Distribution of ascorbate in the anterior bovine eye.
(41/1498)
PURPOSE: To analyze the ascorbate distribution in the anterior eye wall to better understand the functional significance of this compound in the eye. METHOD: Ascorbic acid was determined by high-performance liquid chromatography using an LC-10 system (Shimadzu, Kyoto, Japan). Bovine eye samples were used. RESULTS: The highest ascorbate concentration was observed in the corneal epithelium, with significantly higher values in the central (1.56 mg/g) than in the peripheral (1.39 mg/g) area. The ascorbate content was similar in the corneal stroma (0.22 mg/g), the Descemet's membrane (DM)/endothelium (0.22 mg/g), and the aqueous humor (0.21 mg/ml). By comparison, the sclera (0.15 mg/g) and the conjunctiva (0.11 mg/g) showed lower values, as did the lacrimal gland (0.09 mg/g) and the serum (0.0008 mg/ml). CONCLUSIONS: (1) Peak ascorbate concentration was observed in the central corneal epithelium covering the pupillary area. This is compatible with the idea that the ascorbate may act as an UV filter shielding internal eye structures from radiation damage. (2) The ascorbate concentration in the corneal stroma and DM/endothelium was as high as in the aqueous humor, and it is suggested that the aqueous humor plays a key role in the distribution of ascorbate to the anterior eye wall. (+info)
Vitamin A deficiency alters the expression of mucin genes by the rat ocular surface epithelium.
(42/1498)
PURPOSE: To study effects of depletion of retinoic acid on expression of the mucins ASGP (rMuc4), rMuc5AC, and rMuc1, by the corneal and conjunctival epithelia of the rat. METHODS: Nineteen-day-old Sprague-Dawley male rats were fed a casein-based vitamin A- deficient diet or casein-based diet with vitamin A as control. Rats from both groups were killed at 1, 3, 5, 13, 15, 18, and 20 weeks after initiation of feeding. Expression of the three mucin genes by the ocular surface epithelium was assayed by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: In vitamin A-deficient rats, ASGP mRNA was not detected by RT-PCR after 15 weeks of feeding. rMuc5AC mRNA was detected by RT-PCR at 15 weeks, but by 18 and 20 weeks was no longer detectable. By in situ hybridization, ASGP mRNA was localized in the entire ocular surface epithelium after 1 week of feeding, was diminished but detectable above background by 13 weeks, and was not detectable at 20 weeks. rMuc5AC mRNA was detected in the goblet cells of vitamin A- deficient rats by in situ hybridization at 13 weeks, but was lost by 20 weeks, as were identifiable goblet cells. rMuc1 mRNA were detected by RT-PCR through all time points of 1 to 20 weeks in both vitamin A-deficient and control rats, indicating no significant change in rMuc1 mRNA expression with vitamin A deficiency. CONCLUSIONS: Both the membrane-spanning mucin ASGP (rMuc4) and the secretory mucin rMuc5AC are directly or indirectly regulated by vitamin A in the ocular surface epithelium, whereas the membrane-spanning mucin rMuc1 is not. (+info)
Expression of CD40 and CD40 ligand in the human conjunctival epithelium.
(43/1498)
PURPOSE: CD40 antigen is a membrane receptor that plays a role in the regulation of immune reactions. The expressions of CD40 and CD40 ligand (CD40L) were investigated ex vivo and in vitro in conjunctival epithelial cells, in correlation with HLA DR class H antigen, previously shown to be upregulated in conjunctival inflammatory conditions. METHODS: Impression cytology specimens were collected in 186 patients: 52 normal ones, 65 with keratoconjunctivitis sicca, and 69 with chronic conjunctivitis. Cells were processed for flow cytometry, by using monoclonal antibodies to CD40, CD40L, and HLA DR antigens. Chang conjunctival cells were also used and treated with human recombinant interferon (IFN)-gamma or tumor necrosis factor (TNF)-alpha. CD40, CD40L, and HLA DR expressions were studied by flow cytometry after 24 and 48 hours of treatment. RESULTS: CD40 was found in both normal and pathologic eyes. Quantitation of levels of fluorescence showed a significantly higher expression in pathologic eyes than in normal ones (P < 0.0001). CD40L was variably and inconstantly expressed by conjunctival cells. A strong expression of HLA DR was observed in pathologic eyes, whereas normal eyes showed very low levels (P < 0.0001). Significantly positive correlations were found among CD40, CD40L, and HLA DR levels. Chang conjunctival cells expressed CD40 in basal conditions, whereas CD40L and HLA DR were negative. CD40 expression significantly increased after 24 hours of IFNgamma treatment and after 48 hours' exposure to TNFalpha. These cytokines had no effect on CD40L expression. HLA DR was upregulated after 24 hours of treatment with IFNgamma but remained negative after exposure to TNFalpha. CONCLUSIONS: Human conjunctival epithelial cells normally express CD40 antigen, and, more inconsistently, CD40L. Flow cytometry showed higher expression of these molecules in inflammatory eyes than in normal ones in correlation with class II antigen expression, as well as CD40 and HLA DR upregulation after treatment with proinflammatory cytokines in vitro. (+info)
Apoptosis and apoptosis related gene expression in normal conjunctiva and pterygium.
(44/1498)
BACKGROUND: Pterygium is a relatively common eye disease in the tropics whose aetiology and pathogenesis remain uncertain. As such, interest has focused on understanding the underlying mechanism of pterygia development. METHODS: 15 specimens of pterygia from 15 eyes were examined, together with normal conjunctival tissue from the same eyes for the pattern of gene expression of genes associated with the induction or repression of apoptosis (p53, bcl-2, and bax). In addition, the samples directly for apoptotic cells were examined by the terminal deoxynucleotide transferase (TdT) mediated nick end labelling (TUNEL) methodology. RESULTS: In pterygia specimens apoptotic cells were found mainly confined to the basal layer of cells of the epithelial layer, situated immediately adjacent to the fibrovascular support layer. These cells were shown to express significant levels of p53 and bax, as well as the apoptosis inhibiting protein bcl-2. In contrast, normal conjunctival specimens displayed no bcl-2 expression and apoptotic cells were seen throughout the entire width of the epithelial layer, coupled with high levels of bax expression. CONCLUSION: These results support a model whereby pterygia development is a result of disruption of the normal process of apoptosis occurring in the conjunctiva. (+info)
Membrane-associated mucins in normal human conjunctiva.
(45/1498)
PURPOSE: To examine the presence of specific membrane-associated mucins in normal human conjunctiva. METHODS: Glycoconjugates were extracted from membranes with two detergents: octylglucoside and Triton X114. Mucins were separated by cesium chloride density gradient centrifugation. Size was assessed by gel filtration on Sepharose CL2B and charge by ion-exchange chromatography on MonoQ. Cross reaction with antibodies against mucin gene products was assessed in blots of electrophoresis gels. RESULTS: Extraction of total tissue membranes yielded material with a buoyant density typical of mucins. Gel filtration showed material reacting with antimucin antibodies in a range of molecular sizes. Agarose electrophoresis confirmed the presence of MUC1 and MUC4 and the absence of MUC2 or MUC5AC. Isolation of membrane mucins by sequential, exhaustive extraction with octylglucoside followed by Triton X114 suggested the existence of mucins in different membrane environments. Reagents to carbohydrate epitopes revealed high mobility material, comigrating with MUC1 and MUC4. Low mobility membrane-bound mucins did not cross-react with any antibodies to mucin genes known to be expressed in human conjunctiva. CONCLUSIONS: Membrane-associated mucins are distinct from secreted mucins in normal human conjunctiva. MUC1 and MUC4 mature products decorate the membranes of conjunctival epithelial cells. Their segregation between octyl glucoside and the detergent and aqueous phases of Triton X114 suggests a variety of membrane anchoring modes. (+info)
Overexpression of MMP-1 and MMP-3 by cultured conjunctivochalasis fibroblasts.
(46/1498)
PURPOSE: To determine whether conjunctivochalasis, denoting redundant, loose, nonedematous inferior bulbar conjunctiva, is associated with increased expression and activity of matrix metalloproteinases (MMPS) over their tissue inhibitors (TIMPs). METHODS: Expression of transcripts and proteins of MMPs, TIMPs, and urokinase plasminogen activator (uPA) by cultured normal human conjunctival and conjunctivochalasis fibroblasts was determined by Northern hybridization, enzyme-linked immunosorbent assay (ELISA), and Western blot analysis, respectively. Gelatin and casein zymography and quantitative collagenase activity assay were performed in the serum-free conditioned media. RESULTS: Compared with normal conjunctival fibroblasts from six subjects, conjunctivochalasis fibroblasts from eight patients showed markedly increased transcript expression of MMP-1 (5- to 32-fold) and MMP-3 (4 to 30-fold), whereas that of MMP-2, TIMP-1, TIMP-2, and uPA was similar between the two groups. Protein levels were increased in the serum-free conditioned media of conjunctivochalasis fibroblasts for MMP-1 (3.5- to 7.6-fold) and MMP-3 (2.3- to 13-fold), determined by ELISA and Western blot analysis. There was increased caseinolytic activity of MMP-3 and collagenolytic activity of MMP-1 (2.2-fold) by conjunctivochalasis fibroblasts, whereas no difference was noted between these two types of fibroblasts in the protein and gelatinolytic activity of MMP-2 or expression of TIMP-1 and TIMP-2 proteins, although that of TIMP-1 transcript was slightly higher in some conjunctivochalasis fibroblasts. No expression of MMP-9 was detected. CONCLUSIONS: Overexpression of MMP-1 and MMP-3 mRNA by conjunctivochalasis fibroblasts is correlated with their increased protein levels and proteolytic activities. Collectively, these data help explain how conjunctivochalasis manifests excessive degradation of the conjunctival matrix and Tenon's capsule. (+info)
Long term results after autologous nasal mucosal transplantation in severe mucus deficiency syndromes.
(47/1498)
AIM: Severe mucus deficiency syndromes may require substitution of mucous membrane for re-establishment of the ocular surfaces. The long term results after autologous nasal mucosal transplantation were investigated. METHODS: 55 eyes of 50 patients with severe mucus deficiency syndromes were followed retrospectively after free autologous nasal mucosal transplantation-group A: patients after severe lye, acid, heat burns, or radiation (n=38 eyes), group B: patients with systemic mucosal disease (n=17 eyes). The results of routine clinical examination were recorded and patients were followed for a median of 37 months. 17 biopsies of transplanted nasal mucosa were studied by light microscopy and 22 patients by impression cytology before and at several intervals after mucosal transplantation. RESULTS: All nasal mucosal grafts healed well and no intraoperative complications occurred. During follow up 107 additional surgical procedures were performed including 16 lamellar and 21 penetrating keratoplasties. Subjective complaints improved in 44/47 patients with preoperative symptoms. Best corrected visual acuity at the end of follow up was increased in 23 eyes, 10 eyes (18. 2%) reached a final visual acuity equal to or greater than 20/200. Histopathologically, all (n=17) biopsies showed vital intraepithelial mucin producing goblet cells in the nasal mucosal graft (median 25 cells/field (400x magnification)). The mean density of goblet cells before transplantation was 48/mm(2) and after nasal mucosal grafting 432/mm(2) measured by impression cytology (p<0. 0001). CONCLUSIONS: Functional goblet cells persist in autologous nasal mucosa for up to 10 years after transplantation. In patients with severe mucus deficiency syndromes of different origin nasal mucosal transplantation can re-establish the ocular surface, substitute the mucus components of the tear film, improve symptoms of the patients, and facilitate a moderate increase in visual acuity. (+info)
Indeterminate melanocytic proliferations of the conjunctiva.
(48/1498)
PURPOSE: The purpose of this study is to test the hypothesis that a subset of conjunctival melanocytic proliferations exists that cannot be reproducibly classified as benign, malignant, or indeterminate. METHODS: Three groups of excisional biopsy specimens of conjunctival melanocytic proliferations were evaluated by 5 ophthalmic pathologists. These groups included lesions that were considered by the authors to represent benign (Group 1, n = 5), malignant (Group 2, n = 5) and indeterminate melanocytic proliferations (Group 3, n = 5). The panel classified the same sections in all 3 groups in a randomized, masked fashion, first without and then with a clinical history of patient age, sex and race. The kappa statistic (k) was used to quantify the degree of agreement among observers. RESULTS: There was strong concordance among the panel for both Group 1 (benign, k = 0.76) and Group 2 (malignant, k = 0.70) melanocytic proliferations. There was no concordance of the panel for Group 3 (indeterminate) lesions (k = -0.045). The concordance for Groups 1 and 2 and lack of concordance for Group 3 lesions were independent of knowledge of clinical history of age, sex, and race. CONCLUSIONS: A subset of melanocytic proliferations of the conjunctiva exists that cannot be reproducibly classified by pathologists as benign, malignant, or indeterminate. (+info)