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排序方式: 共有114条查询结果,搜索用时 171 毫秒
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Claudia Merkwitz Orest W. Blaschuk Angela Schulz Paul Lochhead Jaroslawna Meister Angela Ehrlich Albert M. Ricken 《Progress in histochemistry and cytochemistry》2013
Islets form in the pancreas after the first endocrine cells have arisen as either single cells or small cell clusters in the epithelial cords. These cords constitute the developing pancreas in one of its earliest recognizable stages. Islet formation begins at the time the cords transform into a branching ductal system, continues while the ductal system expands, and finally stops before the exocrine tissue of ducts and acini reaches its final expansion. Thus, islets continuously arise from founder cells located in the branching and ramifying ducts. Islets arising from proximal duct cells locate between the exocrine lobules, develop strong autonomic and sensory innervations, and pass their blood to efferent veins (insulo-venous efferent system). Islets arising from cells of more distal ducts locate within the exocrine lobules, respond to nerve impulses ending at neighbouring blood vessels, and pass their blood to the surrounding acini (insulo-acinar portal system). Consequently, the section of the ductal system from which an islet arises determines to a large extent its future neighbouring tissue, architecture, properties, and functions. We note that islets interlobular in position are frequently found in rodents (rats and mice), whereas intralobularly-located, peripheral duct islets prevail in humans and cattle. Also, we expound on bovine foetal Laguesse islets as a prominent foetal type of type 1 interlobular neuro-insular complexes, similar to neuro-insular associations frequently found in rodents. Finally, we consider the probable physiological and pathophysiological implications of the different islet positions within and between species. 相似文献
3.
Annett Sandner Juliane Illert Sabine Koitzsch Susanne Unverzagt Ilona Schön 《Experimental cell research》2013
Gastroesophageal reflux disease has been implicated in the pathogenesis of adenocarcinoma of the oesophagus. The same applies to laryngopharyngeal reflux (LPR) and squamous cell cancer of the head and neck, but so far, this link has not been proven. The impact of low pH and bile acids has not been studied extensively in cells other than oesophageal cancer cell lines and tissue. The aims of this study were to investigate the pathogenic potential of reflux and its single components on the mucosa of the upper respiratory tract. We measured DNA stability in human miniorgan cultures (MOCs) and primary epithelial cell cultures (EpCs) in response to reflux by the alkaline comet assay. As matrix metalloproteinases (MMPs) are involved in extracellular matrix remodelling processes and may contribute to cancer progression, we studied the expression of MMP1, -9, and -14 in MOCs, EpC, UM-SCC-22B, and FADUDD. DNA strand breaks (DNA-SBs) increased significantly at low pH and after incubation with human or artificial gastric juice. Single incubation with glycochenodeoxycholic acid also showed a significant increase in DNA-SBs. In epithelial cell cultures, human gastric juice increased the number of DNA-SBs at pH 4.5 and 5.5. Artificial gastric juice significantly up regulated the gene expression of MMP9. Western blot analysis confirmed the results of gene expression analysis, but the up regulation of MMP1, -9, and -14 was donor-specific. Reflux has the ability to promote genomic instability and may contribute to micro environmental changes suitable for the initiation of malignancy. Further functional gene analysis may elucidate the role of laryngopharyngeal reflux in the development of head neck squamous cell carcinoma (HNSCC). 相似文献
4.
Can-Jie Guo Qin Pan Hua Xiong Yu-Qi Qiao Zhao-Lian Bian Wei Zhong Li Sheng Hai Li Lei Shen Jing Hua Xiong Ma Jing-Yuan Fang 《FEBS letters》2013
In our previous study, miR-126 was identified as one of the leading miRNAs that is downregulated during activation of hepatic stellate cells (HSCs). However, the roles and related mechanisms of miR-126 in HSCs are not understood. In this study, we compared expression of miR-126 during HSC activation both in vitro and in vivo. We also applied RNA interference to analyze the role and mechanism of miR-126∗ in the activation of HSCs. Restoring HSCs with Lv-miR-126∗ resulted in decreased proliferation, accumulation of extracellular matrix components, and cell contraction, while also negatively regulating the vascular endothelial growth factor (VEGF) signal transduction pathways by partially targeted VEGF-A. Thus, we postulate that miR-126 may be a biological marker for the activation of HSCs, and useful for reducing intrahepatic vascular resistance and improving the sinusoidal microcirculation in chronic liver diseases. 相似文献
5.
Jiang-guo ZHANG Xiao-min QIN Xiao-jing WANG Wei-ming YAN Chuan-long ZHU Xiao-ping LUO Qin NING 《Virologica Sinica》2007,22(5):339-346
To study the contribution of T cell subsets in the pathogenesis of Murine hepatitis virus Type 3(MHV-3) induced chronic viral hepatitis in C3H/Hej mice,ninety C3H/Hej mice were chosen to individually receive 10 plaque forming units(PFU)of MHV-3 intraperitoneally.The changes of virus titer and pathology in liver tissue were examined by standard plaque assay and by the hematoxylin/eosin(HE) staining method from 2 days post MHV-3 infection.The ratios of T cell subsets including CD3 CD4 CD8-,CD3 CD4-CD8 ,CD3 CD4-CD8-,CD3 CD4 CD25 ,CD3 CD4 CD25-and CD3 CD4-CD25 T lymphocyte of total T lymphocytes in blood,spleen and liver were examined at 0,2,4,6,8,10,12,15,20,25,30,40 days post MHV-3 infection by flow cytosorting.We observed that the virus titer raised and showed persistent virus duplications and inflammatory changes in the livers of C3H/Hej mice from 2 days post MHV-3 infection.The double negative T cell(DN Treg cell) and CD4 CD25 T cell ratios increased significantly from 2 days post MHV-3 infection in C3H/Hej mice,and CD3 CD4 CD8-,CD3 CD4-CD8 ,CD3 CD4 CD25-and CD3 CD4-CD25 T cell ratios decreased accordingly.In conclusion,the changes of virus titer and pathology in the livers of C3H/Hej mice post MHV-3 suggest their contribution to viral persistence.Further characterizations of DN Treg cells are that infection indicates that MHV-3 could induce the chronic inflammation in livers of C3H/Hej mice.The increase of the DN Treg cell and CD4 CD25 T cell ratios in C3H/Hej mice post MHV-3 infection suggests that DN Treg cells and CD4 CD25 T cells may both have important suppressive immunomodulation functions in the development of chronic viral hepatitis and have important roles in the virus persistent infection.Further characterizations of DNT cell and CD4 CD25 T cell are under investigation. 相似文献
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Chameleon sequences have been implicated in amyloid related diseases. Here we report an analysis of two types of chameleon sequences, chameleon-HS (Helix vs. Strand) and chameleon-HE (Helix vs. Sheet), based on known structures in Protein Data Bank. Our survey shows that the longest chameleon-HS is eight residues while the longest chameleon-HE is seven residues. We have done a detailed analysis on the local and global environment that might contribute to the unique conformation of a chameleon sequence. We found that the existence of chameleon sequences does not present a problem for secondary structure prediction programs, including the first generation prediction programs, such as Chou-Fasman algorithm, and the third generation prediction programs that utilize evolution information. We have also investigated the possible implication of chameleon sequences in structural conservation and functional diversity of alternatively spliced protein isoforms. 相似文献
8.
Wild and tissue cultured plants of Portulaca grandiflora Hook. have shown to be able to decolorize a sulfonated diazo dye Navy Blue HE2R (NBHE2R) up to 98% in 40 h. A significant induction in the activities of lignin peroxidase, tyrosinase and DCIP reductase was observed in the roots during dye decolorization. The wild plants and tissue cultures could independently decolorize and degrade NBHE2R into metabolites viz. N-benzylacetamide and 6-diazenyl-4-hydroxynaphthalene-2-sulfonic acid. A dye mixture and a textile effluent were also decolorized efficiently by P. grandiflora. The phytotoxicity study revealed reduction in the toxicity due to metabolites formed after dye degradation. 相似文献
9.
We investigated the possible role of prostaglandins produced by COX-2 in the immunosuppression observed during Trypanosoma cruzi infection. Con-A-stimulated splenocytes isolated from mice on days 5, 10, and 15 of infection released large amounts of PGE2 and this release was inhibited by the treatment of animals with sodium salicylate or meloxicam. The treatment of the animals with these drugs enhanced the release of IL-2 by splenocytes from T. cruzi-infected animals and significantly reduced the blood parasitemia and delayed the mortality of the infected mice. Furthermore, the release of TNF-alpha, IFN-gamma, IL-4, and IL-10 by Con-A-stimulated splenocytes obtained from infected mice on days 5, 10, and 15 of the infection was significantly inhibited by treatment of the animals with salicylate or meloxicam. In conclusion, the results suggest that the prostaglandins produced mainly by COX-2 mediate the immunosuppression observed in the acute phase of T. cruzi infection. 相似文献
10.
Structure of the house dust mite allergen Der f 2: implications for function and molecular basis of IgE cross-reactivity 总被引:4,自引:0,他引:4
Johannessen BR Skov LK Kastrup JS Kristensen O Bolwig C Larsen JN Spangfort M Lund K Gajhede M 《FEBS letters》2005,579(5):1208-1212
The X-ray structure of the group 2 major allergen from Dermatophagoides farinae (Der f 2) was determined to 1.83 A resolution. The overall Der f 2 structure comprises a single domain of immunoglobulin fold with two anti-parallel beta-sheets. A large hydrophobic cavity is formed in the interior of Der f 2. Structural comparisons to distantly related proteins suggest a role in lipid binding. Immunoglobulin E (IgE) cross-reactivity between group 2 house dust mite major allergens can be explained by conserved surface areas representing IgE binding epitopes. 相似文献