Effects of omega 3 fatty acids on receptor tyrosine kinase and PLC activities in EMT6 cells.

The effects of omega 3 fatty acids and epidermal growth factor (EGF) on the activity of receptor tyrosine kinase (RTK) and phospholipase C (phosphatidylinositol (PI)-specific PLC) were examined in EMT6 cells. The non-omega 3 treated, non-EGF stimulated cells served as controls. Treatment of the EMT6 cells with omega 3 fatty acids resulted in a 62% increase in RTK activity and a 67% increase in PI-specific PLC activity. When EGF was added to incubations for RTK activity, it stimulated the RTK activity 40% in the control cells and 130% in the omega 3-treated cells. When EGF was added to incubations for PI-specific PLC activity, a 54% increase in PI-specific PLC activity was observed in control cells and a 94% increase in the omega 3-treated cells. Thus, treating EMT6 cells with omega 3 fatty acids seems to increase RTK activity and PI-specific PLC activity to a similar extent, but has differential effects on the ability of these enzyme activities to be stimulated by EGF.

Penetrating keratoplasty in rabbits induces latent HSV-1 reactivation when corticosteroids are used.

The increased incidence of corneal graft failure in patients with herpes simplex virus (HSV) keratitis may be due in part to reactivation of latent HSV following surgical corneal trauma and postoperative corticosteroid therapy. To determine the onset, frequency, and nature of HSV recurrences following penetrating keratoplasty (PKP), 21 HSV type 1 (HSV-1) latently infected rabbits underwent unilateral autograft PKP. Opposite unoperated eyes served as HSV-1 latently infected controls. Corneal autografts were performed so that immunologic graft rejection would not be confused with recurrent HSV-1 stromal disease. After PKP, 11 of the 21 eyes were treated with dexamethasone. Ocular cultures and slit-lamp examinations were performed daily for the first postoperative 8 days and every other day thereafter for 82 days. Nine (82%) of the 11 dexamethasone-treated PKP eyes, 2 (20%) of the PKP eyes not treated with dexamethasone, and 3 (17%) of the 18 unoperated eyes had positive HSV-1 ocular cultures. Geographic ulcers appeared only in the PKP eyes treated with dexamethasone; 9 (82%) of the 11 PKP eyes treated with dexamethasone developed geographic ulcers. Between the 24th and 90th postoperative days, stromal keratitis appeared in 5 (56%) of the 9 PKP eyes treated with dexamethasone and in 2 (25%) of the 8 PKP eyes not treated with dexamethasone. Autograft PKP with postoperative corticosteroids significantly increased HSV-1 ocular shedding, epithelial ulceration, and stromal keratitis. This experimental model provides a useful tool to further investigate the development and treatment of HSV-1 epithelial and stromal recurrences after PKP.

Oral acyclovir reduces the incidence of recurrent herpes simplex keratitis in rabbits after penetrating keratoplasty.

To determine if acyclovir sodium prevents postoperative herpes simplex virus type 1 (HSV-1) recurrences, 21 rabbits harboring latent HSV-1 underwent uniocular autograft penetrating keratoplasty. All operated-on eyes were treated with topical and subconjunctival dexamethasone sodium phosphate. Ten of the 21 rabbits also received oral acyclovir (intravenous acyclovir was given at the time of surgery). Postoperatively, 9 (82%) of 11 operated-on eyes in rabbits not treated with acyclovir had positive HSV-1 ocular cultures. In acyclovir-treated rabbits, however, none of the 10 operated-on eyes had positive ocular cultures. In addition, 9 (82%) of 11 of the operated-on eyes had geographic ulcers develop in the non-acyclovir-treated rabbits, compared with 1 (10%) of 10 in the acyclovir-treated rabbits. Finally, stromal keratitis appeared in 5 (56%) of 9 of the operated-on eyes in non-acyclovir-treated rabbits and 1 (12%) of 8 of the operated-on eyes in acyclovir-treated rabbits. The results of this study indicate that acyclovir significantly lowered the incidence of HSV-1 ocular shedding, geographic ulceration, and stromal keratitis in a rabbit autograft penetrating keratoplasty model.

An anatomic study of retrobulbar needle path length.

One hundred twenty human orbits were measured to determine orbital depth and the position of orbital structures in relation to the length of needles used for retrobulbar anesthesia. The distance from the inferior temporal orbital rim to the nasal entrance of the optic foramen ranged from 42 to 54 mm. Taking into account the size of the optic nerve, the common 38-mm (1.5-in) retrobulbar needle could perforate the optic nerve where it is fixed in front of the foramen in over 11% of the population. The authors recommend that needles be placed less than 31 mm (1.25 in) behind the orbital rim for both retro- and peribulbar anesthesia.