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Biomedical subjects

M Itoi

Publications and source records attributed to M Itoi.

At least 55 records · Page 3Linked to original sources
PubMed1984

Keratoconus with pellucid marginal corneal degeneration.

Examination of 1,625 Japanese patients with keratoconus and 20 patients with pellucid marginal corneal degeneration showed that 17 patients with pellucid degeneration also had keratoconus in the central portion of the cornea. Three patients with pellucid degeneration without keratoconus showed bilateral involvement. Among the 17 cases of pellucid degeneration with keratoconus, eight patients showed bilateral involvement and the others showed unilateral involvement. Pellucid marginal corneal degeneration with or without keratoconus may be a variant of keratoconus or a different manifestation of the same etiologic factor.

Adult↗
PubMed1984

Cytofluorometric nuclear DNA determinations on human corneal endothelial cells.

In order to investigate polyploidization of human corneal endothelium, nuclear DNA cytofluorometry was performed. Touch smears of 31 human corneal endothelium taken from 21 autopsies and 10 donor eyes were fixed with absolute methanol and subsequently stained by the pararosaniline-Feulgen nuclear reaction. The optimum condition for Feulgen hydrolysis of the specimens was determined, and all smears were hydrolysed in 1 N HCl for 5 min at 60 degrees C. After the Feulgen reaction, the pararosaniline-DNA fluorescence was measured with an epi-illumination cytofluorometer (Olympus AH-QRFL). Polyploid nuclei, which are the result of abortive cell division after DNA synthesis, appeared with DNA contents of tetraploid (19 cases) and octaploid (two cases) classes. All other nuclei had DNA quantities within the range of the diploid class. Nuclei containing DNA between diploid and tetraploid amounts were not found. It was concluded that most human corneal endothelial cells are of post mitotic Gl population but that a few are in the generative G0 phase.

Adult↗
PubMed1984

Enzymhistochemical identification of microglial cells in the rat retina: light and electron microscopic studies.

We used the method of thiamine pyrophosphatase (TPPase) enzyme histochemistry and flat-mounted and transverse-sectioned retinas to identify microglial cells. Light microscopically, TPPase activity was demonstrated on the outer surfaces of glial cells located in the inner plexiform layer (IPL) and the ganglion cell layer (GCL) of the entire retinal regions, and also on the outer surfaces of blood vessels. Electron microscopically, TPPase activity was observed on the plasma membranes of the glial cells, the endothelial cells of microvessels and the pericytes. The TPPase-positive glial cells had a dark nucleus with large clumps of chromatin beneath the nuclear envelope. These findings strongly suggest that the glial cells with TPPase activity observed in the IPL and the GCL of the rat retina were microglial cells.

Animals↗
PubMed1984

Corneal endothelial changes caused by ophthalmic drugs.

Morphological changes were examined in the corneal endothelium of rabbits after administration of several drugs widely used in ophthalmology. After administration of epinephrine and dipivalyl epinephrine eye drops, swelling of corneal endothelial cells developed; however, these changes were reversible. No pathological changes were observed in the corneal endothelial layer following the administration of timolol, betamethasone, and gentamicin eye drops. Morphological changes were observed in the corneal endothelial layer after the subconjunctival injection of timolol, betamethasone, and gentamicin.

Animals↗
PubMed1984

Clinical application of temporal modulation transfer function.

The temporal modulation transfer function (temporal MTF) was measured in normal controls and in patients with retinal diseases, optic neuritis and amblyopia. The temporal MTF of controls showed "band-pass" filter properties, having a peak sensitivity at about 15 Hz at 1,000 trolands of mean retinal illuminance. As the retinal illuminance was reduced, the sensitivity decreased, first at high temporal frequencies, then the peak sensitivity decreased. Finally at low temporal frequencies the sensitivity decreased and the peak shifted toward the lower frequency. In retinal diseases, abnormal temporal MTF was detected, and the curves were very similar to those of normal controls when retinal illuminance was reduced. These patterns were not specific to any retinal diseases, and the severity of the condition seemed to determine the pattern. In optic neuritis, an attenuated sensitivity was detected in all frequency ranges; however, the degree of attenuation was more severe than that found in retinal diseases even when the visual acuity was similar. At the convalescent stage, the low frequency sensitivity was restored first, and high frequency loss was observed even when the visual acuity was recovered to 1.0. Two amblyopic patients showed an attenuated sensitivity in the high and intermediate frequency ranges, and in one case sensitivity was attenuated in all frequencies. Three other patients showed normal sensitivity. By occlusion of the nonamblyopic eye, recovery of the sensitivity was observed in one patient whose visual acuity improved.

Adolescent↗
PubMed1983

Hypothalamo-retinal centrifugal projection in the dog.

Horseradish peroxidase (HRP)-filled neurons and their processes were consistently detected in the ventral portion of the dog hypothalamus after intraocular injection of HRP. The number of HRP-filled neurons decreased in parallel with the extent of the resection of the optic nerve. HRP-filled neurons were never detected in specimens with a complete resection of the optic nerve. These findings strongly indicate that these HRP-filled neurons in the ventral hypothalamus are the source of centrifugal fibers to the retina.

Animals↗
PubMed1983

VIP (vasoactive intestinal polypeptide)-like immunoreactive amacrine cells in the retina of the rat.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity was demonstrated in the rat retina, using the peroxidase anti-peroxidase (PAP) method. VIP-like immunoreactivity was observed in the cytoplasm of amacrine cells of the inner nuclear layer (INL) and their varicose processes ramifying in the inner plexiform layer (IPL). VIP-like immunoreactive amacrine cells were present in both central and peripheral retinal regions. In some sections fine ramifications of varicose processes in the IPL could be clearly traced. VIP-like immunoreactivity was detected in both 'stratified' and 'diffuse' amacrine cells. VIP-like immunoreactive amacrine cells were classified into four types.

Animals↗
PubMed1983

Spatio-temporal modulation transfer function in retinal diseases.

Spatio-temporal modulation transfer function was measured in patients with retinal disease (central serous choroidopathy, retinal branch vein occlusion, retinitis pigmentosa) using microcomputer controlled monitor-TV display system. Sensitivity loss in high spatial frequency ranges at 1.0 Hz temporal frequency was the characteristic finding in those diseases, and the results suggest that the sustained channel of the visual perception system is more impaired than the transient channel in retinal diseases involving the macula.

Adult↗
PubMed1983

Temporal contrast sensitivity in optic neuritis and amblyopia.

Temporal contrast sensitivity was measured in patients with optic neuritis and anisometropic amblyopia. In optic neuritis, attenuated sensitivity was detected at all frequency ranges; however, its degree was more severe than that of retinal diseases even when visual acuity was the same. At the convalescent stage, the low-frequency sensitivity was restored first, and high-frequency loss was observed even when the visual acuity was restored to 1.0. Two amblyopic patients showed attenuated sensitivity at high- and intermediate-frequency ranges, and in one case all frequency sensitivity attenuated. Three other patients showed normal sensitivity. By occlusion of the nonamblyopic eye, recovery of sensitivity was observed in one patient, whose visual acuity improved.

Adolescent↗
PubMed1982

Postnatal development of vasoactive intestinal polypeptide immunoreactive amacrine cells in the rat retina.

The ontogenic development of vasoactive intestinal polypeptide (VIP)-immunoreactive amacrine cells in the rat retina was studied using peroxidase-antiperoxidase (PAP) immunohistochemistry. In the rat retina, VIP immunoreactivity appeared entirely in postnatal stage. On the 12th postnatal day, VIP-immunoreactive amacrine cells could be first detected. However, VIP immunoreactivity was very weak and VIP-immunoreactive amacrine cell processes could not be observed at this stage. On the 21st postnatal day, VIP-immunoreactive amacrine cell bodies became more mature and their processes were distinctly observed, resembling their appearance in adult rat retinas. VIP immunoreactivity could be detected in both stratified and diffuse amacrine cells at this stage. The relationship between the first appearance of VIP-immunoreactive amacrine cells and the synaptic formation in the inner plexiform layer is briefly discussed.

Animals↗
PubMed1982

Contrast sensitivity measurement in retinal diseases by laser generated sinusoidal grating.

The contrast sensitivity function (CSF) of 83 patients with retinal diseases was measured by laser-generated sinusoidal grating pattern, which enables the direct measurement of the CSF between the retina and the brain. The CSF abnormality in various retinal diseases was not specific to each disease, and the severity may determine the pattern. The abnormal patterns and rough correlation with visual acuity (V.A.) are: (1) attenuation at high frequency ranges (V.A. greater than 0.8), (2) attenuation at intermediate and high frequency ranges (0.4 less than V.A. less than 0.7), (3) attenuation at all frequency ranges (V.A. less than 0.3). Some cases, however, showed discrepancy between visual acuity and CSF. At the recovery stage of central serous retinopathy and retinal branch vein occlusion, CSF showed delayed recovery or attenuated sensitivity even when visual acuity was restored to 1.0 or more. In retinitis pigmentosa and pre-retinal macular fibrosis, CSF showed more sensitive detection of abnormal macular function than visual acuity measurement. At the post-corticosteroid therapy of Harada's disease and Sympathetic Ophthalmia, CSF recovered more rapidly than visual acuity when retinal detachment was absorbed. Those discrepancies suggest that CSF measurement may be useful for evaluating progression or regression of these diseases.

Adolescent↗
PubMed1982

Temporal modulation transfer function in patients with retinal diseases.

The temporal modulation transfer function (temporal MTF) was measured in normal controls and in patients with various retinal diseases. Temporal MTF of controls showed band-pass filter properties, having a peak sensitivity at about 10 Hz at 1,000 Troland of retinal luminance. As the retinal luminance was reduced, the sensitivity decreased first at high temporal frequencies; then the peak sensitivity decreased, and finally at low temporal frequencies the sensitivity decreased and the peak shifted to the left. In retinal diseases, abnormal temporal MTFs were detected, and the curves were very similar to those of normal controls when retinal luminance was reduced. These patterns were not specific to any retinal diseases, and the severity of the conditions seemed to determine the pattern.

Adult↗
PubMed1982

Temporal contrast sensitivity in central serous choroidopathy.

Temporal contrast sensitivity (TCS), a function of foveal sensitivity to sinusoidally modulated stimuli, was measured in 35 patients with central serous choroidopathy. Attenuation of the sensitivity at high temporal frequency was observed even when visual acuity was not impaired. In patients whose visual acuity was impaired, attenuation of the sensitivity of middle and/or low frequency as well as at high frequency was observed. In many cases TCS recovered to various degrees as the condition improved, even when little recovery of visual acuity was observed.

Adult↗