Remodeling process

Bone Formation The building of new bone through osteoblasts. Bone formation, which is part of the bone remodelling process, includes the synthesis of organic matter (mostly collagen type 1) and subsequent mineralisation. 

An in vitro cell model resembles the remodeling process of osteoclastic bone resorption followed by osteoblastic bone formation investigate the influence of lead on the communication between these cells determine if lead in the medium (i.e. extracellular fluid) or in the matrix (i.e. in the bone) has different effects on osteoclasts and osteoblasts... 

Prevention of osteoporosis and fracture can be achieved through limiting the resorption-remodeling process. Four main families of products can be effective in controlling bone resorption estrogens, SERMs, bisphosphonates, and calcitonin. Large, prospective randomized trials have proven the effectiveness... 

Helicases catalyze the processive separation of duplex DNA into single strands. Despite sharing similarity to helicases, none of the chromatin remodelling factors, with the exception of the INO80 complex, have been shown to catalyze the separation of DNA strands (Shen et al, 2000). Instead, they can translocate on double-stranded (ds) DNA in an ATP-hydrolysis dependent manner and are characterized by their ability to generate superhelical torsional strain in DNA (Havas et al, 2000 Saha et al, 2002 Whitehouse et al, 2003). The crystal structure of Rad54, a member of the SWI/SNF family has been solved for both S. solfataricus and zebrafish which helps to understand the mechanism of the SWI/SNF ATPase domain in remodelling processes (Durr et al, 2005 Thoma et al, 2005). It reveals... 

The bisphosphonates inhibit osteoclastic resorption of bone by binding to the hydroxyapatite crystals of bone. When osteoclasts first attach to bone in the active resorp-tive sites, the bisphosphonates are released from that bone. The release of these compounds locally prevents further osteoclastic attachment to those resorptive surfaces. The bisphosphonates also may inhibit resorption by inducing apoptosis of osteoclasts and by inhibiting release of interleukins and other compounds involved in bone resorption. The net result of actions of these compounds is inhibition of bone osteoclastic resorption. This action allows new bone formation to catch up in the remodeling process and can result in a net gain in bone density. 

It is concluded that chronic leg ulcer patients probably lack the mechanisms that normalise their levels of antioxidant enzymes, which normally decrease at early stages of wound healing in order to allow blood granulocytes and tissue macrophages to perform their function in cleansing the wounded area. Consequently re-epitheUalisation and matrix remodeling processes are delayed. LLLT stimulates... 

The results of animal tests using rats, rabbits, and dogs have demonstrated high biocompatibility and high osteoconductivity. Moreover, the most impressive bone tissue reaction of the HAp/Col composites is incorporation of the composites into the bone-remodeling process, that is, they are resorbed by osteoclastic cells. ... 

Osteoblasts and osteoclasts are involved in the bone remodeling process. One can easily see that certain parts of bone must be eroded and lesorbed in the growing infant or child. Ihe skull, for example, must be resorbed to make room for the growing brain. The osteoclast adheres to the bone and secretes acid in its zone of contact with the bone, A pH of about 3 may be produced in this zone of contact. Normally, bone mineral is very insoluble in water. An attempt to dissolve hydroxyapatite in water at pH 7 results in a solution of calcium ions with a concentration of about 0,1 mM. Bone mineral can, however, be dissolved in acid. Apparently, the bone mineral dissolved in the acid secreted in the region of contact can result in a solution of calcium reaching about 40 mA4- The osteoclast is distinguished by its ruffled bonder... 

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