Masakatsu Fukuda

Concentration dependent effects of hydrogen peroxide on lens epithelial cells

AIMS To evaluate the effects of hydrogen peroxide exposure on the survival and proliferation of cultured lens epithelial cells. METHODS TOTL-86 cells, a line of rabbit lens epithelial cells, were used. The survival and proliferation of TOTL-86 cells were quantified by a rapid colorimetric assay (MTT assay). To determine the effects of hydrogen peroxide, TOTL-86 cells were exposed to different concentrations of hydrogen peroxide. To determine the effect of cell numbers on the survival and proliferation of TOTL-86 cells at a fixed concentration of hydrogen peroxide, different numbers of cells were plated and exposed to hydrogen peroxide. To determine whether there is a synergistic effect between hydrogen peroxide and EGF, bFGF, PDGF-AA, and insulin, TOTL-86 cells were exposed to hydrogen peroxide combined with one of these growth factors. RESULTS High levels (1 mM) of hydrogen peroxide killed TOTL-86 cells and sublethal levels (100 μM) suppressed their proliferation. From 1 nM to 1 μM of hydrogen peroxide, there was a dose dependent increase in the cell numbers. The initial seeded cell number dramatically affected the response to hydrogen peroxide. Although growth factors showed no synergistic effects with hydrogen peroxide on proliferation, both EGF and insulin, but not bFGF or PDGF, rescued TOTL-86 cells from the sublethal effect. CONCLUSION Hydrogen peroxide in cooperation with some growth factors plays an important role in the proliferation of lens epithelial cell.

Aldose reductase inhibitor (CT-112) eyedrops for diabetic corneal epitheliopathy.

We treated two diabetic patients with corneal epithelial disorder that resisted conventional medical therapy with topical CT-112 (5-[3-ethoxy-4-pentyloxyphenyl]-2,4-thiazolidinedione), a newly synthesized aldose reductase inhibitor. One patient had developed recurrent corneal erosion after vitrectomy and the other had spontaneously developed superficial punctate keratopathy. The corneal lesion in each patient responded to topical CT-112 in two to four weeks and was almost cleared within two months. A similar corneal lesion recurred in both patients soon after CT-112 was discontinued, but it disappeared again when the drug was resumed.

Localization of vasoactive intestinal polypeptide and neurotensin immunoreactivities in the avian retina

The distribution of vasoactive intestinal polypeptide (VIP)- and neurotensin (NT)-like immunoreactivities in the chicken retina was investigated by immunohistochemistry. VIP- and NT-positive cells were found throughout the chicken retina. The majority of them were located in the proximal portion of the inner nuclear layer and the processes from these cells directed to the inner plexiform layer where they ramified, suggesting that VIP- and NT-positive cells located in this region probably are amacrine cells.

Demonstration of a substance P-like immunoreactivity in retinal cells of the rat.

The distribution of substance P (SP)-like immunoreactivity in the rat retina was investigated by immunohistochemistry. SP-positive cells were found throughout the retina. The majority of them were located in the proximal portion of the inner nuclear layer and the processes from these cells directed to the inner plexiform layer where they ramified, suggesting that SP-positive cells located in this region probably are amacrine cells. Few SP-positive cells were seen within the ganglion cell layer. They were considered displaced amacrine cells.

Two types of substance P-containing cells and their uneven distribution in the chicken retina: an immunohistochemical analysis with flat-mounts

Substance P-like immunoreactivity (SPI) was investigated in the chicken retina by means of the indirect immunofluorescence method with flat-mounts. SPI cells were located mostly in the peripheral retinal regions, while in the central region, none or only a few cells were seen. Based upon their 3-dimensional profiles, SPI cells can be divided into two types: one type belongs to the stratified amacrine cells of the first sublayer and the other to those of the third to fifth sublayer.

Topical aldose reductase inhibitor for correcting corneal endothelial changes in diabetic patients.

BACKGROUND--Marked variations in cell size (polymegethism) and shape (pleomorphism) are characteristic of the corneal endothelium in diabetic patients and animals. METHOD--Wide field specular microscopy was used to evaluate the clinical efficacy of treating the diabetic corneal endothelium with topical instillation of 0.5% aldose reductase inhibitor, CT-112. RESULTS--Morphological variations (polymegethism and pleomorphism) of the endothelium in eight eyes from eight patients receiving CT-112 resolved within 3 months after initiation of treatment. In contrast, no change in endothelial morphology was noted in five eyes from five patients who received placebo. CONCLUSION--These observations suggest that aldose reductase may be involved in the aetiology of corneal endothelial variations in diabetic patients.

The effects of aldose reductase inhibitor on the corneal endothelial morphology in diabetic rats

Diabetic rats were produced by intravenous injection of streptozotocin. Of these, eleven rats were treated with topical instillation of 0.5% aldose reductase inhibitor (ARI), while ten received vehicle alone. The corneal endothelium of these diabetic rats was examined by specular microscopy and compared to age-matched nondiabetic rats (ten rats). Computerized morphometric analysis of individual cells demonstrated that the endothelium of the untreated diabetic rats had marked polymegathism (increased coefficient of variation in cell area) and pleomorphism (decreased percentage of hexagonal cells), as previously observed in diabetic patients. Similar endothelial changes were also noted in the ARI-treated diabetic rats, but to a significantly lesser extent. These results suggest that topically applied ARI can be effective in reducing morphologic changes of the diabetic endothelium, and that activation of the sorbitol pathway may be implicated in the etiology of such endothelial changes.

Monoamine accumulating neuron system in the rat retina with special reference to noradrenaline accumulating neurons

Abstract The uptake capacity of the retinal neurons for exogenously administered monoamines was examined in the rat. The present study confirmed the presence of 5,6-dihydroxytryptamine (5,6DHT) accumulating retinal neurons in the rat retina and further disclosed that some retinal cells could accumulate exogenously injected noradrenaline (NA). These NA-labeled cells occupied approximately similar positions in the inner nuclear layer to the 5,6DHT-labeled ones, but the two groups of cells were not identical because simultaneous injections of 5,6DHT and NA demonstrated two types of cells, one having yellow and the other showing green fluorescence, respectively. It should be stressed that these two groups of cells are easily distinguishable from well-known dopamine-containing neurons by their sizes and cell locations. The present study further suggested that the NA-accumulating retinal cells might not contain the NA synthesizing enzyme.

Corneal endothelial changes in patients with chronic renal failure

PURPOSE To evaluate the morphologic changes of the corneal endothelium in patients with chronic renal failure. METHODS Twenty corneas of 20 patients with chronic renal failure undergoing hemodialysis were examined by wide-field specular microscopy. Twenty normal corneas from 20 healthy age-matched subjects were enrolled as control corneas. RESULTS Despite normal endothelial cell density, the corneal endothelium of patients with chronic renal failure showed marked polymegethism and pleomorphism. CONCLUSION Polymegethism and pleomorphism of the corneal endothelium are found in patients with chronic renal failure.

Histamine H1-receptor in the retina: Species differences

Histamine H1-receptors in membranes of the various mammalian retinas were studied by [3H]mepyramine binding assay. Specific [3H]mepyramine bindings to bovine, pig, dog and human retinas were observed with the dissociation constants (KD), 3.8 +/- 1.2 nM, 1.8 +/- 0.6 nM, 2.6 +/- 0.6 nM and 3.0 +/- 0.9 nM, respectively, which were similar to those found in brains. But there was no detectable specific binding in the guinea-pig and rabbit retinas. The number of binding sites (Bmax) ranged from negligible value to 290.7 +/- 51.7 fmole/mg protein(human retina). Some H1-antagonists acted as potent agents in competing with [3H]mepyramine binding to bovine and pig retinas. These results indicated that histamine H1-receptors exist in some mammalian retina and have similar characteristics to those in brain membranes, but they distributes in the wide difference of the binding capacities among the species, while in brain variations were smaller.