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Query: UMLS:C0022568 (keratitis)
 5,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The diagnosis of fungal keratitis can be difficult and is often delayed. The distinction between moniliaceous and dematiaceous (pigmented) keratomycoses is not commonly possible on clinical examination. We report a case of a Curvularia lunata fungal keratitis in a 40-year-old patient who presented with diffuse brown pigmentation throughout the ulcer bed. Histologic staining and growth on Sabourad's dextrose agar demonstrated the brown pigmentation characteristic of this pigmented fungus. We call attention to this clinical pigmentation as a helpful clue in the detection of dematiaceous fungal keratitis.
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PMID:Macroscopic pigmentation in a dematiaceous fungal keratitis. 205 34

Microbial adherence to corneal epithelial cells is the initial step in the development of infectious keratitis. In an attempt to inhibit this process, we evaluated the effects of concanavalin A (Con A) upon the adherence of Pseudomonas aeruginosa to injured rabbit corneal epithelial cells. A sterile 21-gauge needle was used to create linear epithelial injuries. Identical samples from suspensions of a pure strain of P. aeruginosa were placed on two groups of injured corneas. Prior to bacterial application, one group of corneas received topical application of Con A, a lectin that is capable of binding to alpha-D-mannose or alpha-D-glucose. The animals were sacrificed 1 hour after application of the bacteria. Scanning electron microscopy of the excised corneas revealed that, compared to the corneas that had not been exposed to Con A, those exposed to the lectin had significant fewer adherent P. aeruginosa bacilli. Additionally, only rare bacteria were noted adhering to the uninjured superficial epithelial cells. These results suggest that, by competitively binding to the exposed mannose and/or glucose groups on the surfaces of these cells, Con A is capable of inhibiting the adherence of P. aeruginosa to injured epithelial cells.
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PMID:The use of concanavalin A to competitively inhibit Pseudomonas aeruginosa adherence to rabbit corneal epithelium. 211 42

Three different commercial extended-wear soft contact lenses worn continuously by patients for at least 28 days were stained with fluorescein isothiocyanate-labeled lectins. These lectins detected the presence of alpha-linked or beta-linked D-mannose, D-glucose, D-galactose, L-fucose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and N-acetyl neuraminic acid (sialic acid) on the surfaces of the contact lenses. These saccharides are bound to other sugars that likely account for an integral part of glycoprotein and/or glycolipid deposits on lens surfaces. These tear deposits may contribute to the chemical spoilage of the lens and, furthermore, may serve as specific receptors for pathogenic microorganisms commonly implicated in extended-wear soft contact lens-associated infectious keratitis.
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PMID:Carbohydrate deposits on the surfaces of worn extended-wear soft contact lenses. 347 46

A rabbit model for herpes simplex virus (HSV) stromal keratitis, produced by intrastromal injection of live virus, was used to evaluate the effects of tunicamycin and 2-deoxy-D-glucose therapy. In vivo and in vitro evidence suggests that HSV strains that produce stromal disease secrete relatively large amounts of highly antigenic glycoproteins. Also, various studies have shown that tunicamycin and 2-deoxy-D-glucose inhibit the production of complete HSV-specific glycoproteins. Thus, these drugs might be capable of mitigating the clinical manifestations of HSV stromal keratitis by reducing the antigenic load. However, when topical therapy with tunicamycin and/or 2-deoxy-D-glucose was begun in rabbit eyes, the day after intrastromal inoculation of live RE strain HSV and several days before the appearance of stromal disease, no difference in the clinical course of herpetic ocular disease was seen between the experimental (treated) and control (untreated) groups.
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PMID:The lack of effect of tunicamycin and 2-deoxy-D-glucose on corneal stromal herpes in rabbits. 632 85

In the case reported, herpes virus I after having caused relapsing keratitis in an eye promoted the formation of a severe corneal ulcer caused by Scopulariopsis brevicaulis, a saprophytic mycete found in soil, which only once has been described as the cause of keratitis in man. Scopulariopsis was identified microscopically after culturing the conjunctival secretion on Sabouraud dextrose agar medium, while DNA probe tests confirmed the absence of herpes virus I. Topical and oral administration of miconazole and scraping of the corneal infiltrate dispersed the infection. Subsequently local steroids were given to reduce the neovascularization, and a therapeutic contact lens was applied because of intercurrent corneal thinning. Three months after beginning antifungal therapy, the visual acuity had increased from 1/120 to 1/10. The case described confirms that S. brevicaulis can cause opportunist infections in a cornea previously damaged by a different agent.
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PMID:Fungal keratitis due to Scopulariopsis brevicaulis in an eye previously suffering from herpetic keratitis. 784 51

Acanthamoeba castellanii is a free-living protozoan that causes keratitis in humans and has been associated with pneumonia and granulomatous amebic encephalitis in dogs, sheep, and other species. Adherence of the Acanthamoeba to epithelial cells is critical to the pathogenesis of this disease. In this study, several mouse monoclonal antibodies (MAb) generated to whole Acanthamoeba trophozoites identified surface membrane epitopes by ELISA and IFA. Nine antibodies inhibited adherence of [(35)S]-methionine-labeled Acanthamoeba trophozoites to hamster corneal epithelial cells by 27-90%. Sodium periodate treatment, but not proteinase K digestion, of whole Acanthamoeba destroyed epitopes recognized by adherence-inhibiting antibodies such as MAb 7H6, suggesting that the adherence epitopes are carbohydrates. Other antibodies, MAb 2A8 for example, recognized surface membrane peptide epitopes that were proteinase K sensitive and sodium periodate resistant. Purified MAb 2A8 was used in an antigen-capture ELISA with peroxidase-labeled MAb 7H6 and demonstrated that the carbohydrate adhesion molecule was linked to the peptide recognized by MAb 2A8. Both MAbs 7H6 and 2A8 recognized a >207-kDa band on a Western blot of eluant from a MAb 2A8 immunoaffinity column, confirming that MAb 7H6 and MAb 2A8 recognize different epitopes on the same adherence molecule. MAbs 7H6 and 2A8 also identified the adhesion molecule in soluble Acanthamoeba membrane preparations and MAb 2A8 immunoaffinity column eluant by ELISA and Western blot. Neither of these antibodies were inhibited from binding to whole trophozoites nor membrane extracts by mannose or mannan in competitive binding assays. When our Acanthamoeba membrane preparations were electrophoresed and immunoblotted with alpha-d-mannosylated-biotin albumin, no bands were recognized in the >207 kDa range by our adherence-associated antibodies. These results suggest that the Acanthamoeba adhesin is not identical to the mannose binding protein of Acanthamoeba but rather is a distinct surface membrane glycoprotein.
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PMID:Acanthamoeba castellanii: characterization of an adhesin molecule. 1040 57

Acanthamoebae produce a painful, blinding infection of the cornea. The mannose-binding protein (MBP) of Acanthamoeba is thought to play a key role in the pathogenesis of the infection by mediating the adhesion of parasites to the host cells. We describe here the isolation and molecular cloning of Acanthamoeba MBP. The MBP was isolated by chromatography on the mannose affinity gel. Gel filtration experiments revealed that the Acanthamoeba lectin is a approximately 400-kDa protein that is constituted of multiple 130-kDa subunits. Cloning and sequencing experiments indicated that the Acanthamoeba MBP gene is composed of 6 exons and 5 introns that span 3.6 kb of the amoeba genome and that MBP cDNA codes for a precursor protein of 833 amino acids. That the cloned cDNA encodes authentic MBP was demonstrated by showing that: (i). recombinant MBP possesses mannose binding activity, and (ii). polyclonal antibodies prepared against Acanthamoeba MBP bound to the recombinant protein. Sequence analysis revealed that the MBP contains a large N-terminal extracellular domain, a transmembrane domain, and a short C-terminal cytoplasmic domain. Despite extensive BLAST searches using the MBP sequence, no significant matches were retrieved. The most striking feature of the Acanthamoeba MBP sequence is the presence of a cysteine-rich region containing 14 CXCXC motifs within the extracellular domain. In summary, we have isolated, cloned, and characterized a novel MBP from Acanthamoeba. Because the presence of antibodies to MBP in tears provides protection against infection, the availability of the MBP cDNA sequence and rMBP should help develop: (i). a tear-based test to identify individuals who are at risk of developing the keratitis and (ii). strategies to immunize high-risk individuals.
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PMID:Cloning and characterization of a novel mannose-binding protein of Acanthamoeba. 1511 36

Acanthamoeba are opportunistic protozoan parasites that can cause fatal granulomatous amoebic encephalitis and eye keratitis, however the pathogenic mechanisms of Acanthamoeba remain unclear. In this study, we described the ability of live Acanthamoeba to hydrolyse extracellular ATP. Both clinical and non-clinical isolates belonging to genotypes, T1, T2, T3, T4 and T7 exhibited ecto-ATPase activities in vitro. Using non-denaturing polyacrylamide gel electrophoresis, ecto-ATPases were further characterized. All Acanthamoeba isolates tested, exhibited a single ecto-ATPase band (approximate molecular weight of 272 kDa). However, clinical isolates exhibited additional bands suggesting that ecto-ATPases may play a role in the pathogenesis of Acanthamoeba. This was supported using suramin (ecto-ATPase inhibitor), which inhibited Acanthamoeba-induced host cell cytotoxicity. Previously, we and others have shown that Acanthamoeba binds to host cells using their mannose-binding protein and binding can be blocked using exogenous alpha-mannose. In this study, we observed that alpha-mannose significantly increased ecto-ATPase activities of pathogenic Acanthamoeba belonging to T1, T2, T3 and T4 genotypes but had no effect on non-pathogenic Acanthamoeba (belonging to T7 genotype). Overall, we have shown, for the first time, that Acanthamoeba exhibit ecto-ATPase activities, which may play a role in the pathogenesis of Acanthamoeba as well as their potential role in the differentiation of pathogenic Acanthamoeba.
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PMID:Ecto-ATPases of clinical and non-clinical isolates of Acanthamoeba. 1551 44

Fusarium spp are non-dermatophytic hyaline moulds found as saprophytes and plant pathogens. Human infections are probably a result of various precipitating predisposing factors of impaired immune status. Immunocompetent individuals of late are also vulnerable to various unassuming saprophytic and plant pathogens. To stress the need to identify correctly and institute appropriate antifungal therapy in newly emerging human fungal infectious agents. Repeated mycological sampling of the skin and nails of the suspected fungal infection were processed as per the standard format including direct microscopy and fungal culture on Sabouraud's dextrose agar. The fungus was isolated as Fusarium solani. Fusarium is an important plant pathogen and soil saprophyte. Infection is acquired by direct inoculation or inhalation of spores. It is associated with a variety of diseases like keratitis, onychomycosis, eumycetoma, skin lesions and disseminated diseases.
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PMID:Fusarium Solani: a causative agent of skin and nail infections. 2283 72

Acanthamoeba castellanii is a single-celled protozoan that is widely distributed in the environment and is a well-known of causing human keratitis, a vision-threatening infection. In this study, an ethyl methane sulfonate (EMS) and a selection of saccharide were applied to A. castellanii by chemical mutagenesis. To understand the functional roles of a mannose-binding protein (MBP). A. castellanii were treated with methyl-alpha-D-mannopyranoside abbreviated Man, with and without the EMS pre-treatment, and their adhesion and cytotoxicity were analyzed, using a human brain microvascular endothelial cell (HBMEC) as the target cell. Both EMS and Man mutants exhibited significantly decreased levels of MBP expression and cytotoxicity to HBMEC, but showed similar levels of binding to HBMEC, as compared with the wild type. Of interest was that the exogenous mannose inhibited amoebae (i.e., Man mutant) binding to the HBMEC by <20%. Only the mutant Man exhibited a significant decrease in bacterial uptake, as compared to the wild type, 0.020 vs 0.032 (p<0.05) and proteolytic activity. The results showed that MBP should be clearly provided as the pathogenic target candidate, to further target-based therapy, but EMS mutation should not be associated with initial adhesion and phagocytosis of A. castellanii.
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PMID:Functional roles of mannose-binding protein in the adhesion, cytotoxicity and phagocytosis of Acanthamoeba castellanii. 2294 16


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