Osteoid

Mycobacterium avium infection DBA/lj T Hyperplasia, synovitis, synovial cyst formation, fibroblast proliferation, and osteoid deposition. Presence of neutrophils in the interarticular space. Higher levels of anti-CII Abs of the IgGl subtype. 93... 

As they secrete osteoid matrix around themselves, osteoblasts eventually become entrapped within lacunae ( spaces ) and mature into osteocytes. Although topographically isolated from each other, osteocytes maintain contact with neighbours by cell processes which run through tiny interconnecting fluid-filled canaliculi (channels) within the matrix. 

These results indicated osteoporosis. In this condition, which often appears secondary to another pathology such as an endocrinopathy, chronic renal failure or following long term immobilization, bone architecture is normal hut its mass is reduced relative to its volume, that is there is normal mineralization hut the amount of osteoid matrix is reduced. Treatment is with bone resorption inhibitors such as the bisphosphonate group of drugs, for example alendronate. 

Bone scans were not performed, but typically in osteomalacia there is widespread under mineralization of osteoid, so unlike osteoporosis, osteomalacia is due to poor quality bone causing a loss of rigidity and strength, rather than a quantitative reduction ofbone. A condition in children, which is biochemically similar to osteomalacia, is rickets. Sufferers have misshapen bones of the head, spine and chest and typically bowed legs. 

Loss of Crtap in mice causes an osteochondrodysplasia characterized by severe osteoporosis and decreased osteoid production... 

Osteoid Etidronate suppresses bone turnover and may retard mineralization of osteoid laid down during the bone accretion process. In patients with fractures, especially of long bones, it may be advisable to delay or interrupt treatment until callus is evident. 

Minkin, C., Rabadjija, L-, Goldhaber, P. Bone remodeling in vitro The effects of two diphosphonates on osteoid synthesis and bone resorption in mouse calvaria. Calc. Tiss. Res. 14, 161 (1974)... 

Figure 1. Diagram of a thin bone trabecula (5) showing the four types of bone cells. Osteoblasts (8) and their precursors (7) are shown on the upper surface over a layer of uncalcified osteoid matrix (9), os-teocytes (6) are shown in their lacunae, an osteoclast (1) and a bone lining cell (3) are shown on the lower surface. Capillaries (4), containing red blood cells in their lu-mina, and a fibroblast (2) are shown near the trabecula. Adapted from Krstic (1978).

Figure 1. The cellular activity during bone remodelling. At the tip (cutting cone) multi-nucleated osteoclasts (OCLs) excavate the mineralised bone tissue. At some distance, after the resting zone, osteoblasts (OBLs) refill the tunnel with (osteoid) that is subsequently mineralised. Osteocytes (OCYs) are former osteoblasts that were entombed within the bone matrix, but remained connected to the bone surface by numerous long slender protrusions (not visible). Courtesy R. Schenk.

Unusual histological findings of increased osteoid formation and abnormal, fish scale bone lamellation pattern were used to suggest a new type VI OI (Rauch and Glorieux, 2004). So far, these findings were reported in fewer than a dozen patients, and the mode of inheritance of the disorder was not established. Another peculiar disorder with recessive inheritance (unusual for type IV OI) was observed in a community of Native Americans in northern Quebec (Rauch and Glorieux, 2004). In these patients, bone... 

Much clinical and experimental experience has been obtained about the manifestation of bone diseases, especially in renal patients. Many patients with Al-induced bone disease remain asymptomatic. There are two distinct forms of Al bone disease. The most severe form is osteomalacia, with recurrent fractures and resistance to vitamin D therapy. This disease is characterized by an increase of osteoid due to a mineralization defect induced by Al that is localized at a critical site in the bone, i.e., the osteoid calcification front [250]. The adynamic bone disease is another form of Al-related bone disease, characterized by a reduced bone turnover [97]. Al can have a direct negative effect on the bone by deposition at the mineralization front, causing a defective calcification. This is due to the influence of Al on calcium-phosphorus precipitation, crystal formation and crystal growth [251]. There might also be a toxic effect on the proliferation of osteoblasts and on mature osteoblasts with a time- and dose-dependent effect on osteoblast growth and function [143]. 

Hypoparathyroidism manifestates as osteomalacia with a low number and activity of both osteoclasts and osteoblasts. Osteoid formation is reduced, and its... 

New bone material is formed chemically by cells called osteoblasts . These cells contain water in place of minerals. Gradually, calcification of the organic matrix (osteoid) occurs due to catalysis of the elements of the collagen structure, and this matrix grows to form the ceramic portion of the bone. The initial mineralization in humans is fast, 70% within the first four days. It takes months to reach normal mineral capacity thereafter. 

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