Etiology of the metabolic syndrome: potential role of insulin resistance, leptin resistance, and other players

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

Association of metabolic syndrome and chronic kidney disease

The prevalence of kidney disease is increasing rapidly worldwide, reflecting rising rates of obesity, diabetes, and associated metabolic syndrome (MetS). Chronic kidney disease and related comorbidities such as obesity, diabetes, and hypertension place a significant financial burden on healthcare systems. Despite the widespread use of RAAS inhibitors, intensive blood pressure and glycemic control, and newer therapeutic options consisting of sodium/glucose cotransporter-2 (SGLT-2) inhibitors or glucagon-like peptide-1 (GLP-1) receptor agonists, a significant risk of progression to end-stage renal disease remains in the high-risk obese and diabetic population. The MetS is a cluster of cardiovascular risk factors that adversely affect the development and progression of chronic kidney failure. According to the criteria of the World Health Organization, it is defined by visceral adiposity, impaired glucose tolerance or insulin resistance, atherogenic dyslipidemia, raised blood pressure, and microalbuminuria with a albumin-to-creatinine ratio ≥30 mg/g. At molecular level MetS is marked by a proinflammatory state and increased oxidative stress leading to various pathophysiological changes causing endothelial dysfunction and a hypercoagulable state. Because the kidney is a highly vascularized organ, it is especially susceptible for those microvascular changes. Therefore, the MetS and its individual components are associated with the premature development, acceleration, and progression of chronic kidney disease. Therefore, it is becoming increasingly important to elucidate the underlying mechanisms of MetS-associated chronic kidney disease in order to develop new strategies for preventing and slowing the progression of renal disease. In this review, we will elucidate (i) the renal structural, hemodynamic, and metabolic changes that occur in obesity and obesity-related kidney injury; (ii) the clinicopathological characteristics of obesity-related kidney injury, primarily focusing on obesity-associated glomerulopathy; (iii) the potential additional factors or predisposing factors that may turn patients more susceptible to renal structural or functional compensatory failure and subsequent injury.

Role of Melatonin in the Onset of Metabolic Syndrome in Women

Metabolic syndrome (MetS) is a constellation of several associated cardiometabolic risk factors that increase the risk of developing type 2 diabetes mellitus (T2DM), cardiovascular diseases, and mortality. The role of hormonal factors in the development of MetS is assumed. In women, an insulin-resistant state that is associated with polycystic ovarian syndrome and increased deposition of intra-abdominal adipose tissue promotes the development of MetS and increases cardiovascular risk. The neuroendocrine hormone melatonin is secreted mainly at night under the regulatory action of the suprachiasmatic nucleus in the hypothalamus. Melatonin secretion is influenced by exogenous factors such as light and seasons and endogenous factors such as age, sex, and body weight. At present, the role of melatonin in metabolic disorders in humans is not fully understood. In this review, we set out to analyze the relationship of melatonin with the main features of MetS in women. Data from experimental and clinical studies on the role of melatonin in glucose metabolism and on the involvement of melatonin in lipid disturbances in MetS are reviewed. The complex influence of melatonin on hypertension is discussed. The changes in melatonin, leptin, and ghrelin and their relation to various metabolic processes and vascular dysfunction are discussed.

Circadian rhythms-related disorders in diurnal fat sand rats under modern lifestyle conditions: A review

Modern lifestyle reduces environmental rhythmicity and may lead to circadian desynchrony. We are exposed to poor day-time lighting indoors and excessive night-time artificial light. We use air-conditioning to reduce ambient temperature cycle, and food is regularly available at all times. These disruptions of daily rhythms may lead to type 2 diabetes mellitus (T2DM), obesity, cardiometabolic diseases (CMD), depression and anxiety, all of which impose major public health and economic burden on societies. Therefore, we need appropriate animal models to gain a better understanding of their etiologic mechanisms, prevention, and management.We argue that the fat sand rat (Psammomys obesus), a diurnal animal model, is most suitable for studying the effects of modern-life conditions. Numerous attributes make it an excellent model to study human health disorders including T2DM, CMD, depression and anxiety. Here we review a comprehensive series of studies we and others conducted, utilizing the fat sand rat to study the underlying interactions between biological rhythms and health. Understanding these interactions will help deciphering the biological basis of these diseases, which often occur concurrently. We found that when kept in the laboratory (compared with natural and semi-wild outdoors conditions where they are diurnal), fat sand rats show low amplitude, nocturnal or arrhythmic activity patterns, dampened daily glucose rhythm, glucose intolerance, obesity and decreased survival rates. Short photoperiod acclimation exacerbates these pathologies and further dampens behavioral and molecular daily rhythms, resulting in CMD, T2DM, obesity, adipocyte dysfunction, cataracts, depression and anxiety. Increasing environmental rhythmicity by morning bright light exposure or by access to running wheels strengthens daily rhythms, and results in higher peak-to-trough difference in activity, better rhythmicity in clock genes expression, lower blood glucose and insulin levels, improved glucose tolerance, lower body and heart weight, and lower anxiety and depression. In summary, we have demonstrated that fat sand rats living under the correspondent of “human modern lifestyle” conditions exhibit dampened behavioral and biological rhythms and develop circadian desynchrony, which leads to what we have named “The Circadian Syndrome”. Environmental manipulations that increase rhythmicity result in improvement or prevention of these pathologies. Similar interventions in human subjects could have the same positive results and further research on this should be undertaken.

Impact of very preterm birth and post-discharge growth on cardiometabolic outcomes at school age: a retrospective cohort study

Background

Adverse metabolic outcomes later in life have been reported among children or young adults who were born as preterm infants. This study was conducted to examine the impact of very preterm/very low birth weight (VP/VLBW) birth and subsequent growth after hospital discharge on cardiometabolic outcomes such as insulin resistance, fasting glucose, and systolic and diastolic blood pressure (BP) among children at 6–8 years of age.

Methods

This retrospective cohort study included children aged 6–8 years and compared those who were born at < 32 weeks of gestation or weighing < 1,500 g at birth (n = 60) with those born at term (n = 110). Body size, fat mass, BP, glucose, insulin, leptin, adiponectin, and lipid profiles were measured. Weight-for-age z-score changes between discharge and early school-age period were also calculated, and factors associated with BP, fasting glucose, and insulin resistance were analyzed.

Results

Children who were born VP/VLBW had significantly lower fat masses, higher systolic BP and diastolic BP, and significantly higher values of fasting glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR), compared to children born at term. VP/VLBW was correlated with HOMA-IR and BPs after adjusting for various factors, including fat mass index and weight-for-age z-score changes. Weight-for-age z-score changes were associated with HOMA-IR, but not with BPs.

Conclusions

Although children aged 6–8 years who were born VP/VLBW showed significantly lower weight and fat mass, they had significantly higher BPs, fasting glucose, HOMA-IR, and leptin levels. The associations of VP/VLBW with cardiometabolic factors were independent of fat mass and weight gain velocity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02851-5.

Effects of dietary n-3 PUFA levels in early life on susceptibility to high-fat-diet-induced metabolic syndrome in adult mice

The maternal nutritional status during pregnancy and lactation was closely related to the growth and development of the fetus and infants, which had a profound impact on the health of the offspring. N-3 polyunsaturated fatty acid (PUFA) had been proved to have beneficial effects on glucolipid metabolism. However, the effects of dietary different n-3 PUFA levels for mother during pregnancy and lactation on susceptibility to high-fat-diet-induced metabolic syndrome for offspring in adulthood are still unclear. The maternal mice were fed with control, n-3 PUFA-deficient or fish oil-contained n-3 PUFA-rich diets during pregnancy and lactation, and the weaned offspring were fed with high-fat or low-fat diet for 13 weeks, then were subjected to oral glucose tolerance tests. The results showed that dietary n-3 PUFA-deficiency in early life could aggravate the high-fat-diet-induced glucolipid metabolism disorders, including glucose intolerance, insulin resistance, obesity, and dyslipidemia, thus increased the susceptibility to metabolic syndrome of adult mice. Notably, nutritional supplementation with n-3 PUFA in early life could significantly alleviate the glucose metabolism disorders by increasing insulin sensitivity, inhibiting gluconeogenesis and promoting glycogenesis. In addition, administration with n-3 PUFA in early life remarkably reduced serum and hepatic lipid profiles by mediating the expression of genes related to lipogenesis and β-oxidation of fatty acids. Dietary n-3 PUFA-deficiency in early life increases the susceptibility to metabolic syndrome of adult offspring, and nutritional supplementation with n-3 PUFA enhances the tolerance to a high-fat diet of adult offspring.

The renin-angiotensin system in COVID-19: Why ACE2 targeting by coronaviruses produces higher mortality in elderly hypertensive patients?

This renin‐angiotensin system (RAS) interpretation is focused on differences in tissue dependence on RAS and on the topological hierarchy that allows mediators to act only on downstream tissues.

Dependence of tissues on RAS: Tested by expectation maximization clustering of the RNA human tissue expression (https://biogps.org/). ACE and vasoconstrictive AT1R clustered with the prorenin receptor. ACE2 and dilatory MAS1 clustered with nine RAS‐related genes, highly expressed in: Liver; Cardiac_Myocytes; Skeletal_Muscle; Uterus; Kidney; Lung; Small_Intestine; Smooth_Muscle.

RAS and stress accumulation: While prorenin is active after binding to its receptor, binding of soluble renin increases its enzymatic activity several times. Increased renin secretion multiplies the overall capacity for producing Ang I, leading to hypertension and increased vascular resistance.

Coronavirus infection and comorbidities: Cardiorespiratory failure during infection is linked to the previously altered RAS role in lungs and myocardium. Reduced vasodilation by ACE2 lead to vasoconstriction and suboptimal tissue perfusion patterns. Also see the video abstract here https://www.youtube.com/watch?v=Jf0Iped-Mws

Effect of waterpipe tobacco smoke exposure on the development of metabolic syndrome in adult male rats

The prevalence of metabolic syndrome is increased worldwide. Tobacco smoking increases the risk of developing metabolic syndrome. Waterpipe tobacco smoking has become a global trend of tobacco consumption and is as common as cigarette smoking. In this study, the effect of waterpipe tobacco smoke (WTS) on the development of metabolic syndrome in rats was evaluated. Adult Wistar rats were exposed for 19 weeks to either fresh air (control) or WTS for 1 hour daily/ 5 days per week (WTS). Central obesity, systolic blood pressure, lipid profile, glucose hemostasis and levels of leptin and adiponectin were evaluated. The WTS exposure increased body weight, abdominal circumference, systolic blood pressure and fasting glucose compared to control animals (P<0.05), consistent with inducing metabolic syndrome. The retroperitoneal fat, lipid profile and levels of insulin, leptin and adiponectin were not affected by WTS exposure (P>0.05). In conclusion, exposure to WTS has detrimental health effects leading to the development of metabolic syndrome in experimental animals.

Effects of Propolis Extract and Propolis-Derived Compounds on Obesity and Diabetes: Knowledge from Cellular and Animal Models

Propolis is a natural product resulting from the mixing of bee secretions with botanical exudates. Since propolis is rich in flavonoids and cinnamic acid derivatives, the application of propolis extracts has been tried in therapies against cancer, inflammation, and metabolic diseases. As metabolic diseases develop relatively slowly in patients, the therapeutic effects of propolis in humans should be evaluated over long periods of time. Moreover, several factors such as medical history, genetic inheritance, and living environment should be taken into consideration in human studies. Animal models, especially mice and rats, have some advantages, as genetic and microbiological variables can be controlled. On the other hand, cellular models allow the investigation of detailed molecular events evoked by propolis and derivative compounds. Taking advantage of animal and cellular models, accumulating evidence suggests that propolis extracts have therapeutic effects on obesity by controlling adipogenesis, adipokine secretion, food intake, and energy expenditure. Studies in animal and cellular models have also indicated that propolis modulates oxidative stress, the accumulation of advanced glycation end products (AGEs), and adipose tissue inflammation, all of which contribute to insulin resistance or defects in insulin secretion. Consequently, propolis treatment may mitigate diabetic complications such as nephropathy, retinopathy, foot ulcers, and non-alcoholic fatty liver disease. This review describes the beneficial effects of propolis on metabolic disorders.

Comparing serum concentration of spexin among patients with metabolic syndrome, healthy overweight/obese, and normal-weight individuals

Background: There are many factors related to etiology of metabolic syndrome (MetS) including obesity. Spexin, a peptide hormone released from adipose tissue, is the most down-regulated gene in obese, compared to non-obese adipose tissue. Hence, it potentially contributes to the progression and development of metabolic diseases. This study was designed to evaluate serum concentration of spexin in patients with MetS compared to weight-matched and normal-weight controls.

Methods: In this case-control study, 153 participants (51 per group) were collected from October 2014 to June 2016. The study groups were all matched for age and sex and included overweight/obese individuals with MetS and 2 control groups without MetS (including weight-matched and normal-weight participants). Body composition and serum concentration of spexin and leptin were measured.

Results: Serum leptin and spexin levels were significantly higher and lower, respectively, in normal-weight compared to overweight/obese groups with/without MetS (p< 0.02). No significant difference was observed in serum leptin and spexin concentrations between the overweight/obese groups with/without MetS (p≥ 0.05). Also, spexin, with cutoff value of 4.6, had 78% sensitivity and 82% specificity for diagnosing overweight/obese from normal-weight participants. Spexin had 78% sensitivity and specificity, with cutoff value of 4.35, in diagnosing MetS participants from normal-weight group.

Conclusion: This study found no correlation between the circulating level of spexin and MetS development. Higher serum concentration of spexin in normal-weight adults compared to the obese participants illustrated the potential role of this novel peptide in obesity.

Linking type 2 diabetes mellitus, cardiac hypertrophy and depression in a diurnal animal model

It was recently suggested that the Metabolic Syndrome should be renamed to "Circadian Syndrome". In this context, we explored the effects of living under standard laboratory conditions, where light is the only cycling variable (relevant to human modern life), in a diurnal mammal, on the relationships between affective-like pathology, type 2 diabetes mellitus (T2DM), and cardiac hypertrophy. After 20 weeks, some of the animals spontaneously developed T2DM, depressive and anxiety-like behavior and cardiac hypertrophy. There were significant correlations between levels of anxiety-like behavior and glucose tolerance, and between heart/total body weight ratio and glucose tolerance. Our data suggest a relationship between the development of T2DM, emotional and cardiac pathology as seen in diurnal humans. Furthermore, our data show a possible relationship between reduced daily cycling cues in the laboratory and what has been regularly termed "Metabolic Syndrome" and recently proposed by us to be renamed to "Circadian Syndrome".

Hypoalbuminemia: Pathogenesis and Clinical Significance

Hypoalbuminemia is associated with inflammation. Despite being addressed repeatedly in the literature, there is still confusion regarding its pathogenesis and clinical significance. Inflammation increases capillary permeability and escape of serum albumin, leading to expansion of interstitial space and increasing the distribution volume of albumin. The half‐life of albumin has been shown to shorten, decreasing total albumin mass. These 2 factors lead to hypoalbuminemia despite increased fractional synthesis rates in plasma. Hypoalbuminemia, therefore, results from and reflects the inflammatory state, which interferes with adequate responses to events like surgery or chemotherapy, and is associated with poor quality of life and reduced longevity. Increasing or decreasing serum albumin levels are adequate indicators, respectively, of improvement or deterioration of the clinical state. In the interstitium, albumin acts as the main extracellular scavenger, antioxidative agent, and as supplier of amino acids for cell and matrix synthesis. Albumin infusion has not been shown to diminish fluid requirements, infection rates, and mortality in the intensive care unit, which may imply that there is no body deficit or that the quality of albumin “from the shelf” is unsuitable to play scavenging and antioxidative roles. Management of hypoalbuminaemia should be based on correcting the causes of ongoing inflammation rather than infusion of albumin. After the age of 30 years, muscle mass and function slowly decrease, but this loss is accelerated by comorbidity and associated with decreasing serum albumin levels. Nutrition support cannot fully prevent, but slows down, this chain of events, especially when combined with physical exercise.

Changes in Plasma Protein Expression Indicative of Early Diet-induced Metabolic Disease in Male Pigs (Sus scrofa)

Recognition of the preclinical stages of metabolic diseases such as diabetes helps to prevent full development of the disease. In our research, we alter the diet composition of pigs to create a model of human metabolic disease. The objective of the current study was to identify plasma proteins and biologic mechanisms that differed in expression between pigs fed a 'cafeteria diet' (considered unhealthy; high in saturated fats) and those fed a 'Mediterranean diet' (considered healthy; high in unsaturated fats). Pigs fed the cafeteria diet showed increased plasma levels of proteins related to LDL ('bad cholesterol'), immune processes, blood clotting, and metal binding. The Mediterranean diet was associated with increased plasma quantities of proteins associated HDL particles ('good cholesterol'), binding of LDL particles, regulation of immune processes, and glycolysis. Pigs fed a cafeteria diet showed molecular signs of diabetes and atherosclerosis-even in the absence of clinical symptoms-which seemed to protect against the development of metabolic disorders. The current results suggest potential biomarkers of the early onset of metabolic syndromes. These biomarkers can help to reveal specific metabolic changes that precede the onset of diabetes, thus enabling the initiation of patient-specific interventions early during pathophysiologic development.

Involvement of the leptin-adiponectin axis in inflammation and oxidative stress in the metabolic syndrome

The aim of the present work was to study whether the leptin-adiponectin axis may have a pathophysiological role in the increased systemic inflammation and oxidative stress observed in patients with the metabolic syndrome (MS). Leptin, adiponectin, and markers of inflammation and oxidative stress were measured in a sample of 140 Caucasian subjects (74 males/66 females), aged 28-82 years, 60 with and 80 without the MS. Total concentrations of adiponectin as well as its multimeric forms HMW, MMW and LMW were significantly lower in individuals with the MS. The ratio adiponectin/leptin, a marker of dysfunctional adipose tissue, was dramatically decreased in the MS group. Systemic oxidative stress, as evidenced by levels of thiobarbituric acid reactive substances (TBARS), as well as markers of inflammation such as serum amyloid A (SAA), C-reactive protein (CRP) and osteopontin were significantly increased in subjects with the MS. Total adiponectin concentrations were negatively correlated with levels of TBARS and CRP levels. Furthermore, the ratio adiponectin/leptin was negatively correlated with SAA concentrations as well as with CRP levels. We concluded that a dysfunctional adipose tissue as suggested by a low adiponectin/leptin ratio may contribute to the increased oxidative stress and inflammation, hallmarks of the MS.

Analysis of the association of leptin and adiponectin concentrations with metabolic syndrome in children: Results from the IDEFICS study

BACKGROUND AND AIMS

Adipokines may play a role in the pathogenesis of the metabolic syndrome (MetS) in children. We aimed to evaluate the association of leptin, adiponectin, and its ratio (L/A ratio) with the metabolic syndrome (MetS) in a subsample of the IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS) cohort.

METHODS AND RESULTS

Leptin, adiponectin and MetS parameters were measured in a subsample of 1253 children (3-9.9 years) participating to the IDEFICS study, grouped as: Non-OW (underweight/normal weight) and OW/Ob (overweight/obese). MetS was defined using the sex- and age-specific cut-offs based on the distribution of MetS components in the IDEFICS cohort. The prevalence of the MetS among OW/Ob was 24.8% and 27.1% in boys and girls respectively, whereas ≤2% among Non-OW. OW/Ob had significantly higher leptin and L/A ratio as compared to Non-OW. Significantly higher leptin was found in OW/Ob with MetS as compared with OW/Ob without MetS. Significantly lower adiponectin was observed only in OW/Ob girls as compared to Non-OW. A 1SD increase in leptin and L/A ratio z-scores or a 1SD decrease in adiponectin z-score were significantly associated with higher risk of MetS. After adjustment for BMI or body fat mass (BFM) the association remained significant only for leptin.

CONCLUSION

We showed that in European children, higher leptin concentration is associated with MetS, even after adjusting for BMI or BFM, confirming an early role of leptin in MetS, while the association of adiponectin with MetS seems be mediated by body fat in this age range.

Effects of a whey protein supplementation on oxidative stress, body composition and glucose metabolism among overweight people affected by diabetes mellitus or impaired fasting glucose: A pilot study

Obesity and diabetes mellitus type 2 (DM2) are characterized by chronic inflammation and oxidative stress [Donath et al. 2013] and this leads to cardiovascular diseases [Hulsmans & Holvoet 2010]. Whey proteins (WP) have antioxidant [Chitapanarux et al. 2009], anti-inflammatory [Sugawara et al. 2012] and hypoglycemic activities [Mignone et al. 2015], while data on weight, body composition [Frestedt et al. 2008; Aldrich et al. 2011] and blood pressure are conflicting [Kawase et al. 2000; Lee et al. 2007]. WP have unpleasant taste and smell [Patel 2015], but a new WP isolate (ProLYOtin®) seems to be more palatable. 40 g/die of ProLYOtin® were supplemented to overweight people (n=31) with impaired fasting glucose/DM2 for 12 weeks. Markers of antioxidant status (total antioxidant status, glutathione peroxidase, glutathione reductase, uric acid), oxidative damage (thiobarbituric acid reactive substances, advanced oxidation protein products, 8-hydroxydeoxyguanosine), inflammation (interleukin-6, high sensitive reactive protein C) and glicemic status (fasting glucose, insulin, glycated hemoglobin), anthropometric data (weight, height, waist circumference), body composition (body cell mass, fat mass), blood pressure, hand grip strength and skin autofluorescence were measured before and at the end of supplementation. Isolate palatability was evaluated. An increase in glutathione peroxidase, a decrease in uric acid and no change in glutathione reductase, total antioxidant status, oxidative damage, inflammation and glucose markers were found. Significant improvements in anthropometric parameters and fat mass were detected. There wasn't any change in blood pressure, skin autofluorescence and physical performance. Two-thirds of subjects judged the supplement positively. ProLYOtin® seems suitable for treatment of OS and overweight.

Genistein treatment improves fracture resistance in obese diabetic mice

BACKGROUND

Obese, type two diabetics are at an increased risk for fracturing their limb bones in comparison to the general population. Phytoestrogens like as the soy isoflavone genistein have been shown to protect against bone loss. In this study, we tested the effects of genistein treatment on femurs of ob/ob mice, a model for obesity and type two diabetes mellitus.

METHODS

Twenty six-week-old female mice were divided into obese (ob/ob) control, obese genistein-treated, lean (ob/+) control, and lean genistein-treated groups (n = 5 each). Treatment with genistein consisted of 600 mg genistein/kg diet. Control mice were given standard rodent chow. At the end of a four-week treatment period, bone histomorphometric and three-point bending properties were compared among groups.

RESULTS

Obese mice had larger bone areas (B.Ar.; P < 0.05) and total areas (Tt.Ar.; P < 0.05), but similar bone volume (B.Ar./Tt.Ar.; P > 0.05) of the proximal femoral epiphysis in comparison to lean mice. Treatment with genistein decreased Tt.Ar. and femur length, and increased ultimate force required to fracture the femur and the maximum deformation to failure (P < 0.05).

CONCLUSIONS

Genistein improves resistance to fracture from bending loads.

Blood Pressure, Serum Glucose, Cholesterol, and Triglycerides in Dogs with Different Body Scores

The objective of this research was to determine the frequency for the occurrence of MS in dogs, using the criteria determined, and to correlate the criteria of dogs that would characterize the MS with different body condition score (BCS). 271 dogs with different body scores were studied, with 101 dogs with BCS 4-5; 101 dogs with BCS 6-7; and 69 dogs with BCS 8-9. Among the dogs studied, 62 (22,87%) had two or more inclusion criteria for MS. Of these, 28 had BCS 6-7, while 34 dogs had BCS 8-9. Therefore, 27,72% of overweight dogs had inclusion criteria for MS and 49,27% of obese ones had two or more inclusion criteria for MS. When only overweight and obese dogs were considered as a total population, it was observed that 36,47% got inclusion criteria for the MS. No dog with BCS 4-5 showed two or more inclusion criteria for MS. The metabolic syndrome, according to the parameters for inclusion defined in the literature, was observed in 22,87% of the animals studied and in 36% of dogs overweight or obese. Furthermore, MS was most common in obese (49%) compared to overweight dogs (27%).

Metabolic Syndrome Patients Have Lower Levels of Adropin When Compared With Healthy Overweight/Obese and Lean Subjects

Metabolic syndrome (MetS), a cluster of cardiometabolic risk factors, is a challenging public health issue. The aim of current study was to test the hypothesis that concentrations of plasma adropin and leptin differ between patients with MetS and comparable age- and sex-matched control groups. This case-control study involved 153 subjects (51 per group). The study group included obese subjects with MetS and the two control groups included weight-matched subjects without MetS ("healthy": obese) and normal weight subjects without MetS. Body composition parameters were measured using bioelectrical impedance analysis. Plasma levels of adropin, leptin, and their ratio were measured. Leptin was significantly different between obese patients with/without MetS groups and normal weight subjects. Patients with MetS had higher levels of leptin (14 ± 12.4) compared with those without MetS (11.2 ± 9.3 vs. 7 ± 7.1 obese and normal weight without MetS, respectively; p = .002). Compared with healthy obese and normal weight subjects, MetS subjects had lower levels of plasma adropin ( p < .001) and a lower plasma adropin to leptin ratio ( p < .001), which remained significant when adjusted for body fat mass by analysis of covariance ( p < .001). This study demonstrates low levels of adropin are correlated with MetS and hence identify it as a potentially protective agent against MetS development. Variation in adropin levels may partly explain the "healthy obese" phenomenon.

Genistein treatment increases bone mass in obese, hyperglycemic mice

BACKGROUND

Obesity and type 2 diabetes mellitus are associated with elevated risk of limb bone fracture. Incidences of these conditions are on the rise worldwide. Genistein, a phytoestrogen, has been shown by several studies to demonstrate bone-protective properties and may improve bone health in obese type 2 diabetics.

METHODS

In this study, we test the effects of genistein treatment on limb bone and growth plate cartilage histomorphometry in obese, hyperglycemic ob/ob mice. Six-week-old ob/ob mice were divided into control and genistein-treated groups. Genistein-treated mice were fed a diet containing 600 mg genistein/kg for a period of 4 weeks. Cross-sectional geometric and histomorphometric analyses were conducted on tibias.

RESULTS

Genistein-treated mice remained obese and hyperglycemic. However, histomorphometric comparisons show that genistein-treated mice have greater tibial midshaft diameters and ratios of cortical bone to total tissue area than the controls. Genistein-treated mice also exhibit decreased growth plate thickness of the proximal tibia.

CONCLUSION

Our results indicate that genistein treatment affects bone of the tibial midshaft in the ob/ob mouse, independent of improvements in the hyperglycemic state and body weight.

Adiponectin: A biomarker for chronic hepatitis C?

Adiponectin, a hormone primarily synthesized and secreted by adipose tissue, plays a pivotal role in lipid metabolism. Chronic hepatitis C (CHC) infection is characterized by disordered lipid metabolism, which may potentially evolve into steatosis over a period of time. A growing body of evidence appears to link decreased adiponectin plasma levels with severe CHC-related steatosis, which suggests a potential role of this adipokine as a diagnostic and therapeutic target for clinical application. In this review, we have attempted to summarize the current status of adiponectin research in the context of CHC, concentrating predominantly on its roles in CHC, and its potential relevance as a biomarker for CHC.

Multifaceted roles of adiponectin in rheumatoid arthritis

Adiponectin is a circulating hormone with pleiotropic functions in lipid and glucose metabolism secreted by adipocytes. It plays a beneficial role in cardiovascular functions and metabolic complications. Recently, growing researches have elucidated that increased adiponectin plasma levels correlate with severity of rheumatoid arthritis (RA) and it is speculative that adiponectin may link to RA. The association of adiponectin with potential inflammatory functions in RA has raised significant interests in exploring this adipokine as a target for RA-diagnostic and therapeutic applications. Despite significant advances in understanding adiponectin functions and signaling mechanisms, its roles in RA remain multifaceted and subject to controversy. This review highlights the evidences linking adiponectin to either anti-inflammatory or pro-inflammatory action in RA. The results of this review may provide important insight into adiponectin in the development of RA.

THYROID FUNCTION AND METABOLIC SYNDROME: A CROSS-SECTIONAL STUDY IN OBESE AND OVERWEIGHT PATIENTS

OBJECTIVE

Metabolic syndrome (MetS) is associated with increased risks of developing cardiovascular disease and type 2 diabetes. Thyroid dysfunction is also a known cardiovascular risk factor. In obese patients, serum thyroid-stimulating hormone (TSH) levels tend to be higher than in lean controls. The objective of this study was to assess potential associations between serum TSH levels and MetS as well as individual components of MetS.

METHODS

This was a cross-sectional observational study of obese and overweight patients seen for initial evaluation at the Boston Medical Center weight-management clinic between February 1, 2013 and February 1, 2014. Demographic, anthropometric, and laboratory data including serum TSH, insulin, glucose, hemoglobin A1c, and lipid levels were obtained from electronic medical records. Associations between serum TSH levels and presence of MetS and its components were assessed.

RESULTS

A total of 3,447 patients, 75.6% female and 38% African American, without known thyroid dysfunction, were included. Mean ± SD age was 46.74 ± 15.11 years, and mean ± SD body mass index was 36.06 ± 9.89 kg/m(2). Among 1,005 patients without missing data, the prevalence of MetS was 71.84%. In patients with MetS, the median serum TSH was 1.41 μIU/mL, compared with 1.36 μIU/mL in patients without MetS (P = .45). In multivariate models, there was no significant association between serum TSH levels and the presence of MetS, adjusting for age, sex, race, education, socioeconomic status, and smoking. There were also no significant associations between serum TSH and individual components of the MetS.

CONCLUSION

Serum TSH level does not appear to be a potentially modifiable risk factor for MetS in obese and overweight individuals.

Role of C reactive protein (CRP) in leptin resistance

Increased plasma levels of both leptin and C reactive protein (CRP) have been reported in a number of conditions, including obesity, and have been linked to cardiovascular pathophysiological processes and increased cardiovascular risk; interestingly these two biomarkers appear to be able to reciprocally regulate their bioavailability, through complex mechanisms that have not been completely clarified yet. Here we first review clinical evidence suggesting not only that the circulatory levels of CRP and leptin show an independent correlation, but also that assessing them in tandem may result in an increased ability to predict cardiovascular disease. We summarize also molecular studies showing that leptin is able to promote CRP production from hepatocytes and endothelial cells in vitro and discuss the studies addressing the possibility that in vivo leptin administration may be able to modulate plasma CRP levels. Furthermore, we describe two studies demonstrating that CRP directly binds leptin in extra-cellular settings, thus impairing its biological actions. Finally we report genetic evidence that common variations at the leptin receptor locus are associated with CRP blood levels. Overall, the data reviewed here show that the chronic elevation of CRP observed in obese subjects may worsen leptin resistance, contributing to the pathogenesis of cardiovascular disease, and highlight a potential link between conditions, such as leptin resistance and endothelial dysfunction, that may be amenable of pharmacological treatment targeted to the disruption of leptin-CRP interaction.

High-fat diet consumption disrupts memory and primes elevations in hippocampal IL-1β, an effect that can be prevented with dietary reversal or IL-1 receptor antagonism

High-fat diet (HFD)-induced obesity is reaching worldwide proportions. In addition to causing obesity, HFDs also induce a variety of health disorders, which includes cognitive decline. Hippocampal function may be particularly vulnerable to the negative consequences of HFD, and it is suspected that 'primed' neuroinflammatory processes may mediate this response. To examine the link between diet, hippocampal function and neuroinflammation, male Wistar rats were fed a medium or HFD. Hippocampal memory function was measured using contextual pre-exposure fear conditioning (CPE-FC). Rats fed a HFD demonstrated impaired memory, an effect that was augmented with longer duration of HFD consumption. HFD-induced memory impairments were linked to potentiated levels of interleukin-1 beta (IL-1β) protein in the hippocampus 2h after the foot-shock that occurs during CPE-FC. Central IL-1 receptor antagonism, with intracisterna magna (ICM) administration of hIL-1RA prior to the foot-shock prevented the diet-induced memory disruption, suggesting a critical role for IL-1β in this phenomenon. Additionally, obese animals whose diet regimen was reversed from HFD back to standard chow recovered memory function and did not demonstrate a foot-shock-induced hippocampal IL-1β increase. Interestingly, dietary reversal neutralized the negative impact of HFD on memory and IL-1β, yet animals maintained physiological evidence of obesity (increased body mass and serum leptin), indicating that dietary components, not body mass, may mediate the negative effects on memory.

Periodontitis and type II diabetes: a two-way relationship

For many years an association between diabetes and periodontitis has been suspected. In more recent times this relationship has been suggested to be bidirectional with each condition being able to influence the other. In this review the two-way relationship between diabetes and periodontitis is considered. For this narrative review a very broad search strategy of the literature was developed using both EMBASE and MEDLINE (via PubMed) databases. The reference lists from the selected papers were also scanned, and this provided an additional source of papers for inclusion and further assessment. The data available suggest that diabetes is a risk as well as a modifying factor for periodontitis. Individuals with diabetes are more likely to have periodontitis and with increased severity when diabetes is uncontrolled/poorly controlled. Possible mechanisms of how diabetes affects periodontitis include adipokine-mediated inflammation, neutrophil dysfunction, uncoupling of bone and advanced glycation end-products-receptor for advanced glycation end-products interaction. Evidence is accruing to support how periodontitis can affect diabetes and complications associated with diabetes. There is some evidence demonstrating that periodontal therapy can result in a moderate improvement in glycaemic control. Available evidence indicates that diabetes and peridontitis are intricately interrelated and that each condition has the capacity to influence clinical features of each other.

Clustering of metabolic and cardiovascular risk factors in the polycystic ovary syndrome: a principal component analysis

CONTEXT

Polycystic ovary syndrome (PCOS) is a prevalent condition with heterogeneity of clinical features and cardiovascular risk factors that implies multiple aetiological factors and possible outcomes.

OBJECTIVE

To reduce a set of correlated variables to a smaller number of uncorrelated and interpretable factors that may delineate subgroups within PCOS or suggest pathogenetic mechanisms.

MATERIALS AND METHODS

We used principal component analysis (PCA) to examine the endocrine and cardiometabolic variables associated with PCOS defined by the National Institutes of Health (NIH) criteria. Data were retrieved from the database of a single clinical endocrinologist. We included women with PCOS (N = 378) who were not taking the oral contraceptive pill or other sex hormones, lipid lowering medication, metformin or other medication that could influence the variables of interest. PCA was performed retaining those factors with eigenvalues of at least 1.0. Varimax rotation was used to produce interpretable factors.

RESULTS

We identified three principal components. In component 1, the dominant variables were homeostatic model assessment (HOMA) index, body mass index (BMI), high density lipoprotein (HDL) cholesterol and sex hormone binding globulin (SHBG); in component 2, systolic blood pressure, low density lipoprotein (LDL) cholesterol and triglycerides; in component 3, total testosterone and LH/FSH ratio. These components explained 37%, 13% and 11% of the variance in the PCOS cohort respectively.

CONCLUSIONS

Multiple correlated variables from patients with PCOS can be reduced to three uncorrelated components characterised by insulin resistance, dyslipidaemia/hypertension or hyperandrogenaemia. Clustering of risk factors is consistent with different pathogenetic pathways within PCOS and/or differing cardiometabolic outcomes.

Inflammation's Association with Metabolic Profiles before and after a Twelve-Week Clinical Trial in Drug-Naïve Patients with Bipolar II Disorder

Inflammation is thought to be involved in the pathophysiology of bipolar disorder (BP) and metabolic syndrome. Prior studies evaluated the association between metabolic profiles and cytokines only during certain mood states instead of their changes during treatment. We enrolled drug-naïve patients with BP-II and investigated the correlation between changes in mood symptoms and metabolic indices with changes in plasma cytokine levels after 12 weeks of pharmacological treatment. Drug-naïve patients (n = 117) diagnosed with BP-II according to DSM-IV criteria were recruited. Metabolic profiles (cholesterol, triglyceride, HbA1C, fasting serum glucose, body mass index (BMI) and plasma cytokines (TNF-α, CRP, IL-6, and TGF-β) were measured at baseline and 2, 8, and 12 weeks post-treatment. To adjust within-subject dependence over repeated assessments, multiple linear regressions with generalized estimating equation methods were used. Seventy-six (65.0%) patients completed the intervention. Changes in plasma CRP were significantly associated with changes in BMI (P = 1.7E-7) and triglyceride (P = 0.005) levels. Changes in plasma TGF-β1 were significantly associated with changes in BMI (P = 8.2E-6), cholesterol (P = 0.004), and triglyceride (P = 0.006) levels. However, changes in plasma TNF-α and IL-6 were not associated with changes in any of the metabolic indices. Changes in Hamilton Depression Rating Scale scores were significantly associated with changes in IL-6 (P = 0.003) levels; changes in Young Mania Rating Scale scores were significantly associated with changes in CRP (P = 0.006) and TNF-α (P = 0.039) levels. Plasma CRP and TGF-β1 levels were positively correlated with several metabolic indices in BP-II after 12 weeks of pharmacological intervention. We also hypothesize that clinical symptoms are correlated with certain cytokines. These new findings might be important evidence that inflammation is the pathophysiology of clinical symptoms and metabolic disturbance in BP-II.

Trial Registration

ClinicalTrials.gov NCT01188148.

Alterations in gut hormones after laparoscopic sleeve gastrectomy: a prospective clinical and laboratory investigational study

OBJECTIVE

To evaluate the effect of laparoscopic sleeve gastrectomy (LSG) on fasting and meal-stimulated release of the gut hormones ghrelin, pancreatic polypeptide (PP), peptide-YY (PYY), glucagon-like peptide-1 (GLP-1), and amylin and of the adipocytokine leptin.

BACKGROUND

Mounting evidence suggests that the mechanisms of weight loss and the improvement in glucose metabolism seen after LSG are related not only to gastric restriction but also to neurohormonal changes.

METHODS

: Fasting and postprandial levels at 60 and 120 minutes after a standard test meal of the above peptides and glucose metabolism indices were evaluated in 15 consecutive morbidly obese (MO) subjects before and 6 and 12 months after LSG. As study controls, 15 lean subjects matched for age and sex were also assessed.

RESULTS

Body mass index values notably decreased at 6 and 12 months (P < 0.01), postoperatively. In addition, an overall improvement of the glycemic profile of MO patients was noted. After LSG, markedly decreased fasting and postprandial levels of ghrelin, amylin, and leptin were observed. A significant postprandial increase of PYY and GLP-1 levels was also noted postoperatively. Interestingly, significantly increased levels of PP were noted only at 60 minutes postprandially after LSG.

CONCLUSIONS

LSG markedly improved glucose homeostasis and generated significant changes in ghrelin, PP, PYY, GLP-1, amylin, and leptin levels. These multiple hormonal actions may have several beneficial effects on the underlying mechanism of weight loss, demonstrating that LSG could be more than just a restrictive bariatric operation.

Rheumatoid arthritis impacts on the independent relationships between circulating adiponectin concentrations and cardiovascular metabolic risk

Adiponectin and leptin are likely involved in the pathophysiology of rheumatoid arthritis (RA) and therefore potential new therapeutic targets. Adiponectin inhibition could be expected to enhance cardiovascular metabolic risk. However, it is unknown whether RA changes the influence of adipokines on cardiovascular metabolic risk. We determined whether RA impacts on the independent relationships of circulating leptin and adiponectin concentrations with cardiovascular risk factors and carotid intima-media thickness (cIMT) in 277 black African subjects from a developing population; 119 had RA. RA impacted on the relationships of adiponectin concentrations with lipid concentrations and blood pressure, independent of confounders including adiposity (interaction P < 0.05). This translated into an association of adiponectin concentrations with more favorable lipid variables including HDL cholesterol (P = 0.0005), non-HDL cholesterol (P = 0.007), and triglyceride (P = 0.005) concentrations, total cholesterol-HDL cholesterol (P = 0.0002) and triglycerides-HDL cholesterol (P = 0.0003) ratios, and higher systolic (P = 0.0006), diastolic (P = 0.0004), and mean blood pressure (P = 0.0007) in RA but not non-RA subjects. Leptin was not associated with metabolic risk after adjustment for adiposity. The cIMT did not differ by RA status, and adipokine concentrations were unrelated to atherosclerosis. This study suggests that leptin and adiponectin inhibition may not alter overall cardiovascular risk and disease in RA.

Relationship of fasting total homocysteine, high sensitivity C-reactive protein and features of the metabolic syndrome in Trinidadian subjects

OBJECTIVES

To assess the relationship of homocysteine, hs-CRP, with known cardiovascular risk factors of the metabolic syndrome.

METHOD

Cross sectional study comprised 182 diabetic outpatients (70 males and 112 females), attending endocrinology clinics in Trinidad.

RESULTS

Both male and females showed significant linear relationships between high sensitive C-reactive protein (hs-CRP), blood pressure and diabetes (r = -0.2 < R or R > 0.2). In females hs-CRP showed significant linear relationship with HDL, triglyceride, blood pressure and diabetes mellitus (p < 0.0001). The inverse relationship of hs-CRP with HDL implies the strong association of hs-CRP with metabolic syndrome. The multivariate logistic regression analysis showed significant relation of hs-CRP, metabolic syndrome and diabetes mellitus. There was no significant relationship of tHCY to any of the features studied.

CONCLUSION

Serum C-reactive protein is significantly related to features of the metabolic syndrome. Total plasma homocysteine, appears to be independent of both hs-CRP and features of the metabolic syndrome.

Vaspin Serum Concentration in Patients with Type 2 Diabetes and Carotid Plaque

Objective:

To examine whether there is an association between the serum concentration of vaspin and the presence of carotid plaque in early stage type 2 diabetes mellitus (T2DM).

Methods:

Patients ( n = 61) with T2DM within 3 years of diagnosis were divided into those with and those without carotid plaque. Fasting serum vaspin levels, measured by enzymelinked immunosorbent assay, and blood pressure were compared between these two groups and also with an age-matched, apparently healthy control group ( n = 26).

Results:

Fasting serum vaspin concentrations were significantly higher in patients with T2DM without carotid plaque than in controls, but significantly lower in T2DM patients with carotid plaque than inthose without. Multivariate logistic regression analysis showed a significant positive association between the presence of carotid plaque and systolic blood pressure and a significant inverse association between the presence of carotid plaque and fasting serum vaspin concentration.

Conclusion:

A significant inverse association was found, in patients with T2DM within 3 years of diagnosis, between serum vaspin concentration and the presence of carotid plaque.

Smoking and adipose tissue inflammation suppress leptin expression in Japanese obese males: potential mechanism of resistance to weight loss among Japanese obese smokers

BACKGROUND

The effect of smoking on leptin regulation is controversial. Smoking may induce low-grade inflammation. Recent series of studies indicated the critical role of macrophage migration in the establishment of adipose tissue inflammation. In this study, we aimed to see the effects of smoking and inflammation on leptin regulation both at cellular and epidemiological levels.

METHODS

We compared the concentration of inflammatory markers and serum leptin levels among Japanese male subjects. Additionally, leptin and intercellular adhesion molecule (ICAM) -1 gene expression was assessed in adipocytes co-cultured with or without macrophages in the presence or absence of nicotine and/or lipopolysaccharide (LPS).

RESULTS

In subjects with BMI below 25 kg/m2, both WBC counts and soluble-ICAM-1 levels are significantly higher in smokers than in non-smokers. However, leptin concentration did not differ according to smoking status. However, in subjects with BMI over 25 kg/m2, smokers exhibited significantly lower serum leptin level as well as higher WBC counts and s-ICAM-1 concentration as compared with non-smokers. Leptin gene expression was markedly suppressed in adipocytes co-cultured with macrophages than in adipocyte culture alone. Furthermore, nicotine further suppressed leptin gene expression. ICAM-1 gene expression was markedly up-regulated in adipocytes co-cultured with macrophages when stimulated with LPS.

CONCLUSIONS

Adipose tissue inflammation appears to down-regulate leptin expression in adipose tissues. Nicotine further suppresses leptin expression. Thus, both smoking and inflammation may diminish leptin effect in obese subjects. Therefore, obese, but not normal weight, smokers might be more resistant to weight loss than non-smokers.

Role of adipokines and other inflammatory mediators in gestational diabetes mellitus and previous gestational diabetes mellitus

Previous Gestational Diabetes Mellitus (pGDM) is a common condition and has been associated with future development of Type 2 Diabetes Mellitus (T2DM) and Metabolic Syndrome (MS) in women affected. The pathogenesis and risk factors implicated in the development of these conditions later in the lives of women with pGDM are not as yet fully understood. Research has recently focused on a group of substances produced mainly by adipose tissue called adipokines, this group including, among others, adiponectin, leptin, Retinol-Binding Protein-4 (RBP-4), and resistin. These substances as well as other inflammatory mediators (CRP, IL-6, PAI-1, TNF-α) seem to play an important role in glucose tolerance and insulin sensitivity dysregulation in women with pGDM. We summarize the data available on the role of these molecules.

Changes in metabolic profile and adipoinsular axis in morbidly obese premenopausal females treated with restrictive bariatric surgery

BACKGROUND

The aim of the present study was to evaluate the effects of surgically induced weight loss on the metabolic profile and adipocytokine levels in premenopausal morbidly obese females.

METHODS

Twenty premenopausal morbidly obese (MO) women with a median age of 34 years (range: 24-48 years) and a median body mass index (BMI) of 41.47 kg/m(2) (range: 38.0-56.73 kg/m(2)) were studied (13 women underwent gastric banding and 7 women underwent sleeve gastrectomy). In addition, 20 lean premenopausal women with a median age of 32 years (range: 22-44 years) and a median BMI of 20.0 kg/m(2) (range: 18.5-24.7 kg/m(2)) were also studied. Anthropometric measurements and metabolic parameters were analyzed in each patient, along with changes in leptin, adiponectin, resistin, and interleukin-6 (IL-6) before surgery, 6 months after surgery, and 12 months after surgery. Comparisons with the reference normal-weight subjects were also performed.

RESULTS

Both weight and BMI were found to be significantly decreased postoperatively. A 54.5% loss of excess BMI was observed 12 months after surgery, and was associated with significant improvement in all anthropometric and metabolic parameters. Twelve months after surgery we also observed decreased levels of serum leptin, resistin, and IL-6; increased levels of serum adiponectin; and a remarkable improvement in metabolic syndrome markers. Furthermore, postoperative serum resistin and IL-6 levels were found to reach those of normal-weight volunteers.

CONCLUSIONS

The results of this study suggest that weight loss through restrictive bariatric surgery results in a significant reduction in leptin, resistin, and IL-6 levels, and an increase in adiponectin levels, in addition to improving insulin sensitivity and glucose and lipid homeostasis in young morbidly obese female patients. These changes were significantly correlated with the magnitude of weight loss.

A spectrum of dynamic insulin sensitivity test protocols

BACKGROUND

Numerous tests have been developed to estimate insulin sensitivity (SI). However, most of the established tests are either too expensive for widespread application or do not yield reliable results. The dynamic insulin sensitivity and secretion test (DISST) uses assays of glucose, insulin, and C-peptide from nine samples to quantify SI and endogenous insulin secretion (UN) at a comparatively low cost. The quick dynamic insulin sensitivity test has shown that the DISST SI values are robust to significant assay omissions.

METHODS

Eight DISST-based variations of the nine-sample assay regimen are proposed to investigate the effects of assay omission within the DISST-based framework. SI and UN were identified using the fully-sampled DISST and data from 218 nine-sample tests undertaken in 74 female individuals with elevated diabetes risk. This same data was then used with appropriate assay omissions to identify SI and UN with the eight DISST-based assay variations.

RESULTS

Median intraprocedure proportional difference between SI values from fully-sampled DISST and the DISST-based variants was in the range of -17.9 to 7.8%. Correlations were in the range of r = 0.71 to 0.92 with the highest correlations between variants with the greatest commonality with the nine-sample DISST. Metrics of UN correlated relatively well between tests when C-peptide was assayed (r = 0.72 to 1) but were sometimes not well estimated when samples were not assayed for C-peptide (r = -0.14 to 0.75).

CONCLUSIONS

The DISST-based spectrum offers a series of tests with very distinct compromises of information yield, accuracy, assay cost, and clinical intensity. Thus, the spectrum of tests has the potential to enable researchers to better allocate funds by selecting an optimal test configuration for their particular application.

Adiponectin/leptin ratio and metabolic syndrome in a Mexican American population

OBJECTIVE

Adiponectin and leptin play critical roles in the development of Metabolic Syndrome (MetS). This study was designed to assess the feasibility of using circulating levels of adiponectin and leptin for the early diagnosis of MetS.

METHODS

A cross-sectional study was performed using data from 367 participants randomly selected from a well-characterized cohort of Mexican-Americans living at the US-Mexico border.

RESULTS

Significant differences in circulating levels of adiponectin and leptin were observed between males and females. Adiponectin/leptin correlated significantly with MetS in this population. A receiver-operator characteristic (ROC) analysis demonstrated that adiponectin/leptin showed a high sensitivity (70.9% for males, 78.9% for females) and specificity (90.2% for males and 69.8% for females) for the diagnosis of MetS, independent of BMI measurements.

CONCLUSION

These data support the central role of adiponectin and leptin in MetS, and demonstrated that adiponectin/leptin can be used as a highly sensitive and specific biomarker for MetS.

Leptin cut-off values for determination of metabolic syndrome: third national surveillance of risk factors of non-communicable diseases in Iran (SuRFNCD-2007)

Leptin is strongly contributed to the clustering of metabolic syndrome (MetS) components and potentially can be regarded as a single predictor of MetS. This population-based study, for the first time, reports the diagnostic accuracy of different leptin cut-points for determining MetS. Further, the current study compares the predictive ability of the appropriate threshold of leptin with insulin resistance. Data of the individuals without history of known diabetes mellitus, aged 25-64 years, from the third national surveillance of risk factors of non-communicable diseases (SuRFNCD-2007) were analyzed. MetS was defined due to either adult treatment panel III (ATPIII) or the modified international diabetes federation (IDF) criteria. Receiver-operating characteristic (ROC) curves were depicted to define cut-off of serum leptin, using the maximum Youden index and the shortest distance methods. Further, the values of leptin cut-offs in prediction of MetS were compared with those of insulin resistance (defined as homeostasis model assessment of insulin resistance >1.775). In men, the optimal cut-offs of leptin for IDF- and ATPIII-defined MetS were 3.6 ng/ml (positive predictive value, PPV: 56.5%; negative predictive value, NPV: 72.7%) and 4.1 ng/ml (PPV: 49.6%; NPV: 78.1%), respectively. In women, the optimal threshold was equal to 11.0 ng/ml (PPV: 53.8%; NPV: 73.0% for IDF criteria and PPV: 60.1%; NPV: 64.9% for ATPIII criteria). The diagnostic accuracy of these values in identifying MetS was similar to that of insulin resistance. Therefore, leptin is comparable to insulin resistance in identifying MetS and can be used as single predictor of MetS.

Pancreatic ultrastructural enhancement due to telmisartan plus sitagliptin treatment in diet-induced obese C57BL/6 mice

OBJECTIVE

We sought to evaluate the effects of telmisartan, sitagliptin, or their combination on pancreatic ultrastructural alterations in high-fat-fed C57BL/6 mice.

METHODS

Three-month-old C57BL/6 mice were fed with standard chow (SC, 10% lipids) or high-fat diet (HF, 60% lipids) during 10 weeks to induce obesity and its comorbidities. After this period, treatment began (lasted 6 weeks), and the HF group was divided into 4 subgroups: untreated HF, HF plus telmisartan (5 mg/kg per day), HF plus sitagliptin (1.1 g/kg per day), and HF plus telmisartan plus sitagliptin. Drugs were mixed with diet. Biochemical analyses, radioimmunoassay, immunofluorescence, stereology, and transmission electron microscopy were performed to assess pancreatic remodeling.

RESULTS

Overweight, hyperinsulinemia, hyperglycemia, and dyslipidemia were found in the HF group, but these outcomes were controlled by the different treatments. Untreated HF animals also showed alterations concerning distribution of α/β cell followed by large and numerous lipid droplets within pancreas. Telmisartan and sitagliptin as monotherapy alleviated these findings, and a complete reversal of pancreatic steatosis was observed after treating with the combination of the 2 drugs.

CONCLUSIONS

AT1 receptor blockade, partial peroxisome proliferator-activated receptor gamma activation, and extended incretin action emerge as feasible strategies to control pancreatic steatosis and avoid progression of pancreatic diseases due to lipotoxicity.

In vivo and in vitro evidence that PPARγ ligands are antagonists of leptin signaling in breast cancer

Obesity is a major risk factor for the development and progression of breast cancer. Leptin, a cytokine mainly produced by adipocytes, plays a crucial role in mammary carcinogenesis and is elevated in hyperinsulinemia and insulin resistance. The antidiabetic thiazolidinediones inhibit leptin gene expression through ligand activation of the peroxisome proliferator-activated receptor-γ (PPARγ) and exert antiproliferative and apoptotic effects on breast carcinoma. In this study, we investigated the ability of PPARγ ligands to counteract leptin stimulatory effects on breast cancer growth in either in vivo or in vitro models. The results show that activation of PPARγ prevented the development of leptin-induced MCF-7 tumor xenografts and inhibited the increased cell-cell aggregation and proliferation observed on leptin exposure. PPARγ ligands abrogated the leptin-induced up-regulation of leptin gene expression and its receptors in breast cancer. PPARγ-mediated repression of leptin gene involved the recruitment of nuclear receptor corepressor protein and silencing mediator of retinoid and thyroid hormone receptors corepressors on the glucocorticoid responsive element site in the leptin gene expression regulatory region in the presence of glucocorticoid receptor and PPARγ. In addition, PPARγ ligands inhibited leptin signaling mediated by MAPK/STAT3/Akt phosphorylation and counteracted leptin stimulatory effect on estrogen signaling. These findings suggest that PPARγ ligands may have potential therapeutic benefits in the treatment of breast cancer.

Mast cells and metabolic syndrome

Mast cells are critical effectors in the development of allergic diseases and in many immunoglobulin E-mediated immune responses. These cells exert their physiological and pathological activities by releasing granules containing histamine, cytokines, chemokines, and proteases, including mast cell-specific chymase and tryptase. Like macrophages and T lymphocytes, mast cells are inflammatory cells, and they participate in the pathogenesis of inflammatory diseases such as cardiovascular complications and metabolic disorders. Recent observations suggested that mast cells are involved in insulin resistance and type 2 diabetes. Data from animal models proved the direct participation of mast cells in diet-induced obesity and diabetes. Although the mechanisms by which mast cells participate in these metabolic diseases are not fully understood, established mast cell pathobiology in cardiovascular diseases and effective mast cell inhibitor medications used in pre-formed obesity and diabetes in experimental models offer hope to patients with these common chronic inflammatory diseases. This article is part of a Special Issue entitled: Mast cells in inflammation.

Palatinose-blended sugar compared with sucrose: different effects on insulin sensitivity after 12 weeks supplementation in sedentary adults

BACKGROUND

We investigated the effects of daily palatinose intake on the risk factors of metabolic syndrome in sedentary non-obese Japanese adults.

METHODS

Japanese adults (40 females and 10 males, age: 53 +/- 9 years, range: 31-72 years old) were randomized into two groups for a double-blind, placebo-controlled intervention study and given either 40 g/day palatinose-blended sugar (PS group) or 40 g/day sucrose (S group) in their diet for 12 weeks.

RESULTS

After the intervention, the insulin resistance index (HOMA-IR) had significantly decreased only in the PS group; the inter-group difference was significant at P = 0.006. Although the S group showed a significant increase in the leptin concentration and the systolic blood pressure, the PS group showed no significant changes; the inter-group differences were significant at P = 0.018 and P = 0.037, respectively.

CONCLUSION

Palatinose intake possibly improves insulin sensitivity when compared with sucrose intake.