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Biomedical subjects

R Kumar

Publications and source records attributed to R Kumar.

At least 1,765 records · Page 98Linked to original sources
PubMedDate not supplied

Alveolar stability of altitude raised rats.

On the lining of alveolar membrane of the lung presence of surfactant, a surface tension lowering agent which is a phospholipid in nature, is well established. A good correlation exists between pulmonary lecithin, the principle constituent of surfactant system and alveolar stability. The production of surface active material in the type II cells is oxygen dependent and is affected by hypoxia. The chemical and physical nature of the surfactant in the lungs of the rats raised at high altitude has been studied in comparison with that of sea level control. Eighteen male adult rats raised at high altitude (3520 m) were used. Phospholipids (Phosphatidyl Choline, Phosphatidyl ethanolamine, Lysophosphatidyl choline, Lysophosphatidyl ethanolamine and Sphingomyelin) were estimated by thin layer chromatography, stability index by Pattle's bubble technique and dynamic surface tension have also been studied to assess the surfactant activity of the lung. The results indicate that there was a decrease in lung surfactant as measured by chemical analysis. However, stability ratio measurements showed that there was very little change in the stability ratio (Sr) as the value of both groups lay in the normal range namely 0.6 to 0.9 hence the lungs of high altitude raised rats had normal alveolar stability. Surface tension values of alveolar lavage in altitude raised animals were also similar to those of normal rats. It is concluded that the rats raised at altitude show a lowering of surfactant as estimated chemically but the stability ratio is not significantly altered to indicate alveolar instability. In the altitude rats lesser quantum of surfactant is adequate to maintain alveolar stability.

Altitude↗
PubMedDate not supplied

Influence of thyroid hormone on the phospholipid composition of lung tissue and surfactant of rats.

Thyroid hormone is an important regulator of lipid metabolism in vivo. The effect of thyroid hormone on the phospholipid composition of lung tissue and surfactant has been studied in hypothyroid and hyperthyroid rats in comparison with the control rats. Rats were made hyperthyroid by administering 1 mg of L-thyroxine/kg body weight for six days. Another group of rats was rendered hypothyroid by injecting 1 mci of Na I131 to each rat. Phosphatidyl choline, lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl ethanolamine, and sphingomyclin, were estimated by thin layer chromatography. A decrease in phospholipids in hypothyroid and an increase in the hyperthyroid rats was observed. This can be attributed to the altered thyroid activity.

Animals↗
PubMedDate not supplied

Treatment of fracture of the femur in children by a "cast-brace".

To investigate the suitability of the cast-braces for the management of fractured femurs in children, the author studied 50 children treated for fractured femurs. After conventional skin traction therapy for three weeks, 40 children are placed in cast-braces and ten in conventional hip-spicas. The results are compared. The advantages noted with the cast-brace are that it reduces stress at the fracture site, allows knee and hip movement and ambulation thus reducing the period of immobilization and the functional loss.

Adolescent↗
PubMedDate not supplied

Immunoregulatory role of stress mediators in rheumatoid arthritis.

Eighteen patients suffering from chronic rheumatoid arthritis were selected for the present study. Plasma levels of stress hormones like catecholamines and cortisol were found to be elevated. At the same time reduction in percentage of E-rosette forming lymphocytes and an elevation in levels of major serum immunoglobulins (IgG, IgA and IgM) were observed. Certain other alterations in serum protein fractions were also noted. Probable role of these factors in the pathogenesis of this disease is discussed and attempts have been made to inter relate these findings.

Adult↗
PubMedDate not supplied

Growth inhibition of human acute promyelocytic leukemia NB-4 cells by interferons and all-trans retinoic acid: trans-modulation of inducible gene expression pathways.

Regulation of cell proliferation appears to be a complex process involving the regulated expression and/or interaction of gene regulatory pathways stimulated by binding of specific growth regulators such as inteferons (IFN) and all-trans retinoic acid (RA) to their respective receptors. We investigated the growth regulation of human acute promyelocytic leukemia NB-4 cells by combinations of IFNs and RA, and explored the possible biochemical interactions between IFNs and RA by studying the regulation of expression of IFN- and RA-inducible cellular pathways by RA and IFN respectively. We observed that combinations of IFNs and RA inhibited NB-4 cell growth significantly more than either agent alone. Analysis of cellular inducible pathways demonstrated that RA augmented levels of gene expression: (i) induced by IFN-alpha such as 2'-5'-oligoadenylate synthetase, mRNA 561 and mRNA 6-16; (ii) induced by IFN-gamma such as 2A and P56; and (iii) induced by both IFN-alpha and IFN-gamma such as mRNA 1-8. Furthermore, IFNs also augmented the expression of RAR-alpha mRNA and RAR-alpha. Co-treatment of NB-4 cells by IFN-gamma plus RA induced a sub-set of IFN-induced genes which were not induced by either IFN-gamma or RA alone. These results suggest that gene inducing interactions, the transregulation of IFN-inducible and RA-inducible gene expression pathways by RA and IFNs, respectively, may be closely related to the potentiation of growth inhibition of NB-4 cells by combinations of IFNs and RA. These findings may be useful in establishing a rationale for using IFNs and RA or combinations of IFNs and RA in the treatment of acute promyelocytic leukemia.

2',5'-Oligoadenylate Synthetase↗
PubMedDate not supplied

Beneficial effects of long-term metoprolol therapy on cardiac haemodynamics in patients with mitral stenosis in sinus rhythm--a randomised clinical trial.

We conducted a placebo controlled randomised clinical trial to evaluate the effects of 6 months therapy with metoprolol on resting and exercise haemodynamics in 31 patients with isolated mitral stenosis in sinus rhythm. Twenty six of them (placebo n = 13, metoprolol n = 13) completed the study protocol. Their mean age was 23.1 +/- 7.9 years and the mean mitral valve area was 0.93 +/- 0.25 cm2. The dose of metoprolol ranged between 50-100 mg per day. The primary outcome variables for the study were the resting and exercise mean pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) and the secondary outcome variables consisted of resting and exercise heart rate, mean pulmonary artery pressure (PAP), mean pulmonary vascular resistance (PVR) and clinical improvement on visual analog scale. These outcome variables were assessed blindly. The resting and exercise mean PCWP (mmHg) increased by 9.1 +/- 3.1 and 16.4 +/- 6.4 on placebo and 2.5 +/- 2.1 and -4.6 +/- 2.3 on metoprolol after 6 months therapy. These differences were statistically significant (p < 0.01). The resting and exercise CI (liters/min/m2) decreased by 0.2 +/- 0.1 and 0.1 +/- 0.1 on placebo and 0.3 +/- 0.5 and 0.3 +/- 1.0 on metoprolol. These haemodynamic effects were accompanied with much better symptomatic improvement in patients treated with metoprolol. The differences in change in mean PAP and PVR in two groups were statistically not significant. Our results suggest that the symptomatic patients with MS, waiting for definitive intervention for 6 months or less, would benefit if given beta blockers during this period.

Adult↗
PubMedDate not supplied

Reduced expression of c-erbB2 gene product in human mammary carcinoma SK-BR-3 cells treated with interferon-gamma and tumor necrosis factor-alpha.

Abnormalities in the expression, structure, or activity of proto-oncogene products have been implicated in the development and maintenance of the malignant cells. Proto-oncogene c-erbB2/HER2 gene product P185HER2 is one such regulatory cellular protein, elevated expression of which can result in transformed phenotypes of mouse fibroblast NIH3T3 cells, and has been also shown to be overexpressed in a number of human tumors including breast carcinoma. In the studies presented here, we have investigated the effects of antiproliferative cytokines such as interferons (INFs) and tumor necrosis factor-alpha (TNF-alpha) on the modulation of expression of P185HER2 and growth-rate of human mammary carcinoma SK-BR-3 cells which overexpress P185HER2. It was observed that the antiproliferative effects of IFN-gamma and TNF-alpha on the cultures of SK-BR-3 cells were associated with reduction in the steady-state levels of P185HER2 with no change in the steady state levels of expression of c-erbB2 mRNA. Treatment of SK-BR-3 cells with either IFN-gamma or TNF-alpha was accompanied by inhibition of rate of synthesis of the protein, enhanced turnover of newly synthesized P185HER2, and reduced expression of P185HER2 on the cell surface. These observed effects on the expression of P185HER2 were more pronounced by more growth inhibitory TNF-alpha than IFN-gamma. These observations suggest that the growth regulation of SK-BR-3 cells by IFN-gamma and TNF-alpha may be associated with reduced expression P185HER2.

Breast Neoplasms↗
PubMedDate not supplied

Meta-analysis.

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Meta-Analysis as Topic↗
PubMedDate not supplied

Etiology of isolated mitral regurgitation: a clinico-echocardiographic study.

One hundred and ninety two consecutive patients with isolated mitral regurgitation (MR) with an audible murmur were studied for determination of etiology. There were 95 males & 97 females (mean age 24.5 +/- 10.8 years; range 13 to 58 years) with 102 patients in NYHA classes I and II, 81 in class III and 9 in NYHA class IV. The etiological grouping was: rheumatic 74 (38.5%), probable rheumatic 28 (15%), mitral valve prolapse 26 (13.5%), dilated cardiomyopathy 15 (8%), infective endocarditis 12 (6%), isochaemic heart disease 10 (5%), miscellaneous group (including rupture chordae tendinae, aortoarteritis etc) 9 (4.5%) and patients with indeterminate etiology 18 (9.5%). Etiology could be determined in 174 out of 192 cases. The clinical methods combined with echocardiography were helpful in 79 cases while echocardiography alone could diagnose etiology in 89 cases. Clinical features alone gave the diagnosis in 6 patients. The findings of gross morphology of the surgically removed mitral valves in 30 patients of this study were similar to their pre-operative etiologic diagnosis based on clinical and echocardiographic features. These findings may be of value in planning treatment and prophylactic strategies in cases of isolated MR.

Adolescent↗