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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 595 records · Page 33Linked to original sources
PubMed1995

Evaluation of a novel tuberculosis complex-specific 34 kDa protein in the serological diagnosis of tuberculosis.

Tuberculosis (TB) serological testing with antigen complexes, although very sensitive, is not always as specific due to reactive serum antibodies in patients with inactive TB or nontuberculous infections. Since the use of recombinant M. tuberculosis proteins may enhance specificity, this study was designed to evaluate a novel 34 kDa tuberculosis complex-specific protein as a component of an antigen panel of recombinant proteins. Seventy patients with active TB (41 positive and 29 negative for acid-fast bacilli (AFB) in sputum) were evaluated, in comparison with 30 tuberculin purified protein derivative skin test positive (PPD+) and 30 PPD- normals, 20 subjects with inactive TB and 20 PPD+ subjects with nontuberculous pneumonia as controls. Serum antibody levels were quantified using enzyme linked immunosorbent assay (ELISA) tests with MS2-34, a fusion protein comprising the NH2-terminal 16 kDa of the 34 kDa protein, a recombinant 38 kDa protein (p38), and PPD. Using MS2-34 and p38 as an antigen panel in active TB patients yielded higher sensitivity and negative predictive value (sensitivity 86%; negative predictive value 91%) than using PPD (sensitivity 66%; negative predictive value 81%). Importantly, the MS2-34+p38 panel yielded a higher sensitivity (83%) than PPD (66%) in the subset of AFB- active TB patients. Thus, this novel protein increases sensitivity and specificity of serological testing for TB when used in panels of recombinant proteins.

Adolescent↗
PubMed1995

The effect of ovariectomy and estradiol replacement on brain-derived neurotrophic factor messenger ribonucleic acid expression in cortical and hippocampal brain regions of female Sprague-Dawley rats.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder whose etiology is presently unknown. Probably the most consistent and widespread deficit seen in this syndrome is that of the basal forebrain cholinergic system. We have previously demonstrated that estradiol (E2) modulates the function of these neurons and plays a role in their maintenance by preventing the ovariectomy-induced decrease in choline acetyltransferase activity. It has been postulated that the lack of neurotrophic support may contribute at least in part to degeneration of cholinergic neurons in AD. As such, it is hypothesized that E2 may affect cholinergic function by modulating the levels of certain neurotrophic factors. We have shown that 3 months after ovariectomy (OVX) there was a significant reduction in NGF messenger RNA (mRNA) levels. In the present study, we extended the hypothesis that E2 may serve a neurotrophomodulatory role by assessing the effect of OVX and E2 replacement on brain-derived nerve factor (BDNF) mRNA levels using in situ hybridization. BDNF mRNA levels were quantified in three groups of animals: ovary-intact animals, 28-week ovariectomized (OVX) animals, and E2-replaced OVX animals. Twenty-eight weeks after OVX, there were significant reductions in two of the three cerebral cortical regions analyzed [frontal (35%) and temporal (39%) cortexes], but E2 replacement was without effect. Twenty-eight weeks after OVX, there were also reductions in BDNF mRNA in all subregions of the hippocampus except CA1 (CA2 by 38%, CA3 by 44%, CA4 by 39%, and dentate gyrus by 37%), whereas E2 replacement was effective in elevating BDNF mRNA levels in the CA3, CA4, and dentate gyrus subregions. Collectively, the data demonstrate that E2 deprivation leads to a reduction in BDNF mRNA. Further, at the time point studied, E2 replacement is more effective in maintaining BDNF mRNA in the hippocampus than in the cortex, suggesting a regional difference in the ovarian steroid requirement for expression of BDNF.

Analysis of Variance↗
PubMed1995

Effect of Japanese mint (Mentha arvensis) oil as fumigant on stored sorghum: physical characteristics, sensory quality and germination.

The Japanese mint (Mentha arvensis) oil (JMO) was effective as fumigant against Sitophilus oryzae in sorghum (Sorghum bicolor). The observations on the effect of JMO treatment at a dose of 166.6 microliters/l of space to grains stored for 3 months in desiccators at 28 +/- 5 degrees C showed non significant (P approximately 0.05) effect on grain hardness, grain density and per cent water absorption. The cooking quality evaluated in terms of cooking time required for boiling of grains was also not significantly affected. The JMO treated samples of boiled sorghum scored significantly lower values for sensory quality characteristics viz. taste, aroma and overall acceptability compared to untreated samples. No effect of JMO on seed germination was observed. As sensory quality is lowered by use of JMO, the technique can only be recommended for seed sorghum preservation, not food.

Edible Grain↗
PubMed1995

Deformation of erythrocytes and aggregates during sedimentation under microgravity.

The basic unit of an aggregate is an erythrocyte which possesses viscoelastic properties. To determine the changes in the shape of erythrocytes during sedimentation in microgravity field the present work is carried out. Fresh well mixed erythrocytes suspensions in plasma at 8% hematocrit are placed in a glass chamber. The entire experimental setup is mounted in a module and placed in a capsule. The online data on the sedimentation of the cells under normal and microgravity are recorded by a video microscopic system. The data are analysed by a PC/AT based image processing system. The results show that the erythrocyte undergoes a process of shape deformation and its sedimentation velocity decreases during microgravity. The erythrocyte from a nearly elliptic shape is transformed to nearly circular shape. A similar change in the projected area of the aggregate is also observed. This is further supported by a varying pattern of sedimentation velocity from normal to microgravity duration. The observed change in the erythrocyte membrane may contribute in the loosening of the large aggregates leading to formation of smaller size aggregates.

Blood Sedimentation↗
PubMed1995

Comparison of Pseudomonas pseudomallei from humans, animals, soil and water by restriction endonuclease analysis.

Pseudomonas pseudomallei isolates from 62 human, 17 animal, 3 soil and 3 water samples were examined by genomic DNA digestion with PstI. Five major (RE I, II, III, IV, V) reproducible restriction patterns were observed, with most (56/62) of the human isolates displaying RE I (30/62), II (5/62), III (15/62), IV (4/62), V (2/62), and the animal (16/17), soil (2/3), water (3/3) isolates showing predominantly RE II profiles. Six human and one soil isolates showed patterns different from those of RE I to V. Restriction endonuclease analysis may be applied in epidemiological studies of melioidosis.

Animals↗
PubMed1995

Aggregation and deformability of erythrocytes in leprosy.

The hemorheological parameters, erythrocyte aggregation and deformability are determined in leprotic patients and are compared with that of healthy subjects. The aggregation is determined by sequential analysis of the He-Ne laser transmission data through erythrocyte suspension at hematocrit 5%. The erythrocyte deformability is determined by measurement of passage time (reciprocal of deformability) of erythrocyte suspension in PBS at hematocrit 6% through cellulose membrane. The observations show that in leprosy the aggregation of erythrocyte is marginally reduced and the deformability is significantly increased. These parameters in combination with low hemoglobin and hematocrit levels in these patients lowers the blood viscosity to maintain the transport of material across the capillary wall.

Cell Aggregation↗
PubMed1995

Population genetic study among the Orange Asli (Semai Senoi) of Malaysia: Malayan aborigines.

A population genetic study was undertaken to provide gene frequency data on the additional blood genetic markers in the Semai and to estimate the genetic relations between the Semai and their neighboring and linguistically related populations by genetic distance and principal components analyses. Altogether 10 polymorphic and 7 monomorphic blood genetic markers (plasma proteins and red cell enzymes) were studied in a group of 349 Senoi Semai from 11 aboriginal settlements (villages) in the Pahang State of western Malaysia. Both the red cell glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (PGD) loci reveal the presence of polymorphic frequencies of a nondeficient slow allele at the G6PD locus and a fast allele at the PGD locus. The Semai are characterized by high prevalences of ahaptoglobinemia and G6PD deficiency, high frequencies of HP*1, HB*E, RH*R1, ACP*C, GLO1*1, PGM1*2+, and GC*1F and corresponding low frequencies of ABO*A, HbCoSp, HB*B0, TF*D, CHI, and GC*2. Genetic distance analyses by both cluster and principal components models were performed between the Semai and 14 other populations (Malay; Javanese; Khmer; Veddah; Tamils of Malaysia, Sri Lanka, and India; Sinhalese; Oraon; Toda and Irula of India; Chinese; Japanese; Koreans) on the basis of 30 alleles at 7 polymorphic loci. A more detailed analysis using 53 alleles at 13 polymorphic loci with 10 populations was carried out. Both analyses give genetic evidence of a close relationship between the Semai and the Khmer of Cambodia. Furthermore, the Semai are more closely related to the Javanese than to their close neighbors--the Malay, Chinese, and Tamil Indians. There is no evidence for close genetic relationship between the Semai and the Veddah or other Indian tribes. The evidence fits well with the linguistic relationship of the Semai with the Mon-Khmer branch of the Austro-Asiatic language family.

Adolescent↗
PubMed1995

Identification of two protein serine/threonine kinase genes and molecular cloning of a SNF1 type protein kinase gene from Toxoplasma gondii.

We report for the first time the identification of two protein kinase genes, in Toxoplasma gondii. Based on the conserved amino acid sequence motifs of catalytic subdomains VI(b) and IX of known protein serine/threonine kinases, degenerate oligonucleotides were synthesized and used in PCR to produce 196 and 373 bp DNAs. They encoded stretches of amino acid sequences characteristic of protein serine/threonine kinases. Dot and Southern blot analysis confirmed that these PCR products were of Toxoplasma origin. Screening of a genomic library of the organism with the 196 bp PCR product as a probe yielded 3 ToxPK1 g clones. Nucleotide sequence of two of these clones, revealed that the protein encoded, TOXPK1 resembled other carbon catabolite derepressing regulatory protein kinases. Therefore, we suggest that TOXPK1 could play a role in the interconversion of active and passive life-cycle stages of this parasite. RT-PCR studies on Toxoplasma tachyzoites' total RNA suggested that ToxPK1 gene is developmentally regulated. The 373 bp PCR product, however encoded a polypeptide that resembled the catalytic subunit of other cAMP-dependent protein kinases. Hence, this protein (TOXPK2) was considered as a product of another gene, ToxPK2.

Amino Acid Sequence↗
PubMed1995

Development of biosensor for glucose estimation by ion sensitive field effect technique.

In order to provide a better understanding of the Ion Sensitive Field Effect Devices (ISFED) as a biosensor, the C-V characteristics and the change in the flat band voltage of Electrolyte-Insulator-Semiconductor (Electrolyte-SiO2-Si) in response to pH are examined. The response of silicon oxynitride as an insulator to pH in EIS has better response compared to that of SiO2. The application of C-V characteristics of EIS as a biosensor for glucose estimation, is investigated. For this purpose glucose oxidase is immobilized on the surface. The change in the capacitance of this system (biased at constant voltage) to different concentrations of glucose is measured. The output response of differential capacitance shows a linear response to the variation of glucose concentration, thus providing a technique which could be used as a biosensor.

Biosensing Techniques↗
PubMed1995

Widespread emergence of Vibrio cholerae 0139 in India.

The National Institute of Communicable Diseases (NICD) has been monitoring the incidence of laboratory confirmed cases of cholera in Delhi in collaboration with Infectious Diseases Hospital (IDH) since 1965. Cholera and cholera-like cases from all hospitals in Delhi are admitted in IDH and the rectal swabs of all such cases are processed for isolation of Vibrio cholerae at NICD laboratory. Since April 1993, there has been isolation of Vibrio cholerae serotype 0139, in increasing numbers (831 out of 2,830, 29.2%) The isolates have been characterized and enterotoxin studies carried out. As a referral laboratory NICD has also confirmed the causative role of Vibrio cholerae 0139 in diarrhea outbreaks from various parts of the country. The implications of establishment of this newer serotype of Vibrio cholerae, as a potential epidemic strain are discussed.

Age Factors↗
PubMed1995

In vitro generation of soluble suppressor factor in murine chronic graft versus host (GVH) disease.

Veto cells are cells which suppress self directed cytotoxicity (CTX) regardless of the strain of origin of the cytotoxic effector cell. The mechanism by which veto cells inhibit self directed CTX is largely unknown. We have previously described the emergence of a veto cell in murine chronic graft versus host (CGVH) disease both in vivo and in vitro. Using an in vitro system in which veto cells are induced, we now report that a soluble factor is also induced which is capable of suppressing CTX. This cytotoxicity suppressing factor (CsF) is heat labile and has a molecular weight above 50 kD. The factor prevents the emergence of a cytotoxic effector cell. but is largely ineffective once the effector cell has functionally emerged. CsF is irreversible and is not restricted in its ability to inhibit anti-self CTX.

Animals↗
PubMed1995

An iron-binding Trypanosoma cruzi urinary antigen.

An 80-kDa Trypanosoma cruzi urinary antigen (UAg) was affinity-purified from the urine of infected dogs. We demonstrated that UAg is structurally and functionally related to proteins belonging to the transferrin family, as shown by amino acid sequence and iron binding experiments. Nevertheless, monoclonal antibodies raised against UAg specifically and selectively recognized this parasite's circulating antigen. The existence of an 80-kDa T. cruzi antigen co-migrating with UAg could be confirmed when epimastigotes were metabolically labelled with [35S] methionine and then immunoprecipitated with the above mentioned antibodies. We conclude that UAg is an iron-binding T. cruzi component eliminated in the urine of the infected host.

Amino Acid Sequence↗
PubMed1995

Symptomatic neonatal polycythemia: comparison of partial exchange transfusion with saline versus plasma.

A prospective study to evaluate efficacy and safety of partial exchange blood transfusion (PEBT) with normal saline or plasma was conducted in 30 symptomatic polycythemic newborns. Babies were randomly assigned to receive PEBT either with normal saline or plasma. Both groups were comparable in terms of birth weight, gestational age, preexchange hematocrit and viscosity. A significant fall in hematocrit and viscosity was noticed at 6 hours following PEBT which persisted even at 24 hours (P < 0.001). Hematocrit and viscosity were comparable in the two groups at 6 and 24 hours (p > 0.05 for both). Majority of babies became asymptomatic after 24 hours of PEBT, but one baby in the saline group remained polycythemic and symptomatic requiring repeat PEBT. No complications related to the procedure were encountered in the two groups. Partial exchange with normal saline was as effective and safe as plasma in symptomatic polycythemic newborns.

Blood Viscosity↗
PubMed1995

Assisted ventilation for hyaline membrane disease.

OBJECTIVES: To study the outcome and complications of assisted ventilation in neonates with hyaline membrane disease (HMD). DESIGN: Retrospective study. SETTING: Hospital based. SUBJECTS: Seventy five premature neonates with HMD needing assisted ventilation born over a period of five years. MAIN OUTCOME MEASURES: Survival rate among those ventilated and complications of assisted ventilation. RESULTS: Survival on assisted ventilation improved from initial 22.2% in 1989 to 77.8% in 1993. Of 19 babies weighing between 750-1000 g, 8(42.1%) survived. Twelve of 27 babies (44.4%) with a gestation of less than 28 weeks survived. Survival rates in babies with gestation of more than 33 weeks was 94%. Intraventricular hemorrhage was the leading cause of death in 52% babies. Nosocomial infections were common and occurred in 50.6% of infants on ventilation and accounted for one-third of deaths. Pneumothorax occurred in one-fifth of babies and was responsible for 3 deaths. Pulmonary interstitial emphysems was observed in 6 babies. Six babies developed bronchopulmonary dysplasia while 7 had retinopathy of prematurity. CONCLUSIONS: Outcome of neonates needing assisted ventilation for HMD has shown consistent improvement over the period of study. Nosocomial infections continue to be a major complication of assisted ventilation in neonates.

Cause of Death↗
PubMed1994

Structure of polymerizable lipid bilayers VII: lateral organization of diacetylenic phosphatidylcholines with short proximal acyl chains.

As an extension of recent results (Rhodes, Xu and Bittman (1992) Biochim. Biophys. Acta 1128, 93; Hui, Xu and Bittman (1992) Langmuir 8, 2724) with a C18 diacetylenic phosphatidylcholine, bilayers of 1,2-bis(pentacosa-4,6-diynoyl)-sn-glycero-3-phosphocholine (C25) were investigated using X-ray diffraction on multibilayers and electron diffraction on Langmuir-Blodgett deposited bilayers. Monolayers of this lipid form solid (gel phase) domains at pi > 14 mN/m. Electron diffraction data indicated that the chain spacing in these domains is 4.25 A and that the chains are tilted at angle of approximately 35 degrees relative to the bilayer plane. Wide angle data from X-ray diffraction experiments indicated a similar spacing and chain tilt. Small angle data showed that the lamellar repeat was 70 A at high humidity and < or = 60 A at low humidity. The bilayer electron density profiles indicated a bilayer structure with no interdigitation. High angle reflections indicate that the principal acyl chain repeat is preserved as a function of hydration but some rearrangement occurs for other reflections. The approximately 10 A reflection corresponding to the headgroup spacing previously observed with C18-diacetylenic phosphatidylcholine bilayers was not observed. The results are interpreted in terms of a packing model and possible limitations or constraints to the polymerization process.

Acetylene↗
PubMed1994

Intradermal gene immunization: the possible role of DNA uptake in the induction of cellular immunity to viruses.

The skin and mucous membranes are the anatomical sites were most viruses are first encountered by the immune system. Previous experiments have suggested that striated muscle cells are unique among mammalian cell types in their capacity to take up and express free DNA in the absence of a viral vector or physical carrier. However, we have found that mice injected into the superficial skin with free (naked) plasmid DNA encoding the influenza nucleoprotein gene had discrete foci of epidermal and dermal cells, including cells with dendritic morphology, that contained immunoreactive nucleoprotein antigen. A single intradermal administration of 0.3-15 micrograms of free plasmid DNA induced anti-nucleoprotein-specific antibody and cytotoxic T lymphocytes that persisted for at least 68-70 weeks after vaccination. Intradermal gene administration induced higher antibody titers than did direct gene injection into skeletal muscle and did not cause local inflammation or necrosis. Compared with control animals, the gene-injected mice were resistant to challenge with a heterologous strain of influenza virus. These results indicate that the cells of the skin can take up and express free foreign DNA and induce cellular and humoral immune responses against the encoded protein. We suggest that DNA uptake by the skin-associated lymphoid tissues may play a role in the induction of cytotoxic T cells against viruses and other intracellular pathogens.

Amino Acid Sequence↗