Obesity as a Disease

Muscle fiber phenotype: a culprit of abnormal metabolism and function in skeletal muscle of humans with obesity

The proportion of the different types of fibers in a given skeletal muscle contributes to its overall metabolic and functional characteristics. Greater proportion of type I muscle fibers is associated with favorable oxidative metabolism and function of the muscle. Humans with obesity have a lower proportion of type I muscle fibers. We discuss how lower proportion of type I fibers in skeletal muscle of humans with obesity may explain metabolic and functional abnormalities reported in these individuals. These include lower muscle glucose disposal rate, mitochondrial content, protein synthesis, and quality/contractile function, as well as increased risk for heart disease, lower levels of physical activity, and propensity for weight gain/resistance to weight loss. We delineate future research directions and the need to examine hybrid muscle fiber populations, which are indicative of a transitory state of fiber phenotype within skeletal muscle. We also describe methodologies for precisely characterizing muscle fibers and gene expression at the single muscle fiber level to enhance our understanding of the regulation of muscle fiber phenotype in obesity. By contextualizing research in the field of muscle fiber type in obesity, we lay a foundation for future advancements and pave the way for translation of this knowledge to address impaired metabolism and function in obesity.

Effect of isgin (Rheum ribes L.) on biochemical parameters, antioxidant activity and DNA damage in rats with obesity induced with high-calorie diet

The present study was designed to investigate the effects of Rheum ribes L. plant root extracts on DNA damage, biochemical and antioxidant parameters in rats with experimental obesity induced with a high-calorie diet. The study groups were divided as "normal control(NC)", "obese control(OC)", "obese + Rheum ribes(OR1)(200 mg/kg)" and "obese + Rheum ribes (OR2)(400 mg/kg)". At the end of the application, rats were sacrificed and blood and tissue samples were obtained. According to the results obtained, the marker of DNA damage in tissues of 8-OHdG was determined to be significantly reduced in brain tissue of the OR1 and OR2 groups compared to the NC group. However, fluctuations were identified in the MDA activity, antioxidant defense system elements and serum biomarkers in tissues. In conclusion, Rheum ribes plant root extract ensured improvements in DNA damage in brain tissues and MDA levels and showed positive effects on antioxidant parameter activities in different tissues.

11β-HSD as a New Target in Pharmacotherapy of Metabolic Diseases

Glucocorticoids (GCs), which are secreted by the adrenal cortex, are important regulators in the metabolism of carbohydrates, lipids, and proteins. For the proper functioning of the body, strict control of their release is necessary, as increased GCs levels may contribute to the development of obesity, type 2 diabetes mellitus, hypertension, cardiovascular diseases, and other pathological conditions contributing to the development of metabolic syndrome. 11β-hydroxysteroid dehydrogenase type I (11β-HSD1) locally controls the availability of the active glucocorticoid, namely cortisol and corticosterone, for the glucocorticoid receptor. Therefore, the participation of 11β-HSD1 in the development of metabolic diseases makes both this enzyme and its inhibitors attractive targets in the pharmacotherapy of the above-mentioned diseases.

The Role of AMPK Signaling in Brown Adipose Tissue Activation

Obesity is becoming a pandemic, and its prevalence is still increasing. Considering that obesity increases the risk of developing cardiometabolic diseases, research efforts are focusing on new ways to combat obesity. Brown adipose tissue (BAT) has emerged as a possible target to achieve this for its functional role in energy expenditure by means of increasing thermogenesis. An important metabolic sensor and regulator of whole-body energy balance is AMP-activated protein kinase (AMPK), and its role in energy metabolism is evident. This review highlights the mechanisms of BAT activation and investigates how AMPK can be used as a target for BAT activation. We review compounds and other factors that are able to activate AMPK and further discuss the therapeutic use of AMPK in BAT activation. Extensive research shows that AMPK can be activated by a number of different kinases, such as LKB1, CaMKK, but also small molecules, hormones, and metabolic stresses. AMPK is able to activate BAT by inducing adipogenesis, maintaining mitochondrial homeostasis and inducing browning in white adipose tissue. We conclude that, despite encouraging results, many uncertainties should be clarified before AMPK can be posed as a target for anti-obesity treatment via BAT activation.

The association between total antioxidant capacity and resting metabolic rate (RMR) / respiratory quotient (RQ) in overweight and obese woman

OBJECTIVE

The effect of total antioxidant capacity on resting metabolic rate (RMR) and respiratory quotient (RQ) of overweight and obese woman has been debated globally. Total Antioxidant Capacity may have an independent effect on resting metabolic rate and respiratory quotient.

METHODS AND MATERIALS

A study population of 263 aged 18-50 years participated in this cross-sectional study from the communities of Tehran based on cluster sampling. Dietary intake assessed by using a semi quantitative food frequency questionnaire (FFQ) Demographic questions. Anthropometrics measurements for each participant were done. Dietary total antioxidant capacity (DTAC) was calculated by the 147-item food frequency questionnaire (FFQ) and FRAP assay. Resting metabolic rate and respiratory quotient was measured by Indirect calorimetry.

RESULTS

The mean DTAC of the study participants was 1251.8 (SD 893.60). There was a statistically significant relationship between dietary total antioxidant capacity (DTAC) and respiratory quotient (P > 0.013). People with high dietary total antioxidant capacity have tended to show a lower RQ than those with a lower one. There was a significant correlation between DTAC and RQ for both the adjusted model for age, total energy intake, BMI, physical activity, higher DTAC diet and the crude model which were (β = 0.011; SE = 0.005; CI = -0.021_0) and (β = -3.143E-6; SE = 0; CI = 0), respectively. However, we found no correlation between the DTAC and RMR/FFM-RES (P < 0.49). Also, a significantly higher relationship was demonstrated between dietary total antioxidant capacity and intake vegetables (P ≤ 0.006), fruits (P ≤ 0.009), white meet (P ≤ 0.03) and dairy products (P ≤ 0.005).

CONCLUSION

RQ is correlated with total antioxidant capacity. Increased intake of high DTAC foods may result in weight loss maintenance. This result may suggest a beneficial role of higher-DTAC diets in the prevention of obesity.

Effect of a high sucrose and high fat diet in BDNF (+/-) mice on oxidative stress markers in adipose tissues

The purpose of this study was to investigate the effects of a high fat and a high sucrosediet in wild type and BDNF (+/-) mice on oxidative stress in epididymal and subcutaneousadipose tissues by measuring different markers of oxidative stress and antioxidant enzymes. Wild type (WT) and BDNF (+/-) male mice were divided into six groups receiving fed control diet (CD), high sucrose diet (HSD), or high fat diet (HFD) for four months. Levels of 3-nitrotyrosine (3-NT) increased in the HFD-fed BDNF (+/-) mice, while 4-hydroxynonenal (4-HNE) levels increased in the CD and HFD-fed BDNF (+/-) groups. Malondialdehyde (MDA) levels decreased in subcutaneous tissue compared to epididymal adipose tissue, independently of diet type. Superoxide dismutase (SOD) activity was reduced by HFD (p < 0.05), butglutathione peroxidase (GSH-Px) activity was increased by HSD in epididymal adipose tissuein BDNF (+/-) mice (p < 0.05). GSH-Px activities was increased by CD and HFD in subcutaneous adipose tissue of BDNF (+/-) (p < 0.05). SOD2 and GSH-Px3 expressions were only decreased by HSD in epididymal and subcutaneous adipose tissues of BDNF (+/-) mice (p < 0.05). In conclusion, reduced BDNF may increase OS in epididymal adipose tissue, but not in subcutaneous adipose tissue following HSD and HFD.

Multimorbidity in Atlantic Canada and association with low levels of physical activity

Owing to an aging population and medical advances, the anticipated growth and prevalence of multimorbidity has been recognized as a significant challenge and priority in health care settings. Although physical activity has been shown to play a vital role in the primary and secondary prevention of chronic disease, much less is known about the relationship between physical activity and multimorbidity. The objective of the present study was to examine the relationship between physical activity levels and multimorbidity in male and female adults after adjusting for key demographic, geographical, and lifestyle factors. The study drew data from a prospective cohort in Atlantic Canada (2009-2015). The sample included 18,709 participants between the ages of 35-69. Eighteen chronic diseases were identified. Physical activity levels were estimated based on the long form of the International Physical Activity Questionnaire. Using logistic regression analysis, we found that multimorbid individuals were significantly more likely to be physically inactive (OR=1.26; 95% CI 1.10, 1.44) after adjusting for key sociodemographic and lifestyle characteristics. Additional stratified analyses suggest that the magnitude of the effect between multimorbidity and physical activity was stronger for men (OR=1.41; 95% CI 1.12, 1.79) than women (OR=1.18; CI 1.00, 1.39) and those living in rural (OR=1.43; CI 1.10, 1.85) versus urban (OR=1.20; CI 1.02, 141) areas. Given the generally low levels of physical activity across populations and a growing prevalence of multimorbidity, there is a need for a prospective study to explore causal associations between physical activity, multimorbidity, and health outcomes.