| Research Abstract |
1999 : The schedule of this year is to compare the response of mandibular osteocytes with femoral one to stretching.
But we obtained an interesting result to charactorise the response of mandibular osteocytes to stretching and parathyroid hormone, (1-34) PTH.So we reported (B.B.R.C vol.264).
2000 : Concerning to the comparison the response of mandibular osteocytes with femoral, we prepared two way of mechanical loading procedures. One is the low-intensity pulsed ultrasound which is generated with the transducer, the Sonic Accelerated Fracture Healing System (SAFHS, Exogen, Inc.) recently we reported (B.B.R,C vol.268), the other is Flexercell Strain Unit (Flexercell Corp.) already reported (Endocrinology vol.137 and B.B.R.C.vol.246). Both are already placed on Kanagawa Dental Collage.)
1, Human osteocytic cell culture (J.Bone Miner.Res.vol.10 and Calcif. Tissue Int.vol.57)
2, Osteocytic cells to mechanical loading
(1999) Stretching (Endocrinology vol.137 and B.B.R.C.vol.246), and PTH (1-34)
… More
was added.
(2000) Low-intensity pulsed ultrasound (B.B.R.C.vol.268), and PTH (1-34) was added.
Each set of six total RNA samples from the cells harvested at : 1, 0 min (control) ; 2, 15 min ; 3, Ihr, 5, 6 hrs ; 6, 24 hrs were subjected to PCR analysis with primers (GAPDH, Osteocalcin, ALP, IGF-1, COX-2, et al.)(J.Bone Miner.Res.vol.10 and Calcif.Tissue Int.vol.57). We used the Thamal Cycler which was supported by this grants-in-aid to do RT-PCR analysis.
3, Result and Discussion
(1999) The upregulated steady-state level of osteocalcin mRNA is further upregulated in the presence of PTH (at 1 h after the initiation of stretching). On the other hand, the downregulated level of the message is further downregulated in the presence of PTH (at 3 h after the 3-h stretching)(B.B.R.C.vol.264). The synergy can be either way, positive or negative, in the course of the response. From this, we presume that related mechanisms are at work between the PTH signaling pathways and the mechanotransduction pathways activated by Stretching.
(2000) 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 sia-loprotein mRNAs. The upregulated expression of these messages appeared in a biphasic manner (B.B.R.C.vol.268). On the contrary, in osteocytes hervested from femoral bone, ultrasound was not effective to induce an anabolic reaction of osteogenic cells. But recently we obtained a new result that was effective to lead bone matrix formation, now we discuss this results and have to investigate more in other samples as soon as possible.
4, Conclusion
Our result suggest that Mandibular osteocytes from neural crests show diferent response to mechanical loading from femoral bone, we need more investigations to obtein good result in bone regenerative operations such as distruction osteogenesis in oral and maxillofacial area. Less
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