Urine leukotriene B4 in familial Mediterranean fever.

OBJECTIVE: To determine urinary leukotriene B4 (LTB4) levels and their role in FMF: METHODS: Urinary LTB4 levels were studied using a commercial ELISA kit in 12 FMF patients during abdominal attacks, and 20 FMF patients during remission. RESULTS: Urinary LTB4 levels in FMF patients during attacks were comparable to those during remission, but higher than normal levels (p = 0.03). CONCLUSIONS: These findings suggest a persistent activation of the leukotriene pathway in FMF. Whether elevated LTB4 levels are the cause or the effect of inflammation is yet to be determined.

Ocular hypotensive effects of cholinergic and adrenergic drugs may be influenced by prostaglandins E2 in the human and rabbit eye.

PURPOSE: Increased PGE2 production by the iris and ciliary body regulate intraocular pressure (IOP) in vivo. Various cholinergic and adrenergic compounds are traditionally used as antiglaucoma drugs, and their effect on IOP reduction is antagonised by cyclooxygenase inhibitors, indicating a role for eicosanoids in their hypotensive activity. One of the most potent antiglaucoma drugs, PG2 alpha (Latanoprost), reduces IOP by increasing uveoscleral outflow and also increases PGE2 production by the iris and ciliary body in vivo. We investigated whether cholinergic and adrenergic antiglaucoma drugs induce the production of prostaglandin E2 (PGE2) in vitro by: 1) the iris-ciliary body (ICB) of rabbits and, 2) irises of glaucoma patients. METHODS: Pilocarpine 2%, epinephrine 1% and echothiophate iodide 0.125% were applied topically to both eyes of Albino rabbits. Control groups were treated with the corresponding vehicles, or untreated completely. Human iris specimens were obtained from nine untreated cataract eyes, and five eyes under antiglaucoma medication undergoing surgery. PGE2 were determined by a radioimmunoassay. RESULTS: PGE2 production by the ICB of treated rabbits in vitro was twice that of vehicle-treated or untreated rabbit eyes (p<0.001, for either group). In vitro PGE2 production by treated glaucoma patients' irises was three times higher (p<0.001) than in cataract control patients. CONCLUSIONS: The study found an increase in in vitro production of PGE2 by the irises of eyes treated with cholinergic and adrenergic antiglaucoma medications. This suggests a role for endogenous PG production in the hypotensive effect of both classes of drug.

Melanocortins are comparable to corticosteroids as inhibitors of traumatic ocular inflammation in rabbits.

BACKGROUND: Melanocyte-stimulating hormone (MSH) is a known anti-inflammatory agent and we investigated whether it reduces the inflammatory reaction following ocular surgery. METHODS: Rabbits received a perforating corneolimbal cut. Treatment involved topical (10(-8)M) or intramuscular (50 mg/kg/day) MSH, topical steroids or saline. The parameters studied were hyperemia, edema, aqueous protein levels and the number of inflammatory cells in the aqueous, as well as their number determined histologically in the injured cornea. Each parameter was assessed at 24 h post injury. RESULTS: Topically and systematically applied MSH reduced edema to levels 60% and 76%, respectively, of those observed in operated saline-treated eyes (P<0.001), and their efficacy was comparable to that of topical steroids. The decrease in hyperemia brought about by MSH was more pronounced than that produced by steroids. Aqueous protein levels were reduced by a similar degree in the steroid- and MSH-treated eyes as in the saline group (P<0.001 for each treatment group); In MSH- and ste-roid-treated eyes the number of inflammatory cells in the aqueous was reduced by 80% and 50%, respectively. CONCLUSION: We demonstrated that MSH reduced the clinical signs of ocular inflammation, curtailed blood-aqueous barrier (BAB) disruption, and reduced aqueous inflammatory cell number. The efficacy of MSH applied systemically or topically was similar to that of steroids in reducing clinical signs of trauma, but MSH efficacy in maintaining BAB integrity surpassed that of steroids. We suggest that the melanocortins might be a useful anti-inflammatory agents in ocular trauma.

Mechanism related to reduction of intraocular pressure by melanocortins in rabbits.

AIM: To investigate whether the ocular hypotensive effect of alpha melanocyte stimulating hormone (MSH) is related to eicosanoids or cyclic AMP (cAMP). METHODS: Intraocular pressure (IOP) readings were taken at a similar time on the day before and after a single dose of topical MSH. Changes in the levels of prostaglandin E(2) (PGE(2)) and prostacyclin in incubated iris ciliary body (ICB) explants were measured by specific radioimmunoassay (RIA). Incubated ICB explants were exposed to MSH or adrenaline (epinephrine) for a week. In addition, cAMP levels in the medium were determined following short term incubation using RIA. RESULTS: A significant dose related reduction in IOP was noted with topical MSH (mean (SD) maximal effect 4.5 (0.1) mm Hg (21%); p<0.001 v appropriate baseline) which persisted up to 6 hours (p=0.05). MSH treated ICB explants showed a 1.5-fold increase in PGE(2) and prostacyclin levels (p<0.001 for each parameter) while cAMP levels were increased twofold (p<0.001). CONCLUSIONS: A single application of MSH caused a sustained dose related ocular hypotensive effect with no side effects. An increase in eicosanoid and cAMP levels following ICB exposure to MSH indicated their involvement in MSH induced ocular hypotension. MSH and its analogues might have clinical relevance as antiglaucoma drugs with fewer side effects because of their antiallergic and anti-inflammatory properties.

Lipoxygenase metabolism following laser induced retinal injury in rabbits.

PURPOSE: 1) to investigate whether leukotriene B(4) (LTB(4)) is a factor in the inflammatory reaction following chorioretinal laser injury in rabbits; 2) to study its relationship with the cyclooxygenase (COX) metabolic pathway; 3) to study the influence of Nordihydroguaiaretic acid (NDGA), an inhibitor; of the lipoxygenase (LOX) cascade, on both COX and LOX metabolism. METHODS: Prostaglandin E(2) (PGE(2)) and LTB(4) synthesis by incubated samples of chorioretina obtained from rabbits' eyes exposed to Neodymium:Yag laser along with these eicosanoids accumulation in the vitreous were measured over one week follow-up period. The effect of NDGA pre-treatment on the COX and the LOX pathways in the laser-injured chorioretina was also assessed. PGE(2) and LTB(4) levels in the vitreous and in the chorioretina incubation medium were quantified using the radioimmunoassay technique with the appropriate antibodies. RESULTS: LTB(4) in vitro production by rabbits' chorioretina subjected to ND; YAG laser was significantly elevated compared to control, peaking on day 7 to levels 2.45 fold greater than baseline (p < 0.01). PGE(2) formation, following a different pattern, was also enhanced and its maximal level (5.2 fold higher than control, p < 0.01) was achieved at the initial phase (day 1 post laser). Laser irradiation caused also an increase in the two eicosanoids accumulation in the vitreous, which was however not proportional to their production levels. NDGA treatment was associated with a sustained decrease in LTB(4) content in the vitreous, but had no effect on PGE(2) vitreal levels. CONCLUSIONS: Laser irradiation of the rabbits' retina induces an alteration in the LOX metabolic pathway, which is dissociated from the influence on the COX cascade, pointing for the first time to a possible role played by LTB( 4) as a mediator in the chorioretinal inflammatory reaction, with no connection to the role played by PGE(2). NDGA selectively inhibited LOX activity without affecting COX activity.

A submicron emulsion of HU-211, a synthetic cannabinoid, reduces intraocular pressure in rabbits.

PURPOSE: To study the ocular hypotensive effect of a nonpsychotropic cannabinoid, HU-211 (11 -hydroxy-delta8-tetra-hydrocannabinol, dimethylheptyl), an N-methyl-D-aspartate (NMDA) agonist, in normotensive rabbits. METHODS: The cannabinoid HU-211, being lipophilic, was incorporated into a stable oil-in-water submicron sterile emulsion, consisting of 0.12% (w/w) HU-211. A single- dose, randomized and double-masked study was designed, using a Digilab 30R pneumotonometer to measure intraocular pressure (IOP) in normotensive rabbits. RESULTS: Application of a single dose of HU-211 ophthalmic preparation resulted in an IOP reduction of 5.3 mmHg (24% of baseline), first evident at 1.5 h post application and persisting for over 6 h. A small but significant lowering of pressure (12.5% of baseline) occurred in the contralateral eyes of HU-211 treated rabbits, lasting for 4 h post treatment. CONCLUSION: Our work demonstrated that HU-211, incorporated into submicron emulsion, caused a 6-h-long reduction in IOP in the treated eye, with a lesser reduction in the contralateral untreated eye.

Angiogenic activity of vitreous extract obtained from rabbit eyes with endotoxin-induced uveitis.

The effect of rabbit vitreous with endotoxin-induced uveitis was investigated for its role in the modulation of rat corneal neovascularization (NV). Elvax pellets implanted into at cornea contained either uveitic vitreous, intact vitreous or Elvax alone. The latter two kinds of pellets did not elicit NV. Uveitic vitreous pellets caused, in 100% of eyes, a persistent NV with maximal growth on the 10th day post implantation. Prostaglandin E2 and leukotriene B4 levels in the uveitic rabbit vitreous at 36 h postendotoxin injection were 7- and 5-fold higher than baseline, respectively. Histopathologically, the neovascularized cornea showed a significant inflammatory reaction attributable to the uveitic vitreous extract.

Early and late postoperative application of 5-fluorouracil following trabeculectomy in refractory glaucoma.

Intraocular pressure (IOP) control was studied retrospectively in two groups of 14 consecutive patients following trabeculectomy with adjunctive postoperative 5-fluorouracil (5-FU) treatment. In one of the groups (the early-treatment group), 5-FU injections were started 2.4 +/- 0.6 days postoperatively; in the other group (the delayed-treatment group), they were started only when clinical signs suggested impending bleb failure (12.6 +/- 5.4 days postsurgery). The patients in the two groups were age-matched and had a similar history of previous failed glaucoma operations or diabetes, both of which are considered indications for postoperative 5-FU injections. The mean number of 5-FU injections and the total dose in the two groups did not differ significantly (5.3 +/- 0.8 and 5.5 +/- 1.1 injections, respectively; 26.4 +/- 3.9 and 27.5 +/- 5.3 mg 5-FU total dose, respectively). The average follow up for the two groups was 16.7 +/- 2.5 and 16.9 +/- 2.7 months, respectively. With an IOP of 18 mm Hg or less with or without medications considered a success, 42.8% of the delayed-treatment and 71.4% of the early-treatment cases were successful. More medications were required in the early-treatment group. Postoperative transient corneal epithelial defects occurred in 71.4% and 78.4% of the eyes in the late- and early-treatment groups, respectively, an insignificant difference. Conjunctival wound leak occurred in one patient (in the delayed-treatment group).(ABSTRACT TRUNCATED AT 250 WORDS)

Pilocarpine incorporated into a submicron emulsion vehicle causes an unexpectedly prolonged ocular hypotensive effect in rabbits.

Pilocarpine, a widely used antiglaucoma drug, was incorporated into a newly developed submicron emulsion (pilocarpine emulsion) suitable for local ocular administration. Pilocarpine-Emulsion effect on the intraocular pressure (IOP) was studied following a single dose application in normotensive rabbits. Membrane filtration (steam autoclaving) was found not to affect particle size distribution, zeta potential or pH of the pilocarpine emulsion preparation. A single dose application of pilocarpine emulsion 1.7% (equivalent to 2% pilocarpine hydrochloride) induced a prolonged progressive decrease in IOP in normotensive rabbits, which started at eleven hours post instillation and reached its maximal value of 6.0 +/- 0.2 mmHg at 29 hours. The pressure decreasing effect induced by pilocarpine emulsion treatment followed a pattern different from that generated by generic pilocarpine (Pilocarpine Hydrochloride 2% eye drops); In the latter group, IOP reduction (starting at two hours) persisted during the initial five hours post-instillation, while in the former, the hypotensive effect started at a later stage, and was maintained during a twenty nine hour follow-up causing a greater IOP decrease than in the generic group (% delta IOP of 28.5% and 18%, respectively). In the contralateral eyes of Pilocarpine Emulsion treated rabbits, an ocular hypotensive effect was noted late after application (11 hours through 29 hours post-instillation), while this effect was negligible in rabbits-treated with aqueous pilocarpine. Our findings point to the possibility that the novel preparation of pilocarpine incorporated into submicron emulsion might serve as a long-acting form of pilocarpine which might require a single daily application. Further studies are required to elucidate the mechanism and action of this preparation.

Levels of prostaglandin E2 and leukotriene B4 in tears of vernal conjunctivitis patients during a therapeutic trial with indomethacin.

A therapeutic trial of 1% indomethacin (Indoptic) eye drops was carried out in 21 children. Looking for possible mediators of inflammation in vernal conjunctivitis, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4 levels in the tears of 9 patients were measured and the effect of the treatment on them examined. A control group of 10 unaffected children was added. Out of 42 eyes in which indomethacin treatment was instilled, only 17 remained in treatment through a 6-week follow-up period. In a few of them a moderate improvement was obtained. The mean level of PGE2 in the patients before treatment was found to be slightly lower than that in the control group, and it dropped even lower during treatment. The average LTB4 level found in patients before treatment was significantly higher than the control group; it decreased somewhat following treatment, but not significantly. This is the first report of elevated LTB4 levels in vernal conjunctivitis, previously not recorded in the literature, it points to the possible role of LTB4 in the pathogenesis of the disease. A constant relationship was observed between low PGE2 levels and high LTB4 content in the patients' tears during highly inflamed states of the eye. We conclude that: (a) indomethacin did not prove to be a highly effective topical treatment for vernal conjunctivitis; (b) PGE2 does not seem to be a dominant mediator of inflammation in this disease; and (c) LTB4, on the other hand, apparently has a role in the mechanism of inflammation of the disease, thus raising hopes for future addition to therapy.

Alpha melanocyte stimulating hormone (alpha-MSH) enhances eicosanoid production by bovine retinal pigment epithelium.

Explants of bovine eyes consisting of retina, with its underlying choroid and sclera (termed retinal explants) were maintained in organ culture in the absence or presence of alpha-melanocyte stimulating hormone (alpha-MSH) for up to 19 days. The conditioned media was collected twice a week and assayed for the following eicosanoids, prostaglandin E2 (PGE2) and prostacyclin. The addition of alpha-MSH to the incubation media resulted in a 1.5 fold enhancement in the production of both PGE2 and prostacyclin. This stimulatory effect diminished after 11 days. Additionally, the three tissue components comprising the retinal explants i.e. 1. neural retina 2. retinal pigment epithelium (RPE) with its underlying vascular layer (choroid) and 3. scleral tissue were separated and incubated in the presence or absence of alpha-MSH. Hormone treatment caused an enhanced eicosanoid production by RPE tissue alone, while its production by the neuronal retina and sclera was reduced or unaffected respectively. This demonstrates that the RPE layer is the source for the alpha-MSH induced eicosanoid production observed in the whole retinal explant. Our findings demonstrate, for the first time that alpha-MSH can stimulate prostaglandin production by RPE maintained in organ culture.

A quantitative in vitro model for silicone oil emulsification. Role of blood constituents.

To understand why some patients seem to be protected from emulsification and others are not, the authors developed an in vitro model for quantitative analysis of silicone oil emulsification. The pro-emulsifying potential of substances and blood components that may have access to the vitreous cavity in a patient's eye was analyzed. In this model, red blood cell ghosts had the highest emulsifying effect; plasma and lymphocytes also had a significant emulsifying effect. Phospholipids in membranes and other soluble blood components may play important roles in this process. These results suggest the importance of avoiding and removing hemorrhage and avoiding inflammation when silicone oil is used in vitreoretinal surgery.

Anterior capsule adherence to iris leading to pseudophakic pupillary block.

We present a rare case of anterior capsule adherence to the iris following extracapsular cataract extraction with posterior chamber intraocular lens implantation and leading to pseudophakic pupillary block. There were no synechiae at the pupillary margins associated with the capsule/iris adherence, but aqueous was entrapped behind the iris and intraocular pressure rose. Laser iridotomy was temporarily beneficial, but it had to be repeated several times.

Identification, prevention, and treatment of silicone oil pupillary block after an inferior iridectomy.

We treated two patients in whom silicone oil pupillary block developed despite a patent inferior iridectomy. The clinical characteristics of this complication were a deep anterior chamber, specular reflexes from the iris surface, identification by biomicroscopy of aqueous trapped inferiorly in the vitreous cavity, and no convection currents in the anterior chamber. This complication may be prevented by early face-down positioning of the patient after the operation, and the avoidance of large, centrally located, inferior iridectomies. We recommend that the iridectomy be placed peripherally no larger than 2 mm and propose a new technique for breaking the silicone oil block, which was clearly successful in one of the patients.

Argon laser irradiation of rabbits' eyes-changes in prostaglandin E2 levels.

Laser irradiation of the eye is a widely used therapeutic measure in various ocular disorders. We investigated in laser-treated rabbits' eyes the changes in prostaglandin E2 (PGE2) levels of the tissue affected by the laser (the retina/choroid) and of its adjacent vitreous over a two-week period. The parameters studied were; PGE2 in vitro production by the retina/choroid, as well as PGE2 and protein levels in the vitreous, the latter indicative of a break in the blood retinal barrier (BRB). The effect of noncoherent light exposure used for illumination, and that of the mechanical manipulation involved (sham exposure) were also studied. Following laser exposure vitreal PGE2 levels were increased two-fold above baseline (days three and 14), whereas light exposure resulted in a single peak. PGE2 in vitro production by the retina/choroid in the laser-exposed group was elevated throughout the observation period, peaking twice (days 3 and 14), in the light-exposed group the enhanced production was evident during a shorter period, whereas in the sham group it remained unchanged from baseline. An elevation in vitreal protein levels to above baseline levels occurred in both the laser- and, to a lesser degree, in the noncoherent light-exposed groups, but not in the sham group. Our study demonstrated an enhanced PGE2 in vitro production by retina/choroid of laser-exposed eyes, which might be attributable to the additive effect of the laser induced trauma, and the noncoherent light photochemical changes; the clinical significance of the recurrent increase in vitreal PGE2 levels in laser-treated eyes might be related to its anti-inflammatory properties.

Prolonged corticosteroid treatment exerts transient inhibitory effect on prostaglandin E2 release from rabbits' eyes.

In humans, the retina and choroid (the photoreceptor and its vascular layers, respectively), are affected by an immunogenic inflammatory reaction--uveitis, associated with excessive levels of prostaglandin E2 (PGE2), and treated for prolonged periods with corticosteroids, known for their inhibitory effect on prostaglandins (PGs) production. In order to assess whether this drug retains its inhibitory effect during chronic use, we investigated the effect of long-term systemic administration of corticosteroids on PGE2 release by the choroid and retina of rabbits' eyes. We used eyes traumatized by laser irradiation, in which the inflammatory reaction is associated with an enhanced PGE2 in vitro release by the choroid-retina throughout a 2-week period; levels peaked on days 1 and 7 to values 2.2- and 5.5-fold, respectively, greater than baseline. Systemic corticosteroid administration to laser-exposed rabbits curtailed the excessive PGE2 release during the first post-laser week; later the amounts released progressively increased to levels 5.5-fold higher than baseline (day 14), whereas in the corresponding untreated laser group, levels were significantly lower. PGE2 tissue content on days 7 and 14 in steroid-treated and untreated laser groups were similarly elevated. We conclude that during prolonged systemic corticosteroids treatment the steroidal inhibitory effect on enhanced PGE2 formation by the retina-choroid of laser injured eyes is transient; it is evident during the early phase following drug administration, whereas later excessive PGE2 release is resumed.

Subthreshold argon-laser irradiation elicits a pronounced vitreal prostaglandin E2 response.

Chorioretinal production of prostaglandin type E2 (PGE2) as well as changes in vitreal protein and PGE2 concentrations were studied following retinal irradiation with low-power laser energy that caused ophthalmoscopically invisible ("subthreshold") laser burns. This was compared with changes following ophthalmoscopically visible ("suprathreshold") laser burns. Our results demonstrate that with in eyes exposed to the lower-power levels, the enhancement in vitreal PGE2 concentration persisted for a longer period and was more pronounced than in eyes exposed to the suprathreshold levels (a 3-fold and a 2-fold increase above baseline values, respectively). Protein leakage into the vitreous was noted only in the suprathreshold group, indicating a blood-retinal barrier (BRB) disruption. The findings of persistent, excessive PGE2 vitreal levels with no protein leakage in the subthreshold group suggest a possible anti-inflammatory role for PGE2 following low-power laser exposure.

Prostaglandin E2 changes in the retina and optic nerve of an eye with injured optic nerve.

Changes in arachidonic acid metabolism were studied in the optic nerve, the chorioretina, and in the vitreous following crush injury to the optic nerve of rats. Crush injury led to: (i) a 3.9-fold increase in optic nerve prostaglandin type E2 in vitro production which peaked on day 5 and was followed by a gradual decline, but was still significantly higher than baseline levels by day 12; (ii) a two-fold increase in the chorioretina prostaglandin type E2 in vitro production which peaked on day 1, and resumed baseline levels by day 3; (iii) a 3.5-fold increase in vitreous prostaglandin type E2 levels on day 1 which remained at 1.5-2 times higher than baseline levels for the rest of the study period (12 days). The findings indicate that the pattern of changes in prostaglandin type E2 production by the optic nerve (consisting mostly of white matter) is different from that described for injured brain tissues. The prolonged accumulation of vitreal prostaglandin type E2 in eyes with damaged optic nerve may lead to undesirable effects on the retina beyond those directly manifested in the retina by altered axonal flow in the injured optic nerve.