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)。...     

Nutrients and limiting factors

The terms nutrient and limiting factor summarise the results of an experiment in which increase in supply results in an increased response. By extension they are often — perhaps usually — used when the user believes that were such an experiment made it would have this characteristic. If the supply is further increased the response diminishes and may, eventually, become negative. Nutrient and limiting factor therefore apply, strictly, only when the circumstances are specified: they cannot be attached to a particular substance without qualification. The claim that nitrogen is a nutrient (or limiting factor) is incomplete. All nutrients are limiting factors, but the reverse is not true. The widespread belief that only one factor can limit a complex process at one time is demonstrably false in general, though it may sometimes be true in particular cases.     

Growth factors and apoptosis

Abstract. Apoptosis is nowadays recognized as an important mechanism by which cells can be eliminated from the organism. In particular its role in tissue modelling during embryogenesis has been highlighted. The human teratoma cell line Tera 2, which in several respects acts as a human embryonic stem cell, can be induced to undergo apoptosis by reducing the serum content of the tissue culture medium. We report here that this process can be reversed by replacing serum with the heparin-binding growth factors, acidic FGF and basic FGF. In contrast, neither of the mammalian transforming growth factors (TGF-β-3) managed to exert any effect on growth or apoptosis in Tera 2 cells.     

Mutagenesis and cardiovascular diseases Molecular mechanisms, risk factors, and protective factors

Although no generalization can be made, it is of interest that cancer, cardiovascular diseases, and other chronic conditions often share common risk factors and common protective factors as well as common pathogenetic determinants, such as DNA damage, oxidative stress, and chronic inflammation. Atherosclerosis is the most important cause of vascular forms representing the major cause of death in the population of many geographical areas. A great deal of studies support the "response-to-injury" theory. A variety of experimental and epidemiological findings are also in favor of the somatic mutation theory, which maintains that the earliest event in the atherogenic process is represented by mutations in arterial smooth muscle cells, akin to formation of a benign tumor. These two theories can be harmonized, also taking into account the highly diversified nature of atherosclerotic lesions. Molecular epidemiology studies performed in our laboratory and other laboratories have shown that DNA adducts are systematically present in arterial smooth muscle cells, and their levels are correlated with atherogenic risk factors known from traditional epidemiology. Oxidative DNA damage was also consistently detected in these cells. The role of glutathione S-transferase polymorphisms on the frequency of the above molecular alterations and of arterial diseases is rather controversial. Prevention of both cancer and atherosclerosis is based on avoidance of exposure to risk factors and on fortification of the host defense mechanisms by means of dietary principles and chemopreventive drugs.     

Mesoderm induction and blood island formation by angiogenic growth factors and embryonic inducing factors

Factors which induce mesoderm, including endothelium lined cavities and primitive blood cells in omnipotent amphibian ectoderm, have been isolated from different sources. Recently it was shown that angiogenic factors, which belong to the protein families of the heparin binding growth factors (acidic and basic fibroblast growth factor) and the transforming growth factors (TGF-beta 1 and -beta 2), also induce mesodermal tissues in amphibian ectoderm. In triturus ectoderm, capillary like endothelial networks are induced preferentially by the transforming growth factors. The relationship between growth factors and inducing factors is discussed.