The effect of caffeine supplementation on trained individuals subjected to maximal treadmill test

Background: Intense physical training increases oxidative stress and inflammation, resulting into muscle and cellular damage. The aim of this study was to analyze the effect of caffeine supplementation on trained young individuals subjected to two treadmill maximal tests.Materials and Methods: It was a double-blind and crossover study comprising 24 active individuals within the age group 18-30 years. The comparisons were conducted: the effect of exercise (week 1 x 2) and caffeine intake (GC x GP) on thiobarbituric acid (TBARS), interleukin 6 (IL-6), interleukin 10 (IL-10) and superoxide dismutase (SOD) variables during pre-exercise time (30 min. after caffeine or placebo intake) and post-exercise (5 min after treadmill test).Results: The comparison between weeks 1 and 2 showed increase in the first week, in the following items: TBARS, IL-6 and IL-10 in the GC and GP groups. The comparison within the same week showed that GC individuals presented lower post-exercise TBARS values in the first and second weeks; IL- 6 presented higher post-exercise values in the GC group in both weeks. The paired analysis comparing pre- and post-exercise, with and without caffeine showed that IL-6 presented higher post-exercise values in the GC group.Conclusion: Caffeine used by athletes can decrease oxidative stress. The increased IL-6 suggest that this ergogenic supplement may stimulate muscle hypertrophy, since IL-6 has myokine effect. However, the caffeine effect on IL-6 level and muscle hypertrophy increase should be better investigated in future studies.Keyword: Caffeine; Exercise; Interleukin; Oxidative stres

Ãndice glicêmico e carga cligêmica de dietas de atletas

Background: Glycemic Index (GI) and Glycemic Load (GL) have been used as tools for choosing diet as a health reference, and especially for athletes, with the purpose of improving physical performance. However, little is known about the GI and GL in the diet of athletes from different sports. Aim: Investigate the GI and GL in the diet of Brazilian athletes. Methods: Cross sectional study conducted with 113 athletes (18.4 ± 6.6 years, 22.3 ± 3.2kg/m2, 13.6 ± 7.0 % body fat, and 12.0 ± 6.9 hours of weekly training). Bioelectrical impedance was used to assess percentage body fat and anthropometric measurements were evaluated. Food consumption was assessed through the 24-hour dietary recall, GI and GL were calculated based on previously established procedures. The Mann-Whitney U test and Kruskal-Wallis test were used for statistical analysis. Results: There was no statistical difference in training volume, macronutrient intake, total calories, GI among men and women (P > 0.05). The GL was lower in women´s diets and was different among sports. High GL diets presented lower percentage of body fat than moderate GL (P< 0.05). Conclusion: The majority of the athletes presented a diet with a low GI and high GL. Differences were found between GL classification and modalities and body fat. Further studies are required to better elucidate the effects of these dietary glycemic properties on body composition and physical performance.Introdução: Ãndice Glicêmico (IG) e Carga Glicêmica (CG) têm sido utilizados como ferramenta de escolha da dieta para melhorar o desempenho físico. No entanto, pouco se sabe sobre a aplicabilidade do consumo pelos atletas de diferentes modalidades. Objetivo: Analisar o IG e a CG da dieta de atletas brasileiros. Métodos: Estudo transversal conduzido com 113 atletas (18,4 ± 6,6 anos, 22,3 ± 3,2kg/m2, 13,6 ± 7,0 % percentual de gordura corporal e 12,0 ± 6,9 horas de treinamento semanal). Para avaliar o percentual de gordura foi utilizado uma bioimpedância elétrica e também foi realizado medidas antropométricas. O consumo alimentar foi avaliado por meio do recordatório de 24 horas. Calculou-se IG e CG da dieta utilizando seguindo procedimentos previamente estabelecidos. O teste Mann-Whitney U e o teste de Kruskal-Wallis foram usados para as análises estatísticas. Resultados: Não houve diferença estatisticas no volume de treinamento, na ingestão de macronutrientes, no total de calorias e no IG entre homens e mulheres (P >0,05). A CG foi menor nas mulheres e diferentes entre os esportes. As dietas de alta CG apresentaram baixo percentual de gordura corporal do que as dietas de moderada CG (P <0,05). Conclusão: A maioria dos atletas apresentou dieta com baixo IG e alta CG. Houve diferenças entre a classificação da CG, as modalidades e o percentual de gordura corporal. Mais estudos são necessários para elucidar os efeitos da CG e do IG na composição corporal e no desempenho físico

THE EFFECT OF CAFFEINE SUPPLEMENTATION ON TRAINED INDIVIDUALS SUBJECTED TO MAXIMAL TREADMILL TEST.

Background: Intense physical training increases oxidative stress and inflammation, resulting into muscle and cellular damage. The aim of this study was to analyze the effect of caffeine supplementation on trained young individuals subjected to two treadmill maximal tests. Materials and Methods: It was a double-blind and crossover study comprising 24 active individuals within the age group 18-30 years. The comparisons were conducted: the effect of exercise (week 1 x 2) and caffeine intake (GC x GP) on thiobarbituric acid (TBARS), interleukin 6 (IL-6), interleukin 10 (IL-10) and superoxide dismutase (SOD) variables during pre-exercise time (30 min. after caffeine or placebo intake) and post-exercise (5 min after treadmill test). Results: The comparison between weeks 1 and 2 showed increase in the first week, in the following items: TBARS, IL-6 and IL-10 in the GC and GP groups. The comparison within the same week showed that GC individuals presented lower post-exercise TBARS values in the first and second weeks; IL- 6 presented higher post-exercise values in the GC group in both weeks. The paired analysis comparing pre- and post-exercise, with and without caffeine showed that IL-6 presented higher post-exercise values in the GC group. Conclusion: Caffeine used by athletes can decrease oxidative stress. The increased IL-6 suggest that this ergogenic supplement may stimulate muscle hypertrophy, since IL-6 has myokine effect. However, the caffeine effect on IL-6 level and muscle hypertrophy increase should be better investigated in future studies

Modulation of the defense mechanism of pancreatic islets against oxidative stress

Orientador: Antonio Carlos BoscheroTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: No diabetes mellitus, radicais de oxigênio estão associados com perda de sensibilidade à glicose ou destruição das células b. Nesse trabalho, investigamos a tolerância de ilhotas de Langerhans de ratos neonatos ao estresse provocado por H2O2, seus mecanismos antioxidantes de defesa e os fatores que promovem manutenção da sensibilidade à glicose. Cultivadas com 1 mM de H2O2, as ilhotas aumentaram até 6' seu consumo de glicose e resistiram ao estresse induzido por H2O2 quando em meio contendo 20 mM de glicose. A expressão da enzima catalase em resposta à glicose se mostrou necessária a essa resistência, mas não suficiente. Em concentrações baixas de H2O2, quando a catalase tem sua atividade modulada por NADPH, observamos que mesmo proteínas sem atividade catalítica adquiriam capacidade antioxidante e eram regeneradas por NADPH. Mapeando a distribuição de atividade peroxidase na ilhota, observamos sensibilidade ao NADPH nas frações nuclear e citossólica. As ilhotas cultivadas em 20 mM de glicose e as que resistem ao H2O2 possuem em comum uma maior atividade da via das pentoses, que gera NADPH citossólico. Nessas ilhotas, verificamos que a produção citossólica de NAD(P)H limita a secreção de insulina. Tais ilhotas produzem NAD(P)H principalmente da oxidação de substratos endógenos no citossol e nas mitocôndrias, ao invés de localizarem seu uso somente no citossol, como se dá nas ilhotas mais sensíveis ao H2O2. A cultura com 20 mM de glicose produziu ilhotas com alta expressão da lançadeira de NADH glicerol-fosfato, enquanto o H2O2 selecionou ilhotas com alta expressão da lançadeira mal/asp. Como ambas as lançadeiras promovem a comunicação entre citossol e mitocôndrias, concluímos que o sistema de lançadeiras e a geração de NADPH sejam fatores críticos para a manutenção da sensibilidade à glicose nas ilhotasAbstract: In diabetes mellitus, oxygen radicals are associated with loss of glucose-sensibility and destruction of b-cells. In this work, we investigated the tolerance of neonatal rat islets to stress induced by H2O2, the islets antioxidant defense mechanism and factors maintaining islet glucoseresponsiveness. Islets cultured with 1 mM of H2O2 increased 6 fold the glucose uptake and resisted H2O2-induced stress when cultured in media containing 20 mM of glucose. Glucose-induced catalase expression was shown to be necessary to islet cell-survival, although not sufficient. In low H2O2 concentrations, the activity of catalase is dependent on NADPH and we observed that even proteins with no catalytic activity could be antioxidants regenerated by NADPH. Mapping the peroxidase activity in islets, we observed sensibility to NADPH in nuclear and cytossolic fractions. Islets cultured with 20 mM of glucose and islets that survived after culture with H2O2 both showed increased activity of the pentose phosphate pathway, which generate cytossolic NADPH. Is theses islets, we verified that cytossolic production of NAD(P)H limits insulin secretion. Such islets generate NAD(P)H principally from oxidation of endogenous fuels in cytossol and mitochondria, in contrary of the most H2O2-sensible islets which use endogenous fuels exclusively in cytossol. Culture with 20 mM of glucose produced islets with high expression of the glycerol-phosphate NADH shuttle, where as culture with H2O2 selected islets with high expression of the mal/asp shuttle. Since both shuttles promote interchange between cytossol and mitochondria, we have concluded that the shuttle system together with NAD(P)H generation ability are critical factors in maintaining islet glucoseresponsivenessDoutoradoFisiologiaDoutor em Biologia Funcional e Molecula

Prevalence and factors associated with depression in the elderly: a cross-sectional study

Introdução: Depressão é uma doença psiquiátrica e provoca prejuízos no aspecto biopsicossocial dos indivíduos acometidos. Sua prevalência na população idosa é expressiva, a identificação dos fatores relacionados a este desfecho permitem que medidas preventivas e de tratamento sejam aplicadas precocemente. Objetivo: Avaliar a associação entre depressão, os fatores sociodemográficos e os riscos para a saúde em idosos. Métodos: Estudo transversal com 388 idosos de ambos os sexos com idade igual ou superior a 65 anos, residentes do município de Cuiabá, estado de Mato Grosso (MT), Brasil. Foram usados questionários sociodemográficos, instrumentos de autorrelato de doenças crônicas, de estilo de vida, ocorrência de quedas e de capacidade funcional, escala de depressão geriátrica, avaliação do estado mental e testes de antropometria. Na análise estatística utilizou-se teste do qui-quadrado, odds ratio (OR) e regressão logística múltipla com intervalo de confiança de 95% e p<5%. Resultados: Encontrou-se predominância de mulheres (64%), sendo mulata/cabocla/parda (43%) e casadas (45%). A depressão foi significativamente associada com: o tercil mais baixo de educação <8 anos (OR=2,15; p=0,012); com dependência parcial ou total de atividades instrumentais da vida diária (OR=1,85; p=0,003); ter cinco ou mais doenças crônicas (OR=2,93; p=0,002), ocorrência de quedas nos últimos doze meses (OR=1,90; p=0,021); dificuldades de sono (OR=2,39; p<0,001) e visual (OR=2,28; p<0,001). Conclusão: A depressão estava associada a fatores modificáveis e que podem ser prevenidos. Desta forma, o diagnóstico precoce destes fatores de risco, a inclusão de atividades socias, físicas e cognitivas devem ser consideradas para sua prevenção.Introduction: Depression is a psychiatric disease that causes losses in the biopsychosocial aspect of the affected individuals. The prevalence in the elderly population is significant, and identify the factors related to this outcome allows preventive measures and treatment can be early applied. Objective: Assessing the association between depression and sociodemographic and health risk factors in the elderly. Methods: This is a cross-sectional study involving 388 elderly of both genders, aged 65 years and older, urban residents of the city of Cuiabá, state of Mato Grosso (MT), Brazil. A sociodemographic questionnaire, as well as a self-report of chronic diseases and lifestyle, a self-report questionnaire of functional capacity, occurrence of falls, Geriatric Depression Scale, mental state assessment, and anthropometry tests were used. The chi-square test, odds ratio (OR), and multiple logistic regression with 95% confidence interval and p<5% were used in the statistical analysis. Results: There was a predominance of women (64%) who were mulatto/caboclo/brown skin (43%) and married (45%). Depression was significantly associated with: the lowest level of education, <8 years (OR=2.15; p=0.012), partial or total dependence of instrumental activities of daily living (OR=1.85; p=0.003), having five or more diseases (OR=2.93, p=0.002), falls in the last twelve months (OR=1.90; p=0.021), and sleep (OR=2.39; p<0.001) and visual difficulties (OR=2.28; p<0.001). Conclusion:  Depression in this group of elderly was associated with modifiable and preventable factors in the health of these people. Thus, the early diagnosis of risk factors associated with depression, the inclusion of social, physical and cognitive activities must be considered for their prevention

Characterization of the insulinotropic action of a phospholipase A2 isolated from Crotalus durissus collilineatus rattlesnake venom on rat pancreatic islets

The ability of PLA2 and crotapotin, isolated from Crotalus durissus collilineatus rattlesnake venom, to stimulate insulin secretion from isolated rat islets was examined. PLA2 and crotapotin stimulated insulin secretion at 2.8 mmol/L glucose, whereas at a high glucose concentrations (16.7 mmol/L) only PLA2 stimulated secretion. Nifedipine (10 micromol/L) did not alter the ability of PLA2 to increase insulin secretion stimulated by a depolarizing concentration of K+ (30 mmol/L). PLA2 did not affect 14CO2 production but significantly increased the efflux of arachidonic acid from isolated islets. These results indicate that PLA2-stimulated secretion is not dependent on an additional influx of Ca2+ through L-type Ca(2+)-channels but rather is associated with arachidonic acid formation in pancreatic islets.status: publishe

Decreased Insulin Secretion In Islets From Rats Fed A Low Protein Diet Is Associated With A Reduced Pkaalpha Expression.

A low protein diet has been shown to affect the amount and activity of several enzymes and to decrease insulin secretion by islets isolated from rats fed such a diet. To understand the mechanisms involved in this phenomenon, we investigated the effects of forskolin, a stimulator of adenylyl cyclase, on insulin secretion by pancreatic islets from rats fed a normal (17%; NP) or low (6%; LP) protein diet for 8 wk. Isolated islets were incubated for 1 h in Krebs-bicarbonate solution containing 8.3 mmol glucose/L, with or without 10 micromol forskolin/L. The forskolin-induced insulin secretion was higher in islets from NP rats than in those from LP rats (P<0.05). Western blotting revealed that the amount of the alpha catalytic subunit of protein kinase A (PKAalpha) was 35% lower in islets from LP rats than in islets from NP rats (P<0.05). Moreover, PKAalpha mRNA expression was reduced by 30% in islets from LP rats (P<0.05). Our results indicated a possible relationship between a low protein diet and a reduction in PKAalpha expression. These alterations in PKAalpha may be responsible in part for the decreased insulin secretion by islets from rats fed a low protein diet.13463-