To examine the influence of osteoblast function on aluminum-induced neo-osteogenesis in the mammalian species, we compared the effects of aluminum in sham-operated and thyroparathyroidectomized (TPTX) beagles. TPTX dogs received sufficient calcium carbonate and calcitriol to maintain normal plasma calcium and calcitriol levels, but developed evidence of decreased osteoblast recruitment and activity, including diminished osteoid-covered trabecular bone surface (3.22 +/- 0.21 vs. 10.95 +/- 1.30%) and a decreased osteoblast number (27.8 +/- 8.1 vs. 139.0 +/- 26.0/mm). Administration of aluminum (1.25 mg/kg i.v., three times/wk) increased the serum aluminum levels in both sham (1,087.0 +/- 276.0 vs. 2.7 +/- 0.8 micrograms/liter) and TPTX animals (2,786.0 +/- 569.0 vs. 3.6 +/- 0.8 micrograms/liter) above normal but did not alter the plasma calcium, creatinine, or PTH from control levels in either sham or TPTX dogs. After 8 wk of therapy, however, bone biopsies from sham-operated beagles displayed evidence of neo-osteogenesis including an increased bone volume (47.0 +/- 1.0 vs. 30.4 +/- 0.9%) and trabecular number (4.1 +/- 0.2 vs. 3.2 +/- 0.2/mm). Much of the enhanced volume resulted from deposition of poorly mineralized woven bone (9.9 +/- 2.7%). In contrast, biopsies from aluminum-treated TPTX animals exhibited significantly less evidence of ectopic bone formation. In this regard, bone (35.5 +/- 1.7%) and woven tissue volume (1.4 +/- 0.8%) as well as trabecular number (3.3 +/- 0.1/mm) were significantly less than those of the aluminum-treated controls. These observations illustrate that aluminum reproducibly stimulates neo-osteogenesis and induces a positive bone balance. However, this effect apparently depends on the availability of a functional osteoblast pool which, if depleted by TPTX, limits the expression of aluminum-induced new bone formation.
L D Quarles, H J Gitelman, M K Drezner
Usage data is cumulative from March 2022 through March 2023.
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.