Systematic variations in immune response-related gene transcript abundance suggest new questions about environmental influences on lacrimal gland immunoregulation.

PURPOSE: Retrospective analyses were undertaken to assess the hypothesis that environmental variables influenced immunophysiological status of lacrimal glands from untreated female rabbits that had been housed out-of-doors until they were acquired for use as controls for experimental studies. MATERIALS AND METHODS: Rabbits were euthanized within 5 days of arrival at University Vivaria. Glands were divided for histology and RNA extraction. Transcript abundances were determined with real time RT-PCR. Sections were stained for CD18 and rabbit thymic lymphocyte antigen. Environmental variables assessed were mean daily high temperature, low humidity, high temperature/low humidity ratio, and days with above average temperature/humidity ratio ("adverse days") during the prior 30 days. RESULTS: Spearman's analyses revealed numerous significant correlations. Numbers of T cells and abundances of mRNAs for CD8; CCL2, and CCL4; IL-1α and IL-1ß; the T(H)1 cytokine, IL-2; and the T(H)2- and B cell cytokines, IL-4, IL-6, IL-10, APRIL, and BAFF, all increased with adverse days, while IFN-γ mRNA abundance decreased. Glands from the group exposed to the most adverse days remained free of immunopathological lesions. Glands from the group exposed to the highest temperatures fell above the regression curves for IL-4, APRIL, and BAFF calculated for the other groups and had significantly higher abundances of mRNAs for prolactin, IL-18, CCL21, CCL28, CXCL8, and CXCL13. One of six glands from this group contained small immune cell aggregates; the others appeared normal. The only gland that presented with frank histopathology was from a group that had experienced benign conditions. CONCLUSIONS: Increasing adverse days correlated with increasing abundances of transcripts, including mRNAs for IL-2, IL-10, and CD8, outside the T(H)1/T(H)2 paradigm. The findings raise intriguing questions as to whether and how such changes might be associated with homeostatic phenomena.

Suppression of lymphocyte proliferation and regulation of dendritic cell phenotype by soluble mediators from rat lacrimal epithelial cells.

Lacrimal epithelial cells appear to constitutively secrete autoantigens to their underling stroma. The present experiments address the hypothesis that they also secrete soluble factors that regulate immune responses. Epithelial cells, spleen cells and lymphocytes were obtained from rabbits or rats and cultured in various configurations. Monocytes from rat bone marrow were matured to dendritic cells (DC) ex vivo. Proliferation was measured by [3H]-thymidine incorporation; surface MHC Class II and CD86 using flow cytometry; and mRNA relative abundances using real time RT-PCR. Microporous culture inserts containing rat lacrimal cells inhibited proliferation of rabbit lymphocytes co-cultured with autologous lacrimal cells and of rat lymphocytes co-cultured with TNF-alpha-stimulated DC. They inhibited CD86 and MHC Class II surface expression by maturating DC and reversed surface expression of CD86 but not MHC Class II by partially matured DC. Subsequent exposure of partially matured DC to mediators from rat lacrimal cells reversed the ability to stimulate lymphocyte proliferation. TGF-beta(1) and IL-10 mRNAs increased somewhat when rat lacrimal cells were isolated but decreased markedly in rabbit lacrimal cells. Antibodies to TGF-beta prevented soluble factors from rat lacrimal cells from inhibiting proliferation of rabbit lymphocytes co-cultured with rabbit lacrimal cells, but recombinant TGF-beta alone did not mimic the soluble factors. IL-10 immunopositivity was detected in epithelial cells of interlobular ducts and occasional interstitial cells in rabbit lacrimal gland. Rat lacrimal epithelial cells secrete TGF-beta and other factors that synergize to suppress lymphocyte proliferation and regulate DC maturation. Interlobular duct epithelial cells in rabbit lacrimal glands may express similar functions.

Autoimmune dacryoadenitis and keratoconjunctivitis induced in rabbits by subcutaneous injection of autologous lymphocytes activated ex vivo against lacrimal antigens.

Autologous peripheral blood lymphocytes (PBL), activated in a mixed cell reaction when co-cultured with purified rabbit lacrimal epithelial cells, are known to induce a Sjögren's-like autoimmune dacryoadenitis and keratoconjunctivitis when injected directly back into the donor animal's inferior lacrimal gland (LG). This study shows that autoreactive lymphocytes injected subcutaneously in a site away from the LG is capable of inducing an autoimmune disease in a rabbit. Induced disease (ID) develops more slowly, taking 4weeks as compared to 2weeks in the direct injection model. Initially, both clinical symptoms and histopathology are less pronounced than in the direct injection ID model, but later the immunocytochemistry shows the same CD4+/CD8+ ratio of 4:1 for both injection methods. The finding that lymphocytes activated against lacrimal antigens can travel or home from the injection site back to the inferior and superior LG, as well as the conjunctiva, suggests that these anatomical sites may have common epitopes that induce pathogenic CD4+ T cells that produce a Sjögren's-like syndrome.

Adenoviral capsid modulates secretory compartment organization and function in acinar epithelial cells from rabbit lacrimal gland.

Although adenovirus (Ad) exhibits tropism for epithelial cells, little is known about the cellular effects of adenoviral binding and internalization on epithelial functions. Here, we examine its effects on the secretory acinar epithelial cells of the lacrimal gland, responsible for stimulated release of tear proteins into ocular fluid. Exposure of reconstituted rabbit lacrimal acini to replication-defective Ad for 16-18 h under conditions that resulted in >80% transduction efficiency did not alter cytoskeletal filament or biosynthetic/endosomal membrane compartment organization. Transduction specifically altered the organization of the stimulated secretory pathway, eliciting major dispersal of rab3D immunofluorescence from apical stores normally associated with mature secretory vesicles. Biochemical studies revealed that this dispersal was not associated with altered rab3D expression nor its release from cellular membranes. Ultraviolet (UV)-inactivated Ad elicited similar dispersal of rab3D immunofluorescence. In acini exposed to replication-defective or UV-inactivated Ad, carbachol-stimulated release of bulk protein and beta-hexosaminidase were significantly (P< or =0.05) inhibited to an extent proportional to the loss of rab3D-enriched mature secretory vesicles associated with these treatments. We propose that the altered secretory compartment organization and function caused by Ad reflects changes in the normal maturation of secretory vesicles, and that these changes are caused by exposure to the Ad capsid.

In vitro susceptibilities of bacterial ocular isolates to fluoroquinolones.

PURPOSE: To evaluate and compare the in vitro antimicrobial activity of levofloxacin versus ciprofloxacin and ofloxacin against ocular isolates from patients with bacterial conjunctivitis. METHODS: The in vitro antimicrobial susceptibilities of ocular isolates to levofloxacin, ofloxacin, and ciprofloxacin were determined using both the agar disk diffusion and broth dilution methods. RESULTS: Disk diffusion susceptibility testing disclosed that 99% (100 of 101 isolates) of gram-negative isolates and 98% (127 of 129 isolates) of gram-positive isolates were susceptible to levofloxacin; 96% (97 of 101 isolates) of gram-negative isolates and 78% (100 of 129 isolates) of gram-positive isolates were susceptible to ofloxacin; and 94% (95 of 101 isolates) of gram-negative isolates and 61% (79 of 129 isolates) of gram-positive isolates were susceptible to ciprofloxacin. Broth dilution testing disclosed that 99% (72 of 73 isolates) of gram-negative isolates and 98% (111 of 113 isolates) of gram-positive isolates were susceptible to levofloxacin; 96% (70 of 73 isolates) of gram-negative isolates and 92% (104 of 113 isolates) of gram-positive isolates were susceptible to ofloxacin; and 95% (69 of 73 isolates) of gram-negative isolates and 82% (93 of 113 isolates) of gram-positive isolates were susceptible to ciprofloxacin. CONCLUSIONS: In this study, levofloxacin demonstrated superior in vitro activity against human bacterial conjunctival isolates compared with either ofloxacin or ciprofloxacin (levofloxacin > ofloxacin > ciprofloxacin).

Proliferation of lacrimal gland acinar cells in primary culture. Stimulation by extracellular matrix, EGF, and DHT.

The study of lacrimal dysfunction and insufficiency, a major cause of dry eye, has been hampered by the inability to induce the proliferation of primary lacrimal acinar cells in vitro. Particularly in light of observations that androgens are able to support the overall size and functional status of the lacrimal glands as well as certain specific lacrimal functions, an in vitro culture system that is permissive for cell proliferation would be most beneficial to study the molecular basis for these processes. Here, we report on the successful establishment of such a system. Using a culture system containing Hepato Stim Medium and Matrigel, we were able to induce the efficient proliferation of primary rabbit lacrimal gland acinar cells with epidermal growth factor (EGF) and dihydrotestosterone (DHT). The generation of this in vitro cell culture system should greatly facilitate study of the regulation of acinar cell function at the molecular and cellular levels.

Expression and activity of cell cycle-regulatory proteins in normal and transformed corneal endothelial cells.

Corneal endothelial cells have a limited capacity for proliferation. Upon transformation with the SV40 large T antigen, however, these cells undergo division and grow rapidly. In order to gain insight into the control mechanisms that determine this proliferative switch, we investigated the expression level and activity of various known cell cycle-regulatory proteins in these cells. Primary human and rabbit corneal endothelial cells were transduced in vitro with a replication-defective adenovirus containing SV40 large T antigen, and subsequently the expression and activity of cell cycle-regulatory proteins was analyzed. Cells transduced with large T antigen exhibited strongly increased activity of cyclin-dependent kinases. This increase correlated with the elevated expression of various cyclin-dependent kinase subunits, such as cyclin A, and to a lesser extent, cyclin D, cdk2, and cdk4. Furthermore, the expression of two cyclin-dependent kinase inhibitors, p21(WAF1) and p27(KIP1), which was high in primary human cells (but not in primary rabbit cells), was strongly reduced in large T-antigen transduced cells. Thus, the remarkably low proliferative activity of normal human corneal endothelial cells appears to be regulated at two levels: the expression of certain cell cycle-regulatory proteins that are essential for cell cycle progression is extremely low (cyclin A) or somewhat low (cdk2 and cdk4); but the amount of p21 and p27, inhibitors of cell cycle progression, is very high. As a consequence, the enzymatic activity of cyclin-dependent kinase is below detectable levels. However, the growth-inhibitory status of these components is clearly reversible: upon transduction with large T antigen, the expression of cyclin A, cyclin D, cdk2, and cdk4 is induced, whereas the expression of p21 and p27 is inhibited, and the cells proliferate. Thus, our study provides insight into the molecular basis of the attenuated proliferation of corneal endothelial cells and suggests potential targets that could be manipulated for the purpose of therapeutic interventions aimed at renewed cell growth.

Inhibition of herpes simplex virus type 1 and adenovirus type 5 by heterocyclic Schiff bases of aminohydroxyguanidine tosylate.

Eleven heterocyclic Schiff bases of aminohydroxyguanidine tosylate (SB-AHGs), compounds I-XI, were tested for antiviral activity against herpes simplex virus type 1 (HSV-1) and adenovirus type 5 (Ad 5) via plaque reduction and virus yield reduction assays. This work was undertaken to test the hypothesis that low molecular weight SB-AHGs (MW < 235 for the free SB) make better antiviral agents than high MW SB-AHGs (MW > 300). The plaque reduction assay method demonstrated that three compounds, I, VII and IX, had moderate activity against HSV-1, with 50% inhibitory concentration (IC50) values of 38.0, 23.5 and 52.1 microM, respectively. Against Ad 5, compounds I, VIII and XI exhibited moderate activity, with IC50 values of 52.7, 19.3 and 5.1 microM, respectively. Among the compounds screened, compound I (1-[(3'-hydroxy-6'-methyl-2'-pyridyl)methylene]amino-3-hydroxyguanidi ne tosylate) was the most promising antiviral candidate, with selectivity indices (SI) of 10.2 (HSV-1) and 7.6 (Ad 5), respectively. Virus yield reduction assays indicated that compound I had less antiviral potency against HSV-1 than against Ad 5. The antiviral effects of compound I at a high input virus multiplicity of infection (MOI > 5) indicated that compound I had effective anti-adenoviral activity at 24 h post infection. This work demonstrated that some of SB-AHGs only have moderate antiviral activities against Ad 5 and HSV-1 viruses. In general, low MW SB-AHGs have low cytotoxicities to the host cells.

Adenovirus infection of the cornea causes histopathologic changes in the lacrimal gland.

PURPOSE: To explore the effects on the lacrimal gland of adenovirus infection of the cornea. METHODS: Rabbit corneas were inoculated with human adenoviruses Ad5, Ad14, or a rabbit adapted form of Ad 5, and in some instances booster inoculations were given. Sections of lacrimal glands removed 21-59 days post-inoculation were immunostained using antibodies against rabbit Class I and Class II MHC molecules, CD4, CD8, CD18, and rabbit thymic lymphocyte antigen (RTLA). Relative numbers of positively stained cells were quantified with a Metamorph image analysis system. RESULTS: RTLA and CD18 antigens were expressed on many interstitial cells in the normal lacrimal gland, but few expressed CD4 or CD8. The number of RTLA+ cells increased by 60-100% after inoculation of Ad5 and after boosting, and CD18+ cells increased from 33-100% after inoculation of Ad5 and after boosting. Booster inoculations also caused focal lymphocytic infiltration. MHC Class I was expressed on interstitial cells and duct epithelium, but not acinar cells, and there was no detectable difference after viral infection. In controls, MHC Class II was localized to a population of interstitial cells and a few acinar cells. A single inoculation of the Ad5 virus did not result in an increase in the total number of MHC Class II-positive cells at 21 days, but inoculation with the rabbit-adapted Ad 5 and booster inoculations caused a 30% increase. CONCLUSIONS: Ad5 and rabbit-adapted Ad5 infection of the cornea induce lymphocytic infiltration in the lacrimal gland, and the effect is enhanced by boosting. There is also an increase in expression of MHC Class II after inoculation with rabbit-adapted Ad5 and with booster inoculations.

Aerosolization of infectious virus by excimer laser.

PURPOSE: To determine the potential for aerosolization of infectious virus present within the tear film during excimer laser photoablation of the cornea. METHODS: Cell monolayers infected with herpes simplex virus or adenovirus, simulating virus-infected corneas, were ablated with the 193-nm excimer laser. Adjacent dishes containing noninfected cell monolayers were subsequently assayed for viral infection. RESULTS: Viral spread to sentinel dishes occurred with both herpes simplex and adenovirus. The titer of virus present in the infected cell monolayers influenced the likelihood of spread to adjacent dishes. The presence of a vacuum aspiration system appeared to influence the direction of virus spread, with dishes located in the direction of the vacuum most likely to contain virus. CONCLUSIONS: The potential for aerosolization of infectious virus exists with photoablation using a large-diameter excimer laser beam. Our experimental design, however, does not prove that spread of infectious virus is likely to occur in the clinical setting. Appropriate measures should be taken to reduce the possibility of the spread of virus from the patient to the surgeon, other medical staff, or other patients.

Immunostimulating polysaccharides from Panax notoginseng.

PURPOSE: The main purpose of this study is to prepare and characterize polysaccharides from Panax notoginseng, investigate their effects on immune system in vitro in order to find new immunostimulants for the prevention and supporting treatment of infection and immunodeficiency related diseases. METHODS: Polysaccharides were extracted with aqueous solution, separated with column chromatography. Their anticomplementary activities were investigated by using human serum and antibody-sensitized sheep red blood cells. Interferon-gamma and tumor necrosis factor inductive activities were studied by using isolated mouse spleen lymphocytes and peritoneal macrophages, respectively. RESULTS: Four polysaccharides, homogeneous in gel-filtration chromatography, were prepared and designated PF3111, PF3112, PBGA11, and PBGA12. Component sugar analysis revealed that they are heteroglycans with MWs ranging from 37 kD to 760 kD, composed of glucose, galactose, arabinose, mannose, and xylose in different molar ratios. Fraction PBGA12 has the most anticomplementary activity which is mediated through both alternative and classical pathways. All the polysaccharides except PBGA11 induced the production of interferon-gamma in the presence of concanavalin A. They induced the production of significant amount of TNF-alpha in cell cultures. CONCLUSIONS: The polysaccharides from P.notoginseng have immunostimulating activities in vitro.

Evaluation of Cidofovir (HPMPC, GS-504) against adenovirus type 5 infection in vitro and in a New Zealand rabbit ocular model.

The antiviral inhibitory activity of Cidofovir [1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine dihydrate, HPMPC, GS-504] against adenovirus type 5 (Ad5) in the New Zealand rabbit ocular replication model was evaluated. The 50% inhibitory dose (ID50) of Cidofovir was determined to be 4.7-9.5 micrograms/ml against four adenoviruses (two Ad5, Ad8 and Ad14) by plaque reduction assay in A549 cells. Twenty-four New Zealand rabbits received intrastromal inoculation and topical application of 2 x 10(6) plaque-forming units (PFU) per eye of Ad5 McEwen, a clinical isolate. Cidofovir was administered topically at three different concentrations twice per day, beginning 16 h postinoculation and continuing for 20 consecutive days. The inhibitory effects were determined by measuring suppression of virus replication and by observation of the clinical effects. Compared to the placebo group, the 1% and 0.5% Cidofovir-treated groups showed significantly reduced Ad5 ocular titers, fewer days of viral shedding and less severe subepithelial opacities (P = 0.0001). The 1% Cidofovir group had the lowest humoral antibody titer against adenovirus antigens, but the difference was not significant (P = 0.24). Cidofovir proved to have potent antiviral activity against adenovirus replication and may have great promise for the treatment of adenovirus infection. Further investigation is recommended.

Studies of adenovirus-induced eye disease in the rabbit model.

PURPOSE: To achieve a better understanding of the pathogenic processes associated with human adenovirus (Ad)-induced ocular disease. METHODS: Growth curves of Ad5 and Ad14 were performed in cell cultures derived from rabbit and human corneal epithelium (CE) and corneal keratocytes (CK). For in vivo studies, rabbit eyes were inoculated intrastromally and topically with 10(6) plaque-forming units per eye of Ad5 and ultraviolet light-inactivated (UV-1) Ad5 or Ad14, and the clinical features of the eyes were evaluated by biomicroscopic slit lamp examinations. Duration and quantitation of virus in tear samples were monitored. Humoral response was evaluated by enzyme-linked immunosorbent assay and serum neutralization titrations. Histopathologic and immunocytochemical staining of frozen corneal tissues was performed to determine the expression of major histocompatibility complex (MHC) class I and II and the presence of CD4+ and CD8+ T lymphocytes and CD18+ cells after the immunopathologic response elicited by virus inoculation. RESULTS: Both Ad5 and Ad14 replicated in all human cell cultures studied. In cells of rabbit origin, Ad5 replicated in cultured CE and CK cells, whereas Ad14 replication appeared restricted. Virus titers in ocular samples from Ad5-inoculated eyes peaked on postinoculation days 3 through 4, with approximately a 100-fold increase in infectious virus in comparison to initial titers. The duration of Ad5 shedding was 8.9 +/- 2.4 days. Ad5, Ad5 UV-I, and Ad14 induced seroconversion and subepithelial opacities. CD4+ and CD8+ T lymphocytes and CD18+ cells were present in these intrastromal immune cell infiltrates. Expression of MHC class I and II was observed in keratocytes and immune cells; MHC class I also was expressed on CE cells in inflamed areas. CONCLUSIONS: Ad5 is capable of replicating in both CE and CK cells of the rabbit eye. The presence of Ad antigens within the corneal stroma originating from infectious virus (Ad5), UV-inactivated virus (Ad5), or nonreplicating infectious virus (Ad14) can elicit indistinguishable immunopathologic responses in the stroma composed of CD4+, CD8+, and CD18+ cells.

Role of adenovirus type 5 early region 3 in the pathogenesis of ocular disease and cell culture infection.

Experimental animal virus replication models make it possible to study the role of viral gene products in adenovirus (Ad)-induced ocular disease. This study tested the hypothesis that the early region 3 (E3) of the human Ad genome plays an important role in the pathogenesis of Ad-induced ocular disease. Both Ad5 wt300, a genetically defined E3+ parent, and Ad5 dl327, a deletion mutant without E3 (E3-), replicated in ocular-derived cell cultures. Ad5 E3+ and Ad8 replicated more efficiently than did Ad5 E3- in cornea and conjunctival cell cultures. Lacrimal gland-derived cell cultures supported human Ad8 replication significantly more efficiently than did either Ad5 E3+ or Ad5 E3-. After intrastromal and topical inoculation of rabbits with either Ad wt300 or Ad dl327, a specific immune response was elicited that coincided with the appearance of subepithelial opacities that mimicked human disease both clinically and histologically. The clinical features (i.e., conjunctivitis, iritis, and corneal edema) were not significantly different for Ad5 E3(+)- and Ad5 E3(-)-induced ocular infection. Ad5 E3(+)- and Ad5 E3(-)-inoculated eyes shed virus for up to 7 and 5 days, respectively, and occasionally established persistent and/or latent infections in corneal, conjunctival, and, infrequently, lacrimal gland cells. Both Ad5 E3+ and Ad5 E3- spread from virus-inoculated animals to the cornea and conjunctiva of normal animals. Under current experimental conditions, expression of the E3 gene does not appear to affect the degree of virulence in ocular disease induced by Ad5 in the rabbit eye model. Deletion of the E3 gene from Ad5 does not make the model more like human disease.

Efficacy and safety of gentamicin and streptomycin in Optisol-GS, a preservation medium for donor corneas.

Increasing reports of gentamicin-resistant bacteria contaminating donor corneas and causing endophthalmitis have indicated that preservation of corneal storage media with 100 micrograms/ml of gentamicin alone needs reevaluation. We investigated the stability and possible cytotoxicity of streptomycin as a supplement to gentamicin in Optisol corneal storage medium. The combination of gentamicin and streptomycin in Optisol solution was stable at room temperature for at least 4 weeks and inhibited the growth of Staphylococcus aureus, S. epidermidis, alpha hemolytic streptococci, Streptococcus Group D, Propionibacterium acnes, Escherichia coli, and diphtheroids, but not Pseudomonas aeruginosa. The addition of vancomycin did not significantly improve the antibacterial effectiveness of the gentamicin and streptomycin combination when stored at 4 degrees C. The growth of 15 of 20 clinical ocular isolates of Ps. aeruginosa was suppressed by the gentamicin-streptomycin combination. Streptomycin in concentrations of up to 1,000 micrograms/ml did not decrease the mitotic activity of corneal endothelial cells as evaluated by the in vitro incorporation of tritiated thymidine or cause cytotoxicity. The addition of 200 micrograms/ml of streptomycin to Optisol corneal storage medium containing 100 micrograms/ml of gentamicin may significantly improve activity against gentamicin-sensitive and gentamicin-resistant contaminants.

Activity of ganciclovir against human adenovirus type-5 infection in cell culture and cotton rat eyes.

The most common causes of acute viral infections of the eye for which there are no effective antiviral drugs are the adenoviruses. Until recently, pathogenesis studies and antiviral drug testing for adenovirus-induced ocular disease were not practical because no animal model was available. However, new animal models for human adenovirus-induced ocular and respiratory infections have now made such studies possible. We assessed the in vitro and in vivo activity of ganciclovir against a genetically defined adenovirus (Ad5 wt 300) known to cause severe ocular disease. The 50% inhibitory dose (ID50) values were determined by plaque reduction assays in human cells. The ID50 values of 47 and 604 microM were determined for ganciclovir and acyclovir, respectively, against Ad5, and 26 and 152 microM, respectively against Ad8. Cotton rats were inoculated bilaterally with 10(5) plaque-forming units per eye and treated topically with ganciclovir (3%, 1%, or 0.3%) or placebo for 21 days. All inoculated eyes were culture positive on days 1-3 with increased infectivity titers, regardless of treatment. However, the incidence, duration, and titer of virus shed in eyes treated with 3% ganciclovir was reduced, and the antiadenovirus enzyme-linked immunosorbent assay titers in serum were lower in these animals. Although these differences were not statistically significant, the observed trend suggested that the highest ganciclovir dose had a suppressive effect on some disease parameters.

Inhibition of human adenoviruses by 1-(2'-hydroxy-5'-methoxybenzylidene)amino-3-hydroxyguanidine tosylate.

Antiviral activities of four Schiff bases of aminohydroxyguanidine, designated ML1, ML4, ATL14 and LK11, were tested against human adenovirus types 5 and 8 (Ad5 and Ad8) in A549 cells by plaque reduction and virus yield reduction methods. Compound (ML1 1-(2'-hydroxy-5'-methoxybenzylidene)amino-3-hydroxyguanidine tosylate gave the best therapeutic indices (TC50/IC50) of 27.2 and 17.8 for Ad5 and Ad8, respectively. Pretreatment of cells with ML1 did not affect the adsorption nor the penetration of virus. Ultrastructure studies showed that only the drug treated infected cells had unidentified irregular shaped electron dense structures that might be drug altered viral macromolecules that were not assembled into complete infectious virus particles. Since these compounds have metal chelating properties, their antiviral activity may involve the early IA (EIA) gene which encodes a viral protein of 289 amino acid which has a zinc finger moiety that is required for its transactivation activity.

Photoinactivation of herpes simplex virus by rose bengal and fluorescein. In vitro and in vivo studies.

Rose bengal and fluorescein are photosensitive dyes in widespread use in the evaluation of ocular surface diseases, including herpes simplex virus (HSV) keratitis. These dyes have recently been shown to penetrate living cells, and rose bengal was previously reported to possess antiviral activity. Several experiments reported herein suggest that these dyes do possess the potential for potent antiviral activity against extracellular virus, but only in the presence of light. Rose bengal is substantially more effective in vitro than fluorescein, and the effect is greater with increasing concentration of dye and duration of light exposure. Electron microscopic evaluation of treated virus showed no structural difference from untreated virus, in spite of 4- to 5-log decreases in virus titer. Intracellular virus was found to be markedly resistant to photoinactivation. In a rabbit model of acute primary HSV keratitis, daily application of topical rose bengal followed by light exposure had no therapeutic effect, although an adverse effect on culture sensitivity testing was seen.

Intraoperative bacterial contamination of the aqueous humor.

Indigenous ocular flora has been presumed to be a source of infectious organisms in postoperative bacterial endophthalmitis. While bacteria have been recovered from the anterior chamber at the time of cataract wound closure in a significant percentage of cases, and bacteria from the vitreous of endophthalmitis cases have appeared genetically to be very similar to bacteria recovered from the adnexa and/or nares at the time of vitrectomy for endophthalmitis, no study has examined the relationship between organisms isolated from the eyelid and conjunctiva, and organisms recovered from the aqueous humor at the time of wound closure. This study examined 59 eyes undergoing cataract and other intraocular surgeries. Cultures of the eyelids and conjunctiva were taken before and after routine preparation with povidone-iodine solution. Cultures also were taken of the aqueous humor at the time of incision into the anterior chamber and at the time of wound closure. No organisms grew from aqueous humor samples taken at the time of incision. However, 13 eyes (22%) grew gram-positive organisms from samples taken at the time of wound closure. Eight of the 13 eyes (62%) had organisms with identical typing and antibiotic sensitivities to organisms isolated from the eyelids and conjunctiva before or after disinfection. This study suggests that a significant number of cases had inoperative bacterial contamination of the aqueous humor by the time of wound closure and that organisms from the eyelids and conjunctiva are an important source of contamination in these cases.

Combination antibiotic supplementation of corneal storage medium.

Gram-positive cocci frequently contaminate donor corneal tissue and represent the most common cause of postkeratoplasty endophthalmitis. Although gentamicin is currently added to corneal storage medium in an effort to decrease bacterial contamination of donor tissue, it has poor or variable in vitro activity against many strains of streptococci and staphylococci. To investigate whether the antibiotic supplementation of corneal storage media could be improved, we surveyed 11 antibiotics for antimicrobial efficacy under simulated storage conditions against gentamicin-resistant strains of Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, and St. viridans. All antibiotics showed markedly reduced activity at 4 C as compared to their predicted activity at 37 C. Bactericidal activity of streptomycin and tobramycin was enhanced by preceding 4 C storage with a three-hour period at room temperature (23 C). Under these conditions, streptomycin showed the best antimicrobial activity of the 11 antibiotics tested. Addition of gentamicin to streptomycin resulted in further improvement of activity against S. aureus and S. epidermidis, whereas the addition of penicillin G to streptomycin enhanced the activity against St. viridans. Optimal antibiotic activity (99% or more killing) against all four isolates of gentamicin-resistant gram-positive cocci was best achieved with the combination of gentamicin, streptomycin, and penicillin G, coupled with a three-hour period at room temperature before 4 C storage.