Biosynthesis of prothrombin: intracellular localization of the vitamin K-dependent carboxylase and the sites of gamma-carboxylation

Prothrombin is a vitamin K-dependent blood coagulation protein that undergoes posttranslational gamma-carboxylation and propeptide cleavage during biosynthesis. The propeptide contains the gamma-carboxylation recognition site that directs gamma-carboxylation. To identify the intracellular sites of carboxylation and propeptide cleavage, we monitored the synthesis of prothrombin in Chinese hamster ovary cells stably transfected with the prothrombin cDNA by immunofluorescent staining. The vitamin K-dependent carboxylase was located in the endoplasmic reticulum and Golgi complex. Antibodies specific to prothrombin processing intermediates were used for immunocytolocalization. Anti-des-gamma-carboxyprothrombin antibodies stained only the endoplasmic reticulum whereas antiproprothrombin antibodies (specific for the propeptide) and antiprothrombin:Mg(II) antibodies (which bind the carboxylated forms of proprothrombin and prothrombin) stained both the endoplasmic reticulum and the Golgi complex. Antiprothrombin:Ca(II)-specific antibodies (which bind only to the carboxylated form of prothrombin lacking the propeptide) stained only the Golgi complex and secretory vesicles, and colocalized with antimannosidase II and anti-p200 in the juxtanuclear Golgi complex. These results indicate that uncarboxylated proprothrombin undergoes complete gamma-carboxylation in the endoplasmic reticulum and that gamma-carboxylation precedes propeptide cleavage during prothrombin biosynthesis.     

Transforming growth factor-β production during the development of renal fibrosis in rats with subtotal renal ablation

The histologic changes observed in the remnant kidney model include progressive mesangial expansion with collapse of capillary lumina, interstitial fibrosis and mononuclear cellular infiltration. Transforming growth factor-beta (TGF-β₁) is an important regulator of extracellular matrix formation. The purpose of this study was to investigate the production and distribution of TGF-β₁ in the kidney during the development of glomerulosclerosis and renal fibrosis in rats with subtotal renal ablation. Eighty-two female Wistar rats weighing 180–220 g were divided into two groups: 49 rats were subjected to 5/6 renal ablation and 33 to sham operation. Urinary albumin excretion, blood pressure and glomerular filtration rate (GFR) were evaluated after the surgical procedure. We also performed histology and immunohistochemistry and determined mRNA for TGF-β₁ in the kidneys of these rats 8, 15, 30 and 90 days after operation. The results showed progressively higher immunohistochemical TGF-β₁ staining in rats with subtotal renal ablation. Cortical renal content of TGF-β₁ mRNA was also higher in these animals and peaked at day 15.
The existence of a temporal association between glomerulosclerosis, interstitial fibrosis and intense mononuclear cellular infiltration on the one hand and higher immunohistochemical TGF-β₁ staining in the renal cortex on the other show that this polypeptide may contribute to the development of renal fibrosis in this model.     

碱性成纤维细胞因子在异基因外周血造血干细胞移植患者中的应用

目的 研究碱性成纤维细胞因子(b—FGF)喷雾剂对异基因外周血造血干细胞移植患口腔溃疡的影响。方法 34例进入血液层流室的异基因外周血造血干细胞移植患，随机分为实验组与对照组，分别观察口腔溃疡发生情况、愈合时间、溃疡分布、平均愈合天数及溃疡VAS疼痛评分。结果 实验组与对照组的口腔溃疡发生率无明显差异，但口腔溃疡伪膜发生率、平均愈合天数及患口腔溃疡VAS疼痛评分明显低于对照组。结论b—FGF可减少患口腔溃疡伪膜的发生，使口腔溃疡面提前愈合，提高患痛感，降低患疼痛感，有助于以较好状态；度过造血干细胞移植期。