摘要:

The present study examines the interaction of light damage to the retina and streptozotocin (SZ)-induced diabetes in male and female rats during the early development of the disease, when changes occur in the blood-retinal barrier and in pigment cell membranes. Exposure of rats to low illuminance was used to determine the relationship between photically-induced cell death and diabetes. Other groups of animals were exposed to a greater illuminance for shorter time periods (24 hours) in attempts to identify a specific post-treatment day for the effect of diabetes. Blood glucose levels were monitored to indicate the severity of the diabetes. Morphometric analyses and histo-pathologic observations demonstrated that the outer nuclear layer (ONL, photoreceptor nuclei) was reduced significantly in thickness in female rats exposed to light during a 9 day period after SZ injection, but was unchanged from the control groups when exposed beginning at 12 days after SZ treatment. Removal of the pituitary gland prior to SZ treatment and light exposure resulted in the survival of more photoreceptor cells and prevented the differential in ONL thickness observed between control and diabetic intact animals. Attempts to establish a period of greatest susceptibility of the diabetic retina to photic damage were unsuccessful, but results indicate that prior light history and/or shipment stress might be related to retinal damage from light exposure.

ISSN:0271-3683    

DOI:10.3109/02713688608995159

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Two classes of growth factors affecting endothelial cell proliferation have been found previously in ocular tissues: a heat labile mitogen from retina (RDGF) and a heat stable inhibitor of proliferation from vitreous. The relative amounts of these growth factors in normal and diabetic cadaver eyes were investigated using fetal bovine aortic endothelial cell proliferation as an assay. Equivalent levels of RDGF activity were extracted from diabetic and normal sensory retinas. An extract from pigment epithelium and choroid was found to have similar levels of mitogenic activity, but this activity was not as heat labile as RDGF. Like RDGF, equivalent amounts of mitogen were extracted from diabetic and normal tissue. Normal human vitreous inhibited endothelial cell proliferation, and this activity was enhanced by heating the material (10 min., 95d`C). Four of the five individual diabetic vitreous samples of identical postmortem times were mitogenic when not heated, and exhibited little or no inhibitory activity when heated. Vitreous of identical postmortem times was pooled and fractionated by heparin-Sepharose chromatography to determine if the heat labile mitogen in vitreous was RDGF. From the insulin-dependent diabetic (IDDM) pooled vitreous sample, a prominent protein of 18 Kd was eluted from the column with 1.2 M NaCl, a characteristic of RDGF. This work suggests that both RDGF and the vitreous inhibitor are found in human vitreous, but their relative concentrations may change in the diabetic state so that retinal neovascularization from retina can occur.

ISSN:0271-3683    

DOI:10.3109/02713688608995160

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Papavarine, cholera toxin, and isoproterenol each elevated cyclic AMP in cultured rat retinal pigment epithelium and reduced the phagocytosis of isolated rod outer segments (38–66% of controls) during a 4 hour incubation. In addition, cultured pigment epithelium was preincubated with 25 mM exogenous cyclic AMP for two days and then incubated with outer segments for 4 hours either in the continued presence of exogenous cyclic AMP (condition A) or in the absence of exogenous cyclic AMP (condition B). Under condition B phagocytosis was 38% higher than under condition A. Intracellular cyclic AMP decreased under condition B but remained constant under condition A. These observations provide evidence that short term decreases in intracellular cyclic AMP are associated with increases in phagocytosis of outer segments by cultured rat pigment epithelium.

ISSN:0271-3683    

DOI:10.3109/02713688608995161

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Since scanning electron microscopy (SEM) is commonly used to evaluate hydrophilic lens deposits, it is important to know what artifacts are induced by the various techniques used to process the lenses. We performed scanning electron microscopy (SEM) using never-worn lenses with hydrations from 38.6% to 71%. Each lens was taken from its vial of factory-sealed, sterile-preserved saline and processed for SEM examination using liquid CO2, freon critical point drying, or air drying with or without alcohol dehydration. The lenses revealed abnormal surface structures occasionally resembling deposits reported on worn soft contact lenses. Varying degrees of gas pockets and surface wrinkling were seen. Individual polymers and lens hydration reacted differently to the various techniques of processing. Of the four methods evaluated, air drying without alcohol dehydration induced the least artifacts.

ISSN:0271-3683    

DOI:10.3109/02713688608995162

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

The level of lipid peroxide (LPO) in glucocorticoid-induced cataractous lenses was measured by using thiobarbituric acid. When 0.25μmol of hydrocortisone hemisuccinate sodium (HC) were administered to 15-day-old chick embryos, the level of LPO in the lens increased to approximately 1.4-fold of the control level at 24 to 48 hr after HC treatment. However, the level returned to the control level by 96 hr with the disappearance of opacity in the lens. A triple application of ascorbic acid (20μmol/egg) at 3, 10 and 20 hr after HC treatment prevented cataract formation and elevation in the level of LPO in 60% of the lenses. In 40% of the eggs treated with HC plus ascorbic acid, the results were no different than HC alone. Treatment with prednisolone hemisuccinate sodium (0.25μmol/egg) produced an elevation in the level of LPO in the lens but that with cortisone hemisuccinate sodium or cortexolone hemisuccinate sodium did not change the level of LPO in the lens. The phenomena of the cataract formation and the elevation of LPO in the lens caused by HC seemed to be related to each other and due to its glucocorticoid activities.

ISSN:0271-3683    

DOI:10.3109/02713688608995163

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

Previous studies in the mouse and guinea pig have reported little or no colonization of sensory ganglia by strains of herpes simplex type 1 failing to express the enzyme, thymidine kinase (TK). The current study in the rabbit demonstrated trigeminal ganglionic colonization and reactivation of a latent thymidine kinase negative strain of HSV-1 by two independent methods: iontophoresis-induced ocular shedding and co-cultivation. Treatment with topical steroids during the acute infection did not enhance the latency rate. Following reactivation, back mutation with phenotypic reversion to thymidine kinase positive was demonstrated in a few recovered isolates. The current study also emphasized the importance of species differences to explain differing experimental results in studies of HSV-1 TK negative latency.

ISSN:0271-3683    

DOI:10.3109/02713688608995164

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

A sensitive method for measuring glutathione-protein mixed disulfides is described. The method is based on cleavage of the protein disulfides with performic acid followed by reaction with dinitrofluorobenzene and HPLC analysis with a Bondapak-anine column. Samples containing 0.1 nmoles or more of glutathione-protein mixed disulfide can be detected. The method has been used to demonstrate (a) the presence of low levels of glutathione mixed disulfide in gamma crystallin isolated from bovine lenses, (b) a dramatic increase in such mixed disulfides after exposure of denatured gamma crystallin to O2in the presence of glutathione, and (c) the formation of glutathione-protein mixed disulfide in lens epithelial cells exposed to 0.6 mM H2-O2- for one hour.

ISSN:0271-3683    

DOI:10.3109/02713688608995165

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

The purposes of these experiments were 1) to measure microscopic changes in the epithelium associated with selenite cataract, and 2) to describe the formation and subsequent clearing of selenite cortical cataract. Fourteen-day old suckling rat pups received a single subcutaneous injection of an overdose of sodium selenite at 2.25 mg Se/kg b.w. Development of cortical cataract was observed by biomicroscopy, and changes in epithelium were studied by light microscopy of flat-mounted lens epithelia.Selenite administration caused cortical cataract 15–30 days after injection in addition to previously characterized nuclear cataract. The cortical cataract progressed through equatorial vacuolization, opacity, and finally clearing of the cataract. Mitosis was suppressed and karyorrhexis was observed in the germinative zone of the epithelium 5 hours after selenite injection. Pathological disorganization of the epithelium followed. Changes included vacuolization, loss of meridional rows, and defective fiber formation. Restoration of epithelial morphology was associated with clearing of cortical opacity. Epithelial damage at 5 hours was the earliest change yet recorded for selenite cataract, and these data are consistent with our working hypothesis that the initial site of attack of selenium in both cortical and nuclear cataract is the lens epithelium.

ISSN:0271-3683    

DOI:10.3109/02713688608995166

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

The effect of retrobulbar epinephrine administration on ocular and optic nerve blood flow was studied in phakic rabbit eyes using a radioactive microsphere (85Sr) technique. Blood flow measurements were performed either 5 minutes or 30 minutes after retrobulbar injection of 10μl of a 2% (base) epinephrine bitartrate solution to the right eye of each rabbit. Blood flow was determined for the iris, scraped ciliary processes, choroid, retina, and optic nerve. Five minutes after retrobulbar injection, there was no statistically significant (P>0.05) difference in eplnephrine-treated eyes compared to contralateral control eyes that received 10μl of retrobulbar saline. Thirty minutes after injection, eyes receiving retrobulbar epinephrine had a statistically significant (P<0.05) fall in blood flow to the iris and scraped ciliary processes, but not to the choroid, retina, or optic nerve.

ISSN:0271-3683    

DOI:10.3109/02713688608995167

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

A method using electrothermal atomic absorption spectroscopy was developed for the determination of copper (Cu) concentration in the cornea, iris, and lens of a variety of species, including dog, cat, rabbit, horse, and toad. Previously described methods were used to determine Cu in aqueous and vitreous humor. There was little difference between copper levels in the same tissue or fluid across the species. However, there were age and pathology-related changes in Cu concentration of the aqueous humor, cornea, and lens. In the groups of older dogs, the Cu concentration of the aqueous humor and cornea is significantly lower than the two younger groups. In both the dog and rabbit, lenses from young animals have the lowest copper concentration which increases and then finally decreases with age. Canine hypermature cataracts have a significantly higher copper concentration than control dogs of all age groups. There was no correlation between Cu concentration in the intraocular fluids and the cataractous lenses taken from the same eye. The role such an increase in lenticular Cu concentration may play in cataractogenesis needs to be explored.

ISSN:0271-3683    

DOI:10.3109/02713688608995168

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor