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PubMed1992

The influence of testosterone substitution on bone mineral density in patients with Klinefelter's syndrome.

The aim of this study was to clarify the extent of bone mineral deficiency in patients with Klinefelter's syndrome on the premise that testosterone substitution could prevent this deficiency. Bone mineral density was measured by single-photon absorptiometry in 42 patients with Klinefelter's syndrome, (21 patients without therapy, 10 with testosterone substitution before the age of 20 and 11 patients with testosterone substitution beginning after the age of 20). We found significantly lower bone mineral density in patients without therapy and in patients when the therapy began later compared to normal individuals. Patients with early therapy showed a high proportion of normal values of bone mineral density. We found a positive correlation between bone mineral density and plasma testosterone and a negative correlation between plasma testosterone and age for patients without therapy. These findings suggest that low testosterone levels before or during puberty cause inadequate bone development and low bone mineral density in Klinefelter's syndrome. Only early testosterone substitution may prevent bone mineral deficiency. Later substitution no longer affects bone mineral density.

Adult↗
PubMed2004

Long-term, high-dose glucocorticoids and bone mineral content in childhood glucocorticoid-sensitive nephrotic syndrome.

BACKGROUND: Glucocorticoids suppress bone formation, impair growth, and induce obesity. We determined the effects of long-term treatment with glucocorticoids on bone mineral content in children with glucocorticoid-sensitive nephrotic syndrome, a disorder with minimal known independent effects on bone. METHODS: We performed dual-energy x-ray absorptiometry of the whole body and spine in 60 children and adolescents with the nephrotic syndrome and 195 control subjects. We used linear regression analysis of log-transformed values to compare the bone mineral content in patients with that in controls. RESULTS: Patients had received an average of 23,000 mg of glucocorticoids and were shorter (P=0.008) and had a greater body-mass index (P<0.001) than controls. The bone mineral content of the spine, adjusted for bone area, age, sex, degree of maturation (Tanner stage), and race, did not differ significantly between patients and controls (ratio, 0.99; 95 percent confidence interval, 0.96 to 1.02; P=0.51). After adjustment for the z score for body-mass index, the bone mineral content of the spine was significantly lower in patients than in controls (0.96; 95 percent confidence interval, 0.92 to 0.99; P=0.01). Whole-body bone mineral content, adjusted for height, age, sex, degree of maturation, and race, was significantly higher in patients than in controls (ratio, 1.11; 95 percent confidence interval, 1.05 to 1.18; P<0.001); however, the addition of the z score for body-mass index to the model eliminated the association with the nephrotic syndrome (ratio, 0.99; 95 percent confidence interval, 0.94 to 1.03; P=0.55). CONCLUSIONS: Intermittent treatment with high-dose glucocorticoids during growth does not appear to be associated with deficits in the bone mineral content of the spine or whole body relative to age, bone size, sex, and degree of maturation. Glucocorticoid-induced increases in body-mass index were associated with increased whole-body bone mineral content and maintenance of the bone mineral content of the spine.

Absorptiometry, Photon↗
PubMed2002

Bone mineral density in triathletes over a competitive season.

There is evidence from previous cross-sectional studies that high volumes of certain sports, including running, swimming and cycling, may have a negative impact on bone mineral density. The aim of the present study was to evaluate prospectively the effects of high athletic training in individuals who engage in high volumes of all three of these activities (triathletes). Bone mineral density for the total body, arms and legs was determined by dual-energy X-ray absorptiometry in 21 competitive triathletes (9 men, 12 women) at the beginning of the training season and 24 weeks later. Age, body mass index, calcium intake and training volume were also recorded to examine potential mediators of bone mineral density change. Men had greater bone mineral density at all sites than women. No significant changes were observed over the 24 weeks for either total body or leg bone mineral density. Bone mineral density in both arms increased by approximately 2% in men (P < 0.03), but no change was observed for women. Change in bone mineral density at all sites was unrelated to age, body mass index, calcium intake and training volume. The results suggest that adverse changes in bone mineral density do not occur over the course of 6 months of training in competitive triathletes.

Absorptiometry, Photon↗
PubMed2002

Changes in bone remodeling rate influence the degree of mineralization of bone.

Mineralization of bone matrix implies two successive steps, a primary mineralization on the calcification front followed by a slow process of secondary mineralization progressively adding about 50-60% of the mineral content on bone matrix. Our model is that antiresorptive agents prolong the lifetime of the basic structural units (BSUs) by causing a marked reduction in the birth rate of basic multicellular units (BMUs), and increase the degree of mineralization of bone (DMB) by allowing a more complete secondary mineralization. Conversely, agents or events provoking an augmentation of the birthrate of BMUs and a decrease of the lifetime of BSUs lead to resorption of new BSUs before they have fully completed their secondary mineralization, leading to the presence of incompletely mineralized BSUs and a low mean DMB value, as measured by quantitative microradiography. Measurements of DMB (distribution and mean value) under circumstances with various remodeling activities favor our model. In postmenopausal osteoporotic women treated during 2 or 3 years with alendronate (10 mg/day), an increase of the mean DMB of approximately 7 to 10% was found, due to a marked reduction in the bone remodeling. In contrast, an activation of bone remodeling as in primary hyperparathyroidism lowered the mean DMB.

Adult↗
PubMedDate not supplied

Microcracks colocalize within highly mineralized regions of cortical bone tissue.

While much work has been performed to quantify the extent of bone damage, its effects on the mechanical integrity of the tissue and its biological impact, the set of factors which gives forth to microdamage are nebulous, particularly the compositional properties local to microdamage. In this context, the current study tested the hypothesis that microcracks initiate within more mineralized regions of bone. Cortical bone specimens were taken from human male donors aged 31, 38, 53, 64, 71, and 84 years at the mid femoral diaphysis in a plane parallel to the osteonal orientation. The mineralization was assessed in a spatially resolved manner using Raman microspectroscopy. Arrays of measurements were taken over the entire area (i.e. global scans) of each sample followed by measurements in the vicinity of microcracks (i.e. local scans). Histograms of mineralization were constructed for global and local scans to determine whether the mineralization of damaged loci differed from the mean overall mineralization. Statistical analysis of this data revealed that the mean mineralization of damaged loci was significantly greater (P < 0.05) than the overall mineralization for each donor, indicating that there exists a highly-mineralized 'brittle volume' in bone. The presence of this damage prone 'brittle volume' has future implications for the assessment of fracture susceptibility.

Adult↗
PubMed1994

Change in bone mineral density in patients with hyperthyroidism after attainment of euthyroidism by dual energy X-ray absorptiometry.

Because of the previous controversial findings in studies of bone mineral density in patients with hyperthyroidism with older methodologies, we assessed bone mineral density in 15 Japanese patients with Graves' disease (8 males and 7 females) before and after treatment using dual energy X-ray absorptiometry (DEXA). Bone mineral density of the lumbar vertebrae and the femur, and thyroid function, and several metabolic parameters were measured before treatment and again after patients achieved a euthyroid state following treatment with methimazole for 4 to 20 months (mean 10.6 months). The bone mineral density of patients was calculated as the percentage of the mean value (%BMD) in an age- and sex-matched control group, and correlations between the changes in bone mineral density and metabolic parameters before and after treatment were investigated. The %BMD of vertebrae in patients with Graves' disease before treatment was 89.7% of that found in the normal population. When patients became euthyroid after treatment, %BMD increased significantly to 94.9%, although it still remained below the control level. TSH receptor antibody, osteocalcin, and alkaline phosphatase were elevated before treatment, but decreased significantly after treatment. The change between pre- and posttreatment TSH receptor antibody was negatively correlated with the change in bone mineral density. In conclusion, these findings suggest that bone mineral density is decreased in patients with Graves' disease and that successful treatment of hyperthyroidism results in a significant increase in bone mineral density within a short period of time. Furthermore, TSH receptor antibody is a useful marker of changes in bone metabolism in this group of patients.

Absorptiometry, Photon↗
PubMed2006

Randomized, placebo-controlled, calcium supplementation study in pregnant Gambian women: effects on breast-milk calcium concentrations and infant birth weight, growth, and bone mineral accretion in the first year of life.

BACKGROUND: Growth and bone mineral accretion in Gambian infants are poorer than those in Western populations. The calcium intake of Gambian women is low, typically 300-400 mg Ca/d, and they have low breast-milk calcium concentrations, which result in low calcium intakes for their breastfed infants. A low maternal calcium supply in pregnancy may limit fetal mineral accretion and breast-milk calcium concentrations and thereby affect infant growth and bone mineral accretion. OBJECTIVE: We investigated the effects of calcium supplementation in Gambian women during pregnancy on breast-milk calcium concentrations and infant birth weight, growth, and bone mineral accretion. DESIGN: A randomized, double-blind, placebo-controlled supplementation study was conducted in 125 Gambian women who received 1500 mg Ca/d (as calcium carbonate) or placebo from 20 wk of gestation until delivery. Infant birth weight and gestational age were recorded. Breast milk was collected, and infant anthropometric and bone measurements were performed at 2, 13, and 52 wk after delivery. Infant bone mineral status was assessed by using single-photon absorptiometry of the radius and whole-body dual-energy X-ray absorptiometry. RESULTS: Compliance with the supplement was high. No significant differences were detected between the groups in breast-milk calcium concentration, infant birth weight, or growth or bone mineral status during the first year of life. A slower rate of increase in infant whole-body bone mineral content and bone area was found in the supplement group than in the placebo group (group x time interaction: P = 0.03 and 0.02, respectively). CONCLUSION: Calcium supplementation of pregnant Gambian women had no significant benefit for breast-milk calcium concentrations or infant birth weight, growth, or bone mineral status in the first year of life.

Absorptiometry, Photon↗
PubMed1984

Effects of the interrelationship between dietary protein and minerals on tissue content of trace metals in streptozotocin-diabetic rats.

Zinc, iron and copper concentrations were measured in several organs from streptozotocin-diabetic and normal male, Long-Evans rats that were maintained for 21 days on a dietary regimen designed to study the combined or singular effects of insulin-dependent diabetes, dietary protein and dietary minerals on the tissue content of trace metals. The diets contained either 20 ppm zinc and iron, 5 ppm copper and 20% protein (HMHP); 8 ppm zinc and iron, 2 ppm copper and 8.3% protein (LMLP); 20 ppm zinc and iron, 5 ppm copper and 8.3% protein (HMLP) or 8 ppm zinc and iron, 2 ppm copper and 20% protein (LMHP). The concentrations of zinc, iron and copper in liver, zinc and iron in kidney and iron in femur were elevated in the diabetic rats and were not influenced by dietary protein and mineral interaction. However, dietary protein, mineral or protein X mineral interaction significantly affected trace metal concentrations of several organs in diabetic rats but had no significant effect in normal rats. Specifically, copper concentration in kidney and duodenum of diabetic rats were influenced by protein X mineral interaction, duodenal zinc concentrations were higher in diabetic rats fed high mineral diets (HMHP and HMLP) compared to diabetic rats fed low mineral diets (LMHP and LMLP) and femur zinc concentration was higher in diabetic rats fed high protein diets (HMHP and LMLP) compared to diabetic rats fed low protein diets (HMLP and LMLP). While hepatic picolinic carboxylase was elevated severalfold in diabetic rats, it was highest in the diabetic rats fed high protein diets (HPHM and HPLM) suggesting that picolinic acid may, at least in part, mediate the effects of dietary protein and minerals on tissue trace metal concentrations in diabetic rats.

Animals↗
PubMed1992

Joint influence of fat and lean body composition compartments on femoral bone mineral density in premenopausal women.

Body composition (fat and lean compartments) and bone mineral density were measured in 246 healthy premenopausal women, aged 20-40 years, residing in Tecumseh, Michigan. Body composition was measured using four-point bioelectrical impedance and values for fat and lean compartments categorized into tertiles. Additionally, each woman was classified into one of nine different cells based on her location within a 3 x 3 table which reflects the joint distribution of both fat and lean compartments. Bone mineral density of the proximal femur, including the femoral neck and trochanter, was measured using dual photon densitometry. The mean femoral neck bone mineral density values increased significantly and linearly for each tertile of muscle mass (0.90, 0.95, and 1.02 g/cm2, p less than 0.0002). Femoral bone mineral density increased significantly but not linearly as the fat compartment progressed from the lowest to the highest tertile (0.95, 0.93, and 0.99 g/cm2). Bone mineral density of the proximal femur was similar and significantly greater in the high muscle/low fat and high muscle/high fat body composition subgroups compared with bone mineral density in the seven other groups. However, women in the high muscle/low fat subgroup had substantially lower mean weight (67 vs. 91 kg, p less than 0.0001) and mean Quetelet index (22.1 vs. 33.7 kg/m2, p less than 0.0001) than women in the high muscle/high fat subgroup. Bone mineral density values were similar and significantly lower in the following body composition cells: low muscle/low fat, low muscle/medium fat, and low muscle/high fat. Similar findings were observed at the trochanteric site. Low muscle is a risk factor for low bone mineral density in young adult women while higher fat is protective only when associated with substantial muscle.

Absorptiometry, Photon↗
PubMed1996

Effect of rotation on periprosthetic bone mineral measurements in a hip phantom.

The effect of rotation on the measurement of periprosthetic bone mineral content and bone mineral density using dual energy xray absorptiometry was studied in 9 anatomic specimen femora implanted with noncemented titanium hip prostheses. An apparatus was constructed to permit accurate femoral rotation through an arc of 30 degrees internal to 30 degrees external rotation in 5 degrees increments. Two scans were obtained at each increment of rotation for a total of 26 scans for each implanted femur. Change in bone mineral content and bone mineral density was measured for each of 7 contiguous periimplant regions (Gruen zones). The precision of the paired bone mineral density measurements was 1.7%. In all Gruen zones, the means of bone mineral content and bone mineral density measurements varied within 5% between 15 degrees internal and 15 degrees external rotation. Variation in limb rotation, as might occur with temporal studies of periimplant bone remodeling, can be tolerated within easily controllable limits without excessive error in bone mineral measurements.

Absorptiometry, Photon↗
PubMed2000

Bone mineral density variations along the lumbosacral spine.

Vertebral bone quality is essential in vertebral strength and the stability of spinal screw fixation. A major factor of bone quality is the density of bone mineral and its distribution throughout the bone. There have been studies regarding bone mineral density variations in the cervical and thoracolumbar spine, but bone mineral density variations in the lumbosacral spine have not been documented. The purpose of the current study was to quantify bone mineral density variations at different lumbosacral levels and within vertebra, especially along the pathways of lumbar pedicle screws. Bone mineral density variations within the vertebrae along the lumbosacral spine were measured in 13 specimens from young male cadavers using peripheral quantitative computed tomography. Measurements included bone mineral density variations at different lumbosacral levels and in transverse layers and vertical columns within each vertebral body. These original data showed that the bone mineral density increased gradually from lumbar to S1 vertebrae, possibly reflecting a caudally increasing load on different lumbosacral levels. The highest bone mineral density in the lumbosacral spine is found at the pedicles and regions closest to pedicle bases, supporting the use of pedicle screw fixation.

Adult↗
PubMed1996

Pitfalls in the measurement of bone mineral density by dual energy x-ray absorptiometry.

STUDY DESIGN: Fifty-three human thoracic and lumbar vertebrae were analyzed by dual energy x-ray absorptiomety to obtain projectional (g/cm2) and volumetric (g/cm3) bone mineral density. OBJECTIVES: To determine the effect of volume on the measurement of bone mineral density by DEXA. SUMMARY OF BACKGROUND DATA: Despite the widespread use of dual energy x-ray absorptiomety to measure bone mineral density expressed as grams per projectional unit area (g/cm2), the effect of volume has been ignored in many published biomechanical studies. METHODS: Projectional bone mineral density (g/cm2) of fifty-three human vertebrae was obtained by dual energy x-ray absorptiometry measurement. This was compared to bone mineral density expressed as grams per unit volume. RESULTS: Many specimens with near equal projectional bone mineral density were demonstrated to have significantly different true densities when measured by dual energy x-ray absorptiomety in grams per unit volume. The difference in true bone mineral density for these specimens ranged from 24.1% to 139%. CONCLUSION: The effect of volume on bone mineral density data based on projectional areas can cause very significant perturbations of the data in biomechanical studies.

Absorptiometry, Photon↗
PubMed2000

Vertebral blood flow and bone mineral density during long-term corticosteroid treatment: An experimental study in immature pigs.

STUDY DESIGN: Bone mineral density and regional blood flow were measured in pigs during long-term methylprednisolone treatment. OBJECTIVES: To investigate possible changes in bone mineral density and vertebral blood flow during long-term glucocorticoid treatment. SUMMARY OF BACKGROUND DATA: Steroid-induced vertebral osteonecrosis preferentially involves endplates and adjacent cancellous bone. The precise etiology of vertebral osteonecrosis during long-term glucocorticoid treatment is unknown. METHODS: Twenty-four 10-week-old female Danish landrace sister pigs from 12 litters were treated in two groups. Twelve animals received oral methylprednisolone for 3 months at a daily dose of 100 mg. The 12 sister pigs received no steroid treatment and served as controls. Regional blood blow was measured by means of microspheres in predefined regions of the C6, T11, and L6 vertebrae. In vitro DEXA scanning of the L2-L4 vertebra was performed to assess bone mineral density. RESULTS: Vertebral cancellous bone and endplate regional blood flow were decreased in the C6 and L6 vertebrae among corticosteroid-treated pigs compared with that of controls.- Width-adjusted lumbar vertebral bone mineral density (g/cm3) was unchanged, whereas projectional lumbar vertebral bone mineral density (g/cm2) was decreased in corticosteroid-treated pigs. CONCLUSIONS: Long-term methylprednisolone treatment decreases vertebral bone blood flow mainly in cancellous bone and endplates. This may be an important factor in the pathogenesis of osteonecrosis secondary to glucocorticoid treatment. Lumbar vertebral bone mineral density was unchanged in growing pigs on long-term glucocorticoid treatment when expressed as volumetric bone density. The effect of glucocorticoid treatment on vertebral bone mineral density appears to depend on whether it is expressed as projectional (g/cm2) or volumetric bone mineral density (g/cm3). Vertebral and longbone growth was reduced during methylprednisolone treatment.

Animals↗
PubMedDate not supplied

Sublingual administration of micronized estradiol and progesterone, with and without micronized testosterone: effect on biochemical markers of bone metabolism and bone mineral density.

OBJECTIVES: The purpose of this investigation was to evaluate the relative efficacy of the sublingual administration of micronized estradiol (E2), progesterone (P4), and testosterone (T) on bone mineral density and biochemical markers of bone metabolism. DESIGN: In this double-blind, prospective study, postmenopausal women were randomly assigned to one of four treatment groups: hysterectomized women were assigned to either 1) micronized E2 (0.5 mg) or 2) micronized E2 (0.5 mg) + micronized T (1.25 mg). Women with intact uteri were assigned to either 3) micronized E2 (0.5 mg) + micronized P4 (100 mg) or 4) micronized E2 (0.5 mg) + micronized P4 (100 mcg) + micronized T (1.25 mg). For the purpose of this study, the four treatment groups were combined into two groups for all comparisons. The E2 and E2+P4 groups were combined into the HRT alone group (n=30), and the E2+T and E2+P4+T groups were combined into the HRT + T group (n=27). Hormones were administered sublingually as a single tablet twice a day for 12 months. Bone mineral density was measured in the anterior-posterior lumbar spine and total left hip via dual energy x-ray absorptiometry. Bone metabolism was assessed via serum bone-specific alkaline phosphatase and urinary deoxypyridinoline and cross-linked N-telopeptide of type I collagen, both normalized to creatinine. Data were analyzed via a repeated measures analysis of variance and a Student's t test (alpha=0.05). RESULTS: The subjects were of similar age (54.0 +/- 0.8 years), height (64.0 +/- 0.3 in), weight (157.6 +/- 4.2 lb), and had similar baseline follicle-stimulating hormone (66.4 +/- 3.2 mIU/L), E2 (26.4 +/- 1.5 pg/ml), P4 (0.3 +/- 0.1 ng/ml), total T (19.0 +/- 1.5 ng/dL), and bioavailable T (3.7 +/- 0.3 ng/dL) levels. During therapy, serum levels increased (p < 0.05) for each hormone. Bone mineral density and bone markers at baseline were similar for each treatment group. Bone-specific alkaline phosphatase decreased (p < 0.05) by -14.3 +/- 4.1% in the HRT alone group and by -8.2 +/- 4.6% in the HRT + T group. Deoxypyridinoline levels decreased significantly in the HRT alone and HRT + T groups, - 14.4 +/- 6.8% and -26.9 +/- 7.6%, respectively. Significant reductions (p < 0.05) in cross-linked N-telopeptide of type I collagen were also observed in both groups, -24.4 +/- 6.5% and -39.5 +/- 8.6%, respectively. Bone mineral density in the lumbar spine increased (p < 0.05) by +2.2 +/- 0.5% the HRT alone group and by + 1.8 +/- 0.6% in the HRT + T group. Total hip bone mineral density was maintained in the HRT alone group (+0.4 +/- 0.4%) and increased (p < 0.05) in the HRT + T group (+ 1.8 +/- 0.5%). CONCLUSIONS: Sublingual micronized HRT favorably decreases serum and urine markers of bone metabolism, prevents bone loss, and results in a slight increase in spine and hip bone mineral density. Although the addition of testosterone to HRT for 1 year did not result in added benefit to the spine bone mineral density, it did result in a significant increase in hip bone mineral density. Longer duration of therapy may have further improved these outcomes.

Administration, Sublingual↗
PubMed2004

Effects of hormonal contraception on bone mineral density after 24 months of use.

OBJECTIVE: To measure the effect of 24 months of depot medroxyprogesterone acetate use on bone mineral density compared with oral contraception (pills) and nonhormonal contraception. METHODS: Women aged 18-33 years self-selected oral contraception, depot medroxyprogesterone acetate, or nonhormonal contraception (controls). Those selecting pills were randomized to formulations containing either 35 microg ethinyl estradiol and norethindrone or 30 microg ethinyl estradiol and desogestrel. Controls were frequency matched on age and race/ethnicity to hormonal contraception users. Dual-energy X-ray absorptiometry of the lumbar spine (L1-L4) was performed at baseline, 12 months, and 24 months. Percent change in bone mineral density was analyzed by using analysis of covariance, adjusting for age, race/ethnicity, weight-bearing exercise, calcium intake, smoking status, and body mass index. RESULTS: Of the 191 women making up the final sample, 86 used pills, 47 used depot medroxyprogesterone acetate, and 58 used nonhormonal contraception. Women using depot medroxyprogesterone acetate for 24 months experienced, on average, a 5.7% loss in bone mineral density, with a 3.2% loss occurring between months 12 and 24. On average, users of desogestrel pills experienced a 2.6% loss in bone mineral density after 24 months. Bonferroni-adjusted pairwise comparisons demonstrated that bone mineral density changes from baseline to 24 months among depot medroxyprogesterone acetate users differed significantly from changes experienced by either of the pill groups or the control group. Changes in bone mineral density among users of either pill did not significantly differ from each other or from controls. CONCLUSION: Loss of bone mineral density associated with depot medroxyprogesterone acetate use appears to be linear during the first 2 years of use. Shifts in bone mineral density among pill users were not significant when compared with controls.

Adolescent↗
PubMed2004

Notch sensitivity of mammalian mineralized tissues in impact.

The toughness of bone is an important feature in preventing it from fracturing. We consider the notch sensitivity in impact, and the associations between brittleness, notch sensitivity and post-yield energy absorption of mammalian mineralized tissues. Specimens of bone-like tissues covering a wide range of mineralization were broken, either notched or un-notched, in impact. The greater the mineral content, the greater was the notch sensitivity. Also, the more brittle tissues dissipated the least post-yield energy and were the most notch sensitive. It is suggested that since antler bone, the least mineralized of all known mammalian mineralized tissues, seems to be notch insensitive in impact, no adaptive purpose would be served by having mineralized tissues of a lower mineralization than antler. This may explain the lower cut-off in mineralization seen in mammals.

Animals↗
PubMed1999

Gender, age, and body weight are the major predictive factors for bone mineral density in Crohn's disease: a case-control cross-sectional study of 113 patients.

OBJECTIVE: We conducted this study to assess bone mineral density and to evaluate conceivable predictive factors for bone loss in patients with Crohn's disease. METHODS: One hundred-thirteen patients with Crohn's disease and 113 healthy subjects, individually matched for gender, age, and body weight were investigated. The group consisted of 68 women and 45 men. The median duration of Crohn's disease was 6 yr. Two-thirds of the patients had been subjected to intestinal resection. Seventy-seven percent had at some time been treated with corticosteroids. Bone mineral density in the lumbar spine, the hip, and the total body skeleton was measured by dual-energy X-ray absorptiometry (DEXA). RESULTS: In patients with Crohn's disease bone mineral density was not different from that of healthy controls except for a regional decrease in bone mineral density of the hip in female patients. The strongest predictors of bone mineral density were gender, age, and body weight. Corticosteroid use was only a weak predictor of diminished bone density. Duration of disease and intestinal resection had no predictive value for bone mineral density. CONCLUSIONS: Gender, age, and body weight are the major determinants of bone mineral density in patients with Crohn's disease. As in healthy individuals, the combined effect of these factors account for up to 50% of the variability in bone mineral density.

Absorptiometry, Photon↗
PubMed1980

Electronmicroscopic study of mineralization in induced heterotopic bone formation in guinea pigs.

Mineralization of heterotopic bone was studied in a bone induction model using allogenic demineralized dentin implanted in the abdominal wall of guinea pigs. There was a high yield of newly formed osteoid and bone as well as some cartilage together with areas of resorption of the dentin, and fibroblast proliferation. The osteoid contained many matrix vesicles II and less of lysosome-like type I vesicles. Early cartilage formation had more type I vesicles. The implanted dentin contained no matrix vesicles. The first signs of mineralization occurred mainly as irregular clusters of mineral crystals in the matrix close to the surface of collagen fibrils. Crystal-like figures were also found inside some type II matrix vesicles, although most of these vesicles in the mineralization zone had no crystals. The type I vesicles of both bone and cartilage exhibited often crystals near the outer membrane. The mineralizing bone showed a reduction in the size and number of proteoglycan particles. Remineralization of the implanted dentin was also often found and the mineralization pattern resembled the mineralization of bone except for the absence of matrix vesicles. Electron diffraction of selected areas showed that the crystals in the new bone and the mineralized dentin were hydroxyapatite.

Animals↗