The Relationship of Omental and Subcutaneous Adipocyte Size to Metabolic Disease in Severe Obesity

Objective

Several studies have reported the existence of a subgroup of obese individuals with normal metabolic profiles. It remains unclear what factors are responsible for this phenomenon. We proposed that adipocyte size might be a key factor in the protection of metabolically healthy obese (MHO) individuals from the adverse effects of obesity.

Subjects

Thirty-five patients undergoing bariatric surgery were classified as MHO (n = 15) or metabolically unhealthy obese (MUO, n = 20) according to cut-off points adapted from the International Diabetes Federation definition of the metabolic syndrome. Median body mass index (BMI) was 48 (range 40–71).

Results

There was a moderate correlation between omental adipocyte size and subcutaneous adipocyte size (r = 0.59, p<0.05). The MHO group had significantly lower mean omental adipocyte size (80.9±10.9 µm) when compared with metabolically unhealthy patients (100.0±7.6 µm, p<0.0001). Mean subcutaneous adipocyte size was similar between the two groups (104.1±8.5 µm versus 107.9±7.1 µm). Omental, but not subcutaneous adipocyte size, correlated with the degree of insulin resistance as measured by HOMA-IR (r = 0.73, p<0.0005), as well as other metabolic parameters including triglyceride/HDL-cholesterol ratio and HbA1c. Twenty-eight patients consented to liver biopsy. Of these, 46% had steatohepatitis and fibrosis. Fifty percent (including all the MHO patients) had steatosis only. Both omental and subcutaneous adipocyte size were significantly associated with the degree of steatosis (r = 0.66, p<0.0001 and r = 0.63, p<0.005 respectively). However, only omental adipocyte size was an independent predictor of the presence or absence of fibrosis.

Conclusion

Metabolically healthy individuals are a distinct subgroup of the severely obese. Both subcutaneous and omental adipocyte size correlated positively with the degree of fatty liver, but only omental adipocyte size was related to metabolic health, and possibly progression from hepatic steatosis to fibrosis.     

Interventions to Reduce and Prevent Obesity in Pre-Conceptual and Pregnant Women: A Systematic Review and Meta-Analysis

Background

The increasing prevalence of obesity in pregnant women is associated with adverse maternal and neonatal outcomes, and increased costs to healthcare, the economy and broader society.

Objectives

To assess the efficacy of behavioural interventions for managing gestational weight gain (GWG) in the pre-conceptual and pregnancy period in overweight, obese and morbidly obese women.

Search Methods

A search was performed for published studies in the English language, from date? 2000–31 December 2012 in five electronic databases; PubMed, Scopus, Cochrane Library, CINAHL and PsycINFO.

Selection criteria

Studies were included if they compared the efficacy or effectiveness of a particular behavioural intervention in pregnant or pre-conceptual women with standard maternity care. Studies that included women with co-morbid conditions such as diabetes mellitus and polycystic ovarian syndrome were excluded to help isolate the effect of the intervention.

Results

Fifteen studies involving 3,426 participants were included. One study (n = 692) focused on the pre-conceptual period and the remaining 14 (n = 2,734) in the pregnancy period. Pooled mean difference for GWG indicated a lower GWG in the intervention groups when compared to standard maternity care groups (n = 1771, mean difference (MD) −1.66 kg, 95% CI −3.12 to −0.21 kg). With respect to the types of participants, considerable heterogeneity between studies was shown in the obese subgroup [Tau² = 15.61; Chi² = 40.80, df = 3 (P<0.00001); I² = 93%].

Conclusions

Behavioural interventions in pregnancy may be effective in reducing GWG in obese women without comorbid conditions, but not overweight or morbidly obese women. Behavioural interventions had no effect on postpartum weight loss or retention, gestation week of delivery and infant birth weight in overweight, obese and morbidly obese women.     

Serum Glycine Is Associated with Regional Body Fat and Insulin Resistance in Functionally-Limited Older Adults

Background

Metabolic profiling may provide insight into biologic mechanisms related to age-related increases in regional adiposity and insulin resistance.

Objectives

The objectives of the current study were to characterize the association between mid-thigh intermuscular and subcutaneous adipose tissue (IMAT, SCAT, respectively) and, abdominal adiposity with the serum metabolite profile, to identify significant metabolites as further associated with the homeostasis model assessment of insulin resistance (HOMA-IR), and, to develop a HOMA-IR associated metabolite predictor set representative of regional adiposity, in 73 functionally-limited (short physical performance battery ≤10; SPPB) older adults (age range, 70–85 y).

Methods

Fasting levels of 181 total metabolites, including amino acids, fatty acids and acylcarnitines were measured with use of an untargeted mass spectrometry-based metabolomic approach. Multivariable-adjusted linear regression was used in all analyses.

Results

Thirty-two, seven and one metabolite(s) were found to be associated with IMAT, abdominal adiposity and, SCAT, respectively, including the amino acid glycine, which was positively associated with SCAT and, negatively associated with both IMAT and abdominal adiposity. Glycine and four metabolites found to be significantly associated with regional adiposity were additionally associated with HOMA-IR. Separate stepwise regression models identified glycine as a HOMA-IR associated marker of both IMAT (model R² = 0.51, p<0.0001) and abdominal adiposity (model R² = 0.41, p<0.0001).

Conclusion

Our findings for a positive association between glycine with SCAT but, a negative association between glycine with IMAT and abdominal adiposity supports the hypothesis that SCAT metabolic processes are different from that found in other fat depots. In addition, because of the significant associations found between glycine with HOMA-IR, IMAT, SCAT and abdominal adiposity, our results suggest glycine as a serum biomarker of both insulin sensitivity and regional fat mass in functionally-limited older adults.     

Low Vitamin D Status Is Associated with Nonalcoholic Fatty Liver Disease Independent of Visceral Obesity in Korean Adults

Objective

To investigate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and nonalcoholic fatty liver disease (NAFLD) independent of visceral obesity in Koreans and to examine whether the associations differ according to the presence of diabetes or insulin resistance.

Research Design and Methods

A total of 1081 adults were enrolled from a population-based cohort in Ansan city. Serum 25(OH)D concentrations were measured in all subjects. Insulin resistance was measured by homeostasis model assessment of insulin resistance (HOMA-IR). Using computed tomography, NAFLD was diagnosed if the liver attenuation index (LAI, the difference between the mean hepatic and splenic attenuation) was <5 Hounsfield Units.

Results

In subjects with diabetes (n = 282), 25(OH)D levels were negatively associated with waist circumference, fasting insulin, HOMA-IR, triglyceride levels, and visceral abdominal fat, and were positively associated with LAI after adjusting for age, sex, season, exercise, and vitamin supplementation. In subjects without diabetes, only triglyceride level was negatively associated with 25(OH)D. The adjusted odds ratio (OR) for NAFLD increased sequentially across decreasing quartiles of 25(OH)D in subjects with diabetes even after adjusting for visceral fat [Q1 vs. Q4; OR for NAFLD 2.5 (95% CI:1.0–6.2)]. In contrast, no significant difference in OR was observed in subjects without diabetes. When we classified non-diabetic subjects by HOMA-IR, an increase in the OR for NAFLD across decreasing quartiles of 25(OH)D was observed in the high HOMA-IR (≥2.5) group [n = 207, Q1 vs. Q4; OR 3.8(1.4–10.3)], but not in the low HOMA-IR (<2.5) group [n = 592, OR 0.8 (0.3–1.9)].

Conclusions

Low vitamin D status is closely associated with NAFLD, independent of visceral obesity in subjects with diabetes or insulin resistance.     

Causal Relationship between Adiponectin and Metabolic Traits: A Mendelian Randomization Study in a Multiethnic Population

Background

Adiponectin, a secretagogue exclusively produced by adipocytes, has been associated with metabolic features, but its role in the development of the metabolic syndrome remains unclear.

Objectives

We investigated the association between serum adiponectin level and metabolic traits, using both observational and genetic epidemiologic approaches in a multiethnic population assembled in Canada.

Methods

Clinical data and serum adiponectin level were collected in 1,157 participants of the SHARE/SHARE-AP studies. Participants were genotyped for the functional rs266729 and rs1260326 SNPs in ADIPOQ and GCKR genes.

Results

Adiponectin level was positively associated with HDL cholesterol and negatively associated with body mass index, waist-to-hip ratio, triglycerides, fasting glucose, fasting insulin, systolic and diastolic pressure (all P<0.002). The rs266729 minor G allele was associated with lower adiponectin and higher HOMA-IR (P = 0.004 and 0.003, respectively). The association between rs266729 SNP and HOMA-IR was no longer significant after adjustment for adiponectin concentration (P = 0.10). The rs266729 SNP was associated with HOMA-IR to an extent that exceeded its effect on adiponectin level (0.15 SD 95% C.I. [0.06, 0.24], P<0.001). There was no significant interaction between rs266729 SNP and ethnicity on adiponectin or HOMA-IR. In contrast, the SNP rs1260326 in GCKR was associated with HOMA-IR (P<0.001), but not with adiponectin level (P = 0.67).

Conclusion

The association of the functional promoter polymorphism rs266729 with lower serum adiponectin and increased insulin resistance in diverse ethnic groups may suggest a causal relationship between adiponectin level and insulin resistance.     

Polyunsaturated Fatty Acids Modulate the Association between PIK3CA-KCNMB3 Genetic Variants and Insulin Resistance

Background

Neighboring genes PIK3CA and KCNMB3 are both important for insulin signaling and β-cell function, but their associations with glucose-related traits are unclear.

Objective

The objective was to examine associations of PIK3CA-KCNMB3 variants with glucose-related traits and potential interaction with dietary fat.

Design

We first investigated genetic associations and their modulation by dietary fat in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study (n = 820). Nine single-nucleotide polymorphisms (SNPs) were selected for analysis, covering more than 80% of the SNPs in the region. We then sought to replicate the findings in the Boston Puerto Rican Health Study (BPRHS) (n = 844).

Results

For KCNMB3 missense mutation rs7645550, meta-analysis indicated that homeostasis model assessment of insulin resistance (HOMA-IR) was significantly lower in minor allele T homozygotes compared with major allele C carriers (pooled P-value = 0.004); for another SNP rs1183319, which is in moderate LD with rs7645550, minor allele G carriers had higher HOMA-IR compared with non-carriers in both populations (pooled P-value = 0.028). In GOLDN, rs7645550 T allele homozygotes had lower HOMA-IR only when dietary n-3: n-6 PUFA ratio was low (≤0.11, P = 0.001), but not when it was high (>0.11, P-interaction = 0.033). Similar interaction was observed between rs1183319 and n-3: n-6 PUFA ratio on HOMA-IR (P-interaction = 0.001) in GOLDN. Variance contribution analyses in GOLDN confirmed the genetic association and gene-diet interaction. In BPRHS, dietary n-3: n-6 PUFA ratio significantly modulated the association between rs1183319 and HbA1c (P-interaction = 0.034).

Conclusion

PIK3CA-KCNMB3 variants are associated with insulin resistance in populations of different ancestries, and are modified by dietary PUFA.     

Metabolic Signatures of Cultured Human Adipocytes from Metabolically Healthy versus Unhealthy Obese Individuals

Background and Aims

Among obese subjects, metabolically healthy and unhealthy obesity (MHO/MUHO) can be differentiated: the latter is characterized by whole-body insulin resistance, hepatic steatosis, and subclinical inflammation. Aim of this study was, to identify adipocyte-specific metabolic signatures and functional biomarkers for MHO versus MUHO.

Methods

10 insulin-resistant (IR) vs. 10 insulin-sensitive (IS) non-diabetic morbidly obese (BMI >40 kg/m²) Caucasians were matched for gender, age, BMI, and percentage of body fat. From subcutaneous fat biopsies, primary preadipocytes were isolated and differentiated to adipocytes in vitro. About 280 metabolites were investigated by a targeted metabolomic approach intracellularly, extracellularly, and in plasma.

Results/Interpretation

Among others, aspartate was reduced intracellularly to one third (p = 0.0039) in IR adipocytes, pointing to a relative depletion of citric acid cycle metabolites or reduced aspartate uptake in MUHO. Other amino acids, already known to correlate with diabetes and/or obesity, were identified to differ between MUHO''s and MHO''s adipocytes, namely glutamine, histidine, and spermidine. Most species of phosphatidylcholines (PCs) were lower in MUHO''s extracellular milieu, though simultaneously elevated intracellularly, e.g., PC aa C32∶3, pointing to increased PC synthesis and/or reduced PC release. Furthermore, altered arachidonic acid (AA) metabolism was found: 15(S)-HETE (15-hydroxy-eicosatetraenoic acid; 0 vs. 120pM; p = 0.0014), AA (1.5-fold; p = 0.0055) and docosahexaenoic acid (DHA, C22∶6; 2-fold; p = 0.0033) were higher in MUHO. This emphasizes a direct contribution of adipocytes to local adipose tissue inflammation. Elevated DHA, as an inhibitor of prostaglandin synthesis, might be a hint for counter-regulatory mechanisms in MUHO.

Conclusion/Interpretation

We identified adipocyte-inherent metabolic alterations discriminating between MHO and MUHO.     

Cranialization of the Frontal Sinus for Secondary Mucocele Prevention following Open Surgery for Benign Frontal Lesions

Objective

To compare frontal sinus cranialization to obliteration for future prevention of secondary mucocele formation following open surgery for benign lesions of the frontal sinus.

Study Design

Retrospective case series.

Setting

Tertiary academic medical center.

Patients

Sixty-nine patients operated for benign frontal sinus pathology between 1994 and 2011.

Interventions

Open excision of benign frontal sinus pathology followed by either frontal obliteration (n = 41, 59%) or frontal cranialization (n = 28, 41%).

Main Outcome Measures

The prevalence of post-surgical complications and secondary mucocele formation were compiled.

Results

Pathologies included osteoma (n = 34, 49%), mucocele (n = 27, 39%), fibrous dysplasia (n = 6, 9%), and encephalocele (n = 2, 3%). Complications included skin infections (n = 6), postoperative cutaneous fistula (n = 1), telecanthus (n = 4), diplopia (n = 3), nasal deformity (n = 2) and epiphora (n = 1). None of the patients suffered from postoperative CSF leak, meningitis or pneumocephalus. Six patients, all of whom had previously undergone frontal sinus obliteration, required revision surgery due to secondary mucocele formation. Statistical analysis using non-inferiority test reveal that cranialization of the frontal sinus is non-inferior to obliteration for preventing secondary mucocele formation (P<0.0001).

Conclusion

Cranialization of the frontal sinus appears to be a good option for prevention of secondary mucocele development after open excision of benign frontal sinus lesions.     

Serum Retinol-Binding Protein 4 as a Marker for Cardiovascular Disease in Women

Background

Elevated serum level of retinol-binding protein 4 (RBP4) has been associated with obesity-related co-morbidities including insulin resistance, dyslipidemia and hypertension.

Objectives

The present study examined the relationship between serum level of RBP4 and various risk factors related to cardiovascular disease (CVD) in men and women.

Methods

284 subjects (139 males, 145 females), grouped into healthy (n = 60), obese diabetes (n = 60), non-obese diabetes (n = 60), obese non-diabetes (n = 60) and patients with CVD (n = 44), were assessed for anthropometric and biochemical parameters related to obesity, diabetes and CVD. In addition, serum levels of several adipokines, including fatty acid binding protein 4 (FABP4) and lipocalin 2 (LCN2) and RBP4 were measured using specific immunoassays.

Results

Serum RBP4 level correlated significantly with principal component derived from known risk factors of CVD (β = 0.20±0.06, P = 0.002). Significance of this correlation was limited to women (β = 0.20±0.06, P = 0.002) and it persisted even after adjusting for BMI (β = 0.19±0.06, P = 0.002). Overall (n = 284) serum RBP4 values significantly correlated with FABP4 (R = 0.19, p = 0.001). Serum FABP4 level of CVD subjects was significantly higher than healthy control (P = 0.001) and non-obese diabetes (P = 0.04) groups, but this difference was attributable to differences in BMI. Serum LCN2 level correlated well with RBP4 (R = 0.15, P = 0.008) and FABP4 (R = 0.36, P<0.001), but did not differ significantly between CVD and other groups.

Conclusions

Results of this study indicate a significant correlation between serum RBP4 and various established risk factors for CVD and suggest RBP4 may serve as an independent predictor of CVD in women.     

Twenty-Four Hour Total and Dietary Fat Oxidation in Lean,Obese and Reduced-Obese Adults with and without a Bout of Exercise

Background

It has been hypothesized that obese and reduced-obese individuals have decreased oxidative capacity, which contributes to weight gain and regain. Recent data have challenged this concept.

Objective

To determine (1) whether total and dietary fat oxidation are decreased in obese and reduced-obese adults compared to lean but increase in response to an acute exercise bout and (2) whether regular physical activity attenuates these metabolic alterations.

Design

We measured 24-hr total (whole-room calorimetry) and dietary fat (¹⁴C-oleate) oxidation in Sedentary Lean (BMI = 21.5±1.6; n = 10), Sedentary Obese (BMI = 33.6±2.5; n = 9), Sedentary Reduced-Obese (RED-SED; BMI = 26.9±3.7; n = 7) and in Physically Active Reduced-Obese (RED-EX; BMI = 27.3±2.8; n = 12) men and women with or without an acute exercise bout where energy expended during exercise was not replaced.

Results

Although Red-SED and Red-EX had a similar level of fatness, aerobic capacity and metabolic profiles were better in Red-EX only compared to Obese subjects. No significant between-group differences were seen in 24-hr respiratory quotient (RQ, Lean: 0.831±0.044, Obese: 0.852±0.023, Red-SED: 0.864±0.037, Red-EX: 0.842±0.039), total and dietary fat oxidation. A single bout of exercise increased total (+27.8%, p<0.0001) and dietary (+6.6%, p = 0.048) fat oxidation across groups. Although exercise did not impact RQ during the day, it decreased RQ during sleep (p = 0.01) in all groups. Red-EX oxidized more fat overnight than Red-SED subjects under both resting (p = 0.036) and negative energy balance (p = 0.003) conditions, even after adjustment for fat-free mass.

Conclusion

Obese and reduced-obese individuals oxidize as much fat as lean both under eucaloric and negative energy balance conditions, which does not support the hypothesis of reduced oxidative capacity in these groups. Reduced-obese individuals who exercise regularly have markers of metabolic health similar to those seen in lean adults. Both the acute and chronic effects of exercise were primarily observed at night suggesting an important role of sleep in the regulation of lipid metabolism.     

Influence of Body Mass Index (BMI) on Functional Improvements at 3 Years Following Total Knee Replacement: A Retrospective Cohort Study

Background

The number of patients presenting for total knee replacement who are classified as obese is increasing. The functional benefits of performing TKR in these patients are unclear.

Aim

To assess the influence pre-operative body mass index has upon knee specific function, general health status and patient satisfaction at 3 years following total knee replacement.

Design

Retrospective comparative cohort study using prospectively collected data from an institutional arthroplasty register.

Methods

1367 patients were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Medical Outcomes Trust Short Form-36 (SF-36) scores supplemented by a validated measure of satisfaction pre-operatively and subsequently at 1,2 and 3 year post-operatively. Comparisons were made by dividing the cohort into 4 groups based on body mass index (BMI) 18.5–25.0 kg/m² (n = 253);>25.0–30.0 kg/m² (n = 559);>30.0−35.0 kg/m² (n = 373);>35.0 kg/m² (n = 182).

Results

Despite lower pre-operative, 1 and 3 year WOMAC and SF-36 scores patients with the highest BMIs >35.0 kg/m² experienced similar improvements to patients with a ‘normal‘ BMI (18.5–25.0 kg/m²) at 1 year (Difference in WOMAC improvement = 0.0 (95%CI −5.2 to 5.2), p = 1.00) and this improvement was sustained at up to 3 years (Difference in 1 year to 3 year improvement = 2.2 (95%CI: −2.1 to 6.5), p = 1.00). This effect was also observed for the SF-36 mental and physical component scores. Despite equivalent functional improvements levels of satisfaction in the >35.0 kg/m² group were lower than for any other BMI group (>35.0 kg/m² = 84.6% satisfied versus 18.5–5.0 kg/m² = 93.3% satisfied,p = 0.01) as was the proportion of patients who stated they would have the operation again (>35.0 kg/m² = 69.6% versus 18.5–25.0 kg/m² = 82.2%,p = 0.01).

Conclusion

Obese and morbidly obese patients gain as much functional benefit from total knee replacement as patients with lesser body mass indexes. This benefit is maintained for up to 3 years following surgery. However, these patients are less satisfied with their knee replacement and almost a third would not have the operation again.     

Multidisciplinary Team-Based Approach for Comprehensive Preoperative Pulmonary Rehabilitation Including Intensive Nutritional Support for Lung Cancer Patients

Background

To decrease the risk of postoperative complication, improving general and pulmonary conditioning preoperatively should be considered essential for patients scheduled to undergo lung surgery.

Objective

The aim of this study is to develop a short-term beneficial program of preoperative pulmonary rehabilitation for lung cancer patients.

Methods

From June 2009, comprehensive preoperative pulmonary rehabilitation (CHPR) including intensive nutritional support was performed prospectively using a multidisciplinary team-based approach. Postoperative complication rate and the transitions of pulmonary function in CHPR were compared with historical data of conventional preoperative pulmonary rehabilitation (CVPR) conducted since June 2006. The study population was limited to patients who underwent standard lobectomy.

Results

Postoperative complication rate in the CVPR (n = 29) and CHPR (n = 21) were 48.3% and 28.6% (p = 0.2428), respectively. Those in patients with Charlson Comorbidity Index scores ≥2 were 68.8% (n = 16) and 27.3% (n = 11), respectively (p = 0.0341) and those in patients with preoperative risk score in Estimation of Physiologic Ability and Surgical Stress scores >0.3 were 57.9% (n = 19) and 21.4% (n = 14), respectively (p = 0.0362). Vital capacities of pre- and post intervention before surgery in the CHPR group were 2.63±0.65 L and 2.75±0.63 L (p = 0.0043), respectively; however, their transition in the CVPR group was not statistically significant (p = 0.6815). Forced expiratory volumes in one second of pre- and post intervention before surgery in the CHPR group were 1.73±0.46 L and 1.87±0.46 L (p = 0.0012), respectively; however, their transition in the CVPR group was not statistically significant (p = 0.6424).

Conclusions

CHPR appeared to be a beneficial and effective short-term preoperative rehabilitation protocol, especially in patients with poor preoperative conditions.     

Associations between Serum Apelin-12 Levels and Obesity-Related Markers in Chinese Children

Objective

To investigate possible correlations between apelin-12 levels and obesity in children in China and associations between apelin-12 and obesity-related markers, including lipids, insulin sensitivity and insulin resistance index (HOMA-IR).

Methods

Forty-eight obese and forty non-obese age- and gender-matched Chinese children were enrolled between June 2008 and June 2009. Mean age was 10.42±2.03 and 10.86±2.23 years in obesity and control groups, respectively. Main outcome measures were apelin-12, BMI, lipids, glucose and insulin. HOMA-IR was calculated for all subjects.

Results

All obesity group subjects had significantly higher total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), insulin levels and HOMA-IR (all P<0.05). In separate analyses, obese girls had significantly higher LDL-C, insulin and HOMA-IR than controls, and obese boys had significantly higher TC, TG, insulin and HOMA-IR than controls (all P<0.05). Apelin-12 levels were significantly higher in obese girls compared to controls (P = 0.024), and correlated positively with TG in all obese subjects. Among obese girls, apelin-12 levels correlated positively with TG, insulin and HOMA-IR after adjusting for age and BMI. In all boys (obese and controls) apelin-12 was positively associated with fasting plasma glucose (FPG). No significant correlations were found in either group between apelin-12 levels and other characteristics after adjusting for age, sex, and BMI.

Conclusions

Apelin-12 levels are significantly higher in obese vs. non-obese girls in China and correlate significantly with obesity-related markers insulin, HOMA-IR, and TG. Increased apelin-12 levels may be involved in the pathological mechanism of childhood obesity.     

An Interaction between a FNDC5 Variant and Obesity Modulates Glucose Metabolism in a Chinese Han Population

Background

To investigate the impact of common variants of FNDC5 on type 2 diabetes and clinical traits related to glucose metabolism in a large Chinese population sample.

Methods

Three tagging single nucleotide polymorphisms within the region of the FNDC5 gene were selected and genotyped in 6822 participants. Detailed clinical investigations and biochemistry measurements were carried out in all of the participants. Subjects without diabetes were classified into normal weight and overweight/obese subgroups according to body mass index (BMI).

Results

None of the SNPs were associated with either the risk of type 2 diabetes in all of the participants or with any of the clinical quantitative traits in the controls with normal glucose regulation. Subgroup analysis showed that in controls with normal weight (BMI <25 kg/m²), the rs16835198 major allele G was significantly associated with fasting insulin levels, and that each additional copy of the allele resulted in a 0.0178 mU/L increment of the values (p = 0.046). Moreover, after adjusting for confounding variables, there were trends towards correlation of rs16835198 with HOMA-insulin resistance (HOMA-IR) (p = 0.057) and low-density lipoprotein cholesterol (LDL-C) levels (p = 0.083). In overweight/obese subjects (BMI ≥25 Kg/m²), we noted rs16835198 showed trends towards association with fasting insulin (p = 0.057) and HOMA-IR levels (p = 0.091), both of which declined with additional copies of the major allele G. Moreover, rs16835198 was significantly associated with high-density lipoprotein cholesterol (HDL-C) levels (p = 0.013), and HOMA-β cell function (p = 0.028) in the overweight/obese subjects. Finally, we observed a significant interaction between BMI-rs16835198 and fasting insulin levels in the control group (p = 0.003).

Conclusions

Our data indicate that the effect of the common FNDC5 SNP rs16835198 on fasting insulin was significantly modified by BMI in the Chinese Han population.     

Common Genetic Variants of Surfactant Protein-D (SP-D) Are Associated with Type 2 Diabetes

Context

Surfactant protein-D (SP-D) is a primordial component of the innate immune system intrinsically linked to metabolic pathways. We aimed to study the association of single nucleotide polymorphisms (SNPs) affecting SP-D with insulin resistance and type 2 diabetes (T2D).

Research Design and Methods

We evaluated a common genetic variant located in the SP-D coding region (rs721917, Met³¹Thr) in a sample of T2D patients and non-diabetic controls (n = 2,711). In a subset of subjects (n = 1,062), this SNP was analyzed in association with circulating SP-D concentrations, insulin resistance, and T2D. This SNP and others were also screened in the publicly available Genome Wide Association (GWA) database of the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC).

Results

We found the significant association of rs721917 with circulating SP-D, parameters of insulin resistance and T2D. Indeed, G carriers showed decreased circulating SP-D (p = 0.004), decreased fasting glucose (p = 0.0002), glycated hemoglobin (p = 0.0005), and 33% (p = 0.002) lower prevalence of T2D, estimated under a dominant model, especially among women. Interestingly, these differences remained significant after controlling for origin, age, gender, and circulating SP-D. Moreover, this SNP and others within the SP-D genomic region (i.e. rs10887344) were significantly associated with quantitative measures of glucose homeostasis, insulin sensitivity, and T2D, according to GWAS datasets from MAGIC.

Conclusions

SP-D gene polymorphisms are associated with insulin resistance and T2D. These associations are independent of circulating SP-D concentrations.     

Acute Post-Bariatric Surgery Increase in Orexin Levels Associates with Preferential Lipid Profile Improvement

Context

Orexin is a recently identified neuropeptide hormone.

Objectives

Acute and long-term post-bariatric changes in Orexin and relationship to post-operative metabolic outcomes.

Design and Participants

Men and women undergoing biliopancreatic diversion with duodenal switch bariatric surgery (n = 76, BMI≥35 kg/m²) were evaluated for body composition and plasma parameters at baseline, acutely (1 and 5 days) and long-term (6 and 12 months) post-surgery.

Setting

University Hospital Centre, Canada.

Interventions and Main Outcome Measures

Groups were subdivided based on acute (average 1 and 5 day) changes in Orexin prior to weight loss: (i)>10% Orexin decrease (n = 33, Orexin_DEC) and (ii)>10% Orexin increase (n = 20, Orexin_INC), to evaluate impact on long-term changes.

Results

Both groups had comparable preoperative Orexin levels, BMI, age, sex distribution, diabetes and lipid lowering medication, plasma glucose and lipid parameters except for apolipoproteinB (p<0.007). Orexin increase was rapid and maintained throughout one year, while Orexin_DEC subjects remained significantly lower throughout. Over 12 months, changes in BMI, fat mass, and %fat mass were comparable. Fasting glucose and insulin increased immediately 1-day post-operatively, decreasing rapidly (5-day) and declining thereafter with the Orexin_INC group remaining lower than the Orexin_DEC group throughout (p = 0.001). Similarly, plasma cholesterol, triglyceride, LDL-C and HDL-C decreased at 1-day, increased slightly (5-day), except HDL-C, then decreased over 1 year, with greater decreases in Orexin_INC group relative to Orexin_DEC group.

Conclusion

Rapid postoperative increases in plasma Orexin are associated with better improvement of glucose and lipid profiles following bariatric surgery.     

T Regulatory Lymphocytes and Endothelial Function in Pediatric Obstructive Sleep Apnea

Background

Obstructive sleep apnea (OSA) is a low-grade inflammatory disease affecting the cardiovascular and metabolic systems. Increasing OSA severity reduces T-regulatory lymphocytes (Tregs) in OSA children. Since Tregs modulate endothelial activation, and attenuate insulin resistance, we hypothesized that Tregs are associated with endothelial and metabolic dysfunction in pediatric OSA.

Methods

50 consecutively recruited children (ages 4.8–12 years) underwent overnight polysomnography and fasting homeostatic model (HOMA) of insulin resistance was assessed. Percentage of Tregs using flow cytometry, and endothelial function, expressed as the time to peak occlusive hyperemia (Tmax), were examined. In a subgroup of children (n = 21), in vitro Treg suppression tests were performed.

Results

Circulating Tregs were not significantly associated with either BMI z score or HOMA. However, a significant inverse correlation between percentage of Tregs and Tmax emerged (p<0.0001, r = −0.56). A significant negative correlation between Tregs suppression and the sleep pressure score (SPS), a surrogate measure of sleep fragmentation emerged (p = 0.02, r = −0.51) emerged, but was not present with AHI.

Conclusions

Endothelial function, but not insulin resistance, in OSA children is strongly associated with circulating Tregs and their suppressive function, and appears to correlate with sleep fragmentation. Thus, alterations in T cell lymphocytes may contribute to cardiovascular morbidity in pediatric OSA.     

Distinct Patterns of the Lipid Alterations between Genotype 1 and 2 Chronic Hepatitis C Patients after Viral Clearance

Background

The hepatitis C virus (HCV) genotype-specific impacts on the host metabolic alterations remained inconclusive.

Methods

A prospective study including 229 (118 genotype 1 (G1) and 111 G2) consecutive chronic HCV patients who had completed a course of anti-HCV treatment and underwent pre- and 24 weeks post-treatment surveys of metabolic profiles was conducted. Patients were stratified according to the therapeutic response, viral genotype and baseline insulin resistance (IR: homeostasis model assessments of IR (HOMA-IR) ≥2.5). Paired t-tests were used to compare the pre- and post-treatment variables.

Results

Significant post-therapeutic increases in cholesterol, triglyceride, HDL, LDL, apolipoprotein A1 and apolipoprotein B were observed in patients with sustained virological response (SVR) but not in those without. Among those with SVR, post-therapeutic increases in HDL (p<0.001) and apolipoprotein A1 (p = 0.012) were only found in G2, whereas increased triglyceride/HDL (p = 0.01) ratios were only found in G1 patients. When stratified by baseline IR among those with SVR, a significant increase in post-treatment HDL (p = 0.019) and apolipoprotein A1 (p = 0.012) but a decrease in HOMA-IR (p = 0.04), C-peptide (p = 0.019) and hemoglobin A1c (p = 0.047) were found in patients with baseline IR; a significant increase in HOMA-IR (p = 0.002) was found in patients without baseline IR. The latter change was observed only in G1 (p = 0.01) but not G2 patients. Although the pre-treatment metabolic profiles of G1 and G2 patients were indifferent, G1 had higher post-treatment triglyceride/HDL ratios (p = 0.041) and triglyceride (p = 0.044) levels than G2 patients.

Conclusions

G2 benefit more than G1 patients from viral clearance in metabolic alterations, particularly in those without baseline IR.     

Zinc-alpha 2-glycoprotein gene expression in adipose tissue is related with insulin resistance and lipolytic genes in morbidly obese patients

Objective

Zinc-α₂ glycoprotein (ZAG) stimulates lipid loss by adipocytes and may be involved in the regulation of adipose tissue metabolism. However, to date no studies have been made in the most extreme of obesity. The aims of this study are to analyze ZAG expression levels in adipose tissue from morbidly obese patients, and their relationship with lipogenic and lipolytic genes and with insulin resistance (IR).

Methods

mRNA expression levels of PPARγ, IRS-1, IRS-2, lipogenic and lipolytic genes and ZAG were quantified in visceral (VAT) and subcutaneous adipose tissue (SAT) of 25 nondiabetic morbidly obese patients, 11 with low IR and 14 with high IR. Plasma ZAG was also analyzed.

Results

The morbidly obese patients with low IR had a higher VAT ZAG expression as compared with the patients with high IR (p = 0.023). In the patients with low IR, the VAT ZAG expression was greater than that in SAT (p = 0.009). ZAG expression correlated between SAT and VAT (r = 0.709, p<0.001). VAT ZAG expression was mainly predicted by insulin, HOMA-IR, plasma adiponectin and expression of adiponectin and ACSS2. SAT ZAG expression was only predicted by expression of ATGL.

Conclusions

ZAG could be involved in modulating lipid metabolism in adipose tissue and is associated with insulin resistance. These findings suggest that ZAG may be a useful target in obesity and related disorders, such as diabetes.