Atherogenecity of LDL and unfavorable adipokine profile in metabolically obese, normal-weight woman

Higher childhood weight gain, lower skeletal muscle mass, and higher cereal consumption in normal-weight Japanese women with high-percentage trunk fat: a subanalysis study

Normal-weight but high-percentage trunk fat phenotype was characterized in a setting where adiposity is not associated with educational and socioeconomic status. Body size trajectory since birth, current body composition measured using whole-body dual-energy X-ray absorptiometry, cardiometabolic traits, serum adipokines, and dietary intake were measured cross-sectionally in 251 normal weight Japanese female university students whose fasting triglyceride and homeostasis model assessment-insulin resistance (HOMA-IR) averaged 56 mg/dL and 1.2, respectively. They were grouped according to tertile of percentage trunk fat. Although HOMA-IR did not differ among three groups, high-percentage trunk fat was associated with higher triglyceride and apolipoprotein B, and lower HDL cholesterol and apolipoprotein A1. In multivariate logistic regression analyses, weight-adjusted skeletal muscle mass (OR: 0.13, 95% CI: 0.04-0.38, p < 0.001), weight gain from birth to age 12 years (OR: 1.214、95% CI: 1.008-1.463、p = 0.04), and cereal consumption (OR:1.008, 95% CI: 1.000-1.016, p = 0.04) were associated with high-percentage trunk fat independent of birthweight, HOMA-IR, adipose tissue-insulin resistance index (the product of fasting insulin and free fatty acid), triglyceride, HDL cholesterol, apolipoprotein A1 and B, leptin, adiponectin, blood pressure, and high-sensitivity C-reactive protein. Early childhood growth, lower skeletal muscle mass, and higher cereal consumption may be associated with normal-weight but high-percentage trunk fat phenotype in Japanese female university students in this subanalysis study. Atherogenic profile of lipids and apolipoproteins may be directly related to abdominal fat accumulation.

Triglyceride-glucose index is capable of identifying metabolically obese, normal-weight older individuals

BACKGROUND

The concept of metabolically obese, normal weight (MONW) has emerged to describe individuals with a normal body mass index (BMI) who are at a relatively high risk of chronic diseases. However, BMI itself is a suboptimal index for the assessment of the health risks associated with visceral fat. The triglyceride-glucose (TyG) index is considered to be a reliable and cost-effective marker of insulin resistance. Therefore, in the present study, we aimed to determine the TyG index cut-off values that could be used to define MONW in older people and to determine the usefulness of these values for the prediction of chronic diseases.

METHODS

A total of 4,721 participants in the Korea National Health and Nutritional Examination Survey who were ≥ 60 years of age and did not have underweight or obesity were included. MONW was defined using the criteria for metabolic syndrome (MS), and the TyG index was calculated on the basis of the fasting plasma triglyceride and glucose concentrations. Chronic diseases, including T2DM, hypertension, and non-alcoholic fatty liver disease (NAFLD), were diagnosed.

RESULTS

The prevalence of MS increased from the lowest to the highest TyG index tertile. The cut-off values of the TyG index for MONW were calculated as 8.88 and 8.80 for males and females, respectively. MONW, defined using these cut-off values, was associated with high odds ratios for NAFLD, T2DM, and hypertension in both males and females.

CONCLUSIONS

The TyG index cut-off values calculated in the present study can be used to discriminate individuals with MONW from other older individuals without obesity and to predict the risk of chronic diseases. These findings show that the TyG index is an effective and cost-efficient method of assessing the risk of chronic diseases in people with MONW.

Phenotyping obesity: A focus on metabolically healthy obesity and metabolically unhealthy normal weight

Over the past 4 decades, research has shown that having a normal body weight does not automatically imply preserved metabolic health and a considerable number of lean individuals harbour metabolic abnormalities typically associated with obesity. Conversely, excess adiposity does not always equate with an abnormal metabolic profile. In fact, evidence exists for the presence of a metabolically unhealthy normal weight (MUHNW) and a metabolically healthy obese (MHO) phenotype. It has become increasingly recognised that different fat depots exert different effects on the metabolic profile of each individual by virtue of their location, structure and function, giving rise to these different body composition phenotypes. Furthermore, other factors have been implicated in the aetiopathogenesis of the body composition phenotypes, including genetics, ethnicity, age and lifestyle/behavioural factors. Even though to date both MHO and MUHNW have been widely investigated and documented in the literature, studies report different outcomes on long-term cardiometabolic morbidity and mortality. Future large-scale, observational and population-based studies are required for better profiling of these phenotypes as well as to further elucidate the pathophysiological role of the adipocyte in the onset of metabolic disorders to allow for better risk stratification and a personalised treatment paradigm.

Association between normal-weight obesity and bone mineral density in older Korean adults: A population-based cross-sectional study

The effects of normal-weight obesity, which is defined as having a high level of body fat despite a normal body mass index, on the health of bones in older adults are poorly understood. This cross-sectional study examined the relationship between normal-weight obesity and bone mineral density in Korean adults aged 50 years or more (2815 men and 2744 women) from the 2008-2011 Korea National Health and Nutrition Examination Surveys. Between the ages of 50 and 69 years, individuals with normal-weight obesity had a higher risk of low bone mineral density (odds ratio = 1.596, 95 % confidence interval = 1.189-2.141, p = 0.002) compared with individuals with normal-weight non-obesity. However, no significant association between normal-weight obesity and bone mineral density was observed among people between the ages of 70 and 89 years. The study findings support the clinical significance of normal-weight obesity as a proxy biomarker to identify in primary care settings people who are at increased risk of developing osteoporosis at an early stage of aging.

Metabolic syndrome is associated with similar long-term prognosis in those living with and without obesity: an analysis of 45 615 patients from the nationwide LIPIDOGRAM 2004-2015 studies

AIMS

We aimed to evaluate the association between metabolic syndrome (MetS) and long-term all-cause mortality.

METHODS AND RESULTS

The LIPIDOGRAM studies were carried out in the primary care in Poland in 2004, 2006, and 2015. MetS was diagnosed based on the National Cholesterol Education Program, Adult Treatment Panel III (NCEP/ATP III), and Joint Interim Statement (JIS) criteria. The cohort was divided into four groups: non-obese patients without MetS, obese patients without MetS, non-obese patients with MetS, and obese patients with MetS. Differences in all-cause mortality were analysed using Kaplan-Meier and Cox regression analyses. A total of 45 615 participants were enrolled (mean age 56.3, standard deviation: 11.8 years; 61.7% female). MetS was diagnosed in 14 202 (31%) by NCEP/ATP III criteria and 17 216 (37.7%) by JIS criteria. Follow-up was available for 44 620 (97.8%, median duration 15.3 years) patients. MetS was associated with increased mortality risk among the obese {hazard ratio, HR: 1.88 [95% confidence interval (CI) 1.79-1.99] and HR: 1.93 [95% CI 1.82-2.04], according to NCEP/ATP III and JIS criteria, respectively} and non-obese individuals [HR: 2.11 (95% CI 1.85-2.40) and 1.7 (95% CI 1.56-1.85) according to NCEP/ATP III and JIS criteria, respectively]. Obese patients without MetS had a higher mortality risk than non-obese patients without MetS [HR: 1.16 (95% CI 1.10-1.23) and HR: 1.22 (95% CI 1.15-1.30), respectively in subgroups with NCEP/ATP III and JIS criteria applied].

CONCLUSIONS

MetS is associated with increased all-cause mortality risk in non-obese and obese patients. In patients without MetS, obesity remains significantly associated with mortality. The concept of metabolically healthy obesity should be revised.

Adipose tissue specific CCL18 associates with cardiometabolic diseases in non-obese individuals implicating CD4+ T cells

AIM

Obesity is linked to cardiometabolic diseases, however non-obese individuals are also at risk for type 2 diabetes (T2D) and cardiovascular disease (CVD). White adipose tissue (WAT) is known to play a role in both T2D and CVD, but the contribution of WAT inflammatory status especially in non-obese patients with cardiometabolic diseases is less understood. Therefore, we aimed to find associations between WAT inflammatory status and cardiometabolic diseases in non-obese individuals.

METHODS

In a population-based cohort containing non-obese healthy (n = 17), T2D (n = 16), CVD (n = 18), T2D + CVD (n = 19) individuals, seventeen different cytokines were measured in WAT and in circulation. In addition, 13-color flow cytometry profiling was employed to phenotype the immune cells. Human T cell line (Jurkat T cells) was stimulated by rCCL18, and conditioned media (CM) was added to the in vitro cultures of human adipocytes. Lipolysis was measured by glycerol release. Blocking antibodies against IFN-γ and TGF-β were used in vitro to prove a role for these cytokines in CCL18-T-cell-adipocyte lipolysis regulation axis.

RESULTS

In CVD, T2D and CVD + T2D groups, CCL18 and CD4+ T cells were upregulated significantly compared to healthy controls. WAT CCL18 secretion correlated with the amounts of WAT CD4+ T cells, which also highly expressed CCL18 receptors suggesting that WAT CD4+ T cells are responders to this chemokine. While direct addition of rCCL18 to mature adipocytes did not alter the adipocyte lipolysis, CM from CCL18-treated T cells increased glycerol release in in vitro cultures of adipocytes. IFN-γ and TGF-β secretion was significantly induced in CM obtained from T cells treated with CCL18. Blocking these cytokines in CM, prevented CM-induced upregulation of adipocyte lipolysis.

CONCLUSION

We suggest that in T2D and CVD, increased production of CCL18 recruits and activates CD4+ T cells to secrete IFN-γ and TGF-β. This, in turn, promotes adipocyte lipolysis - a possible risk factor for cardiometabolic diseases.

Association of normal weight obesity phenotype with inflammatory markers: A systematic review and meta-analysis

Background

Individuals with normal weight could suffer from obesity based on their body fat percentage (also known as normal weight obesity (NWO)), thus being at risk of significant morbidity and mortality compared to the general population. It seems that inflammatory pathways and chronic inflammation are significant contributors to the pathogenicity of NWO. This study aimed to assess and pool the association of proinflammatory and anti-inflammatory cytokines with NWO.

Methods

In this systematic review and meta-analysis, online international databases (PubMed, Scopus, EMBASE, Web of Science, and Google Scholar) were searched until August 2022. All observational studies with an English full text comparing the mean levels of proinflammatory and anti-inflammatory cytokines (e.g., C-reactive protein (CRP), various types of interleukins (IL) s, tumor necrosis factor-alpha (TNF)) and white blood cell (WBC) count, in subjects with NWO and "normal weight non-obese (NWNO)" were included. Two researchers independently screened, reviewed and assessed the quality of included studies. The remaining articles' data were extracted post-screening. The heterogeneity between studies was assessed using the I² and Cochran's Q tests. A random effect model meta-analysis was used to pool the standardized mean difference (SMD) as an effect size.

Results

From the initial 559 studies, 21 and 19 were included in the qualitative and quantitative synthesis, respectively. In the systematic review, 8 studies reported a significant association between various proinflammatory cytokines (CRP, IL₆, IL_1β, and TNFα) and NWO. According to random-effect meta-analysis, the association between NWO with CRP (SMD: 0.60, 95% CI: 0.30, 0.91) and IL6 (SMD: 0.90, 95%CI: 0.14, 1.66) was statistically significant. Moreover, the mean level of TNF_α in subjects with NWO and NWNO did not differ significantly (SMD: 0.67, 95% CI: -0.36, 1.70).

Conclusion

The findings of this study show that NWO was associated with high levels of CRP and IL6. Therefore, inflammatory pathways may play a role in the pathogenicity of NWO.

Metabolic Obesity in People with Normal Body Weight (MONW)-Review of Diagnostic Criteria

Disorders of metabolic obesity with normal body weight (MONW) are widely recognized risk factors for the development of cardiovascular diseases and type 2 diabetes. Despite this, MONW is not diagnosed in clinical practice. There is no consensus on the definition of MONW, and measuring the degree of insulin resistance or obesity among apparently healthy, non-obese patients is not widely applicable. The awareness of the relationship between metabolic disorders such as MONW and a higher risk of mortality from cardiovascular causes and other related diseases prompts the need for action to be taken aimed at creating appropriate diagnostic models that will allow for the effective detection of those with metabolic abnormalities among people with normal body weight. Such actions are decisive in the prevention and treatment of diseases. Therefore, the purpose of this article is to review the MONW diagnostic criteria used over the years.

Association of Metabolic Health and Central Obesity With the Risk of Thyroid Cancer: Data from the Korean Genome and Epidemiology Study

BACKGROUND

It is unknown whether the risk of thyroid cancer differs among metabolically healthy/unhealthy, normal-weight, or obese women. We aimed to assess the association of metabolic health and obesity with thyroid cancer risk.

METHODS

The Korean Genome and Epidemiology Study is a population-based prospective cohort study. Data were obtained from 173,343 participants (age {greater than or equal to}40 years) enrolled from 2004 to 2013. Obese participants were those with body mass index (BMI) {greater than or equal to}25 kg/m2. Participants with abnormalities in three of these indices were considered metabolically unhealthy: triglycerides, blood pressure, high-density lipoprotein cholesterol (HDL-cholesterol), waist circumference (WC), and fasting glucose levels. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for thyroid cancer risk associated with metabolic health and obesity.

RESULTS

Compared to non-obese women without metabolic abnormalities, metabolically unhealthy women, either normal-weight or obese, had an increased risk of thyroid cancer (HR [95% CI]=1.57[1.02-2.40] and 1.71[1.21-2.41], respectively). Significant association was not observed in men. Thyroid cancer risk was higher among non-obese women with high WC ({greater than or equal to}85 cm; HR [95% CI]=1.62[1.03-2.56]) than in non-obese women with low WC, and in obese women with low HDL-cholesterol (<50 mg/dL; HR[95% CI]=1.75[1.26-2.42]) compared to non-obese women with high HDL-cholesterol.

CONCLUSIONS

Metabolically unhealthy women or women with central adiposity may be at an increased thyroid cancer risk despite normal BMI.

IMPACT

This study suggests that women with central obesity and metabolically abnormality despite normal BMI may constitute a target group for thyroid cancer prevention and control programs.

Cancer Risk in Normal Weight Individuals with Metabolic Obesity: A Narrative Review

Obesity represents one of the most significant public health challenges worldwide. Current clinical practice relies on body mass index (BMI) to define the obesity status of an individual, even though the index has long been recognized for its limitations as a measure of body fat. In normal BMI individuals, increased central adiposity has been associated with worse health outcomes, including increased risks of cardiovascular disease and metabolic disorders. The condition leading to these outcomes has been described as metabolic obesity in the normal weight (MONW). More recent evidence suggests that MONW is associated with increased risk of several obesity-related malignancies, including postmenopausal breast, endometrial, colorectal, and liver cancers. In MONW patients, the false reassurance of a normal range BMI can lead to lost opportunities for implementing preventive interventions that may benefit a substantial number of people. A growing body of literature has documented the increased risk profile of MONW individuals and demonstrated practical uses for body composition and biochemical analyses to identify this at-risk population. In this review, we survey the current literature on MONW and cancer, summarize pathophysiology and oncogenic mechanisms, highlight potential strategies for diagnosis and treatment, and suggest directions for future research.

Metabolically healthy obesity and metabolically obese normal weight: a review

Despite the general relationship between obesity and its co-morbidities, there are both obese individuals who scarcely present the associated pathologies (metabolically healthy obese; MHO) and individuals who present obesity alterations despite having normal weight (metabolically obese normal weight; MONW). It is still difficult to define metabolically MHO and MONW individuals because different classifications have been used in the studies reported. Indeed, different inclusion criteria have been used to discriminate between metabolically healthy and metabolically unhealthy subjects. Due to this and other reasons, such as differences in ethnicity, genetics, and lifestyle of the populations, data concerning the prevalence of MHO and MONW are very variable. The main determinants of MHO are type of growth (hypertrophy or hyperplasia), anatomical location, inflammation of adipose tissue, ectopic fat accumulation, genetic factors, and lifestyles factors. In the case of MONW, the main determinants are genetic background and lifestyle factors. With regard to treatment, it is not clear whether MHO subjects would benefit from traditional lifestyle interventions, based on diet energy restriction and increased physical activity. For MONW subjects, there is still no specialized treatment, and the therapies are the same as those used in obese subjects.

Impact of insulin resistance on subclinical left ventricular dysfunction in normal weight and overweight/obese japanese subjects in a general community

BACKGROUND

Insulin resistance carries increased risk of heart failure, although the pathophysiological mechanisms remain unclear. LV global longitudinal strain (LVGLS) assessed by speckle-tracking echocardiography has emerged as an important tool to detect early LV systolic abnormalities. This study aimed to investigate the association between insulin resistance and subclinical left ventricular (LV) dysfunction in a sample of the general population without overt cardiac disease.

METHODS

We investigated 539 participants who voluntarily underwent extensive cardiovascular health check including laboratory test and speckle-tracking echocardiography. Glycemic profiles were categorized into 3 groups according to homeostatic model assessment of insulin resistance (HOMA-IR): absence of insulin resistance (HOMA-IR < 1.5), presence of insulin resistance (HOMA-IR ≥ 1.5) and diabetes mellitus (DM). Multivariable logistic regression models were conducted to evaluate the association between abnormal glucose metabolism and impaired LVGLS (> - 16.65%).

RESULTS

Forty-five (8.3%) participants had DM and 66 (12.2%) had abnormal HOMA-IR. LV mass index and E/e' ratio did not differ between participants with and without abnormal HOMA-IR, whereas abnormal HOMA-IR group had significantly decreased LVGLS (- 17.6 ± 2.6% vs. - 19.7 ± 3.1%, p < 0.05). The prevalence of impaired LVGLS was higher in abnormal HOMA-IR group compared with normal HOMA-IR group (42.4% vs. 14.0%) and similar to that of DM (48.9%). In multivariable analyses, glycemic abnormalities were significantly associated with impaired LVGLS, independent of traditional cardiovascular risk factors and pertinent laboratory and echocardiographic parameters [adjusted odds ratio (OR) 2.38, p = 0.007 for abnormal HOMA-IR; adjusted OR 3.02, p = 0.003 for DM]. The independent association persisted even after adjustment for waist circumference as a marker of abdominal adiposity. Sub-group analyses stratified by body mass index showed significant association between abnormal HOMA-IR and impaired LVGLS in normal weight individuals (adjusted OR 4.59, p = 0.001), but not in overweight/obese individuals (adjusted OR 1.62, p = 0.300).

CONCLUSIONS

In the general population without overt cardiac disease, insulin resistance carries independent risk for subclinical LV dysfunction, especially in normal weight individuals.

Adiponectin Is Related to Cardiovascular Risk in Severe Mental Illness Independent of Antipsychotic Treatment

Background: Schizophrenia (SCZ) and bipolar disorder (BD) are severe mental illnesses (SMI) associated with elevated cardiovascular disease (CVD) risk, including obesity. Leptin and adiponectin are secreted by adipose tissue, with pro- and anti-inflammatory properties, respectively. The second generation antipsychotics (AP) olanzapine, clozapine, and quetiapine have been associated with high leptin levels in SMI. However, the link between inflammatory dysregulation of leptin and adiponectin and CVD risk in SMI, and how this risk is influenced by body mass and AP medication, is still not completely understood. We investigated herein if leptin, adiponectin or their ratio (L/A ratio) could predict increased CVD risk in SCZ, BD, and in subgroups according to use of antipsychotic (AP) treatment, independent of other cardio-metabolic risk factors. Methods: We measured fasting plasma levels of leptin and adiponectin, and calculated the L/A ratio in n = 1,092 patients with SCZ and BD, in subgroups according to AP treatment, and in n = 176 healthy controls (HC). Differences in the levels of adipokines and L/A between groups were examined in multivariate analysis of covariance, and the correlations between adipokines and body mass index (BMI) with linear regression. CVD risk was defined by total cholesterol/high-density lipoprotein (TC/HDL) and triglyceride/HDL (TG/HDL) ratios. The adipokines and L/A ratios ability to discriminate individuals with TG/HDL and TC/HDL ratios above threshold levels was explored by ROC analysis, and we investigated the possible influence of other cardio-metabolic risk factors on the association in logistic regression analyses. Results: We observed higher leptin levels and L/A ratios in SMI compared with HC but found no differences in adiponectin. Both adipokines were highly correlated with BMI. The low adiponectin levels showed a fair discrimination in ROC analysis of individuals with CVD risk, with AUC between 0.7 and 0.8 for both TC/HDL and TG/HDL, in all groups examined regardless of diagnosis or AP treatment. Adiponectin remained significantly associated with an elevated TC/HDL and TG/HDL ratio in SMI, also after further adjustment with other cardio-metabolic risk factors. Conclusions: Adiponectin is not dysregulated in SMI but is associated with CVD risk regardless of AP treatment regime.

Prospective Association of Obesity Patterns with Subclinical Carotid Plaque Development in Early Postmenopausal Chinese Women

OBJECTIVE

This study aimed to examine the prospective associations of general and abdominal obesity patterns with carotid plaque development among early postmenopausal Chinese women.

METHODS

A total of 518 postmenopausal women aged 50 to 64 years were recruited between 2002 and 2004 and were followed up at 3 years and 5 years. Carotid plaque was measured using B-mode ultrasonography, whereas general and abdominal obesity were defined as BMI ≥ 25 kg/m² and waist-hip ratio ≥ 0.85, respectively. Sociodemographic, lifestyle, mental health, disease history, and clinical measurements were also assessed for confounding control. Multivariable binary logistic regression analyses on plaque development at 5 years were performed among 322 women with no carotid plaque at baseline.

RESULTS

Over the 5-year follow-up period, 70 women (21.7%) developed carotid plaque. Baseline abdominal obesity independently predicted plaque development (adjusted odds ratio = 2.30; 95% CI: 1.15-4.60), but general obesity did not. Women with normal-weight abdominal obesity were more than twice as likely to develop carotid plaque (adjusted odds ratio = 2.43; 95% CI: 1.02-5.75) compared with women with no obesity, with their risk comparable to women with both general and abdominal obesity.

CONCLUSIONS

Abdominal obesity was a critical predictor of subclinical carotid plaque development among early postmenopausal Chinese women. Policy makers should recognize the need to identify high-risk midlife women with normal-weight abdominal obesity in public health and clinical practice.

Increased incidence of bladder cancer with metabolically unhealthy status: analysis from the National Health Checkup database in Korea

We assessed the association between metabolic health status and the incidence of bladder cancer using nationally representative data from the National Health Insurance System and National Health Checkups (NHC) databases in South Korea. Data for 11,781,768 men who participated in the NHC between 2009 and 2012 were analysed. The normal-weight and physically obese categories were defined as body mass indexes (BMI) < 25 and ≥25 kg/m², respectively. Metabolically obese was defined as the presence of ≥3 components of metabolic syndrome. The participants were stratified into metabolically healthy, normal-weight (MHNW); metabolically obese, normal-weight (MONW); metabolically healthy, obese (MHO); metabolically obese, obese (MOO). Multivariate-adjusted Cox regression analysis was conducted to examine the association between metabolic health status and the incidence of bladder cancer. The study participants included 17,777 men newly registered with bladder cancer. Analysis according to metabolic health status classification revealed a higher multivariable-adjusted hazard ratio in the MOO, MONW group than in the MHO group (1.307 [95% CI: 1.258–1.358], 1.183 [95% CI: 1.137–1.231] and 1.066 [95% CI: 1.017–1.119], respectively; hazard ratios given relative to MHNW group) We found an association between metabolic health status and the incidence of bladder cancer, with an increasing risk according to the number of metabolic health status components.

Physiological and Lifestyle Traits of Metabolic Dysfunction in the Absence of Obesity

PURPOSE OF REVIEW

Individuals with metabolically unhealthy normal weight (MUNW) have an adverse cardiometabolic risk factor profile in the absence of excess body weight, and increased risk for diabetes and heart disease. We critically review some physiological traits and lifestyle characteristics of the MUNW phenotype.

RECENT FINDINGS

The prevalence of MUNW varies considerably around the world and among ethnicities, partly because of different definitions; on average, this phenotype affects about ~ 30% of normal weight persons globally. Most studies have recruited MUNW subjects who, although within the normal weight range, are significantly "more obese" than their metabolically healthy lean peers (greater body mass index or total body fat); hence one cannot ascertain whether observed differences are true traits of the MUNW phenotype of simply secondary to greater relative adiposity within the normal range. Carefully matched studies have indicated that MUNW can exist in the absence of excess total body fat. These subjects have a preferential accumulation of fat in the upper body (abdominal subcutaneous and visceral adipose tissues) and the liver, but not skeletal muscle; perhaps surprisingly, this predominantly "android" fat distribution does not translate into increased waist circumference. The MUNW phenotype is associated with lower aerobic fitness and muscle mass and strength, but whether this is simply due to inadequate regular physical activity is not entirely clear. Likewise, no consistent associations have been found between any dietary factors and the development of MUNW phenotype, but diet-induced modest weight loss facilitates its resolution. Delineating the mechanisms leading to metabolic dysfunction in the absence of increased body weight and body fat will likely reveal important targets for improving metabolic health and eventually for reducing the burden of cardiometabolic disease, not only in individuals with normal body weight but also in people with obesity.

Obesity-Stroke Paradox Exists in Insulin-Resistant Patients But Not Insulin Sensitive Patients

Background and Purpose- The underlying mechanisms of stroke-obesity paradox are still not fully understood. This study aims to investigate the contribution of insulin resistance to the association between body mass index and stroke outcomes. Methods- Patients with ischemic stroke without history of diabetes mellitus in the Abnormal Glucose Regulation in Patients With Acute Stroke Across-China registry were included. Overweight or obese was defined as body mass index ≥23, and the median of homeostasis model assessment-insulin resistance index was chosen as cutoff to define insulin resistance. Cox or logistic regression model was used to assess the interaction between body mass index and homeostasis model assessment-insulin resistance on 1-year prognosis (all-cause mortality and poor functional outcome defined as modified Rankin Scale score 3-6). Results- Of 1227 study participants, the median homeostasis model assessment-insulin resistance was 1.9 (interquartile range, 1.1-3.1) and 863 (70.3%) patients were classified as overweight or obese. Among insulin-resistant patients, overweight/obese patients experienced one-half of the risk of death after stroke than their low/normal weight counterparts (9.42% versus 17.69%, unadjusted hazard ratio, 0.50; 95% CI, 0.31-0.82), while among insulin-sensitive ones, no significant difference of mortality risk was found (7.58% versus 6.91%, 1.07; 0.57-1.99). Similar trends were observed for poor functional outcome. Results were similar after adjustments for confounders. There were significant interactions between body mass index and homeostasis model assessment-insulin resistance on the risks of mortality (P=0.045) and poor functional outcome (P=0.049). Conclusions- We observed the obesity paradox for mortality and functional outcome in insulin-resistant patients but did not find the obesity paradox in insulin-sensitive patients. Insulin resistance may be one of the mechanisms underlying the obesity paradox of the outcome in patients with ischemic stroke.

Associations between Macronutrient Intakes and Obesity/Metabolic Risk Phenotypes: Findings of the Korean National Health and Nutrition Examination Survey

Obesity is a risk factor for many health issues, as are metabolic abnormalities. However, few studies have addressed the associations between obesity/metabolic risk phenotypes and dietary macronutrient intakes (carbohydrate, protein, and fat). Therefore, this study examined the associations between macronutrient intakes and obesity/metabolic risk phenotypes in a Korean population. We used data from the Korean National Health and Nutrition Examination Survey, a cross-sectional survey of Korean civilians, conducted in 2014 and 2016, and data on a total of 7374 participants were analyzed. Macronutrient intakes were defined as the proportions of energy derived from carbohydrate, protein, and fat. Those exhibiting obesity/metabolic risk phenotypes (or not) were divided into four groups: normal weight without metabolic abnormalities; obese without metabolic abnormalities; normal weight with metabolic abnormalities; and obese with metabolic abnormalities. After adjusting for age, smoking status, alcohol consumption, extent of physical activity, household income, and daily fiber intake, no association was found between the proportions of carbohydrate, protein, or fat intakes and obesity/metabolic risk phenotypes except for a positive association between metabolically healthy but obese status and low protein intake in females. Further studies are required to evaluate the effects of macronutrient intakes on obesity/metabolic risk phenotypes and associated health outcomes.

Incidence of Prostate Cancer according to Metabolic Health Status: a Nationwide Cohort Study

BACKGROUND

We assessed the association between metabolic health status and incidence of prostate cancer using the National Health Check-ups (NHC) database of Korea.

METHODS

A total of 11,771,252 men who participated in the NHC between 2009 and 2012 and 56,552 men who were newly diagnosed with prostate cancer were analyzed. Normal-weight and obesity were defined as body mass index (BMI) < 25 kg/m² and ≥ 25 kg/m², respectively. Metabolic obesity was defined as the presence ≥ 3 components of the metabolic syndrome. Participants were stratified into 4 groups: metabolically healthy, normal-weight; metabolically obese, normal-weight (MONW); metabolically healthy, obese (MHO); and metabolically obese, obese. Multivariate Cox regression analysis was performed to examine the relationship between metabolic health status and incidence of prostate cancer.

RESULTS

During a mean 5.4 ± 1.1 years of follow-up, 56,552 patients were registered with a diagnosis of prostate cancer. When analyzed according to metabolic health status classification, the multivariable-adjusted hazard ratio (HR) was 1.143 for the MONW group, 1.097 for the MHO group, showing the HR for the MONW group was higher than that for the MHO group. As the number of metabolic syndrome components increased, HR increased significantly. When stratified based on BMI, metabolically obese patients showed significantly higher HR than metabolically healthy patients in all BMI groups.

CONCLUSION

This population-based nationwide study revealed an association between metabolic health status and the incidence of prostate cancer, and the risk increased according to the number of components of the metabolic syndrome.

Obesity phenotypes and their paradoxical association with cardiovascular diseases

The pro-inflammatory state of the visceral adipose tissue (VAT) is supposed to accelerate cardiovascular (CV) and metabolic diseases in obese subjects. Some studies have recently reported an improved CV prognosis in certain obese and overweight patients as compared with leaner ones. This phenomenon, known as the "obesity paradox" (OP), has been described in many chronic diseases. This narrative review is based on the material searched for and obtained via PubMed and Web of Science up to May 2017. The search terms we used were: "obesity, paradox, adipose tissue" in combination with "cardiovascular, coronary heart disease, heart failure, arrhythmias". Using the current Body Mass Index (BMI)-based obesity definition, individuals with different clinical and biochemical characteristics are gathered together in the same category. Emerging evidence point to the existence of many "Obesity phenotypes" with different association with CV risk, accordingly to physical and life-style features. In this narrative review, we discussed if obesity phenotypes may be associated with a different CV risk, potentially explaining the OP. As a globally accepted definition of obesity is still lacking, we emphasized the need of a new approach, which should consider the heterogeneity of obesity. Better defining "obesities" and related CV risk is critical to markedly improve the classical BMI-based definition of obesity.

Metabolic Phenotype and Risk of Colorectal Cancer in Normal-Weight Postmenopausal Women

BACKGROUND

The prevalence of metabolically unhealthy phenotype in normal-weight adults is 30%, and few studies have explored the association between metabolic phenotype and colorectal cancer incidence in normal-weight individuals. Our aim was to compare the risk of colorectal cancer in normal-weight postmenopausal women who were characterized by either the metabolically healthy phenotype or the metabolically unhealthy phenotype.

METHODS

A large prospective cohort, the Women's Health Initiative, was used. The analytic sample included 5,068 postmenopausal women with BMI 18.5 to <25 kg/m² Metabolic phenotype was defined using the Adult Treatment Panel-III definition, excluding waist circumference; therefore, women with one or none of the four components (elevated triglycerides, low high-density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose) were classified as metabolically healthy. Multivariable Cox proportional hazards regression was used to estimate adjusted HRs for the association between metabolic phenotype and risk of colorectal cancer.

RESULTS

Among normal-weight women, those who were metabolically unhealthy had higher risks of colorectal cancer (HR, 1.49; 95% CI, 1.02-2.18) compared with those who were metabolically healthy.

CONCLUSIONS

A metabolically unhealthy phenotype was associated with higher risk of colorectal cancer among normal-weight women.

IMPACT

Normal-weight women should still be evaluated for metabolic health and appropriate steps taken to reduce their risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 26(2); 155-61. ©2017 AACR.

Study protocol for the FITR Heart Study: Feasibility, safety, adherence, and efficacy of high intensity interval training in a hospital-initiated rehabilitation program for coronary heart disease

Background

For decades, moderate intensity continuous training (MICT) has been the cornerstone of exercise prescription for cardiac rehabilitation (CR). High intensity interval training (HIIT) is now recognized in CR exercise guidelines as an appropriate and efficient modality for improving cardiorespiratory fitness, a strong predictor of mortality. However, the clinical application of HIIT in a real world CR setting, in terms of feasibility, safety, and long-term adherence, needs further investigation to address ongoing reservations. Furthermore, studies using objective measures of exercise intensity (such as heart rate; HR) have produced variable outcomes. Therefore we propose investigating the use of subjective measures (such as rating of perceived exertion (RPE)) for prescribing exercise intensity.

Methods

One hundred adults with coronary artery disease (CAD) attending a hospital-initiated CR program will be randomized to 1) HIIT: 4 × 4 min high intensity intervals at 15–18 RPE interspersed with 3-min active recovery periods or 2) MICT: usual care exercise including 40 min continuous exercise at a moderate intensity corresponding to 11–13 RPE. Primary outcome is change in exercise capacity (peak VO₂) following 4 weeks of exercise training. Secondary outcome measures are: feasibility, safety, exercise adherence, body composition, vascular function, inflammatory markers, intrahepatic lipid, energy intake, and dietary behavior over 12-months; and visceral adipose tissue (VAT) following 12 weeks of exercise training.

Conclusions

This study aims to address the ongoing concerns regarding the practicality and safety of HIIT in CR programs. We anticipate study findings will lead to the development of a standardized protocol to facilitate CR programs to incorporate HIIT as a standard exercise option for appropriate patients.

Dyslipidemia: Obese or Not Obese-That Is Not the Question

PURPOSE OF REVIEW

Purpose of review: It is becoming increasingly clear that some obese individuals do not develop dyslipidemia and instead remain healthy, while some normal weight individuals become dyslipidemic and unhealthy.

RECENT FINDINGS

The present review examines the similarities and differences between healthy and unhealthy individuals with and without obesity and discusses putative underlying mechanisms of dyslipidemia. The presence of dyslipidemia and compromised metabolic health in both lean and obese individuals suggests that the obese phenotype per se does not represent a main independent risk factor for the development of dyslipidemia and that dyslipidemia, rather than obesity, may be the driver of metabolic diseases. Notably, adipose tissue dysfunction and ectopic lipid deposition, in particular in the liver, seems a common trait of unhealthy individuals.

Are all metabolically healthy individuals with obesity at the same risk of diabetes onset?

OBJECTIVE

To examine the risk of diabetes and the development of an unhealthy status according to metabolic health. To assess the effect of changes in metabolic health among participants with metabolically healthy obesity (MHO) on the risk of diabetes.

METHODS

A total of 4,340 subjects were included. Unhealthy metabolic status was defined as having three or more risk factors of the Adult Treatment Panel-III criteria. A Cox proportional-hazard analysis was conducted to estimate the hazard ratio (HR) of developing diabetes across the change in the metabolic status of subjects with MHO.

RESULTS

After 40,622 person-years of follow-up, the risk of becoming unhealthy was 1.53 times higher for participants with MHO, compared with lean or overweight healthy subjects. A greater risk of diabetes was found in MHO, but it was attributable to those who progressed to an unhealthier status over time: HR of 4.78 (95% CI: 3.38-6.78). The combination of being metabolically unhealthy and obesity heightened the risk of diabetes: HR of 10.09 (95% CI: 4.82-21.55).

CONCLUSIONS

The increased risk of diabetes in MHO is attributed to the progression to an unhealthier state. "Healthy obesity" is not a permanent situation but a transitory state.

Adipose tissue infiltration in normal-weight subjects and its impact on metabolic function

Discordant phenotypes, metabolically healthy obese and unhealthy normal-weight individuals, are always interesting to provide important insights into the mechanistic link between adipose tissue dysfunction and associated metabolic alterations. Macrophages can release factors that impair the proper activity of the adipose tissue. Thus, studying subcutaneous and visceral adipose tissues, we investigated for the first time the differences in monocyte/macrophage infiltration, inflammation, and adipogenesis of normal-weight subjects who differed in their degree of metabolic syndrome. The study included 92 normal-weight subjects who differed in their degree of metabolic syndrome. Their anthropometric and biochemical parameters were measured. RNA from subcutaneous and visceral adipose tissues was isolated, and mRNA expression of monocyte/macrophage infiltration (CD68, CD33, ITGAM, CD163, EMR-1, CD206, MerTK, CD64, ITGAX), inflammation (IL-6, tumor necrosis factor alpha [TNFα], IL-10, IL-1b, CCL2, CCL3), and adipogenic and lipogenic capacity markers (PPARgamma, FABP4) were measured. Taken together, our data provide evidence of a different degree of macrophage infiltration between the adipose tissues, with a higher monocyte/macrophage infiltration in subcutaneous adipose tissue in metabolically unhealthy normal-weight subjects, whereas visceral adipose tissue remained almost unaffected. An increased macrophage infiltration of adipose tissue and its consequences, such as a decrease in adipogenesis function, may explain why both the obese and normal-weight subjects can develop metabolic diseases or remain healthy.

TyG Index Change Is More Determinant for Forecasting Type 2 Diabetes Onset Than Weight Gain

The risk of type 2 diabetes associated with obesity appears to be influenced by other metabolic abnormalities, and there is controversy about the harmless condition of the metabolically healthy obese (MHO) state. The aim of this study is to assess the risk of diabetes and the impact of changes in weight and in triglyceride-glucose index (TyG index), according to the metabolic health and obesity states.We analyzed prospective data of the Vascular Metabolic CUN cohort, a population-based study among a White European population (mean follow-up, 8.9 years). Incident diabetes was assessed in 1923 women and 3016 men with a mean age at baseline of 55.33 ± 13.68 and 53.78 ± 12.98 years old.A Cox proportional-hazard analysis was conducted to estimate the hazard ratio (HR) of diabetes on metabolically healthy nonobese (MHNO), metabolically healthy obese, metabolically unhealthy nonobese (MUNO), and metabolically unhealthy obese (MUO). A continuous standardized variable (z-score) was derived to compute the HR for diabetes per 1-SD increment in the body mass index (BMI) and the TyG index.MHO, MUNO, and MUO status were associated with the development of diabetes, HR of 2.26 (95% CI: 1.25-4.07), 3.04 (95% CI: 1.69-5.47), and 4.04 (95% CI: 2.14-7.63), respectively. MUNO individuals had 1.82 greater risk of diabetes compared to MHO subjects (95% CI: 1.04-3.22). The HRs for incident diabetes per 1-SD increment in BMI and TyG indexes were 1.23 (95% CI: 1.04-1.44) and 1.54 (95% CI: 1.40-1.68). The increase in BMI did not raise the risk of developing diabetes among metabolically unhealthy subjects, whereas increasing the TyG index significantly affect the risk in all metabolic health categories.Metabolic health is more important determinant for diabetes onset than weight gain. The increase in weight does not raise the risk of developing diabetes among metabolically unhealthy subjects.

A Nested Case-Control Study of Metabolically Defined Body Size Phenotypes and Risk of Colorectal Cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND

Obesity is positively associated with colorectal cancer. Recently, body size subtypes categorised by the prevalence of hyperinsulinaemia have been defined, and metabolically healthy overweight/obese individuals (without hyperinsulinaemia) have been suggested to be at lower risk of cardiovascular disease than their metabolically unhealthy (hyperinsulinaemic) overweight/obese counterparts. Whether similarly variable relationships exist for metabolically defined body size phenotypes and colorectal cancer risk is unknown.

METHODS AND FINDINGS

The association of metabolically defined body size phenotypes with colorectal cancer was investigated in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Metabolic health/body size phenotypes were defined according to hyperinsulinaemia status using serum concentrations of C-peptide, a marker of insulin secretion. A total of 737 incident colorectal cancer cases and 737 matched controls were divided into tertiles based on the distribution of C-peptide concentration amongst the control population, and participants were classified as metabolically healthy if below the first tertile of C-peptide and metabolically unhealthy if above the first tertile. These metabolic health definitions were then combined with body mass index (BMI) measurements to create four metabolic health/body size phenotype categories: (1) metabolically healthy/normal weight (BMI < 25 kg/m2), (2) metabolically healthy/overweight (BMI ≥ 25 kg/m2), (3) metabolically unhealthy/normal weight (BMI < 25 kg/m2), and (4) metabolically unhealthy/overweight (BMI ≥ 25 kg/m2). Additionally, in separate models, waist circumference measurements (using the International Diabetes Federation cut-points [≥80 cm for women and ≥94 cm for men]) were used (instead of BMI) to create the four metabolic health/body size phenotype categories. Statistical tests used in the analysis were all two-sided, and a p-value of <0.05 was considered statistically significant. In multivariable-adjusted conditional logistic regression models with BMI used to define adiposity, compared with metabolically healthy/normal weight individuals, we observed a higher colorectal cancer risk among metabolically unhealthy/normal weight (odds ratio [OR] = 1.59, 95% CI 1.10-2.28) and metabolically unhealthy/overweight (OR = 1.40, 95% CI 1.01-1.94) participants, but not among metabolically healthy/overweight individuals (OR = 0.96, 95% CI 0.65-1.42). Among the overweight individuals, lower colorectal cancer risk was observed for metabolically healthy/overweight individuals compared with metabolically unhealthy/overweight individuals (OR = 0.69, 95% CI 0.49-0.96). These associations were generally consistent when waist circumference was used as the measure of adiposity. To our knowledge, there is no universally accepted clinical definition for using C-peptide level as an indication of hyperinsulinaemia. Therefore, a possible limitation of our analysis was that the classification of individuals as being hyperinsulinaemic-based on their C-peptide level-was arbitrary. However, when we used quartiles or the median of C-peptide, instead of tertiles, as the cut-point of hyperinsulinaemia, a similar pattern of associations was observed.

CONCLUSIONS

These results support the idea that individuals with the metabolically healthy/overweight phenotype (with normal insulin levels) are at lower colorectal cancer risk than those with hyperinsulinaemia. The combination of anthropometric measures with metabolic parameters, such as C-peptide, may be useful for defining strata of the population at greater risk of colorectal cancer.

Normal weight dyslipidemia: Is it all about the liver?

OBJECTIVE

The liver coordinates lipid metabolism and may play a vital role in the development of dyslipidemia, even in the absence of obesity. Normal weight dyslipidemia (NWD) and patients with nonalcoholic fatty liver disease (NAFLD) who do not have obesity constitute a unique subset of individuals characterized by dyslipidemia and metabolic deterioration. This review examined the available literature on the role of the liver in dyslipidemia and the metabolic characteristics of patients with NAFLD who do not have obesity.

METHODS

PubMed was searched using the following keywords: nonobese, dyslipidemia, NAFLD, NWD, liver, and metabolically obese/unhealthy normal weight. Additionally, article bibliographies were screened, and relevant citations were retrieved. Studies were excluded if they had not measured relevant biomarkers of dyslipidemia.

RESULTS

NWD and NAFLD without obesity share a similar abnormal metabolic profile. When compared with patients with NAFLD who have obesity, the metabolic abnormalities of NAFLD without obesity are similar or less severe. Furthermore, hepatic lesions develop independent of obesity, and the extent of dyslipidemia seems comparable.

CONCLUSIONS

NAFLD may impair hepatic lipid handling, causing faulty lipid homeostasis, and serves as a likely starting point for initiation and propagation of dyslipidemia along with associated comorbidities in patients without obesity.

Association between dietary patterns and metabolic syndrome in individuals with normal weight: a cross-sectional study

Background

The results of several papers have confirmed the existence of correlations between an unhealthy diet and the presence of metabolic syndrome. However, relationships between eating habits and metabolic obesity with normal weight have not yet been sufficiently studied. The aim of the study is to determine which dietary patterns are present in individuals with a normal BMI and to find out whether those patterns were connected with the risk of metabolic syndrome and its features.

Methods

A cross-sectional study was carried out in a group of 2479 subjects with a normal weight (BMI = 18.5–24.9 kg/m²), aged between 37–66. The study included the evaluation of eating habits, anthropometric measurements, blood pressure tests and the analysis of the collected fasting-blood samples, on the basis of which cholesterol, triglycerides and glucose levels were determined. Dietary patterns were determined by means of factor analysis.

Results

In the group of individuals with a normal BMI, four dietary patterns were distinguished: “healthy”, “fat, meat and alcohol”, “prudent” and “coca cola, hard cheese and French fries”. After controlling for potential confounders, subjects in the highest tertile of prudent dietary pattern scores had a lower odds ratio for the metabolic obesity normal weight) (odds ratio: 0.69; 95 % CI: 0.53-0.89; p < 0.01) and low HDL cholesterol (odds ratio: 0.77; 95 % CI: 0.59-0.99; p < 0.05), in comparison to those from the lowest tertile, whereas the individuals in the second tertile had a higher odds ratio for the increased blood glucose concentration than those in the lowest tertile (odds ratio: 0.74; 95 % CI: 0.57-0.96; p < 0.05).

Conclusion

A dietary pattern characterized by a high consumption of fish and whole grains, and a low consumption of refined grains, sugar, sweets and cold cured meat, is connected with lower risk of metabolic obesity normal weight as well as with the lower risk of low HDL cholesterol concentration and increased glucose concentration.

A novel criterion for identifying metabolically obese but normal weight individuals using the product of triglycerides and glucose

OBJECTIVES

Metabolically obese but normal weight (MONW) individuals constitute a subgroup of normal weight individuals that display impaired insulin sensitivity with a higher risk of developing diabetes, cardiovascular disease and mortality. We aimed to propose a novel criterion for defining MONW by examining the usefulness and the cutoff value of the TyG index, a product of the levels of triglycerides and glucose, in identifying MONW individuals. In addition, the performance of this criterion in predicting the future incidence of diabetes was assessed.

SUBJECTS/METHODS

A total of 7541 non-diabetic, normal weight (body mass index ⩾18.5 and <25 kg m(-)(2)) subjects were selected from the Korea National Health and Nutrition Examination Survey conducted in 2009-2010. Another 3185 participants with follow-up studies were selected from a prospective community-based cohort study. The TyG index was calculated as ln(fasting triglycerides (mg dl(-1)) × fasting glucose (mg dl(-1))/2).

RESULTS

The levels of the TyG index paralleled the prevalence of metabolic syndrome and its components. The cutoff value of the TyG index that reflected MONW based on the receiver operating characteristics analysis was 8.82 for men and 8.73 for women, with the area under the curve values being 0.855 and 0.868, respectively. The sensitivity and the specificity were 84.2 and 77.6% in men and 69.1 and 89.4% in women, respectively. Individuals designated as MONW, who have a normal weight and TyG levels higher than cutoff, displayed a metabolically unhealthy phenotype and an approximately twofold higher risk of developing diabetes compared with metabolically healthy normal weight subjects.

CONCLUSIONS

We propose a simple diagnostic criterion of MONW, which might be used to discriminate subjects with a higher risk of metabolic diseases.

Metabolic obesity, adipocytokines, and inflammatory markers in Asian Indians--CURES-124

AIM

This study looked at the association of adipokines, inflammatory and oxidative stress markers in subjects with the following phenotypes: metabolically healthy, nonobese (MHNO), metabolically healthy, obese (MHO), metabolically obese, nonobese (MONO), and metabolically obese, obese (MOO).

MATERIALS AND METHODS

Subjects with MHNO (n=462), MHO (n=192), MONO (n=315), and MOO (n=335) were randomly selected from the Chennai Urban Rural Epidemiology Study. Adiponectin, visfatin, resistin, high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), oxidized low-density lipoprotein (LDL), and monocyte chemoattractant protein-1 (MCP-1) were measured by enzyme-linked immunosorbent assay.

RESULTS

Levels of adiponectin were lowest in the MOO group, followed by the MONO, MHO, and the MHNO groups (P=0.042), whereas the levels of visfatin (P=0.042) and resistin (P=0.043) were highest in the MOO group, followed by the MONO, MHO, and the MHNO groups. Levels of hs-CRP (P=0.029), TNF-α (P=0.036), IL-6 (P=0.042), oxidized LDL (P=0.036), and MCP-1 (P=0.039) increased from the MHNO to MHO to MONO to MOO phenotypes. Linear regression analysis of the parameters with body mass index (BMI) and metabolic syndrome components showed that adiponectin is negatively associated with abdominal obesity (β=-0.060; P=0.039) and BMI (β=-0.076; P=0.009) and that TNF-α is negatively associated with high-density lipoprotein levels (β=0.114, P=0.049) even after adjusting for age and gender. hs-CRP (β=0.112, P=0.020) and oxidized LDL (β=0.114, P=0.050) showed a positive association with systolic blood pressure even after adjusting for age and gender.

CONCLUSIONS

The metabolically obese phenotype is characterized by altered adipokine and inflammatory profiles, which could make this phenotype at high risk for type 2 diabetes mellitus and cardiovascular diseases.

Identifying subgroups of obesity using the product of triglycerides and glucose: the Korea National Health and Nutrition Examination Survey, 2008-2010

OBJECTIVE

To determine whether the TyG index, a product of the levels of triglycerides and glucose, may be a valuable marker for identifying metabolically obese but normal weight (MONW) or metabolically healthy but obese (MHO) individuals.

DESIGN AND SUBJECTS

A total of 17 029 nondiabetic subjects (7185 men and 9844 women) were selected from the Korea National Health and Nutrition Examination Survey conducted in 2008-2010. Individuals with a normal body mass index (BMI) (≥18·5 and <23 kg/m(2) ) and the highest quartile of the homoeostasis model assessment of insulin resistance (HOMA-IR) were classified as MONW. Individuals with obesity (BMI ≥25 kg/m(2) ) and the lowest quartile of HOMA-IR were classified as MHO.

MEASUREMENTS

The TyG index was calculated as ln[fasting triglycerides (mg/dl) × fasting glucose (mg/dl)/2].

RESULTS

The levels of the TyG index paralleled with various metabolic risk parameters. The index was significantly higher in the MONW group and lower in the MHO group when compared with the non-MONW group and the non-MHO group, respectively. The odds ratios (ORs) of being categorized into the MONW group were approximately fourfold higher in the highest vs lowest quartiles of the TyG index (3·999: 95% CI, 2·508-6·376 in men; 4·737: 95% CI, 3·418-6·565 in women) among normal weight subjects. Conversely, there was a stepwise decrease in the OR of being categorized into the MHO group across the TyG index quartiles among obese subjects.

CONCLUSIONS

These data highlight the value of the TyG index in discriminating those subjects with higher risks of metabolic diseases.

Obesity with metabolic abnormality is associated with the presence of carotid atherosclerosis in Korean men: a cross-sectional study

BACKGROUND

Obesity is a risk factor for cardiovascular disease, but metabolic disturbances can also lead to the development of this disease. Therefore, we investigated the associations between obesity subtype, considering both body weight and metabolic disturbances, and carotid atherosclerosis as a predictor of cardiovascular disease in Korean men.

METHODS

Data from a total of 980 men were analysed in this study. Obesity subtypes were classified as normal weight without metabolic syndrome (metabolically healthy normal weight; MHNW), obesity without metabolic syndrome (metabolically healthy, but obese; MHO), normal weight with metabolic syndrome (metabolically abnormal, but normal weight; MANW) and obesity with metabolic syndrome (metabolically abnormal obese; MAO). Carotid intima-media thickness (CIMT) and carotid plaque were assessed using a high-resolution B-mode ultrasound system. Carotid atherosclerosis was defined as a mean CIMT value >0.9 mm or the presence of carotid plaque.

RESULTS

Mean CIMT in the MAO subtype was significantly higher than that in the MHNW control group (0.790 ± 0.019 vs. 0.747 ± 0.013 mm; p < 0.001). The presence of carotid plaque was positively associated with MAO subtype [adjusted odds ratio (aOR) 1.49, 95 % confidence interval (CI) 1.02-2.16; p = 0.039], but not with MHO or MANW, compared to the MHNW control group. The MAO subtype showed a positive association with the presence of carotid atherosclerosis (aOR 1.68, 95 % CI 1.17-2.42; p = 0.006).

CONCLUSIONS

Only the MAO subtype showed a higher CIMT value and positive associations with carotid plaque and carotid atherosclerosis, but not with MHO and MANW subtypes, compared to the MHNW control. Additional prospective studies are needed to evaluate preclinical carotid atherosclerosis according to the subtypes of obesity.

Circulating Lp-PLA₂ activity correlates with oxidative stress and cytokines in overweight/obese postmenopausal women not using hormone replacement therapy

Controversy remains regarding whether there is an association between circulating lipoprotein-associated phospholipase A2 (Lp-PLA2), cytokines, and oxidative stress in healthy postmenopausal women. We investigated the influence of age on Lp-PLA2 activity in postmenopausal women not using hormone therapy and the relationship of Lp-PLA2 enzyme activity to serum cytokine levels and oxidative stress indices. Normal weight (n = 1284) and overweight/obese (n = 707) postmenopausal women not using hormone therapy were categorized into five age groups: 50-54, 55-59, 60-64, 65-69, and 70-89 years. Overweight-obese women showed higher plasma Lp-PLA2 activity, urinary 8-epi-prostaglandin F2α (8-epi-PGF2α), serum interleukin (IL)-6, and smaller LDL particles than normal-weight women after adjusting for age, years postmenopause, smoking, drinking, blood pressure, glucose, insulin, lipid profiles, BMI, and waist circumference. Overweight/obese women 70-89 years old showed higher Lp-PLA2 activity than those aged 50-54 years, whereas no significant difference in Lp-PLA2 activity existed across normal-weight female age groups. Overweight/obese women aged ≥ 65 years showed higher Lp-PLA2, oxidized LDL (ox-LDL), IL-6, and 8-epi-PGF2α than age-matched normal-weight controls. Overweight/obese women aged ≥ 70 years had higher ox-LDL levels than those aged 50-59, and overweight/obese women aged 65-89 showed higher IL-6 and 8-epi-PGF2α. There were strong positive correlations between Lp-PLA2 and ox-LDL (r = 0.385, P < 0.001), Lp-PLA2 and IL-6 (r = 0.293, P < 0.001), and ox-LDL and IL-6 (r = 0.303, P < 0.001) in overweight/obese women; however, these relationships were weak in normal-weight women. These results suggest that aging and obesity-related oxidative and inflammatory mediators are associated with Lp-PLA2 activity in overweight/obese postmenopausal women not using hormone therapy.

Molecular insights into the role of white adipose tissue in metabolically unhealthy normal weight and metabolically healthy obese individuals

Obesity is a risk factor for the development of type 2 diabetes and cardiovascular disease. However, it is now recognized that a subset of individuals have reduced cardiometabolic risk despite being obese. Paradoxically, a subset of lean individuals is reported to have high risk for cardiometabolic complications. These distinct subgroups of individuals are referred to as metabolically unhealthy normal weight (MUNW) and metabolically healthy obese (MHO). Although the clinical relevance of these subgroups remains debated, evidence shows a critical role for white adipose tissue (WAT) function in the development of these phenotypes. The goal of this review is to provide an overview of our current state of knowledge regarding the molecular and metabolic characteristics of WAT associated with MUNW and MHO. In particular, we discuss the link between different WAT depots, immune cell infiltration, and adipokine production with MUNW and MHO. Furthermore, we also highlight recent molecular insights made with genomic technologies showing that processes such as oxidative phosphorylation, branched-chain amino acid catabolism, and fatty acid β-oxidation differ between these phenotypes. This review provides evidence that WAT function is closely linked with cardiometabolic risk independent of obesity and thus contributes to the development of MUNW and MHO.

The "New Deadly Quartet" for cardiovascular disease in the 21st century: obesity, metabolic syndrome, inflammation and climate change: how does statin therapy fit into this equation?

Despite population-based improvements in cardiovascular risk factors, such as blood pressure, cholesterol and smoking, cardiovascular disease still remains the number-one cause of mortality in the United States. In 1989, Kaplan coined the term "Deadly Quartet" to represent a combination of risk factors that included upper body obesity, glucose intolerance, hypertriglyceridemia and hypertension [Kaplan in Arch Int Med 7:1514-1520, 1989]. In 2002, the third report of the National Cholesterol Education Program Adult Treatment Panel (NCEP-ATP III) essentially added low HDL-C criteria and renamed this the "metabolic syndrome." [The National Cholesterol Education Program (NCEP) in JAMA 285:2486-2497, 2001] However, often forgotten was that a pro-inflammatory state and pro-thrombotic state were also considered components of the syndrome, albeit the panel did not find enough evidence at the time to recommend routine screening for these risk factors [The National Cholesterol Education Program (NCEP) in JAMA 285:2486-2497, 2001]. Now over a decade later, it may be time to reconsider this deadly quartet by reevaluating the roles of obesity and subclinical inflammation as they relate to the metabolic syndrome. To complete this new quartet, the addition of increased exposure to elevated levels of particulate matter in the atmosphere may help elucidate why this cardiovascular pandemic continues, despite our concerted efforts. In this article, we will summarize the evidence, focusing on how statin therapy may further impact this new version of the "deadly quartet".

Association of metabolically abnormal but normal weight (MANW) and metabolically healthy but obese (MHO) individuals with arterial stiffness and carotid atherosclerosis

OBJECTIVE

Despite recent interest in differential impact of body size phenotypes on cardiovascular outcomes and mortality, studies evaluating the association between body size phenotypes and indicators of atherosclerosis are limited. This study investigated the relationship of metabolically abnormal but normal weight (MANW) and metabolically healthy but obese (MHO) individuals with arterial stiffness and carotid atherosclerosis in Korean adults without cardiovascular disease.

METHODS

A total of 1012 participants (575 men and 437 women, mean age 50.8 years), who underwent a health examination between April 2012 and May 2013 were prospectively enrolled based on inclusion and exclusion criteria. Study subjects were classified according to body mass index (BMI) and the presence/absence of metabolic syndrome.

RESULTS

The prevalence of metabolically healthy normal weight (MHNW), MANW, MHO, and metabolically abnormal obese (MAO) were 54.84%, 6.42%, 22.83%, and 15.91%, respectively. Individuals with MANW had significantly higher brachial-ankle pulse wave velocity and maximal carotid intima-media thickness values than those with MHO, after adjusting for age and gender (P = 0.026 and P = 0.018, respectively). The odds ratio (OR) of arterial stiffness and carotid atherosclerosis in the MANW group were significantly higher than in the MHNW group in unadjusted models. Furthermore, multivariable models showed that increased OR of carotid atherosclerosis in the MANW group persisted even after adjusting for confounding factors (OR = 2.98, 95% CI = [1.54, 5.73], P = 0.011).

CONCLUSIONS

Compared to MHNW or MHO subjects, Korean men and women with the MANW phenotype exhibited increased arterial stiffness and carotid atherosclerosis.

CLINICAL TRIALS NO

NCT01594710.

Association of obstructive sleep apnea and glucose metabolism in subjects with or without obesity

OBJECTIVE

The purpose of this study was to investigate whether the impact of obstructive sleep apnea (OSA) on glucose metabolism was different according to the presence or absence of obesity.

RESEARCH DESIGN AND METHODS

A total of 1,344 subjects >40 years old from the Korean Genome and Epidemiology Study were included. OSA was detected by home portable sleep monitoring. Plasma glucose, HbA1c, and insulin resistance were compared according to OSA and obesity status. The associations between OSA and impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG + IGT, and diabetes were evaluated in subjects with and without obesity after adjusting for several confounding variables. The effect of visceral obesity on this association was evaluated in 820 subjects who underwent abdominal computed tomography scanning.

RESULTS

In subjects without obesity, fasting glucose, 2-h glucose after 75-g glucose loading, and HbA1c were higher in those with OSA than in those without after controlling for age, sex, and BMI. In addition, the presence of OSA in nonobese subjects was associated with a higher prevalence of IFG + IGT and diabetes after adjusting for several confounding variables (odds ratio 3.15 [95% CI 1.44-6.90] and 2.24 [1.43-3.50] for IFG + IGT and diabetes, respectively). Further adjustment for visceral fat area did not modify this association. In contrast, in those with obesity, none of the abnormal glucose tolerance categories were associated with OSA.

CONCLUSIONS

The presence of OSA in nonobese individuals is significantly associated with impaired glucose metabolism, which can be responsible for future risk for diabetes and cardiovascular disease.

Higher mortality in metabolically obese normal-weight people than in metabolically healthy obese subjects in elderly Koreans

OBJECTIVE

The purpose of this study was to investigate the impact of body mass index (BMI) and the presence of metabolic syndrome (MetS) on all-cause and cardiovascular mortality in elderly Korean men and women, and especially to compare metabolically obese normal-weight (MONW) and metabolically healthy obese (MHO) subjects.

PATIENTS AND METHODS

A total of 2317 elderly people (over 60 years of age) were studied using follow-up data from the South-West Seoul (SWS) Study, a prospective cohort study. Mortality from all causes and cardiovascular disease (CVD) were evaluated according to the combination of the presence or absence of MetS and Asian-specific body mass index (BMI) criteria (BMI <23 kg/m²; normal weight, BMI 23-24·9 kg/m²; overweight, BMI ≥25 kg/m²; obesity).

RESULTS

During a median follow-up of 10·3 years, 393 subjects died, including 126 from CVD. Among subjects with MetS, all-cause and CVD mortality were significantly higher in normal-weight subjects than overweight or obese individuals in Cox proportional-hazard models adjusted for confounding factors. Furthermore, among six groups with various MetS/BMI combinations, MONW individuals had the highest risk, whereas overweight subjects without MetS had the lowest risk of death from all causes and CVD [HR = 2·2 (95% CI = 1·4-3·4), HR = 3·0 (95% CI = 1·4-6·6) respectively]. Interestingly, all-cause mortality was significantly higher in MONW than MHO individuals.

CONCLUSIONS

In contrast to MHO subjects, elderly individuals with the MONW phenotype exhibited greater all-cause mortality during 10 years of follow-up.

Rapid and easy assessment of insulin resistance contributes to early detection of polycystic ovary syndrome

AIMS

Polycystic ovary syndrome (PCOS) is frequently observed in women of reproductive age, and is associated with disturbances in both reproductive and metabolic function. Insulin resistance (IR) is key to the pathophysiology of PCOS, and early detection may improve outcomes in this patient group. Rapid and straightforward laboratory tests may contribute towards early detection.

METHODS

A retrospective chart review of 185 women presenting for the first time to a gynecology clinic was carried out. Of this group, 77 met the inclusion criteria. The sample was divided according to insulin sensitivity (IS) given by the Matsuda Index, and the two groups were compared using correlation analysis. Furthermore, the sensitivity and specificity of the Matsuda, homeostasis model assessment of IR (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) indexes were compared.

RESULTS

Although bodu mass index (BMI) was higher in the insulin resistant group than the insulin sensitive group, the mean age of the IR group was actually lower. HOMA-IR and QUICKI correlated well with the Matsuda index in both groups. The HOMA-IR test showed the highest sensitivity and specificity in the detection of IR when compared to the Matsuda Index, and no added benefit was derived from using a combination of both QUICKI and HOMA- 1R.

CONCLUSIONS

In a group of 77 women diagnosed with PCOS, 49 (63.6%) had IR according to the Matsuda index. The HOMA-IR index, which is based on fasting serum insulin and glucose, correlated closely with the Matsuda index, indicating it may be a reliable substitute in the detection and subsequent early intervention required to improve outcomes in PCOS.

Simvastatin inhibits ox-LDL-induced inflammatory adipokines secretion via amelioration of ER stress in 3T3-L1 adipocyte

Adipocytes behave as a rich source of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein 1 (MCP-1). Endoplasmic reticulum (ER) stress in adipocytes can alter adipokines secretion and induce inflammation. The aim of this study is to evaluate the effect of simvastatin on the ox-LDL-induced ER stress and expression and secretion of TNF-α and MCP-1 in 3T3-L1 adipocytes. Differentiated adipocytes were treated with various concentrations of ox-LDL (0-100 μg/ml) for 24h with or without simvastatin pre-treatment. The protein expressions of ER stress markers, glucose-regulated protein 78 (GRP78) and C/EBP homology protein (CHOP), were determined by Western blot analysis. The mRNA expressions of TNF-α and MCP-1 were measured by real-time PCR. The protein release of TNF-α and MCP-1 in culture medium were evaluated by ELISA. Ox-LDL treatment led to significant up-regulation of GRP78 and CHOP in dose-dependent manner. The expressions of TNF-α and MCP-1 were dose-dependently increased at mRNA and protein levels after ox-LDL intervention. The effects of ox-LDL on adipocytes were abolished by pre-treatment with 4-phenylbutyrate (4-PBA), a chemical chaperone known to ameliorate ER stress. Simvastatin could inhibit ox-LDL-induced ER stress and reduce the expression of TNF-α and MCP-1 at mRNA and protien level in dose dependent manner. In conclusion, ox-LDL can stimulate the expression and secretion of TNF-α and MCP-1 through its activation of ER stress in adipocytes. Simvastatin might exert direct anti-inflammatory effects in adipocytes through amelioration of ER stress.

Women's higher health risks in the obesogenic environment: a gender nutrition approach to metabolic dimorphism with predictive, preventive, and personalised medicine

Women's evolution for nurturing and fat accumulation, which historically yielded health and longevity advantages against scarcity, may now be counteracted by increasing risks in the obesogenic environment, recently shown by narrowing gender health gap. Women's differential metabolism/disease risks, i.e. in fat accumulation/distribution, exemplified during puberty/adolescence, suggest gender dimorphism with obesity outcomes. Women's higher body fat percentage than men, even with equal body mass index, may be a better risk predictor. Differential metabolic responses to weight-reduction diets, with women's lower abdominal fat loss, better response to high-protein vs. high-carbohydrate diets, higher risks with sedentariness vs. exercise benefits, and tendency toward delayed manifestation of central obesity, metabolic syndrome, diabetes, cardiovascular disease, and certain cancers until menopause-but accelerated thereafter-suggest a need for differing metabolic and chronological perspectives for prevention/intervention. These perspectives, including women's differential responses to lifestyle changes, strongly support further research with a gender nutrition emphasis within predictive, preventive, and personalized medicine.

Physical activity and screen time in metabolically healthy obese phenotypes in adolescents and adults

INTRODUCTION

The purpose of this study was to examine levels of physical activity (PA) and screen time (ST) in metabolically healthy obese (MHO) and metabolically unhealthy obese (MUO) adolescents and adults.

METHODS

NHANES data from obese adolescents (12-18 years, BMI z-score ≥ 95th percentile) and adults (19-85 years, BMI ≥ 30 kg/m(2)) were pooled from 2003-2005 cycles. Metabolic phenotypes were categorized as MHO (0 or 1 cardiometabolic risk factor; triglycerides, HDL-C, blood pressure, or glucose) or MUO (≥2 cardiometabolic risk factors). Logistic regression models estimated associations between phenotype and PA/ST adjusted for age, gender, BMI, race/ethnicity, menopausal status, and NHANES cycle.

RESULTS

Among adolescents, PA was not associated with MHO. In contrast, MHO adults 19-44 years were 85% more likely to engage in active transportation and 2.7 times more likely to be involved in light intensity usual daily activity versus sitting. For each minute per day, adults 45-85 years were 36% more likely to have the MHO phenotype with higher levels of moderate PA. ST was not associated with metabolic phenotypes in adolescents or adults.

CONCLUSION

The current study provides evidence that PA, but not ST, differs between MHO and MUO in adults, but not in adolescents. Future studies are needed to confirm results.

Gender-specific relationships between plasma oxidized low-density lipoprotein cholesterol, total antioxidant capacity, and central adiposity indicators

BACKGROUND

Oxidative stress has a pivotal role in the onset of obesity-related chronic diseases. This study assessed potential gender differences in the associations of adiposity (total vs. central) with oxidative stress markers in healthy young adults.

METHODS

This cross-sectional study enrolled 272 subjects (97 males, 175 females; 22 ± 3 years, body mass index 22.0 ± 2.8 kg/m(2)). Body composition, cardiometabolic and lifestyle features, oxidized low-density lipoprotein cholesterol (ox-LDL) concentrations, plasma total antioxidant capacity (TAC), and glutathione peroxidase (GPx) activity in erythrocytes were determined by validated procedures.

RESULTS

Compared to women, men had statistically higher concentrations of ox-LDL (61.7 vs. 53.5 U/l, p = 0.022). In analyses with the whole sample, those individuals included in the highest tertile of central adiposity indicators (waist circumference, WC, or waist-to-hip ratio, WHR) presented higher ox-LDL and lower TAC values (p < 0.01), while no statistical differences were found across tertiles of total body fat. WHR values were more strongly associated with ox-LDL and TAC concentrations, compared to other adiposity indicators, with higher slopes for women. Sex differences in ox-LDL concentrations were abolished (p > 0.05) after individual pairing of men and women for WC (53.8 vs. 61.6 U/l, p = 0.225) or WHR (56.1 vs. 56.3 U/l, p = 0.471). No differences were found in GPx values concerning gender or adiposity indicators.

CONCLUSIONS

Plasma ox-LDL and TAC values were more strongly influenced by central adiposity indicators (WHR and WC) in women than in men, suggesting that the change of the gynoid to android pattern phenotype among young women could lead to a steeper unfavourable redox status compared to men.

Prognostic implications for insulin-sensitive and insulin-resistant normal-weight and obese individuals from a population-based cohort

BACKGROUND

There are few prospective data on the prognosis of insulin-sensitive and insulin-resistant normal-weight (NW) or obese individuals.

OBJECTIVES

The estimated liver fat content, incidences of hyperglycemia and cardiovascular disease, and all-cause and cardiovascular mortality rates were investigated in a population-based cohort of 1658 individuals who were categorized according to BMI and insulin resistance as defined by HOMA-IR values ≥2.5 and the presence of metabolic syndrome.

DESIGN

This was a prospective cohort study with a 9-y follow-up. Anthropometric values, blood pressure, and blood metabolic variables were measured, and information on vital status was collected from demographic files at follow-up.

RESULTS

A total of 137 of 677 NW individuals (20%) were classified as insulin resistant and normal weight (IR-NW), and 72 of 330 obese individuals (22%) were classified as insulin sensitive and obese (IS-obese). Incidences of diabetes, impaired fasting glucose, and cardiovascular events were 0.4%, 6.3%, and 3.3%, respectively, in insulin-sensitive and normal-weight (IS-NW) individuals (reference category); 5.8%, 10.2%, and 6.6%, respectively, in IR-NW individuals; and 5.6%, 8.3%, and 8.3%, respectively, in IS-obese individuals. In a multiple logistic regression model, risks of incident hyperglycemia and cardiovascular events increased in both groups compared with in the reference category [HR (95% CI): 2.54 (1.42, 4.55) and 1.98 (0.86, 4.54) in IR-NW subjects; 2.16 (1.01, 4.63) and 2.76 (1.05, 7.28) in IS-obese subjects]. The estimated liver fat content significantly increased during follow-up only in the IR-NW group in the same model. Cardiovascular mortality was 2-3-fold higher in IR-NW and IS-obese than in IS-NW individuals in a Cox regression model.

CONCLUSIONS

Our data refute the existence of healthy obese phenotypes because IS-obese individuals showed increased cardiometabolic risk. The existence of unhealthy NW phenotypes is supported by their increased risk of incident hyperglycemia, fatty liver, cardiovascular events, and death.

Oxidative stress is associated with visceral adipose tissue and subclinical atherosclerosis in a healthy multi-ethnic population

Oxidative stress plays an important role in the development of atherosclerosis. Excess visceral adipose tissue (VAT) and increased carotid intima-media thickness (IMT) are risk factors for coronary artery disease. We tested the hypothesis that VAT and IMT were associated with systemic oxidative stress. Healthy men and women (n = 565) matched for ethnicity (Aboriginal, Chinese, European, and South Asian) were recruited. Plasma malondialdehyde, a biomarker of oxidative stress, was measured as thiobarbituric acid reactive substances (TBARS). VAT and IMT were determined by computerized tomography and ultrasound scans, respectively. Plasma TBARS levels correlated with VAT and total atheroma burden (sum of IMT area and plaque area) in the entire cohort. When stratified by ethnicity, plasma TBARS levels correlated with distinct body composition and arterial measures in different ethnic populations with more associations present amongst Chinese and Europeans relative to Aboriginals and South Asians. VAT was associated with plasma TBARS levels independent of age, sex, ethnicity, smoking, and body mass index. Plasma TBARS levels were associated with IMT, the presence of plaques, and total atheroma burden, independent of age, sex, ethnicity, smoking, body mass index, and VAT. The association with total atheroma burden remained significant even when adjusted for apolipoprotein B. Results from the present study indicate that oxidative stress is positively associated with VAT as well as diffuse and focal carotid atherosclerosis in apparently healthy men and women.

Does inflammation determine whether obesity is metabolically healthy or unhealthy? The aging perspective

Obesity is a major health issue in developed as well as developing countries. While obesity is associated with relatively good health status in some individuals, it may become a health issue for others. Obesity in the context of inflammation has been studied extensively. However, whether obesity in its various forms has the same adverse effects is a matter of debate and requires further research. During its natural history, metabolically healthy obesity (MHO) converts into metabolically unhealthy obesity (MUHO). What causes this transition to occur and what is the role of obesity-related mediators of inflammation during this transition is discussed in this paper.