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Biomedical subjects

V Singh

Publications and source records attributed to V Singh.

At least 253 records · Page 14Linked to original sources
PubMed1992

Influence of immunogen modification of the gonadotropin releasing hormone antibody reactivity.

The binding of MoAbs and PoAbs to native GnRH, azo-GnRH, GnRH-BSA and azo-GnRH-BSA conjugates was studied using a solid phase ELISA test. The use of carbonate/bicarbonate buffer (pH 9.2) significantly affected the coating of peptide to the ELISA plates. Azo-GnRH coated in PBS showed seven times less binding to MoAb than the native GnRH. Saturation analysis studies indicated comparable binding to the antibodies to the coated GnRH and GnRH-BSA but binding to azo-GnRH-BSA was higher than to azo-GnRH. The epitope recognition ability of MoAbs was therefore investigated. Blocking ELISA additivity tests were performed to analyse whether MoAbs recognised a common epitope involving a conformation or sequence of the modified peptide (azo-GnRH). The plates coated with azo-GnRH or azo-GnRH-BSA and saturated with MoAbs did not bind PoAbs. The inhibition activity was similar when GnRH or GnRH-BSA was used instead of azo-GnRH or azo-GnRH-BSA thus suggesting that the MoAbs were directed against a conformational epitope of the GnRH molecule.

Animals↗
PubMed1992

Immunospecificity and affinity studies on anti-luteinizing hormone releasing hormone antibodies developed by azo-LHRH-TT and azo-LHRH-BSA conjugates.

Monoclonal and conventional antibodies against the 'self' decapeptide LHRH produced by azo-LHRH-TT and azo-LHRH-BSA conjugates were studied for immunoreactivity with native LHRH, azo-LHRH, LHRH (OH) and its fragments of sequence 1-10, 7-10, 4-10 and 4-6. The CoAb reacted 8-20% to azo-LHRH, 2-6% to LHRH-Lys, 1-3% LHRH-LYS-MDP and 0.5-1.68% to LHRH-Ala-Ala-Tuftsin but failed to react to LHRH free acid and its fragments. On the other hand MoAb reacted 4-6% to azo-LHRH and 10-18% to LHRH-Lys, 3-5% to LHRH-Ala-Ala-Tuftsin. These results indicate that the azotization drastically inhibited immunoreactivity but that the azo-LHRH-carrier conjugate preserved the immunogenic epitope responsible for the induction of an effective anti-LHRH antibody response.

Amino Acid Sequence↗
PubMed1992

Coumarin congeners as antidepressants.

3-Carboethyl coumarin (I) was converted to coumarin 3-acid hydrazide (II). This on reaction with appropriate aldehyde yielded 3-arylidino amino coumarin (III). Compound III on diazotisation and reaction with ferric chloride yielded the corresponding formazans viz. 3-substituted phenyl azoarylidino, amido coumarins (IVa1-a10) and oxadiazoles viz. 2-aryl-5-(3-coumarinyl)-1,3,4-oxadiazoles (Va1-a3), respectively. Simultaneously 3-carboethyl coumarin on hydrolysis gave 3-carboxy coumarin (VI) which on reaction with aryl amine in methylene chloride yielded 3-(N-aryl)amido coumarin (VIIa1-a3). The compounds were screened for their antidepressant activity against a tricyclic antidepressant (imipramine). Compounds IVa4, IVa5 and IVa9 exhibited activity better than imipramine with no toxicity (ALD50 greater than 1000 mg/kg) but IVa5 showed some side effects.

Amphetamine↗
PubMed1992

Synthesis and pharmacological evaluation of some phenothiazines as antidepressants.

10-Hydrazino acetyl phenothiazine (II) has been converted to N-10-acetyl amino phenothiazine-N-phenyl thiourea (III) which have been converted to 3-aryl-1-(10-phenothiazine acetyl amino)-2,3-dihydro-2-thioxo-4,6-(1H,5H) pyrimidinones (IV) on condensation with aryl amines and aryl aldehydes yielded 3-aryl-1-(10-Phenothiazine acetyl amino)-5-(substituted phenyl amino methyl)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (Va-k) and 3-aryl-1-(10-phenothiazine acetyl amino)-5-(substituted phenylidine)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (vl-o). The compounds were screened for their antidepressant activity against a tricyclic antidepressant (imipramine). Compounds Va, Vf, Vm and Vi exhibited activity better than imipramine with no toxicity (ALD50 greater than 1000 mg/kg) but Vi showed some side effects.

Amphetamine↗
PubMed1992

Clinical and etiological profile of acute viral hepatitis.

There is a paucity of data on the incidence of sporadic viral hepatitis in Indian children. Clinical, biochemical and etiological profile of 54 patients with acute viral hepatitis was evaluated. Of these, 32 (59.25%) patients had Hepatitis A, 18 (33.33%) had NANB, 2 (3.7%) had Hepatitis B and 2 (3.7%) concurrent Hepatitis A and B infection. It was not possible to distinguish the etiological agents on the basis of the clinical and biochemical profile. Fulminant hepatitis was documented in 8 (14.8%) cases. Children with NANB infection were at a greater risk (p less than 0.05) of developing fulminant hepatitis as compared to Hepatitis A infection.

Acute Disease↗
PubMed1992

Effect of picroliv on protein and nucleic acid synthesis.

Oral administration of picroliv, a standardised fraction of roots and rhizomes of Picrorhiza kurroa, showed stimulation of nucleic acid and protein synthesis in rat liver. Results are comparable with a standard hepatoprotective agent, silymarin.

Animals↗
PubMed1992

Properties of a ribosome-inactivating protein, gelonin, purified using three different methods.

Ribosome-inactivating protein, gelonin, isolated from an Indian plant Gelonium multiflorum of Euphorbiaceae family has been used to design and synthesize immunotoxins and hormonotoxins for selective targeting purposes. Since gelonin isolated by aqueous extraction, cation-exchange chromatography and gel-filtration chromatography (Method I), contains non-proteinous material absorbing at 280 nm, the ammonium sulphate precipitation method (Method II) and Cibacron blue affinity chromatography method. (Method III) have been used to purify gelonin from the dry seeds. Three batches of gelonin purified by each method were prepared and subjected to extensive physico-chemical and immunochemical characterization. The molecular weight was determined by gel-filtration chromatography on a pre-calibrated Sephadex G-100, TSK-G4000 TW on HPLC or Superose-12 on fast protein liquid chromatography. In all cases, the molecular weight was approximately 30,000Da. The SDS-PAGE also revealed a homogeneous protein of 30kDa molecular weight. In Method II, the non-proteinous material which binds to CMC-gel in association of gelonin was substantially removed during ammonium sulphate fractionation. A careful analysis clearly revealed that Method II, although yielded low protein, gave gelonin devoid of the non-proteinous material. The SPDP modification of epsilon-NH2 groups of gelonin obtained from Methods I, II, and III was also carried out and its effect on immunoreactivity was studied.

Chemical Precipitation↗
PubMed1992

Significance of pleural effusion in patients with acute pancreatitis.

We retrospectively reviewed the charts of all patients with acute pancreatitis admitted to our hospital between July 1987 and June 1991 to determine the relationship of a pleural effusion in patients with acute pancreatitis with the severity of the disease, the etiology of the pancreatitis, pseudocyst formation, and triglyceride levels. Eleven (13.4%) of the 82 patients with acute pancreatitis had evidence of pleural effusion. Eight of 42 patients with alcoholic pancreatitis developed an effusion, compared with one of 33 patients with biliary pancreatitis, indicating that an alcoholic etiology may be a risk factor. Seven (63%) of the 11 patients had associated pseudocysts. Patients with severe disease had a greater incidence of pleural effusion. The effusion was on the left side in six, bilateral in four, and on the right side in one patient. Hypertriglyceridemia did not appear to be an independent risk factor associated with pleural effusions. Diagnostic thoracentesis was performed in three patients because of the presence of fever. Pleural fluid amylase was normal in one case and mildly elevated in the other two. All effusions resolved spontaneously without the need for any therapeutic intervention.

Acute Disease↗
PubMed1991

Screening for cervical cancer by direct inspection.

Since cytology-based screening programmes for cervical cancer cannot be provided on a large scale in developing countries, an alternative approach is needed. To find out whether visual inspection of the cervix is an adequate alternative, women with cytological evidence of dysplasia were followed up cytologically and colposcopically until cancer was detected, and the gross appearance of the cervix was recorded at each stage. Although only 40-50% of cancers were accompanied by abnormal-looking cervices, whereas 71% were detectable on cytology and 87% on colposcopy, visual inspection may be useful in areas where cytological screening programmes are not available.

Adult↗
PubMed1991

Effect of chronic microwave radiation on T cell-mediated immunity in the rabbit.

Experiments were conducted to elucidate the effects of chronic low power-level microwave radiation on the immunological systems of rabbits. Fourteen male Belgian white rabbits were exposed to microwave radiation at 5 mW/cm2, 2.1 GHz, 3 h daily, 6 days/week for 3 months in two batches of 7 each in specially designed miniature anechoic chambers. Seven rabbits were subjected to sham exposure for identical duration. The microwave energy was provided through S band standard gain horns connected to a 4K3SJ2 Klystron power amplifier. The first batch of animals were assessed for T lymphocyte-mediated cellular immune response mechanisms and the second batch of animals for B lymphocyte-mediated humoral immune response mechanisms. The peripheral blood samples collected monthly during microwave/sham exposure and during follow-up (5/14 days after termination of exposures, in the second batch animals only) were analysed for T lymphocyte numbers and their mitogen responsiveness to ConA and PHA. Significant suppression of T lymphocyte numbers was noted in the microwave group at 2 months (P less than 0.01, delta % 21.5%) and during follow-up (P less than 0.01, delta % 30.2%). The first batch animals were initially sensitised with BCG and challenged with tuberculin (0.03 ml) at the termination of microwave irradiation/sham exposure and the increase in foot pad thickness (delta mm), which is a measure of T cell-mediated immunity (delayed type hypersensitivity response, DTH) was noted in both the groups. The microwave group revealed a better response than the control group (delta % +12.4 vs. +7.54). The animals were sacrificed and the tissue T lymphocyte counts (spleen and lymph node) were analysed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Factors contributing to chromosome damage in lymphocytes of cigarette smokers.

Cigarette smoking is generally believed to be responsible for a substantial number of human health problems. However, the causal relationship between smoking, the induction of biological effects and the extent of health problems among smokers have not been fully documented. Using the recently developed lymphocyte micronucleus (MN) assay, we have evaluated the chromosome aberration frequencies in 67 cigarette smokers and 59 matched non-smoking control subjects. We found that the mean MN frequency (per 100 cells) in the smokers was slightly higher than that found in the non-smokers (0.71 +/- 0.23 and 0.58 +/- 0.05 respectively; p less than 0.08). Factors which contribute to the expression of chromosome aberrations were also investigated. A significant age-dependent increase in MN frequencies was observed in both groups (p less than 0.05). Linear regression analysis showed that the age-dependent effects among smokers (r = 0.54; p less than 0.02) was further enhanced by cigarette consumption (r = 0.62; p less than 0.005). Consumption of low potency 'one-a-day' type multivitamins had no effect on MN frequencies in either sex of non-smokers and in the 1 male smoker who took multivitamins but vitamin intake consistently reduced the MN frequencies among female smokers. Using a challenge assay, fidelity of DNA repair was evaluated. Lymphocytes from both smokers and non-smokers were irradiated with single doses of 0 or 100 cGy of X-rays or with double doses of 100 cGy of X-rays each separated by 15 or 60 min (100/15 or 100/60). Chromosome translocation frequencies were consistently higher after irradiation in lymphocytes from smokers than in those from non-smokers. Statistically significant differences were detected when the cells were irradiated with the double doses of 100 cGy X-rays each separated by 60 min (p less than 0.05). These data suggest that lymphocytes from smokers made more mistakes in the repair of DNA damage than cells from non-smokers. Our studies provide new insights into the genotoxic effects of cigarette smoke and new information which may be useful for understanding the mechanisms for induction of health problems from smoking.

Aging↗
PubMed1991

Piezoelectric effect in renal calculi.

The piezoelectric effect is investigated for the first time in renal calculi in vitro. The kidney stones are shaped from solid samples as well as from stones crushed into powder and pressed into tablets. Presence of alpha quartz in the renal calculi is investigated by an X-ray technique and the presence of this constituent also helps to explain the piezoelectric effect in the renal calculi. The dielectric and piezoelectric parameters are studied in detail.

Electric Conductivity↗