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DXA Scanning (dxa + scanning)
Selected AbstractsDXA scanning in women over 50 years with distal forearm fracture shows osteoporosis is infrequent until age 65 yearsINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 3 2008H. Lashin Summary Aims:, Women with distal forearm fracture (DFF) may have low bone mineral density (BMD) and merit Dual Energy Xray (DXA) scanning. However patient age at fracture and the database for ,healthy' subjects may influence how many have osteoporosis and require DXA scans. Osteoporosis prevalence in DFF patients by age was investigated using local or nHanes III databases for BMD. Methods:, A total of 186 women over 50 years consecutively referred with DFF over 1 year were audited without exclusion criteria. BMD of L2,4 and femoral neck (Hologic QDR4500A) was measured and T - and Z -scores calculated from a local database or nHanes III. Results:, Of 90 patients aged 50,64 years, 21.1% had femoral neck T -score < ,2.5 and 7.7% < ,3.0 (local) and 8.8% and 4.4% respectively (nHanes III). Patients aged 65,74 years (n = 61) included 19.7% with T -score < ,2.5 (nHanes III = 10%). 41.2% (nHanes III = 28.6%) of patients > 75 years had femoral neck osteoporosis. Including patients with spine T < ,2.5 increased the proportion to 31.1% (50,64 years) and 34.4% (65,74 years) with no extra over 75 years. Weight predicted low BMD ineffectively (area under ROC = 70%). Conclusion:, Osteoporosis is infrequent in women with DFF below 65 years. As fracture prevention treatment yields significant fracture reduction only in patients with T -score < ,2.5, DXA scanning below 65 years is not justified. After 65 years scanning is justified at all ages, as even in the elderly patients osteoporosis is present in < 50% of patients with DFF. Using nHanes III limits the number of DFF patients warranting treatment. Low body weight is unreliable for identifying osteoporosis. [source] Capsaicin-Sensitive Sensory Neurons Contribute to the Maintenance of Trabecular Bone Integrity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2005Sarah C Offley Abstract This investigation used capsaicin to selectively lesion unmyelinated sensory neurons in rats. Neuronal lesioning induced a loss of trabecular integrity, reduced bone mass and strength, and depleted neuropeptides in nerve and bone. These data suggest that capsaicin-sensitive sensory nerves contribute to trabecular bone integrity. Introduction: Familial dysautomia is an autosomal recessive disease in which patients suffer from unmyelinated sensory neuron loss, reduced BMD, and frequent fractures. It has been proposed that the loss of neurotransmitters synthesized by unmyelinated neurons adversely affects bone integrity in this hereditary syndrome. The purpose of this study was to determine whether small sensory neurons are required for the maintenance of bone integrity in rats. Materials and Methods: Ten-month-old male Sprague-Dawley rats were treated with either capsaicin or vehicle. In vivo DXA scanning and ,CT scanning, and histomorphometry were used to evaluate BMD, structure, and cellular activity. Bone strength was measured in distal femoral sections. Body weight and gastrocnemius/soleus weights were measured and spontaneous locomotor activity was monitored. Peroneal nerve morphometry was evaluated using light and electron microscopy. Substance P and calcitonin gene-related peptide (CGRP) content in the sciatic nerve and proximal tibia were determined by enzyme immunoassay (EIA). Substance P signaling was measured using a sciatic nerve stimulation extravasation assay. Results: Four weeks after capsaicin treatment, there was a loss of BMD in the metaphyses of the tibia and femur. In the proximal tibia, the osteoclast number and surface increased, osteoblast activity and bone formation were impaired, and trabecular bone volume and connectivity were diminished. There was also a loss of bone strength in the distal femur. No changes occurred in body weight, 24-h grid-crossing activity, weight bearing, or muscle mass after capsaicin treatment, indicating that skeletal unloading did not contribute to the loss of bone integrity. Capsaicin treatment destroyed 57% of the unmyelinated sensory axons, reduced the substance P and CGRP content in the sciatic nerve and proximal tibia, and inhibited neurogenic extravasation. Conclusion: These results support the hypothesis that capsaicin-sensitive sensory neurons contribute to the maintenance of trabecular bone integrity. Capsaicin-sensitive neurons have efferent functions in the tissues they innervate, effects mediated by transmitters released from the peripheral nerve terminals. We postulate that the deleterious effects of capsaicin treatment on trabecular bone are mediated by reductions in local neurotransmitter content and release. [source] Comparison of body fat estimates using 3D digital laser scans, direct manual anthropometry, and DXA in men,,§¶AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010Todd N. Garlie Objectives: The purpose of this study was to assess the feasibility of utilizing three dimensional whole body laser surface scanning (3DS) to obtain specific anthropometric measurements to estimate percent body fat (BF). Methods: Percent BF estimates from 37 male volunteers, of age 18,62 yr, were determined by inputting manual anthropometric (MA) and 3DS anthropometric measurements into the current Army BF prediction equation for males. The results were compared with each other and to BF values from Dual Energy X-ray Absorptiometry (DXA), employed as a reference method. Results: Mean percent BF estimates (±SD) derived from MA, 3DS and from DXA were 18.4(±3.8), 18.8(±3.9), and 18.9(±4.7), respectively. Analysis of Variance tests revealed no statistical difference between the mean values. Correlation analysis comparing MA and 3DS derived percent BF estimates to each other and to those measured by DXA revealed moderate to strong Pearson correlation coefficients (r), small to moderate standard errors of the estimate (SEE), and were statistically significant (p < 0.05). Conclusions: Correlation coefficients and SEE results for this sample were: (1) DXA vs 3DS; r = 0.74, SEE = 3.2, (2) MA vs DXA; r = 0.82, SEE = 2.8, and (3) MA vs 3DS; r = 0.96, SEE = 1.0. Lin's concordance analysis, including Bland-Altman limits of agreement (LOA), revealed statistically significant measurement agreement among the three measurement modalities (p < 0.05). The application of 3DS scanning to estimate percent BF from commonly used anthropometric measurements are in close agreement with BF estimates derived from analogous MA measurements and from DXA scanning. Am. J. Hum. Biol. 22:695-701, 2010. Published 2010Wiley-Liss, Inc. [source] Adenosine A1 receptors regulate bone resorption in mice: Adenosine A1 receptor blockade or deletion increases bone density and prevents ovariectomy-induced bone loss in adenosine A1 receptor,knockout miceARTHRITIS & RHEUMATISM, Issue 2 2010Firas M. Kara Objective Accelerated osteoclastic bone resorption plays a central role in the pathogenesis of osteoporosis and other bone diseases. Because identifying the molecular pathways that regulate osteoclast activity provides a key to understanding the causes of these diseases and developing new treatments, we studied the effect of adenosine A1 receptor blockade or deletion on bone density. Methods The bone mineral density (BMD) in adenosine A1 receptor,knockout (A1R-knockout) mice was analyzed by dual x-ray absorptiometry (DXA) scanning, and the trabecular and cortical bone volume was determined by microfocal computed tomography (micro-CT). The mice were ovariectomized or sham-operated, and 5 weeks after surgery, when osteopenia had developed, several parameters were analyzed by DXA scanning and micro-CT. A histologic examination of bones obtained from A1R-knockout and wild-type mice was carried out. Visualization of osteoblast function (bone formation) after tetracycline double-labeling was performed by fluorescence microscopy. Results Micro-CT analysis of bones from A1R-knockout mice showed significantly increased bone volume. Electron microscopy of bones from A1R-knockout mice showed the absence of ruffled borders of osteoclasts and osteoclast bone resorption. Immunohistologic analysis demonstrated that although osteoclasts were present in the A1R-knockout mice, they were smaller and often not associated with bone. No morphologic changes in osteoblasts were observed, and bone-labeling studies revealed no change in the bone formation rates in A1R-knockout mice. Conclusion These results suggest that the adenosine A1 receptor may be a useful target in treating diseases characterized by excessive bone turnover, such as osteoporosis and prosthetic joint loosening. [source] | ||||||||||