1,721,111 research outputs found
mTOR signaling as a target of amino acid treatment of the age-related sarcopenia.
No full textSarcopenia is an age-related structural and functional impairment of skeletal muscle leading to loss of strength, contractile capacity and endurance. Among factors implicated in sarcopenia, deregulation of muscle protein synthesis (MPS) has frequently been reported. Thus, the attempts aiming at identifying possible countermeasures to sarcopenia require consideration of a complex coordinated interaction of factors contributing to the balance between protein synthesis and breakdown and the identification of several regulators on their function. We will focus here on the signaling pathways controlling protein synthesis in skeletal muscle, specifically on one of the downstream effectors of the kinase Akt/PKB, the mammalian target of rapamycin (mTOR) kinase which is now recognized as a key regulator of cell growth and a pivotal sensor of nutritional status over the lifespan. Dysfunction of mTOR signaling in the elderly and its potential role as a target of amino acids in the treatment of age-related sarcopenia will be discussed
Muscle weakness and nutrition in critical illness: matching nutrient supply and use.
No full textLate parenteral nutrition supplementation can improve mithocondrial mechanisms for repair or removal, thus creating better cellular conditions for eff ective muscle contraction and strength generation
A critical reflection on the definition of metabolic syndrome.
No full textThe metabolic syndrome (visceral obesity, dyslipidaemia, hyperglycaemia, and hypertension), has become one of the major public-health challenges worldwide. There has been growing interest in this constellation of closely related cardiovascular risk factors. Recently, definition and relevance of this syndrome have been questioned. In the present review we analyze in detail the epistemological issues regarding definition and the methodological approaches to definition of the metabolic syndrom
Healthspan and longevity in mammals: a family game for cellular organelles?
No full textHealthy mitochondria are essential generators of cellular energy, while senescent or damaged mitochondria are bioenergetically inefficient and are sources of reactive oxygen species. The mitochondrial life cycle, comprising biogenesis, fusion/fission events and mitophagic elimination, is carefully orchestrated, and age-related decay of the lifecycle contributes to chronic degenerative diseases. Mitochondria make contacts with other cellular organelles in the endomembrane system (endoplasmic reticulum, peroxisomes and lysosomes) whose dynamics are co-regulated and interactions finely tuned to meet the cell requirements and maintain the health of the organism. This review will consider the evidence that mitochondrial biogenesis and quality control, as well as the complex interplay among cellular organelles, may be affected by the aging process(es), with negative consequences for the well being of elderly individuals. Moreover, we propose that nutrients or drugs able to maintain organelle homeostasis may represent novel preventive and/or therapeutic approaches for chronic age-related diseases
Amino acid supplements and diabetes
No full textInsulin resistance, the major limiting factor for peripheral glucose disposal in skeletal muscles, has an intricate multifactor origin. In particular, altered insulin signaling and multiple postreceptor defects contribute to decreased glucose transport, phosphorylation and oxidation.
There is increasing evidence that amino acids (AA) and, in particular, branched chain amino acids (BCAA) may play a fundamental role in metabolic regulation and glucose homeostasis. These roles originate from a range of effects including the known relationship between amino acids and glucose/insulin metabolism, the stimulatory effect of signaling pathways controlling protein synthesis in skeletal muscle, the regulation of the antioxidant defense system, and, as recently demonstrated, the stimulatory effect on mitochondrial biogenesis and function.
Overall while protein/amino acids intake is a primary substrate for gluconeogenesis, specific amino acids directly or indirectly regulate glucose oxidation through several mechanisms. This complex mix of metabolic outcomes may result in significant improvement of glycemic control in humans with type 2 diabetes
Biochemical and functional identification of a novel dopamine receptor subtype in rat brown adipose tissue. Its role in modulating sympathetic stimulation-induced thermogenesis.
No full textGSK3β inhibition protects mouse cortical neurons against oxygen-glucose deprivation injury.
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Branched-chain amino acids, mitochondrial biogenesis, and healthspan: an evolutionary perspective
No full textMalnutrition is common among older persons, with important consequences increasing frailty and morbidity and reducing health expectancy. On the contrary, calorie restriction (CR, a low-calorie dietary regimen with adequate nutrition) slows the progression of age-related diseases and extends the lifespan of many species. Identification of strategies mimicking key CR mechanisms - increased mitochondrial respiration and reduced production of oxygen radicals - is a hot topic in gerontology. Dietary supplementation with essential and/or branched chain amino acids (BCAAs) exerts a variety of beneficial effects in experimental animals and humans and has been recently demonstrated to support cardiac and skeletal muscle mitochondrial biogenesis, prevent oxidative damage, and enhance physical endurance in middle-aged mice, resulting in prolonged survival. Here we review recent studies addressing the possible role of BCAAs in energy metabolism and in the longevity of species ranging from unicellular organisms to mammals. We also summarize observations from human studies supporting the exciting hypothesis that dietary BCAA enriched mixture supplementation might be a health-promoting strategy in aged patients at risk. © Valerio et al
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