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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 487 records · Page 27Linked to original sources
PubMed1997

Evaluation of the recombinant 38-kilodalton antigen of Mycobacterium tuberculosis as a potential immunodiagnostic reagent.

The diagnosis of infection caused by Mycobacterium tuberculosis is of increased public health concern following increases in the number of cases in developed countries and major increases in developing countries associated with the spread of human immunodeficiency virus (HIV) infection. The specificity of purified protein derivative skin testing for the detection of infection is compromised by exposure to environmental mycobacteria. Examination of sputum detects the most infectious patients, but not those with extrapulmonary disease. The 38-kDa antigen of M. tuberculosis contains two M. tuberculosis-specific B-cell epitopes. We overexpressed the gene for this antigen in Escherichia coli and evaluated the recombinant product in in vitro assays of T-cell function and as a target for the antibody response in humans. The sensitivity and specificity of the antigen as a skin test reagent were also assessed in outbred guinea pigs. We found that 69% of healthy sensitized humans recognize the antigen in vitro, as manifested by both cell proliferation and the production of gamma interferon. Untreated patients initially have a lower frequency of response (38%); this recovers to 72% during therapy. A total of 292 patients (20 with HIV coinfection) and 58 controls were examined for production of antibody to the 38-kDa antigen by using a commercially available kit. The sensitivity of the test in comparison with that of culture was 72.6%, and the specificity was 94.9%. The antigen was also tested for its ability to induce skin reactions in outbred guinea pigs sensitized by various mycobacterial species. The antigen provoked significant skin reactions in M. tuberculosis-, M. bovis BCG-, and M. intracellulare-sensitized animals. The significance of these findings and the usefulness of this antigen in immunodiagnosis are discussed.

AIDS-Related Opportunistic Infections↗
PubMed1997

Most basal I(SC) in Calu-3 human airway cells is bicarbonate-dependent Cl- secretion.

Serous cells secrete antibiotic-rich fluid, but secretion is impaired in cystic fibrosis. We are investigating Calu-3 cells as a serous cell model. Basal short-circuit current (I[SC]) in Calu-3 cells grown at air interface had a basal I(SC) approximately six times larger than submerged cultures (69 +/- 22 vs. 11 +/- 10 microA/cm2). Basal I(SC) in either condition was reduced only 7 +/- 5% by bumetanide and was unaffected by apical amiloride, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), or calixarene but was reduced 77 +/- 18% by N-phenylanthranilic acid. Three transport mechanisms accounted for almost all basal I(SC). The largest component is HCO3(-)-dependent Cl- secretion. Replacement of Krebs-Henseleit solution with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered solution and changing gassing from 95% O2-5% CO2 to air reduced the basal I(SC) by 61 +/- 10%. Acetazolamide decreased basal I(SC) by 33 +/- 6%, whereas acetazolamide + basolateral DNDS eliminated 42-58% of the bumetanide-insensitive basal I(SC). Neither DNDS nor acetazolamide had any effect when applied in HCO3(-)-free solution. Apical phlorizin, a blocker of Na+-glucose cotransport, eliminated one-half of the remaining I(SC). Cl- replacement with gluconate eliminated all I(SC) except the phlorizin-sensitive component. Unlike basal I(SC), 80 +/- 24% of stimulated I(SC) was inhibited by bumetanide. Thus basal and stimulated secretions are mediated by different mechanisms.

Amiloride↗
PubMed1997

Calcium-stimulated Cl- secretion in Calu-3 human airway cells requires CFTR.

Human airway serous cells secrete antibiotic-rich fluid, but, in cystic fibrosis (CF), Cl(-)-dependent fluid secretion is impaired by defects in CF transmembrane conductance regulator (CFTR) Cl- channels. Typically, CF disrupts adenosine 3',5'-cyclic monophosphate (cAMP)-mediated Cl- secretion but spares Ca(2+)-mediated secretion. However, in CF airway glands, Ca(2+)-mediated secretion is also greatly reduced. To determine the basis of Ca(2+)-mediated Cl- secretion in serous cells, we used thapsigargin to elevate intracellular Ca2+ concentration ([Ca2+]i) in Calu-3 cells, an airway cell line bearing some similarities to serous cells. Cells were cultured using conventional and air interface methods. Short-circuit current (Isc) and transepithelial conductance (Gte) were measured in confluent cell layers. Thapsigargin stimulated large, sustained changes (delta) in Isc and Gte, whereas forskolin stimulated variable and smaller increases. delta Isc was decreased by basolateral bumetanide, quinidine, barium, or diphenylamine-2-carboxylate (DPAC) but was unaffected by high apical concentrations of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 4,4'-dinitrostilbene-2,2'-disulfonic acid, and calixarene. Isc was measured after permeabilizing the basolateral membrane and establishing transmembrane ion gradients. Unstimulated apical membranes displayed high Cl- conductance (GCl) that was decreased by DPAC but not by DIDS. Apical GCl could be increased by elevating intracellular cAMP concentration but not [Ca2+]i. We conclude that CFTR channels are the exclusive GCl pathway in the apical membrane and display approximately 60% of maximum conductance at rest. Thus elevated [Ca2+]i increases K+ conductance to force Cl- through open CFTR channels. We hypothesize that loss of CFTR channels causes diminution of cholinergically mediated gland secretions in CF.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1997

Identification and characterization of single strand DNA-binding protein that represses growth hormone receptor gene expression.

The GH receptor is essential for the actions of GH on growth and metabolism. Electromobility shift assay established that a 42-bp enhancer element in the promoter of the L1 transcript of the murine GH receptor bound nuclear proteins specific for the coding strand or the DNA duplex. Using methylation interference footprinting and electromobility shift assay with mutant oligonucleotides, the DNA-binding sites for the single-strand DNA-binding protein (SSBP) and the double-strand DNA-binding protein (DSBP) were mapped and shown to be contiguous with partial overlap. Shift-Western analysis indicated that the SSBP was a component of the DSBP complex. A functional interaction between SSBP and DSBP was suggested by the effect of the exclusion of SSBP on equilibrium binding and dissociation rate ("off rate") of the DSBP-DNA complex. Experiments using the anionic detergent deoxycholate provided evidence for a direct protein-protein interaction between SSBP and DSBP. Using lectin-affinity chromatography, discordance between the pattern of O-glycosylation of SSBP and DSBP was demonstrated. Transient transfection experiments support the role of SSBP as a repressor of DSBP's activation of transcription of the GH receptor gene. Southwestern analysis indicated that a protein of molecular mass 23-kDa exhibited binding activity specific to the coding strand of the enhancer element. We conclude that single- and double-strand DNA-binding proteins conjointly regulate the expression of the murine GH receptor gene.

Animals↗
PubMed1997

Dynamic trunk strength of Canadian football players, soccer players, and middle to long distance runners.

Muscle strength data for sports which have varying demands on the trunk musculature are needed. The purpose of this study was to measure the trunk strength of three different sports groups of male varsity athletes and a recreationally active but nontrained group. Forty-six athletes (soccer: N = 16, Canadian football: N = 15, and middle and long distance runners: N = 15) and 15 recreationally active subjects were studied. Three consecutive concentric and eccentric contractions through a range of 60 degrees at an angular velocity of 30 degrees per second (0.5236 rad/sec) were performed to measure the strength of the trunk flexors and extensors. Results showed peak concentric and eccentric flexor torque for football and soccer players to be significantly greater than the other two groups (p < or = 0.05). Peak concentric and eccentric extensor torque was significantly greater for football players than runners (p < or = 0.05). Soccer players' eccentric flexor peak torque relative to body mass was significantly greater than runners and the recreationally active subjects (p < or = 0.05). This study compares trunk flexor and extensor data for specific sports populations.

Adolescent↗
PubMed1997

Referred adolescents as young adults: the relationship between psychosocial functioning and personality disorder.

OBJECTIVE: To examine the functioning of young adults who had been referred for psychiatric treatment during adolescence. METHOD: A group of 145 adolescents referred at a mean age of 14 years were interviewed at a mean age of 20 years to ascertain their functioning and whether they suffered from a personality disorder. RESULTS: Having a personality disorder was associated with poor functioning at follow-up independently of adolescent diagnosis. Antisocial personalities were typified by problems with the law, a poor work record and early cohabitation, while other personality disorders were characterised by social isolation and problems in interpersonal relationships. Poor quality of the family environment and having received treatment during the follow-up period were the only developmental variables associated with poor functioning. CONCLUSIONS: Developing a personality disorder and having a poor family environment, rather than having an adolescent disorder, appear to be the factors that result in poor functioning in young adults.

Adolescent↗
PubMed1997

Nucleotide sequence of ToxPK1 gene from Toxoplasma gondii.

We report here for the first time a complete nucleotide sequence (6.8 kb) of a protein kinase gene (ToxPK1) from the obligate intracellular protozoan parasite of man, Toxoplasma gondii. This gene comprising putatively of 9 exons and 8 introns forms the Toxoplasma gene with the largest number and size of introns reported so far. The predicted protein with 508 amino acids contains the 15 invariant residues as well as the characteristic motifs specific to protein serine/threonine kinases. Homology-based computational comparisons suggested that TOXPK1 belongs to or closely resembles the SNF1 subfamily of protein-serine/threonine kinases. Based on the functions of SNF1 homologs in other organisms and our RT-PCR results, it is likely that TOXPK1 may be transiently expressed to up-regulate glycogen biosynthesis during the development of tachyzoites into bradyzoites.

Amino Acid Sequence↗
PubMed1997

Effect of Prunus amygdalus seeds on lipid profile.

The effect of Prunus amygdalus, which is rich in unsaturated fat, fibre diet and low cholesterol was studied in 36 normolipidemic male albino rabbits for 60 days. Three different doses i.e. whole seeds defatted and oil showed a decrease in serum total cholesterol, triglyceride, LDL cholesterol, VLDL cholesterol and an increase in phospholipid, faecal sterol and HDL cholesterol. The maximum effects where shown by whole seeds followed by oil and defatted.

Animals↗
PubMed1997

A study of combined filtration and adsorption on nylon-based dye-affinity membranes: separation of recombinant L-alanine dehydrogenase from crude fermentation broth.

Dextran, hydroxyethylcellulose (HEC), and poly(vinyl alcohol) PVA were covalently linked to bisoxirane-activated nylon membranes. Cibacron Blue F3G-A was immobilized on to these membranes to yield a dye-affinity membrane. The hydrodynamic permeability of affinity membranes was reduced to approximately 50% of that of the original Nylon membrane due to extension of polymer coils into flow-through pores. Adsorption of pre-purified human serum albumin (HSA) and malate dehydrogenase (MDH) displayed highest maximum binding capacities on HEC-coated dye-ligand-affinity membranes, ranging from (163 micrograms/cm2 for HSA to 316 micrograms/cm2 for MDH. The protein recovery of HSA was 100% on dextran-coated membranes compared with 70% on PVA-coated membranes, whereas almost 100% recovery was found for MDH, independent of the polymer. Application of crude supernatant from recombinant Escherichia coli yielded purification factors of 7.4, 8.9 and 11.2 for recombinant alanine dehydrogenase from Mycobacterium tuberculosis for HEC-, dextran- and PVA-coated membranes respectively. Dynamic capacities decreased remarkably to approximately 3 micrograms/cm2 due to co-adsorption of host proteins. The presence of cell debris caused only a slight decrease of purification factors, but a dramatic decrease of the permeability of affinity membranes due to development of a particle layer in front of the membranes. Although enzyme recoveries were up to 90% using cell-free supernatant, more than 50% of the product was lost due to polarization, concentration and rejection at particle layers when using crude homogenates. In order to further improve this integrated downstream process, sophisticated membrane techniques are required by which the formation of a filter cake is circumvented. Further refinement of polymer-coated membranes would not help one to avoid this problem.

Alanine Dehydrogenase↗
PubMed1997

Role of eicosanoid inhibition of ischemia reperfusion injury: intact and isolated rat heart studies.

The effects of FPL-55712 (leukotriene receptor antagonist) and OKY-046 (thromboxane synthase inhibitor) were studied on ischemic and reperfused myocardium using in vivo and in vitro rat heart paradigms. The in vivo studies included production of regional ischemia by coronary artery ligation for 72 h followed by reperfusion. Macroscopic methods using nitro blue tetrazolium (NBT) staining were employed to measure infarct size. For in vitro studies, isolated rat hearts were perfused by Langendorff's technique. Regional ischemia was produced for 60 min followed by reperfusion. Coronary outflow and creatine phosphokinase (CPK) release in the coronary effluent were measured. Both these parameters showed a correlation with the duration of reperfusion. In isolated heart studies, FPL-55712 reduced CPK release and improved coronary outflow significantly, whereas OKY-046 did not show any beneficial effect. In intact heart studies, FPL-55712 did not reduce the infarct size, whereas OKY-046 decreased the myocardial infarct to a significant extent. The present study demonstrates a definite involvement of leukotrienes and thromboxanes in reperfusion injury. Inability of FPL-55712 to reduce infarct size may be due to the very short half-life of the drug. Lack of efficacy of OKY-046 in isolated studies suggests the involvement of platelet-derived thromboxanes in the reperfusion injury as these are not available in isolated heart preparations.

Animals↗
PubMed1997

Intravenous magnesium sulfate in acute severe asthma not responding to conventional therapy.

OBJECTIVE: To evaluate the effectiveness of early administration of intravenous Magnesium sulfate (i.v. MgSO4) in children with acute severe asthma not responding to conventional therapy. DESIGN: Randomized double-blind, placebo-controlled trial. SETTING: Pediatric emergency service of a large teaching hospital. SUBJECTS: 47 children aged between 1-12 years with acute severe asthma showing inadequate or poor response to 3 doses of nebulized salbutamol given at an interval of 20 min each. INTERVENTION: The MgSO4 group received 0.2 ml/kg of 50% MgSO4 as intravenous (i.v.) infusion over 35 minutes and the placebo group received normal saline infusion in the same dose and at the same rate. MgSO4 solution and normal saline were coded and dispensed in identical containers. Decoding was done at the completion of the study. All the patients received oxygen, nebulized salbutamol, i.v. aminophylline and corticosteroids. RESULTS: MgSO4 group showed early and significant improvement as compared to placebo group in PEFR and SaO2 at 30 min and 1, 2, 3 and 7 hours after stopping the infusion (p ranging from < 0.05 to < 0.01). The clinical asthma score also showed significant improvement in the MgSO4 group 1, 2, 3 and 11 hours after stopping the infusion (p < 0.01). CONCLUSION: Addition of MgSO4 to conventional therapy helps in achieving earlier improvement in clinical signs and symptoms of asthma and PEFR in patients not responding to conventional therapy alone.

Acute Disease↗
PubMed1997

Hypoglycemic effect of Prunus amygdalus seeds in albino rabbits.

On administration of 2.5 g almond seed and its proportionate fractions, viz. 1.22 g defatted seed and 1.28 g oil to three groups of albino rabbits, they showed a definite hypoglycemic action during a two months study. The active factor seems to be a non oil fraction which is only partly soluble in ethyl ether.

Animals↗
PubMed1997

Partitioning a vocabulary's IS-A hierarchy into trees.

Controlled medical vocabularies are useful in application areas such as medical information-systems and decision-support. However, such vocabularies are large and complex, and working with them can be daunting. It is important to provide a means for orienting users to the vocabulary's contents. This paper introduces a methodology for partitioning a vocabulary into small, meaningful pieces. The partitioning is done with respect to the vocabulary's IS-A hierarchy. The methodology, based on a set of rules for refining the IS-A hierarchy, is a process carried out by a user in conjunction with the computer. The methodology is demonstrated on a complex portion of a vocabulary.

Classification↗
PubMed1997

Therapeutic value of bovine saliva in wound healing: a histomorphological study.

Biopsies were collected from the control (normal saline solution treated) and saliva treated wounds (back and loin region) of calves on 3rd, 7th, 14th, 21st and 28th days post-wounding. A faster connective tissue and epidermal regeneration was observed in saliva treated group. The inflammatory response was subdued as early as on 3rd day. On the 14th day the test wounds were covered with a dense layer of fibroblast and collagen and epidermal growth started. On 21st day the condensation of collagen and vascularization of the scar tissue was further augmented. By 28th day, the wounds were completely filled and nearly 85% of the wound surface was covered with epidermis.

Animals↗