Search PubMed⌕ Search

Biomedical subjects

A Sanghvi

Publications and source records attributed to A Sanghvi.

At least 37 records · Page 2Linked to original sources
PubMed1985

Differences in the binding, internalization and catabolism of low-density lipoprotein between normal human T and B lymphocytes.

Studies in human peripheral blood B and T lymphocytes show that high-affinity binding of low-density lipoprotein (LDL) to the cell surface receptor and the kinetics of binding are comparable between B and T lymphocytes, but the internalization of receptor-bound LDL in B cells appears deficient. Yet, the fraction of internalized LDL degraded by both B and T lymphocytes is of similar magnitude. Moreover, the lysosomal acid cholesterol ester hydrolase and acyl-CoA:cholesterol acyltransferase activities in B cell were about one-third of those in T lymphocytes. These data suggest deficient LDL catabolism in B lymphocytes relative to that in T lymphocytes.

B-Lymphocytes↗
PubMed1985

Effects of casein and soy protein on hepatic and serum lipids and lipoprotein lipid distributions in the rat.

Rats fed a semipurified diet containing casein developed higher levels of circulating triglycerides and cholesterol than animals fed a soy protein-containing diet. The increased serum lipid levels in non-fasted rats were associated largely with the d less than 1.006 g/ml lipoprotein particles (e.g. chylomicrons or very low density-like lipoproteins). In addition, casein-fed rats exhibited higher levels of circulating insulin and depressed hepatic 7 alpha-hydroxylase levels compared to soy-fed rats. Supplementation of the casein diet with arginine, to give an arginine/lysine ratio comparable to that in the soy diet, resulted in a reduction of d less than 1.006 g/ml lipids, a reduction in serum insulin levels and an elevation in hepatic 7 alpha-hydroxylase activity. Supplementation of the soy diet with lysine also resulted in modification of these parameters toward those observed with casein diets, albeit the effects were less dramatic. The results suggest that the hyperlipidemia associated with feeding casein-based diet is associated with decreased rates of clearance of chylomicron-like lipoproteins and their component triglycerides and cholesterol. Furthermore, this is largely prevented by addition of arginine to diets containing casein as the sole protein source.

Animals↗
PubMed1985

Pituitary and thyroid hormone levels before and after orthotopic hepatic transplantation and their responses to thyrotropin-releasing hormone.

Basal and TRH-induced responses of T3, T4, TSH, GH, and PRL were determined before and 1 month after orthotopic hepatic transplantation in 41 patients (22 with primary biliary cirrhosis and 19 with primary sclerosing cholangitis). The responses of these patients before and after transplantation were compared to those of age-matched normal subjects. The results demonstrate that 1 month after successful hepatic transplantation, basal and TRH-induced TSH, GH, and PRL levels had decreased toward, but not completely to, normal levels.

Adult↗
PubMed1985

Mycetoma caused by Aspergillus nidulans in India.

The first case of mycetoma caused by Aspergillus nidulans has been described from India in a young farmer of Jaisalmer situated in the Thar desert of Western Rajasthan, India. The diagnosis was confirmed by histopathological and mycological studies.

Adult↗
PubMed1985

Cyclosporine measurement in transplantation.

Use of cyclosporine is a major breakthrough in immunosuppressive therapy for organ transplantation. Critical to its success, however, is the availability of regular and frequent measurements of the blood levels of the drug. Radioimmunoassay and/or high-pressure liquid chromatography may be employed for this analysis. Radioimmunoassay measures the parent molecule together with its metabolites, whereas high-pressure liquid chromatography measures only the parent drug, which indicates that clinical and laboratory experience, as well as an understanding of methodology, are necessary for the interpretation of cyclosporine levels.

Chromatography, High Pressure Liquid↗
PubMed1985

Measurement of urinary chloride with the Kodak Ektachem 400.

Urinary chloride can be measured simply, precisely, and accurately with the Ektachem 400 clinical chemistry analyzer. Because the coated film technique used in this instrument requires the presence of a protein matrix, we added a protein-based calibrator to the urine samples to overcome the low protein concentration in these specimens. Its advantages over a coulometric titration method (Astra analyzer) include the extension of the range of linearity to lower concentrations and the absence of interference from prednisone metabolites in urine. A disadvantage is the negative bias interference of allopurinol.

Autoanalysis↗
PubMed1984

Properties of cholesterol 7 alpha-hydroxylase in rat liver microsomal acetone powder.

Rat liver microsomes were extracted with acetone, and a microsomal powder preparation was obtained. The cholesterol 7 alpha-hydroxylase activity of acetone powder was linear with time, the amount of protein, and the amount of cholesterol in human or rat serum. Unesterified lipoprotein cholesterol was also an effective substrate, and the Km values increased progressively from high-density lipoprotein (HDL) to low-density lipoprotein (LDL) to very-low-density lipoprotein (VLDL), suggesting that HDL-free-cholesterol was the better substrate.

Acetone↗
PubMed1983

Differential suppression of lymphocyte cholesterol synthesis by low density lipoprotein and erythrocyte insulin receptors in normolipidemic subjects.

The rates of cholesterol synthesis from acetate were studied in freshly isolated peripheral blood lymphocytes in 41 age- and sex-matched subjects with essentially normal serum lipid profiles. Insulin binding to erythrocytes obtained from the same blood samples was also studied simultaneously. From the data on lymphocyte cholesterol synthesis in the absence or presence of low density lipoprotein in the medium, an index, LDL50, was calculated for each subject. This is the concentration of LDL cholesterol (nmol/ml) in the medium necessary to reduce cholesterol synthesis to 50% of that in the absence of LDL. On the basis of LDL50, the subjects could be segregated into three distinct groups, I, II, and III, with LDL50 of 6.5, 23.3, and 77.0 nmol/ml, respectively. This grouping was independent of the serum lipid profiles, age or sex. Insulin binding studies showed that the amount of insulin specifically bound and the number of insulin receptors per cell were inversely correlated with LDL50. LDL50 was also determined for 4 subjects with clinically manifested consequences of familial hypercholesterolemia. The LDL50 values for these individuals corresponded to values obtained for subjects in group III. The number of insulin receptors and the amount of insulin bound in these patients were correspondingly low. These results suggest that LDL50 may be useful in discerning abnormal cellular cholesterol metabolism in subjects with or without accompanying hyperlipidemias.

Adult↗
PubMed1983

Loss of cholesterol 7 alpha-hydroxylase activity in vitro in the presence of bivalent metal ions and by dialysis of rat liver microsomes.

A loss in cholesterol 7 alpha-hydroxylase activity [cholesterol 7 alpha-monooxygenase; cholesterol,NADPH:oxygen oxidoreductase (7 alpha-hydroxylating), EC 1.14.13.17] was seen when rat liver microsomes were incubated in the presence of Ca2+, Mg2+, or Mn2+. The loss in enzyme activity was complete within only 5 min of incubation with Ca2+ and Mn2+, whereas Mg2+ required 10 to 15 min of incubation with microsomes to produce a similar inhibition. This effect of metal ions could be blocked if the incubations were carried out in phosphate buffer. Similarly, preincubation of microsomes in the presence of NaF completely prevented the loss in enzyme activity due to Ca2+ and Mg2+ ions, but only partially the loss due to Mn2+. These results suggest metal ion activation of an endogenous microsomal phosphatase, which in turn may inactivate cholesterol 7 alpha-hydroxylase through its dephosphorylation. Further, a dialyzable microsomal factor appears to be essential for stabilizing the enzyme, because dialysis of a microsomal suspension results in a considerable loss of enzyme activity.

Adenosine Triphosphate↗
PubMed1983

Regulation of three key enzymes in cholesterol metabolism by phosphorylation/dephosphorylation.

Our laboratories have investigated the role of phosphorylation/dephosphorylation in the regulation of three key enzymes in cholesterol metabolism. 3-Hydroxy-3-methylglutarylcoenzyme A (HMG-CoA) reductase (EC 1.1.1.34), the major regulatory enzyme in cholesterol biosynthesis, is inhibited by phosphorylation. Acyl-CoA:cholesterol O-acyltransferase (ACATase; EC 2.3.1.26) and cholesterol 7 alpha-hydroxylase (EC 1.14.13.7), key regulatory enzymes in the utilization of cholesterol, are activated by phosphorylation. In view of these results, we propose that short-term regulation of the concentration of intracellular unesterified cholesterol is achieved by a coordinate phosphorylation/dephosphorylation of these three enzymes. For example, if cholesterol enters the liver cell, HMG-CoA reductase would be inhibited by phosphorylation and biosynthesis of cholesterol would be reduced; however, reactions utilizing cholesterol would be activated, due to the phosphorylation of ACATase and cholesterol 7 alpha-hydroxylase. Thus, the phosphorylation/dephosphorylation of these three enzymes provides an elegant short-term mechanism for the homeostasis of intracellular unesterified cholesterol.

Acyltransferases↗
PubMed1983

Recovery of sexual function in abstinent alcoholic men.

Sixty chronically alcoholic men who were impotent and known to have abstained from alcohol were followed prospectively to determine (a) the frequency of spontaneous recovery of normal sexual functioning, (b) indicators of spontaneous recovery, and (c) the response of those who did not achieve a spontaneous recovery to agents known to interact with the hypothalamic-pituitary-gonadal axis. Twenty-five percent of the men studied experienced a spontaneous recovery. Indicators of a spontaneous recovery were absence of testicular atrophy and normal gonadotropin responses to luteinizing hormone releasing factor or clomiphene, or both. Interestingly, the severity of the biochemical or histologic liver disease at admission to study did not have value in predicting endocrine responses or recovery of sexual functioning with continued abstinence. Those not recovering spontaneously were treated sequentially with clomiphene, human chorionic gonadotropin, and an oral exogenous androgen, fluoxymesterone. Only the androgen produced acceptable results and then only at unusually high doses, suggesting some degree of androgen insensitivity in such men.

Adult↗
PubMed1982

Effect of detergents on in vitro 7 alpha-hydroxycholesterol formation by rat liver microsomes.

Formation of 7 alpha-hydroxycholesterol by rat liver microsomes was quantitated using a gas chromatograph-mass spectrometer (GC/MS) operated in selected ion monitoring (SIM) mode. Microsomes from normal rat livers incubated for different periods were found to yield increased 7 alpha-hydroxycholesterol with time. This was also true when incubations contained Tween-80, but in this instance, the rate of 7 alpha-hydroxycholesterol production was lower and dependent on the concentration of Tween used. Similarly, Triton X-100, Renex-30, Kyro EOB, Cutscum, and Emulgen 911 all lowered the formation of 7 alpha-hydroxycholesterol by rat liver microsomes, whereas Triton WR-1339 stimulated its production. Analysis of data obtained from following the enzyme reaction over an extended period using an integrated Michaelis-Menten equation indicated the enzyme possesses a very significant affinity for the product (Ks greater than Kp). Similar analysis shows that Tween-80 is a noncompetitive inhibitor of the enzyme.

Animals↗
PubMed1981

On the differential suppression of cholesterol synthesis by low density lipoprotein in B and T lymphocytes.

Cholesterol synthesis and its suppression by low density lipoprotein cholesterol were measured in purified B and T peripheral blood lymphocytes. After preincubation for 53 h in lipoprotein-deficient serum, both B and T cells exhibited increased cholesterol synthesis as compared with synthesis measured in cells immediately after their isolation from blood and without preincubation with lipoprotein-deficient serum. The magnitude of this increase was far greater in T cells in comparison with that in B cells in all subjects studied. But, whereas there was an immediate and progressive suppression of cholesterol synthesis in lipoprotein-deficient serum-incubated T cells as the concentration of low density lipoprotein cholesterol in the medium was increased, synthesis in lipoprotein-deficient serum-incubated B cells remained insensitive to the presence of low density lipoprotein in the medium. Hydroxymethylglutaryl-CoA reductase activity was observed also to follow a similar pattern in both cell types. These observations may imply that one or more events, including binding of low density lipoprotein to its receptor, internalization and degradation of low density lipoprotein receptor complex finally leading to suppression of hydroxymethylglutaryl-CoA reductase activity and cholesterol synthesis, fail to take place in B cells.

Adult↗