摘要:

45Ca uptake was studied in isolated frog retinal pigment epithelial cells in response to the phagocytic stimuli, zymosan.45ca uptake was strongly stimulated immediately in the presence of zymosan particles. Calcium uptake was proportional to the zymosan concentrations. After 60 min in the presence of zymosan acid phosphatase andβ-glucuronidase activities showed a 25% and 50% increase, respectively. Rod outer segments induced a similar increase of these enzyme activities. The zymosan-induced lysosomal enzyme activities was inhibited by cytochalasinβand ruthenium red. The ionophore A23187 produced a remarkable increase in45ca uptake but did not affect the lysosomal enzyme activities. These results suggest that _in vitro RPE cells are able to respond to zymosan as phagocytosable stimuli and that calcium mediate that response.

ISSN:0271-3683    

DOI:10.3109/02713689209001770

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

In this investigation we localized and compared the level of gamma-glutamyl transpeptidase (GGTP) activity in retinal and brain preparations using histochemical, enzymatic and in situ hybridization assays. We compared GGTP distribution to another microvessel specific enzyme, alkaline phosphatase (AP). In the rat brain, GGTP activity was observed in microvessels and choroid plexus by a histochemical method. Similar studies in the rat retina revealed activity in the pigment epithelium but only a very weak reaction in microvessels. Histochemical staining for alkaline phosphatase was observed in both retinal and brain microvessels choroid plexus and pigment epithelium. Biochemical analysis verified that GGTP activity was significantly lower in retinal than brain microvessels, while alkaline phosphatase activity was similar in both types of microvessels. GGTP specific activity of bovine brain and retinal microvessels was 185+39 mUnits and 8.5+1.5 mUnits (p<0.001), respectively. By contrast, alkaline phosphatase specific activity in brain and retinal microvessels was 732+139 and 471+114 (p<0.1), respectively. Choroid plexus and retinal pigment epithelium exhibited similar levels of GGTP and alkaline phosphatase. Differences in GGTP expression between retinal and brain microvessels were also observed on the mRNA level. In situ hybridization studies revealed that brain microvessels expressed four times more GGTP specific mRNA than retinal microvessels. We conclude that retinal microvessels do not express high levels of GGTP which may make them more vulnerable than brain microvessels to injuries mediated by leukotrienes and oxidative stress.

ISSN:0271-3683    

DOI:10.3109/02713689209001771

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

We studied zinc uptake by nonhuman primate retinal pigment epithelium (RPE) and choroid, usingwZn as a probe. With intravenously administeredMZnCl2, virtually all detectable tracer was lost from the plasma after 20 hours but the pigment epithelium-choroid showed prominent uptake and retention. Plasma concentrations of oral“ZnO remained high 20 hours after feeding. Uptake and retention of orally administeredMZn as“ZnO from the bloodstream by the RPE/choroid was avid in both young and old animals. Excretion in urine and feces was minimal. All pigmented ocular tissues took up and retained“Zn. A survey of total zinc content of human and nonhuman primate ocular tissues showed that the pigmented tissues had consistently higher concentrations of zinc. Our results demonstrate for the first time direct uptake and retention of zinc from the blood by primate RPE and other ocular tissues.

ISSN:0271-3683    

DOI:10.3109/02713689209001772

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Developmental expression of S-antigen and its mRNA in human and rat fetal retina was studied by immunocytochemical andin situhybridization techniques. Immunocytochemistry indicated that S-antigen was present after 4 months gestation in the fetal human retina. In the rat, S-antigen was detected in the retina only after birth.In situhybridization studies indicated that the S-antigen mRNA was present at 13 weeks gestational age in the human and at 15 days in the rat embryo. S-antigen mRNA was expressed not only in the retina but also in ocular tissues of neural crest origin in the fetus.

ISSN:0271-3683    

DOI:10.3109/02713689209001773

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

To assess the protective effect of ascorbic acid in retinal light damage of rats, we have determined the uptake and retinal tissue distributions of its L- and D- stereoisomers following interperitoneal or intraocular injections. The effects of intense-intermittent light exposure and darkness on tissue ascorbate were compared by measuring its levels in retina and retinal pigment epithelial tissues at various times after administration. The protective effects of the two forms of ascorbate against retinal light damage were also compared by measuring rhodopsin levels 2 weeks after intense light exposure. After interperitoneal injection, both forms of ascorbic acid were higher in the retinal pigment epithelial-choroid-scleral complex (eye cup)than in the retina. Over a 2 hr post-injection period, L-ascorbate in the eye cup was 2 to 4 fold higher than normal (10–11 nmol); D-ascorbate levels were between 15 and 30 nmol. During the same period retinal L-ascorbate was just above normal (12–14 nmol), whereas less than 5 nmol of D-ascorbate was present. When ascorbate was given by the intraocular route the opposite effect was found. During the 2 hr post-injection period retinal L-ascorbate levels were 2 to 5 fold higher than normal; D-ascorbate was between 25 and 50 nmol/retina. Within 1 hr post-injection, L-ascorbate in the eye cup was near normal and D-ascorbate levels were 10 nmol or less.In uninjected rats perfused with normal saline, the endogenous L-ascorbate was distributed 55% in the retina with 9% and 36%, respectively, in the RPE-choroid and sclera. Ten-thirty min after interperitoneal injection about 40% of the L-ascorbate was present in the retina with 17% and 44% in the RPE-choroid and sclera. Total ascorbate (L + D) levels in the same tissues of D- injected rats were similar to those found for rats given L-ascorbate. Following 7 hrs of darkness, tissue ascorbate levels in the injected rats decreased to approximately the same levels present in uninjected animals. For rats exposed to intense light average retinal ascorbate levels decreased further, while RPE-choroid and scleral levels were largely unchanged from the dark control levels.About 50% of the tissue ascorbate was present in the retina 10–30 min after intraocular injection. The RPE-choroid contained between 10 and 14% of the ascorbate, with 35–40% present in the sclera. Retinal ascorbate levels remained high in the injected eyes following 2.5 hrs of darkness, but decreased as a result of intense light treatment. RPE-choroid levels and ascorbate in the sclera were similar in the light exposed and dark maintained animals.As measured by the level of rhodopsin present 2 weeks after intense light treatment, interperitoneal L- or D-ascorbate provided equivalent and significant protection for experiments lasting up to 7 hrs. For rats given ascorbate by the intraocular route, the two stereoisomers were also equally effective for exposures lasting 2.5 hrs. In these rats, rhodopsin levels were significantly higher in the L- or D- injected eyes than in the eyes of rats injected with saline, or in the uninjected fellow eyes. In experiments lasting 4 hrs, rhodopsin levels in the injected eyes were higher than in the uninjected eyes, but the differences were not significant. Our findings support an antioxidative role for ascorbate in retinal light damage and suggest that it exerts a protective effect when tissue levels are elevated.

ISSN:0271-3683    

DOI:10.3109/02713689209001774

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Plasmin, a proteolytic enzyme, has been detected in the tears of patients experiencing anterior ocular disease, and during contact lens wear. Using a radial caseinolysis procedure, we examined tear plasmin levels in 66 patients who were wearing soft and rigid lenses for daily and extended wear. Compared to non-contact lens wearers, patients wearing soft and rigid lenses for extended wear were significantly more likely to exhibit tear plasmin activity. Eight hours of open-eye thick HEMA lens wear did not induce tear plasmin activity in a group of 10 subjects. However, significant increases in tear plasmin activity were recorded after short-term (1 hour) eye closure with and without lens wear, and following overnight (8 hours) eye closure without lens wear. Overnight eye closure also resulted in significantly increased numbers of epithelial cells and leucocytes in the tear fluid. Our results suggest that increased tear plasmin activity during extended contact lens wear may be attributable to the effects of eye closure rather than hypoxia or the presence of the contactlens per se.

ISSN:0271-3683    

DOI:10.3109/02713689209001775

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Ethacrynic acid (ECA), a sulfhydryl (SH)-reac-tive diuretic drug, has been shown to increase outflow facility (C) both in living monkey eyes and in the calf eye, in vitro (Epstein et al. 1987). In an attempt to increase the therapeutic index of this drug for potential clinical use in glaucoma, we explored the effect of various thiol adducts of ECA on C in the calf eye in vitro. These adducts might be expected to liberate ECA by a reversible retro-Michael type reaction.Enucleated calf eyes were perfused at 25°C at 15 mm Hg for 5 hours with various ECA-thiol adducts. ECA-cysteine at 0.25 mM (for each) increased outflow facility 104% compared to 38% in sham manipulated eyes (n-10; p<.005). A dose response effect was demonstrated from 0.01 mM to 0.25 mM. A relative potency table (for increasing C) was established for several ECA-thiol adducts:Cysteine = cysteamine

ISSN:0271-3683    

DOI:10.3109/02713689209001776

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Rabbit corneas were injected intrastromally withPseudomonas aeruginosa. Sixteen hours after injection, the rabbits were divided randomly into four treatment groups (3 rabbits/6 eyes per group: 1, ciprofloxacin and prednisolone; 2, ciprofloxacin only; 3, prednisolone only; 4, untreated. Ocular signs of inflammation were graded in a masked fashion by slit lamp examination before injection and 16 and 27 hours after injection. Slit lamp examination scores were significantly lower in eyes receiving ciprofloxacin and prednisolone or prednisolone alone, compared with scores in untreated eyes. Slit lamp examination scores were not significantly lower in eyes receiving ciprofloxacin alone, compared with untreated controls. The numbers of viable bacteria in the corneas treated with ciprofloxacin and in the corneas treated with ciprofloxacin and prednisolone were similar and were significantly less (P<0.0001) than those in untreated corneas, indicating that the presence of the steroid did not interfere with the bactericidal action of ciprofloxacin.

ISSN:0271-3683    

DOI:10.3109/02713689209001777

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Bovine rhodopsin was subjected to reductive methyl-ation in the dark using formaldehyde and high specific activity sodium borotritide. After purification by gel filtration and affinity chromatography on Concanavalin A-Sepharose, the product retained its immunoreactive properties. [3H]-Reductively methylated rhodopsin (specific activity, 32 Ci/mmole) was suitable for use in radioimmunoassays for rhodopsin, having many advantages over radioiodinated rhodopsin for this purpose. The site of the reductive methylation was shown to be the non-active site lysines with the production of tritiated N-e-dimethyllysine and tritiated N-e-methyllysine in a molar ratio of about 1.3:1, respectively. In terms of stability, ease of preparation, and specificity, tritiated, reductively methylated rhodopsin presents itself as a preferable ligand to radioiodinated rhodopsin in many applications, such as the radioimmunoassay.

ISSN:0271-3683    

DOI:10.3109/02713689209001778

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

An experimental model of optic nerve ischemia was designed in the rabbit to determine early biochemical alterations, i.e. -changes of high energy phosphate metabolites (ATP and phosphocreatine)–in occlusive and peri-occlusive areas. Vascular occlusion provoked a rapid fall of ATP and phosphocreatine in the optic nerve. Free radicals scavengers, superoxide dismutase plus catalase or dimethylthiourea were able to counteract the drop of phosphate metabolites in the peri-occlusive area. These results show that hypoxia leads to oxygen-derived free radical generation which can be responsible for cell damage and emphasize the role of free radicals in the pathogenesis of ocular diseases related to vascular dysfunction.

ISSN:0271-3683    

DOI:10.3109/02713689209001779

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor