RESUMO
Muscle mass is the major deposit of protein molecules with dynamic turnover between net protein synthesis and degradation. In human subjects, invasive and non-invasive techniques have been applied to determine their skeletal muscle catabolism of amino acids at rest, during and after different forms of physical exercise and training. The aim of this review is to analyse the turnover flux and the relative oxidation rate of different types of muscle proteins after one bout of exercise as well as after resistance and endurance condition of training. Protein feeding in athletes appears to be a crucial nutrition necessity to promote the maintenance of muscle mass and its adaptation to the need imposed by the imposed technical requirements. In resting human individuals, there commended protein daily allowance is about 0.8 g (dry weight) kg−body weight per 24 h knowing that humans are unable to accumulate protein stores in muscle tissues. Nevertheless, practical feeding recommendations related to regular exercise practice are proposed to athletes by different bodies in order to foster their skills and performance. This review will examine the results obtained under endurance and resistance type of exercise while consuming single or repeated doses of various ingestions of protein products (full meat, essential amino acids, specific amino acids and derivatives, vegetarian food). From the scientific literature, it appears that healthy athletes(and heavy workers) should have a common diet of 1.25 g kg−24 h to compensate the exercise training muscle protein degradation and their resyn thesis within the following hours. A nitrogen-balance assay would berecommended to avoid any excessive intake of protein. Eventually, a daily equilibrated food intake would beof primer importance versus inadequate absorption of some specific by-products.
Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto , Aminoácidos/biossíntese , Aminoácidos/metabolismo , Exercício Físico , Proteínas MuscularesRESUMO
Different fuels are available to generate ATP for muscle activities during sport events. Glycogen from striated muscles and liver stores may be converted to lactic acid or almost completely oxidized to carbon dioxide (CO2), triacylglycerol within the muscle itself and fatty acids from adipose tissue could be converted to CO2 in acting muscles, some free amino acids can be released within the muscle itself and from intestinal stores to sustain the amount of ATP generation indispensable for muscle contraction. All single biochemical reactions, but one, need one or several enzymes to activate the conversion of a substrate into a product. The energy transformation in biochemical reactions is led by application of so-called free energy. Reversible and non-reversible reactions within a metabolic pathway are dependent on specific enzymes near or far from equilibrium. Allosteric enzymes are regulatory enzymes that provide the direction in the pathway. A regulatory enzyme is either activated or inhibited by small regulators (ligands). A reversible substrate cycle between A and B is catalyzed by two enzymes with different fluxes. The need of ATP production for muscle contraction is under the leadership of regulatory enzymes and available substrate stores. The improvement of adapted metabolic reactions under sport training depends on the appropriate increase of regulatory enzymes within the glycolytic and oxidative pathways. The amount of some specific enzymes is increased by training in order to improve the maximum activity of the metabolic pathway. Unfortunately, several publications do not precisely implicate the appropriate enzyme(s) to explain or reject the adaptation induced by the training schedule. A few examples will illustrate the factual interpretation and the inadequate allegation...
Assuntos
Humanos , Trifosfato de Adenosina , Enzimas , Glicogênio , Treinamento ResistidoRESUMO
Objetivos. El trasplante celular para la regeneración del miocardio está limitado por la escasa viabilidad del injerto y la baja retención celular. En la miocardiopatía isquémica la matriz extracelular está profundamente alterada, por consiguiente, sería importante asociar un procedimiento para regenerar las células miocárdicas y restaurar la función de la matriz extracelular. En este estudio clínico, fue evaluada la terapia celular intrainfarto asociada a una matriz de colágeno sembrada con células e implantada sobre ventrículos infartados.Métodos. En 15 pacientes (54,2±3,8 años de edad) que presentaban cicatrices miocárdicas postisquémicas en el ventrículo izquierdo (VI) y con indicación de cirugía de revascularización miocárdica, se implantaron, durante la operación, células de la médula ósea mononucleares autólogas (CMO) en la cicatriz. Se agregó sobre esa zona infartada una matriz de colágeno tipo I con el mismo número de CMO
Resultados. No hubo mortalidad ni eventos adversos relacionados (seguimiento 15±4,2 meses). La clase funcional según la New York Heart Association (NYHA) mejoró de 2,3±0,5 a 1,4±0,3 (p=0,005). El volumen de fin de diástole del VI evolucionó de 142±24 a 117±21 mL (p=0,03), el tiempo de desaceleración del llenado del VI mejoró aumentando de 162±7 mseg a 196±8 mseg (p=0,01). El espesor del área cicatrizada progresó de 6±1,4 a 9±1,5 mm (p=0,005). La fracción de eyección (FE) mejoró de 25±7 a 33±5% (p=0,04).Conclusiones. La inyección intramiocárdica de células de médula ósea y la fijación simultánea de una matriz sembrada con progenitores celulares (stem cells) sobre el epicardio fue simple y sin complicaciones. La matriz de colágeno aumento el espesor de la zona del infarto con nuevos tejidos viables, limitando la dilatación ventricular y mejorando la función diastólica. Estos resultados positivos no pueden ser absolutamente relacionados a las células y la matriz, pues se asociaron puentes de revascularización coronaria. En conclusión, la ingeniería de tejidos puede extender las indicaciones y beneficios de la terapia con células madre en cardiología, convirtiéndose en un camino prometedor para la creación de un miocardio bioartificial
Objectives. Stem cell therapy for myocardial regeneration is limited by poor graft viability and low cell retention. In ischemic cardiomyopathy the extracellular matrix is pathologically modified, therefore it could be important to associate a procedure aiming at regenerating both, myocardial cells and the extracellular matrix. We evaluated intrainfarct cell therapy associated with a cell-seeded collagen scaffold grafted onto infarcted hearts.Methods. In 15 patients (aged 54.2±3.8 years) presenting LV postischemic myocardial scars and with indication for a single off-pump-CABG, autologous mononuclear bone marrow cells (BMC) were implanted during surgery in the scar. A 3D collagen type I matrix seeded with the same number of BMC was grafted onto the infarction zone.Results. There was no mortality and any related adverse events (follow-up 15±4.2 months). NYHA FC improved from 2.3±0.5 to 1.4±0.3 (p=0.005). LV end-diastolic volume evolved from 142±24 to 117±21 mL (p=0.03), LV filling deceleration time improved from 162±7 ms to 196±8 ms (p=0.01). Scar area thickness progress from 6±1.4 to 9±1.5mm (p=0.005). EF improved from 25±7 to 33±5% (p=0.04).Conclusions. Simultaneous intramyocardial injection of mononuclear bone marrow cells and fixation of a BMC-seeded matrix onto the epicardium is feasible and safe. The cell seeded collagen matrix seems to increase the thickness of the infarct scar with viable tissues and help to normalize cardiac wall stress in injured regions, thus limiting ventricular remodelling and improving diastolic function. Patients improvements can not be conclusively related to the cells and matrix due to the association of CABG. Cardiac tissue engineering should extend the indications and benefits of stem cell therapy in cardiology, becoming a promising way for the creation of a bioartificial myocardium
Assuntos
Humanos , Cardiomioplastia , Terapia Baseada em Transplante de Células e Tecidos , Insuficiência Cardíaca , Miocárdio , Engenharia TecidualRESUMO
Introducción y objetivos. El mecanismo más frecuente de regurgitación mitral isquémica es la restricción de movimiento de los velos en sístole (tipo IIIb de Carpentier). La anuloplastia es la técnica más aceptada para su reparación. El nuevo anillo protésico Carpentier-McCarthy-Adams IMR Etlogix® fue diseñado para tratar cada una de las peculiaridades de esta entidad, principalmente la dilatación anular asimétrica. En este estudio revisamos las bases de creación del anillo y describimos nuestra experiencia clínica inicial. Métodos. Se intervino a 40 pacientes (edad, 68 ± 10 años) de regurgitación mitral isquémica de tipo IIIb (grados 3+/4+) mediante el nuevo anillo protésico entre diciembre de 2003 y junio de 2005. Los procedimientos asociados fueron la revascularización coronaria (n = 27 [68%]), la valvuloplastia tricuspídea (n = 10 [25%]) y la técnica modificada de Maze (n = 9 [22%]). La estimación del riesgo quirúrgico por EuroSCORE fue del 17% ± 11%. Resultados. La mortalidad hospitalaria fue del 2,5% (n = 1). La morbilidad postoperatoria incluyó 1 caso de accidente cerebrovascular (2,5%), 1 caso de insuficiencia renal (2,5%) y 4 casos de insuficiencia respiratoria (10%). El estudio ecocardiográfico previo al alta hospitalaria reveló la ausencia de regurgitación mitral en 36 pacientes (92%) y regurgitación de grado leve en 3 (8%). Se obtuvo el seguimiento ecocardiográfico a largo plazo de 36 pacientes (92%; intervalo de seguimiento, 15-34 meses), y se objetivó una tasa de recurrencia (grado ≥ 2+) del 3% (n = 1). Conclusiones. El anillo de Carpentier-McCarthy-Adams IMR Etlogix® corrige de manera efectiva la regurgitación mitral isquémica de tipo IIIb. La nueva conformación tridimensional asimétrica afronta las características anatomopatológicas de este tipo de disfunción y puede aportar excelentes resultados a largo plazo (AU)
Introduction and objectives. The most common mechanism underlying ischemic mitral regurgitation is restricted leaflet motion during systole (Carpentier's type IIIb). Annuloplasty is the preferred technique for surgical repair. The new CarpentierMcCarthyAdams IMR Etlogix® prosthetic annuloplasty ring was designed specifically to address the particular peculiarities of this condition, principally asymmetric annular dilatation. The aims of this study were to review the rationale underlying the creation of the ring and to report our early clinical experience. Methods. The study included 40 patients with type-IIIb ischemic mitral regurgitation (grade 3+/4+) who underwent mitral value reconstruction using the new prosthetic ring between December 2003 and June 2005. Their mean age was 68±10 years. Concomitant procedures included coronary artery bypass grafting (n=27, 68%), tricuspid valvuloplasty (n=10, 25%), and a modified Maze procedure (n=9, 22%). The mean predicted EuroSCORE mortality for surgery was 17±11%. Results. In-hospital mortality was 2.5% (n=1). Major postoperative morbidities included one case of stroke (2.5%), one renal failure (2.5%), and four respiratory failures (10%). Predischarge echocardiography revealed no mitral regurgitation in 36 patients (92%) and mild regurgitation in three (8%). Long-term follow-up echocardiography was carried out in 36 patients (92%) after 1534 months, and showed that the rate of recurrence of (grade é2+) mitral regurgitation was 3% (n=1). Conclusions. The CarpentierMcCarthyAdams IMR Etlogix® annuloplasty ring was effective in correcting type-IIIb ischemic mitral regurgitation. Its novel three-dimensional asymmetric shape is designed to deal with the anatomical and pathological characteristics of the condition and its use may, therefore, result in an excellent long-term outcome (AU)