Reflections of a metabolic biochemist: Eric Arthur Newsholme

Publicado em 18/03/2011 por Lucas Guimarães Ferreira
Quinta-feira, 17 de Março de 2011, o mundo perdeu um grande cientista: Eric Newsholme. O Dr. Newsholme contribuiu imensamente para o campo da bioquímica, publicando diversos trabalhos acerca da regulação do metabolismo no músculo e adaptações metabólicas ao exercício. Seu legado não será esquecido e o conhecimento gerado por ele e todos os alunos que o acompanharam em algum momento da vida, como o prof. Rui Curi do Instituto de Ciências Biomédicas da USP, continuarão a contribuir para o crescimento da ciência.
Segue um artigo publicado no The Biochemist sobre Eric Newsholme com uma entrevista.
Publicado em bioquímica, paper | Deixe um comentário

Comentários em postagens.

Publicado em 16/03/2011 por Lucas Guimarães Ferreira
Estava olhando algumas postagens antigas e ví que algumas tinham comentários de algumas pessoas. Como eu não havia habilitado a opção de ser avisado por e-mail quando houvessem comentário em alguma postagem, eu não ficava sabendo e acabei não respondendo.
Problema resolvido. Comentem que eu respondo, se necessário, o mais breve possível!
Lucas Guimarães.
Publicado em mensagem | Deixe um comentário

Creatine as a therapeutic strategy for myopathies.

Publicado em 16/03/2011 por Lucas Guimarães Ferreira
Segue a revisão recente do Dr. Tarnopolsky, uma das maiores autoridades na área, sobre a utilização da creatina em miopatias publicada na Amino Acids.

Amino Acids. 2011 Mar 12. [Epub ahead of print]

Tarnopolsky MA.
Department of Pediatrics and Medicine, McMaster University, 1200 Main St. W. HSC-2H26, Hamilton, ON, L8N 3Z5, Canada, tarnopol@mcmaster.ca.

Abstract

Myopathies are genetic or acquired disorders of skeletal muscle that lead to varying degrees of weakness, atrophy, and exercise intolerance. In theory, creatine supplementation could have a number of beneficial effects that could enhance function in myopathy patients, including muscle mass, strength and endurance enhancement, lower calcium levels, anti-oxidant effects, and reduced apoptosis. Patients with muscular dystrophy respond to several months of creatine monohydrate supplementation (~0.075-0.1 g/kg/day) with greater strength (~9%) and fat-free mass (~0.63 kg). Patients with myotonic dystrophy do not show as consistent an effect, possibly due to creatine transport issues. Creatine monohydrate supplementation shows modest benefits only at lower doses and possibly negative effects (cramping) at higher doses in McArdle’s disease patients. Patients with MELAS syndrome show some evidence of benefit from creatine supplementation in exercise capacity, with the effects in patients with CPEO being less robust, again, possibly due to limited muscle creatine uptake. The evidence for side effects or negative impact upon serological metrics from creatine supplementation in all groups of myopathy patients is almost non-existent and pale in comparison to the very substantial and well-known side effects from our current chemotherapeutic interventions for some myopathies (i.e., corticosteroids).

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Publicado em creatina, Músculo, paper, suplementação | Deixe um comentário

Ética na publicação de artigos científicos: quem são os autores?

Publicado em 04/03/2011 por Lucas Guimarães Ferreira
Uma questão sempre presente da pesquisa científica é: quem são os autores do trabalho e quem apenas proveu auxílio? Quem merece – ou deve – estar com o nome no trabalho como co-autor?

Segundo as diretrizes do periódico Medicine Science in Sports Exercise, os autores são aqueles que participaram de ao menos 2 das seguintes etapas do trabalho:

– participação significante da escrita do manuscrito;
– revisão significante do manuscrito;
– participação no delineamento da pesquisa;
– participação na aquisição de dados;
– análise e interpretação dos dados;
– proveu conhecimentos de estatística para o estudo.

Infelizmente os revisores e o editor dos periódicos não podem atestar que estas diretrizes foram de fato seguidas pelos autores, de qualquer forma, cabe o bom senso e a honestidade dos pesquisadores. Em um meio onde publicação é moeda corrente, é muito freqüente a troca de favores, de forma a busca o maior número de publicações possíveis no currículo sem o devido envolvimento na pesquisa.

Quem trabalha de forma séria e honesta sabe o custo de se obter dados fidedignos e confiáveis. Estes só são possíveis através de diversos experimentos (e não apenas 1 experimento com um n de X). Muitas vezes a decepção se faz presente ao assistir a falta de ética no meio acadêmico e científico. Mas se essa falta de ética está presente em todos os setores de nossa sociedade – infelizmente – era mesmo de se esperar que em nosso meio também estivesse.

Nos resta tentar ensinar nossos alunos, desde o mais cedo possível, o valor do trabalho sério, da ética e da honestidade para que assim, quem sabe um dia, possamos confiar mais na informação científica que nos é disponibilizada.
Publicado em ciência, ética, opinião, pesquisa | Deixe um comentário

Omega-3 Fatty acids supplementation attenuates inflammatory markers after eccentric exercise in untrained men.

Publicado em 04/03/2011 por Lucas Guimarães Ferreira
O estudo de Tartibian et al (2011), recém publicado na Clinical Journal of Sports Medicine mostra que a suplementação com ácidos graxos ômega 3 foi eficaz em reduzir a resposta inflamatória após contrações excêntricas. Segue o resumo:
Clin J Sport Med. 2011 Mar;21(2):131-7.

Tartibian B, Maleki BH, Abbasi A.

From the *Department of Cellular and Molecular Exercise Physiology, Faculty of Physical Education and Sport Science, Urmia University, Urmia, Iran; †Institute of Clinical and Experimental Transfusion Medicine (IKET), and Institute of Sport Science, University of Tuebingen, Tuebingen, Germany.

Abstract

OBJECTIVE: : To examine the effect of ingestion of omega-3 (N-3) fatty acids on the production of interleukin (IL) 6, tumor necrosis factor (TNF) α, prostaglandin (PG) E2, lactate dehydrogenase (LDH), creatine kinase (CK), and myoglobin (Mb) during an eccentric exercise program.
DESIGN: : A randomized, double-blinded, repeated measures design was used for this study.
SETTING: : The study was performed in the Exercise Physiology Laboratory of the Urmia University.
PARTICIPANTS: : Forty-five men, who had not participated in any training program for 60 days before their participation in this study, were recruited.
INTERVENTIONS: : Plasma levels of PGE2, IL-6, TNF-α, CK, LDH, and Mb were taken before supplementation, pre-exercise, and immediately, 24, and 48 hours after eccentric exercise. Subjects were assigned to one of the experimental (1.8 g/d N-3), placebo, or control groups.
MAIN OUTCOME MEASURES: : Plasma levels of PGE2, IL-6, and TNF-α were assessed using enzyme-linked immunosorbent assays kits. Plasma level of LDH, Mb, and CK were measured using an autoanalyzer, a c-counter, and an automatic blood analyzer, respectively.
RESULTS: : The experimental group showed less elevation in TNF-α and PGE2 immediately, 24, and 48 hours after exercise, when compared with the other groups. Significantly less elevation was shown in the concentration of IL-6, CK, and Mb for the experimental group at 24 and 48 hours after exercise. The experimental group also demonstrated a significant trend toward reduction in the plasma concentration of LDH immediately, 24, and 48 hours after the exercise program.
CONCLUSIONS: : Ingestion of N-3 can be effective in ameliorating, eccentric exercise-induced, inflammatory markers.
Publicado em ácidos graxos, nutrição, paper, suplementação | Deixe um comentário

The effect of HMB supplementation on body composition, fitness, hormonal and inflammatory mediators in elite adolescent volleyball players: a prospective randomized, double-blind, placebo-controlled study.

Publicado em 01/03/2011 por Lucas Guimarães Ferreira
Eur J Appl Physiol. 2011 Feb 16. [Epub ahead of print]

Portal S, Zadik Z, Rabinowitz J, Pilz-Burstein R, Adler-Portal D, Meckel Y, Cooper DM, Eliakim A, Nemet D.

School of Nutritional Sciences, Hebrew University of Jerusalem, Jerusalem, Israel.

Abstract

The use of ergogenic nutritional supplements is becoming inseparable from competitive sports. β-Hydroxy-β-Methylbutyric acid (HMB) has recently been suggested to promote fat-free mass (FFM) and strength gains during resistance training in adults. In this prospective randomized, double-blind, placebo-controlled study, we studied the effect of HMB (3 g/day) supplementation on body composition, muscle strength, anaerobic and aerobic capacity, anabolic/catabolic hormones and inflammatory mediators in elite, national team level adolescent volleyball players (13.5-18 years, 14 males, 14 females, Tanner stage 4-5) during the first 7 weeks of the training season. HMB led to a significant greater increase in FFM by skinfold thickness (56.4 ± 10.2 to 56.3 ± 8.6 vs. 59.3 ±  11.3 to 61.6 ± 11.3 kg in the control and HMB group, respectively, p < 0.001). HMB led to a significant greater increase in both dominant and non-dominant knee flexion isokinetic force/FFM, measured at fast (180°/sec) and slow (60°/sec) angle speeds, but had no significant effect on knee extension and elbow flexion and extension. HMB led to a significant greater increase in peak and mean anaerobic power determined by the Wingate anaerobic test (peak power: 15.5 ± 1.6 to 16.2 ± 1.2 vs. 15.4 ± 1.6 to 17.2 ± 1.2 watts/FFM, mean power: 10.6 ± 0.9 to 10.8 ± 1.1 vs. 10.7 ± 0.8 to 11.8 ± 1.0 watts/FFM in control and HMB group, respectively, p < 0.01), with no effect on fatigue index. HMB had no significant effect on aerobic fitness or on anabolic (growth hormone, IGF-I, testosterone), catabolic (cortisol) and inflammatory mediators (IL-6 and IL-1 receptor antagonist). HMB supplementation was associated with greater increases in muscle mass, muscle strength and anaerobic properties with no effect on aerobic capacity suggesting some advantage for its use in elite adolescent volleyball players during the initial phases of the training season. These effects were not accompanied by hormonal and inflammatory mediator changes.
Publicado em nutrição, paper, suplementação | Deixe um comentário

Resistance exercise volume affects myofibrillar protein synthesis and anabolic signalling molecule phosphorylation in young men.

Publicado em 07/02/2011 por Lucas Guimarães Ferreira
J Physiol. 2010 Aug 15;588(Pt 16):3119-30. Epub 2010 Jun 25.

Burd NA, Holwerda AM, Selby KC, West DW, Staples AW, Cain NE, Cashaback JG, Potvin JR, Baker SK, Phillips SM.

Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.

Abstract

We aimed to determine if any mechanistic differences exist between a single set (1SET) and multiple sets (i.e. 3 sets; 3SET) of resistance exercise by utilizing a primed constant infusion of [ring-13C6]phenylalanine to determine myofibrillar protein synthesis (MPS) and Western blot analysis to examine anabolic signalling molecule phosphorylation following an acute bout of resistance exercise. Eight resistance-trained men (24+/-5 years, BMI=25+/-4 kg m2) were randomly assigned to perform unilateral leg extension exercise at 70% concentric one repetition maximum (1RM) until volitional fatigue for 1SET or 3SET. Biopsies from the vastus lateralis were taken in the fasted state (Fast) and fed state (Fed; 20 g of whey protein isolate) at rest, 5 h Fed, 24 h Fast and 29 h Fed post-exercise. Fed-state MPS was transiently elevated above rest at 5 h for 1SET (2.3-fold) and returned to resting levels by 29 h post-exercise. However, the exercise induced increase in MPS following 3SET was superior in amplitude and duration as compared to 1SET at both 5 h (3.1-fold above rest) and 29 h post-exercise (2.3-fold above rest). Phosphorylation of 70 kDa S6 protein kinase (p70S6K) demonstrated a coordinated increase with MPS at 5 h and 29 h post-exercise such that the extent of p70S6K phosphorylation was related to the MPS response (r=0.338, P=0.033). Phosphorylation of 90 kDa ribosomal S6 protein kinase (p90RSK) and ribosomal protein S6 (rps6) was similar for 1SET and 3SET at 24 h Fast and 29 h Fed, respectively. However, 3SET induced a greater activation of eukaryotic translation initiation factor 2B (eIF2B) and rpS6 at 5 h Fed. These data suggest that 3SET of resistance exercise is more anabolic than 1SET and may lead to greater increases in myofibrillar protein accretion over time.
Figure 3. Myofibrillar protein fractional synthesis rate (FSR) at rest and 5 h after protein ingestion after one set (1SET) or 3 sets (3SET) of resistance exercise and 24–29 h later Inset, volume load (kg times repetitions) performed during 1SET and 3SET of resistance exercise. *Significantly different from rest (P < 0.05). †Significantly different from 29 h (P < 0.05). ‡Significantly different from 1SET (P < 0.05).


Figure 4. Phosphorylation of eIF2BεSer539 (A), p90RSKThr573 (B), p70S6KThr389 (C) and rps6Ser240/244 (D) following one set (1SET) or 3 sets (3SET) of resistance exercise in the fasted or fed statesData are expressed as fold-change from rest. *Significantly different from Fast (P < 0.05). †Significantly different from 1 set (1SET) within that time point (P < 0.05).
Publicado em bioquímica, fisiologia, paper, treinamento | Deixe um comentário

O que você precisa saber sobre questões éticas ao escrever um artigo científico

Publicado em 03/02/2011 por Lucas Guimarães Ferreira
Os problemas éticos mais comuns encontrados em artigos científicos (e como evitá-los).

Texto disponibilizado no site da Federação das Sociedades de Biologia Experimental (FeSBE), baseado em um texto da American Physiological Society (APS).

Disponível em: http://www.fesbe.org.br/v5/etica_em_pesquisa.pdf

Publicado em ciência, ética, pesquisa | Deixe um comentário

Chronic supplementation of beta-hydroxy-beta methylbutyrate (HMβ) increases the activity of the GH/IGF-I axis and induces hyperinsulinemia in rats.

Publicado em 18/01/2011 por Lucas Guimarães Ferreira
Saiu nosso estudo sobre os efeitos da suplementação de HMB sobre o eixo somatotrófico e resistência à insulina, publicado na Growth Hormone & IGF-1 Research. Segue o resumo.
Growth Horm IGF Res. 2011 Jan 13. [Epub ahead of print]
Gerlinger-Romero F, Guimarães-Ferreira L, Giannocco G, Nunes MT.

Abstract

OBJECTIVE: Beta-hydroxy-beta-methylbutyrate (HMβ) is a metabolite of leucine widely used for improving sports performance. Although HMβ is recognized to promote anabolic or anti-catabolic effects on protein metabolism, the impact of its long-term use on skeletal muscle and/or genes that control the skeletal protein balance is not fully known. This study aimed to investigate whether chronic HMβ treatment affects the activity of GH/IGF-I axis and skeletal muscle IGF-I and myostatin mRNA expression.
DESIGN: Rats were treated with HMβ (320mg/kg BW) or vehicle, by gavage, for 4weeks, and killed by decapitation. Blood was collected for evaluation of serum insulin, glucose and IGF-I concentrations. Samples of pituitary, liver, extensor digitorum longus (EDL) and soleus muscles were collected for total RNA or protein extraction to evaluate the expression of pituitary growth hormone (GH) gene (mRNA and protein), hepatic insulin-like growth factor I (IGF-I) mRNA, skeletal muscle IGF-I and myostatin mRNA by Northern blotting/real time-PCR, or Western blotting.
RESULTS: Chronic HMβ treatment increased the content of pituitary GH mRNA and GH, hepatic IGF-I mRNA and serum IGF-I concentration. No changes were detected on skeletal muscle IGF-I and myostatin mRNA expression. However, the HMβ-treated rats although normoglycemic, exhibited hyperinsulinemia.
CONCLUSIONS: The data presented herein extend the body of evidence on the potential role of HMβ-treatment in stimulating GH/IGF-I axis activity. In spite of this effect, HMβ supplementation also induces an apparent insulin resistance state which might limit the beneficial aspects of the former results, at least in rats under normal nutritional status and health conditions.

Copyright © 2010 Growth Hormone Research Society. Published by Elsevier Ltd. All rights reserved.

Publicado em bioquímica, fisiologia, nutrição, paper, suplementação | Deixe um comentário

Livro: Metabolismo Passo a Passo – J.G. Salway

Publicado em 17/01/2011 por Lucas Guimarães Ferreira
Para o estudo do metabolismo, indico o livro de J.G. Salway. Trata-se de um livro-atlas que aborda pontos-chave de vias metabólicas. Texto simples e conciso e boas ilustrações.

Capa Livro

Publicado em bioquímica, fisiologia, livro | Deixe um comentário