Distribution of epidermal growth factor receptors in rabbit lens epithelial cells.

PURPOSE: This study examined the growth-promoting effect of epidermal growth factor (EGF) on rabbit lens epithelial cells and the distribution of EGF receptors in these cells. METHODS: Rabbit lens epithelial cells were cultured in TC-199 medium containing 0.5% fetal bovine serum and EGF for 1 to 5 days, and the growth-promoting effects of EGF were calculated with absorbance of methylene blue staining method. EGF receptors in the cells were analyzed by Scatchard plots using 125I-EGF in serum-free culture. RESULTS: EGF, which enhanced the cell growth in a dose-dependent manner, was stimulatory at 0.1-100 ng/ml and maximal (328.2%) with 10 ng/ml on day 5. The cells had two different affinity receptors. The number and the dissociation constant of the low affinity receptors were 5.81 x 10(4)/cell and 1.488 nM, respectively, and those of the high affinity receptors were 1.53 x 10(4)/cell and 0.159 nM, respectively. CONCLUSION: EGF may contribute to the development of living lenses.

Teratogenicities of ophthalmic drugs. II. Teratogenicities and tissue accumulation of thimerosal.

Under the conditions of this study, systemically or topically applied thimerosal was found to have no teratogenic effect even when given in concentrations approaching the 50% lethal dose of these compounds. A comparison of topical and subcutaneous administration of thimerosal to rabbits shows that a substantial concentration of mercury was present in blood and tissues of the treated animals and their offspring. Thimerosal was found to cross the blood-brain and placenta barriers.

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.

Teratogenicities of ophthalmic drugs. I. Antiviral ophthalmic drugs.

Nonradioactive idoxuridine (IDU,5-iodo-2'-deoxyuridine), while not teratogenic to rats, does produce fetal maliformations in rabbits when administered topically to the eye in doses similar to those used clinically, 0.1% four times a day for 12 days. These maliformations include exophthalmos and clubbing of the forelegs. By contrast, trifluorothymidine (F3TdR), another highly effective antiherpetic agent currently under investigation but not available for general use, was found not to be teratogenic to rabbits, even when given in concentrations tenfold greater than the doses used to produce idoxuridine teratogenicity.

Neuronal responsiveness in area 21a of the cat.

Photic responsiveness was studied in cells of area 21a which was identified as a region containing few cells projecting to area 17, and was bounded to two other visual areas (posteromedial lateral suprasylvian area and area 19) providing abundant efferent projection to area 17. Area 21a cells were characterized by strong orientation, but demonstrated poor direction and end-stop selectivity, in contrast to strong direction or end-stop selectivity of cells in another two visual areas.

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.

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.

Clinical effect of blowing nitrogen gas across the cornea during photorefractive keratectomy.

OBJECTIVE: We evaluated the clinical effects of blowing nitrogen gas over the cornea during photorefractive keratectomy. METHODS: We retrospectively compared clinical outcomes of 32 patients (37 eyes), divided into two groups who had photorefractive keratectomy with nitrogen gas blowing across the cornea (n = 19) and without nitrogen gas (n = 18). All photorefractive keratectomies were performed between April 1991 and August 1992. Ablation zone diameters were 5.0 or 5.5 mm. The average attempted correction was -3.47 +/- 1.76 diopters (D) in the nitrogen gas group, and -3.48 +/- 1.25 D in the non-nitrogen gas group. RESULTS: The nitrogen gas group achieved more accurate corrections than the non-nitrogen gas group, but had a significantly greater amount of corneal haze at all postoperative examinations. Corneal haze was most evident at 1 month and gradually diminished therafter in both groups. At 6 months, videokeratography revealed a central island in 2 eyes (11.1%) of the non-nitrogen gas group. Because of undercorrection (2 eyes) or central island (1 eye), 3 out of 18 eyes in the non-nitrogen gas group were reablated 6 months later. CONCLUSIONS: The non-nitrogen gas group had more undercorrections and a higher frequency rate of central steep islands, but nitrogen gas blowing caused a greater amount of corneal haze.

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.

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.

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.

Corneal incisions utilizing the 1,053-nm picosecond Nd:YLF ophthalmic laser.

We evaluated the precision and predictability of a 1,053-nm picosecond Nd:YLF ophthalmic laser with various combinations of computer-controlled parameters. We utilized epithelium-free corneal-sclera preparations from NZW rabbits, and the 1,053-nm Nd:YLF laser (Intelligent Surgical Lasers, San Diego, CA, U.S.A.). X-line and line patterns were utilized to make linear corneal incisions. Three parameters (layer size, crossing width, and energy level) were evaluated. One parameter was changed for a total of 120 combinations of computer-controlled parameters. Three incisions were performed for each combination. Although the intended depths of the incisions were constant (300 mu m), the actual depths of the incisions varied with the change of parameters. Increasing layer size decreased the depth of incisions, and increasing crossing width or energy level increased the depth of incisions. Only three of 120 combinations of parameters achieved depths near 300 mu m. Within the same combination of parameters, the depth of the corneal incisions varied. Debris of ablated stromal tissue was observed at the border and partially occupying the incision. Most of the incisions were "funnel"-shaped with the distal treatment zone having a "zigzag" or irregular border. Further improvements are necessary to use this laser system for corneal transverse incisions.

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.

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.

Glutathione isopropyl ester (YM737) inhibits the progression of X-ray-induced cataract in rats.

The effect of glutathione (GSH) isopropyl ester on the progression of X-ray-induced cataract was investigated in rats. Intraperitoneal administration of 20 mg/kg GSH isopropyl ester, three times weekly, 1 day after a single irradiation dose delayed the progression of X-ray-induced cataracts significantly. The amount of non-protein SH groups and the Na+/K+ ratio in the lenses of drug-treated rats were maintained at the normal levels even 27 weeks after irradiation. Posttreatment with the drug resulted in a significantly lower level of malondialdehyde in the irradiated lenses than in the nontreated lenses. When 500 mg/kg GSH-isopropyl ester was administered by i.p. injection to normal rats, the GSH-ester was detected in plasma and aqueous humor after 15 min. In the lenses of the GSH-isopropyl ester-injected rats, the GSH level was 120% of that in the non-treated rats after 4 h, suggesting that GSH-isopropyl ester is transported from the aqueous humor to the lens and there converted to GSH after about 4 h. Our observations lead us to conclude that the delay of X-ray-induced lens opacity progression is due to maintenance of normal lenticular GSH levels achieved by post-irradiation administration of GSH-isopropyl ester. However, continuous administration of 100 mg/kg after irradiation had no effect on the progression of cataracts induced by X-rays.

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.

Case-control study of senile cataract in Japan: a preliminary report.

A hospital-based case-control study of senile cataract was conducted in Japan from 1988 to 1990. Two hundred and twelve patients with senile cataract and 212 control subjects with the same age-sex distribution were interviewed and given an ophthalmological examination. Both groups were randomly selected outpatients from 9 hospitals. Associations between senile cataract and four groups of variables, factors regarded as risks, life style habits, general aging indices or other factors were analyzed, and the data was subjected to statistical analysis. An increased risk of cataract was found in males who were presently spending 7 hours or more outside daily (Odds ratio = 5.07) and in females with 4 or fewer remaining teeth (Odds ratio = 2.03). The findings from this study suggest that there may be a sex-related host sensitivity or life style which is predisposing to the development of senile cataract.

[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.