Platelet-activating factor increases mucosal permeability in rat intestine via tyrosine phosphorylation of E-cadherin

1. Platelet-activating factor (PAF), an inflammatory mediator, plays an important role in mediating intestinal injury. However, it remains unclear whether PAF has a function in the intestine. The production of PAF by normal intestine and by unstimulated intestinal epithelial cell lines suggests that PAF may have a regulatory function in the normal bowel. 2. In this study we investigated the role of PAF in modulating intestinal mucosal permeability in rats. Lumen-to-blood transit of FD-4 (dextran 4400), (an index of intestinal permeability), was assessed in sham-operated rats and rats injected with PAF (1.25 microg kg(-1), i.v., a dose insufficient to induce intestinal injury). 3. PAF-induced villus cytoskeletal changes were examined by staining the intestine for F-actin. The effect of PAF on tyrosine phosphorylation of the junctional protein E-cadherin was examined by immunoprecipitation. Some rats were pretreated with AG1288 (a tyrosine kinase inhibitor) before PAF injection, and mucosal permeability change was assessed. 4. To investigate the role of endogenous PAF upon mucosal permeability, we studied the effect of PAF antagonists on (intraluminal) glucose-induced increase in mucosal permeability. 5. We found that low dose PAF: (a) alters the cytoskeletal structure of intestinal epithelium, (b) causes the influx of FD4 from intestinal lumen to systemic circulation, (c) induces tyrosine phosphorylation of E-cadherin and cadherin-associated proteins. Glucose-induced mucosal permeability increase is abolished by using two structurally different PAF antagonists. 6. These results suggest that endogenous PAF modulates macromolecular movement across the intestinal mucosal barrier, probably via tyrosine phosphorylation of E-cadherin and cytoskeletal alteration of enterocytes.     

实验性骨质疏松性骨折愈合方式的组织学观察

动态观察骨质疏松性骨折愈合的组织学变化与特征,进一步阐明骨质疏松性骨折的愈合方式。方法选择８０只８月龄,雌性ＳＤ大鼠,手术方法为建立骨质疏松骨折与一般骨折的实验模型各４０只,于手术后５天、１、２、４、６、８、１２、１６周截取骨痂组织作光镜与光镜观察。     

Ⅰ型细胞间粘附分子mRNA表达与肝癌侵袭转移的关系

目的：研究Ⅰ型细胞间粘附分子（ＩＣＡＭ－１）ｍ ＲＮＡ 的表达与肝癌侵袭转移的关系。方法：采用原位分子杂交及Ｎｏｒｔｈ－ｅｒｎ ｂｌｏｔ方法检测３４例肝癌组织中ＩＣＡＭ－１ ｍ ＲＮＡ 的表达。结果：３４例肝癌中２４例包膜不完整、门静脉癌栓或形成转移灶,１０例肝癌包膜完整,３４例肝癌中２１例肝癌细胞ＩＣＡＭ－１ ｍ ＲＮＡ表达阳性。伴门静脉癌栓或形成转移的肝癌１８例中,１６例ＩＣＡＭ－１ｍ ＲＮＡ 表达（＋ ＋ ）～（＋ ＋ ＋ ）;６例包膜不完整的肝癌３例表达阳性,而１０例包膜完整的肝癌仅有２例表达阳性。门静脉癌栓及肝内转移灶ＩＣＡＭ－１ ｍ ＲＮＡ 表达强阳性。结论：肝癌细胞ＩＣＡＭ－１ ｍ ＲＮＡ 的表达与肝癌的侵袭转移相关。     

保护薇乔缝线携载反义寡聚核苷酸的实验研究

目的：探讨手术缝线携载反义基因片断的可能性及可行性,为术中血管吻合口局部转染反义基因提供新的途径。方法：保护薇乔缝线反复浸于反义核酸溶液中７２h,溴化乙锭（ＥＢ ）标记,紫外灯下观察其吸附反义基因的情况。将吸附反义基因的缝线置于生理盐水中分别于不同时间点测其释放的Ｄ值,绘出体外控释曲线。同时取释放液进行泳分析。以在荧光标记的核酸溶液中浸过的缝线直接行兔颈总动脉吻合,２４h取材制片荧光显微镜下观察。结     

腹主动脉瘤腔内隔绝术国产化器具的动物应用研究

目的：研制开发腹主动脉瘤腔内隔绝术国产化器具。方法：以镍钛合金丝编织成Ｚ形支架,外面包裹国产真丝超薄人造血管,装入导鞘制成腔内隔绝系统;以牛颈静脉间置法制作保留腰动脉的犬腹主动脉瘤模型;Ｘ线监视下将腔内隔绝系统经犬动脉导入动脉瘤腔内,释放后将移植物固定在动脉瘤两端正常血管壁上,使动脉瘤与血流隔绝。结果：１０只模型犬接受手术,成功９只。术后即时检查,移植物与宿主结合紧密,没有移位、内漏等并发症发生。     

Dissipation of Clodinafop-Propargyl and Its Metabolite in Wheat Field Ecosystem

The dissipation and residues of clodinafop-propargyl and clodinafop in wheat and soil were investigated by high performance liquid chromatography-tandem mass spectrometry. Clodinafop-propargyl rapidly degraded to the acid derivative-clodinafop as major metabolite in plant and soil. The half-lives of clodinafop-propargyl were 2.35–11.20 days in soil and 6.00 days in wheat plant. The half-lives of clodinafop were 7.04–11.22 days in soil and 0.67–1.24 days in wheat plant. The residues of clodinafop-propargyl and clodinafop in wheat grain, wheat straw and soil were below the detection limit.     

心脏介入诊疗术后股动脉血管不同止血方法的并发症及防范

目的通过对经股动脉行心脏介入诊疗术后采用不同止血方法患者的常见并发症观察，探讨其防范技巧。方法对283倒经股动脉行心脏介入诊疗（选择性冠状动脉造影及支架植入术）术后采用常规绷带加压包扎、Angioseal血管缝合器及动脉压迫器止血后发生并发症的成因进行分析。结果．经股动脉途径行心脏介入治疗术后并发症主要是穿刺部位出血，表现为出血、血肿，腹膜后出血或血肿，假性动脉瘤和动静脉瘘，主要原因是穿刺部位过高或过低，血管损伤。过度抗凝和压迫止血不当所致。结论股动脉准确穿刺、术中轻柔操作、准确压迫动脉鞘管进入血管口及松紧适度是减少并发症的主要预防措施，根据病人的具体情况选择适当的股动脉心脏介入诊疗术后压迫止血方法可以减少并发症的发生。     

Requirement for GSH in recycling of ascorbic acid in endothelial cells.

Ascorbic acid may be involved in the defense against oxidant stress in endothelial cells. Such a role requires that the cells effectively recycle the vitamin from its oxidized forms. In this work, we studied the ability of cultured bovine aortic endothelial cells (BAECs) to take up and reduce dehydroascorbic acid (DHA) to ascorbate, as well as the dependence of ascorbate recycling on intracellular GSH. BAECs took up and reduced DHA to ascorbate much more readily than they took up ascorbate. Although BAECs in culture did not contain ascorbate, ascorbate accumulated to concentrations of 2-3 mM in BAECs following incubation with 400 microM DHA. Extracellular ferricyanide oxidized intracellular ascorbate, which was recycled by the cells. Reduction of DHA, either when added to the cells or when generated in response to ferricyanide, caused significant decreases in intracellular GSH concentrations. Depletion of intracellular GSH with 1-chloro-2,4-dinitrobenzene, diethylmaleate, and diamide almost abolished the ability of the cells to reduce DHA to ascorbate. DHA reduction by thioredoxin reductase was evident in dialyzed cell extracts, but occurred at rates far lower than direct GSH reduction of DHA. These results suggest that maximal rates of DHA reduction, and thus recycling of ascorbate from DHA, are dependent upon GSH in these cells.     

Molecular cloning and sequence analysis of the cDNA for the putative beta subunit of the type-II gonadotrophin from the European eel

Oestradiol treatment enhances type-II gonadotrophin (GTH-II) synthesis in the European eel (Anguilla anguilla) at the silver stage. As a first step in studying the molecular mechanisms involved in this stimulation, we cloned and characterized the cDNA encoding the beta subunit of eel GTH-II. A cDNA library was constituted in lambda gt10 from oestradiol-treated eels. It was screened using an oligodeoxyribonucleotide mixed probe designed to be complementary to a highly conserved region of cDNAs from several LH-related beta subunits. Several clones were obtained and four were subcloned in pUC13 and sequenced. The longest clones comprised a 420 bp coding sequence, plus 5' and 3' untranslated regions of 36 and 172 bp respectively. Comparison with GTH-II from other teleost fish permitted the localization of the putative cleavage site of a 24 amino acid signal peptide. The resulting 116 amino acid apopeptide had well-conserved cysteine positions and a putative N-linked glycosylation site; homology was 70-80% with GTH-II from other fish, 45% with LH from mammals and birds, 38% with mammalian FSH and only 35% with fish GTH-I. Preliminary results indicated a strong positive effect of oestradiol treatment on the level of the putative GTH-II beta-subunit mRNA. This supports our proposal that the European eel provides a suitable model for studying the positive regulation of gonadotrophin synthesis by gonadal steroids.