Research progress of necroptosis on bone related diseases / 中国骨伤

As a new type of cell death, necroptosis is initiated by tumor necrosis factor receptor 1(TNFR1), and then activated receptor-interacting protein kinase 1(RIP1) and receptor-interacting protein kinase 3 (RIP3), following by the activation of mixed lineage kinase domain-like protein(MLKL) to deliver cell death signal. When necroptosis happens, damage associated molecular patterns (DAMPs) enter into extracellular area through the ruptured cytomembrane, followed by the disordered tissue hemeostasis. In recent years, many researches showed that necroptosis playimportant roles in a few bone related diseases, such as osteoporosis, osteonecrosis, osteosarcoma, etc. Thus, we try to briefly review the researches in this field.

Effect of experimentally created occlusal disorders on the expression of estrogen in rat condylar cartilage / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of experimentally created occlusal disorders (ECOD) on the expression of estrogen in rat condylar cartilage.</p><p><b>METHODS</b>The model of ECOD was created by moving right upper and left lower first molars anteriorly. The animals in ECOD were sacrificed at 2, 4, 6, 8 weeks later. In removed occlusal disorders group, the moved first molars were extracted at 6 weeks later, and the animals were sacrificed 2 weeks later. The expression of estrogen was detected by SABC technique of immunocytochemistry, and then was analyzed by the density of estrogen-positive chondrocytes.</p><p><b>RESULTS</b>1) Estrogen was abundant in mature layer and hypertrophic layer of rat mandibular condylar cartilage. 2) In control group, the expression of estrogen decreased gradually from 6-week-old to 16-week-old. 3) In both childhood and puberty rats, the expression of estrogen in experiment group was significantly higher at 2 weeks after treatment, while no difference was found at 4, 6, 8 weeks after treatment. However, the expression in removed occlusal disorder group was higher than that in control group and 8 weeks of ECOD group.</p><p><b>CONCLUSION</b>In rat condylar cartilage, the expression of estrogen de-creases with age. Induced by ECOD, the expression of estrogen increases in early stage of remodelling activity.</p>

Expression feature and bioinformatic analysis of molar root patterning gene 1 / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To examine the expression of molar root patterning gene 1 (Mrp1) and predict the Mrp1 structure by bioinformatics analysis.</p><p><b>METHODS</b>A pair of Mrp1-specific PCR primers were designed, and RT-PCR method was used to study the mRNA's expression pattern in rat molar root and other organs. Gene positioning and other protein sequence prediction were carried out by chromosome analysis and other bioinformatics analysis.</p><p><b>RESULTS</b>Mrp1 was expressed not only in the molar but also in the developing pancreas, liver, lung and kidney tissues. Mrp1 was located in the 18q12.3 chromosome of the rats and the Mrp1 amino acids sequence had about 37% homology with a known protein Uroplakin IIIb (p35) which was an urothelial differentiation membrane molecular marker. A trans-membrane structure, 5 PKC phosphorylation sites and 4 CKII phosphorylation sites in Mrp1 were found.</p><p><b>CONCLUSIONS</b>Mrp1 has a broad expression in different developing organs, and it may have a important function in the rat tooth root development.</p>

Effect of induced occlusal disorders and removed occlusal disorders on the expression of bone morphogenetic protein-2 of condylar cartilage in rats / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This article was to study the effect of induced occlusal disorders and removed occlusal disorders on the expression of bone morphogenetic protein-2 (BMP-2) of condylar cartilage.</p><p><b>METHODS</b>Young and adult female Sprague-Dawley rats were divided respectively into induced occlusal disorders group, removed occlusal disorders group and control group, 3 rats every group. For induced occlusal disorders rats, the elastic rubbers were inserted between the first and second molar in the left upper side and right lower side to form the disordered occlusion. They were killed under anaesthesia 8 weeks after the treatment. For removed occlusal disorders rats, the first molars that caused disordered occlusion were extracted 6 weeks after forming disordered occlusion. 2 weeks later, they were killed under anaesthesia. For normal rats, they were killed at the same time with experimental rats. Hibateral temporomandibular joints of each rat were removed and stained with HE and monoclone antibody of BMP-2. The thickness of condylar cartilage was measured. The expression of BMP-2 in condylar cartilage was detected by half-quantity immunohistochemical analysis.</p><p><b>RESULTS</b>For adult induced occlusal disorders group, the thickness of cartilage in intermediate part of condyle decreased. However, it increased in the posterior part. After removing occlusal disorders, the thickness of posterior condylar cartilage returned to normal level. But it was still thinner than control group in the intermediate part. The expression of BMP-2 in anterior, intermediate, posterior part of condylar cartilage of young induced occlusal disorders group was higher than that of young removed occlusal disorders group expression of BMP-2 showed induced occlusal disorders group was higher than removed occlusal disorders group, which was higher than control group. and control group. No difference of the expression of BMP-2 was found in young removed occlusal disorders group and control group. For the expression of BMP-2 in intermediate part of condylar cartilage, both adult induced and removed occlusal disorders groups were higher than adult control group. For the posterior part of adult condyle cartilage, the expression of BMP-2 showed induced occlusal disorders group was higher than removed occlusal disorders group, which was higher than control group.</p><p><b>CONCLUSION</b>Induced occlusal disorders can lead higher expression of BMP-2 in condylar cartilage of young and adult rats. Adaptability of condylar cartilage of adult rats is weaker than young rats, especially the intermediate part.</p>

Management of disk displacement with condylar fracture / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate clinical features of disk displacement during the course of condylar fracture and to explore the techniques of disk reposition and suturation.</p><p><b>METHODS</b>32 patients (10 females and 22 males) who had disk displacements with condylar fractures were followed up. Reduction and reposition of the dislocated disks simultaneously with fixation of fractures were performed. 7 patients underwent intermaxillary fixation with elastic bands for 1 to 2 weeks.</p><p><b>RESULTS</b>The occlusions were satisfactory in all cases but one for the reason of ramus height loss. No TMJ symptom was found when examined 3 months post operation.</p><p><b>CONCLUSIONS</b>Anterior disk displacements were most occurred with high condylar process fractures. Surgical reposition and suturation of disk play an important role for the later TMJ-function.</p>