Biomedical subjects
P V Subbaiah
Publications and source records attributed to P V Subbaiah.
Intestinal absorption of lipids.
Explore the source record for details and available documents.
Transesterification of lysolecithin in the intestinal mucosa of rats.
Explore the source record for details and available documents.
Studies on the phospholipases of rat intestinal mucosa.
1. Subcellular distribution and characteristics of different phospholipases of rat intestinal mucosa were studied. 2. The presence of free fatty acid was necessary for the maximal hydrolysis of lecithin (phosphatidylcholine), but there was no accumulation of lysolecithin (1 or 2-acylglycerophosphorylcholine);lysolecithin accumulated when the reaction was carried out in the presence of sodium deoxycholate and at or above pH8.0. 3. The fatty acid-activated phospholipase B as well as lysolecithinase showed optimum activity at pH6.5, whereas for the phospholipase A it was about pH8.6. 4. The bulk of the phospholipase A was present in the microsomal fraction, whereas the phospholipase B and lysolecithinase activities were distributed between the microsomal and soluble fractions of the mucosal homogenate. 5. Phospholipase A was equally distributed between the brush border and brush-border-free particulate fraction, with the brush border having highest specific activity, whereas the other two activities were distributed between the brush-border-free particulate and soluble fractions. 6. Various treatments showed marked differences between the phospholipase A and phospholipase B activities, but not between phospholipase B and lysolecithinase activities. 7. By using (beta[1-(14)C]-oleoyl) lecithin it was shown that the mucosal phospholipase A was specific for the beta-ester linkage of the lecithin molecule.
Acylation of lysolecithin in the intestinal mucosa of rats.
1. The presence of an active acyl-CoA-lysolecithin (1-acylglycerophosphorylcholine) acyltransferase was demonstrated in rat intestinal mucosa. 2. ATP and CoA were necessary for the incorporation of free [1-(14)C]oleic acid into lecithin (phosphatidylcholine). 3. The reaction was about 20 times as fast with [1-(14)C]oleoyl-CoA as with free oleic acid, CoA and ATP. 4. With 1-acylglycerophosphorylcholine as the acceptor, both oleic acid and palmitic acid were incorporated into the beta-position of lecithin; the incorporation of palmitic acid was 60% of that of oleic acid. 5. Of the various analogues of lysolecithin tested as acyl acceptors from [1-(14)C]oleoyl CoA, a lysolecithin with a long-chain fatty acid at the 1-position was most efficient. 6. The enzyme was mostly present in the brush-border-free particulate fraction of the intestinal mucosa. 7. Of the various tissues of rats tested for the activity, intestinal mucosa was found to be the most active, with testes, liver, kidneys and spleen following it in decreasing order.
Acylation of lysolecithin to lecithin by a brush-border-free particular preparation from rat intestinal mucosa.
Explore the source record for details and available documents.
Further studies on the intestinal absorption of triglycerides and fatty acids in rats.
Explore the source record for details and available documents.
Atherosclerosis and oral contraceptive use. Serum from oral contraceptive users stimulates growth of arterial smooth muscle cells.
Pooled serum from women taking a combined estrogen-progestin oral contraceptive preparation caused significantly greater cell proliferation and incorporation of 3H-thymidine into DNA in both human arterial smooth muscle cells and dermal fibroblasts in tissue culture than did serum from controls. A portion of this mitogenic effect appears to be related to the presence of a factor(s) that is heat stable, nondialyzable, and contained in the lipoprotein-deficient serum fraction. In vitro addition of varying concentrations of mestranol and norethindrone, the two constituents of the oral contraceptive preparation taken by participants in the study, to control serum did not enhance its mitogenicity, suggesting that the effect observed with intact serum was due either to a metabolite of these compounds or to the production of other growth-promoting substances during oral contraceptive treatment. Since smooth muscle cell proliferation is an integral feature of all atherosclerotic lesions, these findings provide some insights applicable to understanding the pathogenesis of vascular disease associated with oral contraceptive use.