Comparison of Microcomputed Tomographic and Microradiographic Measurements of Cortical Bone Porosity

Cortical bone is perforated by a network of canals that have a significant impact upon its material properties. Microcomputed tomography offers the possibility of noninvasively visualizing and quantifying cortical pores in both two and three dimensions. Establishing how two-dimensional (2D) microcomputed tomographic (CT) analysis compares with conventional methods for analyzing cortical porosity is an important prerequisite for the wider adoption of this technique and the development of three-dimensional (3D) analysis. Therefore, we compared porosity-related parameters from 2D microcomputed tomographic images with those from matching microradiographic sections. Samples from five human femora were scanned at a 10-m resolution and then sequentially sectioned and microradiographed. An average of eight image pairs were produced from each femur (total, n = 41). The repeatability and comparability of the two techniques was assessed for three parameters; cortical porosity (%), mean pore area (m²), and pore density (pores/mm²). For repeatability, no significant difference (P > 0.05) was found between the two methods for cortical porosity and mean pore area; however, pore density differed significantly (P < 0.001). For comparability, the bias (± error) between the methods was found to be 0.51% (±0.31%) for cortical porosity and –155 m² (±293 m²) for mean pore area. The bias for pore density was dependent upon measurement size with microcomputed tomographic images having 14% (±9.3%) fewer pores per millimeter squared. The qualitative and quantitative similarities between the two techniques demonstrated the utility of 2D microcomputed tomographic for cortical porosity analysis. However, the relatively poor results for pore density revealed that a higher resolution (<10 m) is needed to consistently visualize all cortical pores in human bone.     

Correlation between Hydroxyapatite Crystallite Orientation and Ultrasonic Wave Velocities in Bovine Cortical Bone

The mineral component of bone is mainly composed of calcium phosphate, constituting 70% of total bone mass almost entirely in the form of hydroxyapatite (HAp) crystals. HAp crystals have a hexagonal system and uniaxial elastic anisotropy. The objective of this study was to investigate the effect of HAp crystallite preference on macroscopic elasticity. Ultrasonic longitudinal wave velocity and the orientation of HAp crystallites in bovine cortical bone are discussed, considering microstructure, density, and bone mineral density (BMD). Eighty cube samples of cortical bone were made from two bovine femurs. The orientation of HAp crystallites was evaluated by integrated intensity ratio of (0002) peak using an X-ray diffractometer. Ultrasonic longitudinal wave velocity was investigated with a conventional pulse system. The intensity ratio of HAp crystallites and velocity were measured in three orthogonal directions; most HAp crystallites aligned in the axial direction of the femurs. Our results demonstrate a linear correlation between velocity and intensity ratio in the axial direction. Significant correlation between velocity and BMD values was observed; however, the correlation disappeared if we focused on the identical type of microstructure. In conclusion, differences in microstructure type have an impact on density and BMD, which clearly affects the velocity. In addition, at the nanoscopic level, HAp crystallites aligned in the axial direction also affected the velocity and anisotropy.     

A Delay in Pubertal Onset Affects the Covariation of Body Weight,Estradiol, and Bone Size

The skeletal system functions as a locomotive organ and a mineral reservoir and combinations of genetic and environmental factors affect the skeletal system. Although delayed puberty is associated with compromised bone mass, suppression of estrogen should be beneficial to cortical strength. The purpose was to employ path analysis to study bone strength and delayed puberty. Forty-five female rats were randomly assigned to a control group (n = 15) and an experimental group (n = 30) that received injections of gonadotropin releasing hormone antagonist (GnRH-a). Causal models were constructed by specifying directed paths between bone traits. The first model tested the hypothesis that the functional relationships between bone traits and body weight were altered by a delay in pubertal onset. GnRH-a injections during puberty altered the covariation between body weight and bone size. The second model was constructed to test the hypothesis that variability in stiffness was causally related to variability in body weight. The model also tested the relationship between the periosteal and endocortical surfaces and their relationship to stiffness. There was no change in the relationship between the surfaces in the GnRH-a group. The third model determined the effect of estradiol on both total area and relative cortical area in both groups. The relationship between periosteal surface and serum estradiol levels was only significant during estrogen suppression. These data suggest that increases in body weight during or prior to puberty may not be protective of bone strength.     

Five Years of Treatment with Risedronate and its Effects on Bone Safety in Women with Postmenopausal Osteoporosis

We have recently reported that risedronate preserves normal bone formation and decreases bone remodeling in women with postmenopausal osteoporosis after 3 years of treatment. We report now the results of a 2-year extension study. The primary objective of this study was to determine the effect of 5 years of risedronate treatment (5 mg daily) on bone quality and bone remodeling based on paired transiliac bone biopsies. There were additional measurements that included bone turnover markers and bone mineral density (BMD). Histologic evaluation of biopsy sections (placebo, n = 21; risedronate, n = 27) yielded no pathologic findings after 5 years in either treatment group. Histomorphometric assessment of paired biopsy specimens after 5 years (placebo, n =12; risedronate, n = 13) found no statistically significant differences between treatment groups in structural or resorption parameters. There was a significant reduction in osteoid (–27%) and mineralizing surfaces (–49%) from baseline values in the risedronate group that were also significantly different from placebo at 5 years. Similarly, activation frequency decreased significantly (–77%) in the risedronate group, although it was not significantly different from placebo at 5 years (0.09 vs. 0.21, respectively). Double tetracycline labels were identified in all biopsy specimens indicating continuous bone turnover. After 5 years of risedronate treatment, serum bone-specific alkaline phosphatase (bone ALP) and N-telopeptide (NTX) decreased significantly from baseline by 33.3% and 47.5%, respectively. In the placebo group, bone ALP decreased by 3.9% (P = NS), whereas NTX decreased by 27.0% (P < 0.005). Lumbar spine BMD increased significantly in the risedronate group (9.2%), whereas no significant change was seen in the placebo group (–0.26%). Risedronate was overall well tolerated; during the 2-year study extension nonvertebral fractures occurred in 7 patients in placebo and 2 patients in risedronate groups. The findings from this study are consistent with the antiremodeling effect of risedronate and support long-term bone safety and antifracture efficacy of risedronate treatment.This work was supported by grants from Procter & Gamble Pharmaceuticals, Inc., Mason, Ohio, and Aventis Pharmaceuticals, Bridgewater, New Jersey.     

3D Analysis of Cortical and Trabecular Bone From Hip DXA:Precision and Trend Assessment Interval in PostmenopausalWomen

The 3D distribution of the cortical and trabecular bone mass is a critical component in determining the resistance of a bone to fracture that is not assessed in standard dual-energy X-ray absorptiometry (DXA) exams. In this work, we assessed in vivo short-term precision of measurements provided by 3D modeling techniques from DXA scans and trend assessment intervals (TAIs) in postmenopausal women. Subjects included to study precision errors were scanned twice, with repositioning for duplicate hip scans, using either a Lunar iDXA scanner (GE Healthcare, Madison, WI) or a Discovery W scanner (Hologic, Inc., Waltham, MA). Postmenopausal women having baseline and 18-mo follow-up visit were scanned using a Lunar iDXA device to assess TAIs. TAIs indicate what time intervals are required to allow accurate assessment of response to treatment or progression of disease. The 3D-SHAPER software (Galgo Medical, Barcelona, Spain) was used to derive 3D measurements from hip DXA scans. Least significant changes were 10.39 and 8.72 mg/cm³ for integral volumetric bone mineral density (BMD), 9.64 and 9.59 mg/cm³ for trabecular volumetric BMD, and 6.25 and 5.99 mg/cm² for cortical surface BMD, using the Lunar iDXA and Discovery W scanners, respectively. TAIs in postmenopausal women were 2.9 yr (integral volumetric BMD), 2.6 yr (trabecular volumetric BMD), and 3.5 yr (cortical surface BMD), using the Lunar iDXA scanner. As a comparison, TAIs for areal BMD were 2.8 yr at neck and 2.7 yr at total femur. Least significant changes of measurements provided by 3D modeling techniques from DXA were assessed. TAIs in postmenopausal women were similar to those measured for areal BMD measurements. DXA-derived 3D measurements could potentially provide additional indicators to improve patient monitoring in clinical practices.     

The Effect of Season and Vitamin D Supplementation on Bone Mineral Density in Healthy Women: A Double-Masked Crossover Study

Vitamin D status is known to be an important determinant of bone mineral density (BMD). There is a significant seasonal variation in serum vitamin D, and some studies have reported an associated seasonal variation in BMD. The present study was devised to investigate whether a seasonal variation in BMD could be detected in healthy normal subjects, along with associated variations in serum parathyroid hormone (PTH), intestinal calcium absorption and biochemical markers of bone turnover. A second aim was to investigate whether, if such variations were identified, they could be suppressed by vitamin D supplementation. The subjects were 70 healthy female volunteers (mean age 47.2 years, range 24–70 years) recruited into a double-masked crossover study and followed over 2 years. During the first year 35 subjects received a daily oral supplement containing 800 IU (20 mg) cholecalciferol (group 1) and 35 subjects received a placebo preparation (group 2). During the second year the treatment each group received was reversed. Lumbar spine (L1–L4), left proximal femur and total body BMD were measured by DXA at 3-month intervals. Serum 25-hydroxyvitamin D (25-OHD), serum PTH, bone markers (bone-specific ALP (BSAP) and urinary crosslinks (DYPD/creatinine)) and calcium absorption were also measured at each visit. Cholecalciferol treatment increased serum 25-OHD by 25.4 nmol/l (p <0.001), while a reciprocal decrease in serum PTH of 6.6 ng/l (p = 0.011) was seen in subjects in the lowest quartile of baseline serum 25-OHD. The treatment had no significant effect on spine, femur or total body BMD, calcium absorption or bone markers. When Fourier analysis was used to analyze the data for seasonal effect (defined as twice the amplitude of the 1-year period variation) a highly significant effect for 25-OHD of 18 nmol/l (p <0.001) was found. However, no effect was found for BMD, PTH, calcium absorption or bone markers. The analysis set a 95% confidence limit to the seasonal effect of less than 0.6% for spine, total hip and total body BMD. It was concluded that in the population of healthy women studied there was no evidence of seasonal variation in spine, femur or total body BMD, serum PTH, calcium absorption or bone markers. Vitamin D supplementation was found to have no effect on BMD. Received: 7 July 2000 / Accepted: 14 November 2000     

Administration of a Glucocorticoid With Depot Effect Counteracts the Stimulating Effect of Growth Hormone on Cancellous and Cortical Bone of the Vertebral Body in Rats

Our earlier studies have shown that growth hormone administration could not counteract decreased longitudinal growth and cortical osteopenia of rat femora induced by a glucocorticoid with depot effect. In the present study we examined the effects of glucocorticoid on vertebral bone as well as the effect of growth hormone on vertebral bone in young growing animals also given glucocorticoid injections. Five groups of female rats (3 1/2 months) were treated for 80 days as follows: (1) saline, (2) prednisolone: Delcortol 5 mg/kg/day, (3) growth hormone: 5 mg/kg/day, (4) prednisolone and growth hormone, (5) food restriction. Vertebral dimensions, histomorphometry, and mechanical competence of the vertebral bone were examined. Growth hormone administration increased body weight, vertebral height, cross-sectional area, and volume. The compressive strength of the L₄-corpus cylinder was also increased due to an increase in cancellous bone volume and an increase in the area of cortical bone surrounding the vertebral body. Glucocorticoid administration decreased body weight, height, and volume of the intact vertebrae. Histological examination revealed that glucocorticoid administration decreased the area of cortical bone surrounding the vertebral body but had no effect on the cancellous bone volume. No effect of glucocorticoid administration on mechanical strength of the L₄ corpus cylinder could be detected. In agreement with our findings in cortical bone, we found no effect of growth hormone on vertebral bone when given to animals also receiving glucocorticoid injections. Growth hormone increases longitudinal growth, cortical and cancellous bone mass, and mechanical competence of the vertebral body. Glucocorticoid administration decreases longitudinal growth of the vertebrae and cortical bone mass without affecting cancellous bone mass of the vertebral body. Despite this, administration of a glucocorticoid with depot effect totally inhibits the effect of growth hormone on vertebral bone. Received: 12 March 1997 / Accepted: 14 November 1997     

Effect of 1α-Hydroxyvitamin D3 on Cancellous Bone Matrix: An Experimental Study on Adult Rats

Two groups of adult male rats were treated perorally for 6 weeks with 0.1 μg and 1.0 μg of 1a-hydroxyvitamin D₃ (la-OH-D₃), respectively. The effect of the treatment on cancellous bone matrix was studied by chemical analysis and morphometric measurements. The effect of the 1.0 μg dose on the inorganic composition, and on the calcification of the cancellous bone matrix, was significantly more pronounced, decreasing the amount of glycosaminoglycans. The lower dose level, 0.1 μg of la-OH-D₃, increased the collagen metabolism, whereas the higher dose level did not. The amount of cancellous bone determined morphometrically increased significantly during treatment with both dose levels. 1a-OH-D₃, converted in the organism to the hormonal form 1.25 (OH)₂D₃, induces new bone formation, probably by direct influence on the cancellous bone tissue itself.     

Prophylactic Effects of 1,24,25-Trihydroxyvitamin D3 on Ovariectomy-Induced Cancellous Bone Loss in the Rat

Vitamin D metabolites can prevent estrogen depletion-induced bone loss in ovariectomized (OVX) rats. In this study, we investigated the bone-sparing effects of oral 1α,24R,25-trihydroxyvitamin D₃ (1,24,25(OH)₃D₃) in a wide dose range in aged OVX rats. Fifty-three female Fischer-344 rats (6 months old, 170 g BW) were either ovariectomized or sham-operated (SHAM). Eight rats served as baseline controls. Groups of OVX rats (n= 7–8 each) received vehicle alone or graded oral doses of 1,24,25(OH)₃D₃ (0.05, 0.1, 0.2, and 0.3 μg/kg BW/day), starting five days after surgery. Urine and blood samples were collected one, two, three, and four months after surgery. Serum samples were analyzed for total calcium and alkaline phosphatase. Calcium, hydroxyproline, and collagen crosslinks (HPLC) were determined in urine. After fluorochrome double labeling, the rats were sacrificed four months postsurgery and the first lumbar vertebrae and the proximal tibiae were processed undecalcified for bone histomorphometry. Ovariectomy induced a 28% and a 69% reduction in vertebral and tibial cancellous bone area, respectively. Osteopenia in OVX rats was associated with increased histomorphometric and biochemical indices of bone turnover. The administration of 1,24,25(OH)₃D₃ to OVX rats dose-dependently increased vertebral and tibial cancellous bone mass, serum calcium, and urinary calcium excretion, and reduced histomorphometric and biochemical indices of bone resorption. 1,24,25(OH)₃D₃ at doses of 0.2 and 0.3 μg/kg/day produced strong anabolic effects, especially on vertebral cancellous bone in OVX rats, and increased mineral apposition rate and wall width of completed remodeling units relative to vehicle-treated OVX rats. Even at high doses, 1,24,25(OH)₃D₃ did not impair bone mineralization. We conclude that oral administration of 1,24,25(OH)₃D₃ can effectively prevent estrogen depletion-induced cancellous bone osteopenia in the aged OVX rat model. The therapeutic window for 1,24,25(OH)₃D₃ in OVX rats, however, is also narrow, comparable to that for calcitriol. Received: 29 March 1996 / Accepted: 23 September 1996     

The Effect of Vitamin K and D Supplementation on Ovariectomy-Induced Bone Loss

This study was designed to assess the effect of vitamin K and D supplementation on ovariectomy-induced bone loss. Female Sprague-Dawley rats aged 8–9 months were ovariectomized (OVX) or sham operated and divided into five experimental groups: (1) ovariectomy (OVX), (2) OVX plus vitamin K supplementation, (3) OVX plus vitamin D supplementation, (4) OVX plus vitamin K and vitamin D supplementation, and (5) sham operation. The trabecular bone area was estimated by bone histomorphometry by microradiography and histological examination. Bone loss in OVX plus vitamin K and vitamin D group was significantly reduced at both 7 and 14 weeks compared with the OVX group. No significant bone loss in OVX plus vitamin K or OVX plus vitamin D groups was found. A similar effect of vitamin K and D supplementation on ovariectomy-induced bone loss was recognized in histological examination. Our findings indicate that vitamins K and D may have a synergistic effect on reducing bone loss. This is valuable information for the treatment of bone loss in postmenopausal women with osteoporosis. Received: 1 September 1998 / Accepted: 10 January 1999     

Compartmental Bone Morphometry in the Mouse Femur: Reproducibility and Resolution Dependence of Microtomographic Measurements

Microcomputed tomography (μCT) is widely used for nondestructive bone phenotyping in small animals, especially in the mouse. Here, we investigated the reproducibility and resolution dependence of μCT analysis of microstructural parameters in three different compartments in the mouse femur. Reproducibility was assessed with respect to precision error (PE_%CV) and intraclass correlation coefficient (ICC). We examined 14 left femurs isolated postmortem from two strains of mice (seven per group). Measurements and analyses were repeated five times on different days. In a second step, analysis was repeated again five times for a single measurement. Resolution dependence was assessed by high-resolution measurements (10 μm) in one strain and subsequent image degrading. Reproducibility was better in full bone compartment and in cortical bone compartment in the diaphysis (PE_%CV = 0.06–2.16%) than in trabecular compartment in the distal metaphysis (PE_%CV = 0.59–5.24%). Nevertheless, ICC (0.92–1.00) showed a very high reliability of the assessed parameters in all regions, indicating very small variances within repeated measurements compared to the population variances. Morphometric indices computed from lower- and higher-resolution images displayed in general only weak dependence and were highly correlated with each other (R² = 0.91–0.99). The results show that parameters in the full and cortical compartments were very reproducible, whereas precision in the trabecular compartment was somewhat lower. Nevertheless, all compartmental analysis methods were very robust, as shown by the high ICC values, demonstrating high suitability for application in inbred strains, where highest precision is needed due to small population variances.     

A 3-Year Longitudinal Study of the Effect of Physical Activity on the Accrual of Bone Mineral Density in Healthy Adolescent Males

It has previously been suggested that physical activity predominantly influences the accumulation of bone density before puberty. The purpose of the present study was to examine the effect of physical activity on the accumulation of bone mass in male athletes between 16 and 19 years of age. The cohort studied consisted of 12 badminton players (aged 16.1 ± 0.5), 20 ice hockey players (aged 16.1 ± 0.5), and 24 age-matched controls (aged 16.1 ± 0.6). The bone mineral density (BMD, g/cm²) of the total body, spine, dominant and nondominant humerus, head and femoral neck was measured twice with a 3-year interval by dual energy X-ray absorptiometry (DXA). In addition, at the femoral neck, volumetric bone mineral density (vBMD, mg/cm³) was estimated. At baseline, the athletes as a whole group had significantly higher BMD at the total body (P = 0.03), dominant (P = 0.006) and nondominant humerus (P = 0.009) and femoral neck (P = 0.007) compared to the controls. At the 3-year followup, the athletes had significantly higher BMD at all sites (total body; P = 0.003, spine; P = 0.02, dominant humerus; P = 0.001, nondominant humerus; P = <0.001, femoral neck; P = 0.001) except for the head (P = 0.91) compared with controls. The athletes also had higher vBMD at the femoral neck compared with the controls (P = 0.01). Furthermore, to be an athlete was found to be independently associated with a higher increase in nondominant humerus BMD ( = 0.24; P < 0.05) and femoral neck BMD ( = 0.30; P < 0.05) compared with the controls, during the study period. In summary, these results suggests that it is possible to achieve continuous gains in bone mass in sites exposed to osteogenic stimulation after puberty in males by engaging in weight-bearing physical activity.     

Effect of Supplementation with Vitamin D3 and Calcium on Quantitative Ultrasound of Bone in Elderly Institutionalized Women: A Longitudinal Study

Supplementation of elderly institutionalized women with vitamin D and calcium decreased hip fractures and increased hip bone mineral density. Quantitative ultrasound (QUS) measurements can be performed in nursing homes, and easily repeated for follow-up. However, the effect of the correction of vitamin D deficiency on QUS parameters is not known. Therefore, 248 institutionalized women aged 62–98 years were included in a 2-year open controlled study. They were randomized into a treated group (n = 124), receiving 440 IU of vitamin D₃ combined with 500 mg calcium (1250 mg calcium carbonate, Novartis) twice daily, and a control group (n = 124). One hundred and three women (42%), aged 84.5 ± 7.5 years, completed the study: 50 in the treated group, 53 in the controls. QUS of the calcaneus, which measures BUA (broadband ultrasound attenuation) and SOS (speed of sound), and biochemical analysis were performed before and after 1 and 2 years of treatment. Only the results of the women with a complete follow-up were taken into account. Both groups had low initial mean serum 25-hydroxyvitamin D levels (11.9 ± 1.2 and 11.7 ± 1.2 mg/l; normal range 6.4–40.2 mg/l) and normal mean serum parathyroid hormone (PTH) levels (43.1 ± 3.2 and 44.6 ± 3.5 ng/l; normal range 10–70 ng/l, normal mean 31.8 ± 2.3 ng/l). The treatment led to a correction of the metabolic disturbances, with an increase in 25-hydroxyvitamin D by 123% (p50.01) and a decrease in PTH by 18% (p50.05) and of alkaline phosphatase by 15% (p50.01). In the controls there was a worsening of the hypovitaminosis D, with a decrease of 25-hydroxyvitamin D by 51% (p50.01) and an increase in PTH by 51% (p50.01), while the serum calcium level decreased by only 2% (p5 0.01). After 2 years of treatment BUA increased significantly by 1.6% in the treated group (p50.05), and decreased by 2.3% in the controls (p50.01). Therefore, the difference in BUA between the treated subjects and the controls (3.9%) was significant after 2 years (p50.01). However, SOS decreased by the same amount in both groups (approximately 0.5%). In conclusion, BUA, but not SOS, reflected the positive effect on bone of supplementation with calcium and vitamin D₃ in a population of elderly institutionalized women. Received: 23 February 1998 / Accepted: 19 October 1998     

Effect of High Impact Activity on Bone Mass and Size in Adolescent Females: A Comparative Study Between Two Different Types of Sports

The purpose of this cross-sectional study was to investigate the influence of two different types of weight-bearing activity, muscle strength, and body composition on bone mineral density (BMD), bone mineral content (BMC), and bone area in three different groups of late adolescent girls. The first group consisted of 10 females participating in competitive rope-skipping (age 17.8 ± 0.8 years) training for 6.7 ± 3.1 hours/week; the second group consisted of 15 soccer players (age 17.4 ± 0.8 years) training for 6.1 ± 2.0 hours/week; and the third group consisted of 25 controls (age 17.6 ± 0.8 years) with physical activity of 0.9 ± 1.1 hours/week. The groups were matched for age, height, and weight. BMD (g/cm²), BMC (g), and bone area (cm²) of the total body, lumbar spine, hip, total femur, distal femur, diaphyses of femur and tibia, proximal tibia, and humerus were measured using dual-energy X-ray absorptiometry (DXA). Bone density was also assessed in the radial forearm site of the dominant limb in the rope skippers and in 10 matched controls. The rope skippers had 22% higher BMD at the ultradistal site (P < 0.01). Both high-activity groups had significantly higher BMD (P < 0.05) at most loaded sites compared with the control group. When adjusting for differences in lean mass and starting age of sport-specific training between the activity groups, the rope-skipping group had a higher BMD of the total body, lumbar spine, and right humerus compared with the soccer group. They also had a significantly higher bone area of the total body, total femur, and the proximal femur than both other groups, and a significantly higher bone area of the tibia diaphysis, compared with the soccer group. In a multivariate analysis among all subjects (n = 50), all BMD sites, except the femur diaphysis, distal femur, and proximal tibia, were significantly related to type of physical activity (β= 0.25–0.43, P < 0.05). The bone area values at different sites were strongly related to muscle strength and parameters related to body size [height, weight, lean mass, fat mass, and body mass index (BMI)]. In conclusion, it appears that in late adolescent women, weight-bearing activities are an important determinant for bone density, and high impact activities such as jumping also seem to be associated with a modification of the bone geometry (hence, the bone width) at the loaded sites. Received: 28 June 1999 / Accepted: 22 March 2000     

Exogenous PTH and Endogenous 1,25‐Dihydroxyvitamin D Are Complementary in Inducing an Anabolic Effect on Bone

PTH and 1,25(OH)₂D each exert dual anabolic and catabolic skeletal effects. We assessed the potential interaction of PTH and 1,25(OH)₂D in promoting skeletal anabolism by comparing the capacity of exogenous, intermittently injected PTH(1‐34) to produce bone accrual in mice homozygous for the 1α(OH)ase‐null allele [1α(OH)ase^?/? mice] and in wildtype mice. In initial studies, 3‐mo‐old wildtype mice were either injected once daily (40 μg/kg) or infused continuously (120 μg/kg/d) with PTH(1–34) for up to 1 mo. Infused PTH reduced BMD, increased the bone resorption marker TRACP‐5b, and raised serum calcium but did not increase serum 1,25(OH)₂D. Injected PTH increased serum 1,25(OH)₂D and BMD, raised the bone formation marker osteocalcin more than did infused PTH, and did not produce sustained hypercalcemia as did PTH infusion. In subsequent studies, 3‐mo‐old 1α(OH)ase^?/? mice, raised on a rescue diet, and wildtype littermates were injected with PTH(1–34) (40 μg/kg) either once daily or three times daily for 1 mo. In 1α(OH)ase^?/? mice, baseline bone volume (BV/TV) and bone formation (BFR/BS) were lower than in wildtype mice. PTH administered intermittently increased BV/TV and BFR/BS in a dose‐dependent manner, but the increases were always less than in wildtype mice. These studies show that exogenous PTH administered continuously resorbs bone without raising endogenous 1,25(OH)₂D. Intermittently administered PTH can increase bone accrual in the absence of 1,25(OH)₂D, but 1,25(OH)₂D complements this PTH action. An increase in endogenous 1,25(OH)₂D may therefore facilitate an optimal skeletal anabolic response to PTH and may be relevant to the development of improved therapeutics for enhancing skeletal anabolism.     

1α，25双羟维生素D3对成骨样细胞增殖与分化的影响

采用同位素掺入，细胞周期、细胞化学和扫描电镜等方法观察了１α，２５双羟维生素Ｄ３［１，２５（ＯＨ）２Ｄ３］对人及大鼠成骨样细胞ＯＳ－７３２和ＲＯＳ１７／２．８增殖及分化的影响。结果表明：１，２５（ＯＨ）２Ｄ３对ＯＳ－７３２细胞增殖的抑制作用呈明显的时效和量效关系。在给１０－７ｍｏｌ／Ｌ的１，２５（ＯＨ）２Ｄ３后第４和第６天，对ＯＳ－７３２细胞生长的抑制率分别为４０％和６０％；对ＤＮＡ，ＲＮＡ和蛋白质合成的抑制作用分别为５９％，４１％和２２％。流式细胞计测定结果表明：１，２５（ＯＨ）２Ｄ３使ＤＮＡ合成受阻；扫描电镜显示：１，２５（ＯＨ）２Ｄ３有抑制ＲＯＳ１７／２．８细胞表面微绒毛的作用。此外，细胞化学染色表明：该激素有增加成骨样细胞碱性磷酸酶活性和促进骨形态形成蛋白合成的作用，即刺激骨形成的作用。     

The Effect of Low-Dose Cholecalciferol and Calcium Treatment on Posttransplant Bone Loss in Renal Transplant Patients: A Prospective Study

Background/Aim. Posttransplant steroid doses have been reduced with the use of new and potent immunosuppressive agents. However, posttransplant osteoporosis is still a serious problem. Our aim in this study was to investigate the effect of low-dose cholecalciferol and calcium supplementation on bone loss after transplantation in renal transplant patients. Methods. Fifty-eight renal transplantation patients were included in the study. Fourteen newly transplanted patients (group 1) and 44 renal transplantation patients with a graft age of at least six months (group 2) were involved. All patients received 400 IU/day orally cholecalciferol (vitamin D3) and 600 mg/day orally calcium replacement starting from the second day posttransplantion. All patients baseline serum and urine biochemistry, serum 25-hydroxy vitamin D3 (25 (OH)D3), and bone mineral density (BMD) tests were performed. Also, the same measurements were performed at the 12th month in group 1. Results. After one year of treatment, BMDs were improved in group 1. Patients in group 1 had a nonsignificant increase of lumbar spine (8.12 ± 18.64% of baseline BMD) and femoral total (7.10 ± 13.48% of baseline BMD) BMD at the end of the first year. On the other hand, there was a significant increase in femoral neck (10.06 ± 15.70% of baseline BMD, p < 0.05) measurements. The baseline results of group 2 were similar to group 1. In group 1, 25 (OH)D3 levels were increased while PTH levels were decreased at the end of the year. Conclusion. In renal transplant patients who use low-dose metilprednisolon and new immunosuppressive agents together, low doses of vitamin D3 and calcium replacement for one year provides a reduction in lumbar spine, femoral neck, and femoral total bone loss and prevents bone loss in group 2. In addition, it contributed to the normalization of PTH levels.     

Effect of combined administration of vitamin D3 and vitamin K2 on bone mineral density of the lumbar spine in postmenopausal women with osteoporosis

The effect of the combined administration of vitamin D₃ and vitamin K₂ on bone mineral density (BMD) of the lumbar spine was examined in postmenopausal women with osteoporosis. Ninety-two osteoporotic women who were more than 5 years after menopause, aged 55–81 years, were randomly divided into four administration groups: vitamin D₃ (1α hydroxyvitamin D₃, 0.75 μg/day) (D group; n = 29), vitamin K₂ (menatetrenone, 45 mg/day) (K group; n = 22), vitamin D₃ plus vitamin K₂ (DK group, n = 21), and calcium (calcium lactate, 2 g/day) (C group; n = 20). BMD of the lumbar spine (L2–L4) was measured by dual energy X-ray absorptiometry at 0, 1, and 2 years after the treatment started. There were no significant differences in age, body mass index, years since menopause, and initial BMD among the four groups. One-way analysis of variance (ANOVA) with repeated measurements showed a significant decrease in BMD in the C group (P < 0.001). Two-way ANOVA with repeated measurements showed a significant increase in BMD in the D and K groups compared with that in the C group (P < 0.05 and P < 0.001, respectively), and a significant increase in BMD in the DK group compared with that in the C, D, and K groups (P < 0.0001, P < 0.05 and P < 0.01, respectively). These findings indicate that combined administration of vitamin D₃ and vitamin K₂, compared with calcium administration, appears to be useful in increasing the BMD of the lumbar spine in postmenopausal women with osteoporosis. Received: January 13, 2000 / Accepted: June 5, 2000     

Effect of Soy Protein on Bone Metabolism in Postmenopausal Japanese Women

We conducted a cross-sectional study of the effects of soybean protein intake on bone mineral density and biochemical markers in 85 postmenopausal Japanese women. Nutrients in the diet of postmenopausal Japanese women visiting the osteoporosis unit, including subjects with normal lumbar spine bone mineral density (L2–4 BMD), were investigated by questionnaire, and the calculated daily energy, protein, soy protein and calcium intake were obtained. L2–4 BMD was measured with dual-energy X-ray absorptiometry, and assays done of serum alkaline phosphatase (ALP) and serum intact osteocalcin (IOC) as bone formation markers and urinary pyridinoline (UPYR) and urinary deoxypyridinoline (UDPYR) as bone resorption markers. Soy protein intake was significantly associated with the Z-score for L2–4 BMD (r= 0.23, p = 0.038) and UDPYR (r =−0.23, p = 0.034). Stepwise multiple regression analyses showed that soy protein intake is significantly associated with the Z-score for L2–4 BMD (β= 0.225, p = 0.04) and UDPYR (β=−0.08, p = 0.03) among four nutritional factors. These results suggest that high soy protein intake is associated with a higher bone mineral density and a lower level of bone resorption, but further studies are needed to confirm the causal dynamic mechanisms. Received: 17 September 1999 / Accepted: 29 February 2000