Total Skeleton Research Articles

Effect of high saturated‐fat diets on bone mass and endochondral ossification in healthy growing rats

High‐fat diets can produce deleterious effects on bone metabolism in growing animals. Objective: To investigate in healthy growing rats the effect of high saturated‐fat diets on bone mass and endochondral ossification. Weaning male Wistar rats (n=20) were fed ad libitum one of the 2 diets, for 4 wks: control (C; fat=7% w/w) (AIN‐93G) or a high‐fat diet containing 20% w/w of beef‐tallow (BT). Then rats were sacrificed. Total skeleton bone mineral density (BMD) and bone mineral content (BMC) were evaluated by DXA (Lunar DPX‐L).The following histomorphometric parameters were evaluated: Bone volume (BV/TV)(%) and cartilage growth plate thickness (CGP.Th).Statistics: Student's t test & Pearson's correlations coefficients were calculated. Results (as mean±SD): BMD(mg/cm2), C=245±13 vs BT=244±13 (p>0.05); BMC(mg), C=1085±319 vs BT=689± 224; (BV/TV)(%), C=45±5 vs BT=38±3 (p<0.03); total GPC.Th(mm), C=0.44±0.04 vs BT=0.43±0.03 (p>0.05); proliferative zone GPC.Th(mm), C=0.21±0.01 vs BT=0.18± 0.01 (p>0.001).The correlation between BMC vs proliferative zone CGP.Th was ‐0.881 (p<0.05).ConclusionHigh saturated‐fat diets lead to a decreased in BMC associated with a significant increased in CGP.Th as well as a reduction in BV/TV. Based on these findings, we suggest that high saturated‐fat diets acts as a dependent risk factor for bone modeling interfering the acquired of bone mass. Awarded by UBACyT O 008 ‐ O015.

Consequences of high‐fat diets on body growth and bone mineral density, in growing rats

Objective: To investigate in growing rats, the effect of high‐fat diets with different n‐6/n‐3 fatty acids ratios, on body growth and parameters of bone densitometry. Weaning male Wistar rats (n=50) were fed ad libitum one of the following diets for 8 wk: control (C; fat=7% w/w) (AIN‐93G) or a high‐fat diet (20% w/w): soybean oil (SO), corn‐oil (CO), linseed oil (LO) or beef‐tallow (BT). Body weights (W) and lengths (L) were recorded every 4 days. W and L gain velocities were calculated (g W/100g W rat and L/10cm L rat, respectively). After 8 wk, rats were sacrificed. Total skeleton bone mineral density (BMD) and bone mineral content (BMC) were evaluated by DXA using a Lunar DPX‐L. Spine BMD was determined. Groups were analyzed as: a) BT vs. SO, CO and LO; b) SO, CO and LO; c) C vs. SO.Results: a) BT achieved the lowest W, total skeleton BMC, BMC/W and spine BMD (P<0.0001); b) No significant differences were observed on anthropometric measurements, total skeleton BMC, BMD, BMC/W or spine BMD, but spine BMD on SO showed a tendency to a diminution (P=0.064); c) Anthropometric measurements, total skeleton BMC and BMD were similar but SO showed reductions of 10% on total BMC/W and spine BMD.Conclusion: The combination of adequate amounts of dietary fat and n‐6/n‐3 fatty acids ratio protects bone health and maintains body growth. Awarded by UBACyT O 003‐4.

Derivation of site-specific skeletal masses within the current ICRP age series

The calculation of absorbed dose to the radiosensitive tissues of the skeleton is routinely performed using reference masses provided in publications from the International Commission on Radiological Protection (ICRP). These values typically include total skeleton tissue masses by reference subject age, but not by individual bone site at a given age. Site-specific variations in absorbed fractions are known to occur for internal alpha-particle and beta-particle emitters, and in certain medical dose reconstructions, site-specific estimates of marrow dose may be desirable. Furthermore, bone-site-specific tissue masses are required to properly estimate skeletal-averaged absorbed fractions and, more importantly, specific absorbed fractions for internalized radionuclides and radiopharmaceuticals. Reference masses by skeletal site are also needed in the development of ICRP compliant tomographic phantoms, as this organ system is initially segmented from medical images only as a homogeneous tissue region. ICRP reference skeletal masses are assigned based upon several independent data sources, many of which may not be entirely consistent with one another. In this study, a methodology is presented, using data from the various ICRP publications, to derive site-specific skeletal tissue masses for each member of the ICRP age series. Active marrow masses are calculated and differences are shown with respect to ICRP Publications 70 and 89 values. New data for a revised surrogate tissue region for the osteoprogenitor cells within bone marrow is presented with estimates of its total mass throughout the skeleton and for different subject ages.

Effects of deflazacort vs. methylprednisone: a randomized study in kidney transplant patients

Metabolic effects of deflazacort vs. methylprednisone were studied in prepubertal patients after kidney transplantation. Thirty-one patients participated: 15 received deflazacort and 16 remained on methylprednisone. The study started at a mean of 2.1 years after transplantation, when patients were randomized to either continue with methylprednisone or switch to deflazacort. Height velocity increased more in the deflazacort than in the methylprednisone group only during the first 2 years: 5.4 +/- 0.5 vs. 3.5 +/- 0.3 cm/year, and 4.2 +/- 0.8 vs. 2.2 +/- 0.4 cm/year p=0.007, [by two-way analysis of variance (ANOVA)]. After 2 and 3 years, the number of patients who were overweight increased in the methylprednisone group and decreased in the deflazacort group; p<0.01. Lean body mass increased more in the deflazacort than in the methylprednisone group (p=0.003). Fat body mass increased only in the methylprednisone group (p<0.01). Total cholesterol and low-density-lipoprotein (LDL) cholesterol increased in the methylprednisone group (p<0.05 and p<0.01, respectively). Total and LDL cholesterol were reduced (p<0.01 and p<0.001, respectively), whereas high-density-lipoprotein (HDL) cholesterol increased (p<0.001) during deflazacort therapy. Lumbar spine bone mineral density (BMD) decreased in both groups, but total skeleton BMD decreased only in the methylprednisone group (p<0.001). Finally, normal glucose/insulin ratio, defined as > 7, was associated (p<0.05) with the deflazacort group. Our data suggest that deflazacort therapy might improve linear growth and lean body mass and prevent excessive bone loss and fat accumulation. It also leads to an improvement in lipoprotein profile without reduction in insulin sensitivity.

In vivo measurements of 210Pb in skull and knee geometries as an indicator of cumulative 222Rn exposure in a underground coal mine in Brazil

Cumulative exposure to radon can be evaluated by measuring 210Pb in bone. The skull and knee are two convenient parts of the skeleton for in vivo measuring 210Pb because these regions of the body present a high concentration of bone, the detectors are easily positioned and the likelihood of cross contribution from other organs or tissues is low. A radiological survey of non-uranium mines in Brazil indicated that an underground coal mine in Paraná, located in the south of Brazil, exhibited a high radon concentration. In vivo measurements of 32 underground coal miners were performed in the IRD-CNEN Whole Body Counter shielded room using an array of four high-resolution germanium detectors. Estimations of 210Pb in the total skeleton were determined from direct in vivo measurements of 210Pb in the head and knees. In vivo measurements of 210Pb in 6 out of 32 underground coal miners ranged from 80 to 164 Bq, suggesting that these workers were significantly exposed to 222Rn.

THE POTENTIAL RISK OF CONSUMING HIGH FAT DIETS ON BONE MINERAL CONTENT

Human aging is associated with an increased incidence of several chronic diseases including osteoporosis. Additionally, it is well documented a strong correlation between bone and lipid metabolisms. Efforts to reduce disabilities are focus on nutrition during growth. We studied the relationship between high fat diets and bone metabolism during growth. 25 male weanling Wistar rats were randomly assigned to one of the following diets for 8 weeks (t=8): control (AIN 93) & 4 experimental groups (soybean, corn, flaxseed and cow). Carbohydrate/ protein/ fat calorie ratio was 66/16/16 and 44/16/40, respectively. Ca % was similar. Body weights (BW) and lengths (BL) and diet intake (Cal/100g/day) were recorded. At t=8, B mineral density (BMD, mg/cm2) and content (BMC, mg) and % B fat (DEXA, Lunar) were determined in the total skeleton while column mineral density was calculated. No significant differences (data was between ranges) in BW (38–41) and BL (1.5–1.9) velocities, diet (23–68) or % B fat (24–36). Results: X ± SD Individuals do growth similarly independent of the diets. Neither increased PUFA appear responsible for BMD or BMC in cortical bone. However, BMD decreased in an active bone tissue being independent of PUFA source. Saturated fat diet accounted for deleterious effect on BMD (cortical and trabecular) and BMC. Body size proportions could mask the potential risk of following certain diets. Awarded by UBACyT 004.

Sex steroids concentrations in relation to bone mineral density in men with coronary atherosclerosis

Background Although suspected, relationships between sex steroids and bone mineral density (BMD) are not fully defined in male population. According to recent data there may also exist an association between low BMD and atherosclerosis. Objective Our aim was to investigate relationships between serum sex steroids and BMD, and between BMD and atherosclerosis in men with coronary artery disease (CAD). Subjects and methods We recruited for the study 55 men aged 40–60 years with angiographically confirmed CAD and 30 healthy, age-matched controls. In each of the examined subjects serum levels of total testosterone (T), estradiol (E 2), estrone and DHEA-S, as well as femoral neck, lumbar spine and total skeleton BMD were measured. Results We found that the prevalence of osteopenia/osteoporosis recognized on spine and/or femoral BMD ( T-score below −1.0) did not differ between men with CAD and healthy controls (respectively 47% versus 47%; p = 0.8 in χ 2 Yates test). The mean BMD value at different regions did not differ between both groups either. Hormonal status of men with CAD and normal BMD was similar to men with CAD and osteopenia/osteoporosis except for the level of testosterone. After adjustment for age and BMI, men with lower BMD had lower testosterone and lower T/E 2 ratio than men with normal BMD (geometric means for testosterone were respectively: 16.1 ± 8.3 versus 16.2 ± 4.2; p < 0.05 in ANCOVA with BMI and age as covariates; for T/E 2 ratio it was: 202.1 ± 94.7 versus 222.8 ± 83.9; p = 0.05). However, we did not find any correlation between sex hormones concentrations and bone mineral density. There was a relationship between the advance of atherosclerosis (ranged by number of stenotic arteries) and BMD: men with the most advanced form of the disease (three-vessels) had the lowest femoral neck BMD. The groups did not differ in lumbar spine BMD. Conclusions Our data suggest that in middle-aged men with CAD: (1) lower serum testosterone and lower T/E 2 ratio are associated with lower BMD; (2) advance of coronary atherosclerosis is inversely related to femoral neck BMD, however this relationship is weak and requires further investigation.

The IL-1 gene family and bone involvement in celiac disease

Celiac disease (CD) is associated with decreased bone mineral mass. Its pathogenesis is multifactorial since both systemic and local mechanisms may play a role. Our objective was to determine whether single-nucleotide polymorphisms in genes encoding members of the interleukin-1 family are associated with bone damage measured by densitometry in a series of 71 adult CD patients assessed at diagnosis. When compared with non-carrier CD patients, carriers of allele T of the interleukin-1beta gene (IL1B-511T) had a significantly lower bone mass at the total skeleton level (p = 0.0484) and a greater prevalence of osteopenia/osteoporosis (p = 0.0102). To our knowledge, this is the first evidence on the association between a genetic predisposition and low bone mass in CD patients. This finding supports the postulated inflammation-associated bone loss pathogenesis as one of the causes of bone weakness in CD.

Exercise Effects on Bone Mineral Density: Relationships to Changes in Fitness and Fatness

Weight loss typically reduces bone mineral density (BMD). Exercise may preserve or increase BMD even while reducing fatness. We examined the relationships among exercise-induced changes in fitness and fatness with BMD. Randomized controlled trial conducted between July 1999 and November 2003. Men and women (n =115) aged 55 to 75 years. Six months of exercise training. Fitness measured as peak oxygen uptake and muscle strength, body composition by anthropometry, dual-energy x-ray absorptiometry, and magnetic resonance imaging. A total of 51 men and 53 women completed the trial. Exercise increased aerobic and strength fitness and lean body mass, and reduced general and abdominal obesity. BMD did not change among men in either group. Among women exercisers, there were reductions in total skeleton BMD (p =0.02) and greater trochanter BMD (p =0.02). By bivariate correlation, among women, increased femoral neck BMD was associated with increased aerobic fitness (p =0.01) and with reduced body weight (p =0.02) and BMI (p =0.02). In the final regression model, 13% of the change in femoral neck BMD was explained by the change in aerobic fitness (p <0.01). Among the men, increased total hip BMD and femoral shaft BMD were associated with increased lean mass and lower-body strength. In the final regression models, the change in lean mass explained 9% of the variance in total hip BMD (p =0.04). The change in lean mass explained 20% of the change in femoral shaft BMD (p <0.01), and the change in lower-body strength explained an additional 6% (p <0.04). When examined by group assignment, 6 months of exercise had no effect on BMD among men, and reduced BMD among women. When examined by change in fitness and fatness, women who had the greatest increases in aerobic capacity and men who had the greatest increases in strength and lean mass were more likely to increase their BMD. Exercise-induced reductions in fatness did not lead to bone loss.

Bone Mineral Density In Male Runners And Climbers

While in running the weight-bearing bones are stressed predominantly by high-impact ground-reaction forces, in climbing bones of the total skeleton are stressed by vigorous muscle contractions. Purpose To determine the influence of two disciplines of sport which are characterised by different loading patterns and a different anatomical distribution of the loads on bone mineral density (BMD) of male athletes. Methods We compared the BMD of age-, weight-, and height matched competitive male runners, competitive climbers, and controls. Total body (TB) and regional (upper extremity, lower extremity) BMD were measured by dual-energy X-ray absorptiometry (DXA). Quantitative computed tomographic (QCT) scans were made from the femoral neck (FN) and the lumbar spine (LS). Quantitative ultrasound (QUS) measurements were performed at the calcaneus. ResultsTableRunners and climbers had about the same TB BMD value which was significantly higher than in the control group. The regional analysis showed significant differences between runners and climbers in favour to the mechanically loaded sites. At the FN the runners had a significantly higher trabecular BMD than the climbers and the controls, while the climbers had a significantly higher cortical BMD than the runners and the controls. At the LS the runners and the climbers had similar values for trabecular BMD, which differed significantly from the controls. As expected, runners had the highest QUI value at the calcaneus. Conclusion The results indicate that both, sports producing impact loading as well as sports producing forces by vigorous muscle contraction have beneficial effects on BMD. The bone adaptation is site specific. The inhomogeneous results at the FN (QCT) might be due to the different loading pattern. We suggest that bones that are loaded by compression due to ground reaction forces preliminary adapt by increasing the trabecular BMD while bones loaded by bending resulting from muscle contraction, adapt by increasing the cortical BMD.

Bone metabolism of male rats chronically exposed to cadmium

Recently, based on a female rat model of human exposure, we have reported that low-level chronic exposure to cadmium (Cd) has an injurious effect on the skeleton. The purpose of the current study was to investigate whether the exposure may also affect bone metabolism in a male rat model and to estimate the gender-related differences in the bone effect of Cd. Young male Wistar rats received drinking water containing 0, 1, 5, or 50 mg Cd/l for 12 months. The bone effect of Cd was evaluated using bone densitometry and biochemical markers of bone turnover. Renal handling of calcium (Ca) and phosphate, and serum concentrations of vitamin D metabolites, calcitonin, and parathormone were estimated as well. At treatment with 1 mg Cd/l, corresponding to the low environmental exposure in non-Cd-polluted areas, the bone mineral content (BMC) and density (BMD) at the femur and lumbar spine (L1–L5) and the total skeleton BMD did not differ compared to control. However, from the 6th month of the exposure, the Z score BMD indicated osteopenia in some animals and after 12 months the bone resorption very clearly tended to an increase. The rats' exposure corresponding to human moderate (5 mg Cd/l) and especially relatively high (50 mg Cd/l) exposure dose- and duration-dependently disturbed the processes of bone turnover and bone mass accumulation leading to formation of less dense than normal bone tissue. The effects were accompanied by changes in the serum concentration of calciotropic hormones and disorders in Ca and phosphate metabolism. It can be concluded that low environmental exposure to Cd may be only a subtle risk factor for skeletal demineralization in men. The results together with our previous findings based on an analogous model using female rats give clear evidence that males are less vulnerable to the bone effects of Cd compared to females.

Low-level lifetime exposure to cadmium decreases skeletal mineralization and enhances bone loss in aged rats

The effects of low-level lifetime exposure to cadmium (Cd) on the skeleton mineral status and the risk of bone loss in the elderly were studied in an experimental model of human environmental exposure in non-Cd-polluted areas. Young female Wistar rats were exposed to 1 mg Cd/l in drinking water for 24 months. Bone mineral content (BMC), density (BMD) and area of the lumbar spine (L1–L5) and femur, and total skeleton BMD (T-BMD) were measured densitometrically at the baseline and after 6, 12, 18, and 24 months. Prevalence of osteopenia and osteoporosis was evaluated based on the BMD T score and Z score. Osteocalcin (OC) in the serum and total alkaline phosphatase (total ALP) in the serum, cortical and trabecular bone samples as bone formation markers, and C-terminal cross-linking telopeptide of type I collagen (CTX) in the serum and urine as bone resorption markers were measured. Calcium (Ca) and Cd concentrations in the serum/blood and urine were determined as well. In the Cd-exposed females, the L1–L5 and femur BMC and BMD at all the studied time points were lower compared to control. The exposure to Cd resulted in lower accumulation of peak bone mass, accelerated osteopenia, and enhanced the prevalence of osteoporosis in aged rats. The effect of Cd was more pronounced at the L1–L5 than at the femur. CTX concentration in the urine was decreased after 6 months and next increased compared to control, whereas the urinary loss of Ca was enhanced during the exposure to Cd. After 24 months of the treatment, the serum total ALP activity and the activity of this enzyme in cortical and trabecular bone decreased and serum CTX concentration increased, whereas the concentrations of OC and Ca were unchanged. The study clearly revealed that low-level lifetime exposure to Cd diminishes the accumulation of bone mass during skeletal growth and influences bone metabolism at maturity causing osteopenia, and enhances the age-related bone loss due to high turnover rate leading in consequence to osteoporosis in aged rats. The results together with our previous findings confirm the hypothesis that environmental exposure to Cd may be a risk factor for skeletal diseases.

Low levels of endogenous estradiol protect bone mineral density in young postmenopausal women

Objective Low levels of endogenous estrogens may play a role in the protection of bone mineral density (BMD) in healthy postmenopausal women. The aim of this study was to evaluate the effect of endogenous estradiol and testosterone on bone mass in young and older healthy postmenopausal women.Methods The study involved 99 postmenopausal women aged 55–75 years. The BMDs of the lumbar spine, proximal femur and total skeleton were determined. Measurements were taken of serum calcium, bone alkaline phosphatase, Crosslaps, estradiol, estrone, sex hormone binding globulin, testosterone, bioavailable testosterone and urine calcium. Estradiol was measured using a sensitive assay with a lower detection limit at 5 pg/ml.Results A multivariate analysis showed that the BMD of the lumbar spine was significantly predicted by estradiol (p < 0.05), and testosterone (p < 0.0001). Likewise, testosterone was found to be an independent predictor of the BMD of the total femur (p < 0.001) and the total skeleton (p < 0.001). The population was divided into two groups: ⩽ 65 (Group 1) and > 65 years (Group 2) of age and also stratified according to estradiol levels: > 10 and ⩽ 10 pg/ml. Significant differences in BMD were found in women in Group 1 in whom estradiol levels higher than 10 pg/ml were associated with a higher BMD of the lumbar spine ( + 14%, p < 0.01), proximal femur ( + 6%, p < 0.05) and total skeleton ( + 7%, p < 0.05) compared with women with estradiol levels below 10 pg/ml. Bone alkaline phosphatase levels (p < 0.05) and serum Crosslaps (not significant) were lower in women in Group 1 with a level of estradiol more than 10 pg/ml.Conclusion Endogenous estradiol levels higher than 10 pg/ml and testosterone protected bone mass in healthy postmenopausal women under 65 years of age. These results were not observed in the group of older women.

Ultrasound parameters and markers of bone turnover in hyperthyroidism: a longitudinal study.

Hyperthyroid patients are characterized by accelerated bone turnover leading to bone mass loss. The aim of this study was to assess changes in quantitative ultrasound [QUS] parameters, bone mineral density (BMD), and biochemical markers of bone turnover in patients prior to and after the onset of hyperthyroid treatment. A 2-yr longitudinal study was performed on 10 women recently diagnosed with Grave's disease after starting antithyroid therapy. Six patients were postmenopausal. All patients showed evidence of thyrotoxicosis as indicated by suppressed serum TSH and high levels of total serum thyroxine. They received antithyroid therapy (methimazole and/or 131I radiodine). QUS parameters were measured using an Achilles ultrasound unit and BMD was assessed by dual-energy X-ray absorptiometry (DXA). Thyroid hormones and markers of bone turnover were determined at baseline and 6, 12, and 24 mo after the onset of treatment.Stiffness, broadband ultrasound attenuation (BUA), and speed of sound (SOS) were low at baseline compared to normal values for the same age range and increased after 2 yr of treatment. A significant increase in BMD of the lumbar spine, total skeleton, and skeletal regions (legs) was also observed after treatment. Recovery of stiffness was almost complete at 12 mo. No significant elevation was observed between 12 and 24 mo. Stiffness increased 7.6%, 10.4%, and 10.4% after 6 mo (p < 0.02), after 1 yr (p < 0.02), and after 2 yr, respectively. No significant increase in SOS and BUA was observed between 12 and 24 mo. Furthermore, recovery of total skeleton and lumbar spine BMD continued throughout the study. Successful antithyroid therapy produced a rapid increase in QUS parameters (Stiffness) and spine BMD and femoral neck during the first year of treatment and a slower increment in total skeleton (up to 24 mo). Overall, ad integrum restitution was not observed in QUS or BMD.

Effects of body weight and sex on carcass tissue distribution in goats

Distribution of fat, muscle and bone tissues was studied in bucks, wethers and doe Jebel Akhdar (JA) Omani goats raised under intensive management and slaughtered at 11, 18 or 28 kg body weight (BW). Weight of individual tissues was expressed as percentage of total respective tissue weight in the half carcass. Weight of total body fat in the empty body weight (EBW) ranged between 7.6% in bucks at 11 kg BW and 23.5% in does at 28 kg BW. At 18 kg BW, JA goats had higher TBF, carcass and non-carcass fat than those slaughtered at 12 kg BW ( P<0.001). Does and wethers had a faster rate of deposition of carcass and non-carcass fat relative to EBW. Therefore, they had higher fat content ( P<0.001) than bucks at 28 kg BW. The highest proportion of fat in the body was deposited intermusculary whereas the omentum constituted the highest non-carcass fat proportion. About 55% of the musculature in JA goat carcasses was found in muscle groups of the proximal hind leg, around the vertebral column and in the proximal forelimb (expensive muscle groups). Bucks had higher proportions of musculature in the forequarter ( P<0.001) and intrinsic muscles of the neck but lower proportions of muscles at the proximal hind limb ( P<0.001) than does and wethers. About 51% of the total skeleton was found in the axial skeleton, 22–23% in the forelimb and 22–23% in the hind limb of JA goats. There were few sex or slaughter weight effects on proportions of bone weight in the skeleton. In general, slaughter weight and sex effects on tissue distribution were more pronounced in the fat tissue. The magnitude of these effects on muscle and bone tissues was small and is unlikely to have economic impact on meat production from goats.

Estrogen receptor beta dinucleotide (CA) repeat polymorphism is significantly associated with bone mineral density in postmenopausal women.

Significant associations between the lengths of a highly polymorphic dinucleotide (CA) repeat located within the human estrogen receptor beta (ESR2) gene on chromosome 14, bone mineral density (BMD) and androgen levels have been reported previously in premenopausal women. We measured the size of this microsatellite repeat in 226 healthy women (60-98 years). After adjustment for age, body mass index, hormone replacement status, and other variables known to influence BMD, women with < 25 CA repeats had significantly higher BMD measured in the total skeleton, lumbar spine, and femoral neck when compared with women having longer alleles. Women with shorter alleles also had higher circulating estrone and estradiol levels that approached statistical significance as compared with women harboring longer alleles after appropriate adjustments were performed in linear regression models. Women having both short and long CA repeats had BMD values in all regions of the skeleton that were midway between those found in women homozygous for longer or shorter repeat sizes. Because the ESR2 CA repeat size was neither associated with change in BMD nor serum levels of biochemical markers of bone turnover, it is likely that ESR2 CA repeat genotype is significantly linked to the attainment of peak bone mass in women.

Bone Mass Changes In Vivo During the Entire Reproductive Cycle in Rats Feeding Different Dietary Calcium and Calcium/Phosphorus Ratio Content

The purpose of this study was to quantify in vivo the impact of different dietary Ca contents on the maternal total skeleton and skeletal sub-areas in adult rats during pregnancy and lactation, using DXA. Twenty-four female Wistar rats (approximately 5 months old) were mated and divided into three groups (n = 8) and fed one of the following diets, varying only in Ca content (LCD: 0.14%, NCD: 0.6% or HCD: 1.2%). Pups were adjusted to 8-9 per dam. Maternal ionic calcium and in vivo bone mineral density (BMD) were measured at the beginning, after delivery and after weaning. Regardless of the diet, ionized calcium decreased from onset to weaning ( P < 0.05). At weaning, bone mass decreased 7.3% in NCD, 15% in LCD and 10.5% in HCD from initial values. Total skeleton, whole and proximal tibia and spine BMDs only decreased at delivery in the LCD group ( P < 0.05) but, irrespective of the diet, at weaning, they were lower compared to delivery and initial values ( P < 0.05). LCD group presented the lowest BMD in the proximal tibia and spine regions ( P < 0.05). At birth, pups did not present differences, however, at weaning, LCD pups reached the lowest body weight ( P < 0.05), NCD presented the highest body Ca content ( P < 0.05) and there were no differences between LCD and HCD. This in vivo study showed that regardless of the dietary calcium content, the maternal skeleton is slightly affected by pregnancy but severely affected by lactation. However, the degree of such response appears to depend not only on dietary Ca content but also on dietary Ca/P molar ratio.

Effect of intravenous pamidronate on bone markers and local bone mineral density in fibrous dysplasia

Bisphosphonates have proven to be effective in patients with fibrous dysplasia of the bone (FD) as shown by their effect on bone pain, markers of bone turnover, or radiological changes. The aim of this study was to evaluate the usefulness of measuring bone mineral density (BMD) of affected bones to assess the efficacy of bisphosphonate treatment. Seven patients (mean age 26 years) received courses of 180 mg intravenous infusion of pamidronate every 6 months (60 mg/day during 3 days). Clinical symptoms, serum alkaline phosphatase, and urinary C-terminal cross-linking telopeptide of type I collagen were assessed every 3 months. BMD of total skeleton and X-rays of FD areas (FDa) were performed at baseline and at 12 months. BMD of FDa was compared with the contralateral side (CL) using the region of interest program on the total skeleton scan. BMD of total skeleton was normal at baseline. Average BMD of FDa was −11.4% compared with CL, a significantly greater difference than that observed between the left and right sides in healthy controls, −0.7% (P < 0.02). At 12 months bone pain diminished in all patients. Bone turnover markers decreased. Mean total skeleton BMD increased 3.3% (P < 0.02). Subregions of the total skeleton scan presenting FD lesions augmented: arms +9.6% (P < 0.02), legs +4.2%, and pelvis +3.5% (P < 0.05). The increase in mean BMD of FDa was +6.8% compared with +2.6% in CL. No changes were observed on the X-ray. These results indicate that simultaneous determination of markers of bone turnover and BMD of FDa is useful in short-term follow-up to determine the efficacy of intravenous pamidronate.

The Impact of congenital, severe, untreated growth hormone (GH) deficiency on bone size and density in young adults: insights from genetic GH-releasing hormone receptor deficiency.

GH and IGF-I have well recognized effects on bone elongation during development, but their importance for bone mineralization and structure during the growth phase are less well understood. Because children with GH deficiency are generally treated with GH, little detailed information exists in humans about the effects of long-term GH deficiency on bone development. The recently described syndrome of genetic GHRH receptor deficiency in Pakistan (dwarfism of Sindh) affords a unique opportunity to examine the question of GH deficiency on bone development because the affected patients have congenital, severe, isolated GH deficiency, which had never been treated because of societal reasons. We performed dual energy x-ray absorptiometry scans in four adult males (age, 23-30 yr) to address the question of bone mineralization. Areal bone mineral density (BMD) was low (mean Z scores: -3.3, -2.1, -3.7, and -1.7) in the lumbar spine, femoral neck, forearm, and total skeleton, respectively. This low areal BMD is in part caused by the small bone size in these dwarfed patients. When corrected for size, volumetric BMD (bone mineral apparent density) was normal to near normal (mean Z scores: -1.2, +0.8, and +0.8 for lumbar spine, femoral neck and total skeleton, respectively). We conclude that GH/IGF-I deficiency has relatively little impact on bone mineralization during the bone accretion phase. This is in marked contrast to their effect on bone elongation and overall bone size.

Clinical applications of body composition measurements using DXA.

Dual-energy X-ray absorptiometry (DXA) scanning was primarily developed for the diagnosis of osteoporosis and was initially applied to studies of the clinically important sites of the lumbar spine, femoral neck, and forearm. The rapid adoption of DXA has led to the development of different, competing generations of equipment. Improvements have been achieved through advances in X-ray generation and detection technology, modification of data acquisition protocols, and implementation of more sophisticated image analysis algorithms. As a result, DXA has been extended to allow the study of the total skeleton and its regional parts, as well as soft-tissue composition measurement. The three major components of the body: fat mass, lean mass, and bone mineral mass, can now be easily measured using a single whole body DXA scan with high precision and low scanning time. The comprehensive view of body composition provided by DXA makes it an attractive technique for a variety of clinical applications such as the prevention of cardiovascular and metabolic diseases, clinical management of different chronic diseases, and monitoring of the impact of treatment regimens on body tissues. In this article we review the contribution DXA has made to the understanding of body composition in clinical studies in adults.