Dexamethasone increases neutral sphingomyelinase activity and sphingosine levels in 3T3-L1 fibroblasts.

The activity of neutral sphingomyelinase (EC 3.1.4.12) in a plasma membrane enriched fraction was found to be increased in dexamethasone treated cells. The elevation of sphingomyelinase activity was blocked by cycloheximide indicating that protein synthesis was required for the steroid action. Ceramidase (EC3.5.1.23) activity was unaffected by the dexamethasone treatment. Levels of sphingosine in 3T3-L1 Cells were also increased after treatment with 10(-7) M dexamethasone for 2 and 4 hours.

RASARATNA SAMUCHAYA: "Indian Alchemy".

This article deals with the history of Indian Alchemy and surveys its gradual and fertile growth in ancient India.

Differential regulation of the synthesis of mannosylphosphoryl derivatives of dolichol and retinol in HeLa cells.

We have shown earlier that in HeLa S3G cells, glucocorticoids stimulate the synthesis of dolichyl phosphorylmannose (Dol-P-Man) with a concomitant increase in the glycosylation of proteins (Ramachandran, C.K., Gray, S.L. and Melnykovych G. (1982) Biochem. J. 208, 47-52). Although controversial, there have been several lines of evidence suggesting that the synthesis of retinyl phosphorylmannose (Ret-P-Man) and Dol-P-Man may be carried out by the same enzyme. We examined this possibility and conclude that in HeLa S3G cells the syntheses of Dol-P-Man and Ret-P-Man are catalyzed by two different enzymes located in the same microenvironment. Our conclusion is based on the following observations: exogenously added dolichyl phosphate and retinyl phosphate did not compete with each other; when the cells were grown in the presence of 1 microM dexamethasone, the microsomal synthesis of Dol-P-Man was stimulated, without affecting the Ret-P-Man synthesis; Arrhenius plots on Ret-P-Man and Dol-P-Man synthesis showed breaks at 22 and 37.7 degrees C.

Metabolic potential of the adipose tissue of rats during hyper- and hypovitaminosis A.

Effect of excess feeding and depletion of vitamin A on the ability of adipose tissue to maintain plasma free fatty acid levels has been studied in rats. Both in hypervitaminosis A (fed 9 mg of retinol for 2 consecutive days) and in vitamin A deficiency (kept on a vitamin A-deficient diet for 6 weeks) the rats showed elevated levels of plasma free fatty acids. Hypervitaminosis A caused a decrease in the fatty acid release from adipose tissue on in vitro incubation, probably due to lowered levels of cyclic AMP. On the other hand, adipose tissue from vitamin A-deficient animals showed an increased lipolytic rate as compared to that of the controls. No change in the lipogenic ability was indicated in either of the conditions as indicated by the activities of enzymes involved in this process. We conclude that the fatty acid homeostasis can be greatly influenced by the vitamin A status of the animals.

Enhancement in the adhesion of tumor cells to endothelial cells by decreased cholesterol synthesis.

Adhesive interactions between tumor cells and the endothelial cells are presumed to be an obligatory step in the metastatic process. Using an in vitro model, we have examined the role of endothelial lipids in the regulation of this interaction. The cholesterol levels of bovine aorta endothelial cell monolayers were inhibited by the addition of compactin, 25-hydroxycholesterol, or 7-ketocholesterol. Metastatic B16 melanoma cells prelabeled with 14C-amino acid mixture were then deposited on this monolayer as a suspension and, at various time intervals, the number of cells adhering to the monolayer was determined. The results indicated that inhibition of cellular cholesterol caused enhancement in cell adhesion. On the other hand, perturbations of the glycosylation in the endothelial cells were without any effect on cell adhesion. The presence of cholesterol dispersion in the growth medium partially reversed the enhancement in cell adhesion caused by the cholesterol inhibitors. Growth in the presence of retinol or dexamethasone (1 microM) also caused enhancement in the adhesiveness of the tumor cells to endothelial cells, possibly because of their effects on cholesterol synthesis. Procaine, a local anesthetic which is known to increase membrane fluidity, also increased the tumor cell-endothelial interaction, suggesting that the membrane fluidity plays an important role in the regulation of cell adhesion.

The total life - vision in ancient Indian medicine.

In this paper the author discusses the ancient Ayurvedic system of India which is basically of holistic approach. The contribution of modern scholars are also summed up here.

Gerontology in ayurveda.

In this paper the author discusses how the secret of life was taken care of by our ancients. The contribution of modern research scholars in this fields are also summed up here.

NIMI TANTRA (Opthalmology of Ancient India).

The art of opthalmology was well developed in ancient India and was known as Nimi Tantra. In this paper the author presents the main features of Nimi Tantra an authoritative treatises written by Nimi, a prominent opthalmologist of his time.

Transient changes in phospholipid methylation induced by dexamethasone in lymphoid cells.

We have investigated the effect of dexamethasone on phospholipid methylation by chronic lymphatic leukemia cells in culture. Methyl transfer from S-adenosyl[methyl-3H]methionine into lipid fraction showed a sharp rise within 2 to 3 hr of dexamethasone treatment. After 6 hr of dexamethasone treatment, however, methylation decreased below the control levels and remained lower thereafter. Analysis of the lipid components indicated that the formation of phosphatidylmonomethylethanolamine was not affected by dexamethasone. However, phosphatidylcholine synthesis by the transmethylation pathway showed an initial increase followed by a decrease. The results point to the possibility that this effect may have physiological significance in the lymphocytolytic effects of glucocorticoids.

Studies on the stimulation of dolichol-mediated glycosylation by dexamethasone in HeLa cells.

The effect of the addition of 1 microM-dexamethasone on the temporal sequence of the glycosylation process has been studied in HeLa S3G cells. In the presence of delipidized serum, dexamethasone caused an increase in 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and an accelerated synthesis of dolichols. These events were followed by an increase in the transfer of mannose from GDP-mannose to mannolipid. An increase in the rate of synthesis of lipid-linked oligosaccharides and a stimulation of glycosylation were observed in cells grown in the presence of delipidized serum in the culture medium. The data are consistent with the view that cellular syntheses of lipids and glycoproteins are co-ordinately controlled.

Evidence for the stimulation of dolichol and mannolipid synthesis by glucocorticoids in HeLa cells.

The effects of addition of 1 microM-dexamethasone on the rate of transfer of mannose from GDP-mannose into mannolipid have been studied in HeLa cell cultures. Concurrent with an increase in incorporation of mannose into glycoproteins, the incorporation of mannose from GDP-mannose in vitro into mannolipid and dolichol-linked oligosaccharides was increased after dexamethasone treatment. Stimulation of mannolipid synthesis showed a correlation with the 11 beta, 17 alpha, 21-trihydroxy structure of C21 steroids. Dexamethasone treatment also resulted in an increased incorporation of acetate into dolichol and dolichyl phosphate. The results suggest that the effect of dexamethasone on the cell-surface glycoprotein accumulation is related to increased sugar-linked dolichol synthesis.

Physicians and surgeons in ancient India.

This paper briefly recapitulates the evolution of ancient medical classics its origin, the Physicians and Surgeons and their contributions in its mythological and historical background. The significance of this science in the ancient days is also evidenced by the existence, of the two seats of learning-Takshasila and Kasi-in all its prolific profundity.

Cholesterol biosynthesis in a variety of cultured cells. Lack of correlation between synthesis and activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase caused by dexamethasone.

In a variety of cell lines grown in the presence of 10(-6) M dexamethasone, the incorporation of acetate into cellular cholesterol was partially suppressed. However, the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (mevalonate:NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34) was either significantly elevated or remained unchanged providing evidence that under certain conditions 3-hydroxy-3-methylglutaryl coenzyme A reductase activity is not a valid measure of cholesterogenesis.

Early effects of hypervitaminosis A on gluconeogenic activity and amino acid metabolizing enzymes of rat liver.

In an earlier report from this laboratory, one of the early manifestations of hypervitaminosis A was shown to be a marked stimulation of hepatic gluconeogenesis. In the present study, effects of feeding 30,000 IU of retinyl palmitate to young rats (80-100 g), once daily, for 2 days on the incorporation of 14C-labeled precursors into glucose and glycogen by liver slices, levels of amino acids in blood and tissues, and activities of some important amino acid catabolizing enzymes in the liver were investigated. A stimulation of hepatic gluconeogenesis in hypervitaminosis A was indicated by the increased incorporation of 14C-labeled alanine and bicarbonate into glucose and glycogen by liver slices. Excessive intake of retinol caused a marked increase in the activities of hepatic alanine aminotransferase and ornithine aminotransferase and a decrease in that of tryptophan pyrrolase, without affecting those of tyrosine aminotransferase and serine dehydratase. The ratio of NADH:NAD in the livers of rats fed excess retinol was significantly increased. It is suggested that enhancement of glucoeogenesis in hypervitaminosis A is caused by a stimulation of gluconeogenic activity of the liver.