David DiLoreto

Neurotoxic Effects of Tumor Necrosis Factor Alpha in Primary Human Neuronal Cultures are Mediated by Activation of the Glutamate AMPA Receptor Subtype: Implications for AIDS Neuropathogenesis

Human immunodeficiency virus type 1 (HIV) infection of the central nervous system is characterized by neuronal loss in discrete areas of the central nervous system. We have previously demonstrated that HIV-infected monocytes in culture with astroglial cells produce high levels (> or = 200 pg/ml) of the cytokine tumor necrosis factor-alpha (TNF alpha). We now demonstrate that TNF alpha (> or = 200 pg/ml) is neurotoxic to cultured primary human fetal cortical neurons at both light and electron microscopic levels. Subtoxic doses of TNF alpha (50 pg/ml) are neurotoxic in combination with the glutamate (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) subtype receptor agonist AMPA (100 microM). The neurotoxic effects of TNF alpha (200 pg/ml) are blocked in part by the AMPA receptor antagonist, 6-cyano-7-nitroquinoxaline-2, 3-dione (10 microM). This suggests that TNF alpha may exert neurotoxic effects on human neurons by indirect activation of AMPA receptors, which may be important in the pathogenesis and treatment of HIV-mediated encephalopathy.

Intravitreal injection of AAV2 transduces macaque inner retina

PURPOSE Adeno-associated virus serotype 2 (AAV2) has been shown to be effective in transducing inner retinal neurons after intravitreal injection in several species. However, results in nonprimates may not be predictive of transduction in the human inner retina, because of differences in eye size and the specialized morphology of the high-acuity human fovea. This was a study of inner retina transduction in the macaque, a primate with ocular characteristics most similar to that of humans. METHODS In vivo imaging and histology were used to examine GFP expression in the macaque inner retina after intravitreal injection of AAV vectors containing five distinct promoters. RESULTS AAV2 produced pronounced GFP expression in inner retinal cells of the fovea, no expression in the central retina beyond the fovea, and variable expression in the peripheral retina. AAV2 vector incorporating the neuronal promoter human connexin 36 (hCx36) transduced ganglion cells within a dense annulus around the fovea center, whereas AAV2 containing the ubiquitous promoter hybrid cytomegalovirus (CMV) enhancer/chicken-β-actin (CBA) transduced both Müller and ganglion cells in a dense circular disc centered on the fovea. With three shorter promoters--human synapsin (hSYN) and the shortened CBA and hCx36 promoters (smCBA and hCx36sh)--AAV2 produced visible transduction, as seen in fundus images, only when the retina was altered by ganglion cell loss or enzymatic vitreolysis. CONCLUSIONS The results in the macaque suggest that intravitreal injection of AAV2 would produce high levels of gene expression at the human fovea, important in retinal gene therapy, but not in the central retina beyond the fovea.

Infectious Endophthalmitis in Adult Eyes Receiving Boston Type I Keratoprosthesis

PURPOSE To report the clinical characteristics of infectious endophthalmitis after Boston type I keratoprosthesis (K-Pro) implantation. DESIGN Retrospective study. PARTICIPANTS One hundred forty-one adult eyes receiving a K-Pro at a single institution from May 2004 through July 2008. METHODS A retrospective chart review was performed of all adult eyes receiving a K-Pro at the University of Rochester from May 2004 through July 2008. Those patients identified as having been treated for exogenous bacterial endophthalmitis were reviewed for demographic data, indication for K-Pro, bandage contact lens use, prophylactic antibiotic use, timing and clinical presentation of endophthalmitis, gram stain and culture results of intraocular fluid, timing and presentation of any subsequent episodes of endophthalmitis (recurrent endophthalmitis), and preoperative and postoperative visual acuity through August 2010. MAIN OUTCOME MEASURES Incidence of endophthalmitis, time to occurrence, recurrence rates, visual outcomes, and risk factors associated with K-Pro endophthalmitis. RESULTS Ten (7.1%) of 141 eyes of 130 adult patients were diagnosed and treated for bacterial endophthalmitis. Average time to endophthalmitis developing after K-Pro was 9.8 months (standard deviation [SD], 6.2 months; range, 2-25 months). Coagulase-negative staphylococci were identified in 7 eyes. In 7 of the 10 eyes, recurrent endophthalmitis developed that occurred at a mean of 4 months (SD, 3.9 months; range, 1-13 months) after resolution of the initial episode. At each episode of endophthalmitis, no eye was receiving vancomycin ophthalmic drops and most eyes were receiving only fluoroquinolone ophthalmic drops for prophylaxis. CONCLUSIONS Infectious endophthalmitis after K-Pro implantation has a higher incidence, delayed onset, and high risk for recurrence compared with postoperative endophthalmitis associated with more common intraocular procedures such as cataract surgery. The concurrent use of topical vancomycin is recommended because it seems to be important in reducing the incidence and recurrence of endophthalmitis and because fluoroquinolone ophthalmic drops do not seem to be sufficient prophylaxis in these eyes.

Differentiation of Y79 retinoblastoma cells with pigment epithelial-derived factor and interphotoreceptor matrix wash: effects on tumorigenicity.

We investigated the in vivo differentiation potential of Y79 human retinoblastoma cells following pre-treatment with two novel neurotrophic agents: PEDF (human recombinant pigmented-epithelial derived factor) or IPM (interphotoreceptor matrix) wash. These agents were able to induce a significant degree of morphological differentiation in vitro. However, 48 days after subretinal transplantation of pre-treated cells, massive tumor formation was apparent. In contrast, Y79 cells pre-treated with retinoic acid/sodium butyrate, which attain a lesser degree of morphological differentiation, did not produce tumors over a 30 to 60 day-survival time (del Cerro et al., Brain Research, 12-22, 1992). We conclude that for PEDF and IPM, the degree of in vitro differentiation and the degree of mitotic arrest are independent features.

The first decade of continuous progress in retinal transplantation

In recent months, neural fetal retina has been transplanted into blind human patients affected by Retinitis Pigmentosa. Initial success, as documented by improved visual activity, has been reported (del Cerro et al., Neuroscience Abstract, 1996). With the rapid progress in human patients, additional questions are arising concerning transplantation issues. Additional answers and further success in treating clinical disease will necessarily come from new laboratory research in animal models as well as in vitro systems. This increases the need for evaluation of the data already gathered over the first decade of retinal transplantation. The extensive experimental background work that preceded the current wave of human retinal transplants is reviewed in this paper, with particular emphasis given to the work dealing with the transplantation of neural retina. Microsc Res Tech 36:130–141, 1997.

The influences of age, retinal topography, and gender on retinal degeneration in the Fischer 344 rat

The Fischer 344 (F344) rat is presently the animal of choice for age-related research. The existence of an age-related retinal degeneration was reported previously in the males of this strain, but a gender comparison has not been performed. In this study, histological and morphometric measurements of the retina related to age, retinal topography, and gender were made on 3- to 24-month-old animals. The thicknesses of the outer nuclear layer (ONL) and the photoreceptor layer (PRL) were measured from sagittal sections at six loci. Retinas of both sexes showed steady decline with age in the thicknesses of the ONL and PRL at all locations. An important finding was the presence, after 12 months of age, of a drastically accelerated rate of peripheral retinal degeneration seen only in male subjects. Females showed a less dramatic rate of peripheral degeneration which did not begin until after 18 months of age. In addition, two other forms of retinal degeneration were found--cystoid degeneration was found earlier and more frequently in the male, while a paving-stone type of degeneration was found in both sexes. These two types of lesions were preferentially, but not exclusively found in the peripheral retina. In conclusion, the F344 rat offers a convenient model to study a pattern of retinal degeneration affected by the combination of gender, regional and age-related factors.

Solitary nonreactive choroidal tuberculoma in a patient with acquired immune deficiency syndrome.

PURPOSE To report a case of a solitary, nonreactive choroidal tuberculoma in a patient with acquired immune deficiency syndrome (AIDS). METHOD Case Report. RESULTS A 26-year-old male patient with AIDS and systemic tuberculosis was found to have a solitary 1.5-disc-diameter elevated mass just superior and temporal to the optic disc. There was no associated inflammation, exudate, hemorrhage, or serous retinal detachment. Fluorescein angiography showed late hyperfluorescence in a staining pattern. The mass quickly regressed with antituberculosis therapy. CONCLUSIONS Choroidal tuberculoma can present with little associated inflammation or retinal change in a patient with AIDS. The clinical history and knowledge of opportunistic choroidal infections in patients with AIDS helps to make the diagnosis.

A functional analysis of the age-related degeneration in the Fischer 344 rat.

We have previously described how the expression of photoreceptor cell degeneration in the Fischer 344 rat is affected by age, retinal topography, and gender. Degeneration in the central and equatorial regions progresses linearly with age throughout the life span of the animal, while the periphery of the male is subject to sudden and dramatic losses of cells in the superior hemisphere after 12 months and in the inferior hemisphere after 18 months of age. The purpose of the present study was to determine how this degeneration affected retinal function and visual ability in the male Fischer 344 from 3 to 24 months of age. Functional testing included the electroretinogram (ERG, measuring both a-wave and b-wave amplitudes and implicit times) and the behavioral method of startle reflex modification (RM, which measures the degree to which a light flash inhibits the response to an immediately subsequent loud noise). All of the functional measures showed a decline with age, but varied in their time course. ERG amplitudes showed a linear decline in amplitude over the entire age range. In contrast, the implicit times of the ERG waves and the degree to which the light flash inhibited the startle reaction both showed a slight maturation in function (faster implicit times and greater inhibition) from 8 or 12 months of age. After 18 months of age, the implicit time showed a significant increase and the startle response showed a significant decrease. This study shows how visual function correlates with the histopathological changes seen in age-related retinal degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

The Intensity of the Pupillary Light Reflex Does Not Correlate with the Number of Retinal Photoreceptor Cells

The purpose of this study was to determine if the pupillary light reflex (PLR) can serve as an indicator of the number of photoreceptor cells present in the rat retina to a sufficient degree of precision to be useful for testing the functional effects of retinal transplantation. The PLR was measured as percentage constriction of normal Fischer 344 rats (n = 14) and compared to the PLR of light-damaged (1300 luxes/30 days exposure) Fischer rats (n = 13). Additionally, the PLR of RCS-rdy+ (congenic) rats (n = 8) was compared to the PLR or RCS dystrophic rats (n = 7). Three eyes from each group were randomly chosen for morphometry. The number of photoreceptor nuclear profiles per 60 microns of retinal length was counted at six predetermined loci and averaged. The mean PLR of Light-Damaged F344 group (64%) was significantly different from the mean PLR of the Normal F344 group (75%) (P = 0.003). However, the mean PLR of the RCS Dystrophic group (72%) did not differ from the mean PLR of the RCS Congenic group (71%) (P = 0.82). Morphometry revealed that the mean number of photoreceptor nuclear profiles within each group of animals was vastly different: Normal F344 = 138, Light Damaged F344 = 19, Congenic RCS = 93, and Dystrophic RCS = 1. No correlation was found between intensity of PLR and number of photoreceptors present (r = 0.11, P = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)

Late-Onset Bacterial Endophthalmitis Following Glaucoma Drainage Implantation

Abstract. A clinicopathologic report of late-onset bacterial endophthalmitis 4 years after implantation of a Baerveldt drainage implant is described. An 80-yearold woman with glaucoma presented 8 years after tube shunt implantation with clinical endophthalmitis. During surgical removal of the implant, a small conjunctival buttonhole caused by the suture securing the plate to the sclera was noted to be the only entry site. Vitreous and anterior chamber taps were performed with intravitreal antibiotics. Cultures revealed Streptococcus pneumoniae infection. The pathologic analysis showed epithelialization of the conjunctival buttonhole and diffuse ocular inflammation, mucopurulent material, and fibrovascular membranes. Due to severe pain, the eye was enucleated after 1 week. [Ophthalmic Surg Lasers Imaging 2003;34:128-130.].