摘要:

Since ultraviolet light may be a contributing factor to cataractogenesis, we investigated the response of the lens epithelium, a potential target for W insult, to WA radiation, Cell survival and the induction and repair of DNA single-strand breaks (SSBs) were measured in cultured rabbit lens epithelial cells following WA exposure. The light was passed through a filter which eliminated wavelengths below 335 nm in order to ensure that the cells were exposed only to WA. In order to study the effect of various fluences of WA on cell survival, 2×106cells suspended in mode's buffer were exposed to WA. During all irradiations the cells were maintained at 0.5°C in order to minimize DNA repair. Following WA treatment, 200 cells were cultured in minimal essential medium containing 10% rabbit serum, and a colony forming assay was used to quantify cell survival. WA induced cell death in a dose-dependent manner. In additional experiments, confluent epithelial cells on glass slides immersed in Tyrode's buffer were irradiated and SSBs were quantified using the alkaline elution technique.A 30 min exposure to WA (180 KJ/m2) induced measurable SSBs. An increase in WA fluence brought about an increase in the number of DNA SSBs. Rejoining of SSBs was measured after the cells were irradiated in Tyrode's for 2 hrs and allowed to repair in the dark for 4 hrs at 36°C in MEM containing 10% serum. Eighty percent of the DNA SSBs were repaired within 4 hrs as determined by analysis of the alkaline elution profile. The repair kinetics were biphasic with an initial fast and subsequently slower component. The results indicate that UVA can induce SSBs in lens epithelial cells, that the cells can repair most UVA-induced SSBs, and that UVA treatment can be toxic to the epithelium.

ISSN:0271-3683    

DOI:10.3109/02713689309020382

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Glucocorticoid-induced ocular hypertension has been demonstrated in both animals and humans. It is possible that glucocorticoid-induced changes in trabecular meshwork (TM) cells are responsible for this hypertension. In order to elaborate further the effect of glucocorticoids on the trabecular meshwork, the ultrastructural consequences of dexamethasone (DEX) treatment were examined in three different human TM cell lines. Confluent TM cells were treated with 0.1μd of DEX for 14 days, and then processed for light, epifluorescent microscopy or transmission electron microscopy (TEN). The effect of DEX treatment on TM cell and nuclear size was quantified using computer assisted morphometrics. Morphometric analysis showed a significant increase in both TM cell and nuclear size after 14 days of DEX treatment. Epifluorescent microscopy of rhodamine-phalloidin stained, control TM cells showed the normal arrangement of stress fibers. In contrast, DEX-treated TM cells showed unusual geodesic dome-like cross-linked actin networks. Control TM cells had the normal complement and arrangement of organelles as well as electron dense inclusions and large vacuoles. DEX-treated TM cells showed stacked arrangements of smooth and rough endoplasmic reticulum, proliferation of the Golgi apparatus, pleomorphic nuclei and increased amounts of extracellular matrix material. The DEX-induced alterations observed in the present study may be an indication of the processes that are occurring in thein vivodisease process.

ISSN:0271-3683    

DOI:10.3109/02713689309020383

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The lacrimal glands of males and females of various species differ with respect to several morphological, biochemical and functional characteristics. The purpose of this study was to determine the effect of sexual maturation on Na+,K+-ATPase, muscarinic cholinergic receptors andβ-adrenergic receptors, which are closely related to the secretion of electrolytes and fluid by the gland, and on other membrane-associated enzymes, specifically galactosyltransferase and alkaline and acid phosphatase. Soluble and total membrane fractions were obtained from lacrimal glands of prepubertal (1.0 kg), pubertal (2 kg), and mature (4 kg) New Zealand white rabbits of both sexes. Prepubertal and pubertal rabbits exhibited no sex differences in the total amount of lacrimal gland protein or in any of the enzymes or receptors, with the exception of galactosyltransferase and alkaline phosphatase. Galactosyltransferase had higher total and specific activities in prepubertal and pubertal males, and alkaline phosphatase had higher specific activity in prepubertal males. As animals matured, total protein and activities of the enzymes increased, and several quantitative differences between males and females became apparent. Samples from mature females contained significantly less DNA and membrane and total protein. Specific activities of Na+, K+-ATPase, cholinergic receptors, galactosyltransferase, and acid and alkaline phosphatase were 40% to 80% greater (p<0.05) in mature females. Total and specific activity forβ-adrenergic receptors, on the other hand, were higher in the male rabbits. These findings suggest that sex hormones play a role in regulating the levels of expression of a number of enzymes and receptors, including several which are clearly involved in lacrimal secretory functions.

ISSN:0271-3683    

DOI:10.3109/02713689309020384

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Neuropeptide Y (NPY)-like immunoreactivity (LI) in the irisciliary body of rats kept under constant darkness (DD) and in 12 h light-12 h dark cycle (LD) was determined by enzyme immunoassay. NPY-LI contents in the iris-ciliary body were found to oscillate in circadian fashion under DD and LD conditions, with a peak at about circadian time 12 (CT 12) and a trough at around CT 0. Unilateral superior cervical ganglionectomy caused a significant decrease in NPY-LI levels in the sympathectomized eye compare to the contralateral intact eye, independent of lighting phase. These results suggest the presence of an endogenous circadian rhythm in NPY-LI content in the rat iris-ciliary body, and the possible involvement of a sympathetic input from the superior cervical ganglion.

ISSN:0271-3683    

DOI:10.3109/02713689309020385

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

A high resolution optical mapping procedure was developed to visualize oxygen concentration levels topographically within the tissue of the inner retinain vivaThe novel optical mapping procedure has the potential for describing oxygen metabolism in retinal and other body tissues and elucidating the coupling of metabolism to function. The method is based upon the fluorescence quenching by molecular oxygen of a lipid soluble probe substance which accumulates within the lipid bilayers of tissue cells. The optical mapping system can provide more than 300,000 values of tissue PO2in space with millisecond time resolution. Optical maps of inner retinal tissue PO2were imaged under conditions of normoxia, hyperoxia, and for a retina which received restricted panretinal photocoagulation. Moreover, the effects of transient increases in intraocular pressure were also investigated. An O2consumption rate of 5.48±0.50 (SEM)×10-−3ml O2/ml tissue/min for the light-adapted rat inner retina was estimated from the application of a Krogh cylinder diffusion model to tissue PO2gradients measured in the capillary-free zone around arterioles. Similarly, arterioles oxygenated a surrounding cylinder of tissue with a mean radius of 144.73±5.52 (SEM)μm. Histograms of PO2values within inner retinal tissue (mean PO2= 25.03 mm Hg, median=24.58 mm Hg) showed remarkable correspondence to those determined invasively in brain by others, using O2microcathodes, possibly suggesting a similarity in the underlying capillary architectures of the two neural tissues. Moreover, panretinal photocoagulation increased inner retinal tissue O2by>10 mm Hg, supporting the hypothesis that the beneficial effects of this treatment in diabetic retinopathy result from relieving a hypoxic stimulus for neovascularization.

ISSN:0271-3683    

DOI:10.3109/02713689309020386

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Adhesion molecules play a critical role in leukocyte emigration to a site of inflammation. In order to assess the potential therapeutic benefit of blocking adhesion molecule function in anterior uveitis, the efficacy of antibodies to specific adhesion molecules was tested in 3 separate rabbit models of anterior uveitis. Antibodies to two different leukocyte molecules, CDlla and CD18, and antibodies to the endothelial ligand for CD11a/CD18, ICAM-1 (intercellular adhesion molecule-1, CD54), were studied in inflammation after intravitreally injected interleukin-1, intravitreally injected endotoxin, or an ocular reversed passive Arthus reaction. The CD18 antibody (2 mg/kg intravenously) reduced the cellular infiltrate with each of these 3 models. The antibody to CDlla was equally effective but was tested only in the IL-1-induced model. The antibody to ICAM-1 reduced the cellular infiltrate associated with this model, but the results did not reach statistical significance. None of the antibodies was able to reduce the associated increase in vascular permeability as measured by protein in the aqueous humor. The antibody to CD18 failed to reduce the inflammation if it was administered 24 hours after the intravitreally injected endotoxin. These observations demonstrate that leukocyte migration into the anterior segment of the eye is dependent on the CD11a/CD18 complex.

ISSN:0271-3683    

DOI:10.3109/02713689309020387

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Oral administration of uveitogenic antigens inhibits the development of experimental autoimmune uveoretinitis (EAU) and the cellular immune response initiated by these antigens. The mechanism of oral tolerance is not completely clear, but accumulating data indicate that suppressor cells are actively involved in this process. The spleen is known to harbor suppressor cells and their precursors and the present study was aimed at testing the role of this organ in the induction of oral tolerance by S-antigen (SAG). We report here that: (a) splenectomy abrogated the induction of oral tolerance; unlike in sham operated controls, feeding with S-Ag did not inhibit the development of EAU in splenectomized rats; (b) spenectomized rats responded with higher cellular immune responses than did sham operated controls, but feeding with S-Ag inhibited these responses in both groups of animals; (c) splenectomy also abrogated the adoptive transfer of tolerance: EAU induction was inhibited in sham operated recipients of splenocytes from S-Ag fed donors but not in the splenectomized recipients. The data thus indicate that the spleen plays an important role in the induction of oral tolerance, perhaps by acting as the site for induction andor amplification of cells with suppressor activity.

ISSN:0271-3683    

DOI:10.3109/02713689309020388

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

In Royal College of Surgeons (RCS) rats with inherited retinal dystrophy, photoreceptor cell degeneration is accompanied by Muller cell changes, in particular, increased expression of the intermediate filament protein, glial fibrillary acidic protein (GFAP). In this study, we examined the expression of GFAP in retinas of 4 month-old RCS dystrophic rats either transplanted with normal retinal pigment epithelial (RPE) cells or injected with vehicle (sham control). The sham-injected and non-treated retinas showed increased expression of GFAP in Muller cells with advancing age. GFAP-immunostained Muller processes were observed in the region of the subretinal space of these RCS retinas beginning by 4 months. However, in the retinas of RCS rats transplanted with normal RPE cells, GFAP expression by Muller cells was significantly reduced. Specifically, under the transplanted RPE cells, GFAP-inununolabeled Muller radial processes were not observed and GFAP immunostaining was not present in the subretinal space at any time period examined. Immunoblot analysis of the superior hemisphere of RPE-cell transplanted retinas of 4 month-old RCS dystrophic rats showed less GFAP immunostaining than sham-injected and the inferior hemisphere of retinas of age-matched RCS rats. This study showed that in normal RPE-cell transplanted retinas of RCS rats, in addition to rescued photo-receptor cells, there was an accompanying stabilization of Muller cells as demonstrated by a reduction in the expression of GFAP.

ISSN:0271-3683    

DOI:10.3109/02713689309020389

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Vertebrate retinas, especially photoreceptor cellular membranes, contain high levels of docosahexaenoic acid (DHA) and relatively low levels of arachidonic acid (AA). The present study was designed to test the hypothesis that DHA enrichment in the retina is the result of preferential uptake and incorporation relative to other fatty acids. Frog retinas were incubatedin vitrowith [3H]DHA or [3H]AA for up to 6 h, and the amounts of label in retinal lipids were quantitated. The incorporation of DHA into total lipids, triglycerides, phosphatidylcholine, and phosphatidylethanolamine was similar to that of AA when each was presented as the only substrate, and was linear with fatty acid concentration and incubation time. The addition of excess, unlabeled AA reduced the uptake and incorporation of DHA into retinal lipids. A slightly greater inhibition was noted for the uptake and incorporation of AA in the presence of unlabeled DHA. There was about 2-3 fold greater incorporation of DHA into phosphatidic acid, diglycerides, and phosphatidylinositol compared with AA, whereas the reverse was found for phosphatidyiserine. The different levels of DHA and AA in retinal phospho-lipids cannot be explained by different rates of uptake and incorporation of these fatty acids into lipids, although some slight enrichment of DHA may be possible by this mechanism. The linear incorporation with fatty acid concentration suggests that the difference could be accomplished by controlling the amount and type of fatty acids delivered to the retina by the adjacent pigment epithelium.

ISSN:0271-3683    

DOI:10.3109/02713689309020390

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Rodkone dysplasia type one (rcd-1) is an early onset inherited retinal dystrophy segregating in the Irish setter breed. It is classed as one of the autosomal recessive canine generalised Progressive Retinal Atrophies (PRA). The disease results in complete loss of photoreceptors by approximately one year of age. Levels of retinal cGMP are markedly elevated and of abnormal distribution in rod photoreceptors. Rod phosphodiesterase activity is absent and mRNA encoding the beta subunit (PDEB) of the holoenzyme is uniquely reduced in predegenerate retinae. Using retinae from normal, unrelated adult dogs we have PCR-amplified and sequenced the cDNA for PDEβ. The cDNA is almost identical to that recently described for the Irish setter in the USA apart from two translationally silent single nucleotide changes. Using carrier and affected setters from a UK breeding colony we have screened genomic DNA and can confirm the G to A transition in rcd-1 affected dogs at position 2420, creating an amber mutation in codon 807. However, PRA-affected Tibetan terriers and miniature longhaired dachshunds are normal at this locus, underlining the genetic heterogeneity of this disease group. In addition we have developed a rapid, PCR-based diagnostic test for this mutation that will differentiate normal dogs from asymptomatic carriers.

ISSN:0271-3683    

DOI:10.3109/02713689309020391

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor