Subcutaneous and visceral adipose tissue: their relation to the metabolic syndrome

[LDL: from metabolic syndrome to instability of the atherosclerotic plaque]

The dyslipidemia of the metabolic syndrome (MS) confers an elevated cardiovascular risk and is characterized by increased concentrations of triglycerides, decreased HDL-cholesterol and qualitative alterations in LDL which renders it more atherogenic, like the small dense LDL. Modified forms of LDL (mLDL) have been detected in vivo in the plasma and atherosclerotic plaques. A minor fraction of the total LDL has an electronegative charge and is represented by a heterogenic subpopulation of particles [LDL(-)], with higher potential to induce endothelial injury. It could be derived from oxidation, glication or other processes that alter its chemical composition and is increased in diabetic, hypercholesterolemic subjects, and in those with established coronary artery disease. mLDL are internalized by macrophages through scavenger receptors, originating foam cells and inducing an immune-inflammatory reaction. In the atherosclerotic process, the action of mLDL continues until plaque rupture and thrombogenesis, when it promotes apoptosis in endothelial and smooth muscle cells, and activates matrix metalloproteinases, weaken the fibrous cap, and further enhance the inflammatory process that ends in the thrombus formation. Development of new laboratory methods is necessary to enhance the clinical applicability of mLDL and the predictive power of the conventional lipid profile and other cardiovascular risk factors of the MS.

Modulation of aromatase activity by diet polyphenolic compounds

Estrogens are involved in physiological actions related to reproduction, body fat distribution, and maintenance of bone mass and are also related to the pathogenesis of estrogen-dependent cancers. The aim of this work was to study the effect of polyphenols on estrogen synthesis. The effect of polyphenols and polyphenolic-rich beverages on aromatase activity was tested in JAR cells (a choriocarcinoma cell line) through the tritiated water release assay. Some of the tested polyphenols inhibited estrogen production, chrysin being the most potent. Additionally, we observed that red wine, alcohol-free red wine, green tea, and black tea (200 microL/mL) significantly decreased aromatase activity. No effect on aromatase expression, as assessed by western blotting and RT-PCR, has been detected after 24 h of treatment with any of the flavonoids under study. In conclusion, polyphenols are able to modulate aromatase activity and, consequently, estrogen synthesis. The knowledge of such interference may help to clarify some of the biological properties attributed to polyphenols and may be useful in prevention/treatment of estrogen-dependent disorders.

Using endophenotypes for pathway clusters to map complex disease genes

Nature determines the complexity of disease etiology and the likelihood of revealing disease genes. While culprit genes for many monogenic diseases have been successfully unraveled, efforts to map major complex disease genes have not been as productive as hoped. The conceptual framework currently adopted to deal with the heterogeneous nature of complex diseases focuses on using homogeneous internal features of the disease phenotype for mapping. However, phenotypic homogeneity does not equal genotypic homogeneity. In this report, we advocate working with well-measured phenotypes portrayed by amounts of transcripts and activities of gene products or their metabolites, which are pertinent to relatively small pathway clusters. Reliable and controlled measures for oligogenic traits resulting from proper dissection efforts may enhance statistical power. The large amounts of information obtained on gene and protein expression from technological advances can add to the power of gene finding, particularly for diseases with unclear etiology. Data-mining tools for dimension reduction can assist biologists to reveal novel molecular endophenotypes. However, there are still hurdles to overcome, including high cost, relatively poor reproducibility and comparability among platforms, the cross-sectional nature of the information, and the accessibility of human tissues. Concerted efforts are required to carry out large-scale prospective studies that are integrated at the levels of phenotype characterization, high throughput experimental techniques, data analyses, and beyond.

Transcriptional regulation of metabolism

Our understanding of metabolism is undergoing a dramatic shift. Indeed, the efforts made towards elucidating the mechanisms controlling the major regulatory pathways are now being rewarded. At the molecular level, the crucial role of transcription factors is particularly well-illustrated by the link between alterations of their functions and the occurrence of major metabolic diseases. In addition, the possibility of manipulating the ligand-dependent activity of some of these transcription factors makes them attractive as therapeutic targets. The aim of this review is to summarize recent knowledge on the transcriptional control of metabolic homeostasis. We first review data on the transcriptional regulation of the intermediary metabolism, i.e., glucose, amino acid, lipid, and cholesterol metabolism. Then, we analyze how transcription factors integrate signals from various pathways to ensure homeostasis. One example of this coordination is the daily adaptation to the circadian fasting and feeding rhythm. This section also discusses the dysregulations causing the metabolic syndrome, which reveals the intricate nature of glucose and lipid metabolism and the role of the transcription factor PPARgamma in orchestrating this association. Finally, we discuss the molecular mechanisms underlying metabolic regulations, which provide new opportunities for treating complex metabolic disorders.

Regional fat localizations and racial/ethnic variations in odds of hypertension in at-risk American adults

The objective of this study was to determine the contribution of regional fat localizations defined as abdominal (AO) or truncal (TO) obesity in racial/ethnic differences to the prevalence odds of hypertension in overweight American adults. Data (n=5,694) from the 1999-2002 US National Health and Nutrition Examination Survey were utilized for this analysis. Abdominal obesity was defined as waist circumference >or=102 and >or=88 cm for men and women, respectively. Truncal obesity was defined using ratio of subscapular to triceps skinfold thickness and were >or=2.24 and >or=1.32, for men and women, respectively. Prevalence odds ratios from gender-specific logistic regression models were used to evaluate the contribution of regional fat localizations to racial/ethnic variation in hypertension. Statistical adjustment was made for age, education, alcohol intake and body mass index. In both men and women, coexistence of AO and TO was associated with much higher prevalence odds of hypertension than association due to each of the regional fat localizations. In men, coexistence of AO and TO was associated with 1.99, 2.47 and 2.10 increased prevalence odds of hypertension in Whites, Blacks and Mexican Americans, respectively. The corresponding values in women were 2.83, 4.07 and 3.61 in Whites, Blacks and Mexican Americans, respectively. The coexistence of AO and TO appears to be the culprit that contributes to high blood pressure on top of body mass index. Weight reduction programs that are targeted toward abdominal and truncal regions in at-risk populations and along racial/ethnic lines may help to alleviate racial/ethnic disparity in risk of hypertension.

Accurate quantification of visceral adipose tissue (VAT) using water-saturation MRI and computer segmentation: Preliminary results

PURPOSE

To describe and evaluate the accuracy of water-saturation MRI and a computer segmentation program for quantification of visceral adipose tissue (VAT).

MATERIALS AND METHODS

MRI was performed on five patients with whole-volume coverage of the abdomen using two different sequences: 1) a T1-weighted spoiled gradient-echo breath-hold sequence (non-water-saturation) and 2) a T1-weighted spoiled gradient-echo water-saturation breath-hold sequence (water-saturation). The computer segmentation program analyzed the data and calculated VAT volumes (cm3) from both sequences. The data from one patient were additionally processed with the use of a manual technique. The intrastudy reproducibility of the proposed method using the water-saturation MRI sequence and the computer segmentation technique was tested by repeated measures of the automated system analysis (x 10) on MRI data from a single subject to calculate variability.

RESULTS

VAT volumes measured by the water-saturation MRI sequences were consistently greater than those measured by the non-water-saturation sequences. Comparison of VAT volumes derived from the water-saturation images and measured by the computer segmentation technique vs. the manual technique showed good correlation (K = 0.8), with a significant time-saving benefit associated with the automated method (5 minutes vs. 1 hour). There was poor correlation between VAT volume measurement calculated by the manual technique and the computer segmentation technique using non-water-saturation images. The reproducibility of the computer segmentation technique using data derived from water-saturation images was high, with a low variability (+/- 5%).

CONCLUSION

The results obtained demonstrate that the proposed method may be able to provide accurate quantification of VAT in a highly reproducible and efficient manner.

Regional differences in adipose tissue metabolism in women: minor effect of obesity and body fat distribution

Studies comparing adipose tissue metabolism in central versus peripheral fat depots have generated equivocal data. We examined whether regional differences in abdominal subcutaneous and omental adipose tissue metabolism in women exist and whether they persist across the spectrum of body fatness and abdominal adiposity values. We measured adipocyte size; lipoprotein lipase (LPL) activity; and basal, isoproterenol-, forskolin-, and dibutyryl cAMP-stimulated lipolysis in adipose tissue or mature adipocytes isolated from the omental and subcutaneous fat depots in a sample of 55 healthy women undergoing elective gynecological surgery. Measures of body fat mass and body fat distribution were also obtained by dual-energy X-ray absorptiometry and computed tomography. Subcutaneous adipocytes were significantly larger than omental adipocytes (P < 0.0001). LPL activity expressed as a function of cell number was significantly higher in subcutaneous versus omental adipose tissue (P < 0.0001). Basal, isoproterenol-stimulated, dibutyryl cAMP-stimulated (10(-3) mol/l) and forskolin-stimulated (10(-5) mol/l) lipolysis (expressed as a function of cell number) were all significantly higher in subcutaneous versus omental adipocytes (P < 0.05 to P < 0.0001). However, the response of omental adipocytes to lipolytic stimuli tested (fold increase over basal level) was significantly greater in magnitude compared with subcutaneous adipocytes (P < 0.01). These differences were relatively constant across total body fat mass and visceral adipose tissue area tertiles. In conclusion, compared with adipocytes from the omental fat compartment, subcutaneous adipocytes are larger, have higher LPL activity, and are more lipolytic on an absolute basis, which may reflect a higher fat storage capacity in this depot in women. In contrast, omental adipocytes display greater relative responsiveness to both adrenergic receptor-and postreceptor-acting agents compared with subcutaneous adipocytes. Overall and visceral obesity have only minor effects on regional differences in adipose tissue metabolism.

Role of hypoadiponectinemia in the metabolic syndrome and its association with post-glucose challenge hyper-free fatty acidemia: a study in prediabetic Japanese males

We investigated the role of hypoadiponectinemia in the metabolic syndrome (MS), as well as its association with post-glucose challenge hyper-free fatty acidemia in the clinical setting. The study subjects comprised 177 corporate employees shown to have a fasting plasma glucose (FPG) level of 125 mg/dL or less in a 75 g OGTT in the corporation's healthcare center. When divided into those who met the Japanese criteria for the metabolic syndrome (MS group; n = 45) and those who did not (Non-MS group; n = 132), the MS group was shown to have significantly lower adiponectin levels than the Non-MS group, and tended to show higher high-sensitivity C-reactive protein (CRP) values than the Non-MS group, while not achieving statistical significance. The MS group showed higher baseline glucose levels; higher baseline, 30-, 60-, and 120-min post-challenge insulin levels; higher 30-, 60-, and 120-min post-challenge free fatty acid levels than the Non-MS group. Additionally, there was a significant, negative correlation between adiponectin levels, area under the free fatty acid curve, and area under the insulin curve at OGTT (r = -0.24, p < 0.01; r = -0.21, p < 0.01, respectively). When the patients were divided by adiponectin level into four groups to examine the number of risk factors for MS detected per patient and the incidence of MS, the lower the adiponectin level, the more risk factors were found per patient, with 68% of patients with an adiponectin level of less than 4 microg/mL found to have MS. In those with an adiponectin level of less than 4 microg/mL, BMI values, uric acid levels, HOMA-R values, and the number of risk factors for MS involved per patient were shown to be higher than in those with an adiponectin level of 4 microg/mL or greater. Furthermore, the following risk factors for MS were more frequently found in those with an adiponectin level of less than 4 microg/mL than in those with an adiponectin level of 4 microg/mL or greater: VFA > or = 100 cm2 (OR 12.8, p < 0.001); TG > or = 150 mg/dL (OR 3.2, p < 0.05); HDLC < 40 mg/dL (OR 1.9, p = 0.29); BP > or = 130/85 mmHg (OR 2.2, p = 0.15); and FPG > or = 110 mg/dL (OR 1.9, p = 0.29). Again, the incidence of MS (OR 7.6, p < 0.001) by the ATPIII criteria, as well as that by the Japanese criteria (OR 8.6, p < 0.001), was found to be higher in those with an adiponectin level of less than 4 microg/mL than in those with an adiponectin level of 4 microg/mL or greater. Our study results suggest that adiponectin is closely associated with the multiple risk factors that go to make up the MS, suggesting a role for hypoadiponectinemia as a surrogate marker for the MS and further appear to suggest that post-challenge hyper-free fatty acidemia may account in part for hypoadiponectinemia in the MS.

Gonadal hormones determine sensitivity to central leptin and insulin

Males have proportionally more visceral fat and are more likely to develop complications associated with obesity than females, and the male brain is relatively more sensitive to the catabolic action of insulin and less sensitive to that of leptin than the female brain. To understand the underlying mechanism, we manipulated estrogen through ovariectomy (OVX) and estradiol administration. Rats with relatively high systemic estrogen (intact females and OVX females and males administered estrogen subcutaneously) were significantly more sensitive to leptin's anorexic action in the brain (i3vt), as well as significantly less sensitive to insulin's i3vt action, than intact males. Administering estradiol directly into the brain of our females increased i3vt leptin sensitivity while decreasing i3vt insulin sensitivity and changed the body fat distribution of our females to resemble that of intact females. These data indicate that estrogen acts within the brain to increase leptin sensitivity, decrease insulin sensitivity, and favor subcutaneous over visceral fat.

Endothelial dysfunction in PCOS: role of obesity and adipose hormones

PURPOSE

Polycystic ovary syndrome (PCOS) is an extremely prevalent disorder in which elevated blood markers of cardiovascular risk and altered endothelial function have been found. This study was designed to determine if abnormal carotid intima-media thickness (IMT) and brachial flow-mediated dilation (FMD) in young women with PCOS may be explained by insulin resistance and elevated adipocytokines.

METHODS

A prospective study in 50 young women with PCOS (age: 25.2 +/- 1 years; body mass index [BMI]: 28.7 +/- 0.8) and 50 matched ovulatory controls (age: 25.1 +/- 0.7 years; BMI: 28.5 +/- 0.5) was performed. Carotid IMT, brachial FMD, and blood for fasting glucose, insulin, leptin, adiponectin and resistin were measured.

RESULTS

PCOS, IMT was increased (P <.01), FMD was decreased (P <.01), fasting insulin was increased (P <.01), QUICKI (a marker of insulin resistance) was decreased (P <.01), and adiponectin was lower (P <.05), whereas leptin and resistin were not different compared with matched controls. Whereas BMI or waist/hip ratios did not correlate with IMT or FMD, insulin and QUICKI correlated positively and negatively with IMT (P <.01). There was a significant negative correlation between adiponectin and IMT (P <.05). These correlations were unchanged when adjusting for BMI and the correlation between IMT and adiponectin was unaffected by insulin resistance parameters.

CONCLUSIONS

These data suggest that young women with PCOS have evidence for altered endothelial function. Adverse endothelial parameters were correlated with insulin resistance and lower adiponectin. Both insulin resistance and adiponectin appear to be important parameters. It is hypothesized that the type of fat distribution may influence these factors.

O sistema endocanabinóide: novo paradigma no tratamento da síndrome metabólica

O balanço energético é um dos mais importantes mecanismos de homeostase e de sobrevivência das espécies. O sistema endocanabinóide é um novo e importante componente entre estes mecanismos. Os seus receptores e agonistas endógenos se expressam no sistema nervoso central (SNC) e perifericamente, em vários sítios, estabelecendo uma rede de comunicação periferiaSNC. Um aspecto marcante é a sua expressão no tecido adiposo, onde regula a lipogênese e aumenta a expressão de genes influentes no metabolismo dos lipídeos e dos carboidratos. Estes aspectos são importantes para o controle do peso corporal e da Síndrome Metabólica (SM). O sistema é ativado sob demanda e desativado rapidamente, atuando autócrina e paracrinamente, e as evidências sugerem que mantém-se hiperativado em estados de obesidade. Um antagonista específico do seu principal receptor (CB1), o Rimonabant, tem se mostrado importante ferramenta no controle do peso em modelos animais de obesidade e de SM. Da mesma forma, grandes estudos em humanos confirmam sua eficácia no controle do peso e das variáveis metabólicas, sugerindo um papel importante deste medicamento para o controle do risco cardiovascular associado à SM.

Lipoprotein lipase gene S447X polymorphism modulates the relation between central obesity and serum lipids, a twin study

OBJECTIVE

To investigate the impact of lipoprotein lipase (LPL) gene S447X polymorphism on the relation between central obesity and lipid levels.

DESIGN

A total of 961 adult twin pairs were included from the program of Chinese Twin Registry, between 2001 and 2002. Central obesity was defined as waist circumference > or =90 cm for male and > or =80 cm for female. Two statistical methods were performed to test the modification effect of S447X polymorphism of LPL gene on the relation between central obesity and lipid levels: one was Generalized Estimating Equation (GEE) models for all twin pairs and the other was co-twin matched case-control analysis in 82 central obesity discordant monozygotic twin pairs.

RESULTS

In GEE models for all twins, central obesity was significantly associated with serum lipids except for high-density lipoprotein (HDL), while X447 allele had favorable effects on the levels of triglyceride (TG), HDL and TG to HDL ratio (TG/HDL). The interactions of S447X polymorphism and central obesity were statistically significant for TG/HDL and HDL. In central obesity discordant monozygotic twin pairs, central obesity was significantly related with 26.2% increase of TG and 27.2% increase of TG/HDL in S/S447 genotype, while in 447X allele carrier, central obesity was significantly related with 13.7% increase of HDL.

CONCLUSION

These results suggest that LPL gene S447X polymorphism modifies the relation between central obesity and serum lipids, which also stresses the importance of reducing waist circumference to improve serum lipids for people with central obesity, especially those with S/S447 genotype.

Epicardial adipose tissue: anatomic, biomolecular and clinical relationships with the heart

A growing amount of evidence suggests that regional fat distribution plays an important part in the development of an unfavorable metabolic and cardiovascular risk profile. Epicardial fat is a metabolically active organ that generates various bioactive molecules, which might significantly affect cardiac function. This small, visceral fat depot is now recognized as a rich source of free fatty acids and a number of bioactive molecules, such as adiponectin, resistin and inflammatory cytokines, which could affect the coronary artery response. The observed increases in concentrations of inflammatory factors in patients who have undergone coronary artery bypass grafting remain to be confirmed in healthy individuals. Furthermore, epicardial adipose mass might reflect intra-abdominal visceral fat. Therefore, we propose that echocardiographic assessment of this tissue could serve as a reliable marker of visceral adiposity. Epicardial adipose tissue is also clinically related to left ventricular mass and other features of the metabolic syndrome, such as concentrations of LDL cholesterol, fasting insulin and adiponectin, and arterial blood pressure. Echocardiographic assessment of epicardial fat could be a simple and practical tool for cardiovascular risk stratification in clinical practice and research. In this paper, we briefly review the rapidly emerging evidence pointing to a specific role of epicardial adipose tissue both as a cardiac risk marker and as a potentially active player in the development of cardiac pathology.

The metabolic syndrome in polycystic ovary syndrome

Much overlap is present between the polycystic ovary syndrome (PCOS) and the metabolic syndrome. This article reviews the existing data regarding the prevalence, characteristics, and treatment of the metabolic syndrome in women with PCOS. The prevalence of the metabolic syndrome in PCOS is approximately 43-47%, a rate 2-fold higher than that for women in the general population. High body mass index and low serum HDL cholesterol are the most frequently occurring components of the metabolic syndrome in PCOS. The pathogenic link between the metabolic syndrome and PCOS is most likely insulin resistance. Therefore, the presence of the metabolic syndrome in PCOS suggests a greater degree of insulin resistance compared to PCOS without the metabolic syndrome. Obesity, atherogenic dyslipidemia, hypertension, impaired fasting glucose/impaired glucose tolerance, and vascular abnormalities are all common metabolic abnormalities present in PCOS. Lifestyle modification has proven benefit and pharmacological therapy with insulin-sensitizing agents has potential benefit in the treatment of the metabolic syndrome in women with PCOS.

Leptin and Adiponectin in the HIV Associated Metabolic Syndrome: Physiologic and Therapeutic Implications

Leptin and adiponectin represent two newly discovered adipose tissue derived hormones with important roles in energy homeostasis and insulin resistance. Their interrelations with the manifestations of the HIV associated metabolic syndrome and specific somatomorphic changes i.e. fat redistribution is reviewed. A synopsis of published studies is presented and the potential role of leptin and adiponectin is discussed. We have described an association of the HIV metabolic syndrome with a state of reduced insulin sensitivity due to adiponectin deficiency. The metabolic syndrome is also accompanied by leptin deficiency in lipoatrophic subjects and possibly by a leptin resistance state in lipohypertrophic patients. Adiponectin and / or leptin therapy in a manner similar to other leptin deficiency states may assist in the future management of such patients.

Metabolic syndrome in the elderly

The prevalence of metabolic syndrome is increasing worldwide, especially among the elderly. Due to multiple age-related physiologic mechanisms, the elderly are at increased risk of developing intra-abdominal obesity and the metabolic syndrome, including nonalcoholic steatohepatitis. Metabolic syndrome consists of obesity, insulin resistance, dyslipidemia, and hypertension leading to increased risk of cardiovascular disease (CVD) and renal events. With the future population dynamics, the metabolic syndrome should be emphasized among the health care field, researchers, and clinicians. Without proactive and preventative efforts, elderly patients and the health care system will likely experience an epidemic of the metabolic syndrome and the associated CVD.

Adipocyte-derived hormones, cytokines, and mediators

Adipose tissue is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. These secreted proteins, which include tumor necrosis factor (TNF)-alpha, resistin, IL-6, IL-8, acylation-stimulating protein (ASP), angiotensinogen, plasminogen activator inhibitor-1 (PAI-1) ("bad" adipokines) and leptin, adiponectin ("good" adipokines) seem to play important regulatory roles in a variety of complex processes, including fat metabolism, feeding behavior, hemostasis, vascular tone, energy balance, and insulin sensitivity, but none is without controversy regarding its respective mechanism and scope of action. The present review is focused on the effects of free fatty acids and a restricted number of adipokines, which have been implicated in vascular (angiotensinogen, PAI-1) and energy and glucose homeostasis (ASP, TNFalpha, IL-6, resistin, leptin, adiponectin).

Visceral fat is an independent predictor of all-cause mortality in men

OBJECTIVE

To examine the independent associations of abdominal fat (visceral and subcutaneous) and liver fat with all-cause mortality.

RESEARCH METHODS AND PROCEDURES

Participants included 291 men [97 decedents and 194 controls; mean age, 56.4 +/- 12.0 (SD) years] who received a computed tomography (CT) examination at the preventive medicine clinic in Dallas, TX, between 1995 and 1999, with a mean mortality follow-up of 2.2 +/- 1.3 years. Abdominal fat was determined using contiguous CT images from the L3-L4 to L4-L5 intervertebral space. Liver fat was assessed using the CT-determined liver attenuation value, which is inversely related to liver fat. Logistic regression was used to determine the independent association between the fat depots and all-cause mortality.

RESULTS

During the study, there were 97 deaths. Visceral fat [odds ratio (OR) per SD: 1.83; 95% CI: 1.23 to 2.73], abdominal subcutaneous fat (1.44; 1.02 to 2.03), liver fat (0.64; 0.46 to 0.87), and waist circumference (1.41; 1.01 to 1.98) were significant individual predictors of mortality after controlling for age and length of follow-up. In a model including all three fat measures (subcutaneous, visceral, and liver fat), age, and length of follow-up, only visceral fat (1.93; 1.15 to 3.23) was a significant predictor of mortality.

DISCUSSION

Visceral fat is a strong, independent predictor of all-cause mortality in men.

Differences in the pathology of the metabolic syndrome with or without visceral fat accumulation: a study in pre-diabetic Japanese middle-aged men

To elucidate the role of visceral fat accumulation in the metabolic syndrome, differences in the pathology of the metabolic syndrome with or without visceral fat accumulation were investigated. A total of 472 prediabetic Japanese men (mean age, 47.5 +/- 7.2 yr) with impaired fasting glycemia (IFG) levels of 110-125 mg/dL were eligible for participation in the study. The study subjects were divided into the following four groups, and intergroup comparisons were made: group I without visceral fat area [VFA] > or = 100 cm2 but presenting with fewer than two other risk factors (i.e., TG > or =150 mg/dL, HDL-C < 40 mg/dL, BP > or = 130/ > or = 85 mmHg, or FPG > or = 110 mg/dL) (n = 231); group II without VFA of > or = 100 cm2 but presenting with three or more other risk factors (n = 57); group III with VFA of > or = 100 cm2 accompanied by FPG 110 mg/dL alone (n = 27); and group IV with VFA > or =100 cm2 and two or more other risk factors (n = 157). The prevalence of patients who had three or more risk factors with or without VFA > or = 100 cm2 was 45.3% (214 out of 472 patients), while that of those with VFA > or = 100 cm2 who had two or more other risk factors was 33% (157 out of 472 patients). Group II had significantly higher VFA values than group I (p < 0.05), and group IV had significantly higher VFA values than group II (p < 0.001). While no significant differences in HOMA-R values were seen between groups I and II, these values were significantly higher in group IV compared to groups I and II (p < 0.001 and p < 0.05, respectively). Furthermore, group IV showed significantly higher 2-h insulin levels after glucose loading compared to group I (p < 0.001). While no significant differences were seen between groups II and IV, insulin levels tended to be higher in group IV. Adiponectin levels showed an incremental fall in VFA from group I through groups II and III to group IV. Groups III and IV showed significantly lower adiponectin levels compared to group I (p < 0.05, p < 0.001, respectively); and group IV showed significantly lower adiponectin levels than group II (p < 0.05). A logistic regression analysis using VFA, TG and HDL-C, and BP as explanatory variables showed that the relative risk for high HOMAR values were 2.65 (p < 0.001) for patients with VFA > or =100 cm2; 1.64 (p < 0.05) for those with TG > or = 150 mg/dL and HDL < 40 mg/dL; and 1.79 (p < 0.01) for those with BP > or = 130/ > or = 85 mmHg. These findings demonstrate that the degree of insulin resistance and the risk of arteriosclerosis vary depending on whether or not the metabolic syndrome accompanied by a clustering of risk factors has visceral fat accumulation as an underlying pathology, strongly suggesting a crucial role for visceral fat accumulation in the metabolic syndrome.

Growth hormone receptor deficiency results in blunted ghrelin feeding response, obesity, and hypolipidemia in mice

We have previously shown that growth hormone (GH) overexpression in the brain increased food intake, accompanied with increased hypothalamic agouti-related protein (AgRP) expression. Ghrelin, which stimulates both appetite and GH secretion, was injected intracerebroventricularly to GHR-/- and littermate control (+/+) mice to determine whether ghrelin's acute effects on appetite are dependent on GHR signaling. GHR-/- mice were also analyzed with respect to serum levels of lipoproteins, apolipoprotein (apo)B, leptin, glucose, and insulin as well as body composition. Central injection of ghrelin into the third dorsal ventricle increased food consumption in +/+ mice, whereas no change was observed in GHR-/- mice. After ghrelin injection, AgRP mRNA expression in the hypothalamus was higher in +/+ littermates than in GHR-/- mice, indicating a possible importance of AgRP in the GHR-mediated effect of ghrelin. Compared with controls, GHR-/- mice had increased food intake, leptin levels, and total and intra-abdominal fat mass per body weight and deceased lean mass. Moreover, serum levels of triglycerides, LDL and HDL cholesterol, and apoB, as well as glucose and insulin levels were lower in the GHR-/- mice. In summary, ghrelin's acute central action to increase food intake requires functionally intact GHR signaling. Long-term GHR deficiency in mice is associated with high plasma leptin levels, obesity, and increased food intake but a marked decrease in all lipoprotein fractions.

Gender differences in the metabolic syndrome and their role for cardiovascular disease

Women live longer than men and develop cardiovascular disease (CVD) at an older age. The metabolic syndrome represents a major risk factor for the development of CVD, and gender differences in this syndrome may contribute to gender differences in CVD. In recent years, the metabolic syndrome has been more prevalent in men than in women. Prevalence is increasing and this increase has been steeper in women, particularly in young women, during the last decade. The contributions of the different components of the metabolic syndrome differ between genders and in different countries. In a recent survey in Germany, 40% of the adult population had been diagnosed with disturbed glucose tolerance or type 2 diabetes. Undiagnosed diabetes was more frequent in men than in women, and risk factors for undiagnosed diabetes differed between the sexes. Worldwide, in individuals with impaired glucose tolerance, impaired fasting glucose was observed more frequently in men, whereas impaired glucose tolerance occurred relatively more often in women. Lipid accumulation patterns differ between women and men. Premenopausal women more frequently develop peripheral obesity with subcutaneous fat accumulation, whereas men and postmenopausal women are more prone to central or android obesity. In particular, android obesity is associated with increased cardiovascular mortality and the development of type 2 diabetes. Visceral adipocytes differ from peripheral adipocytes in their lipolytic activity and their response to insulin, adrenergic and angiotensin stimulation and sex hormones. Visceral fat is a major source of circulating free fatty acids and cytokines, which are directly delivered via the portal vein to the liver inducing insulin resistance and an atherogenic lipid profile. Inflammation increases cardiovascular risk particularly in women. A relatively greater increase in cardiovascular risk by the appearance of diabetes in women has been reported in many studies.Thus, the presently available data suggest that the pathophysiology of the metabolic syndrome and its contribution to the relative risk of cardiovascular events and heart failure show gender differences, which might be of potential relevance for prevention, diagnostics, and therapy of the syndrome.

Fully automated large-scale assessment of visceral and subcutaneous abdominal adipose tissue by magnetic resonance imaging

OBJECTIVE

To describe and evaluate a fully automated method for characterizing abdominal adipose tissue from magnetic resonance (MR) transverse body scans.

METHODS

Four MR pulse sequences were applied: SE, FLAIR, STIR, and FRFSE. On 39 subjects, each abdomen was traversed by 15 contiguous transaxial images. The total abdominal adipose tissue (TAAT) was calculated from thresholds obtained by slice histogram analysis. The same thresholds were also used in the manual volume calculation of TAAT, subcutaneous abdominal adipose tissue (SAAT) and visceral abdominal adipose tissue (VAAT). Image segmentation methods, including edge detection, mathematical morphology, and knowledge-based curve fitting, were used to automatically separate SAAT from VAAT in various 'nonstandard' cases such as those with heterogeneous magnetic fields and movement artefacts.

RESULTS

The percentage root mean squared errors of the method for SAAT and VAAT ranged from 1.0 to 2.7% for the four sequences. It took approximately 7 and 15 min to complete the 15-slice volume estimation of the three adipose tissue classes using automated and manual methods, respectively.

CONCLUSION

The results demonstrate that the proposed method is robust and accurate. Although the separation of SAAT and VAAT is not always perfect, this method could be especially helpful in dealing with large amounts of data such as in epidemiological studies.

Non-alcoholic fatty liver disease is associated with carotid artery wall thickness in diet-controlled type 2 diabetic patients

Non-alcoholic fatty liver disease (NAFLD) is closely associated with several metabolic syndrome (MetS) features. We assessed whether NAFLD is significantly associated with carotid artery intima-media thickness (IMT), as a marker of subclinical atherosclerosis, and whether such association is independent of classical cardiovascular risk factors and MetS features. We studied 100 diet-controlled Type 2 diabetic patients with ultrasonographically diagnosed NAFLD and 100 diabetic patients without NAFLD who were comparable for age and sex. Main outcome measures were carotid IMT (by ultrasonography), classical risk factors, insulin resistance [as estimated by homeostasis model assessment (HOMA)-IR] and MetS (as defined by the Adult Treatment Panel III criteria). NAFLD patients had a markedly greater carotid IMT (1.24 +/- 0.13 vs 0.95 +/- 0.11 mm; p < 0.001) than those without the condition. The MetS and all its clinical traits were more highly prevalent in those with NAFLD (p < 0.001). Adjustment for age, sex, smoking history, diabetes duration, glycosylated hemoglobin, LDL cholesterol, liver enzymes and microalbuminuria did not really affect the significant differences in carotid IMT that were observed between the groups. Further adjustment for the MetS also had little impact, but additional adjustment for HOMA-IR score consistently attenuated any statistical significance (p = 0.28). In multivariate regression analysis, HOMA-IR score along with age and MetS (principally raised blood pressure values) were independently related to carotid IMT, whereas NAFLD was not. In conclusion, these results suggest that among diet-controlled Type 2 diabetic individuals the significant increase of carotid IMT in the presence of NAFLD is largely explained by HOMA-estimated insulin resistance.

The beneficial effects of high-density lipoprotein on adipocytes may relate to its anti-atherogenic properties

High-density lipoprotein (HDL) has significant anti-atherogenic properties, whereas the underlying mechanisms are complex and have not been completely elucidated. Adipocytes produce a variety of adipokines with cardiovascular effects. The dysregulated secretion of adipokines by adipocytes may contribute to the increased risk of atherosclerosis associated with obesity. Clinical evidences indicate that higher plasma HDL-C levels are associated with a favourable adipokines secretion profile, suggesting that HDL might improve the dysregulated adipokines secretion. HDL may diminish lipid accumulation in adipocytes through phosphorylation of PPARgamma and inhibition of aP2 expression, which possibly account for the favourable effects of HDL on adipokines secretion. Therefore, we hypothesize that HDL might exert several beneficial effects on adipocytes, which may relate to its anti-atherogenic properties.

Botulinum toxin injections to reduce adiposity: Possibility, or fat chance?

Obese individuals often suffer from negative self-image. Many, even those with a normal body mass index, resort to pharmacotherapy (lipase inhibitors or appetite suppressants), mesotherapy and surgery (gastric volume reduction, liposuction or apronectomy) in a bid to remove excess adipose tissue. These treatments are associated with inherent morbidity and even mortality, and hence should not be undertaken lightly. The observation that denervation of adipose tissue results in lipoatrophy leads us to postulate that chemodenervation using botulinum toxin may achieve the same result, i.e. fat loss, and we explore the methods by which selective fat loss may be achieved. We concede that removal of subcutaneous fat does not, however, reduce the risks associated with the metabolic syndrome, as visceral (intra-abdominal) fat is not reduced by the removal of subcutaneous fat.

Whole-body T1 mapping improves the definition of adipose tissue: Consequences for automated image analysis

PURPOSE

To determine whether a whole-body T1-mapping acquisition method improves the definition of adipose tissue (AT) and simplifies automated AT segmentation compared to an image-based method.

MATERIALS AND METHODS

The study included 10 subjects. Two whole-body volumes were acquired from each subject using two different flip angles. Whole-body T1 maps were calculated from each pair of whole-body volumes. AT was automatically segmented from the T1 maps and from the original image slices. The results were evaluated using manually segmented slices as reference.

RESULTS

The T1-mapping method segmented more of the reference AT than the image-based method, with mean values (standard deviations (SDs)) of 87.7(5.1)% and 81.1(5.2)%, respectively. Compared to the image-based method, the T1-mapping method gives better histogram separation of AT in whole-body volumes. The suggested method also provides an output with smaller in-slice AT intensity variations.

CONCLUSION

The T1-mapping method improves the definition of AT. T1-based analysis is superior to analysis based on the original images, and allows fully automated and accurate whole-body AT segmentation.

Climacteric obesity: from genesis to clinic

The etiology of obesity is multifactorial and still unclear. Genetic factors play a significant role and include several gene candidates: polymorphisms of genes for ss(2)-adrenoreceptor, resistin, estrogen receptor-a and peroxisome proliferator-activated receptor-gamma. Moreover, peptides regulating hunger and satiety, e.g. leptin, galanin, cholecystokinin and neuropeptide Y, and altered nutritional patterns have been implicated. Also, factors associated with aging, e.g. decreased levels of growth hormone and dehydroepiandrosterone, and the activity of the sympathetic nervous system (resting metabolism and thermogenesis) cannot be disregarded. Participation of the sex steroids and inflammatory factors has also been postulated in the etiology of obesity. Three phenotypes of obesity are postulated; however, the visceral (abdominal) phenotype is typical of postmenopausal women and is characterized by several metabolic disorders with high risks of diabetes mellitus type 2 and cardiovascular disease. On the basis of personal experience and data from evidence-based medicine, diagnostic-therapeutic algorithms of climacteric obesity are presented.

Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism

Obesity is becoming a global epidemic in both children and adults. It is associated with numerous comorbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, obesity is an independent risk factor for CVD, and CVD risks have also been documented in obese children. Obesity is associated with an increased risk of morbidity and mortality as well as reduced life expectancy. Health service use and medical costs associated with obesity and related diseases have risen dramatically and are expected to continue to rise. Besides an altered metabolic profile, a variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amounts, even in the absence of comorbidities. Hence, obesity may affect the heart through its influence on known risk factors such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, obstructive sleep apnea/hypoventilation, and the prothrombotic state, in addition to as-yet-unrecognized mechanisms. On the whole, overweight and obesity predispose to or are associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death because of their impact on the cardiovascular system. The pathophysiology of these entities that are linked to obesity will be discussed. However, the cardiovascular clinical evaluation of obese patients may be limited because of the morphology of the individual. In this statement, we review the available evidence of the impact of obesity on CVD with emphasis on the evaluation of cardiac structure and function in obese patients and the effect of weight loss on the cardiovascular system.

Disorders of glucose metabolism in sleep apnea

Sleep is a complex behavioral state that occupies one-third of the human life span. Although viewed as a passive condition, sleep is a highly active and dynamic process. The sleep-related decrease in muscle tone is associated with an increase in resistance to airflow through the upper airway. Partial or complete collapse of the airway during sleep can lead to the occurrence of apneas and hypopneas during sleep that define the syndrome of sleep apnea. Sleep apnea has become pervasive in Western society, affecting approximately 5% of adults in industrialized countries. Given the pandemic of obesity, the prevalence of Type 2 diabetes mellitus and metabolic syndrome has also increased dramatically over the last decade. Although the role of sleep apnea in cardiovascular disease is uncertain, there is a growing body of literature that implicates sleep apnea in the pathogenesis of altered glucose metabolism. Intermittent hypoxemia and sleep fragmentation in sleep apnea can trigger a cascade of pathophysiological events, including autonomic activation, alterations in neuroendocrine function, and release of potent proinflammatory mediators such as tumor necrosis factor-alpha and interleukin-6. Epidemiologic and experimental evidence linking sleep apnea and disorders of glucose metabolism is reviewed and discussed here. Although the cause-and-effect relationship remains to be determined, the available data suggest that sleep apnea is independently associated with altered glucose metabolism and may predispose to the eventual development of Type 2 diabetes mellitus.

Vaspin gene expression in human adipose tissue: association with obesity and type 2 diabetes

Recently, vaspin was identified as an adipokine with insulin-sensitizing effects, which is predominantly secreted from visceral adipose tissue in a rat model of type 2 diabetes. In this study, we examined whether vaspin mRNA expression is a marker of visceral obesity and correlates with anthropometric and metabolic parameters in paired samples of visceral and subcutaneous adipose tissue from 196 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance. Vaspin mRNA expression was only detectable in 23% of the visceral and in 15% of the subcutaneous (SC) adipose tissue samples. Vaspin mRNA expression was not detectable in lean subjects (BMI<25) and was more frequently detected in patients with type 2 diabetes. No significant correlations were found between visceral vaspin gene expression and visceral fat area or SC vaspin expression. However, visceral vaspin expression significantly correlates with BMI, % body fat, and 2 h OGTT plasma glucose. Subcutaneous vaspin mRNA expression is significantly correlated with WHR, fasting plasma insulin concentration, and glucose infusion rate during steady state of an euglycemic-hyperinsulinemic clamp. Multivariate linear regression analysis revealed % body fat as strongest predictor of visceral vaspin and insulin sensitivity as strongest determinant of SC vaspin mRNA expression. In conclusion, our data indicate that induction of human vaspin mRNA expression in adipose tissue is regulated in a fat depot-specific manner and could be associated with parameters of obesity, insulin resistance, and glucose metabolism.

Consequences of menopause in women with diabetes mellitus - a clinical problem

Human life was prolonged by 30 years in the past century, with the result that about 40% of a woman's life falls within the postmenopausal period. The consequences, both early and remote, in the form of cardiovascular disease, osteoporosis and neoplastic disease are most pronounced in women suffering from one of the most common diseases, i.e., diabetes mellitus and the metabolic syndrome preceding it. These patients are problematic for physicians, and for this reason a study of diagnostic and therapeutic management was undertaken on the basis of our own experience as well as examination based on evidence-based medicine. Prior to making therapeutic decisions it is necessary to determine cardiovascular, thromboembolic and breast cancer risk factors. Hormonal therapy may be helpful in young postmenopausal women who are free of risk factors, and its composition and route of administration are significant considerations. Women with risk factors and who are more than 10 years after menopause should be administered alternative therapy depending on the diagnosed pathology.

Is alcohol consumption a risk factor for weight gain and obesity?

Alcohol represents an important source of energy. Despite its comparatively high energy content of 7.1 g/kcal, it is still controversial whether moderate amounts of alcohol represent a risk factor for weight gain and obesity. Epidemiologic data showed a positive, negative, or no relationship between alcohol intake and body weight. Despite the difficulty in assessing alcohol intake as well as controlling for different confounders of the energy-balance equation, the conflicting epidemiologic data can be explained in most instances. Every component of the energy-balance equation is affected by the ingestion of alcohol. Moderate amounts of alcohol enhance energy intake due to the caloric content of the alcohol as well as its appetite-enhancing effects. Alcohol-induced thermogenesis is approximately 20% in healthy nonalcoholic subjects, i.e., moderate alcohol consumers, which is higher than for other energy substrates but considerably lower than in heavy alcohol consumers. This would suggest that a major fraction of the alcohol energy represents a navailable energy source for ATP synthesis in moderate non-daily alcohol consumers. Experimental evidence from several metabolic studies showed a suppression of lipid oxidation by alcohol and thus the enhancement of a positive fat balance. The nonoxidized fat is preferentially deposited in the abdominal area. The experimental metabolic evidence suggests that the consumption of moderate amounts of alcohol has to be accounted for in the energy-balance equation and may represent a risk factor for the development of a positive energy balance and thus weight gain. In the heavy alcohol consumer and eventually also in daily moderate alcohol consumers, a larger fraction of the alcohol energy might not be an available source of energy due to the induction of the microsomal ethanol-oxidizing system (MEOS). Experimental data in combination with epidemiologic findings suggest that alcohol energy counts more in moderate nondaily alcohol consumers than in some moderate daily and all heavy consumers. Accordingly the question is not "Whether alcohol calories do count" but "How much do alcohol calories count?". There seems to be a large individual variability according to the absolute amount of alcohol consumed, the drinking frequency as well as genetic factors. Presently it can be said that alcohol calories count more in moderate nondaily consumers than in daily (heavy) consumers. Further, they count more in combination with a high-fat diet and in overweight and obese subjects.

Visceral fat and beta cell function in non-diabetic humans

AIMS/HYPOTHESIS

Preferential visceral adipose tissue (VAT) accumulation has been clearly associated with insulin resistance. In contrast, the impact of visceral obesity on beta cell function is controversial.

METHODS

In 62 non-diabetic women and men (age 24-69 years, BMI 21-39 kg/m2), we measured VAT and subcutaneous adipose tissue (SAT) fat mass by magnetic resonance imaging. We also measured insulin secretion and beta cell function by C-peptide deconvolution and physiological modelling of data from a frequently sampled, 75-g, 3-h OGTT, respectively.

RESULTS

VAT (range 0.1-3.1 kg) was strongly related to sex, age and BMI; SAT was related to sex and BMI. Controlling for sex, age, BMI and SAT by multivariate analysis, excess VAT was associated with a clinical phenotype comprising higher plasma glucose levels, BP, heart rate and serum transaminases. The corresponding metabolic phenotype consisted of insulin resistance (partial r=-0.38) and hyperinsulinaemia (partial r=0.29). The latter, however, was appropriate for the degree of insulin resistance regardless of obesity and abdominal fat distribution. Moreover, none of the model-derived parameters describing beta cell function (glucose sensitivity, rate sensitivity and potentiation) was independently associated with excess VAT.

CONCLUSIONS/INTERPRETATION

In non-diabetic Caucasian adults of either sex, preferential visceral fat deposition in itself is part of an insulin-resistant phenotype. The insulin secretory response to a physiological challenge is increased to fully compensate for the insulin resistance, but the dynamics of beta cell function (glucose sensitivity, rate sensitivity and potentiation) are largely preserved.

Plasma visfatin concentrations and fat depot-specific mRNA expression in humans

Visceral and subcutaneous adipose tissue display important metabolic differences that underlie the association of visceral obesity with obesity-related cardiovascular and metabolic alterations. Recently, visfatin was identified as an adipokine, which is predominantly secreted from visceral adipose tissue both in humans and mice. In this study, we examined whether visfatin plasma concentrations (using enzyme immunosorbent assay) and mRNA expression (using RT-PCR) in visceral and subcutaneous fat correlates with anthropometric and metabolic parameters in 189 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance. Visfatin plasma concentration correlates positively with the visceral visfatin mRNA expression (r(2) = 0.17, P < 0.0001), BMI (r(2) = 0.062, P = 0.004), percent body fat (r(2) = 0.048, P = 0.01), and negatively with subcutaneous visfatin mRNA expression (r(2) = 0.18, P < 0.0001). However, in a subgroup of 73 individuals, in which visceral fat mass was calculated from computed tomography scans, there was no correlation between plasma visfatin concentrations and visceral fat mass. We found no significant correlation between visfatin plasma concentrations and parameters of insulin sensitivity, including fasting insulin, fasting plasma glucose concentrations, and the glucose infusion rate during the steady state of an euglycemic-hyperinsulinemic clamp independent of percent body fat. Visfatin gene expression was not different between visceral and subcutaneous adipose tissue in the entire study group nor in selected subgroups. We found a significant correlation between visceral visfatin gene expression and BMI (r(2) = 0.06, P = 0.001) and percent body fat (measured using dual-energy X-ray absorptiometry) (r(2) = 0.044, P = 0.004), whereas no significant association between BMI or percent body fat and subcutaneous visfatin mRNA expression existed (both P >0.5). In conclusion, visfatin plasma concentrations and visceral visfatin mRNA expression correlated with measures of obesity but not with visceral fat mass or waist-to-hip ratio. In addition, we did not find differences in visfatin mRNA expression between visceral and subcutaneous adipose tissue in humans.

Perhydroquinolylbenzamides as Novel Inhibitors of 11β-Hydroxysteroid Dehydrogenase Type 1

High-throughput screening identified 5 as a weak inhibitor of 11beta-HSD1. Optimization of the structure led to a series of perhydroquinolylbenzamides, some with low nanomolar inhibitory potency. A tertiary benzamide is required for biological activity and substitution of the terminal benzamide with either electron-donating or -withdrawing groups is tolerated. The majority of the compounds show selectivity of >20 to >700-fold over 11beta-HSD2. Analogues which showed >50% inhibition of 11beta-HSD1 at 1 muM in an cellular assay were screened in an ADX mouse model. A maximal response of >70% reduction of liver corticosterone levels was observed for three compounds; 9m, 25 and 49.

Childhood obesity and type 2 diabetes mellitus

Until recently, the majority of cases of diabetes mellitus among children and adolescents were immune-mediated type 1a diabetes. Obesity has led to a dramatic increase in the incidence of type 2 diabetes (T2DM) among children and adolescents over the past 2 decades. Obesity is strongly associated with insulin resistance, which, when coupled with relative insulin deficiency, leads to the development of overt T2DM. Children and adolescents with T2DM may experience the microvascular and macrovascular complications of this disease at younger ages than individuals who develop diabetes in adulthood, including atherosclerotic cardiovascular disease, stroke, myocardial infarction, and sudden death; renal insufficiency and chronic renal failure; limb-threatening neuropathy and vasculopathy; and retinopathy leading to blindness. Health care professionals are advised to perform the appropriate screening in children at risk for T2DM, diagnose the condition as early as possible, and provide rigorous management of the disease.

Plasma levels of adiponectin, a novel adipocyte-derived hormone, in sleep apnea

OBJECTIVE

Obstructive sleep apnea (OSA) is associated with obesity, sympathetic activation, systemic inflammation, and cardiovascular morbidity. Obesity, beta-adrenergic agonists, and inflammation are linked to decreased expression and/or secretion of an adipose tissue-derived antiatherogenic hormone, adiponectin. The purpose of the study was to investigate whether OSA affected plasma levels of adiponectin, which might help explain OSA-associated cardiovascular morbidity.

RESEARCH METHODS AND PROCEDURES

We randomly selected 68 otherwise healthy male subjects, either with moderate/severe OSA [apnea-hypopnea index (AHI)>or=20; n=35] or without OSA (AHI<or=5; n=33). The diagnosis of OSA was made based on prospective full polysomnography. Adiponectin was measured before polysomnography between 8 and 10 pm.

RESULTS

AHI was higher in the OSA group (49.5+/-4.4 vs. 2.9+/-0.4 events/h; p<0.001). OSA subjects were also more obese, with greater BMI (33+/-1 vs. 30+/-1; p=0.016) and percentage body fat (29+/-1% vs. 26+/-1%; p=0.030). Adiponectin levels were 7.67+/-0.73 and 6.33+/-0.51 microg/mL in the OSA and non-OSA groups, respectively, and this difference was significant in covariate analysis (taking into account age, hemodynamic characteristics, measures of body fat, and OSA severity) (p=0.009). After excluding from both groups the subjects with extreme BMI, such that the OSA and non-OSA study cohorts had similar BMI and percentage body fat, subjects with OSA had significantly higher plasma adiponectin (8.49+/-0.92 vs. 6.32+/-0.55 microg/mL; p=0.042), differences also evident in covariate analysis (p=0.017).

DISCUSSION

Plasma adiponectin levels are elevated in otherwise healthy subjects with OSA. Therefore, low adiponectin is unlikely to explain the association between OSA and cardiovascular disease.

Adipocyte-specific glucocorticoid inactivation protects against diet-induced obesity

Local glucocorticoid (GC) action depends on intracellular GC metabolism by 11beta-hydroxysteroid dehydrogenases (11betaHSDs). 11betaHSD1 activates GCs, while 11betaHSD2 inactivates GCs. Adipocyte-specific amplification of GCs through transgenic overexpression of 11betaHSD1 produces visceral obesity and the metabolic syndrome in mice. To determine whether adipocyte-specific inactivation of GCs protects against this phenotype, we created a transgenic model in which human 11betaHSD2 is expressed under the control of the murine adipocyte fatty acid binding protein (aP2) promoter (aP2-h11betaHSD2). Transgenic mice have increased 11betaHSD2 expression and activity exclusively in adipose tissue, with the highest levels in subcutaneous adipose tissue, while systemic indexes of GC exposure are unchanged. Transgenic mice resist weight gain on high-fat diet due to reduced fat mass accumulation. This improved energy balance is associated with decreased food intake, increased energy expenditure, and improved glucose tolerance and insulin sensitivity. Adipose tissue gene expression in transgenic mice is characterized by decreased expression of leptin and resistin and increased expression of adiponectin, peroxisome proliferator-activated receptor gamma, and uncoupling protein 2. These data suggest that reduction of active GCs exclusively in adipose tissue is an important determinant of a favorable metabolic phenotype with respect to energy homeostasis and the metabolic syndrome.

Role of premature leptin surge in obesity resulting from intrauterine undernutrition

Intrauterine undernutrition is closely associated with obesity related to detrimental metabolic sequelae in adulthood. We report a mouse model in which offspring with fetal undernutrition (UN offspring), when fed a high-fat diet (HFD), develop pronounced weight gain and adiposity. In the neonatal period, UN offspring exhibited a premature onset of neonatal leptin surge compared to offspring with intrauterine normal nutrition (NN offspring). Unexpectedly, premature leptin surge generated in NN offspring by exogenous leptin administration led to accelerated weight gain with an HFD. Both UN offspring and neonatally leptin-treated NN offspring exhibited an impaired response to acute peripheral leptin administration on a regular chow diet (RCD) with impaired leptin transport to the brain as well as an increased density of hypothalamic nerve terminals. The present study suggests that the premature leptin surge alters energy regulation by the hypothalamus and contributes to "developmental origins of health and disease."

Effect of vitamin A content in cafeteria diet on the expression of nuclear receptors in rat subcutaneous adipose tissue

The aim of this study was to determine the effects of cafeteria diet containing control or elevated level of vitamin A on the expression of nuclear receptors in adipose tissue. Male Wistar rats were submitted to 3 experimental diets during 8 weeks, a standard diet and two hyper-energetic, hyperlipidic "cafeteria" diets containing normal (Caf) or higher (Caf+) vitamin A level. During the experiment, body weights and energy intakes were measured. At the end of the experimental period, subcutaneous adipose tissue (Swat) and all the fat mass were removed and weighted. Nuclear receptors mRNA levels of RARalpha, RARgamma, RXRalpha, PPARgamma were measured in the Swat by a real-time semi-quantitative RT-PCR method. We observed that energy intake of Caf+ and Caf groups was significantly higher than that of the control group. Despite a higher increase of the energy intake in the Caf group compared to the Caf+ group, no significant difference was observed in the body weight gain of the Caf+ compared to the Caf group. The Caf+ and Caf diets led to a significant increase of adipose tissue in cafeteria groups as observed in the Swat depot. The mRNA levels of PPARgamma and RXRalpha were significantly increased in the Caf+ group as compared to control group, with a significant positive correlation between these two parameters. Expressions of RARalpha and RARgamma were not modified in experimental groups compared to controls. In conclusion, 8-week exposure to cafeteria diets with normal and higher levels of vitamin A led to an increase of adiposity in rats, associated, only in the group fed with the higher vitamin A level cafeteria diet, with an increase of PPARgamma and RXRalpha expressions in subcutaneous adipose tissue.

Reduction of hepatic and adipose tissue glucocorticoid receptor expression with antisense oligonucleotides improves hyperglycemia and hyperlipidemia in diabetic rodents without causing systemic glucocorticoid antagonism

Glucocorticoids (GCs) increase hepatic gluconeogenesis and play an important role in the regulation of hepatic glucose output. Whereas systemic GC inhibition can alleviate hyperglycemia in rodents and humans, it results in adrenal insufficiency and stimulation of the hypothalamic-pituitary-adrenal axis. In the present study, we used optimized antisense oligonucleotides (ASOs) to cause selective reduction of the glucocorticoid receptor (GCCR) in liver and white adipose tissue (WAT) and evaluated the resultant changes in glucose and lipid metabolism in several rodent models of diabetes. Treatment of ob/ob mice with GCCR ASOs for 4 weeks resulted in approximately 75 and approximately 40% reduction in GCCR mRNA expression in liver and WAT, respectively. This was accompanied by approximately 65% decrease in fed and approximately 30% decrease in fasted glucose levels, a 60% decrease in plasma insulin concentration, and approximately 20 and 35% decrease in plasma resistin and tumor necrosis factor-alpha levels, respectively. Furthermore, GCCR ASO reduced hepatic glucose production and inhibited hepatic gluconeogenesis in liver slices from basal and dexamethasone-treated animals. In db/db mice, a similar reduction in GCCR expression caused approximately 40% decrease in fed and fasted glucose levels and approximately 50% reduction in plasma triglycerides. In ZDF and high-fat diet-fed streptozotocin-treated (HFD-STZ) rats, GCCR ASO treatment caused approximately 60% reduction in GCCR expression in the liver and WAT, which was accompanied by a 40-70% decrease in fasted glucose levels and a robust reduction in plasma triglyceride, cholesterol, and free fatty acids. No change in circulating corticosterone levels was seen in any model after GCCR ASO treatment. To further demonstrate that GCCR ASO does not cause systemic GC antagonism, normal Sprague-Dawley rats were challenged with dexamethasone after treating with GCCR ASO. Dexamethasone increased the expression of GC-responsive genes such as PEPCK in the liver and decreased circulating lymphocytes. GCCR ASO treatment completely inhibited the increase in dexamethasone-induced PEPCK expression in the liver without causing any change in the dexamethasone-induced lymphopenia. These studies demonstrate that tissue-selective GCCR antagonism with ASOs may be a viable therapeutic strategy for the treatment of the metabolic syndrome.