RESUMO
Previous publications have described unethical organ procurement procedures in the People's Republic of China. International awareness and condemnation contributed to the announcement abolishing the procurement of organs from executed prisoners starting from January 2015. Eighteen months after the announcement, and aligned with the upcoming International Congress of the Transplantation Society in Hong Kong, this paper revisits the topic and discusses whether the declared reform has indeed been implemented. China has neither addressed nor included in the reform a pledge to end the procurement of organs from prisoners of conscience, nor has the government initiated any legislative amendments. Recent reports have discussed an implausible discrepancy of officially reported steady annual transplant numbers and a steep expansion of the transplant infrastructure in China. This paper expresses the viewpoint that, in the current context, it is not possible to verify the veracity of the announced changes, and it thus remains premature to include China as an ethical partner in the international transplant community. Until we have independent and objective evidence of a complete cessation of unethical organ procurement from prisoners, the medical community has a professional responsibility to maintain the academic embargo on Chinese transplant professionals.
Assuntos
Ética Médica , Transplante de Órgãos/ética , Doadores de Tecidos/ética , Obtenção de Tecidos e Órgãos/ética , Obtenção de Tecidos e Órgãos/normas , China , Humanos , Transplante de Órgãos/legislação & jurisprudência , Doadores de Tecidos/legislação & jurisprudência , Obtenção de Tecidos e Órgãos/legislação & jurisprudênciaRESUMO
The primary aim of this study was to evaluate the benefits of resistance training (RT) on quality of life (QOL) and fatigue in breast cancer survivors as an adjunct to usual care. We recruited 39 women who had survived breast cancer [mean age (y) 51.9 ± 8.8; time since diagnosis (m) 11.6 ± 13.2]. Primary outcomes were fatigue as assessed by the Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT) scale and QOL as assessed by the Functional Assessment of Cancer Therapy - General (FACT-G) scale. ANCOVA was used to assess the change in the primary outcomes while controlling for baseline values, with effect sizes (ES) displayed as partial Eta squared. The experimental group received supervised RT 3 days per week in a university clinic for 16 weeks. Perceptions of fatigue improved significantly in the RT group compared to controls [mean (SD) 6.7 (7.5) points vs. 1.5 (3.7) points], (P = 0.006, ES = 0.20) as did QOL [6.9 (8.5) points vs. 1.6 (4.4) points], (P = 0.015, ES = 0.16). We demonstrated both statistically and clinically important improvements in fatigue and QOL in response to RT in breast cancer survivors.
Assuntos
Neoplasias da Mama/complicações , Fadiga/prevenção & controle , Treinamento Resistido/métodos , Sobreviventes , Adolescente , Adulto , Idoso , Neoplasias da Mama/fisiopatologia , Fadiga/fisiopatologia , Feminino , Humanos , Pessoa de Meia-Idade , Força Muscular , Músculo Esquelético/fisiologia , Comportamento Sedentário , Adulto JovemRESUMO
The human ageing process is universal, ubiquitous and inevitable. Every physiological function is being continuously diminished. There is a range between two distinct phenotypes of ageing, shaped by patterns of living - experiences and behaviours, and in particular by the presence or absence of physical activity (PA) and structured exercise (i.e., a sedentary lifestyle). Ageing and a sedentary lifestyle are associated with declines in muscle function and cardiorespiratory fitness, resulting in an impaired capacity to perform daily activities and maintain independent functioning. However, in the presence of adequate exercise/PA these changes in muscular and aerobic capacity with age are substantially attenuated. Additionally, both structured exercise and overall PA play important roles as preventive strategies for many chronic diseases, including cardiovascular disease, stroke, diabetes, osteoporosis, and obesity; improvement of mobility, mental health, and quality of life; and reduction in mortality, among other benefits. Notably, exercise intervention programmes improve the hallmarks of frailty (low body mass, strength, mobility, PA level, energy) and cognition, thus optimising functional capacity during ageing. In these pathological conditions exercise is used as a therapeutic agent and follows the precepts of identifying the cause of a disease and then using an agent in an evidence-based dose to eliminate or moderate the disease. Prescription of PA/structured exercise should therefore be based on the intended outcome (e.g., primary prevention, improvement in fitness or functional status or disease treatment), and individualised, adjusted and controlled like any other medical treatment. In addition, in line with other therapeutic agents, exercise shows a dose-response effect and can be individualised using different modalities, volumes and/or intensities as appropriate to the health state or medical condition. Importantly, exercise therapy is often directed at several physiological systems simultaneously, rather than targeted to a single outcome as is generally the case with pharmacological approaches to disease management. There are diseases for which exercise is an alternative to pharmacological treatment (such as depression), thus contributing to the goal of deprescribing of potentially inappropriate medications (PIMS). There are other conditions where no effective drug therapy is currently available (such as sarcopenia or dementia), where it may serve a primary role in prevention and treatment. Therefore, this consensus statement provides an evidence-based rationale for using exercise and PA for health promotion and disease prevention and treatment in older adults. Exercise prescription is discussed in terms of the specific modalities and doses that have been studied in randomised controlled trials for their effectiveness in attenuating physiological changes of ageing, disease prevention, and/or improvement of older adults with chronic disease and disability. Recommendations are proposed to bridge gaps in the current literature and to optimise the use of exercise/PA both as a preventative medicine and as a therapeutic agent.
Assuntos
Envelhecimento/fisiologia , Exercício Físico , Fragilidade , Promoção da Saúde , Qualidade de Vida , Idoso , Exercício Físico/fisiologia , Terapia por Exercício/normas , Fragilidade/prevenção & controle , Humanos , Fenótipo , Comportamento SedentárioRESUMO
The majority of resistance training (RT) research with children to date has focused on pre-adolescents and the safety and efficacy of this type of training rather than the potential metabolic health benefits. Our objectives, using computerized databases, were (i) to systematically review studies utilizing RT interventions with children and adolescents <18 years; (ii) to investigate the metabolic health outcomes (adiposity, lipids, insulin, glucose) associated with RT; (iii) to provide recommendations for future investigations. A total of 12 studies met the review criteria. There is only a small amount of evidence that children and adolescents may derive metabolic health-related adaptations from supervised RT. However, methodological limitations within the body of this literature make it difficult to determine the optimal RT prescription for metabolic fitness in children and adolescents, and the extent and duration of such benefits. More robustly designed single modality randomized controlled trials utilizing standardized reporting and precise outcome assessments are required to determine the extent of health outcomes attributable solely to RT and to enable the development of evidence-based obesity prevention and treatment strategies in this cohort.
Assuntos
Metabolismo Energético/fisiologia , Levantamento de Peso/fisiologia , Adolescente , Criança , Feminino , Humanos , Masculino , Força Muscular/fisiologia , SegurançaRESUMO
BACKGROUND: High-intensity progressive resistance training (PRT) improves adiposity and metabolic risk in adults, but has not been investigated in children within a randomized controlled trial (RCT). OBJECTIVE: We hypothesized that high-intensity PRT (8 weeks, twice a week) would decrease central adiposity in children, as assessed via waist circumference. METHODS DESIGN/SETTING/PARTICIPANTS: Concealed randomization stratified by age and gender was used to allocate rural New Zealand school students to the wait-list control or PRT group. INTERVENTION: Participants were prescribed two sets (eight repetitions per set) of 11 exercises targeting all the major muscle groups at high intensity. PRIMARY OUTCOME: Waist circumference; secondary outcomes included whole body fat, muscular fitness (one repetition maximum), cardiorespiratory fitness (peak oxygen consumption during a treadmill test), lipids, insulin sensitivity and fasting glucose. RESULTS: Of the 78 children (32 girls and 46 boys; mean age 12.2(1.3) years), 51% were either overweight (33%) or obese (18%). High-intensity PRT significantly improved waist circumference (mean change PRT -0.8 (2.2) cm vs +0.5 (1.7) cm control; F=7.59, P=0.008), fat mass (mean change PRT +0.2 (1.4) kg vs +1.0 (1.2) kg control; F=6.00, P=0.017), percent body fat (mean change PRT -0.3 (1.8)% vs +1.2 (2.1)% control; F=9.04, P=0.004), body mass index (mean change PRT -0.01 (0.8) kg m(-2) vs +0.4 (0.7) kg m(-2) control; F=6.02, P=0.017), upper body strength (mean change PRT+11.6(6.1) kg vs +2.9(3.7) kg control; F=48.6, P<0.001) and lower body strength (mean change PRT +42.9(26.6) kg vs +28.5(26.6) kg control; F=4.72, P=0.034) compared to the control group. Waist circumference decreased the most in those with the greatest baseline relative strength (r=-0.257, P=0.036), and greatest relative (r=-0.400, P=0.001) and absolute (r=0.340, P=0.006) strength gains during the intervention. CONCLUSION: Isolated high-intensity PRT significantly improves central and whole body adiposity in association with muscle strength in normal-weight and overweight children. The clinical relevance and sustainability of these changes in adiposity should be addressed in future long-term studies.
Assuntos
Adiposidade/fisiologia , Obesidade/terapia , Treinamento Resistido , Circunferência da Cintura , Adolescente , Glicemia , Composição Corporal , Índice de Massa Corporal , Criança , Colesterol/sangue , Impedância Elétrica , Feminino , Humanos , Insulina/sangue , Resistência à Insulina , Modelos Lineares , Masculino , Força Muscular/fisiologia , Nova Zelândia , Obesidade/sangue , Estudantes , Triglicerídeos/sangueRESUMO
An active cognitive lifestyle has been suggested to have a protective role in the long-term maintenance of cognition. Amongst healthy older adults, more managerial or supervisory experiences in midlife are linked to a slower hippocampal atrophy rate in late life. Yet whether similar links exist in individuals with Mild Cognitive Impairment (MCI) is not known, nor whether these differences have any functional implications. 68 volunteers from the Sydney SMART Trial, diagnosed with non-amnestic MCI, were divided into high and low managerial experience (HME/LME) during their working life. All participants underwent neuropsychological testing, structural and resting-state functional MRI. Group comparisons were performed on hippocampal volume, morphology, hippocampal seed-based functional connectivity, memory and executive function and self-ratings of memory proficiency. HME was linked to better memory function (p = 0.024), mediated by larger hippocampal volume (p = 0.025). More specifically, deformation analysis found HME had relatively more volume in the CA1 sub-region of the hippocampus (p < 0.05). Paradoxically, this group rated their memory proficiency worse (p = 0.004), a result correlated with diminished functional connectivity between the right hippocampus and right prefrontal cortex (p < 0.001). Finally, hierarchical regression modelling substantiated this double dissociation.
Assuntos
Envelhecimento/patologia , Envelhecimento/fisiologia , Emprego , Função Executiva/fisiologia , Hipocampo/patologia , Hipocampo/fisiologia , Liderança , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico , Feminino , Estilo de Vida Saudável/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão/fisiologia , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
UNLABELLED: The relationship between excess abdominal adipose tissue, metabolic and cardiovascular health risk has stimulated interest in the efficacy of physical activity in specifically perturbing this adipose depot. The evolution of imaging techniques has enabled more direct measurement of changes in abdominal and visceral fat. The purpose of this summary was to systematically review the relationship between physical activity and abdominal fat. METHODS: Database searches were performed on MEDLINE, CINAHL, SPORT DISCUS and PUBMED, from 1985 to 2005 with keywords "exercise", "abdominal fat" and "visceral fat". RESULTS: Nineteen randomized controlled trials (RCTs) and eight non-randomized controlled trials were selected. In RCTs using imaging techniques to measure change in abdominal fat in overweight or obese subjects, seven out of 10 studies (including three trials with type 2 diabetics) reported significant reductions compared with controls. Reductions in visceral and total abdominal fat may occur in the absence of changes in body mass and waist circumference. Waist-to-hip ratio is not a sensitive measure of change in regional adiposity in exercise studies. No studies fulfil the Consolidated Standards of Reporting Trials (CONSORT) statement's criteria for the highest quality of randomized trial; however, many studies were in progress or published before the opportunity to comply with these recommendations. Therefore, limited evidence from a number of studies suggests a beneficial influence of physical activity on reduction in abdominal and visceral fat in overweight and obese subjects when imaging techniques are used to quantify changes in abdominal adiposity. More rigorous studies are needed to confirm these observations.
Assuntos
Gordura Abdominal/metabolismo , Exercício Físico/fisiologia , Obesidade/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Metabolismo Energético , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/metabolismo , Aptidão Física/fisiologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Redução de PesoRESUMO
The longitudinal changes in isokinetic strength of knee and elbow extensors and flexors, muscle mass, physical activity, and health were examined in 120 subjects initially 46 to 78 years old. Sixty-eight women and 52 men were reexamined after 9.7 +/- 1.1 years. The rates of decline in isokinetic strength averaged 14% per decade for knee extensors and 16% per decade for knee flexors in men and women. Women demonstrated slower rates of decline in elbow extensors and flexors (2% per decade) than men (12% per decade). Older subjects demonstrated a greater rate of decline in strength. In men, longitudinal rates of decline of leg muscle strength were approximately 60% greater than estimates from a cross-sectional analysis in the same population. The change in leg strength was directly related to the change in muscle mass in both men and women, and it was inversely related to the change in medication use in men. Physical activity declined yet was not directly associated with strength changes. Although muscle mass changes influenced the magnitude of the strength changes over time, strength declines in spite of muscle mass maintenance or even gain emphasize the need to explore the contribution of other cellular, neural, or metabolic mediators of strength changes.
Assuntos
Envelhecimento/fisiologia , Músculo Esquelético/fisiologia , Esforço Físico/fisiologia , Idoso , Estudos Transversais , Feminino , Nível de Saúde , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Fatores SexuaisRESUMO
BACKGROUND: Frail institutionalized elders have a high prevalence of nutritional risk factors, undernutrition, weight loss, and nutrition-related morbidity and excess mortality. Little information is available on effective means to intervene in this setting. HYPOTHESES: We tested the hypothesis that addition of multinutrient oral supplements to the diet of frail elders would improve their overall nutritional status and functional level. METHODS: Fifty nursing home residents aged 88+/-1 yr. were followed for 10 weeks in the course of a randomized controlled trial of supplementation with a multinutrient liquid supplement vs. a non-nutritive placebo drink. Three-day food weighing was used to analyze their habitual dietary intake before and during the final week of the intervention. Nutritional status was further assessed with nutritional biochemistries, anthropometric measurements, and body composition analysis as well as physical and functional performance tests. RESULTS: The nutritional supplement was consumed with high compliance, but did not significantly augment total caloric intake. Supplementation was associated with significant reductions in total energy, protein, fat, water, fiber, and many vitamins and minerals in the habitual diet of these nursing home residents. Nutritional status improved in terms of folate levels in serum, but no other measured vitamin or mineral indices. Body composition analysis revealed a small gain in weight, increases in fat stores, but no improvement in lean tissue mass associated with supplemention. No physical performance or functional gains were associated with supplementation. CONCLUSION: Short-term nutritional supplementation in elders at nutritional risk is offset by simultaneous reduction in voluntary food intake. It seems likely that changing other components of energy expenditure such as physical activity levels or basal metabolism may be required to produce overall improvements in nutritional intake in this setting.
Assuntos
Envelhecimento , Suplementos Nutricionais , Idoso Fragilizado , Estado Nutricional , Idoso , Idoso de 80 Anos ou mais , Composição Corporal , Ingestão de Energia , Feminino , Ácido Fólico/sangue , Humanos , Masculino , Casas de Saúde , Cooperação do Paciente , PlacebosRESUMO
BACKGROUND: While strict criteria have been developed for defining osteoporosis in women (bone mineral density measurements more than 2.5 standard deviations below the mean for young adult normal women, i.e. t-score value < -2.5), there still remains a controversy regarding the definition in men. Spinal fractures occur in 5% and hip fractures in 6% of men older than 50 years. There are significant differences between men and women with respect to the pathogenesis of osteoporosis, underlying medical conditions and postfracture sequelae. OBJECTIVE: To provide an overview of the pathogenesis, diagnosis and prevention of osteoporosis in men. DISCUSSION: Osteoporosis is increasingly recognised. Data from the Dubbo Osteoporosis Epidemiology Study suggests that 30% of men in Australia aged over 60 years will suffer from an osteoporotic fracture. It is estimated that 30-60% of men presenting with spinal fractures will have another illness contributing to their bone loss. Osteoporotic fractures in men are associated with higher morbidity and mortality than in women. Lifestyle changes together with daily calcium supplementation should be implemented and vitamin D3 should be considered in men with osteopenia.
Assuntos
Osteoporose/diagnóstico , Osteoporose/prevenção & controle , Densidade Óssea , Cálcio da Dieta , Colecalciferol , Humanos , Masculino , Pessoa de Meia-Idade , Osteoporose/etiologia , Fatores de RiscoRESUMO
BACKGROUND: Osteoporosis is associated with significant morbidity and mortality in men. Published randomised controlled trials assessing the benefits of therapy in men with osteoporosis are limited, but those available need to be used to develop management guidelines. OBJECTIVE: To present evidence based guidelines for the treatment of osteoporosis in men. DISCUSSION: It is estimated that 30-60% of men presenting with spinal fractures have another illness contributing to their bone disease. Therefore assessment and treatment of coexisting medical conditions is a vital part of management of osteoporosis. While primary prevention of fractures remains crucial, treatment to ensure further fractures do not occur is equally important. Alendronate is the treatment of choice for men with osteoporosis and fractures, with cyclical etidronate an appropriate alternative and testosterone replacement therapy is indicated in hypogonadal men presenting with osteoporosis.
Assuntos
Osteoporose/prevenção & controle , Calcitriol/uso terapêutico , Cálcio da Dieta , Difosfonatos/uso terapêutico , Humanos , Masculino , Guias de Prática Clínica como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Testosterona/uso terapêutico , Vitamina DRESUMO
BACKGROUND: Last year, Australian Family Physician published 'Guidelines for Management of Postmenopausal Osteoporosis', which were developed by Osteoporosis Australia. Recently, significant advances in our understanding of the treatment of corticosteroid osteoporosis have occurred. OBJECTIVE: The following guidelines, also developed by Osteoporosis Australia, and supported by the National Asthma Campaign, are to help general practitioners identify those patients at risk of this problem and to provide information about current treatment strategies. DISCUSSION: Corticosteroids are widely used and effective agents for the control of many inflammatory diseases. Corticosteroid osteoporosis is a common problem associated with the long term high dose use of these medications.
Assuntos
Corticosteroides/efeitos adversos , Osteoporose Pós-Menopausa/induzido quimicamente , Osteoporose Pós-Menopausa/prevenção & controle , Cálcio da Dieta , Difosfonatos/uso terapêutico , Feminino , Terapia de Reposição Hormonal , Humanos , Moduladores Seletivos de Receptor Estrogênico/uso terapêutico , Vitamina DRESUMO
OBJECTIVE: Lean body weight (LBW) decreases with age while total body fat increases, resulting in altered drug pharmacokinetics. A semi-mechanistic equation estimating LBW using height, weight and sex has been developed for potential use across a wide range of body compositions. The aim of this study was to determine the ability of the LBW equation to estimate dual energy x-ray absorptiometry-derived fat free mass (FFM(DXA)) in a population of older women with recent hip fracture. METHODS: Baseline, four and 12 month data obtained from 23 women enrolled in the Sarcopenia and Hip Fracture study were pooled to give 58 measurements. LBW was estimated using the equation: LBW (kg) = (9270 x Wt) / (8780 + (244 x BMI)). Body composition was classified as: 'normal' (BMI <25kg/m(2) and not sarcopenic), 'overweight-obese' (BMI >25kg/m(2) and not sarcopenic), 'sarcopenic' (sarcopenic and BMI <25kg/m(2)), or 'sarcopenic-obese' (sarcopenic and BMI >25kg/m(2)). The ability of the LBW equation to predict FFMDXA was determined graphically using Bland-Altman plots and quantitatively using the method of Sheiner and Beal. RESULTS: The mean ± SD age of female participants women was 83±7 years (n=23). Sarcopenia was frequently observed (65.2%). Bland-Altman plots demonstrated an underestimation by the LBW equation compared to FFMDXA. The bias (95% CI) and precision (95% CI) calculated using the method of Sheiner and Beal was 0.5kg (-0.7, 1.66kg) and 4.4kg (-3.7, 12.4kg) respectively for pooled data. CONCLUSION: This equation can be used to easily calculate LBW. When compared to FFMDXA, the LBW equation resulted in a small underestimation on average in this population of women with recent hip fracture. The degree of bias may not be clinically important although further studies of larger heterogeneous cohorts are needed to investigate and potentially improve the accuracy of this predictive equation in larger clinical cohorts.
Assuntos
Composição Corporal/fisiologia , Peso Corporal/fisiologia , Matemática/normas , Músculo Esquelético/fisiologia , Absorciometria de Fóton/métodos , Absorciometria de Fóton/normas , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/patologia , Feminino , Fraturas do Quadril/epidemiologia , Fraturas do Quadril/etiologia , Humanos , Músculo Esquelético/patologia , Valor Preditivo dos Testes , Sarcopenia/complicações , Sarcopenia/diagnósticoRESUMO
OBJECTIVE: Meniscus tears are often presumed to be associated with a traumatic event, but they can also occur as a result of the cartilage degeneration process in osteoarthritis (OA). The aim of this paper is to describe the prevalence and clinical correlates of degenerative meniscus tears in women with knee OA. METHOD: The subjects were women screened for a double-blind, sham-exercise controlled clinical trial for women over 40 years of age with OA in at least one knee, according to American College of Rheumatology (ACR) clinical criteria. The presence of meniscus tears was assessed via a 3T Intera (Philips Medical Systems) magnetic resonance image (MRI). Clinical examination included a history of arthritis onset and physical examination of the lower extremities. Physical assessments included body composition, muscle strength, walking endurance, gait velocity, and balance. In addition, pain and disability secondary to OA, physical self-efficacy, depressive symptoms, habitual physical activity level and quality of life were assessed via questionnaires. RESULTS: Almost three-quarters (73%) of the 41 subjects had a medial, lateral, or bilateral meniscus tear by MRI. Walking endurance and balance performance were significantly impaired in subjects with a degenerative meniscus tear, compared to subjects without tears, despite similar OA duration, symptoms, and disability, body composition, and other clinical characteristics. CONCLUSION: Meniscus tears, diagnosed by MRI, are very common in older women with knee OA, particularly in the medial compartment. These incidentally discovered tears are associated with clinically relevant impairments of balance and walking endurance relative to subjects without meniscus tears. The explanation for this association requires further study.
Assuntos
Cartilagem/patologia , Imageamento por Ressonância Magnética/métodos , Limitação da Mobilidade , Osteoartrite do Joelho/patologia , Medição da Dor/métodos , Lesões do Menisco Tibial , Idoso , Estudos Transversais , Feminino , Humanos , Meniscos Tibiais/patologia , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Fatores Sexuais , Inquéritos e QuestionáriosRESUMO
The benefits of dietary creatine supplementation on muscle performance are generally related to an increase in muscle phosphocreatine content. However, creatine supplementation may benefit endurance sports through increased glycogen re-synthesis following exercise. This study investigated the effect of creatine supplementation on muscle glycogen content, submaximal exercise fuel utilisation and endurance performance following 4 weeks of endurance training. Thirteen healthy, physically active, non-vegetarian subjects volunteered to take part and completed the study. Subjects were supplemented with either creatine monohydrate (CREAT, n = 7) or placebo-maltodextrin (CON, n = 6). Submaximal fuel utilisation and endurance performance were assessed before and after a 4 week endurance training program. Muscle biopsies were also collected before and following training for assessment of muscle creatine and glycogen content. Training increased quadriceps glycogen content to the same degree (approximately 20%) in both groups (P = 0.04). There was a significant training effect on submaximal fuel utilisation and improved endurance performance. However, there was no significant treatment effect of creatine supplementation. Creatine supplementation does not effect metabolic adaptations to endurance training.
Assuntos
Adaptação Fisiológica , Creatina/farmacologia , Suplementos Nutricionais , Exercício Físico/fisiologia , Resistência Física/efeitos dos fármacos , Adolescente , Adulto , Antropometria , Carboidratos/química , Gorduras/metabolismo , Feminino , Glicogênio/análise , Humanos , Masculino , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Oxirredução , Resistência Física/fisiologiaRESUMO
A system in vitro consisting of a femur from a cadaver and soft-tissue equivalent material was used to test the agreement between several techniques for measuring bone mineral. Calcium values measured by delayed gamma neutron activation (DGNA) and bone mineral content (BMC) by Lunar, Hologic and Norland dual-energy X-ray absorptiometers (DXA) were compared with calcium and ash content determined by direct chemical analysis. To assess the effect of soft-tissue thickness on measurements of bone mineral, we had three phantom configurations ranging from 15.0 to 26.0 cm in thickness, achieved by using soft-tissue equivalent overlays. Chemical analysis of the femur gave calcium and ash content values of 61.83 g +/- 0.51 g and 154.120 +/- 0.004 g, respectively. Calcium measured by DGNA did not differ from the ashed amount of calcium at any of the phantom configurations. The BMC measured by DXA was significantly higher, by 3-5%, than the amount determined by chemical analysis for the Lunar densitometer and significantly lower, by 3-6%, for the Norland densitometer (p<0.001-0.024), but only 1% lower (not significant) for the Hologic densitometer. DXA instruments showed a decreasing trend in BMC as the thickness increased from 20.5 to 26.0 cm (p<0.05). However, within the entire thickness range (15.0-26.0 cm), the overall influence of thickness on BMC by DXA was very small. These findings offer insight into the differences in these currently available methods for bone mineral measurement and challenge the comparability of different methods.