Correlates of individual differences in body-composition changes resulting from physical training in obese children.
(9/2834)
BACKGROUND: No studies have been reported in children that assess correlates of body-composition changes in response to a physical training intervention. OBJECTIVE: The hypothesis studied was that variation in diet and physical activity would explain a significant portion of the interindividual variation in the response of body composition to physical training. DESIGN: The participants were 71 obese children aged 7-11 y (22 boys, 49 girls; 31 whites, 40 blacks). Body composition was measured by dual-energy X-ray absorptiometry, physical activity by a 7-d recall interview, and diet by two, 2-d recalls. The children underwent 4 mo of physical training. RESULTS: The mean attendance was 4 d/wk, the mean (+/-SD) heart rate for the 40-min sessions was 157 +/- 7 beats/min, and the mean energy expenditure was 946 +/- 201 kJ/session. On average, the percentage body fat decreased significantly in the total group, and total mass, fat-free soft tissue, bone mineral content, and bone mineral density increased, but there was a good deal of individual variability. Multiple regression models indicated that in general, more frequent attendance, being a boy, lower energy intake, and more vigorous activity were associated with healthier body-composition changes with physical training. Ethnicity was not retained as a correlate of the change of any component of body composition. CONCLUSIONS: In obese children, age, vigorous activity, diet, and baseline percentage body fat together accounted for 25% of the variance in the change in percentage body fat with physical training. (+info)
Randomised controlled trial of vitamin D supplementation on bone density and biochemical indices in preterm infants.
(10/2834)
AIMS: To test the hypothesis that a vitamin D dose of 200 IU/kg, maximum 400 IU/day, given to preterm infants will maintain normal vitamin D status and will result in as high a bone mineral density as that attained with the recommended dose of 960 IU/day. METHODS: Thirty nine infants of fewer than 33 weeks of gestational age were randomly allocated to receive vitamin D 200 IU/kg of body weight/day up to a maximum of 400 IU/day or 960 IU/day until 3 months old. Vitamin D metabolites, bone mineral content and density were determined by dual energy x-ray absorptiometry, and plasma ionised calcium, plasma alkaline phosphatase, and intact parahormone measurements were used to evaluate outcomes. RESULTS: The 25 hydroxy vitamin D concentrations tended to be higher in infants receiving 960 IU/day, but the differences did not reach significance at any age. There was no difference between the infants receiving low or high vitamin D dose in bone mineral content nor in bone mineral density at 3 and 6 months corrected age, even after taking potential risk factors into account. CONCLUSIONS: A vitamin D dose of 200 IU/kg of body weight/day up to a maximum of 400 IU/day maintains normal vitamin D status and as good a bone mineral accretion as the previously recommended higher dose of 960 IU/day. Vitamin D is a potent hormone which affects organs other than bone and should not be given in excess to preterm infants. (+info)
Body composition of preterm infants during infancy.
(11/2834)
AIMS: To examine body composition in preterm infants. METHODS: Body composition was measured by dual energy x-ray absorptiometry (DEXA) at hospital discharge, term, 12 weeks, and at 6 and 12 months corrected age in 125 infants (birthweight < or = 1750 g, gestational age < or = 34 weeks). RESULTS: Body weight derived by DEXA accurately predicted that determined by conventional scales. In both sexes lean mass (LM), fat mass (FM), %FM, bone area (BA), bone mineral mass (BMM), and bone mineral density (BMD) increased rapidly during the study; significant changes were detectable between discharge and term. At 12 months, LM, BA, and BMM, but not FM, %FM, or BMD were greater in boys than in girls. Corrected for age, LM was less than those of the reference term infant; FM and %FM were similar; BMM was greater. Corrected for weight, LM was similar to those of the reference infant, while the FM and %FM of study infants were slightly greater. CONCLUSIONS: DEXA accurately measures body mass. Body composition in preterm boys and girls differs. Interpretation of DEXA values may depend on whether age or body weight are regarded as the appropriate reference. (+info)
Age-related bone loss: relationship between age and regional bone mineral density.
(12/2834)
We assessed the changes in regional bone mineral density according to age and examined the relationship between various regional bone mineral densities. The study was conducted in 985 Japanese women divided into < 50-years group (n = 435) and > or = 50 years group (n = 550). The total body bone mineral density and that of the head, arm, leg, thoracic (T)-spine, lumbar (L)-spine, ribs, and pelvis were measured using dual energy x-ray absorptiometry. There was a significant generalized reduction of bone mineral density in all regions after the age of 50 years. The most marked age-related decrease was observed in the L-spine. Bone mineral densities in all regions significantly correlated to each other in both age groups, but the degree of significance varied among regions. The relationship between bone mineral density of the L-spine and that of T-spine regions was the most significant in both groups. In the < 50-years group, the correlation between bone mineral density of the pelvis and that of L-spine and T-spine was the highest, followed by that between the pelvis and the leg. On the other hand, in the > or = 50-years group, the correlation between bone mineral density of the pelvis and that of the leg was the highest, but not the L-spine or T-spine. Since spine measurements are affected by vertebral deformity and/or aortic calcification, our findings suggest the pelvis may be a useful region for screening measurements of bone mineral density, especially in older women. (+info)
Growth hormone treatment of osteoporotic postmenopausal women - a one-year placebo-controlled study.
(13/2834)
OBJECTIVES: To study the effect of 12 months of growth hormone (GH) treatment on bone markers, bone mineral density (BMD), lean body mass (LBM) and body fat mass (BF) in postmenopausal osteoporotic women. DESIGN: Sixteen patients were randomised to a double-blind randomised placebo-controlled one-year study with daily s.c. injections of GH or placebo. After the first year 14 patients (8 placebo treated, 6 GH treated) were recruited to GH treatment during the second year. All patients were also supplemented with 0.5 g calcium per oral. METHODS: Bone mineral density and body composition were assessed by dual energy X-ray absorptiometry. Biochemical bone markers were analysed by RIA or HPLC techniques. Diurnal GH profiles were performed with continuous venous blood sampling. RESULTS: Sixteen patients started in the placebo-controlled study. In all, twelve patients completed one year and only four patients completed two years of GH treatment. At baseline 3 patients had serum insulin-like growth factor-I (S-IGF-I) levels below -2 S.D. for age. Maximal diurnal GH levels tended to correlate negatively with S-IGF-I (P=0.076). S-IGF-I was unrelated to BMD. Serum IGF-binding protein-1 (S-IGFBP-1) correlated negatively with femoral neck BMD (r=-0.61, P=0.012). The intended GH dose of 0.05U/kg/day or a maximum of 3U/day s.c. was reduced to 0.024+/-0.004U/kg/day, equal to 0.5-2.7U/day due to frequent side effects, and four patients were excluded. After one year of GH treatment BF increased slightly, LBM and BMD in total body and lumbar spine were unchanged but femoral neck BMD had decreased 3.4+/-1.6% (P<0.05). The mean S-IGF-I increase was 32% (range -38-138%). Mean levels of the bone formation markers S-osteocalcin and S-procollagen type I propeptide increased maximally by 88 and 36% respectively after 9-12 months while the bone resorption markers were unchanged. In the placebo-treated group there were no significant alterations. CONCLUSIONS: The effects on S-IGF-I, bone markers and LBM were small although GH-related side effects were common. The reason for this apparent partial resistance to the anabolic effects of GH is not clear but nutritional deficits may be involved. Assessment of the effects of GH on bone mass and fracture rate requires longer study periods than one year. (+info)
Strong association between malnutrition, inflammation, and atherosclerosis in chronic renal failure.
(14/2834)
BACKGROUND: Atherosclerotic cardiovascular disease and malnutrition are widely recognized as leading causes of the increased morbidity and mortality observed in uremic patients. C-reactive protein (CRP), an acute-phase protein, is a predictor of cardiovascular mortality in nonrenal patient populations. In chronic renal failure (CRF), the prevalence of an acute-phase response has been associated with an increased mortality. METHODS: One hundred and nine predialysis patients (age 52 +/- 1 years) with terminal CRF (glomerular filtration rate 7 +/- 1 ml/min) were studied. By using noninvasive B-mode ultrasonography, the cross-sectional carotid intima-media area was calculated, and the presence or absence of carotid plaques was determined. Nutritional status was assessed by subjective global assessment (SGA), dual-energy x-ray absorptiometry (DXA), serum albumin, serum creatinine, serum urea, and 24-hour urine urea excretion. The presence of an inflammatory reaction was assessed by CRP, fibrinogen (N = 46), and tumor necrosis factor-alpha (TNF-alpha; N = 87). Lipid parameters, including Lp(a) and apo(a)-isoforms, as well as markers of oxidative stress (autoantibodies against oxidized low-density lipoprotein and vitamin E), were also determined. RESULTS: Compared with healthy controls, CRF patients had an increased mean carotid intima-media area (18.3 +/- 0.6 vs. 13.2 +/- 0.7 mm2, P < 0.0001) and a higher prevalence of carotid plaques (72 vs. 32%, P = 0.001). The prevalence of malnutrition (SGA 2 to 4) was 44%, and 32% of all patients had an acute-phase response (CRP > or = 10 mg/liter). Malnourished patients had higher CRP levels (23 +/- 3 vs. 13 +/- 2 mg/liter, P < 0.01), elevated calculated intima-media area (20.2 +/- 0.8 vs. 16.9 +/- 0.7 mm2, P < 0.01) and a higher prevalence of carotid plaques (90 vs. 60%, P < 0.0001) compared with well-nourished patients. During stepwise multivariate analysis adjusting for age and gender, vitamin E (P < 0.05) and CRP (P < 0.05) remained associated with an increased intima-media area. The presence of carotid plaques was significantly associated with age (P < 0.001), log oxidized low-density lipoprotein (oxLDL; P < 0.01), and small apo(a) isoform size (P < 0.05) in a multivariate logistic regression model. CONCLUSION: These results indicate that the rapidly developing atherosclerosis in advanced CRF appears to be caused by a synergism of different mechanisms, such as malnutrition, inflammation, oxidative stress, and genetic components. Apart from classic risk factors, low vitamin E levels and elevated CRP levels are associated with an increased intima-media area, whereas small molecular weight apo(a) isoforms and increased levels of oxLDL are associated with the presence of carotid plaques. (+info)
Bone loss in long-term renal transplantation: histopathology and densitometry analysis.
(15/2834)
BACKGROUND: There is little information of the spectrum and factors implicated in the bone loss in long-term renal transplantation, and virtually no data using both histomorphometric and densitometric analysis. METHODS: Twenty-three males and 22 females (13 postmenopausal) were studied with a bone biopsy and densitometry. Sixteen patients were on cyclosporine A monotherapy, 20 on azathioprine + prednisolone, and 9 on cyclosporine A + prednisolone or triple therapy. The mean time after transplantation was 127 +/- 70 months. RESULTS: No group had a significant decrease in bone mineral density (BMD) of the axial skeleton compared with an age- and sex-matched normal population. Compared with sex-matched young controls, osteopenia was observed in all groups at the femoral neck (except premenopausal women and triple therapy) and in the triple-therapy group at the L1-L4 spine region. At the distal radius, osteopenia was found in all the groups. Histopathological diagnosis was mixed uremic osteodystrophy in 46.5%, adynamic bone in 23.2%, hyperparathyroid disease in 13.9%, and normal bone in 16.3%. The diagnosis was not different according to immunosuppressive therapy, but men tended to show more mixed uremic bone disease. There was no significant difference in BMD between histopathological subtypes. In general, patients showed slight osteoclast function increase, osteoblast function decrease, and marked retardation of dynamic parameters. The cyclosporine A monotherapy group had a significantly lower appositional rate than azathioprine + prednisolone. Men had a significantly lower bone volume than women, and premenopausal women had a significantly lower mineralizing surface than postmenopausal women and men. In the multivariate analysis, male gender, time after transplantation, old age, and time on dialysis prior to transplantation were significant predictive factors for a negative effect on bone mass. CONCLUSIONS: Long-term renal transplant-patients showed reduced BMD in both trabecular and cortical bone. This reduction in BMD was not as severe as in short-term reports and was associated with osteoclast stimulation, osteoblast suppression, and retardation of mineral apposition and bone formation rates. Bone mass loss was not different between the immunosuppression therapy groups. Male gender and age were the strongest predictive factors for low bone mass. (+info)
Hydration of fat-free body mass: review and critique of a classic body-composition constant.
(16/2834)
The assumed "constancy" of fat-free body mass hydration is a cornerstone in the body-composition research field. Hydration, the observed ratio of total body water to fat-free body mass, is stable at approximately 0.73 in mammals and this constancy provides a means of estimating total body fat in vivo. This review examines both in vitro and in vivo data that support the hydration constancy hypothesis and provides a critique of applied methodology. Biological topics of interest are then examined and critical areas in need of future research are identified. These are important issues because water dilution is the only method currently available for estimating body fat in all mammals, which range in body mass by a factor of 10(4). (+info)