Prediction Intervals for Overdispersed Poisson Data and Their Application in Medical and Pre-Clinical Quality Control.

In pre-clinical and medical quality control, it is of interest to assess the stability of the process under monitoring or to validate a current observation using historical control data. Classically, this is done by the application of historical control limits (HCL) graphically displayed in control charts. In many applications, HCL are applied to count data, for example, the number of revertant colonies (Ames assay) or the number of relapses per multiple sclerosis patient.

Toxicological inhalation studies in rats to substantiate grouping of zinc oxide nanoforms.

Background: Significant variations exist in the forms of ZnO, making it impossible to test all forms in in vivo inhalation studies. Hence, grouping and read-across is a common approach under REACH to evaluate the toxicological profile of familiar substances. The objective of this paper is to investigate the potential role of dissolution, size, or coating in grouping ZnO (nano)forms for the purpose of hazard assessment.

In vivo alkaline comet assay: Statistical considerations on historical negative and positive control data.

The alkaline comet assay is frequently used as in vivo follow-up test within different regulatory environments to characterize the DNA-damaging potential of different test items. The corresponding OECD Test guideline 489 highlights the importance of statistical analyses and historical control data (HCD) but does not provide detailed procedures. Therefore, the working group "Statistics" of the German-speaking Society for Environmental Mutation Research (GUM) collected HCD from five laboratories and >200 comet assay studies and performed several statistical analyses.

Assessment of the bioaccumulation potential of four commonly used phenolic benzotriazoles based on in silico and experimental in vivo data.

Phenolic benzotriazoles (BTZs) are used globally as light stabilizers in various plastic products to protect them from photooxidative degradation. The same physical-chemical properties that confer their functionality, like a sufficient photostability and a high octanol-water partition coefficient, also raise concerns on their potential for environmental persistence and bioaccumulation based on in silico predictive tools. To evaluate their bioaccumulation potential in aquatic organisms, standardized fish bioaccumulation studies according to OECD TG 305 were conducted with four of the most commonly used BTZs: UV 234, UV 329, UV P, and UV 326.

Body and organ weight data in 28-day toxicological studies in two mouse strains.

Toxicological studies were performed in an AAALAC (American Association for Laboratory Animal Care)-approved laboratory at BASF SE, Ludwigshafen, Germany, in accordance with the German Animal Welfare Act and the effective European Council Directive 2010/63/EU. Data were recorded in the BASF SE pathology data capture system. Historical control data (2008-2013) were compiled for a) Twelve 28-day studies performed according to OECD 407 with mice from Janvier C57BL/j Rj (J) and Charles River CD-1 (CRL), in total 73 control females and 73 control males, 5-8 weeks old at the beginning of the studies.

Variance of body and organ weights in 28-day studies in mice.

The OECD guideline 407 outlines the conduct of 28-day studies in rodents to detect systemic toxicity with focus on endocrine and immunotoxic effects. It was validated with the rat as preferred model species. Justification is required for other rodent species, as an increased variability is expected compared to the rat.

Is normalized hindlimb length measurement in assessment of thyroid disruption in the amphibian metamorphosis assay relevant?

The amphibian metamorphosis assay represents an OECD Level 3 and EDSP Tier 1 ecotoxicity test assessing thyroid activity of chemicals in African clawed frog (Xenopus laevis). To evaluate the effectiveness of snout-vent length (SVL) normalization of hindlimb length (HLL), correlation between the HLL and SVL or body weight was evaluated in the control groups of 10 individual studies from three laboratories. Two studies required separate analysis of the Nieuwkoop-Faber (NF) stage ≤60 and >60 animals creating a total of 12 data sets.

The rat bone marrow micronucleus test: Statistical considerations on historical negative control data.

Recent updates of the OECD Guidelines for the Testing of Chemicals (Section 4: Health Effects) on genotoxicity testing emphasize the use of appropriate statistical methods for data analysis and proficiency proof. Updates also concern the mammalian erythrocyte micronucleus test (OECD 474), as the currently most often performed regulatory in vivo test. As the updated guideline gives high importance to adequate statistical assessment of historical negative control data to estimate validity of experiments and judge results, the present study evaluated statistical methodologies for handling of historical negative control data sets, and comes forward with respective proposals and reference data.

Acetylcholinesterase measurement in various brain regions and muscles of juvenile, adolescent, and adult rats.

Several insecticides, chemicals, and drugs are known to inhibit acetylcholinesterase (AChE) activity, responsible for the cleavage of the neurotransmitter acetylcholine. The administration of AChE inhibitors leads to typical parasympathomimetic (toxic) symptoms in rats. In order to differentiate between compounds acting in various regions of the brain or in peripheral nerves, regulatory authorities demand the measurement of AChE activity in different compartments and the study of potential toxicity at different developmental stages.

Immunophenotyping does not improve predictivity of the local lymph node assay in mice.

The local lymph node assay (LLNA) is a regulatory accepted test for the identification of skin sensitizing substances by measuring radioactive thymidine incorporation into the lymph node. However, there is evidence that LLNA is overestimating the sensitization potential of certain substance classes in particular those exerting skin irritation. Some reports describe the additional use of flow cytometry-based immunophenotyping to better discriminate irritants from sensitizing irritants in LLNA.

Effect of estrogenic binary mixtures in the yeast estrogen screen (YES).

Endocrine disrupting compounds (EDCs) of natural or synthetic origin can interfere with the balance of the hormonal system, either by altering hormone production, secretion, transport, or their binding and consequently lead to an adverse outcome in intact animals. An important aspect is the prediction of effects of combined exposure to two or more EDCs at the same time. The yeast estrogen assay (YES) is a broadly used method to assess estrogenic potential of chemicals.

Applicability of rat precision-cut lung slices in evaluating nanomaterial cytotoxicity, apoptosis, oxidative stress, and inflammation.

The applicability of rat precision-cut lung slices (PCLuS) in detecting nanomaterial (NM) toxicity to the respiratory tract was investigated evaluating sixteen OECD reference NMs (TiO₂, ZnO, CeO₂, SiO₂, Ag, multi-walled carbon nanotubes (MWCNTs)). Upon 24-hour test substance exposure, the PCLuS system was able to detect early events of NM toxicity: total protein, reduction in mitochondrial activity, caspase-3/-7 activation, glutathione depletion/increase, cytokine induction, and histopathological evaluation. Ion shedding NMS (ZnO and Ag) induced severe tissue destruction detected by the loss of total protein.

Anti-androgenicity can only be evaluated using a weight of evidence approach.

Preputial separation (PPS) is a commonly used external marker for the onset of male puberty in experimental animal studies. While treatment-related delays in PPS may be indicative of specific anti-androgenic activity, impaired general growth also alters the onset of puberty. To differentiate between specific and non-specific effects on the age at PPS--and thereby evaluate the validity of the endpoint PPS-two-generation toxicity studies of 23 substances were evaluated.

Health and nutritional status of Wistar rats following subchronic exposure to CV127 soybeans.

This subchronic duration feeding study evaluated the nutritional and health status of rats fed diets containing CV127 at incorporation levels of 11% and 33%. For control comparisons, rats were also exposed to similar incorporation levels of the near isogenic conventional soybean variety (Conquista) and two other conventional soybean varieties (Monsoy, Coodetec). In spite of phenotypic differences among these four soybean varieties, there were no quantitative differences in their respective proximate and other compositional properties, including proteins, amino acids, antinutrients and nutritional cofactors.

ECOSAR model performance with a large test set of industrial chemicals.

The widely used ECOSAR computer programme for QSAR prediction of chemical toxicity towards aquatic organisms was evaluated by using large data sets of industrial chemicals with varying molecular structures. Experimentally derived toxicity data covering acute effects on fish, Daphnia and green algae growth inhibition of in total more than 1,000 randomly selected substances were compared to the prediction results of the ECOSAR programme in order (1) to assess the capability of ECOSAR to correctly classify the chemicals into defined classes of aquatic toxicity according to rules of EU regulation and (2) to determine the number of correct predictions within tolerance factors from 2 to 1,000. Regarding ecotoxicity classification, 65% (fish), 52% (Daphnia) and 49% (algae) of the substances were correctly predicted into the classes "not harmful", "harmful", "toxic" and "very toxic".

The stability of historical control data for common neoplasms in laboratory rats and the implications for carcinogenic risk assessment.

Time-related changes in the incidences of spontaneous neoplasms in skin (fibroma and keratoacanthoma), thyroid (C-cell and follicular cell adenomas/carcinomas), uterus (stromal polyp), testes (Leydig cell tumor) and hemolymphoreticular system (mesenteric lymph node hemangioma and malignant granular lymphocytic leukemia) were assessed statistically in Wistar, Sprague-Dawley and F344 rats employed by the BASF, Germany and major European contract research organizations over the last 20 years. Negative trends (5 out of 80 cases) were observed for skin fibromas in F344 males, for follicular cell adenomas in Han Wistar females and in Sprague-Dawley males and females, and for follicular cell carcinomas in Sprague-Dawley males. Positive trends (8 out of 80 cases) were observed for skin keratoacanthomas in Han Wistar males, for C-cell adenomas in BASF Wistar males and females, for stromal polyps in Han Wistar and Sprague-Dawley females, and for mesenteric lymph node hemangiomas in Han Wistar and Sprague-Dawley males and in BASF Wistar females.

The stability of historical control data for common neoplasms in laboratory rats: adrenal gland (medulla), mammary gland, liver, endocrine pancreas, and pituitary gland.

Time-related changes in the incidences of spontaneous neoplasms in adrenals (medulla), mamma, liver, pituitary, and (endocrine) pancreas were assessed statistically in Wistar, Sprague-Dawley, and F344 rats employed by BASF, Germany and major European contract research organizations over the last 20 years. Negative trends (7 of 80 cases) were observed for pituitary pars distalis adenomas in Sprague-Dawley males and females, for pancreas islet cell adenomas in BASF Wistar males and females, for benign adrenal pheochromocytomas in Sprague-Dawley males, for malignant pheochromocytomas in F344 males, and for mammary gland fibroadenomas in BASF Wistar females. Positive trends (13 of 80 cases) were observed for benign pheochromocytomas, mammary gland adenocarcinomas, and pancreas islet cell carcinomas in HanWistar females, for malignant pheochromocytomas and islet cell carcinomas in BASF Wistar males, for benign pheochromocytomas and islet cell adenomas in F344 males, for mammary gland fibroadenomas in Sprague-Dawley females, and for benign hepatocellular tumors in HanWistar males and females, and in BASF Wistar and Sprague-Dawley females.