PubMed Health⌕ Search

Biomedical subjects

M Itoi

Publications and source records attributed to M Itoi.

At least 19 recordsLinked to original sources
PubMed1992

Distribution of epidermal growth factor (EGF) receptors in rabbit corneal epithelial cells, keratocytes and endothelial cells, and the changes induced by transforming growth factor-beta 1.

Three kinds of rabbit corneal cells (epithelial cells, keratocytes and endothelial cells) were cultured, and the growth promoting effects of epidermal growth factor (EGF) were examined in these cells. It was found that the sensitivity of the epithelial cells to EGF was the highest, that of the endothelial cells was a little lower, and that of the keratocytes was the lowest. Transforming growth factor-beta 1 (TGF-beta 1) did not influence growth of the three kinds of corneal cells. It was found that TGF-beta 1 enhanced the growth promoting effect of EGF in the keratocytes, but not in the epithelial and endothelial cells. EGF receptors in the corneal cells were labelled with [125I]EGF and analysed by Scatchard plot. In the epithelial and endothelial cells, both high and low affinity receptors were found, while the keratocytes had only low affinity receptor. In the epithelial cells, the number and the association constant of the high affinity receptors were, respectively, 2.79 x 10(4) per cell and 0.034 nM, and those of the low affinity receptors were, respectively, 13.4 x 10(4) per cell and 0.700 nM. In the endothelial cells, the number and the association constant of the high affinity receptors were 1.27 x 10(4) per cell and 0.086 nM, respectively, and those of the low affinity receptors were 8.91 x 10(4) per cell and 1.536 nM. In the keratocytes, the number of receptors and the association constant were 9.49 x 10(4) per cell and 1.535 nM, respectively. The corneal cells were treated with TGF-beta 1 for 24 hr and its influence on EGF receptors was examined. The results showed that TGF-beta 1 induced the high affinity receptors in the keratocytes, although TGF-beta 1 did not influence EGF receptors in the epithelial and endothelial cells. The number of high affinity receptors in keratocytes treated with TGF-beta 1 was 1.02 x 10(4) per cell and the association constant was 0.171 nM (this was approximately tenfold higher than that of the receptor of keratocytes not treated with TGF-beta 1).

Animals↗
PubMed1992

Changes of glutathione and taurine concentrations in lenses of rat eyes induced by galactose-cataract formation or ageing.

Sulphur-containing compounds in the lens were studied in relation to galactose cataract formation. Female Wistar rats were fed a 35% galactose diet and the changes in lens sulphur concentration and its distribution on a gel filtration column were compared with age-related changes. Concentration of sulphur in the whole lens decreased with time. A low constant level was attained on the fifth day of the galactose diet. A decrease of sulphur concentration in the soluble fraction of the lens paralleled that of the whole lens which was correlated with the decrease of glutathione and taurine concentrations on a gel filtration column by high-performance liquid chromatography-inductively coupled argon plasma atomic emission spectrometry (HPLC-ICP). Concentration of magnesium in the lens decreased after the fifth day, while the ratio of sodium to potassium increased. These changes in sulphur-containing compounds and metals were observed prior to the onset of cataract formation.

Aging↗
PubMed1992

Effects of 2-mercaptopropionylglycine on the development of X-ray-induced cataract in rats.

The effect of 2-mercaptopropionylglycine on the development of cataract induced by a single dose of X-ray (10 Gy) was investigated in rats. Intraperitoneal injection of 20 mg/kg, three times weekly starting 1 day after irradiation delayed the development of X-ray-induced cataracts significantly. The amounts of non-protein SH groups, malondialdehyde and the Na+/K+ ratio, in the lenses of rats post-treated with the drug were significantly maintained at normal levels even at 27 weeks after irradiation. On the other hand, a single administration of 250 mg/kg of the compound, 30 min prior to irradiation had no effect on cataract progression induced by X-ray.

Animals↗
PubMed1991

Ultrastructural observations of typical gap junctions in human foetal lens nucleus.

The ultrastructure of gap junctions throughout the human foetal lens was observed. By freeze-fracture analysis, we observed numerous gap junctions in both lens cortex and lens nucleus. Comparison between lens cortex and lens nucleus showed that the gap junctions of lens nucleus are characterized by extreme mosaics of closely apposed P- and E-faces in junctional areas, though no significant difference in the area of gap junctions was observed between lens cortex and lens nucleus. In addition, some morphological variations, such as the smooth domains without particles or pits in junctional areas and the reticulated figures of gap junctions, were observed only in the lens nucleus. We also observed by thin-section electron microscopy that cell membranes of human foetal lens nucleus, as observed in the lens cortex, are mainly composed of continuous lipid bilayer and junctional structures. We concluded that characteristic morphology of lens gap junctions, as observed in the cortex of human foetal lens, is mostly preserved in the human foetal lens nucleus, although some depth-dependent alterations were also observed.

Fetus↗
PubMed1990

Classification system for cataracts. Application by the Japanese Cooperative Cataract Epidemiology Study Group.

A cataract classification and grading system for the main purpose of cataract epidemiological studies is proposed by the Japanese Cooperative Cataract Epidemiology Study Group. Cataractous types are classified principally into cortical, nuclear and subcapsular opacities. Stages of cataract advancement are classified into grade I (early stage), grade II (moderate stage) and grade III (advanced stage). Regarding cortical opacities an opacified area obtained from red-reflex images is utilized for grading judgment. Nuclear opacity grading is based on the intensity of scattering at the nucleus. Grading of subcapsular opacities is judged from their extension in the three different pupillary areas. To help grading judgments, standard pictures of cortical and nuclear cataracts are provided. Gradings of lens coloration are divided into pale yellow (grade I), yellow (II), brownish yellow (III) and brown including reddish and black brown (IV). A recording chart is also provided.

Adult↗
PubMed1990

Spreading of cultured corneal epithelial cells on fibronectin and other extracellular matrices.

Previous investigations demonstrated that fibronectin is an essential adhesive glycoprotein for the corneal epithelial cells. Fibronectin mediates attachment and spreading of the corneal epithelial cells. However, it seems to be important to know the changes in cellular receptor activity in order to understand the interactions of corneal epithelial cells and underlying extracellular matrix. In this investigation, we studied the effects of various culture times and conditions on the receptor activity of rabbit corneal epithelial cells for fibronectin. The cultured cells were placed on tissue culture plates that were coated with various concentrations of four extracellular matrices: fibronectin, laminin and collagen types I and IV. Freshly isolated corneal epithelial cells without culture did not spread on fibronectin and laminin; they spread only on collagen types I and IV. When the epithelial cells were cultured for 12 h or more, they spread on fibronectin. However, the spreading of the cells on collagen types I and IV was the same regardless of the culture period (up to 20 h). Only a small number of epithelial cells spread on laminin at the highest concentration examined after culture for 12 h or more. Thus, the corneal epithelial cells responded differently to fibronectin, collagen types I and IV, and laminin. Perhaps the receptor for fibronectin appears when epithelial cells are cultured, but the receptor(s) for collagen types I and IV are always present on the cell surface of corneal epithelial cells.

Animals↗
PubMed1989

Changes in lens proteins induced at the early stage of cataractogenesis in cac (Nakano) mice.

Changes in lens proteins induced at the early stages of cataractogenesis in cac (Nakano) mice were investigated by two-dimensional gel electrophoresis (2D-PAGE). The 2D-PAGE profile of lens proteins in 21-day-old cac mice differed from that in 27-day-old normal mice, even though the appearance of 'pin-head' nuclear opacity (26-day-old) had not yet been observed in the lenses. Especially noticeable were great differences in the polypeptides associated with the alpha- and beta- crystallin subfractions, the appearances of which corresponded to an increase in a ratio of the amounts of Na+ to that of K+ in the lenses of defective mice. No dramatic decrease in the gamma-crystallin fraction was observed until the mature cataract stage.

Animals↗
PubMed1989

[A cataract classification and grading system].

A cataract classification and grading system developed for cataract epidemiological survey was introduced. Cataractous opacities were classified into cortical, nuclear and subcapsular types. Gradings of cataract progression were divided into early (Grade I), moderate (II) and advanced (III) stages. The grading of cortical opacity was judged by the opaque area in a maximally dilated pupillary zone of which findings were obtained from a red-reflex image. The grading of nuclear opacity was judged from the intensity of scattering light at the nucleus. Three grading steps were based on the densitometrical analysis of photographed images. Subcapsular opacities were classified into three gradings by extensions up to the normal, moderately dilated and maximally dilated pupil size. Regarding cortical and unclear cataracts, standard images indicating border findings between Grades I and II and Grades II and III were provided to help with classification. Nuclear coloration was classified into pale yellow, yellow, brownish yellow and brown including reddish brown and black brown. To document cataractous findings, a recording chart was made.

Cataract↗
PubMed1989

Specular microscopic studies of the corneal endothelia of Japanese diabetics.

We did a specular microscopic study with computer-assisted morphometric analysis of individual cells on the corneal endothelia of 69 Japanese diabetics and 53 age-matched nondiabetics. No statistically significant differences were seen in the mean cell areas of diabetics and nondiabetics. However, the coefficient of variation of cell area was significantly higher and the percentage of hexagonal cells was significantly lower in diabetics than in nondiabetics. Although racial differences of the corneal endothelia exist between Japanese and Americans, diabetic changes are quite similar in the two populations.

Adult↗
PubMed1979

Contrast (modulation) sensitivity functions measured in patients with high refractive error with emphasis on aphakia: I. Theoretical considerations.

Recently, alterations in contrast (modulation) sensitivity functions of patients with high refractive errors have been noted. For example, this seems to be a common finding in aphakia. In some measure the observed alterations are due to the effect of the corrective lens and the optics of the eyes. These optical effects (in addition to blur) must be factored out in order to determine whether residual effects on the visual system remain. The argument is applicable to photographs of sine wave fringes as well as devices designed to produce interference patterns directly on the retina. A simple means for largely correcting these lens effects is discussed.

Aphakia↗