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Caffeine Enhances the Calcium-Dependent Cardiac Mitochondrial Permeability Transition: Relevance for Caffeine Toxicity

Sardão, Vilma A.; Oliveira, Paulo J.; Moreno, António J. M.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
37.2%
Caffeine (1,3,7-trimethylxanthine), a compound present in beverages such as tea and coffee, is known to be toxic at high concentrations. Some of the observed clinical conditions include cardiovascular disease and reproductive disorders, among others. The possible toxic effects of caffeine on heart mitochondria are still poorly understood. The influence of caffeine on the mitochondrial permeability transition has not been clarified so far. The objective of this study was to investigate whether caffeine, at toxic concentrations, had any stimulating effect on the permeability transition of heart mitochondria isolated from Wistar rats, as well as whether it influenced mitochondrial respiratory parameters. Our results show that caffeine reduced mitochondrial ability to accumulate calcium by increasing the susceptibility of heart mitochondria to the opening of the transition pore. Caffeine not only hindered mitochondrial capacity to recover membrane potential after calcium addition but also increased the rate of calcium-dependent mitochondrial swelling and calcium-induced calcium release. The increased swelling was also observed in nonenergized mitochondria. Caffeine also showed a complex array of effects on heart mitochondrial bioenergetics...

Influence of caffeine on the survival of leaf-cutting ants Atta sexdens rubropilosa and in vitro growth of their mutualistic fungus

Miyashira, Carlos H.; Tanigushi, Daniel G.; Gugliotta, Adriana M.; Santos, Deborah Yara Alves Cursino dos
Fonte: WILEY-BLACKWELL; MALDEN Publicador: WILEY-BLACKWELL; MALDEN
Tipo: Artigo de Revista Científica
ENG
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BACKGROUND: Leaf-cutting ants collect plant fresh material for the cultivation of their mutualistic fungus. Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) cause great economic losses through their foraging activity, mainly in agriculture. The main control method is the application of granulated toxic baits incorporated with an active ingredient (AI). The present goal is to evaluate the effect of caffeine on in vitro growth of the mutualistic fungus and on the survival of the leaf-cutting ants, aiming to verify the potential toxicity of this secondary metabolite over these organisms. RESULTS: Three distinct patterns of fungal growth correlated with caffeine concentration were observed: (1) no effect (0.01% caffeine); (2) intermediate growth reduction (0.05% caffeine); (3) drastic growth reduction (0.10 and 0.50% caffeine). The highest caffeine concentration causes fungus death in the first week. As for insect survival, caffeine does not seem to exert any effect. The treatments with diet containing caffeine showed similar values of M50, irrespective of caffeine concentration. CONCLUSION: As caffeine was shown to reduce growth of the mutualistic fungus of Atta sexdens rubropilosa, but with no conclusive effect on insect survival...

Cafeína e desempenho em atividade de endurance?; Does caffeine maximize endurance exercise performance?

Souza Junior, Tácito Pessoa de; Capitani, Caroline Dario; Loturco Filho, Irineu; Viveiros, Luis; Aoki, Marcelo Saldanha
Fonte: Itaperuna Publicador: Itaperuna
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
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A cafeína é frequentemente consumida por atletas, por causa dos seus possíveis efeitos ergogênicos. É preconizado que a cafeína maximize a performance por agir, independentemente, ou concomitamente, através de 3 mecanismos: 1) aumento da mobilização do cálcio intracelular, 2) aumento na oxidação de ácidos graxos livres e 3) antagonista do receptor de adenosina no sistema nervoso central. Estudos iniciais sugeriram que o efeito ergogênico da cafeína estava relacionado ao aumento da oxidação de ácidos graxos e a consequente redução da glicogenólise. Entretanto, estudos mais recentes indicam que a cafeína maximiza o desempenho de endurance, principalmente, pelos seus efeitos antagônicos sobre os receptores de adenosina no sistema nervoso. Atuando através deste mecanismo, a cafeína poderia modular a fadiga central, influenciar a percepção subjetiva de esforço, a sensação de dor e o nível de vigor, que poderiam levar ao aumento do desempenho físico. A maioria das pesquisas tem utilizado protocolos de ingestão 60 minutos antes do teste de desempenho, a fim de assegurar a ótima absorção. Entretanto, tem sido demonstrado que a cafeína também melhorar a performance quando consumida de 15 a 30 minutos antes do teste. A utilização da cafeína na forma anidra...

Determinação voltamétrica simultânea de paracetamol e cafeína e de ácido ascórbico e cafeína em formulações famacêuticas empregando um eletrodo de diamante dopado com boro; Simultaneous voltammetric determination of paracetamol and caffeine and ascorbic acid and caffeine in pharmaceutical formulations using a boron doped diamond electrode

Lourenção, Bruna Cláudia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/02/2010 PT
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Neste trabalho descreve-se o desenvolvimento de procedimentos eletroanalíticos para a determinação de paracetamol, ácido ascórbico (AA) e cafeína em formulações farmacêuticas utilizando um eletrodo de diamante dopado com boro (BDD) e voltametria de pulso diferencial (DPV). Inicialmente, foram obtidos os voltamogramas cíclicos para o paracetamol, AA e cafeína separadamente sendo os potenciais de pico anódicos de oxidação de cada um destes analitos iguais a 0,80 V, 0,92 V e 1,47 V, respectivamente. O efeito do pré-tratamento eletroquímico do eletrodo de BDD nas medidas voltamétricas foi também objeto de estudo. Os parâmetros da voltametria de onda quadrada e voltametria de pulso diferencial também foram estudados e otimizados para cada analito. No primeiro procedimento desenvolvido, determinou-se simultaneamente paracetamol e cafeína em formulações farmacêuticas utilizando o eletrodo de BDD e voltametria de pulso diferencial após a otimização das condições experimentais. A curva analítica foi linear no intervalo de concentração de paracetamol e cafeína de 5,0 × 10-7 mol L-1 a 8,3 × 10-5 mol L-1 com limite de detecção iguail a 4,9 × 10-7 mol L-1 para paracetamol e 3,5 × 10-8 mol L-1 para cafeína. O desvio padrão relativo do paracetamol e da cafeína para a repetibilidade intra-dias foi de 0...

Efeito da cafeína na detecção de isquemia à cintilografia de perfusão miocárdica associada ao estresse com adenosina; Effects of caffeine on ischemia detection in myocardial perfusion scyntigraphy induced by adenosine stress

Reis, Lais Vissotto Garchet Santos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/12/2010 PT
Relevância na Pesquisa
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A utilização da cintilografia de perfusão miocárdica (CPM) estava limitada a pacientes que podiam realizar algum tipo de exercício, para ampliarmos a disponibilidade clínica da CPM, vários protocolos com estresses farmacológicos foram desenvolvidos. A adenosina fármaco amplamente utilizado, potente vasodilatador coronariano, apresenta uma importante interação com outras substâncias que anatagonizam seus efeitos, o dipiridamol, alimentos com cafeína e derivados de xantinas. O tempo de suspensão de cafeína da dieta para o uso exógeno da adenosina na realização da CPM ainda não está definido. Para testar essa hipótese avaliamos a influência da abstinência de cafeína em 24h, 12h e 1h, através de sua dosagem sérica, antes do estresse farmacológico com adenosina e sua possível repercussão nas imagens da CPM e o efeito vasodilatador no sistema cardiovascular. Definimos como objetivo primário: comparar a presença e a extensão dos defeitos reversíveis da CPM verificados em pacientes com abstinência de café por 24 horas (E1) com as imagens da randomização com 1 hora e 12 horas (E2) sem cafeína e como objetivos secundários: avaliar a presença e intensidade dos paraefeitos, comportamento da frequência cardíaca e da pressão arterial sistêmica. Foram submetidos ao estresse farmacológico com adenosina 194 pacientes para a realização da CPM...

Níveis plasmáticos de cafeína no cordão umbilical e apneia da prematuridade; Serum levels of caffeine in umbilical cord and apnea of prematurity

Hentges, Claudia Regina; Guedes, Renato Rostirola; Silveira, Rita de Cássia dos Santos; Procianoy, Renato Soibelmann
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
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Objetivo: Determinar a influência da presença de cafeína no sangue de cordão umbilical na ocorrência de apneia. Métodos: Estudo de coorte prospectivo de recém-nascidos pré-termo com peso de nascimento menor que 2.000 g. Os critérios de exclusão foram: mães que receberam opioides; ventilação mecânica durante os primeiros 4 dias de vida; malformações cerebrais e cardíacas maiores; asfixia perinatal; hemorragia peri-intraventricular grave; exsanguineotransfusão antes do quarto dia de vida; e uso de metilxantina antes da extubação. Os recém-nascidos foram divididos em com e sem cafeína detectável no sangue de cordão umbilical, sendo acompanhados nos primeiros 4 dias para verificar ocorrência de apneia. Resultados: Oitenta e sete recém-nascidos com e 40 sem cafeína detectável no sangue de cordão umbilical foram estudados. A mediana da concentração de cafeína dos 87 pacientes com cafeína detectável no sangue de cordão umbilical foi 2,3 μg/mL (0,2-9,4 μg/mL). Não houve associação entre ocorrência de apneia e presença de cafeína no sangue de cordão umbilical. Recém-nascidos com cafeína detectável no cordão umbilical tiveram tendência a apresentar apneia mais tardiamente (66,3±4,14 horas) do que aqueles com níveis indetectáveis (54...

Caffeine effect on mortality and oviposition in successive generations of Aedes aegypti

Laranja, Alessandra Theodoro; Manzato, Antonio José; Bicudo, Hermione Elly Melara de Campos
Fonte: Universidade de São Paulo (USP), Faculdade de Saúde Pública Publicador: Universidade de São Paulo (USP), Faculdade de Saúde Pública
Tipo: Artigo de Revista Científica Formato: 1112-1117
ENG
Relevância na Pesquisa
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OBJETIVO: Experimentos anteriores mostraram que a cafeína bloqueia o desenvolvimento de Aedes aegypti (Diptera, Culicidae) na fase larval, inibindo conseqüentemente a produção de adultos. O objetivo do estudo foi obter dados que pudessem sugerir desenvolvimento de resistência dos mosquitos à cafeína. MÉTODOS: Foi avaliada a produção de adultos em gerações sucessivas, a partir de ovos produzidos na geração anterior e a taxa de oviposição em cada geração, utilizando meios contendo cafeína a 200 e 500 µg/ml e água de torneira proveniente de poço artesiano como controle. Os experimentos foram conduzidos em São José do Rio Preto, entre 2002 e 2005. Nos testes estatísticos foram utilizados a análise exploratória de dados e algoritmos de alisamento. RESULTADOS: Ocorreu redução crescente da produção de adultos, nas duas concentrações, ao longo das gerações, mas apenas no experimento a 200 µg/ml os dados foram estatisticamente significantes. Quanto à oviposição, a análise dos números mostra redução crescente e acentuada na média de ovos por fêmea, no experimento tratado. CONCLUSÕES: Não houve evidência de resistência ao longo das gerações devido ao tratamento com cafeína. Os resultados encontrados podem reforçar a indicação da cafeína como uma alternativa aos principais agentes de controle do Ae. aegypti atualmente usados...

Prevention of rat liver fibrosis and carcinogenesis by coffee and caffeine

Furtado, Kelly S.; Polletini, Jossimara; Dias, Marcos C.; Rodrigues, Maria A. M.; Barbisan, Luis F.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 20-26
ENG
Relevância na Pesquisa
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 08/50985-5; Processo FAPESP: 07/54858-5; Processo FAPESP: 09/50890-7; Coffee has been inversely related to the incidence of human liver disease; however, whether caffeine is the component responsible for the beneficial effects of coffee remains controversial. This study evaluated the beneficial effects of coffee or caffeine in a medium-term bioassay for rat liver fibrosis/carcinogenesis induced by diethylnitrosamine (DEN) and carbon tetrachloride (CCl4). One week after the DEN injection, the groups started to receive conventional coffee, instant coffee or 0.1% caffeine ad libitum for 24 weeks. The groups receiving conventional coffee or caffeine presented a significant reduction in collagen content and mRNA expression of collagen I. The groups receiving instant coffee or caffeine had a significant reduction in the size and area of pre-neoplastic lesions and in the mean number of neoplastic lesions. A significant increase in liver bax protein levels was observed in the groups receiving instant coffee or caffeine as compared to the control group. These data indicate that the most pronounced hepatoprotective effect against fibrosis was observed in the groups receiving conventional coffee and 0.1% caffeine...

Teores de metilxantinas e metabolismo de cafeína em frutos de guaraná (Paullinia cupanavar. sorbilisKunth.); Methylxanthine content and caffeine metabolism in guarana fruits (Paullinia cupanavar. sorbilisKunth.)

Flávia Camila Schimpl
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 31/07/2013 PT
Relevância na Pesquisa
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Alguns grupos de plantas caracterizam-se por acumularem cafeína. Chá, café e guaraná, que acumulam cafeína, são algumas dessas plantas. As sementes de guaraná possuem o maior teor de cafeína já descrito em plantas, entre 2,5 e 6%. A popularização dos produtos a base de guaraná e a alta demanda por cafeína natural (obtida por descafeinação de plantas) destacam o interesse comercial pela espécie. A biossíntese de cafeína em plantas foi extensivamente estudada em café e chá e ambas espécies têm as mesmas vias chave da biossíntese da cafeína. O terceiro passo da via ocorre na presença de teobromina sintase (TS), enzima com atividade específica na conversão de 7-metilxantina em teobromina, e/ou dependendo da espécie, na presença de cafeína sintase (CS), uma enzima bifuncional que atua nos dois últimos passo da síntese de cafeína, na conversão da 7-metilxantina para teobromina e posteriormente desta para cafeína. O objetivo desta tese foi caracterizar os níveis de metilxantinas, atividade e expressão de CS em frutos de guaraná, sendo que para isto foram realizadas análises bioquímicas e moleculares nos tecidos de cinco cultivares (BRS-Amazonas, BRS-CG372, BRS-CG611, BRS-Maués, BRS-Luzéia). Teobromina acumulou preferencialmente em folhas (estádios jovem...

Caffeine, adenosine receptors, and synaptic plasticity

Costenla, Ana Rita; Cunha, Rodrigo A.; Mendonça, Alexandre de
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
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Copyright ©2012 IOS Press All rights reserved.; Few studies to date have looked at the effects of caffeine on synaptic plasticity, and those that did used very high concentrations of caffeine, whereas the brain concentrations attained by regular coffee consumption in humans should be in the low micromolar range, where caffeine exerts pharmacological actions mainly by antagonizing adenosine receptors. Accordingly, rats drinking caffeine (1 g/L) for 3 weeks, displayed a concentration of caffeine of circa 22 μM in the hippocampus. It is known that selective adenosine A1 receptor antagonists facilitate, whereas selective adenosine A2A receptor antagonists attenuate, long term potentiation (LTP) in the hippocampus. Although caffeine is a non-selective antagonist of adenosine receptors, it attenuates frequency-induced LTP in hippocampal slices in a manner similar to selective adenosine A2A receptor antagonists. These effects of low micromolar concentration of caffeine (30 μM) are maintained in aged animals, which is important when a possible beneficial effect for caffeine in age-related cognitive decline is proposed. Future studies will still be required to confirm and detail the involvement of A1 and A2A receptors in the effects of caffeine on hippocampal synaptic plasticity...

Disclosing the caffeine dose to be administered that restores insulin sensitivity in prediabetes animal

Coelho, Joana Mensurado Cartaxo Índias
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em /11/2014 ENG
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The results discussed in this thesis originated the following communications in International and National congresses: Sacramento JF, Coelho JC, Melo BF, Guarino MP and Conde SV. (2014) Assessment of caffeine dose and time of administration required for resetting insulin sensitivity in high sucrose diet in rats. 50th Meeting of EASD (European Association for the study of Diabetes), 14-19 September, Vienna, Austria Coelho JC, Melo BF, Sacramento JF, Guarino MP and Conde SV (2014). Establishing the caffeine dose that chronically restores insulin sensitivity in animal model of prediabetes. Fundação Astrazeneca Innovate Competition, iMed conference 6.0®, 10-12 October, Lisboa, Portugal Also, during the last year I was involved in other ongoing projects that originated the following communications: Coelho JC, Melo BF, Sacramento JF, Ribeiro MJ, Guarino MP and Conde SV (2014). Are the effects of carotid sinus nerve resection on insulin sensitivity mediated by an increase in Glut4 expression in skeletal muscle?. XLIV Reunião Anual da Sociedade Portuguesa de Farmacologia, XXXII Reunião de Farmacologia Clínica e XIII Reunião de Toxicologia, 5-7 February, Coimbra, Portugal Sacramento JF, Rodrigues T, Coelho JC, Matafome P, Ribeiro MJ...

ASSOCIATION OF CAFFEINE INTAKE AND LIVER FIBROSIS IN PATIENTS WITH CHRONIC HEPATITIS C

OLIVEIRA,Kalinca da Silva; BUSS,Caroline; TOVO,Cristiane Valle
Fonte: Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE ; Colégio Brasileiro de Cirurgia Digestiva - CBCD ; Sociedade Brasileira de Motilidade Digestiva - SBMD ; Federação Brasileira de Gastroenterologia - FBG; Sociedade Brasileira de Hepatologia - SBH; Sociedade Brasileira de Endoscopia Digestiva - SOBED Publicador: Instituto Brasileiro de Estudos e Pesquisas de Gastroenterologia - IBEPEGE ; Colégio Brasileiro de Cirurgia Digestiva - CBCD ; Sociedade Brasileira de Motilidade Digestiva - SBMD ; Federação Brasileira de Gastroenterologia - FBG; Sociedade Brasileira de Hepatologia - SBH; Sociedade Brasileira de Endoscopia Digestiva - SOBED
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
Relevância na Pesquisa
37.18%
Background Caffeine consumption has been associated to decreased levels of liver enzymes and lower risk of fibrosis in patients with hepatitis C virus. Objectives This study aimed to evaluate the association between caffeine consumption and inflammatory activity or degree of liver fibrosis in patients with hepatitis C virus infection. Methods A cross-sectional study of patients with chronic hepatitis C virus infection treated in an outpatient Gastroenterology Unit of Santa Casa Hospital (Porto Alegre - Brasil). Patients were interviewed regarding the consumption of caffeine and anthropometric assessment was performed. Liver biopsy was performed in a maximum period of 36 months before inclusion in the study Results There were 113 patients, 67 (59.3%) females, 48 (42.5%) were aged between 52 and 62 years, and 101 (89.4%) were white. The average caffeine consumption was 251.41 ± 232.32 mg/day, and 70 (62%) patients consumed up to 250 mg/day of caffeine. There was no association between caffeine consumption and inflammatory activity on liver biopsy. On the other hand, when evaluating the caffeine consumption liver fibrosis an inverse association was observed. Conclusions The greater consumption of caffeine was associated with lower liver fibrosis. There was no association between caffeine consumption and inflammatory activity.

Caffeine effect on mortality and oviposition in successive generations of Aedes aegypti

Laranja,Alessandra Theodoro; Manzato,Antonio José; Bicudo,Hermione Elly Melara de Campos
Fonte: Faculdade de Saúde Pública da Universidade de São Paulo Publicador: Faculdade de Saúde Pública da Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 EN
Relevância na Pesquisa
37.16%
OBJECTIVE: Previous experiments showed that caffeine blocks the development of Aedes aegypti (Diptera, Culicidae) in the larval stage, consequently inhibiting the production of adults. This study aimed at obtaining data suggestive of caffeine resistance by these mosquitoes. METHODS: Experiments were carried out in successive generations to assess adult production from eggs laid in previous generation and oviposition rate in every generation using 200 and 500 µg/mL caffeine. Tap water was used as control. Experiments were conducted in the city of São José do Rio Preto, Southeastern Brazil between 2002 and 2005. Statistical tests consisted of exploratory data analysis and smoothing algorithms. RESULTS: Increasing reduction in productivity of adults occurred among generations at both caffeine concentrations but the differences were only significant at 200µg/mL caffeine. As for the oviposition rate, there was a decrease in the mean number of eggs per female over generations at both caffeine concentrations. CONCLUSIONS: There was no evidence of caffeine resistance over generations. The study results corroborate caffeine as an alternative as an important Ae. Aegypti control agent to avoid resistance.

Caffeine intake by patients with autosomal dominant polycystic kidney disease

Vendramini,L.C.; Nishiura,J.L.; Baxmann,A.C.; Heilberg,I.P.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 EN
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Because caffeine may induce cyst and kidney enlargement in autosomal dominant polycystic kidney disease (ADPKD), we evaluated caffeine intake and renal volume using renal ultrasound in ADPKD patients. Caffeine intake was estimated by the average of 24-h dietary recalls obtained on 3 nonconsecutive days in 102 ADPKD patients (68 females, 34 males; 39 ± 12 years) and compared to that of 102 healthy volunteers (74 females, 28 males; 38 ± 14 years). The awareness of the need for caffeine restriction was assessed. Clinical and laboratory data were obtained from the medical records of the patients. Mean caffeine intake was significantly lower in ADPKD patients versus controls (86 vs 134 mg/day), and 63% of the ADPKD patients had been previously aware of caffeine restriction. Caffeine intake did not correlate with renal volume in ADPKD patients. There were no significant differences between the renal volumes of patients in the highest and lowest tertiles of caffeine consumption. Finally, age-adjusted multiple linear regression revealed that renal volume was associated with hypertension, chronic kidney disease stage 3 and the time since diagnosis, but not with caffeine intake. The present small cross-sectional study indicated a low level of caffeine consumption by ADPKD patients when compared to healthy volunteers...

Efeitos da ingestão de cafeína sobre a contribuição anaeróbia e o desempenho em ciclismo de 4.000m após depleção de glicogênio muscular; Effect of caffeine ingestion on anaerobic contribution and 4-km cycling time Trial performance after muscle glycogen depletion

Cavalcante, Marcos David da Silva
Fonte: Universidade Federal de Alagoas; BR; Nutrição; Programa de Pós-Graduação em Nutrição; UFAL Publicador: Universidade Federal de Alagoas; BR; Nutrição; Programa de Pós-Graduação em Nutrição; UFAL
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
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Several research has shown that caffeine ingestion (1, 2, 7 trimethylxanthine) increases performance. Due to these findings and their removal from the list of banned substances in 2004 by the international anti doping agency, athletes of various sports have widely used caffeine in order to increase performance during competitions. Studies have shown an increase in performance in high-intensity exercise after caffeine ingestion. The increase in performance with the use of caffeine in this type of performance, seems to be related to increasing the anaerobic contribution . On the other hand, depletion of glycogen stores appear to reduce performance during high intensity exercise. This reduction according studies appears to be due to a reduction of the anaerobic contribution. More recently, research has been conducted in order to investigate whether supplementation of carbohydrate with the addition of caffeine provides the additional effect on performance. Thus, the goal of this dissertation was: 1) review the main findings about the effects on performance in time trial and what the mechanisms involved in the combined supplementation of caffeine and carbohydrate (review article). 2) verify if intake of caffeine can reverse the impairment in performance and anaerobic contribution caused by depletion of muscle glycogen during 4000m cycling time trial (results article). In the studies reviewed in the review article found that most studies with combined ingestion of caffeine and carbohydrate showed a further increase in performance. However...

Caffeine for apnea of prematurity trial: Benefits may vary in subgroups

Davis, P.; Schmidt, B.; Roberts, R.; Doyle, L.; Asztalos, E.; Haslam, R.; Sinha, S.; Tin, W.
Fonte: Mosby Inc Publicador: Mosby Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
37.2%
Objective: To determine whether the benefits of caffeine vary in three subgroups of 2006 participants in the Caffeine for Apnea of Prematurity (CAP) trial. Study design: Post-hoc subgroup analyses were performed on the basis of: (1) indication for commencement of study drug: treat apnea, prevent apnea, or facilitate extubation; (2) positive pressure ventilation (PPV) at randomization: endotracheal tube (ETT), noninvasive ventilation, or none; and (3) timing of commencement of study drug: early or late (≤3 versus >3 days). Outcomes assessed were those showing treatment effects in the original analyses. We investigated the consistency of caffeine effects by using regression models that incorporated treatment/subgroup factor interactions. Results: There was little evidence of a differential treatment effect of caffeine in subgroups defined by the clinical indication for starting study drug. The size and direction of the caffeine effect on death or disability differed depending on PPV at randomization (P = .03). Odds ratios (95% CI) were: no support, 1.32 (0.81-2.14); noninvasive support, 0.73 (0.52-1.03); and ETT, 0.73 (0.57-0.94). Adjustment for baseline factors strengthened this effect (P = .02). Starting caffeine early resulted in larger reductions in days of respiratory support. Postmenstrual age at time of discontinuing PPV was shorter with earlier treatment (P = .01). Mean differences (95% CI) were: early...

Studie zur Untersuchung der Auswirkungen von Koffein auf den Pupillographischen Schläfrigkeitstest bei gesunden Probanden; Investigation of caffeine effects on the pupillographic sleepiness test (PST)in healthy subjects

Stuiber, Gitta
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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Einleitung: Koffein gehört zur Gruppe der Methylxanthine (diese Substanzen werden von Pflanzen als Fraßschutz gebildet). Nach Kaffeegenuss erreicht die Koffeinwirkung nach ca. 30 Minuten ihr Maximum und hält im Normalfall zwischen zwei und fünf Stunden an. Koffein wirkt vor allem auf die Großhirnrinde. Eine wichtige Wirkung des Koffeins ist die Blockierung von Adenosin-Rezeptoren. Dies führt unter anderem dazu, dass bei schläfrigen Personen Schläfrigkeitserscheinungen aufgehoben werden und die geistige Leistungsfähigkeit gesteigert wird. Wegen der sympathomimetischen Wirkung von Koffein ist zu erwarten, dass Koffein die sympathische Hemmung verstärkt und dadurch zu einer Dämpfung schläfrigkeitstypischer, spontaner Pupillen-oszillationen im Dunkeln führt. Letztere dienen beim Pupillographischen Schläfrigkeitstest (PST) zur objektiven Erfassung von Tagesschläfrigkeit. Bisher fanden alle PST-Studien und -Untersuchungen unter der Bedingung statt, dass der Konsum von Koffein vier Stunden vor der Messung nicht erlaubt war. In dieser Studie wollten wir herausfinden, wie groß der Koffeineffekt auf die Messergebnisse des PST ist und wie lange dieser Effekt anhält. Es sollte eine Antwort gefunden werden auf die Frage: reichen vier Stunden Koffeinkarenz vor Messbeginn aus oder muss die Zeitspanne verändert werden? Methodik: Mit dem Pupillographischen Schläfrigkeitstest werden die spontanen Pupillenoszillationen in Dunkelheit 11 Minuten lang aufgezeichnet und automatisch mit einer Software ausgewertet. Der Messparameter ist der PUI. Hohe PUI-Werte sprechen für Tagesschläfrigkeit. Vor jeder Messung sollten die Probanden für zehn Minuten entspannt sitzen und z.B. lesen. Wir untersuchten 20 freiwillige Personen...

Reconsidering Caffeine: An Awake and Alert New Look at America's Most Commonly Consumed Drug

Mrazik, David M.
Fonte: Harvard University Publicador: Harvard University
Tipo: Paper (for course/seminar/workshop)
EN_US
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37.24%
Caffeine is one of the most pervasively ingested addictive substances in the United States, yet astoundingly little attention is paid to its ubiquitous presence. This Paper examines caffeine, the substance, from many perspectives. First, it discusses caffeine with particular regard to its chemical properties; its presence in foods, beverages, and medications both naturally and as an additive; and its known impacts on human biological and psychological functioning. Relevant medical investigations of caffeine’s therapeutic properties and its toxicology are included in order to better evaluate the benefits, the risks, and the relative safety of prolonged caffeine consumption. In light of more recent medical findings, the Paper finds that caffeine poses fewer serious health risks than previously thought, and the potential for damage to the vast majority of the consumer public is minimal. The Paper also addresses issues of FDA regulation of caffeine, including a discussion of current regulation and classification of the substance both as a food product and as a drug product, as well as questioning the usefulness of greater consumer warning labels and promotion of improved public awareness of caffeine’s various health effects. Due to both the paucity of long-term caffeine health studies and the conflicts among those studies...

Microarray and Real-Time PCR Analysis of Gene Expression in the Honeybee Brain Following Caffeine Treatment

Kucharski, Robert; Maleszka, Ryszard
Fonte: Humana Press Inc. Publicador: Humana Press Inc.
Tipo: Artigo de Revista Científica
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37.18%
To test the idea that caffeine might induce changes in gene expression in the honeybee brain, we contrasted the transcriptional profiles of control and caffeine-treated brains using high-throughput cDNA microarrays. Additional quantitative real-time PCR was performed on a subset of eight transcripts to visualize the temporal changes induced by caffeine. Genes that were significantly upregulated in caffeine-treated brains included those involved in synaptic signaling (GABA:Na symporter, dopamine D2R-like receptor, and synapsin), cytoskeletal modifications (kinesin and microtubule motors), protein translation (ribosomal protein RpL4, elongation factors), and calcium-dependent processes (calcium transporter, calmodulin-dependent cyclic nucleotide phosphodiesterase). In addition, our study uncovered a number of novel, caffeine-inducible genes that appear to be unique to the honeybee. Time-dependent profiling of caffeine-sensitive gene expression shows significant upregulation 1 h after treatment followed by moderate downregulation after 4 h with no additional changes occuring after 24 h. Our results provide initial evidence that the dopaminergic system and calcium exchange are the main targets of caffeine in the honeybee brain and suggest that molecular responses to caffeine in an invertebrate brain are similar to those in vertebrate organisms.

Caffeine Intake and its Association with Disease Progression, Sleep Quality and Anxiety Symptoms and Nutritional Alterations in People Living with HIV in the Miami Adult Studies on HIV Cohort

Ramamoorthy, Venkataraghavan
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: text Formato: application/pdf
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37.2%
Miami-Dade County has approximately 27,000 people living with HIV (PLWH), and the highest HIV incidence in the nation. PLWH have reported several types of sleep disturbances. Caffeine is an anorexic and lipolytic stimulant that may adversely affect sleep patterns, dietary intakes and body composition. High caffeine consumption (>250 mg. per day or the equivalent of >4 cups of brewed coffee) may also affect general functionality, adherence to antiretroviral treatment (ART) and HIV care. This study assess the relationship of high caffeine intake with markers of disease progression, sleep quality, insomnia, anxiety, nutritional intakes and body composition. A convenience sample of 130 PLWH on stable ART were recruited from the Miami Adult Studies on HIV (MASH) cohort, and followed for three months. After consenting, questionnaires on Modified Caffeine Consumption (MCCQ), Pittsburg Insomnia Rating Scale (PIRS), Pittsburg Sleep Quality Index (PSQI), Generalized Anxiety Disorder-7 (GAD-7), socio-demographics, drug and medication use were completed. CD4 count, HIV viral load, anthropometries, and body composition measures were obtained. Mean age was 47.89±6.37 years, 60.8% were male and 75.4% were African-Americans. Mean caffeine intake at baseline was 337.63 ± 304.97 mg/day (Range: 0-1498 mg/day) and did not change significantly at 3 months. In linear regression...