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In order to clarify the mechanisms underlying the changes in primary afferent neurons in trigeminal neuropathic pain, a chronic constriction nerve injury model of the infraorbital nerve (ION-CCI) was developed in rats. Mechanical allodynia was observed at 3 days after ION-CCI and lasted more than 14 days. Single-unit activities were recorded from the ION of anesthetized rats. C-, Abeta- and Adelta-units were identified on the basis of their conduction velocity. Adelta-units were frequently encountered at a later period after ION-CCI. The highest Adelta-spontaneous activity was recorded at 3 days after ION-CCI and progressively decreased after that, but spontaneous activity was still higher at 14 days after ION-CCI than that of naïve rats. Mechanical-evoked responses of Adelta-units were also highest at 3 days after ION-CCI and then gradually decreased. In consideration of these data, patch-clamp recordings were performed on medium to large size neurons of the dissociated trigeminal ganglion (TRG). Patch-clamp recordings revealed that the IK (sustained) and IA (transient) in rats with ION-CCI were significantly smaller than those of naïve rats, and correlated with an increase in duration of repolarization phase and a decrease in duration of depolarization phase, respectively. The hyperpolarization-activated current (Ih) was significantly larger in TRG neurons of rats with ION-CCI as compared with those of naïve rats. The present results suggest that Ih, IK and IA in Adelta-afferent neurons in TRG are significantly involved in the changes in afferent spontaneous activity and mechanically evoked activity that accompany mechanical allodynia produced by trigeminal nerve injury.

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It has gradually become evident that nanomaterials, which are widely used in cosmetics, foods, and medicinal products, could induce substantial inflammation. However, the roles played by the physical characteristics of nanomaterials in inflammatory responses have not been elucidated. Here, we examined how particle size and surface modification influenced the inflammatory effects of nanosilica particles, and we investigated the mechanisms by which the particles induced inflammation. We compared the inflammatory effects of silica particles with diameters of 30-1,000 nm in vitro and in vivo. In macrophages in vitro, 30- and 70-nm nanosilica particles (nSP30 and nSP70) induced higher production of tumor necrosis factor-α (TNFα) than did larger particles. In addition, intraperitoneal injection of nSP30 and nSP70 induced stronger inflammatory responses involving cytokine production than did larger particles in mice. nSP70-induced TNFα production in macrophage depended on the production of reactive oxygen species and the activation of mitogen-activated protein kinases (MAPKs). Furthermore, nSP70-induced inflammatory responses were dramatically suppressed by surface modification of the particles with carboxyl groups in vitro and in vivo; the mechanism of the suppression involved reduction in MAPK activation. These results provide basic information that will be useful for the development of safe nanomaterials.

BackgroundIn Tak province of Thailand, a number of adolescent students who migrated from Burma have resided in the boarding houses of migrant schools. This study investigated mental health status and its relationship with perceived social support among such students.MethodsThis cross-sectional study surveyed 428 students, aged 12–18 years, who lived in boarding houses. The Hopkins Symptom Checklist (HSCL)-37 A, Stressful Life Events (SLE) and Reactions of Adolescents to Traumatic Stress (RATS) questionnaires were used to assess participants’ mental health status and experience of traumatic events. The Medical Outcome Study (MOS) Social Support Survey Scale was used to measure their perceived level of social support. Descriptive analysis was conducted to examine the distribution of sociodemographic characteristics, trauma experiences, and mental health status. Further, multivariate linear regression analysis was used to examine the association between such characteristics and participants’ mental health status.ResultsIn total, 771 students were invited to participate in the study and 428 students chose to take part. Of these students, 304 completed the questionnaire. A large proportion (62.8%) indicated that both of their parents lived in Myanmar, while only 11.8% answered that both of their parents lived in Thailand. The mean total number of traumatic events experienced was 5.7 (standard deviation [SD] 2.9), mean total score on the HSCL-37A was 63.1 (SD 11.4), and mean total score on the RATS was 41.4 (SD 9.9). Multivariate linear regression analysis revealed that higher number of traumatic events was associated with more mental health problems.ConclusionsMany students residing in boarding houses suffered from poor mental health in Thailand’s Tak province. The number of traumatic experiences reported was higher than expected. Furthermore, these traumatic experiences were associated with poorer mental health status. Rather than making a generalized assumption on the mental health status of migrants or refugees, more detailed observation is necessary to elucidate the unique nature and vulnerabilities of this mobile population.

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