Monitoring Mixture Effects of Neurotoxicants in Surface Water and Wastewater Treatment Plant Effluents with Neurite Outgrowth Inhibition in SH-SY5Y Cells.

Cell-based assays covering environmentally relevant modes of action are widely used for water quality monitoring. However, no high-throughput assays are available for testing developmental neurotoxicity of water samples. We implemented an assay that quantifies neurite outgrowth, which is one of the neurodevelopmental key events, and cell viability in human neuroblastoma SH-SY5Y cells using imaging techniques.

Impact of Endodontic Irrigant Activation on Smear Layer Removal and Surface Disintegration of Root Canal Dentine In Vitro.

The objective of this study was to compare the ability of different endodontic irrigation activation methods to enable irrigant penetration, remove the smear layer from root canal walls after preparation, and investigate surface effects on dentine. Root canals of 90 single-rooted teeth were prepared and irrigated with EDTA (17%) and sodium hypochlorite (5%), where both irrigants or sodium hypochlorite only were activated as follows: conventional needle irrigation, ultrasonic activation, sonic activation (EDDY), or laser-based activation (photon-induced photoacoustic streaming/PIPS). For the evaluation of irrigant penetration into dentinal tubules, methylene blue was injected and activated as well.

Endocrine disrupting chemicals entering European rivers: Occurrence and adverse mixture effects in treated wastewater.

In the present study on endocrine disrupting chemicals (EDCs) in treated wastewater, we used chemical and effect-based tools to analyse 56 wastewater treatment plant (WWTP) effluents from 15 European countries. The main objectives were (i) to compare three different receptor-based estrogenicity assays (ERα-GeneBLAzer, p-YES, ERα-CALUX®), and (ii) to investigate a combined approach of chemical target analysis and receptor-based testing for estrogenicity, glucocorticogenic activity, androgenicity and progestagenic activity (ERα-, GR-, AR- and PR-GeneBLAzer assays, respectively) in treated wastewater. A total of 56 steroids and phenols were detected at concentrations ranging from 25 pg/L (estriol, E3) up to 2.

Modeling the Dynamics of Mixture Toxicity and Effects of Organic Micropollutants in a Small River under Unsteady Flow Conditions.

The presence of anthropogenic organic micropollutants in rivers poses a long-term threat to surface water quality. To describe and quantify the in-stream fate of single micropollutants, the advection-dispersion-reaction (ADR) equation has been used previously. Understanding the dynamics of the mixture effects and cytotoxicity that are cumulatively caused by micropollutant mixtures along their flow path in rivers requires a new concept.

Validation of an SH-SY5Y Cell-Based Acetylcholinesterase Inhibition Assay for Water Quality Assessment.

The acetylcholinesterase (AChE) inhibition assay has been frequently applied for environmental monitoring to capture insecticides such as organothiophosphates (OTPs) and carbamates. However, natural organic matter such as dissolved organic carbon (DOC) co-extracted with solid-phase extraction from environmental samples can produce false-negative AChE inhibition in free enzyme-based AChE assays. We evaluated whether disturbance by DOC can be alleviated in a cell-based AChE assay using differentiated human neuroblastoma SH-SY5Y cells.

Di-(2-ethylhexyl) phthalate substitutes accelerate human adipogenesis through PPARγ activation and cause oxidative stress and impaired metabolic homeostasis in mature adipocytes.

The obesity pandemic is presumed to be accelerated by endocrine disruptors such as phthalate-plasticizers, which interfere with adipose tissue function. With the restriction of the plasticizer di-(2-ethylhexyl)-phthalate (DEHP), the search for safe substitutes gained importance. Focusing on the master regulator of adipogenesis and adipose tissue functionality, the peroxisome proliferator-activated receptor gamma (PPARγ), we evaluated 20 alternative plasticizers as well as their metabolites for binding to and activation of PPARγ and assessed effects on adipocyte lipid accumulation.

Impact of various aeration strategies on the removal of micropollutants and biological effects in aerated horizontal flow treatment wetlands.

Two aerated horizontal subsurface flow treatment wetlands were studied over two years for the removal efficacy with respect of conventional wastewater parameters, micropollutants and effect-based methods. One wetland served as control and was aerated 24 h d across 100% of the fractional length of the system. The second aerated horizontal flow treatment wetland was investigated under several aeration modes: first year with a zone of 85% aeration, followed by five months with a zone of 50% aeration and six months with a zone of 35% aeration.

Inhibition of neurite outgrowth and enhanced effects compared to baseline toxicity in SH-SY5Y cells.

Early life exposure to environmental chemicals can cause developmental neurotoxicity (DNT). The impairment of key neurodevelopmental processes such as neurite outgrowth inhibition can be used as endpoints for screening of DNT effects. We quantified neurite-specific effects using the ratio of effect concentrations for cytotoxicity and neurite outgrowth inhibition (SR).

Critical Membrane Concentration and Mass-Balance Model to Identify Baseline Cytotoxicity of Hydrophobic and Ionizable Organic Chemicals in Mammalian Cell Lines.

All chemicals can interfere with cellular membranes and this leads to baseline toxicity, which is the minimal toxicity any chemical elicits. The critical membrane burden is constant for all chemicals; that is, the dosing concentrations to trigger baseline toxicity decrease with increasing hydrophobicity of the chemicals. Quantitative structure-activity relationships, based on hydrophobicity of chemicals, have been established to predict nominal concentrations causing baseline toxicity in human and mammalian cell lines.

Toxic effects of substituted p-benzoquinones and hydroquinones in in vitro bioassays are altered by reactions with the cell assay medium.

Substituted para-benzoquinones and hydroquinones are ubiquitous transformation products that arise during oxidative water treatment of phenolic precursors, for example through ozonation or chlorination. The benzoquinone structural motive is associated with mutagenicity and carcinogenicity, and also with induction of the oxidative stress response through the Nrf2 pathway. For either endpoint, toxicological data for differently substituted compounds are scarce.

Alternatives for the worse: Molecular insights into adverse effects of bisphenol a and substitutes during human adipocyte differentiation.

Bisphenol A (BPA), which is used in a variety of consumer-related plastic products, was reported to cause adverse effects, including disruption of adipocyte differentiation, interference with obesity mechanisms, and impairment of insulin- and glucose homeostasis. Substitute compounds are increasingly emerging but are not sufficiently investigated.We aimed to investigate the mode of action of BPA and four of its substitutes during the differentiation of human preadipocytes to adipocytes and their molecular interaction with peroxisome proliferator-activated receptor γ (PPARγ), a pivotal regulator of adipogenesis.

Removal of micropollutants and biological effects by conventional and intensified constructed wetlands treating municipal wastewater.

Seven treatment wetlands and a municipal wastewater treatment plant (WWTP) were weekly monitored over the course of one year for removal of conventional wastewater parameters, selected micropollutants (caffeine, ibuprofen, naproxen, benzotriazole, diclofenac, acesulfame, and carbamazepine) and biological effects. The treatment wetland designs investigated include a horizontal subsurface flow (HF) wetland and a variety of wetlands with intensification (aeration, two-stages, or reciprocating flow). Complementary to the common approach of analyzing individual chemicals, in vitro bioassays can detect the toxicity of a mixture of known and unknown components given in a water sample.

Estrogenicity of chemical mixtures revealed by a panel of bioassays.

Estrogenic compounds are widely released to surface waters and may cause adverse effects to sensitive aquatic species. Three hormones, estrone, 17β-estradiol and 17α-ethinylestradiol, are of particular concern as they are bioactive at very low concentrations. Current analytical methods are not all sensitive enough for monitoring these substances in water and do not cover mixture effects.

Translational Factor eIF4G1 Regulates Glucose Homeostasis and Pancreatic β-Cell Function.

Protein translation is essential for cell physiology, and dysregulation of this process has been linked to aging-related diseases such as type 2 diabetes. Reduced protein level of a requisite scaffolding protein of the initiation complex, eIF4G1, downstream of nutrients and insulin signaling is associated with diabetes in humans and mice. In the current study, we tested the hypothesis that eIF4G1 is critical for β-cell function and glucose homeostasis by genetically ablating eIF4G1 specifically in β-cells in vivo (βeIF4G1 knockout [KO]).

Translational Factor eIF4G1 Regulates Glucose Homeostasis and Pancreatic β-Cell Function.

Protein translation is essential for cell physiology, and dysregulation of this process has been linked to aging-related diseases such as type 2 diabetes. Reduced protein level of a requisite scaffolding protein of the initiation complex, eIF4G1, downstream of nutrients and insulin signaling, is associated with diabetes in both humans and mice. In the present study, we tested the hypothesis that eIF4G1 is critical for β-cell function and glucose homeostasis by genetically ablating eIF4G1 specifically in β-cells (βeIF4G1KO).

Optimization of a pre-metabolization procedure using rat liver S9 and cell-extracted S9 in the Ames fluctuation test.

Many environmental pollutants pose a toxicological hazard only after metabolic activation. In vitro bioassays using cell lines or bacteria have often no or reduced metabolic activity, which impedes their use in the risk assessment. To improve the predictive capability of in vitro assays, external metabolization systems like the liver S9 fraction are frequently combined with in vitro toxicity assays.

IL4I1 Is a Metabolic Immune Checkpoint that Activates the AHR and Promotes Tumor Progression.

Aryl hydrocarbon receptor (AHR) activation by tryptophan (Trp) catabolites enhances tumor malignancy and suppresses anti-tumor immunity. The context specificity of AHR target genes has so far impeded systematic investigation of AHR activity and its upstream enzymes across human cancers. A pan-tissue AHR signature, derived by natural language processing, revealed that across 32 tumor entities, interleukin-4-induced-1 (IL4I1) associates more frequently with AHR activity than IDO1 or TDO2, hitherto recognized as the main Trp-catabolic enzymes.

Cytotoxicity Burst? Differentiating Specific from Nonspecific Effects in Tox21 Reporter Gene Assays.

Background: High-throughput screening of chemicals with reporter gene assays in Tox21 has produced a large database on cytotoxicity and specific modes of action. However, the validity of some of the reported activities is questionable due to the "cytotoxicity burst," which refers to the supposition that many stress responses are activated in a nonspecific way at concentrations close to cell death.

Objectives: We propose a pragmatic method to identify whether reporter gene activation is specific or cytotoxicity-triggered by comparing the measured effects with baseline toxicity.

Assessing the Mixture Effects in Bioassays of Chemicals Occurring in Small Agricultural Streams during Rain Events.

Rain events may impact the chemical pollution burden in rivers. Forty-four small streams in Germany were profiled during several rain events for the presence of 395 chemicals and five types of mixture effects in bioassays (cytotoxicity; activation of the estrogen, aryl hydrocarbon, and peroxisome proliferator-activated receptors; and oxidative stress response). While these streams were selected to cover a wide range of agricultural impacts, in addition to the expected pesticides, wastewater-derived chemicals and chemicals typical for street runoff were detected.

Cellular Metabolism in High-Throughput Reporter Gene Assays and Implications for the Quantitative - Extrapolation.

High-throughput reporter gene assays are increasingly applied to assess the potency of chemicals to alter specific cellular signaling pathways. Genetically modified reporter gene cell lines provide stable readouts of the activation of cellular receptors or transcription factors of interest, but such reporter gene assays have been criticized for not capturing cellular metabolism. We characterized the metabolic activity of the widely applied AREc32 (human breast cancer MCF-7), ARE-bla (human liver cancer HepG2), and GR-bla (human embryonic kidney HEK293) reporter gene cells in the absence and in the presence of benzo[]pyrene (BaP), an AhR ligand known to upregulate cytochrome P450 and .

Maternal paraben exposure triggers childhood overweight development.

Parabens are preservatives widely used in consumer products including cosmetics and food. Whether low-dose paraben exposure may cause adverse health effects has been discussed controversially in recent years. Here we investigate the effect of prenatal paraben exposure on childhood overweight by combining epidemiological data from a mother-child cohort with experimental approaches.

How To Improve the Dosing of Chemicals in High-Throughput Mammalian Cell Assays.

Controlling the exposure of chemicals in mammalian cell assays is an important prerequisite for the application of methods in risk and hazard assessment of chemicals. Existing models require numerous physicochemical and system parameters to quantify the effective concentration in the assay. Synthesizing these studies, this article briefly communicates how the protein-rich supplement in the medium can be utilized to adjust constant and quantifiable exposure concentrations without the need for measurements and complex modeling.

Baseline Toxicity and Volatility Cutoff in Reporter Gene Assays Used for High-Throughput Screening.

Most studies using high-throughput cell-based bioassays tested chemicals up to a certain fixed concentration. It would be more appropriate to test up to concentrations predicted to elicit baseline toxicity because this is the minimal toxicity of every chemical. Baseline toxicity is also called narcosis and refers to nonspecific intercalation of chemicals in biological membranes, leading to loss of membrane structure and impaired functioning of membrane-related processes such as mitochondrial respiration.

Quantification of freely dissolved effect concentrations in in vitro cell-based bioassays.

Improved understanding of chemical exposure in in vitro bioassays is required for quantitative in vitro-in vivo extrapolation (QIVIVE). In this study, we quantified freely dissolved concentrations in medium sampled from in vitro cell-based bioassays (C) for nine chemicals with different hydrophobicity and speciation at the time point of dosing and after an incubation period of 24 h using solid-phase microextraction. The chemicals were tested in two reporter gene assays, the AREc32 assay indicative of the oxidative stress response and the PPARγ-GeneBLAzer assay that responds to chemicals which bind to the peroxisome proliferator-activated receptor gamma.