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Query: UMLS:C0205700 (ash)
 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lumbar spine of 14 cadavers was studied both by 153Gd dual photon absorptiometry (DPA) and quantitative computed tomography (QCT) at 96 and 125 kVp. The intact spine and the individual vertebrae were analyzed. After these measurements the ash content of the vertebral body, the posterior elements, and the transverse processes was determined. The fat content of the vertebral body as well as its volume was also measured. With DPA, the bone mineral content (BMC) determined in situ as well as on excised spine specimens correlated highly with the amount of total vertebral ash (r greater than 0.92, SEE less than 3.2 g). The bone mineral density (BMD, area density) of 3 lumbar vertebrae correlated accurately with the mean ash density of the vertebral body (r greater than 0.81, SEE less than 0.015 g/cm3). The so-called corpus density and central density determinations were less accurate. No difference in accuracy was found between measurements when using 3 mm and 4.5 mm step intervals. Variations in the distribution of mineral between the vertebral body and the posterior elements contribute to the error in predicting vertebral body mineral with DPA. QCT gave a smaller error when a cylindric portion of the vertebral body with a 20 mm diameter was measured compared with one with a 9 mm diameter, when the dual energy technique was used (p less than 0.01). With dual energy QCT a correlation was found between a center segment of 3 vertebrae in the lumbar spine and the mean ash density of the vertebral body of r = 0.92 (SEE = 0.010 g/cm3).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vertebral bone mineral measurement using dual photon absorptiometry and computed tomography. 296 52

An ash study was performed to analyze the accuracy of forearm measurements at the one-third site of three dual x-ray absorptiometry (DXA) systems using 20 cadavers. A Hologic QDR-2000, a Hologic QDR-1000/W, and a Lunar DPX-L system were used. The correlations between ash weight and DXA BMC were excellent for the three instruments (r > 0.97, p < 0.001), with accuracy errors < 5.2%. To perform a forearm cross-calibration of bone mineral content (BMC) and density (BMD) between the scanners, 10 healthy volunteers were additionally scanned at the distal one-third radius. The correlations among the DXA machines were excellent (r > 0.95); the absolute BMC and BMD values were significantly different between the two Hologics and the Lunar machine. The slope and intercept of both the BMC and BMD between the two Hologic systems were close to unity. In conclusion, the DXA forearm software packages provide accurate methods for assessing bone mineral content and density. The conversion of data among different manufacturers should be performed by careful cross-calibration measurements.
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PMID:Dual x-ray absorptiometry forearm software: accuracy and intermachine relationship. 781 26

Bone densitometric measurements are widely used for monitoring therapeutic regimens for osteoporosis. However, it is a matter of debate which measurement site is most appropriate for prediction of individual fracture risk. The aim of this cross-sectional study was to investigate the relationship between bone mineral measurements at various sites and spine deformity index (SDI) in osteoporotic women. The SDI was determined in 37 osteoporotic women aged 56-87 years (mean 70.9 years). Peripheral (single-photon absorptiometry of the distal forearm, and iliac crest ash content) and axial (dual-photon absorptiometry of the lumbar spine) bone mass measurements were obtained. SDI increased with age (r = 0.34, p < 0.05), whereas forearm BMC (r = -0.52, p < 0.002) and forearm BMD (r = -0.62, p < 0.0001) decreased. No significant age-related changes were observed in lumbar BMC or iliac crest ash content in these osteoporotic women. A highly significant correlation was found between SDI and lumbar BMC (r = -0.60, p < 0.01). A significant, but less pronounced correlation was found between SDI and forearm BMC (r = -0.37, p < 0.05), whereas no relation was revealed between SDI and forearm BMD or iliac crest ash content. In a multiple regression model, the relationship between lumbar BMC and SDI remained significant after adjusting for the influence of age, whereas the relationship to forearm BMC disappeared. Furthermore, a multiple regression analysis was performed in order to evaluate the ability of all four bone mass measurements and age to predict variations in SDI.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Spine deformity index in osteoporotic women: relations to forearm and vertebral bone mineral measurements and to iliac crest ash density. 794 51

In several clinical osteoporosis studies, fluoride treatment has been shown to have a positive effect on bone mass but without a concomitant decrease in vertebral fracture rate. In contrast, some studies have shown that increases in spinal BMD are also paralleled by decreased vertebral fracture incidence. We have previously demonstrated, in a pig model, that 6-month treatment with fluoride increased bone mass but decreased bone quality. The aim of the present study was to elucidate whether normal age-related fluoride accumulation in human bone per se influences bone quality. From 73 normal individuals, aged 20-91 years (36 females, 37 males) two trabecular bone cylinders were obtained from the central part of L3. Biomechanical competence, ash density, and fluoride content were assessed in one cylinder, and trabecular bone volume was determined in the other. The results showed an age-related decrease in bone mass for both men and women. Bone strength normalized for bone mass (bone quality also identical with bone material strength) also showed an age-related decrease in men and women. Bone fluoride concentration increased significantly in both sexes (range 463-4000 ppm). Multiple regression analyses disclosed that fluoride by itself had no influence on bone quality, in this study with a limited number of cases, when the influence of sex and age were taken into account. It is concluded that normal age-related accumulation of fluoride in vertebral trabecular bone does not seem to affect the quality of bone. Whether this is also the case during fluoride therapy has to be assessed.
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PMID:Normal age-related changes in fluoride content of vertebral trabecular bone--relation to bone quality. 802 46

We evaluated the precision and accuracy of dual-energy x-ray bone densitometry (DXA) in 38 male and female rats aged 1-10 months. The coefficients of variation (CV) estimated from same-day paired measurements of bone mineral content (BMC) were 1.26% at the lumbar spine and 0.69% at the whole skeleton, and the corresponding CV for BMC corrected for projected bone area (i.e., bone mineral density, BMD) were 0.57 and 0.66%. BMC, measured in vivo, correlated closely with the subsequently determined ash weights (spine r2 = 0.94, whole-skeleton r2 = 0.97). The long-term CV for BMC measurements, assessed by measuring a frozen animal daily for 4 weeks, were 1.28% for the spine and 1.03% for the whole skeleton; for BMD the corresponding CV were 0.88 and 1.15%. To examine the utility of serial DXA measurements we followed female rats subjected to ovariectomy (OVX) or sham operation at 10 months of age and male rats given daily subcutaneous injections of hPTH-(1-34) or vehicle starting at 10 months of age every 3 weeks for 15 weeks. In the OVX rats a progressive decrease in spine BMC was observed that was most rapid during the first 6 weeks. By 15 weeks the mean spine BMC decreased by 17% in the OVX rats (p < 0.007 versus sham operation). OVX did not affect the accuracy of DXA measurements as assessed by comparison with the ash weight at the end of the 15 week study. PTH treatment increased spine BMC by a mean of 32% and increased whole-skeleton BMC by a mean of 19% within 15 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Accuracy, precision, and utility of spine and whole-skeleton mineral measurements by DXA in rats. 815 5

Effects of androgen deficiency and androgen replacement on bone density, as measured with dual-energy X-ray absorptiometry (DXA) and single photon absorptiometry (SPA), cortical ratio (cortical thickness/outside bone diameter x 100), and biomechanical properties were evaluated in 14-month-old (1 month after orchiectomy (orch) or sham-operation) and in 17-month-old (4 months after orch or sham) male rats. Whole femoral bone mineral content (BMC) and density (BMD) measured with DXA were not significantly decreased 1 month after orch. Whole femoral BMC and BMD were 10% and 8% lower in 4 months after orch (P < 0.01 and P < 0.001, respectively). This decrease was prevented by testosterone replacement. There was an excellent correlation (R = 0.99) between whole femoral BMC and femoral ash weight. Selective scanning of cortical and cancellous sites of the femur showed that both cancellous and cortical BMC and BMD were significantly decreased 4 months after orch. SPA of the right tibia confirmed a 7% decrease in cancellous BMC and BMD 4 months after orch (preventable by testosterone) but not in cortical BMD and BMC. Femoral cortical ratio decreased with age (47 +/- 2 in 14-month-old and 40 +/- 2 in 17-month-old sham rats versus 63 +/- 1 in 6-month-old male rats) due to a continuously enlarging femoral shaft. Androgen deficiency resulted in an even greater decrease of the cortical ratio 4 months after orch (36 +/- 2 in 17-month-old orch rats) that was again prevented by testosterone (47 +/- 3).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The aged male rat as a model for human osteoporosis: evaluation by nondestructive measurements and biomechanical testing. 828 23

In mature rats experiencing 14-day head-down suspension or 14-day head-down suspension followed by 28-day reambulation, the hindlimb long bones, humerus, and skull were removed for the determination of morphometry and bone mineral content (BMC) and density (BMD) with dual-energy X-ray absorptiometry, dry and ash weights, and calcium content. The bones of the animals in the control groups (killed at days 0, 14, and 42) had their own maturation rate. The body weights of suspended animals were lower than those of the control animals. Suspension does not appear to impair the long-bone elongation rate. However, the tibia of suspended rats exhibited a lower calcium content, ash weight, BMC, and BMD. Similar trends were observed in the femur. In the humerus, no significant change was observed. In the skull, the values of the suspended rats were similar to those of the control rats. At the end of the reambulation period, the body weights showed no difference between the control and experimental animals. The bone alterations were not completely reversible compared with their respective controls. In the tibia, BMC and BMD were always decreased. In the femur, trends toward low values were still visible. The skull showed a decrease in BMC and ash and dry weights. This unexpected finding suggested that importance of a rapid decrease in cephalad fluid shift at the time of desuspension. Finally, we showed that dual-energy X-ray absorptiometry measurement is sufficiently accurate to detect intergroup differences.
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PMID:Bone changes in 6-mo-old rats after head-down suspension and a reambulation period. 859 97

Ipriflavone (i.p.) positively affects bone density in postmenopausal osteoporosis, primarily by inhibiting bone resorption. Using in vitro models of human osteoblast differentiation, we have observed that i.p. and some of its metabolites stimulate the expression of bone sialoprotein, decorin, and type I collagen, and facilitate the deposition of mineralized matrix. This suggests that i.p. may stimulate bone formation in addition to its antiresorptive activity. To assess whether these effects translate into an improved bone "quality" in vivo, we measured biomechanical properties, mineral composition, and crystallinity of femurs of 12-week-old, male, Sprague-Dawley rats treated with i.p. for 1 month. i.p. significantly decreased vibration damping, an index of strain energy loss. Because vibration damping increases as bone porosity increases, the results indicate that i.p.-treated bones acquired a higher capacity to withstand dynamic stress. In fact, 1.5-fold higher energy was required to fracture femurs of i.p.-treated rats after a single supramaximal impact. i.p. also increased BMD, assessed by both volume displacement and ash analysis, whereas the relative contents of Ca, P, and Mg in the ashes were not affected. Thus, no gross abnormalities in mineral composition of bone occurred after i.p. administration. As a measure of bone crystallinity, X-ray diffraction analysis was performed. The broadening parameter beta 1/2 for the (310) and (002) reflections was not significantly different between i.p.-treated and control animals. Similarly, there were no differences in serum levels of Ca, Mg, alkaline phosphatase, and type I collagen telopeptides between treated and control animals at the end of the study. Therefore, 1-month treatment with i.p. increased bone density and improved the biomechanical properties of adult male rat bones without altering mineral composition or bone crystallinity.
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PMID:In vitro and in vivo effects of ipriflavone on bone formation and bone biomechanics. 926 10

Widespread osteoporosis testing and diagnosis are currently limited due to the high capital cost and reduced portability of many existing bone densitometry techniques. In this study we evaluated an inexpensive, low radiation, X-ray-based technique for assessing bone density of the middle phalanx. The technique, termed computed digital absorptiometry (CDA), is similar to radiographic absorptiometry (RA), using a single-energy X-ray source, an aluminum alloy step-wedge, and a charge-coupled device (CCD) detector system to automatically compute bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2) in the middle phalanx of the third finger. The potential advantage of CDA over current RA techniques is that by using a filmless detector system, no off-site processing of radiographs is required and bone density results are obtained immediately after the test. Using human cadaveric specimens we determined the accuracy and short-term precision of CDA as well as its correlation with other hand and forearm bone densitometry methods. We obtained 26 cadaveric forearms (50% female, mean age 78 years, range 52-96 years). BMC and BMD of the middle phalanx of the third finger were determined using CDA and using RA. We assessed forearm BMC and BMD using single-energy and dualenergy X-ray absorptiometry (SXA and DXA). Precision of CDA was assessed by measuring ten of the specimens five times each with repositioning between measurements. Finally, the middle phalanx was dissected and incinerated to determine ash weight. BMC estimates from CDA and from RA were strongly correlated with ash weight (r = 0.89, p < 0.001 and r = 0.93, p < 0.001, respectively). The mean coefficients of variation using CDA were 1.36% and 0.70% for phalanx BMC and BMD, respectively. BMC and BMD measured by CDA were strongly correlated with hand and forearm bone mineral measurements performed by SXA, DXA and RA (r = 0.74-0.91). These results indicate that CDA accurately and precisely predicts BMC of the middle phalanx. Thus, with further clinical verification, this technique may prove to be a useful tool for the widespread testing and assessment of osteoporotic fracture risk.
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PMID:Precision and accuracy of computed digital absorptiometry for assessment of bone density of the hand. 942 2

Lean body mass (LBM), total body bone mineral mass (BMC), total body bone areal density (BMD), and body fat mass (FM) were measured in rats by dual photon absorptiometry (DXA), using two different instruments. The coefficients of variation for repeated measurements of LBM and FM were about 0.4 and 2.5%, respectively, over an animal body weight range of 150 to 600 g. For BMC and BMD, the coefficients of variation were less than 2%. The correlation coefficients for LBM, FM, BMC, and BMD measured on the two densitometers were all greater than 0.94. The slope of the regression line relating LBM measured by DXA and LBM measured by carcass analysis was 0.999, and the correlation coefficient was 0.99. For FM the slope was 1.05, and the correlation coefficient was 0.98. BMC measures by DXA were falsely low in small animals. For larger animals, the correlation between BMC and ash weight was 0.93, but the slope of the regression line was 0.78. DXA measures of LBM and FM were accurate and reproducible for rats weighing between 150 and 600 g. There was a size-dependent error in BMC, which will be significant in longitudinal measurements of bone mass.
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PMID:Precision and accuracy of total body bone mass and body composition measurements in the rat using x-ray-based dual photon absorptiometry. 943 51


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