摘要:

Taurine is an amino acid that is essential for retinal integrity and function. Although it has been suggested that the ratio of melatonin to taurine in the interphotoreceptor matrix may regulate the phagocytosis of outer segments by retinal pigment epithelial (RPE) cells, the effect of taurine on the RPE has not been studied. Using cultured RPE cells, we found that in vitro taurine specifically stimulated proliferation of human and rabbit RPE, but had only minimal effect on cultured scleral fibroblasts. The RPE proliferation was due to more cells entering into S-phase and thus an increase in DNA synthesis, was not dependent upon cell density, and was most pronounced in the presence of a low concentration of fetal bovine serum.

ISSN:0271-3683    

DOI:10.3109/02713689209001804

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Previously we have detected the occurrence of retinal lipid peroxidation initiated by phagocyte-derived oxygen radicals in experimental autoimmune uveitis (EAU). In the current studies, the confirmation of inflammation-mediated lipid peroxidation was proceeded further to include measurement of multiple parameters, including conjugated dienes, ketodienes, thiobarbituric acid reactive substances and fluorescent chromolipids. The assay for myeloperoxidase, a measure for the number of polymorphonuclear leukocytes in the inflammatory sites was also carried out. The levels of all these parameters were followed through the course of EAU development. The sequential evaluation of histologic changes using both light and electron microscopy was also carried out and the results were correlated with lipid peroxidation indices. These data suggest that the retinal lipid peroxidation plays a causative role in the subsequent retinal degeneration.

ISSN:0271-3683    

DOI:10.3109/02713689209001805

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

As photoreceptor degeneration progresses in Royal College of Surgeons (RCS) rats, a variety of morphological and physiological alterations occur in the outer retina. Since the choriocapillaris responds to changes in the outer retina in other retinopathies, we examined the possibility that changes in the choroidal vasculature also occur in RCS rats. The choroidal and choriocapillary vessels in RCS and control (RCSrdy+) rats were examined during the period after which photoreceptor loss and retinal vascular changes had occurred (7-mos to 28-mos). Light microscopic (LM) morphometry and electron microscopic (EM) examination showed no significant differences between these groups in the number, size or morphology of these vessels. However, EM image analysis revealed that nerve fibers and bundles were twice as abundant in the RCS choroid than in the control. Using immunohistochemical techniques at the LM level combined with image analysis we found that vasoactive intestinal polypeptide positive (VIP+) fibers were significantly increased in the RCS choroid compared with control choroid. In contrast, the abundance of immunoreactive fibers labelled for substance P and dopamineβhydroxylase appeared similar in both the control and RCS choroid. Since VIP is a potent vasodilator, the increased abundance of nerve fibers in the RCS choroid in conjunction with the unaltered number and size of these vessels suggests that choroidal blood flow may be increased. It is uncertain whether this increase is a response to the outer retinal pathology or contributes to it.

ISSN:0271-3683    

DOI:10.3109/02713689209001806

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

We examined the morphology of the corneal surface epithelial cells in 13 eyes of 13 subjects using specular microscopy. We determined cell area, perimeter, and shape comparing the central cornea with the inferior and superior periphery. We found surface epithelial cells are significantly smaller in the central cornea. The cells measured 560±93 square microns in the central cornea, 850±135 square microns in the superior cornea and 777±176 square microns in the inferior cornea (p<. 005). Newly emerged surface cells are smaller and are thought to enlarge with time. We postulate that lid shearing forces are greater in the central cornea and contribute to epithelial cell exfoliation. We further postulate that preferential shearing of central corneal surface cells is an important factor driving the centripetal movement of corneal epithelial cells.

ISSN:0271-3683    

DOI:10.3109/02713689209001807

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

A“Soft”corticosteroid, loteprednol etabonate I, designed based on the“inactive metabolite”concept can be used as a safe ophthalmic anti-inflammatory drug. By design, the metabolism of I follows a predicted biotransformation pathway, thus unwanted systemic side effects are avoided. Local side effects are also reduced. Accordingly, in a cross-over study I did not elevate the intraocular pressure (IOP) in rabbits, as opposed to dexamethasone.

ISSN:0271-3683    

DOI:10.3109/02713689209001808

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

This investigation was a follow-up to an earlier biochemical and light microscopic histochemical study, in which the lysosomal protease dipeptidyl peptidase II (DPP II) was demonstrated in rodent lenses. In the present study, a method was employed that allowed a more precise histochemical localization of the enzyme, one that was suitable for ultrastructural as well as light microscopic analysis. Successful demonstration of the enzyme using either of two synthetic substrates, and the significant reduction of the enzyme reaction by phenylmethylsulphonyl fluoride (PMSF), a serine protease inhibitor, pointed to the sensitivity of the method. A flat-embedding technique allowed the correlative light and electron microscopic analysis of specific areas of the specimen.Examination of the epithelium and outer cortical regions of the lens revealed the compartmentalization of DPP II activity within lysosomal dense bodies that were concentrated primarily in the equatorial and sutural regions, and also an association of the reaction product with larger bodies that were confined to the sutural regions. The latter structures appeared to represent fiber cell fragments that were enwrapped with narrow extensions of the surrounding fiber cells. The location of enzyme activity within the sutural bodies and also within the intercellular spaces of the modified fiber cell extensions surrounding these bodies suggested that lysosomal proteases may play a role in the segregation and degradation of specific regions of normal lens fiber cells.

ISSN:0271-3683    

DOI:10.3109/02713689209001809

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

The in vivo hemodynamics of the ciliary process vasculature In the albino rabbit were studied with an Improved technique of Intraocular microendos-copy. The spreading pattern and velocity of the dye front has been observed in defined vessel segments following intracarotid Injection of Evans Blue.In the anterior portion of the ciliary processes a“thoroughfare channel”(bypass) was found leading from the arteriolar tree directly Into the marginal venule bypassing the capillary network of the ciliary processes. This bypass is characterized by a higher blood flow velocity (1.5–3mm/sec) than was found for the capillary network (0.8–1 mm/sec). A stoppage of blood flow was observed in the capillary network at 45–50mmHg after step-wise elevation of intraocular pressure (IOP): blood flow was not stopped in the thoroughfare channel until IOP values of 55–60mmHg were reached. Intraarterial administration of vasoconstrictive agents could lead to a complete stoppage of blood flow in the capillary net whereas the marginal route often remained patent.

ISSN:0271-3683    

DOI:10.3109/02713689209001810

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

This study was performed to determine the effects of phorbol esters and ionomycin on phospholipase D (PLD) activity in bovine corneal epithelial cells (BCEC). The cells were prelabeled with [3H]myristic acid and incubated for specific time intervals with various test agents in the presence and absence of ethanol. The PLD activity was assayed by monitoring the formation of labeled phosphatidylethanol ([3H]PEt) in [3H]myristate labeled cells. In the absence of ethanol, 1μM phorbol 12-myristate 13-acetate (PMA) increased the formation of labeled phosphatidic acid ([3H]PA) with no significant effect on the radioactivity of [3H]PEt. In the presence of 85 mM ethanol, whereas there was only a small further increase in [3H]PA, the formation of [3H]PEt was increased by several-fold, demonstrating activation of PLD by the phorbol ester. The effects of PMA were time- and dose-dependent, and were mimicked by phorbol 12,13-dibutyrate. The inactive phorbol derivatives, 4-α-phorbol, 4-α-phorbol 12,13-didecanoate, 4-α-phorbol 12-myristate 13-acetate and 4-α-phorbol 12,13-dibutyrate, were without effect. Short-time (30 min) incubation of BCEC with staurosporine or H-7, or prolonged (20 hours) incubation with PMA rendered the cells less sensitive to subsequent treatment with PMA, suggesting that activation of PLD in the cells is mediated by protein kinase C (PKC). Addition of 20μM ionomycin in the presence of ethanol also increased the formation of [3H]PA and [3H]PEt in a time- and dose-dependent manner. Co-presence of ionomycin and PMA at submaximal concentrations in the incubation medium resulted in increased formation of [3H]PA and [3H]PEt which was less than their individual effects combined, indicating a lack of synergism between Ca2+ and PMA in activating PLD. Incubation of BCEC with staurosporine resulted in significant inhibition of ionomycin-induced production of [3H]PEt, suggesting that in addition to direct activation of PLD by Ca2+, the enzyme is probably stimulated by sequential activation of PLC (producing diacylglycerol) and PKC following the ionomycin addition. We conclude that BCEC possess PLD which is stimulated by PKC as well as elevated intracellular Ca2+.

ISSN:0271-3683    

DOI:10.3109/02713689209001811

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

5-Fluorouracil (5-FU) and Mitomycin C (MMC) are used as adjunct chemotherapy during glaucoma filtering surgery to suppress conjunctival fibroblast proliferation. Since part of these agents may gain access to the anterior chamber and cause cytotoxicity to the corneal endothelium we set up an in vitro system to establish a dose-response effect. Cytotoxicity of MMC and 5-FU was quantified using Mosmann's colorimetric assay in a bovine endothelial cell culture system. In this assay the respiratory activity of the cells is used as a marker for cell viability.After incubation for 5 minutes the 3.0 mg/ml concentration of MMC showed endothelial cytotoxicity, whereas no endothelial toxicity of 5-FU was noted in concentrations up to 50 mg/ml. After incubation for 30 minutes endothelial cytotoxicity was demonstrated for 50 mg/ml of 5-FU and 1 mg/ml of MMC. After an exposure-time of 60 minutes the toxicity level remained 50 mg/ml for 5-FU but decreased to 0.5 mg/ml for MMC.We conclude that with respect to the clinically used concentrations and methods of application of 5-FU and MMC in vivo endothelial toxicity is not to be expected. However, in cases of accidental access of MMC to the anterior eye chamber and following a reduction of aqueous turnover rate the safety of MMC is unwarranted.

ISSN:0271-3683    

DOI:10.3109/02713689209001812

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

The effects of cyclooxygenase inhibitors flurbiprofen and indomethacin on the inflammatory response and immune reactions induced by S-antigen in the rat eye were studied. The treatment with flurbiprofen and indomethacin administered subcutaneously every 12 hours, commenced on the day of S-antigen injection and was continued until the termination of the experiment (12 days). Flurbiprofen reduced vasodilation and the inflammatory exudate into the anterior chamber by 38% and 36% respectively while inhibiting polymorphonuclear leukocytes infiltration by 57% without affecting monocytes infiltration. Indomethacin had similar but greater effects than flurbiprofen on all these parameters. However, the differences between the mean values of the two compounds were not significant. Both compounds also attenuated spleen cell proliferation, serum IgG levels to S-antigen and interferon-gamma levels in the aqueous humor. The level of prostaglandin E2, but not of leukotriene B4, was increased in the untreated inflamed uveal tissues and this increase was significantly inhibited by flurbiprofen and indomethacin. The results of this study suggest that cyclooxygenase products are involved in the normal development of both humoral and cellular immune response in the experimental uveitis.

ISSN:0271-3683    

DOI:10.3109/02713689209001813

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor