摘要:

This study establishes the metabolic similarities and differences of intact abattoir corneas and the human cornea ex vivo, using31P nuclear magnetic resonance spectroscopy. Phosphorylated sugars (SP), inorganic orthophosphate (Pi), phosphodiesters, ATP, ADP, and the nucleoside diphosphosugars and dinucleotides (NS&DN) were quantitated. The intracorneal pH also was determined. In addition, metabolic indices ATP/Pi, ATP/ADP, ATP/ (ADP + Pi), SP/Pi, the phosphorylation potential, and the31P energy modulus were calculated. Significant differences were observed between the abattoir and human corneas in phosphorylated sugars, NS&DN, and intracorneal pH, as well as in the indices ATP/ADP and SP/Pi. The overall energy status as measured by the31P energy modulus was significantly higher in the bovine cornea when compared to the porcine and human corneas, suggestive of a very high energy reserve in the bovine cornea.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Theoretical light scattering calculations, when applied to models based on structures seen in electron micrographs of corneal stroma, require knowledge of the constituent fibril positions and radii. Obtaining this information manually is a difficult and time-consuming task. In order to facilitate this problem, we present a simple and flexible computer algorithm that allows the process to be automated using a Macintosh computer. The accuracy of the results is checked by comparing light scattering calculations using fibril positions and radii found manually with those found by the computer. The results show that the computer algorithm is a viable and accurate means of obtaining the needed data.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Corneal graft failure is frequently mediated by uncontrolled inflammatory disease. We studied the expression of cell adhesion molecules in seven penetrating keratoplasty specimens with graft failure and in a normal eye bank cornea using immunohistochemical staining and monoclonal antibodies against intercellular adhesion molecule- 1 (ICAM-1, CD54), lymphocyte functionassociated antigen-1 (LFA-1, CD1 la/CD 18), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and major histocompatibility complex (MHC) class II antigen (HLA-DR). ICAM-1 and HLA-DR were expressed on keratocytes and the corneal endothelium in six of the seven specimens. ICAM-1 expression was strongest in the corneas with the most severe inflammation (corneal allograft rejection and severe intraocular inflammation). LFA-1 is a counter-receptor for ICAM-1, and infiltration with leukocytes expressing either the a or (J chain of LFA-1 was found in areas of ICAM-1 expression in four of the seven corneas. In contrast, E-selectin was expressed in the stroma in only two specimens, and VCAM-1 in one specimen. Expression of cell adhesion molecules or MHC class II antigen were not detected in the normal eye bank cornea. These data suggest that ICAM-1 expression may play an important role in the development of corneal graft failure. Furthermore, monoclonal antibodies to block ICAM-1 or its ligands may inhibit the development of corneal inflammation.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Mooren's ulcer is a chronic, painful rodent nonpurulent corneal ulcer. In order to discern the possible role that immunological processes (antibody and cell-mediated) play in the development of a Mooren's ulcer, we evaluated sera from patients (n=16) for the presence of circulating antibodies against normal rabbit and human corneal epithelium using an indirect immunofluorescent technique (IFT) and determined the T-lymphocyte subsets (CD4, CD8, CD11) in the peripheral blood. This condition was treated with an immunophilin, cyclosporin A (CsA) (0.5% solution), applied topically. Antibodies against rabbit corneal epithelium were detected in 12 of 16 patients (75%), while only six of 16 (37.5%) patients had antibodies against human corneal epithelium. The percentage of CD8 (suppressor T cells) T lymphocytes was significantly lower in patients with Mooren's ulcer than in the controls (p<0.01). Mooren's ulcer was effectively treated with 0.5% CsA in 11 of 18 (61.1%) affected eyes (n=14 patients), as determined by long-term (24-31 months) follow-up. We noted particularly that regulatory imbalance existed in the immune systems of the patients. We also think that the limbus and conjunctival lymphoid tissue adjacent to the limbus might play an important role in the pathogenesis of the disease. The detection of serum antibodies against corneal epithelium and determination of T-lymphocyte subsets in the peripheral blood may provide a referential basis for the clinical diagnosis of Mooren's ulcer. Effective treatment with 0.5% topical CsA is primarily through the depression of ocular immunoreactions, although systemic action is not completely ruled out.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Eighteen suture abscesses that developed after penetrating keratoplasty in 15 patients were reviewed. The time from keratoplasty to the diagnosis of an abscess ranged from 1 to 53 months with a mean of 21.5 months. In 13 of the 18 cases, the patient was taking topical steroids at the time of diagnosis. All were culture-proven bacterial ulcers, except for one case that had a positive Gram's stain, but no growth on culture. The organisms cultured were Staphylococcus epidemidis (six eyes), Streptococcus pneumoniae (five eyes), Sta. aureus (four eyes), Str. viridans (two eyes), Klebsiella oxytoca (one eye), Serratia marcescens (one eye), Moraxella sp (one eye), and Escherichia coli (one eye). The offending suture was removed in all cases, and the eyes were treated with topical fortified antibiotics (cefazolin and tobramycin). After treatment, 67% (12 of 18 eyes) had clear grafts, 17% (three of 18 eyes) were scarred, and 16% (three of 19 eyes) had failed grafts. Intensive topical steroid therapy was used when a subsequent graft rejection developed. Retained sutures following corneal transplants can result in sight-threatening infections and should be considered for removal as soon as the wound is well healed.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Corneal epithelial permeability studies using fluorophotometers were performed on 90 eyes of 51 normal subjects. After recording the autofluorescence of the cornea (AFC) and of the lens (AFL), we applied 20 µl of 2% sodium fluorescein to the conjunctival sac. The corneal fluorescence 45 min later (F45), which paralleled the corneal epithelial permeability to fluorescein, was measured by fluorophotometer and analyzed. All parameters of the two eyes of each subject correlated well with each other. There was positive correlation between AFL and patient age and between AFC and patient age (r=0.78, p<0.001, and r=0.74, p<0.001, respectively). The F45 increased exponentially with advancing age ( r= 0.67, p<0.001). The strong correlation between AFC and AFL in each eye (r=0.79, p<0.001) indicated corresponding aging processes in both the cornea and the lens. The increase in epithelial permeability with age possibly represents a subclinical breakdown of barrier function, rendering the corneas more vulnerable to insults.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

To test the effects of different frequencies of a 193-nm excimer laser on the surface smoothness of the ablated materials and the damage to the adjacent structure, four different frequencies (5, 10, 15, and 20 Hz) of a 193-nm excimer laser were used to perform ablations on 20 rabbit corneas and four polymethylmethacrylate blocks at a fluence of 160 mJ/cm2. Each frequency was tested five times on five corneas. The ablated materials were processed and examined with scanning electron microscopy (SEM) and light and transmission electron microscopy (TEM) and a Zygo interference microscope, which quantitatively evaluates the surface smoothness. The results from the Zygo microscope show that there is no statistically significant difference in surface smoothness between any two different frequencies. The SEM reveals similar regularity and uniformity on the ablated surfaces, with no relationship between the laser frequencies and the amount of surface deposits. The TEM demonstrates no correlation between the various frequencies and the thickness of the superficial pseudomembrane and the amount of collateral damage in the adjacent stroma. It appears that the higher frequencies are comparable to the lower one (5 Hz) as to ablation quality, with the benefit of curtailing surgical time and decreasing the chances of eye movement.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

The effect of topical cyclosporin A on conjunctival T cells was studied in nine patients with secondary Sjögren's disease. Patients had conjunctival biopsies performed before and after a 6-week course of topical cyclosporin. Epithelium and substantia propria in the Sjögren's patients before treatment showed significantly more CD4 + cells than specimens taken from nine age- and sex-matched controls. Following treatment with topical cyclosporin, there was a significant reduction in the number of CD4 + cells in both the conjunctival epithelium and substantia propria. Despite the fact that the treatment resulted in immunopathological improvement, the clinical benefit was not as favorable. Our results suggest that topical cyclosporin may have a local immunosuppressive effect on the conjunctiva in patients with Sjögren's disease.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Dutch-belted rabbits with corneal epithelium either intact or debrided were injected subconjunctivally with 300 µl of one of six antifungal agents: 10 mg/ml miconazole, 5 mg/ml fluconazole, 5 mg/ml ketoconazole, 2.5 mg/ml itraconazole, and 5 mg/ml amphotericin B. At intervals of 10 min to 96 h after injection, animals were killed and corneas removed at the limbus. Three vertical strips from the right cornea and four contiguous 3-mm disks trephined from the central vertical axis of the left cornea were placed on agar plates seeded with an appropriate indicator organism. After 24 h of incubation, the zones of inhibition were measured. For itraconazole, miconazole, fluconazole, saperconazole, and ketoconazole, central corneal levels peaked by 2 h in normal and debrided corneas. Little or no drug was detectable after 4-8 h, except for itraconazole, which persisted in the cornea for at least 24 h in both normal and debrided corneas. Peak levels of amphotericin B in the central cornea were achieved after 2 h in rabbits with debrided corneas, with no drug activity measured after 8 h. There were no detectable levels of drug found in the central corneas of rabbits with intact corneal epithelium. On the basis of this pilot study, the method offers a rapid approach to the screening of antifungal agents for possible use by subconjunctival injection.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

We tested the antibacterial activity of ophthalmic 0.3% ciprofloxacin against that of 5.0% cefazolin and 1.36% tobramycin in two experimental models of keratitis, using a methicillin-sensitive strain of Staphylococcus aureus and an aminoglycoside-sensitive strain of Pseudomonas aeruginosa, respectively. Both corneas of New Zealand white rabbits were intrastromally injected with either S. aureus or P. aeruginosa. Twenty-four hours later, each eye was topically treated hourly for 24 hours. In the S. aureus model, the control group received Tears Naturale Free (Alcon Laboratories, Inc., Fort Worth, TX), the ciprofloxacin group received 0.3%, ciprofloxacin and the cefazolin group received 5.0% cefazolin. In the P. aeruginosa model, the control group received Tears Naturale Free, the ciprofloxacin group received 0.3% ciprofloxacin, and the tobramycin group received 1.36% tobramycin. One hour after the last eyedrops were administered, the rabbits were killed, and their corneas were processed for quantification of bacteria. For the S. aureus model, the mean (±SEM) colony forming units (CFU) of the control, 7.1 x 106(±4.0 x 106); ciprofloxacin, 6.4 x 102(±1.6 x 102); and cefazolin, 1.3 x 103(±1.8 x 102) groups were different (F=17.5; p=0.001). The ciprofloxacin and cefazolin groups were not different from each other (p=0.034). The mean (±SEM) CFU for the control group in the P. aeruginosa model was 2.8 x 108(±1.7 x 107). All corneas in the ciprofloxacin and tobramycin groups were sterile. Short-term treatment with ciprofloxacin was an effective treatment when compared with both fortified cefazolin and fortified tobramycin in eradicating S. aureus and P. aeruginosa, respectively, in these rabbit models of bacterial keratitis.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID