Reduction by dietary matrix metalloproteinase inhibitor BAY 12-9566N of neoplastic development induced by diethylnitrosamine, N-nitrosodimethylamine, or 7,12-dimethylbenz(a)anthracene in rats.

BAY 12-9566N (BAY), which is a substituted 4-biarylbutyric acid and has the properties of a matrix metalloproteinase (MMP) inhibitor, was tested in the accelerated cancer bioassay (ACB). In the ACB, three different genotoxic carcinogens were administered individually to groups of male and female Wistar rats, in initiation (IN) segments lasting 10 weeks, followed by BAY in promotion segments lasting 42 weeks, for a total of 52 weeks of treatment, followed by 12 weeks of recovery. The IN target organs in males were the liver using diethylnitrosamine (DEN), and the lungs, using N-nitrosodimethylamine (NDA), and in females, the mammary gland using 7,12-dimethylbenz(a)anthracene (DMBA). The study consisted of eight groups of 24 rats each as follows: controls (male and female), DEN alone (male), DEN/BAY (male), NDA (male), NDA/BAY (male), DMBA (female), and DMBA/BAY (female). The daily dose of BAY was 240 mg/kg in the diet, yielding a cumulative dose of 70,560 mg/kg. The cumulative doses of carcinogens were 220 mg/kg DEN, 150 mg/kg NDA, or 15 mg/kg DMBA. No significant difference in body-weight gain pattern was evident between any of the groups at 52 or 64 weeks. Rather, in males, DEN-induced hepatocellular adenomas were reduced with BAY treatment from 29% to 21% (p < 0.05) and carcinomas from 42% to 29% (p < 0.01). Also, in males, NDA-induced pulmonary adenomas were reduced with BAY treatment from 38% to 21% (p < 0.01) and carcinomas from 21% to 4% (p < 0.01). In females, DMBA-induced mammary gland adenomas were reduced from 13% to 4% (p < 0.01) and carcinomas from 54% to 42% (p < 0.05). Thus, BAY produced a consistent and significant reduction of neoplasm development in both genders in three target tissues of carcinogenicity in which neoplasms were induced by three different DNA-reactive initiators. This inhibition may be due to inhibition of MMP, leading to reduced neoplastic growth and development.

Porcine Corneal Ocular Reversibility Assay (PorCORA) predicts ocular damage and recovery for global regulatory agency hazard categories.

In this study, we examined the capacity of the Porcine Corneal Ocular Reversibility Assay (PorCORA) to classify the reversibility of ocular effects for 32 test compounds (20 reversible, 12 irreversible) from various chemical classes. PorCORA predicted 28 of 32 compounds correctly when compared to historical rabbit eye test data. The correlation coefficient for PorCORA versus historical rabbit test data was 0.84, based on the last day of damaged cornea reversal. These results demonstrate a high correlation between corneal irritation recovery time in the PorCORA and the rabbit eye. When compared to historical Modified Maximal Average Score (MMAS) in rabbit eyes, PorCORA yielded a correlation coefficient of 0.80, demonstrating ability to predict MMAS. PorCORA was highly predictive of regulatory agency ocular hazard classification categories, resulting in 91% accuracy for EU R41 and GHS Category 1. PorCORA was also predictive of EPA Category I (88% accuracy). Overall, the accuracy (88-91%), sensitivity (79-86%), specificity (94%), positive predictivity (94%), and negative predictivity (85-89%) for all three regulatory classifications indicate that ocular irritation hazardous effects were well predicted by the PorCORA. This study suggests that PorCORA could help discriminate between EU R36 and R41, GHS Categories 1 and 2, and EPA Categories I and II.

Ocular irritation reversibility assessment for personal care products using a porcine corneal culture assay.

Personal care product manufacturers have used a broad spectrum of alternative ocular irritation assays during the past two decades because these tests do not require the use of live animals, they provide reliable predictive data, and they are relatively inexpensive to conduct. To complement these assays, the ex vivo Porcine Corneal Opacity Reversibility Assay (PorCORA) was recently developed using a corneal culture model to predict reversibility of ocular irritants. Three commercially available consumer products (a shampoo, a hair color glaze, and a hair colorant system containing 12% hydrogen peroxide) were each tested in two PorCORA study replicates in order to assess potential ocular damage reversibility for surfactant-, propylene carbonate-, and peroxide-based formulations, respectively. Under the exaggerated, in vitro study conditions, the surfactant-based shampoo may cause irreversible porcine corneal damage (histological changes in the epithelial squamous cell and/or basal cell layers), whereas the hair color glaze and 12% hydrogen peroxide product caused fully reversible ocular irritation (microscopic changes only in the superficial squamous cell layer). The hair color glaze and peroxide product results correlate with established in vivo data for similar compounds, but the shampoo results contradicted previous BCOP results (expected to be only a mild irritant). Therefore, although the PorCORA protocol shows promise in predicting the extent and reversibility of potential ocular damage caused by accidental consumer eye exposure to personal care products, the contradictory results for the surfactant-based shampoo indicate that more extensive validation testing of the PorCORA is necessary to definitively establish the protocol's reliability as a Draize test replacement.

Novel cultured porcine corneal irritancy assay with reversibility endpoint.

Several alternative assays exist to assess ocular irritancy without the use of live animals. However, these assays cannot address ocular injury reversibility. Reversibility is an issue critical to regulatory authorities and manufactures of commercial products, as ocular irritation caused by misuse or accidental exposure to a product may cause irreversible eye damage. Here we report the development and initial characterization of a novel ocular irritation assay that addresses ocular injury reversibility. This assay, the Porcine Corneal Ocular Reversibility Assay (PorCORA), uses an air-interface porcine corneal culture system to sustain ex vivo porcine corneas as a model system. These corneas are maintained in culture for 21 days to determine if cornea injury, once inflicted, will reverse. Corneal injury reversibility is measured using Sodium Fluorescein (NaFl) stain to detect compromised epithelial barrier function. In this study, we examined the effects of five compounds on the cultured corneas: phosphate-buffered saline (PBS), 100% Ethanol (EtOH), 3% Sodium Dodecyl Sulfate (SDS), 1% Benzalkonium Chloride (BAK), and 10% Sodium Hydroxide (NaOH). Overall, the persistence of corneal effects between historical Draize rabbit eye data and PorCORA indicates a correlation coefficient of 0.98 (for the five compounds tested) and a correlation coefficient of 0.97 with the Draize modified maximal average score (MMAS). Finally, both fluorescence confocal microscopy and histopathology evidence demonstrates that the PorCORA and NaFl measurements are indicative of actual cellular and tissue damage. PorCORA shows promise as a potential non-animal replacement assay capable of predicting ocular damage reversibility.