Insulin Directly Regulates the Circadian Clock in Adipose Tissue.

Adipose tissue (AT) is a key metabolic organ which functions are rhythmically regulated by an endogenous circadian clock. Feeding is a "zeitgeber" aligning the clock in AT with the external time, but mechanisms of this regulation remain largely unclear. We tested the hypothesis that postprandial changes of the hormone insulin directly entrain circadian clocks in AT and investigated a transcriptional-dependent mechanism of this regulation. We analyzed gene expression in subcutaneous AT (SAT) of obese subjects collected before and after the hyperinsulinemic-euglycemic clamp or control saline infusion (SC). The expressions of core clock genes PER2, PER3, and NR1D1 in SAT were differentially changed upon insulin and saline infusion, suggesting insulin-dependent clock regulation. In human stem cell-derived adipocytes, mouse 3T3-L1 cells, and AT explants from mPer2Luc knockin mice, insulin induced a transient increase of the Per2 mRNA and protein expression, leading to the phase shift of circadian oscillations, with similar effects for Per1 Insulin effects were dependent on the region between -64 and -43 in the Per2 promoter but not on CRE and E-box elements. Our results demonstrate that insulin directly regulates circadian clocks in AT and isolated adipocytes, thus representing a primary mechanism of feeding-induced AT clock entrainment.

Orphan GPR116 mediates the insulin sensitizing effects of the hepatokine FNDC4 in adipose tissue.

The proper functional interaction between different tissues represents a key component in systemic metabolic control. Indeed, disruption of endocrine inter-tissue communication is a hallmark of severe metabolic dysfunction in obesity and diabetes. Here, we show that the FNDC4-GPR116, liver-white adipose tissue endocrine axis controls glucose homeostasis. We found that the liver primarily controlled the circulating levels of soluble FNDC4 (sFNDC4) and lowering of the hepatokine FNDC4 led to prediabetes in mice. Further, we identified the orphan adhesion GPCR GPR116 as a receptor of sFNDC4 in the white adipose tissue. Upon direct and high affinity binding of sFNDC4 to GPR116, sFNDC4 promoted insulin signaling and insulin-mediated glucose uptake in white adipocytes. Indeed, supplementation with FcsFNDC4 in prediabetic mice improved glucose tolerance and inflammatory markers in a white-adipocyte selective and GPR116-dependent manner. Of note, the sFNDC4-GPR116, liver-adipose tissue axis was dampened in (pre) diabetic human patients. Thus our findings will now allow for harnessing this endocrine circuit for alternative therapeutic strategies in obesity-related pre-diabetes.

Dietary Rapeseed Oil Supplementation Reduces Hepatic Steatosis in Obese Men-A Randomized Controlled Trial.

SCOPE: Effective treatment for obesity associated non-alcoholic fatty liver disease (NAFLD) is limited. Dietary supplementation of n-3 polyunsaturated fatty acids, specifically alpha linolenic acid (ALA), can resolve intrahepatic lipid content (IHL). This study investigates the effect of daily supplementation of either refined rapeseed (RA), containing high amounts of ALA, or refined olive (OL) oil on IHL and glucose metabolism in NAFLD patients. METHODS AND RESULTS: 27 obese men consumed an isocaloric diet including either 50 g of RA or OL daily for 8 weeks. Hepatic proton magnetic resonance spectroscopy, hyperinsulinemic-euglycemic clamp studies and blood tests are performed before and at the end of the study. At 8 weeks a significant reduction in IHL is observed for RA (13.1 ± 1.6 before versus 11.1 ± 1.6% after intervention) versus OL (13.3 ± 2.5 before versus 15.7 ± 2.7% after intervention). For RA, a 21% reduction (P < 0.02) in serum free fatty acids (FFA) and a 1.68-fold increase (P = 0.03) of serum interleukin-6 (IL-6) is observed after 8 weeks. CONCLUSION: RA has a beneficial effect on hepatic lipid metabolism as shown by reduced IHL and serum FFA. RA induced IL-6 production seems to be liver protective confirming previous results.

Sexually dimorphic metabolic responses to exposure of a high fat diet during pregnancy, lactation and early adulthood in Gipr-/- mice.

Obesity has a multifactorial origin. It is known that alterations of the intra uterine milieu induce developmental programming effects leading to metabolic diseases in offspring. Obesity is diminished in mice lacking the glucose-dependent insulinotropic polypeptide receptor (Gipr-/-) when exposed to a high fat diet (HFD). We investigated whether Gipr-/- mice are still protected from obesity when additionally exposure to a HFD during pregnancy and lactation occurs. Male and female wild type (WT) and Gipr-/- offspring received either a control/ low fat diet or HFD during pregnancy and lactation and were then either left on this diet or placed on the opposite diet after weaning until 24 weeks of life. Female WT mice showed increased body weight and adiposity when exposed to a HFD during pregnancy and lactation and post-weaning compared to female WT that received the HFD after weaning only. This exacerbated effect of a HFD during pregnancy and lactation was abolished in female Gipr-/- mice. Male Gipr-/- mice were protected from obesity to a much lesser extent. Male Gipr-/- mice exposed to a HFD during pregnancy and lactation and after weaning exhibited significantly increased fed serum glucose compared to Gipr-/- mice exposed to a HFD after weaning only. In female Gipr-/- mice no differences in fed blood glucose were observed between these groups. Our data indicate that female Gipr-/- mice are more protected from obesity. This protection is preserved in female Gipr-/- mice when additional deleterious effects of a HFD occur during fetal development.

VEGF and GLUT1 are highly heritable, inversely correlated and affected by dietary fat intake: Consequences for cognitive function in humans.

OBJECTIVE: Reduction of brain glucose transporter GLUT1 results in severe neurological dysfunction. VEGF is required to restore and maintain brain glucose uptake across the blood brain barrier via GLUT1, which was shown to be acutely diminished in response to a high fat diet (HFD) in mice. The genetic and HFD-related regulation and association of VEGF and GLUT1 (SLC2A1) in humans was investigated in the NUtriGenomic Analysis in Twins (NUGAT) study. METHODS: 92 healthy and non-obese twins were standardized to a high-carbohydrate low-fat diet for 6 weeks before switched to a 6-week HFD under isocaloric conditions. Three clinical investigation days were conducted: after 6 weeks of low-fat diet and after 1 and 6 weeks of HFD. Serum VEGF and other cytokine levels were measured using ELISA. Gene expression in subcutaneous adipose tissue was assessed by quantitative Real-Time PCR. Genotyping was performed using microarray. The Auditory Verbal Learning Task was conducted to measure cognitive performance. RESULTS: In this human study, we showed that the environmental regulation of SLC2A1 expression and serum VEGF by HFD was inversely correlated and both factors showed strong heritability (>90%). In response to the HFD containing 45% fat, serum VEGF levels increased (P = 0.002) while SLC2A1 mRNA expression in adipose tissue decreased (P = 0.001). Higher BMI was additionally associated with lower SLC2A1 expression. AA-genotypes of the rs9472159 polymorphism, which explained ∼39% of the variation in circulating VEGF concentrations, showed significantly reduced serum VEGF levels (P = 6.4 × 10-11) but higher SLC2A1 expression (P = 0.009) in adipose tissue compared to CC/CA-genotypes after 6 weeks of HFD. Memory performance in AA-genotypes declined in response to the HFD compared to CC- and CA-genotypes. CONCLUSIONS: The results provide evidence to suggest the translatability of the dietary regulation of VEGF and GLUT1 from mouse models to humans. Our data demonstrate that HFD induces a genetically determined and correlated decrease of GLUT1 and increase of VEGF which may affect memory performance. CLINICAL TRIAL REGISTRATION NUMBER: NCT01631123.

High-Fat Diet During Mouse Pregnancy and Lactation Targets GIP-Regulated Metabolic Pathways in Adult Male Offspring.

Maternal obesity is a worldwide problem associated with increased risk of metabolic diseases in the offspring. Genetic deletion of the gastric inhibitory polypeptide (GIP) receptor (GIPR) prevents high-fat diet (HFD)-induced obesity in mice due to specific changes in energy and fat cell metabolism. We investigated whether GIP-associated pathways may be targeted by fetal programming and mimicked the situation by exposing pregnant mice to control or HFD during pregnancy (intrauterine [IU]) and lactation (L). Male wild-type (WT) and Gipr(-/-) offspring received control chow until 25 weeks of age followed by 20 weeks of HFD. Gipr(-/-) offspring of mice exposed to HFD during IU/L became insulin resistant and obese and exhibited increased adipose tissue inflammation and decreased peripheral tissue substrate utilization after being reintroduced to HFD, similar to WT mice on regular chow during IU/L. They showed decreased hypothalamic insulin sensitivity compared with Gipr(-/-) mice on control diet during IU/L. DNA methylation analysis revealed increased methylation of CpG dinucleotides and differential transcription factor binding of promoter regions of genes involved in lipid oxidation in the muscle of Gipr(-/-) offspring on HFD during IU/L, which were inversely correlated with gene expression levels. Our data identify GIP-regulated metabolic pathways that are targeted by fetal programming.

GIP increases adipose tissue expression and blood levels of MCP-1 in humans and links high energy diets to inflammation: a randomised trial.

AIMS/HYPOTHESIS: Obesity is associated with elevated monocyte chemoattractant protein-1 (MCP-1), a proinflammatory chemokine related to diabetes and cardiovascular disease. Since obesity is triggered by energy dense diets, we hypothesised that nutrient induced intestinal hormones such as glucose-dependent insulinotropic peptide (GIP) may directly stimulate the release of chemokines from adipose tissue and induce low-grade inflammation. METHODS: GIP effects on gene expression and secretion of inflammatory markers were studied by microarray analysis and PCR from human subcutaneous fat biopsies of slightly obese but healthy volunteers in the metabolic ward of German Institute of Human Nutrition, Department of Clinical Nutrition, Potsdam-Rehbrücke. To allocate the participants to the study arms they were numbered in order of their recruitment and then assigned to the groups by a random number generator. In a randomised, single-blind (participants) crossover design, the participants received GIP infusions in postprandial concentrations (2 pmol kg(-1) min(-1)) or saline (154 mmol/l NaCl) infusions for 240 min either alone, in combination with hyperinsulinaemic-euglycaemic (EU) or hyperinsulinaemic-hyperglycaemic (HC) clamps. Possible mechanisms of GIP effects were investigated in single and co-cultures of macrophage and adipocyte cell lines and in primary human monocytes, macrophages and adipocytes. RESULTS: A total of 17 participants were randomised to the following groups: EU with GIP infusion (n = 9); EU with NaCl infusion (n = 9); HC with GIP infusion (n = 8); HC with NaCl infusion (n = 8); sole GIP infusion (n = 11) and sole placebo infusion (n = 11). All 17 individuals were analysed. The study is completed. In human subcutaneous adipose tissue (hSCAT), infusions of GIP significantly increased inflammatory chemokine and cytokine gene networks in transcriptomic microarray analyses. Particularly MCP-1 (180 ± 26%), MCP-2 (246 ± 58%) and IL-6 (234 ± 40%) mRNA levels in adipose tissue as well as circulating plasma concentrations of MCP-1 (165 ± 12 vs 135 ± 13 pg/ml; GIP vs saline after 240 min; p < 0.05 for all variables) in humans increased independently of circulating insulin or glucose plasma concentrations. GIP stimulation increased Mcp-1 mRNA-expression in co-cultures of differentiated 3T3L1-adipocytes and RAW 264.7 macrophages but not in the isolated cell lines. Similarly, GIP increased MCP-1 transcripts in co-cultures of primary human macrophages with human adipocytes. GIP receptor (GIPR) transcripts were present in primary monocytes and the different cell lines and induced activation of extracellular related kinase (ERK) as well as increases in cAMP, indicating functional receptors. CONCLUSIONS/INTERPRETATION: Our findings suggest that the nutrient induced gut hormone GIP may initiate adipose tissue inflammation by triggering a crosstalk of adipocytes and macrophages involving MCP-1. TRIAL REGISTRATION: ClinicalTrials.gov NCT00774488. FUNDING: This work was supported by the German Research Foundation (DFG): grant No. Pf164/021002.

Regulation of nutrition-associated receptors in blood monocytes of normal weight and obese humans.

Obesity, type 2 diabetes and associated metabolic diseases are characterized by low-grade systemic inflammation which involves interplay of nutrition and monocyte/macrophage functions. We suggested that some factors such as nutrient components, neuropeptides involved in the control of gastrointestinal functions, and gastrointestinal hormones might influence immune cell functions and in this way contribute to the disease pathogenesis. The aim of this study was to investigate the mRNA expression of twelve nutrition-associated receptors in peripheral blood mononuclear cells (PBMC), isolated monocytes and monocyte-derived macrophages and their regulation under the switching from the high-carbohydrate low-fat diet to the low-carbohydrate high-fat (LC/HFD) isocaloric diet in healthy humans. The mRNA expression of receptors for short chain fatty acids (GPR41, GPR43), bile acids (TGR5), incretins (GIPR, GLP1R), cholecystokinin (CCKAR), neuropeptides VIP and PACAP (VIPR1, VIPR2), and neurotensin (NTSR1) was detected in PBMC and monocytes, while GPR41, GPR43, GIPR, TGR5, and VIPR1 were found in macrophages. Correlations of the receptor expression in monocytes with a range of metabolic and inflammatory markers were found. In non-obese subjects, the dietary switch to LC/HFD induced the increase of GPR43 and VIPR1 expression in monocytes. No significant differences of receptor expression between normal weight and moderately obese subjects were found. Our study characterized for the first time the expression pattern of nutrition-associated receptors in human blood monocytes and its dietary-induced changes linking metabolic responses to nutrition with immune functions in health and metabolic diseases.

Dietary rapeseed/canola-oil supplementation reduces serum lipids and liver enzymes and alters postprandial inflammatory responses in adipose tissue compared to olive-oil supplementation in obese men.

SCOPE: Obesity is associated with hyperlipidemia, hepatic steatosis, and low-grade inflammation. Studies have shown that MUFA as well as PUFA have beneficial effects on blood lipids and the inflammatory state. METHODS AND RESULTS: This study investigates the effects of a daily supplementation of either 50 g of rapeseed/canola (RA) or olive (OL) oil over 4 wk on serum lipids, serum liver enzymes, and inflammatory gene expression in subcutaneous (s. c.) adipose tissue in obese men. Consuming RA resulted in increased serum n-3 fatty acids and a reduction in total cholesterol, LDL cholesterol, and serum aspartate aminotransferase compared to OL. In s. c. adipose tissue, gene expression of the pro-inflammatory cytokine IL6 was reduced in RA compared to OL. However, after 4 h after a test meal, containing the appropriate oil, white bread, and 400 mL of liquid diet drink (835 kcal in total), gene expression of IL6, IL1B, and EMR1 (egf-like module containing Mucin-like hormone receptor-like 1) was increased in RA and of monocyte chemoattractant protein-1 (CCL2) in both RA and OL. CONCLUSION: This demonstrates that consuming RA for 4 wk improves serum lipids, liver enzymes, and basal inflammation in s. c. adipose tissue, but it mediates an acute pro-inflammatory response in adipose tissue upon consuming a meal.

Evidence for a regulatory role of Cullin-RING E3 ubiquitin ligase 7 in insulin signaling.

Dysfunctional regulation of signaling pathways downstream of the insulin receptor plays a pivotal role in the pathogenesis of insulin resistance and type 2 diabetes. In this study we report both in vitro and in vivo experimental evidence for a role of Cullin-RING E3 ubiquitin ligase 7 (CRL7) in the regulation of insulin signaling and glucose homeostasis. We show that Cul7(-/-) mouse embryonic fibroblasts displayed enhanced AKT and Erk MAP kinase phosphorylation upon insulin stimulation. Depletion of CUL7 by RNA interference in C2C12 myotubes led to increased activation of insulin signaling pathways and cellular glucose uptake, as well as a reduced capacity of these cells to execute insulin-induced degradation of insulin receptor substrate 1 (IRS1). In vivo, heterozygosity of either Cul7 or Fbxw8, both key components of CRL7, resulted in elevated PI3 kinase/AKT activation in skeletal muscle tissue upon insulin stimulation when compared to wild-type controls. Finally, Cul7(+/-) or Fbxw8(+/-) mice exhibited enhanced insulin sensitivity and plasma glucose clearance. Collectively, our findings point to a yet unrecognized role of CRL7 in insulin-mediated control of glucose homeostasis by restraining PI3 kinase/AKT activities in skeletal muscle cells.

The impact of combined use of fall-risk medications and antithrombotics on injury severity and intracranial hemorrhage among older trauma patients.

PURPOSE: Use of fall-risk medications (medications that increase risk of falling in the elderly as defined by Beers criteria, STOPP/START criteria, and other literature) or antithrombotics is common in the elderly, and the impact of their concomitant use should be assessed in regards to fall injuries. The primary objective of this study is to assess the simultaneous outpatient use of fall-risk medications and antithrombotics in elderly fall-patients, and secondarily to analyze the injury severity score and occurrence of intracranial hemorrhage. METHODS: Consecutive chart review at a level 2 trauma center in California, USA from August 01, 2009 to October 31, 2010. Records included 112 patients at least 65 years of age admitted with an outpatient fall. Fisher's exact and Student's t-tests were used (alpha 0.05, two-tailed) to examine prescribing patterns, intracranial hemorrhage occurrence, and injury severity score. Regression adjusted for antithrombotic and fall-risk medication type and number, opiate use, co-morbidities, age, and gender. RESULTS: Thirty-nine percent (44/112) of outpatients were prescribed antithrombotics plus fall-risk medications. The mean injury severity score (ISS) was 13.3 (range 1-26, standard deviation 7.2) for patients taking both medication classes versus 9.7 (range 1-25, standard deviation 7.5) for patients taking antithrombotics alone (p = 0.027). Additionally, in patients over 80 years of age, intracranial hemorrhage occurred more frequently with the use of antithrombotics plus fall-risk medications versus antithrombotics alone (18/29 = 62.1% versus 7/24 = 29.2%, p = 0.027, odds ratio = 3.974, 95% confidence interval = 1.094-15.010). Multivariate analyses showed an independent relationship between intracranial hemorrhage occurrence and type of therapy, as well as injury severity score and simultaneous therapy with fall-risk medications and antithrombotics. CONCLUSION: Simultaneous prescribing of antithrombotics and fall-risk medications is common. For outpatients over 80 years of age, the odds of experiencing a post-fall intracranial hemorrhage are 4 times higher when prescribed antithrombotics plus fall-risk medications compared to antithrombotics alone, and injury severity is higher with combined use of these medication classes.

Update: Methicillin-resistant Staphylococcus aureus screening and decolonization in cardiac surgery.

Methicillin-resistant Staphylococcus aureus (MRSA) has become a concerning multidrug-resistant organism, expanding further outside the hospital setting. Cardiothoracic surgery patients are at an increased risk for mediastinitis and other surgical site infections, which may be further complicated by MRSA. To reduce MRSA surgical site infections, multidisciplinary active surveillance should be implemented in at least high-risk patients, incorporating basic infection control practices, appropriate antibiotic prophylaxis, and decolonization. This article will review the various guidelines, addressing the role of MRSA active surveillance in cardiothoracic surgery, and provide guidance for cardiothoracic surgeons.

Hepatic response to restoration of GLUT4 in skeletal muscle of GLUT4 null mice.

Expression of GLUT4 in fast-twitch skeletal muscle fibers of GLUT4 null mice (G4-MO) normalized glucose uptake in muscle and restored peripheral insulin sensitivity. GLUT4 null mice exhibit altered carbohydrate and lipid metabolism in liver and skeletal muscle. To test the hypothesis that increased glucose utilization by G4-MO muscle would normalize the changes seen in the GLUT4 null liver, serum metabolites and hepatic metabolism were compared in control, GLUT4 null, and G4-MO mice. The fed serum glucose and triglyceride levels of G4-MO mice were similar to those of control mice. In addition, the alternations in liver metabolism seen in GLUT4 nulls including increased GLUT2 expression and fatty acid synthesis accompanied by an increase in the oxidative arm of the pentose phosphate pathway were absent in G4-MO mice. The transgene used for GLUT4 restoration in muscle was specific for fast-twitch muscle fibers. The mitochondria hypertrophy/hyperplasia in all GLUT4 null skeletal muscles was absent in transgene-positive extensor digitorum longus muscle but present in transgene-negative soleus muscle of G4-MO mice. Results of this study suggest that the level of muscle GLUT4 expression influences mitochondrial biogenesis. These studies also demonstrate that the type and amount of substrate that muscle takes up and metabolizes, determined in part by GLUT4 expression levels, play a major role in directing hepatic carbohydrate and lipid metabolism.

Arsenic in drinking water and bladder cancer mortality in the United States: an analysis based on 133 U.S. counties and 30 years of observation.

This study analyzes the relationship between arsenic exposure through drinking water and bladder cancer mortality. The county-specific white male bladder cancer mortality data (1950-1979) and county-specific groundwater arsenic concentration data were obtained for 133 U.S. counties known to be exclusively dependent on groundwater for their public drinking water supply. No arsenic-related increase in bladder cancer mortality was found over the exposure range of 3 to 60 microg/L using stratified analysis and regression analyses (both unweighted and weighted by county population and using both mean and median arsenic concentrations). These results, which provide a direct estimate of arsenic-related cancer risk for U.S. residents, exclude the National Research Council's 2001 risk estimate that was based on Southwest Taiwan data and required adjusting for differences between the body mass and water consumption rates of U.S. and Taiwanese residents.

Critical care of the morbidly obese.

This article describes the special needs of the critically ill morbidly obese, with a focus on the care of the postoperative obesity surgery patient. The technique of surgery is described elsewhere in this journal. Details of nursing care complicated by obesity are discussed. Environment of care modifications required for routine care of the morbidly obese in critical care are detailed. Pharmacokinetic factors to be considered are reviewed. A case study is presented to coalesce concepts presented.

Bladder cancer and arsenic exposure: differences in the two populations enrolled in a study in southwest Taiwan.

OBJECTIVE: Analyses of bladder cancer mortality in the Black Foot Disease (BFD) endemic area of southwest Taiwan conducted by Morales et al. showed a discontinuity in risk at 400 microg/L arsenic in the drinking water in a stratified analysis and no discontinuity in a continuous analysis. As the continuous analysis presentation had been used by both the NRC and the EPA to assess the carcinogenic risk from arsenic ingestion, an explanation of the discontinuity was sought. METHODS: Review of 40 years of published health studies of the BFD-endemic area of SW Taiwan showed that earlier publications had limited their cancer associations with arsenic levels in artesian well waters and that the reports of Morales et al., NRC, and EPA failed to do so. Underlying data for the Morales et al. study were obtained from the appendix to the NRC report. Bladder cancer mortality rates were calculated from case counts and person-years of observation for each study village. Villages were categorized by water source according to the descriptions from the underlying study. Graphic and regression analyses were conducted of the bladder cancer mortality rates using exposure as a continuous variable and simultaneously stratifying by water source. RESULTS: The median village well arsenic levels ranged from 350 to 934 microg/L for villages solely dependent on artesian well water and from 10 to 717 microg/L for villages not solely dependent on artesian well water. Bladder cancer mortality rates were found to be dependent upon the arsenic level only for those villages that were solely dependent on artesian well water for their water source. Bladder cancer mortality rates were found to be independent of arsenic level for villages with non-artesian well water sources. CONCLUSIONS: The data indicate that arsenic exposure levels do not explain the bladder cancer mortality risk in SW Taiwan among villages not dependent upon artesian well water. The association for villages dependent upon artesian well water may be explained either by arsenic acting as a high-dose carcinogen or in artesian well water as a co-carcinogen with some other aspect of artesian well water (possibly humic acid). Arsenic exposure level alone appears to be an insufficient exposure measure to describe the risk of bladder cancer mortality in the BFD-endemic area. Risk analyses that fail to take water source into account are likely to misrepresent the risk characterization, particularly at low arsenic levels.