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Biomedical subjects

R Srivastava

Publications and source records attributed to R Srivastava.

At least 91 records · Page 5Linked to original sources
PubMed1993

Constitutive production of interleukin-8 (IL-8) by normal and malignant human B-cells and other cell types.

The culture supernatants from 43 human cell lines obtained during log phase and from purified normal peripheral blood B-lymphocytes cultured at 10(6) cells ml-1 for 48 h in RPMI 1640-5% fetal calf serum were examined for interleukin-8 (IL-8) using Elisa kits. Constitutive IL-8 production was found for 14/15 B-cell lines (5 derived from normal persons and 2 from AML patients, 1 pre-B-ALL, 2 CLL with trisomy 12, 2 HTLV-I+, 1 HTLV-II+, 1/2 Burkitt lymphoma), 4/16 T-cell lines (3/6 HTLV-I+, 1 HTLV-II+, 0/9 T-ALL), myeloid line HL-60, monocytoid line U937, 3/3 ovarian carcinoma, 1/1 endometriosis, 2/2 normal fibroblast, 0/2 C-ALL, 0/1 pre-erythroid line K562, as well as for normal B-lymphocytes. Later, cells examined by indirect immunofluorescence using IL-8 antibodies gave a positive reaction. DNA from 4 IL-8 producing and 3 non-producing cell lines, when probed with IL-8 cDNA gave the same 3.5 kb EcoRI fragment indicating similarities of the IL-8 gene in these cells. Two B-cell lines examined showed the expression of 1.8 kb IL-8 mRNA. These results indicate IL-8 production by a greater variety of cells than previously believed which open possibilities for new IL-8-mediated immune functions by such cells as B-cells.

B-Lymphocytes↗
PubMed1993

Identification of the flagellar antigens of Vibrio cholerae El Tor and their role in protection.

Antiserum to the surface antigens of the wild-type flagellate strain KB207 of Vibrio cholerae El Tor was absorbed with isogenic aflagellate mutant CD12. Antibodies remaining in the absorbed serum exhibited specificity to KB207 but not to CD12 and inhibited motility of KB207. Proteins from cell-free lysates of KB207 and CD12 were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. CD12 differed from KB207 in the absence of two proteins of 40 and 38 kDa. These proteins were detected in KB207 when electrophoretically separated proteins were immunoblotted with unabsorbed and absorbed sera. These two proteins were isolated by immunoaffinity chromatography using purified antibodies from absorbed serum. Although antigenic, the 40 and 38 kDa proteins did not induce protection against cholera in the rabbit ileal loop model.

Animals↗
PubMed1993

Identification of a 33 kDa antigen associated with an adhesive and colonizing strain of Vibrio cholerae El Tor and its role in protection.

Proteins from the cell-free lysates of the wild-type strain KB207 of Vibrio cholerae El Tor and the isogenic non-adhesive mutant CD11 were analysed by native and denaturing polyacrylamide gel electrophoresis. A protein of 33 kDa present in KB207 was absent from CD11. Antiserum to the surface antigens of KB207 was absorbed with CD11. Antibodies remaining in the serum after absorption reacted to KB207 but not to CD11 as judged by slide agglutination, double gel diffusion and dot blot ELISA. Antibodies in the absorbed serum inhibited adherence of KB207 to rabbit intestinal mucosa and colonization in an infant mice model. The 33 kDa protein was isolated from KB207 by immunoaffinity chromatography. Antibodies present in the absorbed serum were used as ligand. The 33 kDa antigen was immunogenic and conferred protection in the rabbit ileal loop model. Combined administration of 33 kDa protein and B-subunit of cholera toxin offered full protection.

Animals↗
PubMed1993

Age-dependent vulnerability of the striatum to the mitochondrial toxin 3-nitropropionic acid.

The mechanisms of delayed onset and cell death in Huntington's disease (HD) are unknown. One possibility is that a genetic defect in energy metabolism may result in slow excitotoxic neuronal death. Therefore, we examined the effects of age on striatal lesions produced by local administration of the mitochondrial toxin 3-nitropropionic acid in rats. In vivo chemical shift magnetic resonance imaging showed marked increases in striatal lactate concentrations that significantly correlated with increasing age. Histologic and neurochemical studies showed a striking age dependence of the lesions, with 4- and 12-month-old animals being much more susceptible than 1-month-old animals. Continuous systemic administration of low doses of 3-nitropropionic acid for 1 month resulted in striatal lesions showing growth-related changes in dendrites of striatal spiny neurons using the Golgi technique. These results show that a known mitochondrial toxin can produce selective axon-sparing striatal lesions showing both the age dependence and striatal spiny neuron dendritic changes that characterize HD.

Adenosine Triphosphate↗
PubMed1993

Evaluation of DNA-DNA hybridization for the direct detection of enterotoxigenic Escherichia coli in stool blots.

The simplicity of enterotoxigenic Escherichia coli (ETEC) stool blot hybridization, where the total bacterial growth of a fecal inoculum is examined directly for the presence of enterotoxin genes, has been marred by reports of unsatisfactory sensitivity and/or specificity. To assess the accuracy of stool blot hybridization and to study the effect of varying proportions of ETEC among fecal E. coli (ETEC/E. coli) on test performance, a detailed 'blind' study of 166 stool specimens from children with diarrhea was performed. Oligonucleotide probes were found to be superior to polynucleotide probes, having a sensitivity of 80%, a specificity of 99%, a positive predictive value of 89% and a negative predictive value of 97%. The sensitivity was found to be 100% when ETEC/E. coli > 2/12, as compared with 20% when ETEC/E. coli < or = 2/12 (p = 0.001), showing that the proportion of ETEC among fecal E. coli is of paramount importance for test sensitivity.

Bacteriological Techniques↗
PubMed1993

Neurochemical and histologic characterization of striatal excitotoxic lesions produced by the mitochondrial toxin 3-nitropropionic acid.

An impairment of energy metabolism may underlie slow excitotoxic neuronal death in neurodegenerative diseases. We therefore examined the effects of intrastriatal, subacute systemic, or chronic systemic administration of the mitochondrial toxin 3-nitropropionic acid (3-NP) in rats. Following intrastriatal injection 3-NP produced dose-dependent striatal lesions. Neurochemical and histologic evaluation showed that markers of both spiny projection neurons (GABA, substance P, calbindin) and aspiny interneurons (somatostatin, neuropeptide Y, NADPH-diaphorase) were equally affected. Subacute systemic administration of 3-NP produced age-dependent bilateral striatal lesions with a similar neurochemical profile. However, in contrast to the intrastriatal injections, striatal dopaminergic afferent projections were spared. Both freeze-clamp measurements and chemical shift magnetic resonance spectroscopy showed that 3-NP impairs energy metabolism in the striatum in vivo. Microdialysis showed no increase in extracellular glutamate concentrations after systemic administration of 3-NP. The lesions produced by intrastriatal injection or systemic administration of 3-NP were blocked by prior decortication. However, the NMDA antagonist MK-801 did not block the effects of intrastriatal 3-NP, consistent with a non-NMDA excitotoxic mechanism. In contrast to subacute systemic administration of 3-NP, chronic (1 month) administration produced lesions confined to the striatum in which there was relative sparing of NADPH-diaphorase interneurons, consistent with an NMDA excitotoxic process. Chronic administration showed growth-related proliferative changes in dendrites of spiny neurons similar to changes in Huntington's disease (HD). These results are consistent with in vitro studies showing that mild metabolic compromise can selectively activate NMDA receptors while more severe compromise activates both NMDA and non-NMDA receptors. Chronic administration of 3-NP over 1 month produces selective striatal lesions that replicate many of the characteristic histologic and neurochemical features of HD.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Intestinal colonization & production of diarrhoea by enteroadherent-aggregative Escherichia coli.

The ability of HEp-2 cell adherent Esch. coli of aggregative phenotype (EA-Agg EC) to cause diarrhoea and to colonize the bowel of rabbits was studied. Thirty six rabbits were challenged with one of three EA-Agg EC strains (F23A; H766C and F17A-15, 3 and 3 rabbits respectively) or a control strain (K12-15 rabbits) in reversible ileal-tie in adult rabbit diarrhoea (RITARD) model. The animals were sacrificed 72 h post challenge. Severe diarrhoea occurred in greater number of F23A challenged rabbits than the controls (P < 0.05). Mucosal cultures from proximal and distal small intestine and colon yielded about 1000 times more Esch. coli in the test than control rabbits (P < 0.001 in each case). EA-Agg EC were consistently grown from mucosa in the test rabbits who commonly showed mild to moderate villous stunting and grade + to nuclear fragmentation (karyorrhexis) in the small and large bowel epithelium. The control animals had either normal villi or very mild villous stunting. Results comparable to F23A were obtained with the other two EA-Agg EC strains tested in a smaller number of animals.

Animals↗
PubMed1992

Nonradioactive polynucleotide gene probe assay for the detection of three virulence toxin genes in diarrhoeal stools.

The present study describes a nonisotopic DNA-DNA hybridization assay for the detection of enterotoxigenic Escherichia coli (ETEC) in which the probes were labelled with the hapten molecule digoxigenin and after hybridization, DNA hybrids were detected by antidigoxigenin alkaline phosphatase conjugate. A blinded study carried out on a battery of enterotoxigenic and nonenterotoxigenic Esch. coli by dig-probe hybridization assay were compared with the results of a radiolabelled toxin gene probe hybridization assay (performed earlier). The three digoxigenin labelled probes gave a 100 per cent specificity and sensitivities of 95.45, 100 and 100 per cent for LT, STh and STp respectively. These results were comparable to those with the radioactive probes.

Child↗
PubMed1991

Structure of pescaproside E, a fatty acid glycoside from Ipomoea pescaprae.

Three fatty acid glycosides, designated pescaprosides A, B, and E, have been isolated from Ipomoea pescaprae (family Convolvulaceae). Chemical studies on pescaproside E, the major product, led to its characterisation as a pentaglycoside of 11-hydroxyhexadecanoic acid. Its sugar chain was esterified with 2-methylbutanoic and lauric acids. The structure of the pentaglycoside has been established as O-alpha-L-rhamnopyranosyl-(1----3)-O-[alpha-L-rhamnopyranosyl- (1----4)]-O-alpha-L-rhamnopyranosyl-(1----4)-O-beta-D-fucopyranosyl-(1-- --2)- O-alpha-L-rhamnopyranosyl-(1----11)-oxyhexadecanoic acid.

Carbohydrate Conformation↗
PubMed1991

Cloning of xylanase gene of Streptomyces flavogriseus in Escherichia coli and bacteriophage lambda-induced lysis for the release of cloned enzyme.

The xylanase gene of Streptomyces flavogriseus was cloned in pUC8 plasmid and expressed in Escherichia coli lysogenic for lambda cI857. lambda-Induced lysis of E. coli at 42 degrees C allowed efficient release of cloned enzyme activity in extracellular environment. The xylanase gene was located in the 0.8-kb HindIII fragment and coded for 18,000 Mr xylanase.

Bacteriophage lambda↗
PubMed1991

A class I jumping clone places the HLA-G gene approximately 100 kilobases from HLA-H within the HLA-A subregion of the human MHC.

By the combination of cosmid cloning, chromosomal jumping, and pulsed-field gel electrophoresis (PFGE), we have fine-mapped the HLA-A subregion of the human major histocompatibility complex (MHC). Through the isolation of a class I jumping clone, the Q alpha-like HLA-G class I gene has been placed within 100 kb of HLA-H. The tight physical linkage of these class I genes has been further supported by hybridizing PFGE blots with locus-specific probes. It has been found that both of the above class I genes are linked to HLA-A, with HLA-H residing no more than 200 kb from the HLA-A gene. These data support the possible existence of a Q alpha-like subregion composed of nonclassical HLA class I genes within the human MHC linked telomerically to the HLA-A locus.

Cell Line↗
PubMed1991

Perceived level and sources of stress in baccalaureate nursing students.

The purpose of this study was to investigate the perception of level and sources of stress in nursing students in the various years of the baccalaureate nursing program by identifying the general level of physiological and psychological health, identifying the levels of stress experienced by students in second-, third-, and fourth-year nursing and by identifying the areas that are perceived as being particularly stressful. The method was a descriptive correlational design. The sample consisted of 94 baccalaureate nursing students. Data were collected using two questionnaires--the General Health Questionnaire (GHQ) and the Stress Inventory. Data were analyzed using frequency distributions, t-tests, content analysis, measures of correlation, and analysis of variance. Results showed that the students experienced high stress levels and that they are at risk of having a physical or psychiatric illness. Analysis was done splitting the groups by student status, i.e., RN or generic. Results showed that while both groups are stressed, the generic students report significantly higher levels of stress. Sources of stress also were identified and reported in this article.

Education, Nursing, Baccalaureate↗
PubMed1990

Amplification of platelet response during acute inflammation in rats.

Enhanced aggregation of platelets was observed in platelet-rich plasma, but not in washed platelet suspension (WPS), during acute inflammation in rats. Incubation of WPS with inflammatory plasma increased the aggregatory response to ADP, but the plasma itself did not cause aggregation of platelets. It potentiated the aggregatory response of normal platelets, when platelets were stimulated with arachidonic acid, thrombin, calcium ionophore A23187 or phorbol-12-myristate-13-acetate. Pretreatment of rats with indomethacin (10 mg/kg) did not prevent the increased aggregation response of platelets due to inflammation. This response was not due to any of the biogenic amines nor was it due to platelet factor 4. The activity of the inflammatory plasma was reduced when it was incubated with phospholipase A2, indicating the involvement of platelet-activating factor (PAF). The activity was present both in the lipid and the protein fraction of the inflammatory plasma. The results indicate that a substance(s) released in the circulation during inflammation renders the platelets hyperactive. This substance appears to be a protein which is present in the inflammatory plasma and acts together with PAF to cause increased aggregation of platelets.

Acute Disease↗