摘要:

Purpose.A clinico-histopathological cross correlation was made to study the mechanism of tissue damage in toxoplasmic retino-choroiditis during an experimental reactivation of chronic toxoplasmosis and to compare the influence of treatment by sulfaddiazine on the retinal lesions.Methods.Chronically infected Swiss-Webster mice were treated, six weeks after infection, with an avirulent strain ofToxoplasma gondii(Beverley strain) with polyclonal rabbit antibody directed against murine interferon gamma.Results.Mice treated by anti-interferon gamma developed clinical lesions between day 15 and day 30 (lesions including single foci of retinochoroiditis, multifocal lesions or diffuse areas of retinal necrosis). These lesions did not arise from borders of pre-existing scars. The retina was photographed with an operating microscope fitted with a 90 diopter lens. Biological study showed a significant rise of parasitic loads in the eye and brain. Histological examination is in favour of free organism dissemination via retinal vessels; the lesions are restricted to the inner retina and ciliary body, the parasites migrated from extra-ocular cysts via the vasculature. No cysts were seen at the beginning of the study; they were found at the scar phase and appeared in mice treated with sulfadiazine. The clinical lesions were not caused by cysts but by coagulated necrosis in the retinal tissue. Parasite migration may have played a trigger role.Conclusions.The retinal damage was constituted either as a result of a toxic effect of the organisms or as a hypersensitive reaction to the toxoplasma organism. The results of this study showed that the treatment with anti interferon gamma was sufficient to reactivate chronic infection.

ISSN:0271-3683    

DOI:10.3109/02713689609003451

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.The proliferation of many cell types are regulated by cytokines and neuropeptides by autocrine and paracrine mechanisms. Retinal pigment epithelial (RPE) cells are also regulated by cytokines. But RPE cells are very close to the neural retina which has some neuropeptides. The present study was to investigate the effects of neuropeptides on the growth of RPE cells.Methods, RPE cells were obtained from the eyes of 11 day old chick embryos and cultured in Dulbecco's modified Eagle's culture medium containing 10% fetal calf serum. The growth of RPE cells was evaluated by [3H]-thymidine uptake.Results.Substance P, p-endorphin and calcitonin gene-related peptide markedly stimulated the growth of RPE cells. The effects of methionine-enkephalin, somatostatin and vasoactive intestinal peptide were intermediate. The strongest effects of substance Rβ-endorphin and calcitonin gene-related peptide were observed at 106to 107M. The stimulation of RPE cells withβ-endorphin was inhibited by naloxone, suggesting that the stimulation withβ-endorphin is mediated by an opioid receptor.β-endorphin and substance P induced RPE cell growth stimulating activity. Leucine-enkephalin and neuropeptide Y did not affect the growth of RPE cells.Conclusions.These results suggest that neuropeptides play an important role in the regulation of RPE cell growth.

ISSN:0271-3683    

DOI:10.3109/02713689609003452

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.To evaluate some RPE cell functions, such as wound healing, in a preparation more similar toin situconditions, we developed a method to obtain and culture retinal pigment epithelial (RPE) cells as a sheet. And we assessed the effects of fetal bovine serum (FBS) on the rate of RPE wound healing.Methods.We prepared RPE sheet cultures by incubating rat eyes in 0.1% proteinase K for 13 min, peeling away the neural retina RPE complex, and then incubating the tissue for 1 h to promote spontaneous separation of the RPE sheet from the retina. A Iter several days of incubation, the cultured sheets of RPE cells were examined by phase-contrast microscopy, scanning and transmission electron microscopy and immunocytochemistry. We made round defects 1 mm in diameter in cultured RPE sheets and estimated the rate of wound closure in media with different concentrations of FBS (0 to 10%).Results.The RPE cells cultured in sheets retained theirin situleatures. including microvilli, tight junctions and gap junctions, and the distribution of actin and cytokeratin filaments. A wound was noted to close with restoration of a polygonal configuration. The rate of wound closure depended on serum concentration in the culture medium; when supplemented with 10% fetal bovine serum, wound closure was complete in approximately 40 h.Conclusions.The RPE sheet-culture technique we developed thus provides a suitable model for studying such RPE cell functions as wound healing or phagocytosis. Curr Eye Res. 15: 714-718, 1996

ISSN:0271-3683    

DOI:10.3109/02713689609003453

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.To investigate possible causes and implications of the decrease in glutathione concentration in rat lenses during organ culture.Methods.Freshly excised lenses were incubated in modified TC-199 medium. Ellman's Reagent or the GSH-400 assay were used to assay glutathione levels in lenses cultured for different times and under a variety of altered culture conditions.Results.In lenses from young rats the glutathione decrease was not ameliorated by reduction of oxygen tension in the incubator, nor by supplementation of the culture medium with various antioxidants or sulfhydryl compounds, nor with the amino acid precursors of glutathione. Addition of 2-mercaptoethanol stimulated cysteine transport into the lens but had only a modest effect in maintaining the level of glutathione. The decrease in glutathione concentration was less in cultured lenses from older rats. Lenses from rhesus monkeys exhibited no decrease in glutathione levels when maintained in organ culture for up to 48 h.Conclusions.The basis for the decreased glutathione in cultured young rat lenses is still uncertain. The data from the present study indicate a definite relationship between glutathione loss and age for cultured rat lenses, with young lenses being much more susceptible. The resistance of cultured monkey lenses to loss of glutathione demonstrates species differences in this property which may be relevant to previously reported differences in susceptibility to oxidative damage.

ISSN:0271-3683    

DOI:10.3109/02713689609003454

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.To develop a rapid and accurate method for the quantification of reduced glutathione (GSH) and oxidized glutathione (GSSG) using micro-quantities of ocular lens.Methods.The epithelium, cortex and nucleus of the lens were separated and also the whole lens was homogenized in 3% metaphosphoric acid. The homogenate was ultrafiltered by centrifugation at 10,000 g in an Amicon microconcentrator, molecular weight cut off 3,000 g. The method does not require prior derivatization of the glutathiones. The filtrate was analyzed on a Mircosorb-MV by a high performance liquid chromatography (HPLC) column using an isocratic solvent system (3% methanol and 10 mM potassium phosphate, pH 3.0) and detection at 200 nm.Results.The GSH and GSSG were eluted from the HPLC column at retention times 5 and 10 min, respectively. The detection limit was 10 pmoles applied to the column. The recovery of GSH and GSSG added to the tissue samples was 97-100%.Conclusions. A fast and sensitive HPLC-method for the quantification of picomole quantities of GSH and GSSG in ocular lens, which does not require prior derivatization, has been developed.

ISSN:0271-3683    

DOI:10.3109/02713689609003455

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.To understand the biological activity of entactin, a component of the basement membrane of the corneal epithelium, we investigated the ability of rabbit corneal epithelial cells to attach to an entactin matrix and the effect of entactin on the cells' attachment to other corneal basement proteins.Methods.Multiwell plastic plates were coated with bovine serum albumin (BSA), alone or with BSA and entactin, laminin, fibronectin or collagen type IV. Cultured rabbit corneal epithelial cells were seeded on the plates. After incubation (usually 90 min), the cells were fixed and stained with 1% crystal violet. The number of attached cells was counted under a light microscope.Results.The numbers of attached cells increased in proportion to both the incubation period and the concentration of entactin coated. Furthermore, the number of cells attached to the entactin-coated plate was greater than the number attached to the BSA-coated plate for each incubation period (30 to 120 min). Likewise, when laminin-coated plates were treated with entactin, the number of the attached cells increased in proportion to the concentration of entactin. However, entactin did not affect the cellular attachment to fibronectin or type IV collagen. Cellular attachment to entactin was partially inhibited by the cells' preincubation with the synthetic peptide (GRGDSP).Conclusions.The present results showed that cultured corneal epithelial cells adhere to entactin and that entactin stimulated the attachment of these cells to the laminin matrix. These findings suggest that entactin plays a specific role in maintaining the normal integrity of the corneal epithelium.

ISSN:0271-3683    

DOI:10.3109/02713689609003456

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.In proliferative vitreoretinopathy (PVR) retinal pigment epithelial (RPE) cells are thought to synthesise and interact with extracellular matrix (ECM) proteins to form fibrocellular membranes attached to the retina, which the cells then progressively contract detaching the retina. Haemorrhage into the eye is an exacerbating factor in the pathology. To investigate some of the possible interactions between ECM proteins, platelet mitogens and RPE cells in this study, we examined the combined effect of platelet derived mitogens and ECM proteins on RPE cell proliferation and contraction.Methods.Cells were cultured on a range of individual ECM proteins as well as on the ECM deposited by normal vitreous fluid and exposed to platelet mitogens. Effects on cell proliferation and cell detachment from these substrates and tissue culture plastic were examined.Results.We report additive/synergistic effects of platelet mitogens (PDGF and TGFb) as well as bFGF, with ECM proteins (laminin, fibronectin, collagen 1 and vitreous-deposited ECM) on RPE proliferation. Further we report stimulation of RPE cell contraction on vitreous proteins when exposed to serum prepared from platelet-rich plasma. In this context it was noticeable that it was cells grown on vitreous matrix plus pigment rather than cells grown on clear vitreous that exhibited this behaviour.Conclusions.This study supports a combined action of platelet mitogens and matrix proteins in inducing RPE cell proliferation and contractility and provides a simplein vitromodel of some of the late stages of PVR.

ISSN:0271-3683    

DOI:10.3109/02713689609003457

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.We have previously shown that 4-hydroxynonenal (4-HNE) causes opacification of cultured rat lenses and that a novel group of glutathione S-transferases (GSTs) exhibit high specific activity towards 4-HNE. Previous studies have shown that t-butylated hydroxy toluene (BHT) induced GSTs in cultured rat lens. Therefore, the purpose of the present studies was to investigate if the opacification of rat lenses exposed to 4-HNE is ameliorated by pre-culturing the lenses in media containing BHT.Methods.Rat lenses were divided into four groups. Groups I and II were controls and groups III and IV were cultured in the presence of 100μM 4-HNE. Groups II and IV were pre-cultured in the media containing 10μ.M BHT for 24 hrs which was designated as 0 time point. Lenses were withdrawn at 24 and 72 h and evaluated for opacification by digital image analysis. Induction of the specific GST isozyme (γGST8-8) was studied in the lens epithelium by immunohistochemical studies.Results.Digital image analysis revealed amelioration in opacification induced by 4-HNE, when the lenses were pre-cultured with BHT. Immunohistochemical studies show that BHT induced GST8_8several folds in the epithelium.Conclusions.These studies indicate that pretreatment with BHT would increase the lens capacity to detoxify 4-HNE by conjugating it with GSH, thus assigning an important detoxication role to this specific GST isozyme in oxidative cataract.

ISSN:0271-3683    

DOI:10.3109/02713689609003458

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.Human uveal melanoma cells have been shown to produce plasminogen activator (PA), an enzyme which can enhance tumor metastasis by promoting degradation of extracellular matrix. This study used cultured human uveal melanoma cells to determine whether the PA production of uveal melanoma cells could be modulated by transforming growth factor-beta2 (TGF-beta2), a mitogen present in the uvea.Methods.Five different cell lines of human uveal melanoma of differing cellular morphology (2 spindle, 2 epithelioid, 1 mixed) derived from tumors from different locations in the eye (3 choroidal, 1 ciliochoroidal, 1 orbital) were grown in serum-free media, in the presence or absence of TGF-beta2 (lng/ml to lOOng/ml). After 24 hrs, the conditioned media were collected and quantitated for PA activity by measuring the radial diffusion in fibrin-agarose clot and for total PA concentration using an enzyme-linked immunoassay.Results.Among the cell lines studied, all produced PA. Cell lines derived from intraocular tumors secreted tissue-type PA (tPA), and TGF-beta2 stimulated tPA activity and secretion of cell lines containing epithelioid cells but had no effect on spindle cells. In contrast, tumor cells isolated from an orbital tumor secreted urokinase (uPA), activity and secretion of which was inhibited by TGF-beta2.Conclusions.We conclude that cultured human uveal melanoma cells produce either tPA or uPA, and TGF-beta2 can have a variable effect on PA production of these cells.

ISSN:0271-3683    

DOI:10.3109/02713689609003459

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose.To investigate the source and protein content of sub-retinal fluid in self-forming experimental serous retinal detachmentsMethods.Detachments were induced in Dutch rabbit eyes using rose bengal photosensitization to cause choriocapillaris injury and thrombosis. Serous detachments formed spontaneously within the next 24 h. Subretinal fluid was withdrawn 3, 8 and 24 hrs after photosensitization, and was analyzed for osmolality and albumin content by gel electrophoresis.Results.The albumin concentration in the subretinal fluid of light-induced detachments was 68% of serum level at 3 h after light damage, and rose close to serum level by 24 h. The osmolality of subretinal fluid 24 h after light damage was essentially the same as serum and vitreous fluid.Conclusions.The subretinal protein and fluid in light-induced detachments in the central retina of the rabbit must come from the choroid, since there are no intrinsic retinal blood vessels in that region of the fundus. These data demonstrate that serous retinal detachments can form from choroidal fluid.

ISSN:0271-3683    

DOI:10.3109/02713689609003460

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor