Absence of an effect of liposuction on insulin action and risk factors for coronary heart disease

Adipose tissue heterogeneity: implication of depot differences in adipose tissue for obesity complications

Obesity, defined as excess fat mass, increases risks for multiple metabolic diseases, such as type 2 diabetes, cardiovascular disease and several types of cancer. Over and above fat mass per se, the pattern of fat distribution, android or truncal as compared to gynoid or peripheral, has a profound influence on systemic metabolism and hence risk for metabolic diseases. Increases in upper body adipose tissue (visceral and abdominal subcutaneous) confer an independent risk, while the quantity of gluteofemoral adipose tissue is protective. Variations in the capacity of different depots to store and release fatty acids and to produce adipokines are important determinants of fat distribution and its metabolic consequences. Depot differences in cellular composition and physiology, including innervation and blood flow, likely influence their phenotypic properties. A number of lines of evidence also support the idea that adipocytes from different anatomical depots are intrinsically different as a result of genetic or developmental events. In this chapter, we will review the phenotypic characteristics of different adipose depots and mechanisms that link their depot-specific biology to metabolic complications in men and women.

Metabolic alterations following visceral fat removal and expansion: Beyond anatomic location

Increased visceral adiposity is a risk factor for metabolic disorders such as dyslipidemia, hypertension, insulin resistance and type 2 diabetes, whereas peripheral (subcutaneous) obesity is not. Though the specific mechanisms which contribute to these adipose depot differences are unknown, visceral fat accumulation is proposed to result in metabolic dysregulation because of increased effluent, e.g., fatty acids and/or adipokines/cytokines, to the liver via the hepatic portal vein. Pathological significance of visceral fat accumulation is also attributed to adipose depot/adipocyte-specific characteristics, specifically differences in structural, physiologic and metabolic characteristics compared with subcutaneous fat. Fat manipulations, such as removal or transplantation, have been utilized to identify location dependent or independent factors that play a role in metabolic dysregulation. Obesity-induced alterations in adipose tissue function/intrinsic characteristics, but not mass, appear to be responsible for obesity-induced metabolic dysregulation, thus “quality” is more important than “quantity.” This review summarizes the implications of obesity-induced metabolic dysfunction as it relates to anatomic site and inherent adipocyte characteristics.

Adiposity in children and adolescents: correlates and clinical consequences of fat stored in specific body depots

The 2011 Pennington Biomedical Research Center's Scientific Symposium focused on adiposity in children and adolescents. The symposium was attended by 15 speakers and other invited experts. The specific objectives of the symposium were to (i) integrate the latest published and unpublished findings on the laboratory and clinical assessment of depot-specific adiposity in children and adolescents, (ii) understand the variation in depot-specific adiposity and related health outcomes associated with age, sex, maturation, ethnicity and other factors and (iii) identify opportunities for incorporating new markers of abdominal obesity into clinical practice guidelines for obesity in children and adolescents. This symposium provided an overview of important new advances in the field and identified directions for future research. The long-term goal of the symposium is to aid in the early identification of children and adolescents who are at increased health risk because of obesity and obesity-related conditions.

Obesity: a disease or a biological adaptation? An update

Obesity is characterized by the accumulation of excess body fat and can be conceptualized as the physical manifestation of chronic energy excess. An important challenge of today's world is that our so-called obesogenic environment is conducive to the consumption of energy and unfavourable to the expenditure of energy. The modern, computer-dependent, sleep-deprived, physically inactive humans live chronically stressed in a society of food abundance. From a physiological standpoint, the excess weight gain observed in prone individuals is perceived as a normal consequence to a changed environment rather than a pathological process. In other words, weight gain is a sign of our contemporary way of living or a 'collateral damage' in the physiological struggle against modernity. Additionally, substantial body fat loss can complicate appetite control, decrease energy expenditure to a greater extent than predicted, increase the proneness to hypoglycaemia and its related risk towards depressive symptoms, increase the plasma and tissue levels of persistent organic pollutants that promote hormone disruption and metabolic complications, all of which are adaptations that can increase the risk of weight regain. In contrast, body fat gain generally provides the opposite adaptations, emphasizing that obesity may realistically be perceived as an a priori biological adaptation for most individuals. Accordingly, prevention and treatment strategies for obesity should ideally target the main drivers or root causes of body fat gain in order to be able to improve the health of the population.

C-reactive protein decrease after postbariatric abdominoplasty

In a prospective study, indices of glucose homeostasis, lipid profile, and systemic inflammation were monitored after an aesthetic abdominoplasty, aiming to scrutinize the possible metabolic benefits for abdominal fat removal. Premenopausal females with substantial weight loss (N=40) undergoing circumferential abdominoplasty (index group, n=20) or augmentation mammoplasty with mastopexy (controls, n=20) were recruited. All of them originally underwent Roux-en-Y gastric bypass. Variables included BMI, white blood cell count, C-reactive protein, hemoglobin, total cholesterol and fractions, triglycerides, glucose, and HbA1c. Follow-up reached 20.3 ± 13.6 months for index cases and 29.5 ± 17.4 months for controls. The metabolic and inflammatory indices improved after the bariatric surgery. Subsequent monitoring indicated a stable body weight and biochemical profile in both groups. The exceptions were HDL cholesterol and C-reactive protein, which respectively increased and diminished after the abdominoplasty, consistent with an inflammatory and metabolic advantage for this operation. This is the first long-term study in a weight-stable population to point out such a pattern after abdominoplasty.

Bariatric surgery: an IDF statement for obese Type 2 diabetes

The International Diabetes Federation Taskforce on Epidemiology and Prevention of Diabetes convened a consensus working group of diabetologists, endocrinologists, surgeons and public health experts to review the appropriate role of surgery and other gastrointestinal interventions in the treatment and prevention of Type 2 diabetes. The specific goals were: to develop practical recommendations for clinicians on patient selection; to identify barriers to surgical access and suggest interventions for health policy changes that ensure equitable access to surgery when indicated; and to identify priorities for research. Bariatric surgery can significantly improve glycaemic control in severely obese patients with Type 2 diabetes. It is an effective, safe and cost-effective therapy for obese Type 2 diabetes. Surgery can be considered an appropriate treatment for people with Type 2 diabetes and obesity not achieving recommended treatment targets with medical therapies, especially in the presence of other major co-morbidities. The procedures must be performed within accepted guidelines and require appropriate multidisciplinary assessment for the procedure, comprehensive patient education and ongoing care, as well as safe and standardized surgical procedures. National guidelines for bariatric surgery need to be developed for people with Type 2 diabetes and a BMI of 35 kg/m² or more.

Effects and mechanism of duodenal-jejunal bypass and sleeve gastrectomy on GLUT2 and glucokinase in diabetic Goto-Kakizaki rats

Background

The study investigated the effects and mechanism of duodenal-jejunal bypass (DJB) and sleeve gastrectomy (SG) on the expression of liver GLUT2 and glucokinase (GCK) in diabetic rats.

Methods

Animal models of Goto–Kakizaki (GK) rats were established for the investigation of DJB and SG. Results of weight, food intake, fasting plasma glucose level, oral glucose tolerance test and insulin were compared. Liver tissues were harvested 8 weeks postoperatively. Reverse transcription-PCR and western blot were used to detect liver GLUT2 and GCK mRNA and protein expression after operation.

Results

Fasting plasma glucose levels of DJB group and SG group in GK rats were markedly declined at 3 days and l, 2, 4, 6, and 8 weeks postoperatively (P <0.01), whereas the levels of the sham-operated group only dropped at 3 days and 1 week postoperatively, and there were no significant differences 2 weeks postoperatively (P >0.05). In the liver of GK rats, GLUT2 mRNA level and protein expression after DJB were higher than those in sham-operated group and control group. GLUT2 mRNA level and protein expression after SG were significantly lower than those in control group (P <0.01). GCK mRNA and protein experienced similar expression change.

Conclusions

Both DJB and SG can decrease the plasma glucose levels of GK rats, whereas they have different effects on the expression of liver GLUT2 and GCK.

Little evidence of systemic and adipose tissue inflammation in overweight individuals(†)

Context: The effect of weight loss by diet alone or diet in conjunction with exercise on low-grade inflammation in non-obese (overweight) individuals is not known. Objective: Test the hypothesis that 24 weeks of moderate calorie restriction (CR; 25%) by diet only or with aerobic exercise would reduce markers of systemic inflammation and attenuate inflammation gene expression in subcutaneous adipose tissue. Design: Randomized controlled trial. Setting: Institutional Research Center. Participants: Thirty-five overweight (body mass index: 27.8 ± 0.7 kg/m²) but otherwise healthy participants (16M/19F) completed the study. Intervention: Participants were randomized to either CR (25% reduction in energy intake, n = 12), caloric restriction + exercise (CR + EX: 12.5% reduction in energy intake + 12.5% increase in exercise energy expenditure, n = 12), or control (healthy weight-maintenance diet, n = 11) for 6 months. Main outcome measures: Fasting serum markers of inflammation [leptin, highly sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), adiponectin] and inflammation-related genes [CD68, IL-6, TNF-α, macrophage migration inhibitory factor (MIF), monocyte chemoattractant protein-1 (MCP-1), adiponectin, plasminogen activator inhibitor-1 (PAI-1)] in subcutaneous adipose tissue. Results: CR and CR + EX lost similar amounts of body weight (–10 ± 1%), fat mass (–24 ± 3%), visceral fat (–27 ± 3%), and had increased insulin sensitivity (CR: 40 ± 20%, CR + EX: 66 ± 22%). Leptin was significantly decreased from baseline (p < 0.001) in both groups however TNF-α and IL-6 were not changed. hsCRP was decreased in CR + EX. There was no change in the expression of genes involved in macrophage infiltration (CD68, MIF MCP-1, PAI-1) or inflammation (IL-6, TNF-α, adiponectin) in either CR or CR + EX. Conclusion: A 10% weight loss with a 25% CR diet alone or with exercise did not impact markers of systemic inflammation or the expression of inflammation-related adipose genes in overweight individuals.

Large-volume liposuction and prevention of type 2 diabetes: a preliminary report

This report presents a preliminary study investigating the effects of large-volume liposuction on the parameters that determine type 2 diabetes. The study enrolled 31 patients with a body mass index (BMI) exceeding 30 kg/m(2) over a 1-year period. All the liposuction procedures were performed with the patient under local anesthesia using ketamine/valium sedation. Pre- and postoperative blood pressure, fasting glucose, glycosylated hemoglobin (HbA1C), weight, and BMI were evaluated for 16 of the 30 patients who returned for a follow-up visit 3 to 12 months postoperatively. The average aspirate was 8,455 ml without dermolipectomy and 5,795 ml with dermolipectomy. The data reveal a trend of improvement in blood sugar levels associated with weight loss that helps the patients. The average blood sugar level dropped 18% in our return patients, and the average weight loss was 9.2%. The average drop in BMI was 6.2%, and HbA1C showed a decrease of 2.3%. The patients with the best weight loss had the best reduction in blood sugar level and blood pressure. No transfers to the hospital and no thromboebolism occurred for any of the 31 patients. One dehiscence, two wound infections, and three seromas were reported. The authors hypothesize that large-volume liposuction in their series may have motivated some to diet, which could be explored in a larger series with control groups. Liposuction alone did not improve obesity but helped to motivate some of the patients to lose weight. These patients had the best results.

Markers of inflammation and fat distribution following weight loss in African-American and white women

Changes in markers of inflammation (MOI) and fat distribution with weight loss between African-American (AA) and white (W) women have yet to be characterized. The purpose of this study was to examine potential ethnic differences in MOI and regional fat distribution with weight loss, and identify the associations between these markers and changes in regional fat distribution with weight loss among AA and W women. Subjects were 126 healthy, premenopausal women, BMI 27-30 kg/m(2). They were placed on a weight-loss intervention consisting of diet and/or exercise until a BMI <25 was achieved. Fat distribution was measured with computed tomography, and body composition with dual-energy X-ray absorptiometry. Serum concentrations of tumor necrosis factor-α (TNF-α), soluble TNF receptor-I (sTNFR-I), sTNFR-II, C-reactive protein (CRP), and interleukin-6 (IL-6) were assessed. All MOI and adiposity measures significantly decreased with weight loss. Significant ethnic differences with weight loss were observed for fat mass, body fat, intra-abdominal adipose tissue (IAAT), sTNFR-I, and sTNFR-II. Mixed-model analysis indicated that adjusting for change in IAAT explained ethnic differences in change in TNF-α and the decrease in TNF-α with weight loss, while total fat mass only explained the decrease in sTNFR-I and sTNFR-II with weight loss. In conclusion, all MOI decreased following weight loss among W, whereas only IL-6 and CRP decreased following weight loss in AA. The most distinct phenotypic difference observed was a greater impact of weight loss on TNF-α in W compared to AA, which was directly associated with IAAT in W.

Sleep, sleep-disordered breathing and lipid homeostasis: translational evidence from murine models and children

Impaired sleep, particularly in the context of sleep-disordered breathing (SDB), is associated with a vast array of comorbidities, including obesity. It is well known that the etiology of obesity is both complex and multifactorial. Recent trends have shown that obesity rates have risen at an alarming rate in children, and this has likely contributed to an increased prevalence of SDB in children. Like the 'chicken and the egg' hypothesis, the temporal relationship of obesity and SDB is unclear but it is speculated that these two conditions converge to promote a fundamental disruption to normal lipid homeostasis. In this review, the effect of sleep disruption and SDB on lipid homeostasis in both murine and human models will be critically examined, with the intent of demonstrating that disrupted sleep in children is itself a precursor to obesity via disordered lipid homeostasis.

Association of in vivo β-adrenergic receptor sensitivity with inflammatory markers in healthy subjects

OBJECTIVE

Several stress-related states and conditions that are considered to involve sympathetic overactivation are accompanied by increased circulating levels of inflammatory immune markers. Prolonged sympathetic overactivity involves increased stimulation of the β-adrenergic receptor (β-AR). Although prior research suggests that one mechanism by which sympathetic stimulation may facilitate inflammation is via β-AR activation, little work has focused on the relationship between circulating inflammatory immune markers and β-AR function within the human body (in vivo). We examined whether decreased β-AR sensitivity, an indicator of prolonged β-adrenergic overactivation and a physiological component of chronic stress, is related to elevated levels of inflammatory immune markers.

METHODS

Ninety-three healthy participants aged 19 to 51 years underwent the chronotropic 25 dose isoproterenol test to determine in vivo β-AR function. Circulating levels of C-reactive protein, interleukin 6, and soluble tumor necrosis factor receptor 1 were determined.

RESULTS

β-AR sensitivity was lower in people with higher C-reactive protein concentrations (r = 0.326, p = .003). That relationship remained significant after controlling for sociodemographic and health variables such as age, sex, ethnicity, body mass index, mean arterial blood pressure, heart rate, leisure-time exercise, and smoking status. No significant relationship was found between chronotropic 25 dose and interleukin 6 or soluble tumor necrosis factor receptor 1.

CONCLUSIONS

This study demonstrates a link between in vivo β-adrenergic receptor function and selected circulating inflammatory markers (CRP) in humans. Future studies in specific disease states may be promising.

Physical activity and exercise in the regulation of human adipose tissue physiology

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.

Reductions in cardiovascular risk after bariatric surgery

PURPOSE OF REVIEW

Obesity is commonly associated with multiple conditions imparting adverse cardiovascular risk, including hypertension, dyslipidemia, and insulin resistance or diabetes. In addition, sleep disordered breathing, inflammation, left ventricular hypertrophy, left atrial enlargement, and subclinical left ventricular systolic and diastolic dysfunction may collectively contribute to increased cardiovascular morbidity and mortality. This review will describe improvements in cardiovascular risk factors after bariatric surgery.

RECENT FINDINGS

All of the cardiovascular risk factors listed above are improved or even resolved after bariatric surgery. Cardiac structure and function also have shown consistent improvement after surgically induced weight loss. The amount of improvement in cardiac risk factors is generally proportional to the amount of weight lost. The degree of weight loss varies with different bariatric procedures. On the basis of the improvement in risk profiles, it has been predicted that progression of atherosclerosis could be slowed and the 10-year risk of cardiac events would decline by ~50% in patients undergoing weight loss surgery. In keeping with these predictions, two studies have demonstrated reductions in 10-year total and cardiovascular mortality of approximately 50% in patients who had bariatric surgery.

SUMMARY

These encouraging data support the continued, and perhaps expanded, use of surgical procedures to induce weight loss in severely obese patients.

Metabolic effects of intra-abdominal fat in GHRKO mice

Mice with targeted deletion of the growth hormone receptor (GHRKO mice) are growth hormone (GH) resistant, small, obese, hypoinsulinemic, highly insulin sensitive and remarkably long-lived. To elucidate the unexpected coexistence of adiposity with improved insulin sensitivity and extended longevity, we examined effects of surgical removal of visceral (epididymal and perinephric) fat on metabolic traits related to insulin signaling and longevity. Comparison of results obtained in GHRKO mice and in normal animals from the same strain revealed disparate effects of visceral fat removal (VFR) on insulin and glucose tolerance, adiponectin levels, accumulation of ectopic fat, phosphorylation of insulin signaling intermediates, body temperature, and respiratory quotient (RQ). Overall, VFR produced the expected improvements in insulin sensitivity and reduced body temperature and RQ in normal mice and had opposite effects in GHRKO mice. Some of the examined parameters were altered by VFR in opposite directions in GHRKO and normal mice, and others were affected in only one genotype or exhibited significant genotype × treatment interactions. Functional differences between visceral fat of GHRKO and normal mice were confirmed by measurements of adipokine secretion, lipolysis, and expression of genes related to fat metabolism. We conclude that in the absence of GH signaling, the secretory activity of visceral fat is profoundly altered and unexpectedly promotes enhanced insulin sensitivity. The apparent beneficial effects of visceral fat in GHRKO mice may also explain why reducing adiposity by calorie restriction fails to improve insulin signaling or further extend longevity in these animals.

Plasma amino acid profile is associated with visceral fat accumulation in obese Japanese subjects

What is already known about this subject •  Asians with metabolic complications associated with obesity, a low body mass index and a low waist circumference have a greater proportion of visceral adipose tissue for a given amount of total body fat compared with Europeans. •  Apparent obese humans and obese animal models show an elevation of branched-chain amino acid levels in plasma. •  A multivariate logistic regression model of plasma free amino acids has been used to screen for several types of cancers in clinical settings. What this study adds •  A specific formula incorporating six amino acid values (Ala, Gly, Glu, Trp, Tyr and branched-chain amino acid) was developed for discrimination of subjects with high visceral fat area by multivariate logistic regression analyses. •  The generated amino acid formula was strongly correlated with visceral fat area in both apparent and non-apparent obese subjects. •  Measuring plasma free amino acids can be used to distinguish the non-apparent visceral obesity in clinical settings in Asian populations.

SUMMARY

Metabolic complications associated with obesity are becoming more common among Japanese subjects. However, visceral fat accumulation is not always apparent by measuring body mass index (BMI) or waist circumference in Asian populations because of the physiological characteristics particular to those ethnicities. Excess visceral fat accumulation raises the odds ratio for developing cardiovascular disease. Thus, high-throughput determination of the amount of abdominal adipose tissue is necessary. We hypothesized that accumulating visceral fat alters the peripheral amino acid profile and that a multivariate logistic regression model of plasma free amino acids can distinguish visceral obesity. A total of 1449 Japanese subjects (985 males and 464 females) who had undergone a comprehensive health screening were enrolled in this study. The visceral fat area was determined using computed tomography imaging, and a plasma free amino acid index to identify high visceral fat areas (≥100 cm(2) ) was developed. The sensitivity and specificity values of the generated amino acid index were 80% and 65%, respectively. In particular, the sensitivity of the generated index to identify subjects with non-apparent visceral obesity (BMI < 25 kg m(-2) ; visceral fat area ≥ 100 cm(2) ) was much greater than that of the waist circumference (73% vs. 46%, respectively). This index's high sensitivity and specificity may be the result of specific alterations in the patients' amino acid profiles, which were specifically correlated with the visceral fat areas and not with subcutaneous fat areas. This profile can be used as a predictor of elevated visceral obesity and a risk assessment tool for metabolic complications in Asian populations.

Effects of reduction mammoplasty on metabolic profile and body weight

BACKGROUND

Advanced studies on adipose tissue have established that subcutaneous adipose tissue acts as an endocrine organ to help maintain homeostasis. Based on this information, many plastic surgeons have evaluated the metabolic effects of liposuction because liposuction is the most common surgical procedure in plastic surgery. Liposuction removes a substantial amount of subcutaneous fat from a specific area of the body. Mammoplasty is another procedure that removes a large amount of subcutaneous fat. In this study, the metabolic effects of reduction mammoplasty were evaluated with hemogram, blood glucose, lipid profile, insulin, and insulin resistance tests before and after surgery.

METHODS

The study involved 35 patients who underwent reduction mammoplasty between January 2006 and June 2009. All the patients were evaluated with physical examination and their history, height, and weight were obtained. Venous blood samples were collected before, 4 h after, and 3 months after the surgical procedure to evaluate hemogram, blood glucose, insulin, and lipid profiles. The HOMA scores of the patients were calculated. Inferiorly based dermal pedicle, central pedicle, and free nipple graft techniques were used in the operations and all excision materials were sent for histopathological examination.

RESULTS

The mean age of the patients was 39.6 ± 11.6 years. The mean excision volume was 2249 ± 1001 g. Body mass indexes were not significantly different before and 3 months after the surgery (p > 0.05). Blood glucose, LDL, HDL, triglyceride, total cholesterol, hemoglobin, and hematocrit values before and 4 h after the surgery were also different (p < 0.05). However, comparisons with the 3-month postoperative test results revealed no statistically significant differences (p > 0.05) and comparisons of all the measurements showed that insulin levels and HOMA scores were not significantly different (p > 0.05).

CONCLUSION

The results of the present study showed that reduction mammoplasty operations do not have any positive effects on blood insulin, glucose profile, lipid profile, and body mass index 3 months after the surgery.

Intermittent hypoxia activates temporally coordinated transcriptional programs in visceral adipose tissue

Obstructive sleep apnea (OSA) is a prevalent disorder characterized by intermittent hypoxia (IH) during sleep. OSA is strongly associated with obesity and dysregulation of metabolism-yet the molecular pathways linking the effects of IH on adipocyte biology remain unknown. We hypothesized that exposure to IH would activate distinct, time-dependent transcriptional programs in visceral adipose tissue of mice. We exposed 36 mice to IH or normoxia for up to 13 days. We transcriptionally profiled visceral fat tissue harvested from the animals and performed functional enrichment and network analysis on differentially expressed genes. We identified over 3,000 genes with significant expression patterns during the time course of IH exposure. The most enriched pathways mapped to metabolic processes, mitochondrion, and oxidative stress responses. We confirmed the pathophysiological relevance of these findings by demonstrating that mice exposed to chronic IH developed dyslipidemia and underwent significant lipid and protein oxidation within their visceral adipose depots. We applied gene-gene interaction network analysis to identify critical controllers of IH-induced transcriptional programs in adipocytes-these network hubs represent putative targets to modulate the effects of chronic IH on adipose tissue. Our approach to integrate computational methods with gene expression profiling of visceral fat tissue during IH exposure shows promise in helping unravel the mechanistic links between OSA and adipocyte biology.

Omentectomy added to Roux-en-Y gastric bypass surgery: a randomized, controlled trial

BACKGROUND

Excess visceral adipose tissue predicts for incipient diabetes mellitus and cardiovascular disease. Human data are mixed regarding the benefits of selective visceral adipose tissue reduction. We investigated the effects of omentectomy added to laparoscopic Roux-en-Y gastric bypass on glucose homeostasis and lipids, inflammatory markers, and adipokines 90 days postoperatively in nondiabetic patients at the Legacy Good Samaritan Hospital and Oregon Health and Science University (Portland, OR).

METHODS

A single-blind, randomized study of laparoscopic Roux-en-Y gastric bypass plus omentectomy versus laparoscopic Roux-en-Y gastric bypass alone in 28 subjects (7 men and 21 women). The groups were matched at baseline for gender, age, and body mass index (BMI). The eligibility criteria included age ≥18 years, BMI ≥40 and <50 kg/m(2) without co-morbid conditions or BMI ≥35 and <50 kg/m(2) with co-morbid conditions. The primary outcome measures were changes in the fasting plasma glucose, insulin, and homostatic model assessment of insulin resistance. The secondary measures were BMI and the high-sensitivity C-reactive protein, tumor necrosis factor-α, interleukin, total and high-molecular-weight adiponectin, fibrinogen, and plasminogen activator inhibitor-1 levels.

RESULTS

After surgery, the BMI decreased significantly in both groups and was not different at the follow-up point. Although many outcome parameters improved with weight loss in both groups postoperatively, only the omentectomy group experienced statistically significant decreases in fasting glucose (P < .05), total (P = .004) and very-low-density lipoprotein (P = .001) cholesterol, and an increase in the high-molecular-weight/total adiponectin ratio (P = .013).

CONCLUSIONS

Omentectomy added to laparoscopic Roux-en-Y gastric bypass results in favorable changes in glucose homeostasis, lipid levels, and adipokine profile at 90 days postoperatively. These data support the hypothesis that selective ablation of visceral adipose tissue conveys metabolic benefits in nondiabetic humans.

Systemic inflammatory reaction after silicone breast implant

BACKGROUND

Systemic inflammation after augmentation mammaplasty with modern silicone implants is not currently recognized. In a prospective controlled study, C-reactive protein and other variables were monitored, aiming to test this hypothesis in a young cohort of patients.

METHODS

Females (18-30 years old, BMI = 18.5-30 kg/m(2), N = 52) were consecutively recruited for breast implant (n = 24, Group I) and for abdominal liposuction (n = 28, Group II/Controls). Patients were interviewed at baseline and followed until 6 months after operation. Variables included demographic and clinical information, surgical outcome, inflammatory markers and autoantibodies.

RESULTS

Operations were well tolerated, without surgical or infectious complications. Mean prosthesis size was 258 ± 21 ml (range = 220-280) and mean aspirate of liposuction was 1972 ± 499 ml (range = 1200-3000). Preoperative, 2-month, and 6-month C-reactive protein concentrations for breast implant patients were 1.3 ± 1.2, 4.8 ± 3.0, and 4.3 ± 6.4 mg/l and for liposuction 3.5 ± 2.7, 3.5 ± 2.1, and 2.2 ± 2.2 mg/l, respectively. Change at 2 months was significant (p = 0.001). Autoantibody investigation failed to reveal remarkable aberrations, except for anticardiolipin elevation, which was nearly symmetrical in the two groups.

CONCLUSION

C-reactive protein levels increased after operation and correlated with proinflammatory and procoagulatory indices. A mild increase in anticardiolipin IgM occurred but differences between populations were lacking. Despite excellent cosmetic outcomes and lack of complications, acute phase reaction could signal ongoing immunogenicity of silicone and long-term monitoring is recommended.

Liver attenuation, pericardial adipose tissue, obesity, and insulin resistance: the Multi-Ethnic Study of Atherosclerosis (MESA)

Insulin resistance is linked to general and abdominal obesity, but its relation to hepatic lipid content and pericardial adipose tissue is less clear. The purpose of this study was to examine cross-sectional associations of liver attenuation, pericardial adipose tissue, BMI, and waist circumference with insulin resistance. We measured liver attenuation and pericardial adipose tissue using the existing cardiac computed tomography scans in 5,291 individuals free of clinical cardiovascular disease and diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA) during the study's baseline visit (2000-2002). Low liver attenuation was defined as the lowest quartile and high pericardial adipose tissue as the upper quartile of volume (cm(3)). We used standard clinical definitions for obesity and abdominal obesity. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA(IR)) index. In multivariate linear regression with all adiposity measures in the model simultaneously, all adiposity measures were significantly (P < 0.0001) associated with insulin resistance: regression coefficients (±s.e.) were 0.31 (±0.02) for low liver attenuation, 0.27 (±0.02) for high pericardial adipose tissue, 0.27 (±0.02) for obesity, and 0.32 (±0.02) for abdominal obesity. We found significant differences (P = 0.003) between standardized liver attenuation and insulin resistance by ethnicity: regression coefficients per 1 s.d. increment were 0.10 ± 0.01 for whites, 0.11 ± 0.02 for Chinese, 0.08 ± 0.2 for blacks, and 0.14 ± 0.01 for Hispanics. Liver attenuation and pericardial adipose tissue were associated with insulin resistance, independent of BMI and waist circumference.

Endothelial dysfunction associated with obesity and the effect of weight loss interventions

Endothelial damage is central to the initiation and progression of atherosclerosis, while in addition vascular endothelial cells secrete several anti-atherogenic substances including the potent vasodilator nitric oxide. Increased adhesion molecule expression, in response to pathophysiological stimuli is perhaps the earliest indicator of compromised endothelial integrity. Obesity and adiposity are associated with an increased risk of CVD, influencing disease progression via a number of mechanisms, including enhanced endothelial activation. This review discusses possible mechanisms linking adiposity and more specifically regional fat depots with endothelial function and evaluates studies investigating the effect of weight loss on endothelial function, assessed by biochemical and physiological measurements. Overall, the research to date suggests that visceral adiposity is a stronger predictor of endothelial activation than overall adiposity, possibly mediated via the action of NEFA in circulation. While in general there is a suggestion that weight loss is associated with significant improvements in endothelial function, this is not apparent in all interventions and published literature to date provides less than convincing evidence for the effects of weight loss on endothelial activation.

Bariatric surgery: a cure for diabetes?

PURPOSE OF REVIEW

To review the basic mechanisms of caloric intake reduction of bariatric surgery and its clinical and metabolic outcomes. To describe novel bariatric procedures, their effects on glucose homeostasis and insulin sensitivity and to explain the proposed mechanisms for type 2 diabetes mellitus (T2DM) resolution.

RECENT FINDINGS

The effects of surgically induced weight loss on T2DM have elucidated in part the role of proximal and distal gastrointestinal bypass on insulin sensitivity. A dual mechanism for improvement in glucose homeostasis after bariatric surgery has been proposed that appears to be weight loss independent.

SUMMARY

Bariatric surgery is the most effective therapy for obesity and obesity-related comorbidities today that provide high rates of resolution of T2DM with improvements in insulin resistance and β-cell function. Novel bariatric procedures offer a unique opportunity to understand the pathophysiology of T2DM and to identify potential pharmacologic targets for effective T2DM treatments and a potential cure.

Fat redistribution following suction lipectomy: defense of body fat and patterns of restoration

No randomized studies in humans have examined whether fat returns after removal or where it returns. We undertook a prospective, randomized-controlled trial of suction lipectomy in nonobese women to determine if adipose tissue (AT) is defended and if so, the anatomic pattern of redistribution. Healthy women with disproportionate AT depots (lower abdomen, hips, or thighs) were enrolled. Baseline body composition measurements included dual-energy X-ray absorptiometry (DXA) (a priori primary outcome), abdominal/limb circumferences, subcutaneous skinfold thickness, and magnetic resonance imaging (MRI) (torso/thighs). Participants (n = 32; 36 ± 1 year) were randomized to small-volume liposuction (n = 14, mean BMI: 24 ± 2 kg/m(2)) or control (n=18, mean BMI: 25 ± 2) following baseline. Surgery group participants underwent liposuction within 2-4 weeks. Identical measurements were repeated at 6 weeks, 6 months, and 1 year later. Participants agreed not to make lifestyle changes while enrolled. Between-group differences were adjusted for baseline level of the outcome variable. After 6 weeks, percent body fat (%BF) by DXA was decreased by 2.1% in the lipectomy group and by 0.28% in the control group (adjusted difference (AD): -1.82%; 95% confidence interval (CI): -2.79% to -0.85%; P = 0.0002). This difference was smaller at 6 months, and by 1 year was no longer significant (0.59% (control) vs. -0.41% (lipectomy); AD: -1.00%; CI: -2.65 to 0.64; P = 0.23). AT reaccumulated differently across various sites. After 1 year the thigh region remained reduced (0.77% (control) vs. -1.83% (lipectomy); AD: -2.59%; CI: -3.91 to -1.28; P = 0.0001), but AT reaccumulated in the abdominal region (0.64% (control) vs. 0.42% (lipectomy); AD: -0.22; CI: -2.35 to 1.91; P = 0.84). Following suction lipectomy, BF was restored and redistributed from the thigh to the abdomen.

Bariatric surgery reduces visceral adipose inflammation and improves endothelial function in type 2 diabetic mice

OBJECTIVE

Bariatric surgery is emerging as an effective method to alleviate a multitude of medical conditions associated with morbid obesity and type 2 diabetes. However, little is known about the effects and mechanisms of bariatric surgery on visceral fat inflammation and endothelial dysfunction in type 2 diabetes. We hypothesize that bariatric surgery ameliorates interferon-γ-mediated adipose tissue inflammation/oxidative stress and improves endothelial function in type 2 diabetic mice.

METHODS AND RESULTS

Control mice (m Lepr(db)) and diabetic mice (Lepr(db)) were treated with either sham surgery or improved gastric bypass surgery and then were evaluated at 5, 10, 20, and 30 days to assess postsurgical effects. Surgery reduced body weight, abdominal adiposity, blood glucose level, and food intake in Lepr(db). The surgery-induced decrease in visceral adiposity was accompanied by amelioration of T-lymphocytes and macrophage infiltration, as well as reduction in the expression of interferon-γ and other inflammatory cytokines in the mesenteric adipose tissue (MAT) of Lepr(db) mice. Furthermore, surgery improved endothelium-dependent, but not endothelium-independent, vasorelaxation in small mesenteric arteries (SMA) of Lepr(db) mice. The improvement in endothelial function was largely attenuated by nitric oxide synthase inhibitor (L-NAME) incubation. Interferon-γ treatment increased the mRNA expression of tumor necrosis factor-α in the MAT of control mice and incubation of SMA of control mice with tumor necrosis factor-α caused impairment of endothelial function. Superoxide production in MAT/SMA and nitrotyrosine protein level in SMA were elevated in diabetic mice. Surgery reduced MAT/SMA oxidative stress in Lepr(db) mice.

CONCLUSIONS

The amelioration of adipose tissue inflammation and the improvement of endothelial function may represent important mechanisms that result in cardiovascular benefits after bariatric surgery.

The contribution of vitamin A to autocrine regulation of fat depots

Morbidity and mortality associated with increased white fat accumulation in visceral fat depots have focused attention on the pathways regulating the development of this tissue during embryogenesis, in adulthood, and while under the influence of obesogenic diets. Adipocytes undergo clonal expansion, differentiation (adipogenesis) and maturation through a complex network of transcriptional factors, most of which are expressed at similar levels in visceral and subcutaneous fat. Rigorous research attempts to unfold the pathways regulating expression and activity of adipogenic transcription factors that act in a fat-depot-specific manner. Peroxisome proliferator-activated receptor-γ (PPARγ) is the master regulator of adipogenesis, and is expressed at higher levels in subcutaneous than in visceral depots. PPARγ expression in adipogenesis is mediated by CCAAT/enhancer binding proteins (C/EBPs) and several transcription factors acting in conjunction with C/EBPs, although alternative pathways through zinc-finger protein-423 (ZFP423) transcription factor are sufficient to induce PPARγ expression and adipogenesis. Vitamin A and its metabolites, retinaldehyde and retinoic acid, are transcriptionally-active molecules. Retinoic acid is generated from retinaldehyde in adipose tissue by the aldehyde dehydrogenase-1 family of enzymes (Aldh1). In this review, we discuss the role of Aldh1 enzymes in the generation of retinoic acid during adipogenesis, in the regulation of the transcriptional network of PPARγ in a fat-depot-specific manner, and the important contribution of this autocrine pathway in the development of visceral obesity. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.

Bariatric surgery: an IDF statement for obese Type 2 diabetes

The International Diabetes Federation Taskforce on Epidemiology and Prevention of Diabetes convened a consensus working group of diabetologists, endocrinologists, surgeons and public health experts to review the appropriate role of surgery and other gastrointestinal interventions in the treatment and prevention of Type 2 diabetes. The specific goals were: to develop practical recommendations for clinicians on patient selection; to identify barriers to surgical access and suggest interventions for health policy changes that ensure equitable access to surgery when indicated; and to identify priorities for research. Bariatric surgery can significantly improve glycaemic control in severely obese patients with Type 2 diabetes. It is an effective, safe and cost-effective therapy for obese Type 2 diabetes. Surgery can be considered an appropriate treatment for people with Type 2 diabetes and obesity not achieving recommended treatment targets with medical therapies, especially in the presence of other major co-morbidities. The procedures must be performed within accepted guidelines and require appropriate multidisciplinary assessment for the procedure, comprehensive patient education and ongoing care, as well as safe and standardized surgical procedures. National guidelines for bariatric surgery need to be developed for people with Type 2 diabetes and a BMI of 35 kg/m(2) or more.

Bariatric surgery: an IDF statement for obese Type 2 diabetes

The International Diabetes Federation Taskforce on Epidemiology and Prevention of Diabetes convened a consensus working group of diabetologists, endocrinologists, surgeons and public health experts to review the appropriate role of surgery and other gastrointestinal interventions in the treatment and prevention of Type 2 diabetes. The specific goals were: to develop practical recommendations for clinicians on patient selection; to identify barriers to surgical access and suggest interventions for health policy changes that ensure equitable access to surgery when indicated; and to identify priorities for research. Bariatric surgery can significantly improve glycaemic control in severely obese patients with Type 2 diabetes. It is an effective, safe and cost-effective therapy for obese Type 2 diabetes. Surgery can be considered an appropriate treatment for people with Type 2 diabetes and obesity not achieving recommended treatment targets with medical therapies, especially in the presence of other major co-morbidities. The procedures must be performed within accepted guidelines and require appropriate multidisciplinary assessment for the procedure, comprehensive patient education and ongoing care, as well as safe and standardized surgical procedures. National guidelines for bariatric surgery need to be developed for people with Type 2 diabetes and a BMI of 35 kg/m(2) or more.

Exercise prescription for patients with type 2 diabetes and pre-diabetes: a position statement from Exercise and Sport Science Australia

Type 2 diabetes mellitus (T2DM) and pre-diabetic conditions such as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) are rapidly increasing in prevalence. There is compelling evidence that T2DM is more likely to develop in individuals who are insufficiently active. Exercise training, often in combination with other lifestyle strategies, has beneficial effects on preventing the onset of T2DM and improving glycaemic control in those with pre-diabetes. In addition, exercise training improves cardiovascular risk profile, body composition and cardiorespiratory fitness, all strongly related to better health outcomes. Based on the evidence, it is recommended that patients with T2DM or pre-diabetes accumulate a minimum of 210 min per week of moderate-intensity exercise or 125 min per week of vigorous intensity exercise with no more than two consecutive days without training. Vigorous intensity exercise is more time efficient and may also result in greater benefits in appropriate individuals with consideration of complications and contraindications. It is further recommended that two or more resistance training sessions per week (2-4 sets of 8-10 repetitions) should be included in the total 210 or 125 min of moderate or vigorous exercise, respectively. It is also recommended that, due to the high prevalence and incidence of comorbid conditions in patients with T2DM, exercise training programs should be written and delivered by individuals with appropriate qualifications and experience to recognise and accommodate comorbidities and complications.

The effect of obesity on chronic kidney disease

Overweightness and obesity are associated with many hemodynamic, structural, and histopathologic alterations in the kidney and with metabolic and biochemical changes that predispose to these abnormalities. Consequent to these disorders, these individuals are more likely to develop chronic kidney disease and end-stage renal failure. Overweight and obese people are more prone to develop albuminuria and, for at least some types of kidney disease, a greater amount of albuminuria and more rapid progression of renal failure. These individuals are more likely to develop diabetes mellitus and hypertension. Diabetic nephropathy, hypertensive nephrosclerosis, focal and segmental glomerulosclerosis, renal cell carcinoma, and urate and calcium oxalate urolithiasis are the more common kidney and urological diseases reported in obese people. Preliminary data indicate that many of the clinical and nephropathologic manifestations associated with obesity can be reversed or ameliorated with reductions in body fat induced by dietary energy restriction or surgical procedures that reduce intake and gastrointestinal absorption of calories.

Body composition phenotypes in pathways to obesity and the metabolic syndrome

Dynamic changes in body weight have long been recognized as important indicators of risk for debilitating diseases. While weight loss or impaired growth can lead to muscle wastage, as well as to susceptibility to infections and organ dysfunctions, the development of excess fat predisposes to type 2 diabetes and cardiovascular diseases, with insulin resistance as a central feature of the disease entities of the metabolic syndrome. Although widely used as the phenotypic expression of adiposity in population and gene-search studies, body mass index (BMI), that is, weight/height(2) (H(2)), which was developed as an operational definition for classifying both obesity and malnutrition, has considerable limitations in delineating fat mass (FM) from fat-free mass (FFM), in particular at the individual level. After an examination of these limitations within the constraints of the BMI-FM% relationship, this paper reviews recent advances in concepts about health risks related to body composition phenotypes, which center upon (i) the partitioning of BMI into an FM index (FM/H(2)) and an FFM index (FFM/H(2)), (ii) the partitioning of FFM into organ mass and skeletal muscle mass, (iii) the anatomical partitioning of FM into hazardous fat and protective fat and (iv) the interplay between adipose tissue expandability and ectopic fat deposition within or around organs/tissues that constitute the lean body mass. These concepts about body composition phenotypes and health risks are reviewed in the light of race/ethnic variability in metabolic susceptibility to obesity and the metabolic syndrome.

Mechanisms of vascular complications in prediabetes

Although the state of prediabetes is defined by its role as a diabetes risk factor, it also carries a significant risk of cardiovascular disease, independent of progression to diabetes. Typical diabetic microvascular complications also occur, albeit at low rates, in prediabetes. There is evidence that both glucose-related and glucose-independent mechanisms contribute to these vascular complications. Effective preventive strategies will likely require control of glycemia, as well as other metabolic risk factors. This article reviews some of the proposed mechanisms for the vascular complications of the prediabetic state.

Visceral fat decreased by long-term interdisciplinary lifestyle therapy correlated positively with interleukin-6 and tumor necrosis factor-α and negatively with adiponectin levels in obese adolescents

The purpose of this study was to assess the level of cytokine expression in correlation with visceral and subcutaneous fat in obese adolescents admitted to long-term interdisciplinary weight loss therapy. The study was a longitudinal clinical intervention of interdisciplinary therapy. Adolescents (18, aged 15-19 years) with body mass indexes greater than the 95th percentile were admitted and evaluated at baseline and again after 1 year of interdisciplinary therapy. Visceral and subcutaneous fat was analyzed by ultrasonography. Blood samples were collected to analyze tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and adiponectin concentrations that were measured by enzyme-linked immunosorbent assay. The most important finding in the present investigation is that the long-term interdisciplinary lifestyle therapy decreased visceral fat. Positive correlations between IL-6 levels and visceral fat (r = 0.42, P < .02) and TNF-α levels and visceral fat (r = 0.40, P < .05) were observed. Negative correlations between TNF-α levels and subcutaneous fat (r = -0.46, P < .01) and adiponectin levels and subcutaneous fat (r = -0.43, P < .03) were also observed. In addition, we found a positive correlation between TNF-α levels and the visceral to subcutaneous fat ratio (r = 0.42, P < .02) and a negative correlation between adiponectin level and the visceral to subcutaneous fat ratio (r = -0.69, P < .001). Despite the limitation of sample size, our results indicate that the observed massive weight loss (mainly visceral fat) was highly correlated with a decreased inflammatory state, suggesting that the interdisciplinary therapy was effective in decreasing inflammatory markers.

Serum visfatin is associated with type 2 diabetes mellitus independent of insulin resistance and obesity

OBJECTIVE

The aim of this study was to evaluate the association of serum visfatin, adiponectin and leptin with 2 diabetes mellitus (T2DM) in the context of the role of obesity or insulin resistance, which is not well understood.

METHODS

A total of 76 newly-diagnosed T2DM patients and 76 healthy control subjects, matched for age, body mass index (BMI) and sex ratio, were enrolled. Anthropometric parameters, glycemic and lipid profile, insulin resistance (measured by homeostasis model assessment of insulin resistance index [HOMA-IR]), leptin, adiponectin, and visfatin were assessed.

RESULTS

On the contrary to adiponectin, serum leptin and visfatin levels were higher in T2DM patients compared with controls (10.07 ± 4.5, 15.87 ± 16.4, and 5.49 ± 2.4 vs. 12.22 ± 4.9 μg/ml, 8.5 ± 7.8 ng/ml and 3.58 ± 2.2 ng/ml, respectively, P<0.01). Waist circumference and BMI were correlated with leptin and adiponectin but not with visfatin. Leptin, adiponectin and visfatin all were associated with T2DM following adjusting for obesity measures. After controlling for HOMA-IR, visfatin remained as an independent predictor of T2DM (odds ratio=1.32, P<0.05). In a multiple regression analysis to determine visfatin only triglycerides and fasting glucose remained in the model (P<0.05).

CONCLUSION

Elevation of visfatin in T2DM is independent of obesity and insulin resistance and is mainly determined by fasting glucose and triglycerides.

Weight science: evaluating the evidence for a paradigm shift

Current guidelines recommend that "overweight" and "obese" individuals lose weight through engaging in lifestyle modification involving diet, exercise and other behavior change. This approach reliably induces short term weight loss, but the majority of individuals are unable to maintain weight loss over the long term and do not achieve the putative benefits of improved morbidity and mortality. Concern has arisen that this weight focus is not only ineffective at producing thinner, healthier bodies, but may also have unintended consequences, contributing to food and body preoccupation, repeated cycles of weight loss and regain, distraction from other personal health goals and wider health determinants, reduced self-esteem, eating disorders, other health decrement, and weight stigmatization and discrimination. This concern has drawn increased attention to the ethical implications of recommending treatment that may be ineffective or damaging. A growing trans-disciplinary movement called Health at Every Size (HAES) challenges the value of promoting weight loss and dieting behavior and argues for a shift in focus to weight-neutral outcomes. Randomized controlled clinical trials indicate that a HAES approach is associated with statistically and clinically relevant improvements in physiological measures (e.g., blood pressure, blood lipids), health behaviors (e.g., eating and activity habits, dietary quality), and psychosocial outcomes (such as self-esteem and body image), and that HAES achieves these health outcomes more successfully than weight loss treatment and without the contraindications associated with a weight focus. This paper evaluates the evidence and rationale that justifies shifting the health care paradigm from a conventional weight focus to HAES.

Do obese patients after weight loss become metabolically normal?

OBJECTIVE

To compare the metabolic cardiovascular risk factors of obese patients after weight loss and 4-year weight loss maintenance afterwards against a matched control group of subjects with a stable body weight and without history of weight loss.

METHOD

50 obese non-diabetic subjects in the study group who previously lost 10% or more of their weight and afterwards entered a 4-year weight loss maintenance programme were matched by age, BMI and sex and compared to 50 weight-stable subjects without history of weight loss. The comparison between both groups was done in term of anthropometrical, metabolic and biological characteristics, early atherosclerosis and insulin sensitivity.

RESULTS

Anthropometrical, metabolic and biological characteristics were similar between the weight loss group and the control matched group. However, insulin sensitivity was still significantly lower in the weight loss than in the matched control group (p = 0.02). Intima media thickness (IMT) also was similar in both groups. We found that lower atherosclerosis measured by IMT at the level of the carotid is associated with better insulin sensitivity (p < 0.05). After the 4-year weight loss maintenance programme, insulin sensitivity improved in the post-weight loss group from 7.9 ± 3.2 to 8.4 ± 3.6 mg/kg/min.

CONCLUSION

All cardiometabolic parameters of obese subjects, except for insulin sensitivity, normalised completely after weight loss. The latter was improved by a weight loss maintenance programme if successfully completed.

Strategies for reducing body fat mass: effects of liposuction and exercise on cardiovascular risk factors and adiposity

Liposuction is the most popular aesthetic surgery performed in Brazil and worldwide. Evidence showing that adipose tissue is a metabolically active tissue has led to the suggestion that liposuction could be a viable method for improving metabolic profile through the immediate loss of adipose tissue. However, the immediate liposuction-induced increase in the proportion of visceral to subcutaneous adipose tissue could be detrimental to metabolism, because a high proportion of visceral to subcutaneous adipose tissue is associated with risk factors for cardiovascular disease. The results of studies investigating the effects of liposuction on the metabolic profile are inconsistent, however, with most studies reporting either no change or improvements in one or more cardiovascular risk factors. In addition, animal studies have demonstrated a compensatory growth of intact adipose tissue in response to lipectomy, although studies with humans have reported inconsistent results. Exercise training improves insulin sensitivity, inflammatory balance, lipid oxidation, and adipose tissue distribution; increases or preserves the fat-free mass; and increases total energy expenditure. Thus, liposuction and exercise appear to directly affect metabolism in similar ways, which suggests a possible interaction between these two strategies. To our knowledge, no studies have reported the associated effects of liposuction and exercise in humans. Nonetheless, one could suggest that exercise training associated with liposuction could attenuate or even block the possible compensatory fat deposition in intact depots or regrowth of the fat mass and exert an additive or even a synergistic effect to liposuction on improving insulin sensitivity and the inflammatory balance, resulting in an improvement of cardiovascular risk factors. Consequently, one could suggest that liposuction and exercise appear to be safe and effective strategies for either the treatment of metabolic disorders or aesthetic purposes.

Prdm16 determines the thermogenic program of subcutaneous white adipose tissue in mice

The white adipose organ is composed of both subcutaneous and several intra-abdominal depots. Excess abdominal adiposity is a major risk factor for metabolic disease in rodents and humans, while expansion of subcutaneous fat does not carry the same risks. Brown adipose produces heat as a defense against hypothermia and obesity, and the appearance of brown-like adipocytes within white adipose tissue depots is associated with improved metabolic phenotypes. Thus, understanding the differences in cell biology and function of these different adipose cell types and depots may be critical to the development of new therapies for metabolic disease. Here, we found that Prdm16, a brown adipose determination factor, is selectively expressed in subcutaneous white adipocytes relative to other white fat depots in mice. Transgenic expression of Prdm16 in fat tissue robustly induced the development of brown-like adipocytes in subcutaneous, but not epididymal, adipose depots. Prdm16 transgenic mice displayed increased energy expenditure, limited weight gain, and improved glucose tolerance in response to a high-fat diet. shRNA-mediated depletion of Prdm16 in isolated subcutaneous adipocytes caused a sharp decrease in the expression of thermogenic genes and a reduction in uncoupled cellular respiration. Finally, Prdm16 haploinsufficiency reduced the brown fat phenotype in white adipose tissue stimulated by β-adrenergic agonists. These results demonstrate that Prdm16 is a cell-autonomous determinant of a brown fat-like gene program and thermogenesis in subcutaneous adipose tissues.

The relationship between heat shock protein 72 expression in skeletal muscle and insulin sensitivity is dependent on adiposity

Decreased gene expression of heat shock protein 72 (HSP72) in skeletal muscle is associated with insulin resistance in humans. We aimed to determine whether HSP72 protein expression in insulin-sensitive tissues is related to criterion standard measures of adiposity and insulin resistance in a young healthy human population free of hyperglycemia. Healthy participants (N = 17; age, 30 ± 3 years) underwent measurement of body composition (dual-energy x-ray absorptiometry), a maximum aerobic capacity test (VO(2max)), an oral glucose tolerance test, and a hyperinsulinemic-euglycemic clamp (M) to access insulin sensitivity. Skeletal muscle and subcutaneous adipose tissue biopsies were obtained by percutaneous needle biopsy. HSP72 protein expression in skeletal muscle was inversely related to percentage body fat (r = -0.54, P < .05) and remained significant after adjustment for age and sex (P < .05). Insulin sensitivity was also related to HSP72 protein expression in skeletal muscle (r = 0.52, P < .05); however, this relationship disappeared after adjustment for percentage body fat (P = .2). In adipose tissue, HSP72 protein expression was not related to adiposity or insulin sensitivity. Physical activity and aerobic fitness did not show any association with HSP72 protein expression in either tissue studied. A lower expression of HSP72 protein in human skeletal muscle was associated with increased adiposity and decreased insulin sensitivity in healthy individuals. These findings are consistent with rodent data suggesting that HSP72 stimulates fat oxidation with consequent reduction in fat storage and adiposity.

Fat tissue, aging, and cellular senescence

Fat tissue, frequently the largest organ in humans, is at the nexus of mechanisms involved in longevity and age-related metabolic dysfunction. Fat distribution and function change dramatically throughout life. Obesity is associated with accelerated onset of diseases common in old age, while fat ablation and certain mutations affecting fat increase life span. Fat cells turn over throughout the life span. Fat cell progenitors, preadipocytes, are abundant, closely related to macrophages, and dysdifferentiate in old age, switching into a pro-inflammatory, tissue-remodeling, senescent-like state. Other mesenchymal progenitors also can acquire a pro-inflammatory, adipocyte-like phenotype with aging. We propose a hypothetical model in which cellular stress and preadipocyte overutilization with aging induce cellular senescence, leading to impaired adipogenesis, failure to sequester lipotoxic fatty acids, inflammatory cytokine and chemokine generation, and innate and adaptive immune response activation. These pro-inflammatory processes may amplify each other and have systemic consequences. This model is consistent with recent concepts about cellular senescence as a stress-responsive, adaptive phenotype that develops through multiple stages, including major metabolic and secretory readjustments, which can spread from cell to cell and can occur at any point during life. Senescence could be an alternative cell fate that develops in response to injury or metabolic dysfunction and might occur in nondividing as well as dividing cells. Consistent with this, a senescent-like state can develop in preadipocytes and fat cells from young obese individuals. Senescent, pro-inflammatory cells in fat could have profound clinical consequences because of the large size of the fat organ and its central metabolic role.

Preoperative weight gain might increase risk of gastric bypass surgery

BACKGROUND

Weight loss improves the cardiovascular and metabolic risk associated with obesity. However, insufficient data are available about the health effects of weight gain, separate from the obesity itself. We sought to determine whether the changes in body weight before open gastric bypass surgery (OGB) would have a significant effect on the immediate perioperative hospital course.

METHODS

A retrospective chart review of 100 consecutive patients was performed to examine the effects of co-morbidities and body weight changes in the immediate preoperative period on the hospital length of stay and the rate of admission to the surgical intensive care unit (SICU).

RESULTS

Of our class III obese patients undergoing OGB, 95% had ≥1 co-morbid condition and an overall SICU admission rate of 18%. Compared with the patients with no perioperative SICU admission, the patients admitted to the SICU had a greater degree of insulin resistance (homeostatic model analysis-insulin resistance 10.8 ± 1.3 versus 5.9 ± 0.5, P = .001), greater serum triglyceride levels (225 ± 47 versus 143 ± 8 mg/dL, P = .003), and had gained more weight preoperatively (.52 ± .13 versus .06 ± .06 lb/wk, P = .003). The multivariate analyses showed that preoperative weight gain was a risk factor for a longer length of stay and more SICU admissions lasting ≥3 days, as were a diagnosis of sleep apnea and an elevated serum triglyceride concentration.

CONCLUSION

The results of the present retrospective study suggest that weight gain increases the risk of perioperative SICU admission associated with OGB, independent of the body mass index. Sleep apnea and elevated serum triglyceride levels were also important determinants of perioperative morbidity. In view of the increasing epidemic of obesity and the popularity of bariatric surgical procedures, we propose that additional clinical and metabolic research focusing on the understanding of the complex relationship among obesity, positive energy balance, weight gain, and perioperative morbidity is needed.

Ectopic fat and cardiovascular disease: what is the link?

AIM

of this paper is to review the recent literature on the relationship between ectopic fat accumulation and cardiovascular disease.

DATA SYNTHESIS

Ectopic fat is an important predictor of metabolic (in particular insulin resistance) and cardiovascular disease, carrying more risk than general fat accumulation. Recent studies have shown a link between ectopic fat accumulation, as cardiac (epicardial or intra-myocardial fat) and/or visceral and/or hepatic fat, and development of atherosclerosis, coronary heart disease and hypertension.

CONCLUSIONS

Ectopic fat accumulation is not only a marker of cardiometabolic disease, since through the release of adipocitokines, lipotoxic and glucotoxic agents, participates in the crosstalk with insulin-sensitive organs leading to metabolic, cardiac and vascular dysfunctions.