Izumi Koizuka

Ear involvement in patients with rheumatoid arthritis.

Objective: This study evaluates the degree of hearing impairment in patients with rheumatoid arthritis (RA) and examines the correlation between hearing impairment and the clinical data or chemical mediators. Background: Both sensorineural hearing loss (SNHL) and conductive hearing loss (CHL) have been reported in patients with RA, but the results of most studies are not in agreement, and the pathophysiology of hearing impairment in RA is not well known. Methods: Hearing in patients with RA and controls was examined using pure-tone audiometry and tympanometry. Also, the amounts of pro-inflammatory cytokines and matrix metalloproteinases in addition to antibodies against type II collagen in plasma of the patients with RA were determined using enzyme-linked immunosorbent assay. Results: The frequency of SNHL in the patients with RA was higher than in normal controls (36.1% versus 13.9%), and bone conduction at 2,000 Hz differed significantly between the patients with RA and the controls (p < 0.01). Moreover, the presence of SNHL was related to ESR (p < 0.05), plasma interleukin-6 (p < 0.05), and plasma matrix metalloproteinase-3 (p < 0.001). On the other hand, CHL was not observed, whereas As-type tympanograms increased in the patients with RA (p < 0.01). Abnormal tympanograms were not related to any clinical findings or any chemical mediators tested. Conclusion: We demonstrated that there is increased SNHL in patients with RA, which may result from systemic inflammation and tissue injury, and increased latent-type CHL caused by stiffness of the middle ear system whose mechanisms are not yet clear.

Rotation vector analysis of eye movement in three dimensions with an infrared CCD camera.

We have developed a new technique for analyzing the rotation vector of eye movement in three dimensions with an infrared CCD camera based on the following four assumptions; i) the eye rotates on a point; ii) the pupil edge is a circle; iii) the distance from the center of eye rotation to pupil circle remains unchanged despite the rotation; iv) the image of the eye by the CCD camera is projected onto a plane which is perpendicular to the camera axis. After taking digital images of voluntary circular eye movements, we first constructed a three-dimensional frame of reference fixed on the orbita of the subject wearing a goggle equipped with an infrared CCD camera, and determined the space coordinates of the center of eye rotation, the center of the pupil, and an iris freckle. We then took digital images of the eye movements during a saccade or vestibulo-ocular reflex (VOR) and analyzed the axis and angle of the eye movements by the trajectories of the center of the pupil and the iris freckle. Finally, Listings plane of saccade and the gain and the phase of VOR were obtained. The suitability of this technique is examined.

Auditory evoked off-response: its source distribution is different from that of on-response.

OFFSET auditory responses were investigated by electroencephalography mainly in the 1970s, but since then no particular attention has been paid to them. Among the studies using magnetoencephalography (MEG) devices there are, to our knowledge, only three studies of the auditory off-response, and no significant variance has ever been observed between the source locations of on- and off-responses elicited from pure tones. We measured auditory evoked magnetic fields (AEFs) to various frequency pure tone stimulation in 5 healthy subjects with a 122-channel helmet-shaped magnetometer, and compared the distributions of the source locations of auditory N100m-Off (magnetic off-response around 100 ms) with those of N100m-On. Their spatial distributions were quite close to each other, and yet they were significantly different.

Micro‐magnetic resonance imaging of the inner ear in the guinea pig

We applied a magnetic resonance microscopy at 7.05 T with a gradient coil unit to image the fine structure of the guinea pig cochlea. First, a three‐dimensional MR image of the surface of the cochlea was obtained to select the location of cross‐sectional images. Then, cross‐sectional images of the basal turn, the second turn and the apical turn of the cochlea were obtained. Based upon the different protein concentrations of the endolymph vs the perilymph, the scala vestibuli, scala tympani and the cochlear duct could be clearly distinguished. This allowed a determination of the location of both the basilar membrane and Reissners membrane. We raise the possibility that MRM may become useful in the diagnosis of endolymphatic hydrops (Menieres disease).

Life‐style and environmental factors in the development of nasal NK/T‐cell lymphoma: A case–control study in East Asia

Cases of nasal NK/T‐cell lymphoma (NKTCL) occur occasionally in Asian and Latin American countries but rarely in Western countries. The etiological role of life‐style and environmental factors in nasal NKTCL was investigated. Five university hospitals in Japan and one each in Korea and China participated in this study; a total of 88 cases and 305 hospital controls were accrued during 2000–2005. The odds ratio (OR) of NKTCL obtained after adjustments of age, sex and country was 4.15 (95% confidence interval (CI), 1.74–9.87) for farmers, 2.81 (CI, 1.49–5.29) for producers of crops, 4.01 (CI, 1.99–8.09) for pesticide users, 11.65 (CI, 1.17–115.82) for residents near garbage burning plants, 2.95 (CI, 1.25–6.95) for former drinkers, and 0.49 (CI, 0.23–1.04) for current smokers. The ORs for crop producers, who minimized their exposure to pesticides by using gloves and glasses, and sprinkling downwind at the time of pesticide use, were 3.30 (95% CI, 1.28–8.54), 1.18 (95% CI, 0.11–12.13) and 2.20 (95% CI, 0.88–5.53), respectively, which were lower than those for producers who did not take these precautions. Exposure to pesticides and chemical solvents could be causative of NKTCL. Taken together, life‐style and environmental factors might be risk factors for NKTCL.

Three-Dimensional Eye Rotation Axis Analysis of Benign Paroxysmal Positioning Nystagmus

We have developed a new technique for analyzing the rotation vector of eye movement with an infrared CCD camera [Imai et al.: Acta Otolaryngol 1999;119:24–28]. We used this technique to analyze the eye rotation axis of benign paroxysmal positioning nystagmus (BPPN) that was induced by the Dix-Hallpike maneuver in 14 patients with benign paroxysmal positioning vertigo (BPPV). Eye rotation axes of BPPN in 8 patients were closely perpendicular to the posterior canal of the undermost ear in the provocative head position. Under the hypothesis that BPPN is due to a mechanical stimulation of the posterior canal by canalolithiasis, this finding suggested that the posterior canal of the undermost ear is the lesion. On the other hand, eye rotation axes of BPPN in the other 6 patients were closely aligned with the naso-occipital axis. It is suggested that canalolithiasis induces endolymphatic flow in both posterior and anterior canals via the common crus and the summation of the eye movements induced by stimulation of both the posterior and anterior canals rotates the eye along the naso-occipital axis.

Ipsilateral Dominance of Human Olfactory Activated Centers Estimated from Event‐Related Magnetic Fields Measured By 122‐Channel Whole‐Head Neuromagnetometer Using Odorant Stimuli Synchronized with Respirations

ABSTRACT: The aim of this study was to measure and analyze olfactory event‐related magnetic fields using a whole‐cortex biomagnetometer (122‐channel SQUID gradiometer). Amyl‐acetate gas (approx. 1%) was administered for 300 msec into either the right or left nostril in synchronization with respiration using a mask and an optical fiber sensor. Clear olfactory event‐related magnetic fields were asymmetrically obtained on both sides of the forehead in all six subjects. The generators of olfactory magnetic fields were estimated at two regions located fairly asymmetrivally near the bilateral frontal deep areas. The goodness‐of‐fit was better for the two‐dipole model than the one‐dipole model in all experiments.

Evaluation of the otolith function using sinusoidal off-vertical axis rotation in patients with benign paroxysmal positional vertigo

The vestibulo-ocular reflex (VOR) was studied via sinusoidal off-vertical axis rotation (OVAR) to evaluate the otolith function in patients with benign paroxysmal positional vertigo (BPPV). Subjects were sinusoidally rotated with eyes open in complete darkness at frequencies of 0.4 and 0.8 Hz with a maximum angular velocity of 60 degrees s(-1) in earth-vertical axis rotation (EVAR) and OVAR. Twenty-three controls and 24 BPPV patients were investigated. Results showed that VOR gain during OVAR at 0.8 Hz in a 30 degrees nose-up position in BPPV patients was significantly less than the gain during EVAR, whereas the gain was not significantly different between EVAR and OVAR in the controls in each condition. In addition, to examine each type of BPPV, we also investigated whether there were any differences between the patients who suffered from dizziness and those who did not. VOR gain in OVAR of BPPV patients who were suffering from dizziness was significantly less than that of BPPV patients without dizziness. Not only cupulolithiasis or canalolithiasis, but also otolith dysfunction was considered to be the possible origin of BPPV. Because sinusoidal OVAR produced minimal nausea compared to constant velocity OVAR, the stimulation of 0.8 Hz nose-up in sinusoidal OVAR may be used to evaluate otolith function without discomfort for patients.

Absence of Nuclear p16 From Epstein-Barr Virus-Associated Undifferentiated Nasopharyngeal Carcinomas

Objective: Epstein‐Barr virus (EBV) is detected in the majority of undifferentiated nasopharyngeal carcinomas (UNPCs, World Health Organization type III). However, the exact mechanism involved in the carcinogenesis of EBV‐associated UNPCs remains to be elucidated. An important unresolved question is: how is the normal cell cycle deregulated during EBV‐associated UNPC development? The p16CDKN2 gene encodes a nuclear protein, p16, which inhibits the D‐type cyclin/cyclin‐dependent kinase complexes that phosphorylate the retinoblastoma gene product (pRb), thus blocking G1 cell cycle progression. The objective of this study was to determine whether p16 absence is involved in the development of EBV‐associated UNPCs.

Effect of adaptive plasticity of linear vestibulo-ocular reflex upon angular vestibulo-ocular reflex

OBJECTIVE The vestibulo-ocular reflex (VOR) produces compensatory eye movements during head movements. The VOR consists of the angular VOR and the linear VOR. The VOR is under adaptive control that corrects VOR performance when visual-vestibular mismatch arises during head movements. Most experiments concerning plasticity of the VOR have used the angular VOR. So far, there has been no investigation on the effect of adaptive plasticity of the linear VOR on the angular VOR. In this study, using a linear sled, we tested the hypothesis that the angular VOR is altered by changes in the linear VOR. METHODS To modify the linear VOR, we used an adaptation paradigm. Eight subjects were translated sinusoidally at 0.125 Hz and 0.16 g peak acceleration along their inter-aural axis for 40 min, while viewing earth-fixed vertical stripes on the wall while wearing the binocular magnifying lenses. Six of the eight subjects showed an increase in linear VOR sensitivity after adaptation. Each of the six subjects who showed an increase in linear VOR sensitivity after adaptation also showed an increased angular VOR gain at 0.125 Hz. CONCLUSION These results suggest that the linear VOR and the angular VOR share common neural pathways in such a way that a change in the synaptic efficacy of one pathway is accompanied by a commensurate change in the other.