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2017 Society of Toxicology Annual Meeting

MB Research Labs - Protecting You Like One of Our Own.

Join Us at the 56th Annual Meeting of the Society of Toxicology and ToxExpo , Baltimore, Maryland, March 12-16, 2017

Industries Served:

MB conducts Good Laboratory Practice (GLP) compliant toxicology assays as well as low-cost screening studies for clients in the cosmetic, consumer product, chemical, biotech and pharmaceutical industries.

About MB Research

MB Research Labs, a Contract Toxicology Testing organization, serves the in vivo and in vitro toxicology testing needs of both government and industry.

Complete support services including consultation, protocol development, quality assurance, analytical chemistry and archive facilities are integral components of studies performed at MB.

Our technical and support procedures are in full compliance with OECD, FDA, and EPA-OCSPP. For more information about our capabilities, please click here.

Scientific Poster Presentations

Wed 1:15pm-4:30pm. Session: Alternatives to Mammalian Models I, Abstract 2748, Poster Board P116
Micheal Carathers, Bennett Varsho, Puneet Vij, and George DeGeorge
  1. MB Research Laboratories, Spinnerstown, PA, United States

In order to explore the applicability domain for more pure chemicals and mixtures (including commercial products), we performed a series of studies using the Human Cell Line Activation Test (h-CLAT) protocol under the latest OECD Test Guideline. THP-1 cell expression of CD86 and CD54 from a new, expanded set of validation chemicals and several complex mixtures were measured. A variety of products from the petroleum, agrochemical, food, beauty and chemical industries, were obtained via retail outlets and evaluated. Known positive (via safety data sheets) mixtures were assessed along with similar non-sensitizing mixtures. These included: non-PPD containing hair dye, propolis extract, diesel fuel additive, a pesticide, and commercial acrylate-based sealants. In addition to mixtures, we evaluated the OECD proficiency test chemicals, which includes DNCB, Phenylenediamine, Nickel Sulfate, 2-Mercaptobenzothiazole, R(+)Limonene, Imidazolidinyl Urea, and the non-sensitizers Lactic Acid, Isopropanol, Glycerol, and 4-Aminobenzoic Acid. All chemicals were able to be exposed at a low or non-irritating concentration, yielding a CV75 or higher viability, as determined by flow cytometry. Sensitizer potency was measured by the concentration of test chemical that induced a Relative Fluorescence Intensity (RFI) that was a threshold positive response (CD86 = 200%, CD54 = 150%) of control. Two sets of draft OECD guidelines proficiency chemicals were tested for a total of 15 pure chemicals (6 non-sensitizers and 9 sensitizers). The h-CLAT correctly predicted 9 of 9 sensitizing and 5 of 6 non-sensitizing chemicals, for an overall Accuracy of 93.7%.

Wed 1:15pm to 4:30pm. Session: Autoimmunity/Hypersensitivity, Abstract 2957, Poster Board P508
Matthew Troese1, Bennett Varsho1, Dirk Weisensee2 and George DeGeorge1
  1. MB Research Laboratories, Spinnerstown, PA, United States
  2. Cell Systems® Biotechnologie Vertrieb GmbH, Troisdorf, Germany

Human skin models release IL-18 in response to a wide range of dermal sensitizing chemicals. Using a 3D skin model (epiCS®) in the In Vitro Sensitization Assay (IVSA), we measured IL-18 secretion as a biomarker of sensitization. In this test model we are able to achieve 90% accuracy when testing 20 pure test chemicals (11 sensitizers, 7 non-sensitizing irritants and 2 non-toxic materials). Further analysis of the data revealed that test chemical concentrations that induced a 2-fold increase in IL-18 secretion (Stimulation Index; SI-2) allowed for derivation of potency categorizations. The IL-18 SI-2 was directly proportional to the potency of the sensitizer. A limitation of all other OECD-validated in vitro sensitization assays is that test substances that are mixtures are often not compatible with the test system. An advantage of the RhE tissues is that they can be topically dosed, like skin, with a wide variety of substances, such as liquids, gels, powders, and waxes. Next, we explored the feasibility of expanding IVSA’s applicability domain. We obtained sensitizing and non-sensitizing mixtures (as listed on their SDS documents) from several commercial sources used in different industries for assessment. These included hair dyes, caulking material, adhesives, antimicrobial fuel additive and propolis (dietary supplement). A positive response (SI≥2) was detected for all the known sensitizing mixtures. In summary, the IVSA was able to correctly distinguish pure sensitizing chemicals and mixtures from non-sensitizing materials with high Accuracy and Sensitivity.

Tues 9:30am-12:45am. Session: Non-Phamaceutical Safety Assessment, Abstract 1873, Poster Board P449
Bennett Varsho, Micheal Carathers, Debra Hall and George DeGeorge
  1. MB Research Laboratories, Spinnerstown, PA, United States

In the mid-1990s, government regulators moved from allowing the use of strong potency positive control agents in animal studies for dermal sensitization to requiring the use of weak to moderate sensitizers. This shift arose from the desire to prove that the performing laboratories could demonstrably identify weak to moderate sensitizers under their specific testing conditions, thereby reducing concerns regarding false negatives. Twenty years later, the recommended replacement agents, including those used in the authors’ laboratory (mercaptobenzothiazole [MBT] and hexylcinnamaldehyde [HCA]), are in widespread use and indeed demonstrate the test methods’ capacity to identify weak to moderate sensitizers. In the authors’ laboratory, the Magnusson and Kligman Guinea Pig Maximization Test (GPMT) returns 30-45% positive responders with MBT, while the Buehler Method returns 20-65% positive responders with HCA. In the Murine Local Lymph Node Assay, a concentration of 25% HCA returns 40-100% positive responders using both the flow cytometric method and the more recent BrdU-ELISA method. Factors potentially affecting positive response rates, including induction and/or challenge concentrations, vehicle effects, and animal strain are compared and reported in detail.

Wed 1:15pm-4:30pm. Session: Alternatives to Mammalian Models I, Abstract 2761, Poster Board P129
Micheal Carathers, Puneet Vij, Blair Yasso, Bennett Varsho, Edwin Delacruz, George DeGeorge
  1. MB Research Laboratories, Spinnerstown, PA, United States

The important classification of severe ocular irritation as distinct from corrosion is traditionally determined by assessing reversibility of damage to the corneal epithelium over time in live rabbits (The Draize Test). Currently, there are no regulatory accepted alternative (non-rabbit) ocular irritation assays that are capable of assessing both corneal tissue damage and reversibility (healing). The Bovine Corneal Opacity and Permeability (BCOP) assay predicts a corrosive classification if the In Vitro Irritation Score (IVIS) is > 55; however, materials in this category that may cause reversible (non-corrosive) damage in the Draize Rabbit Eye Test are overclassified. This overclassification can lead to inaccurate hazardous shipping labels and increased manufacturing and distribution costs.
Here, we demonstrate the feasibility of a dual assay system for distinguishing corrosive materials from those merely moderately to severely irritating. Twenty-one chemicals with known EPA ocular toxicity classifications (based on rabbit data) were evaluated using the BCOP assay. Chemicals with an IVIS ≥ 20 were to be considered moderately irritating to corrosive and were further assayed in the Porcine Cornea Opacity Reversibility Assay (PorCORA). The PorCORA uses excised porcine corneas that are maintained in culture for up to 21 days. Test chemicals are topically dosed on the corneal epithelium and assessed for damage by fluorescent dye stain retention, similarly to the Draize method. Test chemicals causing stain retention persisting until Day 21 were deemed corrosive (EPA Cat. 1). If the stain retention cleared before Day 21, the test chemical was classified a severe irritant (EPA Cat. 2). Of the 21 chemicals tested, 6/6 Category 1 chemicals induced irreversible damage in the PorCORA, while ocular damage caused by 15/15 Category 2 and Category 3 (IVIS ≥ 20 to 55) chemicals completely reversed by Day 21.
This dual ex vivo assay system fulfills an unmet need under current ocular hazard regulatory test guidelines by providing a non-live-animal (ex vivo) approach to resolving the differences between corrosive (EPA Cat. 1) and severely irritating (EPA Cat. 2) chemicals.