Osteoclast

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Related to osteoclastic: calcitonin, osteoclast activating factor

osteoclast

[′äs·tē·ə‚klast]
(histology)
A large multinuclear cell associated with bone resorption.
(medicine)
A large surgical apparatus through which leverage can be exerted to effect osteoclasis.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Osteoclast

 

a cell that is involved in the destruction and resorption of bone tissue in vertebrate animals and man. An osteoclast contains from three to several dozen nuclei and a great many lysosomes, whose hydrolytic enzymes upon release from the osteoclasts resorb the mineral matrix of bone and calcified cartilage.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Osteoclasts can no longer function without these proteins and bone resorption is substantially reduced.With decreased osteoclastic activity, resorption sites are reduced.
Post-SCI 3 wk to 6 mo, the serum level of bone collagen I telopeptide was reported to be higher, indicating predominant osteoclastic activity [3-4].
They preferentially bind to bone surfaces which are undergoing remodelling and are released by the bone matrix during reabsorbion, inhibiting osteoclastic activity.
Osteoclastic resorption now exceeds the ability of osteoblasts to build new bone, and mineralized bone collagen is removed before completing secondary mineralization.
RANKL (receptor activator of the nuclear factor-kB ligand) is a surface protein, part of the superfamily of TNF (tumoral necrosis factor), which when bound to their receptors (RANK) expressed in the osteoclastic precursors stimulates its differentiation in mature osteoclast, increasing its bone resorption and causing hypercalcemia and osteoporosis.
The researchers in this study conlcuded that antioxidants may reduce the damaging effects of oxidative stress on bone mass by reducing the up regulated osteoclastic differentiation and enhancing the down regulated osteoblastic differentiation.
Currently FDA-approved bisphosphonates, including Fosamax (alendronate), Actonel (risedronate), Didronel (etidronate), Boniva (ibandronate), and Reclast (Zometa) (zoledronate), are designed to strengthen bone by inhibiting normal osteoclastic bone resorbing activity, which slows the loss of bone mineral density (BMD), allowing the trabecular architecture to stabilize.
Bone turnover improved selectively in women >70 years old, as assessed by the dualenergy x-ray absorptiometry (DEXA) technique and the decrease of osteoclastic activity.
The principal action of bisphosphonates is inhibition of osteoclastic bone resorption, but the potent nitrogen-containing aminobisphosphonates such as zoledronic acid, alendronate, pamidronate, rise-dronate, and ibandronate also have proinflammatory effects, with an acute phase reaction characterized by fever and flulike symptoms occurring following a first treatment with these drugs in more than one-third of patients (Clin.
The right mastoid process demonstrated osteoclastic activity in the bone and the petrous portion exhibited signs of bone remodeling.
Findings may include a dense fibroblastic stroma, areas of cystic degeneration, osteoid, microfractures, haemorrhage, macrophages with hemosiderin, and multinucleated osteoclastic giant cells.
They also appear to reduce bone resorption by inhibiting osteoclastic vacuolar proton pumps.

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