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11.
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed.  相似文献   
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We have previously reported two common lipoprotein lipase (LPL) gene mutations underlying LPL deficiency in the majority of 37 French Canadians (Monsalve et al., 1990. J. Clin. Invest. 86: 728-734; Ma et al., 1991. N. Engl. J. Med. 324: 1761-1766). By examining the 10 coding exons of the LPL gene in another French Canadian patient, we have identified a third missense mutation that is found in two of the three remaining patients for whom mutations are undefined. This is a G to A transition in exon 6 that results in a substitution of asparagine for aspartic acid at residue 250. Using in vitro site-directed mutagenesis, we have confirmed that this mutation causes a catalytically defective LPL protein. In addition, the Asp250----Asn mutation was also found on the same haplotype in an LPL-deficient patient of Dutch ancestry, suggesting a common origin. This mutation alters a TaqI restriction site in exon 6 and will allow for rapid screening in patients with LPL deficiency.  相似文献   
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Characterization of non-transferrin-bound iron clearance by rat liver   总被引:10,自引:0,他引:10  
Recent evidence suggests that the hepatic iron-loading characteristic of hemochromatosis may result in part from efficient hepatic clearance of non-transferrin-bound iron, which is increased in this disorder. However, this hypothesis assumes that hepatic clearance remains highly efficient despite excess iron stores. We therefore studied hepatic uptake of non-transferrin-bound iron in the single-pass perfused rat liver under varying conditions. Animals were iron loaded or depleted by dietary manipulation, but no changes in the efficiency of ferrous iron uptake or the kinetic parameters were seen (single-pass extraction, 59-74%; Km, 16-19 microM; Vmax, 30-32 nmol X min-1 X g liver-1). Added divalent zinc, cobalt, and manganese ions reversibly inhibited ferrous iron uptake and the inhibition by zinc was shown to be competitive. Uptake required calcium, was markedly temperature-sensitive (delta E = 14.3 Kcal/mol), and was relatively insensitive to inhibition of cellular energy metabolism. Particles consistent with ferritin cores were seen in lysosomes of hepatic parenchymal cells within 30 min of perfusion with ferrous iron. These results suggest that ferrous iron is cleared from plasma by a passive, saturable transport process that is not regulated by the iron content of the liver and that may be shared with other transition metal ions. Because clearance is highly efficient, increased levels of non-transferrin-bound iron in plasma may present the liver with an obligatory iron load resulting in progressive accumulation and toxicity.  相似文献   
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 本文介绍了以α-鹅膏蕈碱和低浓度KCl为手段建立了RNA聚合酶Ⅰ、RNA聚合酶Ⅱ活性的细胞核转录系统进而研究了cGMP、cAMP、cAMP丁酯及cAMP硫代环磷酰二乙胺对大鼠肝细胞核中RNA聚合酶Ⅰ与Ⅱ活性的影响。结果显示cGMP可以提高RNA聚合酶Ⅰ的活性;cAMP主要提高RNA聚合酶Ⅱ的活极,而cAMP分子结构变化产生的丁酯及硫代环磷酰二乙胺衍生物可增强cAMP的这种作用,为深入研究cAMP的构效关系提供了实验依据。  相似文献   
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The effect of the type I interferon on the development and process of experimental pyelonephritis caused by E. coli was studied on mice weighing 12 to 14 g. Interferon was administered intraperitoneally in a dose of 1000 units on days 3 and 7 of the disease. It was shown that the administration of the type I interferon to the mice with experimental pyelonephritis promoted rapid elimination of bacteria from the kidneys, prevented their penetration to the contralateral (intact) kidney, prevented marked macro- and microscopic damages in the kidneys, lowered the intensity of the inflammatory reaction, and increased the phagocytic activity of neutrophils and the number of the E-rosette-forming lymphocytes in the thymus. The data provided experimental grounding for clinical trials of interferon preparations in treatment of bacterial pyelonephritis.  相似文献   
17.
 E.coli RNA聚合酶ββ'亚单位编码的基因rpoBC与核糖核蛋白基因rplJL共同构成rpoBC操纵子。rpl-rpo间区转录终止信号~tL7的转录产物RNA有两组富含C-G的反向对称结构及一串寡聚U;反向对称区可形成1:2和3:4茎环或单一5:6茎环。 用M13mp11噬菌体插入~tL7的112bp片段重组M13mp11-490,在此基础上用定点突变技术建立~tL7的七核苷酸缺失突变体,从而破坏1:2茎环,建成M13mp11-85。 分别把原型~tL7及缺失型~tL7~v克隆到表达质粒pHR24中,构建成pHR37(P_ftsQ~tL7-galk)及pHR24-9(p_ftsQ-~tL7~v-galk)。测定galk基因产物半乳糖激酶活性,推算转录的终止效率。结果表明:~tL7终止效率为50%,~tL7~v为20%。说明仅有3:4茎环及寡聚U,即具终止作用; 1:2茎环通过某种方式加强3:4茎环从而提高终止效率。  相似文献   
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本文用细胞免疫化学方法,在冰冻切片上,检测了胎儿不同组织和器官内带γδ和αβ受体的T细胞(TCR)的分布,结果发现TCR细胞的分布与,般T细胞不同,有相对固定的分布区,如胸腺内TCR细胞主要分布在皮筋质交界处和髓质部;脾脏内的γδT主要位于边缘区,而αβT主要位于动脉周围淋巴鞘,在红髓和血窦两种细胞共存;淋巴结内只有少数TCR细胞位于滤泡间或副皮质,滤泡内则未见。消化管内的TCR细胞主要分布在小肠的固有膜,而胃、大肠和阑尾的固有膜内很少见;肝内TCR细胞主要集中在血管和血窦周围;皮肤切片内的少数TCR细胞见于真皮内,表皮基底层细胞内未见。这些细胞在胎儿期的免疫皮应及其生理功能还不清楚。  相似文献   
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将γ─亚麻酸生产菌Cunninghamellaspp.8761进行原生质体化,并用物理方法进行诱变,使其在形态上产生了变异,γ─亚麻酸含量有所增加。本文报道了该菌株原生质体的制备,再生条件,以及诱变后形态变化,发酵性能。  相似文献   
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