肌肉营养因子

现已发现许多物质具有肌肉营养作用,这些物质称为肌肉营养因子。肌肉营养因子为运动神经元病和肌肉退行性病变的研究和治疗提供了新的手段。本文分别叙述了已知的各种肌肉营养因子的研究概况,并指出肌肉营养因子研究的方向和临床意义。     

Initiation factors that bind mRNA. A comparison of mammalian factors with wheat germ factors

Three mammalian eukaryotic initiation factors (eIF) are required for the ATP-dependent binding of mRNA to the 40 S ribosomal subunit. These three factors, eIF-4A, eIF-4B, and eIF-4F, have also been isolated from wheat germ. Three assays were used to measure the ability of the wheat germ factors to interact with and/or substitute for the mammalian factors. Two assay systems were used to measure partial reactions involving the interaction of the three factors, ATP, and mRNA: 1) RNA-dependent ATP hydrolysis and 2) cross-linking of the factors to the 5' cap of oxidized mRNA. A third assay system was used to measure the ability of the factors to support initiation of protein synthesis. The results of the ATP hydrolysis and cross-linking experiments indicate that the wheat germ factors can interact with or substitute for the mammalian factors. Wheat germ eIF-4A appears to be functionally equivalent to mammalian eIF-4A. Wheat germ eIF-4B and eIF-4F appear to be isozymes possessing functions similar to mammalian eIF-4F. Wheat germ eIF-4B does not appear to be a functional equivalent to the mammalian eIF-4B. In a complete translation system from wheat germ, mammalian factors partially substitute for wheat germ factors, whereas the wheat germ factors are ineffective in the mammalian system.     

Growth factors as survival factors: Regulation of apoptosis

Apoptosis is now widely recognized as a common form of cell death and represents a mechanism of cell clearance in many physiological situations where deletion of cells is required. Peptide growth factors, initially characterised as stimulators of cell proliferation, have now been shown to inhibit death in many cell types. Deprivation of growth factors leads to the induction of apoptosis, i.e. condensation of chromatin and degradation in oligonucleosomesized fragments, formation of plasma and nuclear membrane blebs and cell fragmentation into apoptotic bodies which can be taken up by neighbouring cells. Here we discuss the mechanism(;s) by which growth factors may inhibit apoptosis.     

Pathogen factors and host factors in murine pulmonary blastomycosis

Factors related to pathogenesis were studied in a murine model of pulmonary fungal infection with strains of Blastomyces dermatitidis. Strain 26199V was 10⁵-fold more lethal in pulmonary challenge than strain GA-1. This relationship between the two strains also occurred after intraperitoneal challenge. Serial studies with lung cultures and histology of sacrificed animals after pulmonary challenge with similar doses, and challenge studies in mice of differing maturity, indicated GA-1 is impaired in initial replication in situ, although the two strains grow equally well in the presence of murine substrates in vitro. In vitro studies indicated the two strains were indistinguishable in most studies of biochemical and metabolic markers, and in studies with chemical and physical inhibitors. The exceptions were their morphologic appearance in the yeast phase, ability to hydrolyze esculin, and susceptibility to crystal violet dye and bile. The last finding and previous work suggested possible differences in lipid content; these were confirmed in studies which also included two other strains. Greater phospholipid and palmitic acid content were associated with greater virulence.     

肝炎后肝硬化患者肝癌发生的保护因素与危险因素研究

目的:通过回顾性病例对照研究,探讨多种因素在病毒性肝炎后肝化门静脉高压症患者HCC发生过程中的作用以及脾切除是否抑制了肝癌的发生进程。方法:收集第四军医大学西京医院病案统计室检索2002年1月～2008年12月之间出院诊断为病毒性肝炎后(HBV/HCV)肝硬化门脉高压的病例2300余例,收集所有病例的一般资料,临床及实验室检查数据,影象学检查结果,以及在治疗过程中的脾切除手术史。采用病例对照,按年龄、性别两个指标进行1:1配对,根据研究对象是否合并HCC将其分为合并HCC组(组1),未合并HCC组(组2),采用SPSS17.0进行单因素分析及多因素logistic回归分析。结果:描述性统计结果显示,两组的ALB、AST、TP、ALP、GGT等差异有统计学意义(P<0.05),而PLT、ALT、TBIL等在两组间差异无统计学意义(P>0.05)。将单因素分析有意义的研究因素纳入多因素logistic回归方程得知,AST、ALP、GGT异常升高增加了肝癌发生的危险性,而行脾切除和门奇断流术明显降低了肝癌发生的危险性,仅为无手术患者肝癌发生危险性的57.1%(OR:0.571,95%CI:0.394～0.825)。...