Showing papers by "Andreas Pfeiffer published in 2009"

A high normal TSH is associated with the metabolic syndrome

Abstract: Summary Objective Obesity and insulin resistance are key features of the metabolic syndrome. In euthyroidism, the relationships between TSH and insulin resistance or the metabolic syndrome are less clear. We investigated the associations between TSH and the features and prevalence of the metabolic syndrome in euthyroid German subjects. Methods In a cross-sectional study, glucose metabolism was defined by an oral glucose tolerance test (oGTT) (except for those with evident diabetes) in 1333 subjects with TSH values between 0·3 and 4·5 mU/l who did not take any thyroid medication. Lipid parameters were measured, blood pressure and anthromopmetric parameters were taken, and insulin resistance was quantified as HOMA%S. Results TSH was weakly correlated with BMI (R = 0·061, P = 0·025). This association remained significant after adjustment for sex, age, and impaired glucose metabolism (P = 0·002). Subjects with a TSH in the upper normal range (2·5–4·5 mU/l, n = 119) had a significantly higher BMI (30·47 ± 0·57 vs. 28·74 ± 0·18 kg/m2, P = 0·001) and higher fasting triglycerides (1·583 ± 0·082 vs. 1·422 ± 0·024 mmol/l, P = 0·023), and their likeliness for fulfilling the ATP III criteria of the metabolic syndrome was 1·7-fold increased (95% CI: 1·11– 2·60). Conclusion In euthyroidism, subjects with a TSH in the upper normal range (2·5–4·5 mU/l) were more obese, had higher triglycerides, and had an increased likeliness for the metabolic syndrome. Therefore, a TSH below 2·5 mU/l is associated with a favourable metabolic profile. Whether lowering TSH to levels below 2·5 mU/l improves metabolism needs to be investigated in intervention trials.

Free fatty acids link metabolism and regulation of the insulin-sensitizing fibroblast growth factor-21.

Abstract: OBJECTIVE Fibroblast growth factor (FGF)-21 improves insulin sensitivity and lipid metabolism in obese or diabetic animal models, while human studies revealed increased FGF-21 levels in obesity and type 2 diabetes. Given that FGF-21 has been suggested to be a peroxisome proliferator–activator receptor (PPAR) α–dependent regulator of fasting metabolism, we hypothesized that free fatty acids (FFAs), natural agonists of PPARα, might modify FGF-21 levels. RESEARCH DESIGN AND METHODS The effect of fatty acids on FGF-21 was investigated in vitro in HepG2 cells. Within a randomized controlled trial, the effects of elevated FFAs were studied in 21 healthy subjects (13 women and 8 men). Within a clinical trial including 17 individuals, the effect of insulin was analyzed using an hyperinsulinemic-euglycemic clamp and the effect of PPARγ activation was studied subsequently in a rosiglitazone treatment trial over 8 weeks. RESULTS Oleate and linoleate increased FGF-21 expression and secretion in a PPARα-dependent fashion, as demonstrated by small-interfering RNA–induced PPARα knockdown, while palmitate had no effect. In vivo, lipid infusion induced an increase of circulating FGF-21 in humans, and a strong correlation between the change in FGF-21 levels and the change in FFAs was observed. An artificial hyperinsulinemia, which was induced to delineate the potential interaction between elevated FFAs and hyperinsulinemia, revealed that hyperinsulinemia also increased FGF-21 levels in vivo, while rosiglitazone treatment had no effect. CONCLUSIONS The results presented here offer a mechanism explaining the induction of the metabolic regulator FGF-21 in the fasting situation but also in type 2 diabetes and obesity.

Diabetic microvascular complications and growth factors.

Abstract: Diabetes mellitus is associated with typical patterns of long term vascular complications which vary with the organ involved. The microvascular kidney disease (Olgemoller and Schleicher, 1993) is characterized by thickening of the capillary basement membranes and increased deposition of extracellular matrix components (ECM), while loss of microvessels with subsequent neovascularisation is predominant in the eye and peripheral nerves. On the other hand macrovascular disease is characterized by accelerated atherosclerosis. These complications are dependent on long term hyperglycemia. Specific biochemical pathways linking hyperglycaemia to microvascular changes were proposed: the polyol pathway (Greene et al., 1987), non-enzymatic glycation of proteins (Brownlee et al., 1988), glucose autooxidation and oxidative stress (Hunt et al., 1990), hyperglycemic pseudohypoxia (Williamson et al., 1993) enhanced activation of protein kinase C by de novo-synthesis of diacyl glycerol (Lee et al., 1989; DeRubertis and Craven 1994) and others. These pathways are not mutually exclusive (Larkins and Dunlop, 1992; Pfeiffer and Schatz, 1992). They may be linked to alterations in the synthesis of growth factors particularly since atherosclerosis and angioneogenesis are associated with increased proliferation of endothelial and smooth muscle cells. Increased synthesis of ECM components is stimulated by growth factors like transforming growth factor beta (TGF beta) (Derynck et al., 1984) and insulin-like growth factor I (IGF-I) (Moran et al., 1991). This review will summarize some of the recent evidence for an involvement of growth factors in diabetic vascular complications and will attempt to assign their emergence in the sequence of events leading to vascular complications.

The role of insulin-like growth factor (IGF) binding protein-2 in the insulin-mediated decrease in IGF-I bioactivity.

Abstract: Context: Insulin interacts with the GH-IGF system by a reciprocal regulation of IGF-binding proteins (IGFBP) and GH, which in turn regulate insulin sensitivity via bioactive IGF-I. This network is linked to metabolic syndrome and cardiovascular diseases. Objective: We evaluated the effect of glucose and insulin on IGFBP-1-4, particularly IGFBP-2, in the regulation of bioactive IGF-I and its relation to insulin resistance. Setting: The study was conducted at an endocrinology center. Research Design and Methods: Twenty-four healthy subjects (12 men; aged 21–72 yr; body mass index 25.9 ± 0.9 kg/m2) and 19 subjects with impaired glucose tolerance (IGT; eight men; aged 26–71 yr; body mass index 28.9 ± 1.2 kg/m2) were prospectively studied using oral glucose tolerance test and hyperinsulinemic euglycemic clamp. Results: During the clamp, insulin decreased IGF-I bioactivity in both IGT subjects and controls (−16.2 ± 2.8 and −13.9 ± 3.3%, respectively; P < 0.01). In addition, insulin increased IGFBP-2 and GH and ...

Genetic Variation in GPR133 is Associated with Height - Genome Wide Association Study in the Self-contained Population of Sorbs

Abstract: Recently, associations of several common genetic variants with height have been reported in different populations. We attempted to identify further variants associated with adult height in a self-contained population (the Sorbs in Eastern Germany) as discovery set. We performed a genome wide association study (GWAS) (similar to 390 000 genetic polymorphisms, Affymetrix gene arrays) on adult height in 929 Sorbian individuals. Subsequently, the best SNPs (P < 0.001) were taken forward to a meta-analysis together with two independent cohorts [Diabetes Genetics Initiative, British 1958 Birth Cohort, (58BC, publicly available)]. Furthermore, we genotyped our best signal for replication in two additional German cohorts (Leipzig, n = 1044 and Berlin, n = 1728). In the primary Sorbian GWAS, we identified 5 loci with a P-value < 10(-5) and 455 SNPs with P-value < 0.001. In the meta-analysis on those 455 SNPs, only two variants in GPR133 (rs1569019 and rs1976930; in LD with each other) retained a P-value at or below 10(-6) and were associated with height in the three cohorts individually. Upon replication, the SNP rs1569019 showed significant effects on height in the Leipzig cohort (P = 0.004, beta = 1.166) and in 577 men of the Berlin cohort (P = 0.049, beta = 1.127) though not in women. The combined analysis of all five cohorts (n = 6,687) resulted in a P-value of 4.7 x 10(-8) (beta = 0.949). In conclusion, our GWAS suggests novel loci influencing height. In view of the robust replication in five different cohorts, we propose GPR133 to be a novel gene associated with adult height. (Less)

Polymorphisms within insulin-degrading enzyme (IDE) gene determine insulin metabolism and risk of type 2 diabetes.

Abstract: Insulin-degrading enzyme (IDE) is the ubiquitously expressed major enzyme responsible for insulin degradation. Insulin-degrading enzyme gene is located on chromosome region 10q23-q25 and exhibits a well-replicated peak of linkage with type 2 diabetes (T2DM). Several genetic association studies examined IDE gene as a susceptibility gene for T2DM with controversial results. However, pathophysiological mechanisms involved have remained elusive. We verified associations of two IDE polymorphisms (rs1887922 and rs2149632) with T2DM risk in two independent German cohorts and evaluated in detail the association of common variants with insulin metabolism and glycemic traits. We confirmed previously published findings for diabetes-associated rs1887922 and rs2149632 in the European Prospective Investigation into Cancer and Nutrition-Potsdam cohort (n = 3049; RR 1.26, p = 0.003 and RR 1.33, p < 0.0001 for additive model). Haplotypes which carried one risk allele of rs2149632 or two risk alleles of both studied IDE SNPs also demonstrated a strong association with increased T2DM risk in this cohort (p = 0.001 and p < 0.0001, respectively). However, we found no significant T2DM association in the cross-sectional metabolic syndrome Berlin-Potsdam cohort (n = 1026). In nondiabetic subjects (NGT+IFG/IGT; n = 739), we found an association of rs2149632 with impaired glucose-derived insulin secretion and a trend to decreased insulin sensitivity for rs1887922. In the NGT subjects (n = 440), the association with decreased insulin secretion for rs2149632 remain significant, and the association with decreased hepatic insulin degradation for rs1887922 were observed additionally. This study validates and confirms the association of IDE polymorphisms with T2DM risk in the prospective German cohort and provides novel evidence of influences of IDE genetic variants on insulin metabolism.

Glucose inhibits the insulin-induced activation of the insulin-degrading enzyme in HepG2 cells

Abstract: Aims/hypothesis Hepatic insulin degradation decreases in type 2 diabetes. Insulin-degrading enzyme (IDE) plays a key role in insulin degradation and its gene is located in a diabetes-associated chromosomal region. We hypothesised that IDE may be regulated by insulin and/or glucose in a liver cell model. To validate the observed regulation of IDE in vivo, we analysed biopsies of human adipose tissue during different clamp experiments in men. Methods Human hepatoma HepG2 cells were incubated in normal (1 g/l) or high (4.5 g/l) glucose medium and treated with insulin for 24 h. Catalytic activity, mRNA and protein levels of IDE were assessed. IDE mRNA levels were measured in biopsies of human subcutaneous adipose tissue before and at 240 min of hyperinsulinaemic, euglycaemic and hyperglycaemic clamps. Results In HepG2 cells, insulin increased IDE activity under normal glucose conditions with no change in IDE mRNA or protein levels. Under conditions of high glucose, insulin increased mRNA levels of IDE without changes in IDE activity. Both in normal and high glucose medium, insulin increased levels of the catalytically more active 15a IDE isoform compared with the 15b isoform. In subcutaneous adipose tissue, IDE mRNA levels were not significantly upregulated after euglycaemic or hyperglycaemic clamps. Conclusions/interpretation Insulin increases IDE activity in HepG2 cells in normal but not in high glucose conditions. This disturbance cannot be explained by corresponding alterations in IDE protein levels or IDE splicing. The loss of insulin-induced regulation of IDE activity under hyperglycaemia may contribute to the reduced insulin extraction and peripheral hyperinsulinaemia in type 2 diabetes.

Deficient activation and different expression of transforming growth factor-β isoforms in active proliferative diabetic retinopathy and neovascular eye disease

Abstract: An increased expression and secretion of angiogenic growth factors was proposed to occur in proliferative diabetic retinopathy and other neovascularizing retinal diseases. However, a loss of anti-angiogenic factors also might promote retinal neovascularization. Therefore we investigated the active and latent vitreous levels of the subtypes of the endothelial anti-mitogen transforming growth factor-beta in vitreous of 58 patients. Four groups of patients were compared: Controls without retinal hypoxia, patients with quiescent and active proliferative diabetic retinopathy (PDR), and patients with severe retinal hypoxia resulting in rubeosis iridis. Whereas the amount of total TGF-beta in the four groups did not differ significantly, latent TGF-beta isoform expression showed complex alterations in ocular vitreous. Levels of active TGF-beta of patients with active PDR (79.5 +/- 28 pg/ml; n = 8) were decreased to 20% of the control levels (378 +/- 55 pg/ml; n = 12; p = 0.0005) and 25% of the mean concentration in quiescent PDR (346 +/- 64 pg/ml; n = 9; p = 0.0021). Levels in rubeosis (52 +/- 10 pg/ml; n = 10) did not differ significantly from those found in active PDR but were decreased to 15% of those in patients with quiescent PDR (p = 0.0004). Furthermore a highly significant inverse correlation between active TGF-beta and alpha2-antiplasmin, a liver produced inhibitor of the activation of TGF-beta by plasmin was noted (r = -0.59; n = 28; p = 0.001). We conclude that deficient activation of TGF-beta occurs in active proliferative diabetic retinopathy and in hypoxic angiogenesis most likely as a consequence of a blood retina barrier breakdown and influx of alpha2-antiplasmin from serum. The disinhibition of endothelial cell proliferation may be a central component in the process of neovascularization.

Metabolic effects of diets differing in glycaemic index depend on age and endogenous glucose-dependent insulinotrophic polypeptide in mice

Abstract: Aims/hypothesis High- vs low-glycaemic index (GI) diets unfavourably affect body fat mass and metabolic markers in rodents. Different effects of these diets could be age-dependent, as well as mediated, in part, by carbohydrate-induced stimulation of glucose-dependent insulinotrophic polypeptide (GIP) signalling.

The influence of genetic variations in HHEX gene on insulin metabolism in the German MESYBEPO cohort

Abstract: Background In the present study, we aimed to validate the type 2 diabetes (T2DM) susceptibility alleles identified in the first genome-wide association study in the hematopoietically expressed homeobox protein (HHEX) gene region (rs1111875 and rs7923837). Furthermore, we investigated quantitative metabolic risk phenotypes of these two variants for association with three key components of the insulin metabolism: insulin secretion, insulin sensitivity and insulin degradation. Methods Two HHEX polymorphisms were genotyped in 1026 subjects from the German MESYBEPO cohort. Complete OGTT data were available for a subset of 420 with normal glucose tolerance (NGT), 282 with impaired glucose tolerance/impaired fasting glucose (IGT/IFG) and 146 diabetic subjects. Results We validated association of both HHEX polymorphisms with T2DM. In the non-diabetic subcohort including NGT and IFG/IGT subjects, the risk alleles of rs7923837 and rs1111875 were significantly associated with decreased first and second phases of insulin secretion and lower insulinogenic index after oral glucose loading. In healthy, normal glucose-tolerant subjects, the same association of HHEX SNP rs1111875 with OGTT-derived phases of insulin secretion were detectable, however, rs7923837 was only weakly associated with reduced insulinogenic index. For both polymorphisms, no significant correlations with insulin sensitivity were obtained. Reduced insulin clearance was also observed in heterozygous carriers of rs1111875. Conclusions We validated the association of polymorphisms of the HHEX gene with T2DM in the MESYBEPO cohort. Importantly, variations within the HHEX gene conferred the impaired insulin secretion and changes of insulin degradation but no alteration in insulin sensitivity in carriers of risk alleles. Copyright © 2008 John Wiley & Sons, Ltd.

Factors that influence retinol-binding protein 4-transthyretin interaction are not altered in overweight subjects and overweight subjects with type 2 diabetes mellitus.

Abstract: Retinol-binding protein 4 (RBP4) is an adipokine bound in plasma to transthyretin (TTR), which prevents its glomerular filtration and subsequent catabolism in the kidney. Alterations of this interaction have been suggested to be implicated in the elevation of RBP4 that are thought to contribute to the development of insulin resistance associated with obesity and type 2 diabetes mellitus (T2DM). However, the factors linking RBP4 to TTR in humans are not clear. Therefore, this study evaluated parameters influencing the RBP4-TTR interaction and their relation to obesity and T2DM. The RBP4 and TTR levels were quantified in plasma of 16 lean controls, 28 overweight controls, and 14 overweight T2DM patients by enzyme-linked immunosorbent assay. Transthyretin isoforms involved in RBP4 binding were determined by linear matrix-assisted laser desorption/ionization-time of flight-mass spectrometry after RBP4 coimmunoprecipitation. Holo-RBP4 (retinol-bound) and apo-RBP4 (retinol-free) were assessed by immunoblotting using nondenaturating polyacrylamide gel electrophoresis. Plasma levels of both RBP4 and TTR did not differ among the groups of lean controls, overweight controls, and overweight T2DM subjects. Using RBP4 immunoprecipitation, 4 mass signals were observed for TTR representing native, S-cysteinylated, S-cysteinglycinylated, and S-glutathionylated TTR. No differences in peak intensity of TTR isoforms were observed among the groups. Moreover, no differences in the ratio of holo- and apo-RBP4 were evident. The results suggest that circulating RBP4 and TTR were not affected by human obesity or T2DM, which might be attributed to the absence of alterations of TTR isoforms and the ratio of holo- and apo-RBP4 that might modify the TTR-RBP4 interaction.

Butyrate-induced alterations of phosphoinositide metabolism, protein kinase C activity and reduced CD44 variant expression in HT-29 colon cancer cells.

Abstract: Initiation of cell growth and neoplastic transformation frequently involves activation of growth factor receptor-coupled tyrosine kinases and stimulation of the phosphoinositide second messenger system. Altered expression of CD44 variants was reported in several malignant tumor types with possible implications for tumor progression and prognosis. CD44 variant expression was reported to be associated with second messenger activation and differentiation. We therefore investigated the effects of butyrate-induced short-term differentiation on phosphoinositide signaling, phospholipase C and protein kinase C activity and alteration of CD44 variant expression in human HT-29 colon carcinoma cells. HT-29 cells were cultured with sodium butyrate for 6 days. Phosphoinositide turnover was measured by [32P]orthophosphate incorporation and phospholipase C activity by determination of the release of [3H]inositolphosphates from [3H]myoinositol prelabeled cells. Protein kinase C activity was determined by histone III-S phosphorylation, PKC subtype expression by RNase protection analysis, and CD44 variant expression was determined by RT-PCR using variant-specific primers. Treatment of HT-29 human colon carcinoma cells with sodium butyrate caused a dose-dependent inhibition of cell proliferation (IC50, 2.5 mM) with morphologic signs of an enterocytic differentiation following 6 days of treatment. The phosphoinositide turnover as determined by 32P-incorporation under non-equilibrium conditions showed a 30-40% inhibition of labeled phosphoinositides and phosphatidic acid and a dose-dependent inhibition of cholinergically stimulated phospholipase C activity as a secondary event following butyrate-induced enterocytic differentiation. However, long-term incubation of HT-29 cells with phorbol ester or an inhibitor of classical and novel PKC subtypes did not affect cell proliferation. In butyrate-treated HT-29 cells activation of calcium-dependent protein kinase C by cholinergic stimulation or phorbolester treatment induced an increase in membrane-bound cPKC activity, while expression of distinct high- molecular CD44 variant transcripts v3 (670 bp), v5 (940 bp) and v8 (535 bp) were drastically reduced after butyrate pretreatment. Enterocytic differentiation of HT-29 colon carcinoma cells seems to be associated with alterations in phosphoinositide resynthesis, phospholipase C activity and ligand/receptor-induced PKC translocation. The observed reduction of distinct high-molecular CD44v3, v5 and v8 variants following butyrate-induced differentiation indicates an association of specific CD44 variant expression with the malignant phenotype of HT-29 colon cancer cells, thus being possible targets for new diagnostic and therapeutic strategies.

Okadaic acid indicates a major function for protein phosphatases in stimulus-response coupling of RINm5F rat insulinoma cells.

Abstract: Stimulus-induced insulin secretion involves the activation of several protein kinases within the beta cell. Most prominent are protein kinase A, protein kinase C and calcium/calmodulin-dependent protein kinases. Protein kinase action is functionally antagonized by protein phosphatases. The four ubiquious serine/threonine protein phosphatases are termed PP-1, PP-2A, -2B and -2C. PP-1 and PP-2A are in vivo parts of major protein complexes. These complexes presumably regulate the phosphatase activity and direct the enzyme to its site of action. Therefore, PP-1 and -2A could play an important role in controlling intracellular signal transmission. Two different toxins, okadaic acid and calyculin A, both from marine invertebrates, were recently discovered and identified as potent and highly specific inhibitors of PP-1 and PP-2A. Both compounds emerged as very useful tools for studying intracellular phosphorylation events. We took advantage of these substances to investigate the significance of protein phosphatase action in stimulus-induced insulin secretion. To avoid major complexity, we confined our study to the cAMP and the phosphoinositide signal pathway. Okadaic acid alone evoked virtually no secretory response. cAMP-dependent secretion was markedly enhanced by 1 microM okadaic acid. The stimulatory effect of okadaic acid was strongly dependent on the concentration of cAMP analoga. In contrast, insulin release caused by the cholinergic agonist carbachol was not influenced by okadaic acid. Calyculin A (10 nM) slightly increased cAMP-induced secretion, but its high toxicity prohibited accurate interpretation of the data. Our findings support the idea that serine/threonine phosphatases act as important regulators in stimulus response coupling.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of human platelet protein kinase C-beta 2 in vivo in response to acute hyperglycemia.

Abstract: Protein kinase C (PKC) is known to be activated in experimental model systems by elevated glucose and may play an important role in the pathogenesis of diabetic complications. Since there is no information about its role in humans in vivo we investigated the activation of PKC in human thrombocytes during infusion of glucose and insulin in normal controls and in 19 NIDDM patients by determining membrane and cytosol levels of PKC beta 2 using immune blots. In the 27 subjects investigated (8 controls, 19 NIDDM) membrane-associated levels of PKC beta 2 increased significantly after 60 and 150 min (p < 0.005). In controls an increase of membrane and of cytosolic PKC beta 2 occurred upon elevation of glucose by 5.5 mmol/L or more and the membrane association persisted for at least 60 min. In NIDDM glucose was elevated by 7.5-10 mmol/L during infusions. Increases of both membrane and cytosolic PKC beta 2 (< 20%-300%) occurred in 10 NIDDM patients suggesting that both, translocation and increased synthesis of PKC beta 2 were stimulated by glucose. Nine other patients showed no alteration (i.e. < 20%) of PKC beta 2. The 2 groups were similar regarding parameters of diabetes control, baseline glucose and glucose elevation during the test. However, the PKC beta 2 responsive group had lower levels of serum triglycerides (1.39 +/- 0.19 vs. 2.32 +/- 0.34 g/L; p = 0.038). To assess whether absolute levels of PKC were altered in human diabetes, platelet levels of PKC alpha, beta 1 and beta 2 were determined in 22 controls and 25 NIDDM subjects with poorly controlled diabetes (HbA1c = 9.8 +/- 0.36%). Cytosolic levels of PKC alpha were significantly decreased by 27% compared to controls in NIDDM but there was no change of PKC beta 1 or PKC beta 2. We conclude that 1. acute elevation of glucose by 5.5 mmol/L or more can activate PKC beta 2 translocation in controls and NIDDM patients in vivo irrespective of parameters of metabolic control. 2. NIDDM patients differ in their PKC beta 2-responses to glucose and 3. poor metabolic control leads to moderate downregulation of PKC alpha suggesting continued activation.

Acute hyperinsulinaemia and hyperlipidaemia modify circulating adiponectin and its oligomers.

Abstract: Summary Objective Obesity and insulin resistance are associated with low adiponectin levels, although adiponectin is exclusively expressed in white adipose tissue. The mechanism beyond that paradox is not entirely clear, although insulin itself may reduce circulating adiponectin levels. However, obesity is also associated with hyperlipidaemia and the effects of free fatty acids (FFAs) and triglycerides (TG) on circulating adiponectin levels have not yet been investigated. Materials and methods We analysed the effect of an acute and euglycaemic elevation of insulin on adiponectin oligomers in 23 healthy individuals. In a subgroup including 11 healthy men, FFAs and TG were acutely elevated by infusion of heparin/lipids over 120 min. Again the effect on circulating adiponectin and its oligomers was investigated. Adiponectin was determined by ELISA, oligomers were detected by nondenaturating Western blot. Results Acute hyperinsulinaemia resulted in a significant reduction of total adiponectin to 7·74 ± 0·98 µg/ml (P = 0·004). High molecular weight (HMW) adiponectin did not change (0·80 ± 0·12 to 0·81 ± 0·14 µg/ml; P = 0·887), whereas MMW adiponectin decreased from 4·30 ± 0·51 to 3·78 ± 0·48 µg/ml (P = 0·005) and LMW adiponectin from 3·63 ± 0·42 to 3·15 ± 0·46 µg/ml (P = 0·048). Interestingly, heparin/lipid infusion also reduced circulating adiponectin levels (P = 0·001), which was primarily the result of reduced MMW adiponectin (P = 0·004), whereas LMW and HMW were not significantly affected. Conclusions The presented data suggest that both, hyperinsulinaemia and hyperlipidaemia, may contribute to low adiponectin levels in states of obesity.

Low–Glycemic Index vs High–Cereal Fiber Diet in Type 2 Diabetes

Abstract: To the Editor: In their randomized controlled trial, Dr Jenkins and colleagues reported moderately reduced levels of hemoglobin A1c (HbA1c) in patients with type 2 diabetes treated with a low–glycemic index diet compared with a high–cereal fiber diet over 6 months. They concluded that low–glycemic index diets may be useful as part of the strategy to improve glycemic control in patients with type 2 diabetes. Low–glycemic index diets are typically high-fiber diets. As the authors acknowledged, the low–glycemic index diet contained even more fiber than the high–cereal fiber diet (18.7 vs 15.7 g of fiber per 1000 kcal; P .001). Several of the recommended foods in the high–cereal fiber group contained considerable amounts of soluble fibers (such as pectin in guava and carrots) that, unlike cereal fibers, do not appear to influence diabetes risk. In addition, starchy high–glycemic index food such as baked potatoes, emphasized in the high–cereal fiber and restricted in the low–glycemic index group, might have further influenced the observed findings. However, we recognize the challenges in designing an intervention comparing effects of low–glycemic index vs high–cereal fiber diets. We disagree with the authors’ statement that “with the exception of oat and barley fiber” (which are rich in soluble -glucan fibers), “cereal fibers are largely without metabolic effect.” The authors provided a reference supporting that additional consumption of 15 g of wheat bran per day for 3 months does not change fasting glucose and HbA1c levels in diabetic patients. However, the dose might have been too small, and even short-term ingestion of various other insoluble fibers including purified cereal fiber in higher doses (approximately 30 g per day) shows significant meal-related metabolic effects. Improved whole-body insulin sensitivity after consumption of insoluble, nonviscous fibers has been reported, using euglycemic-hyperinsulinemic clamps. Glycemic control is incompletely reflected by HbA1c and fasting glucose levels. The metabolic benefit of insoluble cereal fibers may exceed that of low–glycemic index or soluble fibers and may best be reflected by measures of insulin sensitivity. Although estimates of insulin sensitivity are likely to more accurately estimate hepatic rather than wholebody insulin sensitivity, to provide a complete picture the authors should report such indices including fasting insulin levels. Martin O. Weickert, MD martin.weickert@charite.de Andreas F. H. Pfeiffer, MD Department of Endocrinology, Diabetes and Nutrition Charite-University-Medicine Berlin Berlin, Germany

A reverse postural test as a screening tool for aldosterone-producing adenoma: a pilot study.

Abstract: The aldosterone-to-renin ratio (ARR) is an accepted screening tool for primary hyperaldosteronism (PA). An ambulatory case finding test to separate surgically remediable aldosterone-producing adenoma (APA) from other forms of PA, however, is currently not available. The aim of this study was to evaluate a reverse postural test (RPT) as a novel tool for identifying APA. We investigated 6 healthy controls, 19 primary hypertensive patients, and a prospective cohort of 32 patients clinically suspicious for primary hyperaldosteronism. We diagnosed seven patients with surgically proven APA, and three patients with idiopathic hyperaldosteronism. Serum aldosterone was measured after 30-min of moderate exercise (Aldo-1) and after a subsequent 2-h supine resting period (Aldo-2) with calculation of the ratio Aldo-2/Aldo-1. Aldosterone significantly decreased after supine resting in both healthy controls and primary hypertensives, but not in patients with APA. Receiver-operating-curve analysis revealed that the RPT was suitable for the screening of APA. A combination of the ratio Aldo-2/Aldo-1 >0.59 and Aldo-2 >160 pg/ml correctly identified all the patients with APA, with no false positives. Although the high sensitivity of the RPT here observed needs to be confirmed in larger studies, the high positive predictive value of RPT could be useful for the identification of APA in outpatients.

Methods and assays for classifying foodstuff and/or beverage and/or diet and/or nutrition regimen and/or medicament in view of an effect on the cardiovascular system

Abstract: Subject of the present invention is an in vitro -method for classifying a foodstuff and/or beverage and/or diet and/or nutrition regimen and/or medicament in view of an effect on the cardiovascular system of a subject, comprising determining the relative level of one or more cardiovascular markers.

Overexpression of calcium/calmodulin-dependent protein kinase II in insulinoma cells by use of a retroviral vector.

Abstract: The manner in which increasing intracellular calcium levels lead to insulin exocytosis is not known. Possibly the signal is mediated by activation of calcium/calmodulin-dependent protein kinase II (CaM Kin II). In this work the establishment of an insulinoma cell line stably overexpressing CaM Kinase II subtype delta 2 by an ecotropic retroviral transduction system is described.

Laser induced tunneling in less than 12 attoseconds: Instantaneous or invalid concept?

Abstract: We use attosecond angular streaking to place an intensity-averaged upper limit of 12 attoseconds on the tunneling delay time in strong field ionization of helium. This is far shorter than most tunneling times discussed before.

Laser induced tunneling ionization in less than 12 attoseconds measured by attosecond angular streaking

Abstract: It is typically assumed that electrons can escape from atoms through tunneling when exposed to strong laser fields, but the timing of the process has been controversial, and far too rapid to probe in detail. We have used attosecond angular streaking [1] to place an upper limit of 34 attoseconds and an intensity-averaged upper limit of 12 attoseconds on the tunneling delay time in strong field ionization of a helium atom in the non-adiabatic tunneling regime [2]. This is the fastest process that has ever been measured. Our experimental results give a strong indication that there is no real tunneling delay time, which is also confirmed with numerical simulations using the time-dependent Schrodiger equation [3].