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Biomedical subjects

Carl Grunfeld

Publications and source records attributed to Carl Grunfeld.

45 records · Page 3Linked to original sources
PubMed2002

Sick euthyroid syndrome is associated with decreased TR expression and DNA binding in mouse liver.

Infection is associated with low serum thyroid hormones and thyrotropin levels. Here we demonstrate that infection also reduces thyroid hormone receptor (TR) expression. In gel shift experiments, retinoid X receptor (RXR)/TR DNA binding was reduced in mouse liver by 60 and 77%, respectively, 4 and 16 h after lipopolysaccharide (LPS) administration. Surprisingly, LPS did not decrease either TR-alpha or TR-beta protein levels at 4 h, but by 16 h TR-alpha(1), TR-alpha(2), and TR-beta levels were reduced by 55, 87, and 41%, respectively. We previously reported that LPS rapidly decreases RXR protein levels in liver. Therefore, we added RXR-beta to hepatic nuclear extracts prepared 4 h after LPS treatment, which restored RXR/TR DNA binding to a level comparable to that of controls. A similar experiment conducted on extracts prepared 16 h after LPS administration did not restore RXR/TR DNA binding. We propose that decreased RXR expression is limiting for RXR/TR DNA binding at 4 h, whereas the reduction in both TR and RXR levels results in further decreased binding at 16 h.

Animals↗
PubMed2002

Altered gene expressions involved in energy expenditure in 5-HT(2C) receptor mutant mice.

Mice with a targeted null mutation of the serotonin 5-HT(2C) receptor gene exhibit hyperphagia that leads to a late-onset obesity. Here we show that oxygen consumption was decreased in fed and fasted obese mutants. No phenotypic differences were observed in uncoupling protein-1 (UCP-1) mRNA levels in brown adipose tissues and UCP-3 mRNA in skeletal muscle. UCP-2 mRNA levels were significantly increased in white adipose tissue (4-fold) and skeletal muscle (47%) in older obese mutant mice, whereas UCP-2 mRNA in liver are significantly increased in both young lean (54% increase) and older obese (52% increase) mutant mice. In contrast, 5-HT(2C) receptor mutants displayed age-dependent decreases in beta 3-adrenergic receptor (beta 3-AR) mRNA levels in white adipose tissue, however, no such changes were observed in brown adipose tissue. These results indicate that a mutation of 5-HT(2C) receptor gene leads to a secondary decrease in beta 3-AR gene expression that is related to enhanced adiposity.

Animals↗
PubMed2002

Reduction in cytochrome P-450 enzyme expression is associated with repression of CAR (constitutive androstane receptor) and PXR (pregnane X receptor) in mouse liver during the acute phase response.

Expression of P-450 (Cyp) enzymes is reduced in liver during the acute phase response, contributing to the decrease in bile acid levels and drug metabolism during infection. Nuclear hormone receptors CAR and PXR are key transactivators of Cyp2b and Cyp3a genes, respectively. Injection of bacterial lipopolysaccharide (LPS) induced the expected reduction in Cyp2b10 and Cyp3a mRNA levels in mouse liver. These decreases were associated with a marked reduction in CAR and PXR mRNA levels within 4 h following treatment. LPS-induced CAR and PXR repression were dose-dependent and sustained for at least 16 h. LPS treatment also reversed the up-regulation of Cyp3a in mice pre-treated with PXR ligand RU486. In addition, we observed a concomitant decrease in RXR (retinoid X receptor) mRNA levels, the obligatory partner of both CAR and PXR for high affinity binding to DNA. These findings represent one possible molecular mechanism underlying sepsis-induced repression of Cyp enzymes.

Animals↗
PubMed2002

Indinavir acutely inhibits insulin-stimulated glucose disposal in humans: a randomized, placebo-controlled study.

BACKGROUND: Therapy with HIV protease inhibitors (PI) causes insulin resistance even in the absence of HIV infection, hyperlipidemia or changes in body composition. The mechanism of the effects on insulin action is unknown. In vitro studies suggest that PI selectively and rapidly inhibit the activity of the insulin-responsive glucose transporter GLUT-4. We hypothesized that a single dose of the PI indinavir resulting in therapeutic plasma concentrations would acutely decrease insulin-stimulated glucose disposal in healthy human volunteers. METHODS: Randomized, double-blind, cross-over study comparing the effect of 1200 mg of orally administered indinavir and placebo on insulin-stimulated glucose disposal during a 180-min euglycemic, hyperinsulinemic clamp. Six healthy HIV-seronegative adult male volunteers were studied twice with 7 to 10 days between studies. RESULTS: There were no significant differences in baseline fasting body weight, or plasma glucose, insulin, lipid and lipoprotein levels between placebo- and indinavir-treated subjects. During steady-state (t60-180 min) insulin reached comparable levels (394 +/- 13 versus 390 +/- 11 pmol/l) and glucose was clamped at approximately 4.4 mmol/l under both conditions. The average maximum concentration of indinavir was 9.4 +/- 2.2 microM and the 2-h area under the curve was 13.5 +/- 3.1 microM.h. Insulin-stimulated glucose disposal per unit of insulin (M/I) decreased in all subjects from 14.1 +/- 1.2 to 9.2 +/- 0.8 mg/kg.min per microUI/ml (95% confidence interval for change, 3.7-6.1; P < 0.001) on indinavir (average decrease, 34.1 +/- 9.2%). The non-oxidative component of total glucose disposal (storage) decreased from 3.9 +/- 1.8 to 1.9 +/- 0.9 mg/kg.min (P < 0.01). Free fatty acid levels were not significantly different at baseline and were suppressed equally with insulin administration during both studies. CONCLUSIONS: A single dose of indinavir acutely decreases total and non-oxidative insulin-stimulated glucose disposal during a euglycemic, hyperinsulinemic clamp. Our data are compatible with the hypothesis that an acute effect of indinavir on glucose disposal in humans is mediated by a direct blockade of GLUT-4 transporters.

Adult↗
PubMed2002

Steatosis in chronic hepatitis C: relative contributions of obesity, diabetes mellitus, and alcohol.

Steatosis has emerged as a histologic finding of importance to the progression of hepatitis C virus (HCV)-associated liver disease. However, most studies of HCV-associated steatosis have excluded alcohol drinkers and individuals with diabetes and thus have not addressed the relative contribution of known causes of steatosis to liver injury in HCV-associated disease. To address this issue, we studied 297 consecutive patients with HCV who met inclusion criteria. Alcohol consumption, demographics, and serologic tests were correlated with degrees of steatosis and fibrosis on liver biopsy. Liver biopsy specimens were also examined for evidence of significant alcohol or nonalcoholic steatohepatitis (NASH) injury. In univariate analysis, steatosis correlated with type 2 diabetes mellitus (P =.005) and body mass index (BMI) (P =.0001) but not with the intensity of alcohol intake (in grams per day). In multivariate analysis, BMI (P =.0002) and genotype 3a infection (P =.02) were independent predictors of steatosis. When patients with risk factors for NASH were excluded, genotype 3a infection was the only independent predictor of steatosis. Steatosis (P =.04) and inflammation (P <.0001) scores on liver biopsy were the only independent predictors of fibrosis. Significant alcohol or NASH injury was found in only 6% of biopsy specimens. In conclusion, steatosis in HCV infection is associated with risk factors for NASH, particularly obesity, rather than alcohol consumption.

Adult↗
PubMed2002

Effects of recombinant human growth hormone on hepatic lipid and carbohydrate metabolism in HIV-infected patients with fat accumulation.

We recently reported that treatment with a pharmacologic dose of recombinant human growth hormone (GH) resulted in a significant loss of body fat and gain in lean tissue in HIV-infected patients with syndromes of fat accumulation. However, insulin-mediated glucose disposal decreased transiently after one month of GH therapy. The present paper focuses on the changes of hepatic carbohydrate and fat metabolism associated with GH treatment in the same subjects. We assessed hepatic insulin sensitivity under both fasting and hyperinsulinemic-euglycemic clamp conditions prior to and after one and six months of GH treatment (3 mg/day) in five patients using stable isotope tracer techniques. Indirect calorimetry, and measurements of lipid concentrations. Fasting endogenous glucose production (EGP) increased significantly at one month (12.0 +/- 0.7 to 14.9 +/- 0.9 micromol/kg/min, P < 0.03), and the increase was sustained at six months of GH treatment (14.0 +/- 1.1 micromol/kg/min, NS). This increase in EGP was driven in part by increased glucogenesis (GNG) (3.5 +/- 0.9 to 5.2 +/- 0.9 and 5.8 +/-1.2 micromol/kg/min, n = 4, P < 0.01 and P < 0.01 at one and six months, respectively); small changes in hepatic glycogenolysis also contributed. Sustained increases in lipolysis and progressive decreases in hepatic fractional de novo lipogenesis (DNL) and triglyceride concentrations occurred with GH treatment. These changes were accompanied by an improved lipid profile with a significant increase in HDL cholesterol and significant decreases in total and LDL cholesterol and triglyceride levels, the latter consistent with the decrease in hepatic DNL. During a hyperinsulinemic-euglycemic glucose clamp, EGP and GNG were markedly suppressed compared to the corresponding time points under fasting conditions, albeit less so when measured after one month of GH treatment. Thus, in HIV-infected patients with abnormal fat distribution, pharmacologic doses of GH improved the overall lipid profile, but worsened glucose homeostasis under both fasting and hyperinsulinemic conditions. The combined implications of these positive and negative metabolic effects for cardiovascular disease risk remain unknown.

Adipose Tissue↗
PubMed2002

The fatty liver in AIDS.

Steatosis or fatty liver in individuals with human immunodeficiency virus (HIV) may result from HIV itself, the use of nucleoside analogues, concurrent infection with hepatitis B or C, alcohol use, diabetes mellitus, obesity, or combinations of these factors. Nucleoside analogues have been the focus of increasing concern, because several fatal cases of severe macrosteatosis, lactic acidosis, and hepatomegaly have been linked to the use of nucleoside analogues. Other classes of antiretroviral drugs, as well as opportunistic infections, can also cause hepatic injury without steatosis. The additive effect of these different risk factors, especially in the presence of underlying hepatic steatosis, likely contributes to the increased prevalence of hepatic abnormalities among HIV-infected individuals. The conditions under which some patients rapidly progress to hepatic failure and/or cirrhosis need to be defined. This is a US government work. There are no restrictions on its use.

Acquired Immunodeficiency Syndrome↗