Recombinant tissue plasminogen activator injected into the vitreous cavity may penetrate the retinal veins of a porcine model of vascular occlusion

AIM

To determine if recombinant tissue plasminogen activator (rtPA) injected into the vitreous cavity can penetrate the retinal vessels of porcine eyes with or without vascular occlusion.

METHODS

Eight eyes (group I) of four pigs underwent clamping of the optic nerve flush with the globe for 90 minutes. One hour after reperfusion, one eye of each pig was injected with 75 microg of rtPA, and the fellow eye was injected with balanced salt solution (BSS). Eyes were processed for immunohistochemistry. Four additional eyes (group II) of two pigs were subjected to the same injections, but without optic nerve clamping.

RESULTS

After reperfusion, the clinical picture was similar to that of a central retinal vein occlusion. Immunoperoxidase staining showed rtPA only in the retinal veins but not the retinal arteries in all eyes injected with rtPA in both groups I and II. Those eyes also showed intense rtPA staining at the level of the internal limiting membrane (ILM). No staining was seen at the level of the ILM or inside the retinal vessels in the BSS injected eyes. Immunofluorescence staining showed intense staining at the level of the ILM, but not inside the retinal vessels in the rtPA-injected eyes.

CONCLUSIONS

rtPA may penetrate the retinal veins, but not the arteries of porcine eyes with and without vascular occlusion. The ILM may play a part in preventing rtPA penetration.

Unexpected autopsy findings arising from postmortem ocular examination

BACKGROUND

A full autopsy at our institution includes removal of the eyes for pathologic examination. To our knowledge, the rate of ophthalmic findings at autopsy has not been documented previously.

DESIGN

We retrospectively reviewed 277 consecutive autopsies conducted between 1995 and 1999 in which the eyes were removed for examination. Ophthalmic findings were placed in the following categories: I, major findings included those that contributed to the patient's death, would have changed patient management, and/or may have important medical implications for close relatives; II, expected findings after ophthalmologic surgery and minor findings that may have eventually required treatment; and III, incidental findings.

RESULTS

Major findings (category I) were found in 32% of autopsies. Minor findings (category II) and incidental findings (category III) were documented in 62% and 34% of autopsies, respectively. Only 14% of autopsies revealed no ophthalmologic diagnoses.

CONCLUSION

In our series, postmortem ocular examination revealed a number of important findings, including several heritable and rare conditions. Eighty-six percent of autopsies disclosed at least one pathologic ophthalmologic finding, approximately one third of which demonstrated findings significant enough to have likely required management. Diabetic retinopathy was the most frequent major finding. Malignant melanoma of the choroid was the most commonly found intraocular neoplasm. Chronic uveitis was the most common minor finding. We conclude that important, often unexpected ophthalmic findings are frequently encountered at autopsy, underscoring the relevance of routine postmortem examination of the eyes.

Preoperative mobilization of circulating dendritic cells by Flt3 ligand administration to patients with metastatic colon cancer

PURPOSE

To evaluate preoperative dendritic cell (DC) mobilization and tumor infiltration after administration of Flt3 ligand (Flt3L) to patients with metastatic colon cancer.

PATIENTS AND METHODS

Twelve patients with colon cancer metastatic to the liver or lung received Flt3L (20 microg/kg/d subcutaneously for 14 days for one to three cycles at monthly intervals) before attempted metastasectomy. The number and phenotype of DCs mobilized into peripheral-blood mononuclear cells (PBMCs) were evaluated by flow cytometry. After surgical resection, metastatic tumor tissue was evaluated for DC infiltration. In vivo immune responses to recall antigens were measured.

RESULTS

After Flt3L administration, on average, the total number of leukocytes in the peripheral blood increased from 5.9 +/- 1.0 x 10(3)/mm(3) to 11.2 +/- 3.8 x 10(3)/mm(3) (mean +/- SD, P: =. 0001). The percentage of CD11c(+)CD14(-) DCs in PBMCs increased from 2.4% +/- 1.8% to 8.8% +/- 4.7% (P: =.004). Delayed-type hypersensitivity (DTH) responses to recall antigens (CANDIDA:, mumps, and tetanus) showed marginally significant increases in reactivity after Flt3L administration (P: =.06, P: =.03, and P: =.08, respectively). An increase in the number of DCs was observed at the periphery of the tumors of patients who received Flt3L compared with those of patients who had not.

CONCLUSION

Flt3L is capable of mobilizing DCs into the peripheral blood of patients with metastatic colon cancer and may be associated with increases in DC infiltration in the peritumoral regions. Flt3L mobilization is associated with a trend toward increased DTH responses to recall antigens in vivo. The use of Flt3L to increase circulating DCs for cancer immunotherapy should be considered.

8(S)-hydroxyeicosatetraenoic acid is the lipoxygenase metabolite of arachidonic acid that regulates epithelial cell migration in the rat cornea

BACKGROUND

We previously found that the inhibition of lipoxygenases resulted in delayed epithelial wound closure in organ-cultured rat corneas. The present study was undertaken to determine the lipoxygenase enzyme and metabolite(s) responsible for regulating reepithelialization and their mechanism of action.

METHODS

The effects of esculetin--an established lipoxygenase inhibitor--on endogenous hydroxyeicosatetraenoic acids (HETEs) production, epithelial wound closure, filamentous-actin (F-actin) cytoskeleton, and mitotic rate were investigated using a cell-culture assay and an organ-culture assay of rat corneal epithelium.

RESULTS

Lipoxygenase inhibition by esculetin, which resulted in the disruption of F-actin organization and a decrease in the mitotic rate, delayed wound closure in both cell- and organ-culture assays. Normal corneoscleral rims metabolized [3H]arachidonic acid to 12-HETE (major metabolite), 8-HETE, and 9-HETE. HETE synthesis was inhibited by esculetin in a dose-dependent fashion. Chiral-phase analysis revealed that they contained only (S)-enantiomers, which indicated that they were lipoxygenase metabolites. The inhibitory effects of esculetin on F-actin organization and epithelial wound closure in an organ-culture assay were totally reversed by exogenously added 8(S)-HETE, whereas 12- and 9-HETE had no effect. However, none of the HETEs reversed the decreased mitotic rate or achieved complete wound closure in the cell-culture assay.

CONCLUSIONS

These results suggest that 8(S)-HETE is the key metabolite of arachidonic acid that regulates corneal epithelial cell migration during wound healing. The metabolite responsible for cell proliferation remains to be determined.

Etomoxir-induced PPARalpha-modulated enzymes protect during acute renal failure

Regulation of fatty acid beta-oxidation (FAO) represents an important mechanism for a sustained balance of energy production/utilization in kidney tissue. To examine the role of stimulated FAO during ischemia, Etomoxir (Eto), clofibrate, and WY-14,643 compounds were given 5 days prior to the induction of ischemia/reperfusion (I/R) injury. Compared with rats administered vehicle, Eto-, clofibrate-, and WY-treated rats had lower blood urea nitrogen and serum creatinines following I/R injury. Histological analysis confirmed a significant amelioration of acute tubular necrosis. I/R injury led to a threefold reduction of mRNA and protein levels of acyl CoA oxidase (AOX) and cytochrome P4A1, as well as twofold inhibition of their enzymatic activities. Eto treatment prevented the reduction of mRNA and protein levels and the inhibition of the enzymatic activities of these two peroxisome proliferator-activated receptor-alpha (PPARalpha) target genes during I/R injury. PPARalpha null mice subjected to I/R injury demonstrated significantly enhanced cortical necrosis and worse kidney function compared with wild-type controls. These results suggest that upregulation of PPARalpha-modulated FAO genes has an important role in the observed cytoprotection during I/R injury.

A comparative study of bovine pericardium (periguard) and homologous sclera as lower eyelid spacer graft analogs in New Zealand white rabbits

PURPOSE

To compare bovine pericardium (Periguard; Bio-Vascular, Inc., St. Paul, MN, U.S.A.) and homologous sclera as spacer graft analogs in a rabbit model.

METHODS

A nonrandomized experimental animal study was conducted. Elliptical subconjunctival implants were placed in one lower eyelid each of 10 rabbits. Five rabbits received homologous sclera implants, and five received bovine pericardium implants. The rabbits were killed 7 weeks later, and the lower eyelids were examined clinically and histopathologically.

RESULTS

Rabbit eyelids implanted with Periguard had a more marked inflammatory reaction and more significant collagen lamellar disruption than eyelids implanted with homologous sclera, although clinically they appeared quite similar.

CONCLUSIONS

Although bovine pericardium elicited a more intense inflammatory response at the histopathologic level, both implants were similarly tolerated at the clinical level. These findings are consistent with animal and human investigations of bovine pericardium in other parts of the body, and warrant further studies into its potential use in the human eyelid.

The influence of hyperbaric oxygen therapy and irradiation on hydroxyapatite ocular implant exposure and fibrovascular ingrowth in New Zealand white rabbits

PURPOSE

Lack of adequate fibrovascular ingrowth has been implicated as a cause of exposure of hydroxyapatite (HA) implants in anophthalmic sockets. We investigated the vasculopathic effects of external beam irradiation, and the fibrovascular-enhancement effects of hyperbaric oxygen (HBO), on HA implant exposure and fibrovascular ingrowth in a rabbit model.

METHODS

Eighteen rabbits underwent enucleation with implantation of a 12-mm HA sphere. Six rabbits received 20 Gy of external beam orbital irradiation prior to enucleation. Three irradiated and 6 nonirradiated rabbits received postoperative HBO. Three weeks postoperatively, all rabbits were evaluated clinically for evidence of implant exposure. Implants were then removed, and histopathologic analysis of fibrovascular ingrowth was performed.

RESULTS

The amount of vascularization as measured by the depth of ingrowth was greater for nonirradiated (89% ingrowth) than for irradiated (71% ingrowth) animals. HA implant exposure occurred in 1 of 12 (8%) of the nonirradiated, and 4 of 6 (67%) of the irradiated rabbit orbits. HBO did not protect irradiated rabbits from exposure, but did enhance fibrovascular ingrowth in nonirradiated rabbits (100% ingrowth vs. 77% ingrowth).

CONCLUSION

Impaired orbital vascularization from prior irradiation appears to retard fibrovascular ingrowth into HA implants, and is associated with an increased incidence of exposure. While HBO did not diminish the likelihood of exposure in irradiated sockets, HA fibrovascular ingrowth in normal orbits appeared to increase with HBO. This may have beneficial clinical application in cases of exposure in nonirradiated orbits.

Bovine pericardium versus homologous sclera as wrapping materials for hydroxyapatite ocular implants: an animal study

PURPOSE

We compared bovine pericardium and homologous sclera as wrapping materials for hydroxyapatite (HA) ocular implants in enucleated New Zealand white rabbits.

METHODS

Eighteen rabbits were unilaterally enucleated and the sockets implanted with 10-mm HA spherical implants. Six implants were wrapped with homologous sclera, 6 with bovine pericardium, and 6 were not wrapped. The rabbits were killed 7 weeks later and the sockets were examined clinically for inflammation and implant exposure. Exenterated specimens were assessed histopathologically for inflammation and vascularization.

RESULTS

No clinical evidence of implant exposure or extrusion was detected in rabbits receiving sclera or bovine pericardium wrapped implants. Histopathologically, the bovine pericardium displayed more inflammation in its outer portion, as well as more disruption of its lamellar arrangement than did the sclera. Fibrovascular in-growth was complete in all wrapped implants.

CONCLUSION

Bovine pericardium behaves similar clinically to homologous sclera as a wrapping material for spherical HA ocular implants in a rabbit model, and may represent a reasonable alternative to sclera in such procedures in humans.

Clinicopathologic features and surgical management of dissecting glaucoma filtering blebs

Three patients are described in whom full-thickness glaucoma filtering procedures were complicated by marked extension of the bleb over the cornea, with subsequent symptoms that required surgical intervention. The surgical management in each case involved blunt dissection of the bleb from the cornea, with revision of the remaining portion of the bleb differing in each case according to the intraoperative findings. Light microscopic examination of one surgical specimen revealed a markedly attenuated epithelium covering hydropic corneal stroma. The authors postulate that the mechanism of formation involves aqueous humor dissection between corneal epithelium and stroma, leading to abnormal hydration of the superficial lamellae.

Cytomegalovirus keratitis after penetrating keratoplasty

We report the development of cytomegalovirus (CMV) keratitis in the penetrating keratoplasty of a 59-year-old human immunodeficiency virus-negative woman after uncomplicated corneal transplantation. Immunosuppression with topical cyclosporine A 2% in corn oil and topical prednisolone acetate 1% suspension was used postoperatively. The 15-month postoperative course was complicated by multiple episodes of endothelial rejection, medically controlled elevated intraocular pressure, polymicrobial bacterial (coagulase-negative staphlococcus and alpha-hemolytic streptococcus) keratitis, and endothelial plaque formation with associated hypopyon and epithelial defect. The graft failed and penetrating keratoplasty was repeated. Cytomegalovirus infection of superficial keratocytes in a region of scarring was identified in histological sections stained with hematoxylin and eosin and confirmed using mouse monoclonal anti-cytomegalovirus antibodies. Excision of the diseased corneal button with no additional treatment appears to have been curative. Low-grade keratitis was the only manifestation of the CMV infection, and it has not recurred 6 months postoperatively.

Coordinated activation of corneal wound response genes in vivo as observed by in situ hybridization

We used subtractive screening of a cDNA library prepared from corneoscleral rims after cauterizing rat corneas. We identified 76 clones whose corresponding mRNA increased during the wound healing process in an in vivo model of injury which damages the corneal epithelium, stroma, and endothelium. Of these clones, 31 sequences encode known proteins. Another 45 clones are novel sequences based on comparison with the GenBank/EMBL databases. Changes in the level of expression of the novel genes, and a selected number of the known genes, were examined by in situ hybridization 22 and 72 hr after corneal injury. The majority produced a 'wound pattern' of expression such that the mRNAs were highly induced in all cell types adjacent to the wound site at 22 hr post injury. This signal decreased in intensity with distance from the wound site. In a subset of corneoslceral rims examined by in situ hybridization, the mRNAs for these genes were also highly induced in the limbal epithelium, where the progenitor corneal epithelial stem cells reside. By 72 hr, when acute tissue damage had been repaired, the induced mRNA was only faintly present in the thickened epithelium. Our results provide a useful framework for further studies defining the pathophysiological roles of the known and novel proteins encoded by the isolated cDNA clones.

Removal of optic disc stalks during diabetic vitrectomy

BACKGROUND

The morphologic features and clinical consequences of removing residual optic disc stalks during vitrectomy for complications of diabetic retinopathy have not been described.

METHODS

Twenty-four residual optic disc stalks that were surgically removed from eyes with proliferative diabetic retinopathy and dense nonclearing vitreous hemorrhage and/or traction retinal detachment were studied histologically using conventional hematoxylin and eosin staining as well as a modified Glees staining technique.

RESULTS

Histologic examination demonstrated that 79% of the specimens consisted of vascularized glial tissue with an infiltrate of mononuclear cells and 21% consisted of glial membranes devoid of vasculature. Axons were identified in 33% of all tissues studied. Intra-operative hemorrhage occurred in three eyes with strongly adherent optic disc stalks and was controlled with transient elevation of the intraocular pressure. The presence of axons in the removed optic disc stalks was not correlated with a decreased final postoperative visual acuity (median time to follow-up 21 months).

CONCLUSIONS

Residual optic disc stalks removed during vitrectomy for proliferative diabetic retinopathy frequently contained axons. The presence of axons does not portend an unfavorable postoperative visual outcome.

Pyogenic granuloma of the cornea induced by "snake oil"

A pyogenic granuloma of the cornea developed on the vascularized cornea of a 79-year-old woman after "snake oil" accidentally dripped in her eye. The snake oil was being used to relieve forehead pain, which may have been referred. The five previously reported examples of corneal pyogenic granuloma are similar to this case in that trauma preceded development of the lesion. However, the chemical trauma induced by the snake oil appears to be a unique mechanism of injury.

The effect of angiostatic steroids and beta-cyclodextrin tetradecasulfate on corneal neovascularization in the rat

Folkman and coworkers have described angiostatic steroids that markedly inhibit neovascularization of the rabbit cornea when given topically with beta-cyclodextrin tetradecasulfate (beta-CD), yet have minimal or no glucocorticoid or mineralocorticoid activity. Our objective was to extend these observations to another species, the rat. We induced neovascularization by cauterizing rat corneas with silver nitrate/potassium nitrate; drugs were applied topically four times per day for 4 days in most experiments. Submicron sized emulsions of lipid-soluble dexamethasone and the angiostatic steroids 17 alpha-hydroxyprogesterone (1 or 10 mg ml-1) and cortexolone (1 or 10 mg ml-1) were prepared by lecithin encapsulation of drug microcrystals. The vehicle for water-soluble hydrocortisone 21-phosphate (HCP) +/- beta-CD (Molecusol; Pharmatec, Inc) was 10% Tween 20 in Tris-buffered 0.9% saline. Angiogenesis was significantly inhibited only by 1 mg ml-1 dexamethasone (-63.2% when compared with controls), 0.5 mg ml-1 HCP + 1 mg ml-1 beta-CD (-33.4%), and 1 mg ml-1 HCP (-40.2%). HCP (0.5 mg ml-1) or beta-CD (1 or 2 mg ml-1) alone had no significant effect on neovascularization; the inhibition by 1.0 mg ml-1 HCP was not potentiated by 2 mg ml-1 beta-CD. We also tested HCP and tetrahydro-S (TH-S) using 1.5% hydroxypropyl methylcellulose vehicle and beta-CD from Takeda Chemical Industries, Ltd., to simulate the procedure of Folkman and coworkers.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of inhibitors of arachidonic acid metabolism on corneal reepithelialization in the rat

We examined the ability of inhibitors of arachidonic acid metabolism to influence the rate of healing of organ-cultured rat corneas with 3-mm diameter central epithelial abrasions. In control corneas, and in the presence of the cyclooxygenase inhibitors indomethacin (1 microM), or flurbiprofen (1 microM), the defect was completely reepithelialized by 25 hr. In contrast, corneas cultured with the lipoxygenase inhibitors quercetin (100 microM), esculetin (100 microM), or baicalein (10 microM) or the dual cyclooxygenase/lipoxygenase inhibitors BW 775C (100 microM) or BW A540C (100 microM) had significantly delayed epithelial healing rates when compared with the controls; complete healing of the epithelial defects required 32.5-40 hr. Dose-response studies with esculetin and BW 755C demonstrated that the concentrations for 50% inhibition of reepithelialization (65.3 microM for esculetin, 39.6 microM for BW 755 C) were significantly greater than those for inhibition of 12-lipoxygenase activity (16.6 microM for esculetin, 21.1 microM for BW 755C), the major lipoxygenase activity in normal rat cornea. Addition of 12(S)-5,8,10,14- hydroxyeicosatetraenoic acid [12(S)-HETE, 0.01-10 microM], the main 12-lipoxygenase metabolite of arachidonic acid in normal rat cornea, to the organ cultures did not influence the rate of epithelial wound healing in the absence of presence of 100 microM esculetin. Our results suggest that lipoxygenase activity is an important factor in regulating corneal epithelial wound healing in the rat, presumably by influencing epithelial cell migration. The lipoxygenase enzyme and metabolite(s) responsible for regulating reepithelialization, and the mechanism of action, remain to be determined.

Calcific phacolysis

BACKGROUND AND METHODS

The authors report the clinical and ocular histopathologic findings in three patients with longstanding unilateral post-traumatic blindness. After one or more decades, acute pain associated with conjunctival hyperemia and apparent keratoprecipitates or a hypopyon developed in the affected eye of each individual. Phacoanaphylaxis was diagnosed preoperatively in two patients.

RESULTS

Calcified granular lens fragments were dispersed throughout all three eyes. The anterior chamber in all patients contained extracellular calcified lens particles, but only one eye contained conspicuous macrophages. Two eyes showed elevated intraocular pressure (IOP), and in one patient calcified particles extended into a glaucomatous optic nerve head.

CONCLUSION

To the authors' knowledge, this is the first report describing a rare condition involving the intraocular dispersal of calcified lens particles after disruption of the lens capsule. The authors have designated this entity as calcific phacolysis.

Effect of protein kinase C inhibitors and activators on corneal re-epithelialization in the rat

PURPOSE

To examine the ability of protein kinase C (PKC) inhibitors and activators to influence the rate of corneal re-epithelialization in the rat.

METHOD

Rat corneas with 3 mm diameter central epithelial abrasions were organ-cultured in control medium or in medium with inhibitors or activators of PKC.

RESULTS

In control corneas, the defect was completely re-epithelialized by 25 hr. In the presence of the PKC inhibitors staurosporine (100 nM), sphinganine (50 mumol/l), or H-7 (100 mumol/l) there were significantly larger epithelial defects than in controls after 5-25 hr of incubation. Re-epithelialization rates were similar to control corneas when the incubation medium contained HA1004 (100 mumol/l), an analogue of H-7 that is a potent inhibitor of cyclic adenosine monophosphate- and cyclic guanosine monophosphate-dependent protein kinases and a weak inhibitor of PKC. Two PKC activators, 1-oleoyl-2-acetyl-sn-glycerol (OAG) and phorbol 12-myristate 13-acetate (PMA), were unable to enhance the rate of epithelial wound healing.

CONCLUSIONS

Our results suggest that PKC activity is an important factor in regulating corneal epithelial wound healing, presumably by influencing cell migration. Moreover, the results with OAG and PMA suggest that PKC is maximally activated during re-epithelialization in this organ-culture assay.

Histopathological variation in keratoconus

During examination of 131 penetrating keratoplasty specimens from patients with keratoconus obtained in an 11-year period, we observed two histopathologic variants based on the appearance of Bowman's layer and the corneal epithelium. "Typical" keratoconus specimens had multiple breaks in Bowman's layer and central epithelial thinning, whereas "atypical" corneas lacked breaks in Bowman's layer and had less thinning of the central epithelium. Ninety-five corneas were from patients who underwent grafting in only one eye. Seventy-six (80%) of these corneas were "typical" and 19 corneas (20%) were "atypical" in appearance. Both variants had similar degrees of central stromal thinning. Patients with "typical" and "atypical" corneas differed demographically by race only; 49% of "typical" and 95% of "atypical" corneas were from white individuals. Thirty-six corneas were from 18 patients who underwent bilateral penetrating keratoplasty. The histologic appearance of these corneal pairs was concordant in 13 patients and discordant (one "typical" and one "atypical" cornea) in five patients. Statistical analysis indicated that this distribution is not significantly different from that predicted by chance and suggests that "typical" and "atypical" corneas are manifestations of the same disease process.

Corneal argyrosis associated with silver soldering

We report a patient who developed corneal argyrosis secondary to occupational silver soldering. Clinically, the cornea was notable for a green-brown discoloration localized to Descemet's membrane by slit-lamp biomicroscopy. Silver particles were identified within the anterior three eighths of Descemet's membrane by light and electron microscopy and energy-dispersive x-ray microanalysis. To our knowledge, the association between corneal argyrosis and silver soldering has not been previously reported.

Cat keratoplasty wound healing and corneal astigmatism

BACKGROUND

A major contributor to postkeratoplasty astigmatism may be donor/recipient disparity. Deficient or excess cornea at the wound is thought to influence the directions of the steep and flat meridians. Using an established model of penetrating keratoplasty in the cat, this study evaluated the morphometry of histopathologic wound features in the steep and flat meridians.

METHODS

Thirteen cats had successful penetrating keratoplasties after intentionally misshapen donor corneas were misaligned in misshapen recipient beds. At 9.50 +/- 0.32 (mean +/- 1 SEM) months after keratoplasty, photokeratography was performed and analyzed, corneas were sectioned along the steep and flat meridians, and four histologic sections were processed. Features of the wounds were measured using a Zeiss Videoplan. The relationships between the morphometry of each feature and every other feature, between the morphometry of each feature and eccentricity, and between the steep and flat section morphometry of each feature were statistically evaluated.

RESULTS

Epithelial thickness, area of lamellar alteration, length of Descemet's membrane produced postoperatively, and the depth that preoperative Descemet's membrane was embedded in the stroma were correlated with eccentricity (corneal astigmatism). Stromal thickness and the presence or absence of folded and fragmented Descemet's membrane were not correlated with eccentricity. Wound morphometry at the steep meridians was neither correlated with nor significantly different from wound morphometry at the flat meridians.

CONCLUSIONS

Differences between healing at the steep and flat meridians were not likely contributors to astigmatism. Disproportionate availability of tissue in wound regions may have affected healing throughout the entire wound over time. The absence of Bowman's layer in cats restricts application of our results to understanding the etiology of corneal astigmatism after penetrating keratoplasty in humans.

The effect of total-body irradiation on corneal neovascularization in the Fischer 344 rat after chemical cauterization

Previous investigations of corneal neovascularization after irradiation yielded discordant results. Most studies indicated that new blood vessel formation in the cornea is inhibited by irradiation. However, others reported that angiogenesis after corneal cauterization is similar in both irradiated and nonirradiated animals. To assess the effect of total-body irradiation on neovascularization further, the amount of angiogenesis was determined in irradiated rats after chemically induced corneal injury. Corneal tissue was evaluated quantitatively with computerized image analysis 2, 3, or 4 days postcautery in rats perfused with India ink and gelatin immediately after death. The rats were exposed to a single dose (9 Gy) of total-body irradiation 6 days before corneal cauterization. In both the nonirradiated and irradiated rats, neovascularization increased with the duration of the postcautery interval. The amount of corneal neovascularization was not significantly different in the irradiated and nonirradiated rats at any of the postcautery intervals studied. This investigation suggests that endothelial cell migration plays a more important role than cell replication in the pathogenesis of corneal angiogenesis in the Fischer 344 rat. Moreover, the suppression of corneal angiogenesis by irradiation may be dependent on the experimental conditions and species examined.

Retrobulbar anesthesia and eyelid closure--effect on corneal angiogenesis

We evaluated the effect of corneal anesthesia produced by retrobulbar injections of bupivicaine and epinephrine on corneal neovascularization in the rat. The eyelids were sutured closed to prevent dessication and ulceration of the insensitive corneas. The amount of corneal neovascularization induced in animals receiving a retrobulbar anesthetic did not differ from those receiving control solutions. However, rats receiving retrobulbar injections exhibited greater corneal neovascularization than those that did not. Rats that had their eyelids sutured or patched closed also had more neovascularization than animals that did not. Likewise, rats that had sutures placed in the upper and lower eyelids, without palpebral immobilization, manifested more neovascularization than rats without sutures. These studies suggest that corneal anesthesia does not affect neovascularization induced by silver/potassium nitrate cauterization and that retrobulbar injections and eyelid closure enhance corneal neovascularization.

Histopathology of silicone oil keratopathy in humans

Corneal endothelial decompensation is a frequent complication when silicone oil is used as a tamponade following vitrectomy for treatment of proliferative vitreoretinopathy in an aphakic eye. We evaluated the clinical, histopathological, and ultrastructural features of silicone oil-induced keratopathy in 10 patients who developed corneal complications requiring penetrating keratoplasty. Clinically, some cases showed corneal edema, corneal hypesthesia, endothelial opacification, band keratopathy, and peripheral corneal vascularization. Histopathologically, retrocorneal membranes were present, and different degrees of stromal hypercellularity, superficial stromal calcification, and vascularization were noted. The ultrastructural features of endothelial cell loss and retrocorneal membrane formation are consistent with changes previously reported in rabbits and cats receiving intracameral silicone oil injections.

12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid is a more potent neutrophil chemoattractant than the 12(R) epimer in the rat cornea

12(R)-hydroxy-5,8,10,14-eicosatetraenoic acid [12(R)-HETE] is reported to be more potent than its epimer 12(S)-HETE as a chemoattractant for human neutrophils in vitro and following topical application to the skin. To assess the in vivo neutrophil chemoattractant potencies of 12(S)-HETE and 12(R)-HETE in the rat, we injected 1 microgram, 5 micrograms, or 10 micrograms of these eicosanoids into the corneal stroma. Rats were killed 12-15 hours after injection, and the number of neutrophils in the stroma was counted in a histological section of the cornea including the injection site. The number of neutrophils was significantly increased in corneas injected with 5 micrograms (+103% of control) or 10 micrograms (+456% of control) of 12(S)-HETE and in those injected with 10 micrograms of 12(R)-HETE (+111% of control). The neutrophilic infiltrate in corneas injected with 1 microgram or 5 micrograms of 12(S)-HETE was not significantly different from that in corneas injected with 1 microgram of leukotriene B4. The data for the 10 micrograms injections indicate that 12(S)-HETE is a more potent neutrophil chemoattractant than 12(R)-HETE in the rat cornea. Our results suggest that species or tissue specificity may determine the relative potencies of 12-HETE epimers as chemoattractants for neutrophils, and that 12(S)-HETE may be an important inflammatory mediator in the rat cornea.

The effect of oxygen on corneal neovascularization

Since tissue oxygen levels are believed to play a pivotal role in new vessel growth in several situations, we studied the effect of several oxygen concentrations (0, 10, 21, 50, 75, or 100%) on corneal vascularization induced in the rat by chemical cautery. We achieved this by perfusing known concentrations of oxygen through goggles fitted over both eyes of the rat after corneal cauterization. Neovascularization was measured in flat corneal preparations with India ink-filled vessels 4 days postcautery using computerized image analysis. The angiogenic response of rats whose eyes were continuously exposed to 0-75% oxygen were not significantly different from each other. The mean response in corneas exposed to 100% oxygen was 10-21% lower than all of the other groups, and this difference was statistically significant when compared to oxygen concentrations of 0, 21 and 75%. The reason for the inhibitory effect of 100% oxygen remains to be determined, but it may represent a toxic effect of oxygen free radicals on the vascular endothelium.

Effect of inhibitors of arachidonic acid metabolism on corneal neovascularization in the rat

We used computerized image analysis to evaluate quantitatively the ability of topically applied corticosteroids (dexamethasone sodium phosphate, prednisolone acetate), cyclooxygenase inhibitors (flurbiprofen, indomethacin, ketorolac), lipoxygenase inhibitors (REV 5901, esculetin, quercetin), and dual cyclooxygenase/lipoxygenase inhibitors (BW 755C, BW A540C) to reduce corneal neovascularization in the rat induced by silver/potassium nitrate cauterization. Significant decreases in the neovascular response were found with corticosteroids and cyclooxygenase inhibitors. A complete dose-response curve was performed for a representative compound from each class. Dexamethasone was found to be superior to flurbiprofen in its ability to reduce neovascularization in this model, while no significant inhibition was noted with either REV 5901 or BW 755C, even at high doses. We conclude that the corneal angiogenic response in this model can be reduced by inhibition of cyclooxygenase as well as by other mechanisms that are steroid-dependent but are, as yet, poorly defined.

The effects of total lymphoid irradiation upon corneal vascularization in the rat following chemical cautery

The effect of total lymphoid irradiation (TLI), a form of radiotherapy known to suppress the number of circulating lymphocytes, on corneal neovascularization was assessed in rats. The corneas of TLI-treated rats were cauterized with silver/potassium nitrate one day after delivering gamma irradiation in five equal fractions (10 Gy total dose). Corneal neovascularization was assessed quantitatively by computerized image analysis in corneal flat preparations 4 days after corneal injury following perfusion of the circulation with India ink. TLI reduced the total leukocyte, lymphocyte, neutrophil, and platelet counts below preirradiation levels. The number of circulating lymphocytes was reduced more than neutrophils and platelets. TLI caused a predominance of cytotoxic/suppressor lymphocytes. Tissue examinations 4 days after TLI disclosed an absence of the thymus, as well as a markedly reduced number and size of lymph nodes. TLI rats had less corneal vascularization than nonirradiated controls. Our findings are consistent with the hypothesis that leukocytes play an important role in the pathogenesis of corneal angiogenesis following chemical cautery, but this study does not indicate how TLI suppresses corneal neovascularization.

Intraocular pressure following intravitreal silicone oil injection

The clinical features of 100 consecutive cases and the histopathology of six enucleated eyes, all having undergone silicone oil injection for complicated retinal detachments, were studied with regard to the incidence and mechanisms of postoperative intraocular pressure changes. Preoperatively, five patients had glaucoma and 35 had hypotony (7 mm Hg or less). Immediately after surgery, 43 patients had glaucoma and 14 had hypotony, while seven had glaucoma and 39 had hypotony in the late postoperative period (average follow-up of 1 year). In most cases, the mechanism of intraocular pressure change did not appear to be directly related to the presence of silicone, but rather to the preoperative status of the eye and other aspects of the vitreoretinal surgery. When silicone was a factor, the resulting intraocular pressure appeared to represent a balance between mechanisms obstructing aqueous outflow (pupillary block and the reaction to silicone bubbles in the anterior chamber angle) and mechanisms reducing aqueous production (cyclitic membranes and retinal detachment).

Quantitation of corneal neovascularization using computerized image analysis

We have developed a method for quantitating corneal neovascularization, induced in anesthetized rats by silver nitrate/potassium nitrate cauterization, using a LeMont OASYS video input image analyzer. Corneal vessels are visualized by perfusing the upper half of deeply anesthetized animals with a mixture of 10% india ink, 11% gelatin in lactated Ringer's solution. The eyes are then rapidly cooled using a stream of compressed dichlorodifluoromethane (Freon) to solidify the gelatin mixture. Magnified images of flat preparations of the corneas are acquired using a television camera attached to a dissecting microscope. The images are electronically converted to digital form and the digitized data are stored in the image analyzer. The area of the cornea and blood vessels are independently determined by analyzing the digitized data as discrete values of varying shades of gray (gray-scale analysis). The area and gray scale of the injury and its distance from the corneoscleral limbus can also be measured to determine variability of location and intensity of the injury in different animals. This technique allows the area occupied by new blood vessels during studies on corneal neovascularization in rats to be rapidly quantitated.

Primary orbital leiomyosarcoma. A case report and review of the literature

An 82-year-old woman presented with a five-week history of painless proptosis. Results of clinical evaluation, including computed tomography, were consistent with a benign orbital tumor. Biopsy followed by surgical resection disclosed leiomyosarcoma. We reviewed the literature and studied the clinical spectrum of this rare disease of the orbit.

Retinal toxicity of cyanoacrylate tissue adhesive in the rabbit

N-butyl-2-cyanoacrylate tissue adhesive was injected into the preretinal space of rabbit eyes to study potential toxicity to the retina. Application of 3.3-10.0 ul of cyanoacrylate tissue adhesive showed localized but definite retinal toxicity. White halos appeared surrounding the preretinal cyanoacrylate immediately after injection with a gradual evolution of the white areas into pigmentary scars by 1 month. Histological examination confirmed severe focal necrosis of the retina. No identifiable distant toxic effects or electrophysiologic changes were observed during the 6-month follow-up period.

Histopathologic and immunochemical features of lattice corneal dystrophy type III

We examined seven corneas from five patients with a new form of lattice corneal dystrophy (designated lattice corneal dystrophy type III) by light and electron microscopy. Numerous amyloid deposits were scattered throughout the corneal stroma, some of which were much larger than those usually observed in either lattice corneal dystrophy type I or II; these were located predominantly midway between the epithelium and the endothelium. Image analysis disclosed that the cross-sectional size of the large stromal amyloid deposits was significantly greater than those in age-matched patients with lattice corneal dystrophy type I. All patients had a discontinuous band of amyloid (15 to 25 micron wide) in the superficial stroma beneath Bowman's layer, which usually had only one or two small disruptions. Descemet's membrane and the endothelium were normal. The stromal deposits, which were composed of 10-nm diameter fibrils typical of amyloid, stained positively with Congo red after the histologic sections were pretreated with dilute potassium permanganate. Immunohistochemical studies on formalin-fixed, paraffin-embedded tissue indicated that only some deposits reacted weakly with antibodies to amyloid protein AA. The deposits stained positively with antibodies to protein AP and negatively with antibodies to kappa and lambda immunoglobulin light chains.

Improvement in efficacy of corticosteroid therapy in an animal model of proliferative vitreoretinopathy by pretreatment

Intraocular injection of the corticosteroid triamcinolone acetonide reduces the incidence of retinal detachment in rabbit eyes injected with tissue-cultured fibroblasts. When the steroid was injected simultaneously with the cells, a reduction of retinal detachment from 93% (control) to 75% (treated) was achieved on day 28. When the steroid was injected 24 h preceding cell injection, the reduction of retinal detachment was from 85% (control) to 43% (treated). The development of retinal detachment is caused by proliferation of injected fibroblasts. Reduction of this proliferation is probably achieved partially through direct inhibition of mitosis, but more important may be the reduction of the reactive inflammatory process.

Experimental transvitreal cyanoacrylate retinopexy in a primate model

We evaluated the use of transvitreal cyanoacrylate retinopexy in the treatment of experimental rhegmatogenous retinal detachment during vitreous surgery in the cynomolgus monkey. The chorioretinal adhesions produced with cyanoacrylate tissue adhesive as compared with those produced by transscleral retinal cryopexy were more rapid in onset as well as stronger. To test the efficacy of cyanoacrylate retinopexy further, a 360-degree peripheral retinectomy was created in five eyes with circumferential cyanoacrylate application to the posterior retinal edge. The cyanoacrylate retinopexy did not prevent the development of proliferative vitreoretinopathy with traction retinal detachment, but in three of the eyes the tissue adhesive continued to maintain retinal apposition to the retinal pigment epithelium at the retinotomy edge. Histologic examination of the retinas disclosed a foreign body reaction adjacent to the cyanoacrylate sites, but there was no evidence of any distant effects caused by the tissue adhesive.

Neovascular glaucoma associated with an iris melanoma. A clinicopathologic report

A 48-year-old man had uniocular neovascular glaucoma, with the only apparent predisposing factor being a primary epithelioid melanoma of the iris. The new vessels disappeared following total excision of the tumor. These findings have implications regarding the mechanisms of neovasculogenesis.

Cholinergic stimulation of phosphatidylinositol hydrolysis by rat corneal epithelium in vitro

Phosphatidic acid (PA) is an obligate intermediate in the phosphatidylinositol (PI) cycle and may serve as a sensitive marker for this pathway of reactions. Previously, we have shown that acetylcholine (ACh) stimulates formation of labeled PA in whole rat corneas whose phospholipids were prelabeled with [14C]arachidonate. To determine which layer of the cornea exhibits the ACh effect, intact epithelium was isolated from the rest of the corneal tissue (designated "stroma/endothelium") by incubating rat corneas with neutral protease and then stripping off the epithelium using forceps. The epithelium was ultrastructurally normal and avidly incorporated [14C]arachidonate into phospholipids; the stroma/endothelium had only trace incorporation. [14C]Arachidonyl-PA formation by the epithelium was significantly increased after a 37 second (+58%) and was maximal after a 5.0 minute (+188%) incubation in the presence of 1 mM ACh. The stimulation by ACh was blocked by atropine and scopolamine but not by d-tubocurarine. The epithelium also incorporated significant quantities of [3H]inositol into phosphatidylinositol (PI), phosphatidylinositol monophosphate (PIP), and phosphatidyl-inositol bisphosphate (PIP 2). When [3H]inositol-labeled epithelia were incubated for 5 minutes with 1 mM ACh, [3H]inositol monophosphate (IP) was increased 200%, [3H]inositol bisphosphate (IP2) was increased 225%, and [3H]inositol 2 trisphosphate (IP3) was increased 74%. These results suggest that muscarinic cholinergic receptors may be an important regulator of the PI cycle in corneal epithelium and thus may affect intracellular calcium mobilization and epithelial proliferation and regeneration.

Ocular rosacea

The demographic, clinical, and histopathologic characteristics of ocular rosacea are reviewed, with emphasis on examination of the skin in patients with external ocular disease. Since no single clinical or pathological hallmark of rosacea exists, a proposed point system for diagnosis is presented. Studies of pathogenesis reveal that no single unifying hypothesis accounts for all the expressions of ocular rosacea. Reports of treatment with tetracycline and other antibiotics demonstrate efficacy, although the mechanisms of action of these drugs are not known. More recently, other classes of drugs, including isotretinoin and hexachlorocyclohexane, have proven to be effective in dermatologic manifestations of rosacea, but effects on ocular manifestations are unknown.

Fatal pulmonary bile embolism following acute acalculous cholecystitis

A 52-year-old man died during reoperation for bleeding after the development of acute postoperative acalculous cholecystitis. While the liver was being manipulated during surgery, the pulmonary artery diastolic pressure increased suddenly, cardiac output and blood pressure decreased, and soon afterward the patient had a cardiac arrest from which he could not be resuscitated. During resuscitative efforts, the maximum partial arterial oxygen pressure achieved was only 55 mm Hg despite 100% inspired oxygen. At autopsy, bile aggregates were found within necrotic liver parenchyma, portal and central vein branches, and numerous pulmonary arterioles and capillaries. The pulmonary arterial bile most likely resulted from embolization of inspissated hepatic bile aggregates during surgical manipulation.

Cholinergic stimulation of phosphatidic acid formation by rat cornea in vitro

The cornea has one of the highest acetylcholine (ACh) concentrations of any tissue but the function of the ACh has remained enigmatic. During studies on corneal arachidonic acid metabolism, we observed that ACh stimulates formation of labeled phosphatidic acid in rat corneas whose phospholipids were prelabeled with [14C]arachidonate. ACh did not affect the metabolism of free [14C]arachidonate. [14C]Arachidonyl-phosphatidic acid formation was doubled after 10 min of incubation in the presence of ACh concentrations of 10(-4) M or greater. The stimulation by ACh could be completely blocked by atropine and scopolamine and partially blocked by d-tubocurarine. These studies suggest that intact rat cornea has muscarinic cholinergic receptors and that the enzymes of the inositol phospholipids pathway are present since phosphatidic acid is an obligatory intermediate in that cycle of reactions.

Ocular cicatricial pemphigoid with granular IgA and complement deposition

A 65-year-old woman developed chronic redness of both eyes, and, over the ensuing 2 1/2 years, she had progressive conjunctival scarring with symblepharon formation. Other mucosal surfaces were not involved. A conjunctival biopsy specimen 12 months following onset of her disease showed areas of epithelial separation from the basement membrane zone as well as subepithelial chronic inflammation and scarring. Two years later, another conjunctival biopsy specimen showed granular deposition of IgA and C3 along the epithelial basement membrane zone using direct immunofluorescent staining. Electron microscopy confirmed the presence of deposits that were morphologically consistent with antigen-antibody complexes. These findings suggest that antigen-antibody (IgA) immune-complex deposition may provide an alternative pathogenetic mechanism to basement membrane zone autoantibody formation for development of progressive conjunctival scarring.

Cutaneous T-cell lymphoma presenting as a rapidly enlarging ocular adnexal tumor

A 63-year-old man, in good health previously, developed swelling and erythema of the right upper eyelid which progressed to involve both eyelids and surrounding tissues. After one month, he had a 9.0 x 9.0 x 3.5 cm mass despite two attempts at incisional drainage and treatment with antibiotics. Multiple asymptomatic erythematosus nodules (2-3 cm in diameter) developed on his back, trunk, and arms four weeks after onset of the eyelid erythema and swelling. Biopsies of two upper back papules and the eyelid disclosed cutaneous T-cell lymphoma, a lymphoproliferative malignancy of thymus derived lymphocytes originating in the skin. Systemic chemotherapy resulted in a marked decrease in the ocular adnexal mass but lymphomatous meningitis and quadriplegia developed. The patient died four months later; an autopsy was not performed. This case demonstrates that cutaneous T-cell lymphoma may rarely have its initial manifestation as a rapidly enlarging eyelid tumor.

Pyoderma gangrenosum involving the eyelid

A 62-year-old man was seen with an ulcer of the left upper eyelid of two weeks' duration. Over the previous 40 years, similar ulcers had intermittently developed elsewhere on his skin and spontaneously resolved over several months leaving atrophic scars. A biopsy specimen of the eyelid lesion showed epidermal ulceration with acute inflammation and liquefactive necrosis of the underlying dermis. Microorganisms and vasculitis were not present. On the basis of the clinical history and a compatible biopsy specimen, the diagnosis of pyoderma gangrenosum was made. This is an uncommon, idiopathic, ulcerating skin disease that may also have ocular manifestations. Eyelid ulcers have not previously been reported, to our knowledge. The diagnosis is established by clinical history and exclusion of other causes of ulceration.

Identification of calcium oxalate crystals using alizarin red S stain

Calcium oxalate crystals stain with alizarin red S at a pH of 7.0 but not at a pH of 4.2. In contrast, calcium phosphate and calcium carbonate stain at a pH of both 7.0 and 4.2. This difference allows presumptive identification of calcium oxalate deposits. The identity of calcium oxalate can then be confirmed by its insolubility in 2M acetic acid, since both calcium carbonate and calcium phosphate are soluble. We have applied this procedure for several years and have found it to be a rapid, reliable, and technically simple procedure for distinguishing calcium oxalate from other calcium deposits.

Mitomycin-induced hemolytic-uremic syndrome

Four patients who took the antitumor agent mitomycin manifested microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. At autopsy, kidneys from all four patients had a microangiopathy typical of the hemolytic-uremic syndrome (HUS), with thromboses in glomerular capillaries and arterioles, fibrin deposition in mesangium, and prominent cellular intimal proliferation of the interlobular arteries. Development of the HUS was an important factor contributing to death in all four patients. From a review of the literature and our initial results of a randomized chemotherapy protocol for metastatic adenocarcinoma of the colorectum, it appears that mitomycin was the most likely cause for the development of the HUS in these patients. As more patients are being treated with mitomycin, particular care must be taken to monitor them for development of a drug-induced HUS.

Controlled aspiration of subretinal fluid in the diagnosis of carcinoma metastatic to the choroid

Carcinoma metastatic to the choroid was diagnosed in three patients by cytopathologic examination of subretinal fluid. The specimen was obtained using a scleral depressor modified to allow controlled aspiration of subretinal fluid through a sharp, angled, 30-gauge needle. This new method provides a useful tool for accurate diagnosis of carcinoma metastatic to the choroid in cases where the diagnosis is in question.