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Biomedical subjects

B G Devi

Publications and source records attributed to B G Devi.

6 recordsLinked to original sources
PubMed1992

Studies on urea cycle enzyme levels in the human fetal liver at different gestational ages.

Urea cycle enzymes involved in the detoxification of ammonia were studied in liver tissues of 57 male and 49 female fetuses of different age groups ranging from 13 to 36 wk of gestation. Surgical wedge biopsies of liver from 18 male and 12 female adults were used as controls. Significant enzyme activity was found to be present as early as the 13th wk of gestation. As gestational age advanced, enzyme activity gradually increased, reaching about 90% of the adult activity by the 36th wk of gestation.

Adult↗
PubMed1992

Changes in membrane fluidity during human liver development.

The physico-chemical properties of the hepatic plasma membrane during prenatal period of development and in adult human liver were studied. Fluorescence polarization studies using the lipid probe pyrene, clearly demonstrated a significant reduction in the membrane fluidity with liver maturation. Lipid analysis showed an age dependent reduction in lipid/protein ratio while there was an increase in membrane cholesterol throughout the prenatal period and in adult human liver which decreased the membrane fluidity. Hepatic plasma membrane from prenatal liver also showed a decrease in phosphatidyl choline/phosphatidyl ethanolamine ratio and an increase in sphingomyelin/phosphatidyl choline ratio. These results suggest that there is a gradual decrease in lipid content and membrane fluidity during the prenatal period of development which might regulate the differentiation of membrane associated function in human liver.

Adult↗
PubMed1992

Glycogen metabolism during human liver development.

Development of enzymes of glycogen metabolism in human fetal and neonatal liver was investigated. Glycogen was present in quantitatable amount from early gestational age onwards; however, ultrastructurally it could not be detected earlier than 20 weeks. Increase in glycogen synthetase a activity during 21-36 weeks of gestation subsequently resulted in glycogen accumulation. A rapid degradation of this glycogen storage, at birth, was accompanied by an elevation in glycogen phosphorylase a activity. The present investigation to be the first to provide a complete profile of glycogen storage and differentiation of glycogen metabolising enzymes in preparing the prenatal fetus for its independent nutritional life.

Adult↗
PubMed1989

Localization of intracellular zinc under conditions of altered permeability control of the plasma membrane.

Intracellular zinc was located as electron dense granules associated with the plasma membrane, endoplasmic reticular membranes, mitochondrial membranes, nuclear membranes and chromatin in Zajdela ascitic hepatoma and AK5 macrophage ascitic tumour cells. The quantity of intracellular zinc estimated by atomic emission spectrometer was different in the two cell lines. However, after loss of permeability control by the plasma membrane, involving glutaraldehyde and heat-shock treatments, the quantity of intracellular zinc was increased to almost the same extent in both cases.

Animals↗
PubMed1975

The purification and properties of peroxidase in Mycobacterium tuberculosis H37Rv and its possible role in the mechanism of action of isonicotinic acid hydrazide.

Peroxidase from Mycobacterium tuberculosis H37Rv was purified to homogeneity. The homogeneous protein exhibits catalase and Y (Youatt's)-enzyme activities in addition to peroxidase activity. Further confirmation that the three activities are due to a single enzyme was accomplished by other criteria, such as differential thermal inactivation, sensitivity to different inhibitors, and co-purification. The Y enzyme (peroxidase) was separated from NADase (NAD+ glycohydrolase) inhibitor by gel filtration on Sephadex G-200. The molecular weights of peroxidase and NADase inhibitor, as determined by gel filtration, are 240000 and 98000 respectively. The Y enzyme shows two Km values for both isoniazid (isonicotinic acid hydrazide) and NAD at low and high concentrations. Analysis of the data by Hill plots revealed that the enzyme has one binding site at lower substrate concentrations and more than one at higher substrate concentration. The enzyme contains 6g-atoms of iron/mol. Highly purified preparations of peroxidases from different sources catalyse the Y-enzyme reaction, suggesting that the nature of the reaction may be a peroxidatic oxidation of isoniazid. Moreover, the Y-enzyme reaction is enhanced by O2. Isoniazid-resistant mutants do not exhibit Y-enzyme, peroxidase or catalase activities, and do not take up isoniazid. The Y-enzyme reaction is therefore implicated in the uptake of the drug.

Catalase↗