In vitro studies revealed that insulin resistance might be associated with the intracellular formation of ceramide, the second messenger in the sphingomyelin signaling pathway. The aim of the present study was to examine the content and composition of fatty acids in ceramide and sphingomyelin in human muscle and to evaluate their relationships with insulin sensitivity. The study was conducted on 27 male subjects with normal glucose tolerance. Euglycemic-hyperinsulinemic clamps and biopsies of vastus lateralis muscle were performed. In 10 subjects, additional biopsies were taken after a 4-h clamp and after a clamp with concurrent Intralipid/ heparin infusion. We identified 13 ceramides and sphingomyelins according to fatty acid residues. Insulin sensitivity was related to total ceramide content (r ‫؍‬ ؊0.49, P ‫؍‬ 0.01) and to ceramide consisting of palmitic (r ‫؍‬ ؊0.48, P ‫؍‬ 0.011), palmitoleic (r ‫؍‬ ؊0.45, P ‫؍‬ 0.019), mirystic (r ‫؍‬ ؊0.42, P ‫؍‬ 0.028), and nervonic acid (r ‫؍‬ ؊0.39, P ‫؍‬ 0.047). Hyperinsulinemia did not affect estimated muscle parameters. Intralipid/heparin infusion resulted in a 24.73% decrease in insulin sensitivity (P ‫؍‬ 0.007) and a 47.81% increase in ceramide content (P ‫؍‬ 0.005). These changes were significantly related to each other (r ‫؍‬ ؊0.64, P ‫؍‬ 0.046). A relationship with the decrease in insulin sensitivity was also observed for ceramides consisting of palmitic (r ‫؍‬ ؊0.68, P ‫؍‬ 0.03) and linoleic (r ‫؍‬ ؊0.66, P ‫؍‬ 0.038) acid. Our data indicate that the sphingomyelin signaling pathway in muscle might be an important factor determining the development of insulin resistance in humans.

Obesity is associated with the increased risk of cardiovascular disease; however, mechanisms responsible for such an increase are not fully understood. IL-8 is a cytokine that might have atherogenic properties. Recent in vitro studies revealed that IL-8 is produced and secreted by human adipocytes. The aim of the present study was to evaluate plasma IL-8 concentrations in obese subjects and the relationships between circulating IL-8 and anthropometric and biochemical parameters and TNF-alpha system. A total of 75 subjects with normal glucose tolerance, 35 lean and 40 obese, were recruited for this study. Plasma IL-8 levels were measured in fasting state, after an oral glucose tolerance test and after the euglycemic hyperinsulinemic clamp. A significant increase in plasma IL-8 was observed in the obese group. In simple regression analysis, performed for the initial evaluation of relationships, plasma IL-8 was related to body mass index, percentage of body fat, fat mass (FM), and soluble TNF-alpha receptor 2 (sTNFR2) in both groups and with waist-to-hip ratio and sTNFR1 in the obese. In multiple regression analysis, FM, waist-to-hip ratio, gender, sTNFR2, and low density lipoprotein cholesterol were responsible for 44% of IL-8 variability. During oral glucose tolerance testing, mean plasma IL-8 concentrations increased in both groups, whereas clamp resulted in a significant increase in plasma IL-8 only in the obese. We conclude that plasma IL-8 levels are increased in obese subjects, and are related to FM and TNF-alpha system. Increase in circulating IL-8 might be one of the factors linking obesity with greater cardiovascular risk.

Abstract. Diabetic nephropathy may be effectively prevented and treated by controlling glycemia and administering angiotensinconverting enzyme (ACE) inhibitors. However, strict metabolic control can be difficult, and ACE inhibitors may be poorly tolerated and only partially effective, particularly in diabetes mellitus type 2 (DM2), warranting the search for ancillary treatment. Sulodexide is a glycosaminoglycan, a new class of drug that has demonstrated nephroprotective activity in experimental investigations. The Di.N.A.S. study was a randomized, double-blind, placebo-controlled, multicenter, dose-range finding trial to evaluate the extent and duration of the hypoalbuminuric effect of oral sulodexide in diabetic patients. A total of 223 microalbuminuric and macroalbuminuric DM1 and DM2 patients with serum creatinine Յ150 mol/L and stable BP and metabolic control were recruited. They were randomly allocated to one of four groups: 50 mg/d, 100 mg/d, or 200 mg/d sulodexide daily or placebo for 4 mo (T0 to T4), with 4 mo of follow-up after drug suspension (T4 to T8). Treatment with 200 mg/d sulodexide for 4 mo significantly reduced log albumin excretion rate (logAER) from 5.25 Ϯ 0.18 at T0 to 3.98 Ϯ 0.11 at T4 (P Ͻ 0.05), which was maintained till T8 (4.11 Ϯ 0.13; P Ͻ 0.05 versus T0). Moreover, the sulodexideinduced percent reductions in AER at T4 were significantly different from the placebo value at T4 and approximately linear to dose increments (30% [confidence limits, 4 to 49%], P ϭ 0.03; 49% [30 to 63%], P ϭ 0.0001; and 74% [64 to 81%], P ϭ 0.0001 in the sulodexide 50, 100, and 200 mg/d groups, respectively. At T8, the sulodexide 200 mg/d group maintained a 62% (45 to 73%) AER significant reduction versus placebo (P ϭ 0.0001). Subanalysis by type of diabetes (DM1 versus DM2, microalbuminuric versus macroalbuminuric, or on concomitant ACE inhibitors versus not on ACE inhibitors) demonstrated similar findings. These effects were obtained without any significant variation in metabolic control and BP or serum creatinine. Very few adverse events were reported; none were serious. In conclusion, a 4-mo course of high doses of sulodexide significantly and dose-dependently improves albuminuria in DM1 and DM2 patients and micro-or macroalbuminuric patients with or without concomitant ACE inhibition. The effect on albuminuria is long-lasting and seemingly additive to the ACE inhibitory effect.Diabetes is the most common cause of end-stage renal disease (ESRD) in Western countries. In the United States, diabetes currently accounts for 44% of all new cases of ESRD (1). Despite advances in clinical care, the incidence of diabetes mellitus type 2 (DM2)-related cases of ESRD is rapidly increasing (2), and survival of DM-related ESRD patients on dialysis is markedly low (3,4).The anatomic hallmarks of diabetic nephropathy (DN) include thickening of the glomerular basement membrane (GBM) and mesangial expansion with hyalinosis both in the mesangium and capillary lumen. These lesions lead to glomerular fibrosis, which progressiv...

Type 1 diabetes is believed to be a Th1 lymphocyte-mediated disease, and both environmental and genetic factors play a role in its pathogenesis. It was recently found that interleukin (IL)-18 acts as a proinflammatory cytokine and, in synergy with IL-12, promotes development of Th1 lymphocyte response by induction of gamma-interferon production. The aim of our study was to evaluate the frequency of known polymorphisms in the IL-18 promoter in patients with type 1 diabetes in comparison with healthy control subjects, since higher levels of IL-18 were recently reported in the subclinical stage of type 1 diabetes. We studied two recently described single-nucleotide polymorphisms of the promoter of IL-18 gene at the position -137 and -607, which have been suggested to cause differences in transcription factor binding and have an impact on IL-18 gene activity. The genotype distribution differed significantly between patients with type 1 diabetes and control subjects. The difference reflected an increase in the GC genotypes and a decrease in GG genotypes at position -137 in the promoter of IL-18 gene. AA genotype at position -607 was found only in the control group. The results also demonstrated that the contribution of -137GC genotypes to genetic susceptibility to type 1 diabetes differs depending on the combination of IL-18 promotor gene haplotypes. Our study suggests the first evidence of an association between type 1 diabetes and polymorphisms in the promoter of IL-18 gene.

Plasma concentrations of adiponectin, tumor necrosis factor-alpha (TNF-alpha) and its soluble receptors sTNFR-1 and sTNFR-2 were measured in 80 patients with gestational diabetes (GDM) (mean age 29.0 +/- 4.9 years) and 30 pregnant women with normal glucose tolerance (NGT) (mean age 28.2 +/- 6.0 years). We found that GDM patients had significantly lower concentrations of adiponectin (11.28 +/- 5.91 vs. 16.31 +/- 6.04 microg/ml, p = 0.00009) and elevated levels of TNF-alpha (1.71 +/- 0.92 vs. 1.27 +/- 0.42 pg/ml, p = 0.0175) in comparison to NGT women. The differences remained statistically significant after adjusting for BMI. Plasma levels of sTNFR-1 and sTNFR-2 also tended to be higher in GDM patients. In the GDM group TNF-alpha concentrations correlated significantly with sTNFR-1 (r = 0.444, p = 0.00008), sTNFR-2 (r = 0.364, p = 0.0016) and with C-peptide concentrations (r = 0.318, p = 0.016), whereas in women with NGT TNF-alpha correlated only with TG levels (r = 0.50, p = 0.024). Multivariate linear regression analysis revealed that prepregnant BMI was the most predictive indicator of TNF-alpha concentrations in GDM women. TG concentrations as well as BMI before pregnancy and at the time of sampling in pregnant NGT women were significant predictors, explaining 62% of the variance in TNF-alpha concentration. There were also negative correlations between adiponectin concentrations and a pregestational BMI (r = - 0.298, p = 0.009), BMI at the time of sampling (r = - 0.239, p = 0.034) and TG concentrations (r = - 0.379, p = 0.039) in GDM patients, whereas women with NGT showed only a negative correlation between adiponectin and TG concentrations (r = - 0.488, p = 0.025). In a multivariate regression analysis, prepregnancy BMI and TG levels remained significant predictors, explaining 39% of the variation in plasma adiponectin concentration in GDM women. In conclusion, our results suggest that decreased adiponectin concentration in GDM may not simply reflect maternal adiposity and insulin resistant state, but may contribute to the impaired glucose metabolism during pregnancy, with potential implications for screening and prevention of the disease.

The aim of this study was to evaluate lipid peroxidation and scavenging enzyme activity in streptozotocin-induced diabetes, and then to establish whether moderate doses of nonenzymatic antioxidant vitamin E play a role in the antioxidant defence system in diabetic pregnant rats and their offspring. The study group consisted of 30 normal female Wistar rats, which were given a single dose of streptozotocin (40 mg/kg) and were mated 7 days later. Subsequently, the diabetic animals were divided into two matched groups: the first supplemented with vitamin E (30 mg/100 g chow), and the other fed with a standard diet lacking vitamin E. Controls consisted of 15 pregnant rats. On the first day after delivery, the rats were decapitated and homogenates of maternal liver and uterus as well as neonatal lungs and liver were prepared. Then the following parameters were measured: malondialdehyde (MDA) concentrations in the homogenates and blood serum, glutathione (GSH) levels, the activity of CuZn-superoxide dismutase (SOD) and glutathione peroxidase (GPx), and glycaemia. The neonates of diabetic rats were smaller than the healthy ones and serum glucose concentration was markedly higher in the diabetic animals. MDA levels were significantly increased, whereas GSH, SOD and GPx were markedly diminished in the diabetic adult rats and their offspring in comparison to the control group. In the animals supplemented with alpha-tocopherol, MDA concentrations were significantly lower, GSH content and SOD activities were markedly elevated most tissues studied, whereas GPx remained unchanged. We conclude that, by monitoring the activity of selected scavenging enzymes, information on ongoing biological oxidative stress and thereby on the fetus/neonate status may be obtained. Our results suggest that diabetic pregnant rats and their neonates are exposed to an increased oxidative stress and that vitamin E supplementation may reduce its detrimental effects.

Objective: Tumor necrosis factor-a (TNFa) plays an important role in the pathogenesis of insulin resistance and type 2 diabetes. Plasma levels of the soluble (s) fractions of TNFa receptors, especially sTNFR2, are good indicators of TNFa system activation in obesity. The aim of the present study was to assess the effect of exercise training on the TNFa system and to evaluate the relationship with changes in insulin sensitivity. Design and methods: Sixteen obese women (body mass index (BMI).27.8 kg/m 2 ), 8 with normal (NGT) and 8 with impaired glucose tolerance (IGT), participated in an exercise training program which lasted for 12 weeks and included exercise performed on a bicycle ergometer at an individual intensity of 70% maximal heart rate, for 30 min, 5 days a week. Anthropometrical measurements and blood biochemical analyses were performed, and plasma TNFa, sTNFR1 and sTNFR2 levels were assessed. Insulin sensitivity was evaluated using the hyperinsulinemic euglycemic clamp technique (insulin infusion: 50 mU Â kg 21 Â h 21 ). Results: At baseline, despite similar anthropometrical parameters, IGT subjects were markedly more insulin resistant and had higher TNFa and sTNFR2 concentrations. Exercise training increased insulin sensitivity and decreased TNFa and sTNFR2 levels, while sTNFR1 remained unchanged. The decrease in sTNFR2 was signi®cantly related to the increase in insulin sensitivity; that relationship remained signi®cant after adjustment for the concurrent changes in BMI, waist circumference, percentage of body fat, plasma glucose, insulin and free fatty acids. Conclusions: Regular physical exercise decreases TNFa system activity and that decrease may be responsible for the concurrent increase in insulin sensitivity.

OBJECTIVE -Tumor necrosis factor-␣ (TNF-␣) is a possible link between obesity and impaired glucose tolerance (IGT) and type 2 diabetes. Data about TNF-␣ and soluble forms of its receptors (sTNFR1 and sTNFR2) in IGT are controversial. The aim of the present study was to assess plasma TNF-␣, sTNFR1, and sTNFR2 levels and to evaluate the relationships with insulin resistance in obese subjects with IGT.RESEARCH DESIGN AND METHODS -A total of 104 subjects participated in the present study: 30 obese subjects with IGT (obese-IGT), 32 obese subjects with normal glucose tolerance (obese-NGT), and 42 lean healthy control subjects (control-NGT). Anthropometry and blood biochemical parameters were measured and euglycemic-hyperinsulinemic clamp was performed.RESULTS -Obese-IGT subjects were more insulin resistant in comparison with obese-NGT and control-NGT groups; obese-NGT subjects were more insulin resistant than control-NGT. Plasma sTNFR1 and sTNFR2 were markedly higher in both groups of obese subjects in comparison with control-NGT and in the obese-IGT versus obese-NGT group. Plasma sTNFR1 and sTNFR2 were inversely related to insulin sensitivity. Both relationships remained significant after adjustment for age, BMI, waist girth, percent body fat, plasma glucose, insulin, nonesterified fatty acids, cholesterol, and triglycerides. Correlation between sTNFR2 and insulin sensitivity was also present in all the groups analyzed separately, but the correlation between sTNFR1 and insulin sensitivity was present only in the obese-NGT group. CONCLUSIONS -Our data suggest that TNF-␣ receptors are increased in obese-IGT subjects and are related to insulin resistance. These findings indicate that the TNF-␣ system might contribute to the development of insulin resistance in glucose-intolerant subjects. Diabetes Care 26:875-880, 2003