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BACKGROUND Age-related deterioration in homeostatic regulatory mechanisms leads to decreased complexity in their output. For example, the degradation of cardiac autonomic control results in loss of complexity in the heart rate signal. Frailty is a state of critically impaired homeostasis that results in heightened vulnerability to stressors. We propose a(More)
BACKGROUND Frailty assessment provides a means of identifying older adults most vulnerable to adverse outcomes. Attention to frailty in clinical practice is more likely with better understanding of its prevalence and associations with patient characteristics. We sought to provide national estimates of frailty in older people. METHODS A popular, validated(More)
Advanced glycation end products (AGEs) have been implicated in the pathogenesis of sarcopenia. Our aim was to characterize the relationship between serum carboxymethyl-lysine (CML), a major circulating AGE, and incident severe walking disability (inability to walk or walking speed <0.4 m/sec) over 30 months of followup in 394 moderately to severely disabled(More)
BACKGROUND Oxidative stress has been implicated in sarcopenia and the loss of muscle strength with aging, but the relationship between oxidative stress and decrease in muscle strength and physical performance has not been well characterized. Serum protein carbonyls are markers of oxidative damage to proteins and are caused by oxidative stress. METHODS(More)
Grip strength, an indicator of muscle strength, has been shown to be a predictor of poor outcomes among older adults. Protein carbonylation, an indicator of oxidative damage to proteins, leads to cellular dysfunction and a decline in tissue function. Oxidative stress has been implicated in the pathogenesis of sarcopenia. The objective was to determine(More)
This introduction to the R package BB is a (slightly) modified version of Varadhan and Gilbert (2009), published in the Journal of Statistical Software. We discuss R package BB, in particular, its capabilities for solving a nonlinear system of equations. The function BBsolve in BB can be used for this purpose. We demonstrate the utility of these functions(More)
We consider studies for evaluating the short-term effect of a treatment of interest on a time-to-event outcome. The studies we consider are only partially controlled in the following sense: (1) Subjects' exposure to the treatment of interest can vary over time, but this exposure is not directly controlled by the study; (2) subjects' follow-up time is not(More)
BACKGROUND The role of nutritional status in the disablement process is still unclear. The objective of this study was to assess whether low concentrations of nutrients predict the development and course of disability. METHODS Longitudinal study including community-dwelling women 65 years or older enrolled in the Women's Health and Aging Study I. In(More)
Frailty is a state of health signified by an increased vulnerability to adverse health outcomes in the face of stressors (e.g. infection). There is emerging consensus that research on both the theory and measurement of frailty must focus on the dynamic interactions within and across systems underlying the frailty syndrome. In this paper, we propose a(More)