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Biomedical subjects

T Yagasaki

Publications and source records attributed to T Yagasaki.

13 recordsLinked to original sources

Preventing and preparing for animal health emergencies in the Far East.

The advantageous geographical location of Member Countries of the Office International des Epizooties in the Far East (often islands or peninsulas) provides better isolation than that of countries with terrestrial frontiers. However, in the light of the explosive foot and mouth disease (FMD) outbreak which occurred in Taipei China in 1997 after nearly 70 years of freedom from FMD, countries in the Far East were alerted to the fact that while countries can be physically far or isolated from the rest of the world, they do not necessarily remain protected from epidemics and consequently need to be aware of effective methods of management of animal health emergencies. Countries in the Far East reviewed national management policies from the viewpoint of organisational structure, surveillance system, diagnostic service, vaccine stock, funding, legislation etc., and reconstructed these policies to ensure they were better organised to prevent and control malignant diseases, such as FMD, in the case of an emergency. With the accelerating and increasing movement of animals and animal products internationally, countries in the region met in Tokyo in April 1998 to discuss preparedness and management of animal health emergencies.

Animal Diseases↗

[Lateralization in dissociated vertical deviation with flash visual evoked potentials].

Lateralization, suggesting misrouting of optic nerve fibers in albinism, was examined by the flash visual evoked potentials (flash VEP) test in dissociated vertical deviation (DVD). Eighteen cases of DVD were studied and compared with 5 cases of X-recessive ocular albinism and 4 normal controls. Full-field monocular and binocular stimulation was employed with electroencepharograph electrodes on O1 and O2 (10/20 system), and the latency of P100 was statistically analysed with two-way analysis of variance. The difference in the P100 latency between contralateral and ipsilateral stimulation was significant (p < 0.05) in albinism, but not in DVD and normal controls. Therefore, DVD is probably not associated with misrouting of optic nerve fibers.

Adolescent↗

[Effect of tilting on cyclodeviation in nine diagnostic positions of gaze in normal subjects with Awaya's New Cyclo Tests].

We measured cyclodeviation in all nine diagnostic positions of gaze in normal subjects with the New Cyclo Tests and phase difference haploscope. Measurements with the New Cyclo Tests were carried out in the upright posture, and head tilt 15 or 30 degrees to the right or left. Measurements with the phase difference haploscope were carried out in the upright posture with or without the fusional background. Cyclodeviation in all nine diagnostic positions of gaze measured with the New Cyclo Tests in the upright posture was similar to that measured with phase difference haploscope under the fusional background. Both tests showed that excyclodeviation was significantly greater in upward, right-upward and left-upward gaze than in the primary position. It is concluded that cyclodeviation measured with the New Cyclo Tests is not affected by cyclophoria. The amount of excyclodeviation measured with New Cyclo Tests showed no difference between head tilt postures. We suggest that the effects of head tilting on cyclodeviation could be compensated by the corresponding effect on cyclotorsion of both eyes in normal subjects.

Adult↗

Posterior tenotomy of the superior oblique at the scleral insertion for A-pattern deviations.

A posterior (two-thirds) tenotomy of the superior oblique at the scleral insertion spares the anterior fibers whose action is primarily torsional and can avoid some complications such as cyclovertical diplopia or torticollis, which may be induced by a superior oblique tenotomy or a recession for A-pattern deviations associated with superior oblique overaction (SOOA). A retrospective review was performed of 11 cases with A-pattern, aged 5 to 51 years, who underwent the posterior tenotomy. The average preoperative A-pattern was 18.3 prism diopters and the posterior tenotomy resulted in 16.3 prism diopters of reduction in the A-pattern. There was a good coefficient of correlation between the preoperative amount of A-pattern and the obtained reduction in it (P < 0.001). SOOA was graded on a 9-point system. The average SOOA score of our cases was reduced from +2.77 to +0.77 after the surgery. None of the cases showed worsening of stereoacuity or cyclodeviation. The posterior tenotomy is a simple and effective procedure to correct mild to moderate A-pattern deviations with SOOA.

Adolescent↗

[Studies on the effect of checkerboard pattern on sensory and motor fusion].

We studied the fundamental effects of checkerboard pattern (CP) as fusional background on sensory and motor fusion to clarify the effectiveness of the checkerboard pattern stimulator (CPS), which clinically accelerates anti-suppression and bifoveal fusion in the treatment of manifest strabismus. We studied the size of CP which could generate motor fusion in order to eliminate artificial deviations induced by various powers of prism in Aulhorn's phase difference haploscope, with 20 normal subjects aged from 26 to 30 years old. Seven kinds of check sizes from 0.125 to 5 cycles/degrees (c/d) were presented. We found that a check size of 0.5 c/d or more (narrower check size) had no effect on horizontal motor fusion and that a check size of 1 c/d or more had no effect on vertical motor fusion. To remove suppression, it is important to produce only sensory fusion with the CP. Assuming that the lower limit of visual acuity for CPS is 0.05, the check size needs to be maintained approximately at 1.5 c/d. Our results suggest that a check size of 0.5 c/d for CPS is appropriate to promote sensory bifoveal fusion and stereopsis.

Adult↗

[A case with stereopsis following early surgery for unilateral congenital cataract].

We report a case of stereopsis following early surgery for congenital monocular cataract. The patient was a 3.75-year-old girl who underwent early surgery for congenital monocular cataract at the age of 19 weeks and received an immediate gas-permeable hard contact lens fitting and occlusion therapy consisting of daily patching the sound eye for 6 hours. During the subsequent years, patching was increased to 50% to 80% of the waking day. Three years and two months postoperatively, she showed good visual acuity of 0.7 in the operated eye and also demonstrated stereoacuity of 1200 to 1500 seconds of arc in the Lang Stereotest or the TV-Random Dot Stereo test, duplicatably. From recent reports with excellent results of stereopsis, including this, we conclude that stereopsis is obtainable in patients undergoing congenital monocular cataract extraction by the end of month 2, contact lens fitting with a good compliance, and a progressive regimen of part-time occlusive therapy not to exceed 80% of the waking time.

Cataract↗

Changes in nystagmus after simultaneous surgery for bilateral congenital cataracts.

The presence of nystagmus has been considered as an indicator of poor prognosis in infants with bilateral congenital cataracts. However, of the 10 infants with preoperative nystagmus reported in this study, after simultaneous surgery for bilateral congenital cataracts, 5 cases showed a resolution of nystagmus or reduction to latent nystagmus postoperatively. This study was carried out to clarify what factors resolved or reduced the preoperative nystagmus. Those 5 cases in whom nystagmus was ameliorated postoperatively were operated on within one month after the onset. Age of nystagmus onset, age at surgery or type of cataract did not affect this amelioration of nystagmus. In contrast, the 5 cases who had no postoperative change in nystagmus were operated on later than this period. Our results demonstrate that it is possible to resolve or reduce preoperative nystagmus in bilateral congenital cataracts by a simultaneous bilateral lens removal within one month after the onset of nystagmus.

Cataract↗

[The relationship between the developmental change in visual acuity measurements and change of refractive error in young infants].

219 normal infants aged 3 to 36 months were tested to investigate the relationship between the development of visual acuity and the change of refractive error. 17 infants were tested over a period of time. Visual acuity was assessed by Teller Acuity Cards (TAC), and refractive error was measured by an infrared video refractor (PR1000) without cycloplegics. The results were as follows. 1) The success rate of both tests in 3 to 6 month-old infants was higher than in infants aged 11 to 14 months and 23 to 36 months. 2) Visual acuity showed a rather slow development in infants aged 3 to 12 months. 3) With-the-rule astigmatism of 1 diopter (D) or more occurred with a high incidence in the 3 to 8 month old infants, and decreased with age. 4) The visual acuity in the infants with astigmatism was no different than in those without it. 5) The slow developmental curve of visual acuity measured in 3 to 12-month old infants was probably the result of psychological aversion to the TAC.

Age Factors↗

[Inferior oblique underaction].

We investigated the etiology and incidence of 100 cases of inferior oblique underaction. The difference between congenital and acquired underaction was discussed using Awaya's New Cyclo Tests (NCT) to examine cyclodeviation qualitatively and quantitatively. Inferior oblique underaction had been considered more frequently congenital than acquired. However, 63.0% of our cases were proved to be acquired. The congenital cases were Brown's syndrome and cases of unknown causes and the acquired cases were mainly of myasthenic or traumatic origin. The results of the NCT examination were as follows: incyclodeviation or no cyclodeviation was encountered in all cases of congenital underaction except for one postoperative case, but excyclodeviation rather than incyclodeviation occurred in cases of acquired underaction, which showed ocular torticollis to the side of the paretic eye. This result suggested that some other muscles were involved in acquired cases of seemingly isolated inferior oblique underaction, especially in myasthenia gravis. A diagnosis of myasthenia gravis should be considered first when an acquired inferior oblique underaction occurs with association of excyclodeviation demonstrated by the NCT as well as Cogan's lid twitch sign.

Adolescent↗

Two cases of acquired syphilis with acute central chorioretinitis as initial manifestation.

Acquired syphilis has become an overlooked cause of posterior uveitis including chorioretinitis. Two male cases of bilateral acute acquired syphilitic chorioretinitis were observed, one of whom demonstrated an early delay of choroidal circulation during fluorescein angiography, possibly indicating the choroidal or subretinal neovascular proliferation which occurred later. Although both patients had been treated with oral prednisone for approximately one month before their initial visit to our clinic, good visual recovery had not been achieved. Diagnosis was first confirmed by the positive results of serologic Treponema pallidum hemagglutination and Venereal Disease Research Laboratory tests. The patients were successfully treated with orally administered bacampicillin, which resulted in the complete recovery of visual acuity and normal fundus appearance except for slight pigmentary changes of the retina in the macular area.

Acute Disease↗

Comparison of muscle volume between congenital and acquired superior oblique palsies by magnetic resonance imaging.

Magnetic resonance imaging (MRI) studies of superior oblique (SO) muscles have revealed a high incidence of SO muscle atrophy/hypoplasia in congenital SO palsy patients. It has also been reported that long-standing acquired SO palsy patients show atrophic SO muscles in the affected eye. The purpose of this study was to compare the incidence of SO muscle atrophy/hypoplasia in congenital and acquired SO palsy by utilizing MRI. Coronal MRI image planes were taken from 29 cases of unilateral congenital SO palsy and 9 cases of acquired unilateral SO palsy patients. The SO muscle bellies were traced and their sizes were measured from each image plane. The total volume of the affected superior oblique muscle was compared with that of the normal fellow eye. The mean volume of the affected superior oblique muscle to that of the normal muscle was 45.3% (SD = 30.1) in the congenital group and 65.8% (SD = 22.7) in the acquired group. The volume reduction of the SO muscle in congenital SO palsy patients appears to be mainly a congenital abnormality rather than a secondary change, as seen in acquired SO palsy patients.

Adolescent↗