Retinal 's' antigen disease in rats

The form of experimental allergic uveoretinitis induced by sensitization with retinal 's' antigen in rats actually begins as a pars planitis and juxtapapillary choroiditis. Retinal inflammation develops at the middle limiting vascular layer of the retina and extends outward with focal destruction of photoreceptors and inward as a perivasculitis of small retinal vessels. Extensive choroiditis is a late development in severely diseased animals. Significant strain differences in susceptibility to disease were observed.

Endotoxin-induced uveitis in the rat

Experimental studies of ocular inflammation induced by endotoxin have been performed almost exclusively in rabbits. Although the rat has been considered refractory to both the systemic and local effects of endotoxin, the present study has shown that intravitreal injection of endotoxin evoked a characteristic acute inflammatory response which was reproducible and dose-dependent. In addition, a consensual ocular response in the control eye occurred which was less severe but also dose-dependent. Preliminary investigations support the view that consensual responses of this nature may be mediated by a nervous reflex are mechanism. Sequential histological analysis revealed a marked polymorphonuclear cell infiltration of most ocular tissues in the early stages, while mononuclear cells predominated after 3 days. Widespread intravascular microthrombi were also observed, particularly in the ciliary vessels. Recovery, however, was usually complete by 7 days.

Experimental uveitis in isolated humoral and cellular immunity

Passive transfer of homologous immune serum in rabbits followed by intravitreous injection with the corresponding antigen resulted in an uveal inflammation which resembled the Arthus-type reaction. Clinically and histologically, the reaction was maximal 24 h after antigen injection. The histologically observed cell infiltration consisted predominantly of polymorphonuclear leukocytes. Passive transfer of sensitized homologous thymocytes followed by intravitreous injection with the corresponding antigen resulted in an uveal inflammation which resembled the delayed-type hypersensitivity reaction. Tissue infiltration of polymorphonuclear cells as well as mononuclear cells occurred predominantly during the first day following antigen injection. An exudate containing almost exclusively eosinophils was present in the aqueous humor and/or vitreous body of most of these rabbits. During the second day an increase in the ratio monomuclear cells/polymorphonuclear cells could be observed.

Inflammatory effects of endotoxin-like contaminants in commonly used protein preparations

Protein preparations from commercial suppliers are contaminated with bacterial endotoxins. The continued use of these preparations indicates that many researchers are unaware of this, and they may attribute all observed effects to the proteins themselves. Intravitreous injection of bovine serum albumin has an initial inflammatory effect on the rabbit eye which occurs before an immune reaction to the antigen itself can develop. This direct inflammatory effect can be fully accounted for by endotoxin-like contaminants which are present in protein preparations obtained from commercial suppliers. A pharmaceutical (U.S. Pharmacopeia) serum albumin preparation contains no detectable endotoxin, and has no initial inflammatory effect on the eye. Since endotoxins, even in minute amounts, have a variety of effects, the use of such contaminated protein preparations in biological research can lead to erroneous conclusions and should, therefore, be avoided.

The ocular anti-inflammatory action of imidazole

Imidazole administered intraperitoneally to albino rabbits at a dose of 250 mg. per kilogram inhibited the rise of aqueous humor protein concentration by approximately 50 per cent 30 minutes after paracentesis. Systemic imidazole administered daily to albino rabbits injected with intravitreal Shigella endotoxin decreased the conjunctival and iris hyperemia and reduced the anterior chamber cell and flare and the haziness of the optical media. Systemically administered imidazole had no effect on the aqueous humor concentrations of c-AMP or c-GMP in the rabbit. In vitro studies of rabbit ciliary body-iris phosphodiesterase activity indicated no effect of imidazole at a concentration of 10(-3) molar.

Mechanism of steroid action in ocular inflammation: Inhibition of prostaglandin production

Prostaglandin E (PGE) concentration the aqueous humor of an intact rabbit eye was less than 0.1 ng. per milliliter and increased to 19 +/- 3 ng. per milliliter 60 minutes following paracentesis. The rise in PGE level was associated with clinical signs of ocular inflammation. Pretreatment with triamcinolone reduced both the accumulation of PGE in the aqueous humor and the inflammatory response following paracentesis. intravitreal injection of E. coli endotoxin into rabbit eyes increases PGE level in the anterior chamber to 72 +/- 17 ng. per milliliter and induced acute uveitis. slices of iris and ciliary body (ICB) derived from either rabbit eyes with endotoxin-induced uveitis or normal eyes were incubated for 60 to 240 minutes and the rate of PGE release into the medium was measured by radioimmunoassay. after a 4 hour incubation, the PGE release from inflamed ICB was threefold higher than that of normal ICB. incubation of inflamed ICB with hydrocortisone, or Millicorten (100 mug per milliliter) for 4 hours reduced PGE accumulation in the medium by 50 and 81 per cent, respectively. Aldosterone had no effect on the rate of PGE release from inflamed ICB throughout the incubation period. Hydrocortisone or Millicorten also reduced PGE tissue content of inflamed ICB by about 74 per cent during the period of incubation. Indomethacin (100 mug per milliliter) abolished PGE accumulation. The suppressive action of hydrocortisone on PGE release into the incubation medium was prevented by the addition of arachidonic acid (2 mug per milliliter), a substrate for prostaglandin synthesis. By contrast , the inhibitory action of indomethacin was not affected by provision of arachidonic acid. We suggest that glucocorticosteroids reduce PGE accumulation by limiting the availability of the substrate for prostaglandin biosynthesis and thus suppress the inflammatory response.

Positive FTA-ABS tests in subjects with corticosteroid-induced uveitis

Of 17 subjects who developed severe anterior nongranulomatous uveitis during or immediatelyy after testing with topical corticosteroid preparations, 14 (82%) had a positive fluorescent-treponemal-antibody absorption (FTA-ABS) test. No association was found between corticosteroid-induced uveitis and any specific HL-A locus.

Ara-A and IDU therapy of human superficial herpetic keratitis

Ara-A ointment was compared to IDU ointment in patients with dendritic herpes simplex virus infection of the corneal epithelium. Twenty-eight patients were treated with Ara-A ointment and twenty-four with IDU ointment. The lesions healed in 5.1 days with Ara-A and in 6.9 days with IDU. This drug was given in a double-controlled manner, so that neither the patient, nor the investigator knew which drug the patient was receiving. The patient groups were comparable as to length of the dendritic lesion and duration of symptoms. The adverse reactions to each of these drugs were comparable and in no case was there any permanent ocular change from drug use.

Prevention of experimental allergic uveitis. Treatment and methotrexate

These experiments were undertaken to determine if methotrexate therapy, initiated after immunization, could prevent the development of experimental allergic uveitis. Strain 13 guinea pigs were immunized with Strain 13 guinea pig retina-uvea extract that had been emulsified in Freund complete adjuvant. Some were treated with methotrexate twice a week until the 21st day. Each week, all of their eyes were examined with a slit-lamp. At the end of the study, some were skin tested, and the sera of selected animals were tested by immunodiffusion for antibody. The eyes of certain groups were examined histologically. Results show methotrexate prevented the development of this type of uveitis, even when therapy was initiated seven days after immunization. The disease did not appear after therapy was stopped. Methotrexate also inhibited the development of skin sensitivity and antibody to retina-uvea antigen.

Vitreous substitution with gases

The effects of vitreous substitution with air, a sulfur hexafluoride-air mixture, an octafluorocyclobutane-air mixture, and physiological saline were compared in owl monkeys. Each gas caused an increase in ocular vascular permeability greater than that caused by saline, as measured by vitreous inflow of serum protein labeled with iodine I 131 and discgel electrophoresis. The duration of increased vascular permeability closely paralleled the time each gas remained in the vitreous cavity.

Untoward effects associated with practolol administration: oculomucocutaneous syndrome

Keratoconjunctivitis sicca, conjunctival scarring, fibrosis, metaplasia, and shrinkage developed in 27 patients as an adverse reaction to practolol. Rashes, nasal and mucosal ulceration, fibrous or plastic peritonitis, pleurisy, cochlear damage, and secretory otitis media also occurred in some cases. Three patients suffered profound visual loss though most retained good vision. Symptoms and signs improved on withdrawal of the drug, but reduction of tear secretion persisted in most patients.