Experimental gerontology
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Experimental gerontology · Nov 2013
Neuromechanical properties of the triceps surae in young and older adults.
The aim of this study was to compare voluntary and involuntary force generating capacity of the triceps surae muscles in healthy young and older adult participants during isometric and isokinetic contractions. Ultrasound was used to measure medial gastrocnemius (MG) fascicle length during maximal voluntary isometric contractions and supra-maximal isometric twitch contractions at five ankle angles throughout the available range of motion, as well as isokinetic concentric and eccentric contractions at four ankle velocities. Maximum voluntary activation of the plantar flexors was assessed using the twitch interpolation technique. ⋯ These age-related differences in torque were not explained by torque-length-velocity behaviour of the MG muscle fascicles, passive plantar flexor torque-angle properties, decreased neural drive of the plantar flexor muscles or antagonistic co-activation of the tibialis anterior muscle. The residual deficit in isometric and concentric plantar flexor torques in healthy older adults may involve reduced muscle quality. A significant reduction in supra-maximal twitch torque at longer MG fascicle lengths as well as a lower MG fascicle velocity during eccentric contractions in older adults was detected, which could possibly be a function of the reported increased Achilles tendon compliance in older adults.
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Elderly patients may experience impairments in cognition or mood following surgery. To study the development and underlying mechanisms of these postoperative behavioral changes, young (3 months) and aged (18-20 months) male rats were subjected to abdominal surgery followed by behavioral testing during a period of 6 weeks. Microglia activation (IBA-1) and neurogenesis (DCX) were immunohistochemically determined. ⋯ However, aged rats displayed long-term changes in affective behavior and had increased microgliosis in the CA1 hippocampal region following surgery. Microglia activation following surgery was positively correlated to parameters of behavior and spatial learning. These findings support the hypothesis that elderly patients have an increased behavioral and (neuro)inflammatory response to surgery and these factors may be related.
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Aging is associated with a host of biological changes that contribute to a progressive decline in cognitive and physical function, ultimately leading to a loss of independence, and increased risk of mortality. To date, prolonged caloric restriction (i.e., a reduction in caloric intake without malnutrition) is the only non-genetic intervention that has consistently been found to extend both mean and maximal life span across a variety of species. Most individuals have difficulty sustaining prolonged caloric restriction, which has led to a search for alternative approaches that can produce similar to benefits as caloric restriction. ⋯ For this reason, there is increasing scientific interest in further exploring the biological and metabolic effects of intermittent fasting periods, as well as whether long-term compliance may be improved by this type of dietary approach. This special will highlight the latest scientific findings related to the effects of both caloric restriction and intermittent fasting across various species including yeast, fruit flies, worms, rodents, primates, and humans. A specific emphasis is placed on translational research with findings from basic bench to bedside reviewed and practical clinical implications discussed.
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Experimental gerontology · Jun 2013
Beneficial effects of Yerba Mate tea (Ilex paraguariensis) on hyperlipidemia in high-fat-fed hamsters.
Yerba Mate tea (Mate), an infusion made from the leaves of the tree Ilex paraguariensis, is a widely consumed beverage in South America. Mate has previously been shown to have hypolipidemic effects. However, its mechanism of action is not well understood. ⋯ Mate aqueous extract significantly decreased body-weight gain and lowered serum lipid levels in the hyperlipidemic hamster model. Meanwhile, Mate treatment increased antioxidant enzyme activity, improved lipoprotein lipase (LPL) and hepatic lipase (HL) activities in serum and liver, upregulated mRNA expression of peroxisome proliferator-activated receptor α and low density lipoprotein receptor, and downregulated mRNA expression of sterol regulatory element-binding protein 1c and acetyl CoA carboxylase in the liver. The results indicate that Mate tea ameliorates hyperlipidemia partly by reducing lipid peroxidation, improving endothelial function and LPL and HL activities, and modulating the expression levels of genes involved in lipid oxidation and lipogenesis.
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Experimental gerontology · Mar 2013
Preoperative renal dysfunction and clinical outcomes of cardiac surgery in octogenarians.
The proportion of elderly individuals is growing and the prevalence of chronic kidney disease (CKD) among elderly people undergoing cardiac surgery is increasing constantly. The aim of this study was to determine the influence of different degrees of preoperative renal dysfunction on postoperative outcomes in patients older than 80years of age. ⋯ A substantial increase in the risk of postoperative CVA and sepsis, but not mortality, was demonstrated in octogenarians with advanced but not mild degrees of preoperative CKD. Compared to younger patients, a high burden of comorbidities in octogenarians may have a greater influence on outcomes post cardiac surgery than impaired renal function. Our data may provide a rationale for modified risk stratification in octogenarian candidates for cardiac surgery.