suggests that while fibroblast activation is a response that parallels the extent of scar formation, proliferation may not necessarily correlate with levels of fibrosis. In this paper from co-first authors Dr Park and Ranjbarvaziri, corresponding author Dr Ardehali, from David Geffen School of Medicine, University of California, Los Angeles, the authors utilized a novel multiple-strain approach known as the Hybrid Mouse Diversity Panel to characterize the contributions of cardiac fibroblasts to the formation of isoproterenol-induced cardiac fibrosis in three strains of mice.                                                 They found that isolated cardiac fibroblasts treated with isoproterenol exhibited strain-specific increases in the levels of activation, but showed comparable levels of proliferation. Similar results were found in vivo with fibroblast activation but not proliferation correlating with the differential levels of cardiac fibrosis after isoproterenol treatment. RNA sequencing revealed that cardiac fibroblasts from each strain exhibited unique gene expression changes in response to isoproterenol.                                                 The authors further identified LTBP2 as a commonly upregulated gene after isoproterenol treatment. Expression of LTBP2 was elevated and specifically localized in the fibrotic regions of the myocardium after injury in mice and in human heart failure, suggesting that it may be a potential therapeutic target. That brings us to the end of our summaries. Now for our feature discussion.                                                 We all know that t-wave inversion is common in patients with cardiomyopathy, however up to a quarter of athletes of African descent, and five percent of white athletes also have t-wave inversion on ECG, but with unclear clinical significance despite comprehensive clinical evaluation. Now, what is the role in diagnostic use of genetic testing beyond clinical evaluation when we investigate these athletes with t-wave inversion? Well we're about to get some answers in today's feature paper, and I'm so pleased to have the corresponding author of the paper, Dr Sanjay Sharma from St. George's University of London, as well as our associate editor Dr Mark Link from UT Southwestern.                                                 Sanjay, please let us know what you did and what you found. Dr Sanjay Sharma:            Well as you rightly say, that up to 25% of black athletes have t-wave inversion, as do three to five percent of white athletes. And these t-wave inversions often overlap with the sort of patterns that you see in patients with hypertrophic cardiomyopathy and arrhythmogenic cardiomyopathy. For example, 80% of people with hypertrophic cardiomyopathy have t-wave inversion as do 60% of patients with ARVC. Now we know that some ECG patterns, t-wave inversions in V1 to V4 are benign in black patients, but the significance of other ECG patterns is unknown. Cascade screening in family members with cardiomyopathy have shown that t-wave inversion may be the only manifestation of gene inheritance, and there are reports to suggest that some athletes with t-wave inversion do go on to develop overt cardiomyopathy. Now when we investigate the vast majority of our patients with t-wave inversion, these are our athlete patients, we don't actually find anything. But over the past decade, also, these has been major advance in next generation sequencing that allows us to perform genetic testing in a large number of genes that can cause diseases, capable of causing sudden death.                                                 And so, we thought we'd investigate the role of this gene testing in athletes with t-wave inversion. We looked at a hundred, 50 black athletes and 50 white athletes who had t-wave inversion, and we investigated them comprehensively with clinical tests. But we also added in a gene panel looking at 311 genes implicated in six cardiac diseases, notably hypertrophic cardiac myopathy, arrhythmogenic cardiomyopathy, dilated cardiomyopathy, left ventricular non-compaction, long QT syndrome, and the brugada syndrome. We found that 21% of our athletes were then diagnosed with a cardiac disorder capable of causing sudden death, and the vast majority of these people had hypertrophic cardiomyopathy. And this diagnosis was based on clinical evaluation. When we looked at gene testing, we found that gene testing only picked up a problem in 10%. So, the diagnostic yield of gene testing was half that of comprehensive clinical investigation.                                                 When we actually looked at athletes who had nothing wrong with them in clinical investigation, and actually had a gene mutation, we found that only 2.5% of athletes who had t-wave inversion but clinically normal tests, actually had something wrong with them. And our conclusions were that gene testing picks up only half the athletes that clinical testing does, and gene testing is only responsible for identifying 2.5% of athletes with t-wave inversion, where clinical tests are negative. That was the summary of our study in short. We did find that black athletes were less likely to have a positive diagnosis of cardiac myopathy than white athletes, and black athletes are also less likely to have a genetic mutation capable of causing a cardiomyopathy than white athletes. Dr Carolyn Lam:                First and foremost, congratulations on such a beautiful paper, and so wonderfully summarized as well. It really seems to fly in the face, doesn't it? Of the way we've been discussing personalized medicine and saying that we're going to start whole genome sequencing everyone and that's going to provide all the answers for future disease risks. I mean, if I'm not wrong, what your paper is trying to tell us is that at this moment we don't have good examples where genetic testing may trump clinical diagnoses, and in fact we should be still focusing on a comprehensive clinical evaluation of patients and in the absence of a genotype we should learn to question what we're doing in genetic testing. Do you agree with that? Dr Sanjay Sharma:            You couldn't have said that more precisely. As I've said, the diagnostic yield of clinical testing was 21% versus only 10% with genetic testing. The diagnostic yield of pure genetic testing in people with otherwise completely normal findings clinically was only 2.5%. And the other thing that I forgot to tell you was that genetic testing, if we included genetic testing in addition to comprehensive assessment, cost us three times as much as clinical investigation on its own, and had we relied solely on genetics, and nothing else, it would have cost us ten times more than clinical testing. So our cost per making a diagnosis using genetics only would have amounted to $30,000 per condition. Dr Carolyn Lam:                Wow, what a great wake up call. Mark, you've thought a lot about this and in fact there was another paper in this week’s journal that has very complimentary messages. In fact you invited an editorial by Dan Roden, and I really loved his title of it, "Growing Pains in Cardiovascular Genetics." Would you maybe add your thoughts in relation to the other paper, as well as overall? Dr Mark Link:                     Sure. Circulation was very interested in these papers. These are really  ... Now, as Dan Roden says, "Growing pains." Twenty years ago when genetics came out it was looked upon as it was going to completely change our clinical medicine and precision medicine is really relying a lot on genetics. And while ultimately that may be the case, we are in a stage now where the honeymoon is over. And the other paper that was in this same issue was a paper by Hosseini  and colleagues, and it was the Clin Gen paper looking at the Brugada Syndrome abnormalities. Now the Clin Gen is an NIH sponsored group that takes individuals from a number of different institutions and actually gene testing, and tries to provide an independent assessment of the abnormality of genes. Previously is was companies that did this. A company would gene test ... They would look for gene abnormalities, try to link it with clinical disease, and they could basically then do just on their patients. But Clin Gen now is trying to tie all those companies together to get a broad consortion and to look at genetic abnormalities and whether they're truly pathologic, where there's areas of unknown significance, or whether they're truly not pathologic.                                                 So as an example, they took Brugada Syndrome, and they took the different gene abnormalities that have been described from basically different companies and different labs and different institutions, and they looked at the evidence behind the fact that they were truly pathologic, 'cause all 21 genes were defined as pathologic. They found in their independent assessment that only one ended up to be truly pathologic, and the others ones were disputed. And sort of another wakeup call that just because a single company calls a gene pathologic or Brugada Syndrome, does not make it pathologic necessarily. So we all thought these were two very important papers that looked at some of the limitations of genetic testing. We asked Dan Roden, who is really a very accomplished scholar in this field, to provide perspective on this. And I agree, I loved his title, "Growing Pains in Cardiovascular Genetics." And what he did is reviewed the history of genetic testing, and he actually starts before genetic testing and starts with Mendelian genetics, and [inaudible] genetics. And then 23 years ago they started linking that Mendelian genetics to gene abnormalities, especially in diseases such as long QT syndrome and hypertrophic cardiomyopathy.                                                 We've come a tremendous way in diagnosing gene abnormalities and associating them with these underlying cardiac myopathies and hind channel abnormalities. So no one doubts we've come a tremendous way, but there's a long way to go in terms of getting better diagnostic accuracy and really defining where these genetic testing are ultimately going to play out in clinical medicine. So everyone's excited about it, but I think these two papers are two cautionary tales that we do have to remember that genetic testing in 2018 is not the end all and be all. Dr Carolyn Lam:                I love that, cautionary tales. So important. But where do we go from here? What's the take home message for clinicians listening to this today in 2018? I mean is it that perhaps when we do these things we now need to include medical geneticists and genetic counselors as vital partners as we look at this all? Perhaps we need to not forget the primacy of clinical evaluation. What do you think, Sanjay? Dr Sanjay Shar:                  Well, there are guidelines from the American Medical Genetics side as to what one defines as a disease-causing mutation. But I agree that we need to be using certified laboratories that can actually interpret the genetic mutations. For example, in our study of athletes, 63% actually had variance of undetermined significance. So they had spinning mistakes in their genes which probably didn't account to anything at all, but had these mutations, or these so called variance of undetermined mutations been interpreted by someone who didn't really know much about this, these could have resulted in false positive results which could cause absolute chaos for an athletes career. So I do think this type of testing has to be governed very, very carefully and needs to be performed in very specialized and certified laboratories. Dr Carolyn Lam:                Indeed. Not just to the athlete, but to their families too, isn't it? Mark, what do you think is the take home message [inaudible 00:16:18]? Dr Mark Link:                     I think one of the big take home messages that I took away from these papers is that clinical medicine is not dead. In fact, clinical medicine in this day and age is still the prime way of taking care of patients. Genetic testing is still in its infancy. It doesn't help clinically in too many situations yet. It will in the future. It helps in the diagnosis, it's not as useful in the treatment. So we have a long ways to go with genetics. I like your comment that going forward we're going to need more genetic counselors to make sense of these results. Clinicians are going to have a hard time making sense of these results. I do think that there is plenty of role once a disease causing mutation has been defined, and in that situation it's invaluable in cascade screening in identifying other family members who may be affected, but outside that I do believe and I agree completely with both of you, that clinical medicine is not dead. And clinical evaluation should be number one and should enjoy it's prime time because that's where we still are at. And genetics is still in its infancy and so is cardiology. Dr Carolyn Lam:                Perhaps in selective settings ... We're not talking here about, for example, hypercholesteremia variance, we're not talking about cancer gene variance for which screening may be a little bit more advanced, and we may understand the gene phenotype associations that are perhaps- Dr Mark Link:                     I think that understanding gene phenotype associations are going to be critically important in the future. I think, as Sanjay said, the real use of genetic screening now is cascade screening for the family, and there it's invaluable. That you can tell if you've got a co-band with the disease, and with a defined pathological mutation. You can test siblings, sons and daughters, parents to see if any of them have the gene. I think that's where it should be used for sure in 2018. Dr Carolyn Lam:                Thank you so much Mark and Sanjay. So some precautions, some hope. Very, very balanced discussion. So much more we could discuss, so I really want to highly encourage our audience. Pick up this issue. You have to read these amazing papers and the editorials. Dr Carolyn Lam:                So, here's a podcast with all your colleagues, and don't forget to tune in next week.  

Cancer-associated fibroblasts lay the tracks for directional migration Cancer-associated fibroblasts, or CAFs, regulate tumor progression by secreting chemokines and remodeling the extracellular matrix. Erdogan et al. reveal that the CAF-dependent alignment of fibronectin promotes directional cancer cell migration. This biosights episode presents the paper by Erdogan et al. from the November 6th, 2017, issue of The Journal of Cell Biology and includes an interview with two of the paper's authors, Begum Erdogan and Mingfang Ao (Vanderbilt University, Nashville, TN). Produced by Caitlin Sedwick and Ben Short. See the associated paper in JCB for details on the funding provided to support this original research. Subscribe to biosights via iTunes or RSS View biosights archive The Rockefeller University Press biosights@rockefeller.edu

WFIRM talks to Richard Clark, MD about the development of peptide P12 for burn wound treatment.

Thu, 3 Jul 2014 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/17146/ https://edoc.ub.uni-muenchen.de/17146/1/Gibson_Josefine.pdf Gibson, Josefine ddc:540, ddc:500, Fakultät für

Yong Ho Bae and Richard Assoian discuss a signaling pathway that causes cells to stiffen their cytoskeletons and proliferate when placed on stiff substrates.

Thu, 21 Nov 2013 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/16317/ https://edoc.ub.uni-muenchen.de/16317/1/Markwardt_Daniel.pdf Markwardt, Daniel

Andrés F. Muro, ICGEB, Mouse Molecular Genetics, Group Leader Trieste - ITALY speaks on "Fibronectin and Ugt1 mutant mouse strains: the function of splice variants, the mechanisms of disease and possible therapeutic approaches". This seminar has been recorded at ICTP Trieste by ICGEB Trieste

In der vorliegenden Untersuchung wurde das Gewebe der Zahnpulpa des Schweines im Vergleich mit der Pulpa von Zähnen des Menschen mit verschiedenen histologischen, histochemischen, immunhistochemischen und elektronenmikroskopischen Methoden untersucht. Zahnpulpa von Mensch und Schwein sind sehr ähnlich aufgebaut und bestehen aus verzweigten Fibroblasten und reich entwickelter Matrix, in der erstaunlich viele Blutgefäße und auch Nerven vorkommen. Kleine Unterschiede zwischen den zwei Säugetierarten, wie z.B. vermehrter Kollagengehalt beim Menschen, hängen vermutlich damit zusammen, dass das untersuchte Material vom Menschen mindestens 30 Jahre alten Zähnen entstammte, wohingegen das Material vom Schwein maximal 2 Jahre alten Zähnen entstammte. Beim Schwein wurden keine konstanten Unterschiede im Aufbau der Zahnpulpa von Milch- und Dauerzähnen beobachtet. Die Matrix der Pulpa enthält ein dichtes dreidimensionales Netzwerk aus meistens feinen Kollagenfasern. In der Pulpaperipherie und in der Umgebung von Arterien bzw. Arteriolen und Nerven sind Kollagenfasern besonders konzentriert. Immunhistochemisch bestehen diese Fasern aus Kollagen vom Typ III und Kollagen vom Typ I. Typische retikuläre Fasern lassen sich lichtmikroskopisch nur unbefriedigend und wohl nur teilweise mit den histologischen Silberimprägnationsmethoden nachweisen. Elastische Fasern fehlen in der Matrix. Fibronectin kommt in der gesamten Zahnpulpa vor und ist in der zellreichen Peripherie in reicherem Maße vertreten als im Zentrum der Pulpa. Die Substrathistochemie (PAS-Reaktion, Alcianblau-Färbung) zeigt, dass die Zahnpulpa in mäßigem Umfang neutrale Glykoproteine, aber in reichem Maße anionische Proteoglykane enthält, deren Glykosaminoglykane mehrheitlich Chondroitinsulfat und Dermatansulfat sind. Decorin (= Decoran) kommt in reichem Maße in einem sehr regelmäßigen Lokalisierungsmuster vor, und verbindet in regelmäßigen Abständen benachbarte Kollagenfibrillen. Das Muster der regelmäßigen Brücken aus Glykosaminoglykanketten zwischen Kollagenfibrillen entspricht dem Konzept der „Shape-modules“, das in Bindegewebstypen mit ganz anderen biomechanischen Funktionen, als sie in der Zahnpulpa herrschen, erarbeitet wurde, und das offenbar ganz universell gilt. S-100 und Neurofilament-Protein markieren gut kleine Nerven. Der kationische kupferhaltige Farbstoff „Cupromeronic Blue“ markiert im elektronenmikroskopischen Präparat scharf die Glykosaminoglykane von Proteoglykanen. In der Matrix kommen kollagen- und nicht-kollagenassoziierte Proteoglykane vor. Das typische kollagenassoziierte Proteoglykan ist das Decoran (= Decorin), das in anderen Bindegeweben an d- und e-Bande und z. T. zusätzlich an die a- und e-Bande der D-Periode der Kollagenfibrillen bindet. Die Bindungsstellen können am Kollagen der Zahnpulpa nicht genau ermittelt werden; es scheint aber ein komplexes dreidimensionales Muster vorzuliegen. Sehr häufig wurden in der Zahnpulpa auf Längsschnitten durch Kollagenfibrillen nur eine Decoran-„Brücke“ pro D-Periode beobachtet. Neben Decoran, das die benachbarten Kollagenfibrillen verbindet bzw. auf Abstand hält, kommen Proteoglykane vor, die ringförmig oder parallel oder schräg zur Längsachse der Kollagenfibrillen verlaufen. Nicht-kollagenassoziierte Proteoglykane kommen in unterschiedlicher Größe und Struktur in der Pulpamatrix vor.

BBK32, a fibronectin (Fn)-binding protein of Borrelia (B.) burgdorferi sensu lato (s.l.) which is encoded by the bbk32 gene located on the 36kb linear plasmid (lp36) of isolate B31, is playing an important role in serological diagnosis of Lyme borreliosis. Firstly, we were interested in the genomic localization of bbk32 regarding different B. burgdorferi s.l. species as well as between strains of the same species. Southern blot analyses based on 23 strains of the species B. burgdorferi sensu stricto (s.s.), B. afzelii, B. garinii and B. spielmanii revealed that position of bbk32 is rather variable between the species but also within a given species. bbk32 could be located on different linear plasmids (lp), mainly on lp23kb, lp24kb, lp25kb, lp31kb and lp36kb. The meaning of this finding remains unclear so far. Secondly, a mumber of thirteen chimeric polypeptides representing different parts of the N-terminal regions of BBK32 proteins of both B. burgdorferi s.s. isolate B31 and B. garinii isolate PHei were generated. Fn-binding capabilities of those generated polypeptides were evaluated either by Western-ligand blot-based binding assay or by enzyme-linked immunosorbent assay (ELISA)-based binding assay. Results showed that BBK32 from PHei possesses a higher Fn-binding capability than that from B31. Furthermore, the higher Fn-binding capacity is associated with four amino acids (Lysine131, Lysine145, Threonine147 and Isoleucine155) in the 32-amino acid-long segment (from position 131 to 162). Moreover, both gelatin and collagen could partially inhibit the binding of BBK32 to Fn. This suggests that BBK32 might also bind to the collagen-binding domain of Fn (repeat I6-9 and II1, 2) and partially to its N-terminal fibrin-binding domain (repeat I1-5). Though the meaning of the different Fn-binding capacities remains unclear so far, such studies may provide us with markers to define the different pathogenic potentials of various Borrelia species and strains. Thirdly, eight recombinantly prepared BBK32 homologues (either as partial or as whole) were tested in a line assay to evaluate their contribution for serologic diagnosis of Lyme borreliosis. Though BBK32 homologues could react with sera from Lyme borreliosis patients, compared with other Borrelia-antigens established in the Max von Pettenkofer Institute, these BBK32 homologues could not improve the sensitivity and specificity of the class-specific IgG or IgM antibody tests. Nevertheless, this study underlines the fact that the heterogeneity of Lyme disease Borrelia species must be taken into consideration in the microbiological diagnosis of Lyme borreliosis in European patients.

Some biliary proteins (pronucleators) seem to be essential factors for cholesterol crystal formation and crystal growth in bile. A recent study suggests that fibronectin is such a pronucleator in bile. Fibronectin also seems to closely interact with intestinal mucin. Since biliary mucin plays an important role in gallstone formation, such an interaction in bile may be of relevance in cholesterol gallstone formation. To more clearly elucidate the role of fibronectin in cholesterol gallstone disease, we measured the concentration of fibronectin in native bile of cholesterol gallstone patients and checked its influence on the cholesterol nucleation time of model bile. We further looked for a molecular interaction between biliary fibronectin and gallbladder mucin. We found that fibronectin is present in gallbladder bile of gallstone patients in low concentrations (2.6 +/- 1.2 micrograms/ml). Bile fibronectin did not interact with gallbladder mucin. Moreover, in a wide range of concentrations fibronectin had no influence on the nucleation time of model bile. We conclude that fibronectin does not seem to play a major role in cholesterol gallstone disease.

The binding of bacteria or bacterial products to host proteins of tissue extracellular matrix may be a mechanism of tissue adherence. We investigated interactions of the plasmid-encoded outer membrane protein YadA, which confers pathogenic functions on enteropathogenic yersiniae, with fibronectin. Attachment of YadA-positive and YadA-negative recombinant Yersinia enterocolitica strains to cartilage-derived human cellular fibronectin and human plasma fibronectin in the solid phase revealed that YadA mediates binding of yersiniae to cellular fibronectin in a saturable, concentration-dependent manner. The interaction could be inhibited by an anti-YadA-specific anti-serum. An anti-beta 1-integrin antibody and the synthetic peptide G-R-G-D-S-P, representing the binding site for alpha 5 beta 1-integrin on fibronectin, did not block attachment of YadA-positive yersiniae to cellular fibronectin, indicating a binding site for YadA on cellular fibronectin independent of the R-G-D-S-containing site. By contrast, YadA failed to mediate binding to plasma fibronectin immobilized on nitrocellulose or plastic surfaces. These observations provide evidence for the hypothesis that the binding region for YadA in cellular fibronectin is not present in plasma fibronectin. This study is the first report on differential binding of bacteria to splicing variants of fibronectin. Further experiments might answer the question whether binding of YadA to cellular fibronectin contributes to the pathogenesis of yersiniae, both to the initial adhesion of the bacteria to the matrices of the host and to the arthritogenic potential of enteropathogenic yersiniae.

Fri, 1 Jan 1993 12:00:00 +0100 https://epub.ub.uni-muenchen.de/7483/1/eisenmenger_wolfgang_7483.pdf Eisenmenger, Wolfgang; Penning, R.; Tübel, J.; Wilske, J.; Nerlich, A.; Betz, P.

Fibronectin, collagen type III, laminin, and cytokeratin 5 were visualized in normal skin and in skin showing early or advanced signs of autolytic decomposition to prove whether the immunohistochemical analysis of these antigens can provide useful information for an age-estimation of skin wounds obtained from putrified corpses. In cases with early signs of decomposition (visible course of veins, greenish discoloration) and without microscopic alterations like relaxation of the epidermal cell layers or destruction of the blood vessel structures, the staining pattern was identical to that found in normal, non-putrefied skin. In skin already showing microscopic alteration of the tissue structure, fibronectin and collagen type III could not be localized unambiguously. The distribution of laminin and cytokeratin 5, however, was well preserved. In advanced putrefied skin no reliable staining results could be obtained for fibronectin, collagen type III, and laminin. Even though cytokeratin 5 was still detectable in remnants of decomposition-resistant skin appendages, no information useful for an age-estimation of skin wounds can be obtained due to the autolytic detachment of the epidermal layers.

We analyzed the distribution of fibronectin in routinely embedded tissue specimens from 53 skin wounds and 6 postmortem wounds. In postmortem wounds a faint but focal positive staining was exclusively found at the margin of the specimens which dit not extend into the adjacent stroma. Vital wounds were classified into 3 groups. The first comprising lesions with wound ages ranging from a few seconds to 30 min, the second comprising those with wound ages upt to 3 weeks, and the third group with lesions more than 3 weeks old. Ten out of 17 lesions with a wound age up to 30 min showed a clear positive reaction within the wound area. Three specimens in this group were completely negative, while in 4 additional cases the result was not significantly different from postmortem lesions. These 7 cases were characterized by acute death with extremely short survival times (only seconds). In wounds up to 3 weeks old fibronectin formed a distinct network containing an increasing number of inflammatory cells corresponding to the wound age. In 2 cases with a survival time of 17 days and in all wounds older than 3 weeks fibronectin was restricted to the surface of fibroblasts and to parallel arranged fibers in the granulation tissue without any network structures. We present evidence that fibronectin is a useful marker for vital wounds with a survival time of more than a few minutes. Fibronectin appears before neutrophilic granulocytes migrate into the wound area. Since a faint positive fibronectin staining is seen in postmortem lesions and bleedings, we propose that only those wounds which show strong positive fibronectin staining also extending into the adjacent stroma should be regarded as vital.

Mon, 1 Jan 1990 12:00:00 +0100 https://epub.ub.uni-muenchen.de/5907/1/5907.pdf Jüngst, Dieter; Mezger, J.; Xie, Yining; Gerbes, Alexander L. ddc:610, Medizin