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Biomedical subjects

S Chauhan

Publications and source records attributed to S Chauhan.

At least 73 records · Page 4Linked to original sources
PubMed1993

Bradyrhizobium japonicum delta-aminolevulinic acid dehydratase is essential for symbiosis with soybean and contains a novel metal-binding domain.

The Bradyrhizobium japonicum hemA gene product delta-aminolevulinic acid (ALA) synthase is not required for symbiosis of that bacterium with soybean. Hence, the essentiality of the subsequent heme synthesis enzyme, ALA dehydratase, was examined. The B. japonicum ALA dehydratase gene, termed hemB, was isolated and identified on the basis of its ability to confer hemin prototrophy and enzyme activity on an Escherichia coli hemB mutant, and it encoded a protein that was highly homologous to ALA dehydratases from diverse organisms. A novel metal-binding domain in the B. japonicum ALA dehydratase was identified that is a structural composite of the Mg(2+)-binding domain found in plant ALA dehydratases and the Zn(2+)-binding region of nonplant ALA dehydratases. Enzyme activity in dialyzed extracts of cells that overexpressed the hemB gene was reconstituted by the addition of Mg2+ but not by addition of Zn2+, indicating that the B. japonicum ALA dehydratase is similar to the plant enzymes with respect to its metal requirement. Unlike the B. japonicum hemA mutant, the hemB mutant strain KP32 elicited undeveloped nodules on soybean, indicated by the lack of nitrogen fixation activity and plant hemoglobin. We conclude that the hemB gene is required for nodule development and propose that B. japonicum ALA dehydratase is the first essential bacterial enzyme for B. japonicum heme synthesis in soybean root nodules. In addition, we postulate that ALA is the only heme intermediate that can be translocated from the plant to the endosymbiont to support bacterial heme synthesis in nodules.

Amino Acid Sequence↗
PubMed1991

Primary tumors of small bones: a clinicopathological and radiological study.

Primary small bone tumors are rare. Most of them have been reported as solitary case reports in the literature. In this retrospective study of small bone tumors over the period of five years, the commonest tumor encountered was enchondroma. Next in frequency were exostosis, giant cell tumor, benign chondroblastoma. Solitary cases of benign osteoblastoma, mesenchymal chondrosarcoma and glomus tumors were encountered. All these cases were analysed clinically, radiologically and correlated with histopathology in each case.

Adolescent↗
PubMed1990

Clinical and roentgenological profiles and etiological correlations of encysted pleural effusions.

One hundred and thirty-six cases of encysted pleural effusions were studied and investigated to reach an etiological diagnosis. The clinical profile of encysted pleural effusions differed little from that of free pleural effusions. Of the four sites of encystments seen (costoparietal, interlobar, subpulmonic, and mediastinal), costoparietal effusions were the commonest and resulted most often from infections. Interlobar encystments came next in frequency and most often resulted from congestive cardiac failure. Of the various causes of encysted pleural effusions, tuberculosis was the commonest, followed by pyogenic infection and congestive cardiac failure, in this order. Conventional radiographic techniques were adequate in diagnosing most cases of encysted pleural effusions.

Adolescent↗
PubMed1990

Alterations in immunoglobulin & complement levels in chronic obstructive pulmonary disease.

Thirty patients of chronic obstructive pulmonary disease (COPD; all smokers) and an equal number of controls (15 smokers) were studied. The COPD patients were further divided into group A (predominantly emphysema) and group B (predominantly bronchitis) of 15 patients each. Serum and sputum IgG, IgA and IgM and serum C3 and C4 were estimated. IgG, IgA, IgM and C3 and C4 were similar in smoker and non-smoker controls. Mean (+/- SD) serum IgG (IU/ml) was significantly higher in COPD patients (207.78 +/- 62.73) than in control (177.25 +/- 43.5; P less than 0.05), serum IgA (IU/ml) was also significantly higher in COPD (205.04 +/- 46.56) than in control (108.21 +/- 33.3; P less than 0.01). IgM was similar in the 2 groups. Sputum IgA (IU/ml) was higher in COPD (4.68 +/- 3.51) than in control (2.25 +/- 1.03; P less than 0.05). IgG and IgM were similar in the 2 groups. Both serum C3 (IU) and C4 (IU) were lower in COPD patients (C3 = 95.9 +/- 33.11, C4 = 113.6 +/- 62.4) than in control (C3 = 167.3 +/- 25.42, C4 = 205 +/- 76.5; P less than 0.05). Serum IgA in type B COPD (212.25 +/- 50.06) was higher than in type A (197.52 +/- 43.3; P less than 0.05) IgG and IgM were similar in these 2 groups. In COPD patients, immunoglobulins were either normal or higher indicating that deficiency of immunoglobulin is not a predisposing factor in development of COPD. Similar immunoglobulin values in smoker and nonsmoker controls indicated that smoking was not the cause of rise of immunoglobulins in COPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Complement C3↗
PubMed1986

Biochemical changes in rat vital organs by feeding a diet infested with Penicillium rubrum Stoll.

Weanling albino rats were fed with either a control diet or one infested with Penicillium rubrum Stoll for a period of 30 days. At the end of the experimental period, determinations of haemoglobin, total proteins and transaminases were made in blood and tissues (liver, brain and kidney). The fungus was found to render the food toxic, resulting in liver and kidney damage. The toxicity of the fungus was also evidenced by poor live weight gains and organ weights.

Administration, Oral↗
PubMed1985

Enhancement in the activities of mouse epidermal glucose-6-phosphate dehydrogenase, hexokinase, phosphofructokinase, and pyruvate kinase by 12-O-tetradecanoyl-phorbol-13-acetate.

The active ingredient in the tumor-promoting croton oil, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), was shown to increase the activity of mouse skin epidermal glucose-6-phosphate dehydrogenase (+84%), hexokinase (+100%), phosphofructokinase (+158%), and pyruvate kinase (+101%). This increase in activity of these key enzymes of glucose metabolism occurred 2-8 h after TPA application and was due to a net increase in the enzyme content. This increase in the activity of the glycolytic enzymes, as well as the reported TPA-induced increase in the synthesis of RNA and DNA and cell proliferation, suggest that activation of the glycolytic pathway may be involved in the carcinogenic effects of tumor promoters.

Animals↗
PubMed1984

Genome analysis of BK (WW) viral DNA cloned directly from human urine.

DNA from a third isolate of the WW strain of BK virus was prepared from human urine and was cloned into the BamHI site of pBR322. Restriction mapping showed a number of changes relative to the prototype BK viral DNA, including the presence of a new PstI, an SstI, and an AvaII site and the loss of a HindIII, an SstI, and an NcoI site. There is evidence for more extensive changes in the vicinity of the origin of replication.

BK Virus↗
PubMed1984

The effects of chronic administration of chlorine dioxide, chlorite and chlorate to normal healthy adult male volunteers.

The physiological impact of chronic 12 week ingestion of chlorine dioxide and its byproducts, chlorite and chlorate, was compared to the effects of chlorine, chloramine and untreated water. The water disinfectant solutions were administered daily (500 ml, 5 ppm) to normal healthy adult male volunteers. An extensive battery of tests was used to evaluate the physiological impact of the ingested water disinfectants. Upon analysis of both quantitative and qualitative parameters it was concluded that the 12 week chronic administration of chlorine dioxide and its byproducts was accompanied by no clinically important physiological effects.

Adult↗
PubMed1984

The effects of chronic administration of chlorite to glucose-6-phosphate dehydrogenase deficient healthy adult male volunteers.

Under controlled laboratory conditions, the safety of daily ingestion of 5 ppm chlorine dioxide, chlorite and chlorate by normal healthy adult males has been established. To determine the effect upon potentially susceptible individuals, a parallel chronic human investigation was undertaken. Study subjects were three healthy adult males deficient in glucose-6-phosphate dehydrogenase. These volunteers received 500 ml of sodium chlorite at a concentration of 5 ppm daily for twelve consecutive weeks; the subsequent observation period extended an additional eight weeks. Upon evaluation of an extensive battery of tests designed to measure the biochemical and physiological response to chlorite ingestion, no clinically significant changes were detected.

Adult↗
PubMed1983

'Frustration--anxiety behaviour as a function of leprosy patients age and personality'.

The paper incorporates five studies (i.e., four of frustration and one of anxiety). The design is 'Multi-group-Control-group'. Each one of the five studies has four '3 X 3 X 2' factorial experiments. Each experiment has 360 elements. These are three groups (of lepromatous, non-lepromatous and of disease-free normals). Each group consists of 120 elements (equally distributed among adolescents, adults and senescents). The particulars of the patients have been obtained from the Central JALMA Institute for Leprosy and the Kushta Seva Sadan (Agra). The disease-free normal elements are drawn freely from the population of the Agra town. The sample possesses statistical justification for size and representativeness. Data are collected with the help of reliable tools and the 'F' test is run for verification of the 'null hypotheses'. Results show that experiences of 'fixation-regression' frustration, atypically belong to normal senescence. Resignation and anxiety experiences, as growing hazards, specifically relate to leprosy patients. Personality factors that normally demote 'frustration-anxiety' behaviour exhibit 'role-negation' in the leprosy patients. Age shows 'role-reversion'. Implications of such 'role' changes relate to the 'self-eroding' process of personality in the patients.

Adolescent↗
PubMed1980

Effect of undernutrition on lipid metabolism of brain. In vivo incorporation of labelled acetate and palmitate into lipids.

Albino rats were malnourished from neonatal to weanling stage by increasing the litter size. The in vivo incorporation of (1-(14)C)-acetate, (1-(14)C)-palmitate into the lipid classes was examined in the animals. A stimulated incorporation of the label was observed in total lipids, phospholipids, cholesterol, cerebrosides and sulfatides of the brain of malnourished animals compared to controls.

Acetates↗