Bone structure

Very recently it was found that ordered as well as disordered motifs in human bone exist (Reznikov, Shahar and Weiner, 2014a,2014b). The ordered motif displays two major preferred orientations, that is perpendicular to the long axis of 

There are two basic structural types of bone cancellous (trabecular, spongy) and cortical (dense) bones. Cancellous bone matter is less dense than that of cortical bone and is found across the ends of the long bones. Owing to its lower density, cancellous bone has also a much lower modulus of elasticity but higher strain-to-failure rate compared to cortical bone (Table 3.1). Bone has higher moduli of elasticity than soft connective tissues, such as tendons and ligaments. The difference in stiffness (elastic modulus) between the various types of connective tissues ensures a smooth gradient in mechanical stress across a bone, between bones and between muscles and bones (Hench, 2014). 

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The movement of fluoride through the atmosphere and into a food chain illustrates an air-water interaction at the local scale (<100 km) (3). Industrial sources of fluoride include phosphate fertilizer, aluminum, and glass manufacturing plants. Domestic livestock in the vicinity of substantial fluoride sources are exposed to fluoride by ingestion of forage crops. Fluoride released into the air by industry is deposited and accumulated in vegetation. Its concentration is sufficient to cause damage to the teeth and bone structure of the animals that consume the crops. 

Bone remodelling, which continues throughout adult life, is necessary for the maintenance of normal bone structure and requires that bone formation and resorption should be balanced. Bone remodelling occurs in focal or discrete packets know as bone multicellular unit (BMU). In this process, both bone formation and resorption occur at the same place so that there is no change in the shape of the bone. After a certain amount of bone is removed as a result of osteoclastic resorption and the osteoclasts have moved away from the site, a reversal phase takes place in which a cement line is laid down. Osteoblasts then synthesize matrix, which becomes mineralised. The BMU remodeling sequence normally takes about 3 months to produce a bone structure unit (Fig. 2). 

Hypervitaminosis A is characterized by hepatomegaly, cerebral edema and bone structure alterations. (3-Carotene... 

Odgaard, A. 8k Weinans, H. (eds.) 1995 Bone structure and remodeling. Recent advances in human biology. Volume 2. Singapore World Scientific Publishing Co. 

Born in 1965 in Utrecht, the Netherlands, Marjolein van der Meulen received her Bachelors degree in mechanical engineering from the Massachusetts Institute of Technology in 1987. Thereafter, she received her MS (1989) and PhD (1993) from Stanford University. She spent three years as a biomedical engineer at the Rehabilitation R D Center of the Department of Veterans Affairs in Palo Alto, CA. In 1996, Marjolein joined the faculty of Cornell University as an Assistant Professor in the Sibley School of Mechanical and Aerospace Engineering. She is also an Assistant Scientist at the Hospital for Special Surgery, New York. She received a FIRST Award from the National Institutes of Health in 1995 and a Faculty Early Career Development Award from the National Science Foundation in 1999. Her scientific interests include skeletal mechanobiology and bone structural behavior. 

Fig. 2.1.16 Trabecular bone structure, muscle after removal of the soft tissue (right). Image and tendon of a mouse tail in vitro at 21.14T, parameters multi-slice spin-echo method,...

The most dramatic consequence of sHPT is alterations in bone turnover and the development of ROD. Other complications of CKD can also promote ROD. Metabolic acidosis decreases bone formation and aluminum toxicity causes aluminum uptake into bone in place of calcium, weakening the bone structure. The pathogenesis of sHPT and ROD are depicted in Fig. 23-5. 

Mouse bone marrow, rat bone Structural chromosomal aberrations or Bruce and Heddle 1979 Deknudt and... 

Fig. 2. Pathophysiological sequence of events in periodontal disease. Bacteria produce byproducts (e.g. toxins or enzymes) which, along with mucus, constantly form a sticky, colorless plaque on teeth. If not removed, plaque can harden and form bacteria-harboring tartar around teeth. Tissue that attaches the gums to the teeth can be destroyed by the irritants of plaque. If this is the case, gums pull away from the teeth and small pockets arise between the teeth and gums. The pockets then become filled with more plaque, deepen, and it becomes impossible to clean plaque out. At this stage the bone structure supporting teeth can actually be destroyed (courtesy of Drs J. Chavez and S.E. Zaragoza, El Paso Community College, Texas, USA).

Currey, J. D. "Bones - Structure and Mechanics , Princeton University Press Princeton, 2002. 

Weiner, S. and Traub, W. (1992). Bone structure from Angstroms to microns. FASEB Journal 6 879-885. 

Fluoride, Fluoride Is contained In water and In the diet (22,23) Also, fluoride stabilizes the bone crystal (24) and has been shown to decrease bone resorption (25), For these reasons, fluoride has been recommended for the treatment for osteoporosis (26-28), The Importance of the role of fluoride on maintaining the normal bone structure Is also Indicated by a survey which showed that the Incidence of osteoporosis was lower In naturally high fluoride areas than In areas where the fluoride content of the drinking water was low (29) This observation would Indicate that the Intake of certain amounts of fluoride throughout life may be necessary for the maintenance of the normal skeleton, and that fluoride may protect the skeleton from the development of bone loss which leads to osteoporosis with advancing age, particularly In females. 

Figure 9.7 Bone structure. (Reproduced with permission from Basic Histology (1995) Junquiera LC, Carneiro J, and Kelley RO, McGraw-Hill)...

In comparison, physical activity may not have the same "catch-up" capacity. The case has been made that exercise when yoimg is likely to provide lifelong benefits to bone structure and strength (Warden et al, 2007). It is possible that comparisons of "catch-up" with diet and physical activity are not yet possible until we have comparable ranges of deficiency and timing of deficiency prior to a period of adequacy. To generalize from the Matkovic study, dietary Ca intakes in the United States in placebo arms of randomized controlled trials are only moderately deficient compared to the very low Ca intakes of children in certain regions of Oriental (Lee et al, 1993, 1995) and Third World coimtries (Dibba et al, 2000), for example, who consume little or no milk. 

Prince, R. L., Devine, A., DhaUwal, S. S., and Dick, I. M. (2006). Effects of calcium supplementation on clinical fracture and bone structure—results of a 5-year, double-blind, placebo-controlled trial in elderly women. Arch. Intern. Med. 166, 869-875. 

Vitamin D plays a very central role in maintaining the integrity of bone structure. The vitamin actually comprises a set of closely related derivatives of cholesterol that incorporate a 5,7 diene in ring B. The compounds are not actually active per se, requiring activation by ultraviolet light. In a typical example the action of light on... 

Bones act as a reservoir of certain ions, in particular Ca and PO/1". which readily exchange between bones and blood. Bone structure comprises a strong organic matrix combined with an inorganic phase which is principally hydroxyapatite, 3 CadPO/l- CaiOHH. Bones contain two forms of hydroxyapatite. The less soluble crystalline form contributes to the rigidity of the structure. The crystals are quite stable, hut because of the small size present a very large surface area available lor rapid... 

Methionine Homocystinuria Mental retardation common several eye diseases and thromboembolism common osteoporosis and faulty bone structures Cystathionine-j8-synthase... 

The precipitation of calcium phosphate in the development of bone structure is a major topic beyond the scope of this discussion. It should be noted, however, that this process can be controlled by proteins and/or polysaccharides that provide sites for nucleation and that match features in the geometry of the crystal, such as repeat distances between certain groups. Other proteins can inhibit crystal development. Granular deposits of calcium involve small crystals so that deposition and reabsorption will be rapid. The size of the crystals can be controlled by their protein and/or polysaccharide environment, or even by a vesicular membrane which could act as a template. 

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