Kaj Mahlberg

Serum antibody level to S-antigen in children with chronic uveitis.

Bovine S-antigen was purified by gel filtration and ion exchange chromatography according to previously described techniques. An enzyme linked immunosorbent assay (ELISA) using antiserum to bovine S-antigen raised in guinea-pigs was employed to detect S-antigen in the chromatographic fractions. The purity of the S-antigen was determined by SDS-PAGE electrophoresis, where a single band was found. The purified S-antigen in microgram quantities together with Freunds complete adjuvant induced uveitis in rats two weeks after injection into the foot pad. Serum samples from children suffering from chronic uveitis and healthy children were tested for antibodies to S-antigen by the ELISA. A statistically significant difference in the level of specific antibodies between patients and controls was found. There was no clear-cut correlation between the severity of uveitis and antibody titre, but cases with retinal involvement and aggressive uveitis all showed definite elevations of antibodies to S-antigen.

Prevention of experimental corneal allograft rejection in rabbits using cyclosporin-collagen shields

Topical administration of cyclosporin A, a highly hydrophobic cyclic undecapeptide, has been relatively ineffective in preventing corneal allograft rejections due to poor drug penetration. Therefore, we investigated a new continuous-delivery system for cyclosporin A using collagen bandage shields fabricated from porcine scleral tissue. Collagen bandage shields containing 4 mg cyclosporin A were used for the treatment of four corneal allografts embedded in prevascularized rabbit corneas. Four controls were treated with shields containing no cyclosporin A. The shields were changed every 2nd day and signs of rejection were recorded. All controls were rejected by the end of the experiment. Treatment with collagen shields containing cyclosporin A effectively prevented such rejection. The clinical examinations were also confirmed with histopathological analysis. The results indicate that collagen shields can slowly release cyclosporin A and increase the penetration time for the drug. Thus, they are excellent delivery systems for hydrophobic drugs with poor penetration properties.

Use of collagen shields in cataract surgery

Abstract A randomized, prospective, multicenter study evaluated the efficacy and safety of using collagen shields to deliver drugs after cataract surgery. Collagen shields saturated with an antibiotic and a steroid were placed in 90 eyes postoperatively. A control group of 93 eyes received the same drugs through a peribulbar/retrobulbar injection. One day after surgery, the shield group had significantly less corneal edema, conjunctival hemorrhaging, and postoperative pain and fewer corneal opacities. All symptoms except the conjunctival hemorrhaging disappeared by day seven. Our study suggests that using collagen shields for drug delivery after cataract surgery decreases tissue damage and increases patient comfort without adverse side effects.

Prevention of high risk corneal graft rejection using cyclosporine a (CSA) incorporated into a collagen matrix

The aim of this work was to compare the efficacy of cyclosporine (CsA) collagen shields and fragments in suppressing experimental allograft rejection in an animal model for high risk keratoplasty. Altogether 23 experimental animals were treated either with plain collagen shields, oral cyclosporine, collagen CsA shields, or with CsA collagen fragments after corneal transplantation (PKP) in previously vascularized corneas. The study medications were started immediately following PKP. For these animals slit lamp examinations were performed twice a week for the duration of the experiment and the signs of corneal rejection were observed. The animals were followed until an irreversible rejection or until the end of the experiment (14-149 days). The inflammation of the graft was also evaluated histologically when animals were sacrificed. The grafts treated with plain collagen shields all were rejected within 36 days, and the mean graft survival time for these corneas was 25 days. Five transplants that were treated with oral CsA had better survival, and two of five grafts stayed clear until postoperative day 119, when the treatment was stopped. The best graft survival was seen in grafts treated with CsA collagen fragments and all these stayed clear up to 77 days postoperatively. The treatment of the grafts with CsA collagen shields was almost as effective as with CsA fragments, and first signs of rejection appeared as late as nine weeks postoperatively in two of seven grafts. The other of these rejected corneas were later treated with CsA collagen fragments and showed a dramatic improvement in transparency of the cornea and disappearance of inflammation of the graft. The discontinuation of study medication caused an irreversible rejection to appear in a previously clear graft that had been treated successfully with any study medication. We conclude that topical CsA in shields or in fragments will provide a significant advance over systemic CsA alone, and that CsA fragments appear to be as effective as shields in preventing corneal allograft rejection.

Correlation between histopathological, clinical and biochemical parameters in S-antigen-induced experimental autoimmune uveitis in guinea-pigs**

Footpad immunization with purified bovine retinal S-antigen in complete Freunds adjuvant was used to induce experimental allergic uveitis in 32 guinea-pigs. Thirteen animals immunized only with complete Freunds adjuvant were used as controls. Ninety-three point seven per cent of the animals immunized with S antigen developed clinical experimental allergic uveitis while none of the controls had any clinical manifestation of uveitis. Histopathological analysis in the experimental group revealed mono- and polymorphonuclear cell infiltration in the choroid, ciliary body and iris. Simultaneous disruption of the outer segment of photoreceptor cell layer was also noticed. For the anterior segment of the eye there was a strong correlation between the histopathological grading and the clinical grading. For the posterior segment this correlation was, however, poor. Histopathological changes in the eye were correlated with the clinical grading and biochemical parameters (phospholipase A2, prostaglandin E2, leukotriene C4, proteins and myeloperoxidase) measured from aqueous humour, serum samples and ciliary body-iris homogenate. Protein and phospholipase A2 levels in the aqueous humour correlated well with the histological grading of the anterior segment of the eye. The myeloperoxidase activity, measured from ciliary body-iris homogenate, also correlated with the inflammatory cell infiltration in the anterior segment. Leukotriene C4 and prostaglandin E2 levels in aqueous humour did not correlate with the histopathological, or with the clinical grading, although elevated mean values were recorded in eyes having uveitis. Gamma glutamyl transpeptidase, measured in the serum, had a poor correlation with the histological grading for the anterior segment. All other parameters, measured in serum, did not correlate with the histopathological or the clinical grading. Histopathological changes in the anterior uvea are thus reflected by elevated protein and phospholipase A2 levels in aqueous humour as well as by myeloperoxidase activity in ciliary body-iris homogenate.

Compatibility of corticosteroids and antibiotics in combination

Purpose: To study the compatibility of combinations of antibiotics and steroids commonly used in anterior segment surgery. Setting: Research Laboratory, Helsinki University, Finland. Methods: Aggregate production in vitro and in vivo was studied for three injectable antibiotics (cefotaxime sodium, tobramycin sulfate, and gentamicin) and four corticosteroids (triamcinolone acetonide, methylprednisolone sodium succinate, methylprednisolone acetate, and dexamethasone sodium phosphate) using conventional and dark‐field microscopy. Aggregate formation on collagen shields and subconjunctival aggregate formation of tobramycin sulfate in combination with methylprednisolone acetate or dexamethasone sodium phosphate was also studied. Results: Dexamethasone sodium phosphate (4 mg/mL) did not form aggregates with any of the three antibiotics tested. Cefotaxime sodium did not cause aggregates when 24 mg/mL of dexamethasone sodium phosphate was used both in vitro and in vivo or in association with collagen shields. Conclusions: To avoid undesired side effects, such as epithelial sloughing and corneal edema after collagen shield application, antibiotics and steroids must be carefully selected.

Systemic cyclosporin treatment for high-risk corneal transplantation

The success rate for uncomplicated penetrating keratoplasty is very high. However, in high risk patients there is a significantly increased risk for immunologic graft failure and the success rate is relatively poor. Oral cyclosporin A treatment has dramatically decreased the rejection rate in solid organ transplantation. Its oral use in ophthalmology has so far been relatively limited and topical use restricted by poor penetration of the drug into ocular tissues. The favorable results of oral cyclosporin treatment to prevent corneal graft failure in high-risk patients is demonstrated in this study. High-risk corneal transplant patients were selected from the general population scheduled to undergo corneal transplantation. Twenty-two of 277 patients who were operated during a four-year period were regarded as high-risk keratoplasty patients. Systemic cyclosporin A treatment (5mg/kg/day) was given prophylactically to 14 of these patients who were considered to be at high-risk for keratoplasty rejection (CsA group). In addition the patients received a low dose of corticosteroids. Eight similar patients receiving high dose corticosteroids served as a control group (control group). In the CsA group graft survival was 78.6% compared with 37.5% in the control group at 1.5 years. The grafts of patients receiving CsA had a significantly better survival rate (p.o5) than those in control at one and 1.5 years. On the follow-up to four years graft survival in patients treated with CsA was, however, decreasing to 35.7%. The low graft survival in both high-risk groups is in great contrast to graft survival in all patients operated during the same period (93.1%). Systemic cyclosporin treatment when received at the time of the operation is effective in reducing failure from irreversible rejection in high-risk keratoplasty, but for maximal effect, a six-month period of treatment is too short. Subjective side effects were frequent but still acceptable. Blood tests did not reveal any pathological hepatic or renal laboratory values caused by system CsA administration. Careful and frequent follow-ups of the patients are however needed.