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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 559 records · Page 31Linked to original sources
PubMed1996

A clinically viable index for quantifying denture plaque.

A denture plaque index using the dye disclosing method was evaluated in 24 patients with Type II denture stomatitis and 17 control subjects with healthy palatal mucosa. Patients with denture stomatitis had statistically significantly higher plaque scores than did controls, indicating a quantitative increase in denture plaque in patients with denture stomatitis. When this plaque index was tested by two examiners for intraexaminer and interexaminer reproducibility, it yielded a 92% to 96% reproducibility. The plaque index used in this study seems to satisfy the criteria for an ideal clinical index: It is simple, reliable, reproducible, and economical and can be carried out in the shortest possible time in a clinical setting.

Dental Plaque↗
PubMed1996

Health problems in rural elderly at Varanasi, Uttar Pradesh.

Present study comprised of 1070 elderly patients coming to P.H.C. Bhopauli, Varanasi during January 1991-December 1992. Males were 578 and females were 492. Male predominance was present in younger elderly whereas female predominance was seen among those over 75 years of age. Socio-economic status-wise 265 cases belonged to upper, 394 middle and 411 to lower income group. Arthritis (615) was the commonest disease in elderly followed by hypertension (510), visual problems (400), ischaemic heart disease (IHD) (350), hearing impairement (300), diabetes mellitus (DM) (280), protozoal and worm infestations (240), chronic bronchitis, asthma, emphysema (238), tuberculosis (220), peptic ulcer syndrome (210), varicose vein (200), haemorrhoids (180), urinary problems (154). Two hundred and forty seven cases had 2 diseases followed by 3 diseases (239), 4 diseases (165), 5 diseases (127) and more than 5 diseases (81). Multiple diseases were more frequent among those above 75 years of age. Atypical presentations and complications of different diseases were more frequent among older elderly.

Aged↗
PubMed1995

Cloning of the promoter-regulatory region of the murine growth hormone receptor gene. Identification of a developmentally regulated enhancer element.

The growth hormone (GH) receptor is essential for the actions of GH on postnatal growth and metabolism. To identify DNA sequences involved in the regulation of transcription of the murine GH receptor gene, a 17-kilobase genomic clone containing the 5'-flanking region, exon 1, and part of intron 1 of the murine GH receptor gene was isolated. Utilizing primer extension and ribonuclease protection assays, two major transcription start sites were identified in RNA from liver of male, female, and pregnant mice. Transient transfection studies using a reporter gene demonstrated promoter activity in a variety of eukaryotic cells. Deletional analysis and DNA-protein binding assays led to the identification of a 30-base pair enhancer element located about 3.4 kilobases upstream of the transcription start sites. Computer analysis of the nucleotide sequence of the enhancer element did not reveal any potential DNA binding motifs for known transcription factors, and this DNA element failed to exhibit binding activity for some common transcription factors. Analysis of both functional activity and DNA-protein binding activity of this enhancer element in adult and fetal hepatocytes suggests that this DNA element may play a role in the developmental expression of the GH receptor gene.

Animals↗
PubMed1995

Purine functional groups in essential residues of the hairpin ribozyme required for catalytic cleavage of RNA.

Synthetic chemistry techniques have been used to study the functional group requirements of the essential purine residues in hairpin ribozyme cleavage. Three-stranded ribozymes were prepared that had functional group deletions or alterations at single purine sites within loops A and B of the hairpin, and the kinetics of cleavage were compared to those of the unmodified ribozyme. Adenosine analogues used were purine riboside and N7-deazaadenosine, and guanosine analogues used were inosine, N7-deazaguanosine, and O6-methylguanosine. In many cases, introduction of one of these analogues caused substantial loss of ribozyme cleavage activity. Most of the impairments of activity were found to be due to changes in kcat rather than in KM. The losses corresponded in magnitude to loss of at least one hydrogen bond, and the results were rationalized in terms of removal of potential cross-strand hydrogen bonds as well as potential hydrogen bonds between loops A and B. A new secondary structure model for loop B was proposed. Finally, the magnesium ion dependence of cleavage was studied for the modified ribozymes and compared to that of the unmodified ribozyme. It is proposed that magnesium binds in the ground state to the N7-positions of G + 1 and A43 and in the transition state to the N7-position at A9. The results provide further evidence for the folding of the two arms of the hairpin so that in the active conformation loops A and B approach closely to form a specific three-dimensional structure with a magnesium ion (or ions) placed between the loops, making contacts in the ground state and in the transition state.

Adenosine↗
PubMed1995

Characterization of a winged bean (Psophocarpus tetragonolobus) protein kinase with calmodulin-like domain: regulation by autophosphorylation.

A soluble protein kinase purified from winged bean (Psophocarpus tetragonolobus) shoots, has been assessed as a monomeric enzyme with an approximate M(r) of 60,000 in spite of the presence of two polypeptides of 61 and 58 kDa determined by SDS/PAGE. Immunoblot analyses using either of the two antisera raised individually against the polypeptides, detect both of them in purified preparations and a single larger polypeptide (62 kDa) in freshly prepared tissue homogenates, clearly indicating the likelihood of the doublet being formed from the larger one by proteolysis. Histone H1, syntide 2 and a synthetic myosin light chain-related peptide (MLC-peptide) have been identified as exogenous substrates of the enzyme. Complete Ca(2+)-dependence for substrate phosphorylation, a drastic inhibition of the reaction by a calmodulin (CaM) antagonist which can be partially reversed by a heterologous CaM and direct 45Ca(2+)-binding on blot, form compelling evidence in favour of a CaM-like domain of the enzyme. Both the polypeptides of the purified enzyme undergo intramolecular autophosphorylation on serine residue(s). Unlike the substrate phosphorylation reaction, autophosphorylation is Ca(2+)-independent and is not inhibited by the CaM antagonist. Down-regulation of substrate phosphorylation by auto-phosphorylation, and stimulation of the autophosphorylation by histone H1 and MLC-peptide, are novel regulatory features of the enzyme.

Amino Acid Sequence↗
PubMed1995

Cross-recognition by T cells of an epitope shared by two unrelated mycobacterial antigens.

The molecular mimicry represented by cross-recognition of determinants shared by unrelated antigens by antibodies or T cells is of broad immunological interest. In this study, we analyzed the cross-recognition by CD4+ T cells of a peptide epitope shared by two mycobacterial proteins of diverse sequence, represented by the 19-kDa antigen of Mycobacterium tuberculosis and the 28-kDa antigen of Mycobacterium leprae. This epitope was immunodominant with respect to the 19-kDa antigen, but cryptic in relation to the 28-kDa antigen. The cross-reactive epitope cores were identified by Pepscan window analysis and found to be eight residues long in both antigens (residues 69-76 and 127-134). Alignment of these octameric sequences revealed two identical and five conservatively related amino acids. Within the epitope core, two residues (73Asn and 76Ile) were identified as critical for recognition on the basis of inhibition of the cross-reactive T cell proliferative response using singly substituted analog peptides. These results suggest that T cell cross-reactive epitopes can exist in proteins with apparently not more than random levels of sequence homology. Their potential for unsuspected cross-sensitization may play a role in the maintenance of T cell memory, in the pathogenesis of autoimmune diseases and possibly in a wide range of host immune responses to infectious pathogens.

Amino Acid Sequence↗
PubMed1995

The host response in graft versus host disease. III. The in vitro induction of regulatory cells in chronic murine graft versus host disease.

Murine graft versus host (GVH) disease takes two forms depending upon the parental/F1 strain combination employed. Acute lethal GVH disease is characterized by anemia, lymphopenia, hypogammaglobulinemia, profound anti-F1 cytotoxicity, and the loss of cytotoxic potential against third-party alloantigen. In contrast to this, chronic GVH disease is characterized by polyclonal B cell activation, autoantibody production, no anti-F1 cytotoxicity, and retained cytotoxicity against allotargets. We have previously reported that this marked disparity in disease expression results from a radiosensitive host cell which protects the F1 mouse from parental anti-F1 CTX in mice undergoing CGVH disease. Using an in vitro system to induce the host protective cell, we now demonstrate that two distinct Thy-1+ cells emerge which regulate CTX against the host. One cell is of host origin, radiation sensitive, and functionally resembles a veto cell. The second regulatory cell, of parental origin, is radiation resistant and restricted in its ability to suppress anti-F1 CTX. We further demonstrate that the emergence of these cells is modulated by competitive immunoregulatory influences mediated by T contrasuppressor and I-J+ cells.

Animals↗
PubMed1995

Identification of proteins specified by porcine epidemic diarrhoea virus.

Up to now, little was known about the proteins of porcine epidemic diarrhoea virus (PEDV). Using (i) metabolic labelling, (ii) antisera directed against synthetic peptides and monoclonal antibodies, and (iii) eukaryotic and prokaryotic expression systems, we have started to identify and characterize these proteins. The nucleocapsid protein (N) of PEDV was identified as a phosphoprotein with a relative mobility (M(r)) of 57 k. No additional phosphoproteins were detected. At least three glycoproteins were virion associated. The 180/200 k band most probably represented the surface glycoprotein (S), whereas the 27 k protein was the membrane protein (M). The 21 k species could not yet be identified. A rabbit anti-M protein antiserum was generated by using synthetic peptides corresponding to the C-terminus of M. The specificity of this serum was reconfirmed by transient expression of the M-gene in Vero cells followed by immunofluorescence. In order to generate antisera against the putative gene products of ORF3 and of the internal N reading frames (I-1, I-2, I-3), additional anti-peptide sera were raised. The putative ORF3 product which had been tagged by a 6 Histidine tail, was expressed in E. coli and purified by nickel chelate affinity chromatography before 2-dimensional polyacrylamide gel electrophoresis and immunostaining with a rabbit anti-peptide serum directed against the N-terminus of the ORF3 product. Transient expression of the I-1 and I-3 reading frames was used to confirm the specificity of the corresponding anti-peptide sera. The immunological tools presented in this paper are now being used to identify the putative corresponding gene products specified by PEDV.

Animals↗
PubMed1995

Aetiology of nephrolithiasis in north Indian children.

The aetiology of nephrolithiasis was investigated in 32 north Indian children (25 boys, 7 girls, mean age 7.9 +/- 3.3 years). An underlying disorder was detected in 16 (50%) patients and included idiopathic hypercalciuria (8 patients), hyperoxaluria (3 patients) and renal tubular acidosis, primary hyperparathyroidism and hyperuricosuria (1 patient each). Magnesium ammonium phosphate calculi were found in 2 patients with recurrent urinary tract infections, 1 of whom had a duplex pelvic collecting system. In 16 patients (50%) a cause for renal calculi was not identified. Our findings suggest that an underlying disorder is present in a large proportion of children with nephrolithiasis where appropriate treatment may be beneficial.

Calcium↗
PubMed1995

Elucidation of the life cycle of the intestinal protozoan Blastocystis hominis.

This paper elucidates the status of the different morphological forms of Blastocystis and reports the existence of thin- and thick-walled cysts in B. hominis on the basis of current experimental evidence. It is suggested that the thin-walled cysts are autoinfectious, leading to multiplication of the organism in the intestinal tract. The thick-walled cysts are responsible for external transmission via the faecal-oral route. A life cycle for B. hominis is postulated on the basis of these findings.

Acridine Orange↗
PubMed1995

Effect of Japanese mint (Mentha arvensis) oil as fumigant on nutritional quality of stored sorghum.

Japanese mint (Mentha arvensis) oil (JMO) can be used effectively as fumigant against Sitophilus oryzae in stored sorghum. The effect of JMO at a dose of 166 microliter/l of space on nutrient composition and protein quality was studied in infested and uninfested sorghum grains stored for 3 months. The results revealed non significant effect of JMO on gran moisture, total ash, crude fibre, crude fat, crude protein and fat acidity in infested and uninfested grains at the end of 3 months storage. The JMO treatment had small but significant effect on reducing and non-reducing sugars. The values of Protein Efficiency Ratio (PER) for uninfested JMO treated grains, infested JMO treated grains and for untreated control stored for 3 months were 1.11, 1.07 and 1.09, respectively against control casein diet for which it was 2.15.

Dietary Carbohydrates↗
PubMed1995

Vascular endothelial growth factor gene expression in ovine placenta and fetal membranes.

OBJECTIVE: The purpose of this study was to explore the gene expression of vascular endothelial growth factor (VEGF) in placental cotyledon, chorion, and amnion of the ovine fetus. STUDY DESIGN: Time-dated pregnant sheep with singleton or twin fetuses at a gestational age ranging from 100 to 140 days were used for the study. Placental cotyledonary, chorionic, and amniotic tissues were collected and processed for messenger ribonucleic acid analysis by Northern blotting and reverse transcription-polymerase chain reaction. RESULTS: By use of a phosphorus 32-labeled human VEGF complementary deoxyribonucleic acid probe, a prominent VEGF messenger ribonucleic acid transcript of 3.7 kb was detected in the cotyledon, chorion, and amnion. A minor band of 1.7 kb was also found but only in the cotyledon and chorion. The abundance of messenger ribonucleic acid encoding VEGF was highest (p < 0.001) in the cotyledon and lowest in the amnion. In these tissues polymerase chain reaction-amplified products corresponding to VEGF121, VEGF165, VEGF189, and VEGF206 were identified by ethidium bromide. In addition, a polymerase chain reaction fragment corresponding to VEGF145 was observed. These fragments produced specific hybridization signals with the human VEGF radioactive probe where the intensity of the signal was strongest for VEGF165 and weakest for VEGF189. CONCLUSIONS: VEGF gene expression was detected in the cotyledon, chorion, and amnion of the near-term ovine fetus. These findings suggest that vascular endothelial growth factor may play a role in the induction of angiogenesis and promotion of permeability in the microvessels that perfuse the placental and fetal membranes.

Animals↗
PubMed1995

Tubulovesicular elements in Blastocystis hominis from the caecum of experimentally-infected rats.

By transmission electron microscopy (TEM), tubulovesicular elements were seen in Blastocystis hominis obtained from the caecum of experimentally-infected rats. These appeared to arise from the peripheral cytoplasm and were rounded, oval or elongate in sections. It is suggested that these elements form a network for transfer of nutrients to the periphery during the process of encystation.

Animals↗
PubMed1995

Optimum kinetic energy dissipation to maintain blood flow in glass capillaries: an analysis based on flow field determination by axial tomographic and image velocimetry techniques.

The video micrographic images of fully developed blood flow in a glass capillary of diameter 200 microns are recorded. These data after digitization are analyzed by an IBM PC/AT-based image processing system to obtain erythrocyte and velocity distribution profiles by axial tomographic and image velocimetry techniques, respectively. The results obtained show that the parabolic profile of erythrocyte distribution at hematocrit 10% becomes more blunt at 60%. A similar increase in bluntness at the various hematocrit is observed for the velocity profiles. For calculation of kinetic energy dissipation a set of erythrocyte distribution profiles at each hematocrit with a transition from existing to parabolic one by multiparametric analysis, are constructed. The results show that the existing profiles as obtained at all hematocrits dissipate minimum kinetic energy. Any deviation towards parabolic form leads to dissipation of higher amount of the energy.

Algorithms↗
PubMed1995

Properties of rapidly adapting receptors of the airways in monkeys (Macaca mulatta).

The properties of rapidly adapting receptors (RARs) of the airways were examined in anaesthetised, artificially ventilated, paralysed and thoracotomised monkeys. The RARs were identified (i) by their rapid adaptation to a maintained inflation and forced deflation of the lungs and (ii) by their conduction velocity measurements. Right atrial (n = 17) and left atrial (n = 13) injections of histamine (10 micrograms/kg) stimulated the RARs. The stimulation was associated with an increase in peak intratracheal pressure. Right atrial injections of phenyl diguanide (n = 6, 10 micrograms/kg) and 5-hydroxytryptamine (n = 6, 10 micrograms/kg) did not produce a significant stimulation of the RARs. Administration of irritant vapours such as ammonia, (n = 12), cigarette smoke (n = 8), alcohol (n = 10), acetone (n = 10) and ether (n = 7), caused a significant stimulation of the RARs. This stimulation occurred in spite of a significant decrease or no change in peak intratracheal pressure. During mild degrees of pulmonary venous congestion produced by graded increments in mean left atrial pressure (+5 and +10 mmHg), there was a graded increase in RAR (n = 6) activity. The present study shows the existence of the RARs in the airways of the rhesus monkey. These receptors are stimulated (i) by administration of agents which cause bronchoconstriction (ii) by vapours which cause airway irritation and (iii) in conditions which cause an expansion of the extravascular space in airways.

Animals↗