摘要:

The invasion of Bruch's membrane and subsequently the subpigment epithelial and subretinal spaces by proliferating choroidal capillaries are prominent features of age-related macular degeneration. To facilitate study of this process, pure cell lines of bovine choroidal microvessel endothelium and pericytes were isolated and propagated in cell culture media. Their biological and biochemical properties are described. Choroidal microvascular endothelial cells displayed the characteristic cobblestone morphology, required fibronectin or gelatin for attachment to plastic culture dishes, displayed contact inhibition of growth and spontaneously formed tubules in culture. These cells contained antigens for Factor VIII and were able to phagocytize acetylated-low density lipoprotein. Choroidal microvascular pericytes were nonrectangular in shape and did not require substrate attachment factors. They were unable to form tubules in culture, were Factor VIII antigen negative, were unable to phagocytize acetylated-low density lipoprotein and did not display contact inhibition of growth. Choroidal microvascular pericytes contained antigens for muscle and nonmuscle actin.

ISSN:0271-3683    

DOI:10.3109/02713689008999578

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The binding of radiolabelled cGMP to rod outer sequent proteins has been investigated in lice, heterozygous for the recessive rd gene that leads to rod dysplasia. Two binding sites were detected, by Scatchard analysis, in a crude cGMP phosphodiesterase fraction, extracted with an EDTA wash from outer segnents. Affinities were normal but the capacity of both was reduced 25–351.Photoaffinity labelling with3H-cGMP, followed by SDS PAGE and fluorography, suggested that cGMP PDE was the principal binding component in the extracts. If the finding reflects cGMP bindingin. situ, it might explain the 30–401 lower than normal level of cGMP found in the +/rd retina.Visual pignent has been regenerated in isolated norial and heterozygotic retinas by the application of active isomers of cis-retinal, and the time course of cGMP recovery to 'dark-adapted' levels monitored. The increase in the concentration of cGMP was significantly delayed as compared to that of rhodopsin. No differences in time course or kinetics of recovery were discerned between the two genotypes.

ISSN:0271-3683    

DOI:10.3109/02713689008999579

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Collagen shields are fabricated from dissoluable porcine scleral tissue and have been used as an ocular drug delivery system. The aim of the present study was to determine the time and extent of shield absorption when implanted sub-conjunctivally, and the absorption and release of 5-fluorouracil in vitro. Thirty New Zealand white rabbit eyes were employed. BioCor 72 hour collagen shields were surgically implanted in the subconjunctival space. Rabbits were sacrificed at 7, 14 and 21 days after shield implantation, and the remaining shields removed. Remaining shields were measured by both dry weight and protein assay. The absorption and release of 5-FU from collagen shields was determined in vitro using tritiated 5-FU. The collagen shields were not fully absorbed for at least 14 days in the subconjunctival space. In vitro, 5-FU absorbed by the shields reached saturation levels at approximately 15 minutes. Nearly 100% of the 5-FU was released within 15 minutes. Although the time for subconjunctival shield absorption may be useful for antifibroblast drugs, the rate of 5-FU release from these shields is not optimal for enhancing bleb formation when shields are soaked in solutions of 5-FU.

ISSN:0271-3683    

DOI:10.3109/02713689008999580

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

12(R)-HETE [12(R)-hydroxy-5,8,10,14 eico-satetraenoic acid] is one of the major arachidonic acid metabolites produced by microsomal cytochrome P450 of the corneal epithelium. This metabolite is a potent inhibitor of Na+-K+-ATPase activity in several tissues. We investigated endogenous production of 12(R)-HETE in the rabbit corneal epithelium. Incubation of corneal epithelial sheets (prelabeled with14C-arachidonic acid) with arginine vasopressin resulted in the production of radioactive 12(R)-HETE suggesting its formation from endogenously labeled arachidonic acid. The maximal response was obtained with 1μM arginine vasopressin and represents a 15-fold increase in 12(R)-HETE formation compared with that of control tissues. Stimulation of14-arachidonic acid release with a detergent, digitonin, also resulted in endogenous 12(R)-HETE formation. Analysis of the incubation media following digitonin treatment of prelabeled corneal epithelial sheets revealed that 12(R)-HETE production was maximal at 20μM digitonin, a 17-fold increase over control values. This study is the first to describe hormonal and traumatic stimulation of 12(R)-HETE formation from endogenously labeled arachidonic acid in intact corneal tissues. This study demonstrates that the formation of this Na+-K+-ATPase inhibitor can be modulated by physiological and pathophysiological regulation.

ISSN:0271-3683    

DOI:10.3109/02713689008999581

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Hemicholinium-3 effects on the albino rabbit neural retina have been described, but effects on the retinal pigment epithelium (RPE) have not been closely examined. We have studied retinal morphology and function in Dutch belted (pigmented) rabbits after single intravitreal injections of Hemicholinium-3 or saline. DC electroretinogram recordings show a decrease in a, b, and c-wave amplitudes, with the c-wave affected first. Experiments with sodium iodate show that the early decrease in the c-wave results from a loss of the RPE component of the c-wave, rather than the retinal Slow PIII component. After two days, ophthalmoscopic abnormalities of the fundus are severe in a large area with pigmentary changes. A sharp boundary appears between normally pigmented and depigmented fundus, indicative of a critical threshold for damage. The RPE contains clumped melanin. Pigmented cells are seen away from the basement membrane, an early histological observation temporally correlated with a loss of barrier function seen in fluorescein angiograms. After 10 days, apparent proliferation of non-pigmented RPE cells coincides with re-establishment of the barrier. Rod photoreceptor outer segments are lost 4–7 days after injection in the depigmented regions of the fundus, but outer segments are spared in normally pigmented fundus areas. This regional pattern is distinct from that seen in albino rabbit retina where outer segment loss is fairly uniform. We conclude that Hemicholinium-3 affects the RPE in pigmented rabbits in addition to known effects on retinal cholinergic neurons and photoreceptor disc synthesis.

ISSN:0271-3683    

DOI:10.3109/02713689008999582

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Rabbit corneas were isolated, mounted on plastic rings to form a cup and the endothelium was covered with RPMI tissue culture medium. The preparation was then irradiated with 1 J. cm-2of 300nm light over 1 hour and then incubated for a further two hours in the dark. The supernatant fluid was assayed for chemotactic activity toward rabbit neutrophils in an in vitro Boyden chamber assay. The results indicated that medium from irradiated corneas had a chemotactic activity that was 42% of that produced by the standard chemoattractant f-met-leu-phe, (10-9M) while medium from unexposed corneas and exposed medium alone had less than 3% activity. An in vivo assay using sub-epidermal injection into the back of a rabbit gave qualitatively similar results, only f-met-leu-phe and the medium from irradiated corneas causing neutrophil infiltration of the tissue. A checkerboard analysis confirmed that the activity was chemotactic rather than chemokinetic. Release of a chemotactic factor following UV-B irradiation provides a mechanism for the recruitment of neutrophils, at specific localized areas of the endothelium, that is seen after discrete in vivo irradiation. The results also confirm the importance of corneal inflammatory mediators in the development of tissue damage subsequent to exposure to toxic agents.

ISSN:0271-3683    

DOI:10.3109/02713689008999583

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Macrophages are usually present in epiretinal membranes from eyes with proliferative vitreoretinopathy (PVR). Information on the kinetics of macrophages in the eye may be of help in identifying their role in this disease. To determine the half-life of macrophages in the vitreous, peritoneal macrophages were labeled by allowing them to phagocytose141Cerium (gammaemitter) labeled microspheres, and were then injected into the vitreous of the same rabbit from which they were obtained. The animals were sacrificed at various times post-injection and the radioactivity remaining in the vitreous was measured. Using this procedure, the half-life was found to be 4.8 days.

ISSN:0271-3683    

DOI:10.3109/02713689008999584

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The retinas of both normal and Royal College of Surgeons (RCS) rats with inherited retinal dystrophy have been examined using lectin histochemistry to determine the developmental and degenerative changes of the glycoconjugates in the interphotoreceptor matrix (IPM) between postnatal day (P) 10 and P25, when the adult lectin binding patterns are seen in normal rats. Wheat germ agglutinin (WGA; recognizing sialic acid and/or N-acetyl-D-glucosamine) bound to the apical surface of the retinal pigment epithelium (RPE) sparsely at P10 and prominently at P12 in both strains. In both strains at P14, WGA also stained the basal outer segment zone at the inner segment-outer segment junction. Between P14 and P16 in both strains, there was a dramatic increase in the binding of the interstitial region, the space alongside the outer segments and between the apical and basal outer segment zones. The binding pattern of WGA in normal rats remained basically unchanged from P16 to P25, although the intensity of binding was increased somewhat.Ricinus communisagglutinin-1 (RCA-1; specific for galactosyl residues) bound to the outer segment zone prominently and diffusely with increasing intensity with age at P10, P12 and P14 in both strains. At P16 and older, the intense binding of the interstitial zone was dramatically reduced and the RCA-1 bound primarily to the inner and outer segment junctional region, with weak binding to the apical surface of the RPE in both strains. At P25, the binding of the inner and outer segment junctional region was even more restricted, limited to punctate sites in this zone in normal rats and almost missing in RCS rats. These findings demonstrate that a substantial change in the glycoconjugates of the IPM occurs between P14 and P16 in the retinas of both normal and RCS rats, followed by more subtle changes between P16 and P25.

ISSN:0271-3683    

DOI:10.3109/02713689008999585

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

A study of hydrogel contact lenses was undertaken to determine whether NMR relaxation data can be used as a predictor for on-eye lens dehydration. Proton NMR relaxation times (T1and T2), were determined for a series of contact lenses for which on-eye dehydration data were also available. NMR relaxation times were found to depend upon lens water content, but the dependence was not monotonic. T1values varied between 100 and 800 msec, and T2values varied between 6 and 85 msec for the lenses studied. In this study, the NMR signal and corresponding relaxation times are average values, derived both from lens water protons as well as from exchangeable polymer protons. A simple analysis of the data indicates that the mobility of these protons varies by more than a factor of 10 for the lenses studied. A test for linear correlation between NMR relaxation rate, 1/T1and relative change in lens water mass, %δmwgave r=-0.830 for all data, and r=0.904 if one lens was excluded.

ISSN:0271-3683    

DOI:10.3109/02713689008999586

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The presence of the membrane transport mechanism, lactate-H+cotransport, was tested in explants of rabbit corneal epithelium. Basal corneal epithellal cells were loaded with the pH sensitive fluorescent dye BCECF. Intracellular pH (pHi) was measured by ratioing the fluorescence emission output following excitation at 490 and 440 nm. Perfusion of explants in lactate-containing Ringer's, pH 7.40, produced a reversible decrease in pHi. The lactate induced proton influx (mM/min) followed saturating kinetics, Km = 10.7 mM lactate, Vmax = 10.2 mM/min. Proton influx following addition of 10 mM lactate was inhibited 36, 60 and 47% by pre-perfusion in 1 mM CHC (cyano-hydroxycinammic acid), 500μM H2DIDS (4,4'-disothiocyanato -dihydrostilbene- 2,2'-disulfonic acid) and 1 mM LAIE (lactic acid isobutylester), respectively. These inhibitors of lactate-H + cotransport were reversible. Mersalyl acid (500μM) inhibited proton flux from 10 mM lactate addition by nearly 100%, but was irreversible. Stimulation of lactate production by perfusion in N2equilibrated Ringer's (hypoxia) or the addition of 1 mM NaCN led to a slow alkalinization (0,1 pH unit in 10 min). Pre-perfusion with the reversible inhibitors slowed the hypoxic alkalinization by approximately 40%. It is concluded that lactate-H+cotransport is present in the corneal epithelium and that it contributes to pHi regulation during hypoxia.

ISSN:0271-3683    

DOI:10.3109/02713689008999587

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor