Bevacizumab and intraocular tumors: an intriguing paradox.

PURPOSE: Bevacizumab, a humanized monoclonal antibody to vascular endothelial growth factor-A (VEGF-A), was originally developed as an anti-tumor treatment. In ocular oncology, it is being used to treat macular edema due to radiation retinopathy, but it may also be useful for the treatment of primary uveal melanoma (UM) or its metastases. We determined the effect of bevacizumab on the growth of B16F10 cells inside the eye and on B16F10 and UM cells cultured in vitro. METHODS: B16F10 melanoma cells were placed into the anterior chamber of the eye of C57Bl/6 mice and tumor growth was monitored after injection of different doses of bevacizumab or mock injection. In addition, the effect of bevacizumab on in vitro growth of B16F10 and human UM cells and on the expression of VEGF-A, GLUT-1, and HIF-1α was evaluated. RESULTS: Following intraocular injection of bevacizumab into murine B16 tumor-containing eyes, an acceleration of tumor growth was observed, with the occurrence of anterior chamber hemorrhages. Bevacizumab did not affect proliferation of B16F10 cells in vitro, while it inhibited UM cell proliferation. Expression analysis demonstrated that addition of bevacizumab under hypoxic conditions induced VEGF-A, GLUT-1 and HIF-1α in B16F10 cells as well as in UM cell lines and two of four primary UM tumor cultures. CONCLUSIONS: In contrast with expectations, intraocular injection of bevacizumab stimulated B16F10 melanoma growth in murine eyes. In vitro exposure of B16 and human UM cells to bevacizumab led to paradoxical VEGF-A upregulation. The use of VEGF inhibitors for treatment of macular edema (due to radiation retinopathy) after irradiation of UM should be considered carefully, because of the possible adverse effects on residual UM cells.

Pathological changes in rabbit retina and its relationship with glutamic acid after injuries from high-speed bullets.

PURPOSE: To observe the pathological changes in rabbit retinas and the measure of glutamic acid levels in the vitreous body after suffering from high-speed bullet injuries. METHODS: Rabbits eyeball contusion models were established with high-speed bullets, i.e., the rabbits eyes were shot with a fixed air rifle at a speed of 90m/s (using plastic bullets, weighing 0.20122g, on average). Retinal tissues treated with HE staining and were prepared for light microscopy examination and glutamate levels were tested at different points in time after the injury. RESULTS: Edema, exudation, hemorrhage, and rupture were evident in rabbit retinas following bullet injuries. Meanwhile, glutamate levels gradually increased as time proceeded. CONCLUSION: Visual impairment is related with retinal damages after high-speed bullet injuries. Increased glutamate concentration serves as a potential factor for aggravating retinal injuries.

Effect of subconjunctivally injected liposome-encapsulated tissue plasminogen activator on the absorption rate of subconjunctival hemorrhages in rabbits.

PURPOSE: To evaluate the effect of subconjunctivally injected liposome-encapsulated tissue plasminogen activator (tPA) on the absorption rate of subconjunctival hemorrhages (SHs). METHODS: SHs were induced in 1 eye each of 36 rabbits by subconjunctival injection of 0.05 mL of autologous blood. After 8 hours, randomized subconjunctival injections were performed: 26,000 IU/mL liposome-encapsulated tPA (0.05 mL) in 9 eyes (group A), free-form tPA (26,000 IU/mL; 0.05 mL) in 9 eyes (group B), only liposomes (0.05 mL) in 9 eyes (group C), or no injection in 9 eyes (group D). The sizes of the SHs at 8, 24, 48, 72, 96, and 120 hours after induction were measured using an image analyzer and were compared among the 4 groups. RESULTS: Group A showed significantly more rapid absorption rates than all the other groups at 24, 48, and 72 hours and had the significantly shortest mean elapsed time for the complete resorption of SHs. The tPA activity in ocular tissue except conjunctiva and plasma were negligible beyond 24 hours after SH induction with both forms of tPA. In the conjunctiva, the tPA activity was significantly prolonged in the liposome-encapsulated tPA group than in the free tPA group. CONCLUSIONS: Subconjunctival injection of liposome-encapsulated tPA seems to enhance SH absorption in rabbits, especially during the early stages with minimal systemic and ocular absorption.

Subconjunctivally injected, liposome-encapsulated streptokinase enhances the absorption rate of subconjunctival hemorrhages in rabbits.

Liposome-encapsulated streptokinase (SK) was prepared with distearoyl-phosphatidyl-ethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-PEG(2000)). In vitro release assay demonstrated over 81% of SK was released from liposomes at 48 h, and the effect of its subconjunctival injection on the absorption rate of induced subconjunctival hemorrhage (SH) in rabbits was evaluated. After 8h of SH induction, eyes were randomly assigned to one of four subconjunctival injection groups (10 eyes each): group A: the free form of SK (1000 IU/mL); group B: liposome-encapsulated SK (1000 IU/mL); group C: 0.1 mL of liposomes; and group D: no injection. SHs were photographed at 8, 24, 48, 72, and 120 h after SH induction and their sizes were compared. Size decrease of the SH was faster in groups A and B than in groups C and D. Group B displayed significantly different absorption rates than group A at 24 and 48 h and with groups C and D at 24, 48, and 72 h, with the shortest mean elapsed time among all groups. The ocular absorption of SK was lower after the injection of the liposome-encapsulated SK than the free form. These results demonstrated that subconjunctival injection of liposome-encapsulated SK enhances the rate of SH absorption, especially in the early phases.

Vitality and age of conjunctival petechiae: the expression of P-selectin.

Confocal laser scanning microscopy (CLSM) results in displaying multiple ruptures of capillaries and venules define conjunctival petechiae as a rhexis haemorrhage. In order to distinguish between petechiae which have arisen before death as opposed to post-mortem artefacts and the establishment of the age of the vessel's damage, we carried out an investigation on a collection of samples from medico-legal cases (positive petechiae: n=65; post-mortem artefacts: n=12; control: n=19) to establish whether the expression of the endothelial adhesion molecule P-selectin as demonstrated by immunohistochemical methods is influenced by trauma before death and possibly by time. Except for cases with massive congestion in those cases where the victim had survived for around minutes, CLSM examination revealed a strong endothelial reaction at the site where the vessel had ruptured. It was impossible to detect a strong P-selectin expression signal in both those vessels which had not suffered any mechanical insult and those which had experienced post-mortem rupture. Therefore, the elevated expression of P-selectin can be used as a criterion to distinguish between those lesions which have occurred in life and those which are post-mortem artefacts.

Ocular autopsy and histopathologic features of child abuse.

PURPOSE: To study the ocular histopathologic features in eyes of children with fatal suspected child abuse. DESIGN: Retrospective case series. PARTICIPANTS: One hundred eighteen autopsy cases of known or suspected child abuse. METHODS: The ocular autopsy and histopathologic features of a cohort of consecutive cases of known or presumed child abuse submitted by Maryland's Office of the Chief Medical Examiner or Johns Hopkins Hospital to the Wilmer Eye Pathology Laboratory were tabulated. MAIN OUTCOME MEASURE: Ocular hemorrhage or structural abnormality. RESULTS: Retinal hemorrhage was present in 44% of cases. Circumferential folds with macular schisis cavities were present in 23% of cases and were bilateral in half of those cases. Peripapillary scleral hemorrhage was present in 38% of cases, and subdural hemorrhage was present in the distal optic nerve in 46% of cases. Hemosiderin was present in 27% of cases. CONCLUSIONS: Intraretinal hemorrhages, circumferential macular folds with schisis cavities, peripapillary scleral hemorrhages, and subdural hemorrhages are common pathologic findings in cases of fatal known or suspected child abuse. Their presence on autopsy should raise the suspicion of shaking or blunt nonaccidental trauma.

Effect of subconjunctivally injected, liposome-bound, low-molecular-weight heparin on the absorption rate of subconjunctival hemorrhage in rabbits.

PURPOSE: To investigate the effect of subconjunctival injection of liposome-bound, low-molecular-weight heparin (LMWH) on the absorption rate of subconjunctival hemorrhages. METHODS: Subconjunctival hemorrhages were induced in both eyes of 30 rabbits by the subconjunctival injection of 0.1 mL of autologous blood from auricular marginal veins. After 8 hours, randomized subconjunctival injections of one of three materials were made: 5 IU/mL liposome-bound LMWH (0.1 mL) in 18 eyes (group A), only liposomes (0.1 mL) in 14 eyes (group B), the free form of LMWH (5 IU/mL, 0.1 mL) in 14 eyes (group C), or no injection in 14 eyes (group D). Subconjunctival hemorrhages were photographed with a digital camera at 8, 24, 48, 72, 96, and 120 hours after induction of subconjunctival hemorrhages, sized with an image analyzer, and compared between groups. RESULTS: Subconjunctival hemorrhages were absorbed faster in group A (liposome-bound LMWH injected) than in with group B (liposome injected). Comparison of groups A and C (free LMWH injected) showed statistical differences in the absorption rates at 96 and 120 hours except at 24, 48, and 72 hours. The mean elapsed time for the complete resorption of subconjunctival hemorrhages was shortest in group A among four groups, whereas group B and the control showed no significant differences. The ocular and systemic absorption of LMWH were significantly lower after injection of the liposome-bound than the free form. CONCLUSIONS: The subconjunctival injection of liposome-bound LMWH appears to enhance subconjunctival hemorrhage absorption in rabbits.

[Pharmacokinetics of recombinant pro-urokinase ocular dosage form]. / Farmakokinetika glaznoi formy rekombinantnoi prourokinazy.

Thrombolytic enzymes are widely used in the treatment of vascular diseases of the eyes and of intraocular hemorrhages. We studied the pharmacokinetics of recombinant prourokinase (proRUK) in ocular structures after its intravitreal administration and subtenon's implantation of collagen infusion system (SICIS). Kinetic parameters of accumulation of labeled proRUK in ocular structures were obtained. After intravitreal administration, the proRUK half-life (T1/2) was 7.9 +/- 1.44 h, with proRUK losing none of its enzymatic activity while in the vitreous body. The maximum accumulation of proRUK in the vitreous administered by the SICIS is observed after 4-5 h and is 1.5-2.0% of the dose administered. In the sclera the maximum accumulation of proRUK is 10-15% (4-6 h after administration), in the vascular membrane 0.8% (4 h after administration). We believe that combination of intravitreal and SICIS-aided administration of proRUK to patients with extensive hemorrhages (subtotal and total hemopthalmia) will improve the efficacy of therapy.