ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Recent studies have suggested that one possible cause of keratocouns involves increased degradation of the corneal extracellur matrix. Most studies have examined corneas from patients with bilateral, sporadic keratoconus. In this report, both corneas from a 70-years-old man with a history of familial keratoconus and clinical signs of unilateral keratoconus were examined for gelatinase activity. Our results demonstrated a qualitative (three additional activity bands of 88, 92 and 100 kDa molecular weights) and quantitative differences (an appareent increase in overall amounts) in the gelationolytic enzyme profiels of the affected keratoconus corneas, and cultured kearatocytes. In addition, gelatinolytic enzymes were4 more readily extracted from the affected cornea compared with controls. These data lend support to the hypothesis of a heterogeneous etiology for keratoconus and to previous suggestions that this disorder may be related to an alteration in extracelluar matrix degradation.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Keratoconus is a noninflammatory corneal disorder characterized by gradual stromal thinning and astigmatism. Altered degradation of corneal extracellular matrix is a suggested etiology for this disorder. In the present study we established keratocyte cultures from normal and keratoconus corneas and investigated the roles that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMP, TIMP-2) may play. After chemical modification (reduction and alkylation) to remove the inhibitor and activation of enzyme with p-aminophenylmercuric acetate (APMA), keratoconus-conditioned media displayed a significant increase (p < 0.05) in the total potential gelatinolytic activity when compared with normal culture media treated in a similar manner. Basal levels of gelatinolytic activity in keratoconus culture media (no reduction, alkylation, or APMA treatment), determined by two different assay methods, tended to be about twice that of normal cell cultures. By zymography, both keratoconus and normal cultures snowed identical enzyme patterns, which represented MMP-2 (72 kDa) in its proform and, depending on the treatment of the media, varying amounts of activated MMP-2 (65 kDa). This suggests that the increased gelatinolytic activity in keratoconus was not correlated with an increased appearance of either the 65-kDa-activated form of MMP-2 or a new MMP species. In addition, no differences in the amount of MMP-2 were detected that could account for the increased activities in keratoconus cultures. However, a relative decline in the detectable TIMP levels in keratoconus cultures resulted in an apparent three-fold increase in the ratio of MMP-2/TIMP. Northern blots showed no significant changes in mRNA levels for MMP-1, MMP-2, MMP-3, TIMP, or TIMP-2. These data suggest that a possible alteration in the interaction between MMP-2 and TIMP may play a role in the increased gelatinolytic activity seen in keratoconus tissues.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Osteo-odonto-keratoprosthesis is a technique designed for patients with severe corneal opacification who would be at high risk of graft rejection should donor tissue transplantation be performed. Because of the isolation of the prosthetic implant from the tissues that the technique provides, the authors are of the opinion that it is the only viable option in such patients. The visual outcome and complications of the procedure in a series of 85 cases are presented.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

It is sometimes claimed that a relationship exists between Fuchs' dystrophy and angle closure glaucoma and that this is an indication for the simultaneous performance of keratoplasty and cataract extraction in patients with Fuchs' dystrophy. If such a relationship exists, then the anterior chamber depth in Fuchs' dystrophy should resemble that in angle closure glaucoma and a significant degree of cornea guttata might be expected to be common in angle closure glaucoma. In 88 patients with angle closure glaucoma we found that the anterior chamber depth was significantly shallower than in cornea guttata or Fuchs' dystrophy for acute (p < 0.001), chronic (p < 0.002) or incipient angle closure glaucoma (p < 0.001). Cornea guttata and Fuchs' dystrophy were very infrequent in these patients with angle closure, only two having cornea guttata and one Fuchs' dystrophy. These results do not support a relationship between angle closure glaucoma and Fuchs' dystrophy or cornea guttata and do not justify performing combined cataract surgery and keratoplasty in all cases of cornea guttata or Fuchs' dystrophy undergoing keratoplasty. Each case should be assessed on its merits and combined surgery should be reserved for patients shown to have a shallow anterior chamber or significant cataract.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The effect that topically administered cyclosporine A (CsA) dissolved in olive oil has on corneal epithelial permeability was determined by fluorophotometry. Twentysix healthy volunteers, who had no ocular or general disease and were not receiving any topical or systemic treatments, were studied. A Fluorotron Master fluorophotometer was used. Measurements were taken before and 45 min after the instillation of 40 μl of a 2% aqueous solution of sodium fluorescein without preservatives. Basal corneal epithelial permeability, as well as the permeability 24 h after the instillation of 2% CsA-olive oil and of the solvent alone, were calculated. Under sterile conditions, the Sandimmun oral solution (Sandoz, Basel, Switzerland) was used to prepare the topical 2% CsA. Immediately after the 2% CsA-olive oil or the solvent alone were instilled, the volunteers complained of itching for ~1 h and developed punctate keratopathy, which improved the next day. Epithelial permeability 24 h after instillation of 2% CsA-olive oil increased 7.03 times (p < 0.001), and that of the solvent alone increased 6.68 times (p < 0.001). No differences in corneal permeability were found between CsA-olive oil and the vehicle (p = 0.651). We concluded that the olive oil used to dissolve CsA is responsible for the increased corneal epithelial permeability.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The Schirmer's tear test is often performed with topical anesthesia to reduce reflex tearing. Fluress (Barnes- Hind, Sunnyvale, CA, U.S.A.) and Fluoracaine (Akorn, Abita Springs, LA, U.S.A.) are commonly used anesthetic- fluorescein preparations that contain viscous additives. Because the rate of Schirmer's strip wetting is dependent on capillary action, a property related to solution viscosity and surface tension, spurious results may be obtained if these agents are used for anesthesia. We report in vitro Schirmer's strip wetting rates for various concentrations of Fluress and Fluoracaine, as well as pure fluorescein solution using a tear substitute (Dacriose; IOLAB, Claremont, CA, U.S.A.) as a diluent. Results showed a direct concentration-dependent reduction of Schirmer's strip wetting with time for both Fluress and Fluoracaine dilutions compared with Dacriose alone (p < 0.001) or Dacriose-fluorescein solutions (p < 0.001). In addition, Schirmer's wetting with Dacriose-fluorescein solutions caused a separation of the Dacriose and fluorescein wetting fronts (p < 0.001) but did not affect the overall Dacriose wetting. These data have clinical implications concerning false-positive results when testing for dry eyes.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

A rapid (5- to 10-min), sensitive (detection limit 0.6 IU/L), and moderately specific fluorometric plasmin assay for small volume tear fluid samples was developed. Addition of albumin (up to 0.1% final concentration) to the assay buffer improved the sensitivity of the test so that plasmin activity in healthy controls could be detected. pH in the reaction buffer was 8.0, Michaelis-Menten constant for the substrate, H-D-Val-Leu-Lys-7-amido-4-methylcoumarin (AMC), was 0.28 mM, and final substrate concentration in the reaction buffer was 1 mM. Intra- and interassay imprecisions were 1.6 and 4.4%, respectively at a plasmin level of 10 IU/L. Tear fluid flow was significantly higher in the patients than in the healthy controls, and this dilatory effect must be considered when using plasmin determination for diagnostic purposes. This effect was counteracted by correcting the plasmin activity values by tear fluid flow. Plasmin flux is plasmin activity (u,IU) secreted in units of time (min). This parameter showed highly significant differences between the patients and controls. All patients with microbial keratitis, corrosive trauma, ocular trauma, herpetic infection, and other diseases showed highly significant elevation of plasmin flux compared with controls. The highest plasmin flux values (several hundredfold that of controls) were recorded in patients with severe corneal ulcers. Few patient samples showed some involvement of other proteases, which were not inhibited by aprotinin.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Injury to a vitamin A-deficient cornea leads to severe acute inflammation often culminating in ulceration. We report on possible regulatory mechanisms involved in the pathogenesis of corneal inflammation in vitamin A deficiency. Thymocyte comitogenic assay and interleukin (IL)-6 induction in corneal fibroblasts have shown that thermally injured and mechanically abraded vitamin A-deficient rat corneas produce much higher levels of an IL-1-like factor as compared with uninjured or injured normal control corneas. This was confirmed by antibody capture enzyme immunoassays, which detected high levels of IL-la and IL-1 (3 in injured vitamin A-deficient corneas. To our knowledge this is the first report describing the induction of IL-1 in the vitamin A-deficient cornea by thermal and mechanical injuries. When mechanically injured corneas were screened for chemotactic activity, they were found to contain significantly higher levels of a chemoattractant as compared with similarly injured, normal control corneas. Chemotactic activity [expressed as a percentage of a known chemotactic tripeptide, formylmethionyl- leucyl-phenylalanine (fMLP), found in medium harvested from vitamin A-deficient corneas] averaged 58.8 ± 8.9% (SEM) as compared with 12.6 ± 5.4% in medium conditioned by normal corneas. Checkerboard analysis confirmed that the activity in vitamin A-deficient cornea conditioned medium was chemotactic and not chemokinetic. These results demonstrate a correlation between IL-1 levels and severity of inflammation in the injured vitamin A-deficient rat cornea.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

We evaluated the epithelializing-promoting effect of a concentration of 0.005 mg/ml murine epidermal growth factor (mEGF), topically administered four times daily, on the herpes simplex virus 1 (HSV-1) corneal ulcers of the rabbit eye. The severity of the herpetic lesions was evaluated clinically, after the time course of the severity of epithelial keratitis, conjunctivitis, iritis, and stromal disease, for 14 days. A histological assessment was performed in the middle and at the end of the follow-up. The stromal keratitis of the mEGF-treated group was significantly more severe than the keratitis exhibited by the placebo-treated rabbits (Y=X3 X2*X4; p=0.0001). There were no significant differences in the degree of conjunctivitis, epithelial keratitis, iritis, and virus shedding between these groups. No evidence of a toxic effect of mEGF or placebo was found in the mock infected rabbit eyes. More studies, using different herpes virus strains and a broad range of murine and human EGF concentrations, are mandatory to ascertain the general significance of these results. Meanwhile, caution is recommended when using mEGF in the presence of an occult or manifest herpetic eye disease.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID