Homeostastic model assessment and insulin sensitivity/resistance

A masked, placebo-controlled, randomized clinical trial evaluating safety and the effect on cardiac function of low-dose rapamycin in 17 healthy client-owned dogs

Introduction

Geroscience studies of low-dose rapamycin in laboratory species have identified numerous benefits, including reversing age-related cardiac dysfunction. Cardiovascular benefits have been observed in dogs with 10 weeks of treatment, raising questions about possible benefits and adverse effects of long-term use of low-dose rapamycin. The objectives of this study were to assess the impact of 6 months of low-dose rapamycin on echocardiographic indices of cardiac function in healthy dogs and to document the occurrence of adverse events.

Methods

Seventeen client-owned dogs aged 6-10 years, weighing 18-36 kg, and without significant systemic disease were included in a prospective, randomized, placebo-controlled, masked clinical trial. Low-dose rapamycin (0.025 mg/kg) or placebo was administered three times per week for 6 months. Baseline, 6-month, and 12-month evaluation included physical examination, cardiology examination, and clinicopathology. Three-month evaluation included physical examination and clinicopathology. Owners completed online questionnaires every 2 weeks.

Results

There were no statistically significant differences in echocardiographic parameters between rapamycin and placebo groups at 6 or 12 months. No clinically significant adverse events occurred. In 26.8% of the bi-weekly surveys owners whose dogs received rapamycin reported perceived positive changes in behavior or health, compared to 8.1% in the placebo group (p = 0.04).

Discussion

While no clinically significant change in cardiac function was observed in dogs treated with low-dose rapamycin, the drug was well-tolerated with no significant adverse events.

Urbanization and Unfavorable Changes in Metabolic Profiles: A Prospective Cohort Study of Indonesian Young Adults

The substantial increase in the prevalence of non-communicable diseases in Indonesia might be driven by rapid socio-economic development through urbanization. Here, we carried out a longitudinal 1-year follow-up study to evaluate the effect of urbanization, an important determinant of health, on metabolic profiles of young Indonesian adults. University freshmen/women in Jakarta, aged 16−25 years, who either had recently migrated from rural areas or originated from urban settings were studied. Anthropometry, dietary intake, and physical activity, as well as fasting blood glucose and insulin, leptin, and adiponectin were measured at baseline and repeated at one year follow-up. At baseline, 106 urban and 83 rural subjects were recruited, of which 81 urban and 66 rural were followed up. At baseline, rural subjects had better adiposity profiles, whole-body insulin resistance, and adipokine levels compared to their urban counterparts. After 1-year, rural subjects experienced an almost twice higher increase in BMI than urban subjects (estimate (95%CI): 1.23 (0.94; 1.52) and 0.69 (0.43; 0.95) for rural and urban subjects, respectively, Pint < 0.01). Fat intake served as the major dietary component, which partially mediates the differences in BMI between urban and rural group at baseline. It also contributed to the changes in BMI over time for both groups, although it does not explain the enhanced gain of BMI in rural subjects. A significantly higher increase of leptin/adiponectin ratio was also seen in rural subjects after 1-year of living in an urban area. In conclusion, urbanization was associated with less favorable changes in adiposity and adipokine profiles in a population of young Indonesian adults.

Cross-sectional association between physical fitness and cardiometabolic risk in Chilean schoolchildren: the fat but fit paradox

BACKGROUND

Previous studies have examined the "fat but fit" paradox, revealing that greater levels of physical fitness may diminish the harmful consequences of excess weight on cardiometabolic risk. Despite the above, specific information about the "fat but fit" paradox in prepuberal population is scarce. The aim of this study was to determine the relationship between cardiometabolic risk across (individual and combined) physical fitness and excess weight status and whether the "fat but fit" paradox is met in the sample of schoolchildren analyzed.

METHODS

A cross-sectional study was conducted including 452 children (59.1% girls), aged 7-9 years from Santiago (Chile). Physical fitness was assessed as cardiorespiratory fitness and muscular fitness. Cardiorespiratory fitness was determined by the 6-minute-walk-test and muscle strength was assessed by the handgrip and standing long jump tests. Excess weight (overweight and obesity) was computed through body mass index (z-score). Cardiometabolic risk was established by summing the z-score of the serum glucose, triglycerides, high-density lipoprotein, insulin and waist-to-height ratio.

RESULTS

Schoolchildren with high physical fitness (individual or combined) showed the lowest cardiometabolic risk mean scores (P for trend <0.001 for all physical fitness groups). Conversely, schoolchildren with low physical fitness (individual or combined) showed the highest cardiometabolic risk mean scores (P for trend <0.001 for all categories). Additionally, schoolchildren without excess weight and with high individual or combined physical fitness status exhibits lower cardiometabolic risk mean scores compared to schoolchildren with excess weight and low physical fitness status (individual or combined) (P for trend <0.001 for all physical fitness groups). A lower odd of having high cardiometabolic risk was found in schoolchildren without excess weight and with both high physical fitness (both cardiorespiratory fitness and muscular fitness) [odds ratio (OR) =0.08; 95% confidence interval (CI): 0.04 to 0.16] in comparison to those with excess weight and low physical fitness.

CONCLUSIONS

Our results suggest that improvements in both fatness and aerobic fitness could be associated with lower cardiometabolic risk.

Space Flight-Promoted Insulin Resistance as a Possible Disruptor of Wound Healing

During space flight, especially when prolonged, exposure to microgravity results in a number of pathophysiological changes such as bone loss, muscle atrophy, cardiovascular and metabolic changes and impaired wound healing, among others. Interestingly, chronic low-grade inflammation and insulin resistance appear to be pivotal events linking many of them. Interestingly, real and experimental microgravity is also associated to altered wound repair, a process that is becoming increasingly important in view of prolonged space flights. The association of insulin resistance and wound healing impairment may be hypothesized from some dysmetabolic conditions, like the metabolic syndrome, type 2 diabetes mellitus and abdominal/visceral obesity, where derangement of glucose and lipid metabolism, greater low-grade inflammation, altered adipokine secretion and adipocyte dysfunction converge to produce systemic effects that also negatively involve wound healing. Indeed, wound healing impairment after traumatic events and surgery in space remains a relevant concern for space agencies. Further studies are required to clarify the molecular connection between insulin resistance and wound healing during space flight, addressing the ability of physical, endocrine/metabolic, and pharmacological countermeasures, as well as nutritional strategies to prevent long-term detrimental effects on tissue repair linked to insulin resistance. Based on these considerations, this paper discusses the pathophysiological links between microgravity-associated insulin resistance and impaired wound healing.

Light exposure during sleep impairs cardiometabolic function

SignificanceAmbient nighttime light exposure is implicated as a risk factor for adverse health outcomes, including cardiometabolic disease. However, the effects of nighttime light exposure during sleep on cardiometabolic outcomes and the related mechanisms are unclear. This laboratory study shows that, in healthy adults, one night of moderate (100 lx) light exposure during sleep increases nighttime heart rate, decreases heart rate variability (higher sympathovagal balance), and increases next-morning insulin resistance when compared to sleep in a dimly lit (<3 lx) environment. Moreover, a positive relationship between higher sympathovagal balance and insulin levels suggests that sympathetic activation may play a role in the observed light-induced changes in insulin sensitivity.

Handgrip strength cut-off points for early detection of cardiometabolic risk in Chilean children

The aim of this study was to determine whether handgrip strength is associated with cardiometabolic risk in children. The secondary aim was to establish sex-specific handgrip strength cut-off points for early detection of cardiometabolic risk. A total sample of 452 Chilean children (267 girls and 185 boys) aged 7-9 years old was analyzed. Muscle fitness was measured by an adjustable dynamometer and normalized by body mass (i.e., handgrip strength/body mass). Sex-specific cardiometabolic risk scores were computed as the sum of the waist-to-height ratio (Equation 1) or waist circumference (Equation 2) and insulin, triglycerides, high-density lipoproteins, and glycemia levels. Receiver operating curve (ROC) analyses were performed to identify those with cardiometabolic risk scores > 1 standard deviation above the mean. ROC analyses showed a significant discriminating accuracy of normalized handgrip strength in identifying cardiometabolic risk in boys (≤ 0.33) and girls (≤ 0.40) using both equations. The highest sensitivity was offered by Equation 2 for boys [46%; 95% CI (32-59%)] and for girls [71%; 95% CI (60-80)]. The greatest specificity was also offered by Equation 2 for boys [82%; 95% CI (74-88)] and girls [63%; 95% CI (55-70)]. Since the values obtained by ROC analyses are low (especially in boys), caution is warranted regarding the strength of the existing evidence base.Conclusion: These specific cut-off points according to sex for possible cardiometabolic risk could be used by Chilean health professionals and school staff as an initial assessment in the field setting. What is known • There is strong evidence for the importance of muscular fitness during childhood and adolescence for cardiometabolic risk. • There has been no research to establish minimum handgrip strength capacity levels to predict cardiometabolic risk among Chilean children. What is new • Cut-off points for handgrip strength relative to body mass to identify cardiometabolic risk in Chilean children are 0.33 in boys and 0.40 in girls. • The early use of these cut-off points and its appropriate identification could have benefits of preventive and diagnostic therapeutic intervention and as a starting point to define adequate levels of handgrip strength.

Gut microbiota of adults with different metabolic phenotypes

OBJECTIVE

The aim of this study was to investigate the gut microbiota of individuals with different metabolic phenotypes and to compare their characteristics.

METHODS

This was a cross-sectional study with 109 adults, classified according to metabolic status, by body mass index, and homeostasis model assessment. Anthropometric and biochemical characteristics and blood pressure were evaluated. Level of physical activity was evaluated by means of a questionnaire, and dietary consumption was evaluated using a 3-d food record. Feces samples were collected from each participant, and gut microbiota profile was analyzed by sequencing of the 16S rRNA gene. The Kruskal-Wallis and χ² tests were used, according to the scale of measurement of the variables, on the statistical program SPSS version 25, with significance level of 5%.

RESULTS

Significantly lower values of saturated fat intake and fasting glycemia were observed in metabolically healthy individuals who were overweight and obese compared with their unhealthy counterparts. Diversity and richness of bacterial communities were lower in individuals who were obese and in the unhealthy phenotype. The genus Eubacterium rectale and genera of the family Prevotellaceae were more abundant in the metabolically healthy obese and metabolically healthy overweight groups than in the metabolically healthy normal weight one, whereas Bifidobacterium was more abundant in the metabolically healthy normal weight group. The genera Coprococcus and Ruminococcus were more abundant in the metabolically healthy overweight group than in the metabolically unhealthy overweight one.

CONCLUSIONS

We observed distinct characteristics in the gut microbiota of different metabolic phenotypes. The intestines of individuals with unhealthy phenotypes hosted inflammation-associated microbiota, with lower butyrate production potential and reduced bacterial diversity.

Ketogenic diet, seizure control, and cardiometabolic risk in adult patients with pharmacoresistant epilepsy: a review

Pharmacoresistant epilepsy causes serious deleterious effects on the patient's health and quality of life. For this condition, a ketogenic diet (KD) is a treatment option. The KD is a general term for a set of diets that contain high amounts of fat and low content of carbohydrates. The most prominent KD treatments are classical KD (4:1 ratio of fat to carbohydrate), modified Atkins diet (2:1 to 1:1 ratio), medium-chain triglycerides KD (with medium-chain triglyceride as a part of the fat content), and low glycemic index KD (using low glycemic carbohydrates). KD has been widely prescribed for children with epilepsy but not for adult patients. One of the main concerns about adult use of KD is its cardiovascular risk associated with high-fat and cholesterol intake. Therefore, this narrative review provides comprehensive information of the current literature on the effects of KD on lipid profile, glycemic-control biomarkers, and other cardiometabolic risk factors in adult patients with pharmacoresistant epilepsy.

Effectiveness of ginger in reducing metabolic levels in people with diabetes: a randomized clinical trial

OBJECTIVE

to evaluate the effectiveness of ginge (Zingiber officinale) in reducing blood sugar and lipid levels in people with type 2 diabetes.

METHOD

a randomized and double-blind clinical trial conducted with people with type 2 diabetes in primary care facilities. The study included individuals aged between 20 and 80 years old, using oral antidiabetic drugs and with HbA1c levels between 6.0% and 10%. The participants were paired 1:1, allocated in two distinct groups, and randomized in blocks, based on their HbA1c levels. In the experimental group, the participants used 1.2g of ginger and, in the control group, 1.2g of placebo, daily for 90 days. The primary outcome was a reduction in fasting blood sugar and HbA1c, and the secondary outcome was a reduction in lipids and HOMA-IR. 103 individuals completed the study, 47 in the experimental group and 56 in the control group.

RESULTS

the participants in the experimental group showed a greater reduction in the blood glucose and total cholesterol values compared to the control group.

CONCLUSION

the use of ginger can help in the treatment of people with diabetes, and data support the inclusion of this herbal drug in the clinical practice of nurses. RBR-2rt2wy.

Resistance to lean mass gain in constitutional thinness in free-living conditions is not overpassed by overfeeding

BACKGROUND

Constitutional thinness (CT), a non-malnourished underweight state with no eating disorders, is characterized by weight gain resistance to high fat diet. Data issued from muscle biopsies suggested blunted anabolic mechanisms in free-living state. Weight and metabolic responses to protein caloric supplementation has not been yet explored in CT.

METHODS

A 2 week overfeeding (additional 600 kcal, 30 g protein, 72 g carbohydrate, and 21 g fat) was performed to compare two groups of CTs (12 women and 11 men) to normal-weight controls (12 women and 10 men). Bodyweight, food intake, energy expenditure, body composition, nitrogen balance, appetite hormones profiles, and urine metabolome were monitored before and after overfeeding.

RESULTS

Before overfeeding, positive energy gap was found in both CT genders (309 ± 370 kcal in CT-F and 332 ± 709 kcal in CT-M) associated with higher relative protein intake per kilo (1.74 ± 0.32 g/kg/day in CT-F vs. 1.16 ± 0.23 in C-F, P < 0.0001; 1.56 ± 0.36 in CT-M vs. 1.22 ± 0.32 in C-M, P = 0.03), lower nitrogen (7.26 ± 2.36 g/day in CT-F vs. 11.41 ± 3.64 in C-F, P = 0.003; 9.70 ± 3.85 in CT-M vs. 14.14 ± 4.19 in C-M, P = 0.02), but higher essential amino acids urinary excretion (CT/C fold change of 1.13 for leucine and 1.14 for arginine) in free-living conditions. After overfeeding, CTs presented an accentuated positive energy gap, still higher than in controls (675 ± 540 in CTs vs. 379 ± 427 in C, P = 0.04). Increase in lean mass was induced in both controls genders but not in CTs (a trend was noticed in CT women), despite a similar nitrogen balance after overfeeding (5.06 ± 4.33 g/day in CTs vs. 4.28 ± 3.15 in controls, P = 0.49). Higher anorectic gut hormones' tone, glucagon-like peptide 1 and peptide tyrosine tyrosine, during test meal and higher snacking frequency were noticed before and after overfeeding in CTs.

CONCLUSIONS

The blunted muscle energy mechanism, previously described in CTs in free-living state, is associated with basal saturated protein turn over suggested by the concordance of positive nitrogen balance and an increased urine excretion of several essential amino acids. This saturation cannot be overpassed by increasing this spontaneous high-protein intake suggesting a resistance to lean mass gain in CT phenotype.

Circulating miRNAs as a Predictive Biomarker of the Progression from Prediabetes to Diabetes: Outcomes of a 5-Year Prospective Observational Study

Due to a global increase in the prevalence of type 2 diabetes mellitus (T2DM), there is an urgent need for early identification of prediabetes, as these people have the highest risk of developing diabetes. Circulating miRNAs have shown potential as progression biomarkers in other diseases. This study aimed to conduct a baseline comparison of serum-circulating miRNAs in prediabetic individuals, with the distinction between those who later progressed to T2DM and those who did not. The expression levels of 798 miRNAs using NanoString technology were examined. Spearman correlation, receiver operating characteristic (ROC) curve analysis, and logistic regression modeling were performed. Gene ontology (GO) and canonical pathway analysis were used to explore the biological functions of the miRNA target genes. The study revealed that three miRNAs were upregulated in the serum samples of patients who later progressed to T2DM. Pathway analysis showed that the miRNA target genes were mainly significantly enriched in neuronal NO synthase (nNOS) signaling in neurons, amyloid processing, and hepatic cholestasis. ROC analysis demonstrated that miR-491-5p, miR-1307-3p, and miR-298 can be introduced as a diagnostic tool for the prediction of T2DM (area under the curve (AUC) = 94.0%, 88.0%, and 84.0%, respectively). Validation by real-time quantitative polymerase chain reaction (qRT-PCR) confirmed our findings. The results suggest that circulating miRNAs can potentially be used as predictive biomarkers of T2DM in prediabetic patients.

Prevalence of insulin resistance and identifying HOMA1-IR and HOMA2-IR indexes in the Middle Black Sea region of Turkey

Background

Insulin resistance (IR) is one of the most important etiological risk factors in the development of diabetes. However, there is no clear data regarding the prevalence of IR in the country.

Objective

This study evaluates the prevalence of IR and identifies the optimal threshold values for the HOMA indexes in Turkey.

Methods

This cross-sectional, population-based survey includes 2013 participants aged 20–84 years. The values of the anthropometric measurements and laboratory analysis were recorded. The 90^th percentile in the non-obese and non-diabetic population was accepted as cut-off values for IR.

Results

The optimal threshold values for IR were 2.46 in HOMA1-IR and 1.40 in HOMA2-IR. Using the HOMA2-IR method, the overall prevalence of IR was 33.2%. The IR prevalence was higher in women (35.6%) compared to men (30.1%) [p=0.008]. There was a higher IR prevalence in men living in urban areas (p=0.001), not in women. The multivariate logistic regression analysis showed that gender, serum glucose level, serum levels of triglycerides and high-density lipoprotein cholesterol, bodymass index and income status were associated with insulin resistance.

Conclusion

The cut-off values of HOMA1-IR and HOMA2-IR were determined in this study and we believe that these findings will be helpful to clinicians in the fight against health problems such as diabetes.

Association between non-obesity and health state among young Japanese male university students

[Purpose] The obesity rate in both males and females has been lower in Japan than in other countries. However, the prevalence of metabolic syndrome-related risk factors is not low when compared with that in Western countries. In this study, we aimed to evaluate the health state of young, non-obese adults in Japan. [Participants and Methods] We recruited 20 young, non-obese Japanese male university students and examined the maximum oxygen consumption, physical activity, and components of metabolic syndrome. We evaluated the physical activity level and dietary habits of the participants through a questionnaire survey. [Results] The questionnaire survey revealed that 70% participants had non-standard dietary habits, 55% did not engage in any regular exercise, and 25% were inactive. On examination, 20% participants had at least one positive risk factor for metabolic syndrome. The homeostatic model assessment of insulin resistance and triglyceride values did not correlate with the body mass index of the participants; however, the values were inversely related to the maximum oxygen consumption levels. [Conclusion] Even participants with normal body mass index had poor dietary habits and a lack of exercise. Our results confirmed that even non-obese Japanese individuals have certain health risks and that having higher maximum oxygen consumption has beneficial effects in preventing the risk factors of severe and life-threatening diseases.

A novel measure of glucose homeostasis (or loss thereof) comprising the joint dynamics of glucose, insulin, glucagon, and cortisol

Quantification of disturbances in glucose-insulin homeostasis has been the cornerstone of appraising insulin resistance and detecting early-stage diabetes. Metabolic homeostasis arises from feedback and feed-forward interactions among (at least) all four of glucose, insulin, glucagon, and cortisol. Quantifying such tetrapartite interactions in the fasting (endogenously regulated) state overnight could elucidate very early regulatory disruption. In the present study, healthy subjects without diabetes (ND; n = 20) and patients with Type 2 diabetes (T2D; n = 21) were investigated by repeated overnight blood sampling of all four of glucose, insulin, glucagon, and cortisol concentrations. To obviate confounding by hormone-specific disappearance rates, analyses were performed at the level of production (glucose) or secretion (insulin, glucagon, and cortisol) rates estimated by regularized deconvolution analysis. Then, a novel method for quantifying the loss of homeostasis among glucose, insulin, and glucagon (and, when available, cortisol) secretion patterns was developed. Potential early stage prediabetic candidates were identified. The new methodology avoids many of the difficulties encountered in the conventional estimation of insulin-glucose sensitivity or resistance, while incorporating the dynamics of the key coregulators under fasting conditions.

PPARG Pro12Ala Ala carriers exhibit greater improvements in peripheral insulin sensitivity in response to 12 weeks of aerobic exercise training

The Ala allele of PPARG Pro12Ala ( rs1801282 ) is associated with greater improvements to the glucose metabolism in exercise studies, but whether this extends to peripheral insulin sensitivity is unknown. Our objective was to investigate the effect of PPARG Pro12Ala on exercise-induced changes in peripheral insulin sensitivity. A total of 124 (91 Pro homozygotes and 33 Ala carriers) previously physically inactive healthy young men and women with overweight or class 1 obesity who completed a 12 wk aerobic exercise intervention were included in the analysis. All participants underwent a hyperinsulinemic euglycemic clamp before and after the 12 wk intervention. The prescribed exercise frequency was 5–7 days/wk, and the exercise energy expenditure was 2,100 4,200 kcal/wk for men and 1,600 kcal/wk for women. Insulin sensitivity improved significantly in both genotype groups. However, Ala carriers had a 1.13-fold (95% confidence interval 1.01; 1.26, P = 0.032) greater improvement in insulin sensitivity from baseline compared with Pro homozygotes. Our data support that PPARG Pro12Ala modifies the effect of aerobic exercise on peripheral insulin sensitivity.

Arm crank ergometry improves cardiovascular disease risk factors and community mobility independent of body composition in high motor complete spinal cord injury

OBJECTIVE

Evaluate the effect of aerobic exercise using arm crank ergometry (ACE) in high motor complete (ISNCSCI A/B) spinal cord injury (SCI) as primarily related to cardiovascular disease (CVD) risk factors and functional mobility and secondarily to body composition and metabolic profiles.

DESIGN

Longitudinal interventional study at an academic medical center.

METHODS

Ten previously untrained participants (M8/F2, Age 36.7 y ± 10.1, BMI 24.5 ± 6.0) with high motor complete SCI (C7-T5) underwent ACE exercise training 30 minutes/day × 3 days/week for 10 weeks at 70% VO2Peak.

OUTCOME MEASURES

Primary outcome measures were pre- and post-intervention changes in markers of cardiovascular fitness (graded exercise testing (GXT): VO2, VO2Peak, respiratory quotient [RQ], GXT time, peak power, and energy expenditure [EE]) and community mobility (time to traverse a 100ft-5° ramp, and 12-minute WC propulsion test). Secondary outcome measures were changes in body composition and metabolic profiles (fasting and area under the curve for glucose and insulin, homeostasis model assessment [HOMA] for %β-cell activity [%β], %insulin sensitivity [%S], and insulin resistance [IR], and Matsuda Index [ISIMatsuda]).

RESULTS

Resting VO2, relative VO2Peak, absolute VO2Peak, peak power, RQ, 12-minute WC propulsion, fasting insulin, fasting G:I ratio, HOMA-%S, and HOMA-IR all significantly improved following intervention (P < 0.05). There were no changes in body composition (P>0.05).

CONCLUSIONS

Ten weeks of ACE at 70% VO2Peak in high motor complete SCI improves aerobic capacity, community mobility, and metabolic profiles independent of changes in body composition.

Anthropometric cutoffs and associations with visceral adiposity and metabolic biomarkers after spinal cord injury

Background/Objectives

To examine associations of different anthropometric measurements of central adiposity to visceral adipose tissue (measured via multi-axial magnetic resonance imaging; MRI) and cardiometabolic disease risk factors in men with spinal cord injury (SCI). Additionally, to determine population-specific seated/supine waist and abdominal circumference cutoffs, which may identify men at increased risk of cardiometabolic disease.

Participants/Methods

Twenty-two men with chronic SCI underwent MRI scans, anthropometric measurements along with assessments of various cardiometabolic risk biomarkers. Pearson/part (accounting for age as a covariate) correlation coefficients were calculated to determine the associations between study variables. Abdominal and waist circumference cutoffs were extrapolated using the slope of linear regression equations.

Results

Seated/supine abdominal and waist circumferences were (P < 0.01) associated with MRI visceral fat cross-sectional area (VAT_CSA), VAT volume and CSA:Total_CSA. Low density lipoprotein, non-high-density lipoprotein and total cholesterol were positively associated with seated/supine abdominal and waist circumferences after controlling for age; r = 0.50–0.61, r = 0.46–0.58, r = 0.52–0.58, P < 0.05, respectively. Tumor necrosis factor alpha was associated with seated/supine abdominal and waist circumferences after accounting for age; r = 0.49–0.51 and r = 0.48–0.56, P < 0.05 respectively. The population-specific cutoffs were 86.5cm and 88.3cm for supine waist and abdominal circumferences, respectively, as well as 89cm and 101cm for seated waist and abdominal circumferences, respectively. After dichotomizing VAT_CSA (< or ≥ 100cm²), peak oxygen uptake, triglycerides, insulin sensitivity and glycated hemoglobin were different (P < 0.05) between groups. After dichotomizing (< or ≥ 86.5cm) supine waist circumference, VAT_CSA, triglycerides and insulin sensitivity were different (P < 0.05) between groups.

Conclusions

Seated/supine circumferences are associated with both central adiposity and biomarkers of cardiometabolic disease risk in persons with SCI. Population-specific cutoffs are proposed herein to identify central adiposity and potential cardiometabolic disease risk after SCI.

A new hypoglycemic mechanism of catalpol revealed by enhancing MyoD/MyoG-mediated myogenesis

AIMS

Enhancing myogenesis has been identified as a possible target to improve insulin sensitivity and protect against metabolic diseases. Catalpol, an iridoid glycoside, has been shown to exert a hypoglycaemic effect by improvement of insulin sensitivity; however, the underlying mechanism remains unknown. In this study, we tested whether catalpol has the potential to improve insulin sensitivity by augmenting myogenesis.

MAIN METHODS

We examined the hypoglycaemic mechanism of catalpol in db/db mice and C2C12 cells. db/db mice were treated with catalpol (200 mg/kg) for 8 consecutive weeks. Serum analysis, skeletal muscle performance and histology, and gene and protein expression were performed. In vitro glucose uptake, gene and protein expression were determined, and small interfering RNA was used to identify the underlying hypoglycaemic mechanism of catalpol.

KEY FINDINGS

In this study, we tested whether catalpol has the potential to improve skeletal insulin sensitivity by augmenting myogenesis, in which we found that, catalpol treatment in db/db mice lowered blood glucose and improved insulin sensitivity via activation of phosphatidylinositol‑3‑Kinase (PI3K)/protein kinase B (AKT) pathway. Moreover, catalpol-treated mice exhibited enhanced myogenesis, as evidenced by increased myogenic differentiation (MyoD), myogenin (MyoG) and myosin heavy chain (MHC) expressions. The in vitro experimental results showed that both catalpol and metformin enhanced glucose uptake via activation of PI3K/AKT pathway. However, unlike metformin, the PI3K/AKT pathway activation by catalpol was dependent on enhanced MyoD/MyoG-mediated myogenesis.

SIGNIFICANCE

Improvement of insulin sensitivity by enhancing MyoD/MyoG-mediated myogenesis may constitute a new therapeutic approach for treating type 2 diabetes.

Optimism, pessimism, cynical hostility, and biomarkers of metabolic function in the Women's Health Initiative

BACKGROUND

Psychological attitudes reflecting expectations about the future (optimism, pessimism) and people (cynical hostility) independently predict incident cardiovascular disease and possibly diabetes, but underlying biologic pathways are incompletely understood. Herein we examined the cross-sectional relationship between optimism, pessimism, and cynicism and biomarkers of metabolic function in the Women's Health Initiative.

METHODS

Among 3443 postmenopausal women, biomarkers of metabolic function (fasting insulin [FINS] and glucose) were measured at baseline and used to calculate insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and pancreatic β-cell activity (homeostasis model assessment of β-cell function [HOMA-B]). Psychological attitudes were assessed by the Life Orientation Test, Revised (full scale, and optimism and pessimism subscales) and the Cook-Medley cynicism subscale. Multivariable linear regression modeled the association of psychological attitudes with biomarker levels, adjusting for sociodemographics, health conditions, and health behaviors. Because obesity promotes insulin resistance and obese individuals tend to report higher levels of pessimism and cynical hostility, an interaction with body mass index (BMI) was explored.

RESULTS

In fully adjusted models, only pessimism remained independently associated with higher FINS and insulin resistance (HOMA-IR). Scoring 1 point higher on the pessimism subscale was associated with a 1.2% higher FINS, whereas scoring 1 SD higher was associated with a 2.7% higher FINS (P = 0.03); results were similar for HOMA-IR. An interaction term with BMI was not significant.

CONCLUSIONS

In multivariable models, higher dispositional pessimism was associated with worse metabolic function; these findings were not modified by obesity status. Results extend prior work by linking pessimism to an objective biomarker of insulin resistance in elderly women.

Impact of Exercise on Cardiometabolic Component Risks in Spinal Cord-injured Humans

Purpose

Spinal cord injury (SCI) creates a complex pathology, characterized by low levels of habitual physical activity and an increased risk of cardiometabolic disease. This study aimed to assess the effect of a moderate-intensity upper-body exercise training intervention on biomarkers of cardiometabolic component risks, adipose tissue metabolism, and cardiorespiratory fitness in persons with SCI.

Methods

Twenty-one inactive men and women with chronic (>1 yr) SCI (all paraplegic injuries) 47 ± 8 yr of age (mean ± SD) were randomly allocated to either a 6-wk prescribed home-based exercise intervention (INT; n = 13) or control group (CON; n = 8). Participants assigned to the exercise group completed 4 × 45-min moderate-intensity (60%–65% peak oxygen uptake (V˙O_2peak)) arm-crank exercise sessions per week. At baseline and follow-up, fasted and postload blood samples (collected during oral glucose tolerance tests) were obtained to measure metabolic regulation and biomarkers of cardiovascular disease. Abdominal subcutaneous adipose tissue biopsies were also obtained, and cardiorespiratory fitness was assessed.

Results

Compared with CON, INT significantly decreased (P = 0.04) serum fasting insulin (Δ, 3.1 ± 10.7 pmol·L⁻¹ for CON and −12.7 ± 18.7 pmol·L⁻¹ for INT) and homeostasis model assessment of insulin resistance (HOMA2-IR; Δ, 0.06 ± 0.20 for CON and −0.23 ± 0.36 for INT). The exercise group also increased V˙O_2peak (Δ, 3.4 mL·kg⁻¹·min⁻¹; P ≤ 0.001). Adipose tissue metabolism, composite insulin sensitivity index (C-ISI_Matsuda), and other cardiovascular disease risk biomarkers were not different between groups.

Conclusions

Moderate-intensity upper-body exercise improved aspects of metabolic regulation and cardiorespiratory fitness. Changes in fasting insulin and HOMA2-IR, but not C-ISI_Matsuda, suggest improved hepatic but not peripheral insulin sensitivity after 6 wk of exercise training in persons with chronic paraplegia.

Post-Exercise Carbohydrate-Energy Replacement Attenuates Insulin Sensitivity and Glucose Tolerance the Following Morning in Healthy Adults

The carbohydrate deficit induced by exercise is thought to play a key role in increased post-exercise insulin action. However, the effects of replacing carbohydrate utilized during exercise on postprandial glycaemia and insulin sensitivity are yet to be determined. This study therefore isolated the extent to which the insulin-sensitizing effects of exercise are dependent on the carbohydrate deficit induced by exercise, relative to other exercise-mediated mechanisms. Fourteen healthy adults performed a 90-min run at 70% V˙O2max starting at 1600–1700 h before ingesting either a non-caloric artificially-sweetened placebo solution (CHO-DEFICIT) or a 15% carbohydrate solution (CHO-REPLACE; 221.4 ± 59.3 g maltodextrin) to precisely replace the measured quantity of carbohydrate oxidized during exercise. The alternate treatment was then applied one week later in a randomized, placebo-controlled, and double-blinded crossover design. A standardized low-carbohydrate evening meal was consumed in both trials before overnight recovery ahead of a two-hour oral glucose tolerance test (OGTT) the following morning to assess glycemic and insulinemic responses to feeding. Compared to the CHO-DEFICIT condition, CHO-REPLACE increased the incremental area under the plasma glucose curve by a mean difference of 68 mmol·L⁻¹ (95% CI: 4 to 132 mmol·L⁻¹; p = 0.040) and decreased the Matsuda insulin sensitivity index by a mean difference of −2 au (95% CI: −1 to −3 au; p = 0.001). This is the first study to demonstrate that post-exercise feeding to replaceme the carbohydrate expended during exercise can attenuate glucose tolerance and insulin sensitivity the following morning. The mechanism through which exercise improves insulin sensitivity is therefore (at least in part) dependent on carbohydrate availability and so the day-to-day metabolic health benefits of exercise might be best attained by maintaining a carbohydrate deficit overnight.

Effects of acute hyperinsulinemia on skeletal muscle mitochondrial function, reactive oxygen species production, and metabolism in premenopausal women

BACKGROUND

Acute metabolic demands that promote excessive and/or prolonged reactive oxygen species production may stimulate changes in mitochondrial oxidative capacity.

PURPOSE

To assess changes in skeletal muscle H₂O₂ production, mitochondrial function, and expression of genes at the mRNA and protein levels regulating energy metabolism and mitochondrial dynamics following a hyperinsulinemic-euglycemic clamp in a cohort of 11 healthy premenopausal women.

METHODS

Skeletal muscle biopsies of the vastus lateralis were taken at baseline and immediately following the conclusion of a hyperinsulinemic-euglycemic clamp. Mitochondrial production of H₂O₂ was quantified fluorometrically and mitochondrial oxidation supported by pyruvate, malate, and succinate (PMS) or palmitoyl carnitine and malate (PCM) was measured by high-resolution respirometry in permeabilized muscle fiber bundles. mRNA and protein levels were assessed by real time PCR and Western blotting.

RESULTS

H₂O₂ emission increased following the clamp (P<0.05). Coupled respiration (State 3) supported by PMS and the respiratory control ratio (index of mitochondrial coupling) for both PMS and PCM were lower following the clamp (P<0.05). IRS1 mRNA decreased, whereas PGC1α and GLUT4 mRNA increased following the clamp (P≤0.05). PGC1α, IRS1, and phosphorylated AKT protein levels were higher after the clamp compared to baseline (P<0.05).

CONCLUSIONS

This study demonstrated that acute hyperinsulinemia induced H₂O₂ production and a concurrent decrease in coupling of mitochondrial respiration with ATP production in a cohort of healthy premenopausal women. Future studies should determine if this uncoupling ameliorates peripheral oxidative damage, and if this mechanism is impaired in diseases associated with chronic oxidative stress.

Mechanisms by which cocoa flavanols improve metabolic syndrome and related disorders

Dietary administration of cocoa flavanols may be an effective complementary strategy for alleviation or prevention of metabolic syndrome, particularly glucose intolerance. The complex flavanol composition of cocoa provides the ability to interact with a variety of molecules, thus allowing numerous opportunities to ameliorate metabolic diseases. These interactions likely occur primarily in the gastrointestinal tract, where native cocoa flavanol concentration is high. Flavanols may antagonize digestive enzymes and glucose transporters, causing a reduction in glucose excursion, which helps patients with metabolic disorders maintain glucose homeostasis. Unabsorbed flavanols, and ones that undergo enterohepatic recycling, will proceed to the colon where they can exert prebiotic effects on the gut microbiota. Interactions with the gut microbiota may improve gut barrier function, resulting in attenuated endotoxin absorption. Cocoa may also positively influence insulin signaling, possibly by relieving insulin-signaling pathways from oxidative stress and inflammation and/or via a heightened incretin response. The purpose of this review is to explore the mechanisms that underlie these outcomes, critically review the current body of literature related to those mechanisms, explore the implications of these mechanisms for therapeutic utility, and identify emerging or needed areas of research that could advance our understanding of the mechanisms of action and therapeutic potential of cocoa flavanols.

In quest for method of insulin resistance assessment in everyday clinical practice-Insulin resistance indices

Insulin resistance (IR) a state of decreased sensitivity of target tissues to insulin is suspected usually in obese so can be overlooked in normal weight subjects thus it is important to find optimal method of IR assessment in clinical practice.

METHODS

HOMA, HOMA2, QUICKI, Matsuda index were calculated using data obtained from medical history of 130 female subjects - patients of the Department of Endocrinology and Metabolic Diseases, in whom oral glucose tolerance test (OGTT) with parallel insulin concentrations assessment was performed.

RESULTS

IR correlated positively with body mass index (BMI) in the entire study group, regardless which of four analyzed IR indices was used. Insulin resistance occurred in the obese as well as in normal weight and underweight subjects. The incidences of IR in the study group varied, depending upon chosen method and adopted cut-off values.

CONCLUSIONS

The need for quantitative assessment of IR in clinical practice is apparent. Proper selection of the best method of IR assessment remains a problem. HOMA appears the method of first choice for clinical use. There is an urgent need to establish universal or, at least, national standard cut-off values for IR, to introduce IR assessment in clinical practice.