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Currently there is no consensus on the impact of dietary protein on calcium and bone metabolism. This study was conducted to examine the effect of increasing protein intake on urinary calcium excretion and to compare circulating levels of IGF-I and biochemical markers of bone turnover in healthy older men and women who consumed either a high or a low protein food supplement for 9 wk. Thirty-two subjects with usual protein intakes of less than 0.85 g/kg.d were randomly assigned to daily high (0.75 g/kg) or low (0.04 g/kg) protein supplement groups. Isocaloric diets were maintained by advising subjects to reduce their intake of carbohydrates. Selected biochemical measurements were made at baseline and on d 35 and either d 49 or 63. Changes in urinary calcium excretion in the two groups did not differ significantly over the course of the study. The high protein group had significantly higher levels of serum IGF-I (P = 0.008) and lower levels of urinary N-telopeptide (P = 0.038) over the period of d 35-49 or 63. We conclude that increasing protein intake from 0.78 to 1.55 g/kg.d with meat supplements in combination with reducing carbohydrate intake did not alter urine calcium excretion, but was associated with higher circulating levels of IGF-I, a bone growth factor, and lowered levels of urinary N-telopeptide, a marker of bone resorption. In contrast to the widely held belief that increased protein intake results in calcium wasting, meat supplements, when exchanged isocalorically for carbohydrates, may have a favorable impact on the skeleton in healthy older men and women.

Background: Little is known about the determinants of individual variability in body weight and fat loss after gastric bypass surgery or about the effects of massive weight loss induced by this surgery on energy requirements., Objectives: The objectives were to determine changes in energy expenditure and body composition with weight loss induced by gastric bypass surgery and to identify presurgery predictors of weight loss., Design: Thirty extremely obese women and men with a mean (+/- SD) age of 39.0 +/- 9.6 y and a body mass index (BMI; in kg/m(2)) of 50.1 +/- 9.3 were tested longitudinally under weight-stable conditions before surgery and after weight loss and stabilization (14 +/- 2 mo). Total energy expenditure (TEE), resting energy expenditure (REE), body composition, and fasting leptin were measured., Results: Subjects lost 53.2 +/- 22.2 kg body weight and had significant decreases in REE (-2.4 +/- 1.0 MJ/d; P < 0.001) and TEE (-3.6 +/- 2.5 MJ/d; P < 0.001). Changes in REE were predicted by changes in fat-free mass and fat mass. The average physical activity level (TEE/REE) was 1.61 at both baseline and follow-up (P = 0.98). Weight loss was predicted by baseline fat mass and BMI but not by any energy expenditure variable or leptin. Measured REE at follow-up was not significantly different from predicted REE., Conclusions: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain.

This study was performed to determine and compare the precision of single and bilateral hip bone mineral density (BMD) measurements and to determine the precision of spinal and total body measurements by dual-energy X-ray absorptiometry (DXA). Precision (group root-mean-square average coefficient of variation) was determined in 6 subjects scanned six times each at the spine, both hips, and total body, with repositioning after each scan. Mean percentage coefficients of variance (%CVs) in BMD for single and bilateral hip scans were, respectively: 0.65% and 0.67% for the total hip, 1.16% and 1.03% for the trochanter, and 1.66% and 1.31% for the femoral neck, respectively. Mean %CV was 1.04% for spine BMD (L2-L4), 0.67% for total body BMD, 1.12% for total body bone mineral content (BMC), 0.94% for total body fat tissue, and 0.77% for total body nonfat soft tissue. We conclude that precision overall is excellent and that femoral neck precision can be improved with bilateral compared with the traditional single hip scans.

Objective: We examined the effects of simvastatin-niacin and antioxidant vitamins on changes in high-density lipoprotein (HDL) subpopulations and alterations in coronary artery stenosis, as assessed by angiography., Methods and Results: Lipids, lipoproteins, and HDL particles were measured on and off treatment in 123 subjects of the HDL-Atherosclerosis Treatment Study. Patients were assigned to 4 treatment groups, simvastatin-niacin, simvastatin-niacin-antioxidant vitamins, antioxidant vitamins, and placebo. Subjects were followed for 3 years on treatment and then for 2 months off treatment. Simvastatin-niacin significantly increased the 2 large apoA-I-containing HDL subpopulations, alpha1 and prealpha1, and significantly decreased the 2 smallest particles, prebeta1 and alpha3, compared with values obtained from the same patients off treatment. Adding antioxidant vitamins to the lipid-modifying agents blunted these effects (not significant). A significant negative correlation (r=-0.235; P<0.01) between the changes in alpha1 HDL particle concentration and coronary artery stenosis was noted. Subjects in the third tertile (157% increase in alpha1) had no progression of stenosis in the 3-year follow-up period, whereas subjects in the first tertile (15% decrease in alpha1) had an average of 2.1% increase in stenosis., Conclusions: Simvastatin-niacin therapy significantly increased the large apoA-I-containing alpha1 HDL particles. This increase was significantly associated with less progression of coronary stenosis even after adjusting for traditional risk factors.

Background: The ability to measure extracellular water (ECW) in critically ill patients can significantly enhance current methods of assessing fluid homeostasis, body composition, and response to nutritional therapy. We measured corrected bromide space to determine change in ECW with wound closure among acutely burned children., Methods: Fifteen children with burns over 30% of their total body surface area had their ECW determined following hemodynamic stabilization and when wound closure was complete. Plasma samples were obtained at baseline and 4 hours after receiving 25 mg/kg of sodium bromide. Plasma bromide was quantified by instrumental neutron activation analysis., Results: Mean CBS decreased with wound closure (9.1 +/- 4.1 vs 7.9 +/- 3.9 liters; P =.04), indicating a significant decrease in ECW over the course of recovery. A decline in weight also occurred over the same period (32.4 +/- 15.2 vs 29.1 +/- 13.5 kg; P =.007); however, change in corrected bromide space as a proportion of weight was not statistically significant., Conclusion: A significant decrease in ECW accompanies the weight loss observed in patients following wound closure. Measurement of bromide dilution space is a convenient method for monitoring ECW that can be done at the bedside.