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1.  Hepatic Insulin Clearance Is Closely Related to Metabolic Syndrome Components 
Diabetes Care  2013;36(11):3779-3785.
OBJECTIVE
Insulin clearance is decreased in type 2 diabetes mellitus (T2DM) for unknown reasons. Subjects with metabolic syndrome are hyperinsulinemic and have an increased risk of T2DM. We aimed to investigate the relationship between hepatic insulin clearance (HIC) and different components of metabolic syndrome and tested the hypothesis that HIC may predict the risk of metabolic syndrome.
RESEARCH DESIGN AND METHODS
Individuals without diabetes from the Metabolic Syndrome Berlin Brandenburg (MeSyBePo) study (800 subjects with the baseline examination and 189 subjects from the MeSyBePo recall study) underwent an oral glucose tolerance test (OGTT) with assessment of insulin secretion (insulin secretion rate [ISR]) and insulin sensitivity. Two indices of HIC were calculated.
RESULTS
Both HIC indices showed lower values in subjects with metabolic syndrome (P < 0.001) at baseline. HIC indices correlate inversely with waist circumference, diastolic blood pressure, fasting glucose, triglycerides, and OGTT-derived insulin secretion index. During a mean follow-up of 5.1 ± 0.9 years, 47 individuals developed metabolic syndrome and 33 subjects progressed to impaired glucose metabolism. Both indices of HIC showed a trend of an association with increased risk of metabolic syndrome (HICC-peptide odds ratio 1.13 [95% CI 0.97–1.31], P = 0.12, and HICISR 1.38 [0.88–2.17], P = 0.16) and impaired glucose metabolism (HICC-peptide 1.12 [0.92–1.36], P = 0.26, and HICISR 1.31 [0.74–2.33] P = 0.36), although point estimates reached no statistical significance.
CONCLUSIONS
HIC was associated with different components of metabolic syndrome and markers of insulin secretion and insulin sensitivity. Decreased HIC may represent a novel pathophysiological mechanism of the metabolic syndrome, which may be used additionally for early identification of high-risk subjects.
doi:10.2337/dc12-1203
PMCID: PMC3816867  PMID: 24026549
2.  Fibroblast Growth Factor 21 Mediates Specific Glucagon Actions 
Diabetes  2013;62(5):1453-1463.
Glucagon, an essential regulator of glucose homeostasis, also modulates lipid metabolism and promotes weight loss, as reflected by the wasting observed in glucagonoma patients. Recently, coagonist peptides that include glucagon agonism have emerged as promising therapeutic candidates for the treatment of obesity and diabetes. We developed a novel stable and soluble glucagon receptor (GcgR) agonist, which allowed for in vivo dissection of glucagon action. As expected, chronic GcgR agonism in mice resulted in hyperglycemia and lower body fat and plasma cholesterol. Notably, GcgR activation also raised hepatic expression and circulating levels of fibroblast growth factor 21 (FGF21). This effect was retained in isolated primary hepatocytes from wild-type (WT) mice, but not GcgR knockout mice. We confirmed this link in healthy human volunteers, where injection of natural glucagon increased plasma FGF21 within hours. Functional relevance was evidenced in mice with genetic deletion of FGF21, where GcgR activation failed to induce the body weight loss and lipid metabolism changes observed in WT mice. Taken together, these data reveal for the first time that glucagon controls glucose, energy, and lipid metabolism at least in part via FGF21-dependent pathways.
doi:10.2337/db12-1116
PMCID: PMC3636653  PMID: 23305646
3.  Rationale and cross-sectional study design of the Research on Obesity and type 2 Diabetes among African Migrants: the RODAM study 
BMJ Open  2014;4(3):e004877.
Introduction
Obesity and type 2 diabetes (T2D) are highly prevalent among African migrants compared with European descent populations. The underlying reasons still remain a puzzle. Gene–environmental interaction is now seen as a potential plausible factor contributing to the high prevalence of obesity and T2D, but has not yet been investigated. The overall aim of the Research on Obesity and Diabetes among African Migrants (RODAM) project is to understand the reasons for the high prevalence of obesity and T2D among sub-Saharan Africans in diaspora by (1) studying the complex interplay between environment (eg, lifestyle), healthcare, biochemical and (epi)genetic factors, and their relative contributions to the high prevalence of obesity and T2D; (2) to identify specific risk factors within these broad categories to guide intervention programmes and (3) to provide a basic knowledge for improving diagnosis and treatment.
Methods and analysis
RODAM is a multicentre cross-sectional study among homogenous sub-Saharan African participants (ie, Ghanaians) aged >25 years living in rural and urban Ghana, the Netherlands, Germany and the UK (http://rod-am.eu/). Standardised data on the main outcomes, genetic and non-genetic factors are collected in all locations. The aim is to recruit 6250 individuals comprising five subgroups of 1250 individuals from each site. In Ghana, Kumasi and Obuasi (urban stratum) and villages in the Ashanti region (rural stratum) are served as recruitment sites. In Europe, Ghanaian migrants are selected through the municipality or Ghanaian organisations registers.
Ethics and dissemination
Ethical approval has been obtained in all sites. This paper gives an overview of the rationale, conceptual framework and methods of the study. The differences across locations will allow us to gain insight into genetic and non-genetic factors contributing to the occurrence of obesity and T2D and will inform targeted intervention and prevention programmes, and provide the basis for improving diagnosis and treatment in these populations and beyond.
doi:10.1136/bmjopen-2014-004877
PMCID: PMC3963103  PMID: 24657884
Epidemiology
4.  Inflammation-Induced Acute Phase Response in Skeletal Muscle and Critical Illness Myopathy 
PLoS ONE  2014;9(3):e92048.
Objectives
Systemic inflammation is a major risk factor for critical-illness myopathy (CIM) but its pathogenic role in muscle is uncertain. We observed that interleukin 6 (IL-6) and serum amyloid A1 (SAA1) expression was upregulated in muscle of critically ill patients. To test the relevance of these responses we assessed inflammation and acute-phase response at early and late time points in muscle of patients at risk for CIM.
Design
Prospective observational clinical study and prospective animal trial.
Setting
Two intensive care units (ICU) and research laboratory.
Patients/Subjects
33 patients with Sequential Organ Failure Assessment scores ≥8 on 3 consecutive days within 5 days in ICU were investigated. A subgroup analysis of 12 patients with, and 18 patients without CIM (non-CIM) was performed. Two consecutive biopsies from vastus lateralis were obtained at median days 5 and 15, early and late time points. Controls were 5 healthy subjects undergoing elective orthopedic surgery. A septic mouse model and cultured myoblasts were used for mechanistic analyses.
Measurements and Main Results
Early SAA1 expression was significantly higher in skeletal muscle of CIM compared to non-CIM patients. Immunohistochemistry showed SAA1 accumulations in muscle of CIM patients at the early time point, which resolved later. SAA1 expression was induced by IL-6 and tumor necrosis factor-alpha in human and mouse myocytes in vitro. Inflammation-induced muscular SAA1 accumulation was reproduced in a sepsis mouse model.
Conclusions
Skeletal muscle contributes to general inflammation and acute-phase response in CIM patients. Muscular SAA1 could be important for CIM pathogenesis.
Trial Registration
ISRCTN77569430.
doi:10.1371/journal.pone.0092048
PMCID: PMC3961297  PMID: 24651840
5.  Fibroblast Growth Factor 21 Predicts the Metabolic Syndrome and Type 2 Diabetes in Caucasians 
Diabetes Care  2012;36(1):145-149.
OBJECTIVE
The incidence of the metabolic syndrome and type 2 diabetes mellitus (T2DM) is rising worldwide. Liver-derived fibroblast growth factor (FGF)-21 affects glucose and lipid metabolism. The aim of this study was to analyze the predictive value of FGF-21 on the incidence of T2DM and the metabolic syndrome.
RESEARCH DESIGN AND METHODS
The Metabolic Syndrome Berlin Potsdam (MeSyBePo) recall study includes 440 individuals. Glucose metabolism was analyzed using an oral glucose tolerance test, including insulin measurements. FGF-21 was measured using enzyme-linked immunosorbent assay. Primary study outcome was diabetes and the metabolic syndrome incidence and change of glucose subtraits.
RESULTS
During a mean follow-up of 5.30 ± 0.1 years, 54 individuals developed the metabolic syndrome, 35 developed T2DM, and 69 with normal glucose tolerance at baseline progressed to impaired glucose metabolism, defined as impaired fasting glucose, impaired glucose tolerance, or T2DM. FGF-21 predicted incident metabolic syndrome (lnFGF-21 odds ratio [OR] 2.6 [95% CI 1.5 – 4.5]; P = 0.001), T2DM (2.4 [1.2–4.7]; P = 0.01), and progression to impaired glucose metabolism (2.2 [1.3 – 3.6]; P = 0.002) after adjustment for age, sex, BMI, and follow-up time. Additional adjustment for waist-to-hip ratio, systolic blood pressure, HDL cholesterol, triglycerides, and fasting glucose did not substantially modify the predictive value of FGF-21.
CONCLUSIONS
FGF-21 is an independent predictor of the metabolic syndrome and T2DM in apparently healthy Caucasians. These results may indicate FGF-21 resistance precedes the onset of the metabolic syndrome and T2DM.
doi:10.2337/dc12-0703
PMCID: PMC3526237  PMID: 22933429
6.  Caloric Restriction Chronically Impairs Metabolic Programming in Mice 
Diabetes  2012;61(11):2734-2742.
Although obesity rates are rapidly rising, caloric restriction remains one of the few safe therapies. Here we tested the hypothesis that obesity-associated disorders are caused by increased adipose tissue as opposed to excess dietary lipids. Fat mass (FM) of lean C57B6 mice fed a high-fat diet (HFD; FMC mice) was “clamped” to match the FM of mice maintained on a low-fat diet (standard diet [SD] mice). FMC mice displayed improved glucose and insulin tolerance as compared with ad libitum HFD mice (P < 0.001) or SD mice (P < 0.05). These improvements were associated with fewer signs of inflammation, consistent with the less-impaired metabolism. In follow-up studies, diet-induced obese mice were food restricted for 5 weeks to achieve FM levels identical with those of age-matched SD mice. Previously, obese mice exhibited improved glucose and insulin tolerance but showed markedly increased fasting-induced hyperphagia (P < 0.001). When mice were given ad libitum access to the HFD, the hyperphagia of these mice led to accelerated body weight gain as compared with otherwise matched controls without a history of obesity. These results suggest that although caloric restriction on a HFD provides metabolic benefits, maintaining those benefits may require lifelong continuation, at least in individuals with a history of obesity.
doi:10.2337/db11-1621
PMCID: PMC3478536  PMID: 22787140
7.  Glucose-Dependent Insulinotropic Polypeptide Reduces Fat-Specific Expression and Activity of 11β-Hydroxysteroid Dehydrogenase Type 1 and Inhibits Release of Free Fatty Acids 
Diabetes  2012;61(2):292-300.
Glucose-dependent insulinotropic polypeptide (GIP) has been suggested to have direct effects on nonislet tissues. GIP also reportedly increased glucose uptake and inhibition of lipolysis in adipocytes after inhibition of the intracellular cortisone-cortisol shuttle 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). We here analyzed whether GIP modifies lipid metabolism and further elucidated the relation between GIP, 11β-HSD1, and fatty acid metabolism. GIP reduced activity of 11β-HSD1 promoter constructs and the expression and activity of 11β-HSD1 in differentiated 3T3-L1 adipocytes in a time- and dose-dependent fashion. This was paralleled by a reduction of free fatty acid (FFA) release and a reduced expression of key enzymes regulating lipolysis in adipose tissue. Preinhibition of 11β-HSD1 completely abolished GIP-induced effects on FFA release. To investigate the acute effects of GIP in humans, a randomized clinical trial was performed. GIP lowered circulating FFAs compared with saline control and reduced expression and ex vivo activity of 11β-HSD1 and adipose triglyceride lipase expression in subcutaneous fat biopsies. Our data suggest that GIP reduces FFA release from adipose tissue by inhibition of lipolysis or by increased reesterification. This process appears to depend on a modification of 11β-HSD1 activity. In general, the presented data support that GIP has direct and insulin-independent effects on adipose tissue.
doi:10.2337/db10-0902
PMCID: PMC3266397  PMID: 22179810
8.  Histone Deacetylase 6 (HDAC6) Is an Essential Modifier of Glucocorticoid-Induced Hepatic Gluconeogenesis 
Diabetes  2012;61(2):513-523.
In the current study, we investigated the importance of histone deacetylase (HDAC)6 for glucocorticoid receptor–mediated effects on glucose metabolism and its potential as a therapeutic target for the prevention of glucocorticoid-induced diabetes. Dexamethasone-induced hepatic glucose output and glucocorticoid receptor translocation were analyzed in wild-type (wt) and HDAC6-deficient (HDAC6KO) mice. The effect of the specific HDAC6 inhibitor tubacin was analyzed in vitro. wt and HDAC6KO mice were subjected to 3 weeks’ dexamethasone treatment before analysis of glucose and insulin tolerance. HDAC6KO mice showed impaired dexamethasone-induced hepatic glucocorticoid receptor translocation. Accordingly, dexamethasone-induced expression of a large number of hepatic genes was significantly attenuated in mice lacking HDAC6 and by tubacin in vitro. Glucose output of primary hepatocytes from HDAC6KO mice was diminished. A significant improvement of dexamethasone-induced whole-body glucose intolerance as well as insulin resistance in HDAC6KO mice compared with wt littermates was observed. This study demonstrates that HDAC6 is an essential regulator of hepatic glucocorticoid-stimulated gluconeogenesis and impairment of whole-body glucose metabolism through modification of glucocorticoid receptor nuclear translocation. Selective pharmacological inhibition of HDAC6 may provide a future therapeutic option against the prodiabetogenic actions of glucocorticoids.
doi:10.2337/db11-0313
PMCID: PMC3266407  PMID: 22210316
9.  Sexual Dimorphic Regulation of Body Weight Dynamics and Adipose Tissue Lipolysis 
PLoS ONE  2012;7(5):e37794.
Background
Successful reduction of body weight (BW) is often followed by recidivism to obesity. BW-changes including BW-loss and -regain is associated with marked alterations in energy expenditure (EE) and adipose tissue (AT) metabolism. Since these processes are sex-specifically controlled, we investigated sexual dimorphisms in metabolic processes during BW-dynamics (gain-loss-regain).
Research Design
Obesity was induced in C57BL/6J male (m) and female (f) mice by 15 weeks high-fat diet (HFD) feeding. Subsequently BW was reduced (-20%) by caloric restriction (CR) followed by adaptive feeding, and a regain-phase. Measurement of EE, body composition, blood/organ sampling were performed after each feeding period. Lipolysis was analyzed ex-vivo in gonadal AT.
Results
Male mice exhibited accelerated BW-gain compared to females (relative BW-gain m:140.5±3.2%; f:103.7±6.5%; p<0.001). In consonance, lean mass-specific EE was significantly higher in females compared to males during BW-gain. Under CR female mice reached their target-BW significantly faster than male mice (m:12.2 days; f:7.6 days; p<0.001) accompanied by a sustained sex-difference in EE. In addition, female mice predominantly downsized gonadal AT whereas the relation between gonadal and total body fat was not altered in males. Accordingly, only females exhibited an increased rate of forskolin-stimulated lipolysis in AT associated with significantly higher glycerol concentrations, lower RER-values, and increased AT expression of adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL). Analysis of AT lipolysis in estrogen receptor alpha (ERα)–deficient mice revealed a reduced lipolytic rate in the absence of ERα exclusively in females. Finally, re-feeding caused BW-regain faster in males than in females.
Conclusion
The present study shows sex-specific dynamics during BW-gain-loss-regain. Female mice responded to CR with an increase in lipolytic activity, and augmented lipid-oxidation leading to more efficient weight loss. These processes likely involve ERα-dependent signaling in AT and sexual dimorphic regulation of genes involved in lipid metabolism.
doi:10.1371/journal.pone.0037794
PMCID: PMC3360591  PMID: 22662224
10.  Diabetes mellitus type 2 in urban Ghana: characteristics and associated factors 
BMC Public Health  2012;12:210.
Background
Sub-Saharan Africa faces a rapid spread of diabetes mellitus type 2 (DM2) but its potentially specific characteristics are inadequately defined. In this hospital-based study in Kumasi, Ghana, we aimed at characterizing clinical, anthropometric, socio-economic, nutritional and behavioural parameters of DM2 patients and at identifying associated factors.
Methods
Between August 2007 and June 2008, 1466 individuals were recruited from diabetes and hypertension clinics, outpatients, community, and hospital staff. Fasting plasma glucose (FPG), serum lipids and urinary albumin were measured. Physical examination, anthropometry, and interviews on medical history, socio-economic status (SES), physical activity and nutritional behaviour were performed.
Results
The majority of the 675 DM2 patients (mean FPG, 8.31 mmol/L) was female (75%) and aged 40-60 years (mean, 55 years). DM2 was known in 97% of patients, almost all were on medication. Many had hypertension (63%) and microalbuminuria (43%); diabetic complications occurred in 20%. Overweight (body mass index > 25 kg/m2), increased body fat (> 20% (male), > 33% (female)), and central adiposity (waist-to-hip ratio > 0.90 (male), > 0.85 (female)) were frequent occurring in 53%, 56%, and 75%, respectively. Triglycerides were increased (≥ 1.695 mmol/L) in 31% and cholesterol (≥ 5.17 mmol/L) in 65%. Illiteracy (46%) was high and SES indicators generally low. Factors independently associated with DM2 included a diabetes family history (adjusted odds ratio (aOR), 3.8; 95% confidence interval (95%CI), 2.6-5.5), abdominal adiposity (aOR, 2.6; 95%CI, 1.8-3.9), increased triglycerides (aOR, 1.8; 95%CI, 1.1-3.0), and also several indicators of low SES.
Conclusions
In this study from urban Ghana, DM2 affects predominantly obese patients of rather low socio-economic status and frequently is accompanied by hypertension and hyperlipidaemia. Prevention and management need to account for a specific risk profile in this population.
doi:10.1186/1471-2458-12-210
PMCID: PMC3364878  PMID: 22429713
11.  Deletion of the Mammalian INDY Homologue Mimics Aspects of Dietary Restriction and Protects Against Adiposity and Insulin Resistance in Mice 
Cell metabolism  2011;14(2):184-195.
SUMMARY
Reduced expression of the Indy (= I am Not Dead, Yet) gene in D. melanogaster and C. elegans prolongs life span, and in D. melanogaster augments mitochondrial biogenesis in a manner akin to caloric restriction. However, the cellular mechanism by which Indy does this is unknown. Here, we report on the knockout-mouse model of the mammalian Indy (mIndy) homologue, SLC13A5. Deletion of mIndy in mice (mINDY−/− mice) reduces hepatocellular ATP/ADP ratio, activates hepatic AMPK, induces PGC-1α, inhibits ACC-2, and reduces SREBP-1c levels. This signaling network promotes hepatic mitochondrial biogenesis, lipid oxidation, and energy expenditure and attenuates hepatic de novo lipogenesis. Together, these traits protect mINDY−/− mice from the adiposity and insulin resistance that evolve with high-fat feeding and aging. Our studies demonstrate a profound effect of mIndy on mammalian energy metabolism and suggest that mINDY might be a therapeutic target for the treatment of obesity and type 2 diabetes.
doi:10.1016/j.cmet.2011.06.009
PMCID: PMC3163140  PMID: 21803289
12.  Attachment style contributes to the outcome of a multimodal lifestyle intervention 
Background & Aims
The long-term success of life-style interventions in the treatment of obesity is limited. Although psychological factors have been suggested to modify therapeutic effects, specifically the implications of attachment styles and the patient-therapist relationship have not been examined in detail yet.
Methods
This study included 44 obese patients who participated in a one-year multimodal weight-reduction program. Attachment style was analyzed by the Adult Attachment Prototype Rating (AAPR) inventory and its relation to a one-year weight reduction program was studied. The patient-therapist-relationship was assessed using the Helping Alliance Questionnaire.
Results
Attachment style was secure in 68% of participants and insecure (preoccupied and dismissing) in 32%. Interestingly a significantly higher weight-reduction was found in securely (SAI) compared to insecurely attached individuals (UAI; p < 0.05). This estimation correlated positively also to the quality of helping alliance (p = 0.004).
Conclusions
The frequency of insecure attachment in obese individuals was comparable to that of the normal population. Our data suggest a greater weight-reduction for SAI than for UAI, and the patient-therapist relationship was rated more positively. The conclusion can be drawn that a patient's attachment style plays a role in an interdisciplinary treatment program for obesity and has an influence on the effort to lose weight.
doi:10.1186/1751-0759-6-3
PMCID: PMC3296567  PMID: 22300715
attachment style; obesity; patient-therapist relationship; weight reduction
13.  A distinct metabolic signature predicts development of fasting plasma glucose 
Background
High blood glucose and diabetes are amongst the conditions causing the greatest losses in years of healthy life worldwide. Therefore, numerous studies aim to identify reliable risk markers for development of impaired glucose metabolism and type 2 diabetes. However, the molecular basis of impaired glucose metabolism is so far insufficiently understood. The development of so called 'omics' approaches in the recent years promises to identify molecular markers and to further understand the molecular basis of impaired glucose metabolism and type 2 diabetes. Although univariate statistical approaches are often applied, we demonstrate here that the application of multivariate statistical approaches is highly recommended to fully capture the complexity of data gained using high-throughput methods.
Methods
We took blood plasma samples from 172 subjects who participated in the prospective Metabolic Syndrome Berlin Potsdam follow-up study (MESY-BEPO Follow-up). We analysed these samples using Gas Chromatography coupled with Mass Spectrometry (GC-MS), and measured 286 metabolites. Furthermore, fasting glucose levels were measured using standard methods at baseline, and after an average of six years. We did correlation analysis and built linear regression models as well as Random Forest regression models to identify metabolites that predict the development of fasting glucose in our cohort.
Results
We found a metabolic pattern consisting of nine metabolites that predicted fasting glucose development with an accuracy of 0.47 in tenfold cross-validation using Random Forest regression. We also showed that adding established risk markers did not improve the model accuracy. However, external validation is eventually desirable. Although not all metabolites belonging to the final pattern are identified yet, the pattern directs attention to amino acid metabolism, energy metabolism and redox homeostasis.
Conclusions
We demonstrate that metabolites identified using a high-throughput method (GC-MS) perform well in predicting the development of fasting plasma glucose over several years. Notably, not single, but a complex pattern of metabolites propels the prediction and therefore reflects the complexity of the underlying molecular mechanisms. This result could only be captured by application of multivariate statistical approaches. Therefore, we highly recommend the usage of statistical methods that seize the complexity of the information given by high-throughput methods.
doi:10.1186/2043-9113-2-3
PMCID: PMC3298809  PMID: 22300499
prediction; fasting glucose; type 2 diabetes; metabolomics; plasma; random forest; metabolite; regression; biomarker
14.  A Polymorphism Within the Connective Tissue Growth Factor (CTGF) Gene has No Effect on Non-Invasive Markers of Beta-Cell Area and Risk of Type 2 Diabetes 
Disease markers  2011;31(4):241-246.
Chromosomal locus 6q23 is strongly linked to type 2 diabetes (T2DM) and related features including insulin secretion in various ethnic populations. Connective tissue growth factor (CTGF) gene is an interesting T2DM candidate gene in this chromosome region. CTGF is a key mediator of progressive pancreatic fibrosis up-regulated in type 2 diabetes. In contrast, CTGF inactivation in mice compromises islet cell proliferation during embryogenesis. The aim of our study was to investigate an impact of CTGF genetic variation on pancreatic beta-cell function and T2DM pathogenesis. We studied the effect of a common CTGF polymorphism rs9493150 on the risk of the T2DM development in three independent German cohorts. Specifically, the association between CTGF polymorphism and non-invasive markers of beta-cell area derived from oral glucose tolerance test was studied in subjects without diabetes. Neither in the Metabolic Syndrome Berlin Potsdam (MESYBEPO) study (n = 1026) (OR = 0.637, CI (0.387–1.050); p = 0.077) nor in the European Prospective Investigation into Cancer and Nutrition-Potsdam (EPIC-Potsdam) (n = 3049) cohort (RR = 0.77 CI (0.49–1.20), p = 0.249 for the recessive homozygote in general model), a significant association with increased diabetes risk was observed. The risk allele of rs9493150 had also no effect on markers of beta-cell area in the combined analysis of the MESYBEPO and Tübingen Family Study (n = 1826). In conclusion, the polymorphism rs9493150 in the 5’-untranslated region of the CTGF gene has no association with T2DM risk and surrogate markers of beta-cell area.
doi:10.3233/DMA-2011-0823
PMCID: PMC3826927  PMID: 22045431
Genetic association; connective tissue growth factor gene; C-peptide; blood glucose; beta-cell mass; type 2 diabetes mellitus
15.  Skeletal Muscle 11beta-HSD1 Controls Glucocorticoid-Induced Proteolysis and Expression of E3 Ubiquitin Ligases Atrogin-1 and MuRF-1 
PLoS ONE  2011;6(1):e16674.
Recent studies demonstrated expression and activity of the intracellular cortisone-cortisol shuttle 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in skeletal muscle and inhibition of 11beta-HSD1 in muscle cells improved insulin sensitivity. Glucocorticoids induce muscle atrophy via increased expression of the E3 ubiquitin ligases Atrogin-1 (Muscle Atrophy F-box (MAFbx)) and MuRF-1 (Muscle RING-Finger-1). We hypothesized that 11beta-HSD1 controls glucocorticoid-induced expression of atrophy E3 ubiquitin ligases in skeletal muscle. Primary human myoblasts were generated from healthy volunteers. 11beta-HSD1-dependent protein degradation was analyzed by [3H]-tyrosine release assay. RT-PCR was used to determine mRNA expression of E3 ubiquitin ligases and 11beta-HSD1 activity was measured by conversion of radioactively labeled [3H]-cortisone to [3H]-cortisol separated by thin-layer chromatography. We here demonstrate that 11beta-HSD1 is expressed and biologically active in interconverting cortisone to active cortisol in murine skeletal muscle cells (C2C12) as well as in primary human myotubes. 11beta-HSD1 expression increased during differentiation from myoblasts to mature myotubes (p<0.01), suggesting a role of 11beta-HSD1 in skeletal muscle growth and differentiation. Treatment with cortisone increased protein degradation by about 20% (p<0.001), which was paralleled by an elevation of Atrogin-1 and MuRF-1 mRNA expression (p<0.01, respectively). Notably, pre-treatment with the 11beta-HSD1 inhibitor carbenoxolone (Cbx) completely abolished the effect of cortisone on protein degradation as well as on Atrogin-1 and MuRF-1 expression. In summary, our data suggest that 11beta-HSD1 controls glucocorticoid-induced protein degradation in human and murine skeletal muscle via regulation of the E3 ubiquitin ligases Atrogin-1 and MuRF-1.
doi:10.1371/journal.pone.0016674
PMCID: PMC3031623  PMID: 21304964
16.  New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk 
Dupuis, Josée | Langenberg, Claudia | Prokopenko, Inga | Saxena, Richa | Soranzo, Nicole | Jackson, Anne U | Wheeler, Eleanor | Glazer, Nicole L | Bouatia-Naji, Nabila | Gloyn, Anna L | Lindgren, Cecilia M | Mägi, Reedik | Morris, Andrew P | Randall, Joshua | Johnson, Toby | Elliott, Paul | Rybin, Denis | Thorleifsson, Gudmar | Steinthorsdottir, Valgerdur | Henneman, Peter | Grallert, Harald | Dehghan, Abbas | Hottenga, Jouke Jan | Franklin, Christopher S | Navarro, Pau | Song, Kijoung | Goel, Anuj | Perry, John R B | Egan, Josephine M | Lajunen, Taina | Grarup, Niels | Sparsø, Thomas | Doney, Alex | Voight, Benjamin F | Stringham, Heather M | Li, Man | Kanoni, Stavroula | Shrader, Peter | Cavalcanti-Proença, Christine | Kumari, Meena | Qi, Lu | Timpson, Nicholas J | Gieger, Christian | Zabena, Carina | Rocheleau, Ghislain | Ingelsson, Erik | An, Ping | O’Connell, Jeffrey | Luan, Jian'an | Elliott, Amanda | McCarroll, Steven A | Payne, Felicity | Roccasecca, Rosa Maria | Pattou, François | Sethupathy, Praveen | Ardlie, Kristin | Ariyurek, Yavuz | Balkau, Beverley | Barter, Philip | Beilby, John P | Ben-Shlomo, Yoav | Benediktsson, Rafn | Bennett, Amanda J | Bergmann, Sven | Bochud, Murielle | Boerwinkle, Eric | Bonnefond, Amélie | Bonnycastle, Lori L | Borch-Johnsen, Knut | Böttcher, Yvonne | Brunner, Eric | Bumpstead, Suzannah J | Charpentier, Guillaume | Chen, Yii-Der Ida | Chines, Peter | Clarke, Robert | Coin, Lachlan J M | Cooper, Matthew N | Cornelis, Marilyn | Crawford, Gabe | Crisponi, Laura | Day, Ian N M | de Geus, Eco | Delplanque, Jerome | Dina, Christian | Erdos, Michael R | Fedson, Annette C | Fischer-Rosinsky, Antje | Forouhi, Nita G | Fox, Caroline S | Frants, Rune | Franzosi, Maria Grazia | Galan, Pilar | Goodarzi, Mark O | Graessler, Jürgen | Groves, Christopher J | Grundy, Scott | Gwilliam, Rhian | Gyllensten, Ulf | Hadjadj, Samy | Hallmans, Göran | Hammond, Naomi | Han, Xijing | Hartikainen, Anna-Liisa | Hassanali, Neelam | Hayward, Caroline | Heath, Simon C | Hercberg, Serge | Herder, Christian | Hicks, Andrew A | Hillman, David R | Hingorani, Aroon D | Hofman, Albert | Hui, Jennie | Hung, Joe | Isomaa, Bo | Johnson, Paul R V | Jørgensen, Torben | Jula, Antti | Kaakinen, Marika | Kaprio, Jaakko | Kesaniemi, Y Antero | Kivimaki, Mika | Knight, Beatrice | Koskinen, Seppo | Kovacs, Peter | Kyvik, Kirsten Ohm | Lathrop, G Mark | Lawlor, Debbie A | Le Bacquer, Olivier | Lecoeur, Cécile | Li, Yun | Lyssenko, Valeriya | Mahley, Robert | Mangino, Massimo | Manning, Alisa K | Martínez-Larrad, María Teresa | McAteer, Jarred B | McCulloch, Laura J | McPherson, Ruth | Meisinger, Christa | Melzer, David | Meyre, David | Mitchell, Braxton D | Morken, Mario A | Mukherjee, Sutapa | Naitza, Silvia | Narisu, Narisu | Neville, Matthew J | Oostra, Ben A | Orrù, Marco | Pakyz, Ruth | Palmer, Colin N A | Paolisso, Giuseppe | Pattaro, Cristian | Pearson, Daniel | Peden, John F | Pedersen, Nancy L. | Perola, Markus | Pfeiffer, Andreas F H | Pichler, Irene | Polasek, Ozren | Posthuma, Danielle | Potter, Simon C | Pouta, Anneli | Province, Michael A | Psaty, Bruce M | Rathmann, Wolfgang | Rayner, Nigel W | Rice, Kenneth | Ripatti, Samuli | Rivadeneira, Fernando | Roden, Michael | Rolandsson, Olov | Sandbaek, Annelli | Sandhu, Manjinder | Sanna, Serena | Sayer, Avan Aihie | Scheet, Paul | Scott, Laura J | Seedorf, Udo | Sharp, Stephen J | Shields, Beverley | Sigurðsson, Gunnar | Sijbrands, Erik J G | Silveira, Angela | Simpson, Laila | Singleton, Andrew | Smith, Nicholas L | Sovio, Ulla | Swift, Amy | Syddall, Holly | Syvänen, Ann-Christine | Tanaka, Toshiko | Thorand, Barbara | Tichet, Jean | Tönjes, Anke | Tuomi, Tiinamaija | Uitterlinden, André G | van Dijk, Ko Willems | van Hoek, Mandy | Varma, Dhiraj | Visvikis-Siest, Sophie | Vitart, Veronique | Vogelzangs, Nicole | Waeber, Gérard | Wagner, Peter J | Walley, Andrew | Walters, G Bragi | Ward, Kim L | Watkins, Hugh | Weedon, Michael N | Wild, Sarah H | Willemsen, Gonneke | Witteman, Jaqueline C M | Yarnell, John W G | Zeggini, Eleftheria | Zelenika, Diana | Zethelius, Björn | Zhai, Guangju | Zhao, Jing Hua | Zillikens, M Carola | Borecki, Ingrid B | Loos, Ruth J F | Meneton, Pierre | Magnusson, Patrik K E | Nathan, David M | Williams, Gordon H | Hattersley, Andrew T | Silander, Kaisa | Salomaa, Veikko | Smith, George Davey | Bornstein, Stefan R | Schwarz, Peter | Spranger, Joachim | Karpe, Fredrik | Shuldiner, Alan R | Cooper, Cyrus | Dedoussis, George V | Serrano-Ríos, Manuel | Morris, Andrew D | Lind, Lars | Palmer, Lyle J | Hu, Frank B. | Franks, Paul W | Ebrahim, Shah | Marmot, Michael | Kao, W H Linda | Pankow, James S | Sampson, Michael J | Kuusisto, Johanna | Laakso, Markku | Hansen, Torben | Pedersen, Oluf | Pramstaller, Peter Paul | Wichmann, H Erich | Illig, Thomas | Rudan, Igor | Wright, Alan F | Stumvoll, Michael | Campbell, Harry | Wilson, James F | Hamsten, Anders | Bergman, Richard N | Buchanan, Thomas A | Collins, Francis S | Mohlke, Karen L | Tuomilehto, Jaakko | Valle, Timo T | Altshuler, David | Rotter, Jerome I | Siscovick, David S | Penninx, Brenda W J H | Boomsma, Dorret | Deloukas, Panos | Spector, Timothy D | Frayling, Timothy M | Ferrucci, Luigi | Kong, Augustine | Thorsteinsdottir, Unnur | Stefansson, Kari | van Duijn, Cornelia M | Aulchenko, Yurii S | Cao, Antonio | Scuteri, Angelo | Schlessinger, David | Uda, Manuela | Ruokonen, Aimo | Jarvelin, Marjo-Riitta | Waterworth, Dawn M | Vollenweider, Peter | Peltonen, Leena | Mooser, Vincent | Abecasis, Goncalo R | Wareham, Nicholas J | Sladek, Robert | Froguel, Philippe | Watanabe, Richard M | Meigs, James B | Groop, Leif | Boehnke, Michael | McCarthy, Mark I | Florez, Jose C | Barroso, Inês
Nature genetics  2010;42(2):105-116.
Circulating glucose levels are tightly regulated. To identify novel glycemic loci, we performed meta-analyses of 21 genome-wide associations studies informative for fasting glucose (FG), fasting insulin (FI) and indices of β-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 non-diabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with FG/HOMA-B and two associated with FI/HOMA-IR. These include nine new FG loci (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and FAM148B) and one influencing FI/HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB/TMEM195 with type 2 diabetes (T2D). Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify T2D risk loci, as well as loci that elevate FG modestly, but do not cause overt diabetes.
doi:10.1038/ng.520
PMCID: PMC3018764  PMID: 20081858
17.  A1C Is Associated With Intima-Media Thickness in Individuals With Normal Glucose Tolerance 
Diabetes Care  2009;33(1):203-204.
OBJECTIVE
One-hour glucose during an oral glucose tolerance test (OGTT) was recently proposed as a valuable marker to identify individuals with normal glucose tolerance (NGT) and increased intima-media thickness (IMT). However, central markers of glycemic control were not considered. The aim of this study was to identify which marker of glycemic control is most informative with respect to the variation of IMT in individuals with NGT.
RESEARCH DESIGN AND METHODS
Cardiovascular risk factors, glucose metabolism (OGTT), and IMT were determined in 1,219 nondiabetic individuals (851 women, 368 men; 558 with NGT).
RESULTS
One-hour glucose and A1C levels were significantly correlated to carotid IMT in individuals with NGT, whereas fasting and 2-h glucose levels were not informative. Only A1C was associated with IMT independent of other confounders, whereas 1-h glucose was not informative. Comparable results were found in the total cohort, including individuals with IFG and IGT.
CONCLUSIONS
A1C was the most informative glycemic marker with respect to IMT in individuals with NGT.
doi:10.2337/dc09-1009
PMCID: PMC2797974  PMID: 19808917
18.  Genetic variation in GPR133 is associated with height: genome wide association study in the self-contained population of Sorbs 
Human Molecular Genetics  2009;18(23):4662-4668.
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) (∼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 × 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.
doi:10.1093/hmg/ddp423
PMCID: PMC2773272  PMID: 19729412
19.  Psychodynamic mechanism and weight reduction in obesity group therapy – first observations with different attachment styles 
Objectives: Successful long-term results are extremely rare in non-surgical obesity treatment. Interactional difficulties with the attending physicians and the limited compliance of obese patients are a frequently described dilemma in repeated psychotherapeutic group treatment attempts. The type of relationship initiation and the attachment behavior probably play a central role in this connection but have not yet been systematically investigated.
Methods: This paper focuses on the attachment styles of obese subjects and their effects on psychodynamic group therapy within the context of a weight-reduction program.
Results: The attachment styles are characterized in 107 pre-obese and obese patients, and their effects on patients and therapists in group therapy are described.
Conclusion: The paper surveys the motivational situation, clinical pictures, and repeated group topics.
doi:10.3205/psm000066
PMCID: PMC2940216  PMID: 20930928
obesity; attachment styles; psychotherapy; group; therapist
20.  Free Fatty Acids Link Metabolism and Regulation of the Insulin-Sensitizing Fibroblast Growth Factor-21 
Diabetes  2009;58(7):1532-1538.
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.
doi:10.2337/db08-1775
PMCID: PMC2699854  PMID: 19401423
21.  Risk factors in critical illness myopathy during the early course of critical illness: a prospective observational study 
Critical Care  2010;14(3):R119.
Introduction
Non-excitable muscle membrane indicates critical illness myopathy (CIM) during early critical illness. We investigated predisposing risk factors for non-excitable muscle membrane at onset of critical illness.
Methods
We performed sequential measurements of muscle membrane excitability after direct muscle stimulation (dmCMAP) in 40 intensive care unit (ICU) patients selected upon a simplified acute physiology (SAPS-II) score ≥ 20 on 3 successive days within 1 week after ICU admission. We then investigated predisposing risk factors, including the insulin-like growth factor (IGF)-system, inflammatory, metabolic and hemodynamic parameters, as well as suspected medical treatment prior to first occurrence of abnormal dmCMAP. Nonparametric analysis of two-factorial longitudinal data and multivariate analysis were used for statistical analysis.
Results
22 patients showed abnormal muscle membrane excitability during direct muscle stimulation within 7 (5 to 9.25) days after ICU admission. Significant risk factors for the development of impaired muscle membrane excitability in univariate analysis included inflammation, disease severity, catecholamine and sedation requirements, as well as IGF binding protein-1 (IGFBP-I), but did not include either adjunctive hydrocortisone treatment in septic shock, nor administration of neuromuscular blocking agents or aminoglycosides. In multivariate Cox regression analysis, interleukin-6 remained the significant risk factor for the development of impaired muscle membrane excitability (HR 1.006, 95%-CI (1.002 to 1.011), P = 0.002).
Conclusions
Systemic inflammation during early critical illness was found to be the main risk factor for development of CIM during early critical illness. Inflammation-induced impairment of growth-factor mediated insulin sensitivity may be involved in the development of CIM.
doi:10.1186/cc9074
PMCID: PMC2911767  PMID: 20565863
22.  Evidence That Kidney Function but Not Type 2 Diabetes Determines Retinol-Binding Protein 4 Serum Levels 
Diabetes  2008;57(12):3323-3326.
OBJECTIVE— It has been suggested that retinol-binding protein 4 (RBP4) links adiposity, insulin resistance, and type 2 diabetes. However, circulating RBP4 levels are also affected by kidney function. Therefore, the aim of this study was to test whether RBP4 serum levels are primarily associated with kidney function or type 2 diabetes.
RESEARCH DESIGN AND METHODS— RBP4 serum concentration was determined by enzyme-linked immunosorbent assay in 126 nondiabetic and 104 type 2 diabetic subjects. The study population was divided according to estimated glomerular filtration rate (eGFR) into the following groups: eGFR >90 ml/min per 1.73 m2 (n = 53), 60–90 ml/min per 1.73 m2 (n = 90), 30–60 ml/min per 1.73 m2 (n = 38), and <30 ml/min per 1.73 m2 (n = 49). Each group was subdivided into nondiabetic and type 2 diabetic subjects.
RESULTS— RBP4 serum concentration was elevated (2.65 vs. 2.01 μmol/l; P < 0.001) and eGFR was reduced (56 vs. 74 ml/min per 1.73 m2; P < 0.001) in type 2 diabetic vs. nondiabetic subjects, respectively. By stratifying for eGFR, no more differences in RBP4 serum concentration were detectable between type 2 diabetic and nondiabetic subjects. A linear regression analysis revealed an influence of eGFR (r = −0.477; P < 0.001) but not A1C (r = 0.093; P = 0.185) on RBP4 serum concentration.
CONCLUSIONS— Existing human data showing elevated RBP4 levels in type 2 diabetic patients may be the result of moderate renal insufficiency rather than support for the suggestion that RBP4 links obesity to type 2 diabetes.
doi:10.2337/db08-0866
PMCID: PMC2584139  PMID: 18796616
23.  Lack of Association between the Tagging SNP A+930→G of SOCS3 and Type 2 Diabetes Mellitus: Meta-Analysis of Four Independent Study Populations 
PLoS ONE  2008;3(12):e3852.
Background
The suppressor of cytokine signalling 3 (SOCS3) provides a link between cytokine action and their negative consequences on insulin signalling. Thus SOCS3 is a potential candidate gene for type 2 diabetes (T2DM).
Methodology/Principal Findings
Based on HapMap we identified the polymorphism A+930→G (rs4969168) as a haplotype tagging SNP (htSNP) sufficiently covering the genetic variation of the whole gene. We therefore examined the association between rs4969168 within SOCS3 and T2DM in three independent study populations; one prospective case-cohort study and two cross-sectional study populations. Due to the low frequency of individuals being homozygous for the polymorphism a dominant model of inheritance was assumed. The case-cohort study with 2,957 individuals (764 of them with incident T2DM) showed no effect of the polymorphism on diabetes risk (hazard ratio (95%CI): 0.86 (0.66–1.13); p = 0.3). Within the MeSyBePo-study population 325 subjects had T2DM from a total of 1,897 individuals, while the second cross-sectional cohort included 851 cases of T2DM within a total of 1653 subjects. According to the results in the prospective study, no association with T2DM was found (odds ratio (95%CI): 0.78 (0.54–1.12) for MesyBepo and 1.13 (0.90–1.42) for the Leipzig study population). There was also no association with metabolic subtraits such as insulin sensitivity (p = 0.7), insulin secretion (p = 0.8) or the hyperbolic relation of both, the disposition index (p = 0.7). In addition, no evidence for interaction with BMI or sex was found. We subsequently performed a meta-analysis, additionally including the publicly available data from the T2DM-subcohort of the WTCCC (n = 4,855). The overall odds ratio within that meta-analysis was 0.96 (0.88–1.06).
Conclusions/Significance
There is no strong effect of the common genetic variation within the SOCS3 gene on the development of T2DM.
doi:10.1371/journal.pone.0003852
PMCID: PMC2585796  PMID: 19052638
24.  Frataxin deficiency in pancreatic islets causes diabetes due to loss of β cell mass 
Journal of Clinical Investigation  2003;112(4):527-534.
Diabetes is caused by an absolute (type 1) or relative (type 2) deficiency of insulin-producing β cells. We have disrupted expression of the mitochondrial protein frataxin selectively in pancreatic β cells. Mice were born healthy but subsequently developed impaired glucose tolerance progressing to overt diabetes mellitus. These observations were explained by impairment of insulin secretion due to a loss of β cell mass in knockout animals. This phenotype was preceded by elevated levels of reactive oxygen species in knockout islets, an increased frequency of apoptosis, and a decreased number of proliferating β cells. Hence, disruption of the frataxin gene in pancreatic β cells causes diabetes following cellular growth arrest and apoptosis, paralleled by an increase in reactive oxygen species in islets. These observations might provide insight into the deterioration of β cell function observed in different subtypes of diabetes in humans.
doi:10.1172/JCI200318107
PMCID: PMC171391  PMID: 12925693

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