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Biomedical subjects

M T Subbiah

Publications and source records attributed to M T Subbiah.

161 records · Page 9Linked to original sources
PubMedDate not supplied

Regional differences in cholesterol content of aorta in response to experimental coarctation in spontaneously atherosclerosis-susceptible pigeons.

The effect of experimental coarctation of the aorta at a site above the coeliac bifurcation (site of occurance of spontaneous atherosclerotic lesions) in White Carneau pigeons was examined. Cholesterol content of the aorta in the site where spontaneous atherosclerosis usually occurs (coeliac bifurcation = lesion site) was decreased in pigeons with aortic coarctation. On the other hand, in the region proximal to the site of coarctation which is usually free of atherosclerotic events cholesterol accumulation was increased. A decrease in percent composition of oleic acid (the major fatty acid which increases during atherosclerosis) was noted in the lesion site. These studies have shown regional differences in response of aorta to experimental coarctation in spontaneously atherosclerotic-susceptible pigeons and suggest that lowering of blood pressure at lesion site might decrease cholesterol accumulation and perhaps might retard subsequent atherogenic process.

Animals↗
PubMedDate not supplied

Morphological and smooth muscle cell phenotypic changes in fetal rabbit aorta during early development.

Previous studies from our laboratory noted a) high aortic cholesterol esterification activity in the fetal rabbit, and b) increased susceptibility of fetal aortic explants to smooth muscle cell proliferation in culture, two features commonly associated with atherogenesis. This prompted us to examine in detail morphological development of fetal aorta and its relationship to fetal plasma cholesterol levels. Our studies made three important observations: 1) plasma cholesterol levels were high in early fetus which decreased at term; 2) in early fetus aortic endothelial cells appear to protrude into the lumen, whereas at birth the cells become flat, forming a continuous endothelium sheet; 3) in early fetus, smooth muscle cells exist predominantly in synthetic phenotype, while at birth the cells appear contractile. Despite the presence of synthetic smooth muscle cells and hypercholesterolemia in early fetal life, no accumulation of lipids was evident under transmission electron microscopy.

Animals↗
PubMedDate not supplied

The effect of ileal bypass on sterol balance and plasma cholesterol in the White Carneau pigeon.

The effect of ileal bypass on steady-state sterol balance and plasma cholesterol was studied in sham operated (SO) and ileal bypass (IB) White Carneau pigeons 6 months (Group I) and 18 months (Group II) after surgery while fed their usual cholesterol-free diet. Unlike what has been noted in other animals, the bile acid (BA) and neutral sterol (NS) excretion (mg/kg per day) in IB was not statistically different from that in SO. Group I: BA, 40.2 (SO) vs 39.0 (IB); NS, 13.3 (SO) vs 17.3 (IB). Group II: BA, 55.7 (SO) vs 54.1 (IB); NS, 9.57 (SO) vs 8.84 (IB). IB pigeons had only slightly lower plasma cholesterol levels (postoperative) than SO pigeons. Group I, 329 (SO) vs 271 (IB) mg/dl (P less than 0.05); Group II, 374 (SO) vs 312 (IB) mg/dl. This study indicates that the response to ileal bypass by White Carneau pigeons in terms of cholesterol excretion and plasma cholesterol changes is different than what has been observed in other species.

Animals↗
PubMedDate not supplied

Age-related interrelationships of blood pressure and arterial sterol accumulation in spontaneously atherosclerosis-susceptible and atherosclerosis-resistant pigeons.

Interrelationships of arterial sterol accumulation and blood pressures were examined in age-matched White Carneau and Show Racer pigeons. It was found that the systolic blood pressure of White Carneaux changed from 155.0 mm Hg at nine months of age to 168.8 mm Hg at 17 months of age (P less than 0.005) while that of the Show Racers did not show any age-related increases. In White Carneaux, the total sterol content in the aorta increased by 43.6% from 9 months to 17 months of age (P less than 0.001) with major changes in the steryl ester fraction while no such changes were evident in the Show Racers. This indicates interrelationships of the arterial sterol content and blood pressure in the White Carneau pigeon.

Aging↗
PubMedDate not supplied

Cholestyramine feeding in weaned rats. Increase in plasma corticosterone levels and bile acid synthesis following adrenalectomy.

Feeding cholestyramine to weaned rats increased the bile acid pool and activity of cholesterol 7 alpha-hydroxylase as expected. Following adrenalectomy, cholestyramine still increased the activity of cholesterol 7 alpha-hydroxylase but the magnitude of increase was lower (P less than 0.01) than noted in intact rats. Surprisingly, cholestyramine feeding to both intact and adrenalectomized rats increased plasma levels of corticosterone.

Adrenal Glands↗
PubMedDate not supplied

Dietary inclusion of whole soy foods results in significant reductions in clinical risk factors for osteoporosis and cardiovascular disease in normal postmenopausal women.

OBJECTIVE: To determine the effects of dietary inclusion of soy foods on clinical markers for cardiovascular disease (CVD) and osteoporosis in normal postmenopausal women. DESIGN: This was a single open-group prospective clinical intervention. Forty-two normal postmenopausal women consumed three daily servings for 12 consecutive weeks of whole soy foods containing approximately 60 mg/d of isoflavones. Blood and urine specimens were obtained at baseline and after 12 weeks of dietary intervention. RESULTS: Serum and urine levels of individual and total isoflavones increased significantly (7-19 fold, p < 0.001) from baseline. A significant increase (9.3%, p < 0.05) in the mean lag-time of low-density lipoprotein cholesterol oxidation was seen and was positively correlated with serum phytoestrogens (p < 0.05). Significant increases were found in mean levels of high-density lipoprotein cholesterol (HDLc) (3.7%, p < 0.05) and serum osteocalcin (10.2%, p < 0.025). Significant decreases were observed in total cholesterol:HDLc ratios (5.5%, p < 0.006) and mean urinary N-telopeptide excretion (13.9%, p < 0.02). Urinary excretion of total isoflavones was negatively correlated with very-low-density lipoprotein cholesterol, triglycerides, and total cholesterol:HDLc ratios (p < 0.04). No significant changes from baseline in HDLc peroxidation, total cholesterol, triglycerides, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, bone-specific alkaline phosphatase, follicle-stimulating hormone, or estradiol levels were observed. CONCLUSIONS: Dietary inclusion of whole soy foods containing 60 mg/d of isoflavones results in significant serum levels of phytoestrogens and reductions in several key clinical risk factors for CVD and osteoporosis in normal postmenopausal women. Long-term, placebo-controlled clinical trials are needed to evaluate the effect of phytoestrogens on the clinical endpoints of CVD and osteoporosis in this population.

Cardiovascular Diseases↗
PubMedDate not supplied

Effect of testosterone and oxandrolone on thrombocyte aggregation and synthesis of prostaglandins in thrombocytes and aorta of atherosclerosis-susceptible pigeons.

Effect of intramuscular administration (10 mg/kg/week) of testosterone and oxandrolone on a) thrombocyte aggregation and b) synthesis of prostaglandins from [14C]-arachidonic acid in thrombocytes and aorta of atherosclerosis-susceptible White Carneau pigeon was examined. Neither testosterone nor oxandrolone influenced collagen, ADP and arachidonic acid induced aggregation or the synthesis of prostaglandins in thrombocytes. However, both testosterone and oxandrolone stimulated (p less than 0.05) the synthesis of 6-keto-PGF1 alpha (stable product of prostacyclin) und PGE2 in aorta.

Animals↗
PubMedDate not supplied

Effect of enteral feeding on hepatic steatosis induced by total parenteral nutrition.

This study was designed to test the hypothesis that deprivation of enteral feeding contributes to the development of total parenteral nutrition (TPN)-induced hepatic dysfunction and that alterations of gut hormones are involved in its pathogenesis. Twenty-one adult Sprague-Dawley rats were randomized into three groups: group 1 received chow feeding ad libitum (288 kcal/kg per day); group 2 received dextrose-based TPN (320 +/- 5 kcal/kg per day); and group 3 received TPN (315 +/- 15 kcal/kg per day) plus chow feeding ad libitum (74 +/- 1 kcal/kg per day). After 7 days, portal blood was assayed for insulin, glucagon, gastrin, peptide YY, secretin, and vasoactive intestinal polypeptide; systemic blood for determination of liver function tests and serum lipid analysis. Liver biopsies were taken for histology and staining for fat, and the remainder of the livers were removed for tissue lipid analysis. TPN induced striking hepatic steatosis with prominent histologic changes and accumulation of lipids, mainly triglycerides and cholesterol ester, in the liver. Addition of enteral feeding to TPN-treated animals significantly reduced the histologic changes as well as lipid accumulation in the liver. Portal plasma levels of gastrin and peptide YY were reduced in animals maintained on TPN alone, with no change in secretin or vasoactive intestinal polypeptide levels. Enteral supplementation increased peptide YY levels in group 3, but not to normal, while gastrin secretion remained decreased. The serum triglyceride levels were decreased in both TPN groups; no differences were detected in the serum cholesterol levels or liver function tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗