Microarray analysis of the rat lacrimal gland following the loss of parasympathetic control of secretion.
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Previous studies showed that loss of muscarinic parasympathetic input to the lacrimal gland (LG) leads to a dramatic reduction in tear secretion and profound changes to LG structure. In this study, we used DNA microarrays to examine the regulation of the gene expression of the genes for secretory function and organization of the LG. Long-Evans rats anesthetized with a mixture of ketamine/xylazine (80:10 mg/kg) underwent unilateral sectioning of the greater superficial petrosal nerve, the input to the pterygopalatine ganglion. After 7 days, tear secretion was measured, the animals were killed, and structural changes in the LG were examined by light microscopy. Total RNA from control and experimental LGs (n = 5) was used for DNA microarray analysis employing the U34A GeneChip. Three statistical algorithms (detection, change call, and signal log ratio) were used to determine differential gene expression using the Microarray Suite (5.0) and Data Mining Tools (3.0). Tear secretion was significantly reduced and corneal ulcers developed in all experimental eyes. Light microscopy showed breakdown of the acinar structure of the LG. DNA microarray analysis showed downregulation of genes associated with the endoplasmic reticulum and Golgi, including genes involved in protein folding and processing. Conversely, transcripts for cytoskeleton and extracellular matrix components, inflammation, and apoptosis were upregulated. The number of significantly upregulated genes (116) was substantially greater than the number of downregulated genes (49). Removal of the main secretory input to the rat LG resulted in clinical symptoms associated with severe dry eye. Components of the secretory pathway were negatively affected, and the increase in cell proliferation and inflammation may lead to loss of organization in the parasympathectomized lacrimal gland. (+info)
Pseudomonas aeruginosa corneal ulcer related to overnight orthokeratology.
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BACKGROUND: Overnight orthokeratology was thought to be a safe and non-invasive alternative for low-grade myopia and astigmatism correction. We assessed histories, clinical courses, and visual outcomes of the patients with pseudomonal keratitis related to overnight orthokeratology. METHODS: The records of six patients with pseudomonal keratitis related to overnight orthokeratology were reviewed from January 2001 through December 2002. RESULTS: The average age of the patients was 13 years. The average period between the time that the patient started the overnight orthokeratology program and the onset of infectious keratitis was 17 months. All patients presented with painful red eyes. The area of the corneal ulcer was central in three, and paracentral in three eyes. The corneal infiltrate was small in one eye, and medium in five eyes. The corneal scrapings from these six patients revealed Pseudomonas aeruginosa. All patients responded well to topical antibiotic treatment. Two of six eyes had a final visual acuity within two lines of the pre-infection vision at the last follow-up. Four of the eyes examined lost their best-corrected visual acuity due to central corneal scar or irregular astigmatism. CONCLUSIONS: Overnight orthokeratology contact lens wear has the potential complication of pseudomonal keratitis and may cause significant visual impairment. (+info)
Pseudomonas aeruginosa with lasI quorum-sensing deficiency during corneal infection.
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PURPOSE: To understand the importance of Pseudomonas aeruginosa quorum-sensing systems in the development of corneal infection, the genotypic characteristics and pathogenesis of seven ocular isolates with low-protease and acyl homoserine lactone (AHL) activity and quorum-sensing mutants of PAO1 deficient in lasI, lasR, or rhlR were investigated in the study. METHODS: The possession of the quorum-sensing genes lasI, lasR, rhlI, rhlR, and the quorum-sensing controlled genes lasB, aprA, and rhlAB in the clinical isolates were determined by polymerase chain reaction and Southern blot hybridization. Elastinolytic activity, controlled by the las system, was assayed using elastin Congo red and rhamnolipid production controlled by the rhl system was assessed using agar plates containing methylene blue/cetyltrimethyl ammonium bromide. Induction of keratitis was examined in a scarified inbred BALB/c mouse model. RESULTS: The clinical isolates Paer1 and -3 were lasI and lasR negative, and the isolates Paer2 and -4 were rhlR and rhlAB negative. The isolates Paer17, Paer26, 6294 and 6206 possessed all the genes examined. There was no rhamnolipid production in clinical isolates Paer2 and -4. The isolates Paer1 and -3 were virtually avirulent in the scarified mouse corneas. Using isogenic PAO1 mutants, strain lasI showed a markedly reduced virulence in the corneal infection model. The remainder of the clinical isolates and the lasR or rhlR mutant strains caused severe keratitis. CONCLUSIONS: These results indicate that quorum-sensing deficiency may occur naturally in clinical isolates, and the possession of lasI and hence a functional Las quorum-sensing system may be important in development of corneal infection. (+info)
Ocular bioerodible minitablets as strategy for the management of microbial keratitis.
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PURPOSE: Evaluation in volunteers of ciprofloxacin-containing ocular gelling minitablets with prolonged release properties. METHODS: The irritation potential of ciprofloxacin-containing bioadhesive powder mixtures, used to prepare ocular bioerodible minitablets, was evaluated with a slug mucosal-irritation test. The tear pharmacokinetic profiles of ciprofloxacin were determined in six healthy volunteers after topical administration of a minitablet and a single eye drop in the lower fornix. The drug concentrations in the tear samples collected were measured by using a validated HPLC METHOD: Each volunteer was asked to give an evaluation of the preparations applied by answering a standard questionnaire. RESULTS: The results of the mucosal-irritation test demonstrated the nonirritating properties of the bioadhesive powder mixtures. The ocular minitablet, applied in the fornix was in general well tolerated by the healthy volunteers. The mean tear concentration of ciprofloxacin was 33.0, 135.2, and 33.7 microg/g at 30, 300, and 480 minutes after application of the minitablet. Mean tear levels of 84.7, 45.6, and 8.4 microg/g were obtained at 5, 30, and 60 minutes after application of an eye drop. CONCLUSIONS: Due to their prolonged drug release properties, the ocular minitablets containing ciprofloxacin can be considered as a promising drug delivery system to be used in the treatment of ulcerative bacterial keratitis. (+info)
Contact lens microbial keratitis and prior topical steroid use: a disaster in the making?
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INTRODUCTION: To review the best-corrected visual acuity, ulcer size, microbiological profile and morbidity of contact lens-related microbial keratitis with and without prior topical steroid use. MATERIALS AND METHODS: Retrospective case review of admitted cases of contact lens-related microbial keratitis in a tertiary hospital. Data pertaining to demographics, pre-admission treatment with or without topical steroids, ulcer size, duration of admission, Gram stain and culture results as well as the final best-corrected visual acuity were recorded. Patients are classified into 3 groups: Group 1 received no treatment prior to presentation, Group 2 received topical antibiotics only from their general practitioners and Group 3 prescribed both topical antibiotics and steroids. RESULTS: Forty-six cases were enrolled in the study, 41.3% had prior topical steroids (all dexamethasone) in combination with antibiotics. None of them had topical steroids alone. Large ulcers were associated with steroid use, odds ratio = 7.74 [95% confidence interval (CI), 1.18-50.56] and positivity of Gram stains odds ratio = 7.74 [95% CI, 1.18-50.56] whereas loss of more than 2 Snellen lines was associated with Pseudomonas aeruginosa infection, odds ratios of 21.70 [95% CI,2.09-225.03] and presence of central ulcer, 13.51 [95% CI, 2.33-78.3]. Prior topical steroid use was associated with longer duration of symptoms prior to admission but not duration of stay or surgical intervention. CONCLUSION: Patients with prior topical combined antibiotics-steroids present slightly later and with larger ulcers. However, the duration of stay, final visual acuity, treatment failure and complication rates were not statistically different from the non-treated group. This might be due to 1) early presentation and therefore early treatment of contact lens-related microbial keratitis and 2) the short duration of use of combined antibiotic-steroid eye drops. (+info)
A randomised trial of povidone-iodine to reduce visual impairment from corneal ulcers in rural Nepal.
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AIM: To assess whether povidone-iodine provided any benefit over and above a standard regimen of antibiotic therapy for the treatment of corneal ulcers. METHODS: All patients diagnosed with corneal ulcers presenting for care at a primary eye care clinic in rural Nepal were randomised to a standard protocol of antibiotic therapy versus standard therapy plus 2.5% povidone-iodine every 2 hours for 2 weeks. The main outcomes were corrected visual acuity and presence, size, and position of corneal scarring in the affected eye at 2-4 months following treatment initiation. RESULTS: 358 patients were randomised and 81% were examined at follow up. The two groups were comparable before treatment. At follow up, 3.9% in the standard therapy and 6.9% in the povidone-iodine group had corrected visual acuity worse than 20/400 (relative risk (RR) 1.77, 95% confidence interval (CI) 0.62 to 5.03). 9.4% in the standard therapy and 13.1% in the povidone-iodine group had corrected visual acuity worse than 20/60 (RR 1.39, 95% CI 0.71 to 2.77), and 17.0% and 18.8% had scars in the visual axis in each of these groups, respectively (RR 1.11, 95% CI 0.67 to 1.82). CONCLUSIONS: A small proportion of patients with corneal ulceration treated in this setting had poor visual outcomes. The addition of povidone-iodine to standard antibiotic therapy did not improve visual outcomes, although this design was unable to assess whether povidone-iodine on its own would have resulted in comparable visual outcomes to that of standard therapy. (+info)
Keratocyte loss in corneal infection through apoptosis: a histologic study of 59 cases.
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BACKGROUND: Keratocyte loss by apoptosis following epithelial debridement is a well-recognized entity. In a study of corneal buttons obtained from patients of corneal ulcer undergoing therapeutic keratoplasty, we observed loss of keratocytes in the normal appearing corneal stroma, surrounding the zone of inflammation. Based on these observations, we hypothesized that the cell loss in the inflammatory free zone of corneal stroma is by apoptosis that could possibly be a non-specific host response, independent of the nature of infectious agent. METHODS: To test our hypothesis, in this study, we performed Terminal deoxyribonucleotidyl transferase-mediated d-Uridine 5" triphosphate Nick End Labelling (TUNEL) staining on 59 corneal buttons from patients diagnosed as bacterial, fungal, viral and Acanthamoeba keratitis. The corneal sections were reviewed for morphologic changes in the epithelium, stroma, type, degree and depth of inflammation, loss of keratocytes in the surrounding stroma (posterior or peripheral). TUNEL positivity was evaluated in the corneal sections, both in the zone of inflammation as well as the surrounding stroma. A correlation was attempted between the keratocyte loss, histologic, microbiologic and clinical features. RESULTS: The corneal tissues were from 59 patients aged between 16 years and 85 years (mean 46 years) and included fungal (22), viral (15), bacterial (14) and Acanthamoeba (8) keratitis. The morphological changes in corneal tissues noted were: epithelial ulceration (52, 88.1%), destruction of Bowman's layer (58, 99%), mild to moderate (28; 47.5%) to severe inflammation (31; 52.5%). Morphologic evidence of disappearance or reduced number of keratocytic nuclei in the corneal stroma was noted in 49 (83%) cases; while the TUNEL positive brown cells were identified in all cases 53/54 (98%), including cases of fungal (19), bacterial (14), viral (13), and Acanthamoeba keratitis. TUNEL staining was located mostly in the deeper stroma and in few cases the peripheral stroma. TUNEL positivity was also noted with the polymorphonuclear infiltrates and in few epithelial cells (10 of 59, 17%) cases, more with viral infections (6/10; 60%). CONCLUSIONS: We report apoptotic cell death of keratocytes in the corneal stroma in infectious keratitis, a phenomenon independent of type of infectious agent. The inflammatory cells in the zone of inflammation also show evidence of apoptotic cell death. It could be speculated that the infective process possibly triggers keratocyte loss of the surrounding stroma by apoptosis, which could possibly be a protective phenomenon. It also suggests that necrotic cell death and apoptotic cell deaths could occur simultaneously in infective conditions of the cornea. (+info)
Differential expression of extracellular matrix metalloproteinase inducer (CD147) in normal and ulcerated corneas: role in epithelio-stromal interactions and matrix metalloproteinase induction.
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Extracellular matrix metalloproteinase inducer (EMMPRIN) was originally identified on the tumor cell surface as an inducer of matrix metalloproteinase (MMP) production in neighboring fibroblasts. Here we demonstrate a role for EMMPRIN in MMP induction during corneal wound healing. MMP and EMMPRIN expression was analyzed in normal and ulcerated human corneas, as well as in corneal epithelial and stromal cells in culture using confocal microscopy, zymography, immunoblots, and real-time polymerase chain reaction. In normal cornea EMMPRIN was predominantly expressed in the epithelium but was markedly induced in the anterior stroma of ulcerated corneas. This coincided with MMP-2 induction that co-localized with EMMPRIN at the epithelio-stromal boundary. The role of epithelial-stromal interaction in MMP induction was investigated in an in vitro co-culture system and demonstrated an induction and co-localization of EMMPRIN and MMP-2 in the fibroblasts at the interface with epithelial cells. Direct contact of fibroblasts with EMMPRIN-containing purified epithelial cell membranes also induced MMP-1, MMP-2, and EMMPRIN and this was inhibited by a blocking anti-EMMPRIN antibody, suggesting that EMMPRIN was primarily responsible for this induction. These findings, and the up-regulation of EMMPRIN by epidermal growth factor and transforming growth factor-beta, demonstrate a role for EMMPRIN in wound healing and suggest that sustained local up-regulation of EMMPRIN and MMPs in chronic situations in which healing is delayed may lead to excessive matrix degradation and corneal melts. (+info)