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

The accuracy of a radiographic absorptiometry (RA) technique called digital image processing (DIP), discriminative ability of RA for osteoporotic fracture, and the relationship between RA and dual X-ray absorptiometry (DXA) of the spine and forearm were evaluated. We measured 16 cadaver hands, 32 healthy non-black premenopausal women, 39 healthy non-black postmenopausal women, and 35 non-black osteoporotic postmenopausal females. The overall correlation between the ash weights of the entire metacarpal and the DIP values was excellent (r = 0.954, P < 0.001, SEE = 0.14, CV = 6.4%). Short-term precision error of DIP was 3.5%. Age-related bone loss determined by DIP is comparable to that of spinal and forearm DXA: annual BMD decreases were 0.46% for DIP, 0.45% for forearm, and 0.32% for the spine. DIP of the 2nd metacarpal shows a gradient of risk for spinal fracture only slightly below that of forearm DXA, but substantially below that of spinal DXA. Age-adjusted odds ratios were 1.81 for RA, 2.45 for spinal DXA, and 1.94 for forearm DXA.
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PMID:Accuracy and diagnostic sensitivity of radiographic absorptiometry of the second metacarpal. 943 40

Humans with prolactinoma are at risk for osteoporosis. The relative contributions of hyperprolactinemia-induced hypogonadism and the prolactin (PRL) excess per se have been unclear from clinical studies. To determine the effects of PRL excess, two models of chronic hyperprolactinemia were used. In one, mild hyperprolactinemia was produced in rats bearing extra anterior pituitary glands under the kidney capsule. Severe hyperprolactinemia was produced by subcutaneously transplanting the PRL-secreting MMQ tumor into other rats. To control for estrogen deficiency, the rats were ovariectomized. In some experiments, estrogen replacement was provided. Urinary calcium excretion was increased in hyperprolactinemic rats compared with controls, regardless of severity of PRL excess and estrogen status. This suggested that PRL excess itself had some effect on calcium balance. More importantly, however, the spinal bone mineral density (BMD; measured by dual-energy x-ray densitometry) of mildly hyperprolactinemic ovariectomized rats was the same as control ovariectomized rats. Similarly, tibial dry weight and ash weight were affected by the estrogen status, but not by the severe PRL excess of the tumor-implanted rats. Thus, despite the evidence for an increase in urinary calcium excretion in hyperprolactinemic rats, estrogen deficiency is much more important in determining bone mineral. Therefore, the present data indicate that the osteoporosis of hyperprolactinemia is likely due to PRL-induced hypogonadism, rather than a direct effect of PRL on calcium homeostatis.
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PMID:Relative effects of prolactin excess and estrogen deficiency on bone in rats. 955 May 40

Bone densitometry with DXA (dual energy X-ray absorptiometry) and QCT (quantitative computed tomography) techniques are used for in vivo assessment of bone strength and thereby prediction of fracture risk. However, only few in vitro studies have investigated and compared these techniques' ability to determine vertebral compressive strength. The aim of the present study was to (1) assess the predictive value of DXA, QCT, and pQCT (peripheral QCT) for vertebral bone compressive strength assessed by mechanical testing; (2) describe both linear and power relationship between density and strength; and (3) evaluate whether gender-related differences in the above relations were present. The material comprised human lumbar vertebrae L3 from 51 women and 50 men (age range: 18 to 96 years). The study showed that both DXA and CT techniques (QCT and pQCT) have a high predictive value for vertebral strength. The DXA BMD had a high correlation with maximum compressive load (r2 = 0.86). The QCT and pQCT had high correlations with maximum compressive stress (r2 = 0.75 and r2 = 0.86, respectively). The correlation between ash density of the biomechanically tested specimen and maximum compressive stress was r2 = 0.88. There were no differences between linear and power fit in the degree of determination between density and strength. There was no gender-related difference in the relationship between volumetric density and maximum compressive stress. In conclusion, it was demonstrated that DXA, QCT, and pQCT are ex situ equally capable of predicting vertebral compressive strength with a degree of determination (r2) between 75% and 86%. No differences were found between linear and power analysis of the relationship between density and strength, and no difference was found in the density strength relationship between women and men.
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PMID:Lumbar vertebral body compressive strength evaluated by dual-energy X-ray absorptiometry, quantitative computed tomography, and ashing. 1059 17

Growth hormone (GH) is of importance for normal bone remodelling. A recent clinical study demonstrated that MK-677, a member of a class of GH secretagogues (GHSs), increases serum concentrations of biochemical markers of bone formation and bone resorption. The aim of the present study was to investigate whether the GHSs, ipamorelin (IPA) and GH-releasing peptide-6 (GHRP-6), increase bone mineral content (BMC) in young adult female rats. Thirteen-week-old female Sprague-Dawley rats were given IPA (0.5 mg/kg per day; n=7), GHRP-6 (0.5 mg/kg per day; n=8), GH (3.5 mg/kg per day; n=7), or vehicle administered continuously s.c. via osmotic minipumps for 12 weeks. The animals were followed in vivo by dual X-ray absorptiometry (DXA) measurements every 4th week. After the animals were killed, femurs were analysed in vitro by mid-diaphyseal peripheral quantitative computed tomography (pQCT) scans. After this, excised femurs and vertebrae L6 were analysed by the use of Archimedes' principle and by determinations of ash weights. All treatments increased body weight and total tibial and vertebral BMC measured by DXA in vivo compared with vehicle-treated controls. However, total BMC corrected for the increase in body weight (total BMC:body weight ratio) was unaffected. Tibial area bone mineral density (BMD, BMC/area) was increased, but total and vertebral area BMDs were unchanged. The pQCT measurements in vitro revealed that the increase in the cortical BMC was due to an increased cross-sectional bone area, whereas the cortical volumetric BMD was unchanged. Femur and vertebra L6 volumes were increased but no effect was seen on the volumetric BMDs as measured by Archimedes' principle. Ash weight was increased by all treatments, but the mineral concentration was unchanged. We conclude that treatment of adult female rats with the GHSs ipamorelin and GHRP-6 increases BMC as measured by DXA in vivo. The results of in vitro measurements using pQCT and Archimedes' principle, in addition to ash weight determinations, show that the increases in cortical and total BMC were due to an increased growth of the bones with increased bone dimensions, whereas the volumetric BMD was unchanged.
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PMID:The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. 1082 40

The objective of this study was to directly compare in situ femoral dual-energy X-ray absorptiometry (DXA) and in vitro chemical analysis (ash weight and calcium) with mechanical failure loads of the proximal femur, and to determine the influence of bone size (volume) and density on mechanical failure and DXA-derived areal bone mineral density (BMD, in g/cm2). We performed femoral DXA in 52 fixed cadavers (age 82.1 +/- 9.7 years; 30 male, 22 female) with intact skin and soft tissues. The femora were then excised, mechanically loaded to failure in a stance phase configuration, their volume measured with a water displacement method (proximal neck to lesser trochanter), and the ash weight and calcium content of this region determined by chemical analysis. The correlation coefficient between the bone mineral content (measured in situ with DXA) and the ash weight was r = 0.87 (standard error of the estimate = 16%), the ash weight allowing for a better prediction of femoral failure loads (r = 0.78; p < 0.01) than DXA (r = 0.67; p < 0.01). The femoral volume (r = 0.61; p < 0.01), but not the volumetric bone density (r = 0.26), was significantly associated with the failure load. The femoral bone volume had a significant impact (r = 0.35; p < 0.01) on the areal BMD (DXA), and only 63% of the variability of bone volume could be predicted (based on the basis of body height, weight and femoral projectional bone area. The results suggest that accuracy errors of femoral DXA limit the prediction of mechanical failure loads, and that the influence of bone size on areal BMD cannot be fully corrected by accounting for body height, weight and projected femoral area.
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PMID:In situ femoral dual-energy X-ray absorptiometry related to ash weight, bone size and density, and its relationship with mechanical failure loads of the proximal femur. 1092 27

Purebred New Zealand female rabbits were used in this study for demonstrating the feasibility of establishing rabbit's primary osteoporosis model. Bilateral ovariectomies were performed. Five to eight months after operation, we observed the BMD, weight, hair colour and living condition of the model. After killing the rabbits, we made biomechanical detection and pathologic histomorphometry using the bones. The weight of bone ash, the content of calcium and phosphorus, and the weight of metra were determined. The results showed that BMD, bone bending stress, weight of bone ash, content of calcium and phosphorus in ash, and weight of metra all decreased (P < 0.05); the number of trabecula decreased and the bone cortex became thinner. All these parameters evidenced the primary founding of rabbit's osteoporosis model. This research provides a basis for studying the pathogenesis of primary osteoporosis and evaluating the efficacy of pharmacotherapy.
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PMID:[Primary study on the use of ovariectomized rabbits for establishment of osteoporosis model]. 1136 27

Bisphosphonates inhibit bone resorption. Short-term bisphosphonate treatment at therapeutical dosage has been shown to be safe, but there are only a few studies concerning the long-term effects of bisphosphonates on the non-osteoporotic skeleton. Here, we studied the bone effects of 32 weeks' treatment with clodronate on growing rats, using a therapeutical dose of 2 mg/kg and a high dose of 10 mg/kg. We used biomechanical, densitometrical, and, histomorphometrical analyses to examine the rat tibia, femur, and vertebra and also tested some hematological and biochemical parameters. Tibial length was significantly lower in the high clodronate group compared with the controls. No differences were found in tibial or vertebral ash weights. The L4 vertebra compression failure load was higher in the high clodronate group compared with the therapeutical clodronate group, but not compared with the controls. The mechanical strength of the femoral shaft or femoral neck was not affected by clodronate. Cortical BMD in the L4 vertebra was significantly higher in both clodronate groups compared with controls. Histomorphometrical analysis indicated that the trabecular number of vertebra was increased in the therapeutical clodronate group. The mineral apposition rate was not significantly affected by the treatment. Hematological analyses showed a decreased number of platelets at the high dosage. A slight increase in liver enzyme activity was seen in both groups. We conclude that long-term administration of clodronate has no harmful but rather some beneficial effects on bone at the therapeutical dosage. However, a fivefold dose of clodronate causes a slight decrease in the growth of tibial length.
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PMID:Effects of long-term administration of clodronate on growing rat bone. 1180 Feb 32

We have compared the measurements obtained by different methods: dual energy X-ray absorptiometry (DXA), histomorphometry, ash weight, and two morphometric indices (robusticity and bone weight/bone length index) in the orchidectomized (ORX) rat model of male osteoporosis. We examined 144 male wistar rats: 48 sham-operated, 48 ORX, and 48 ORX-treated with a bisphosphonate (risedronate) 2 or 10 mg/kg/day, 5 days per week. Rats were sacrificed at 2, 4, 8, or 16 weeks after the beginning of the study. DXA was performed on a Hologic QDR 2000 on the whole body, whole tibia, and tibial metaphysis. Bone volumes (C.BV/C.TV, and BV/TV) were measured by histomorphometry on the proximal tibial. A significant correlation was obtained between weight measured by DXA and scale (r = 0.993, P <0.000001). However, DXA underestimated weight by 0.3%. This discrepancy was dependent on the rat's weight. The weight bone length (WL) index was linearly correlated with BMD (r = 0.86), BMC (r = 0.96), and ash weight (r = 0.97). Correlation with robusticity was lower than with the WL index. A significant correlation was found between BMC of the metaphyseal region and the bone volumes but this explained only 27% of the variance; correlation with BMD was poorer (r = 0.40). BMC and ash weight were highly correlated (r = 0.992, P <0.000001). However, DXA overestimated BMC by 11% and the overestimation was found to be clearly dependent on the net mineral content of the bone.
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PMID:Comparison insight dual X-ray absorptiometry (DXA), histomorphometry, ash weight, and morphometric indices for bone evaluation in an animal model (the orchidectomized rat) of male osteoporosis. 1203 21

The inflammatory reactions elicited in mice by subcutaneous injections of IFA and CFA had opposite effects when tested on local metacarpal shank bones and the distal epiphysis of shank bones. Although the intensity of the immune reactions was similar, IFA induced bone loss, while CFA induced bone formation, which was mostly periosteal in nature. BMC and BMD measurements were assessed by means of high resolution DEXA, using a hologic 4500A bone scanner with software dedicated for the analysis of small animal bones. DEXA scans were evaluated and related to histological and bone ash content analyses. The morphological and quantitative ash weight analyses of bones exposed to the adjuvants were consistent with DEXA bone density scan measurements.
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PMID:Evaluation of locally induced osteoarthritis by the complete and incomplete Freund's adjuvant in mice. The application of DEXA measurements. 1244 67

The relative sensitivity of tibia bone mineral content (BMC) and density (BMD), percentage ash (ash), and shear force as indicators for dietary Ca and P was compared in 3-wk-old broiler chicks. One hundred eight 7-d-old chicks were grouped by weight into 6 blocks of 3 cages each with 6 birds per cage. Three corn-soybean meal-based diets were randomly assigned to cages within each block. The diets were low P, medium P, and adequate P and were formulated to contain 4.0, 5.1, and 7.8 g of total P/kg feed, respectively; and 5.1, 6.7, and 10.0 g of Ca/kg feed, respectively. The chicks were fed the experimental diets for 14 d. On d 22, chicks were killed, and tibiae were removed from 3 birds/cage. Weight gain, feed intake, feed efficiency, BMC, BMD, shear force, and ash were determined. The BMC and BMD were determined using dual energy x-ray absorptiometry. Correlations among the various bone status variables and dietary Ca and P were determined. Growth performance criteria and ash increased linearly, and BMC and BMD increased linearly and quadratically as dietary concentrations of Ca and P increased. The correlation coefficient between dietary Ca and BMC, BMD, shear force, or ash was 0.89, 0.91, 0.50, or 0.89, respectively; and between dietary P and BMC, BMD, shear force, or ash was 0.88, 0.91, 0.48, or 0.89, respectively. The correlation coefficient between ash and BMC, BMD, or shear force was 0.92, 0.93, or 0.67, respectively. The correlation coefficients for linear regression between shear force and BMC or BMD was 0.56. The regression model for predicting percentage ash using BMD was as follows: percentage ash = 24 + (240 x BMD) with an r2 of 86%. It is concluded that in broiler chicks, tibia ash, BMC, and BMD may be more sensitive than shear force as indicators of dietary Ca and P concentrations and that BMD as measured by dual energy x-ray absorptiometry may be used to predict percentage of tibia ash.
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PMID:Bone densitometry as an indicator of percentage tibia ash in broiler chicks fed varying dietary calcium and phosphorus levels. 1465 74


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