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Biomedical subjects

R Srivastava

Publications and source records attributed to R Srivastava.

At least 19 recordsLinked to original sources
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↗
PubMed1990

Salmonella typhimurium-associated severe protracted diarrhea in infants and young children.

Eleven (13.8%) children (4-14 months; mean of 7.8 +/- 3.6 months) presenting with protracted diarrhea (duration greater than 21 days) and weight loss had associated infection with Salmonella typhimurium. All had documented weight loss of 16-25% and progressive clinical deterioration. On admission, they had high purging rates (greater than 4 ml/kg/h), hyponatremia (5/11), mucosal injury, and malabsorption as measured by 1 h blood D-xylose, fecal alpha 1-antitrypsin, and oral fat tolerance test. Diarrhea was secretory in 8 of 11 and fecal sodium was high (54-142 mEq/L; mean of 102 +/- 27 mEq/L). The organism showed multiple drug resistance. All patients received antibiotics (amikacin and nalidixic acid/norfloxacin) for 10-14 days, which was followed by rapid improvement in clinical status and absorption studies. The two youngest patients died. Due to ethical reasons, an untreated control group was not included. Use of appropriate antibiotics may benefit children with S. typhimurium-associated severe protracted diarrhea and rapid progressive weight loss.

Amikacin↗
PubMed1990

Transcription analysis, physical mapping, and molecular characterization of a nonclassical human leukocyte antigen class I gene.

The human major histocompatibility complex contains approximately 20 class I genes, pseudogenes, and gene fragments. These include the genes for the three major transplantation antigens, HLA-A, HLA-B, and HLA-C, as well as a number of other genes or pseudogenes of unknown biological significance. Most of the latter have C + G-rich sequences in their 5' ends that are unmethylated in the B-lymphoblastoid cell line 3.1.0. We investigated one of these genes, HLA-H, in more detail. The gene is, overall, strongly homologous in sequence to HLA-A but differs in several potentially significant ways, including changes in conserved promoter sequences, a single-base deletion producing a translation termination codon in exon 4, and a region of sequence divergence downstream of the transcribed portion of the gene. Nevertheless, mouse L cells transfected with the gene accumulated small amounts of apparently full-length polyadenylated RNA. A portion of this RNA begins at the transcription site predicted by analogy to certain class I cDNA clones, while another portion appears to begin shortly upstream. L cells transfected with a hybrid gene containing the first three exons of HLA-H and the last five exons of HLA-B27 accumulated full-length HLA transcripts at the same level as cells transfected with an HLA-B27 gene; both levels are at least 15- to 20-fold higher than that directed by HLA-H alone. In addition, we isolated a cDNA clone for HLA-H that contains a portion of intron 3 attached to a normally spliced sequence comprising exons 4 through 8. These results suggest that low levels of translatable mRNA for the truncated class I heavy chain encoded by HLA-H are produced under physiologic circumstances and that sequences 3' of intron 3 decrease the levels of stable transcripts.

Amino Acid Sequence↗
PubMed1990

Nephronophthisis with bronchiectasis.

A boy with nephronophthisis and bronchiectasis, a previously unrecognised association is described. Electron-microscopic examination of a renal biopsy from an asymptomatic sibling revealed marked thickening and lamination of the tubular basement membranes.

Biopsy↗
PubMed1990

Circadian variation of serum urea concentration in north Indian subjects.

Circadian rhythm of serum urea concentration was studied in 25 clinically healthy, diurnally active, nocturnally resting young male Indians. The mean urea concentration was observed to be 22.32 mg/dl at 0800 h which increased gradually reaching maximum at 0000 h with a mean of 31.00 mg/dl. A marked circadian variation in serum urea was recorded with a statistically significant amplitude and acrophase at 2232 h (Cosinor analysis). The observation that serum urea concentration oscillates physiologically in the peripheral blood according to a circadian rhythm may prove to be of importance in the clinical interpretation of values at different times along the 24 h light-dark period.

Adolescent↗
PubMed1990

Interaction of ethanol, cholesterol and vitamin A on phospholipid methylation in hepatic microsomes of rats.

Effect of ethanol, cholesterol and vitamin A either alone or in combination has been studied on cyt P450 and phospholipid methylation in hepatic microsomes of rats. Ethanol increased cyt P450 activity and decreased phospholipid methylation. Cholesterol effects were opposite to ethanol. Combination of cholesterol and ethanol decreased cyt P450 activity and increased phospholipid methylation. Vitamin A, which alone did not affect cyt P450 activity and phospholipid methylation behaved like cholesterol when given along with ethanol.

Animals↗
PubMed1989

Isolation and characterization of ribosomal DNA variants from Sciara coprophila.

The ribosomal RNA multigene family in the fungus fly Sciara coprophila contains a total of only 65 to 70 repeat units. We explored the types and frequencies of variant repeats in this small multigene family by characterizing different cloned rDNA variants from Sciara. Although we did not observe any intergenic spacer length variants in Sciara, we found a variant due to the insertion of a putative mobile element (lambda Bc11), and variants containing ribosomal insertion elements. By DNA sequence analysis of rDNA/non-rDNA junctions, there are three distinct types of ribosomal insertion elements found in Sciara rDNA: two correspond to the R1 and R2 insertion elements found in other dipterans (clones lambda Bc5 and pBc1L1, respectively), and one is a novel class of ribosomal insertion elements (R3, exemplified by clone pBc6D6) which so far is unique to Sciara. Together, the several different rDNA variants make up from 12 to 20% of the rDNA in Sciara. These results are discussed in the context of evolution of the ribosomal RNA multigene family.

Animals↗
PubMed1989

Role of free radicals in pulmonary thromboembolism in mice.

Involvement of free radicals and their scavenging enzymes in mice pulmonary thromboembolism, induced by intravenous infusion of collagen and adrenaline, has been studied. Malonaldehyde (MDA) and activities of xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD) were estimated in platelets, heart and lung homogenates. MDA increased in all the tissues sharply, while animals showed 70-80% thrombocytopenia. Xanthine oxidase activity in these animals increase significantly in heart. However, increased SOD activity and decreased catalase activity was observed in platelets. Intravenous administration of superoxide dismutase (5 mg/kg), catalase (5 mg/kg) and mannitol (200 mg/kg) protected the mice against pulmonary thromboembolism. The importance of free radicals in mice pulmonary thromboembolism has been demonstrated.

Animals↗
PubMed1989

Antithrombotic effect of thiopurinol.

Antithrombotic activity of ten pyrazolo pyrimidine derivatives was tested in mouse pulmonary thromboembolism model. Out of these compounds, Thiopurinol (C5H4N4S) showed dose-dependent protection in mice from death/paralysis induced by collagen + adrenaline. It also caused dose-dependent inhibition of thrombus formation in the cat. Thiopurinol inhibited aggregation of platelets induced by ADP and arachidonic acid but did not inhibit superoxide generation. It had no antiinflammatory activity nor any effect on cardiovascular system. The results indicate that the antithrombotic activity of the compound is mediated via inhibition of platelet aggregation.

Allopurinol↗