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Biomedical subjects

V Shankar

Publications and source records attributed to V Shankar.

At least 91 records · Page 5Linked to original sources
PubMed1986

Seckel's syndrome.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1981

Synthesis of a series of new N1-[4-(4-nitrophenylthio)phenyl]-N3-(H/alkyl/acyl/aryl) thioureas and their antifungal, insecticidal and larvicidal activities.

A series of new mono and disubstituted thioureas, derived from 4-(4-nitrophenylthio) aniline, have been prepared and screened for antifungal activity against Alternaria alternata and Curvularia lunata. Their insecticidal and larvicidal activities have also been evaluated against adult male and female cockroaches (Periplanata americana) and mosquito larvae (Culex pipiens fatigans Wied) of IIIrd and early IVth instar stage, respectively. The tabulated results reveal that most of the thiourea derivatives, in general, possess marked antifungal, insecticidal and larvicidal properties, but the chlorosubstituted derivatives, in particular, are the most active compounds in the entire series. Compound 20, N1-[4-(4-nitrophenylthio)phenyl]-N3-(4-chlorophenyl) thiourea, was the most active antifungal compound, whereas, compound 12, N1-[4-(4-nitrophenylthio)phenyl]-N3-(4-chlorobenzoyl) thiourea, was the most potent insecticidal and larvicidal compound.

Alternaria↗
PubMed1981

A study of drug resistance among Salmonella typhi and Salmonella paratyphi A in an endemic area, 1977-79.

Tests for antibiotic resistance were carried out on 198 strains of Salmonella typhi and S. paratyphi A isolated from cases of enteric fevers. Their minimal inhibitory concentrations for streptomycin, chloramphenicol, ampicillin, furazolidine and co-trimoxazole were estimated by plate dilution technique. Four strains of S. typhi and one strain of S. paratyphi A were found to show multiple resistance with a set pattern of resistance to chloramphenicol, streptomycin, sulphonamide, tetracycline and spectinomycin. All the five strains carried R-factors. Three of the resistant S. typhi belonged to Phage type 'O' and one was in Phage type 'A'. The single resistant S. paratyphi A belonged to Phage type '2'.

Ampicillin↗
PubMed1976

5-Methylcytosine content in the vertebrate deoxyribonucleic acids: species specificity.

RNA-free native DNA samples, isolated by four methods, from different vertebrate tissues and species, were hydrolyzed chemically and enzymatically and analyzed by paper chromatography to estimate the base composition. It was noted that (i) all the DNA preparations analyzed contained 5-methylcytosine, (ii) on the basis of mole percent of 5-methylcytosine, the composition of DNA varied in different species, but not so much in different tissues of the same species, (iii) the method of DNA hydrolysis, but not the method of deproteinization, affected the mole percent of 5-methylcytosine, and (iv) no 5-hydroxymethylcytosine (5-HMC) was detected in any of the DNA preparations analyzed.

Animals↗
PubMedDate not supplied

S1 nuclease: immunoaffinity purification and evidence for the proximity of cysteine 25 to the substrate binding site.

A simple procedure, involving heat treatment, gel filtration on Sephadex-G 100 followed by chromatography on anti-S1 nuclease antibodies bound to Sepharose, was developed for purification of S1 nuclease to homogeneity with an overall yield of 72%. S1 nuclease was rapidly inactivated, at pH 6.0 and 37 degrees C, in presence of o-phthalaldehyde. Kinetic analysis of o-phthalaldehyde medicated inactivation showed that the reaction followed pseudo-first-order kinetics and the loss of enzyme activity was due to the formation of a single isoindole derivative per molecule of the enzyme. Absorbance and fluorescence spectrophotometric data also gave similar results. The isoindole derivative formation, as a result of o-phthalaldehyde treatment is known to occur through crosslinking of the thiol group of cysteine and the epsilon-amino group of lysine, situated in close proximity in the native enzyme. Since, modification of the only available cysteine residue (Cys25) did not affect the catalytic activity of the enzyme, the o-phthalaldehyde mediated inactivation of S1 nuclease is due to the modification of lysine. Substrates of S1 nuclease, namely ssDNA, RNA, 3'AMP, could protect the enzyme against o-phthalaldehyde mediated inactivation. Moreover, the modified enzyme (having very little catalytic activity) showed a significant decrease in its ability to bind 5'AMP, a competitive inhibitor of S1 nuclease, suggesting that the modification has occurred at the substrate binding site. The above results point towards the presence of cysteine 25 in close proximity to the substrate binding site.

Animals↗
PubMedDate not supplied

Do neonates with meconium aspiration syndrome require antibiotics?

A randomized clinical trial was conducted to evaluate the utility of antibiotics in the routine management of Meconium Aspiration Syndrome (MAS). Neonates diagnosed to have MAS were randomly allocated to either the antibiotic group (n = 20) receiving gentamicin for 7 days, or the control group (n = 20), receiving no antibiotic. All infants were given identical supportive care. The two groups were comparable with respect to birth weight, gestation, sex distribution, mode of delivery, Apgar scores, and initial clinical and radiological severity of the illness. Results showed that the mean duration and the severity of respiratory distress at 24 hours and 48 hours were similar in the two groups. No secondary infection was documented in either group. A single death occurred in the antibiotic group. It is concluded that empirical use of antibiotics in the routine management of meconium aspiration syndrome is of no benefit.

Anti-Bacterial Agents↗
PubMedDate not supplied

Pathology of the diffuse variant of supravalvar aortic stenosis.

Supravalvar aortic stenosis is a rare congenital heart anomaly, producing left ventricular outflow tract obstruction. Of the two anatomic variants that have been described, diffuse type is the rarest. We report five such cases in children between two months and nine years of age. None had features of Williams syndrome. The entire aorta was involved in three cases, with abdominal aortic coarctation in two cases. Stenosis was mainly due to involvement of the media, which showed smooth muscle hypertrophy, abnormal elastic fibers, and mild collagenization. Predominant intimal change was seen in one case. Pulmonary, coronary, arch, renal, and common iliac arteries were also involved.

Aorta, Abdominal↗