Search

We studied the effect of boron supplement on experimental osteopenia caused by strenuous exercise in 93- d-old female Wistar rats. A control group of 15 rats was not manipulated. The exercise group of 30 rats was divided into 2 groups of 15 rats each, one that was fed a diet supplemented with 50 mg/kg of boron in the form of Na(2)B(4)O(7), and other that, did not receive a boron supplement. The length and weight were determined in the femur and fifth lumbar vertebra and the bone mineral content and density were assessed through densitometry, and trabecular bone volume, trabecular number, trabecular thickness, and trabecular separation with histomorphometry. The femur length and weight, and vertebra weight, and femur and vertebra bone mineral content and density were significantly lower and the trabecular separation was higher in the exercise group than in the others (p < 0.005 in all). The femur weight, bone mineral content and density, trabecular bone volume and trabecular thickness, were significantly higher in the exercise plus boron group (p < 0.005 to 0.0001). It was concluded that boron preserves bone mass in rats that have been exposed to intense exercise.

Weight and gonadal status are the main determinants of bone mass in women. Because of this it is important to study which influences it more. The effect of weight (expressed as body mass index, BMI) and gonadal status of women on total-body bone mineral content (TBBMC) and regional bone mineral content (BMC) was investigated. A total of 373 normal women (mean age 48.9 +/- 13.4 years) were studied: 171 postmenopausal women (mean age 59.3 +/- 9.5 years; years since menopause 11.3 +/- 6.7 years); 76 perimenopausal women (mean age 48.9 +/- 2.2 years); and 126 premenopausal women (mean age 34.7 +/- 7.4 years). In all the women, TBBMC and regional BMC were determined by dual-energy X-ray absorptiometry. Also biochemical markers of bone metabolism (total alkaline phosphatase and tartrate-resistant acid phosphatase) and serum estrone and estradiol were determined. When the women were stratified by gonadal status and BMI, thin women (BMI <20 kg/m2) had significantly lower TBBMC and regional BMC, lower gonadal steroid concentration and higher levels of biochemical markers than overweight (BMI 25-30 kg/m2) and obese (BMI >30 kg/m2) women, regardless of gonadal status. Overweight and obese women had findings suggestive of increased parathyroid activity, but greater bone mass. Weight rather than gonadal steroid concentration is the main determinant of bone mass in women regardless of gonadal status.

Objective: After tubal ligation, normal bone mass in the presence of gonadal deficit has been reported. These incongruent results motivated us to examine the topic., Study Design: Bone mass was assessed by densitometry and ultrasonography 60 days after surgery on 100-day-old female Wistar rats. Fifteen Wistar rats with uterine horn ligation (TL) were compared with 15 unoperated, 15 with a sham uterine horn ligation (Sham-TL), and 15 ovariectomized (OVX), using ANOVA and a correlation test to determine the relations between results., Results: Femoral and vertebral bone mass were significantly lower in the OVX y TL groups than in unoperated and controls groups (P<0.0001)., Conclusions: Our study revealed significantly lower axial and peripheral bone mass in rats with uterine horn ligation.

Study Design: A cross-sectional study., Objective: To clarify the existing controversy with regard to whether paraplegic patients suffer a loss of bone mass in the upper limbs., Setting: Madrid, Spain., Methods: We evaluated bone mass by phalangeal ultrasonography in 35 male patients with paraplegia (mean age 49+/-12 years), and 25(OH)D3 and PTH to exclude the presence of osteomalacia and secondary hyperparathyroidism. Spasticity was evaluated according to the Ashworth scale. Patients were compared with a control group of 35 healthy male subjects (mean age 48+/-13 years)., Results: The patients had lower 25(OH)D3 levels and amplitude-dependent speed of sound (Ad-SOS) than controls (both P<0.001), and higher PTH levels (P<0.05). There was a statistically significant negative association between PTH and 25(OH)D3 levels (r=-0.52, P<0.0001, CI -0.73 to -0.22) and between 25(OH)D3 and injury duration (r=0.34, P<0.05, CI -0.60 to -0.01). There was no correlation between Ad-SOS values, levels of PTH or 25(OH)D3, and the injury duration. No significant difference in Ad-SOS values was found in patients grouped according to low-to-normal 25(OH)D3 level or according to normal-to-high PTH level. There were no differences in relation to muscle tone. Only alkaline phosphatase and tartrate-resistant acid phosphatase levels were higher in patients than in controls (both P<0.001)., Conclusion: Paraplegic patients had a loss of phalangeal bone mass that was unrelated to the levels of vitamin D or PTH, or to muscle tone, so it seems to be related to increased bone resorption rather than to deficient bone formation.

Rationale and Objectives: In an experimental study in 40 rat femurs, the authors correlated the amplitude-dependent speed of bone ultrasound (Ad-SOS) with the bone mineral content and density and with the bone trabecular connectivity: trabecular bone volume, trabecular number, trabecular thickness, and trabecular separation to evaluate and compare the usefulness of the Ad-SOS to determine bone quantity and/or quality., Methods: Bone mineral content and density were determined with dual-energy x-ray absorptiometry. Trabecular connectivity was determined with histomorphometric techniques., Results: There was a strong correlation between the Ad-SOS and the other parameters studied, with a particularly high positive correlation with trabecular bone volume and trabecular thickness, and an inverse correlation with trabecular separation. The correlation was weaker with the bone mineral content and bone mineral density and with the trabecular number. For the trabecular separation, the correlation was significant in all cases, but it was negative., Conclusions: Bone ultrasound, in this case Ad-SOS, defines the quality of the bone in terms of trabecular architecture rather than bone density; however, this conclusion is valid only for the rat femur model that the authors used.

Aims: The influence of eating habits on bone mass is a controversial topic. We have use ultrasound to search for the relationships between nutrients and bone density., Methods: A total of 228 women (mean age 48.9 +/- 13.7 years) were studied, and divided according to their gonadal status (pre-, peri- and postmenopausal women). The dietary intake was recorded for 7 days, and their bone mass was measured by phalangeal amplitude-dependent speed of sound (Ad-SOS). ANOVA was made to examine the differences according to gonadal status. To determine the possible correlation between Ad-SOS and nutrient intake, partial correlations, adjusted for important confounding variables, were done., Results: With partial correlations, there was no correlation of Ad-SOS with the nutrients studied here., Conclusion: We find no correlation of bone mass as measured by Ad-SOS with the most common nutrients and trace minerals, either for the participants as a whole or according to gonadal status., (Copyright 2001 S. Karger AG, Basel)

Objective: The effect of a copper supplement on preventing bone mass loss induced by ovariectomy in rats was investigated., Design: Three groups of fifteen 100-day-old female Wistar rats, each with a mean initial weight of approximately 260 g per animal, were selected for a 30-day experiment. One group of 15 ovariectomized rats was fed a diet supplemented with 15 mg of copper per kilogram of feed. The other two groups: 15 ovariectomized and 15 Sham- ovariectomized rats did not receive the supplement. Morphometric (weight and length) and densitometric studies with dual-energy x-ray absorptiometry were performed on the whole femur and the fifth lumbar vertebra of each animal at the end of the 30-day period., Results: The ovariectomized rat group fed a diet supplemented with copper did not show the bone mass loss at the axial (fifth lumbar vertebra) or peripheral (femur) level that was evidenced in the ovariectomized group., Conclusions: The results of the measurement of axial and peripheral bones show that a supplement of copper may have a potential therapeutic application in the treatment and prevention of involutional osteoporosis.

Objective: This paper studied the influence of several gynecological factors (years since menopause (YSM), age at menarche and gynecological age or reproductive life) simultaneously with anthropometric factors as determinants of bone mass in 189 healthy postmenopausal women., Methods: Bone mass was determined by peripheral quantitative computed tomography., Results: An overall evaluation showed that YSM correlated negatively with trabecular and cortical bone density (BMDTrab and BMDCorti) (P<0.05 in both cases). Age at menarche correlated negatively with BMDCorti (P<0.05) and gynecological age correlated positively with BMDTrab (P<0.05). Classifying the women according to their body mass index (BMI), the YSM correlation persisted in those subjects whose BMI was >25 kg/m(2), and in age at menarche and gynecological age of women whose BMI was <25 kg/m(2) (P<0.05). After separating women according to their age at menarche, their gynecological age and BMI, the only significant difference that persisted was in BMDTrab which was lower in the group with gynecological age <33 years, with a BMI <25 kg/m(2) (P=0.020). Parity and smoking had no impact on our results. By multiple regression, with BMD as the dependent variable and the gynecological factors as independent variables, we only observed significance between YSM and BMDCorti (P<0.005). The same was observed after separating women according to their BMI in the >25 kg/m(2) group (P<0.05)., Conclusions: Our data stress the importance of YSM on BMDTrab and BMDCorti, of age at menarche on BMDCorti and of gynecological age on BMDTrab. However, YSM is the gynecological factor that mainly determines BMD. The differences observed between measurements taken with pQCT and other methods commonly used to estimate bone mass indicate that results obtained with one technique cannot be extrapolated to other methods.

Objective: The aim of this study was to examine the effect of manganese (Mn) alone and with the addition of copper (Cu) in the inhibition of osteopenia induced by ovariectomy (OVX) in rats. STUDY CONDITIONS: Four lots of 100-day-old female Wistar rats were divided into experimental groups of 15 each. One group received a diet supplemented with 40 mg/kg of Mn per kilogram of feed (OVX+Mn). The second group received the same diet as the first, but with an additional 15 mg/kg of copper (OVX+Mn+Cu). The third group of 15 OVX and the fourth group of 15 Sham-OVX received no supplements. At the conclusion of the 30-day experiment, the rats were slaughtered and their femurs and fifth lumbar vertebrae were dissected. Femoral and vertebral length were measured with caliper and bones were weighed on a precision balance. The bone mineral content (BMC) and bone density (BMD) of the femur (F-BMC, mg and F-BMD, mg/cm(2)) and the fifth lumbar vertebra (V-BMC, mg and V-BMD, mg/cm(2)) were measured separately with dual energy X-ray absorptiometry., Results: The F-BMD, mg/cm(2) was lower in the OVX than in the Sham-OVX group (P<0.0001) and in the other two groups receiving mineral supplements (P<0.005 in both). F-BMC, mg was significantly lower in the OVX group than in the other three (P<0.0001 in all cases). Calculations for V-BMC, mg and V-BMD, mg/cm(2) are similar to findings in the femur., Conclusions: These data show that a Mn supplement is an effective inhibitor of loss of bone mass after OVX, both on the axial and the peripheral levels, although this effect is not enhanced with the addition of Cu.

The effect of silicon (Si) supplement on preventing bone mass loss induced by ovariectomy (OVX) in rats was investigated. Three groups of 15, 100-day-old female Wistar rats each, with a mean initial weight of approximately 260 g per animal, were selected for the present study. One of the experimental group consisting of 15 OVX rats was fed a diet supplemented with 500 mg of Si per kg of feed (Si + OVX). The other two groups consisting of 15 OVX and 15 sham-OVX rats did not receive these supplements. Morphometric (weight and length) and densitometric studies with dual-energy X-ray absorptiometry were performed on the whole femur and 5th lumbar vertebra of each animal 30 days after the experiment. The Si + OVX rats did not show a loss of bone mass induced by OVX at axial level (5th lumbar vertebra) or periphery (femur). Nonetheless, a significant increase (ANOVA with Bonferroni/Dunn post hocs test) of longitudinal development of the femur (P < 0.0001) was patent. These results, obtained through the measurements of axial and peripheral bones, warrant closer scrutiny in connection with the Si inhibitory effect on bone mass loss as well as the stimulatory effect on bone formation. Both actions, namely, inhibition of resorption and stimulation of formation, infer that Si may have a potential therapeutic application in the treatment of involutive osteoporosis.

The ability of alprazolam to diminish cortisol response and favor ovarian function could make it useful in the prevention of osteopenia in athletes in selected cases. A sample of 45 female Wistar rats, all 93 days old and with a mean initial weight of 267 +/- 17 g, were studied. Rats were exposed to a high-performance level of exercise and were divided into two groups-one group received an alprazolam supplement and one did not-and compared with controls to determine the effect of alprazolam on bone mass as measured by dual-energy X-ray absorptiometry (DKA). Exercise consisted of treadmill running on 5 out of 7 days during a period of 11 weeks. A steep grade treadmill inclination was used to stimulate high-intensity muscle activity. Final inclination was 17.5 degrees and treadmill speed was 45 cm/second. Upon completion of the experiment, all the rats were killed and the femur and 5th lumbar vertebra were dissected and cleaned. Length, weight, bone mineral content (BMC), and density (BMD) of the whole right femur and 5th lumbar vertebra were measured. In the exercise only group (no alprazolam), the length, weight, BMC, BMD, and femur BMC/final rat weight ratio of the femur, and the vertebral weight, vertebral BMD and BMC, and vertebral BMC/final rat weight ratio were lower than in the control and the exercise-alprazolam groups (P < 0.0167 - < 0.0001). Alprazolam preserves bone mass in rats exposed to intense exercise.

Objective: To evaluate the effect of surgical uterine retroversion on bone mass in rats., Study Design: Forty-five female Wistar rats were assigned randomly to three groups: 15 unmanipulated rats, 15 rats that underwent uterine retroversion, and 15 rats that underwent sham uterine retroversion (exposure of the uterus to air followed by closure of the abdominal cavity). Sixty days later the rats were killed and their femurs were dissected. Femurs were weighed and measured, and femoral bone mineral content (BMC) and bone mineral density (BMD) were determined by dual energy X-ray absorptiometry., Results: In the group of rats that underwent uterine retroversion, BMC, BMD, and BMC corrected for final body weight were significantly lower (P<0.001) than in the unmanipulated control and sham uterine retroversion groups., Conclusion: Our findings indicate that uterine retroversion induced a loss of bone mass. We could not determine the mechanism of bone loss; in our opinion, these problem merits further investigations, which currently occupy our interest.

Objective: The T score of the cortical and trabecular bone compartments (T score of BMDTrab and T score of BMDCorti) was calculated in healthy postmenopausal women to determine which bone compartment loses more bone mass., Material and Methods: A total 134 healthy postmenopausal women (mean age 55.1 +/- 6.4 years) and 67 healthy premenopausal women (mean age 36.0 +/- 8.6 years) were studied. Determinations were made using peripheral quantitative computed tomography (pQCT) of the nondominant forearm. The postmenopausal women were divided into groups by years since menopause (YSM): two early postmenopausal groups: < 5 YSM and 6-10 YSM; and two late postmenopausal groups: 11-20 YSM and > 20 YSM., Results: There was a significant correlation between the T score of BMDTrab and the T score of BMDCorti (P < 0.0001). Both correlated negatively and significantly with age (P < 0.001 and P < 0.0001, respectively) and neither correlated with weight. The Wilcoxon test showed no significant differences between the trabecular and cortical T scores in the overall group of women. By YSM, only the > 20 YSM group showed significant differences (P < 0.005). The ANOVA post hoc Bonferroni/Dunn test showed a significant difference in the T score of BMDTrab by YSM only in the < 5 YSM versus 11-20 YSM groups (P = 0.007) and in the < 5 YSM versus > 20 YSM groups (P < 0.0001). The T score of BMDCorti by YSM differed significantly only between the < 5 YSM versus 11-20 YSM groups (P < 0.0001) and between the 11-20 YSM and > 20 YSM groups (P < 0.005)., Conclusion: In contrast with what has been postulated in recent studies, our results showed that postmenopausal bone loss was similar in the cortical and trabecular bone compartments in the first 20 years after menopause. Trabecular bone loss was greater than cortical bone loss in late menopause (> 20 years).

The hypothesis that a zinc (Zn) deficit may cause osteopenia in athletes is well founded. In rats exposed to strenuous exercise, we evaluated the effect of a zinc supplement on femoral and vertebral bone mass determined by dual-energy X-ray absorptiometry. Four lots of 93-day-old female Wistar rats were studied. A control group of 30 rats were not manipulated (Zn- Ex- group). The experimental group of 40 rats was fed a diet supplemented with an additional 20% of Zn/kg of feed; this group was divided into two groups of 20 rats each, one that did not exercise (Zn+ Ex-) and one that did (Zn+ Ex+). A group of 15 rats exercised but did not receive a zinc supplement (Zn- Ex+ group). Training consisted of treadmill running for 5 out of 7 days over an 11-week period. Initial speed, running time, and treadmill speed were increased gradually. Analysis of variance with the Bonferroni/Dunn test showed that the length, weight, bone mineral content (BMC), and bone mineral density (BMD) of the femur were less in the Zn- Ex+ group than in the others (p < 0.008), and the weight, BMC, and BMD of the fifth lumbar vertebra also were lower in the Zn- Ex+ group than in the others (p < 0.008). These findings confirm the adverse effects of strenuous exercise (treadmill running) on bone tissue in rats and the effectiveness of zinc supplementation in preventing it.

Three techniques of bone mass measurement were evaluated in the diagnosis of postmenopausal osteoporosis; the overlap in the measurements and the capacity for discriminating was determined among 51 postmenopausal normal (mean age 66.6 +/- 8.4 years) and 42 postmenopausal osteoporotic women (mean age 68.5 +/- 7.5 years). All bone mass was evaluated by total body bone mineral content (BMCTB), density (BMDTB), ultrasound bone velocity (UBV) in proximal phalanxes 2-5 of the nondominant hand (UBV = mean value of all ultrasound measurements), and peripheral quantitative computed tomography of the nondominant forearm (pQCT). BMCTB was found to be significantly better (P < 0.0001) for diagnosing postmenopausal osteoporosis than the other methods; both cortical and trabecular pQCT measurements were more discriminating than the corresponding UBV measurements (P < 0.001). T-score values in normals, subjects versus osteoporotic ones were BMCTB -1.15 +/- 0.79 versus -3.17 +/- 0.74; BMDTB -1.01 +/- 0.97 versus -3.28 +/- 0.81; UBV -1.51 +/- 1.02 versus -2.34 +/- 1.21; trabecular-pQCT -0.40 +/- 0.72 versus -1.57 +/- 0.37; cortical-pQCT -1.00 +/- 0.87 versus -2.67 +/- 0.53; and total-pQCT -0.65 +/- 1.01 versus -2.34 +/- 0.27, respectively. The overlap in values between the postmenopausal normal and postmenopausal osteoporotic groups was 50% with UBV, 6% with BMCTB, 9% with BMDTB, 25% with cortical pQCT, and 42% with trabecular pQCT. BMCTB, BMDTB, UBV, and pQCT correlated well with each other as measurements of bone mass, but BMCTB was more discriminating than the other measurements in the diagnosis of osteoporosis.

The influence of body mass index (BMI) on T scores for total body bone mineral content (TBBMC) and regional bone mineral content (RBMC) was studied in 186 healthy women: 100 postmenopausal, 35 perimenopausal, and 51 premenopausal. The three groups were divided by BMI >25 kg/m2 and BMI <25 kg/m2 and the postmenopausal women were further subdivided by years since menopause (YSM): <10, 10-20, and >20. Tartrate-resistant acid phosphatase (TRAP) concentration was higher in perimenopausal and postmenopausal women with BMI <25 kg/m2 (P < 0.001). T scores for TBBMC and for axial or peripheral RBMC differed (P < 0.05 in all) between women with BMI >25 kg/m2 and BMI <25 kg/m2. The rate of perimenopausal and postmenopausal age-related slope of BMC, as reflected in all measurements, differed with BMI. In the overall group of women, the T score for TBBMC correlated significantly with BMI (r = 0.46, P < 0.0001); this correlation increased when adjusted for age (r = 0.62, P < 0.0001). BMI correlated with TRAP only in postmenopausal women (r = 0.57, P < 0. 0001). Yearly TBBMC decline was twice as high in postmenopausal women with BMI <25 kg/m2 (P = 0.0004) than in those with BMI >25 kg/m2; the decline of trunk RBMC was more significant (P < 0.0001). These findings confirm the influence of BMI and gonadal status on bone mass.

Changes in total body bone mineral content (BMCTB) and density (BMDTB), and the T-score of BMCTB and (BMDTB) were evaluated in relation to the number of vertebral fractures in women with postmenopausal osteoporosis for the purpose of defining deviations in these parameters that could be predictive of the occurrence of vertebral fracture. The study group consisted of 62 women diagnosed with postmenopausal osteoporosis. All of them had two or more spinal fractures. Regression analysis of the number of fractures against each parameter studied indicated that the following were predictive of the risk of fracture: a reduction of -0.5 in the T-score of both BMCTB and BMDTB (P < 0.0001) and a loss of about 135 g of BMCTB or 0. 058 g/cm2 of BMDTB (P < 0.0001). The fact that such changes were found during the follow-up of women with osteoporosis highlights the importance of bone mass measurements during follow-up.

The effect of electromagnetic fields on bone is debated. In an experimental study of this effect, we compared two lots of growing female rates (both lots n = 15, age 3 weeks, average weight 23.2 +/- 3.3 g), one of which was exposed to a 3-mT, 100-Hz, Helmholtz-type electromagnetic field for 24 hours a day for 30 days, and the other of which served as the control. Bone development and bone mass were evaluated by morphometry, densitometry, and histomorphometry. The rats were killed at 30 days and weighed. The right femurs were dissected, measured, and weighed; bone densitometry was used to determine femoral bone mineral content (BMC) and density (BMD), and histomorphometry of the nondecalcified bone was used to determine trabecular bone volume (Cn-BV-TV%), number (Tb-N mm) and thickness (Tb-Th microm), intertrabecular space (Tb-Sp microm) and growth cartilage thickness (Gc-Th microm). In the rats exposed to the electromagnetic field, BMC and BMD (P = 0.019 and P = 0.002, respectively) and Cn-BV-TV, Tb-N, Tb-Th (P = 0.005, P = 0.036, and P = 0.027, respectively) all were decreased, whereas Tb-Sp was increased (P = 0.002). There were no significant differences in initial and final body weight, or in final femur weight, femur length, and GC-Th. These findings indicate that electromagnetic fields of the type used here reduced bone formation and increased bone resorption without affecting bone development in rats.

Eighty-one women were studied longitudinally to measure trabecular bone mineral density (BMDTrab) and cortical bone mineral density (BMDCorti) in the distal radius by peripheral quantitative computed tomography (pQCT) at intervals of about 1 year and to calculate the rate of percent change/year. Fifty-three women were naturally postmenopausal [mean age 63.3 +/- 5.3 years, age at menopause 50.7 +/- 3.8 years, 13 years since menopause (YSM)] and 28 had been ovariectomized (mean age 52.7 +/- 5.8 years, age at menopause 39.5 +/- 5.0 years, 13 YSM). There was no difference between groups (ANOVA) in the rate of percent change/years in BMDTrab (p = 0.692), but there was in BMDCorti (p = 0.020). When the women who had either gained or lost bone mass were compared (chi-square test), only BMDCorti differed significantly (p = 0.018). Considering > -2.5% change/years as the limit for rapid bone mass loss, BMDTrab values showed that 43% of the naturally postmenopausal women and 42.7% of the ovariectomized women had rapid bone loss (p ns). On the basis of BMDCorti values, 45% of the naturally postmenopausal women and 28.4% of the ovariectomized women had rapid bone loss (p = 0.018). Height, weight, body mass index (BMI), age, YSM, and years of reproductive life did not differ (ANOVA) between the women who gained or lost either BMDTrab or BMDCorti. Using Fisher's r to z and partial correlation adjusted for age and YSM of the percent change/year in BMDTrab and BMDCorti in the overall group and in each menopausal group, only BMDCorti differed.

Rationale and Objectives: The authors studied premenopausal, perimenopausal, and postmenopausal women to determine if ultrasound bone velocity (UBV) on proximal phalanges of women reflect bone changes related to gonadal status and age., Methods: A total of 166 healthy women-64 postmenopausal women (mean age 58.7 +/- 9.4 years), 41 perimenopausal women (mean age 49.5 +/- 2.9 years), and 61 premenopausal women (mean age 36.8 +/- 7.1 years)-were studied. All the women underwent UBV study of the 2nd to 5th proximal phalanges on the nondominant hand and the mean value of all ultrasound measurements was calculated., Results: The postmenopausal women had a UBV that differed significantly, one-way analysis of variance, from that of the perimenopausal women and premenopausal women (both P < 0.001). The UBV measurements of the perimenopausal women differed significantly from those of the premenopausal women (P < 0.01). Simple linear regression analysis of the relation between UBV and age showed that this was significant and negative in the overall group of women (r = -0.69; P < 0.0001), significant in the perimenopausal (r = -0.66; P < 0.001) and postmenopausal women (r = -0.69; P < 0.001) and nonsignificant in the premenopausal women (r = 0.08; P not significant). In the postmenopausal women, the correlation between UBV and years since menopause was larger (r = -0.71; P < 0.0001) than the correlation between UBV and chronological age., Conclusions: Ultrasound bone velocity of the phalanx, as a method for measuring changes in bone with age, has a precision that makes it possible to detect changes in bone mass in perimenopausal women and may perform similarly to other bone mass measurements.

In experimental studies of bone in rats, two morphometric indices reflecting bone density have been proposed, the bone robusticity index and bone weight/bone length index. In rats, the bone mineral content (BMC) and bone mineral density (BMD) of a selected bone can be determined using dual-energy X-ray absorptiometry (DXA); bone volume can be measured by histomorphometry and other techniques. This study was undertaken to compare two morphometric indices (bone robusticity and bone weight/bone length) with the results of DXA and histomorphometry. Forty female Wistar rats (100 days old, mean weight 239+/-12 g) were studied: 20 controls and 20 ovariectomized rats (OVX). The morphometric indices and BMD differed significantly (Friedman test) in the overall group of rats; no differences were observed in the control group, but significant differences were apparent in the OVX group (p<0.0001). The morphometric indices correlated more closely with BMC than with BMD; the femur length/ femur weight index had closer correlations than the robusticity index. Nonetheless, both morphometric indices differed significantly from BMD determined by DXA under abnormal conditions, which makes them unreliable for use in these circumstances.

Total body bone mineral content (TBBMC) and regional bone mineral content (BMC) was measured in the members of the Spanish National Dance Company (15 female, mean age 25.1 +/- 3.8 years, and 15 male, mean age 28.2 +/- 2.1 years) and in 30 controls (15 women, mean age 26.1 +/- 1.8 years, and 15 men, mean age 28.0 +/- 1.5 years). Ca, P, and Mg intake were greater in the group of ballet dancers than in controls analysis of variance (ANOVA, all P < 0.0001). BMC was similar in the group of ballet dancers and controls except in the trunk without pelvis (P < 0.001). Both male and female dancers weighed less than controls (P < 0.05). The BMC of the male dancers was less than that of male controls only in the trunk (P < 0.05) and in the trunk without pelvis (P < 0.005); BMC was lower in female dancers than in female controls only in the arms and in the trunk without pelvis (P < 0.05 and P < 0.005, respectively). TBBMC, adjusted for weight and age, was correlated partially with caloric intake (kcal/day) and with Ca, P, Mg, and Zn intake (g/day), and yielded significant differences between the dancers and controls only in P intake (P < 0.01), and between male dancers and male controls only in caloric intake and in Ca, P, and Zn intake (all P < 0.01, except for Ca, P < 0.05). The lower trunk bone mass observed in the female dancers is a risk factor for eventual osteoporosis.

Our objective was to study the changes in the bone mineral density of the cortical and trabecular compartments with different types of menopause. A total of 153 normal postmenopausal women (mean age 48 +/- 5 years) were studied. The women were divided into three groups based on mean age at menopause: early menopause (menopause before 43 years), normal menopause (menopause at 44-52 years), and late menopause (menopause after 52 years). The number of years since menopause was similar in all three groups (+/- 5 years). Cortical and trabecular bone mineral density was determined in all the women using peripheral quantitative computed tomography. Our results show that only the trabecular bone mineral density differed significantly among the groups (Kruskal-Wallis: P = 0.0029). The women with early menopause had a lower trabecular bone density than the women with normal and late menopause (P = 0.0019 and P < 0.0001, respectively). Among the women with early menopause, 22 had experienced menopause before the age of 40 and 25 after the age of 40; there were significant differences in trabecular bone mineral density between these two subgroups (P < 0.05). Trabecular bone mineral density, the only variable studied that varied among the groups, correlated significantly with the duration of reproductive life (simple linear regression: r = 0.340, P < 0.0001). In conclusion, these findings emphasize the importance of the duration of reproductive life as a determinant of bone mass in women.

Rationale and Objectives: We sought to determine the value of peripheral quantitative computed tomography (pQCT) in measuring bone mineral density., Methods: In 50 healthy, eugonodal premenopausal women, we correlated measurements of total bone mineral content (BMCTB), made with dual-energy X-ray absorptiometry (DXA), and bone mineral density, determined by pQCT., Results: The partial correlations, adjusted for weight and age, between BMCTB and cortical bone density, total bone density, and trabecular bone density were .71 (p < .0001), .63 (p < .0001), and .32 (p < .05), respectively., Conclusion: These results and the advantages of pQCT--providing precise bone density determinations for trabecular and compact bone separately, having a high spatial resolution that allows a "compartmental" analysis of bone structure, having a low coefficient of variation, and having a minimal radiation dose (< 5 mrem)--confirm the adequacy of using this method for bone mass studies.

We compared bone mass in premenopausal, perimenopausal, and postmenopausal women using peripheral quantitative computed tomography to measure separately cortical, trabecular, and total bone density. Trabecular bone density was lower (p < 0.05) in the perimenopausal women than in the healthy premenopausal women. In perimenopausal women, trabecular bone density showed a significant linear regression with age (r = 0.554, p < 0.001), but cortical bone density did not (r = 0.130, p = 0.447). The group of postmenopausal women had significantly lower bone mass in all three bone compartments than the premenopausal and perimenopausal women. These findings confirm the existence of a significant loss of trabecular bone mass in the perimenopausal period.

There is disagreement as to whether the loss of bone mass induced by GnRH agonists is reversible. In part, the differences of opinion might be attributed to the fact that the influence of weight and seasonal changes on bone mass is often overlooked. Taking into consideration weight and seasonal changes in bone mass, total (TBBMC) and regional body bone mineral content were measured in 38 women treated with GnRH agonists for 6 months for endometriosis or leiomyomata. Measurements were made at the onset of treatment, at 6 months of treatment and at 6 months after finishing treatment. TBBMC was corrected for body weight. Body weight had increased significantly at 6 months of treatment (P = 0.0175). Regional bone mineral content showed the following: limbs, no changes; head, significantly lower at 12 months than at baseline (P = 0.0036) and at 6 months (P = 0.0343) of therapy; trunk, significantly lower at 6 months (P = 0.0002) compared to baseline, but the values at 1 year were not significantly different from either the baseline or the 6-month values; pelvis, the same pattern of change as in the trunk (P = 0.0349). TBBMC was significantly lower at 6 months of treatment (P < 0.0001) and at 1 year (P = 0.0162). TBBMC adjusted for weight experienced the same changes as unadjusted bone mineral content (P < 0.0001 and P < 0.0009 at 6 months and 1 year, respectively). Our findings indicate that the bone mass lost with GnRH treatment had not been restored 6 months after discontinuing treatment.

Seventy-two postmenopausal osteoporotic women having more than one nontraumatic vertebral crush fracture were studied. Thirty-six of them, aged 68.8 +/- 1.2 years (18 +/- 4 YSM-years since menopause), were treated with 100 IU/day of salmon calcitonin i.m. plus 500 mg of elemental calcium for 10 days each month. The remaining 36 patients, aged 69.6 +/- 1.4 years (19 +/- 3 YSM), were given only 500 mg of elemental calcium for 10 days each month. All patients underwent clinical and analytical evaluation every 3 months. Radiological evaluation, assessment of vertebral deformities, and metacarpal radiogrammetry were done every 6 months. Densitometric measurements of total and regional bone mass were made every 12 months. At 24 months, the calcitonin group showed a 60% reduction in the number of new fractures and the group receiving only calcium had a 45% increase (P < 0.001). The incidence of vertebral fractures was 0.07 per patient-year in the group treated with calcitonin and 0.45 per patient-year in the group treated with calcium (P < 0.001). At 2 years, the calcitonin group showed a 12% increase in cortical bone mass on metacarpal radiogrammetry, a 16% increase in the axial skeleton on trunk densitometry, a 3.5% increase in total body bone mineral content, a 30.7% increase in pelvic bone mineral content, and a 6.2% increase in arm bone mineral content (all P < 0.001). In the group treated with calcium alone there was a loss of bone mass in every region. These findings suggest that salmon calcitonin is effective in the treatment of osteoporosis and show that it acts on cortical and trabecular bone.

The effect of sports activity on bone mass was assessed by dual-energy X-ray absorptiometry in a group of 22 young cyclists aged 16.2 +/- 0.7 years. These athletes trained for 10 hours a week for over two years. Bone mass values were compared with those of 27 sedentary youngsters aged 16.9 +/- 0.3 years. There were no differences in total body bone mineral (TBBM) between groups. The leg bone mineral content (LBMC), body weight, and percentage fat were lower in the cyclists than in controls (p < 0.02, p < 0.01, and p < 0.001 respectively). No changes were observed when TBBM was normalized for weight. The changes observed earlier in LBMC disappeared when normalized for body weight. These results suggest that cycling does not stimulate bone mass in youngsters, and that the type, quality, and length of sports activity need to be defined.

Bibliographic references seem very controversial regarding the most appropriate anatomical area for bone mass estimation. Since some overlapping in the different bone mass measurements among normal and osteoporotic females has been observed, we have studied the bone mineral content of the pelvic bone through DEXA, and have correlated it with the total body bone mineral content, a highly discriminating measure, in order to observe whether pelvic bone mineral may be a useful measure in bone mass assessment. Pelvic and total body bone mineral values did not decrease until menopause in 104 normal premenopausal females aged 20 to 49 years. On the other hand, these values decreased in normal postmenopausal women (n = 44) aged 50 to 65 years (p < 0.001), with a 16% pelvic bone mineral content and an 11% total body bone mineral content decrease. Osteoporotic females (n = 30), showed lower values for both levels than normal postmenopausal ones (p < 0.001), with a 54% pelvic and a 24% total decrease. A 15% overlap was observed when pelvic values between normal postmenopausal and osteoporotic females were compared. The greater percentage decrease in pelvic BMC compared to total body bone mineral content and the lower overlap observed suggest that the pelvis may be an ideal anatomical area for bone mass evaluations.

Considerable debate exists about when the maximal bone mass, or "bone mass peak" is physiological acquired. In the present study, 140 normal females aged 15 through 19 years (n = 18), 20 through 29 years (n = 58) and 30 through 39 years (n = 64), were assessed in order to determine their total body bone mineral (TBBM) content, as bone mass parameter, by bone densitometry with dual energy X rays. We did not observe significant differences in TBBM values between the different groups. A positive and significant correlation existed between age and TBBM (r = 0.486, p less than 0.05) in female aged 15 to 19 years but not in the rest of the groups. These data suggest that female acquired their maximal bone mass, or bone mass peak, up to the age of 20 years and that it remains stable until, at lest, the age of 39 years. We point up the importance of achieving an adequate skeletal development in females during their first 20 years of life that could perhaps protect them from suffering subsequently from osteoporosis.