A possible mechanism of low molecular weight protein tyrosine phosphatase (LMW-PTP) activity modulation by glutathione action during human osteoblast differentiation

Objective

Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of enzymes strongly involved in the regulation of cell growth and differentiation. Since there is no information concerning the relationship between osteoblastic differentiation and LMW-PTP expression/activity, we investigated its involvement during human osteoblast-like cells (hFOB 1.19) differentiation. It is known that LMW-PTP is regulated by an elegant redox mechanism, so we also observed how the osteoblastic differentiation affected the reduced glutathione levels.

Design

hFOB 1.19 cells were cultured in DMEM/F12 up to 35 days. The osteoblast phenotype acquisition was monitored by measuring alkaline phosphatase activity and mineralized nodule formation by Von Kossa staining. LMW-PTP activity and expression were measured using the p-nitrophenylphosphate as substrate and Western blotting respectively. Crystal violet assay determined the cell number in each experimental point. Glutathione level was determined by both HPLC and DNTB assays.

Results

LMW-PTP modulation was coincident with the osteoblastic differentiation biomarkers, such as alkaline phosphatase activity and presence of nodules of mineralization in vitro. Likewise LMW-PTP, the reduced glutathione-dependent microenvironment was modulated during osteoblastic differentiation. During this process, LMW-PTP expression/activity, as well as alkaline phosphatase and glutathione increased progressively up to the 21st day (p < 0.001) of culturing, decreasing thereafter.

Conclusions

Our results clearly suggest that LMW-PTP expression/activity was rigorously modulated during osteoblastic differentiation, possibly in response to the redox status of the cells, since it seems to depend on suitable levels of reduced glutathione. In this way, we pointed out LMW-PTP as an important signaling molecule in osteoblast biology and bone formation.     

Social and biological early life influences on the prevalence of open bite in Brazilian 6-year-olds

OBJECTIVE: Little is known about the effects of social and biological risk factors for open bite on the primary dentition. The aim of this study was to assess the early-life risk factors affecting anterior open bite. METHODS: A cross-sectional study using a birth cohort was carried out in Pelotas, Brazil. A sample of 400, 6-year-old children was employed. The Foster and Hamilton criteria were used to classify open bite. Data concerning social conditions, and perinatal and childhood health and behaviour were obtained from birth to 12 months of age and during the fifth year of the children's lives. Unconditional bivariate and multiple logistic regression analysis were performed. RESULTS: The prevalence of anterior open bite was 46.3%. Risk factors included: a maternal age of between 30 and 39 years, as compared with children whose mothers were younger; breast-feeding for < 9 months; dental caries experience; pacifier sucking between 12 months and 5 years, as compared to no sucking or a shorter duration of sucking; and the presence of finger-sucking at 6 years of age. CONCLUSION: Open bite in the primary dentition was associated with older mothers, early weaning, dental caries occurrence, long-term use of a pacifier and finger-sucking at 6 years of age. These findings support the common risk approach for intervention to prevent open bite in the primary dentition.     

Cervical impalement injury

Impacted injuries of the head and neck are uncommon. Associated injuries can be present and can be a serious problem. We present an unusual clinical case and discuss the management of this complex injury. Head and neck injuries deserve special attention because of their enormous functional and esthetic significance. Contusion, abrasion, retained foreign bodies, laceration, and avulsion are some of the most frequent injuries. Impalement injuries are not so common. These lesions combine aspects of blunt and penetrating trauma and usually result from penetration by a large, rigid, blunt-tipped object that traverses a certain body area in a through-and-through fashion and often remains in situ at the time of presentation. There have been many case reports describing these injuries in the trunk and extremities; however, cases of head and neck impalement are still lacking in number. A case of an unusual cervical impalement is presented, together with a discussion of the management of this complex injury.     

Molecular size distribution analysis of human gingival glycosaminoglycans in cyclosporin- and nifedipine-induced overgrowths

Glycosaminoglycans are thought to accumulate in formative lesions like drug-induced gingival overgrowth. Recent evidences, however, suggest that the amounts of glycosaminoglycans are comparable in overgrown and healthy gingiva. Besides, alterations in the size distribution of glycosaminoglycan molecules isolated from phenytoin-induced overgrown samples have also been suggested. Therefore, we sought to determine possible differences in molecular size distribution of gingival glycosaminoglycans in other types of drug-induced overgrowths. Purified gingival glycosaminoglycans from healthy and cyclosporin- and nifedipine-induced overgrown gingival tissues were analyzed by agarose gel electrophoresis and their molecular-size distribution was evaluated by both gel filtration chromatography and polyacrylamide gel electrophoresis. Our results on the gingival glycosaminoglycan composition showed presence of chondroitin sulfate, dermatan sulfate, heparan sulfate and hyaluronic acid in all types of gingival tissues examined. In addition, hyaluronic acid was predominantly of a large size eluting near to the void volume of a Superose-6 column, while the sulfated glycosaminoglycans were mainly composed of low molecular size glycosaminoglycans. Our results show no differences in the molecular-size distribution of hyaluronic acid and sulfated glycosaminoglycans among healthy and drug-induced overgrown gingival tissues.     

Nervus intermedius neuralgia: a case report

Nervus intermedius neuralgia (NIN) is an uncommon disorder that affects a sensory branch of the facial nerve. This condition usually provokes a very intense and stabbing pain localized in the depth of the ear canal. Due to the close anatomical proximity, temporomandibular joint (TMJ) pathologies should be included in the differential diagnosis. The treatment of NIN has not been established, although it seems reasonable that the therapeutic approaches used in other more common craniofacial neuralgias, such as trigeminal neuralgia, should be effective. In this paper, the authors present a case report of a female patient diagnosed with NIN who was successfully managed with pharmacological treatment.     

Avulsion of permanent lower central incisors: esthetic-functional solution

Abstract –  This short communication reports a clinical case of a 11-year-old girl, who underwent an avulsion of the lower left lateral incisor and who sought delayed treatment. The treatment was a combined technique with polyethylene fibers and composite resins to create a fixed partial denture, which is a low-cost solution and presents a good esthetic-functional result. The technique is described and the success of its use in appropriately recommended cases is confirmed.     

氟离子缓释正畸粘接剂缓释性能的研究

目的全面了解树脂型氟离子缓释正畸粘接剂(fluoride releasing adhesive，FRA)缓释氟离子的性能，建立一套评价FRA氟离子缓释性能的测试方法及指标。方法测定并计算FRA在一定时间中累计氟离子释放量，绘制出时间—氟离子累计释放量趋势线，并计算每单位质量FRA有效氟离子释放量。结果时间—氟离子累计释放量趋势线显示，FRA在90d内能持续、稳定地释放氟离子，每单位质量FRA在90d内有效氟离子释放量为449μg/g。结论本实验FRA试样具有稳定缓释氟离子的能力。     

牙周炎患者龈沟液和龈组织中IL—8的测定

采用ELISA间接夹心法测定了23名成人牙周炎患者34个患牙龈沟液中的IL-8.并用免疫组织化学法对相应的炎性龈组织进行检测.结果表明IL-8与牙周炎症密切相关,牙周炎龈沟液(GCF)中IL-8检出率为88.24%.IL-8含量范围为0.006～2.772ng/μl.其含量与牙龈指数相关非常显著,与牙周袋深度相关显著,与附着丧失、菌班指数无明显相关.炎性龈组织切片染色表明龈上皮组织和胶原组织中含有大量的阳性染色,从组织学上证明了GCF中IL-8的来源.提示IL-8可能在牙周炎发病机制中起着重要作用.