Biomechanism of abnormal stress on promoting osteoarthritis of temporomandibular joint through Piezo1 ion channel.

OBJECTIVE: This study aimed to investigate whether flow fluid shear stress (FFSS)-mediated signal transduction affects the function of Piezo1 ion channel in chondrocyte and to further explore the role of mechanical overloading in development of temporomandibular joint osteoarthritis (TMJ OA). METHODS: Immunohistochemical staining was used to determine the expression of Piezo1 in TMJ OA tissue collected from rat unilateral anterior crossbite (UAC) models. Chondrocytes harvested from normal adult SD rats were treated with FFSS (0, 4, 8, 12 dyn/cm2) in vitro. Immunofluorescent staining, real-time polymerase chain reaction, western blotting, flow cytometry and phalloidin assay were performed to detect the changes of cellular morphology as well as the expression of Piezo1 and certain pro-inflammatory and degradative factors in chondrocyte. RESULTS: Immunohistochemical analysis revealed that significantly increased Piezo1 expression was associated with UAC stimulation (p < .05). As applied FFSS escalated (4, 8 and 12 dyn/cm2), the expression levels of Piezo1, ADAMTS-5, MMP-13 and Col-X gradually increased, compared with the non-FFSS group (p < .05). Administering Piezo1 ion channel inhibitor to chondrocytes beforehand, it was observed that expression of ADAMTS-5, MMP-13 and Col-X was substantially decreased following FFSS treatment (p < .05) and the effect of cytoskeletal thinning was counteracted. The activated Piezo1 ion channel enhanced intracellular Ca2+ excess in chondrocytes during abnormal mechanical stimulation and the increased intracellular Ca2+ thinned the cytoskeleton of F-actin. CONCLUSIONS: Mechanical overloading activates Piezo1 ion channel to promote pro-inflammation and degradation and to increase Ca2+ concentration in chondrocyte, which may eventually result in TMJ OA.

The value of high-resolution MRI in the diagnosis, efficacy of treatment, and prognosis of central nervous system vasculitis.

AIM OF THE STUDY: To explore the high-resolution magnetic resonance imaging (HR-MRI) characteristics of central nervous system (CNS) vasculitis and to explore the value of HR-MRI in the treatment effect and prognosis evaluation of CNS vasculitis. MATERIAL AND METHODS: During the follow-up of 24 patients diagnosed as CNS vasculitis by the Second Hospital of Hebei Medical University, 3.0T HR-MRI was used for imaging examination and HR-MRI characteristics were analysed. RESULTS: The affected vessel wall of 24 patients showed diffuse uniform centripetal thickening. The HR-MRI examination showed varying degrees of lumen stenosis, including 5 cases (20.8%) involving a single arterial segment, and 19 cases (79.2%) involving multiple arterial segments. And most cases (92.9%) showed grade 2 enhancement of the involved vessel wall. Except for one case involving the basilar artery at the same time, the remaining 23 cases involved only the anterior circulation vessels. We analysed and compared the affected vessels between the relapsed group and the non-relapsed group, and found that the average number of involved vascular segments was 6.5 ±3.4 (3-11) in the relapsed group and 3.5 ±2.1 (1-8) in the non-relapsed group, with a significant difference between the two groups (p = 0.039). CONCLUSIONS: The CNS vasculitis was more likely to involve the anterior circulation vessels. The number of affected vascular segments in the relapsed group of CNS vasculitis was higher than in the non-relapsed group, suggesting that the more vascular segments involved, the more prone to recurrence.

[Logistic regression analysis of risk factors of temporomandibular disorder in undergraduates of Xinjiang Medical University].

PURPOSE: To investigate the prevalence of temporomandibular disorders (TMD) in undergraduates of Xinjiang Medical University and analyse its possible risk factors. METHODS: A sample of 700 medical students included 244 males and 456 females was selected from Xinjiang Medical University and underwent examination of temporomandibular joint, questionnaire survey. Their average age was 20.08±1.457 years. Prevalence of TMD was analyzed, and the possible risk factors associated with the disease were identified by logistic regression analysis with SPSS17.0 software package. RESULTS: The prevalence of TMD was 42.40% in this population. There was no difference between different ethnics. Chewing-side preference, bruxism，orthodontic treatment，tooth extraction，psychological factors，anterior overjet, posterior scissors-bite were the main risk factors which increased the occurrence of TMD. CONCLUSIONS: Poor oral habits, psychological factors and malocclusion were related to the development of TMD.

Negative transcriptional regulation of inflammatory genes by group B3 vitamin nicotinamide.

The water-soluble group B3 vitamin nicotinamide (NAM) is involved in a wide range of physical processes through biosynthetically converted to nicotinamide adenine dinucleotide (NAD(+)). In addition to its pivotal role in energy metabolism, NAD(+) is also the indispensable substrate of poly (ADP-ribose) polymerase-1 (PARP-1) and sirtuin 1 (SIRT1). PARP-1 and SIRT1 may catalyze the posttranslational poly(ADP-ribosyl)ation and acetylation of histones as well as non-histone proteins, such as nuclear factor kappa B and activator protein 1, which play crucial roles in transcriptional regulation of inflammatory genes. The NAD(+)-dependent modifications catalyzed by PARP-1 and SIRT1 liberate NAM, and NAM acts as feedback inhibitor of PARP-1 and SIRT1 through interacting with the enzymes at the binding site for NAD(+). There is increasing evidence that NAM effectively suppresses the expression of inflammatory genes and provides therapeutic benefits in various inflammation-based diseases. The mechanisms underlie the anti-inflammatory properties of NAM might involve the inhibition of PARP-1 and SIRT1.