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Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and(More)
INTRODUCTION The effect of low-intensity pulsed ultrasound (LIPUS) on cell growth was examined in three-dimensional-cultured chondrocytes with a collagen sponge. To elucidate the mechanisms underlying the mechanical activation of chondrocytes, intracellular signaling pathways through the Ras/mitogen-activated protein kinase (MAPK) and the(More)
To explore lineage-dependent responses to mechanical stress in bone cells, newborn rat calvarial cells, exhibiting differential characteristics of osteoblastic and osteocytic cells, were compared in their immediate and late responses to stretching. Seven fractions of sequentially prepared cells were cultured on Matrigel to promote their differentiation. By(More)
Osteocytes, dendritic bone cells, transduce signals of mechanical loading that results in bone formation. We have reported in stretched primary osteocytes that the cAMP level, IGF-I and osteocalcin protein levels were elevated (Endocrinology 137:2028, 1996). Here we report that stretching induces the expression of immediate early genes, c-fos, and COX-2;(More)
Osteocyte-like cells were prepared by sequentially treating calvaria from newborn rats with collagenase and chelating agents. On a reconstituted gel of basement membrane components, cells from the third collagenase digest displayed a round shape and expressed the highest level of alkaline phosphatase with minimal osteocalcin deposition into the matrix. On(More)
Extracellular matrix production and degradation by bone cells are critical steps in bone metabolism. Mutations of the gene encoding MMP-2, an extracellular matrix-degrading enzyme, are associated with a human genetic disorder characterized by subcutaneous nodules, arthropathy, and focal osteolysis. It is not known how the loss of MMP-2 function results in(More)
Mechanotransduction in bone is complex in nature, being influenced by many modulators such as PTH, prostanoids, and extracellular Ca2+. It has been postulated that osteocytes, dendritic resident cells in bone, transduce signals of mechanical loading that result in anabolic responses such as the expression of c-fos, insulin-like growth factor-I (IGF-I), and(More)
UNLABELLED Prior 8-week treatment with menatetrenone, MK-4, followed by 8-week risedronate prevented the shortcomings of individual drugs and significantly increased the strength of ovariectomized ICR mouse femur compared to the ovariectomized (OVX) controls. Neither MK-4 following risedronate nor the concomitant administration may be recommended because(More)
Proteolytic enzymes with gelatinolytic activity in the synovial fluid (SF) of temporomandibular joint (TMJ) arthropathies were assayed by gelatin-impregnated gel enzymography. SF samples were collected from 10 TMJs in patients with closed lock (CL) condition and 5 TMJs from asymptomatic healthy volunteers. Two proteinases with gelatinolytic activities at 92(More)
The effects of 20-min exposure to low-intensity, pulsed ultrasound were investigated in ST2 cells of bone marrow stromal origin. They responded to ultrasound with elevated levels of IGF mRNAs, osteocalcin, and bone sialoprotein mRNAs. The upregulated expression of these messages appeared in a biphasic manner, with the first peak resistant to the protein(More)