The role of locally synthesized growth factors and cytokines in pathogenesis of osteoporosis Bone remodelling is a complex process involving … (1997 Feb)
The role of locally synthesized growth factors and cytokines in pathogenesis of osteoporosis Bone remodelling is a complex process involving a number of cellular functions directed toward the coordinated resorption and formation of new bone . Bone remodelling is regulated by systemic hormones and by local factors . The local factors are synthetized by skeletal cells and include growth factors and cytokines . The end product of remodeling is the maintenance of a mineralized bone matrix , and the major organic component is the collagen . local factors play an important role in pathophysiology of osteoporosis as systemic hormones .

Defective bone remodelling in osteoprotegerin deficient mice. (2004 Feb)
defective bone remodelling in osteoprotegerin deficient mice . previous studies have reported enhanced osteoclastogenesis , increased bone resorption and osteoporosis in osteoprotegerin ( OPG ) deficient mice . In the present study , we show that the tibial epiphyses contain abundant , thin trabeculae lined with numerous osteoclasts and cuboidal osteoblasts . The increase in osteoblasts and osteoclasts was associated with a dramatic increase in calcein labelling of the mineralization fronts and replacement of much of the intertrabecular marrow with numerous alkaline phosphatase positive preosteoblasts . furthermore , the discrete , linear cement lines seen in wild type mice were replaced by a randomly oriented meshwork of cement lines that were stained intensely for tartrate resistant acid phosphatase and osteopontin in the OPG / mice . these indices of accelerated bone remodelling in mutant bone were associated with irregular trabecular surfaces , a disorganized collagen matrix interspersed with amorphous ground substance and numerous fissures between old and new bone . In total , these observations indicate that enhanced osteoclastic activity in OPG / epiphyses led to a coupled increase in osteoblast differentiation and activity and an increase in bone remodelling . The high bone turnover , disorganized matrix and impaired attachment of new to old bone in the cement lines in OPG / mice appear to cause bone fragility .

The usefulness of biochemical markers of bone remodelling in the diagnosis and follow up of paget s disease of bone … (1991 Oct)
The usefulness of biochemical markers of bone remodelling in the diagnosis and follow up of paget s disease of bone , primary hyperparathyroidism , tumoral hypercalcemia and postmenopausal osteoporosis . I . The markers of bone formation rapid detection of the exact changes in bone remodelling is exceptionally important . In this paper , the latest bone remodelling biochemical markers are reviewed . Some of them have already been used for a long time , and their utility has been widely demonstrated . The newest ones , in experimental stage , can be used as a complement to the others . The bone remodelling markers reviewed are : 1 ) alkaline phosphatase ; 2 ) osteocalcin ; 3 ) other noncollagen of bone matrix such as osteonectin , GLA protein of the matrix , osteopontine and alpha 2 HS glycoprotein ; 4 ) procollagenous and other collagenous peptides of the matrix ( C terminal of type I procollagen and urinary elimination of nondialysis hydroxyproline . amongst the bone resorption markers studied are : 1 ) calcium / creatinine urinary quotient ; 2 ) tartrate resistant acid phosphatase ; 3 ) urinary hydroxyproline ; 4 ) other substances derived from collagen disruption such as hydroxilysin glycoside , piridinolinic intermolecular bridges and the enzymatic activity of proline iminopeptidase . We endeavoured to collect all the most important references on the matter , especially those relating to paget s disease of the bone , primary hyperparathyroidism , tumoral hypercalcemia and postmenopausal osteoporosis .

Normal bone remodelling what can go wrong in osteoporosis ? The skeleton is a metabolically active organ in constant change … (1998 Apr)
normal bone remodelling what can go wrong in osteoporosis ? The skeleton is a metabolically active organ in constant change and renewal . specialised cells are responsible for resorbing and synthetizing bone matrix . The process of bone remodelling , by removing old and damaged bone tissue and replacing it with new , is necessary for conserving the integrity of bone . In recent years , research has given new insight into the fine relationship between different cell types in bone tissue . This has enhanced our understanding of the pathophysiology behind osteoporosis and other metabolical bone diseases . This article gives a summary of our present knowledge of the normal cell biology of bone and what contributes to its regulation . How this helps the understanding of normal and pathological bone loss is illustrated . It is important to understand bone remodelling in order to interpret measurements of bone mineral density and biochemical markers accurately .

Bone mineralization and mineral status after initial calcification in matrix vesicles or collagen fibrils , bones are continually modified by … (2003 Dec)
Bone mineralization and mineral status after initial calcification in matrix vesicles or collagen fibrils , bones are continually modified by modelling then remodelling . In bone tissue , the degree of mineralisation of bone structural units is heterogeneous , reflects the rate of bone remodelling , and can be measured using microradiography . Our model is based on the fact that bone remodelling activity and thus the duration of the secondary mineralisation of bone tissue would influence its mineral status ( mainly its degree of mineralisation or bone density at tissue level ) . When the bone remodelling rate increases ( menopause , parathyroid hormone ) , the degree of mineralisation of bone tissue decreases . conversely , after a diminution of the remodelling rate induced by antiresorptive treatments , the degree of mineralisation of bone tissue increases . strontium ranelate ( protelos ) has been tested to date as a potential therapeutic agent in patients suffering from postmenopausal osteoporosis . recent phase III studies ( the spinal osteoporosis therapeutic intervention SOTI study and the treatment Of peripheral osteoporosis study tropos ) show a decrease in the vertebral and extravertebral fracture risk and an increase in bone mineral density measured at lumbar spine and femoral levels . strontium ranelate has a unique mechanism of action , since it decreases bone resorption and increases bone formation ( decoupling agent ) . Our preliminary observations in animal and man reveal that , because of this dual mechanism of action , the degree …

Schnurri 3 is an essential regulator of osteoblast function and adult bone mass. (2007 Oct)
schnurri 3 is an essential regulator of osteoblast function and adult bone mass . skeletal remodelling is a cyclical process where under normal physiological conditions , bone formation occurs at sites where bone resorption has previously taken place . homeostatic remodelling of the skeleton is mediated by osteoclasts , giant multinucleated cells of haematopoietic origin that are responsible for bone resorption and osteoblasts , which originate from mesenchymal stem cells , and synthesise the matrix constituents on bone forming surfaces . 1 proliferation , differentiation and bone remodelling activities of these cells involve a complex temporal network of growth factors , signalling proteins and transcription factors . dysregulation of any one component may disrupt the remodelling process and contribute to the pathogenesis of common skeletal disorders , like osteoporosis and paget s disease . Rare single gene disorders resulting in elevated bone mass due to osteoclast defects are collectively termed osteopetrosis . rarer still are single gene disorders , collectively termed osteosclerosis , in which elevated bone mass is due to intrinsically elevated osteoblast activity . 2 while we have learned much about the molecular control of skeletal formation and remodelling from these mutations , additional genes that regulate bone mass have yet to be characterised .

Dynamics of bone remodelling : biochemical and pathophysiological basis. (1997 Feb)
dynamics of bone remodelling : biochemical and pathophysiological basis . renewal of the bone matrix is induced by bone cells called osteoblasts and osteoclasts , which act sequentially on the bone surface . This remodelling depends on local factors , such as cytokines and growth factors which play an important role in the bone tissue as mediators of cell to cell and matrix to cell communication . growth factors released from the bone matrix during the resorption are responsible for the refilling of the resorption cavity by osteoblasts . cytokines also mediate locally the effect of several hormones on bone cells . recent work is concerned with the modulation by oestradiol of osteoblastic cytokines acting on osteoclast differentiation . In mice , an increased production of interleukin 6 production by osteoblasts is responsible for the increased bone resorption occurring after ovariectomy . other growth factors , such as transforming growth factor beta , whose secretion is modified by oestradiol , may also be implicated . In women , an increase in cytokine production by blood mononuclear cells is associated with the occurence of menopause and reversed by oestrogen treatment . during osteoporosis and age related bone changes , changes in the production of insulin like growth factor I or of one of its binding proteins could be responsible for low bone formation . In addition to their role in bone remodelling , cytokines and growth factors are now implicated in osteoporosis .

Usefulness of bone remodelling biochemical markers in the diagnosis and follow up of paget s bone disease , primary hyperparathyroidism … (1991 Oct)
usefulness of bone remodelling biochemical markers in the diagnosis and follow up of paget s bone disease , primary hyperparathyroidism , tumor hypercalcemia , and postmenopausal osteoporosis . II . Bone resorption markers rapid detection of the exact changes in bone remodelling is exceptionally important . In this paper , the latest bone remodelling biochemical markers are reviewed . Some of them have already been used for a long time , and their utility has been widely demonstrated . The newest ones , in experimental stage , can be used as a complement to the others . The bone remodelling markers reviewed are : 1 ) alkaline phosphatase ; 2 ) osteocalcin ; 3 ) other noncollagen of bone matrix such as osteonectin , GLA protein of the matrix , osteopontine and alpha 2 HS glycoprotein ; 4 ) procollagenous and other collagenous peptides of the matrix ( C terminal of type I procollagen and urinary elimination of non dialysis hydroxyproline . amongst the bone resorption markers studied are : 1 ) calcium / creatinine urinary quotient ; 2 ) tartrate resistant acid phosphatase ; 3 ) urinary hydroxyproline ; 4 ) other substance derived from collagen disruption such as hydroxylysine glycoside , piridinolinic intermolecular bridges and the enzymatic activity of proline iminopeptidase . We endeavored to collect all the most important references on the matter , especially those relating to paget s disease of the bone , primary hyperparathyroidism , tumoral hypercalcemia and postmenopausal osteoporosis .