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Biomedical subjects

A Mookerjee

Publications and source records attributed to A Mookerjee.

32 records · Page 2Linked to original sources
PubMed1981

Dependence of gamma-irradiated Y-peak and melting of DNA on concentration and ionic environment.

Y-peak is found to be a function of ionic strength and concentrations of DNA. The Y-peak reveals close dynamic interaction between DNA and solvent system. Electronic transitions responsible for Y-peak are not the same transitions that are responsible for X-peak. Y-peak's electronic transitions are indicative of charge transfer complex formation between DNA and solvent system. gamma-Irradiation induces hyperchromicity due to strand separation at lower doses. A-T base pairs are first to undergo coiled state as shown by delta Tm spread. Strand chopping and saturation of double bonds of the exposed bases by free radicals (H degrees and OH degrees) give rise to hypochromic regions at X-peak. Rise in ionic strength and the concentration of DNA has protective effect against gamma-damage. Y-peak is found to be a function of solvent, whereas, X-peak is independent of solvent nature.

Animals↗
PubMed1981

Effect of gamma irradiation on dye-DNH binding.

This paper attempts to analyse the effect of (a) gamma radiation and (b) the presence of histones in the form of nucleohistones (DNH) on the modes of ligand (Proflavine, Pf) binding to DNH. Effects were investigated by spectrophotometry. A certain dose of radiation which causes appreciable DNA denaturation has much less effect on DNH. There is a 'threshold' dose beyond which DNH denaturation is directly proportional to dose as in the case of DNA. The histones in DNH act as a shield and at higher doses get dissociated to expose the double helix to radiations. Ligand binding has a further stabilizing effect against radiation damage to DNH.

Cobalt Radioisotopes↗
PubMed1980

Acute hemodynamic alterations after mitral valve replacement with the glutaraldehyde-treated porcine heterograft prosthesis.

Perioperative hemodynamic changes following mitral valve replacement using the porcine heterograft prosthesis were measured in 21 patients with acquired mitral valve disease. Preoperatively, a state of compensatory cardiac failure was suggested by the following: an increased heart rate (HR) (96 beats per minute); low cardiac and stroke volume (SVI) indices (2.3 +/- 0.10 L/min/m2 and 25 +/- 2 ml/beat/m2); and increased systemic vascular resistance (SVR) (1,626 +/- 116 DYNE SEC CM-5). Bothe the mean pulmonary artery PAP) and pulmonary capillary wedge pressures (PCWP) were elevated as well (32 +/- 3 and 22 +/- 2 torr). Immediate hemodynamic improvement followed valve replacement. HR, SVR, PAP, and PCWP all decreased significantly. Twenty-four hours after valve replacement, PAP (23 +/- 1 torr) and PCWP (13 +/- 1 torr) demonstrated marked declines, SVR was reduced by one-third (1,173 +/- 87 dyne sec cm-5), HR had decreased by 10 beats per minute, and SVI had increased to 30 +/- 2 ml/beat/m2. The prompt circulatory improvement of patients soon after mitral valve replacement using the porcine heterograft compares favorably with studies in which other valve types were employed and in which postoperative cardiovascular depression was encountered frequently.

Adult↗
PubMed1977

Acute hemodynamic alterations after aortic valve replacement with the glutaraldehyde-treated porcine heterograft prosthesis.

Twenty-two patients underwent aortic valve replacement for acquired valvular heart disease with the porcine heterograft prosthesis. In the immediate postoperative period, a transient decrease in the cardiac index (CI) (preoperative 3.0 +/- 0.14 to 2.45 +/- 0.16 L. per minute per square meter, p less than 0.05) and an increase in the systemic vascular resistance (SVR) (preoperative 1,078 +/- 62 to 1,287 +/- 103) dynes/sec./cm.-5, p greater 0.05) were seen; these values returned to preoperative levels by the first postoperative day. After valve replacement, an elevation in the heart rate (HR) (preoperative 75 +/- 2 to 87 +/- 4 beats per minute, p less than 0.05) and a reduction in the stroke volume (SV) and stroke work index (SWI) (preoperative 35 +/- 2 to 26 +/- 2 Gm.-M. per square meter, p less than 0.05) occurred which persisted throughout the study. The endocardial viability ration (EVR) increased after valve replacement. These findings suggest that, following aortic valve replacement, (1) an increase HR is the mechanism utilized to maintain cardiac output, (2) subendocardial perfusion is enhanced as indicated by an increase in the EVR, and (3) the hemodynamic alterations following insertion of the porcine heterograft prosthesis are not different from those observed when other valves are placed in similar patient populations.

Adult↗
PubMed1976

Effect of gamma-irradiation on dye-DNA binding.

The effect of gamma-rays on the binding of proflavine and acridine orange to DNA was investigated by spectrophotometry. The effect of irradiation was observed on the buffered solutions of the free dye and free DNA. A dose of about 35 krad caused a hyperchromicity of 30-40 per cent to the DNA peak at 258 nm, while the same dose introduced a hypochromic effect to the monomer peaks of the dyes by 30 per cent. This implied that gamma-rays have an effect of decreasing the monomer concentration of free-day molecules in solution. From the results, we conclude that more dye is bound to the changed conformation of dye-bound DNA on irradiation. Scratchard-binding isotherms drawn for the unirradiated and irradiated complexes of Pf-DNA showed interesting differences. Similar isotherms could not be obtained for the acridine orange-DNA system.

Acridines↗