摘要:

Interphotoreceptor matrix (IPM), washed from the retina and retinal pigment epithelium (PE) of adult bovine eyes, was assayed for acid protease. Considerable enzyme activity was observed in the IPM—close to one-tenth of the total acid protease of the entire retina-IPM-PE functional unit. The specific activity was much higher in that part of the matrix near the PE. Based on the finding of an acid hydrolase in the IPM, the possibility is discussed that PE cells may secrete lysosomal enzymes and that the process of shed-disc digestion may begin in the IPM, prior to phagocytosis by the PE.

ISSN:0271-3683    

DOI:10.3109/02713688209000781

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Membrane preparations from normal and cataractous human lenses were prepared by a procedure which minimally disrupts membrane lipid structure. Fluorescence depolarization ofcisandtrans-parinaric acid probes was measured as a function of temperature in membranes, lipid extracts, and phospholipids. These measurements indicated that membranes from cataractous lenses were less ordered (more fluid) than equivalent membranes from normal, age-matched control lenses. No significant differences could be detected between normal and cataractous membrane total lipid extracts, or between normal and cataractous membrane phospholipids. These observations imply that membrane lipid-protein interactions play a significant role in determination of lens membrane structure, and that these interactions are altered in cataractous lens membranes.

ISSN:0271-3683    

DOI:10.3109/02713688209000782

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

A methodology has been developed to evaluate the disposition of liposome-encapsulated epinephrine and inulin in the conjunctival sac and selected ocular tissues. Relative to inulin, epinephrine effluxed much more rapidly from liposomes and disappeared more rapidly from the tear pool. As a result, liposomes were found to exert opposite effects on the ocular uptake of epinephrine and inulin. Over a period of 45 minutes, the concentration of epinephrine in the eye was 1.5-3 times lower when presented in liposomes than in aqueous solutions. This contrasted with the 3 to 15 fold increase in inulin concentration in the eye from liposomal preparations of the compound. Specifically, much of the increase in inulin concentration in the cornea can be attributed to an increase seen in the epithelium. Despite elevated inulin concentrations in the ocular tissues it bathes, the aqueous humor was devoid of inulin unless the corneal epithelium was physically removed prior to topical dosing. Collectively, these findings suggest that both the manner in which an entrapped compound interacts with the constituents of liposomes and the manner in which liposomes interact with the absorptive surfaces of the eye can significantly influence its pharmacokinetics in the eye.

ISSN:0271-3683    

DOI:10.3109/02713688209000783

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

A murine model of heterotopic corneal transplantation has been developed. Whole corneas were removed from either inbred Balb/cJ or C57B1/6J mice and inserted into an abdominal subcutaneous pouch in C57B1/6J recipient mice. Fresh donor tissue, donor corneas cultured at 37°C in 5 per cent CO2-95 per cent room air, or donor corneas cultured at 37°C in two atmospheres of 98 per cent 02- 2 per cent CO2(hyperbaric oxygen) were utilized. Twenty-one days later, the recipients were sacrificed and the heterotopic grafts were examined in a masked fashion. Rejected grafts were edematous, opaque, and vascularized. In contast, unrejected grafts were clear and nonvascularized. These results were further confirmed by histological examination of the donor grafts in a masked fashion. Control syngeneic grafts were not rejected. The fresh allografts were usually rejected (91%) as were the allografts cultured in CO2- room air (90%). Thus, this murine model of heterotopic corneal transplantation appears to be useful for the study of the factors involved in rejection.In further studies, the donor tissue was carried in hyperbaric oxygen in order to selectively destroy cells bearing la antigens (Langerhans cells and passenger leukocytes). These allografts were rejected only 23 per cent of the time. On the basis of these experiments, we propose that corneal allograft rejection requires a two-signal process for host sensitization.The K and O region (so-called classI) antigens present on all nucleated cells serve as one-signal. It appears from these experiments that la (classII) antigen-bearing cells (Langerhans cells and any passenger leukocytes) are a potent second signal. Further, when these cells are destroyed other minor histocompatibility antigens emerge as less potent second signals. Once the host generates cyctotoxic lymphocytes they appear to recognize and destroy any cells bearing non-host alloantigens.

ISSN:0271-3683    

DOI:10.3109/02713688209000784

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Human lens cells from 5-91-year old individuals were cultured in 8 different basal media containing fetal bovine, adult bovine, rabbit or human serum or human plasma or in a serum-containing medium supplemented with insulin, epidermal growth factor, fibroblast growth factor plus other hormones or trace elements. Cultures were initiated from explants of the capsule and epithelium or following enzymatic dissociation of cells from the capsule. Under all conditions the epithelial cells had a limited doubling potential. As a function of time in culture, cells enlarged, displayed numerous filaments and exhibited apparentin vitrosenescence. Lens epithelia from 4-6 day old rabbits cultured under identical conditions mimicked the behavior of human lens cells. Lens epithelia from newborn rabbits may be a suitable model for investigating the basis of apparentin vitrosenescence in this cell type and could help in defining the conditions required for the long-term growth of human lens cells. The limited growth of human lens epithelia suggests that these cells require tissue-specific nutrients or hormonal supplements not present in standard tissue culture media.

ISSN:0271-3683    

DOI:10.3109/02713688209000785

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

The effect of aldose reductase inhibitors such as sorbinil, alrestatin, and quercitrin has been studied on the aldose reductase purified from human brain and lens, and aldehyde reductase I purified from human liver, and aldehyde reductase II purified from human brain, liver, and red cells. None of the aldose reductase inhibitors have been found to be specific for aldose reductase. Fifty micromolar sorbinil besides inhibiting aldose reductase, completely inhibits aldehyde reductase II from the brain, liver and red cells. Similarly, alrestatin and quercitrin also are potent inhibitors of aldehyde reductase I and aldehyde reductase II.

ISSN:0271-3683    

DOI:10.3109/02713688209000786

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Our previous ultrastructural cytochemistry and spectrophotometric studies of the adult Sprague Dawl ey rat ocular lens exhibited a decrease in the level of ouabain-sensitive Na-K-ATPase activity during galactose-induced cataractogenesis. Most of the enzyme activity was reinstated 130-days following the switch to a galactose-free diet after the establishment of cataracts in the animals. At this stage, however, a small nuclear opacity remained and normal Na-K-ATPase activity was not reestablished. In contrast, inin uteroinduced cataracts (through maternal feeding of galactose during pregnancy) the opacity was completely reversed 30-days postpartum. Results on Na-K-ATPase activity levels and localization in lenses of the newborn undergoing the cataract reversal process are presented in the present report. Methods reported by Ernst (1972) for cytochemical localization and quantisation of this enzyme were used for this study. The electron-dense reaction product for Na-K-ATPase was located and confined to lateral and apical portions of the epithelial cell membranes, and between the lens fibers. The reaction product at birth was sparse and scattered at these locations. With increase in age of the animal, during the reversal of lens opacity, there was an increase in the reaction product which was present as a continuous layer without interruptions. Spectrophotometric analysis of the incubation media also exhibited an increase in the level of enzyme activity during the reversal of opacity. Na-K-ATPase activity in the lenses of galactose exposed newborns was only at 55% of the level in control lenses (lab chow exposed newborns). This depressed enzyme level at birth in lenses of a galactose group, however, increased to 83% of the control lenses at 60 days following birth. The possible mechanism for the reinstatement of Na-K-ATPase activity during galactose cataract regression is discussed.

ISSN:0271-3683    

DOI:10.3109/02713688209000787

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

The distribution of Langerhans cells (LC) in corneal and conjunctival epithelial flat mounts obtained from outbred albino Swiss-Webster mice of various ages was examined by histochemieal methods. The LC stain positively with ATPase and were negative to DOPA-oxidase. Mouse pup limbal conjunctival epithelium showed one or two LC/mm2. LC began to significantly increase in number by day 31 and ranged from 150-205/mm2in 7-48 week old mice. A slight decrease in LC was seen in 12 and 24 month old mice.

ISSN:0271-3683    

DOI:10.3109/02713688209000788

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor