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  • 1
    ISSN: 1432-0827
    Keywords: Aluminum ; Tissue distribution ; Bone histomorphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of intraperitoneal aluminum chloride (1.5 mg aluminum/kg/day for 9 weeks) were studied in normal and uremic rats. Parameters measured included tissue aluminum, serum vitamin D metabolites, and quantitative bone histology. Aluminum administration increased tissue concentrations of this metal in uremic and nonuremic animals. Bone aluminum concentrations were higher in uremic rats (121 ± 27 mg/kg compared to 47 ± 4), whereas liver values were higher in the nonuremic group (175 ± 47 mg/kg compared to 100 ± 36). Serum concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D were reduced in uremia, but aluminum was without apparent effect on any vitamin D metabolite. Aluminum, in the doses administered, caused no skeletal changes in nonuremic animals. Some uremic, non-aluminum-treated rats developed osteomalacia and marrow fibrosis. However, osteomalacia was more severe and the osteoclast count was higher in the uremic, aluminum-treated rats. In this group of animals the mineral apposition rate was reduced at the metaphyseal endosteum but increased at the periosteum, indicating different control mechanisms at the two sites.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0827
    Keywords: Aluminum ; Parathyroid hormone ; Bone ; Renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone aluminum, quantitative bone histology, and plasma parathyroid hormone (PTH) were compared in 29 patients undergoing chronic hemodialysis. Histologic techniques included double tetracycline labeling and histochemical identification of osteoclasts and osteoblasts. Bone aluminum was measured chemically by flameless atomic absorption spectrophotometry, and histochemically. When measured chemically, the bone aluminum was 67±46 (SD) mg/kg dry weight (normal 2.4±1.2 mg/kg); histochemically, aluminum was present at 2.9±4.4% of trabecular surface. The biochemical and histochemical results agreed well (r=0.80,P〈0.001). No double tetracycline labels were seen at the mineralization front where aluminum was deposited, indicating cessation of mineralization at these sites. The osteoblast surface correlated positively with plasma PTH (r=0.67,P〈0.001) and negatively with bone aluminum level (r=−0.42,P〈0.05). Multiple linear regression showed a correlation of aluminum with osteoblasts additional to that of PTH, consistent with a direct effect of aluminum in depressing osteoblast numbers. Though a relationship between PTH and chemically determined bone aluminum level could not be demonstrated, there was a negative correlation between osteoclast count and aluminum, and the nine patients with severe hyperparathyroid bone disease had lower chemically determined aluminum levels than the other patients. These results suggest that aluminum (a) directly inhibits mineralization, (b) is associated with decreased PTH activity and hence osteoblast numbers, and (c) directly reduces osteoblast numbers. In addition to inducing severe, resistant osteomalacia, aluminum appears to contribute to the mild osteomalacia commonly seen in renal failure, characterized by extensive thin osteoid and low tetracycline and osteoblast surfaces.
    Type of Medium: Electronic Resource
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