Assessing the robustness of muscle strength and physical performance measures in women older than 40 years: a test-retest reliability study.

OBJECTIVES: This study investigated the test-retest reliability and minimal detectable change (MDC) of muscle strength and physical performance tests in women older than 40 years. METHODS: A total of 113 women, aged 58 ± 11 years (82% postmenopausal women), with a body mass index of 28.5 ± 5.8 kg/m 2 , participated in this study. One-repetition maximum (1RM) tests were conducted for seven strength exercises: 45° leg press, bench press, leg extension, pec deck, wide-grip lateral pull-down, leg curl, and seated cable row, with a retest after 48 hours. Timed Up and Go (TUG), 6-minute walk, and 30-second sit-to-stand tests were performed on the same day and retested after 72 hours. The tests and retests were administered by the same evaluators. Relative reliability (consistency of participant rank between test-retest) was assessed using the intraclass correlation coefficient for consistency and agreement, and absolute reliability (precision of score) was assessed using the MDC based on the standard error of prediction. RESULTS: The 1RM and performance tests exhibited excellent reliability: 45° leg press (consistency, 0.99; agreement, 0.98), bench press (consistency, 0.96; agreement, 0.96), leg extension (consistency, 0.93; agreement, 0.91), pec deck (consistency, 0.90; agreement, 0.88), wide-grip lateral pull-down (consistency, 0.91; agreement, 0.89), leg curl (consistency, 0.84; agreement, 0.83), seated cable row (consistency, 0.92; agreement, 0.94), TUG (consistency, 0.87; agreement, 0.87), 6-minute walk (consistency, 0.96; agreement, 0.95), and 30-second sit to stand (consistency, 0.85; agreement, 0.80). These tests showed meaningful MDC values, particularly for the 1RM test performed on the machine and the 30-second sit-to-stand test: 45° leg press, 22.2 kg (15%); bench press, 4.9 kg (19%); leg extension, 9.2 kg (35%); pec deck, 8.8 kg (44%); wide-grip lateral pull-down, 9.4 kg (31%); leg curl, 9.2 kg (51%); seated cable row, 11.4 kg (29%); TUG, 1.4 seconds (20%); 6-minute walk, 50.9 m (10%); and 30-second sit to stand, 4.6 reps (30%). CONCLUSIONS: Although the muscle strength and physical performance tests demonstrate excellent relative reliability in women older than 40 years, they exhibit low absolute reliability, particularly the 1RM test performed on the machine and the 30-second sit-to-stand test. Therefore, although these tests show good consistency in the positioning of women within the group after repeated measures, their precision measure is relatively low (high fluctuation). Changes in these tests that are smaller than the MDC may not indicate real changes in women at middle age and older.

Proteomic profiling of the rat hypothalamus.

BACKGROUND: The hypothalamus plays a pivotal role in numerous mechanisms highly relevant to the maintenance of body homeostasis, such as the control of food intake and energy expenditure. Impairment of these mechanisms has been associated with the metabolic disturbances involved in the pathogenesis of obesity. Since rodent species constitute important models for metabolism studies and the rat hypothalamus is poorly characterized by proteomic strategies, we performed experiments aimed at constructing a two-dimensional gel electrophoresis (2-DE) profile of rat hypothalamus proteins. RESULTS: As a first step, we established the best conditions for tissue collection and protein extraction, quantification and separation. The extraction buffer composition selected for proteome characterization of rat hypothalamus was urea 7 M, thiourea 2 M, CHAPS 4%, Triton X-100 0.5%, followed by a precipitation step with chloroform/methanol. Two-dimensional (2-D) gels of hypothalamic extracts from four-month-old rats were analyzed; the protein spots were digested and identified by using tandem mass spectrometry and database query using the protein search engine MASCOT. Eighty-six hypothalamic proteins were identified, the majority of which were classified as participating in metabolic processes, consistent with the finding of a large number of proteins with catalytic activity. Genes encoding proteins identified in this study have been related to obesity development. CONCLUSION: The present results indicate that the 2-DE technique will be useful for nutritional studies focusing on hypothalamic proteins. The data presented herein will serve as a reference database for studies testing the effects of dietary manipulations on hypothalamic proteome. We trust that these experiments will lead to important knowledge on protein targets of nutritional variables potentially able to affect the complex central nervous system control of energy homeostasis.

Identification and characterization of Gluconacetobacter diazotrophicus mutants defective in the solubilization of phosphorus and zinc.

Gluconacetobacter diazotrophicus is a plant-growth-promoting bacterium, which is able to colonize sugarcane and other plant species of economic importance. The potentially beneficial effects promoted by this bacterium on plants are nitrogen-fixation, production of phythormones, action against pathogens and mineral nutrient solubilization. In this study, the molecular mechanisms associated with phosphorus and zinc solubilization were analyzed. A transposon mutant library was constructed and screened to select for mutants defective for phosphorous [Ca(5)(PO(4))(3)OH] and zinc (ZnO) solubilization. A total of five mutants were identified in each screen. Both screenings, performed independently, allowed to select the same mutants. The interrupted gene in each mutant was identified by sequencing and the results demonstrate that the production of gluconic acid is a required pathway for solubilization of such nutrients in G. diazotrophicus.