Biomedical subjects

E Adachi-Usami

Publications and source records attributed to E Adachi-Usami.

At least 19 recordsLinked to original sources

PubMed1995

Three cases of grouped pigmentation of the retina.

We examined three patients with congenital grouped pigmentation of the retina by means of electroretinography, electro-oculography and visually evoked cortical potentials. Two patients were affected bilaterally and 1 had a unilateral condition. Electrophysiological findings were normal in all patients, and no inheritance patterns for the disease were found in any of the patients' histories. Only 5 cases of this disease have been reported in Asian countries in recent years. We believe that our patients contribute to the sample of such cases regarding racial prevalence.

Adult↗

PubMed1994

Electrophysiological studies on light damage in the mouse retina after sodium iodate injection.

Acute experimental retinal degeneration was induced in 3-month-old mice with sodium iodate (NaIO3) injection to investigate the effect of bright light with electroretinography (ERG). Eight C 57 black male mice were anesthetized. The ERG was recorded before and 24 h after the injection of NaIO3. Next, only one eye of each mouse was exposed to a bright light of 3.0 x 10(4) lx white light for 30 min. Ten hours later, ERGs of both the light-exposed and the unexposed eye were recorded. The amplitudes and peak latencies of the a wave and b wave were measured. The ERG was recorded as both eyes were exposed to stimulating flashes that were given in an increasing order of 0.6 log unit steps from the dimmest flash to produce a detectable ERG. The ERG from the light-exposed eye showed a distinctly elevated threshold (approx 2.0 log), while the contralateral unexposed eye did not. The peak latencies of both waves were significantly prolonged by exposure to light. In conclusion, light exposure affected ERG thresholds in mice with experimentally induced acute retinal degeneration.

Animals↗

PubMed1994

Distribution of phosphate-activated glutaminase-like immunoreactivity in the retina of rodents.

The distribution of phosphate-activated glutaminase-like immunoreactivity was examined in the retinas of rodents. Intense glutaminase immunoreactivity was observed in many neuronal perikarya in the ganglion cell layer and inner nuclear layer including those of ganglion, bipolar and amacrine cells and possibly horizontal cells. Almost all bipolar cells containing protein kinase C were immunoreactive for glutaminase, suggesting that the majority of glutaminase immunoreactive bipolar cells were of the ON type. Intense glutaminase immunoreactivity was also found in the neuropil of the inner and outer plexiform layers and around the outer limiting membrane. Weak to moderate immunoreactivity was seen in the outer nuclear layer and photoreceptor inner and outer segments. Under electron microscopy, glutaminase immunoreactivity was seen in bipolar cell axons and amacrine cell processes in the inner plexiform layer. In the outer plexiform layer, immunoreactivity was found in the Müller cell processes, but not in the photoreceptor cell terminals. These results indicate that ganglion cells and ON type bipolar cells use glutaminase to produce transmitter glutamate and suggest glutaminase has additional roles in Müller cells. A population of amacrine cells and horizontal cells showed immunoreactivity to glutaminase.

Animals↗

PubMed1993

Electroretinographic effects of haloperidol on the mouse retina.

The effects of haloperidol on the electroretinogram were studied in mice injected intraperitoneally with haloperidol. A dose-related study was performed. A significant decrease in the amplitude of the b-wave was found in the mice injected with more than 20 mg/kg of haloperidol. However, the peak latency of the b-wave and the stimulus intensity required to elicit a b-wave of one half of the maximum b-wave amplitude remained unchanged. No significant changes were found in the a-wave. This change in the electroretinogram recovered 24 hours after the injection. These results suggest that functional change occurred at the retinal level after intraperitoneal injection of haloperidol.

Animals↗

PubMed1993

Early effects of sodium iodate injection on ERG in mice.

The electroretinogram (ERG) was recorded in 15 ICR albino mice before and 2, 4 and 24 h after injection of 40 mg/kg of NaIO3 and the results were compared with the corresponding ultrastructural findings. Both a- and b-wave amplitudes decreased at 2 h after injection and increased at 4 h to the levels before injection and further increased at 24 h after injection. The b-wave threshold intensity increased by 2.1 log units at 2 h after injection. Thereafter, it decreased once at 4 h and significantly increased at 24 h by 3.4 log units. Electron microscopic examination showed swollen cytoplasmic organelles of the retinal pigment epithelial cells at 4 h after injection. It was thus demonstrated that an early effect of NaIO3 on the electrical response of the mouse retina was more conspicuous than histopathological changes.

Animals↗

PubMed1993

A case of Kearns-Shy syndrome with later onset.

We report a case of Kearns-Shy syndrome in a 44-year-old woman. She complained of bilateral ptosis, exotropia and gait disturbance. Diffuse chorioretinal degeneration and numerous punctate whitish spots were observed in both fundi. Eye movements were severely disturbed. An electroretinogram was almost nonrecordable, while visually evoked cortical potentials to pattern stimulation were normal. The dark adaptation curve showed an elevation of rod threshold. Besides such ophthalmological findings, muscle weakness, extinguished tendon reflex and healing difficulty were observed. Blood lactate, pyruvic acid and serum creatinine kinase were at high levels. A muscle biopsy showed ragged-red fibers and partial deficiency of cytochrome c oxidase. The patient is being treated with coenzyme Q, and we are now following up the therapeutic effects of this treatment.

Adult↗

PubMed1992

Effect of number of test points in automated perimetry.

We studied sensitivity variation in normal subjects by changing the number of test locations under the fixed test field on automated perimetry. Using the user-defined program (Sargon), we designed five different programs that varied in the number of test points. Mean sensitivity and short-term fluctuations were obtained from the same test points of each program. The mean sensitivity within 10 degrees decreased with the increasing number of test points, whereas the short-term fluctuation increased with the increasing number of test points. Our results showed that the number of test points had an important role in measuring sensitivity and its reproducibility on automated perimetry.

Adult↗

PubMed1992

Effect of number of test points and size of test field in automated perimetry.

Sensitivity variation in normal subjects was studied, by changing the number of test locations and the size of test fields on automated perimetry. Using the Sargon program, four different programs that differed in the number of test points or in the size of test field were made. Mean sensitivity and short-term fluctuation were calculated from the same test points of each program. The program with the fewest points and the smallest size produced the greatest sensitivity and the least fluctuation. Our results showed that the number of test points and the size of test field affected the sensitivity and its reproducibility in automated perimetry.

Adult↗

PubMed1992

Assessment of central visual function after successful retinal detachment surgery by pattern visual evoked cortical potentials.

The pattern of visual recovery after successful surgery by pattern visual evoked cortical potentials (VECP), visual acuity, colour vision, and critical fusion frequency was investigated in 14 eyes with retinal detachment involving the macula. The temporal tuning characteristics in the evoked potentials were measured as based on the P100 amplitude and the frequency necessary for evoking 0 mu V amplitude, which was defined as an objective critical fusion frequency by extrapolating the curve. Significant improvement in visual acuity and colour vision was observed within 2 months postoperatively. A significantly increased P100 peak latency became shorter as the postoperative days increased. In general, a good correlation was noted between the P100 peak latency and subjectively measured visual acuity, colour vision, and critical fusion frequency. The objective critical fusion frequency measured by VECP recovered gradually during the 6 months after surgery. Functional recovery was not related to the length of time the macula was detached before surgery.

Adolescent↗

PubMed1992

Increased sensitivity with decreased numbers of test points and decreased test field size in automated perimetry of normal subjects.

Mean sensitivity (MS) was compared among programs with different numbers of test points and different test field sizes with an automated perimeter in normal subjects. The programs tested were designed by the program Sargon. Within a 10-degree visual field the MS was significantly higher with fewer test points and with a smaller test field size. The MS between 10 and 25-degree fields increased under the same conditions. Increased MS was found with decreased numbers of test points and decreased test field size within 25 degrees in automated perimetry of normal subjects.

Adult↗

PubMed1992

[Effects of MPTP on the mouse retina].

MPTP is known as a selective neurotoxin which destroys dopamine-containing neurons, and induces a model of Parkinson's disease. In the retina, MPTP acts on the amacrine cells which contain dopamine. In the present study, C57BL/6J mice were treated i.p. with MPTP (cumulative dose, 150 mg/kg), and the role of dopamine in the mouse retina was investigated electrophysiologically and immunohistochemically. ERGs were recorded before and 10, 30 and 50 days after MPTP injection. The amplitude of the oscillatory potentials was greatly reduced, and that of the b-wave to a lesser degree, while the a-wave was slightly reduced 10 days after injection. These ERG changes tended to return to the control level 50 days after injection. Immunohistochemical analysis showed that 10 days after MPTP injection the number of tyrosine hydroxylase positive amacrine cells was reduced by approximately 50%, and that these changes had lasted at least until 50 days after MPTP injection.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1992

Transient increase of b-wave in the mouse retina after sodium iodate injection.

Twenty C57 black mice received an injection of 40 mg/kg of sodium iodate through the caudal vein. The electroretinograms (ERGs) were recorded before and after injection. Flash stimuli with the maximum illuminance, 30,000 lux, were given at increasing levels of illuminance in 0.6 log U steps for 13 levels of intensity. The a- and b-wave amplitudes increased linearly with increased stimulus intensity for approximately 5.0 log U before being saturated. Twenty four hours after injection, the intensity-amplitude curve shifted toward the higher intensity region. It was calculated that the sensitivity loss of the b-wave after injection was 2.0 log U, although the maximum amplitude was larger and the peak latency was delayed. The same results were seen less obviously in the ERGs 48 hr after injection. After 96 hr, both waves were greatly attenuated and even abolished. At the time the increased ERGs were recorded, the histopathologic findings exhibited severe damage of the retina in the pigment epithelium and in the outer layer.

Animals↗

PubMed1992

Apparent accommodation in pseudophakic eyes as measured with visually evoked potentials.

We measured apparent accommodation with pattern reversal visually evoked cortical potentials in 27 pseudophakic eyes after the implantation of posterior chamber intraocular lenses. The patients ranged in age from 47-83 years. The amplitude of accommodation was not significantly different between pseudophakic eyes and normal phakic eyes. Apparent accommodation was inversely proportional to the pupillary diameter and was significantly correlated with corneal astigmatism. No significant relationship was noted between apparent accommodation and age of patients, corrected visual acuity, or refractive error.

Accommodation, Ocular↗

PubMed1991

Senile changes of crystalline lens: effects on the delayed latency of pattern visually evoked potentials in phakic and pseudophakic eyes.

We recorded visually evoked cortical potentials to pattern stimuli (PVECPs) in 22 patients who received a posterior chamber intraocular lens implant. The mean latency of the P100 obtained from patients was not significantly different from that of age-matched normal phakic subjects. Furthermore, we found that both groups showed a similar increased delay of the P100 latency with age. The results of this study indicated that the senile opacity of the crystalline lens does not contribute to changes of PVECPs with age. These alterations may be due to senile changes of the neural pathway.

Aged↗

PubMed1991

Effect of test field size on the results of automated perimetry in normal subjects and patients with optic neuritis.

The mean sensitivities of the same 8 central test points were compared in two different programs of an automated Octopus perimeter in normal subjects and in patients recovered from optic neuritis (visual acuity 0.8 or better). The programs differed in terms of the size of the stimulated visual field. One program tested the central 30 degrees and the other, central 8.4-degree visual field. It was found that the mean sensitivity tended to become higher when stimulating small field size in both normal persons and patients with optic nauritis.

Adolescent↗

PubMed1991

Pattern visually evoked cortical potential and magnetic resonance imaging in optic neuritis.

We studied the extent of optic nerve lesion with magnetic resonance imaging (MRI) in 24 patients with optic neuritis and compared it with visually evoked cortical potentials (VECP). Patients were divided into acute and chronic stage groups according to the duration of the disease from its onset. The short TI inversion recovery (STIR) mode of the MRI was selected for study. In the acute stage group, abnormally high signals of optic nerve on MRI were demonstrated in 11 of 12 eyes, and the amplitude and peak latency of pattern VECP were unrelated to the extent of the optic nerve lesion visualized by MRI. Conversely, in the chronic stage group, the abnormal MRI findings were exhibited in 19 of 23 eyes, and the relationship between the measurements was statistically significant. This difference in the optic nerve lesion observed by MRI between the acute stage and the chronic stage of optic neuritis may indicate pathophysiologic differences in their origins.

Acute Disease↗

PubMed1990

Electroretinograms and pattern visually evoked cortical potentials in central areolar choroidal dystrophy.

We describe three patients with central areolar choroidal dystrophy whose electroretinograms (ERGs) and pattern visually evoked cortical potentials (VECPs) confirmed their macular dysfunction. Visual fields measured by Goldmann perimetry showed central relative scotomata corresponding to a dystrophic lesion. Dark adaptation curves were slightly abnormal either in the first curve or in the second curve, depending on the visual acuity. Color vision was disturbed irregularly. Fluorescein angiography revealed a loss of the choriocapillaries, and a hyperfluorescent border outlined the dystrophic lesion. Single-flash dark-adapted ERGs and scotopic ERGs were almost normal, while photopic and flicker ERGs showed slightly attenuated amplitudes. Conversely, VECPs to pattern reversal stimulation were greatly affected for both transient and steady-state stimuli. We conclude that, in central areolar choroidal dystrophy, pattern VECPs can provide more information on macular dysfunction than does the ERG.

Adult↗

PubMed1990

Haloperidol delays visually evoked cortical potentials but not electroretinograms in mice.

Visually evoked cortical potentials (VECPs) and electroretinograms (ERG) to flash stimulation were studied in one ICR strain mouse and 23 ICR mice, respectively. The effect of a dopamine receptor blocker, haloperidol, on both responses was investigated. Significant peak latency prolongation was found in VECPs following injection of haloperidol, while the amplitude reduction of the b-wave was found in ERG. No effect of anesthetics only on ERG was found. It has been assumed that haloperidol affects VECPs related function mainly the higher visual pathway. However, the slight decrease of the b-wave amplitude of ERG could not exclude the possibility of the toxic effect on the retina.

Animals↗