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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Osteoporotic fractures are more common in women than men. Although accelerated bone loss following the menopause is recognized as of major importance, it is generally considered that a lower peak adult bone mass in females also contributes to their increased risk of osteoporosis in later life. To examine potential sex differences in peak adult bone mass we studied 29 pairs of dizygotic twins of differing within-pair sex in whom the female twin was premenopausal (mean age 37 years, range 21-55). Bone mineral density (BMD, g/cm2) was measured at the lumbar spine and femoral neck by dual-photon absorptiometry; 22 pairs also had BMD measured in the distal and 21 pairs in the ultradistal radius by single-photon absorptiometry. There was no significant difference in usual dietary calcium intake or tobacco consumption between the twin pairs. Consistent with accepted dogma, BMD at both radial sites were higher (+27%) in the males than their female cotwins. In contrast, there was no sex difference (male versus female) in BMD (mean +/- SEM) in the femoral neck (0.96 +/- 0.02 versus 0.97 +/- 0.03), and surprisingly, the females had a greater lumbar spine BMD than their male cotwins (1.19 +/- 0.03 versus 1.26 +/- 0.03, p less than 0.05). This difference was observed despite the fact that the males were taller (p = 0.033). If the femoral neck BMD values in the females were corrected for this difference in BMI, their values (0.99 +/- 0.03 g/cm2) were significantly higher than those in their male cotwin (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sex differences in peak adult bone mineral density. 227 Jul 79

It has recently been reported that oestrogen replacement may preserve the ratio of muscle strength to cross-sectional area in the hand in addition to its beneficial effect on bone mass in postmenopausal women. Since muscle strength is associated with falls and fractures in elderly people, this additional effect of oestrogen replacement could be of considerable benefit to postmenopausal women. We therefore wished to determine whether this effect was also evident in larger muscle groups that are involved in ambulation, balance, and activities of daily living. We examined the relationship of oestrogen replacement therapy (ORT) to maximal dynamic muscle strength in 85 healthy women aged 65-82 years. Thirty-seven women were currently taking ORT and had been on stable doses for 2 to 43 years [17.8 (1.8); mean (SEM)], while 48 women had no previous exposure to postmenopausal oestrogen therapy. Dynamic muscle strength was determined for five standard lower-body exercises using isotonic equipment by the 1-RM method. Bone mineral density (BMD, g/cm2) of the axial and appendicular skeleton as well as body composition was assessed by dual-energy X-ray absorptiometry. There was no difference between subjects according to ORT status for age, height, weight, lean body mass (LBM), fat mass, or percentage body fat. BMD of the spine (L2-4), mid-radius, and whole body was greater (p < 0.001) in individuals receiving ORT, with no significant difference at the femoral neck. No differences existed between groups for lower-body muscle strength. Normalizing muscle strength to body mass and LBM did not alter the result.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Maximal muscle strength of elderly women is not influenced by oestrogen status. 748 92

The aim of this paper was to evaluate the long-term (5 years) efficacy of nasal salmon calcitonin in prevention of trabecular postmenopausal bone loss, which was a follow-up of a previously published study (3 years); a randomized, controlled group comparison. One hundred healthy postmenopausal women were randomly chosen from those (186) having completed the 3 year protocol. The 100 women were allocated to an additional 2 year period (total of 5 years) of treatment with either 500 mg d-1, 5 days week-1 of calcium or the same amount of calcium plus 50 IU d-1, 5 days per week of nasal salmon calcitonin, 87 (87%) women complied with the protocol throughout. The main outcome measures were the bone mineral density of the lumbar spine (1-BMD) (DPA) and biochemical parameters reflecting bone turnover (serum alkaline phosphatases, urinary calcium/creatinine and hydroxyproline/creatinine ratios). The women receiving calcium alone presented a significant decrease in 1-BMD after 6 months [-1.6 (0.5)%] [mean(SEM)] (P < 0.01) and this decrease remained significant after 36 months [-6.1(0.8)%] (P < 0.01) and until the end of the trial [-6.6(1.0)% at t60] (P < 0.01). In women receiving calcium and calcitonin, 1-BMD significantly increased after 36 months [+2(0.7%] (P < 0.01) and 42 months [+2.5(0.7)%] (P < 0.01 and was unchanged at the other times of investigation [+1.1 (1.1)% at t60] (NS). The evolution of BMD in the two groups was highly significantly different (P < 0.001) since the sixth month of the study and remained so until the end of the study.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A 5-year controlled randomized study of prevention of postmenopausal trabecular bone loss with nasal salmon calcitonin and calcium. 798 45

Bisphosphonates seem to be effective as antiresorptive agents in the prevention and treatment of osteoporosis. However, the optimal dose and route of administration as well as the specific effects on cortical or trabecular bone have not been clarified. To compare pamidronate (APD) with fluoride (F) in the therapy of postmenopausal osteoporosis, 32 osteoporotic women were treated for 2 years either with APD (30 mg as a single intravenous infusion over 1 h every 3 months, n = 16, mean age 65 years) or with fluoride orally (20-30 mg F/day, n = 16, mean age 67 years) in an open study. Both groups received 1 g calcium and 1000 U vitamin D per day, but no estrogens or other drugs acting on bone. Both groups showed the same initial mean number of fractures per patient (2.8 and 2.7). Bone densitometry was performed every 6 months at three sites: lumbar spine and hip with dual-energy X-ray absorptiometry (BMD), distal forearm with single photon absorptiometry and lumbar spine with quantitative computed tomography. Biochemical assessment was performed in blood and urine every 3 months. Lumbar BMD (g/cm2, mean +/- SEM) increased from 0.632 (+/- 0.030) at time 0 to 0.696 (+/- 0.028) at 24 months in the APD group (p < 0.001), and from 0.684 (+/- 0.025) to 0.769 (+/- 0.028) in the fluoride group (p < 0.001). Femoral neck BMD increased significantly from 0.558 (+/- 0.025) to 0.585 (+/- 0.025) (p < 0.01) in the APD group, whereas it did not change in the fluoride group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Two years' effectiveness of intravenous pamidronate (APD) versus oral fluoride for osteoporosis occurring in the postmenopause. 800 44

We examined the effect of pulsed electromagnetic fields (PEMFs) on bone formation and disuse osteoporosis sustained during limb lengthening in a double-blind study. Seven males (mean age 13 years, range 11-19 years) and six females (mean age 12 years, range 9-19 years) were randomly allocated to receive either an active or an inactive PEMF coil. Limb lengthening was performed by the Villarubbias technique using either a unilateral or circular frame system. Sequential bone density measurements were made using dual energy X-ray absorptiometry and compared to traditional radiographs. Ten segments (eight tibial and two femoral) in seven patients were lengthened under the influence of active coils and eight segments (six tibial and two femoral) in six patients using inactive coils. There was no difference in the rate nor the amount of new bone formed at the site of distraction between the two groups. Bone loss in the segments of bone distal to the lengthening sites was observed in both groups but was significantly more marked using inactive coils (BMD reduced by 23% +/- SEM 3% and 33% +/- 4% control values after one and two months, respectively; p < 0.0001) than using active coils (BMD reduced by 10% +/- 2% at 2 months). These differences were greater at 12 months after surgery (reduced by 54% +/- 5% and 13% +/- 4%, respectively; p < 0.0001). Stimulation with pulsed electromagnetic fields has no effect on the regenerate bone, but does prevent bone loss adjacent to the distraction gap.
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PMID:Effect of pulsed electromagnetic fields on bone formation and bone loss during limb lengthening. 880 89

The effects of 52 weeks resistance training at one of two exercise intensities on thigh muscle strength, fiber cross-sectional area (CSA), and tissue composition were studied in healthy 65-79-year-old women. Subjects were assigned to either a control (CO), high-intensity (HI) or low-intensity (LO) training group. Exercise regimens consisted of three sets of leg press, knee extension, and knee flexion exercises, 3 days/week, at either 80% of one-repetition maximum (1-RM) for seven repetitions (HI) or 40% of 1-RM for 14 repetitions (LO). Dynamic muscle strength was evaluated by 1-RM, thigh lean tissue mass (LTM), fat mass, and bone mineral density (BMD, g/cm2) by dual energy X-ray absorptiometry, and fiber CSA of vastus lateralis m. by histomorphometry. Muscle strength increased, on average (+/- SEM), by 59.4 +/- 7.9% and 41.5 +/- 7.9% for HI and LO, respectively, compared to 1.3 +/- 4.8% in CO (P = 0.0001). Type I fiber CSA increased over time (P < 0.05) in both exercise groups, with a trend for increased type II area (HI, P = 0.06; LO, P = 0.11). There was no significant effect of either exercise program on thigh tissue composition, except for BMD at the 1/3 site (middle third of the femur), where LO and CO groups experienced a decline (P < 0.05) of -2.2 +/- 0.5% and -1.8 +/- 0.6%, respectively, while HI maintained BMD (+1.0 +/- 1.0%). Both training programs produced significant gains in thigh muscle strength, which were associated with fiber hypertrophy, although these did not translate into appreciable alterations in thigh tissue composition.
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PMID:Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women. 884 74

Cardiac transplantation is associated with increased prevalence and incidence of fracture, and rapid bone loss has been reported during the first posttransplant year. To define further the pattern and etiology of bone loss after cardiac transplantation, we enrolled 70 patients (52 men and 18 women) in a prospective 3-yr study. Bone densitometry (BMD) and biochemical indexes of mineral metabolism were performed before and at defined times after transplantation. Despite supplementation with elemental calcium (1000 mg/day) and vitamin D (400 IU/day), the mean rate of bone loss during the first year was 7.3 +/- 0.9% (+/- SEM) at the lumbar spine and 10.5 +/- 1.1% at the femoral neck. The rate of bone loss slowed (P < 0.001 compared to year 1) at both sites (0.9 +/- 0.9% and 0.1 +/- 1.0%, respectively) during the second year. During the third year, lumbar spine BMD increased at a rate of 2.4 +/- 0.8%/yr (P < 0.02 compared to year 2), but femoral neck BMD did not change. At the radius, the rate of decline in BMD was negligible during the first year (0.9 +/- 0.5%), but was significant during the second (2.1 +/- 0.6%; P < 0.01) and third (2.9 +/- 0.8%; P < 0.03) years. Evaluation of the pattern of bone loss during the first year demonstrated that mean lumbar spine BMD decreased rapidly during the first 6 months, after which there was no further decline. In contrast, femoral neck BMD continued to fall at an annualized rate of 8.2 +/- 1.3% during the second half of the year. The pattern and rates of bone loss were similar in men and women. Biochemistries revealed decreases in serum testosterone and osteocalcin and increases in all bone resorption markers 1 and 3 months after transplantation, with a return to baseline by 6 months. Higher rates of bone loss were associated with greater exposure to prednisone, lower serum concentrations of vitamin D metabolites, greater suppression of osteocalcin, higher levels of bone resorption markers, and, in men, lower serum testosterone concentrations. We conclude that rapid bone loss is primarily confined to the initial year after transplantation. During the first 6 months, bone loss is accompanied by alterations in markers of bone turnover consistent with biochemical uncoupling of bone formation and resorption. Greater exposure to glucocorticoids, lower serum concentrations of vitamin D metabolites and testosterone, and higher bone turnover were associated with more rapid bone loss.
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PMID:Bone loss and turnover after cardiac transplantation. 914 40

Bone densitometry provides a measure of bone mass expressed as bone mineral content (BMC) or areal bone mineral density (aBMD). BMC is unadjusted for bone size while aBMD is adjusted for the projected area of the region scanned but not its depth. Because patients with fractures often have reduced bone size, the deficit in BMC or aBMD relative to controls may be partly the result of the comparison of a smaller bone in patients with fractures with a bigger bone in controls without fractures. We asked, what proportion of the deficit in BMC and aBMD found in women with spine fractures relative to controls is attributable to smaller vertebral size? We measured BMC (g), volume (cm3, derived from projected area3/2), aBMD (g/cm2), and volumetric BMD (vBMD, g/cm3) of the third lumbar vertebra by dual-energy X-ray absorptiometry in 270 premenopausal women aged 18-43 years, 163 postmenopausal women with spine fractures aged 54-83 years, and 209 women without fractures aged 54-87 years. The regression of BMC and aBMD on volume in the premenopausal women was used to calculate volume adjusted BMC and aBMD in postmenopausal women with and without fractures (adjusted BMC = observed BMC + [50 - observed volume] x 0.29; adjusted aBMD = observed aBMD + [50 - observed volume] x 0.0044). The data were expressed in the original units and as standard deviation scores (SD) above or below the young normal mean (T scores) or the age predicted mean (Z scores). All results were expressed as mean +/- SEM. Women with spine fractures had reduced BMC (T = -2.35 +/- 0.07 SD, Z = -1.18 +/- 0.06 SD), volume (T = -1.08 +/- 0.08 SD, Z = -0.82 +/- 0.08 SD), aBMD (T = -3. 06 +/- 0.09 SD, Z = -1.14 +/- 0.06 SD) and vBMD (T = -2.67 +/- 0.10 SD, Z = - 0.94 +/- 0.07 SD) (all p < 0.001). About 48% of the difference in BMC between postmenopausal women with and without spine fractures, and about 16% of the difference in aBMD was explained by the difference in vertebral volume between them. When women with and without spine fractures were intentionally matched by aBMD (and age, height, and weight), vertebral volume was reduced (Z = -0.66 +/- 0.13 SD, p < 0.001). When women with and without fractures were intentionally matched by vertebral volume (and age, height, and weight), vBMD was reduced (Z = -1.07 +/- 0.10 SD, p < 0. 001). Women with spine fractures have smaller vertebrae with less bone in the smaller bone. About half the deficit in BMC relative to controls is due to their smaller bone size. The remainder may be due to reduced bone accrual, increased bone loss, or both. Thus, the pathogenesis of bone fragility is heterogeneous. Factors responsible for a deficit in bone mass (due to reduced accrual or excess bone loss) are unlikely to be identified when reduced bone size exaggerates the deficit, and increased bone size obscures it. Understanding the pathogenesis of bone fragility requires acknowledgment of this heterogeneity and the description of its varied morphological basis. This can be achieved by the study of the periosteal and endosteal surfaces of bone because the absolute and relative changes in these surfaces during growth and aging determine skeletal size, its mass, and architecture.
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PMID:Vertebral bone mass, size, and volumetric density in women with spinal fractures. 1049 Dec 28

Osteopenia is a frequent, often persistent, complication of anorexia nervosa (AN) in adolescent girls and occurs during a critical time in bone development. Little is known about bone metabolism in this patient population. Therefore, we measured bone density (BMD) and body composition by dual energy x-ray absorptiometry, nutritional status, bone turnover, calcium, and hormonal status in 19 adolescent girls with AN (mean +/- SEM, 16.0+/-0.4 yr) and 19 bone age-matched controls. The mean duration of AN was 19+/-5 months. Spinal (L1-L4) osteopenia was common in AN. Lumbar anterioposterior BMD was more than 1 SD below the mean in 42% of patients, and lateral spine BMD was more than 1 SD below in 63% of patients compared with controls. Lean body mass significantly predicted lumbar bone mineral content (r = 0.75; P < 0.0001) in controls only. In AN, duration of illness was the most significant predictor of spinal BMD (lumbar: r = -0.44; P = 0.06; lateral: r = -0.59; P = 0.008). AN adolescents with mature BA (15 yr and greater) were hypogonadal [estradiol, 16.2+/-1.9 vs. 23.3+/-1.6 pg/mL (P = 0.01); free testosterone, 0.70+/-0.17 vs. 1.36+/-0.14 pg/mL (P = 0.01)] although dehydroepiandrosterone sulfate and urinary free cortisol levels did not differ. Leptin levels were reduced in AN (2.9+/-2.1 vs. 16.5+/-1.8 ng/mL; P < 0.0001). Insulin-like growth factor I (IGF-I) was reduced in AN to 50% of control levels (219+/-41 vs. 511+/-35 ng/mL; P < 0.0001) and correlated with all measures of nutritional status, particularly leptin (r = 0.80; P < 0.0001). Surrogate markers of bone formation, serum osteocalcin (OC) and bone-specific alkaline phosphatase (BSAP), were significantly (P = 0.02) reduced in AN vs. controls (OC, 39.1+/-6.4 vs. 59.2+/-5.2 ng/mL; BSAP, 27.9+/-4.0 vs. 40.6+/-3.4 U/L). The majority of the variation in bone formation in AN was due to IGF-I levels (OC: r2 = 0.72; P = 0.002; BSAP: r2 = 0.53; P = 0.01) in stepwise regression analyses. Bone resorption was comparable in patients and controls. These data demonstrate that bone formation is reduced and uncoupled to bone resorption in mature adolescents with AN in association with low bone density. Lean body mass was a significant predictor of BMD in controls, but not AN patients. The major correlate of bone formation in AN was the nutritionally dependent bone trophic factor, IGF-I. Reduced IGF-I during the critical period of bone mineral accumulation may be an important factor in the development of osteopenia in adolescents with AN.
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PMID:The effects of anorexia nervosa on bone metabolism in female adolescents. 1059 7

Osteoporosis is a common disease with a strong genetic component, characterized by reduced bone mineral density and increased fracture risk. Although the genetic basis of osteoporosis is incompletely understood, previous studies have identified a polymorphism affecting an Sp1 binding site in the COLIA1 gene that predicts bone mineral density and osteoporotic fractures in several populations. Here we investigated the role of COLIA1 genotyping and bone densitometry in the prediction of osteoporotic fractures in a prospective, population-based study of men (n = 156) and women (n = 185) who were followed up for a mean (+/- SEM) of 4.88+/-0.03 years. There was no significant difference in bone density, rate of bone loss, body weight, height, or years since menopause between the genotype groups but women with the 'ss' genotype were significantly older than the other genotype groups (p = 0.03). Thirty-nine individuals sustained 54 fractures during follow-up and these predominantly occurred in women (45 fractures in 30 individuals). Fractures were significantly more common in females who carried the COLIA1 's' allele (p = 0.001), although there was no significant association between COLIA1 genotype and the occurrence of fractures in men. Logistic regression analysis showed that carriage of the COLIA1 's' allele was an independent predictor of fracture in women with an odds ratio (OR) [95% CI] of 2.59 [1.23-5.45], along with spine bone mineral density (OR = 1.57 [1.04-2.37] per Z-score unit) and body weight (OR = 1.05 [1.01-1.10] per kilogram). Moreover, bone densitometry and COLIA1 genotyping interacted significantly to enhance fracture prediction in women (p = 0.01), such that the incidence of fractures was 45 times higher in those with low BMD who carried the 's' allele (24.3 fractures/100 patient-years) compared with those with high BMD who were 'SS' homozygotes (0.54 fracture/100 patient-years). We conclude that in our population, COLIA1 genotyping predicts fractures independently of bone mass and interacts with bone densitometry to help identify women who are at high and low risk of sustaining osteoporotic fractures.
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PMID:Prediction of osteoporotic fractures by bone densitometry and COLIA1 genotyping: a prospective, population-based study in men and women. 1130 20


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