Jacob Eapen

Differences in lipid peroxidation of rat liver rough and smooth microsomes.

The rough and smooth microsomes of rat liver show significant differences in lipid peroxidation induced by both NADPH and ascorbate. The parameters studied include kinetics, response towards cofactors and sensitivity to inhibitors. Smooth microsomes are more prone to lipid peroxidation with increasing concentrations of NADPH, Fe3+, ascorbate and Fe2+, and are more susceptible to inhibitors than rough microsomes. Smooth microsomes also contain higher amounts of ascorbic acid, NADPH cytochrome c reductase and total lipids, besides possessing a higher degree of unsaturation in lipids, all of which promote lipid peroxidation. Our results suggest that, although smooth microsomes are more sensitive to lipid peroxidation, they are compensated for by being more sensitive to inhibitors of lipid peroxidation.

The metabolic fate of [35S]-diallyl disulphide in mice

Diallyl disulphide (DADS) is a major constituent of garlic oil. Uptake of [35S]-labelled diallyl disulphide by mouse liver is highest at 90 min after treatment. 2h after treatment with [35S]-DADS, 70% of the radioactivity is present in the liver cytosol of which 80% is metabolized to sulphate.

Changes in enzymes of hepatic rough and smooth microsomes during postnatal development and ageing of rats

Significant changes are observed in wet weight, microsomal protein content and enzymes of purified rough and smooth microsomes of liver during postnatal development and ageing of female Wistar rats. Protein content of total microsomes increases up to 15 days of age and remains steady during subsequent development, unlike that of rough and smooth microsomes which shows changes throughout the same period. Activities of cytochrome P-450, cytochrome b5 and NADPH-cytochrome c reductase increase during the period of maturation and decline during senescence. The decrease during senescence is at different rates in the two microsomal fractions. Microsomal glucose-6-phosphatase, but not adenosine triphosphatase, shows a similar increase during development and decrease during senescence.

Mode of action of garlic oil—Effect on oxidative phosphorylation in hepatic mitochondria of mice

Abstract The effect of garlic oil on oxidativc phosphorylation in liver mitochondria of mice has been studied. Garlic oil impairs oxidative phosphorylation in hepatic mitochondria. The coupling activity of sites 1. 2 and 3 appears to be affected by garlic oil. The extent to which respiration is affected varies with the substrates used. For example, garlic oil affects respiration during oxidation of NAD-lmkcd substrates such as glutamate to a greater extent than during oxidation of succinate and ascorbate. The inhibitory effect on respiration is less than that on phosphorylation. Diallyl disulfide, the principal insecticidal component of garlic oil, has a similar inhibitory effect on the mitochondrial oxidative phosphorylation. In contrast, dipropyl disulfide. which is chemically comparable to diallyl disulfide but is devoid of insecticidal activity, has a substantially lesser effect on oxidative phosphorylation.

Studies on Lipids of Brain, Kidneys and Liver of Mice during Postnatal Development

The postnatal changes in distribution and synthesis of lipids of mice liver, kidneys and brain have been studied. The hepatic lipids show greater variation in females than in males during postnatal de

Induction of rat liver microsomal enzymes by cycloheximide

Abstract Administration of cycloheximide into rats induced certain enzymes of rough and smooth microsomes. NADPH cytochrome c reductase of smooth microsomes and glucose-6-phosphatase of rough and smooth microsomes attained peak activities 2 hr after cycloheximide treatment. Cytochrome P-450 and cytochrome b 5 of the rough microsomes were highest 6 hr after the antibiotic injection. On the other hand, cycloheximide reduced ATPase activity in the smooth microsomes. All the components studied except NADPH cytochrome c reductase of the smooth microsomes approached control values 24 hr after the treatment. The responses of rough and smooth microsomes toward cycloheximide were different.

Effect of garlic oil on incorporation of amino acids into proteins of Culex pipiens quinquefasciatus say larvae

Abstract Incorporation of [ 14 C]leucine into proteins of 3rd instar Culex pipiens quinquefasciatus Say larvae increases linearly with time between 1 and 4 h. Garlic oil as well as the active larvacidal principle from it, viz. diallyl disulphide, inhibits significantly synthesis of the larval proteins. The maximum reduction in incorporation is observed during the first hour of treatment. The incorporation of [ 14 C]phenylalanine is also inhibited by garlic oil and the effect is irreversible. Garlic oil does not seem to have any effect on proteins already labelled and it does not suppress substantially oxygen uptake by the larvae.

Enhanced gamma glutamyl transpeptidase activity in rat uterus following deciduoma induction and implantation

Abstract Gamma glutamyl transpeptidase (GGT) is significantly enhanced in the rat uterus following implantation and during deciduoma morphogenesis. Uteri of gravid rats (Day 7 and 8 of pregnancy) show higher levels of this enzyme in the regions of implantation than in the interimplantation areas. Most of the GGT activity of induced deciduoma is present in the endometrium and the enzyme activity increases gradually to reach a peak five days post induction. Myometrial GGT activity is barely detectable during deciduoma growth. Results are discussed in relation to endometrial alterations during nidation and uterine glutathione content.

Protein synthesis by rat cardiac muscle myofibkils

Abstract The present study is an attempt to elucidate the role of cardiac muscle myofibrils in protein synthesis. Pulse labelling in vivo shows that the fraction containing myofibrils is a major site of amino acid incorporation into protein. Myofibrils and myofibrillar ribosomes incorporate labelled amino acids into protein when incubated in a conventional medium used to demonstrate cell-free protein synthesis. Evidences are presented to establish that the protein synthesis is genuine. Ribosomes derived from myofibrils show a nearly 4-fold increase in specific activity in comparison with myofibrils. Neither cycloheximide nor chloramphenicol inhibits in vitro amino acid incorporation by myofibrils or by ribosomes derived from them. In contrast, in vivo amino acid incorporation into protein of cardiac muscle and its subcellular fractions is nearly completely inhibited by cycloheximide. Amino acid incorporation by isolated myofibrils and by myofibrillar ribosomes is not inhibited by ribonuclease. The in vitro amino acid incorporation by myofibrils does not appear to depend on factors present in the cell sap. The results suggest extensive and independent protein synthesis by myofibrils, with myofibrillar ribosomes as the functional units.

In vivo studies on the effect of garlic oil in mice

Abstract The in vivo effect of garlic oil on protein, glycogen and lipid metabolism as well as on oxidative phosphorylation has been studied in liver and kidneys of mice. The incorporation of [ 14 C] leucine into proteins of the liver is virtually unchanged by treatment with garlic oil whereas the labelling of proteins of the kidneys is reduced. Garlic oil enhances the incorporation of [ 14 C] glucose into hepatic glycogen, produces a temporary rise in blood glucose levels and depletes liver glycogen. Renal glycogen levels and incorporation of [ 14 C] glucose into renal glycogen remain unchanged following garlic oil treatment. The compound has little or no effect on the incorporation of [ 14 C] acetate into hepatic and renal lipids. Garlic oil impairs partially the oxidative phosphorylation associated with the oxidation of ascorbate in hepatic mitochondria without affecting noticeably the P/O ratio during the oxidation of glutamate and succinate.