摘要:

Selenite cataract is a fairly recently described, experimental animal model for cataract (1). Selenite cataract has been extensively characterized histologically (2) and biochemically (3,4). The model has been particularly useful for studies on the roles of calcium accumulation and lens proteolysis in cataract formation (4). This review describes current knowledge of the biochemical mechanism for selenite cataract and indicates how the model may be used for further understanding of cataractogenesis in general.

ISSN:0271-3683    

DOI:10.3109/02713688709025181

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

An analysis of the corneal endothelium of a 23 year old female who had never worn contact lenses but who had unilateral ptosis, showed marked endothelial pleomorphism of the cornea underneath the closed lid. Since corneal hypoxia has been shown to produce corneal endothelial polymegethism in contact lens wearers, and since hypoxic condtions exist under the closed lid, it is reasonable to assume that the polymegethous endothelial changes which occur with aging are a result of chronic corneal exposure to hypoxic conditions under the closed lid during sleep. Corneal hypoxia is apparently not the cause of declining endothelial cell density with age.

ISSN:0271-3683    

DOI:10.3109/02713688709025182

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Forskolin was used to study cyclic AMP-mediated regulation of aqueous humor dynamics in rabbits. Crystalline forskolin was solubilized in oil and its pharmacological effects were studied both in vitro and following topical ocular administration. In vitro, using cultured corneal epithelial cells, forskolin rapidly stimulated cyclic AMP production and in vivo increased cyclic AMP concentration in the aqueous humor 10-fold following topical administration. The effect of topical forskolin on intraocular pressure and aqueous humor formation was determined in vivo using pneumatonometry and fluorophotometry, respectively. Forskolin caused a prolonged reduction of intraocular pressure and decreased aqueous humor formation. The ability of forskolin to potentiate the ocular hypotensive effect of epinephrine was investigated. Forskolin in combination with epinephrine caused a decrease in intraocular pressure of longer duration than either 0.1% epinephrine or 1% forskolin administered separately. Forskolin caused a small but significant increase in the permeability of the blood-aqueous barrier at the time of maximal intraocular pressure reduction. This effect on the blood-aqueous barrier may explain the inhibitory effect of forskolin on aqueous humor formation.

ISSN:0271-3683    

DOI:10.3109/02713688709025183

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Purified S-antigen was used to induce experimental autoimmune uveitis in 42 guinea pigs. 16 animals were used as controls. Footpad immunization with fresh bovine S-antigen in physiologic saline mixed with complete Freunds's adjuvant induced a clinical disease in 95% of the eyes in test animals.In aqueous humour the increase in phospholipase-A2and proteins as well as myeloperoxidase measured from iris-ciliary blocks correlated well with the severity of uveitis evaluated by clinical grading. Leukotriene C. and prostaglandin E2were only elevated in aqueous humour arawn from eyes showing a mild form of uveitis. Neither leukotriene C4nor prostaglandin E2were detected in eyes graded as clinically moderate or severe.In serum samples phospholipase A2leukotriene C4prostaglandin E2and gamma glutamyf transpeptidase were measured. Of these biochemical parameters, only gamma glutamyl transpeptidase was significantly elevated in test animals with experimental autoimmune uveitis.Histological analysis revealed focal mononuclear cell infiltrations in the choroid. Mononuclear as well as polymorphonuclear cell infiltration was seen predominantly in the pars plana region of the ciliary body of test animals with uveitis. Simultaneous destruction of the outer segments of the photoreceptor layer was seen.

ISSN:0271-3683    

DOI:10.3109/02713688709025184

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Both anticoagulants (heparin and streptokinase) and non-steroidal anti-inflammatory compounds (aspirin and indomethacin) were used against a water-soluble derivative of marihuana, MDM. While the anticoagulants had no effect on the ocular effects of MDM, both aspirin and indomethacin altered the time course and effected the MDM-induced reduction of intraocular pressure. The usual initial hypertensive effect of intravenous MDM was eliminated and the later intraocular pressure fall occurred earlier as well as being inhibited by about 35 to 50%. Assay for prostaglandins revealed that intravenous MDM (3.86μg) caused a marked rise in PGE2concentration of the aqueous humor and iris-ciliary body during the first hour or two after administration of MDM, but normal values occurred at 4, 6, and 8 hours when the intraocular pressure is reduced by up to 60%. Following intravitreal MDM (0.002μg), however, the PGE2levels remained unchanged over 24 hours, despite the induction of a fall in intraocular pressure between 14 and 18 hours which lasts for many hours. Prostaglandin appears to be involved in the hypertensive phase of intraocular pressure change after intravenous MDM injection; and, while the fall in intraocular pressure may contain a component partially mediated by prostaglandins, there is no evidence that intravitreal MDM induces any effect on prostaglandin levels. The involvement of prostaglandins, therefore, in the mediation of MDM-induced ocular hypotensive effects is apparently small.

ISSN:0271-3683    

DOI:10.3109/02713688709025185

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

The activities of human lens aldehyde dehydrogenase, glyceraldehyde-3-P dehydrogenase, polyol dehydrogenase, triosephosphate isomerase and glutathione reductase were measured prior to and following their exposure to oxidation. Active oxygen species were generated by the reaction of either methylene blue or riboflavin with light over a 60 minute time interval. It was found that oxidants generated by both photosensitizers rapidly diminish the activities of glutathione reductase and glyceraldehyde-3-P dehydrogenase but do not alter the activity of triosephosphate isomerase. After an initial time delay, PD activity likewise was abolished and 50% ADH activity remained at the end of the reaction sequence. All enzyme activities affected declined at a faster rate in the presence of methylene blue than riboflavin, and methylene blue itself served as an enzyme inhibitor to the catalytic function of glutathione reductase and glyceraldehyde-3-P dehydrogenase. These findings suggest that singlet oxygen formation not only alters the properties of the crystallin components of the human lens but also damages several of their enzyme associated counterparts.

ISSN:0271-3683    

DOI:10.3109/02713688709025186

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Humanα-crystallins were separated from fetal, young, senile nondiabetic and diabetic lenses. The effects of aging and diabetes uiellitus were studied by fluorescence measurements, including emission maximum, quantum yield and polarization, using both intrinsic probes (tryptophan and non-tryptophan) and extrinsic probes [4-(N-iodoacetoxy) N-methylamino-7-nitrobenz-2-oxa-1,3-diazole (IANBD) and 6-(p-toluidinyl)naphthalene-2-sulfonate (TNS)]. Results indicate that diabetic effects (glycation and aggregation) give fluorescence change to a far greater extent than that of aging. This was demonstrated by a large decrease in tryptophan quantum yield and an increase in non-tryptophan quantum yield, and also by a decrease in polarization of non-tryptophan. The sulfhydryl (SH)-specific probe IANBD shows a blue-shift in emission maximum, a decrease in intensity and an increase in polarization. The hydrophobic probe TNS shows a decrease in both intensity and polarization. These results suggest that tryptophan oxidation, mixed disulfide formation and glycation, as well as other undetected post-translational modifications have partially unfolded the proteins, making the protein structure less rigid. The possible effect of this unfolding process is that proteins become more susceptible to aggregation.

ISSN:0271-3683    

DOI:10.3109/02713688709025187

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Aqueous humor from human glaucomatous eyes was divided into two groups. Group I aqueous humor contains a negligible amount of ascorbate, while group II contains ascorbate. Group I aqueous humor stimulates ascorbate oxidation. This oxidative effect is inhibited by the addition of EDTA, indicating the presence of metallic ions. The amount of copper determined by atomic spectro-photometry in these samples was 1.54μg/ml. On the contrary, group II aqueous humor protects against ascorbate oxidation. The small amount of albumin present in these samples accounts for part of this protective effect.

ISSN:0271-3683    

DOI:10.3109/02713688709025188

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

We compared the efficacy of two polyenes, amphotericin B and natamycin, in two models of yeast infection. In one, treatment was begun immediately after inoculation, in the other it was delayed 24 hours. In each model infection withCandida albicanswas established in the corneal stroma of dutch-belted rabbits and treated topically with 5% natamycin or amphotericin B 0.15% and 0.075%. Quantitative isolate recovery techniques were used to assess response after 5 days of treatment. A significant therapeutic effect was present for amphotericin B in both models. However, delayed treatment with natamycin was ineffective using treatment schedules efficacious when begun 1 hour after inoculation. A therapeutic effect was present only with administration of the drug every 1/2 hr. This altered response may reflect a difference in susceptibility between different growth phases in yeasts.

ISSN:0271-3683    

DOI:10.3109/02713688709025189

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

Antibodies for several molecules that function in the visual process were used to localize these molecules in primate rod and cone cells. These antibodies (monoclonal or polyclonal) were prepared against Interphotoreceptor Retinoid-binding Protein (IRBP), S-antigen (S-Ag), opsin,α-transducin and also against cyclic GMP (cGMP). Lowicryl-embedded tissues were labeled with secondary antibodies linked to colloidal gold. Although IRBP is predominantly an extracellular protein, the relatively small amount found intracellularly was localized mainly in rods, with little in cones. Opsin, S-Ag and cGMP were found mainly in rod cell outer segments. A polyclonal antiserum raised against transducin-αpurified from rod outer segments predominantly labeled rod cells, but an antiserum against the carboxyterminal decapeptide of transducin-αlabeled both rod and cone cells. Thus, most of these specialized molecules are present predominantly in rod cells, confirming major differences in components of the visual cycle in rods and cones.

ISSN:0271-3683    

DOI:10.3109/02713688709025190

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor