An upper respiratory tract obstruction due to nasopharyngeal diseases such as allergic rhinitis and tonsillar hypertrophy/sinusitis in growing children inhibits normal nasal breathing and leads to oral breathing. One symptom of this phenomenon appearing in the living body is hypoxia. Typically, it is rare for hypoxia associated with an upper respiratory obstruction to become severe and cause dyspnea, and it generally causes mild hypoxia. However, there are no previous reports regarding the effect of mild hypoxia on the living body. Thus, in this study, in order to examine the effect of mild hypoxia on the entire body, alterations in the immune system of growing rats using a mild hypoxia exposed model were evaluated.
　Six-week-old Wistar male rats were used(n=60)and assigned to either the mild hypoxia group(18% FIO₂)or control group. In both groups, five experimental time points, days 1, 3, 7, 14, and 21, were set. After the rats were sacrificed at each time point, the spleen was removed and the natural killer(NK)cell ratio(CD3^-/CD161⁺)in splenic lymphocytes were compared by flow cytometry.
　The NK cell ratio of the day 1 group within the mild hypoxia group was significantly higher compared to that of the control group(P<0.05). Moreover, the NK cell ratio of the mild hypoxia groups indicated were significantly lower than those of the control groups for day 7, 14, and 21(P<0.05).
　The exposure to mild hypoxia in growing rats may change the NK cell ratio in the splenic lymphocytes.

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　The purpose of this study was to evaluate brain MRI distortion caused by orthodontic appliances. MRI was performed in 10 subjects and after insertion 3 kind of orthodontic appliances(type1-3), the MRI were compared. Type 1 used resin brackets in the incisor teeth, stainless steel brackets in the premolar teeth and stainless steel single tube in the molar teeth. Type2 used ceramic brackets in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Type3 used ceramic brackets with CoCr alloy clip in the incisor teeth, titanium brackets in the premolar teeth and titanium single tube in the molar teeth. Each MR sequence consisted of 6 sequences.: the Echo Planar Imaging method diffusion-weighted images(DWI), Spin Echo sequence(SE)T1-weighted images, Fast Field Echo sequence(FFE)T1-weighted images, Turbo Spin echo sequence(TSE)T2-weighted images, fat-supression image as Short Tau inversion recovery method(STIR), and Fluid attenuated-inversion recovery(FLAIR).Two neurosurgeons examined the MRI for distortion in predetermined regions of the brain. In Type 1, MRI imaging by neither DWI nor FFE is feasible in these sites. SE-T1, TSE-T2, FLAIR and STIR are indicating the feasibility for MRI imaging. In Type 2 and Type 3, by all imaging types and at all of the anatomical sites, are indicating the feasibility for MRI imaging in the brain. The study showed that ceramic brackets, ceramic brackets with CoCr alloy clip, titanium brackets and titanium tubes do not always have to be removed before brain MRI.

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　Orthodontic root resorption(ORR)is an unavoidable pathological consequence of orthodontic tooth movement. Swinging of the root due to the reciprocating movement of the tooth(jiggling)mayexacerbate ORR.However, little is known about the mechanism how jiggling induces ORR. We herein investigated the tumor necrosis factor(TNF)-α expression in odontoclasts in resorbed roots by jiggling force in vivo.
　Twenty-four eight-week old of male Wistar rats were divided into four groups, a heavy force group(HF:50g), optimal force group(OP: 10g), jiggling force group(JF: compression and tension, repetition; 10g)and a control group(no appliances: 0g). The expression levels of the TNF-α protein in odontoclasts in the dental root were determined using an immunohistochemical analysis.
　The immunoreactivity for TNF-α in resorbed roots exposed to the jiggling force was stronger than that in the other groups on day 21. The number of TNF-α-positive odontoclasts was significantly increased in the JF group on day 21 compared with the other groups.
　These results suggest that a jiggling force may aggravate ORR via TNF-α expression during orthodontic tooth movement.

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　We describe a case of trigeminal neuralgia caused by compensatory enlargement of the basilar artery in a patient with bilateral agenesis of the internal carotid arteries.
　A 46-year-old man experienced sharp, stabbing pain in the left face when washing his face. In imaging examinations, magnetic resonance imaging(MRI)revealed displacement of the left trigeminal nerve due to basilar artery enlargement and leftward deviation, but no brain tumors or other abnormalities. The left internal carotid artery was not visible on magnetic resonance angiography(MRA), but marked enlargement of bilateral vertebral and basilar arteries was seen, along with considerable leftward deviation of the basilar artery. The anterior and middle cerebral arteries constituting the anterior circulation were bilaterally connected with the posterior communicating artery, which was enlarged. Bilateral internal carotid arteries were vestigially interrupted from the bifurcation of the common carotid artery. No carotid canals were apparent on either side on computed tomography(CT). For his symptoms, we managed his pain using carbamazepine, and instructed to follow a low-salt, low-fat diet and to avoid excessive alcohol consumption.
　Our case report suggest that imaging examination(e.g. CT, MRA and MRI)are essential when investigating trigeminal neuralgia, in order to visualize the head and neck region and identify any causal vessels and confirm the presence or absence of tumors. In addition, patients with abnormal hemodynamic status such as agenesis of an internal carotid artery or megadolichobasilar anomaly should undergo regular follow-up due to the high risk of cerebral hemorrhage and cerebral infarction.

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