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Biomedical subjects

S Kumar

Publications and source records attributed to S Kumar.

At least 235 records · Page 13Linked to original sources
PubMed1990

Aortic dissection in a non-marfanoid child.

A nine year old girl presented with chest pain and dyspnoea of sudden onset. She had no marfanoid features, with a normal slit lamp examination and a normal aortic valve on echocardiography. The diagnosis of dissecting aneurysm of the ascending aorta involving the aortic valve cusps, the right coronary artery and the pericardium was later established with the help of ECG, pericardiocentesis, echocardiography and aortography.

Aortic Dissection↗
PubMed1990

Primary ascaridial perforations of small intestine and Meckel's diverticulum.

The clinical presentation of six cases with primary ascaridial perforations of the terminal ileum (4 cases) and Meckel's diverticulum (2 cases), without any associated underlying intestinal disease, is described. All the cases presented clinically as peritonitis and had worm masses in the intestinal lumen with maximal impaction in the terminal ileum. Ileal perforations were surgically closed in two layers after removal of the worms. Diverticulectomy after removal of the worms was performed for Meckelian diverticular perforations. Peritoneal toilet was done in all the cases. Pressure necrosis from the impacted worm masses probably resulted in these perforations.

Ascariasis↗
PubMed1990

Morbidity and mortality of acute myocardial infarction in and around Aligarh.

A 6-year retrospective study of 341 cases of acute myocardial infarction admitted to JN Medical College Hospital, Aligarh in respect of the incidence, complications and mortality in relation to age, sex, religion, smoking habit occupation and risk factors was made. The incidence was found to be 9 per 1000 hospital admissions. Maximum number of cases was in the age group of 51-60 years and male to female ratio was 7:1. There was no significant difference in incidence and mortality between Hindus and Muslims of both sexes. Highest incidence was noted among sedentary workers and smokers. Hypercholesterolaemia was found in only 17.01% cases, the rest having normal serum cholesterol levels. Hypertension and diabetes mellitus were associated in 24.05% and 12.32% cases respectively. Cardiac complications were noted in 43.4% of patients, the commonest being cardiac failure. Overall in-hospital mortality was observed to be 11.41% of which 79.49% had cardiac complications. Diabetics had significantly (p less than 0.05) higher mortality rate (21.43%) as compared to non-diabetics. Smokers had higher mortality rate compared to non-smokers (p less than 0.01). Although those with hypertension and with hypercholesterolaemia had higher mortality, the results were not statistically significant. The average day of expiry after acute myocardial infarction was 3.82 days during hospital stay.

Adult↗
PubMed1990

Binary conjugational transfer system of vectors pRK290 and pLAFRI is proficient both ways between Escherichia coli and Rhizobium.

Wide host range vector plasmids pRK290 and pLAFRI carrying genomic fragments of Rhizobium are transferable both ways between R. meliloti and R. leguminosarum cells on the one hand and to E. coli cells on the other, in triparental matings involving E. coli cells carrying pRK2013, the helper for Tra functions to the vector plasmids. The vector plasmids pRK290 and pLAFRI can be employed for recovering clones harbored by R. leguminosarum and R. meliloti by transfer to Rhizobium cells by direct matings of the library with them.

Cloning, Molecular↗
PubMed1990

Pulp calcifications in primary teeth.

One hundred and twenty primary maxillary and mandibular extracted teeth were collected to study the occurrence and nature of pulp calcifications. The teeth were serially sectioned, stained with hematoxylin and eosin, examined by light microscope. Pulp calcifications were observed in 31 (25.8%) teeth. Two types of pulp calcifications were noticed i.e., diffuse calcifications and free/attached type denticles. The occurrence of pulp calcification appears identical in all teeth except in the first primary molar which is statistically not significant (P greater than 0.05). The low prevalence of pulp calcifications in the primary teeth support the view that pulp calcification increases as the age advances.

Dental Pulp Calcification↗
PubMed1989

Mutagenicity of dihydrodiols and diol epoxides of dibenz[a, h]acridine in bacterial and mammalian cells.

Bay-region diol epoxides are ultimate carcinogenic metabolites of a number of polycyclic aromatic compounds. Dibenz[a, h]acridine can form two diastereomeric pairs of these diol epoxides which are not positionally equivalent as a result of the nitrogen atom at position 7. We have assessed the structure-activity relationships resulting from heterocyclic nitrogen substitution by examining the mutagenic activity of these four bay-region diol epoxides of dibenz[a,h]acridine in both bacterial and mammalian cells. In strains TA98 and TA100 of Salmonella typhimurium, the diastereomeric 10,11-diol-8,9-epoxides were 20 to 40 times more mutagenic than the corresponding 3,4-diol-1,2-epoxides. Furthermore, in strain TA100, dibenz[a,h]acridine 10,11-dihydrodiol, the expected metabolic precursor of the 10,11-diol-8,9-epoxide, was metabolically activated by rat hepatic microsomes up to a 12-fold greater extent than the 3,4-dihydrodiol. In Chinese hamster V79 cells, the 10,11-diol-8,9-epoxide diastereomers were 20 to 80 times more mutagenic than their 3,4-diol-1,2-epoxide counterparts. Quantum mechanical calculations of the predicted ease of benzylic carbocation formation at C-1 and C-8 from the diol epoxides indicate that the 3,4-diol-1,2-epoxides should be less reactive due to resonance destabilization of the C-1 carbocation as a result of the electronegative nitrogen atom. Decreased chemical reactivity of 3,4-diol-1,2-epoxides may explain their decreased mutagenic activity.

Acridines↗
PubMed1989

The amino acid sequence of the sex steroid-binding protein of rabbit serum.

The amino acid sequence of the sex steroid-binding protein (SBP or SHBG) of rabbit serum, specific for binding testosterone and 5 alpha-dihydrotestosterone, was determined using a complementary combination of mass spectrometric and Edman degradation techniques. The monomeric unit of the homodimeric protein is a single chain glycopeptide of 367 amino acid residues, with N-linked oligosaccharide side chains at Asn-345 and Asn-361 and disulfide bonds connecting Cys-158 to Cys-182 and Cys-327 to Cys-355. The polypeptide molecular weight of the monomer calculated from the sequence is 39,769. The molecular weight of the homodimer including 9% carbohydrate is 87,404. The sequence contains a relatively hydrophobic segment between Trp-241 and Leu-282, which includes many leucine residues in an alternating pattern. An amino acid sequence repeat is also located within that segment. Both of these patterns are present in human SBP and in the androgen-binding protein of rat epididymis. The sequence data indicate that the previously reported microheterogeneity of rabbit SBP in sodium dodecyl sulfate-polyacrylamide gel electrophoresis reflects variants generated by differential glycosylation of the monomer rather than different gene products. Seventy-nine percent of the amino acids of rabbit SBP are identical to those of human SBP; rabbit SBP thus joins human SBP and rat androgen-binding protein in one gene family that is distinct from the steroid hormone receptor superfamily. It appears that the problem of binding sex steroid hormones has been solved independently in two different gene families that contain completely different steroid-binding domains. Since the nonhomologous steroid-binding domains of both families of proteins recognize essentially the same steroid structure, it will be interesting to determine the structural basis of the two different protein designs that lead to similar steroid-binding specificity.

Amino Acid Sequence↗