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T Tokoro

Publications and source records attributed to T Tokoro.

174 records · Page 10Linked to original sources
PubMedDate not supplied

Multicenter genetic study of retinitis pigmentosa in Japan: I. Genetic heterogeneity in typical retinitis pigmentosa.

A nationwide, multicenter study of typical retinitis pigmentosa (RP) was carried out in collaboration with 18 hospitals throughout Japan to obtain current information for genetic counseling. We analyzed the genetic heterogeneity of RP based on the parental consanguinity of 434 probands registered during a 6-month period in 1990. A gradual decline in the frequency of consanguineous marriage was recognized among the normal parents of RP patients. The relative frequencies of inheritance patterns were estimated as: autosomal recessive, 25.2%; autosomal dominant, 16.9%; X-linked, 1.6%; and simplex, 56.3%. A comparison of these results with previous reports in Japan revealed a decline in the relative frequency of autosomal recessive cases and an increase in simplex cases. This suggests a decrease in the incidence of autosomal recessive retinitis pigmentosa in Japan, as well as the necessity for exhaustive investigations aimed at identifying inheritance patterns for RP patients seeking genetic counseling.

Adolescent↗
PubMedDate not supplied

Multicenter genetic study of retinitis pigmentosa in Japan: II. Prevalence of autosomal recessive retinitis pigmentosa.

Retinitis pigmentosa (RP) is a group of genetically heterogeneous diseases with autosomal recessive (AR), autosomal dominant, and X-linked modes of inheritance. Autosomal recessive retinitis pigmentosa (ARRP) is the most common form in Japan. A genetic analysis was done to determine the prevalence of ARRP indirectly, to provide an estimation of changing trends in the overall prevalence of RP. Data on the frequency of consanguinity and marriage year of normal parents of 59 ARRP patients were obtained from a nationwide multicenter survey of typical retinitis pigmentosa conducted in 1990. The gene frequency of ARRP was 0.01145 (Dahlberg's formula). In 1990, the number of young symptomatic ARRP patients decreased, while the number of patients aged 40 years and older increased. The total number of symptomatic ARRP patients in 1990 was nearly 21% higher than in 1970. Despite a dramatic decline in consanguinity in recent decades in Japan, the number of ARRP patients has increased. This increase is attributed to greater longevity and overall population growth. Our results suggest that the total number of RP patients has not decreased, and may even have increased.

Adolescent↗
PubMedDate not supplied

Measurement of temporal summation of visual acuity with use of modified tachistoscope.

Visual acuity was measured in 18 normal eyes of 10 subjects ranging in age from 20 to 30 years, using a modified tachistoscope. We changed the exposure duration of the target (1-1000 msec) or background luminance (0.1-200 cd/m2). Visual acuity improved with increasing duration of exposure. At background luminance over 10 cd/m2, critical duration time was approximately 500 msec. At low luminances below 10 cd/m2, however, critical duration was prolonged. This tendency was also seen when pupil diameter was fixed at 3 mm using an artificial pupil. Visual acuity also could be determined as the product of background luminance and exposure duration. We concluded that these findings follow the Bloch-Bunsen-Roscoe law.

Adult↗
PubMedDate not supplied

Indocyanine green angiographic findings of lacquer cracks in pathologic myopia.

Lacquer cracks are thought to represent healed mechanical breaks in the retinal pigment epithelium, Bruch's membrane, and choriocapillaris complex. In this study, we analyzed the indocyanine green (ICG) angiographic features of lacquer cracks and compared them with findings using fluorescein angiography. Complete ophthalmologic examinations, fluorescein angiography, and ICG angiography were performed in 29 consecutive patients (37 eyes) with lacquer cracks. Fluorescein angiograms of the cracks revealed linear hyperfluorescence in all 37 eyes. Using ICG angiography, we observed linear hypofluorescence in all 37 eyes. In 15 of 37 eyes, the length of the hypofluorescent lesion detected by ICG angiography was longer than the hyperfluorescent lesion observed by fluorescein angiography. In 17 of 37 eyes, more lacquer cracks were observed by ICG angiography than by fluorescein angiography. These findings indicate that ICG angiography can detect the development of the lesion more precisely, and may provide useful information for diagnosing pathologic myopia.

Adolescent↗
PubMedDate not supplied

Processes of blue light-induced damage to retinal pigment epithelial cells lacking phagosomes.

PURPOSE: To experimentally clarify the processes of the changes induced by blue light directly on the retinal pigment epithelium (RPE) before the formation of phagosomes or the accumulation of lipofuscin. METHODS: We developed a new experimental method in which primary cultured cells of very young pigmented rats were exposed to several intensities and durations of blue light (wavelength = 440+/-10 nm). RESULTS: At 1.0 mW/cm2, the damage was limited to mitochondria. At 2.0 mW/cm2, the cytoplasm exhibited large whorls of membrane or whorled inclusions, which were consistent with autophagic vacuoles. At 4.0 mW/cm2, the RPE cells showed lysis of the cytoplasm and a nucleus that was consistent with necrosis. CONCLUSIONS: Our results suggested that damage induced by blue light to cultured RPE cells may originate in the mitochondria and end in necrosis. The type of cell death induced in the RPE by blue light seems to be determined mainly by the intensity of the light, but is also related to the duration of exposure.

Animals↗
PubMedDate not supplied

Bilateral large peripapillary venous and arterial loops.

BACKGROUND: Peripapillary loops of venous origin are extremely rare. CASE: A 55-year-old woman was referred to us for further examination of peripapillary vascular abnormalities. OBSERVATIONS: Fundus examination and fluorescein angiography clearly showed a venous and an arterial peripapillary loop in both her right and left fundi. The venous loop in the right eye was in a large hairpin configuration, extending into the retina about 1 disc diameter from the optic disc. Fluorescein angiography in the left eye revealed slow and irregular filling of dye into a venous loop that showed stasis of the bloodstream through the loop. Various retinal vascular abnormalities, including cilioretinal artery and triple branching of the retinal vein were also observed. CONCLUSION: The findings in this case of bilateral peripapillary venous and arterial loops and unilateral trifurcation of retinal vein suggest that there could be an association in the other retinal abnormalities. Periodic follow-up examinations seem necessary.

Coloring Agents↗
PubMedDate not supplied

Disturbance of electrolyte balance in vitreous of chicks with form-deprivation myopia.

PURPOSE: To investigate the changes in the electrolyte and protein concentrations in the vitreous of 3-week-old chicks with form-deprivation myopia (FDM). METHODS: FDM was induced in 2-day-old male white leghorn chicks by covering the left eye with a translucent plastic goggle and leaving the right eye uncovered to serve as control. After 19 days the animals were euthanized, and the axial dimensions of the eyes were measured with a caliper in an unfixed condition. The liquid vitreous and aqueous humor were removed by paracentesis, and blood was collected from the jugular vein. Sodium, potassium, and chloride concentrations were determined using ion-selective electrodes. Calcium and phosphate concentrations were determined by colorimetric assays using orthocresol phthalein complexone and bacterial xanthine oxidase, respectively. RESULTS: The concentrations of potassium and phosphate were decreased, whereas chloride concentration was increased in the vitreous of the FDM eyes (P < .01). Sodium and calcium concentrations were similar to those in the control eyes. No significant changes in the concentration of electrolytes were observed in the aqueous humor. No significant differences were found in the protein concentrations in the liquid vitreous, gel vitreous, and aqueous humor. CONCLUSIONS: Form-deprivation induced a significant increase of the volume of the liquid vitreous in the eye of the FDM chick. The increased liquid vitreous of the myopic eye was accompanied by an alteration of the electrolyte balance, by a mechanism that has not yet been clarified.

Animals↗
PubMedDate not supplied

Case report: indocyanine green dye leakage from retinal artery in branch retinal vein occlusion.

BACKGROUND: Little is known about retinal vascular lesions underlying hemorrhage in the acute phase of branch retinal vein occlusion (BRVO). CASE: A 64-year-old woman presented with a decrease in visual acuity of ten-day duration in her left eye. OBSERVATIONS: At the initial examination, her left fundus showed the typical appearance of BRVO, including retinal bleeding and soft exudates in the lower half of the fundus, after the arteriovenous crossing. Fluorescein angiography showed no detail in the retinal vessels, which were occluded by retinal bleeding. However, in the early phase of indocyanine green (ICG) angiography, ICG dye leaked from the retinal artery at a point proximal to the first bifurcation. In the late phase of ICG angiography, the dye pooled along the retinal artery in a fusiform fashion. One year after laser photocoagulation was performed in the area of the BRVO, ICG dye leakage from the retinal artery had completely disappeared. CONCLUSIONS: These findings suggest that the changes in the retina detected by ICG angiography may have been associated with the onset of BRVO. In patients with acute BRVO, ICG angiography may be used to evaluate retinal arterial lesions covered by hemorrhage and provide useful information.

Capillary Permeability↗
PubMedDate not supplied

Nitric oxide synthase expression in ischemic rat retinas.

PURPOSE: To investigate the expression of nitric oxide synthase (NOS) in the ischemic retina. METHODS: Retinal ischemia was induced in rats by bilateral common carotid artery occlusion (BCCAO) for various lengths of time. Using the retina after BCCAO, expression of neuronal NOS (nNOS) and inducible NOS (iNOS) and identification of their positive cells were studied by histological and immunohistochemical examinations. RESULTS: Histological examinations revealed significant reduction in the thickness of the inner plexiform layer and the outer plexiform layer of the retina. Expression of nNOS was detected in retinal ganglion cells, amacrine cells, and Müller cells after BCCAO. The expression of nNOS and iNOS detected in Müller cells became stronger and persisted long after BCCAO. CONCLUSIONS: In the ischemic retina, Müller cells and retinal ganglion cells expressed nNOS and iNOS. These phenomena may be involved in the ischemic damage to the retina.

Animals↗