Juxtaparanodal clustering of Shaker-like K+ channels in myelinated axons depends on Caspr2 and TAG-1

In myelinated axons, K+ channels are concealed under the myelin sheath in the juxtaparanodal region, where they are associated with Caspr2, a member of the neurexin superfamily. Deletion of Caspr2 in mice by gene targeting revealed that it is required to maintain K+ channels at this location. Furthermore, we show that the localization of Caspr2 and clustering of K+ channels at the juxtaparanodal region depends on the presence of TAG-1, an immunoglobulin-like cell adhesion molecule that binds Caspr2. These results demonstrate that Caspr2 and TAG-1 form a scaffold that is necessary to maintain K+ channels at the juxtaparanodal region, suggesting that axon–glia interactions mediated by these proteins allow myelinating glial cells to organize ion channels in the underlying axonal membrane

Substrate Micropatterning as a New in Vitro Cell Culture System to Study Myelination

Artículo de publicación ISIMyelination is a highly regulated developmental process whereby oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system ensheathe axons with a multilayered concentric membrane. Axonal myelination increases the velocity of nerve impulse propagation. In this work, we present a novel in vitro system for coculturing primary dorsal root ganglia neurons along with myelinating cells on a highly restrictive and micropatterned substrate. In this new coculture system, neurons survive for several weeks, extending long axons on defined Matrigel tracks. On these axons, myelinating cells can achieve robust myelination, as demonstrated by the distribution of compact myelin and nodal markers. Under these conditions, neurites and associated myelinating cells are easily accessible for studies on the mechanisms of myelin formation and on the effects of axonal damage on the myelin sheath.Regenerative Medicine and Nanomedicine Initiative of the Canadian Institutes of Health Research (CIHR) RMF-7028 FONDECYT 1080252 CIHR Ministry of Industry of Canada Rio Tinto Alcan Molson Foundatio

The Tumor Suppressor PRDM5 Regulates Wnt Signaling at Early Stages of Zebrafish Development

PRDM genes are a family of transcriptional regulators that modulate cellular processes such as differentiation, cell growth and apoptosis. Some family members are involved in tissue or organ maturation, and are differentially expressed in specific phases of embryonic development. PRDM5 is a recently identified family member that functions as a transcriptional repressor and behaves as a putative tumor suppressor in different types of cancer. Using gene expression profiling, we found that transcriptional targets of PRDM5 in human U2OS cells include critical genes involved in developmental processes, and specifically in regulating wnt signaling. We therefore assessed PRDM5 function in vivo by performing loss-of-function and gain-of-function experiments in zebrafish embryos. Depletion of prdm5 resulted in impairment of morphogenetic movements during gastrulation and increased the occurrence of the masterblind phenotype in axin+/− embryos, characterized by the loss of eyes and telencephalon. Overexpression of PRDM5 mRNA had opposite effects on the development of anterior neural structures, and resulted in embryos with a shorter body axis due to posterior truncation, a bigger head and abnormal somites. In situ hybridization experiments aimed at analyzing the integrity of wnt pathways during gastrulation at the level of the prechordal plate revealed inhibition of non canonical PCP wnt signaling in embryos overexpressing PRDM5, and over-activation of wnt/β-catenin signaling in embryos lacking Prdm5. Our data demonstrate that PRDM5 regulates the expression of components of both canonical and non canonical wnt pathways and negatively modulates wnt signaling in vivo

Діагностичні та лікувальні підходи при ехінококозі печінки

The purpose of the study was to improve the results of surgical treatment for echinococcosis of the liver and the quality of life of operated patients due to the improvement of diagnostic and therapeutic approaches, prevention of postoperative complications and recurrence of the disease. 22 patients were treated for echinococcosis of the liver. The duration of the operation was 2 hours in case of echinococcectomy with atypical resection of the liver, in case of laparoscopic echinococcectomy ‒ 1.2 hours, in case of puncture aspiration injection reaspiration technique ‒ 40 minutes. No fatal cases were observed. Recurrence of the disease was found in 9.1 %. A radical and effective operation is atypical resection of a part of the liver with an echinococcal cyst. Laparoscopic echinococcectomy is an alternative to open atypical resection of a part of the liver with an echinococcal cyst. The main condition for performing puncture aspiration injection reaspiration under ultrasound and X ‒ ray guidance is the absence of cystobiliary fistulae, since instillation of a cyst with a scolicidal solution can be the cause of sclerosing cholangitis. The anti-relapse antiparasitic therapy with albendazole 10‒15 mg/kg body weight twice a day or mebendazole 40‒50 mg/kg body weight three times a day in three 28-day courses with a break of 14 days should be carried out for 3‒6 months in the postoperative period.Метою дослідження було покращити результати хірургічного лікування при ехінококозі печінки та якості життя оперованих хворих за рахунок вдосконалення діагностично‒лікувальних підходів, профілактики післяопераційних ускладнень і рецидиву хвороби. На лікуванні з приводу ехінококозу печінки знаходилось 22 хворих. При ехінококектомії з атиповою резекцією печінки тривалість операції склала 2 години, при лапароскопічній ехінококектомії ‒ 1,2 години, при методиці PAIR ‒ 40 хв. Летальних випадків на спостерігали. Рецидив захворювання виявлено у 9,1 %. Радикальною і ефективною операцією є атипова резекція частини печінки з ехінококовою кістою. Лапароскопічна ехінококектомія є альтернативою відкритій атиповій резекції частини печінки з ехінококовою кістою. Головною умовою виконання puncture aspiration injection reaspiration під УЗ та рентген‒ навігацією є відсутність цистобіліарних нориць, так як інстиляція кісти сколіцидним розчином може бути причиною склерозуючого холангіту. У післяопераційному періоді на протязі 3‒6 місяців слід проводити протирецидивну антипаразитарну терапію альбендазолом по 10‒15 мг/кг ваги двічі на день або мебендазолом по 40‒50 мг/кг ваги тричі на день трьома 28‒ денними курсами з перервою 14 днів

A Claudin-9–Based Ion Permeability Barrier Is Essential for Hearing

Hereditary hearing loss is one of the most common birth defects, yet the majority of genes required for audition is thought to remain unidentified. Ethylnitrosourea (ENU)–mutagenesis has been a valuable approach for generating new animal models of deafness and discovering previously unrecognized gene functions. Here we report on the characterization of a new ENU–induced mouse mutant (nmf329) that exhibits recessively inherited deafness. We found a widespread loss of sensory hair cells in the hearing organs of nmf329 mice after the second week of life. Positional cloning revealed that the nmf329 strain carries a missense mutation in the claudin-9 gene, which encodes a tight junction protein with unknown biological function. In an epithelial cell line, heterologous expression of wild-type claudin-9 reduced the paracellular permeability to Na+ and K+, and the nmf329 mutation eliminated this ion barrier function without affecting the plasma membrane localization of claudin-9. In the nmf329 mouse line, the perilymphatic K+ concentration was found to be elevated, suggesting that the cochlear tight junctions were dysfunctional. Furthermore, the hair-cell loss in the claudin-9–defective cochlea was rescued in vitro when the explanted hearing organs were cultured in a low-K+ milieu and in vivo when the endocochlear K+-driving force was diminished by deletion of the pou3f4 gene. Overall, our data indicate that claudin-9 is required for the preservation of sensory cells in the hearing organ because claudin-9–defective tight junctions fail to shield the basolateral side of hair cells from the K+-rich endolymph. In the tight-junction complexes of hair cells, claudin-9 is localized specifically to a subdomain that is underneath more apical tight-junction strands formed by other claudins. Thus, the analysis of claudin-9 mutant mice suggests that even the deeper (subapical) tight-junction strands have biologically important ion barrier function

Verification of genes differentially expressed in neuroblastoma tumours: a study of potential tumour suppressor genes

<p>Abstract</p> <p>Background</p> <p>One of the most striking features of the childhood malignancy neuroblastoma (NB) is its clinical heterogeneity. Although there is a great need for better clinical and biological markers to distinguish between tumours with different severity and to improve treatment, no clear-cut prognostic factors have been found. Also, no major NB tumour suppressor genes have been identified.</p> <p>Methods</p> <p>In this study we performed expression analysis by quantitative real-time PCR (QPCR) on primary NB tumours divided into two groups, of favourable and unfavourable outcome respectively. Candidate genes were selected on basis of lower expression in unfavourable tumour types compared to favourables in our microarray expression analysis. Selected genes were studied in two steps: (1) using TaqMan Low Density Arrays (TLDA) targeting 89 genes on a set of 12 NB tumour samples, and (2) 12 genes were selected from the TLDA analysis for verification using individual TaqMan assays in a new set of 13 NB tumour samples.</p> <p>Results</p> <p>By TLDA analysis, 81 out of 87 genes were found to be significantly differentially expressed between groups, of which 14 have previously been reported as having an altered gene expression in NB. In the second verification round, seven out of 12 transcripts showed significantly lower expression in unfavourable NB tumours, <it>ATBF1</it>, <it>CACNA2D3</it>, <it>CNTNAP2</it>, <it>FUSIP1</it>, <it>GNB1</it>, <it>SLC35E2</it>, and <it>TFAP2B</it>. The gene that showed the highest fold change in the TLDA analysis, <it>POU4F2</it>, was investigated for epigenetic changes (CpG methylation) and mutations in order to explore the cause of the differential expression. Moreover, the fragile site gene <it>CNTNAP2 </it>that showed the largest fold change in verification group 2 was investigated for structural aberrations by copy number analysis. However, the analyses of <it>POU4F2 </it>and <it>CNTNAP2 </it>showed no genetic alterations that could explain a lower expression in unfavourable NB tumours.</p> <p>Conclusion</p> <p>Through two steps of verification, seven transcripts were found to significantly discriminate between favourable and unfavourable NB tumours. Four of the transcripts, <it>CACNA2D3</it>, <it>GNB1</it>, <it>SLC35E2</it>, and <it>TFAP2B</it>, have been observed in previous microarray studies, and are in this study independently verified. Our results suggest these transcripts to be markers of malignancy, which could have a potential usefulness in the clinic.</p

Genomic microsatellites identify shared Jewish ancestry intermediate between Middle Eastern and European populations

<p>Abstract</p> <p>Background</p> <p>Genetic studies have often produced conflicting results on the question of whether distant Jewish populations in different geographic locations share greater genetic similarity to each other or instead, to nearby non-Jewish populations. We perform a genome-wide population-genetic study of Jewish populations, analyzing 678 autosomal microsatellite loci in 78 individuals from four Jewish groups together with similar data on 321 individuals from 12 non-Jewish Middle Eastern and European populations.</p> <p>Results</p> <p>We find that the Jewish populations show a high level of genetic similarity to each other, clustering together in several types of analysis of population structure. Further, Bayesian clustering, neighbor-joining trees, and multidimensional scaling place the Jewish populations as intermediate between the non-Jewish Middle Eastern and European populations.</p> <p>Conclusion</p> <p>These results support the view that the Jewish populations largely share a common Middle Eastern ancestry and that over their history they have undergone varying degrees of admixture with non-Jewish populations of European descent.</p

Claudin 13, a Member of the Claudin Family Regulated in Mouse Stress Induced Erythropoiesis

Mammals are able to rapidly produce red blood cells in response to stress. The molecular pathways used in this process are important in understanding responses to anaemia in multiple biological settings. Here we characterise the novel gene Claudin 13 (Cldn13), a member of the Claudin family of tight junction proteins using RNA expression, microarray and phylogenetic analysis. We present evidence that Cldn13 appears to be co-ordinately regulated as part of a stress induced erythropoiesis pathway and is a mouse-specific gene mainly expressed in tissues associated with haematopoietic function. CLDN13 phylogenetically groups with its genomic neighbour CLDN4, a conserved tight junction protein with a putative role in epithelial to mesenchymal transition, suggesting a recent duplication event. Mechanisms of mammalian stress erythropoiesis are of importance in anaemic responses and expression microarray analyses demonstrate that Cldn13 is the most abundant Claudin in spleen from mice infected with Trypanosoma congolense. In mice prone to anaemia (C57BL/6), its expression is reduced compared to strains which display a less severe anaemic response (A/J and BALB/c) and is differentially regulated in spleen during disease progression. Genes clustering with Cldn13 on microarrays are key regulators of erythropoiesis (Tal1, Trim10, E2f2), erythrocyte membrane proteins (Rhd and Gypa), associated with red cell volume (Tmcc2) and indirectly associated with erythropoietic pathways (Cdca8, Cdkn2d, Cenpk). Relationships between genes appearing co-ordinately regulated with Cldn13 post-infection suggest new insights into the molecular regulation and pathways involved in stress induced erythropoiesis and suggest a novel, previously unreported role for claudins in correct cell polarisation and protein partitioning prior to erythroblast enucleation

Organization of multiprotein complexes at cell–cell junctions

The formation of stable cell–cell contacts is required for the generation of barrier-forming sheets of epithelial and endothelial cells. During various physiological processes like tissue development, wound healing or tumorigenesis, cellular junctions are reorganized to allow the release or the incorporation of individual cells. Cell–cell contact formation is regulated by multiprotein complexes which are localized at specific structures along the lateral cell junctions like the tight junctions and adherens junctions and which are targeted to these site through their association with cell adhesion molecules. Recent evidence indicates that several major protein complexes exist which have distinct functions during junction formation. However, this evidence also indicates that their composition is dynamic and subject to changes depending on the state of junction maturation. Thus, cell–cell contact formation and integrity is regulated by a complex network of protein complexes. Imbalancing this network by oncogenic proteins or pathogens results in barrier breakdown and eventually in cancer. Here, I will review the molecular organization of the major multiprotein complexes at junctions of epithelial cells and discuss their function in cell–cell contact formation and maintenance

Endoscopic Surgery in Trachea and Bronchi

Эндоскопические операции (ЭО) прочно вошли в арсенал торакальной хирургии как метод паллиативного лечения рака легкого и малоинвазивного радикального лечения ряда доброкачественных заболеваний трахеи и крупных бронхов. Среди различных методик ЭО наибольшее распространение получили методы лазерной и электрохирургической реканализации дыхательных путей. Накопленный в клинике 25-летний опыт ЭО при ряде заболеваний трахеобронхиального дерева позволил поделиться им в настоящем сообщении.Experience in 1623 endoscopic operations in 976 patients with tumors and cicatricle stenosis of trachea and bronchi has been carried out. The results of endoscopic operations with the use of AIG-laser rays and electrosurgical methods have been analyzed. Improvement in the bronchial passage was achieved in 85% of the patients. Complications were seen in 3% of cases, death was registered in 15 (1.5%) during the process of treatment. In case of tumorous stenosis, endoscopic recanalization brought rough palliative character enhanced the quality of daily life