Osteocalcin Expression and Mineralization in Developing Tooth of Xenopus laevis

Osteocalcin (OC) is the most abundant noncollagenous protein of extracellular matrix in the bone. In an OC deficient mouse, bone formation rates are increased in cancellous and cortical bones. OC is known as a negative regulator of mineral apposition. OC is also expressed in the tooth of the rat, bovine, and human. However, little is known about OC during tooth development in Xenopus. The purpose of this study is to compare the expression of OC with mineralization in the developing tooth of Xenopus, by using von Kossa staining and in situ hybridization. At stage 56, the developmental stage of tooth germ corresponds to the cap stage, and an acellular zone was apparent between the dental papilla and the enamel organ. From stage 57, calcium deposition was revealed by von Kossa staining prior to OC expression, and the differentiated odontoblasts forming predentin were located at adjoining predentin. At stage 58, OC transcripts were detected in the differentiated odontoblasts. At stage 66, OC mRNA was expressed in the odontoblasts, which was aligned in a single layer at the periphery of the pulp. These findings suggest that OC may play a role in mineralization and odontogenesis of tooth development in Xenopus.

Effect of Pdx1 Expression after Sox9 Depletion in the Early Pancreatic Development in African Clawed Frog (Xenopus laevis) / 대한해부학회지

The pancreas is a mixed exocrine and endocrine gland involved in the control of many homeostatic functions.During embryogenesis,the pancreas arises from dorsal and ventral evaginations of the foregut,which subse- quently fuse into a single organ.The characterization of early genes expressed in the developing pancreas is critical to understand its specification and differentiation.Pdx1 is one of the earliest markers of pancreatic development and a key molecule in its development.Sox proteins form a large class of transcriptional regulators implicated in the control of a variety of developmental processes.One member of this family,Sox9,is expressed in the developing pancreas, but little is known about the function of Sox9 in the developing pancreas.We further investigated Sox9 function during pancreatic development in Xenopus .Using a hormone-inducible inhibitory mutant of Sox9 ,we found that Pdx1 expres- sion was reduced in the ventral pancreatic buds in Sox9-depleted embryos.We suggest that Sox9 gene expression may be involved in pancreatic development in Xenopus.

Effect of Retinoic Acid on the Expression of PDGF Receptors During Palatogenesis / 대한해부학회지

Although cleft lip and palate are one of the most common craniofacial malformation, little is still known about the mechanism of the palate formation. Retinoic acid (RA) is known a teratogen, and cleft palate is induced by retinoic acid administration in the secondary palate formation stage. Many growth factors and their receptors are involved in the formation of the secondary palate. Here, we investigated the expression of PDGFR-alpha, and PDGFR-beta during palatogenesis after retinoid acid administration in mice by RT-PCR and immunohistochemistry. At E15.5, the opposing palatal shelves fused with one another in the control group, but the palatal shelves were not elevated and cleft palate was induced in the RA-treated group. In RT-PCR, PDGFR-beta was downregulated during palatogenesis after RA administration. In immunohistochemical experiment, PDGFR-alpha and PDGFR-beta were reduced in RA-induced group. Taken together, we suggest that PDGF receptors may be molecules involved in palate formation.

The Reliability and Accuracy of Perdriolle's Method on Measurement of Spinal Axial Rotation / 대한정형외과학회잡지

The purpose of this study is to determine how accuratively and reliably the Perdriollo s method can measure vertebral rotaton according to the level of vertebra and true axial rotation. Standard AP radiographs were taken using 10 dry human vertebra (two set of T3, T6, T9, T12, L3) with 5degrees increments in axial rotation, ranging from 0degrees to 50degrees. In order to evaluate the reliability of Perdriolle s method, three observers measured each radiograph twice, and intet-and intraobserver variance were estimated. The accuracy of Perdriolle's method was analyzed by total error analysis, root mean square error (RMSE) and Deviation of differences. 372 errors were made in the 660 measurement and 88.9% of all measurements were within +/- 5degrees of true rotation angle. There were no signigicant difference in the intraobserver measurement at each level whereas interobserver measurements were significantly different only at T3 level. The measurement was also the least accurate at T3 (RMSE=6.2292). We concluded that Perdriolle's method using torsion meter is an accurate and reliable one to measure the vertebral rotation with less accuracy and reliability in high thoracic level.