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Biomedical subjects

S C Jain

Publications and source records attributed to S C Jain.

At least 91 records · Page 5Linked to original sources
PubMed1980

Body fluid compartments in humans during acute high-altitude exposure.

Body fluid compartments were studied in a group of sea level residents at sea level and during 12 d of acute exposure to an altitude to 3,500 m. Measurements of total body water and extracellular water were done on the third and 12th days of exposure, while plasma volume was measured on 12th day only. The intracellular water, blood volume, and red cell mass were computed from the above parameters. Total body water and extracellular water decreased progressively, the decrease being 4.7% (p less than 0.001) and 6.0% (p less than 0.05) respectively on the 12th day. Plasma volume and blood volume decreased significantly with a slight increase in red cell mass. Intracellular water, computed from total body water and extracellular water, decreased by 4.3% on 12th day. This study suggested hypohydration on acute altitude exposures.

Adult↗
PubMed1978

Conformational flexibility in DNA structure and its implications in understanding the organization of DNA in chromatin.

X-ray crystallographic studies of drug-nucleic acid crystalline complexes have suggested that DNA first bends or 'kinks' before accepting an intercalative drug or dye. This flexibility in DNA structure is made possible by altering the normal C2' endo deoxyribose sugar puckering in B DNA to a mixed sugar puckering pattern of the type C3' endo (3'-5') C2' endo and partially unstacking base pairs. A kinking scheme such as this would require minimal sterochemical rearrangement and would also involve small energies. This has prompted us to ask more generally if a conformational change such as this could be used by proteins in their interactions with DNA. Here we describe an interesting superhelical DNA structure formed by kinking DNA every ten base pairs. This structure may be used in the organization of DNA within the nucleosome structure in chromatin.

Base Sequence↗
PubMed1978

Body fluid compartments in rabbits on exposure to acute hypobaric hypoxia.

Body fluid compartments were studied in rabbits divided into three groups--control, exposed to acute hypoxia, and exposed to hypoxia after treatment with 2 mg frusemide intramuscularly. Total body water, extracellular body water, and plasma space were determined using the triple radiotracer technique. Total body water decreased insignificantly with no change in extracellular body space on exposure to hypoxia. Plasma volume and blood volume showed a significant decrease with a significant increase in haematocrit. In rabbits pretreated with frusemide, total body water, extracellular body water, plasma volume, blood volume, and interstitial fluid space decreased significantly on hypoxic exposure. This study suggested hypohydration on acute hypoxic exposure with a loss of intracellular water, while pretreatment with frusemide resulted in further hypohydration with a loss from both intracellular and extracellular compartments. The results have been discussed in relation to suggested use of diuretics on induction to high altitude.

Altitude Sickness↗
PubMed1978

Haematologic changes in rabbits during acclimatisation, deacclimatisation, and reinduction to hypoxia.

Haematologic changes were studied in 16 albino rabbits during acclimatisation, deacclimatisation, and reinduction to hypobaric hypoxia. Of these, four animals died during reinduction. Haemoglobin, haematocrit, and red blood cell count attained maximum values by the 15th day during acclimatisation and by the 10th day during reinduction. Reticulocyte count reached maximum level by the fifth day, both during acclimatisation and reinduction. All these parameters returned to initial control levels by the 10th day of deacclimatisation. The erythrocytes became macrocytic during acclimatisation and remained so during deacclimatisation and reinduction. Blood volume increased on acclimatisation, returned to control values during deacclimatisation, and remained low at this level on reinduction. Red cell mass increased both during acclimatisation and reinduction and returned to control levels on deacclimatisation. Plasma volume did not change on acclimatisation and deacclimatisation, but was reduced on reinduction. The erythrocyte life span and erythrocyte glutamic oxaloacetic transaminase (EGOT) decreased during acclimatisation and reinduction. There was no change in RBC osmotic fragility, indicating no change in the integrity of the red cell wall. The deaths during reinduction were possibly due to haemoconcentration and increased blood viscosity as a result of reduction in plasma volume. It has been concluded that reinduction to hypoxia after a phase of deacclimatisation imposes a more severe stress than experienced during acclimatisation.

Acclimatization↗