Inhibition of host resistance by nutritional hypercholesteremia.

Previous experiments showed that nutritionally induced hypercholesteremia in mice caused an increase in susceptibility to coxsackievirus B, with a marked suppression of cellular infiltrates in infected tissues and an increased mortality. The present studies demonstrated that a hypercholesteremic diet was associated with an inhibition in host resistance as measured by susceptibility to Listeria monocytogenes infection and the growth of two transplanted syngeneic murine tumors. Moreover, the ability of Corynebacterium parvum to induce regression of a transplanted methylcholanthrene-induced fibrosarcoma was inhibited in hypercholesteremic hosts, as was the histiocytic infiltration normally accompanying C. parvum inoculation. In contrast, the peritoneal macrophages from C. parvum-treated hypercholesteremic mice were indistinguishable from similarly treated macrophages from normal mice with respect to their in vitro tumoricidal activity and the presence of a cell surface antigen associated with activated macrophages. Hypercholesteremia was also associated with a decreased antibody response to sheep erythrocytes in vivo, but dit not appear to exert a detrimental effect on B- or T-cell blastogenesis when tested in vitro. The findings that the hypercholesteremic diet was associated with an impairment in the host immune response and increased susceptibility to viral, bacterial, and tumor cell challenge are discussed with respect to virus-lipid interactions in the pathogenesis of atherogenesis and diabetes mellitus.     

力竭运动大鼠心室肌蛋白质组表达特征

目的:采用蛋白质组学技术,建立安静和递增运动负荷训练后力竭大鼠心室肌蛋白质组的差异性表达谱,初步筛选出心室肌对力竭运动产生反应的目标蛋白质。方法:实验于2007-03在湖南师范大学生命科学学院蛋白质化学与蛋白质组学国家教育部重点实验室和省级运动人体科学实验室完成。①实验分组:10只SD雄性大鼠随机分为对照组和运动组,每组5只。②实验方法:运动组经过7周的大强度递增运动负荷训练后(最后一次力竭),对两组心室肌组织的全蛋白进行双向凝胶电泳分离。结果:经图像分析,在运动组的电泳图谱上共展现蛋白质点(338±17)个,对照组展现蛋白质点(352±17)个。运动后差异表达的蛋白质点共有99个。对其中差异表达的9个蛋白质点进行质谱鉴定,共鉴定出7个蛋白质,Stress-70protein,NADH-ubiquinone oxidoreductase Mr75000subnunit,Long-chain specific acyl-CoA dehydrogenase,Tropomyosin-1alphachain在运动后"缺失",Nitrilase family,member2在运动后表达上调在5倍以上,一个相对分子质量为21000的未知蛋白在运动后表达下调在5倍以上,另外有两个点经鉴定均为Myosin-6,在运动后表达量相反。这些蛋白质属于收缩蛋白、能量代谢酶、分子伴侣等。结论:递增运动负荷训练后力竭时,大鼠心室肌蛋白质组明显地发生了反应。运动后"缺失"和下调的蛋白质点与心肌收缩的调控和能量代谢的方式转变以及细胞的应激反应有关,其中,成功筛选出6种在运动医学领域尚未涉足的、具有运动应激特点的目标蛋白质。     

An endogenous glycosylphosphatidylinositol-specific phospholipase D releases basic fibroblast growth factor-heparan sulfate proteoglycan complexes from human bone marrow cultures

Basic fibroblast growth factor (bFGF) is a hematopoietic cytokine that stimulates stromal and stem cell growth. It binds to a glycosylphosphatidylinositol (GPI)-anchored heparan sulfate proteoglycan on human bone marrow (BM) stromal cells. The bFGF- proteoglycan complex is biologically active and is released by addition of exogenous phosphatidylinositol-specific phospholipase C. In this study, we show the presence of an endogenous GPI-specific phospholipase D (GPI-PLD) that releases the bFGF-binding heparan sulfate proteoglycan and the variant surface glycoprotein (a model GPI-anchored protein) from BM cultures. An involvement of proteases in this process is unlikely, because released proteoglycan contained the GPI anchor component, ethanol-amine, and protease inhibitors did not diminish the release. The mechanism of release is likely to involve a GPI-PLD and not a GPI-specific phospholipase C, because the release of variant surface glycoprotein did not reveal an epitope called the cross- reacting determinant that is exposed by phospholipase C-catalyzed GPI anchor cleavage. In addition, phosphatidic acid (which is specifically a product of GPI-PLD-catalyzed anchor cleavage) was generated during the spontaneous release of the GPI-anchored variant surface glycoprotein. We also detected GPI-PLD-specific enzyme activity and mRNA in BM cells. Therefore, we conclude that an endogenous GPI-PLD releases bFGF-heparan sulfate proteoglycan complexes from human BM cultures. This mechanism of GPI anchor cleavage could be relevant for mobilizing biologically active bFGF in BM. An endogenous GPI-PLD could also release other GPI-anchored proteins important for hematopoiesis and other physiologic processes.     

Analysis of cell division among subpopulations of lymphoid cells in sheep. I. Thymocytes

The number, distribution and surface phenotype of dividing cells in the thymus, and differences between the cell cycle status of thymocyte subpopulations, were studied in fetal and post-natal lambs using double-labelling techniques. Dividing cells were labelled in vivo for various periods with 5-bromo-2-deoxyuridine (BrdU). The proportions of constituent thymocyte subpopulations that had synthesized DNA during the labelling period were measured by flow cytometry or immunohistochemistry using a panel of monoclonal antibodies (mAbs) specific for sheep lymphocyte differentiation antigens and MHC class I and class II antigens in conjunction with an anti-BrdU mAb. The proportion of thymocytes that incorporated BrdU during a 1-hr labelling period varied with age, and levels of 30%, 13% and 9% were measured, respectively, in 40- and 125-day-old fetuses and 8-week-old lambs. Eight percent of the thymocytes in lambs were synthesizing DNA, with 4% entering the G2 phase per hour, and a substantial number of thymocytes (21%) had a G2 + M phase DNA content. A small subset of thymocytes (1-3%) recognized by mAb E-79 localized to the subcapsular region of the cortex and displayed the highest level of BrdU incorporation. Cortical-type thymocytes (CD1+) comprised 50-70% of thymocytes; however, few of these incorporated BrdU and the proportion in the G2 + M phase of the cell cycle was higher than for other thymocyte subpopulations. The 197+CD4-CD8- T cells also showed no evidence of in vivo division.     

MMP-13 is over-expressed in renal cell carcinoma bone metastasis and is induced by TGF-β1

Bone metastasis occurs frequently in renal cell carcinoma (RCC) patients causing significant morbidity by stimulating excessive osteolysis, yet the mechanisms responsible have been little studied. Matrix metalloproteinases (MMPs) are over-expressed in many cancer types and are believed to play a role in bone metastasis, however, the expression of MMPs in RCC bone metastasis (RBM) has not been investigated. Due to their ability to degrade the main component of organic bone matrix, type I collagen, we investigated the expression of MMP-1, -2, -8, -9, and -13 in RBM. By quantitative (q)RT-PCR, expression of MMP-13 was significantly increased in RBM tissues relative to that in RCC and adjacent normal kidney while no differences in the expression of MMP-1, -2, -8, or -9 mRNA were observed. Correspondingly, increased expression of MMP-13 protein was also observed in RBM relative to RCC by immunohistochemical analysis. Intriguingly, the expression of MMP-13 in the human RBM cell line RBM1-IT4 was stimulated by TGF-β1, a growth factor abundant in the bone microenvironment and known to promote RBM-induced osteolysis in animals. Exposure of RBM1-IT4 cells to TGF-β1 increased MMP-13 mRNA levels as well as the latent and active forms of MMP-13 protein. Further, stable expression of a dominant-negative TGF-β type II receptor in RBM1-IT4 cells inhibited MMP-13 expression following TGF-β1 exposure. These data suggest that MMP-13 expression is elevated in RBM relative to primary RCC and adjacent normal kidney, and is regulated at the cellular level by TGF-β1.     

Maternal toxicity with continuous nevirapine in pregnancy: results from PACTG 1022

OBJECTIVE: To compare the safety of nelfinavir and nevirapine-based antiretroviral treatment in HIV-1-infected pregnant women. METHODS: In Pediatric AIDS Clinical Trials Group Protocol 1022, 38 antiretroviral-naive pregnant women at 10-30 weeks' gestation were randomized to nelfinavir or nevirapine with zidovudine plus lamivudine. The study was suspended because of greater than expected toxicity and changes in nevirapine prescribing information. The incidence of treatment-limiting hepatic or cutaneous toxicity was compared between groups for all subjects and for the subset with CD4 cell counts greater than 250 cells/microL at study entry. RESULTS: Toxicity was seen in 1 (5%) of 21 subjects randomized to nelfinavir and 5 (29%) of 17 subjects randomized to nevirapine (P = 0.07). Within the nevirapine group, 1 subject developed fulminant hepatic failure and died, and another developed Stevens-Johnson syndrome. The one adverse event associated with nelfinavir occurred in a subject with a CD4 cell count less than 250 cells/microL. All 5 events among subjects with a CD4 cell count greater than 250 cells/microL were associated with nevirapine (P = 0.04). CONCLUSIONS: Continuous nevirapine may be associated with increased toxicity among HIV-1-infected pregnant women with CD4 cell counts greater than 250 cells/microL, as has been observed in non-pregnant women.     

Life-course financial strain and health in African–Americans

Differential exposure to financial strain may explain some differences in population health. However, few studies have examined the cumulative health effect of financial strain across the life-course. Studies that have are limited to self-reported health measures. Our objective was to examine the associations between childhood, adulthood, and life-course, or cumulative, financial strain with disability, lung function, cognition, and depression. In a population-based cross-sectional cohort study of adult African–American twins enrolled in the US Carolina African American Twin Study of Aging (CAATSA), we found that participants who reported financial strain as children and as adults are more likely to be physically disabled, and report more depressive symptoms than their unstrained counterparts. Participants who reported childhood financial strain had lower cognitive functioning than those with no childhood financial strain. We were unable to detect a difference in lung function beyond the effect of actual income and education in those who reported financial strain compared to those who did not. Financial strain in adulthood was more consistently associated with poor health than was childhood financial strain, a finding that suggests targeting adult financial strain could help prevent disability and depression among African–American adults.