Pioglitazone has direct effects on insulin sensitivity and intracellular lipid content in L6 skeletal muscle cells.

Using L6 skeletal muscle cell line, rendered insulin resistant by incubation with triglyceride-rich lipoproteins (TGRLs), we sought to answer the question whether pioglitazone has direct effects on this cell line. Incubation of L6 cells with TGRLs led to an increase in the intramyocellular triglyceride content. Moreover, TGRLs led to a reduction in insulin-stimulated glycogen content and GSK-3 phosphorylation. All these changes induced by TGRLs could be antagonized by incubation of L6 cells with pioglitazone. The PPAR-γ antagonist GW9662 reversed the pioglitazone effects. We conclude that pioglitazone has direct insulin-sensitizing effects on the L6 skeletal muscle cell line, which are paralleled by a reduction in intramyocellular triglyceride accumulation.

Effect of postprandial lipemia on plasma concentrations of A-FABP, RBP-4 and visfatin.

BACKGROUND AND AIMS: Several studies indicate that changes in the plasma concentrations of adipocyte-fatty acid binding protein (A-FABP), retinol binding protein-4 (RBP-4) and visfatin are associated with chronic states of insulin resistance. Recent studies have shown that postprandial lipemia induces an acute state of insulin resistance. The aim of this study was to investigate the effect of postprandial lipemia on the plasma concentrations of A-FABP, RBP-4 and visfatin. METHODS AND RESULTS: In a within-subject crossover study, we administered a standardized high-fat meal to 24 healthy subjects (12 males and 12 females). Plasma concentrations of adipocytokines were measured in the morning after an overnight fast and during postprandial lipemia, i.e. 2, 4 and 6 hours after meal ingestion (postprandial experiment). To exclude potential confounding factors affecting the adipocytokine plasma concentrations, a control experiment without meal ingestion was performed over the same time period (postabsorptive control experiment). Comparing plasma concentrations of A-FABP, RBP-4 and visfatin between the postprandial and the postabsorptive control experiments, we found no significant differences. Within either of the two experiments, a decrease of A-FABP was noted reaching, however, statistical significance only in the postprandial experiment, i.e. 2 and 4 hours after meal ingestion. CONCLUSION: Postprandial lipemia has no significant effect on the plasma concentrations of visfatin, A-FABP or RBP-4 in relation to their postabsorptive plasma profiles. We conclude that prolonged states of insulin resistance are required to affect plasma concentrations of these adipocytokines.

Effect of obesity and insulin sensitivity on adiponectin isoform distribution.

BACKGROUND: Adiponectin is an insulin-sensitizing, antiatherogenic and anti-inflammatory adipocytokine that circulates in three isoforms: a trimer [low-molecular weight (LMW)], a hexamer (trimer-dimer) of medium molecular weight (MMW) and a multimeric high molecular weight (HMW) isoform. Evidence is accumulating that HMW adiponectin is the active isoform of the adipocytokine. We investigated the impact of adipose tissue and insulin sensitivity on adiponectin isoform distribution. MATERIALS AND METHODS: One hundred and eighty-seven normolipidaemic, non-diabetic lean or obese subjects with or without insulin resistance participating in the Salzburg Atherosclerosis Prevention program in subjects at High Individual Risk (SAPHIR) were included in the study. Insulin sensitivity was determined by the short insulin tolerance test and the homeostasis model assessment (HOMA) index. Serum adiponectin isoform distribution was determined by an enzyme immunoassay. RESULTS: Total adiponectin as well as HMW/total adiponectin ratio was significantly increased in female subjects. Circulating total adiponectin levels were lowest in obese patients due to reduced concentrations of HMW adiponectin. As determined by stepwise regression analysis, besides age and high density lipoprotein (HDL) cholesterol, visceral fat area and waist-to-hip ratio predicted concentrations of HMW adiponectin, while insulin sensitivity had no influence on either total adiponectin or its isoforms. CONCLUSIONS: Our results underline that determination of adiponectin isoforms are more useful than measurement of total adiponectin in clinical settings. Our data suggest that adiponectin concentrations are strongly associated with visceral fat area but not with insulin sensitivity. Thus, we hypothesize that insulin resistance is a consequence rather than the cause of hypoadiponectinaemia in obese subjects.

Effect of pronounced weight loss on visceral fat, liver steatosis and adiponectin isoforms.

BACKGROUND: Weight loss induced by bariatric surgery is an effective method to reverse obesity and comorbidities. The aim of this prospective weight loss study was to investigate changes of body fat distribution in relation to adiponectin and its isoforms and further to investigate the influence of both body fat distribution and adiponectin on the degree of liver steatosis. DESIGN: Fifteen severely obese female patients (body mass index 43.1 +/- 4.1, mean age 34.5 +/- 8.6 years) were examined before and after surgical treatment. Grading of fatty liver disease and the subcutaneous and visceral fat diameters were determined by abdominal ultrasonography. Metabolic parameters were determined using standard methods; serum total adiponectin and its isoforms were detected by enzyme immuno assay (EIA). RESULTS: Mean weight loss was 28.3 kg, which was mostly due to a loss in fat mass, accompanied by an increase in total adiponectin and the high molecular weight (HMW) adiponectin isoform. Visceral adipose tissue (VAT) diameter was highly correlated with liver steatosis, even more strongly than the parameters of liver function. In addition, liver steatosis correlated negatively with HMW adiponectin and binary logistic regression revealed that changes in fat mass, HMW adiponectin and alanine aminotransferase (ALT) were the best predictors for changes in the degree of hepatic steatosis. CONCLUSIONS: Our results suggest that circulating HMW adiponectin is associated with both VAT and liver steatosis. In summary, the major findings were that the VAT diameter is highly correlated with liver steatosis, even stronger than the parameters of liver function and the association of HMW adiponectin with liver steatosis was better than with total adiponectin.

Effect of valproic acid treatment on body composition, leptin and the soluble leptin receptor in epileptic children.

PURPOSE: The aim of the study was to determine the influence of valproic acid (VPA) treatment on leptin, the soluble leptin receptor (sOB-R), the sOB-R/leptin ratio, body composition and insulin resistance in epileptic children. METHODS: A cross-sectional cohort study was conducted at the Medical University Innsbruck, Austria. Children >6 years with idiopathic epilepsy and antiepileptic drug therapy since at least six months were eligible. Leptin concentration, the sOB-R, the sOB-R/leptin ratio, body composition and glucose homeostasis were determined. RESULTS: 87 children (median [range] age 12.8 years [6.0-18.6]) were on treatment with VPA, 55 (12.3 years [6.4-18.3]) on other AEDs, comprising the non-VPA group. VPA-treated children had higher leptin concentrations, body-mass-index standard-deviation score (SDS), body fat (each p<0.001), serum insulin concentrations (p=0.014) and homeostasis model assessment (HOMA) index (p=0.009), as well as a lower sOB-R/leptin ratio (p<0.001) when compared to the non-VPA group. Overweight VPA-treated children showed lower sOB-R concentrations and a lower sOB-R/leptin ratio (each p<0.001) as well as higher body fat and leptin levels (each p<0.001) compared to lean VPA-treated children. CONCLUSION: VPA monotherapy was associated with higher body weight, body fat and serum leptin concentrations as well as impaired glucose homeostasis. Low sOB-R concentrations and a low sOB-R/leptin ratio in overweight VPA-treated patients might contribute to disturbances in glucose homeostasis and to the development of the metabolic syndrome in these children later in life.

Effect of intradialytic parenteral nutrition in patients with malnutrition-inflammation complex syndrome on body weight, inflammation, serum lipids and adipocytokines: results from a pilot study.

OBJECTIVE: Evaluation of the influence of intradialytic parenteral nutrition (IDPN) in patients suffering from Malnutrition-Inflammation Complex Syndrome (MICS) on nutritional status, inflammation, adipocytokines and serum lipids. SUBJECTS: Six patients with MICS were assigned to IDPN, whereas six patients matched for age, sex, body mass index (BMI) and co-morbidity without malnutrition served as controls. Patients were recruited from Outpatient Dialysis Unit, Medical University Innsbruck and from Dialysis Unit, Hospital Feldkirch. RESULTS: In all patients with IDPN, dry body weight increased during the interventional period whereas body weight remained stable in patients without IDPN. Tumor necrosis factor (TNF)-alpha levels were higher in patients with MICS compared with controls at all time points. Total cholesterol, LDL- and HDL-levels significantly increased during dialysis at all time points in controls but not in patients with MICS. Albumin, C-reactive protein, interleukin-6 (IL-6), soluble interleukin-2 receptor (sIL-2R) and adipocytokines did not differ between patients and controls during the study period. CONCLUSIONS: IDPN in patients with MICS increases body weight despite not influencing inflammatory status. Furthermore, IDPN does not induce a pro-atherogenic lipid composition enhancing the risk for atherosclerosis. Thus, IDPN is a safe and effective treatment of malnutrition in patients with MICS.

Are plasma VEGF and its soluble receptor sFlt-1 atherogenic risk factors? Cross-sectional data from the SAPHIR study.

AIMS: Vascular endothelial growth factor (VEGF) is a potent hypoxia-regulated angiogenic factor. Its soluble receptor soluble (s)Flt-1 binds VEGF with high affinity inhibiting the angiogenic function of VEGF. The role of circulating VEGF in atherosclerosis is unclear. METHODS AND RESULTS: In 909 healthy subjects (511 male, 398 female) from the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) we determined fasting plasma VEGF and sFlt-1 concentration, cardiovascular risk factors and carotid atherosclerosis. VEGF levels were lower and sFlt-1 levels higher in men than in women. VEGF and sFlt-1 showed a positive correlation. In the entire population VEGF correlated positively with age, BMI, insulin resistance, white blood cell and platelet count, C-reactive protein (CRP) and carotid intima media thickness (IMT). After adjustment for age, VEGF showed a weak positive correlation with BMI, liver enzymes, CRP and platelet count in males. In females VEGF correlated negatively with LDL-cholesterol and positively with insulin resistance and platelet count. After adjustment for age, no significant correlation with carotid atherosclerosis could be detected. CONCLUSION: Plasma VEGF and sFlt-1 are only weakly correlated with cardiovascular risk factors, suggesting that circulating VEGF levels do have only a minor impact on the development of atherosclerosis.

Effects of six second generation antipsychotics on body weight and metabolism - risk assessment and results from a prospective study.

BACKGROUND: Due to the association of second generation antipsychotics (SGAs) with weight gain and alterations of glucose and lipid homeostasis, we aimed to group six commonly prescribed SGAs into classes of differing risks. METHODS: Twenty-eight patients meeting the criteria for a diagnosis of schizophrenic disorder according to ICD-10 were assigned to monotherapy with olanzapine, clozapine, quetiapine, amisulpride, ziprasidone or risperidone. The levels of glucose and lipid metabolism were assessed before and after 28 days of treatment. RESULTS: Based on cluster analysis, olanzapine and clozapine were found to constitute a high-risk group for metabolic dysregulation while amisulpride, quetiapine, risperidone and ziprasidone could be assigned to a non-high-risk group. Subjects from the high-risk group displayed significant weight gain with concomitant increases of HOMA-IR, levels of insulin, total cholesterol, TG, LDL-C and leptin. No significant changes were observed in the non-high-risk group. CONCLUSION: The results of this study support the conclusion of the Consensus Development Conference on Antipsychotic Drugs and Obesity and Diabetes that certain SGAs are associated with a higher risk for weight gain, insulin resistance and dyslipidemia.

Postprandial lipaemia induces an acute decrease of insulin sensitivity in healthy men independently of plasma NEFA levels.

AIMS/HYPOTHESIS: Typical Western diets cause postprandial lipaemia for 18 h per day. We tested the hypothesis that postprandial lipaemia decreases insulin sensitivity. SUBJECTS, MATERIALS AND METHODS: Employing a randomised crossover design, we administered two types of virtually isocaloric meals to ten healthy volunteers on two separate occasions. The meals (Meals 1 and 2) were both designed to produce a rise in triglycerides, but only Meal 1 generated a rise in NEFA, too. Insulin sensitivity, as quantified by an IVGTT with minimal model analysis, was calculated postabsorptively at 08.00 h and postprandially at 13.00 h, i.e. 3 h after meal ingestion. RESULTS: Triglycerides rose from 0.91+/-0.31 mmol/l postabsorptively to 2.08+/-0.70 mmol/l postprandially with Meal 1 (p=0.005) and from 0.92+/-0.41 to 1.71+/-0.79 mmol/l with Meal 2 (p=0.005). Neither the triglyceride levels at 13.00 h, nor the post-meal AUCs for triglycerides were statistically different between Meal 1 and Meal 2. NEFA rose from 0.44+/-0.17 mmol/l postabsorptively to 0.69+/-0.16 mmol/l postprandially with Meal 1 (p=0.005) and showed no significant change with Meal 2 (0.46+/-0.31 mmol/l postabsorptively vs 0.36+/-0.32 mmol/l postprandially, p=0.09). Both the NEFA level at 13.00 h and the post-meal AUC for NEFA were significantly higher after Meal 1 than Meal 2. Compared with the postabsorptive state, insulin sensitivity decreased postprandially after each of the two meals to a comparable degree (Meal 1: -53%, p=0.02; Meal 2: -45%, p=0.005). CONCLUSIONS/INTERPRETATION: Our study reveals a drop in insulin sensitivity during postprandial lipaemia and strongly suggests that decreased insulin sensitivity is brought about by elevated plasma levels of triglyceride-rich lipoproteins independently of plasma NEFA levels.

Fluorescence determination of low formaldehyde concentrations in air by dye laser excitation.

This paper describes a fluorescence technique for the detection of sub-ppm-concentrations of formaldehyde in air at atmospheric pressure. The aldehyde is excited by a frequency doubled tunable dye laser covering the 320-345-nm wavelength range. The fluorescence intensity, measured at right angles through a 400-nm cutoff filter, is proportional to the formaldehyde concentration in air. Interferences by NO(2) and SO(2) are negligible. The detection limit of the system is 5 pphm at present, in good agreement with an estimate of the fluorescence yield in 1 atm of air. A considerable increase of the sensitivity is possible, and the use of this technique for measuring formaldehyde in ambient air in the ppb concentration range is projected.