Diagnosis of typhoid fever: detection of Salmonella typhi porins-specific antibodies by inhibition ELISA.

Porins are highly immunogenic outer membrane proteins of Salmonella. Sera from typhoid patients contained a high level of IgG antibodies directed to porins of Salm. typhi. Since porins are highly conserved proteins, anti-porins antibodies both from typhoid patients and healthy normals reacted with porins from several Gram-negative bacteria. Therefore, in order to improve the specificity of detecting Salm. typhi porins-specific antibodies, an inhibition ELISA was developed using enzyme-conjugated MoAbs (MP1 and MPN4) specific to Salm. typhi porins. Sera from typhoid patients with positive haemoculture (16 out of 17) inhibited the binding of MP1 to porins, thus showing a positive test for typhoid, whereas sera from patients with other Gram-negative bacterial infections (n = 7) and from healthy volunteers (66 out of 67) were found to be negative. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of this assay were 94.1, 98.7, 97.8, 94.1 and 98.7% respectively. The validity of our inhibition ELISA for typhoid was higher than that of the Widal test. The diagnosis of typhoid fever as early as 3 days after the onset of fever, using a single specimen is possible.     

Prion protein is ubiquitinated after developing protease resistance in the brains of scrapie-infected mice

Although the key event in the pathology of prion diseases is thought to be the conversion of cellular prion protein (PrP(C)) to the protease-resistant scrapie species termed PrP(Sc), the factors that contribute to neurodegeneration in scrapie-infected animals are poorly understood. One probable determinant could be when the accumulation of PrP(Sc) in infected brain overwhelms the ubiquitin-proteasome system and triggers the degenerative cascade. In the present study, it was found that in mouse brains infected with the ME7 scrapie strain, the level of ubiquitin protein conjugates increased significantly at approximately 144 days post-infection (pi) when clinical signs first become apparent. This elevation correlated with the detection of protease-resistant PrP(Sc) and a decline in two endopeptidase activities associated with proteasome function. However, ubiquitination of PrP was only detected at the terminal stage, 3 weeks after the development of clinical symptoms (approximately 165 days pi). These results suggest that ubiquitination of PrP is a late event phenomenon and this conjugation occurs after the formation of protease-resistant PrP(Sc). Whether this post-translational modification and the impairment of proteasome function are pivotal events in the pathogenesis of prion diseases remains to be determined.     

生物素─链霉亲和素系统在检测巨细胞病毒抗体中的应用

本文用自制ＣＭＶ抗原和生物素－链霉亲和素系统试剂，通过最适条件的对比，建立了检测人血清中抗巨细胞病毒ＩｇＭ、ＩｇＡ类抗体的ＢＳＡ－ＥＬＩＳＡ，并与普通ＥＬＩＳＡ作比较，结果表明，ＢＳＡ－ＥＬＩＳＡ的非特异性吸附明显低于普通ＥＬＩＳＡ，与普通ＥＬＩＳＡ相比，抗体效价分别提高５和７倍，阳性率分别提高６８％和１５３．５％。在实际工作中曾用ＢＳＡ－ＥＬＩＳＡ检测临床样品１６５份，就所得结果进行分析。表明ＢＳＡ－ＥＬＩＳＡ检测ＣＭＶＩｇＭ和ＩｇＡ可提高特异性和灵敏度，值得推广应用。     

Role of oxidative stress,angiogenesis and chemo-attractant cytokines in the pathogenesis of ischaemic protection induced by remote ischaemic conditioning: Study of a human model of ischaemia-reperfusion induced vascular injury

Aims

We explored the effect of remote ischaemic conditioning (RIC) on endothelial function and on circulating mediators.

应用单克隆抗体测定纤维连结蛋白ELISA方法的建立

本文介绍用McAb作为包被和检测抗体进行双抗体夹心ELISA来测定人血浆纤维连结蛋白。通过实验找出最佳条件,即两种McAb混合使用,在McAb和酶结合物稀释液内加入4％PEG及使用TMBI底物的最适浓度等,该法敏感性可达80ng/ml,可作为临床常规方法使用。     

Adsorption of anti-dsDNA antibodies by immobilized polyanionic compounds.

Antibodies to dsDNA are characteristically present in serum from patients with systemic lupus erythematosus (SLE), and have been shown to have the capacity to react with various molecules bearing repeating negative charges. After a number of polymeric or monomeric molecules with differently charged groups and hydrophobic molecules had been coupled covalently as ligands on cellulose gel, the adsorption capacities of the ligands for anti-dsDNA antibodies were evaluated. It was found that gels coupled with polyanionic dextran sulphate (DXS) and polyacrylic acid (PA) and monoanionic sulphanilic acid (SA) absorbed anti-dsDNA antibodies effectively. DXS gel also adsorbed antibodies to ssDNA and heparan sulphate, antigens with repeating negatively charged moieties, while no ligand was able to adsorb anti-nRNP antibodies. The finding that DXS gels adsorbed anti-dsDNA antibody in proportion to their charge density, and that the interaction between anti-dsDNA and DXS gel is broken readily by an increase in ionic strength, indicated that the binding is ionic in nature. Moreover, virtually all F(ab')2 anti-dsDNA became adsorbed onto the DXS gels, suggesting that the binding occurred via specific antigen-binding sites on the antibody molecule. Binding of these polyanion-binding autoantibodies with anionic sites in the glomerular basement membrane may therefore cause the tissue damage observed in SLE.     

Horizontal transmission of hepatitis B virus infection in household contacts, Pune, India

The study was undertaken to detect the risk of infection, if any, among 193 household contacts of 40 hospitalised hepatitis patients (group I) with hepatitis B surface antigen (HBsAg) in their blood. As a control group, 103 household contacts of 27 hospitalised hepatitis patients who were negative for HBsAg (group II) were investigated. The family contacts of the former group had a significantly higher prevalence of HBV infection than those of the latter group (P less than .001). Significant differences were observed both in the prevalence of HBsAg (P less than .05) and antibody to HBsAg (anti-HBs) (P less than .025) between the two groups. IgM antibody to hepatitis B core antigen (anti-Hbc-IgM) was detected in 32 out of the 39 (82%) sera tested from the patients of group I with HBsAg. A statistically significant difference (P less than .005) of HBV prevalence was also found in the contacts of these 32 patients suffering from acute hepatitis B as compared to the contacts of the patients of group II. Overall, the children of the first group showed a significantly higher prevalence of HBsAg as compared to the second group. All the children with HBsAg were positive for HBeAg also, but were negative for anti-HBc-IgM. Anti-HBs was detected in a significantly larger number of adult females. Spouses were found to be affected more than other relatives. A significant difference (P less than .025) was noted in the number of families having HBV markers in group I (80.0%) as compared to those in group II (48.1%).(ABSTRACT TRUNCATED AT 250 WORDS)     

The significance of blood levels of IgM,IgA, IgG and IgG subclasses in Sudanese visceral leishmaniasis patients

We developed an ELISA test using leishmania antigenic extracts to detect antigen-specific antibody responses, including subclass and isotype analysis, in visceral leishmaniasis (VL) patients from the Sudan. A total of 92 parasitologically proven patients were compared with cutaneous leishmaniasis, schistosomiasis, malaria, onchocerciasis and tuberculosis patients, as well as with healthy endemic and non-endemic controls. Some VL patients were examined before and after chemotherapy. VL patients showed significantly higher IgG responses compared with all other groups (93·4% sensitivity, 93·7% specificity), and higher (but not significantly) IgM responses. All groups showed low IgA levels. All groups showed low IgA levels. All IgG subclasses, IgG1, 2, 3, and 4, showed higher levels in patients than all other groups, with IgG1 and IgG3 levels being significantly reduced following treatment. The rank order for specificity and sensitivity for IgG subclasses was IgG3 > IgG I> IgG2> IgG4.     

Hepatitis C virus seroconversion rate in established blood donors

The results of hepatitis C virus (HCV) antibody test of 237, 813 blood donations collected from 143, 815 donors by the West Midlands Blood Transfusion Centre in 1993 were analyzed retrospectively in order to determine the seroconversion rate among established previously anti-HCV negative donors. Three hundred sixteen (0.22%; 1 in 455) donors were positive by the enzyme linked immunosorbent assay (ELISA) screening test and 34 (0.024%; 1 in 4, 230) donors were positive by ELISA and the Recombinant Immuno Blot Assay (RIBA). Three donors previously negative for HCV antibody reacted positively by both tests. The annual seroconversion rate was calculated as one in 35, 937 donors. This figure argues against limitation of HCV antibody screening to new blood donors. A further 45 donors negative on previous screening reacted positively by ELISA and were indeterminate by RIBA. Unexpectedly, lapsed blood donors first tested for HCV antibody in 1993 had high positive reaction rates by ELSA and RIBA, which was significantly (P < 0.001) higher than those of new donors. RIBA-positive reaction rate among ELISA-positive donors was significantly higher amongst males than females (P < 0.0011. © 1995 Wiley-Liss, Inc.