Protective effect of microRNA-224 on acute lower extremity ischemia through activation of the mTOR signaling pathway via CHOP in mice.

Acute lower extremity ischemia (ALEXI) is known worldwide as an urgent condition, occurring when there is an abrupt interruption in blood flow into an extremity. This study aims to investigate whether microRNA-224 (miR-224) affects the ALEXI mice and the underlying mechanism. The miR-224 expression and C/EBP homologous protein (CHOP), mammalian target of rapamycin (mTOR), translation initiation factor 4E-binding protein 1 (4E-BP1), and phosphoprotein 70 ribosomal protein S6 kinase (p70S6K) messenger RNA (mRNA), as well as protein expressions, were determined. The target gene of miR-224 was also verified by using a luciferase reporter gene assay. The vascular endothelial cells from the ALEXI mice were transfected with miR-224 mimics, miR-224 inhibitors, or small-interfering RNA against CHOP. Cell proliferation was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cell cycle distribution along with the cell apoptosis were both evaluated by using a flow cytometry. The muscle fibers of the lower extremities found in the ALEXI mice were evidently swollen and rounded, presenting with a remarkably narrowed gap. The positive CHOP expression increased in ALEXI mice than normal mice, while the miR-224 expression and mTOR, 4E-BP1, and p70S6K mRNA, as well as the protein expression, decreased. Luciferase reporter gene assay validated that the miR-224 gene directly targeted CHOP. MiR-224 facilitated cell proliferation but inhibited cell apoptosis; by contrast, CHOP increased cell apoptosis. Moreover, the cells transfected along with miR-224 mimic exhibited a lower CHOP expression as well as increased mTOR, 4E-BP1, and p70S6K expression. Our study provided evidence that miR-224 could alleviate the occurrence and development of ALEXI in mice through activation of the mTOR signaling pathway by downregulating CHOP.

Effects of orthodontic load on the periodontium of autogenously transplanted teeth in beagle dogs.

OBJECTIVE: To observe the periodontal healing of autogenously transplanted teeth loaded orthodontically after autotransplantation in Beagle dogs. METHODS: Forty-eight teeth were autogenously transplanted, 24 of which were loaded postoperatively with orthodontic force at different time points and for different durations. Periodontal healing was evaluated by probing pocket depth (PPD), the expression of relevant proteins, and histomorphometric analyses. RESULTS: The dental pockets of loaded and non-loaded teeth were both much deeper after the first postoperative week than before transplantation (P<0.05). Later, the PPD, which was measured after postoperative weeks 1, 3, 5, 9 and 13, gradually became shallow. The expressions of alkaline phosphatase (ALP) and basic fibroblast growth factor (bFGF) were higher in loaded teeth than in non-loaded teeth (P<0.05), and in groups subjected to two weeks duration of loading than in other groups at the same load time point (P<0.05). For the same load duration, the expressions of ALP and bFGF in teeth loaded after postoperative week 4 were higher than those of other treatments (P<0.05). According to histomorphometric analyses, an orthodontic force on transplanted teeth applied after postoperative weeks 4 or 8 for two weeks duration should be favorable for periodontal healing. CONCLUSIONS: It is advisable to apply an appropriate magnitude of force on autotransplanted teeth, such as orthodontic force, at appropriate time points and for a suitable duration, to achieve the optimal clinical prognosis following autogenous tooth transplantation. These results may serve as a basis for subsequent studies in humans so as to make clinical improvements.

Autophagy appears during the development of the mouse lower first molar.

Odontogenesis consists of a series of consecutive tooth morphogenesis stages, in which apoptosis is involved to eliminate the unnecessary cells. Autophagy, a lysosome or endosome-mediated self-degradation process, is indicated to participate in embryogenesis and tissue morphogenesis associated with apoptosis. This study hypothesized that autophagy may be involved and associated with apoptosis in odontogenesis. The transcripts of autophagy-related genes (Atg5, Atg7, and Atg12) were positively detected in tooth germs at embryonic day (E) 14.5 and postnatal day (P) 5.5 by quantitative real-time PCR. The protein expression of Atg5-Atg12 conjugate and lipidation of LC3 (microtubule-associated protein 1 light chain 3, autophagic marker) were revealed in the developing tooth germs by western blot. Meanwhile, LC3 was immunolocalized in the enamel organ and dental papilla at embryonic stages (E13.5-E18.5), especially stage E14.5 cervical loop and the PEK that facing the mesenchyme. At postnatal stages (P1.5-P15.5), besides the dental epithelium cells, LC3 was detected in the differentiating and differentiated odontoblasts, dental follicle cells, and Hertwig's epithelium root sheath cells. Moreover, double-immunofluorescence analysis revealed the partial colocalization of LC3 and TUNEL signal in the E14.5 PEK that facing the mesenchyme, the E16.5 stratum intermedium and outer enamel epithelium, the P5.5 stratum intermedium and stellate reticulum. Nevertheless, LC3 was also found in non-apoptotic cells. Furthermore, the transmission electron microscopic images revealed the presence of autophagy, as well as the partial colocalization of autophagic vacuoles and apoptotic nuclei during tooth development. Our findings imply the developmental appearance of autophagy and its partial colocalization with apoptosis during odontogenesis.

[Histological study about the effect of orthodontic loading time and duration on the periodontal repair in autologous tooth transplantation].

OBJECTIVE: The study established an animal model of autologous tooth transplantation in dogs and aimed to explore the effects of orthodontic loading time and duration on the periodontal repair in autologous tooth transplantation. METHODS: 12 Beagle dogs were selected and grouped randomly in this research. Four first premolar teeth in every dog were carried on autologous transplant operation. These teeth were exerted the orthodontic force after the operation in 2, 4, 8 and 12 weeks respectively. The loading duration was 1, 2 and 4 weeks respectively. We examined the dental and periodontal tissue samples in first premolar teeth by histological study, measured root absorption rate and analyzed reconstruction condition of periodontal tissue with statistical methods. RESULTS: Root absorption rates of the experimental group which was exerted the orthodontic force were lower than those of the control group. The difference between two groups had statistical significance (P < 0.05). Root absorption rates in different levels of orthodontic loading time (X) and the duration (Y) had no statistical significance (P > 0.05), but these two factors had interaction effect (P(X x Y) < 0.05). CONCLUSION: Orthodontic force contributes to the improvement of root absorption and reconstruction of periodontal tissue in transplant teeth. The orthodontic loading time and the duration have no obvious effect on root absorption rate of transplant teeth. When X is two weeks and Y is four weeks, it is most beneficial for the reconstruction effect of periodontal tissues in transplant teeth.

[Effect of asymmetry elastic on the maturation of bone collagen and mineralization in condyle of adult SD rat].

PURPOSE: The aim of this investigation was to study the osteogenesis activation following asymmetric inter-maxillary elastic on the subchondral bone of adult SD rats. METHODS: Twenty SD ten-week old rats were used in this study (eight rats loading 0.39 N elastic force, another eight rats loading 1.18 N elastic force, the other four rats without loading as control group). The extra-joint device was fixed on the right side by surgery. Tetracycline, calcein and xylenol orange were intraperitoneally injected on one day before surgery, one day before device removal and one day before sacrifice. Masson trichrome staining and in vivo fluorescence technique were used to detect the osteogenesis. RESULTS: The results of bone collagen maturation and velocity of osteogenesis were different from the control group after force loading. Bone collagen showed better maturity in force-loading side and light force induced more active osteogenesis. CONCLUSIONS: The results suggest that even in the adult SD individuals, the subchondral bone still shows remodeling ability to adapt the various mechanical environments. Stress increases the maturity of bone collagen while rotation inhibits maturity. Mechanic force promotes the osteogenesis, especially the light force.

Factors influencing subjective orthodontic treatment need and culture-related differences among Chinese natives and foreign inhabitants.

AIM: The aim of this survey was to compare Chinese natives and foreign inhabitants in Chengdu, China, with respect to: (1) attitudes towards dental appearance, (2) subjective orthodontic treatment need, and (3) the main factors influencing orthodontic treatment need. METHODOLOGY: A total of 522 subjects, including 227 foreign inhabitants and 295 Chinese natives in Chengdu participated in the survey. A simple random sampling method was adopted and a face-to-face interview was conducted at some public sites using a questionnaire. Data was entered by two persons synchronously using Epidata 3.0, and SPSS 13.0 was used to analyze these data. RESULTS: 89.0% of foreign inhabitants were satisfied with their teeth compared to only 46.8% of Chinese natives. Females were more dissatisfied with their teeth than males. Chinese natives put improving appearance as the top priority (55.9%) for seeking orthodontic treatment; however, in foreign inhabitants, the main reason for seeking treatment was to improve masticatory function (44.1%), followed by "to be pretty" (35.2%). The importance of well-aligned teeth and self-perception of psychosocial impact of malocclusion were the same two main factors influencing subjective orthodontic treatment need (P < 0.05) in foreign inhabitants and Chinese natives. Subjective orthodontic treatment need between the two target groups was significantly different (P < 0.05). CONCLUSION: (1) It was very common that Chinese natives were dissatisfied with their dental appearance, and their subjective orthodontic treatment needs were high. (2) There were some differences in orthodontic treatment motives between the two target groups. (3) There were differences in subjective orthodontic treatment needs between foreign inhabitants and Chinese natives. However, the prominent influential factors were almost the same. There may be benefit to understanding subjective orthodontic needs of different races.

[The technique characteristic and clinical application of HX straight-wire appliance].

HX straight-wire appliance (HX-SWA) is designed and adjusted by doctors of Orthodontic Department, West China College of Stomatology, Sichuan University. It is a set of appliance that is constructed according to normal occlusion features of the Chinese people, including the prescription of tip, torque, in/out, counter-tip, counter-rotation and overcorrection in brackets and buccal tubes. Some ingredients of the appliance are different from that of the most popular Roth straight-wire appliance in the world wide. Over a period of the last 10 years, doctors in our hospital kept on summarizing treatment experience with HX-SWA, which will help more doctors promote practice and results in orthodontic clinic.

[Angle's class II malocclusion: a report of seven cases in one family].

A family with Angle's Class ii malocclusion was identified in West China Stomatological Hospital of Sichuan University. The proband was a 22-year-old woman with Angle's Class II Division 2 malocclusion with congenitally missing teeth. A total of 15 members of the 3 generations in the family were investigated. There were 7 members (3 males, 4 females) with Angle's Class II malocclusion in the family. The results provide the primary basis for further study to localize the virulence gene.

Proteomic analysis of early-response to mechanical stress in neonatal rat mandibular condylar chondrocytes.

The objectives of this study were to investigate the early response to mechanical stress in neonatal rat mandibular chondrocytes by proteomic analysis. To evaluate its molecular mechanism, chondrocytes were isolated and cultured in vitro, then loaded mechanical stress by four-point bending system on different patterns. Morphological observation, flow cytometric analysis, and MTT assays indicated that 4,000 microstrain loading for 60 min was an appropriate mechanical stimulus for the following proteome analysis, which produced a transient but obvious inhibitory effect on the cell cycle. Therefore, we took a proteomic approach to identify significantly differential expression proteins in chondrocytes under this mechanical stress. Using 2-DE and MALDI-TOF, we identified seven differentially expressed proteins including the MAPK pathway inhibitor RKIP, cytoskeleton proteins, actin and vimentin, and other selected proteins. Some differentially expressed proteins were validated by both Western blot analysis and fluorescent staining of cytoskeleton at different loading times. The vimentin and RKIP responsive expression were also proven in vivo in oral orthopedic treatment rats, which was in line with the result in vitro. The histological changes in cartilage also showed the inhibition effect. Furthermore, the expressional level of phosphorylated ERK was increased, which demonstrates the changes in MAPK activity. Taken together, these data indicate that mechanical stress resulted in vimentin expression changes first and then led to the subsequent changes in actin expression, MAPK pathway regulated by RKIP and heat shock protein GRP75. All those changes contributed to the cytoskeleton remolding and cell cycle inhibition, finally led to condylar remodeling.

[Effect of asymmetry traction on the expression of type II collagen in adult rat condyle].

OBJECTIVE: The aim of this investigation was to study the expression of collagen type II in the cartilage of mandibular condyle following asymmetric inter-maxillary traction. METHODS: Two hundred and twenty SD rats were used in this study (one hundred and four rats loading 0.39 N elastic force, another one hundred and four rats loading 1.18 N elastic force, while twelve rats for control). The extra-joint device was fixed on the right side by surgery. Half of the experimental group was killed at 3, 7, 14, 28 days. The devices were removed at the 28th day in the rest rats, and the rats were sacrificed at 3, 7, 14, 28 days after removing the device. The type II collagen expression levels of all the joints were measured using immunohistochemical techniques. RESULTS: The positive expression of the type II collagen was mainly observed in the cytoplasm of chondrocyte, especially in maturative and hypertrophic layer. The expression intensity was different in different stages and different sides. Both of the two experimental groups showed the same tendency, while the changes in the light force group were more obviously than the heavy force group. In the right side (force-loading side), the type II collagen expression decreased at the early force-loading period. After the device was removed, the expressions increased immediately but then reach the lowest level. The expression almost recovered to normal level at the end of experiment. In the left side (none force-loading side), the expression remained increasing after force-loading and reached the peak at the 14th day. CONCLUSION: These results suggest that even in the adult individuals, the chondrocyte showed reaction to the mechanical force by altering type II collagen expression patterns and it may be the cause of the cartilage remolding after asymmetric inter-maxillary traction. A forward elastic force showed a depressant effect in matrix synthesis, and heavy force had stronger effect. But the rotation of condyle accelerated the matrix synthesis.

[The skeletal regulating mechanisms and concepts in growth and development of cranial-facial bones and orthodontic treatment].

There are three kinds of mechanisms regulating the growth and development of skeletal tissue: Bone growth, bone modeling and bone remodeling. However, in the current orthodontics literature, there continues to be substantial confusion regarding the usage of the term "bone remodeling". This article reviews the historical causes for this semantics problem and explains the difference between bone modeling and remodeling, as well as the detailed skeletal regulating mechanisms in the growth and development of cranial-facial bones and orthodontic treatment. At last, this article suggests Chinese orthodontists use the terms "bone modeling" and "bone remodeling" more precisely to avoid scientific confusion and barriers to scientific exchange with other biomedical disciplines.

[Effects of orthodontic tooth movements on insulin-like growth factors expression in periodontal tissues].

OBJECTIVE: To elucidate the regulatory bio-mechanism of estrogen and local stress on the bone remodeling activities in vivo. METHODS: A Wistar rat experimental model was established to apply orthodontic activation during different stages of estrous cycle. In situ hybridization was used to detect the variation of the insulin-like growth factors (IGF) mRNA expression in the periodontal tissues. The data of each group was analyzed with SPSS 11.0 software package for Student-Newman-Keuls (S-N-K) test and one way ANOVA test. RESULTS: Both IGF-I mRNA and IGF-II mRNA level expressed in the periodontal tissues were increased by orthodontic activation during various stages of the estrous cycle. But a similar pattern emerged that the IGF-I mRNA level was the lowest in the estrous stage, whereas its level was the highest in the proestrus stage (P < 0.05). No rhythm of IGF-II mRNA expression found during the estrous cycle. CONCLUSION: It was concluded that local mechanical stimulation directly enhanced the IGF expression. In contrast to the IGF-II, IGF-I was also influenced by the sex hormone rhythm during the estrous cycle.

[Displacement of impacted mandibular canine: a case report].

The long distance displacement of canine is a rare phenomenon in orthodontic clinic. Its related clinical epidemiology, etiology, diagnosis and treatment methods are briefly summarized, and a case of mandibular canine displaced in chin is reported.

[A bio-mechanism study of differential orthodontic tooth moving speed during the estrous cycle].

OBJECTIVE: The purpose of this article was to investigate the changes of the estrogen and insulin-like growth factors (IGF) level induced by orthodontic tooth movements in order to elucidate the bio-mechanism of orthodontic treatments during the estrous cycle. METHODS: A Wistar rat experimental model was established to apply orthodontic activation during different stages of estrous. The serum and periodontal tissue estradiol level were determined by radioimmunoassay and immunohistochemistry. In situ hybridization was also used to detect the variation of the IGF mRNA expression in the periodontal tissues. The data of each group was analyzed with SPSS 11.0 software package. RESULTS: Both serum and periodontal estradiol level were increased by orthodontic activation during various stages of the estrous. IGF mRNA expression were also enhanced with the same trend. The estradiol and IGF- I level showed in a similar pattern during the estrous cycle and the rhythm was not changed by the orthodontic activation. There was no rhythm of IGF-II expression found in the estrous cycle. CONCLUSION: It was concluded that estrogen and IGF were involved in the remodeling activities induced by the orthodontic activation. The speed of the orthodontic tooth movements was closely related to the estrous cycle.

[Improvement on the making process of double splints before orthognathic surgery of skeletal Class III].

The conventional methods on making double splints in presurgery of skeletal Class III were complicated. To find an easy method for the improvement of the production of splints and simplify the making process, 17 severe skeletal Class III patients accepted bimaxillary surgery after making double splints were used. According to visual treatment objective (VTO) forecasting on the lateral cephalometric radiograph of ending presurgical orthodontics and analyzing study models, the surgical methods were designed, the mobile osteotomy bone volume was estimated and the maxillary abnormity was classified. For the patients with right midline and without adjusting their occlusion plane, use the single model method (antedisplace maxillary model twice) or double models method (antedisplace maxillary model firstly, and then retrodisplace mandibular model) to make the double splints which guided the fixtion of bimaxillary surgery through their parallel models and simple articulators. The making process of the double splints was simplified and improved, and the postsurgery effects of all patients were satisfied. Therefore, for making the double splints of skeletal Class III bimaxillary surgery, utilizing the proper method on the basis of the specific abnormal conditions of patients can simplify the production process and get twice the result with half the effort.

[PAR index of adolescents with congenital missing teeth pre- and post-orthodontic treatment].

OBJECTIVE: To assess the outcome of orthodontic treatment for adolescents with congenital missing teeth using the PAR (Peer Assessment Ration) index. METHODS: The PAR index was adopted to evaluate and compare the teeth arrangement, molar occlusion, overjet, overbite and centerline condition of 20 adolescents with congenital missing teeth before and after orthodontic treatments. RESULTS: The initial PAR scores and weighted PAR total scores decreased significantly after Orthodontic treatments (P < 0.01), except for the centerline. The PAR total scores decreased by 14.25 +/- 7.91 (80.90% +/- 11.09%). The weighted PAR total scores decreased by 15.45 +/- 8.16 (75.34% +/- 18.41%). CONCLUSION: PAR index can well reflect the improvement of occlusion characters by orthodontic treatment for adolescents with congenital missing teeth. But further improvement is needed for clinical application.

[Early-response of the condylar chondrocyte under cyclic uniaxial compressive stress].

OBJECTIVE: To investigate the protein profile after treatment of the cyclic uniaxial compressive stress on the rat condylar chondrocyte in vitro. METHODS: The third-passage chondrocytes were harvested from the mandibular condyles of 2-day-old rats, and a cellular compressive stress device (self-made four-point bending system) was used to apply stress on cells at 2000 microstrain and 4000 microstrain (0.5 Hz frequency) for 60 min. The early effects of cyclic uniaxial compressive stress on the protein profile of the rat mandibular condylar chondrocytes were examined by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser-desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). RESULTS: The results showed that the protein profile of the condylar chondrocyte did not change statistically in 2000 microstrain group. In 4000 microstrain group, the protein profile of the condylar chondrocyte was changed. Three new proteins appeared. Five proteins disappeared. Twenty-two proteins were down-regulated and 7 proteins were up-regulated (P < 0.05). The eight different protein spots were identified by MALDI-TOF-MS. It included cytoskeleton protein (gamma-actin and vimentin), glycometabolism protein (alpha enolase and stress-70 protein) and signal transduction protein (Raf kinase inhibited protein, RKLP). CONCLUSIONS: There were significant alternations of the protein profile in the rat condylar chondrocyte after the 4000 microstrain cyclic uniaxial compressive stress loading for 60 min. These different proteins might take part in the early response to the cyclic uniaxial compressive stress.