Strategy for the detection of Helicobacter species by amplification of 16S rRNA genes and identification of H. felis in a human gastric biopsy

The aim of the present work was to develop polymerase chain reactions (PCRs) based on the conserved nucleotide sequence of the 16S rRNA gene for detection of bacteria of the Helicobacter genus in human antral biopsy samples. The assay for Helicobacter spp was developed by amplifying a 399-bp 16S rRNA gene sequence specific to the genus Helicobacter. The identity of the amplicon was confirmed by hybridization with an internal probe and by restriction by endonuclease VspI showing two expected fragments of 295 and 104 base pairs. A total of 65 dyspeptic patients from France and New Caledonia were screened for Helicobacter spp infection through the use of the following diagnostic assays on biopsy specimens collected through endoscopy: direct detection of bacteria in histological sections by Giemsa and Warthin Starry staining, urease test and bacterial isolation, PCR for Helicobacter pylori ureC/glmM gene, and PCR targeted to 16S rRNA genes. The 16S rRNA gene PCR assay was able to detect down to 680 bacterial cells, as assessed by agarose gel electrophoresis, and down to 4 bacterial cells by hybridization of amplicon with the internal probe. The 16S rRNA PCR test was 100% specific and sensitive; results obtained with this test were in agreement with the visualization of bacteria by histology. Urease test and culture were 86.4% and 22.7% sensitive, and 96.5 and 100% specific, respectively. The H. pylori ureC/glmM gene-based PCR was 100% specific and only 95.4% sensitive, since one biopsy from a Melanesian patient contained a Helicobacter strain other than H. pylori. For this Melanesian patient, a branch-specific PCR targeting the epsilon branch of Proteobacteria was used to amplify a 967-bp amplicon. This amplicon was sequenced and matched with the H. felis sequence. This was confirmed using an H. felis-specific urease PCR test.     

The GM2-1 ganglioside islet autoantigen in insulin-dependent diabetes mellitus is expressed in secretory granules and is not beta-cell specific

The pancreatic islet monosialo-ganglioside (GM2-1), an autoantigen in insulin-dependent diabetes mellitus (IDDM) recently shown to be the target of autoantibodies associated with diabetes development in relatives of IDDM patients, is islet specific within the pancreas, and its expression is metabolically regulatable. In the present study we sought to establish 1) whether GM2-1 is beta-cell specific, and 2) its intracellular localization. To this end, we analyzed the pattern of ganglioside expression in highly purified beta- and non-beta-cells isolated from rat islets. In addition, ganglioside levels were determined in subcellular fractions of a rat beta-cell line (INS). No qualitative or quantitative difference was found in the pattern of ganglioside expression between beta and non-beta rat islet cells, with GM3, GM2-1, and GD3 gangliosides expressed in both cell populations. Within INS cells, GM2-1 ganglioside was expressed in the fraction containing secretory granules and, to a lesser extent, in plasma membranes; GM3 was expressed in secretory granules, whereas GD3 was found only in plasma membranes. These data indicate that the GM2-1 autoantigen is not beta-cell specific within the islets, in accordance with the observation that this molecule is a target of islet cell autoantibodies that bind to the whole pancreatic islet. Interestingly, this autoantigen is present in secretory granules similarly to other autoantigens in IDDM (insulin, carboxypeptidase H, 38-kDa protein, etc.), suggesting that the autoimmunity to the components of this organelle may be central to the pathogenesis of the disease.     

Cloning of the human uroplakin 1B cDNA and analysis of its expression in urothelial-tumor cell lines and bladder-carcinoma tissue

The human uroplakin 1B (UPK1B) gene codes for a structural protein which is a terminal differentiation component of the asymmetric unit membrane on the apical surface of the mammalian bladder. UPK1B is a member of the tetraspan family of proteins, many of which have de-regulated patterns of expression in cancer. Using polymerase-chain-reaction techniques, we have cloned a partial human UPK1B cDNA which codes for the putative full open reading frame for the UPK1B protein. The deduced human UPK1B protein sequence has 92% and 93% amino-acid homology with bovine UPK1b and mink TI1 proteins respectively. Using Northern analysis, we show that the human UPK1B gene is highly expressed in normal human urothelium. However, expression of UPK1B mRNA was undetectable or markedly reduced in 11 out of 16 samples of transitional-cell-bladder-carcinoma tissue and in all 5 bladder-carcinoma cell lines when compared with normal urothelial tissue. The molecular mechanism of down-regulation of RNA expression does not appear to involve gross gene rearrangements or allelic loss.     

Cancer epigenetics comes of age

The discovery of numerous hypermethylated promoters of tumour-suppressor genes, along with a better understanding of gene-silencing mechanisms, has moved DNA methylation from obscurity to recognition as an alternative mechanism of tumour-suppressor inactivation in cancer. Epigenetic events can also facilitate genetic damage, as illustrated by the increased mutagenicity of 5-methylcytosine and the silencing of the MLH1 mismatch repair gene by DNA methylation in colorectal tumours. We review here current mechanistic understanding of the role of DNA methylation in malignant transformation, and suggest Knudson's two-hit hypothesis should now be expanded to include epigenetic mechanisms of gene inactivation.     

Maternal virus load and perinatal human immunodeficiency virus type 1 subtype E transmission, Thailand. Bangkok Collaborative Perinatal HIV Transmission Study Group

To determine the rate and risk factors for human immunodeficiency virus (HIV)-1 subtype E perinatal transmission, with focus on virus load, pregnant HIV-infected women and their formula-fed infants were followed prospectively in Bangkok. Of 281 infants with known outcome, 68 were infected (transmission rate, 24.2%; 95% confidence interval, 19.3%-29.6%). Transmitting mothers had a 4.3-fold higher median plasma HIV RNA level at delivery than did nontransmitters (P<.001). No transmission occurred at <2000 copies/mL. On multivariate analysis, prematurity (adjusted odds ratio [AOR], 4.5), vaginal delivery (AOR, 2.9), low NK cell percentage (AOR, 2.4), and maternal virus load were associated with transmission. As RNA quintiles increased, the AOR for transmission increased linearly from 4.5 to 24.8. Two-thirds of transmission was attributed to virus load>10,000 copies/mL. Although risk is multifactorial, high maternal virus load at delivery strongly predicts transmission. This may have important implications for interventions designed to reduce perinatal transmission.     

Analytical and biologic variability in measures of hemostasis, fibrinolysis, and inflammation: assessment and implications for epidemiology

CONTEXT: Central venous catheters impregnated with chlorhexidine and silver sulfadiazine have recently been introduced for the prevention of catheter-related infections. However, there remains some uncertainty regarding the efficacy of these catheters because of conflicting reports in the literature. OBJECTIVE: To evaluate the efficacy of chlorhexidine-silver sulfadiazine-impregnated central venous catheters in the prevention of catheter-related bloodstream infection. DATA SOURCES: Studies identified from a computerized search of the MEDLINE database from January 1966 to January 1998, reference lists of identified articles, and queries of principal investigators and the catheter manufacturer. STUDY SELECTION: Randomized trials comparing chlorhexidine-silver sulfadiazine-impregnated central venous catheters with nonimpregnated catheters were included. The outcomes assessed were catheter colonization and catheter-related bloodstream infection confirmed by catheter culture. DATA EXTRACTION: Twelve studies met the inclusion criteria for catheter colonization and included a total of 2611 catheters. Eleven studies with a total of 2603 catheters met the inclusion criteria for catheter-related bloodstream infection. Most patients in these studies were from groups considered to be at high risk for catheter-related infections. Summary statistics were calculated using Mantel-Haenszel methods under a fixed-effects model. DATA SYNTHESIS: The summary odds ratio for catheter colonization was 0.44 (95% confidence interval [CI], 0.36-0.54; P<.001), indicating a significant decrease in catheter colonization associated with impregnated catheters. The studies examining the outcome of primary interest, catheter-related bloodstream infection, had a summary odds ratio of 0.56 (95% CI, 0.37-0.84; P = .005). CONCLUSIONS: Central venous catheters impregnated with a combination of chlorhexidine and silver sulfadiazine appear to be effective in reducing the incidence of both catheter colonization and catheter-related bloodstream infection in patients at high risk for catheter-related infections.     

综合化多传感器空间管理模型与算法研究3

综合化多传感器管理概念的提出拓展了多传感器管理的内涵和功能,相应的空间管理模型与算法是一个重要的研究方向;首先建立综合化多传感器空间管理基本框架,然后在对空间标示及威胁度计算的基础上,提出了基于信号检测的多传感器空间管理算法,并建立了其动态管理中的状态转移向量,最后进行的仿真证明了该算法的有效合理性.     

CD1 expression by dendritic cells in human leprosy lesions: correlation with effective host immunity

A potential role for the CD1 family of lipid Ag-presenting molecules in antimicrobial immunity in vivo was investigated in human leprosy skin lesions. Strong induction of three CD1 proteins (CD1a, -b, and -c) was observed in dermal granulomas in biopsy samples of involved skin from patients with the tuberculoid form of leprosy or with reversal reactions, which represent clinical patterns of disease associated with active cellular immunity to Mycobacterium leprae. In contrast, lesions from patients with the lepromatous form of the disease who lack effective cell-mediated immunity to the pathogen did not show induction of CD1 proteins. Thus, expression of CD1 correlated directly with effective immunity to M. leprae, as assessed by the clinical course of infection. CD1a, -b, and -c could be induced to similar levels on monocytes from the blood of either tuberculoid or lepromatous leprosy patients. This suggested that the absence of expression in lepromatous lesions was most likely due to local factors at the site of infection as opposed to a primary defect of the CD1 system itself. The majority of cells expressing CD1 in leprosy lesions were identified as a population of CD83+ dendritic cells. Initial in vitro studies of the Ag-presenting function of CD1+CD83+ monocyte-derived dendritic cells showed that such cells were highly efficient APCs for CD1-restricted T cells. These results indicate that the CD1 system can be up-regulated in human infectious diseases in vivo, and may play a role in augmenting host defense against microbial pathogens.     

Membrane-type 1 matrix metalloprotease (MT1-MMP) enables invasive migration of glioma cells in central nervous system white matter

Invasive glioma cells migrate preferentially along central nervous system (CNS) white matter fiber tracts irrespective of the fact that CNS myelin contains proteins that inhibit cell migration and neurite outgrowth. Previous work has demonstrated that to migrate on a myelin substrate and to overcome its inhibitory effect, rat C6 and human glioblastoma cells require a membrane-bound metalloproteolytic activity (C6-MP) which shares several biochemical and pharmacological characteristics with MT1-MMP. We show now that MT1-MMP is expressed on the surface of rat C6 glioblastoma cells and is coenriched with C6-MP activity. Immunodepletion of C6-MP activity is achieved with an anti-MT1-MMP antibody. These data suggest that MT1-MMP and the C6-MP are closely related or identical. When mouse 3T3 fibroblasts were transfected with MT1-MMP they acquired the ability to spread and migrate on the nonpermissive myelin substrate and to infiltrate into adult rat optic nerve explants. MT1-MMP-transfected fibroblasts and C6 glioma cells were able to digest bNI-220, one of the most potent CNS myelin inhibitory proteins. Plasma membranes of both MT1-MMP-transfected fibroblasts and C6 glioma cells inactivated inhibitory myelin extracts, and this activity was sensitive to the same protease inhibitors. Interestingly, pretreatment of CNS myelin with gelatinase A/MMP-2 could not inactivate its inhibitory property. These data imply an important role of MT1-MMP in spreading and migration of glioma cells on white matter constituents in vitro and point to a function of MT1-MMP in the invasive behavior of malignant gliomas in the CNS in vivo.