Silvio Assis de Oliveira-Junior

AT1 Receptor Blockade Attenuates Insulin Resistance and Myocardial Remodeling in Rats with Diet-Induced Obesity

Background Although obesity has been associated with metabolic and cardiac disturbances, the carrier mechanisms for these responses are poorly understood. This study analyzed whether angiotensin II blockade attenuates metabolic and cardiovascular disorders in rats with diet-induced obesity. Material and Methods Wistar-Kyoto (n = 40) rats were subjected to control (C; 3.2 kcal/g) and hypercaloric diets (OB; 4.6 kcal/g) for 30 weeks. Subsequently, rats were distributed to four groups: C, CL, OB, and OBL. L groups received Losartan (30 mg/kg/day) for five weeks. After this period we performed in vivo glucose tolerance and insulin tolerance tests, and measured triacylglycerol, insulin, angiotensin-converting enzyme activity (ACE), and leptin levels. Cardiovascular analyzes included systolic blood pressure (SBP), echocardiography, myocardial morphometric study, myosin heavy chain composition, and measurements of myocardial protein levels of angiotensin, extracellular signal-regulated (ERK1/2), c-Jun amino-terminal kinases (JNK), insulin receptor subunit β (βIR), and phosphatidylinositol 3-kinase (PI3K) by Western Blot. Results Glucose metabolism, insulin, lipid, and ACE activity disorders observed with obesity were minimized by Losartan. Moreover, obesity was associated with increased SBP, myocardial hypertrophy, interstitial fibrosis and improved systolic performance; these effects were also minimized with Losartan. On a molecular level, OB exhibited higher ERK, Tyr-phosphorylated βIR, and PI3K expression, and reduced myocardial angiotensin and JNK expression. ERK and JNK expression were regulated in the presence of Losartan, while angiotensin, Tyr-βRI, total and Tyr-phosphorylated PI3K expression were elevated in the OBL group. Conclusion Angiotensin II blockade with Losartan attenuates obesity-induced metabolic and cardiovascular changes.

Obesity Preserves Myocardial Function During Blockade of the Glycolytic Pathway

Background Obesity is defined by excessive accumulation of body fat relative to lean tissue. Studies during the last few years indicate that cardiac function in obese animals may be preserved, increased or diminished. Objective Study the energy balance of the myocardium with the hypothesis that the increase in fatty acid oxidation and reduced glucose leads to cardiac dysfunction in obesity. Methods 30-day-old male Wistar rats were fed standard and hypercaloric diet for 30 weeks. Cardiac function and morphology were assessed. In this paper was viewed the general characteristics and comorbities associated to obesity. The structure cardiac was determined by weights of the heart and left ventricle (LV). Myocardial function was evaluated by studying isolated papillary muscles from the LV, under the baseline condition and after inotropic and lusitropic maneuvers: myocardial stiffness; postrest contraction; increase in extracellular Ca2+ concentration; change in heart rate and inhibitor of glycolytic pathway. Results Compared with control group, the obese rats had increased body fat and co-morbities associated with obesity. Functional assessment after blocking iodoacetate shows no difference in the linear regression of DT, however, the RT showed a statistically significant difference in behavior between the control and the obese group, most notable being the slope in group C. Conclusion The energy imbalance on obesity did not cause cardiac dysfunction. On the contrary, the prioritization of fatty acids utilization provides protection to cardiac muscle during the inhibition of glycolysis, suggesting that this pathway is fewer used by obese cardiac muscle.

High-fat Diet Promotes Cardiac Remodeling in an Experimental Model of Obesity

Background Although nutritional, metabolic and cardiovascular abnormalities are commonly seen in experimental studies of obesity, it is uncertain whether these effects result from the treatment or from body adiposity. Objective To evaluate the influence of treatment and body composition on metabolic and cardiovascular aspects in rats receiving high saturated fat diet. Methods Sixteen Wistar rats were used, distributed into two groups, the control (C) group, treated with isocaloric diet (2.93 kcal/g) and an obese (OB) group, treated with high-fat diet (3.64 kcal/g). The study period was 20 weeks. Analyses of nutritional behavior, body composition, glycemia, cholesterolemia, lipemia, systolic arterial pressure, echocardiography, and cardiac histology were performed. Results High-fat diet associates with manifestations of obesity, accompanied by changes in glycemia, cardiomyocyte hypertrophy, and myocardial interstitial fibrosis. After adjusting for adiposity, the metabolic effects were normalized, whereas differences in morphometric changes between groups were maintained. Conclusions It was concluded that adiposity body composition has a stronger association with metabolic disturbances in obese rodents, whereas the high-fat dietary intervention is found to be more related to cardiac morphological changes in experimental models of diet-induced obesity.

Effects of late exercise on cardiac remodeling and myocardial calcium handling proteins in rats with moderate and large size myocardial infarction

BACKGROUND Physical exercise attenuates myocardial infarction (MI)-induced cardiac remodeling. However, it is unsettled whether late exercise modulates post-infarction cardiac remodeling differentially according to infarct size. We investigated the effects of exercise started at late stage heart failure on cardiac remodeling in rats with moderate and large sized MI. METHODS Three months after MI, rats were assigned into sedentary and exercise groups. Exercise rats underwent treadmill for three months. After assessing infarct size by histological analysis, rats were subdivided into four groups: moderate MI sedentary (Mod MI-Sed; n=7), Mod MI exercised (Mod MI-Ex; n=7), Large MI-Sed (n=11), and Large MI-Ex (n=10). RESULTS Before exercise, MI-induced cardiac changes were demonstrated by comparing results to a Sham group; alterations were more intense in rats with large than moderate MI size. Systolic function, evaluated by echocardiogram using the variation in LV fractional area change between after and before exercise, was improved in exercise than sedentary groups. Calsequestrin expression increased in exercised compared to sedentary groups. L-type calcium channel was higher in Mod MI-Ex than Mod MI-Sed. SERCA2a, phospholamban, and Na(+)/Ca(2+) exchanger expression did not differ between groups. CONCLUSION Late exercise improves systolic function and modulates intracellular calcium signaling proteins in rats with moderate and large MI.

Autonomic modulations of heart rate variability are associated with sports injury incidence in sprint swimmers

ABSTRACT Objectives: Young athletes’ participation in competitive sports is becoming increasingly common, and this increased involvement raises concerns about the occurrence of overtraining and sports injuries. Since these issues are poorly understood, this study analyzed heart rate variability, stress/recovery relationship, and sports injury incidence during a training macrocycle of young sprint and endurance swimmers. Methods: Thirty teenage swimmers (aged 12 to 17 years) were divided into two groups as follows: Sprint (n = 17) and Endurance (n = 13). Subjects were evaluated over 20 weeks, based on the following three schedules: general, specific, and competitive. In addition to heart rate variability and sports injury incidence, the Recovery-Stress-Questionnaire of Athletes was used to analyse stress/recovery states in athletes. All procedures were developed at the initial moment and at the end of each periodization step. Results: The Sprint group presented a reduced standard deviation of normal-normal beats (73.0 ± 6.6 vs. 54.1 ± 3.5 ms; p < 0.05) and root mean square of the successive differences (55.3 ± 6.2 vs. 42.0 ± 3.7 ms; p < 0.01) from the period of general preparation until the time of competition. Recovery-stress monitoring was affected only by the swimming training periodization (p < 0.05). During the general period, differences between recovery and stress scales were correlated directly with the root mean square of the successive differences (r = 0.576; p = 0.001), the standard deviation of instantaneous variability beat-to-beat (r = 0.521; p = 0.003) and the triangular index (r = 0.476; p = 0.008). Differences between general recovery and stress scales were inversely correlated with geometric indexes after the specific training period. Moreover, the Sprint group showed a higher incidence of sports injury than the Endurance group (0.0214 ± 0.0068 vs. 0.0136 ± 0.0050 cases/1000 hours). Conclusion: Sprint training was associated with progressive activation of the sympathetic nervous system as well as a higher incidence of sports injury in comparison to endurance swimming during a training macrocycle.

Association between echocardiographic structural parameters and body weight in Wistar rats

Background The association between echocardiographic structural parameters and body weight (BW) during rat development has been poorly addressed. We evaluated echocardiographic variables: left ventricular (LV) end-diastolic (LVDD) and end-systolic (LVSD) diameters, LV diastolic posterior wall thickness (PWT), left atrial diameter (LA), and aortic diameter (AO) in function of BW during development. Results/Materials and Methods Male Wistar rats (n = 328, BW: 302–702 g) were retrospectively used to construct regression models and 95% confidence intervals relating to cardiac structural parameters and BW. Adjusted indexes were significant to all relationships; the regression model for predicting LVDD (R2 = 0.678; p < 0.001) and AO (R2 = 0.567; p < 0.001) had the highest prediction coefficients and LA function the lowest prediction coefficient (R2 = 0.274; p < 0.01). These relationships underwent validation by performing echocardiograms on additional rats (n = 43, BW: 300–600 g) and testing whether results were within confidence intervals of our regressions. Prediction models for AO and LA correctly allocated 38 (88.4%) and 39 rats (90.7%), respectively, within the 95% confidence intervals. Regression models for LVDD, LVSD, and PWT included 27 (62.7%), 30 (69.8%), and 19 (44.2%) animals, respectively, within the 95% confidence intervals. Conclusions Increase in cardiac structures is associated with BW gain during rat growth. LA and AO can be correctly predicted using regression models; prediction of PWT and LV diameters is not accurate.

Could current factors be associated with retrospective sports injuries in Brazilian jiu-jitsu? A cross-sectional study

BackgroundBrazilian jiu-jitsu is characterized by musculoskeletal disorders and high occurrence of sports injuries. The present study was aimed to analyze some internal factors, as well as to describe occurrence and characteristics of retrospective musculoskeletal injuries in different age groups of Brazilian jiu-jitsu practitioners.MethodsOne hundred ninety-three Brazilian jiu-jitsu practitioners, which were divided into three age groups: Adolescent, Adult, and Master. Besides anthropometric characterization, standard clinical tests were conducted to analyze the global and segmental joint flexibility, lumbar spine range of motion, and handgrip strength. Sports injury occurrence and total physical activity were obtained from an adapted morbidity survey and International Physical Activity Questionnaire - Short Form (IPAQ-SF), respectively.ResultsA total of 247 cases of retrospective injuries was registered (1.27 injury/ participant). Occurrence of rectus femoral muscle retraction in the right leg was increased within Master. Adult and Master have exhibited higher occurrence of sports injuries than Adolescent group (p < 0.05). Joint injuries were the most common sports-related injuries by all Brazilian jiu-jitsu practitioners. While female gender and exposure time constituted the most predictive variables for sports injury occurrence in Adolescent, graduation level was more associated with sports injuries occurrence in Adult.ConclusionsJoint injuries derived from combat demands were the main sports injury in all age categories of Brazilian jiu-jitsu. Master subjects presented a higher occurrence of clinical changes and retrospective musculoskeletal injuries in relation to other age groups. Female gender and exposure time constituted the main predictive factors in adolescent subjects, while graduation category was more directly associated with retrospective injury onset in the Adult group.

Sports injuries in soccer according to tactical position: a retrospective survey

Introduction: In soccer, the players’ positions have been associated with specific functional overload, which may cause sports injuries. Objective: To investigate the occurrence and characterize sport injuries according to soccer player position. Methods: 232 male soccer players (129 professionals and 103 amateurs) from different sport teams in Mato Grosso do Sul, Brazil, were distributed in groups according to their soccer player position. Besides anthropometric characteristics, sports injuries were registered by using a referred morbidity survey. The occurrence of injuries was analyzed by means of the Goodman Test. Logistic regression models were used to investigate the relationship between different risk factors and the occurrence/-recurrence of sports injuries. Results: Forwards showed higher occurrence rates of sport injuries than other soccer position groups. Joint injuries in lower limbs constituted the most frequent registered cases. Muscle injuries in the back region were the most registered sports injuries among midfielders, while muscle damages in lower limbs were the primary injuries registered for other line positions. In the etiologic context, contact was the main cause of sports injuries in all groups. Most athletes (195) reported recurrence of sports injuries. Conclusion: The occurrence of sports injuries was higher among forwards. Traumatic joint and muscle injuries were the most prevalent registers in all line positions.