Comparison of the relative contributions of intra-abdominal and liver fat to components of the metabolic syndrome.

Abdominally obese individuals with the metabolic syndrome often have excess fat deposition both intra-abdominally (IA) and in the liver, but the relative contribution of these two deposits to variation in components of the metabolic syndrome remains unclear. We determined the mutually independent quantitative contributions of IA and liver fat to components of the syndrome, fasting serum (fS) insulin, and liver enzymes and measures of hepatic insulin sensitivity in 356 subjects (mean age 42 years, mean BMI 29.7 kg/m²) in whom liver fat and abdominal fat volumes were measured. IA and liver fat contents were correlated (r = 0.65, P < 0.0001). In multivariate linear regression analyses including either liver or IA fat, liver fat or IA fat explained variation in fS-triglyceride (TG) and high-density lipoprotein (HDL) cholesterol, plasma glucose, insulin and liver enzyme concentrations, and hepatic insulin sensitivity independent of age, gender, subcutaneous (SC) fat, and/or lean body mass (LBM). Including both liver and IA fat, liver and IA fat both explained variation in TG, HDL cholesterol, insulin and hepatic insulin sensitivity independent of each other and of age, gender, SC fat, and LBM. Liver fat independently predicted glucose and liver enzymes. SC fat and age explained variation in blood pressure. In conclusion, both IA and liver fat independently of each other explain variation in serum TG, HDL cholesterol, insulin concentrations and hepatic insulin sensitivity, thus supporting that both fat depots are important predictors of these components of the metabolic syndrome.

Increased coagulation factor VIII, IX, XI and XII activities in non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Obesity and the metabolic syndrome are established risk factors of venous thromboembolism. As most coagulation factors are produced exclusively by the liver and non-alcoholic fatty liver disease (NAFLD) is tightly related to metabolic disorders, we aimed at studying the association of liver fat with various coagulation factor activities. METHODS: Plasma prothrombin (PT) and activated partial thromboplastin time, activities of vWF:RCo, FVII, FVIII, FIX, FXI, FXII, FXIII, fibrinogen and D-dimer concentrations were measured in 54 subjects with and 44 without NAFLD diagnosed by proton magnetic resonance spectroscopy. Subjects were recruited retrospectively for metabolic studies in our laboratory. The body composition and features of insulin resistance were measured in all subjects. RESULTS: FVIII (107±30 vs. 84±22%, P<0.001), FIX (110±14 vs. 94±16%, P<0.001), FXI (109±16 vs. 96±19%, P=0.001) and FXII (113±21 vs. 99±32%, P=0.002) activities were consistently elevated in subjects with as compared with those without NAFLD. Liver fat percentage was positively related to FVIII (r=0.28, P=0.005), FIX (r=0.36, P=0.0003), FXI (r=0.29, P=0.004) and FXII (r=0.30, P=0.003) activities, again independent of age, gender and body mass index (BMI). PT%, vWF:RCo activity and fibrinogen were higher in subjects with as compared with those without NAFLD, but this difference disappeared after adjusting for age, gender and BMI. CONCLUSION: FVIII, FIX, FXI and FXII activities are increased in human NAFLD and correlate with the features of insulin resistance. The relationships between NAFLD and these coagulation factors are independent of age, gender and BMI, suggesting that the fatty liver can contribute to the risk of thrombosis.

Nonalcoholic fatty liver disease: detection of elevated nicotinamide adenine dinucleotide phosphate with in vivo 3.0-T 31P MR spectroscopy with proton decoupling.

PURPOSE: To determine if 3.0-T proton-decoupled phosphorus 31 ((31)P) magnetic resonance (MR) spectroscopy can be used to differentiate between stages of nonalcoholic fatty liver disease (NAFLD) by resolving the components of phosphomonoester (PME) and phosphodiester (PDE) and enabling detection of a greater number of other phosphorus-containing compounds. MATERIALS AND METHODS: This study was approved by the ethics committee of Helsinki University Central Hospital, and written informed consent was obtained from all study subjects. A 3.0-T clinical imager was used to obtain proton-decoupled (31)P MR spectra in the liver of control subjects (n = 12), patients with biopsy-proved simple steatosis due to nonalcoholic causes (nonalcoholic fatty liver, n = 13; nonalcoholic steatohepatitis [NASH], n = 9), and patients with cirrhosis (n = 9) to determine PME, phosphoethanolamine (PE), phosphocholine, PDE, glycerophosphocholine (GPC), glycerophosphoryl ethanolamine, uridine diphosphoglucose, nicotinamide adenine dinucleotide phosphate (NADPH), inorganic phosphate, phosphoenolpyruvate, and alpha-, beta- and gamma-nucleotide triphosphate levels. Liver fat was determined with hydrogen 1 MR spectroscopy. Differences between the disease groups were analyzed with one-way analysis of variance. RESULTS: The PME/(PME + PDE), PME/PDE, and PE/(PME + PDE) ratios were higher and the GPC/(PME + PDE) ratio was lower in patients with cirrhosis than in the other study groups (P < or = .001, one-way analysis of variance). The NADPH/(PME + PDE) ratio was higher in patients with NASH and those with cirrhosis than in control subjects (P < .05, post hoc analyses) and correlated with disease severity (P = .007). CONCLUSION: NADPH, a marker of inflammation and fibrinogenic activity in the liver, is increased in patients with NASH and those with cirrhosis. Proton-decoupled (31)P 3.0-T MR spectroscopy shows promise in the differentiation of NAFLD stages.

Liver fat and lipid oxidation in humans.

BACKGROUND: Studies in animals show that changes in hepatic fatty acid oxidation alter liver fat content. Human data regarding whole-body and hepatic lipid oxidation are controversial and based on studies of only a few subjects. AIMS: We examined whether whole-body and hepatic lipid oxidation are altered in subjects with non-alcoholic fatty liver disease (NAFLD) compared with controls. METHODS: In vivo measurements of rates of substrate oxidation and insulin sensitivity (using the euglycaemic hyperinsulinaemic clamp technique in combination with indirect calorimetry and infusion of [3-(3)H]glucose) were performed in subjects with NAFLD [mean liver fat 14.0% (interquartile range 7.5-20.5%), n=29] and in control subjects [1.6% (1.0-3.0%), n=29]. Liver fat was measured using proton magnetic resonance spectroscopy. Plasma concentrations of 3-hydroxybutyrate (3-OHB) were measured as markers of hepatic lipid oxidation. RESULTS: In the basal state, substrate oxidation rates and serum 3-OHB concentrations were comparable in subjects with and without NAFLD. Plasma 3-OHB concentrations were similarly suppressed by insulin in both the groups. During the insulin infusion, whole-body lipid oxidation was inversely correlated with insulin-stimulated glucose disposal (r=-0.48, P<0.0001), which was lower in subjects with NAFLD [3.7+/-0.2 mg/(kg fat-free mass min)] than in the control subjects [5.0+/-0.3 mg/(kg fat-free mass min), P=0.0008]. CONCLUSIONS: Hepatic lipid oxidation is unchanged in NAFLD. Whole-body lipid oxidation is increased because of peripheral insulin resistance. These data imply that alterations in hepatic fatty acid oxidation do not contribute to liver fat content in humans.

Prediction of non-alcoholic fatty liver disease and liver fat using metabolic and genetic factors.

BACKGROUND & AIMS: Our aims were to develop a method to accurately predict non-alcoholic fatty liver disease (NAFLD) and liver fat content based on routinely available clinical and laboratory data and to test whether knowledge of the recently discovered genetic variant in the PNPLA3 gene (rs738409) increases accuracy of the prediction. METHODS: Liver fat content was measured using proton magnetic resonance spectroscopy in 470 subjects, who were randomly divided into estimation (two thirds of the subjects, n = 313) and validation (one third of the subjects, n = 157) groups. Multivariate logistic and linear regression analyses were used to create an NAFLD liver fat score to diagnose NAFLD and liver fat equation to estimate liver fat percentage in each individual. RESULTS: The presence of the metabolic syndrome and type 2 diabetes, fasting serum (fS) insulin, fS-aspartate aminotransferase (AST), and the AST/alanine aminotransferase ratio were independent predictors of NAFLD. The score had an area under the receiver operating characteristic curve of 0.87 in the estimation and 0.86 in the validation group. The optimal cut-off point of -0.640 predicted increased liver fat content with sensitivity of 86% and specificity of 71%. Addition of the genetic information to the score improved the accuracy of the prediction by only <1%. Using the same variables, we developed a liver fat equation from which liver fat percentage of each individual could be estimated. CONCLUSIONS: The NAFLD liver fat score and liver fat equation provide simple and noninvasive tools to predict NAFLD and liver fat content.

Genetic variation in the ADIPOR2 gene is associated with liver fat content and its surrogate markers in three independent cohorts.

AIMS: We investigated whether polymorphisms in candidate genes involved in lipid metabolism and type 2 diabetes are related to liver fat content. METHODS: Liver fat content was measured using proton magnetic resonance spectroscopy ((1)H-MRS) in 302 Finns, in whom single nucleotide polymorphisms (SNPs) in acyl-CoA synthetase long-chain family member 4 (ACSL4), adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2), and the three peroxisome proliferator-activated receptors (PPARA, PPARD, and PPARG) were analyzed. To validate our findings, SNPs significantly associated with liver fat content were studied in two independent cohorts and related to surrogate markers of liver fat content. RESULTS: In the Finnish subjects, polymorphisms in ACSL4 (rs7887981), ADIPOR2 (rs767870), and PPARG (rs3856806) were significantly associated with liver fat content measured with (1)H-MRS after adjusting for age, gender, and BMI. Anthropometric and circulating parameters were comparable between genotypes. In the first validation cohort of approximately 600 Swedish men, ACSL4 rs7887981 was related to fasting insulin and triglyceride concentrations, and ADIPOR2 rs767870 to serum gamma glutamyltransferase concentrations after adjusting for BMI. The SNP in PPARG (rs3856806) was not significantly associated with any relevant metabolic parameter in this cohort. In the second validation cohort of approximately 3000 subjects from Western Finland, ADIPOR2 rs767870, but not ACSL4 rs7887981 was related to fasting triglyceride concentrations. CONCLUSIONS: Genetic variation, particularly in the ADIPOR2 gene, contributes to variation in hepatic fat accumulation in humans.

Congruence between NOTCH3 mutations and GOM in 131 CADASIL patients.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary subcortical vascular dementia. It is caused by mutations in NOTCH3 gene, which encodes a large transmembrane receptor Notch3. The key pathological finding is the accumulation of granular osmiophilic material (GOM), which contains extracellular domains of Notch3, on degenerating vascular smooth muscle cells (VSMCs). GOM has been considered specifically diagnostic for CADASIL, but the reports on the sensitivity of detecting GOM in patients' skin biopsy have been contradictory. To solve this contradiction, we performed a retrospective investigation of 131 Finnish, Swedish and French CADASIL patients, who had been adequately examined for both NOTCH3 mutation and presence of GOM. The patients were examined according to the diagnostic practice in each country. NOTCH3 mutations were assessed by restriction enzyme analysis of specific mutations or by sequence analysis. Presence of GOM was examined by electron microscopy (EM) in skin biopsies. Biopsies of 26 mutation-negative relatives from CADASIL families served as the controls. GOM was detected in all 131 mutation positive patients. Altogether our patients had 34 different pathogenic mutations which included three novel point mutations (p.Cys67Ser, p.Cys251Tyr and p.Tyr1069Cys) and a novel duplication (p.Glu434_Leu436dup). The detection of GOM by EM in skin biopsies was a highly reliable diagnostic method: in this cohort the congruence between NOTCH3 mutations and presence of GOM was 100%. However, due to the retrospective nature of this study, exact figure for sensitivity cannot be determined, but it would require a prospective study to exclude possible selection bias. The identification of a pathogenic NOTCH3 mutation is an indisputable evidence for CADASIL, but demonstration of GOM provides a cost-effective guide for estimating how far one should proceed with the extensive search for a new or an uncommon mutations among the presently known over 170 different NOTCH3 gene defects. The diagnostic skin biopsy should include the border zone between deep dermis and upper subcutis, where small arterial vessels of correct size are located. Detection of GOM requires technically adequate biopsies and distinction of true GOM from fallacious deposits. If GOM is not found in the first vessel or biopsy, other vessels or additional biopsies should be examined.

Liver fat is increased in type 2 diabetic patients and underestimated by serum alanine aminotransferase compared with equally obese nondiabetic subjects.

OBJECTIVE: The purpose of this study was to determine whether type 2 diabetic patients have more liver fat than age-, sex-, and BMI-matched nondiabetic subjects and whether liver enzymes (serum alanine aminotransferase [S-ALT] and serum aspartate aminotransferase) are similarly related to liver fat in type 2 diabetic patients and normal subjects. RESEARCH DESIGN AND METHODS: Seventy type 2 diabetic patients and 70 nondiabetic subjects matched for BMI, age, and sex were studied. Liver fat ((1)H-magnetic resonance spectroscopy), body composition (magnetic resonance imaging), and biochemical markers of insulin resistance were measured. RESULTS: The type 2 diabetic patients had, on average, 80% more liver fat and 16% more intra-abdominal fat than the nondiabetic subjects. The difference in liver fat between the two groups remained statistically significant when adjusted for intra-abdominal fat (P < 0.05). At any given BMI or waist circumference, the type 2 diabetic patients had more liver fat than the nondiabetic subjects. The difference in liver fat between the groups rose as a function of BMI and waist circumference. Fasting serum insulin (r = 0.55, P < 0.0001), fasting plasma glucose (r = 0.29, P = 0.0006), A1C (r = 0.34, P < 0.0001), fasting serum triglycerides (r = 0.36, P < 0.0001), and fasting serum HDL cholesterol (r = -0.31, P = 0.0002) correlated with liver fat similarly in both groups. The slopes of the relationships between S-ALT and liver fat were significantly different (P = 0.004). Liver fat content did not differ between the groups at low S-ALT concentrations (10-20 units/l) but was 70-200% higher in type 2 diabetic patients compared with control subjects at S-ALT concentrations of 50-200 units/l. CONCLUSIONS: Type 2 diabetic patients have 80% more liver fat than age-, weight-, and sex-matched nondiabetic subjects. S-ALT underestimates liver fat in type 2 diabetic patients.

Effect of liver fat on insulin clearance.

A fatty liver is associated with fasting hyperinsulinemia, which could reflect either impaired insulin clearance or hepatic insulin action. We determined the effect of liver fat on insulin clearance and hepatic insulin sensitivity in 80 nondiabetic subjects [age 43 +/- 1 yr, body mass index (BMI) 26.3 +/- 0.5 kg/m(2)]. Insulin clearance and hepatic insulin resistance were measured by the euglycemic hyperinsulinemic (insulin infusion rate 0.3 mU.kg(-1).min(-1) for 240 min) clamp technique combined with the infusion of [3-(3)H]glucose and liver fat by proton magnetic resonance spectroscopy. During hyperinsulinemia, both serum insulin concentrations and increments above basal remained approximately 40% higher (P < 0.0001) in the high (15.0 +/- 1.5%) compared with the low (1.8 +/- 0.2%) liver fat group, independent of age, sex, and BMI. Insulin clearance (ml.kg fat free mass(-1).min(-1)) was inversely related to liver fat content (r = -0.52, P < 0.0001), independent of age, sex, and BMI (r = -0.37, P = 0.001). The variation in insulin clearance due to that in liver fat (range 0-41%) explained on the average 27% of the variation in fasting serum (fS)-insulin concentrations. The contribution of impaired insulin clearance to fS-insulin concentrations increased as a function of liver fat. This implies that indirect indexes of insulin sensitivity, such as homeostatic model assessment, overestimate insulin resistance in subjects with high liver fat content. Liver fat content correlated significantly with fS-insulin concentrations adjusted for insulin clearance (r = 0.43, P < 0.0001) and with directly measured hepatic insulin sensitivity (r = -0.40, P = 0.0002). We conclude that increased liver fat is associated with both impaired insulin clearance and hepatic insulin resistance. Hepatic insulin sensitivity associates with liver fat content, independent of insulin clearance.

Adipose tissue inflammation and increased ceramide content characterize subjects with high liver fat content independent of obesity.

OBJECTIVE: We sought to determine whether adipose tissue is inflamed in individuals with increased liver fat (LFAT) independently of obesity. RESEARCH DESIGN AND METHODS: A total of 20 nondiabetic, healthy, obese women were divided into normal and high LFAT groups based on their median LFAT level (2.3 +/- 0.3 vs. 14.4 +/- 2.9%). Surgical subcutaneous adipose tissue biopsies were studied using quantitative PCR, immunohistochemistry, and a lipidomics approach to search for putative mediators of insulin resistance and inflammation. The groups were matched for age and BMI. The high LFAT group had increased insulin (P = 0.0025) and lower HDL cholesterol (P = 0.02) concentrations. RESULTS: Expression levels of the macrophage marker CD68, the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha, and plasminogen activator inhibitor-1 were significantly increased, and those of peroxisome proliferator-activated receptor-gamma and adiponectin decreased in the high LFAT group. CD68 expression correlated with the number of macrophages and crown-like structures (multiple macrophages fused around dead adipocytes). Concentrations of 154 lipid species in adipose tissue revealed several differences between the groups, with the most striking being increased concentrations of triacylglycerols, particularly long chain, and ceramides, specifically Cer(d18:1/24:1) (P = 0.01), in the high LFAT group. Expression of sphingomyelinases SMPD1 and SMPD3 were also significantly increased in the high compared with normal LFAT group. CONCLUSIONS: Adipose tissue is infiltrated with macrophages, and its content of long-chain triacylglycerols and ceramides is increased in subjects with increased LFAT compared with equally obese subjects with normal LFAT content. Ceramides or their metabolites could contribute to adverse effects of long-chain fatty acids on insulin resistance and inflammation.

Exploring the lipoprotein composition using Bayesian regression on serum lipidomic profiles.

MOTIVATION: Serum lipids have been traditionally studied in the context of lipoprotein particles. Today's emerging lipidomics technologies afford sensitive detection of individual lipid molecular species, i.e. to a much greater detail than the scale of lipoproteins. However, such global serum lipidomic profiles do not inherently contain any information on where the detected lipid species are coming from. Since it is too laborious and time consuming to routinely perform serum fractionation and lipidomics analysis on each lipoprotein fraction separately, this presents a challenge for the interpretation of lipidomic profile data. An exciting and medically important new bioinformatics challenge today is therefore how to build on extensive knowledge of lipid metabolism at lipoprotein levels in order to develop better models and bioinformatics tools based on high-dimensional lipidomic data becoming available today. RESULTS: We developed a hierarchical Bayesian regression model to study lipidomic profiles in serum and in different lipoprotein classes. As a background data for the model building, we utilized lipidomic data for each of the lipoprotein fractions from 5 subjects with metabolic syndrome and 12 healthy controls. We clustered the lipid profiles and applied a regression model within each cluster separately. We found that the amount of a lipid in serum can be adequately described by the amounts of lipids in the lipoprotein classes. In addition to improved ability to interpret lipidomic data, we expect that our approach will also facilitate dynamic modelling of lipid metabolism at the individual molecular species level.

Liver fat in the metabolic syndrome.

BACKGROUND: The liver, once fatty, overproduces components of the metabolic syndrome, such as glucose and lipids. The amount of liver fat in subjects with and without the metabolic syndrome has not been determined. It is unknown which clinically available markers best reflect liver fat content. MEASUREMENTS: Components of the metabolic syndrome as defined by the International Diabetes Federation and liver fat content by proton magnetic resonance spectroscopy were measured in 271 nondiabetic subjects (162 women, 109 men). In addition, other features of insulin resistance (serum insulin, C-peptide), intraabdominal and sc fat by magnetic resonance imaging, and liver enzymes (serum alanine aminotransferase and serum aspartate aminotransferase) were measured. RESULTS: Liver fat was 4-fold higher in subjects with [n = 116; median 8.2% (interquartile range 3.2-18.7%)] than without [n = 155; 2.0% (1.0-5.0%); P < 0.0001] the metabolic syndrome. This increase in liver fat remained significant after adjusting for age, gender, and body mass index. All components of the metabolic syndrome correlated with liver fat content. The best correlate was waist in both women (r = 0.59, P < 0.0001) and men (r = 0.56, P < 0.0001). Liver fat correlated significantly with serum alanine aminotransferase (r = 0.39, P < 0.0001 for women; r = 0.44, P < 0.0001 for men) and aspartate aminotransferase (r = 0.27, P = 0.0005 for women; r = 0.31, P = 0.0012 for men) concentrations. The best correlates of liver fat were fasting serum insulin (r = 0.61; P < 0.0001 for both women and men) and C-peptide (r = 0.62; P < 0.0001 for both women and men). CONCLUSIONS: Liver fat content is significantly increased in subjects with the metabolic syndrome as compared with those without the syndrome, independently of age, gender, and body mass index. Of other markers, serum C-peptide is the strongest correlate of liver fat.

Effects of acquired obesity on endothelial function in monozygotic twins.

OBJECTIVE: To determine whether acquired obesity or accompanying metabolic changes such as adiponectin deficiency, insulin resistance, dyslipidemia, or visceral fat are associated, independent of genetic influences, with endothelial dysfunction by studying young adult monozygotic (MZ) twin pairs discordant for obesity. RESEARCH METHODS AND PROCEDURES: Nine obesity-discordant (intra-pair difference in BMI, 3.8 to 10.1 kg/m(2)) and nine concordant (0 to 2.3 kg/m(2)) 24- to 27-year-old MZ twin pairs were identified from a population-based FinnTwin16-sample. Endothelial function was measured by blood flow responses to intrabrachial infusions of an endothelium-dependent (acetylcholine) and an endothelium-independent (sodium nitroprusside) vasodilator. Whole body insulin sensitivity was measured using the euglycemic insulin clamp technique, and forearm and body composition were measured with magnetic resonance imaging and DXA. In addition, serum levels of adiponectin, high-sensitivity C-reactive protein, and lipids were determined. RESULTS: The heavier co-twins of the discordant pairs had significantly lower whole body insulin sensitivity than the leaner co-twins. Blood flows/muscle volume during infusions of acetylcholine and sodium nitroprusside were not altered by obesity. However, intra-pair differences in serum adiponectin, intra-abdominal fat, and C-reactive protein were significantly correlated with those in endothelial function. Only the relationship between intra-pair differences in adiponectin and endothelial function persisted in multiple linear regression analysis. Obesity-concordant co-twins had comparable insulin sensitivity and endothelial function. DISCUSSION: In young adult MZ twins discordant for obesity, acquired adiponectin deficiency rather than obesity per se is an independent correlate of endothelial dysfunction.

Glycodelin responses to hyperinsulinaemic clamp vary according to basal serum glycodelin concentration.

OBJECTIVE: Treatment with metformin, an insulin-lowering agent, increases serum glycodelin, a progesterone-regulated lipocalin protein of the reproductive axis that may play a role in foeto-maternal defence mechanisms. This finding led to the hypothesis that insulin might decrease serum glycodelin concentration. DESIGN, PATIENTS AND MEASUREMENTS: Euglycaemic hyperinsulinaemic clamp experiments (n = 50) were carried out on 28 women of reproductive age (range 25-47 years; mean +/- SEM 39 +/- 1.0 years), and the results were analysed with respect to their baseline serum progesterone (< 10 or > or = 10 nmol/l) and glycodelin (< 10 or > or = 10 microg/l, equivalent to < 357 or > or = 357 pmol/l) concentrations at the onset of the clamp. Ten clamp experiments were performed on five women wearing a levonorgestrel-releasing intrauterine device (IUD), and these were analysed as a separate group. RESULTS: Contrary to the hypothesis, no acute glycodelin-lowering effect of insulin was found in any of the groups studied. All the small rises in glycodelin levels detected during acute hyperinsulinaemia occurred in the comparisons of medians and not means, and all such changes took place within the limits seen in the women with no progesterone exposure. In the group with low progesterone/low glycodelin (n = 21), glycodelin showed a small but significant increase at 30 and 90 min of the clamp (P < 0.01). In the group with elevated progesterone/low glycodelin (n = 11), there was a slight glycodelin increase at 30 min (P < 0.05), whereas no increase was found in the group with elevated glycodelin levels (n = 8). In the clamp experiments on women with levonorgestrel-releasing IUD, the basal glycodelin level was low in all cases and, as in the other women with low glycodelin levels, glycodelin was slightly increased at 30, 60 and 90 min of hyperinsulinaemia (P < 0.01). CONCLUSIONS: The results rule out any acute glycodelin-reducing effects of insulin, although indirect long-term effects mediated by insulin on glycodelin secretion cannot be excluded.

Glargine and regular human insulin similarly acutely enhance endothelium-dependent vasodilatation in normal subjects.

OBJECTIVE: Human insulin enhances the vasodilatory effect of acetylcholine (ACh), an endothelium-dependent vasodilator, in normal subjects. Structural changes in a long-acting insulin analog, insulin glargine, may change its binding properties to insulin receptor and structurally homologous receptors, such as the insulin-like growth factor-1 receptor, and thereby alter its vascular effects. In the present study, we compared effects of glargine and regular human insulin on blood flow responses to endothelium-dependent and endothelium-independent vasoactive agents in vivo in normal subjects. METHODS AND RESULTS: Ten healthy men (age: 33+/-9 years [mean+/-SD]; BMI: 23+/-2 kg/m2) were studied on two separate occasions in a double-blind, randomized, crossover fashion. In each study, blood flow responses to intrabrachial artery infusions of ACh and SNP were determined during infusion of saline and intravenously maintained normoglycemic hyperinsulinemia. Hyperinsulinemia (120 minutes; infusion rate: 1 mU/kg per minute) was created by infusing either insulin glargine or human regular insulin. Glargine and human regular insulin similarly stimulated whole-body glucose metabolism and suppressed serum free-fatty acid (FFA) concentrations. Endothelium-independent blood flow responses to low (3 microg/min) and high (10 microg/min) doses of SNP were unaffected by insulin glargine (12.2+/-2.6 versus 13.4+/-4.6 and 19.1+/-4.2 versus 19.6+/-5.1 mL/dL per minute, saline versus insulin, low- and high-dose) and regular human insulin (11.2+/-3.4 versus 12.0+/-5.2 and 16.8+/-5.7 versus 18.4+/-7.7 mL/dL per minute, respectively). In contrast, endothelium-dependent blood flow responses to low (7.5 microg/min) and high (15 microg/min) doses of ACh increased significantly and similarly by insulin glargine, 13.9+/-4.8 versus 19.3+/-6.5 mL/dL per minute (saline versus insulin, +39%, P<0.01) for low-dose ACh and 17.3+/-6.3 versus 23.2+/-9.2 mL/dL per minute (+34%; P<0.02) for high-dose ACh, and regular human insulin, 11.5+/-6.0 versus 15.8+/-8.0 mL/dL per minute (+38%; P<0.05) and 14.0+/-7.5 versus 21.1+/-10.4 mL/dL per minute (+51%; P<0.01). CONCLUSIONS: Insulin glargine and regular human insulin have similar acute stimulatory effects on endothelium-dependent vasodilation in humans.

Effects of equal weight loss with orlistat and placebo on body fat and serum fatty acid composition and insulin resistance in obese women.

BACKGROUND: Dietary fat has been reported to influence insulin sensitivity. OBJECTIVE: The objective of the study was to determine how identical weight loss (target: loss of 8% of body weight over 3-6 mo) in women taking orlistat or placebo combined with a hypocaloric diet influences body composition and insulin sensitivity. DESIGN: Forty-seven obese women [body mass index (in kg/m(2)): 32.1 +/- 0.4] were randomly assigned to receive either orlistat (120 mg 3 times daily; n = 23) or placebo (n = 24) with a hypocaloric diet. Whole-body insulin sensitivity (insulin clamp technique), serum fatty acids, and body composition (magnetic resonance imaging) were measured before and after weight loss. RESULTS: The groups did not differ significantly at baseline with respect to age, body weight, intraabdominal and subcutaneous fat volumes, or insulin sensitivity. Weight loss did not differ significantly between the orlistat (7.3 +/- 0.2 kg, or 8.3 +/- 0.1%) and placebo (7.4 +/- 0.2 kg, or 8.2 +/- 0.1%) groups. Insulin sensitivity improved significantly (P < 0.001) and similarly after weight loss in the orlistat (from 4.0 +/- 0.3 to 5.1 +/- 0.3 mg x kg fat-free mass(-1) x min(-1)) and placebo (from 4.4 +/- 0.4 to 5.4 +/- 0.4 mg x kg fat-free mass(-1) x min(-1)) groups. Intraabdominal fat and subcutaneous fat decreased significantly in both groups, but the ratio of the 2 decreased significantly only in the orlistat group. The proportion of dihomo-gamma-linolenic acid (20:3n-6) in serum phospholipids was inversely related to insulin sensitivity both before (r = -0.48, P < 0.001) and after (r = -0.46, P < 0.001) weight loss, but it did not change significantly in either group. CONCLUSIONS: Weight loss rather than inhibition of fat absorption enhances insulin sensitivity. A decrease in fat absorption by orlistat appears to favorably influence the ratio between intraabdominal and subcutaneous fat, which suggests that exogenous fat or its composition influences fat distribution.

Lowering of LDL cholesterol rather than moderate weight loss improves endothelium-dependent vasodilatation in obese women with previous gestational diabetes.

OBJECTIVE: Effects of weight loss on vascular function are unknown. We compared, in the face of similar weight loss over 3-6 months, effects of orlistat (120 mg t.i.d., n = 23) and placebo (n = 24) on in vivo endothelial function in a high-risk group of obese (BMI 32.1 +/- 0.4 kg/m(2)) premenopausal nondiabetic women with a history of gestational diabetes. RESEARCH DESIGN AND METHODS: Forearm blood flow responses to intra-arterial infusions of acetylcholine (ACh) and sodium nitroprusside (SNP), body composition, and serum lipids were determined before and after weight loss. RESULTS: Weight loss averaged 7.3 +/- 0.2 kg (8.3 +/- 0.1%) and 7.4 +/- 0.2 kg (8.2 +/- 0.1%) of initial body weight in the orlistat and placebo groups, respectively. Forearm and body compositions changed similarly in both groups. Responses to ACh increased by 41% to the low dose (5.9 +/- 0.6 vs. 8.3 +/- 0.3 for flow in the experimental/control arm, P < 0.01) and by 33% to the high dose (7.6 +/- 0.8 vs. 10.1 +/- 0.6, P < 0.001) in the orlistat group, but they remained unchanged in the placebo group. The blood flow responses to SNP did not differ significantly between the groups. LDL cholesterol decreased significantly in the orlistat group from 3.5 +/- 0.2 to 3.0 +/- 0.1 mmol/l (P < 0.01) but remained unchanged in the placebo group. Within the orlistat group, the decrease in LDL cholesterol correlated significantly with the improvement in the blood flow response to ACh (r = -0.44, P < 0.05). CONCLUSIONS: Orlistat but not moderate (8%) weight loss per se improves endothelial function in women with previous gestational diabetes. This improvement is associated with a lowering of LDL cholesterol by orlistat.

Effects of identical weight loss on body composition and features of insulin resistance in obese women with high and low liver fat content.

Our objective was to determine how 8% weight loss influences subcutaneous, intra-abdominal, and liver fat (LFAT), as well as features of insulin resistance, in obese women with high versus low LFAT. A total of 23 women with previous gestational diabetes were divided into groups of high (9.4 +/- 1.4%) and low (3.3 +/- 0.4%) LFAT based on their median LFAT (5%) measured with proton spectroscopy. Both groups were similar with respect to age, BMI, and intra-abdominal and subcutaneous fat. Before weight loss, women with high LFAT had higher fasting serum insulin and triglyceride concentrations than women with low LFAT. At baseline, LFAT correlated with the percent of fat (r = 0.44, P < 0.05) and saturated fat (r = 0.45, P < 0.05) of total caloric intake but not intra-abdominal or subcutaneous fat or fasting serum free fatty acids. Weight loss was similar between the groups (high LFAT -7.4 +/- 0.2 vs. low LFAT -7.7 +/- 0.3 kg). LFAT decreased from 9.4 +/- 1.4 to 4.8 +/- 0.7% (P < 0.001) in women with high LFAT and from 3.3 +/- 0.4 to 2.0 +/- 0.2% (P < 0.001) in women with low LFAT. The absolute decrease in LFAT was significantly higher in women with high than low LFAT (-4.6 +/- 1.0 vs. -1.3 +/- 0.3%, P < 0.005). The decrease in LFAT was closely correlated with baseline LFAT (r = -0.85, P < 0.001) but not with changes in the volumes of intra-abdominal or subcutaneous fat depots, which decreased similarly in both groups. LFAT appears to be related to the amount of fat in the diet rather than the size of endogenous fat depots in obese women. Women with initially high LFAT lost more LFAT by similar weight loss than those with low LFAT, although both groups lost similar amounts of subcutaneous and intra-abdominal fat. These data suggest that LFAT is regulated by factors other than intra-abdominal and subcutaneous fat. Therefore, LFAT does not appear to simply reflect the size of endogenous fat stores.

Impaired responsiveness to NO in newly diagnosed patients with rheumatoid arthritis.

OBJECTIVE: Cardiovascular disease is the major cause of excessive mortality in patients with rheumatoid arthritis (RA). We determined whether endothelial dysfunction characterizes patients with newly diagnosed RA (n=10) compared with normal subjects (control group, n=33) and whether it is reversible with 6 months of anti-inflammatory therapy. METHODS AND RESULTS: Endothelial function was determined by measuring vasodilatory responses to intrabrachial artery infusions of acetylcholine (ACh at 7.5 and 15 microg/min, low and high dose, respectively), an endothelium-dependent vasodilator, and to sodium nitroprusside (SNP, 3 and 10 micro g/min), an endothelium-independent vasodilator. Before treatment, blood flow responses (fold increase in flow) to low-dose SNP were 30% lower in the RA versus the control group (4.1+/-0.4-fold versus 5.9+/-0.5-fold, respectively), and responses to high-dose SNP were 34% lower in the RA group versus the control group (5.1+/-0.6-fold versus 7.7+/-0.7-fold, respectively; P<0.001). The responses to low-dose ACh were 50% lower in the RA group versus the control group (3.0+/-0.5-fold versus 6.6+/-0.7-fold, respectively), and responses to high-dose ACh were 37% lower in the RA group versus the control group (5.0+/-0.4-fold versus 7.9+/-0.8-fold, respectively; P<0.001). After therapy, clinical and laboratory markers of inflammation had significantly decreased. Blood flow responses to ACh increased significantly (P=0.02). CONCLUSIONS: We conclude that newly diagnosed patients with RA have vascular dysfunction, which is reversible with successful therapy. Therefore, early suppression of inflammatory activity may reduce long-term vascular damage.

Liver-fat accumulation and insulin resistance in obese women with previous gestational diabetes.

OBJECTIVE: We determined whether fat accumulation in the liver is associated with features of insulin resistance independent of obesity. RESEARCH METHODS AND PROCEDURES: We recruited 27 obese nondiabetic women in whom liver fat (LFAT) content was determined by proton spectroscopy, intra-abdominal and subcutaneous fat by magnetic resonance imaging, and insulin sensitivity by the euglycemic insulin clamp technique. The women were divided based on their median LFAT content (5%) to groups with low (3.2 +/- 0.3%) and high (9.8 +/- 1.5%) liver fat. The groups were almost identical with respect to age (36 +/- 1 vs. 38 +/- 1 years in low vs. high-LFAT), body mass index (32.2 +/- 0.6 vs. 32.8 +/- 0.5 kg/m(2)), waist-to-hip ratio, intra-abdominal, subcutaneous, and total fat content. RESULTS: Women with high LFAT had features of insulin resistance including higher fasting serum triglyceride (1.93 +/- 0.21 vs. 1.11 +/- 0.09 mM, p < 0.01) and insulin (14 +/- 3 vs. 10 +/- 1 mU/L, p < 0.05) concentrations than women with low LFAT. The group with high LFAT also had higher 24-hour blood pressures, and lower whole-body insulin sensitivity compared with the low-LFAT group. DISCUSSION: In obese women with previous gestational diabetes, LFAT, rather than any measure of body composition, is associated with features of insulin resistance.