Femoral BMC Research Articles

International longitudinal pediatric reference standards for bone mineral content

To render a diagnosis pediatricians rely upon reference standards for bone mineral density or bone mineral content, which are based on cross-sectional data from a relatively small sample of children. These standards are unable to adequately represent growth in a diverse pediatric population. Thus, the goal of this study was to develop sex and site-specific standards for BMC using longitudinal data collected from four international sites in Canada and the United States. Data from four studies were combined; Saskatchewan Paediatric Bone Mineral Accrual Study ( n = 251), UBC Healthy Bones Study ( n = 382); Penn State Young Women's Health Study ( n = 112) and Stanford's Bone Mineral Accretion study ( n = 423). Males and females (8 to 25 years) were measured for whole body (WB), total proximal femur (PF), femoral neck (FN) and lumbar spine (LS) BMC (g). Data were analyzed using random effects models. Bland–Altman was used to investigate agreement between predicted and actual data. Age, height, weight and ethnicity independently predicted BMC accrual across sites ( P < 0.05). Compared to White males, Asian males had 31.8 (6.8) g less WB BMC accrual; Hispanic 75.4 (28.2) g less BMC accrual; Blacks 82.8 (26.3) g more BMC accrual with confounders of age, height and weight controlled. We report similar findings for the PF and FN. Models for females for all sites were similar with age, height and weight as independent significant predictors of BMC accrual ( P < 0.05). We provide a tool to calculate a child's BMC Z-score, accounting for age, size, sex and ethnicity. In conclusion, when interpreting BMC in pediatrics we recommend standards that are sex, age, size and ethnic specific.

Lack of Bone Neoplasms and Persistence of Bone Efficacy in Cynomolgus Macaques After Long-Term Treatment With Teriparatide [rhPTH(1-34)

In rats, teriparatide [rhPTH(1-34)] causes marked increases in bone mass and osteosarcoma. In primates, teriparatide causes lesser increases in bone mass, and osteosarcomas have not been reported. Previous studies in primates were not designed to detect bone tumors and did not include a prolonged post-treatment observation period to determine whether tumors would arise after cessation of treatment. Ovariectomized (OVX), skeletally mature, cynomolgus monkeys (n = 30 per group) were given teriparatide for 18 mo at either 0 or 5 microg/kg/d subcutaneously. After 18 mo of treatment, subgroups of six monkeys from both groups were killed and evaluated, whereas all remaining monkeys entered a 3-yr observation period in which they did not receive teriparatide. Surveillance for bone tumors was accomplished with plain film radiographs, visual examination of the skeleton at necropsy, and histologic evaluation of multiple skeletal sites. Quantitative assessments of bone mass, architecture, and strength were also performed. After the 18-mo treatment period, vertebral BMD, BMC, and strength (ultimate load) were increased by 29%, 36%, and 52%, respectively, compared with OVX controls. Proximal femur BMD, BMC, and strength were also increased by 15%, 28% and 33%, respectively. After 3 yr without treatment, no differences in bone mass or strength at the vertebra were observed relative to OVX controls; however, the femoral neck showed significant persistence in stiffness (20%), BMC (14%), and trabecular BV/TV (53%), indicating a retention of teriparatide efficacy at the hip. Radiographs and histology did not identify any bone proliferative lesions or microscopic lesions of osteosarcoma at the end of the treatment or observation period. These data indicate that teriparatide did not induce bone proliferative lesions over a 4.5-yr interval of observation, including 18 mo of treatment and 3 yr of follow-up observation. Bone analyses confirmed that teriparatide caused increases in bone mass and strength, consistent with previous studies. During the withdrawal phase, beneficial effects of teriparatide treatment on the vertebra were lost; however, some of the beneficial effects on the proximal femur persisted for 3 yr after cessation of treatment. Although the lack of bone tumors in this study provides some additional reassurance regarding the safety of teriparatide for the primate skeleton, the small group size and other limitations of this, or any other animal study, limit the ability to draw definitive conclusions regarding the risk of bone tumor developments in patients.

Caloric Restriction Decreases Cortical Bone Mass but Spares Trabecular Bone in the Mouse Skeleton: Implications for the Regulation of Bone Mass by Body Weight

Body weight is positively correlated with bone mass and density, and both muscle mass and body fat are thought to play a role in regulating bone metabolism. We examined bone metabolism in calorically restricted mice to determine how alterations in soft tissue mass affect bone mass, density, and strength. Caloric restriction (CR) was initiated in male mice at 14 wk of age at 10% restriction, increased to 25% restriction at 15 wk, and then increased to 40% restriction at 16 wk, where it was maintained until 24 wk of age when the study was terminated. Control mice were fed ad libitum (AL). Body composition, BMD, and BMC were measured by DXA, BMD and BMC in the femoral metaphysis were measured by pQCT, femora were tested in three-point bending, serum leptin and IGF-1 were measured using immunoassay, and osteoblast and osteoclast numbers were determined using histomorphometry. Body weight, lean mass, fat mass, percent body fat, serum leptin, and serum IGF-1 were all significantly lower in CR mice than AL mice. Whole body BMC and BMD did not differ significantly between the two groups. Femur BMC, BMD, cortical thickness, and fracture strength decreased significantly in CR mice, but trabecular bone volume fraction in the femur did not change with food restriction. Vertebral cortical thickness also decreased with caloric restriction, whereas spine BMC, BMD, and trabecular bone volume fraction were significantly increased with caloric restriction. Caloric restriction and its related weight reduction are associated with marked decreases in lean mass, fat mass, serum leptin and IGF-1, and cortical bone mass. Consistent with the opposite effects of leptin on cortical and cancellous bone, trabecular bone mass is spared during food restriction.

Acute and Chronic Effects of Honey and Its Carbohydrate Constituents on Calcium Absorption in Rats

The effects of honey and its carbohydrate constituents (glucose, fructose, and raffinose) on calcium absorption in rats were investigated in acute and chronic feeding studies. In the acute study, rats ( n = 120) were gavaged with an oral solution consisting of (a) 10 microCi (45)Ca, (b) 25 mg of calcium as calcium acetate, and (c) one of the following: 0 mg of honey (control), or 200, 500, or 800 mg of honey, a glucose-fructose mixture, 10.75 mg of raffinose, or 200 mg of raffinose. Another group received (45)Ca intraperitoneally. Femurs were collected 2 days later and analyzed for (45)Ca content. Rats given 500 and 800 mg of honey showed 25.5 and 33.6% increases in calcium absorption ( P<0.05), respectively, over the control group. Groups given the glucose-fructose mixture or 200 mg of raffinose had a significantly higher increase in calcium absorption than the control group (17.1 and 25.6%, respectively). In the chronic study, rats (n=96) were fed for 8 weeks with either 0% honey (control), 5% honey, 10% honey, or a glucose-fructose-raffinose (GFR) mixture. Femurs of GFR-fed rats had significantly lower calcium content, (45)Ca absorption, width, and BMD (at distal region) than control rats. Groups fed honey did not show the negative effects of GFR on bone, but had no advantage over the control group. No significant differences were observed in femur length, density, strength, or BMC among any treatment group compared to the control group. These results indicate that although a positive dose-response effect of honey and its carbohydrate constituents on calcium absorption was observed in the acute study, this effect disappeared upon long-term feeding in rats, implying adaptation had occurred.

Influence of Calcium Intake and Physical Activity on Proximal Femur Bone Mass and Structure Among Pre- and Postmenopausal Women. A 10-Year Prospective Study

This 10-year follow-up evaluated the effect of physical activity and calcium intake on proximal femur bone mass (BMC) and structural indices (CSA and Z) and physical performance. A cohort of 133 premenopausal and 134 postmenopausal women with contrasting levels of physical activity (high [PA+]) and low [PA-]) and calcium intake (high [Ca+] and low [Ca-]) was measured with DXA at baseline and 5 and 10 years thereafter. Among premenopausal women, the mean (95% CI) femoral neck BMC was 3.8% (-0.1 to 7.8%) and the trochanter BMC 6.7% (2.4 to 11.3%) greater in the PA+ group than the PA- group. There was no difference between the Ca-intake groups. Among postmenopausal women, the mean femoral neck BMC was 4.2% (-0.2 to 8.8%) greater in the Ca+ group than in the Ca- group and 6.9% (2.2 to11.8%) greater in the PA+ group than in the PA- group. For trochanter BMC, the corresponding differences were 2.7% (-1.6 to 7.2%) and 5.5% (0.9 to 10.3%). The mean differences in CSA and Z were 3.8% (-0.9 to 8.7%) and 4.4% (-2.1 to 11.4%) in favor of the Ca+ group and 6.8% (1.9 to 12.0%) and 9.6% (2.5 to 17.1%) in favor of the PA+ group, respectively. Proximal femur BMC declined generally, but the initial differences between the physical activity and the calcium intake groups were maintained. High calcium intake seemed to slow the decline in trochanter BMC in premenopausal women, while high physical activity was beneficial for proximal femur, particularly among older women.

Effects of hindlimb unloading and bisphosphonates on the serum proteome of rats

Hindlimb unloading has been used as a model for bone loss associated with extended bed rest or space travel. However, this model also reduces muscle mass and influences other biological systems. To evaluate the impact of hindlimb unloading on bone and overall health, we applied 2-D gel electrophoresis (2-DE)-based proteomics to serum samples collected from 24 5-month-old female rats that were treated for 2 weeks under three conditions: control, hindlimb unloading (HU) and unloading plus bisphosphonate (HUA) ( n = 8/group). Prior to the intervention, rats were injected with 3H-tetracycline to label bone surfaces. At the end of the experiment bone, urine, and serum samples were collected. As expected, HU reduced femur aBMD and BMC and increased daily urinary 3H-tetracycline (a measure of bone resorption rate) and these effects were reversed by bisphosphonate. In addition, serum osteocalcin and TRAP5b were decreased in the HUA compared to control and HU. Abundant proteins, albumin, IgG and transferrin were removed from serum samples prior to 2-DE analysis ( n = 5 analytical replicates). Statistical analysis of spot intensities revealed 53 differentially expressed spots among the 3 groups. Cluster analysis shows that 30 spots reflect changes unique to the HU group (i.e. potential bone biomarkers), 6 unique to HUA (i.e. drug related), and 17 common to HU and HUA (e.g. potential mental stress or muscle loss markers). Spots were identified by LC-MS/MS after in-gel trypsin digestion and were found to relate to a variety of physiological functions.

Exercise and Calcium Combined Results in a Greater Osteogenic Effect Than Either Factor Alone: A Blinded Randomized Placebo-Controlled Trial in Boys

We examined the combined effects of exercise and calcium on BMC accrual in pre- and early-pubertal boys. Exercise and calcium together resulted in a 2% greater increase in femur BMC than either factor alone and a 3% greater increase in BMC at the tibia-fibula compared with the placebo group. Increasing dietary calcium seems to be important for optimizing the osteogenic effects of exercise. Understanding the relationship between exercise and calcium during growth is important given that the greatest benefits derived from these factors are achieved during the first two decades of life. We conducted a blinded randomized-controlled exercise-calcium intervention in pre- and early-pubertal boys to test the following hypotheses. (1) At the loaded sites (femur and tibia-fibula), exercise and calcium will produce greater skeletal benefits than either exercise or calcium alone. (2) At nonloaded sites (humerus and radius-ulna), there will be an effect of calcium supplementation. Eighty-eight pre- and early-pubertal boys were randomly assigned to one of four study groups: moderate impact exercise with or without calcium (Ca) (Ex+Ca and Ex+placebo, respectively) or low impact exercise with or without Ca (No-Ex+Ca and No-Ex+Placebo, respectively). The intervention involved 20 minutes of either moderate- or low-impact exercise performed three times a week and/or the addition of Ca-fortified foods using milk minerals (392+/-29 mg/day) or nonfortified foods over 8.5 months. Analysis of covariance was used to determine the main and combined effects of exercise and calcium on BMC after adjusting for baseline BMC. At baseline, no differences were reported between the groups for height, weight, BMC, or bone length. The increase in femur BMC in the Ex+Ca group was approximately 2% greater than the increase in the Ex+placebo, No-Ex+Ca, or No-Ex+Placebo groups (all p<0.03). At the tibia-fibula, the increase in BMC in the Ex+Ca group was approximately 3% greater than the No-Ex+placebo group (p<0.02) and 2% greater than the Ex+Placebo and the No-Ex+Ca groups (not significant). No effect of any group was detected at the humerus, ulna-radius, or lumbar spine for BMC, height, bone area, or volume. In this group of normally active boys with adequate calcium intakes, additional exercise and calcium supplementation resulted in a 2-3% greater increase in BMC than controls at the loaded sites. These findings strengthen the evidence base for public health campaigns to address both exercise and dietary changes in children for optimizing the attainment of peak BMC.

PTH Stimulates Bone Formation in Mice Deficient in Lrp5

Lrp5 deficiency decreases bone formation and results in low bone mass. This study evaluated the bone anabolic response to intermittent PTH treatment in Lrp5-deficient mice. Our results indicate that Lrp5 is not essential for the stimulatory effect of PTH on cancellous and cortical bone formation. Low-density lipoprotein receptor-related protein 5 (Lrp5), a co-receptor in canonical Wnt signaling, increases osteoblast proliferation, differentiation, and function. The purpose of this study was to use Lrp5-deficient mice to evaluate the potential role of this gene in mediating the bone anabolic effects of PTH. Adult wildtype (WT, 23 male and 25 female) and Lrp5 knockout (KO, 27 male and 26 female) mice were treated subcutaneously with either vehicle or 80 microg/kg human PTH(1-34) on alternate days for 6 weeks. Femoral BMC and BMD were determined using DXA. Lumbar vertebrae were processed for quantitative bone histomorphometry. Bone architecture was evaluated by microCT. Data were analyzed using a multiway ANOVA. Cancellous and cortical bone mass were decreased with Lrp5 deficiency. Compared with WT mice, cancellous bone volume in the distal femur and the lumbar vertebra in Lrp5 KO mice was 54% and 38% lower, respectively (p<0.0001), whereas femoral cortical thickness was 11% lower in the KO mice (p<0.0001). The decrease in cancellous bone volume in the lumbar vertebrae was associated with a 45% decrease in osteoblast surface (p<0.0001) and a comparable decrease in bone formation rate (p<0.0001). Osteoclast surface, an index of bone resorption, was 24% lower in Lrp5 KO compared with WT mice (p<0.007). Treatment of mice with PTH for 6 weeks resulted in a 59% increase in osteoblast surface (p<0.0001) and a 19% increase in osteoclast surface (p=0.053) in both genotypes, but did not augment cancellous bone volume in either genotype. Femur cortical thickness was 11% higher in PTH-treated mice in comparison with vehicle-treated mice (p<0.0001), regardless of genotype. Whereas disruption of Lrp5 results in decreased bone mass because of decreased bone formation, Lrp5 does not seem to be essential for the stimulatory effects of PTH on cancellous and cortical bone formation.

High Dietary Phosphate Intake Reduces Bone Strength in the Growing Rat Skeleton

Nutrition influences peak bone mass development in early adulthood. The effect of high dietary phosphate intake on the growing skeleton of 1-month-old male rats (n = 30) was assessed in an 8-week intervention. High dietary phosphate intake increased bone remodeling and impaired bone material properties, diminishing bone mechanical strength. High dietary phosphate intake is typical in the Western diet. Abundant phosphate intake enhances parathyroid secretion and bone metabolism. To study the influence of high dietary phosphate intake on growing bone homeostasis and structure, we submitted growing rats to experimental diets that varied in their phosphate content. One-month-old intact male rats (n = 30) were fed a control diet (Ca:P 1:1) or an experimental diet of either Ca:P 1:2 or Ca:P 1:3 for 8 weeks. At the beginning and the end of the study period, the right femurs were measured using DXA. Double labeling with tetracycline injection was performed 12 and 2 days before death. After death, hind legs were cut loose. Left femurs were processed for histomorphometry. Right femurs were measured with pQCT. Mechanical testing was performed on the right femoral neck and tibial shaft. Six right tibias were analyzed with microCT. Serum PTH, calcium, and phosphate contents were analyzed. High-phosphate intake impaired growth of the animal, limited bone longitudinal growth, and restricted femur BMC and BMD build-up. Osteoclast number, osteoblast perimeter, and mineral apposition rate were increased, and trabecular area and width were decreased. Phosphate decreased femur midshaft total bone BMD, cortical bone BMD, and mean cortical thickness. High-phosphate diet reduced femoral neck and tibial shaft ultimate strength and tibia stiffness and toughness. In addition, serum PTH increased. High dietary phosphate intake reduced growth, skeletal material, and structural properties and decreased bone strength in growing male rats. Adequate calcium could not overcome this.

A Positive Dose–Response Effect of Vitamin D Supplementation on Site-Specific Bone Mineral Augmentation in Adolescent Girls: A Double-Blinded Randomized Placebo-Controlled 1-Year Intervention

The effect of vitamin D supplementation on bone mineral augmentation in 212 adolescent girls with adequate calcium intake was studied in a randomized placebo-controlled setting. Bone mineral augmentation determined by DXA increased with supplementation both in the femur and the lumbar vertebrae in a dose-responsive manner. Supplementation decreased the urinary excretion of resorption markers, but had no impact on formation markers. Adequate vitamin D intake protects the elderly against osteoporosis, but there exists no indisputable evidence that vitamin D supplementation would benefit bone mineral augmentation. The aim of this 1-year study was to determine in a randomized double-blinded trial the effect of 5 and 10 microg vitamin D3 supplementation on bone mineral augmentation in adolescent girls with adequate dietary calcium intake. Altogether, 228 girls (mean age, 11.4 +/- 0.4 years) participated. Their BMC was measured by DXA from the femur and lumbar spine. Serum 25-hydroxyvitamin D [S-25(OH)D], intact PTH (S-iPTH), osteocalcin (S-OC), and urinary pyridinoline (U-Pyr) and deoxypyridinoline (U-Dpyr) were measured. Statistical analysis was performed both with the intention-to-treat (IT) and compliance-based (CB) method. In the CB analysis, vitamin D supplementation increased femoral BMC augmentation by 14.3% with 5 microg and by 17.2% with 10 microg compared with the placebo group (ANCOVA, p = 0.012). A dose-response effect was observed in the vertebrae (ANCOVA, p = 0.039), although only with the highest dose. The mean concentration of S-25(OH)D increased (p < 0.001) in the 5-microg group by 5.7 +/- 15.7 nM and in the 10-microg group by 12.4 +/- 13.7 nM, whereas it decreased by 6.7 +/- 11.3 nM in the placebo group. Supplementation had no effect on S-iPTH or S-OC, but it decreased U-DPyr (p = 0.042). Bone mineral augmentation in the femur was 14.3% and 17.2% higher in the groups receiving 5 and 10 microg of vitamin D, respectively, compared with the placebo group, but only 10 mug increased lumbar spine BMC augmentation significantly. Vitamin D supplementation decreased the concentration of bone resorption markers, but had no impact on bone formation markers, thus explaining increased bone mineral augmentation. However, the positive effects were noted with the CB method but not with IT.

Infant Growth Influences Proximal Femoral Geometry in Adulthood

The relationship between early growth and adult femoral geometry has not been studied previously. In 333 adults, we were able to show that infant weight predicts femoral width and cross-sectional moment of inertia but not femoral neck length. These results support the hypothesis that growth in early life leads to persisting differences in proximal femoral geometry. Both femoral geometry and bone mass have been shown independently to predict both hip strength and fracture risk. Whereas growth during intrauterine and early postnatal life has been shown to influence adult bone mass, the relationship between growth in early life and adult femoral geometry has not been described previously. We studied the relationship between growth during early life, adult hip geometry, and proximal femur bone mass in a sample of 333 men and women (60-75 years of age), for whom birth weight and weight at 1 year of age were recorded. Hip geometry was derived using Hip Structure Analysis software from proximal femur DXA scans (Hologic QDR 1000). There were significant (p < 0.002) relationships between weight at age 1 year and measures of femoral width as well as intertrochanteric (IT) cross-sectional moment of inertia (CSMI), but not with femoral neck length. The relationships with measures of femoral width but not CSMI remained after adjusting for adult body weight and were independent of proximal femoral BMC. These results support the hypothesis that different patterns of growth in utero and during the first year of life lead to persisting differences in proximal femoral geometry, thereby mediating in part the effects of early growth on risk of hip fracture in adulthood.

Acute vs. chronic effects of honey and its carbohydrate constituents on calcium absorption in rats

Previously we reported the acute effects of honey and its carbohydrate constituents (i.e. glucose, fructose, and raffinose) in enhancing calcium absorption in growing rats. We observed a significant dose-response enhancement of calcium absorption with honey (33.6% and 25.5% with 800 and 500 mg honey, respectively), explained in part by its carbohydrate constituents. Here we report the chronic effects of feeding rats with diets containing honey or its carbohydrate constituents. Six-week old male rats (n = 100) were fed with powdered diet consisting of either 0% honey (control), 5% honey, 10% honey, or a glucose-fructose-raffinose mixture. After 8 weeks, daily calcium retention and percent apparent calcium absorption of rats given the 10% honey were significantly higher than control and other groups (P < 0.05). However, there were no significant differences in the femur density, femur peak breaking force, femur BMC, and femur uptake of 45Ca. These results indicate that despite increased calcium absorption and retention with the higher dose of honey, there was no significant effect on femur measures. Funded by the National Honey Board

Dose-response Effects of Exercise Intensity on Bone in Ovariectomized Rats

The purpose of this study was to investigate the effects of different intensities of resistance exercise training on established bone loss in ovariectomized (ovx-ed) rats by densitometry and histomorphometry. Thirty Female Wistar rats were ovx-ed or sham-operated (SHM) at 3 months of age and maintained untreated for 5 months after surgery to establish osteopenia. When they reached 8 months, the ovx-ed rats were divided into four groups in accordance with varying weights applied to a squat-training device: The weight classifications were 1) kept sedentary (OVX); 2) lifted 0 g (LOW); 3) 750 g (MID); and 1500 g (HIGH). The rats in the three training groups performed weight-lifting of 10 reps, performing 2 sets per day, 3 days a week for a ten week period. The Femora and tibiae were removed from each rat and were used for analyses. Ovx induced a significant loss of total BMC in all the bones tested. The ovx-induced femoral BMC loss was observed at all locations tested on the bone (proximal, shaft, and distal), and exercise-intensity dependent restoration was found at the proximal and the distal sites, but not at the shaft. In the tibia, ovx-induced significant bone loss occurred only at the proximal metaphyseal site. The training increased the tibial BMC of all sites in an exercise-intensity dependently, irrespective of the degree of ovx effect. At the tibial shaft, the training increased the cortical bone mass significantly above sham level by the bone apposition at the periosteum. At the proximal tibial metaphysis, exercise had no effect on the cancellous bone volume after ovx-induced bone loss. This finding suggests that the exercise induced bone increase in the ovx-ed rats was from cortical bone, not from cancellous bone, at least in the proximal tibia. These findings indicate that the weight-lifting exercise in rats reversed the ovx-induced bone loss in an exercise-intensity dependent and site-specific manner, even in established osteopenic skeleton 5 mon after ovx.

ACQUISITION OF BONE MASS DURING EARLY ADULTHOOD: A PROSPECTIVE COHORT STUDY

Since most of our current knowledge about the concept of bone gain during adolescence or early adulthood comes from the cross-sectional studies, we aimed to evaluate natural course of changes in bone mineral density prospectively during early adulthood in a cohort. Twenty-two volunteers (15 female, 7 male) with the mean age of 20.0 ± 0.69 years were enrolled into the study. Subjects with any known secondary cause of osteoporosis were excluded from the study. Demographic variables, anthropometric measurements were recorded. Subjects underwent an interview about risk factors for osteoporosis. Physical activity level and calcium intake were evaluated by European Vertebral Osteoporosis Study questionnaire. Lumbar and femoral bone mineral densities were measured using Dual Energy X-ray Absorptiometry (DXA) at baseline and two years after. L1-4 BMD increased from 0.925 ± 0.099 g/cm2 to 0.957 ± 0.094 g/cm2(p = 0.002) and total femur BMD increased from 0.866 ± 0.113g/cm2 to 0.908 ± 0.108g/cm2(p = 0.0001). BMC of L1-4 increased significantly (p = 0.022), however there was no change in bone area measurements (p = 0.82). In case of femoral total measurements, both BMC and bone area demonstrated significant increase over the study period (p = 0.0001 and p = 0.0001). There were significant positive differences in bone mineral densities for L3, L4 measurements in males and for L3 measurements in females (p = 0.028, p = 0.018 and p = 0.02 respectively). Different from the bone gain during adolescent years which is usually attributed to volumetric expansion of the bones; we were able to demonstrate that bone gain continues through early years of adulthood. It would be rational to extend preventive measures beyond adolescence, into early adulthood to optimize the bone mass.

Flaxseed oil and inflammation-associated bone abnormalities in interleukin-10 knockout mice

Interleukin-10 −/− (IL-10) knockout (KO) mice develop an intestinal inflammation that closely mimics human inflammatory bowel disease (IBD) which is accompanied by inflammation-associated bone abnormalities and elevated serum proinflammatory cytokines. The objective of this study was to use the IL-10 KO mouse model to determine whether flaxseed oil (FO) diet, rich in α-linolenic acid (ALA), attenuates intestinal inflammation and inflammation-associated bone abnormalities, compared to a corn oil (CO) control diet. Male wild-type (WT) or IL-10 KO mice were fed a 10% CO or 10% FO diet from weaning (postnatal day 28) for 9 weeks. At necropsy, serum, intestine, femurs and lumbar vertebrae were collected and analyzed. IL-10 KO mice fed CO had lower femur bone mineral content (BMC; P<.001), bone mineral density (BMD; P<.001), peak load ( P=.033) and lumbar vertebrae BMD ( P=.02) compared to WT mice fed either diet. Flaxseed oil had a modest, favorable effect on IL-10 KO mice as femur BMC, BMD and peak load were similar to WT mice fed CO or FO. In addition, lumbar vertebra BMD was similar among IL-10 KO mice fed FO and WT mice fed CO or FO. The fact that FO attenuated serum tumor necrosis factor-α (TNF-α) among IL-10 KO mice suggests that the positive effects of FO on femur BMC, BMD, peak load and vertebral BMD in IL-10 KO mice may have been partly mediated by changes in serum TNF-α. In conclusion, these findings suggest that a dietary level of ALA attainable from a 10% flaxseed oil diet results in modest improvements in some bone outcomes but does not attenuate intestinal inflammation that is characteristic of IL-10 KO mice.

Growth Hormone Injections Improve Bone Quality in a Mouse Model of Osteogenesis Imperfecta

Systemic growth hormone injections increased spine and femur length in a mouse model of OI. Femur BMC, cross-sectional area, and BMD were increased. Smaller gains were produced in vertebral BMC and cross-sectional area. Biomechanical testing showed improvements to structural and material properties in the femur midshaft, supporting expanded testing of growth hormone therapy in children with OI. Osteoblasts in heterozygous Cola2oim mutant mice produce one-half the normal amounts of the alpha2 strand of type I procollagen. The mice experience a mild osteogenesis imperfecta (OI) phenotype, with femurs and vertebrae that require less force than normal to break in a biomechanical test. Subcutaneous injections of recombinant human growth hormone (rhGH) or saline were given 6 days per week to oim/+ mice between 3 and 12 weeks of age, in a protocol designed to simulate a trial on OI children. rhGH injections promoted significant weight gain and skeletal growth compared with saline-treated control animals. Femur and spine lengths were increased significantly. Significant increases at the femur midshaft in cortical BMD (2.2%), BMC (15.5%), and cross-sectional area (13%) were produced by rhGH treatment. Increases in the same cortical bone parameters were measured in the metaphyseal region of the femur and in tail vertebrae, but lumbar vertebrae showed significant increases in BMC (9.6%) and cross-sectional area (10.1%) of trabecular bone. Three-point bending testing documented functional improvements to the femur mid-shafts. GH treatment produced significant increases in bone stiffness (23.7%), maximum load (30.8%), the energy absorbed by the femurs to the point of maximum load (44.5%), and the energy to actual fracture (40.4%). The ultimate stress endured by the bone material was increased by 14.1%. Gains in bone length, cross-sectional area, BMD, BMC, structural biomechanical properties, and strength were achieved without directly addressing the genetic collagen defect in the mice. Results support expanded clinical testing of GH injections in children with OI.

미역취뿌리 추출물이 성장기 흰쥐의 골대사에 미치는 영향

본 연구에서는 3주령의 암컷 흰쥐를 이용하여 미역취뿌리 추출물이 골대사에 미치는 영향을 조사하고자 미역취뿌리 메탄올 추출물을 10, 50, 100 mg/kg/day의 농도로 음용수에 희석하여 9주간 사육시켰다. 매주 체중과 사료효율을 측정한 결과, 대조군에 비해 체중의 변화나 사료효율에는 유의적으로 차이가 없는 것으로 보아 미역취 뿌리 추출물에 대한 기본적 독성은 없고, 성장에 미치는 영향은 없는 것으로 사료되었다. 그리고 3주 간격으로 소변으로 배출되는 Ca과 P의함량을 ICP로 분석 한 결과, 10 mg/kg/day농도로 음용한 군에서 유의적으로 감소됨을 확인 할 수 있었고 혈액으로 유리되는 Ca과 P의 함량 또한 섭취군에서 유의적으로 감소되는 것을 확인하였다. 또한 섭취 후 9주째에 양에너지 방사선 골밀도 측정기(dual energy x-ray absorptiometry, DEXA)를 이용하여 척추, 대퇴골, 골반의 골밀도와 골무기질 함량을 측정한 결과, 메탄을 추출물을 음용한 군의 척추 골밀도가 대조군에 비해 유의적으로 높게 나타났으며, 글 무기질 함량 또한 대퇴골과 골반에서 대조군에 비해 유의적으로 높게 나타났다. 따라서 미역취뿌리 메탄을 추출물의 음용이 암컷 흰쥐에서 골밀도 및 골함량에 유의하게 작용하고 또한 골대사 과정에서 유리되는 Ca와 P의 대사과정에 작용하여 유리되는 Ca과 P의 양을 감소시켜 이상의 결과로 미뤄볼 때, 적절한 미역취뿌리 추출물의 투여는 흰쥐의 성장에 대해 부작용이나 독성없이 골밀도와 골무기질 함량을 높였으며 앞으로 조골세포 기능 저하로 인한 골대사 질환에 사용되어 질 수 있을 것이다. To investigate the bioactivities of Solidago virga-aurea var. gigantea Mig. Root (SVR), we studied the effect of a SVR methanol extract on the activity of bone metabolism. Spraque-Dawley three-week-old female rats were randomly assigned to groups as follows : non-supplemented rats and supplemented with SVR at 10, 50, 100 mg/kg bw/day. Every week determined weight gain and food intake, urine and blood examination of mineral content of calcium and phosphorus was performed each at experimental periods of 3 and 9 weeks respectively; bone mineral density and bone mineral content were also assayed. There were no significant differences in body weight or feed efficiency ratio levels. However, the biological value of calcium and phosphorus excretion in the group supplemented with SVR extract decreased significantly more than that in the group not supplemented with SVR extract. Also, spine BMD, femur BMC and pelvis BMC per weight were significantly greater on SVR extract supplemented groups than that of the control group. In conclusion, it might be expected that methanol extract of SVR does not impair the growth of rats and may improve bone metabolism in rats.

Interleukin-10 knockout mouse: a model for studying bone metabolism during intestinal inflammation.

The objective was to compare bone mass (bone mineral content [BMC], bone mineral density [BMD]) and biomechanical strength of femurs and lumbar vertebrae from male and female wild-type (WT) and IL-10 knockout (KO) mice to determine if the IL-10 KO mouse model is appropriate for studying inflammation-associated bone abnormalities and potential interventions. Offspring from IL-10 KO and WT mice (n = 15 to 19 mice/gender per group) were studied until 13 weeks of age. IL-10 KO mice had a higher (P < 0.05) colonic histologic injury score and serum proinflammatory cytokines (IL-6, IL-1beta, TNF-alpha) than WT mice. IL-10 KO mice also experienced bone abnormalities as femur and verterbral BMC and BMD were lower (P < 0.05) compared with WT mice. Moreover, some biomechanical strength parameters such as femur yield load (P = 0.057) and resilience (P < 0.05) and peak load of lumbar vertebra 3 (P < 0.05) were lower than WT mice. Due to differences in body size, males had greater (P < 0.05) femur and vertebral bone mass as well as femur weight, length, yield load, resilience, and peak load than females. A significant interaction (genotype x gender) was only observed for femur resilience in which male WT mice had a greater (P = 0.009) resilience than all other groups. These results demonstrate that IL-10 KO mice develop bone abnormalities that accompany intestinal inflammation and elevated serum proinflammatory cytokines. Thus, the IL-10 KO mouse model may be useful for studying inflammation-associated bone abnormalities and potential therapeutic interventions.

Reproducibility and Side Differences of Mechanical Tests for Determining the Structural Strength of the Proximal Femur

In this experimental study, we evaluated the reproducibility error of mechanical strength tests of the proximal femur when simulating a fall on the trochanter. Based on side differences in femoral failure loads in 55 pairs of femora, we estimated the upper limit of the precision error to be 15% for the side impact test, whereas the intersubject variability was >40%. Mechanical tests are commonly used as the gold standard for determining one of the main functions of bones, that is, to provide mechanical strength. However, it is unknown what magnitude of error is associated with these tests. Here we investigate the precision error and side difference of a side impact test of the proximal femur. BMC was measured using DXA in 54 pairs of femora from donors 79.0 +/- 10.6 years of age. Bones were tested to failure, simulating a fall on the greater trochanter. Failure loads were 3951 +/- 1659N (CV% = 42%) on the right and 3900 +/- 1652N (CV% = 42%) on the left (no significant side difference). The average random difference of femoral BMC was 7 +/- 7% and that of femoral failure loads was 17 +/- 12%. The correlation between BMC and failure load was 79% (r2), but the association between side differences in failure load with those in BMC was only 4%. When confining the analysis to pairs with less than 5% differences in BMC (n = 31), side differences in failure loads were 15 +/- 13%. When correcting failure loads for side differences of BMC, the difference was 16 +/- 15% These results suggest that the upper limit of the precision error for femoral strength tests is approximately 15% in a side impact configuration. Given the large intersubject variability of failure loads, this test provides an efficient tool for determining the structural strength of the proximal femur in a fall.

RESTRICTED FEEDING AND BONE MASS IN AN ANIMAL MODEL OF THE FEMALE ATHLETE TRIAD

Previous work in this laboratory demonstrated that female rats, restricted-fed to persistent anestrus and allowed unlimited access to running wheels, had significantly lower total body and femoral BMC and BMD compared to ad libitum-fed rats. Also, and libitum-fed rats, with unlimited access to running wheels, had significantly greater total body and femoral BMD and BMC compared to sedentary rats. PURPOSE To examine the effects of dietary restriction and exercise on bone mass in female rats. METHODS Twenty-two female Sprague-Dawley rats (age 40 days) were randomly assigned to four groups: ad libitum-fed running, ad libitum-fed sedentary, restricted-fed running, and restricted-fed sedentary. Running rats were individually housed with digitally monitored running wheels. Rats were fed pelleted AIN-G chow. Beginning at 159 days, the restricted-fed rats were subjected to 30% dietary restriction to initiate weight loss and anestrus. After 60+ days in anestrus (day 280), total body and femoral BMD and BMC were measured by dual-energy x-ray absorptiometry. Separate ANOVAs were used to examine the effects of feeding and exercise on BMD and BMC. RESULTS There were significant main effects (p < 0.05) for feeding and exercise on body mass such that ad libitum-fed and running rats had significantly greater body mass compared to restricted-fed and sedentary rats. Prior to normalizing for body mass, restricted-fed and sedentary rats had significantly less femoral BMD than ad libitum-fed and running rats. However, when normalized for body mass, restricted-fed and sedentary rats had significantly greater femoral BMD and BMC compared to ad libitum-fed and running rats. Feeding and exercise explained 65–85% and 21–56% of the variability in bone mass, respectively. CONCLUSION These findings suggest that the bone loss observed in the restricted-fed rats may have been due primarily to weight loss rather than anestrus.