BMC) And Density Research Articles

Densidade mineral óssea de crianças e adolescentes com hipotireoidismo congênito

A cross sectional study was made on 60 patients (9.9 +/- 1.8 yr-old) with congenital hypothyroidism (CH) (group A): 40 girls (23 prepubertal) and 20 boys (18 prepubertal). Control group (group B) was constituted of 28 healthy children (10.4 +/- 2.1 yr-old): 18 girls (8 prepubertal) and 10 boys (9 prepubertal). To evaluate bone mineral density (BMD) and content (BMC) and to correlate them with chronological and bone age (BA), sex, sexual maturation, l-T4 dose, TSH, TT4, FT4, and CH etiology. BA, total body BMD, and BMC (DXA) were obtained of both groups. TSH, TT4, and FT4 were measured in patients only. BMD was lower in group A (0.795 +/- 0.075 g/cm(2) vs. 0.832 +/- 0.092; p = 0.04) and higher in pubertal than in prepubertal girls (p = 0.004). There was no significant difference between BMD and BMC related to sex and CH etiology. Our data demonstrated that BMD was significantly lower in children with CH, different from what has been published in the literature.

The Effect of Oral Contraceptives on Bone Mass and Stress Fractures in Female Runners

To determine the effect of oral contraceptives (OC) on bone mass and stress fracture incidence in young female distance runners. One hundred fifty competitive female runners ages 18-26 yr were randomly assigned to OC (30 microg of ethinyl estradiol and 0.3 mg of norgestrel) or control (no intervention) for 2 yr. Bone mineral density (BMD) and content (BMC) were measured yearly by dual x-ray absorptiometry. Stress fractures were confirmed by x-ray, magnetic resonance imaging, or bone scan. Randomization to OC was unrelated to changes in BMD or BMC in oligo/amenorrheic (N=50) or eumenorrheic runners (N=100). However, treatment-received analyses (which considered actual OC use) showed that oligo/amenorrheic runners who used OC gained about 1% per year in spine BMD (P<0.005) and whole-body BMC (P<0.005), amounts similar to those for runners who regained periods spontaneously and significantly greater than those for runners who remained oligo/amenorrheic (P<0.05). Dietary calcium intake and weight gain independently predicted bone mass gains in oligo/amenorrheic runners. Randomization to OC was not significantly related to stress fracture incidence, but the direction of the effect was protective in both menstrual groups (hazard ratio [95% CI]: 0.57 [0.18, 1.83]), and the effect became stronger in treatment-received analyses. The trial's statistical power was reduced by higher-than-anticipated noncompliance. OC may reduce the risk for stress fractures in female runners, but our data are inconclusive. Oligo/amenorrheic athletes with low bone mass should be advised to increase dietary calcium and take steps to resume normal menses, including weight gain; they may benefit from OC, but the evidence is inconclusive.

Impact of maternal veiling during pregnancy and socioeconomic status on offspring’s musculoskeletal health

The impact of maternal veiling during pregnancy and of socioeconomic status on offspring's bone mass was investigated in 326 healthy adolescents. Veiling during pregnancy was associated with decreased musculoskeletal parameters in the offspring boys, but not girls. SES was a significant predictor of bone mass in both genders. This study investigates the effects of maternal veiling during pregnancy, a surrogate for low vitamin D level, and socioeconomic status (SES), a surrogate of nutritional status, on their offspring's bone mass at adolescence. Three hundred and twenty-six healthy adolescents aged 13.1(2.0) years and their mothers were studied. The impact of maternal veiling on offspring's bone mass was evaluated through regression analyses. Outcome variables were bone mineral density (BMD) and content (BMC) at the spine, hip, and total body of the children. Predictors were maternal veiling during pregnancy and SES. Covariates were height, body composition, Tanner staging, calcium intake, vitamin D and exercise in children. In boys, adjusted analyses revealed that both maternal veiling during pregnancy and SES were significant predictors of bone mass, at multiple skeletal sites. In girls, SES but not maternal veiling during pregnancy was a significant predictor of bone mass at multiple sites. Maternal veiling during pregnancy was associated with decreased musculoskeletal parameters of boys, but not girls. SES was a significant predictor of bone mass in both genders. These findings may have profound implications on children's bone health.

Levetiracetam, Phenytoin, and Valproate Act Differently on Rat Bone Mass, Structure, and Metabolism

Long-term treatment with antiepileptic drugs (AEDs) is associated with increased risk of fractures. Phenytoin (PHT) and valproate (VPA) have both been suggested to influence bone health, whereas levetiracetam (LEV) is scarcely studied. The present study compares the effect of these AEDs on bone mass, biomechanical strength, and bone turnover in rats. Female rats received PHT (50 mg/kg), VPA (300 mg/kg), or LEV (50 and 150 mg/kg) for 90 days. Dissected femurs were analyzed using dual energy x-ray absorptiometry (DXA), three-point cantilever bending, and histomorphological evaluation. Serum levels of biochemical bone turnover markers were monitored using immunoassay quantification. PHT and VPA reduced bone mineral density (BMD) and content (BMC) in one or more bone compartments, whereas LEV did not. VPA induced increased bone turnover, whereas modest changes were observed for PHT. Interestingly, low-dose LEV was associated with reduced biomechanical strength of the femoral neck (mainly trabecular bone). In addition, low-dose LEV treatment resulted in significantly reduced levels of serum osteocalcin, a marker of bone formation. Histomorphological analyses indicated increased retention of cartilage remnants at the growth plate metaphysis of rats treated with low-dose LEV vs. controls. PHT, VPA, and LEV exert differential effects on bone mass and strength, suggesting different mechanisms of action. The weakening effect of low-dose LEV on the femoral neck, despite a constant BMD, suggests a primary effect on bone quality. These findings warrant further human studies of possible adverse effects of LEV on bone development and growth, particularly in children and adolescents.

Effect of zinc supplementation on bone metabolism in male rats chronically exposed to cadmium

The aim of the present study is to investigate, based on the rat model of moderate and relatively high human exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced disorders in bone metabolism. For this purpose, male Wistar rats received Cd (5 and 50mg/l) or/and Zn (30 and 60mg/l) in drinking water for 6 and 12 months. Bone densitometry and biochemical markers of bone turnover were used to assess the effects of Cd or/and Zn. Bone mineral content (BMC) and density (BMD) were measured in the femur. Serum osteocalcin (OC) and alkaline phosphatase in trabecular (bT-ALP) and cortical (bC-ALP) bone were determined as bone formation markers, and carboxy-terminal cross-linking telopeptides of type I collagen (CTX) in serum were measured as bone resorption marker. Serum concentration of calcium (Ca) and its renal handling, as well as Zn and Cd concentrations in the serum/blood, urine and femur were evaluated as well. The exposure to 5 and 50mg Cd/l (0.340±0.026 and 2.498±0.093mg Cd/kg body wt/24h, respectively), in a dose and duration dependent manner, affected bone turnover (inhibited bone formation and stimulated its resorption) and disturbed bone mineralization (decreased BMC, BMD and Zn concentration). Zn supply at the concentration of 30 and 60mg/l (1.904±0.123 and 3.699±0.213mg/kg body wt/24h, respectively) during Cd exposure influenced the Cd-induced disorders in bone metabolism. Zn administration to the Cd-exposed rats enhanced the bone ALP activity and prevented Cd-induced bone resorption, but had no statistically significant effect on BMC and BMD; however, mean values of the densitometric parameters in the rats receiving both Cd and Zn were higher than in those treated with Cd alone. Moreover, Zn supplementation at both levels of Cd exposure was found to prevent Cd accumulation in the femur and the Cd-induced decrease in bone Zn concentration. The results of the present study allow the conclusion that Zn supplementation during Cd exposure may partly protect from disorders in bone metabolism. The influence of Zn may be accompanied by its ability to prevent Cd-induced Zn deficiency and to decrease Cd accumulation in bone tissue. The findings seem to indicate that enhanced dietary intake of Zn in subjects chronically exposed to moderate and relatively high Cd levels may have a protective influence on the skeleton.

Creatine Monohydrate Increases Bone Mineral Density in Young Sprague-Dawley Rats

Creatine kinase, found in osteoblasts, is an enzyme that is upregulated in response to interventions that enhance bone mass accretion. Creatine monohydrate supplementation can increase fat-free mass in young healthy men and women and can reduce markers of bone breakdown in boys with Duchenne muscular dystrophy. The objective of this study was to determine the influence of supplementation with creatine monohydrate on bone structure and function in growing rats, to establish a therapeutic model. Creatine monohydrate (2% w.w.) (CR; N = 16) or standard rat chow (CON; N = 16) was fed to Sprague-Dawley rats beginning at 5 wk of age, for 8 wk. Bone mineral density (BMD) and content (BMC) were assessed using dual-energy x-ray absorptiometry at the beginning and end of the protocol. The rats were sacrificed, and one femur was removed for the determination of mechanical properties. The CR-treated rats showed greater lumbar BMD and femoral bending load at failure compared with the CON rats (P < 0.05). Together, these data suggest that creatine monohydrate potentially has a beneficial influence on bone function and structure; further investigation is warranted into its effect on bone functional properties and its effects in disorders associated with bone loss.

Bone mineral density in institutionalised patients with refractory epilepsy

Bone mineral density (BMD) and content (BMC) were measured in 208 institutionalised patients with refractory epilepsy. BMD was in the osteoporotic range in 43% of males and 21% of females. BMC was reduced only in male patients. Apart from age and gender, no other factor or specific AED was particularly associated with reduced BMD or BMC. This study indicates the magnitude of the problem of bone disease in refractory epilepsy, in particular affecting young and male patients with chronic epilepsy.

The Bone Mineral Density in Childhood Study: Bone Mineral Content and Density According to Age, Sex, and Race

Low bone mass may increase risk of fracture. Several chronic medical conditions, medications, and lifestyle factors affect bone mineral accrual. Appropriate reference values are essential for identification of children with bone deficits. Our objective was to establish reference curves for bone mineral content (BMC) and density (BMD) in children. The Bone Mineral Density in Childhood Study is an ongoing longitudinal study in which measurements are obtained annually at five clinical centers in the United States. Participants included 1554 healthy children (761 male, 793 female), ages 6-16 yr, of all ethnicities. Scans of the whole body, lumbar spine, hip, and forearm were obtained using dual-energy x-ray absorptiometry. Percentile curves based on three annual measurements were generated using the LMS statistical procedure. BMC of the whole body and lumbar spine and BMD of the whole body, lumbar spine, total hip, femoral neck, and forearm are given for specific percentiles by sex, age, and race (Black vs. non-Black). BMC and BMD were higher for Blacks at all skeletal sites (P < 0.0001). BMC and BMD increased with age, and a plateau was not evident by age 16 (girls) or age 17 (boys). The variation in BMC and BMD also increased with age. Age-, race-, and sex-specific reference curves can be used to help identify children with bone deficits and for monitoring changes in bone in response to chronic diseases or therapies.

Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women

Women participated in 5 months of unilateral concentric (n = 37) or eccentric (n = 33) isokinetic resistance training of the legs and arms. Limb muscular strength increased as did total body, leg, and arm fat-free soft tissue mass, total body BMC, hip BMD, and forearm BMC and BMD. Isokinetic training benefits bone mineral acquisition. Isokinetic resistance training (IRT) is osteogenic; however, it is not known if concentric or eccentric modalities of IRT produce differential effects on bone. We tested our hypothesis that high-load eccentric versus concentric mode of IRT would produce greater increases in muscular strength, fat-free soft tissue mass (FFSTM), bone mineral density (BMD) and content (BMC) in trained legs and arms. Participants were randomized to 5 months of concentric (n = 37) or eccentric (n = 33) training. The non-dominant leg and arm were used during training; dominant limbs served as controls. Muscular strength was measured with an isokinetic dynamometer; body composition was measured by dual-energy X-ray absorptiometry. Muscular strength of the concentrically and eccentrically trained leg (18.6%; 28.9%) and arm (12.5%; 24.6%) significantly increased with training. Gains in total body (TB) BMC (p < 0.05) and, in the trained limbs, total proximal femur BMD (p < 0.05) and total forearm BMD (p < 0.05) and BMC (p < 0.05) occurred in both groups. FFSTM increased for the TB and trained leg and arm (all p < 0.001) in both modes. Regardless of the mode, high-intensity, slow-velocity IRT increases muscular strength and FFSTM of trained limbs and imparts benefits to TB BMC and site-specific BMD and BMC in young women.

Physical Activity, Calcium Intake and Bone Health in Children and Adolescents

Osteoporosis is a serious and potentially debilitating disease, which can lead to a variety of health complications and a diminished quality of life. Consequently, the development of bone mineral density (BMD) and content (BMC) during childhood and adolescence is of great importance, as it may attenuate the effects and incidence of osteoporosis later in life. Identifying the mechanisms by which bones are strengthened early in life is crucial. This review highlights research examining factors that influence BMD and BMC in children and adolescents. While a sizeable amount of variation in BMD and BMC in children and adolescents can be attributed to genetic factors and body size, studies have also shown the positive influence of physical activity and calcium intake on bone development. Research supporting the role of these modifiable factors varies according to age, sex and the bone site studied. During the pubertal years, large gains in BMD and BMC are evident. However, physical activity and calcium intake are also important to the development of BMD and BMC during the prepubertal years. Thus, actions taken throughout childhood may exert a great impact on BMD and BMC, and overall bone health as an adult.

Physical activity and health: Musculoskeletal issues

Sarcopenia and osteoporosis, the complications of the age-related deterioration of the musculoskeletal system, result in increased risk of fracture, disability and death in old age. Consequently, the structure and function of skeletal muscle and bone and their adaptability are essential aspects of overall health, functional capacity and mobility during the whole lifespan. There is convincing clinical evidence that progressive resistance exercise training improves the properties of skeletal muscle in men and women across the age spectrum, thus providing a high reserve capacity for coping with the functional demands of physical tasks. Regarding bones, exercise is most effective during growth, the average gain in bone mineral content (BMC) and density (BMD) in controlled trials being of the order of 2–5% per year. The net gain of BMD after exercise interventions among older people is modest at a level of 1–3% per year. The functional structure of bone may also change as a result of training and other treatme...

SKELETAL MUSCLE ATROPHY, BONE LOSS, AND OXIDATIVE STRESS IN RATS WITH ALDOSTERONISM.

Purpose Congestive heart failure (CHF) is a syndrome composed of symptoms and signs arising from congested organs and hypoperfused tissues; it is mediated by a salt-avid state based on an activation of the circulating renin-angiotensin-aldosterone system (RAAS). Beyond this classic perspective, CHF also features a systemic illness with oxidative stress and progressive loss of soft tissues and bone that eventuates in a wasting syndrome termed cardiac cachexia. Pathophysiologic responses contributing to this illness are under investigation. Methods and Results To simulate one aspect of RAAS activation and to address musculoskeletal health in aldosteronism, 8-week-old male Sprague-Dawley rats weighing 253 ± 11 g were treated for 4 weeks with aldosterone (ALDO, 0.75 μg/h) and 1% NaCl in their drinking water (ALDOST) to raise plasma ALDO levels to those found in human CHF. These levels are accompanied by secondary hyperparathyroidism (SHPT) due to ionized hypocalcemia and hypomagnesemia resulting from increased urinary and fecal excretion of Ca2+ and Mg2+. We monitored body weight; skeletal muscle total Ca2+, and morphology, including scarring (a marker of necrosis) and the presence of myocyte apoptosis (TUNEL assay); tibial bone mineral density (BMD) and content (BMC) and strength to flexor stress; plasma α1-antiproteinase activity (AP), an inverse correlate of oxidative stress; and plasma parathyroid hormone (PTH). Compared with age-/gender-matched untreated controls, with ALDOST we found (mean ± SEM) inadequate weight gain (81 ± 5 vs 22 ±6 g), accompanied by increased (p Conclusions Aldosteronism in rats is accompanied by SHPT with skeletal muscle Ca2+ overloading and atrophy, but not myocyte death, a loss of bone minerals with reduced strength to resist flexor stress, and the appearance of oxidative stress. In human CHF, aldosteronism may contribute to its progressive wasting.

SPIRONOLACTONE IN THE PREVENTION OF SKELETAL MUSCLE ATROPHY AND BONE LOSS IN RATS WITH ALDOSTERONISM.

Purpose Congestive heart failure (CHF), with its classic signs and symptoms, has its origins rooted in a salt-avid state mediated largely by effector hormones of the renin-angiotensin-aldosterone system (RAAS). CHF is accompanied by a systemic illness that features oxidative stress and a progressive loss of soft tissues and bone that eventuates in a wasting syndrome termed cardiac cachexia. To simulate the inappropriate (relative to dietary Na+) aldosteronism found in human CHF, rats receive aldosterone (0.75 μg/h), together with 1% NaCl in drinking water (ALDOST). Skeletal muscle wasting and bone loss are found in ALDOST and associated with secondary hyperparathyroidism (SHPT). Herein we hypothesized that these responses could be attenuated by cotreatment with spironolactone (Spiro), an ALDO receptor antagonist. Methods and Results Eight-week-old male Sprague-Dawley rats received ALDOST alone for 4 weeks or together with Spiro (150 mg/kg/d by gavage). We monitored: body weight and skeletal muscle morphology, including scarring, a marker of myocyte necrosis, and the presence of apoptosis (TUNEL assay); femoral bone mineral density (BMD) and content (BMC); plasma α1-antiproteinase activity (AP), an inverse correlate of oxidative stress; and plasma parathyroid hormone (PTH). Compared with age-/gender-matched controls, with ALDOST we found (mean ± SEM): inadequate weight gain (81 ± 5 vs 22 ± 6 g; p Conclusions In rats with aldosteronism, cotreatment with an ALDO receptor antagonist, Spiro, prevents the appearance of SHPT and accompanying skeletal muscle atrophy, bone loss, and oxidative stress. The use of Spiro in human CHF may offer advantages that extend beyond its diuretic properties.

Idiopathic juvenile osteoporosis – an analysis of the muscle-bone relationship

Idiopathic Juvenile Osteoporosis (IJO), a disease of unknown etiology, manifests typically by pain, bone deformities and fractures. Due to limits in BMD data interpretation, evaluation of the muscle-bone functional unit has recently been proposed as a means to assess the general competence of the skeleton. The aim of this study was to evaluate skeletal status during the acute phase of IJO and during recovery from the disease in relation to muscles. The study population comprised 61 IJO children, including 34 girls (mean age: 13.6+/-3.1 years; range: 7-18) and 27 boys (14.3+/-3.3; 5-18 years). DXA total body (TB) and lumbar spine (S) bone mineral content (BMC) and density (BMD) were measured. Lean body mass (LBM) was employed to calculate SBMC/LBM, TBBMC/LBM, body height (BH)/LBM and LBM/body weight (BW) ratios. Previously established references for healthy controls were utilized for the calculation of Z-score values in IJO cases in respect to phase of the disease. IJO patients had significantly decreased Z-score values for TBBMD, SBMD, SBMC/LBM and TBBMC/LBM ratios but not for the LBM and BH/LBM or LBM/BW ratios. During the acute phase IJO girls had mean Z-scores for TBBMD and SBMD of -2.49+/-0.61 and -3.27+/-1.03, respectively, which were significantly lower than Z-scores during the recovery phase: -0.90+/-0.66, -1.38+/-0.95 (p<0.0001). IJO boys during the acute phase had Z-scores of -2.08+/-0.65 and -2.75+/-1.19 for TBBMD and SBMD, respectively, which were significantly lower than those during the recovery phase (-0.51+/-1.04 and -1.39+/-1.49; p<0.0001). Further, during the acute phase, TBBMC/LBM Z-scores of -2.95+/-1.15 and -2.56+/-1.49 were noted in girls and boys, respectively; the corresponding SBMC/LBM Z-scores were -2.66+/-1.07 and -2.22+/-1.62. During the recovery from IJO, TBBMC/LBM and SBMC/LBM Z-scores of -1.07+/-0.99 and -0.91+/-1.16 and of -1.15+/-1.40 and -0.68+/-1.45 were noted in girls and boys, respectively, and all were significantly higher than those during the acute phase (p<0.0001). The results of this study indicate that IJO is a bone disorder characterized by an imbalanced muscle-bone relationship and fractures at onset and during the acute phase and by at least a partial recovery without bone pain and new fractures. Implementation of the BH/LBM, TBBMC/LBM and SBMC/LBM ratios to the armamentarium of pediatricians diagnosing bone disorders will provide mechanically meaningful data for diagnostic purposes and, hopefully, for proper therapeutic decisions.

Bone Mineral Content and Density of Tunisian Male Rugby Players: Differences Between Forwards and Backs

The purpose of this study was to examine the effects of long-term rugby participation on bone mineral content (BMC) and density (BMD) of male rugby players and to determine if the diverse stimuli elicited by the actions of forwards and backs affect their skeleton differently. Dual energy X-ray absorptiometry (DXA) scans were obtained from 20 male rugby players (10 Forwards and 10 Backs) who actively participated in rugby for the past 13 yr, and from 29 age matched non active subjects of the same ethnic origin. Both groups (rugby players and controls) had comparable age (23.6 +/- 3.7 yr vs. 25.6 +/- 3.4 yr), height (178.1 +/- 4.0 cm vs. 178.3 +/- 6.0 cm), and body fat percentage (14.2 +/- 4.4 vs. 16.5 +/- 5.1). Rugby players showed greater total body mass, and greater total lean and fat body masses than control subjects (p < 0.01). Whole spine BMC and BMD were 52 % and 15 % higher, respectively, in the rugby players than in the control subjects (p < 0.001). Furthermore, rugby players displayed higher skeletal BMC (40 %, 37 % and 58 % for legs, arms and pelvis, respectively) and BMD (16 %, 21 % and 17 %, respectively) than controls. Within the rugby group, forwards were taller, heavier and had greater body fat percentage, and greater total lean and fat body masses than backs (p < 0.05 to p < 0.001). Likewise, BMC, BMD and bone area for the whole body and at specific sites such as arms, spine and legs were also greater in the forwards (p < 0.05 to p < 0.001). Long-term rugby participation, starting at pubertal age, is associated with markedly increased BMC, BMD and bone size at all skeletal sites, except at the head. The musculo-skeletal adaptations, greater in forwards than in backs, could mimic training responses and therefore explain the bone features, localized in specific stressed regions.

Muscle training for bone strength

The main function of bone is to provide the mechanical integrity for locomotion and protection; accordingly, bone mass and architecture are adjusted to control the strains produced by mechanical load and muscular activity. Age-related patterns involve peak bone mass during growth, a plateau in adulthood, and bone loss during aging. The decline in bone mass and structural integrity results in increased risk of fractures, particularly in post-menopausal women. Athletes competing in strength and power events, such as weight-lifting and jumping, have superior bone mass and structure compared with their untrained counterparts in all age groups. Exercise seems to be most effective during rapid growth, the average gain in bone mineral content (BMC) and density (BMD) in controlled trials being of the order of 2-5% per year. The net gain of BMD after exercise interventions among older people is modest, at a level of 1-3% per year, but it is not clear whether positive effects can be maintained over a longer time. Although aerobic exercise is important in maintaining overall health, the resistance type of muscle training may be more applicable to the basic rules of bone adaptation and site-specific effects of exercise, have more favorable effects in maintaining or improving bone mass and architecture, and be safe and feasible for older people. It has been suggested that there is an opportunity for resistance training, for improved effects on BMD in postmenopausal women in bones which have less daily loading. In addition to BMC and BMD, bone geometry and mass distribution may also change as a result of training and other treatment, such as hormonal replacement therapy, thereby further improving bone strength and reducing fracture risk. Appropriate training regimens may reduce the risk of falls and the severity of fall-related injuries, and also constitute potential therapy to improve functional ability and the quality of life in osteoporotic patients. However, further research is needed on dose-response relationships between exercise and bone strength, the feasibility of high-load, high-speed and impact-type of physical training, and the risks and benefits of intensive exercisein elderly individuals.

Relationship of Cytokines to Bone Mineral Density and Content in Postmenopausal Women

Loss of estrogen results in a decrease in bone mineral density (BMD) and content (BMC) and an increase in cytokine production. Elevated cytokines lead to an upregulation of osteoclastogenesis. We determined the relationship between cytokines and BMD and BMC in healthy, postmenopausal women (n=105) not on hormone therapy. Spine BMD and BMC (SpBMD, SpBMC) and hip BMD and BMC were measured by dual energy x-ray absorptiomety. We stimulated whole blood with three concentrations of lipopolysaccharide (low [L], medium [M], high [H]) and assessed cytokine production by a human cytokine multiplex immunoassay (LINCO research). Cytokine data were transformed. We observed significant associations between SpBMD and interleukin (IL)-1M (p<0.05) and IL-1H (p<0.01) plus SpBMC and IL-1M (p=0.01), granulocyte-colony stimulating factor (G-CSF)M, IL-6M, and IL-1H (p<0.05). Femoral neck (FN) BMC was significantly related to IL-1M, interferon gamma (INFγ)M, IL-7H, IL-8H, and IL-1H (p<0.05) while total hip (TH) BMD was significantly associated with IL-1M (p<0.05). Stepwise multiple regression models were: SpBMD=0.651 + 0.00007(IL-1H) + 0.005(age) SpBMC=32.869 - 1.982(BMI) + 0.633(WT) + 0.459(age) + 0.377(IL-1M) FN BMC=0.637 + 0.029(HT) + 0.0001(IL-1H) - 0.509(IL-8H) + 0.212(IL-7H) TH BMD=0.728 + 0.002(WT) + 0.003(IL-1M) We confirmed that cytokine concentrations were related to SpBMC, SpBMD, FN BMC and TH BMD, but not to BMD or BMC at other sites, suggesting that cytokines mainly affect trabecular bone. Supported by funds from NIAMS/NIH (AR046922) and USDA/ARS,WHNRC.

Factors Influencing Bone Mineral Density and Content in Young Girls

The influence of height, body mass, daily physical activity (DPA), and dietary calcium intake (DCI) on bone mineral density (BMD) and content (BMC) was evaluated in 33 four-year-old girls. Results indicated that body mass was significantly correlated with and predictive of BMD and BMC at all sites except the femoral neck BMD. DPA and height also explained a significant proportion of the variance in femoral neck BMD and BMC of the lumbar spine and total body. DCI was not related to or predictive of BMD or BMC at any bone site. These findings highlight the importance of engaging in daily weight-bearing physical activity to promote bone health in young girls.

Bone Mineral Density and Content: Dual Energy X‐ray Absorptiometry versus Peripheral Quantitative Computed Tomography

Dual energy x-ray absorptiometry (DXA) assesses bone mineral density (BMD) and content (BMC), but does not differentiate between cortical (Cr) and trabecular (Tb) bone, independent contributors to bone strength and fracture risk. Peripheral quantitative computed tomography (pQCT) provides a 3-D image of bone and assesses Tb and Cr bone. We compared total (To) BMC, TbBMC, volumetric (v) BMD, and TbBMD of the 4% distal tibia, and ToBMC, CrBMC, vBMD, and CrBMD of the 33% midshaft femur using pQCT to lumbar spine (Sp), hip, and femoral neck (FN) BMD and BMC from DXA in healthy, postmenopausal women. Tibia pQCT BMC and BMD measures were highly correlated (p<0.0001) with DXA measures, while femur pQCT was related to hip and FN BMC and BMD DXA measures, but not spine BMD DXA (Table 1). Table 1. Correlation Coefficients between DXA and pQCT Measures (N=187) Skeletal heterogeneity between axial and peripheral sites suggests that BMD measures from one site are not a good proxy for another BMD site. Further studies are needed to determine the relevance of peripheral densitometry data. Supported by NIAMS/NIH (AR046922); USDA, ARS, WHNRC.

Dietary conjugated linoleic acid (CLA) in the cis‐9, trans‐11 isoform reduces parathyroid hormone (PTH) in male, but not female rats

Previously a mixture of CLA isoforms reduced PTH in male rats over 8 wk. The objective herein was to determine: which isoform caused the reduction in PTH; if the affect was sex specific; and if CLA-induced reductions in PTH were transient. Male and female weanling rats (n=48) were randomized to a control diet or one made with 0.5% of the diet as cis-9, trans-11 CLA, 0.5% of the diet as trans-10, cis-12 CLA or these CLA in a mixture. Measurements made after 4, 8 and 16 wk were: body weight, bioactive PTH, ionized Ca, whole body and regional (lumbar spine, femur and tibia) bone mineral content (BMC) and density (BMD) using dual energy x-ray absorptiometry. Using a factorial design (CLA isomers, age and sex plus interactions), a sex by cis-9, trans-11 CLA interaction was observed in that reduced PTH (139.5 ± 63.9 vs 95.8 ± 42.4 pg/ml, P=0.02) and reduced femur BMC (0.63 ± 0.22 vs 0.58 ± 0.18 g, P=0.03) occurred in males only. No other effects of cis-9, trans-11 CLA were observed. Regarding trans-10, cis-12 CLA, no interaction effects were observed, but a main effect was observed to reduce lumbar spine BMC (0.56 ± 0.17 vs 0.53 ± 0.16 g, P<0.01) and BMD (0.265 ± 0.044 vs 0.255 ± 0.044 g/cm2, P<0.01). In summary, the cis-9, trans-11 CLA isoform is responsible for reduced PTH and this effect is sex-specific; this was true whether fed as a pure isomer or mixed with an equal amount of trans-10, cis-12 CLA. These results require confirmation in other animal models such as ovariectomized rats and also in humans to expand the understanding of dietary CLA in health. Funding: Dairy Farmers of Canada & NSERC.