Skeletal and body-composition effects of anorexia nervosa.

Eleven female patients (aged 18-46 y) with anorexia nervosa were measured by use of dual-photon absorptiometry for 1) bone mineral content (BMC, in g) and bone mineral density (BMD, in g/cm2) of the total skeleton and its regions, 2) BMD of the lumbar spine and the proximal femur, and 3) total body soft-tissue composition. The patients weighed 44.4 kg, approximately 15 kg less than normal peers (n = 22). The fat mass (3.35 kg) and content of soft tissue (7.8%) were four and three times lower (p less than 0.001) respectively, than those in normal women (15.1 kg and 26%, respectively). The total skeleton mineral (1921 g) was approximately 25% less than that of young normal women. The BMC as a fraction of the lean tissue mass was approximately 4.9% in the patients and 5.9% in normal women. Total body and femoral BMD averaged only 10% and 13% lower than those of normal women, respectively; however, spinal BMD was particularly reduced (approximately 25%, p less than 0.001).

[Morphological aspects of the mineral phase of the bone]. / Morfologicheskaia kharakteristika mineral'noi fazy kosti.

By means of light, scanning and transmission electron microscopy structure of the mineral phase of human compact bone have been studied. Mechanical properties of deorganified bone samples have been determined. High compressive strength may be in connection with interactions of plate-like mineral particles at the level of hydrate shell of the bone mineral crystallites.

Dietary calcium, sex hormones, and bone mineral density in men.

OBJECTIVE: To evaluate the factors that determine bone mineral density at axial and appendicular sites in normal men. DESIGN: Measurement of bone mineral density of the radius by single photon absorptiometry and of the lumbar spine and hip by dual photon absorptiometry to assess their relation with various determinants of bone mineral density. Dietary calcium was assessed from a questionnaire validated against a four day dietary record. SETTING: Local community, Sydney, Australia. PATIENTS: 48 Men (aged 21-79, median 44) recruited from the local community including 35 male cotwins of twin pairs of differing sex recruited from the Australian National Health and Medical Research Council twin registry for epidemiological studies on determinants of bone mineral density. MAIN OUTCOME MEASURES: Bone mineral density of the axial and appendicular skeleton and its relation to age, anthropometric features, dietary calcium intake, and serum sex hormone concentrations. RESULTS: Dietary calcium intake (g/day) was a significant predictor of bone mineral density of axial bones, explaining 24% and 42% of the variance at the lumbar spine and femoral neck respectively. This effect was independent of weight. In contrast with the axial skeleton, bone mineral density at each forearm site was predicted by weight and an index of free testosterone but not by dietary calcium intake. CONCLUSIONS: Dietary calcium intake has a role in the determination or maintenance, or both, of the axial but not the appendicular skeleton in adult men.

Distribution of fluoride concentration in the rat's bone.

The present study was undertaken to determine the fluoride distribution profile in the rat femur. Male Wistar rats were divided into four groups and given water containing 0, 25, 50, and 100 ppm of fluoride, respectively, for 10 weeks. The fluoride distribution from the periosteum to the endosteum was determined in each specimen after sampling using the abrasive microsampling technique. In the outer circumferential lamellae, the concentration of fluoride was relatively high in the periosteal layer and then decreased gradually towards its interior. In the haversian and interstitial lamellae, it was lower and roughly constant through the tissue. In the inner circumferential lamellae, it rose again to reach the highest level towards the endosteal surface. Fluoride concentration throughout the cortex increased significantly with increasing intake of fluoride. These increases were especially marked at periosteal and endosteal surfaces.

Effects of age and sex on bone density at the hip and spine in a normal Caucasian New Zealand population.

We have studied a normal adult caucasian population (462 females, 264 males age range 20-84) using dual photon absorptiometry to establish patterns of bone reduction at the spine and hip. Subjects were either randomly selected from the electoral roll or volunteers. Bone mineral density reduction at the lumbar spine in females appeared to increase at 40 years and was sustained until 60 years. In males bone mineral density at the spine was preserved. The density at the hip in females decreased throughout adult life beginning before the menopause. In males bone density was preserved at the femoral neck and trochanteric region but not at Wards triangle where reduction occurred throughout life. When compared with other normal populations there was higher bone mineral density at the spine in postmenopausal New Zealand females but no significant difference at the hip.

Nondestructive measurement of bone mineral in femurs from ovariectomized rats.

One hundred ninety-eight rats were ovariectomized (OX) or sham-ovariectomized (shOX) at 100 days of age. Groups were killed at 35, 70, 100, 125, 180, 270, 360, and 540 days postsurgery. Bone mineral content (BMC) of the right femur was assayed on a dual photon absorptiometer (DPA) optimized for human spine and whole body measurements. Three regions were studied: the distal measuring 0.8 cm, the proximal measuring 0.88 cm, and the diaphysis, the remainder. The DPA technique accurately showed the ash content (r = 0.96), with a precision error of 3-5%. Whole femoral BMC was 4.3-11.1% lower in OX than shOX rats, with significant differences from 35-180 days. By 35 days, distal femoral BMC declined 6% in OX rats and rose 12% in shOX rats. Distal femoral BMC was 11.3-17.5% lower in OX than shOX rats, with significant differences at all times except 540 days. Femoral diaphyseal BMC of OX and shOX rats did not differ at any time. The relative distal femoral osteopenia which appeared by 35 days in OX rats did not worsen during the next 17 months. A DPA suited for human BMC studies is also accurate for BMC determination in bones with 250-500 mg of mineral. It is less precise for this purpose than dedicated instruments using single photon absorptiometry. However, enough precision exists to monitor the development of relative osteopenia in OX rats. Osteopenia in OX rats is confined to a region containing appreciable cancellous bone. Its self-limiting nature suggests the existence of an estrogen-dependent quantum of cancellous bone in female rats. The adult rat model is accurate for cancellous bone of the adult human, but inaccurate for cortical bone.

Regional distribution of mineral and matrix in the femurs of rats flown on Cosmos 1887 biosatellite.

We combined biochemical measurements with novel techniques for image analysis in the rat femur to characterize the location and nature of the defect in mineralization known to occur in growing animals after spaceflight. Concentrations of mineral and osteocalcin were low in the distal half of the diaphysis and concentrations of collagen were low with evidence of increased synthesis in the proximal half of the diaphysis of the flight bones. X-ray microtomography provided semiquantitative data in computer-generated sections of whole wet bone that indicated a longitudinal gradient of decreasing mineralization toward the distal diaphysis, similar to the chemistry results. Analysis of embedded sections by backscattered electrons in a scanning electron microscope revealed distinct patterns of mineral distribution in the proximal, central, and distal regions of the diaphysis and also showed a net reduction in mineral levels toward the distal shaft. Increases in mineral density to higher fractions in controls were less in the flight bones at all three levels, with the most distal cross-sectional area most affected. The combined results from these novel techniques identified the areas of femoral diaphysis most vulnerable to the mineralization defect associated with spaceflight and/or the stress of landing.

Effect of direct-current stimulation on the growth plate. In vivo study with rabbits.

Electrical stimulation of 8 microA direct current was applied to the femoral distal growth plate of young rabbits for periods of 1, 2, and 3 weeks to examine the effect on bone growth. The results were analyzed using X-ray measurement, histological observation including tetracycline labeling, and glycosaminoglycans analysis. No obvious differences between the stimulated side and the control side were observed in the morphological and biochemical studies, but characteristic thickening of the growth plate caused by the accumulation of hypertrophic cells was found in the group stimulated for 2 weeks. Electricity affects the cell behavior of the growth plate, but it is necessary to find more appropriate conditions to stimulate obvious bone growth.

Effects of maternal caffeine with zinc intake during gestation and lactation on bone development in newborn rats.

On day 9 of gestation, pregnant dams were randomly divided into 3 groups. Dams of group 1 were fed a 20% protein diet as a control. Dams of group 2 were fed a 20% protein diet supplemented with caffeine. Dams of group 3 were fed a 20% protein diet supplemented with caffeine and zinc. The amount of caffeine added to the maternal diet was 2 mg/100 g body weight; the amount of zinc was 0.6 g/kg of diet. At birth, pups were mixed within each group, and 8 randomly selected pups from each group were assigned to each dam of the respective group and were continuously fed the same diet. On day 15, the pups were killed and cranial bones, mandibles and femurs removed. The bones were measured, and the mineral content of the mandibles and femurs was determined. Although there were no differences in the dimensions of the cranial bones among the groups, the measurements and mineral content of the mandibles and femurs were consistently affected by the caffeine in the diet. On the other hand, supplementation of the caffeine-added diets with zinc led to greatly improved bone development, reaching values up to or beyond control levels. Thus zinc supplementation of a caffeine diet given to the dams during gestation and lactation can favourably influence the otherwise impaired bone development of their offspring.

Buserelin-mediated osteoporosis: effects of restoring estrogen on bone resorption and whole body calcium content in the rat.

In the rat, prolonged administration of the luteinizing, hormone-releasing hormone agonist buserelin (25 micrograms/kg body wt/day s.c.) lowers blood estradiol, raises bone resorption, and induces osteopenia. The present study was undertaken to determine whether withdrawal of buserelin normalizes blood estradiol, slows bone resorption, and corrects buserelin-mediated osteopenia. Four groups of female rats with 45Ca-labeled bones were studied: group 1A received 0.2 ml saline s.c. daily for 4 weeks; group 2A received 0.2 ml buserelin s.c. daily for 4 weeks; group 1B received 0.2 ml saline s.c. daily for 8 weeks; group 2B received 0.2 ml buserelin s.c. daily for 4 weeks followed by 0.2 ml saline s.c. daily for 4 weeks. Bone resorption was monitored by measuring urinary 45Ca and hydroxyproline. The rats in groups 1A and 2A were killed after 4 weeks and those in groups 1B and 2B after 8 weeks. The mineral contents of the femoral bones and the whole skeletons were measured. Buserelin lowered blood estradiol, elevated urinary 45Ca and urinary hydroxyproline, and lowered femur and total body calcium and 45Ca in group 2A vs. 1A (P less than 0.05). By contrast all these measurements became similar in groups 2B and 1B. Thus, osteopenia generated by a 4-week period of buserelin-mediated hypo-estrogenism is reversible by withdrawing buserelin for 4 weeks. Consequently, buserelin administration and withdrawal may be used to study effects of inducing and reversing estrogen-deficiency bone loss in the rat.

Effects of starch, sucrose, fructose and glucose on chromium absorption and tissue concentrations in obese and lean mice.

Forty-eight male genetically obese (OB) mice (C57BL/6J-OB) and 48 lean male littermates were randomly assigned within main plots (OB or lean) to one of eight diets. Diets were low chromium or supplemented with 1 mg chromium as CrCl3 per kg. Starch, sucrose, fructose or glucose comprised 50% of the diet, which met AIN recommendations except for chromium. Experimental diets and deionized water were available ad libitum for 26 d. Mice were fasted 10 h and were intubated 2 h before killing with 15 microCi of 51CrCl3 in a 25% carbohydrate solution (2 mg carbohydrate/g body wt) of either starch, sucrose, glucose or fructose corresponding to the diet previously fed. 51Cr concentrations were significantly higher in the blood, liver, spleen, epididymal fat pad, testes and femur of animals given their carbohydrate load as starch than in animals fed sucrose, fructose or glucose. Carbohydrate had a significant effect on chromium concentrations of testes, spleen, kidney and liver with values generally being higher with the starch diet. Chromium supplementation increased bone and kidney chromium concentrations and heart and muscle glycogen. These data indicate that the source of carbohydrate can alter chromium absorption and retention.

Bone disorder in cardiomyopathic hamsters.

Bones of cardiomyopathic hamsters (UM-X7.1 Syrian hamsters), at 5, 10 and 20 weeks of age, were compared chemically and histomorphologically with those of normal Syrian hamsters. Femurs of UM-X7.1 hamsters were significantly shorter than those of normal hamsters, and the mean dry weight, mean volume, mean ash weight per unit bone volume and mean ash as a percentage of dry weight of femurs were all significantly less in UM-X7.1 hamsters. The bone disorder preceded the myocardial calcium precipitation and myocardial hypertrophy in the cardiomyopathic hamsters. In addition, the percentage of cortical area measured on the cross-section of tibia and the appositional rate of bone minerals, determined by a tetracycline labelling technique, were also lower in the UM-X7.1 hamsters. These findings suggest that the bone disorder was associated with decreased bone formation in the UM-X7.1 Syrian hamsters.

1,25-Dihydroxyvitamin D3 prevents the decrease of bone mineral appositional rate in rats with inflammation-mediated osteopenia (IMO).

We have studied the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on bone mass and bone mineral appositional rate in intact rats and rats with inflammation-mediated osteopenia (IMO), where osteoblast number and mineral appositional rate are decreased. 1,25(OH)2D3 prevents IMO-specific bone loss when given in a daily dose of 25 ng per rat, but does not when given in higher doses. The hormone was effective, when given over the complete duration of the experiment (21 days), but not when given over shorter time periods (7 and 14 days, respectively). 1,25(OH)2D3 prevents IMO-dependent reduction in mineral appositional rate and leads to an only moderate increase in intact rats. We conclude, that 1,25(OH)2D3 is more effective in stimulating mineral appositional rate in rats with IMO where mineral apposition is impaired.

The effect of age and menopause on bone mineral density of the proximal femur.

Although the menopause has been associated with increased bone loss at several skeletal sites, it has not previously been noted in the hip, yet estrogen therapy has been reported to reduce the incidence of hip fractures. We investigated the effect of age and menopause on bone loss in the proximal femur by measuring bone mineral density (BMD) of the femoral neck, Ward's triangle, and trochanter by dual-photon absorptiometry in 263 normal women aged 20-84. Multiple regression analyses revealed a significant decrease in BMD of the femoral neck and Ward's triangle with age in both pre- and postmenopausal women (p less than 0.001). In the trochanter the decrease with age was significant only in postmenopausal women (p less than 0.001). Further analysis revealed that BMD decreased faster at all sites in the early postmenopausal years. During the first 6 years postmenopause, the decrease in BMD of the femoral neck and trochanter was 3-10 times higher than the change in the decade prior to menopause. About 20% of the lifetime femoral neck loss and 30% of the trochanteric loss occurred in the early postmenopausal period. It is concluded that both age and menopause are major determinants of BMD in the proximal femur. These findings could explain why estrogen therapy has been reported to prevent hip fracture. The rapid early postmenopausal loss in BMD of the proximal femur demonstrates the importance of starting estrogen replacement therapy immediately after menopause for maximum effect.

Quantitative computed tomographic evaluation of femoral bone mineral content in renal osteodystrophy compared with radial photon absorptiometry.

The computed tomography (CT) numbers of cortical bone at the level of 20 cm (CT20) and of spongiosa in the lateral condyle at the level of 2 cm (CT02) from the distal end of the femur were obtained by a quantitative CT method and compared with the bone mineral density of mostly cortical bone within the radius (BMD) by photon absorptiometry. The study included 47 patients with chronic renal failure not dialyzed or induced to regular hemodialysis within 4 weeks of the study (group 1), 28 patients on regular hemodialysis for more than one month (group 2), and ten healthy volunteers (group 3). The measures of bone mineral content (BMC), namely CT20, CT02, and BMD, were compared in terms of their abilities to distinguish members in the various groups. For group 1 and group 3, the greatest variation in BMC was in the difference in CT02, which was primarily a measurement of the BMC of spongiosa. For groups 1 and 2, the greatest variation was in the difference in BMD, which was primarily a measurement of the BMC of cortex. The reproducibility of CT02 was estimated as almost equal to the difference in CT02 values at intervals of 10 months' duration of hemodialysis. The results indicated that CT02 was a useful measurement for evaluating the progress in the early stage of the renal osteodystrophy, and it is recommended that the bone mineral measurement with this QCT method should be performed once or twice a year.

A comparison of rat femoral, sternebral and lumbar vertebral bone marrow fat content by subjective assessment and image analysis of histological sections.

A subjective assessment of the amount of fat within the available marrow space was made from histological sections of the femur, sternebrae and lumbar vertebrae in rats. The sternebrae and vertebrae showed considerably less variability than the femur. Comparison between subjective assessment and image analysis of femoral bone marrow fat showed that there is no great advantage to be gained from using the latter technique. It was concluded that evaluation of sternebral and vertebral bone marrow results in a more accurate assessment of fat content.

Orientation of bone mineral and its role in the anisotropic mechanical properties of bone--transverse anisotropy.

An orientation of hydroxyapatite (HAP) crystals in bovine femur mineral was investigated by means of X-ray pole figure analysis (XPFA). It was found that the c-axis of HAP generally orients parallel to the longitudinal axis of bone (bone axis) and a significant amount of c-axis was oriented in other directions, in particular, perpendicular to the bone axis. Comparing these results with those of the small angle X-ray scattering (SAXS) investigation by Matsushima et al. (Jap. J. appl. Phys. 21, 186-189, 1982) at least two types of morphology of bone mineral were found; rod like bone mineral having the c-axis of HAP crystal parallel to the longitudinal axis of the rod and that having the c-axis not parallel, in a particular case, perpendicular to its longitudinal axis. Transverse anisotropy in mechanical properties of bone was reproduced by the estimation of Young's moduli by using the structural results mainly from XPFA. It is concluded that the anisotropy in mechanical properties of bone is well explained by taking account of the non-longitudinal (off-bone) axial distribution of orientation of bone mineral.

Collagen and non-collagenous proteins in different mineralization stages of human femur.

Mineralized tissues exhibit varying degrees of mineralization in different areas within the same bone. Using the technique of density gradient fractionation, bone powder from the diaphysis of human femur has been separated in different fractions corresponding to the degree of mineralization. Isolated bone fractions were analysed for their content in collagen and non-collagenous proteins. The results showed marked differences between compact and spongy bones, this latter containing higher proportions of little mineralized bone particles than the former (p less than 0.01). The ethylenediaminetetra-acetic acid (EDTA) extractability and the bone matrix size decreased relative to the decrease in specific gravity of bone particles. Among the matrix components of different fractions, sialoprotein consistently increased with the increase in specific gravity while proteoglycan decreased in reverse manner to the increase in collagen. However, in the most mineralized fraction (specific gravity: 2.33 g/cm3), the proteoglycan amount increased while collagen decreased. In conclusion, this study of bone maturation in human femur confirms the suitability of the technique of density gradient fractionation in the studies of bone matrix-mineral interactions. Apart from the fraction with the highest specific gravity, the analytical results obtained in fractions are similar to those observed in age-related bone changes, suggesting that the increase in mineralization degree of bone particles may be related to their age.

Bone mineral density of the spine and proximal femur in normal and osteoporotic subjects in Japan.

Bone mineral density (BMD) of the spine and proximal femur in Japanese men and women was investigated with dual photon absorptiometry, using gadolinium-153. Peak bone mass of the spine (L2-4) was 1.20 g/cm2 in women which was lower than that of men by 4.7%, whereas BMD of the femoral neck was 0.91 g/cm2 in women and lower than in men by 13.3%. Bone loss was faster in postmenopausal women than in men of the corresponding age, and the regressions of BMD on age were 6.7-times higher at L2-4 and 5.1-times higher at the femoral neck than in men. Such rates of loss became slower both in the lumbar spine and proximal femur in women after 70 years of age, but the density at the proximal femur kept decreasing in men after 70 years of age. Fracture thresholds of each region were evaluated at the 90th percentile for BMD of L2-4 in patients with vertebral crush fractures and for BMD of the proximal femur in patients with hip fractures. The fracture threshold was 0.97 g/cm2 at the spine and 0.67 g/cm2 at the femoral neck in women. BMD values at the spine and proximal femur in normal Japanese men and women appear to be lower than those in white American control population.

Femoral bone density in young male adults with stress fractures.

Femoral bone mineral density (BMD) was measured by dualphoton absorptiometry in 41 young military recruits who had one or several stress fractures, during their physical training program. These fractures involved the following locations: Femur (neck: n = 10, diaphysis: n = 2), calcaneus (n = 10), tibia (n = 8), fibula (n = 3), metatarsus (n = 8). The stress fracture group generally had a lower bone density than that of a control group, consisting of 48 young military recruits matched for age, height and weight. However, the BMD was significantly lower (-10%) in patients with femoral and calcaneal locations, but it did not differ for other locations. To determine the possible effect of this intense physical activity on bone mineral mass, bone mass was measured again in 35 subjects from the control group at the end of their training. The BMD remained stable or increased in 28 subjects, but decreased significantly (greater than 2%) in 7 subjects, demonstrating the individual variability in the adaptation of bone to this stress. Our results suggest that lowered bone mass could be a factor that encourages the development of stress fractures (femoral and calcaneal) in young subjects submitted to intense physical activity to which they are not accustomed.