Katsutomo Kato

Immobilization-Induced Cartilage Degeneration Mediated Through Expression of Hypoxia-Inducible Factor-1α, Vascular Endothelial Growth Factor, and Chondromodulin-I

Immobilization results in thinning of the articular cartilage and cartilage degeneration, although the exact mechanisms are not clear yet. Hypoxia is thought to contribute to the degeneration of articular cartilage. We investigated the roles of hypoxia inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and the newly cloned antiangiogenic factor, chondromodulin-I (ChM-1), in cartilage degeneration in immobilized joints. Male Wistar rats (n = 30, 12-week-old) were divided randomly into the control group (n = 10), immobilization group (n = 10), and continuous passive motion (CPM) group (n = 10). In the immobilization group, the ankle joints were fixed in full plantar flexion with plaster casts for 4 weeks. In the CPM group, the ankle casts were removed during the immobilization period and the ankle joints were subjected to CPM. Significant thinning of the articular cartilage was noted in the immobilization group but not in the control or CPM group. In the immobilized group, vascular channels were found in the area between the calcified cartilage zone and the subchondral bone. The densities of HIF-1α—and VEGF-immunostained cells were higher in the immobilized group than the other two groups. In contrast, low expression of ChM-1 was detected in the articular cartilage of the immobilized group compared with the control and CPM group. Our results showed that immobilization induces thinning of the articular cartilage and appearance of vascular channel, in areas with balanced expression of HIF-1α/VEGF and ChM-1.

Non-metric tooth crown traits of the Thai, Aka and Yao tribes of Northern Thailand

A survey was made of Thai tribe members, who cultivate rice paddies in the flatlands of northern Thailand, and of the Aka and Yao tribes, who farm with the slash-and-burn method in a mountainous region of northern Thailand. Plaster casts of the upper and lower jaws of tribe members were taken. Seventeen non-metric traits of their tooth crowns were classified and compared with other Mongoloid populations in various regions and periods. It was observed that the Thai tribe had the Sundadont characteristics, typical of South-East Asians, but the Aka and Yao tribe had more Sinodont than Sundadont characteristics, typical of North-East Asians. The regional and temporal variations of crown morphology in South-East Asia suggest earlier setting of the Thai tribe than the Aka and Yao tribes in this region. Moreover, comparison of the tooth morphological and linguistic classifications contradicts the traditional theory of the genealogy of the Thai language family. On the subject of the origin of modern South-East Asians, it is suggested that there has not been a gene flow of Sinodonty into Sundadonty of the principal ethnic groups in Neolithic South-East Asia.

Mitochondrial DNA analysis of Yayoi period human skeletal remains from the Doigahama site

We analyzed the mitochondrial DNA extracted from 14 human skeletal remains from the Doigahama site in Japan to clarify the genetic structure of the Doigahama Yayoi population and the relationship between burial style and kinship among individuals. The sequence types obtained in this study were compared with those of the modern Japanese, northern Kyushu Yayoi and ancient Chinese populations. We found that the northern Kyushu Yayoi populations belonged to the groups that include most of the modern Japanese population. In contrast, most of the Doigahama Yayoi population belonged to the group that includes a small number of the modern Japanese population. These results suggest that the Doigahama Yayoi population might have contributed less to the formation of the modern Japanese population than the northern Kyushu Yayoi populations. Moreover, when we examined the kinship between individuals in the Doigahama site, we found that the vicinal burial of adult skeletons indicated a maternal kinship, although that of juvenile skeletons did not. The vicinal burial style might have been influenced by many factors, such as paternal lineages, periods and geographical regions, as well as maternal lineages. In addition, skeletons considered to be those of shamans or leaders had the same sequence types. Their crucial social roles may have been inherited through maternal lineage.

Effects of treadmill exercise on muscle fibers in mice with steroid myopathy.

We studied the effect of treadmill exercise on muscle fibers in mice with experimental steroid myopathy. Frozen sections of the extensor digitorum longus (EDL) and soleus (SOL) muscles were stained with hematoxylin-eosin, and the muscle fiber diameters measured. In the EDL, muscle fiber diameters in the steroid groups decreased significantly compared with those in the control groups; moreover, muscle fiber diameters in the exercise groups increased significantly compared with those in the non-exercise groups, whereas the diameters in the SOL did not differ. We speculate that treadmill exercise may prevent corticosteroid-induced muscle fiber atrophy.