Justin Y. Jeon

Voluntary exercise improves insulin sensitivity and adipose tissue inflammation in diet-induced obese mice

Exercise promotes weight loss and improves insulin sensitivity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Obesity correlates with increased production of inflammatory cytokines, which in turn, contributes to systemic insulin resistance. To test the hypothesis that exercise mitigates this inflammatory response, thereby improving insulin sensitivity, we developed a model of voluntary exercise in mice made obese by feeding of a high fat/high sucrose diet (HFD). Over four wk, mice fed chow gained 2.3 +/- 0.3 g, while HFD mice gained 6.8 +/- 0.5 g. After 4 wk, mice were subdivided into four groups: chow-no exercise, chow-exercise, HFD-no exercise, HFD-exercise and monitored for an additional 6 wk. Chow-no exercise and HFD-no exercise mice gained an additional 1.2 +/- 0.3 g and 3.3 +/- 0.5 g respectively. Exercising mice had higher food consumption, but did not gain additional weight. As expected, GTT and ITT showed impaired glucose tolerance and insulin resistance in HFD-no exercise mice. However, glucose tolerance improved significantly and insulin sensitivity was completely normalized in HFD-exercise animals. Furthermore, expression of TNF-alpha, MCP-1, PAI-1 and IKKbeta was increased in adipose tissue from HFD mice compared with chow mice, whereas exercise reversed the increased expression of these inflammatory cytokines. In contrast, expression of these cytokines in liver was unchanged among the four groups. These results suggest that exercise partially reduces adiposity, reverses insulin resistance and decreases adipose tissue inflammation in diet-induced obese mice, despite continued consumption of HFD.

Improved Insulin Sensitivity and Adiponectin Level after Exercise Training in Obese Korean Youth

Objective: The objective of this study was to investigate the association among adiposity, insulin resistance, and inflammatory markers [high‐sensitivity C‐reactive protein (hs‐CRP), interleukin (IL)‐6, and tumor necrosis factor (TNF)‐α] and adiponectin and to study the effects of exercise training on adiposity, insulin resistance, and inflammatory markers among obese male Korean adolescents.

Relationship between osteocalcin and glucose metabolism in postmenopausal women

BACKGROUND Recently, osteocalcin was found to regulate blood glucose, insulin secretion, and fat deposition in mice. However, the relationship between osteocalcin levels and factors related to glucose metabolism in humans has not yet been investigated. We investigated the relationship between osteocalcin and glucose metabolism in postmenopausal women. METHODS Three hundred thirty-nine postmenopausal women were recruited for this study. Glucose metabolism related substance and serum osteocalcin were assayed. RESULTS There was a significant reduction in osteocalcin levels among type 2 diabetes mellitus patients compared with the normal glucose and impaired fasting glucose groups. Next, the subjects in the highest quartile for osteocalcin were observed to have significantly decreased fasting glucose and HbA1c levels compared with subjects in the lowest quartile. In addition, osteocalcin levels were inversely correlated with glucose, insulin, HbA1c, and insulin resistance. Moreover, multivariate analysis showed that serum osteocalcin was found to be an independent factor associated with glucose and HbA1c. CONCLUSIONS There is a potential role of osteocalcin in regulating blood glucose levels in postmenopausal women. This finding indicates that in humans the skeleton may be involved in energy metabolism by functioning as part of the endocrine system.

Association between physical activity and mortality in colorectal cancer: A meta-analysis of prospective cohort studies

Several prospective cohort studies have examined the association between prediagnosis and/or postdiagnosis physical activity (PA) on colorectal cancer outcomes and reported conflicting results. To quantitatively assess this association, we have conducted a meta‐analysis of prospective studies. Databases and reference lists of relevant studies were searched using MEDLINE and EMBASE up to January 2013. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random‐effects models. For this meta‐analysis, a total of seven prospective cohort studies were included. The analysis included 5,299 patients for prediagnosis PA and 6,348 patients for postdiagnosis PA, followed up over a period ranging from 3.8 to 11.9 years. The analyses showed that patients who participated in any amount of PA before diagnosis had a RR of 0.75 (95% CI: 0.65–0.87, p < 0.001) for colorectal cancer‐specific mortality compared to patients who did not participate in any PA. Those who participated in high PA before diagnosis (vs. low PA) had a RR of 0.70 (95% CI: 0.56–0.87, p = 0.002). Similarly, patients who participated in any PA after diagnosis had a RR of 0.74 (95% CI: 0.58–0.95, p = 0.02) for colorectal cancer‐specific mortality compared to patients who did not participate in any PA. Those who participated in high PA after diagnosis (vs. low PA) had a RR of 0.65 (95% CI: 0.47–0.92, p = 0.01). Similar inverse associations of prediagnosis or postdiagnosis PA were found for all‐cause mortality. In conclusion, both prediagnosis and postdiagnosis PA were associated with reduced colorectal cancer‐specific mortality and all‐cause mortality.

Histochemical changes in muscle of individuals with spinal cord injury following functional electrical stimulated exercise training.

Study Design: Longitudinal training. Objectives: To determine the effects of functional electrical stimulated (FES) leg cycle ergometer training on muscle histochemical characteristics in individuals with motor-complete spinal cord injury (SCI). Setting: University of Alberta, Edmonton, Alberta, Canada. Methods: Six individuals with motor-complete SCI (age 31–50 years; 3–25 years post-injury) trained using FES leg cycle ergometry for 30 min, 3 days per week for 8 weeks. Biopsies of the vastus lateralis muscle were obtained pre- and post-training and analyzed for fibre composition, fibre size and capillarization. Results: The majority of muscle fibres were classified as type 2 pre- and post-training. Average fibre area increased 23% (P<0.05) and capillary number increased 39% (P<0.05) with training. As a result of these proportional increases, capillarization expressed relative to fibre area was unchanged with training. Conclusions: FES leg cycle ergometer training results in proportional increases in fibre area and capillary number in individuals with SCI. Sponsorship: Supported by the Glenrose Rehabilitation Hospital.

Functional electrical stimulation exercise increases GLUT-1 and GLUT-4 in paralyzed skeletal muscle

The study purpose was to determine the effect of functional electrical stimulation (FES)-leg cycle ergometer training (30 minutes on 3 d/wk for 8 weeks) on the GLUT-1 and GLUT-4 content of paralyzed skeletal muscle. Biopsy samples of vastus lateralis muscle were obtained pre- and post-training from five individuals with motor-complete spinal cord injury ([SCI] four men and one woman aged 31 to 50 years, 3 to 25 years postinjury involving C5-T8). Western blot analysis indicated that GLUT-1 increased by 52% and GLUT-4 increased by 72% with training (P < .05). This coincided with an increase in the muscle oxidative capacity as indicated by a 56% increase in citrate synthase (CS) activity (P < .05) and an improvement in the insulin sensitivity index as determined from oral glucose tolerance tests (P < .05). It is concluded that FES endurance training is effective to increase glucose transporter protein levels in paralyzed skeletal muscle of individuals with SCI.

Chemerin levels are positively correlated with abdominal visceral fat accumulation

Objective  Chemerin, a recently discovered adipocytokine, may be linked to obesity and obesity‐associated metabolic complications. However, the relationship between visceral fat accumulation and chemerin is still unknown. Therefore, we investigated the relationship between serum chemerin levels and body composition as measured by computed tomography (CT).

Effects of a 6-month lifestyle modification intervention on the cardiometabolic risk factors and health-related qualities of life in women with metabolic syndrome

Although therapeutic lifestyle modification (TLM) has been recommended as a cornerstone treatment of metabolic syndrome (MetS), little is known about the biobehavioral effects of a TLM program for patients in a community. The purpose of this study was to examine the effects of a 6-month TLM program on MetS risk factors and health-related qualities of life (HRQOL) among middle-aged and older women in a community in Korea. Fifty-two women (mean age, 62.7 +/- 9.0 years) with MetS were recruited from 3 community health centers and were randomly assigned to the intervention (n = 31) or control (n = 21) groups. The patients in the intervention group participated in supervised TLM sessions for 6 months. The TLM program included health monitoring, counseling, health education, exercise, and dieting. Metabolic risk factors and HRQOL were measured at baseline, during the study (month 3), at completion (month 6), and post completion (month 12) of the TLM program. Compared with the control group, the TLM group showed significantly greater reductions in body weight (P < .001) and waist circumference (P < .001); these effects were sustained for 6 months after intervention. With regard to HRQOL, the TLM group showed greater improvements in physical function (P = .017), general health (P < .001), vitality (P = .008), and mental health (P = .027). These improvements, however, were not sustained after the intervention. The results indicate that a nurse-led systematic TLM program may be an effective strategy for managing middle-aged and older women with MetS at a community level.

Chemerin and Adiponectin Contribute Reciprocally to Metabolic Syndrome

Obesity and metabolic syndrome (MetS) are considered chronic inflammatory states. Chemerin, a novel adipokine, may play an important role in linking MetS and inflammation. We investigated the association of chemerin with inflammatory markers and with characteristics of MetS in apparently healthy overweight and obese adults. We studied 92 adults; 59 men and 33 women whose average body mass index (BMI) was 28.15±5.08 kg/m2. Anthropometric parameters, insulin resistance indices, lipid profiles, and inflammatory markers including high sensitivity C-reactive protein (hsCRP), pentraxin 3 (PTX3), adiponectin, and chemerin were measured. Controlling for age, gender, and BMI, serum chemerin level was positively correlated with body fat and serum triglyceride, and negatively correlated with adiponectin and high density lipoprotein cholesterol (HDL- C), and was not correlated with altered hsCRP or PTX3 levels. Among the low, moderate and high chemerin groups, high chemerin individuals are more likely to have lower HDL-C. Conversely, individuals in the low adiponectin group are more likely to have lower HDL-C and show more MetS phenotypic traits than moderate and high adiponectin subjects. To determine the relationships of chemerin and adiponectin to MetS and its components, participants were stratified into four groups based on their chemerin and adiponectin levels (high chemerin/high adiponectin, high chemerin/low adiponectin, low chemerin/high adiponectin, or low chemerin/low adiponectin). Participants who were in the high chemerin/low adiponectin group more likely to have dyslipidemia and MetS (OR: 5.79, 95% CI:1.00–33.70) compared to the other three group. Our findings suggest that chemerin and adiponectin may reciprocally participate in the development of MetS.

Reduced serum vaspin concentrations in obese children following short-term intensive lifestyle modification

BACKGROUND Recently, visceral adipose tissue-derived serpin (vaspin) was identified as a potential insulin sensitizing adipokine, however, the factors determining the levels of circulating vaspin levels have not been fully understood. We investigated the association between adiposity, insulin resistance, lipid profiles and inflammatory markers including vaspin levels, and the effects of short-term intensive lifestyle modification on circulating vaspin levels in overweight or obese children. METHODS A total of 50 (25 boys, 25 girls) overweight or obese children aged 11 to 13 years (average age: 12.0+/-0.9 y, BMI: 25.35+/-86 kg/m(2)) who complied with inclusion criteria participated in our study. To determine the association between adiposity, insulin resistance, lipid profiles and inflammatory markers including vaspin levels, cross-sectional analyses were performed. Thereafter, subjects underwent a tightly controlled seven-day intensive lifestyle modification including physical activity, dietary modification, and behavioral modification education in residence of a local university dormitory. RESULTS There was a negative correlation between vaspin concentration and fasting insulin (r=-.325, p<0.05) and homeostasis model assessment of insulin resistance (HOMA-IR) (r=-.331, p<0.05) when percent body fat was controlled. Multivariate linear regression analysis found serum vaspin level to be an independent predictor of insulin and HOMA-IR. Short-term intensive lifestyle modification significantly decreased vaspin levels by 39.28% (pre: .84+/-1.0, post: .51+/-1.0 ng/ml, p<0.001) while adiponectin levels increased by 11.2% (pre: 6.50+/-2.89, post: 7.28+/-2.98 ng/ml, p<0.01). In addition, short-term lifestyle modification significantly improved HOMA-IR (pre: 3.58+/-1.93, post 1.30+/-1.9, p<0.001) and lipid profiles. CONCLUSIONS Serum vaspin level is one of the predictors for insulin resistance and was significantly reduced following short-term lifestyle modification.