ABSTRACT
As a system,estrogen co-plays with growth hormone affecting the longitudinal bone growth.Meanwhile.estrogen receptors(ERα,ERβ,GPR30)are also involved in the regulation of the proliferation,mature and apoptOSis of the chondrocytes in the growth plate. It is well known that ERα promotes the clogure of the growth Mate.while it's emphasized by some latest articles that it is the genetic structure of ERβ that can disturb the expression of the ERα at certain level of serum concentration of estrogen.It regulates the physiological states of the bone growth as well as explains some pathological process. Some new progresses of GPR30 in this field are also summaried in this review.
ABSTRACT
[Objective]To study the effect of tibial diaphyseal lengthening on the longitudinal growth of the tibia.[Method]Rabbit models of tibial diaphyseal lengthening and tibial osteotomy were established.Standard radiography of the tibia was taken and the length of the tibia was measured.Histology of the proximal and distal tibia was made and the thickness of the growth plate was measured.[Result]Tibial osteotomy alone stimulated the longitudinal growth of the tibia and increased the thickness of the growth plate.However,tibial diaphyseal lengthening suppressed this stimulation resulting in natural longitudinal growth and normal thickness of the growth plate that matched the normal side.[Conclusion]Diaphyseal lengthening of tibia does not inhibit the longitudinal growth of the tibia.
ABSTRACT
The purpose of this study was to investigate the effects of running training on bone formation in rats in relation to the age training started. The first experimental period was set from 6 to 12 weeks (wks) old and the second from 12 to 19 wks old. Sixty-four Wistar strain 6-wk-old male rats were initially divided into a non-exercise (N) and an exercise (E) group. At 12 wks old, each group was subdivided into two groups, providing four groups: non-exercise·non-exercise (NN), non-exercise·exercise (NE), exercise·non-exercise (EN) and exercise·exercise (EE) . Exercise consisted of treadmill running at a speed of 30 m/min, 60 mm day, 5 days wk. The animals were sacrificed before the experiment (6 wks old), post-first experiment (12wks old) and postexperiment (19 wks old), the bilateral tibiae were removed and their lengths, bone mineral content (BMC), bone mineral density (BMD) and bone histomorphometric parameters were measured. The tibial length was significantly shorter in 12-wk-old E than N rats and in 19-wk-old EE than NN. At 19 wks old, the total tibial BMD values were significantly higher in EE than NN, and the BMD values of the proximal and distal tibiae, where the cancellous bone was the main component, had increased markedly, whereas no differences between the diaphyseal BMD of each group were noted. Bone histomorphometry at 12 wks old, considered the immature period, showed that the osteoid surfaces and labeled surfaces tended to be increased by running training, but the bone volume was unchanged. In contrast, at 19 wks old, considered the early mature period, the osteoid surfaces showed a tendency to decrease and labeled surfaces to increase and consequently the bone volume increased albeit not significantly. These results suggest that: 1) running training started in immature rats represses longitudinal tibial growth, 2) the cancellous bone is more sensitive then the cortical bone to this type of training and 3) training of early mature rats increases bone volume by increasing the efficiency of osteoid calcification.
ABSTRACT
Objective:To observed the longitudinal changes of the facial growth in vertical dimension in the Chinese adolescents with normal occlusion from 13 to 15 years old.Methods:The subjects were from Beijing area and consisted of 9 males and 14 females aged 12.5-13.5 years with Class I skeletal and dental pattern and without previous orthodontic treatment. Serial 2-year- annual cephalometric radiographs were taken and digitalized. Descriptive statistics for the absolute and incremental changes of the skeletal cephalometric measurements were conducted.Results:Significant gender differences in the changes of facial growth in vertical dimension from 13 to 15 years old were observed. Most of the skeletal measurements in males showed greater value than those in females. The number of the measurements which showed gender difference increased with age. The annual incremental changes of TAFH, TPFH, LAFH, U6-PP in males and those of TPFH and RH in females from 13 to 14 years old were greater than those from 14 to 15 years, However, the average increment of L6-MP in males and that of UI-PP, LI-MP, U6-PP and OB in females from 13 to 14 years old were smaller than those from 14 to 15 years old. There was no significant gender difference in TAFH/TPFH from 13 to 15 years of age. Gender difference from 14 to 15 years old was found in the growth of dental-alveolar height. The main dento-alveolar height changes happened in lower incisors and lower molars in males and in the region of upper molars and upper incisor in females.Conclusion:The skeletal facial growth in vertical dimension from 13 to 14 year old falls into the accelerating period. After 14 years old, the growth velocity is slowed down. There are significant gender differences in the skeletal changes of facial growth in vertical dimension from 13 to 15 years old. From 14 to 15 years old, the gender differences are mainly found in the growth of the dento-alveolar height.