Aerobic Endurance Training Does Not Protect Bone Against Poorly Controlled Type 1 Diabetes in Young Adult Rats.

Streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) decreases trabecular bone volume and bone strength in rodents. The current study investigated the potential protective effects of aerobic endurance training (AET) on bone in STZ-induced T1DM young adult rats. Sixty-four 8-week-old male Sprague-Dawley rats were randomly divided into 4 groups of 16: control non-T1DM sedentary (CS) and exercised (CX), T1DM sedentary (DS) and exercised (DX). Blood glucose was maintained at 9-15 mmol/L using subcutaneously implanted insulin pellets (Linplant, Linshin Canada, Inc.). AET was performed at ~75-85% VO2max for 1 h/day, 5 day/week for 10 weeks. Areal and volumetric bone mineral density (aBMD and vBMD; excised femur) were measured using dual-energy X-ray absorptiometry (DXA; QDR 4500A) and micro computed tomography (µCT; Aloka). Bone strength was tested using a 3-point bending test (Instron 5544 Load Frame). Two-way ANOVA was used to test for T1DM and exercise differences followed by Tukey's HSD tests for interaction effects; significance was set at P < 0.05. T1DM had lower body weight (18.0%), aBMD (8.6%), cortical vBMD (1.6%), trabecular vBMD (2.1%), maximum load at break (22.2%), and increased elastic modulus (11.3%) vs. control (P < 0.001). Exercise in T1DM further decreased body weight (4.7%) vs. sedentary (P = 0.043) and maximum extension during the bending test that demonstrated DX was increased (7.3%) vs. CX (P = 0.033). There were no other beneficial effects of exercise on bone. These results suggest that 10 weeks of AET in rats do not have protective effects on bone in the short term and that T1DM rats have compromised bone health.

Estimating the mineral density of trabecular bone using Compton scattering.

This study proposes a technique based on Compton scattering to estimate trabecular bone mineral density (TBMD), which is important for understanding bone strength, and hence, is pivotal for estimating the condition of the bone. Bone phantoms (a mixture of paraffin wax and bone powder) with various concentrations of bone ash were prepared to simulate the trabecular bone. These samples were exposed to primary gamma photon flux from a137Cs (222 GBq) radioisotope source one after the other, and the scattered photon flux was detected using an NaI(Tl) detector. The presence of the cortical bone (using aluminum sheets) and fat (tertiary butyl alcohol) around the trabecular bone was also studied to determine whether the TBMD measurements had been affected. The correlation between bone ash contents and the intensity of Compton scattering was high with a coefficient of 0.97. The outcomes suggest that TBMD is independent of the presence of the cortical bone and overlying fat, with a statistical uncertainty of ±0.3% in the count rate. The intensity of Compton scattering increased by only 1.5% when the thickness of the aluminum sheet (simulating the cortical bone) becomes was increased by four times, and by less than 5% when the bone phantom was surrounded by tertiary butyl alcohol.

Data on body mass, glucose tolerance and bone phenotype of mice with osteogenesis imperfecta on long-term low-fat and high-fat diets.

Male and female mice with a dominant severe bone fragility disorder, osteogenesis imperfecta, and their wild-type littermates (FVB background) were challenged with a long-term (26 weeks) high-fat diet to evaluate the development of obesity and glucose intolerance. Here we present data for the measurements of body mass, the outcome of glucose tolerance tests during the long-term diet, as well as organ weights and bone phenotype at the end of the study. Interpretation of the data and further in-depth analysis can be found in the article "Male but not female mice with severe osteogenesis imperfecta are partially protected from high-fat diet-induced obesity." by Tauer JT, Boraschi-Diaz I, Al Rifai O, Rauch F, Ferron M, Komarova SV, published in Molecular Genetics and Metabolism. The data presented here demonstrate individual mouse outcomes of long-term diet experiments that can be reused for comparative studies of diet-induced changes in wild-type mice on different backgrounds and different mouse models of osteogenesis imperfecta.

Use of proton pump inhibitors is associated with lower trabecular bone density in older individuals.

Proton pump inhibitors (PPIs) are highly effective in the treatment of upper gastrointestinal acid-related conditions and are fast becoming one of the most frequently prescribed treatments in adult or older persons. Recent data show that long-term use of PPIs in older subjects is associated with important undesirable effects, including a higher risk of osteoporotic fractures. The mechanisms of this association are unclear and the relationship between the use of PPIs and parameters of bone mass and geometry has never been fully explored. This study investigates the relationship between the chronic use of PPIs and the parameters of bone mass (cortical and trabecular bone mineral density - vBMDc and vBMDt) and bone geometry (cortical and trabecular cross sectional area - tCSA and cCSA) in older individuals. The study population consisted of 1038 subjects (452 men and 586 women) 65years or older, selected from the InCHIANTI study, with complete information on computerized tomography performed at tibial level (pQCT) and on medications. Participants were classified as PPI users and nonusers based on self-report of PPI use over the last 15days, with PPI users (36 subjects, 14 men and 22 women) making up 3.4% of the study population (mean age 75.7±7.4years). The relationship between use of PPIs and pQCT bone parameters was tested by multivariate linear regression analysis adjusted for age, sex and several clinical factors and/or statistically confounding variables identified by partial correlation coefficient and Spearman partial rank order correlation coefficients, as appropriate (age, sex, BMI, caloric intake, IGF-1, IL-6, calcium, estradiol, bioavailable testosterone, vitamin D, parathyroid hormone, cross-sectional muscle area, and level of physical activity). PPI users showed age- and sex-adjusted lower vBMDt than nonusers (180.5±54.8 vs. 207.9±59.4, p=0.001). The inverse association between PPI use and vBMDt remained almost unchanged after adjustment for multiple confounders. There was no statistically significant difference in vBMDc, tCSA and cCSA between PPI users and nonusers. In community dwelling older persons, the use of PPIs is inversely associated with vBMDt, an early marker of the osteoporotic process. These findings suggest that PPI use might increase the risk of fractures in older subjects through its detrimental effects on trabecular bone.