Obesity and diabetes: lipids, ‘nowhere to run to’. Clin Sci (Lond). 2009;116:113-123. [PMID: 19076064 DOI: 10.1042/cs20080050]

Silencing the fatty acid elongase gene elovl6 induces reprogramming of nutrient metabolism in male Oreochromis niloticus

Elongation of very long-chain fatty acids protein 6 (ELOVL6) plays a pivotal role in the synthesis of endogenous fatty acids, influencing energy balance and metabolic diseases. The primary objective of this study was to discover the molecular attributes and regulatory roles of ELOVL6 in male Nile tilapia, Oreochromis niloticus. The full-length cDNA of elovl6 was cloned from male Nile tilapia, and was determined to be 2255-bp long, including a 5'-untranslated region of 193 bp, a 3'-untranslated region of 1252 bp, and an open reading frame of 810 bp encoding 269 amino acids. The putative protein had typical features of ELOVL proteins. The transcript levels of elovl6 differed among various tissues and among fish fed with different dietary lipid sources. Knockdown of elovl6 in Nile tilapia using antisense RNA technology resulted in significant alterations in hepatic morphology, long-chain fatty acid synthesis, and fatty acid oxidation, and led to increased fat deposition in the liver and disrupted glucose/lipid metabolism. A comparative transcriptomic analysis (elovl6 knockdown vs. the negative control) identified 5877 differentially expressed genes with significant involvement in key signaling pathways including the peroxisome proliferator-activated receptor signaling pathway, fatty acid degradation, glycolysis/gluconeogenesis, and the insulin signaling pathway, all of which are crucial for lipid and glucose metabolism. qRT-PCR analyses verified the transcript levels of 13 differentially expressed genes within these pathways. Our findings indicate that elovl6 knockdown in male tilapia impedes oleic acid synthesis, culminating in aberrant nutrient metabolism.

Lipids as potential mediators linking body mass index to diabetes: evidence from a mediation analysis based on the NAGALA cohort

BACKGROUND

Body mass index (BMI) and lipid disorders are both known to be strongly associated with the development of diabetes, however, the indirect effect of lipid parameters in the BMI-related diabetes risk is currently unknown. This study aimed to investigate the mediating role of lipid parameters in the association of BMI with diabetes risk.

METHODS

We assessed the association of diabetes risk with BMI, as well as lipid parameters including high-density lipoprotein cholesterol(HDL-C), low-density lipoprotein cholesterol(LDL-CF and LDL-CS), triglycerides(TG), total cholesterol(TC), remnant cholesterol(RC), non-HDL-C, and combined indices of lipid parameters with HDL-C (RC/HDL-C ratio, TG/HDL-C ratio, TC/HDL-C ratio, non-HDL/HDL-C ratio, LDL/HDL-C ratio) using data from 15,453 subjects in the NAGALA project. Mediation models were used to explore the mediating role of lipid parameters in the association of BMI with diabetes risk, and mediation percentages were calculated for quantifying the strength of the indirect effects. Finally, receiver operating characteristic curve (ROC) analysis was used to compare the accuracy of BMI and BMI combined with lipid parameters in predicting incident diabetes.

RESULTS

Multivariate regression models, adjusted for confounding factors, demonstrated robust associations of lipid parameters, BMI, with diabetes risk, with the exception of TC, LDL-CF, LDL-CS, and non-HDL-C. Mediation analysis showed that lipid parameters except TC, LDL-CF, LDL-CS, and Non-HDL-C were involved in and mediated the association of BMI with diabetes risk, with the largest mediation percentage being the RC/HDL-C ratio, which was as high as 40%; it is worth mentioning that HDL-C and HDL-C-related lipid ratio parameters also play an important mediating role in the association between BMI and diabetes, with the mediator proportion being greater than 30%. Finally, based on the ROC results, we found that the prediction performance of all lipid parameters in the current study except TC was significantly improved when combined with BMI.

CONCLUSION

Our fresh findings suggested that lipid parameters partially mediated the association of BMI with diabetes risk; this result indicated that in the context of diabetes risk screening and disease management, it is important to not only monitor BMI but also pay attention to lipid parameters, particularly HDL-C and HDL-C-related lipid ratio parameters.

The prevalence of diabetes and associated risk factors among adult population in a Turkish population (Trabzon city)

OBJECTIVE

The objectives of this study were to determine the prevalence of diagnosed and undiagnosed diabetes mellitus (DM) and prediabetes, and to evaluate the associated risk factors in a sample of adult Turkish population.

METHODS

A total of 4000 eligible study subjects, aged 20 years or older, chosen by multistage sampling on a field were considered. Of those 3721 subjects (2139 women and 1582 men) participated in the study.

RESULTS

The prevalence of prediabetes and DM were found to be as 6.4% and 10.4% (3.6% being newly diagnosed by this study), respectively. In multivariate logistic regression analysis, advanced age (OR:26.7, p < 0.0005 in the group 70 years and over), marriage (OR:2.05, p = 0.047), housewives (OR:1.34, p = 0.003), family history of diabetes (OR:2.84, p < 0.0005), overweight (OR:1.61, p = 0.026), obesity (OR:2.25, p < 0.0005), hypertension (OR:1.42, p = 0.007) and dyslipidemia (OR:1.38, p = 0.028) were independent risk factors for being diabetic.

CONCLUSIONS

DM is an important health problem in the adult population of Trabzon city. Newly diagnosed diabetic patients who were unaware of their status are at high risk. To control DM and associated risk factors, effective public health education and taking urgent steps are needed.

Bilirubin as an indicator of cardiometabolic health: a cross-sectional analysis in the UK Biobank

BACKGROUND

Mildly elevated bilirubin, a by-product of hemoglobin breakdown, might mitigate cardiometabolic risk factors including adiposity, dyslipidemia, and high blood pressure (BP). We investigated the cross-sectional relationship between (total) bilirubin and baseline cardiometabolic risk factors in 467,519 UK Biobank study participants.

METHODS

We used multivariable-adjusted linear regression to estimate associations between bilirubin levels and risk factors of cardiometabolic diseases including body mass index (BMI), waist and hip circumferences (WC, HC), waist-to-hip ratio (WHR), fat mass (FM), and trunk FM, and the blood lipids: apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), apoB/apoA-I, lipoprotein (a), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), LDL/HDL, TC/HDL, triglycerides (TG). Log-transformed bilirubin was modelled with restricted cubic splines and predicted mean values with 99% confidence intervals (CI) for each risk marker were estimated, separately. Second, we applied principal component analysis (PCA) for dimension reduction to in turn six anthropometric traits (height, weight, BMI, WC, HC, and WHR) and all above lipids. Last, we estimated associations (99%CI) between bilirubin and three components of the metabolic syndrome, i.e. WC, TG, and BP using logistic regression.

RESULTS

After multivariable adjustments, higher levels of bilirubin were inversely associated with indicators of general adiposity (BMI and FM) and of body fat distribution (WC, HC, WHR, and trunk FM) in both men and women. For example, women with mildly elevated bilirubin (95th percentile equal to 15.0 µmol/L), compared to women with low bilirubin (5th percentile equal to 4.5 µmol/L), had on average a 2.0 kg/m2 (99% CI 1.9-2.1) lower BMI. Inverse associations were also observed with dyslipidemia among men and women. For example, mildly elevated bilirubin among men (95th percentile equal to 19.4 µmol/L) compared to low levels of bilirubin (5th percentile equal to 5.5 µmol/L) were associated with approx. 0.55 mmol/L (99% CI 0.53-0.56) lower TG levels, with similar inverse associations among women. Multiple-trait analyses using PCA confirmed single-trait analyses. Men and women with mildly elevated bilirubin levels ≥ 17.1 µmol/L, compared to low-normal bilirubin < 10 µmol/L had 13% (99% CI 8%-18%) and 11% (99% CI 4%-17%) lower odds of exceeding systolic BP levels of ≥ 130 mm Hg, respectively.

CONCLUSIONS

Higher levels of bilirubin were inversely associated with cardiometabolic risk factors including adiposity, dyslipidemia, and hypertension.

Asthma and obesity: endotoxin another insult to add to injury?

Low-grade inflammation is often an underlying cause of several chronic diseases such as asthma, obesity, cardiovascular disease, and type 2 diabetes mellitus (T2DM). Defining the mediators of such chronic low-grade inflammation often appears dependent on which disease is being investigated. However, downstream systemic inflammatory cytokine responses in these diseases often overlap, noting there is no doubt more than one factor at play to heighten the inflammatory response. Furthermore, it is increasingly believed that diet and an altered gut microbiota may play an important role in the pathology of such diverse diseases. More specifically, the inflammatory mediator endotoxin, which is a complex lipopolysaccharide (LPS) derived from the outer membrane cell wall of Gram-negative bacteria and is abundant within the gut microbiota, and may play a direct role alongside inhaled allergens in eliciting an inflammatory response in asthma. Endotoxin has immunogenic effects and is sufficiently microscopic to traverse the gut mucosa and enter the systemic circulation to act as a mediator of chronic low-grade inflammation in disease. Whilst the role of endotoxin has been considered in conditions of obesity, cardiovascular disease and T2DM, endotoxin as an inflammatory trigger in asthma is less well understood. This review has sought to examine the current evidence for the role of endotoxin in asthma, and whether the gut microbiota could be a dietary target to improve disease management. This may expand our understanding of endotoxin as a mediator of further low-grade inflammatory diseases, and how endotoxin may represent yet another insult to add to injury.

Adipocyte extracellular vesicles carry enzymes and fatty acids that stimulate mitochondrial metabolism and remodeling in tumor cells

Extracellular vesicles are emerging key actors in adipocyte communication. Notably, small extracellular vesicles shed by adipocytes stimulate fatty acid oxidation and migration in melanoma cells and these effects are enhanced in obesity. However, the vesicular actors and cellular processes involved remain largely unknown. Here, we elucidate the mechanisms linking adipocyte extracellular vesicles to metabolic remodeling and cell migration. We show that adipocyte vesicles stimulate melanoma fatty acid oxidation by providing both enzymes and substrates. In obesity, the heightened effect of extracellular vesicles depends on increased transport of fatty acids, not fatty acid oxidation-related enzymes. These fatty acids, stored within lipid droplets in cancer cells, drive fatty acid oxidation upon being released by lipophagy. This increase in mitochondrial activity redistributes mitochondria to membrane protrusions of migrating cells, which is necessary to increase cell migration in the presence of adipocyte vesicles. Our results provide key insights into the role of extracellular vesicles in the metabolic cooperation that takes place between adipocytes and tumors with particular relevance to obesity.

HIIT is not superior to MICT in altering blood lipids: a systematic review and meta-analysis

Objective

To compare the effects of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on adult lipid profiles; to identify training or participant characteristics that may determine exercise-induced change in total cholesterol (TC), triglycerides (TRG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C).

Design

Systematic review and meta-analysis.

Data sources

English language searches of several databases were conducted from inception until September 2019.

Eligibility criteria for excluding studies

Inclusion: (1) published randomised controlled human trials with group population n≥5; (2) intervention duration ≥4 weeks; (3) comparing HIIT with MICT; and (4) reporting pre–post intervention lipid measurements. Exclusion: subjects with chronic disease, <18 years, pregnant/lactating, in elite athletic training; and studies with a dietary or pharmaceutical intervention component.

Results

Twenty-nine data sets (mmol/L) of 823 participants were pooled and analysed. Neither HIIT nor MICT was better in decreasing TC (0.10 (−0.06 to 0.19), p=0.12, I²=0%), TRG (−0.05 (−0.11 to 0.01), p=0.10, I²=0%), LDL-C (0.05 (−0.06 to 0.17), p=0.37, I²=0%), or TC/HDL-C (−0.03 (−0.36 to 0.29), p=0.85, I²=0%). HIIT significantly raised HDL-C (0.07 (0.04 to 0.11), p<0.0001, I²=0%) compared with MICT.

Conclusion

Neither HIIT nor MICT is superior for altering TC, TRG, or LDL-C, or TC-HDL-C ratio. Compared with MICT, HIIT appeared to significantly improve HDL-C. Clinicians may prescribe either protocol to encourage participation in exercise and reduce cardiovascular risk. To raise HDL-C, HIIT may result in a larger effect size compared with MICT.

PROSPERO registration number

CRD42019136722.

4-Hydroxyderricin Isolated from the Sap of Angelica keiskei Koidzumi: Evaluation of Its Inhibitory Activity towards Dipeptidyl Peptidase-IV

Angelica keiskei sap is used as a blood-sugar reducer in Indonesia, however its molecular mechanism has not yet been explored. 4-hydroxyderricin (4-HD) is one of the major components extracted from A. keiskei sap. The aim of this work was to isolate 4-HD from the sap of A. keiskei planted in Lombok, Indonesia, and to study in silico and in vitro mechanisms against dipeptidyl peptidase-IV (DPP-IV). The dried sap was submitted to liquid–liquid extraction using solvents with different polarity. Further purification processing was conducted using gradient elution column chromatography. The isolated compound was a yellowish powder, m/z 339.2215 [M + H]+, which was confirmed as 4-HD. Sitagliptin, a DPP-IV inhibitor, was employed as the positive control for both the in silico and in vitro studies. It was indicated that 4-HD interacts with Glu206 and Phe357, important amino acid residues in the DPP-IV binding pocket. These interactions are similar to that of sitagliptin. The affinity of 4-HD (inhibition constant (Ki) = 3.99 μM) to DPP-IV is lower than that of sitagliptin (inhibition constant (Ki) = 0.17 μM). Furthermore, in vitro study showed that 4-HD inhibits DPP-IV (IC50 = 81.44 μM) weaker than for sitagliptin (IC50 = 0.87 μM). We concluded that 4- HD might have potential in inhibiting DPP-IV. However, by considering the polar interaction of sitagliptin with DPP-IV, a further structure modification of 4-HD, e.g., by introducing a polar moiety such as a hydroxyl group, might be needed to obtain stronger activity as a DPP-IV inhibitor.

Novel metabolic indices and incident type 2 diabetes among women and men: the Rotterdam Study

AIMS/HYPOTHESIS

Both visceral and truncal fat have been associated with metabolic disturbances. We aimed to investigate the associations of several novel metabolic indices, combining anthropometric and lipid measures, and dual-energy x-ray absorptiometry (DXA) measurements of body fat, with incident type 2 diabetes among women and men from the large population-based Rotterdam Study.

METHODS

Cox proportional hazards models were used to investigate associations of visceral adiposity index (VAI), lipid accumulation product (LAP), the product of triacylglycerol and glucose (TyG), their formula components and DXA measures with incident type 2 diabetes. Associations were adjusted for traditional diabetes risk factors.

RESULTS

Among 5576 women and 3988 men free of diabetes, 511 women and 388 men developed type 2 diabetes during a median follow-up of 6.5 years. In adjusted models, the three metabolic indices VAI (per 1 SD naturally log-transformed HR; 95% CI) (1.49; 1.36, 1.65 in women; 1.37; 1.22, 1.53 in men), LAP (1.35; 1.16, 1.56 in women; 1.19; 1.01, 1.42 in men) and TyG (1.73; 1.52, 1.98 in women; 1.43; 1.26, 1.62 in men), gynoid fat mass (0.63; 0.45, 0.89) and android to gynoid fat ratio (1.51; 1.16, 1.97) in women were associated with incident type 2 diabetes. BMI (1.45; 1.28, 1.65) was the strongest predictor of type 2 diabetes in men.

CONCLUSIONS/INTERPRETATION

Among women, novel combined metabolic indices were stronger risk markers for type 2 diabetes than the traditional anthropometric and laboratory measures and were comparable with DXA measures. Neither combined metabolic indices nor DXA measures were superior to traditional anthropometric and lipid measures in association with type 2 diabetes among men.

Cyanidin and cyanidin-3-glucoside derived from Vigna unguiculata act as noncompetitive inhibitors of pancreatic lipase

The consumption of legumes positively correlated with the reduction of body weight. In the present study, we identified and evaluated pancreatic lipase inhibitors from Vigna unguiculata and unraveled their mode of inhibition. The highly sensitive fluorometric method was adopted to access the pancreatic lipase activity and the ethanolic extract of Vigna unguiculata showed the maximum inhibition (IC₅₀ of 15.2 µg/ml). Cyanidin and cyanidin-3-glucoside are the major anthocyanins observed in Vigna unguiculata. The IC₅₀ value of cyanidin was 28.29 µM which was 6.5-fold higher than the cyanidin-3-glucoside (188.28 µM). We determined an apparent K_i of 27.28 µM for cyanidin and cyanidin-3-glucoside (88.97 µM) with noncompetitive inhibition. Collectively, these results suggest that the glycosylation of the anthocyanidins significantly reduces lipase inhibition. The noncompetitive inhibition of pancreatic lipase by Vigna unguiculata anthocyanins may exert significant pharmacological activities toward obesity complications by calorie restriction. PRACTICAL APPLICATIONS: The results of this study emphasize the importance of legumes in our diet to combat obesity-related complications. Consumption of legumes minimizes fat absorption by inhibiting the action of the fat-digesting enzyme.

White Paper AGA: POWER - Practice Guide on Obesity and Weight Management, Education, and Resources

The epidemic of obesity continues at alarming rates, with a high burden to our economy and society. The American Gastroenterological Association understands the importance of embracing obesity as a chronic, relapsing disease and supports a multidisciplinary approach to the management of obesity. Because gastrointestinal disorders resulting from obesity are more frequent and often present sooner than type 2 diabetes mellitus and cardiovascular disease, gastroenterologists have an opportunity to address obesity and provide an effective therapy early. Patients who are overweight or obese already fill gastroenterology clinics with gastroesophageal reflux disease and its associated risks of Barrett's esophagus and esophageal cancer, gallstone disease, nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, and colon cancer. Obesity is a major modifiable cause of diseases of the digestive tract that frequently goes unaddressed. As internists, specialists in digestive disorders, and endoscopists, gastroenterologists are in a unique position to play an important role in the multidisciplinary treatment of obesity. This American Gastroenterological Association paper was developed with content contribution from Society of American Gastrointestinal and Endoscopic Surgeons, The Obesity Society, Academy of Nutrition and Dietetics, and North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, endorsed with input by American Society for Gastrointestinal Endoscopy, American Society for Metabolic and Bariatric Surgery, American Association for the Study of Liver Diseases, and Obesity Medicine Association, and describes POWER: Practice Guide on Obesity and Weight Management, Education and Resources. Its objective is to provide physicians with a comprehensive, multidisciplinary process to guide and personalize innovative obesity care for safe and effective weight management.

Complement Activation and STAT4 Expression Are Associated with Early Inflammation in Diabetic Wounds

Diabetic non-healing wounds are a major clinical problem. The mechanisms leading to poor wound healing in diabetes are multifactorial but unresolved inflammation may be a major contributing factor. The complement system (CS) is the most potent inflammatory cascade in humans and contributes to poor wound healing in animal models. Signal transducer and activator of transcription 4 (STAT4) is a transcription factor expressed in immune and adipose cells and contributes to upregulation of some inflammatory chemokines and cytokines. Persistent CS and STAT4 expression in diabetic wounds may thus contribute to chronic inflammation and delayed healing. The purpose of this study was to characterize CS and STAT4 in early diabetic wounds using db/db mice as a diabetic skin wound model. The CS was found to be activated early in the diabetic wounds as demonstrated by increased anaphylatoxin C5a in wound fluid and C3-fragment deposition by immunostaining. These changes were associated with a 76% increase in nucleated cells in the wounds of db/db mice vs.

CONTROLS

The novel classical CS inhibitor, Peptide Inhibitor of Complement C1 (PIC1) reduced inflammation when added directly or saturated in an acellular skin scaffold, as reflected by reduced CS components and leukocyte infiltration. A significant increase in expression of STAT4 and the downstream macrophage chemokine CCL2 and its receptor CCR2 were also found in the early wounds of db/db mice compared to non-diabetic controls. These studies provide evidence for two new promising targets to reduce unresolved inflammation and to improve healing of diabetic skin wounds.

A working paradigm for the treatment of obesity in gastrointestinal practice

Obesity is a chronic, relapsing, multi-factorial disease characterized by abnormal or excessive adipose tissue accumulation that may impair health and increase disease risks. Despite the ever-increasing prevalence and economic and societal burden, the current approaches to treat obesity are not standardized or generally effective. In this manuscript, we describe a current working paradigm developed by a consensus approach for the multidisciplinary treatment of obesity in the GI practice. Obesity should be managed as a continuum of care focusing on weight loss, weight loss maintenance and prevention of weight regain. This approach needs to be disseminated throughout the health care system, coordinated by a multidisciplinary team and include gastroenterologists who are in a unique position to address obesity. Gastroenterologists are in the front line of managing the morbidity resulting from obesity, and have expertise in use of the essential tools to manage obesity: nutrition, pharmacology, endoscopy and surgery.

Macrophage PPARγ and impaired wound healing in type 2 diabetes

Macrophages undergo a transition from pro-inflammatory to healing-associated phenotypes that is critical for efficient wound healing. However, the regulation of this transition during normal and impaired healing remains to be elucidated. In our studies, the switch in macrophage phenotypes during skin wound healing was associated with up-regulation of the peroxisome proliferator-activated receptor (PPAR)γ and its downstream targets, along with increased mitochondrial content. In the setting of diabetes, up-regulation of PPARγ activity was impaired by sustained expression of IL-1β in both mouse and human wounds. In addition, experiments with myeloid-specific PPARγ knockout mice indicated that loss of PPARγ in macrophages is sufficient to prolong wound inflammation and delay healing. Furthermore, PPARγ agonists promoted a healing-associated macrophage phenotype both in vitro and in vivo, even in the diabetic wound environment. Importantly, topical administration of PPARγ agonists improved healing in diabetic mice, suggesting an appealing strategy for down-regulating inflammation and improving the healing of chronic wounds.

Evaluation of exenatide versus insulin glargine for the impact on endothelial functions and cardiovascular risk markers

AIMS

To demonstrate the efficacy of exenatide versus insulin glargine on endothelial functions and cardiovascular risk markers.

METHODS

Thirty-four insulin and incretin-naive patients with type 2 diabetes mellitus (body mass index 25-45 kg/m(2)) who received metformin for at least two months were randomized to exenatide or insulin glargine treatment arms and followed-up for 26 weeks. Measurements of endothelial functions were done by ultrasonography, cardiovascular risk markers by serum enzyme-linked immunosorbent assay, and total body fat mass by bioimpedance.

RESULTS

Levels of high sensitivity-C-reactive protein and endothelin-1 decreased (27.5% and 18.75%, respectively) in the exenatide arm. However, in the insulin glargine arm, fibrinogen, monocyte chemoattractant protein-1, leptin and endothelin-1 levels (13.4, 30.2, 47.5, and 80%, respectively) increased. Post-treatment flow mediated dilatation and endothelium independent vascular responses were significantly higher in both arms (p=0.0001, p=0.0001). Positive correlation was observed between the changes in body weight and endothelium-independent vasodilatation, leptin, plasminogen activator inhibitor type 1 and endothelin-1 in both arms (r=0.376, r=0.507, r=0.490, r=0.362, respectively).

CONCLUSIONS

Insulin glargine improved endothelial functions, without leading to positive changes in cardiovascular risk markers. Exenatide treatment of 26 weeks resulted in reduced body weight and improvement in certain cardiovascular risk markers and endothelial functions.

Zingiber officinale (Ginger): A Future Outlook on Its Potential in Prevention and Treatment of Diabetes and Prediabetic States

Diabetes is reaching pandemic levels in both developing and developed countries and requires safe, affordable, and effective therapies. This report summarises work in our laboratory on the effects of Zingiber officinale (ginger) and its components in diabetes models and provides a future outlook on the potential for their use in type 2 diabetes. A high fat diet rat model showed modulation of body weight gain and normalisation of glucose and lipid metabolic disturbances, with reduction of insulin resistance in a high fat-high carbohydrate diet model. Ginger extract inhibits enhanced NF-κB in liver of high fat-fed rats through inhibition of the IKK/IκBα/NF-κB classical pathway. The major active component (S)-[6]-gingerol inhibited elevated cytokines in inflamed HuH7 cells through suppression of COX2 expression and protection against the ROS pathway. Ginger extract and gingerols enhanced glucose uptake in L6 myotubes, by enhancing translocation of GLUT4 to the surface membrane and activation of AMPKα1 through a Ca2+/calmodulin-dependent protein kinase kinase pathway. (S)-[6]-Gingerol also enhanced energy metabolism through marked increment of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) gene expression and mitochondrial content in L6 skeletal muscle cells. Future studies will require well designed clinical trials on ginger preparations of defined chemical composition.

Improving residents' clinical approach to obesity: impact of a multidisciplinary didactic curriculum

BACKGROUND/OBJECTIVES

Obesity has been declared a 21st century pandemic by WHO. Yet surveys reveal physicians-in-training are uncomfortable managing obesity. One major barrier is the lack of residency education on obesity management. This study incorporates an obesity-specific didactic curriculum into an internal medicine (IM) residency programme and assesses its impact on residents' knowledge, attitudes, practice behaviours, and clinical outcomes in patients with obesity.

METHODS

The intervention consisted of four, 1 h, obesity-specific lectures in the University of Florida Resident Noon Conference. Lectures were taught by multidisciplinary experts and offered to 75 IM residents every 2 weeks from 5 November 2010 to 17 December 2010. Impact on IM residents' knowledge and attitudes was assessed by a pre- and post-intervention Obesity Awareness Questionnaire (OAQ). IM residents' clinical performance was assessed by chart reviews of 238 patients with body mass index >25 kg/m(2) in residents' clinics 4 months pre- and 6 months post-intervention for three clinical outcomes and seven practice behaviours on obesity management. Pre- and post-intervention outcomes were compared via paired t tests (quantitative data) or McNemar's test (binary data).

RESULTS

Mean lecture attendance was 25/75 residents (33%) per lecture. Survey response was 67/75 residents (89%) pre-OAQ and 63/75 residents (84%) post-OAQ. While most attitudes remained unchanged, IM residents gained significant confidence in exercise counselling, safety of bariatric surgery, and patients' weight loss potential; they were more likely to address obesity in the plan and referrals to bariatric surgery. Clinical outcomes and IM residents' knowledge demonstrated no improvement.

CONCLUSIONS

Our brief lecture-based curriculum has the potential to improve IM residents' attitudes and practice behaviours towards obesity. The lack of improvement in clinical outcomes and resident knowledge prompts the need for multimodal, longitudinal curricula with experiential application of obesity medicine.

Impact of rosiglitazone on body composition, hepatic fat, fatty acids, adipokines and glucose in persons with impaired fasting glucose or impaired glucose tolerance: a sub-study of the DREAM trial

AIMS

Thiazolidinediones reduce ectopic fat, increase adiponectin and reduce inflammatory adipokines, fatty acids and glucose in people with Type 2 diabetes. We aimed to measure these effects in people with impaired fasting glucose and/or impaired glucose tolerance.

METHODS

After approximately 3.5 years of exposure to rosiglitazone 8 mg (n = 88) or placebo (n = 102), 190 DREAM trial participants underwent abdominal computed tomography and dual-energy X-ray absorptiometry scans. Visceral and subcutaneous adipose tissue areas, estimated hepatic fat content, total fat and lean mass were calculated and changes in levels of fasting adipokines, free fatty acids, glucose and post-load glucose were assessed.

RESULTS

Compared with the placebo, participants on rosiglitazone had no difference in lean mass, had 4.1 kg more body fat (P < 0.0001) and 31 cm(2) more subcutaneous abdominal adipose tissue area (P = 0.007). Only after adjusting for total fat, participants on rosiglitazone had 23 cm² less visceral adipose tissue area (P = 0.01) and an 0.08-unit higher liver:spleen attenuation ratio (i.e. less hepatic fat; P = 0.02) than those on the placebo. Adiponectin increased by 15.0 μg/ml with rosiglitazone and by 0.4 μg/ml with placebo (P < 0.0001). Rosiglitazone's effect on fat distribution was not independent of changes in adiponectin. Rosiglitazone's effects on fasting (-0.36 mmol/l; P = 0.0004) and 2-h post-load glucose (-1.21 mmol/l; P = 0.0008) were not affected by adjustment for fat distribution or changes in adiponectin or free fatty acids.

CONCLUSIONS

In people with impaired fasting glucose/impaired glucose tolerance, rosiglitazone is associated with relatively less hepatic and visceral fat, increased subcutaneous fat and increased adiponectin levels. These effects do not appear to explain the glucose-lowering effect of rosiglitazone.

Preventative effect of Zingiber officinale on insulin resistance in a high-fat high-carbohydrate diet-fed rat model and its mechanism of action

Insulin resistance is a core component of metabolic syndrome and usually precedes the development of type 2 diabetes mellitus. We have examined the preventative effect of an ethanol extract of ginger (Zingiber officinale, Zingiberaceae) on insulin resistance in a high-fat high-carbohydrate (HFHC) diet-fed rat model of metabolic syndrome. The HFHC control rats displayed severe insulin resistance, whilst rats treated with ginger extract (200 mg/kg) during HFHC diet feeding showed a significant improvement of insulin sensitivity using the homeostatic model assessment of insulin resistance (HOMA-IR) after 10 weeks (p < 0.01). An in vitro mechanistic study showed that (S)-[6]-gingerol, the major pungent phenolic principle in ginger, dose-dependently (from 50 to 150 μM) increased AMPK α-subunit phosphorylation in L6 skeletal muscle cells. This was accompanied by a time-dependent marked increment of PGC-1α mRNA expression and mitochondrial content in L6 skeletal muscle cells. These results suggest that the protection from HFHC diet-induced insulin resistance by ginger is likely associated with the increased capacity of energy metabolism by its major active component (S)-[6]-gingerol.

Dyslipidemia in obesity: mechanisms and potential targets

Obesity has become a major worldwide health problem. In every single country in the world, the incidence of obesity is rising continuously and therefore, the associated morbidity, mortality and both medical and economical costs are expected to increase as well. The majority of these complications are related to co-morbid conditions that include coronary artery disease, hypertension, type 2 diabetes mellitus, respiratory disorders and dyslipidemia. Obesity increases cardiovascular risk through risk factors such as increased fasting plasma triglycerides, high LDL cholesterol, low HDL cholesterol, elevated blood glucose and insulin levels and high blood pressure. Novel lipid dependent, metabolic risk factors associated to obesity are the presence of the small dense LDL phenotype, postprandial hyperlipidemia with accumulation of atherogenic remnants and hepatic overproduction of apoB containing lipoproteins. All these lipid abnormalities are typical features of the metabolic syndrome and may be associated to a pro-inflammatory gradient which in part may originate in the adipose tissue itself and directly affect the endothelium. An important link between obesity, the metabolic syndrome and dyslipidemia, seems to be the development of insulin resistance in peripheral tissues leading to an enhanced hepatic flux of fatty acids from dietary sources, intravascular lipolysis and from adipose tissue resistant to the antilipolytic effects of insulin. The current review will focus on these aspects of lipid metabolism in obesity and potential interventions to treat the obesity related dyslipidemia.

Platelets derived from the bone marrow of diabetic animals show dysregulated endoplasmic reticulum stress proteins that contribute to increased thrombosis

OBJECTIVE

Patients with diabetes mellitus have an increased risk of suffering atherothrombotic syndromes and are prone to clustering cardiovascular risk factors. However, despite their dysregulated glucose metabolism, intensive glycemic control has proven insufficient to reduce thrombotic complications. Therefore, we aimed to elucidate the determinants of thrombosis in a model of type 2 diabetes mellitus with cardiovascular risk factors clustering.

METHODS AND RESULTS

Intravital microscopy was used to analyze thrombosis in vivo in Zucker diabetic fatty rats (ZD) and lean normoglycemic controls. Bone marrow (BM) transplants were performed to test the contribution of each compartment (blood or vessel wall) to thrombogenicity. ZD showed significantly increased thrombosis compared with lean normoglycemic controls. BM transplants demonstrated the key contribution of the hematopoietic compartment to increased thrombogenicity. Indeed, lean normoglycemic controls transplanted with ZD-BM showed increased thrombosis with normal glucose levels, whereas ZD transplanted with lean normoglycemic controls-BM showed reduced thrombosis despite presenting hyperglycemia. Significant alterations in megakaryopoiesis and platelet-endoplasmic reticulum stress proteins, protein disulfide isomerase and 78-kDa glucose-regulated protein, were detected in ZD, and increased tissue factor procoagulant activity was detected in plasma and whole blood of ZD.

CONCLUSIONS

Our results indicate that diabetes mellitus with cardiovascular risk factor clustering favors BM production of hyperreactive platelets with altered protein disulfide isomerase and 78-kDa glucose-regulated protein expression that can contribute to increase thrombotic risk independently of blood glucose levels.

Influence of fatty acids on mitochondrial metabolism of adipocyte progenitors and endothelial cells

CONTEXT

In obesity, the cells are exposed to excessive amounts of nutrients, especially free fatty acids (FFAs) that induce a variety of metabolic changes.

OBJECTIVE

We investigated the effect of FFAs on the mitochondrial function in different cell populations under stress conditions.

METHODS

Human adipose tissue progenitor cells (SVF) or endothelial cells (HUVECs) were incubated with 30μM of selected saturated or unsaturated FFA for 24 h, at times supplemented with 5ng/mL tumour necrosis factor alpha (TNFα) for the last 4 h. Changes in oxygen respiration rate, mitochondrial membrane potential (mitoMP) and total ATP content were monitored.

RESULTS

Saturated palmitic acid demonstrated no effect, while a selection of unsaturated FFAs ameliorated metabolism of the progenitor SVF cells. TNFα either did not affect or nullified some of the favourable FFA-induced effects.

CONCLUSIONS

The mitoMP was the most sensitive parameter reflecting positive impact of the unsaturated FFA on the adipose SVF cells' metabolism.

Microvascular responsiveness in obesity: implications for therapeutic intervention

Obesity has detrimental effects on the microcirculation. Functional changes in microvascular responsiveness may increase the risk of developing cardiovascular complications in obese patients. Emerging evidence indicates that selective therapeutic targeting of the microvessels may prevent life-threatening obesity-related vascular complications, such as ischaemic heart disease, heart failure and hypertension. It is also plausible that alterations in adipose tissue microcirculation contribute to the development of obesity. Therefore, targeting adipose tissue arterioles could represent a novel approach to reducing obesity. This review aims to examine recent studies that have been focused on vasomotor dysfunction of resistance arteries in obese humans and animal models of obesity. Particularly, findings in coronary resistance arteries are contrasted to those obtained in other vascular beds. We provide examples of therapeutic attempts, such as use of statins, ACE inhibitors and insulin sensitizers to prevent obesity-related microvascular complications. We further identify some of the important challenges and opportunities going forward.

LINKED ARTICLES

This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.

Effects of perinatal exposure to palatable diets on body weight and sensitivity to drugs of abuse in rats

The aim of the present study was to determine the effects of fat- and sugar-rich diets in utero and during the pre-weaning period on bodyweight and responses to drugs of abuse. In Exp. 1, dams were fed a balanced control diet or high-fat diet (HFD), and female offspring were cross-fostered to dams consuming the balanced diet. The HFD-exposed offspring, compared to controls, were heavier in body weight, had increased circulating triglyceride levels, and consumed more alcohol and HFD in adulthood. In Exp. 2, dams were fed standard chow alone or standard chow plus a 16% high-fructose corn syrup (HFCS) or 10% sucrose solution. Sets of offspring from each group were cross-fostered to dams in the other groups, allowing for the effects of HFCS or sucrose exposure during the gestational period or pre-weaning period to be determined. The offspring (both female and male) exposed to HFCS or sucrose in utero had higher body weights in adulthood and exhibited increased alcohol intake as shown in female offspring and increased amphetamine-induced locomotor activity as shown in males. Exposure to HFCS or sucrose only during the pre-weaning period had a similar effect of increasing amphetamine-induced locomotor activity in males, but produced no change in circulating triglycerides or alcohol intake. Collectively, these data suggest that prenatal as well as pre-weaning exposure to fat- and sugar-rich diets, in addition to increasing body weight, can affect responses to drugs of abuse.

High fat intake leads to acute postprandial exposure to circulating endotoxin in type 2 diabetic subjects

OBJECTIVE

To evaluate the changes in circulating endotoxin after a high-saturated fat meal to determine whether these effects depend on metabolic disease state.

RESEARCH DESIGN AND METHODS

Subjects (n = 54) were given a high-fat meal (75 g fat, 5 g carbohydrate, 6 g protein) after an overnight fast (nonobese control [NOC]: age 39.9 ± 11.8 years [mean ± SD], BMI 24.9 ± 3.2 kg/m(2), n = 9; obese: age 43.8 ± 9.5 years, BMI 33.3 ± 2.5 kg/m(2), n = 15; impaired glucose tolerance [IGT]: age 41.7 ± 11.3 years, BMI 32.0 ± 4.5 kg/m(2), n = 12; type 2 diabetic: age 45.4 ± 10.1 years, BMI 30.3 ± 4.5 kg/m(2), n = 18). Blood was collected before (0 h) and after the meal (1-4 h) for analysis.

RESULTS

Baseline endotoxin was significantly higher in the type 2 diabetic and IGT subjects than in NOC subjects, with baseline circulating endotoxin levels 60.6% higher in type 2 diabetic subjects than in NOC subjects (P < 0.05). Ingestion of a high-fat meal led to a significant rise in endotoxin levels in type 2 diabetic, IGT, and obese subjects over the 4-h time period (P < 0.05). These findings also showed that, at 4 h after a meal, type 2 diabetic subjects had higher circulating endotoxin levels (125.4%↑) than NOC subjects (P < 0.05).

CONCLUSIONS

These studies have highlighted that exposure to a high-fat meal elevates circulating endotoxin irrespective of metabolic state, as early as 1 h after a meal. However, this increase is substantial in IGT and type 2 diabetic subjects, suggesting that metabolic endotoxinemia is exacerbated after high fat intake. In conclusion, our data suggest that, in a compromised metabolic state such as type 2 diabetes, a continual snacking routine will cumulatively promote their condition more rapidly than in other individuals because of the greater exposure to endotoxin.

Treatment of lipid disorders in obesity

Obesity is the most common cause of secondary hyperlipidemia. Atherogenic dyslipidemia refers to elevated triglycerides, low HDL-cholesterol and small dense LDL associated with visceral obesity and metabolic syndrome. Obesity may also be associated with isolated low HDL-cholesterol or high triglycerides and postprandial hyperlipidemia. While some obese patients have high LDL cholesterol concentrations, obesity has a more pronounced effect on other atherogenic lipids and lipoproteins. Obesity may aggravate familial lipid disorders. Lipid disorders in obesity are responsive to weight loss, pharmacotherapy and weight loss surgery. Statins are the lipid-lowering drug of choice, together with lifestyle change. Hard clinical end point data to support combinations of statins with other drugs is lacking. After weight loss surgery, the absolute risk of cardiovascular disease should be reassessed, but tools to facilitate risk assessment need to be developed.

Psoriasis increased the risk of diabetes: a meta-analysis

To evaluate the association between psoriasis and risk of diabetes, pertinent studies were identified by searching electronic databases and by reviewing the reference lists of retrieved articles. We included observational studies that examined the association between psoriasis and risk of diabetes. Two reviewers independently assessed eligibility and used a standardized form to collect data from published studies. The study quality was assessed by the Newcastle-Ottawa Scale. A total of 22 eligible studies that included 3,307,516 participants fulfilled the inclusion criteria. Compared to individuals without psoriasis, subjects with psoriasis had a 1.42-fold increased risk of diabetes (95% CI, 1.40-1.45). Findings from this meta-analysis suggest that individuals with psoriasis may have a modestly increased risk of diabetes.

WAT is a functional adipocyte?

In vertebrates, adipose tissue is the main storage site for lipids within specialized lipid-laden mature adipocytes. While many species have evolved cells capable of lipid storage, the adipocyte represents a unique specialized cell involved in fuel storage, endocrine, nervous and immune function. However, the adipocytes are not the only cell type in mammals that can accumulate lipid droplets. The ectopic accumulation of lipid in non-adipose tissues including the liver, skeletal muscle, bone, pancreas, and heart in combination with its excessive accumulation in adipose tissue contributes to metabolic disease. Determining the lipid processing components that are necessary and sufficiently for lipid accumulation in adipose and non-adipose tissues, in addition to endocrine function, will lead to a clearer definition of an adipocyte.

Obesity and susceptibility to autoimmune diseases

For decades, obesity has been considered to be the result of the complex interaction between genes and the environment and its pathogenesis is still unresolved. The discovery of hormones and neural mediators responsible for the control of food intake and metabolism at the hypothalamic level has provided fundamental insights into the complicated pathways that control food intake. However, the molecular basis for the association between obesity and low-degree chronic inflammation is still unknown. More recently, the discovery of leptin, one of the most abundant adipocyte-derived hormones, has suggested that nutritional status, through leptin secretion, can control immune self-tolerance modulating Treg suppressive function and responsiveness. Furthermore, recent experimental evidence has shown the presence of an abundant adipose tissue-resident Treg population responsible for the control of metabolic parameters and glucose homeostasis. Better knowledge of the intricate network of interactions among leptin-related energy regulation, Treg activities and obesity could lead to valuable strategies for therapeutic intervention in obesity and obesity-associated insulin resistance.

A key problem and challenge for hepatology: Obesity-related metabolic liver diseases

With the arrival of the new millennium, gastroenterologists have been faced with the problem of metabolic liver diseases associated with obesity. The active role of the liver in metabolism and inflammation make it a key organ in the war against the rapidly-spreading world-wide epidemic of obesity. Many lives and much money could be saved if the work of hepatologists led to the development of effective diagnostic and therapeutic strategies against this growing leader of cirrhosis.

Experimental animal models of pancreatic carcinogenesis for prevention studies and their relevance to human disease

Pancreatic cancer is difficult to cure, so its prevention is very important. For this purpose, animal model studies are necessary to develop effective methods. Injection of N-nitrosobis(2-oxopropyl)amine (BOP) into Syrian golden hamsters is known to induce pancreatic ductal adenocarcinomas, the histology of which is similar to human tumors. Moreover, K-ras activation by point mutations and p16 inactivation by aberrant methylation of 5' CpG islands or by homozygous deletions have been frequently observed in common in both the hamster and humans. Thus, this chemical carcinogenesis model has an advantage of histopathological and genetic similarity to human pancreatic cancer, and it is useful to study promotive and suppressive factors. Syrian golden hamsters are in a hyperlipidemic state even under normal dietary conditions, and a ligand of peroxizome proliferator-activated receptor gamma was found to improve the hyperlipidemia and suppress pancreatic carcinogenesis. Chronic inflammation is a known important risk factor, and selective inhibitors of inducible nitric oxide synthase and cyclooxygenase-2 also have protective effects against pancreatic cancer development. Anti-inflammatory and anti-hyperlipidemic agents can thus be considered candidate chemopreventive agents deserving more attention.

Cornus kousa F.Buerger ex Miquel increases glucose uptake through activation of peroxisome proliferator-activated receptor γ and insulin sensitization

AIM OF THE STUDY

Cornus kousa F.Buerger ex Miquel, an oriental medicinal plant, has been traditionally used for the treatment of hyperglycemia, but its molecular mechanism remains unknown. The goal of this study was to investigate the peroxisome proliferator-activated receptor γ (PPARγ) ligand-binding activity of Cornus kousa and to determine the effects of Cornus kousa on insulin sensitization in 3T3-L1 cells for the treatment of type 2 diabetes.

MATERIALS AND METHODS

PPARγ luciferase transactivation assay was used to evaluate the PPARγ ligand-binding activity of Cornus kousa leaf extract. Western blot analysis, oil Red O staining, and glucose uptake assay were performed to evaluate PPARγ agonistic activity and insulin sensitizing effects of Cornus kousa leaf extract (CKE) in 3T3-L1 cells.

RESULTS

CKE increased PPARγ ligand-binding activity in a dose-dependent manner. In addition, CKE enhanced adipogenesis and the expression of PPARγ target proteins, including glucose transporter 4 (GLUT4) and adiponectin, as well as proteins involved in adipogenesis, including PPARγ and CCAAT/enhancer binding protein α (C/EBPα) in 3T3-L1 adipocytes. Furthermore, CKE led to significant induction of glucose uptake and stimulated insulin signaling, but not to activation of AMP-activated protein kinase (AMPK) signaling. The enhanced glucose uptake by CKE were abolished by treatment with bisphenol a diglycidyl ether (BADGE), a PPARγ antagonist, or LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), but not by compound C, an AMPK inhibitor.

CONCLUSION

Consistent with the high PPARγ ligand-binding activity, CKE increased glucose uptake through PPARγ activation and insulin signaling. These results suggest that CKE could have pharmacological effects for the treatment of hyperglycemia and type 2 diabetes.

Influence of obesity on control in asthmatic Japanese patients defined by the Japanese definition of obesity

BACKGROUND Despite the use of inhaled corticosteroid (ICS) becoming increasingly widespread, many problems related to asthma management still need to be addressed. One of them, obesity, has been reported to exert a harmful influence on asthma control. However, there have been few reports focusing not only on both obesity and its influence on Japanese asthma patients but also on the Japanese definition of obesity, as defined by the Japan Society for the Study of Obesity (JASSO). AIMS & METHODS The aim of this study was to confirm the influence of obesity, as defined by the JASSO, on asthma management in Japanese asthmatic patients. Using data from the Niigata Asthma Treatment Study Group 2008 questionnaire survey, differences between the "normal" group (18.5 kg/m(2) ≤ BMI <25 kg/m(2)) and the "obese" group (25 kg/m(2) ≤ BMI) were analyzed. RESULTS There was a significantly lower step 1 rate (19.4% v.s. 26.8%) and a higher proportion of patients using inhaled salmeterol (43.6% v.s. 35.8%) and leukotriene receptor antagonist (49.8% v.s. 40.8%) in the obese group relative to the normal group, although there were no significant differences in indicators of asthma control, including asthma control test scores. CONCLUSION This study investigated influences of JASSO-defined obesity on asthma severity and management in a clinical setting in Japan. It is possible that there are strong interactions between asthma and obesity, such as obesity causing decreased ICS therapy efficacy and leukotriene (LT)-related inflammation, although further investigation is necessary.

Regulatory T cells in obesity: the leptin connection

Studies to understand the pathogenesis of obesity have revealed mediators that are responsible for the control of food intake and metabolism at the hypothalamic level. However, molecular insight explaining the link between obesity and low-degree chronic inflammation remains elusive. The adipocyte-derived hormone leptin, and thereby the nutritional status, could control immune self-tolerance by affecting regulatory T (Treg) cell responsiveness and function. Furthermore, resident Treg cells, which are capable of modulating metabolism and glucose homeostasis, are abundant in adipose tissue. Here, we provide an update on recent findings relating Treg cells to obesity and discuss how the intricate network of interactions among leptin, Treg cells and adipose tissue might provide new strategies for therapeutic interventions.

Ginsenoside Rc, an active component of Panax ginseng, stimulates glucose uptake in C2C12 myotubes through an AMPK-dependent mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng and its major component, ginsenosides, are widely used for the prevention of various disorders in oriental medicine.

AIM OF THE STUDY

To evaluate the effect of ginsenoside Rc (Rc), one of the active constituents in Panax ginseng, on glucose uptake in C2C12 myotubes.

RESULTS

Treatment of the C2C12 myotubes with Rc significantly increased glucose uptake. To determine the mechanism of Rc-induced glucose uptake, either insulin-dependent signaling or insulin-independent signaling pathway activities were measured using western blot analysis. We showed that Rc significantly activated an insulin-independent AMPK signaling pathway. However, Rc had no effect on the components of the insulin-dependent signaling pathway, such as receptor substrates (IRS)-1 and protein kinase B or Akt (PKB/Akt). Moreover, we found that treatment with an AMPK inhibitor abolished both glucose uptake and p38 MAPK phosphorylation. This result implies that AMPK activity is critical for the Rc-induced glucose uptake and that AMPK is situated upstream of p38 MAPK. In addition, we also showed that the activation of AMPK and p38 induced by ginsenoside Rc is mediated by reactive oxygen species (ROS) production, suggesting that upstream regulators of AMPK- and p38 MAPK-mediated glucose uptake.

CONCLUSION

Ginsenoside Rc significantly enhances glucose uptake by inducing ROS generation, which leads to AMPK and p38 MAPK activation. Consequently, ginsenoside Rc can be used as a potent natural anti-diabetic agent.

beta-cell function in obese-hyperglycemic mice [ob/ob Mice]

This review summarizes key aspects of what has been learned about the physiology of pancreatic islets and leptin deficiency from studies in obese ob/ob mice. ob/ob Mice lack functional leptin. They are grossly overweight and hyperphagic particularly at young ages and develop severe insulin resistance with hyperglycemia and hyperinsulinemia. ob/ob Mice have large pancreatic islets. The beta-cells respond adequately to most stimuli, and ob/ob mice have been used as a rich source of pancreatic islets with high insulin release capacity. ob/ob Mice can perhaps be described as a model for the prediabetic state. The large capacity for islet growth and insulin release makes ob/ob mice a good model for studies on how beta-cells can cope with prolonged functional stress.

Pigment epithelium-derived factor (PEDF) as a therapeutic target in cardiovascular disease

In this review we discuss the role of pigment epithelium-derived factor (PEDF) as a possible new target molecule to therapeutically influence cardiovascular disease. PEDF is a multifunctional, pleiotropic protein with antiangiogenic, antitumorigenic, antioxidant, anti-inflammatory, antithrombotic, neurotrophic and neuroprotective properties. First identified in retinal pigment epithelium cells, it is expressed in various tissues throughout the body such as the eye, liver and adipose tissue. Recently PEDF has also been characterized in the heart. PEDF has been suggested to have a protective role in atherosclerosis, the main cause of coronary heart disease, myocardial infarction and heart failure due to its anti-inflammatory, antioxidant and antithrombotic effects in the vessel wall and platelets. Additionally PEDF has strong antiangiogenic effects by inducing apoptosis in endothelial cells and by regulating the expression of other angiogenic factors. Therefore blocking of PEDF locally for example in ischemic tissue in the heart might favour angiogenesis, induce neovascularization and lead to increased perfusion of the injured tissue. On the other hand, local overexpression of PEDF restricted to atherosclerotic lesions might block angiogenesis, inflammation and thrombosis at these sites and thus counteract destabilization and rupture of the lesion otherwise caused by inflammatory activation and excessive angiogenesis and inhibit subsequent thrombus formation.

Mechanisms of coronary microvascular adaptation to obesity

The metabolic syndrome (MetS) is associated with clustering of cardiovascular risk factors in individuals that may greatly increase their risk of developing coronary artery disease. Obesity and related metabolic dysfunction are the driving forces in the prevalence of MetS. It is believed that obesity has detrimental effects on cardiovascular function, but its overall impact on the vasomotor regulation of small coronary arteries is still debated. Emerging evidence indicates that in obesity coronary arteries adapt to hemodynamic changes via maintaining and/or upregulating cellular mechanism(s) intrinsic to the vascular wall. Among other factors, endothelial production of cyclooxygenase-2-derived prostacyclin and reactive oxygen species, as well as increased nitric oxide sensitivity and potassium channel activation in smooth muscle cells, have been implicated in maintaining coronary vasodilator function. This review aims to examine studies that have been primarily focused on alterations in coronary vasodilator function in obesity. A better understanding of cellular mechanisms that may contribute to coronary microvascular adaptation may provide insight into the sequence of pathological events in obesity and may allow the harnessing of these effects for therapeutic purposes.

Prevention of high-fat diet-induced muscular lipid accumulation in rats by alpha lipoic acid is not mediated by AMPK activation

Skeletal muscle triglyceride accumulation is associated with insulin resistance in obesity. Recently, it has been suggested that alpha lipoic acid (ALA) improves insulin sensitivity by lowering triglyceride accumulation in nonadipose tissues via activation of skeletal muscle AMP-activated protein kinase (AMPK). We examined whether chronic ALA supplementation prevents muscular lipid accumulation that is associated with high-fat diets via activation of AMPK. In addition, we tested if ALA supplementation was able to improve insulin sensitivity in rats fed low- and high-fat diets (LFD, HFD). Supplementing male Wistar rats with 0.5% ALA for 8 weeks significantly reduced body weight, both on LFD and HFD (-24% LFD+ALA vs. LFD, P < 0.01, and -29% HFD+ALA vs. HFD, P < 0.001). Oil red O lipid staining revealed a 3-fold higher lipid content in skeletal muscle after HFD compared with LFD and ALA-supplemented groups (P < 0.05). ALA improved whole body glucose tolerance ( approximately 20% lower total area under the curve (AUC) in ALA supplemented groups vs. controls, P < 0.05). These effects were not mediated by increased muscular AMPK activation or ALA-induced improvement of muscular insulin sensitivity. To conclude, the prevention of HFD-induced muscular lipid accumulation and the improved whole body glucose tolerance are likely secondary effects due to the anorexic nature of ALA.