Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peripheral quantitative computed tomography (pQCT) is able to evaluate trabecular and cortical bone separately, and to determine geometric properties from cross-sectional images for noninvasive assessments of mechanical strength. In order to assess the diagnostic value of pQCT of the femoral neck, 60 healthy women were examined with a new pQCT machine, XCT-3000 (Norland-Stratec, Germany), which is suitable for direct measurement of the hip. The region of interest chosen was the center of the femoral neck. pQCT of the distal radius and dual energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck were also performed. The study demonstrated that total bone mineral density (BMD) (femoral MD) and trabecular BMD (femoral-TBD) decreased with advancing age. Percent cortical area showed a small but significant decrease with advancing age and % trabecular area increased slightly. Both the endosteal perimeter and the periosteal perimeter were relatively constant with aging. Bone strength index (BSI) and stress-strain index (SSI), which reflect the mechanical strength of bone, declined with advancing age, especially after menopause. Femoral TBD correlated strongly with femoral neck BMD by DXA and L2-L4 BMD by DXA but femoral-CBD did not correlate with femoral neck BMD by DXA. Volumetric BMD of the femoral neck and distal radius were closely correlated. It is concluded that (1) cortical thinning occurs with aging by endocortical resorption and loss of femoral-TBD; (2) loss of femoral-CBD occurred at a slower rate than radial CBD, perhaps due to the weight-bearing effect; (3) biomechanical parameters such as the BSI and SSI may reflect increasing fragility of the femoral neck in pre- and postmenopausal women; (4) pQCT of the femoral neck had diagnostic value at least equivalent to that of DXA or pQCT of the distal radius.
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PMID:Peripheral quantitative computed tomography of the femoral neck in 60 Japanese women. 1059 63

Several studies have suggested an increased prevalence of osteopenia in dialysis. Peripheral quantitative computed tomography (pQCT) is a new technique that allows the noninvasive evaluation of trabecular and cortical bone separately. The aim of the study was: (1) to evaluate cortical bone by pQCT in continuous ambulatory peritoneal dialysis (CAPD) patients and compare the data with that obtained in healthy controls; and (2) to correlate cortical bone parameters with bone mineral density (BMD) of the lumbar spine and femoral neck and total bone mineral content (TBMC). Cortical bone parameters were obtained in 22 CAPD patients and 27 healthy individuals at the distal radius using a Stratec XCT 960 pQCT machine. In the dialysis patients, we also determined BMD and TBMC by bone densitometry. Dialysis patients, compared with controls, showed a significant reduction in volumetric cortical BMD (VcBMD) (p = 0.04) and cortical thickness (cThk) (p < 0.0001) with a significant increase in radial total cross-sectional area (TA) (p = 0.006), endosteal circumference (p < 0.0001), and buckling ratio (p < 0.0001). In CAPD patients, total time on dialysis correlated negatively with radial total BMD (p < 0.01) and VcBMD (p < 0.01). Age correlated positively with TA (p < 0.01), endosteal (p < 0.01), and periosteal circumferences (p < 0.01). Serum intact parathyroid hormone (PTH) levels correlated positively with endosteal (p = 0.04) and periosteal perimeter (p = 0.01). Total alkaline phosphatase correlated negatively with VcBMD (p < 0.01), and positively with endosteal perimeter (p = 0.02). Total bone mineral content correlated significantly with radial cortical content (p < 0.001), cross-sectional cortical area (cA; p < 0.001), and cThk (p < 0.01) but not with total radial BMD, VcBMD, or buckling ratio. No correlations were found between radial cortical parameters and BMD measured at the lumbar spine or femoral neck. We conclude that dialysis patients show cortical osteopenia with marked cortical thinning partially mediated by PTH action on bone. Total bone mineral content correlated with various radial cortical parameters (content, area, and thickness) but not with others. No correlations were found between cortical bone parameters measured at the peripheral skeleton with areal bone density measured at the axial skeleton. These findings suggest that pQCT may be a new tool in the assessment of bone fragility in dialysis patients.
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PMID:Evaluation of cortical bone by peripheral quantitative computed tomography in continuous ambulatory peritoneal dialysis patients. 1701 10

The cystine/glutamate exchanger (xCT) provides intracellular cyst(e)ine for production of glutathione, a major cellular antioxidant. Using xCT overexpression and underexpression, we present evidence that xCT-dependent glutathione production modulates both neuroprotection from oxidative stress and cell proliferation. In embryonic and adult rat brain, xCT protein was enriched at the CSF-brain barrier (i.e., meninges) and also expressed in the cortex, hippocampus, striatum, and cerebellum. To examine the neuroprotective role of xCT, various non-neuronal cell types (astrocytes, meningeal cells, and peripheral fibroblasts) were cocultured with immature cortical neurons and exposed to oxidative glutamate toxicity, a model involving glutathione depletion. Cultured meningeal cells, which naturally maintain high xCT expression, were more neuroprotective than astrocytes. Selective xCT overexpression in astrocytes was sufficient to enhance glutathione synthesis/release and confer potent glutathione-dependent neuroprotection from oxidative stress. Moreover, normally nonprotective fibroblasts could be re-engineered to be neuroprotective with ectopic xCT overexpression indicating that xCT is a key step in the pathway to glutathione synthesis. Conversely, astrocytes and meningeal cells derived from sut/sut mice (xCT loss-of-function mutants) showed greatly reduced proliferation in culture attributable to increased oxidative stress and thiol deficiency, because growth could be rescued by the thiol-donor beta-mercaptoethanol. Strikingly, sut/sut mice developed brain atrophy by early adulthood, exhibiting ventricular enlargement, thinning of the cortex, and shrinkage of the striatum. Our results indicate that xCT can provide neuroprotection by enhancing glutathione export from non-neuronal cells such as astrocytes and meningeal cells. Furthermore, xCT is critical for cell proliferation during development in vitro and possibly in vivo.
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PMID:Cystine/glutamate exchange modulates glutathione supply for neuroprotection from oxidative stress and cell proliferation. 1703 36