Bone Tissue Models

Hydrated composites with nanostructured HAP and proteins (gelatin, BSA), HGA, were studied as models of bone tissue (Golovan et al. 2010). BSA was used because albumins are the main non-collagen proteins in bone tissue (Krasavina and Torbenko 1979), and gelatin was used instead of collagen. 

Nanostructured hydroxyapatite Caio(P04)g(OH)2 (HAP) was synthesized using aqueous solutions of the corresponding salts of phosphorus ((NH4)2HP04) and nitric (Ca(N03) 2H20) acids (Vysotskaja et al. 2002)  

Nuclear Magnetic Resonance Studies of Interfacial Phenomena 

FIGURE 7.68 Size distributions of pores filled by unfrozen water for (a) SAW and (b) WAW in human bone tissue initially and after addition of water and solvents, (c) BBl and (d) BB2 after addition of water and solvents. 

FIGURE 7.69 SEM images of HGA composite at different magnification (bar 100 (im and 100 nm). 2010 Taylor Francis Group, LLC 

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Bone defects surgically produced in sheep and rabbit models, have been treated with freeze dried methylpyrrohdinone chitosan [334-336]. hi view of improving bone tissue reconstitution with chitosan associated with calcium phosphate. Microscopic and histological analyses showed the presence of an osteogenic reaction moving from the rim of the surgical lesion toward the center. In control lesions, dense fibrous tissue, without the characteristic histoarchitecture of bone was observed. 

Figure 7.7. A finite element model of a bone specimen in compression. This model was created by converting the voxels from a microcomputed tomography scan into individual bone elements. Loads can then be applied to the model to understand the stresses that are created in the bone tissue.

ANDERSON J J B, AMBROSE w w and GARNER s c (1998) Biphasic effects of genistein on bone tissue in the ovariectomized, lactating rat model. Proc Soc Exp Biol Med 217, 345-50. 

Fig. 6.3 Schematic illustration of bone modelling and remodelling. Bio-inorganic hybrid nanomaterials are kept fresh in bone tissue.

Droloxifene (3-hydroxy-tamoxifen) behaves as an estrogen agonist in bone tissue and several lipid and coagulation markers in castrated rat models and does not show stimulation of the endometrial epithelium in preclinical studies (Ke et al. 1997). Endometrial stimulation has, however, been observed in clinical trials, which, together with the fact that as an estrogen agonist it is ten times less potent than tamoxifen in bone tissue and lipid metabolism (Hendrix et al. 2001) and that in a recent head-to-head comparison with tamoxifen droloxifene was demonstrated not to be superior in any parameter of breast cancer treatment efficacy (Buzdar et al. 2002), has resulted in cancellation of its clinical development. 

Mastro AM, Vogler EA (2009) A three-dimensional osteogenic tissue model for the study of metastatic tumor cell interactions with bone. Cancer Res 69 4097 100... 

Kufahl, R.H. and Saha, S. (1990) A theoretical model for stress-generated fluid flow in the canaliculi-lacunae network in bone tissue. Journal of Biomechanics 23 171-180... 

Risk assessment. The model accounts for most of the major features of chromium(VI) and chromium(III) absorption and kinetics in the rat, and reduction from the chromium(VI) to the chromium(III) valence state, but the bioavailability/absorbability of chromium from environmental sources is mostly unknown, except for bioavailability/absorbability of a few chemically defined salts. Furthermore, the mechanisms by which chromium reserves from bone tissue are released into plasma as well as age, physiological conditions and species variations are important considerations in the refinement of any PBPK model for risk assessment purposes. 

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