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Biomedical subjects

V R Nair

Publications and source records attributed to V R Nair.

14 recordsLinked to original sources
PubMed1993

Reduction of UV-induced mitotic delay by caffeine in BUdR-substituted plasmodia of Physarum polycephalum.

Chromosomal DNA of the synchronously mitotic plasmodia of P. polycephalum was substituted with 5-bromo-2'-deoxyuridine, by growing the plasmodia during S phase, on a medium containing this nucleoside analog. A strong synergism was observed between bromodeoxyuridine and UV-irradiation, in late G2-irradiated plasmodia in that, the mitotic delay obtained in them was much more than a simple sum of the delays induced by these two agents individually. It was also observed that the mitotic delay in this system is reduced significantly by different concentrations of caffeine applied immediately after irradiation and there was a stage specificity in this effect. The reduction in mitotic delay was maximum (80%) in those plasmodia irradiated 20-30 min before control metaphase, when mitogenic factors also reach their maximum activity in this system. It is proposed that the mitotic delay reducing effect of caffeine is due to its ability to promote the activity of the mitogenic factors, largely independent of the system which is responsible for monitoring the state of the chromosomal DNA.

Animals↗
PubMed1991

Differential effect of cordycepin on S and G2 phases of cell cycle in plasmodia of Physarum polycephalum Schw.

Effect of pulse treatments of cordycepin, an analog of adenosine, on S and G2 phases of the cell cycle of the mitotically synchronous plasmodia of Physarum polycephalum has been studied. Various concentrations of the drug (50-200 micrograms ml-1) were found to be effective in delaying mitosis by several hours in both the phases. However, there was a significant increase in mitotic delay in those treated during G2. It is suggested that this extra delay during G2 could be due to the transcriptive level inhibition of specific RNA types, such as that of tubulins, whose gene activity is cell cycle regulated and turned on during G2 in Physarum, or alternatively because of a deficiency for ATP and the consequent inhibition of events such as mitotic spindle assembly and phosphorylation of histones.

Animals↗
PubMed1990

Effects of microgravity on microcirculation.

The blood behaviour in human circulatory system observed during space flights reveals that the microgravity environment reduces the flow rate and increases the haematocrit compared with the situation on the earth surface. The present study gives a theoretical analysis of the above phenomena by considering a two layer Newtonian model for blood flow in capillaries. The effect of gravity on plasma layer as well as on the blood viscosity is taken into account for calculating the percentage change in flow rate of blood. The corresponding apparent viscosities on the earth surface and in space are estimated. The results are analyzed and presented graphically. The findings agree reasonably well with the data observed in spaceflight experiments.

Aerospace Medicine↗
PubMed1984

Mitotic delays and macromolecular synthesis in G2 phase-irradiated plasmodia of Physarum polycephalum.

Mitotically synchronous surface plasmodia of Physarum polycephalum were irradiated at different times of G2 phase with doses of UV ranging from 350 to 2800 Jm-2. The UV sensitivity, measured in terms of delay in progression towards mitosis, gradually declined through G2 phase to almost zero in early prophase, when irradiated with 350 Jm-2 of UV. However, with higher doses, 700 and 1400 Jm-2, late G2 was found to be even more susceptible than early G2. The delay in these cases rises for the last 0.1 part of the cycle up to a UV-transition point in early prophase. Thus, processes which were not sensitive to a lower dose of UV are affected by higher doses. Above 700 Jm-2, delay was not directly proportional to dose. With doses above 1400 Jm-2, the delays obtained were more variable, although some tendency for an increased delay is observed in plasmodia irradiated in late G2 when compared with those irradiated in middle G2. The least UV-sensitive phase is between -0.2 and -0.4 part of the cycle in relation to mitosis (0 point). Both RNA synthesis and protein synthesis are inhibited in plasmodia irradiated at any time during G2 phase with 1400 Jm-2 of UV. However, on an average, irradiation in late G2 caused the most inhibitions.

Fungal Proteins↗
PubMed1976

Vasoplasty: a new technique.

A technique by which plain catgut is used as an internal splint in vasoplasty is described. 28 cases have been carried out, of which only 4 have failed.

Adult↗
PubMedDate not supplied

Experience with anal stretch in treatment of piles.

Fifty patients in two groups of twenty-five were treated with anal stretch and standard haemorrhoidectomy operation. Thy were followed up for six months. Anal stretch patients had less pain and post operative stay in hospital was minimal (3 days). They also returned to work much earlier. No complications occured in either group. It is felt that the anal stretch method is the preferable of the two.

Adult↗
PubMedDate not supplied

Seroprevalence of rubella and cytomegalovirus (CMV) infection in pregnant women from Kerala State.

Prevalence of rubella antibody in 536 and cytomegalovirus (CMV) antibody in 260 pregnant women attending an antenatal clinic, in India, was studied by means of hemagglutination inhibition (HAI) test (for rubella antibody) and complement fixation test (CFT-for CMV antibody). The antibody detection rate in pregnant women was 74.1% for rubella and 85.4% for CMV. The prevalence rate of CMV infection was higher during third trimester (89.6%), while rubella antibody was more prevalent during second trimester (77.5%). The geometrical mean titre (GMT) was 73 for rubella antibody and 57 for CMV. Further, rubella antibody was found to be more prevalent in the age group of 26-30 years (76.8%), while for CMV, the highest prevalence rate was seen in 21-25 years (89.2%). The present study indicates the potential possibility of primary rubella infection in 26.0% and CMV infection in 15.0% of the susceptible women during pregnancy and the development of congenital malformations in children born to the infected women.

Age Factors↗