Veterans Health Administration

About: Veterans Health Administration is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Population & Veterans Affairs. The organization has 63820 authors who have published 98417 publications receiving 4835425 citations. The organization is also known as: VHA.

The Effects of Exercise on Falls in Elderly Patients: A Preplanned Meta-analysis of the FICSIT Trials

Abstract: Objective —To determine if short-term exercise reduces falls and fall-related injuries in the elderly Design —A preplanned meta-analysis of the seven Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT)—independent, randomized, controlled clinical trials that assessed intervention efficacy in reducing falls and frailty in elderly patients All included an exercise component for 10 to 36 weeks Fall and injury follow-up was obtained for up to 2 to 4 years Setting —Two nursing home and five community-dwelling (three health maintenance organizations) sites Six were group and center based; one was conducted at home Participants —Numbers of participants ranged from 100 to 1323 per study Subjects were mostly ambulatory and cognitively intact, with minimum ages of 60 to 75 years, although some studies required additional deficits, such as functionally dependent in two or more activities of daily living, balance deficits or lower extremity weakness, or high risk of falling Interventions —Exercise components varied across studies in character, duration, frequency, and intensity Training was performed in one area or more of endurance, flexibility, balance platform, Tai Chi (dynamic balance), and resistance Several treatment arms included additional nonexercise components, such as behavioral components, medication changes, education, functional activity, or nutritional supplements Main Outcome Measures —Time to each fall (fall-related injury) by self-report and/or medical records Results —Using the Andersen-Gill extension of the Cox model that allows multiple fall outcomes per patient, the adjusted fall incidence ratio for treatment arms including general exercise was 090 (95% confidence limits [CL], 081, 099) and for those including balance was 083 (95% CL, 070,098) No exercise component was significant for injurious falls, but power was low to detect this outcome Conclusions —Treatments including exercise for elderly adults reduce the risk of falls ( JAMA 1995;273:1341-1347)

New approaches for interpreting projected bone densitometry data

Abstract: Bone densitometry using dual-photon absorptiometry (DPA) or dual-energy x-ray absorptiometry (DXA) has become a standard method for assessing bone mineral content in the spine and other skeletal regions. A projected areal density, referred to as bone mineral density (BMD,g/cm2), is normally calculated to assess regional bone density and strength. We demonstrate that this measure can be misleading when used to compare bones of different sizes due to inherent biases caused by bone thickness differences. For example, assuming that volumetric bone density remains constant and bony linear dimensions are proportional to height, a 20% increase in height would result in a 20% increase in both the thickness and the BMD of any bone. We describe new analysis methods to reduce the confounding effect of bone size, and we introduce a parameter, bone mineral apparent density (BMAD, g/cm3), that better reflects bone apparent density. Using this parameter, we calculate a quantity that serves as an index of bone strength (IBS, g2/cm4) for whole vertebral bodies. These analyses were applied to lumbar spine (L2-4) DXA measurements in a population of women 17-40 years old and appear to offer advantages to conventional techniques.

Functional and clinical significance of skeletal muscle architecture.

Abstract: Skeletal muscle architecture is the structural property of whole muscles that dominates their function. This review describes the basic architectural properties of human upper and lower extremity muscles. The designs of various muscle groups in humans and other species are analyzed from the point of view of optimizing function. Muscle fiber arrangement and motor unit arrangement is discussed in terms of the control of movement. Finally, the ability of muscles to change their architecture in response to immobilization, eccentric exercise, and surgical tendon transfer is reviewed. Future integrative physiological studies will provide insights into the mechanisms by which such adaptations occur. It is likely that muscle fibers transduce both stress and strain and respond by modifying sarcomere number in a way more suited to the new biomechanical environment.

Cerebrospinal fluid leptin levels: relationship to plasma levels and to adiposity in humans.

Abstract: The adipocyte hormone, leptin (OB protein), is proposed to be an "adiposity signal" that acts in the brain to lower food intake and adiposity. As plasma leptin levels are elevated in most overweight individuals, obesity may be associated with leptin resistance. To investigate the mechanisms underlying brain leptin uptake and to determine whether reduced uptake may contribute to leptin resistance, we measured immunoreactive leptin levels in plasma and cerebrospinal fluid (CSF) of 53 human subjects. Leptin concentrations in CSF were strongly correlated to the plasma level in a nonlinear manner (r = 0.92; p = 0.0001). Like levels in plasma, CSF leptin levels were correlated to body mass index (r = 0.43; p = 0.001), demonstrating that plasma leptin enters human cerebrospinal fluid in proportion to body adiposity. However, the efficiency of this uptake (measured as the CSF:plasma leptin ratio) was lower among those in the highest as compared with the lowest plasma leptin quintile (5.4-fold difference). We hypothesize that a saturable mechanism mediates CSF leptin transport, and that reduced efficiency of brain leptin delivery among obese individuals with high plasma leptin levels results in apparent leptin resistance.