Mineralization, cortical bone

Bone mineral density was measured after 7.4 months in 49 asthmatic children, 38 of whom took inhaled beclomethasone, average daily dose 276 micrograms, and 11 sodium cromoglicate, average daily dose 30 mg (121). Children who had used beclomethasone had grown as much as those who used sodium cromoglicate. Trabecular and cortical bone mineral density in the proximal forearm and lumbar spine increased to the same extent in both groups. 

The first subsurface bone tissue Raman spectroscopic measurements were performed using picosecond time-resolved Raman spectroscopy on excised equine cortical bone [56, 57], In these experiments it was shown that a polystyrene backing could be detected through 0.3 mm of bone. The same picosecond technology was used to perform the first transcutaneous Raman spectroscopic measurements of bone tissue [58]. In this study, the cortical bone mineral/matrix ratios of excised limbs of wild type and transgenic (oim/oim) mice were compared and the differences demonstrated. 

Chavassieux P, Garnero P, Duboeuf F, Vergnaud P, Brunner-Ferber F, Del-mas PD, et al (2001) Effects of a new selective estrogen receptor modulator (MDL 103,323) on cancellous and cortical bone in ovariectomized ewes a biochemical, histomorphometric, and densitometric study. J Bone Miner Res 16 89-96... 

Bone mineral effect. Coffee, taken by 258 healthy occupationally active men aged 40-63 years, significantly reduced the trabecular bone mineral content. The extent of alcohol intake did not differentiate bone mineral content values at the distal radius, whereas the significant detrimental effects of both smoking and coffee drinking on trabecular (but not cortical and total) bone mineral content were revealed. Simultaneously, smokers and ex-smokers, when... 

Of the four prominent pure end-member phosphate species of the apatite group only dahllite (space group C63/m) is a common biomineral28. This carbonate apatite is a distinct variety of apatite rather than a mixture of CaC03 and hydroxyapatite. Expressed as oxides, the mineral content of bovine cortical bone (dry fat-free material) has the following chemical composition112 ... 

In an attempt to simplify the discussion, we ignore the fact that the modulus and properties of bone are dependent on the testing direction and mineral content. A typical stress-strain curve for cortical bone is illustrated in Figure 6.7. Mineralized ECMs show a much higher modulus and UTS, and the strain at failure is markedly decreased. In the same manner that increased crosslinking increases the UTS of unmineralized tissue, mineral deposition acts as a crosslink and improves the UTS and the modulus of bone. The UTS for cortical bone varies from 100 to 300 MPa, the modulus varies from several to more than 20GPa, and the strain at failure falls to only 1 to 2%. 

Few groups have dealt with the problem of ageing of bones and teeth. It is known that with time many physical and chemical properties of bones and teeth mineral components undergo different changes. Kuhn et al.131 employed 31P SS NMR to study the FIPO4 groups of young and old cancellous and cortical bovine bones. From these data, it was apparent that calcium phosphate in the form of carbonated apatite is the only bone mineral component. 

Carboxyethylgermsesquioxane can inhibit bone resorption by osteoclasts in a concentration-dependent manner . The therapeutic effect of 2-carboxyethylgermanium sesquioxane (Ge-132) for experimental osteoporosis has been studied using ovariectomized rats maintained on a low calcium containing diet. The Ge-132 decreased the bone strength, and affected the femur cortical bone index and bone mineral mass caused by osteoporosis . ... 

Ratios of bulk metals to ultratrace metals have been used by some workers to gain insight into the altered relationship of metal concentration in the aged (US), For example, the ratio of calcium to zinc in both trabecular and cortical bone has been found to be inversely proportional to the age of the subject. In patients with osteoporesis, minerals in general are quantitatively reduced although they remain the same qualitatively, meaning that bone density decreases as the subject advances in age. 

Figure 4.3 Tissue sections, (a) A 12-week-old mouse Von Kossa-stained for mineral and counterstained with toluidine blue for tissue morphology (b) IR images of cortical bone at 16 weeks the top panel shows the integrated area under the 900-1200cm phosphate envelope. The second and third panels illustrate the mineral to matrix ratios and crystallinity, respectively. Reprinted with permission from Ref [37].

In contrast to trabecular bone, in the cortical bone of ovx monkeys the mineral content was significantly increased in endosteal regions, while the crystallinity and collagen crosslink ratio remained constant in both periosteal and endosteal tissue [66]. Because these parameters displayed different trends in cortical and trabecular bone, the compositional adaptations may be site-specific. 

The anabolic agents parathyroid hormone (PTH) [66, 71] and nandrolone dec-anoate (ND) [72, 73] have both been shown to stimulate bone formation. PTH caused bone to exhibit compositional characteristics typically associated with younger bone, including a lower mineral matrix ratio, crystallinity and crosslink ratio. In contrast, ND treatment restored those parameters affected by ovariectomy to the level of sham controls in cortical bone, but not in trabecular bone. 

Bone composition, such as mineralizahon, carbonate accumulation, crystallinity and collagen crosslinking, has been shown to change with age [41], and is correlated with the bone s mechanical properhes [42, 43]. In microdamaged bone, the collagen crosslinking is altered but the mineralization and crystallinity are unaffected [44] (Figure 14.6). Alterahons in bone composition have been observed in diseases such as osteoporosis [45], osteopetrosis [46] and osteoarthritis [47]. The treatment of osteoporosis with nandrolone decanoate, an anabolic steroid, was shown to alter the cortical bone composition [48], whereas treatment with bisphos-phonates had little effect [49]. 

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