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Biomedical subjects

C C Chan

Publications and source records attributed to C C Chan.

At least 433 records · Page 24Linked to original sources
PubMed1987

S-100 antigenic determinants in human retina.

Few or no S-100 determinants are detectable in normal human retina. However, the expression of this antigen was observed on the retinal Muller cells of eyes with sympathetic ophthalmia or uveitis. This finding, along with other experimental data, may be interpreted as indicating the retinal Muller cells may have an immunoactive role. Although the possibility of non-specific expression of the S-100 antigen during intraocular inflammation cannot be ruled out, it is postulated that, in the retina, Muller cells may have immunomodulating role similar to that of other S-100-positive/Ia-positive cells of certain lymphoid tissues.

Enzyme-Linked Immunosorbent Assay↗
PubMed1987

Pharmacologic effects on the expression of class II histocompatibility antigen in experimental endotoxin-induced uveitis.

Systemic dexamethasone, cyclosporine A, colchicine, indomethacin, and cobra venom factor were administered to Lewis rats that were then challenged with 100 micrograms of Salmonella typhimurium endotoxin. The effects of these five pharmacologic agents in endotoxin-induced uveitis were studied by analyzing their effects on ocular inflammation and on the expression of class II antigen of the major histocompatibility complex (MHC) on the epithelium of the ciliary body and iris. All the agents used in our study exhibited anti-inflammatory effects but only dexamethasone was able to inhibit significantly the expression of Ia antigen on the uveal epithelium. This demonstrates a dissociation between the inflammation and class II antigen expression and supports our previous data that class II antigen presentation may precede the inflammatory infiltrates. The alteration of ocular inflammation and especially the variation of Ia antigen expression in the uveal tissue may provide insight into the mechanism of action and the success of different pharmacologic agents used in the treatment of uveitis.

Animals↗
PubMed1987

Immunopathology of ocular onchocerciasis. 2. Anti-retinal autoantibodies in serum and ocular fluids.

Ocular fluids and sera from 12 onchocerciasis patients and nine age-matched controls living in Tamale, Ghana, were examined for the presence of anti-retinal autoantibodies by the indirect immunoperoxidase technique. Antibodies directed against autoantigens of the inner retina (nerve fiber, ganglion cell, and Müller cell) were found in the sera of 10 of 12 patients, but in only three of nine controls (P less than 0.003). Autoimmune antibodies against the outer segment of the photoreceptor were noted in 7 of 12 patients, in contrast to only one of nine controls (P less than 0.02). Findings with the ocular fluids generally mirrored those with the sera. These autoantibodies could not be absorbed by conventional techniques using either retinal S-antigen (S-Ag) or the interphotoreceptor retinoid binding protein, an observation suggesting that other ocular antigens are involved. Such anti-retinal antibodies, especially those directed against the inner retina, may play a significant role in the pathogenesis of the retinal degeneration and optic atrophy that occur as a consequence of onchocerciasis.

Adult↗
PubMed1987

Conjunctival lesions in adults. A clinical and histopathologic review.

A total of 2,455 conjunctival lesions in adults (over 15 years old) obtained during a 61-year period were reviewed and histopathologically classified as congenital, acquired epithelial, acquired subepithelial, pigmented, inflammatory/degenerative, and miscellaneous. The most common lesions in decreasing order of frequency were: pterygium, nevus, dysplasia, nonspecific nongranulomatous inflammation, and epithelial inclusion cyst. The most common conjunctival malignancy in adults was squamous cell carcinoma, followed by melanoma, and pagetoid change associated with sebaceous gland carcinoma. Squamous cell carcinomas arise from progressive stages of mild, moderate, and severe dysplasia. These tumors have a low malignant potential but may behave more aggressively in the spindle cell and mucoepidermoid variants. Melanomas arise de novo, from nevi or, most commonly, from acquired melanosis and have an associated 14-32% mortality rate by metastatic spread. Sebaceous carcinomas are often initially clinically misdiagnosed, involve the conjunctiva by pagetoid spread, and can have a low rate of metastasis and death if diagnosed early and excised with frozen-section monitoring of the surgical margins.

Adolescent↗
PubMed1987

Nephropathic cystinosis: immunohistochemical and histopathologic studies of cornea, conjunctiva and iris.

Specimens of a cornea, conjunctiva and iris were removed at the time of penetrating keratoplasty in a case of nephropathic cystinosis. Immunohistochemical studies revealed the presence of class II antigens on the stromal keratocytes of the cornea and the vascular endothelial cells, pericytes and fibroblasts of the conjunctiva. In addition, there were thinning and focal breaks in Bowman's membrane. Both of these findings may have contributed to the severe photophobia and blepharospasm seen in patients with longstanding cystinosis.

Child↗
PubMed1987

Immunohistochemical analysis of experimental autoimmune uveoretinitis (EAU) induced by interphotoreceptor retinoid-binding protein (IRBP) in the rat.

Experimental autoimmune uveoretinitis (EAU) was induced in rats by immunization with bovine interphotoreceptor retinoid-binding protein (IRBP) and studied by immunohistochemistry. In general, the IRBP induction of inflammatory cellular components and expression of immune-related antigens on various non-lymphoid cells resembled those provoked by S-antigen (S-Ag). However, differences were found between the two diseases, including: 1) The increase in T suppressor/cytotoxic cells occurred in IRBP EAU more rapidly than in S-Ag EAU. 2) Fewer numbers of non-lymphoid cells expressed major histocompatibility complex class II surface antigens in IRBP EAU than in S-Ag EAU. The immunopathogenic mechanism of EAU induced by these two retinal antigens are discussed.

Animals↗
PubMed1987

Cyclosporine and dexamethasone inhibit T-lymphocyte MHC class II antigens and IL-2 receptor expression in experimental autoimmune uveitis.

Results of recent studies indicated that a monoclonal ART18 antibody recognizes the receptor sites or closely related structures for IL-2 on activated rat T-cells. The major histocompatibility complex (MHC) class II (Ia) antigens (RT1B and RT1D in rat), detected with OX6 antibody, and OX17 antibody, may be present on activated rat T-cells. In the present report, we examined the effect of corticosteroids and cyclosporine (CsA) on the expression of IL-2 receptors and Ia antigens by the T-cells, which constituted the major cellular component of the ocular infiltration during the period of peak ocular inflammatory activity in experimental autoimmune uveoretinitis (EAU). Lewis rats immunized with retinal S-antigen (S-Ag) and treated for a limited time with suboptimal doses of either CsA or Dexamethasone (Dex) subsequently developed EAU. The inflamed ocular tissues were studied using an immunoperoxidase staining technique. CsA treatment resulted not only in the inhibition of IL-2 receptors on T-cells, but also in the prevention of the induction of Ia antigen expression on T-cells and other non-lymphoid cells. Dex treatment resulted in less inhibition of the expression of both class II antigens and IL-2 receptor by the infiltrating T-cells.

Animals↗
PubMed1987

Heterogenous expression of antigenic markers on retinoblasts.

Using a large panel of monoclonal antibodies to antigenic determinants specific for photoreceptor outer segments (S-Ag), for cells of neural (Leu-7) bipolar and/or ganglion cell (A2B5), glial/astrocytic (LN-1) or Muller's cell (M.M.) and two polyclonal antibodies to S-Ag and S-100 protein, the authors studied the expression of these antigenic determinants in four newly established retinoblastoma cell cultures and in cells derived from the Y-79 cell line. All four newly established retinoblastoma cell cultures demonstrated antigenic determinants specific for photoreceptors, astrocyte/glial and Muller's cells. The population of cells derived from the Y-79 cell line reacted mainly with the polyclonal antibody to S-100 protein, reflecting the homogeneity of its cell population mainly harboring antigenic determinants specific for astrocyte/glial cells. The heterogeneic staining of the newly established retinoblastoma cell cultures may reflect the multipotential-embryonic origin of these cells demonstrated by their ability to express antigenic determinants specific for the different cellular elements of the mature neuro-retina while the strictly glial staining of the Y-79 may be the result of cloning of this cell line.

Astrocytes↗
PubMed1987

2-substituted tetralin derivatives as conformationally restricted butyrophenone analogs.

Five related derivatives of 2-(2-piperidinoethyl)tetralin have been synthesized as partially rigid analogs of the neuroleptic butyrophenones. Their in vitro dopamine receptor binding properties and in vivo inhibition of dexamphetamine-induced locomotor activity are described. 1-Phenyl-2-(2-piperidinoethyl)-3,4-dihydronaphthalene hydrochloride (8) is about 1% as potent as haloperidol.

Animals↗
PubMed1986

Expression of HLA-DR antigen on retinal pigment epithelial cells in retinitis pigmentosa.

Class II (HLA-DR) antigens are cell surface molecules that play a major role in the initiation and perpetuation of immune responses. Although most cells do not constitutively express class II antigens, selected cells can be stimulated to do so in some immunologically mediated disorders. When retinal pigment epithelial cells were evaluated by either immunoperoxidase or immunofluorescent staining of frozen eye sections from normal individuals, HLA-DR antigens were not detected. In contrast, retinal pigment epithelial cells from two patients with retinitis pigmentosa did express HLA-DR antigens. These findings demonstrated that at some time during the course of retinitis pigmentosa, the retinal pigment epithelial cell is activated to express HLA-DR.

Aged↗
PubMed1986

HLA-DR antigens on retinal pigment epithelial cells from patients with uveitis.

The pathogenic mechanisms involved in immunologically associated ocular diseases are not clearly understood. To further evaluate these types of disorders, we examined the expression of HLA-DR antigen on eye sections from normal individuals and five patients (six eyes) with ocular inflammation (sympathetic ophthalmia and chronic uveitis). Using immunoperoxidase staining technique and the complement-mediated cytotoxicity assay, we detected the presence of HLA-DR antigens on retinal pigment epithelial (RPE) cells from uveitic eyes. In contrast, HLA-DR antigen was not detected on RPE cells from normal ocular tissue. Our study shows that during the course of human ocular inflammatory disorders, the RPE cell is activated to express HLA-DR antigens. This antigen expression may be important in the initiation and/or perpetuation of immune reactivity in the eye.

Adolescent↗
PubMed1986

Immunohistochemistry and electron microscopy of cyclitic membrane. Report of a case.

An immunohistochemical study using various antibodies directed against antigens of inflammatory cells, neurons, and Müller cells, interstitial collagens (types I and III), basement membrane collagens (types IV and V), and basement membrane glycoproteins (laminin and fibronectin) was performed to characterize the components of two cyclitic membranes (in an enucleated eye and a surgical specimen) from a 15-year-old patient with an eight-year history of chronic bilateral uveitis. When specimens were obtained, no inflammation was seen clinically. Correlative light and electron microscopic examinations were also performed on one specimen. The preponderant cells in the cyclitic membrane were glial cells. The preponderant extracellular tissue within the cyclitic membrane consisted of basement membrane components. These observations suggest that cyclitic membranes could be formed mainly by the extension of proliferative glial elements from the retina, with a minor component derived from fibroblasts.

Adolescent↗
PubMed1986

Experimental occlusion of the retinal vein.

We used a pars plana approach to experimentally induce retinal vein occlusions (RVO) in cats by the application of electric energy near the veins at the optic nerve head. This experimental model was utilized to study the natural evolution of thrombosis in the cilioretinal veins, which are located near the lamina cribrosa in the cat. We observed that occlusion of the retinal veins occurs by the formation of a thrombus and that with time there is associated endothelial cell proliferation and recanalization in each instance.

Animals↗
PubMed1986

Sympathetic ophthalmia. Immunopathological findings.

Ocular tissue from six patients with a clinical diagnosis of sympathetic ophthalmia (SO) was examined using immunohistochemical techniques. All patients presented with a history of bilateral panuveitis after penetrating ocular injury or multiple intraocular surgeries and clinical features of SO. In four cases, classic histopathological features of SO were observed, including granulomatous uveal tract infiltration and subretinal pigment epithelium (RPE) collections of inflammatory cells (Dalen-Fuchs nodules). Bone marrow derived monocytes were the major cellular components in these granulomas. In two cases, histopathology failed to demonstrate typical Dalen-Fuchs nodules or granulomas in the choroid. However, the choroidal infiltrates were composed primarily of T-helper and B lymphocytes, without macrophages or epithelioid cells. The eyes examined in this report indicate that a varied spectrum of immunopathological and histopathological findings may occur in clinically diagnosed SO.

Adult↗
PubMed1986

HLA-DR expression by labial minor salivary gland tissues in Sjögren's syndrome.

Minor salivary gland biopsy specimens from patients with Sjögren's syndrome (primary and secondary) and from normal controls were examined with the four step biotin-avidin-immunoperoxidase assay. The composition of the infiltrating cells was similar in patients with both primary and secondary Sjögren's syndrome, consisting primarily of T lymphocytes with predominance of T helper/inducer cells. B lymphocytes (Leu-14) were approximately 20-35% of the infiltrating lymphocytes, while only a few OKM1 (monocytes/macrophages) cells and Leu-7+ (natural killer; NK) cells were observed. The majority of infiltrating lymphocytes expressed HLA-DR antigens. In the biopsy specimens of the controls there were no infiltrates; the scattered lymphocytes, however, were also predominantly T lymphocytes. Finally, the glandular epithelial cells (ducts and acini) were inappropriately expressing HLA-DR antigens, in contrast with controls where minimal HLA-DR expression was found.

Adult↗
PubMed1986

Expression of Ia antigen on retinal pigment epithelium in experimental autoimmune uveoretinitis.

Recently, human retinal pigment epithelial (RPE) cells have been demonstrated to express class II, HLA-DR, antigens both in vivo and in vitro. HLA-DR antigens were detected on RPE cells from patients with uveitis and retinitis pigmentosa. In addition, in vitro studies revealed that not only does this cell express HLA-DR antigen but also that this antigen can be modulated by the lymphokine, interferon (IFN)-gamma. In this study we evaluated the development of the murine class II, Ia, antigens on RPE cells in experimental autoimmune uveoretinitis (EAU). Ia antigen was evaluated with the avidin-biotin-peroxidase technique. Ia antigen was not detected on RPE cells from normal rats. However, Ia antigen was detected on the surface of RPE cells from EAU rats four days prior to the development of clinical and histopathological EAU. Moreover, the expression of Ia antigen on RPE cells from EAU rats continued to persist until one and one-half months after immunization. This study demonstrates that during the course of EAU the RPE cell is activated to express Ia antigens. This antigen expression may be important in the initiation and/or perpetuation of immune reactivity in the eye.

Animals↗