P-glycoprotein regulating biphasic insulin secretion in rat pancreatic beta cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>A 65-kD mdr1 (multi-drug resistance protein 1, P-glycoprotein)-like protein has been suggested to be the regulatory protein to the chloride channel protein 3 (ClC-3) mediating insulin granules acidification and release in mouse pancreatic beta cells. But the protein has not been deeply investigated. In this study, we identified existence of the 65-kda protein in rat islets and preliminarily explored its biological functions.</p><p><b>METHODS</b>Total RNAs of rat kidneys served as positive controls, and pancreas, islets and INS-1 cells were extracted for reverse-transcript PCR (RT-PCR), respectively. The cDNAs were run with specific primers selected from the mRNA of abcb1b encoding P-glycoprotein. All PCR products were visualized in agarose gel electrophoresis and sequenced. Homogenates of rat islets and INS-1 cells were applied to SDS-PAGE. P-glycoprotein was detected by a specific monoclonal antibody, C219. Biphasic insulin release was measured in static incubations of rat islets with radioimmunology assay.</p><p><b>RESULTS</b>Compared with positive control, expression of the P-glycoprotein mRNA segments were detected in the islets, INS-1 cells and pancreas. Sequence analysis confirmed that the PCR products were matched with mRNA of P-glycoprotein. A 65-kda protein was recognized by the antibody in the islets homogenate but not in that of INS-1 cells in Western-blotting. Instead, the homogenate of INS-1 cells contained a 160-kda protein recognized by the antibody. Insulin secretion of rat islets were stimulated by high glucose (16.7 mmol/L), and showed biphasic curve during 60-minute incubation. After co-incubation with cyclosporine A (CsA), specific inhibitor to P-glycoprotein, the second phase of insulin secretion was reduced significantly while the first phase was not influenced.</p><p><b>CONCLUSIONS</b>The 65-kda protein expressed in rat islets is most likely a mini-P-glycoprotein. It may play a key role regulating biphasic insulin release.</p>

Adaptive changes of ultrastructures of dentritic cells during maturation induced by lipopolysaccharide / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the adaptive changes of ultrastructure of the dentritic cells (DC) before and after maturation.</p><p><b>METHODS</b>The murine bone marrow mononuclear cells were induced into immatured dendritic cells with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). The cell morphology was observed under an inverted phase contrast microscope, and the surface markers were detected by flow cytometry. Then the DC was induced to be matured with lipopolysaccharide (LPS) for 48 hours, the ultrastructures of DC was observed before and after maturation under transmission electron microscope and then a comparative analysis was doned.</p><p><b>RESULTS</b>The surface processes of matured dentritic cells stimulated by LPS decreased significantly, whereas the organelles and the diameter of nucleolus increased.</p><p><b>CONCLUSION</b>The distribution of surface processes may be associated with the antigen-presenting capacity of DC, and it is also a potential ruler of cell function and status.</p>

Effects and mechanism of glucagon-like peptide-1 on injury of rats cardiomyocytes induced by hypoxia-reoxygenation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Although the insulinotropic role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes mellitus has been substantiated, its role in cardioprotection remains largely unknown. This study aimed to determine the effects of GLP-1 on injury of rats cardiac myocytes induced by hypoxia-reoxygenation (H/R) and the possible mechanisms.</p><p><b>METHODS</b>The cultured neonatal rats cardiac myocytes were randomly divided into seven groups: the normal control group, the H/R group, the GLP-1 + H/R group, the GLP-1 + H/R + UO126 (the p42/44 mitogen-activated protein kinase (MAPK) inhibitor) group, the GLP-1 + H/R + LY294002 (phosphatidylinositol 3-kinase (PI3K) inhibitor) group, the H/R + UO126 group, and the H/R + LY294002 group. The lactate dehydrogenase (LDH) activity, apoptosis rate of cardiac myocytes, and caspase-3 activity were detected after the injury of H/R.</p><p><b>RESULTS</b>Compared with the normal control group, the activity of LDH, cardiac myocyte apoptosis rate, and caspase-3 activity all increased significantly in the H/R group (P < 0.01). Compared with the H/R group, these three indices all decreased in the H/R + GLP-1 group (P < 0.01). However, the changes of LDH activity, apoptosis rate, and caspase-3 activity were inhibited by LY294002 and UO126 respectively.</p><p><b>CONCLUSIONS</b>GLP-1 can directly act on cardiac myocytes and protect them from H/R injury mainly by inhibiting their apoptosis. Its mechanism may be through the PI3K-Akt pathway and the MAPK signaling pathway.</p>

Prodrug structural modifications of cyclovirobuxine D and their biological activity / 药学学报

<p><b>AIM</b>To search for compounds for the treatment of cardiovascular diseases through prodrug structural modifications of cyclovirobuxine D, a single efficient composition distilled from Box plant in China, which was used to treat angina and myocardial infarction.</p><p><b>METHODS</b>According to prodrug design principle, a series of cyclovirobuxine D analogues were prepared, suc as succinate, phosphate and amino acid ester, and their biological activities were tested.</p><p><b>RESULTS</b>Seven new compounds were obtained and confirmed with 1H NMR, MS, and element analysis.</p><p><b>CONCLUSION</b>In pharmacology experiment, for treating arrhythmia induced by aconitine, succinate and amino acid ester of cyclovirobuxine D (I and VII) showed better activities than that of cyclovirobuxine D. The normal rhythm of the heart duration of I and VII were ( 11.53 +/- 7.62) min and (12.68 +/- 9.25) min, compared with 0.9% NaCl solution and cyclovirobuxine D, (2.36 +/- 1.68) min and (10.25 +/- 6.59) min (P < 0.01), respectively. Another pharmacology experiment, for treating arrhythmia induced by chloroform, the negative ratio of I and VII were 80% and 82%, compared with 0.9% NaCl solution and cyclovirobuxine D, 43% and 52% (P < 0.05), respectively. The difference between new compounds and cyclovirobuxine D was distinct.</p>

Structural modification and bioactivity of cyclovirobuxine D / 药学学报

<p><b>AIM</b>To search for new compounds for the treatment of cardiovascular diseases by structural modification of cyclovirobuxine D.</p><p><b>METHODS</b>According to rational drug design principle, a series of cyclovirobuxine D analogues were prepared, and their bioactivities were tested.</p><p><b>RESULTS</b>Ten new compounds were syntheized and confirmed by spectra.</p><p><b>CONCLUSION</b>Endurance lacking oxygen activity and antiarrhythmia effects of some analogues of cyclovirobuxine D were tested. Some compounds showed better activity than cyclovirobuxine D.</p>