Roles of pilin and PilC in adhesion of Neisseria meningitidis to human epithelial and endothelial cells.

Pili and pilin antigenic variation play important roles in adhesion of Neisseria meningitidis (MC) to human epithelial and endothelial cells. We recently identified one pilin variant that confers high adhesiveness of MC to human epithelial cells in culture. However, other factor(s) also play a role in MC adhesiveness, since some nonadhesive variants of MC strain 8013 are piliated and produce the same pilin variant as adhesive derivatives. PilC1 and PilC2, high molecular weight outer membrane proteins in Neisseria gonorrhoeae, are proposed to play roles in pilus assembly. Strain 8013 also contains pilC1 and pilC2; their products function in a similar if not identical manner in pilus biogenesis. PilC1 has an additional function in that it also modulates adhesiveness of strain 8013.     

Regulation of interleukin-12 expression in human monocytes: selective priming by interferon-gamma of lipopolysaccharide-inducible p35 and p40 genes

Interleukin-12 (IL-12) is a monocyte/macrophage-derived cytokine that is critical for T lymphocyte and natural killer cell activities and functions. In this study, we examined the regulation of IL-12 expression by human monocytes in response to bacterial lipopolysaccharide (LPS). Several novel aspects of IL-12 induction from monocytes were shown. Optimal expression of IL-12 mRNA and bioactivity required specific priming of monocytes by interferon-gamma (IFN-gamma) before LPS stimulation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) provided an equivalent priming stimulus for LPS-induced tumor necrosis factor (TNF) and IL-12 p40 mRNA, but primed poorly for LPS-inducible p35 message and secreted IL-12 activity. Macrophage colony-stimulating factor (M-CSF), although a potent survival factor for monocytes, showed no priming activity for IL-12 production. Time course experiments demonstrated independent regulation of p40 and p35 by IFN-gamma and LPS. LPS inducibility of p40 expression required only a brief exposure to IFN-gamma (2 hours), while prolonged exposure (+/- 24 hours) to IFN-gamma resulted in diminishing levels of p40 mRNA. p35 inducibility (by LPS) required a longer exposure to IFN-gamma (8 to 16 hours), and continued to be inducible up to 40 hours following IFN- gamma priming. Both mRNAs were rapidly induced (1 to 2 hours) in IFN- gamma-primed monocytes; p35 message reached a plateau by 2 hours, while p40 continued to accumulate. Finally, both p40 and p35 were directly induced by LPS in the presence of cycloheximide. These results indicated that both p40 and p35 are LPS-inducible in monocytes following IFN-gamma pretreatment, and that the regulated expression of p35 controls the level of active IL-12 protein in purified human monocytes. The selectivity of priming by IFN-gamma is in accord with a putative role for IL-12 in the initiation and amplification of TH1-type responses.     

Adverse effect of obesity on red cell membrane arachidonic and docosahexaenoic acids in gestational diabetes

Aims/hypothesis Gestational diabetes is a metabolic disorder affecting 2–5% of women and is a predictor of obesity, Type 2 diabetes mellitus and cardiovascular disease. Insulin resistance, a characteristic of gestational diabetes and obesity, is correlated with the fatty acids profile of the red cell and skeletal muscle membranes. We investigated the plasma and red cell fatty acid status of gestational diabetes. The effect of obesity on membrane fatty acids was also examined.Methods Fasting blood obtained at diagnosis was analysed for the fatty acids in plasma choline phosphoglycerides and red cell choline and ethanolamine phosphoglycerides.Results There were reductions in arachidonic acid (controls 10.74±2.35 vs gestational diabetes 8.35±3.49, p<0.01) and docosahexaenoic acid (controls 6.31±2.67 vs gestational diabetes 3.25±2.00, p<0.0001) in the red cell choline phosphoglycerides in gestational diabetes. A similar pattern was found in the ethanolamine phosphoglycerides. Moreover, the arachidonic and docosahexaenoic acids depletion in the red cell choline phosphoglycerides was much greater in overweight/obese gestational diabetes (arachidonic acid=7.49±3.37, docosahexaenoic acid=2.98±2.18, p<0.01) compared with lean gestational diabetes (arachidonic acid=10.03±2.74, docosahexaenoic acid=4.18±1.42).Conclusion/interpretation Apparently normal plasma choline phosphoglycerides fatty acids profile in the gestational diabetic women suggested that membrane lipid abnormality is associated specifically with perturbation in the membrane. The fact that the lipid abnormality is more pronounced in the outer leaflet of the membrane where most of receptor binding and enzyme activities take place might provide an explanation for the increased insulin resistance in gestational diabetes and obesity.Abbreviations AA arachidonic acid - CPG choline phosphoglycerides - DHA docosahexaenoic acid - EPG ethanolamine phosphoglycerides - FAME fatty acid methyl esters - GDM gestational diabetes mellitus     

Therapy of patients with human T-cell lymphotrophic virus I-induced adult T-cell leukemia with anti-Tac, a monoclonal antibody to the receptor for interleukin-2

Human T-cell lymphotropic virus I (HTLV-I)-induced adult T-cell leukemia (ATL) cells constitutively express interleukin-2 (IL-2) receptors identified by the anti-Tac monoclonal antibody (MoAb), whereas normal resting cells do not. This observation provided the scientific basis for a trial of intravenous anti-Tac in the treatment of nine patients with ATL. The patients did not suffer untoward reactions and did not have a reduction in the normal formed elements of the blood, and only one of the nine produced antibodies to the anti-Tac MoAb. Three patients had transient mixed, partial, or complete remissions lasting from 1 to more than 8 months after anti-Tac therapy, as assessed by routine hematologic tests, immunofluorescence analysis of circulating cells, and molecular genetic analysis of HTLV-I provirus integration and of the T-cell receptor gene rearrangement. The precise mechanism of the antitumor effects is unclear; however, the use of a MoAb that prevents the interaction of IL-2 with its receptor on ATL cells provides a rational approach for the treatment of this malignancy.     

Effects of dexamethasone on selective lymphocyte subpopulations in hypercortisolemic patients with anorexia nervosa and with bulimia nervosa: Preliminary report

The studies reported here describe the effects of intravenous (IV) administration of the synthetic glucocorticoid dexamethasone (DEX) on certain neuroendocrine and immunological measures in hypercortisoiemic patients with anorexia nervosa (AN) and with bulimia nervosa (BN). The results demonstrate that failure to suppress cortisol levels after DEX administration in patients with AN is associated with failure to reduce the level of adrenocorticotropic hormone (ACTH), the ratio of CD4-to-CD8 lymphocytes, the percent and number of circulating CD4 lymphocytes, and the percent and number of virgin CD4 cells (CD4+CD45RA+). Administration of DEX to patients with BN suppressed plasma ACTH and cortisol levels, reduced the CD4/CD8 ratio and the percent and number of CD4 and of CD4 + CD45RA+ lymphocytes, and increased the percent and number of circulating CD8 lymphocytes. Administration of DEX failed to alter other immune measures in either patient population, including circulating populations of B and natural killer cells, the proliferative response to T-cell mitogen, and the number of glucocorticoid receptors in circulating lymphocytes.     

Restoration of E-cadherin/beta-catenin expression in pancreatic cancer cells inhibits growth by induction of apoptosis

BACKGROUND: beta-Catenin is a component of the E-cadherin/catenin adhesion complex that maintains epithelial cell integrity. We have previously observed decreased beta-catenin expression in both human pancreatic cancer cell lines and primary tumors. To determine the significance of this finding with respect to pancreatic carcinogenesis, this study evaluated the effects of restoring expression of beta-catenin with and without E-cadherin in pancreatic cancer cells. METHODS: MiaPaca-2 cells were stably transfected with full-length cDNAs for beta-catenin, E-cadherin, or a mutated E-cadherin lacking the beta-catenin-binding domain. Doubly transfected cell clones containing beta-catenin and either E-cadherin or deleted E-cadherin were also selected. Assays for cell adhesion, cell cycle profile, motility, and apoptosis were performed. RESULTS: Cell clones expressing beta-catenin alone or beta-catenin and deleted E-cadherin did not differ significantly from the parental cell lines in any of the assays performed. In contrast, MiaPaca-2 cell clones expressing both beta-catenin and E-cadherin showed tight adhesion, decreased cell growth, and a significantly increased apoptotic index as compared to the parental line or singly transfected clones. CONCLUSIONS: MiaPaca-2 cells undergo apoptosis at a significantly increased rate after restoration of the E-cadherin/beta-catenin adhesion complex. This increase in apoptosis is dependent on the ability of E-cadherin to bind beta-catenin. Loss of beta-catenin expression may therefore provide pancreatic cancer cells with a growth advantage that contributes to tumor progression.     

The initial steps leading to papillomavirus infection occur on the basement membrane prior to cell surface binding

Using a murine challenge model, we previously determined that human papillomavirus (HPV) pseudovirions initially bind preferentially to the cervicovaginal basement membrane (BM) at sites of trauma. We now report that the capsids undergo a conformational change while bound to the BM that results in L2 cleavage by a proprotein convertase (PC), furin, and/or PC5/6, followed by the exposure of an N-terminal cross-neutralization L2 epitope and transfer of the capsids to the epithelial cell surface. Prevention of this exposure by PC inhibition results in detachment of the pseudovirions from the BM and their eventual loss from the tissue, thereby preventing infection. Pseudovirions whose L2 had been precleaved by furin can bypass the PC inhibition of binding and infectivity. Cleavage of heparan sulfate proteoglycans (HSPG) with heparinase III prevented infection and BM binding by the precleaved pseudovirions, but did not prevent them from binding robustly to cell surfaces. These results indicate that the infectious process has evolved so that the initial steps take place on the BM, in contrast to the typical viral infection that is initiated by binding to the cell surface. The data are consistent with a dynamic model of in vivo HPV infection in which a conformational change and PC cleavage on the BM allows transfer of virions from HSPG attachment factors to an L1-specific receptor on basal keratinocytes migrating into the site of trauma.     

冠状动脉粥样硬化ADAMTS7新位点的发现和冠状动脉粥样硬化中ABO位点与心肌梗死的相关性:两项全基因组关联研究

<正>背景:该研究旨在评价在现有的冠状动脉粥样硬化的病变中,遗传因素对粥样硬化斑块进展及特异性心肌梗死是否存在显著作用。方法:对欧洲后裔参与者冠状动脉造影表型进行了两项全基因组关联研究(GWAS),为寻找冠状动脉疾病(CAD)易感性基因位点,研究比较了有异常(n=12393)和无异常的(对照组n=7383)个体;为寻找心肌梗死易感性基因位点,也同时比较了造影证实存在CAD并且有心肌梗死的个体(n=5783)与虽有CAD但无心肌梗死的个体(n=3644)。