How omics technologies can contribute to the ‘3R’ principles by introducing new strategies in animal testing

N-Halaminated spermidine-containing polymeric coating enables titanium to achieve dual functions of antibacterial and osseointegration

Titanium (Ti) and its alloys have been widely employed in the treatment of orthopedics and other hard tissue diseases. However, Ti-based implants are bioinert and suffer from bacterial infections and poor osseointegration in clinical applications. Herein, we successfully modified Ti with a porous N-halaminated spermidine-containing polymeric coating (Ti-SPD-Cl) through alkali-heat treatment, surface grafting and chlorination, and it has both excellent antibacterial and osteogenic abilities to significantly enhance osseointegration. The as-obtained Ti-SPD-Cl contains abundant N-Cl groups and demonstrates effective antibacterial ability against S. aureus and E. coli. Meanwhile, due to the presence of the spermidine component and construction of a porous hydrophilic surface, Ti-SPD-Cl is also beneficial for maintaining cell membrane homeostasis and promoting cell adhesion, exhibiting good biocompatibility and osteogenic ability. The rat osteomyelitis model demonstrates that Ti-SPD-Cl can effectively suppress bacterial infection and enhance bone-implant integration. Thus, Ti-SPD-Cl shows promising clinical applicability in the prevention of orthopedic implant infections and poor osseointegration.

Toxicity effects of pesticides based on zebrafish (Danio rerio) models: Advances and perspectives

Pesticides inevitably enter aquatic environments, posing potential risks to organisms. The common aquatic model organism, zebrafish (Danio rerio), are widely used to evaluate the toxicity of pesticides. In this review, we searched the Web of Science database for articles published between 2012 and 2022, using the keywords "pesticide", "zebrafish", and "toxicity", retrieving 618 publications. Furthermore, we described the main pathways by which pesticides enter aquatic environments and the fate of their residues in these environments. We systematically reviewed the toxicity effects of pesticides on zebrafish, including developmental toxicity, endocrine-disrupting effects, reproductive toxicity, neurotoxicity, immunotoxicity, and genotoxicity. Importantly, we summarized the latest research progress on the toxicity mechanism of pesticides to zebrafish based on omics technologies, including transcriptomics, metabolomics, and microbiomics. Finally, we discussed future research prospects, focusing on the combined exposure of multiple pollutants including pesticides, the risk of multigenerational exposure to pesticides, and the chronic toxicity of aquatic nanopesticides. This review provides essential data support for ecological risk assessments of pesticides in aquatic environments, and has implications for water management in the context of pesticide pollution.

The 3Rs in Experimental Liver Disease

Patients with cirrhosis present multiple physiological and immunological alterations that play a very important role in the development of clinically relevant secondary complications to the disease. Experimentation in animal models is essential to understand the pathogenesis of human diseases and, considering the high prevalence of liver disease worldwide, to understand the pathophysiology of disease progression and the molecular pathways involved, due to the complexity of the liver as an organ and its relationship with the rest of the organism. However, today there is a growing awareness about the sensitivity and suffering of animals, causing opposition to animal research among a minority in society and some scientists, but also about the attention to the welfare of laboratory animals since this has been built into regulations in most nations that conduct animal research. In 1959, Russell and Burch published the book "The Principles of Humane Experimental Technique", proposing that in those experiments where animals were necessary, everything possible should be done to try to replace them with non-sentient alternatives, to reduce to a minimum their number, and to refine experiments that are essential so that they caused the least amount of pain and distress. In this review, a comprehensive summary of the most widely used techniques to replace, reduce, and refine in experimental liver research is offered, to assess the advantages and weaknesses of available experimental liver disease models for researchers who are planning to perform animal studies in the near future.

The power of retrotransposons in high-throughput genotyping and sequencing

The use of molecular markers has become an essential part of molecular genetics through their application in numerous fields, which includes identification of genes associated with targeted traits, operation of backcrossing programs, modern plant breeding, genetic characterization, and marker-assisted selection. Transposable elements are a core component of all eukaryotic genomes, making them suitable as molecular markers. Most of the large plant genomes consist primarily of transposable elements; variations in their abundance contribute to most of the variation in genome size. Retrotransposons are widely present throughout plant genomes, and replicative transposition enables them to insert into the genome without removing the original elements. Various applications of molecular markers have been developed that exploit the fact that these genetic elements are present everywhere and their ability to stably integrate into dispersed chromosomal localities that are polymorphic within a species. The ongoing development of molecular marker technologies is directly related to the deployment of high-throughput genotype sequencing platforms, and this research is of considerable significance. In this review, the practical application to molecular markers, which is a use of technology of interspersed repeats in the plant genome were examined using genomic sources from the past to the present. Prospects and possibilities are also presented.

Evaluation of the EPR Effect in the CAM-Model by Molecular Imaging with MRI and PET Using 89Zr-Labeled HSA

Mouse models are commonly used to study the biodistribution of novel radioligands, but alternative models corresponding to the 3Rs principles, such as the chorioallantoic membrane (CAM) model, are highly required. While there are promising data from the CAM model regarding target-specific radiolabeled compounds, its utility for assessing macromolecule biodistribution and analyzing the EPR effect remains to demonstrated. Using ⁸⁹Zr-labeled human serum albumin, the accumulation of nontarget-specific macromolecules in CAM and mouse xenograft models was studied using PET and MRI. Therefore, the radioligand [⁸⁹Zr]Zr-DFO-HSA was analyzed in both chicken embryos (n = 5) and SCID mice (n = 4), each with TZM-bl and PC-3 tumor entities. Dynamic PET and anatomical MRI, as well as ex vivo biodistribution analyses, were performed to assess ligand distribution over 24 h. Histological staining and autoradiography verified the intratumoral accumulation. The tumors were successfully visualized for CAM and mouse models by PET, and the albumin influx from the blood into the respective tumors did not differ significantly. The accumulation and retention of HSA in tumors due to the EPR effect was demonstrated for both models. These results highlight that the CAM model is a potential alternative to the mouse model for initial studies with novel radiolabeled macromolecules with respect to the 3Rs principles.

Pilot testing and optimization of a larval fathead minnow high throughput transcriptomics assay

Concentrations at which global gene expression profiles in cells or animals exposed to a test substance start to differ significantly from those of controls have been proposed as an alternative point of departure for use in screening level hazard assessment. The present study describes pilot testing of a high throughput compatible transcriptomics assay with larval fathead minnows. One day post hatch fathead minnows were exposed to eleven different concentrations of three metals, three selective serotonin reuptake inhibitors, and four neonicotinoid-like compounds for 24 h and concentration response modeling was applied to whole body gene expression data. Transcriptomics-based points of departure (tPODs) were consistently lower than effect concentrations reported in apical endpoint studies in fish. However, larval fathead minnow-based tPODs were not always lower than concentrations reported to elicit apical toxicity in other aquatic organisms like crustaceans or insects. Random in silico subsampling of data from the pilot assays was used to evaluate various assay design and acceptance considerations such as transcriptome coverage, number of replicate individuals to sequence per treatment, and minimum number of differentially expressed genes to produce a reliable tPOD estimate. Results showed a strong association between the total number of genes for which a concentration response relationship could be derived and the overall variability in the resulting tPOD estimates. We conclude that, for our current assay design and analysis pipeline, tPODs based on fewer than 15 differentially expressed genes are likely to be unreliable for screening and that interindividual variability in gene expression profiles appears to be a more significant driver of tPOD variability than sample size alone. Results represent initial steps toward developing high throughput transcriptomics assays for use in ecological hazard screening.

Exposure to GenX and its novel analogs disrupts fatty acid metabolism in male mice

Perfluoroalkyl ether carboxylic acids (PFECAs), including hexafluoropropylene oxide dimer acid (HFPO-DA, GenX), have been widely used as alternatives to perfluorooctanoic acid (PFOA) and subsequently detected in various environmental matrices. Despite this, public information regarding their hepatotoxicity remains limited. Here, to compare the hepatotoxicity of PFECAs and identify better alternatives for GenX, adult male mice were exposed to different concentrations (0.4, 2, and 10 mg/kg/d) of PFOA, GenX, and its analogs (PFMO2HpA and PFMO3NA) for 28 d. Results demonstrated increased hepatomegaly and disturbed fatty acid metabolism with increasing treatment doses. After dimensionality reduction analysis, significant differences were observed in the relative liver weights and liver and serum biochemical parameters among the four clusters. Furthermore, when chemical concentrations in the liver were similar, no differences in the indicators of liver injury associated with fatty acid metabolism were observed among groups in the same clusters. Our results suggest that dimensionality reduction analysis is a useful strategy for analyzing samples exposed to multiple compounds at different doses. Furthermore, PFECAs exhibit similar hepatotoxicities at the same cumulative hepatic concentration in mice with constant body weight, while PFMO2HpA exhibits lower hepatotoxicity compared to GenX at the same dose.

Advantages of omics technology for evaluating cadmium toxicity in zebrafish

In the last decade, several advancements have been made in omics technologies and they have been applied extensively in diverse research areas. Especially in toxicological research, omics technology can efficiently and accurately generate relevant data on the molecular dynamics associated with adverse outcomes. Toxicomics is defined as the combination of toxicology and omics technologies and encompasses toxicogenomics, toxicoproteomics, and toxicometabolomics. This paper reviews the trend of applying omics technologies to evaluate cadmium (Cd) toxicity in zebrafish (D. rerio). Cd is a toxic heavy metal posing several environmental concerns; however, it is being used widely in everyday life. Zebrafish embryos and larvae are employed as standard models for many toxicity tests because they share 71.4% genetic homology with humans. This study summarizes the toxicity of Cd on the nerves, liver, heart, skeleton, etc. of zebrafish and introduces detailed omics techniques to understand the results of the toxicomic studies. Finally, the trend of toxicity evaluation in the zebrafish model of Cd based on omics technology is presented.

Strategies to apply 3Rs in preclinical testing

Animal experimentation has been fundamental in biological and biomedical research. To guarantee the maximum quality, efficacy and/or safety of products intended for the use in humans in vivo testing is necessary; however, for over 60 years, alternative methods have been developed in response to the necessity to reduce the number of animals used in experimentation, to guarantee their welfare; resorting to animal models only when strictly necessary. The three Rs (Replacement, Reduction, and Refinement), seek to ensure the rational and respectful use of laboratory animals and maintain an adequate projection in terms of bioethical considerations. This article describes different approaches to apply 3Rs in preclinical experimentation for either research or regulatory purposes.

Determining the Biological Mechanisms of Action for Environmental Exposures: Applying CRISPR/Cas9 to Toxicological Assessments

Toxicology is a constantly evolving field, especially in the area of developing alternatives to animal testing. Toxicological research must evolve and utilize adaptive technologies in an effort to improve public, environmental, and occupational health. The most commonly cited mechanisms of toxic action after exposure to a chemical or particle test substance is oxidative stress. However, because oxidative stress involves a plethora of genes and proteins, the exact mechanism(s) are not commonly defined. Exact mechanisms of toxicity can be revealed using an emerging laboratory technique referred to as CRISPR (clustered regularly interspaced short palindromic repeats). This article reviews the most common CRISPR techniques utilized today and how each may be applied in Toxicological Sciences. Specifically, the CRISPR/CRISPR-associated protein complex is used for single gene knock-outs, whereas CRISPR interference/activation is used for silencing or activating (respectively) ribonucleic acid. Finally, CRISPR libraries are used for knocking-out entire gene pathways. This review highlights the application of CRISPR in toxicology to elucidate the exact mechanism through which toxicants perturb normal cellular functions.

The 3Rs Principle in Animal Experimentation: A Legal Review of the State of the Art in Europe and the Case in Italy

The aim of this paper is to describe the essential points of Italian and European legislation governing the use of animals in biomedical experimentation. A close look will be taken at the principles of the 3Rs, which represent the mainstay of the legal architecture based on which a correct interpretation may be drawn of the legislative documents on animal experimentation. Furthermore, this paper will address the ways in which Directive 2010/63/EU is implemented in Italian legislation on the welfare of laboratory animals. In addition to an assessment of legal issues (such as the scope of jurisdiction of supervisory authorities tasked with issuing authorizations), it will include a discussion of cases of inadequate and insufficient implementation of the requirements laid down by Directive 2010/63/EU. Both the consistency of the interpretation of national legislation with the Directive and the direct effectiveness of the Directive in national law, in which animal testing has been and still is the subject of heated debate between supporters and opponents, will be examined.

Covalent grafting of hyperbranched poly-L-lysine on Ti-based implants achieves dual functions of antibacteria and promoted osteointegration in vivo

The dual functional implants of antibacteria and osteointegration are highly demanded in orthopedic and dentistry, especially for patients who suffer from diabetes or osteoporosis simultaneously. However, there is lack of the facile and robust method to produce clinically applicable implants with this dual function although coatings possessing single function have been extensively developed. Herein, hyperbranched poly-L-lysine (HBPL) polymers were covalently immobilized onto the alkali-heat treated titanium (Ti) substrates and implants by using 3-glycidyloxypropyltrimethoxysilane (GPTMS) as the coupling agent, which displayed excellent antibacterial activity against S. aureus and E. coli with an efficiency as high as 89.4% and 92.2% in vitro, respectively. The HBPL coating also significantly promoted the adhesion, spreading, proliferation and osteogenic differentiation of MC3T3-E1 cells in vitro. Furthermore, the results of a S. aureus infection rat model in vivo ulteriorly verified that the HBPL-modified screws had good antibacterial and anti-inflammatory abilities at an early stage of implantation and better osteointegration compared with the control Ti screws.

Predicting Cytotoxicity of Metal Oxide Nanoparticles using Isalos Analytics Platform

A literature curated dataset containing 24 distinct metal oxide (MexOy) nanoparticles (NPs), including 15 physicochemical, structural and assay-related descriptors, was enriched with 62 atomistic computational descriptors and exploited to produce a robust and validated in silico model for prediction of NP cytotoxicity. The model can be used to predict the cytotoxicity (cell viability) of MexOy NPs based on the colorimetric lactate dehydrogenase (LDH) assay and the luminometric adenosine triphosphate (ATP) assay, both of which quantify irreversible cell membrane damage. Out of the 77 total descriptors used, 7 were identified as being significant for induction of cytotoxicity by MexOy NPs. These were NP core size, hydrodynamic size, assay type, exposure dose, the energy of the MexOy conduction band (EC), the coordination number of the metal atoms on the NP surface (Avg. C.N. Me atoms surface) and the average force vector surface normal component of all metal atoms (v⟂ Me atoms surface). The significance and effect of these descriptors is discussed to demonstrate their direct correlation with cytotoxicity. The produced model has been made publicly available by the Horizon 2020 (H2020) NanoSolveIT project and will be added to the project's Integrated Approach to Testing and Assessment (IATA).

Problem Formulation for Off-Target Effects of Externally Applied Double-Stranded RNA-Based Products for Pest Control

Externally applied dsRNA-based biocontrol products may lead to off-target degradation of messenger RNA in target and non-target organisms. For the purposes of regulatory risk assessment of such products, producing a comprehensive catalog of any off-target effects using profiling methods is unnecessary and would be ineffective in supporting decision-making. Instead, problem formulation should derive criteria that indicate acceptable risk and devise a plan to test the hypothesis that the product meets those criteria. The key to effective risk assessment of dsRNA-based biocontrols is determining whether their properties indicate acceptable or unacceptable risk, not whether they arise from on- or off-target effects of dsRNA.

Mechanistic identification of biofluid metabolite changes as markers of acetaminophen-induced liver toxicity in rats

Acetaminophen (APAP) is the most commonly used analgesic and antipyretic drug in the world. Yet, it poses a major risk of liver injury when taken in excess of the therapeutic dose. Current clinical markers do not detect the early onset of liver injury associated with excess APAP-information that is vital to reverse injury progression through available therapeutic interventions. Hence, several studies have used transcriptomics, proteomics, and metabolomics technologies, both independently and in combination, in an attempt to discover potential early markers of liver injury. However, the casual relationship between these observations and their relation to the APAP mechanism of liver toxicity are not clearly understood. Here, we used Sprague-Dawley rats orally gavaged with a single dose of 2 g/kg of APAP to collect tissue samples from the liver and kidney for transcriptomic analysis and plasma and urine samples for metabolomic analysis. We developed and used a multi-tissue, metabolism-based modeling approach to integrate these data, characterize the effect of excess APAP levels on liver metabolism, and identify a panel of plasma and urine metabolites that are associated with APAP-induced liver toxicity. Our analyses, which indicated that pathways involved in nucleotide-, lipid-, and amino acid-related metabolism in the liver were most strongly affected within 10 h following APAP treatment, identified a list of potential metabolites in these pathways that could serve as plausible markers of APAP-induced liver injury. Our approach identifies toxicant-induced changes in endogenous metabolism, is applicable to other toxicants based on transcriptomic data, and provides a mechanistic framework for interpreting metabolite alterations.

Selective Inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis with Pulsed Electric Fields and Antibiotics

Objective: Increasing numbers of multidrug-resistant bacteria make many antibiotics ineffective; therefore, new approaches to combat microbial infections are needed. In addition, antibiotics are not selective-they kill pathogenic organisms as well as organisms that could positively contribute to wound healing (bio flora). Approach: Here we report on selective inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis, potential pathogens involved in wound infections with pulsed electric fields (PEFs) and antibiotics (mix of penicillin, streptomycin, and nystatin). Results: Using a Taguchi experimental design in vitro, we found that, under similar electric field strengths, the pulse duration is the most important parameter for P. aeruginosa inactivation, followed by the number of pulses and pulse frequency. P. aeruginosa, a potential severe pathogen, is more sensitive than the less pathogenic S. epidermidis to PEF (alone or in combination with antibiotics). Applying 200 pulses with a duration of 60 μs at 2.8 Hz, the minimum electric fields of 308.8 ± 28.3 and 378.4 ± 12.9 V/mm were required to inactive P. aeruginosa and S. epidermidis, respectively. Addition of antibiotics reduced the threshold for minimum electric fields required to inactivate the bacteria. Innovation: This study provides essential information, such as critical electric field parameters for bacteria inactivation, required for developing in vivo treatment and clinical protocols for using PEF for wound healing. Conclusion: A combination of PEFs with antibiotics reduces the electric field threshold required for bacteria disinfection. Such an approach simplifies devices required to disinfect large areas of infected wounds.

In vitro study of putative genomic biomarkers of nephrotoxicity through differential gene expression using gentamicin

Drug-induced nephrotoxicity is one of the most frequently observed effects in long-term pharmacotherapy. The effects of nephrotoxicity are commonly discovered later due to a lack of sensitivity in in vivo methods. Therefore, researchers have tried to develop in vitro alternative methods for early identification of toxicity. In this study, LLC-PK1 cells were exposed to gentamicin through MTT and trypan blue assay. Concentrations of 4 (low), 8 (medium) and 12 (high) mM, were used to evaluate differential gene expression. A panel of genes was selected based on gene expression changes. The search for sequences of mRNA encoding proteins previously associated with kidney damage was conducted in the databases of the National Center for Biotechnology Information (USA). RNA was extracted from the cells, and RT-qPCR was performed to evaluate differential expression profiles of the selected genes. Among the 11 analyzed genes, four proved to be differentially up-regulated in cells exposed to gentamicin: HAVcr1, caspase 3, ICAM-1 and EXOC6. According to this study's results, we suggest that these genes play an important role in the mechanism of in vitro nephrotoxicity caused by gentamicin and can be used as early in vitro biomarkers to identify nephrotoxicity when developing safer drugs.

Combined ecotoxicological risk assessment in the frame of European authorization of pesticides

Organisms are frequently exposed to mixtures of chemical contaminants in the environment, causing a potential "cocktail effect", or combined effect. The joint action of different molecules with similar or different modes of action could result in a potentially unlimited number of additives, synergistic or antagonistic combinations. Since the large number of contaminants makes it impossible to perform ecotoxicity tests for each potential mixture, a robust approach for prospective environmental risk assessment of chemical mixtures is needed. A number of recent publications by the European Commission and the authorities in charge prove the increasing interest that is spreading in the European community towards the topic of the assessment of chemical mixtures. The current EU regulation for Plant Protection Products authorization (Reg. 1107/2009 EC) explicitly requires the evaluation of the potential combined effects of active substances. We reviewed current methods and limitations of mixture assessment of pesticides (7 fungicides and 4 herbicides) through the analysis of the approaches adopted to investigate possible risks for different non-target organisms. The Concentration Addition (CA) approach was the most used approach to predict multiple toxicity to non-target organisms. The guidance for birds and mammals first introduced standard procedures to assess the multiple toxicity based on on CA concept. The recent aquatic EFSA guidance introduced some requirements to evaluate potential mixture toxicity, while the current guidance requirements for terrestrial organisms still lack clear indications on how to conduct the assessment. Moreover, new indications come from the draft guidance for the assessment of terrestrial plants and in-soil organisms. However, the approval and implementation of these new guidelines are still at a developmental stage. Some final considerations are drawn on the future possibilities to improve risk assessment procedures so as to identify harmful effects of pesticides mixtures on non-target organisms.

Experimental diabetes induced by alloxan and streptozotocin: The current state of the art

Diabetes mellitus is a chronic metabolic disorder with a high prevalence worldwide. Animal models of diabetes represent an important tool in diabetes investigation that helps us to avoid unnecessary and ethically challenging studies in human subjects, as well as to obtain a comprehensive scientific viewpoint of this disease. Although there are several methods through which diabetes can be induced, chemical methods of alloxan- and streptozotocin-induced diabetes represent the most important and highly preferable experimental models for this pathological condition. Therefore, the aim of this article was to review the current knowledge related to quoted models of diabetes, including to this point available information about mechanism of action, particular time- and dose-dependent protocols, frequent problems, as well as major limitations linked to laboratory application of alloxan and sterptozotocin in inducing diabetes. Given that diabetes is known to be closely associated with serious health consequences it is of fundamental importance that current animal models for induction of diabetes should be continuously upgraded in order to improve overall prevention, diagnosis and treatment of this pathological condition.

Coelomic fluid: a complimentary biological medium to assess sub-lethal endosulfan exposure using ¹H NMR-based earthworm metabolomics

Endosulfan is an environmentally persistent pesticide and has been shown to be genotoxic, neurotoxic and carcinogenic to surrounding organisms. Earthworms are widely used in environmental metabolomic studies to assess soil ecotoxicity. Previous nuclear magnetic resonance (NMR)-based metabolomic studies have analyzed earthworm tissue extracts after exposure to endosulfan and identified some key metabolic indicators that can be used as biomarkers of stress. However, some metabolites may have been masked due to overlap with other metabolites in the tissue extract. Therefore, in this study, the coelomic fluid (CF) and the tissue extract of the earthworm, Eisenia fetida, were both investigated using ¹H NMR-based metabolomics to analyze their metabolic profile in response to endosulfan exposure at three sub-lethal (below LC₅₀) concentrations. Principal component analysis determined the earthworm CF and earthworm tissue extract to both have significant separation between the exposed and control at the two highest sub-lethal endosulfan exposures (1.0 and 2.0 μg cm⁻²). Alanine, glycine, malate, α-ketoglutarate, succinate, betaine, myo-inositol, lactate and spermidine in the earthworm CF and alanine, glutamine, fumarate, glutamate, maltose, melibiose, ATP and lactate in earthworm tissue extract were all detected as having significant fluctuations after endosulfan exposure. An increase in ATP production was detected by the increase activity in the citric acid cycle and by anaerobic metabolism. A significant decrease in the polyamine, spermidine after endosulfan exposure describes an apoptotic mode of protection which correlates to a previous endosulfan exposure study where DNA damage has been reported. This study highlights that earthworm CF is a complementary biological medium to tissue extracts and can be helpful to better understand the toxic mode of action of contaminants at sub-lethal levels in the environment.

Computational toxicological investigation on the mechanism and pathways of xenobiotics metabolized by cytochrome P450: a case of BDE-47

Understanding the transformation mechanism and products of xenobiotics catalyzed by cytochrome P450 enzymes (CYPs) is vital to risk assessment. By density functional theory computation with the B3LYP functional, we simulated the reaction of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) catalyzed by the active species of CYPs (Compound I). The enzymatic and aqueous environments were simulated by the polarizable continuum model. The results reveal that the addition of Compound I to BDE-47 is the rate-determining step. The addition of Compound I to the ipso and nonsubstituted C atoms forms tetrahedral σ-adducts that further transform into epoxides. Hydroxylation of the epoxides leads to hydroxylated polybrominated diphenyl ethers and 2,4-dibromophenol. The addition to the Br-substituted C2 and C4 atoms has a higher barrier than addition to the nonsubstituted C atoms, forming phenoxide and cyclohexadienone which subsequently undergo debromination/hydroxylation. A novel mechanism was identified in which the approach of Compound I to C2 led to formation of a phenoxide and an expelled Br(-) ion. The predicted products were consistent with the metabolites identified by others. As a first attempt to simulate the enzymatic transformation of a polycyclic compound, this study may enlighten a computational method to predict the biotransformation of xenobiotics catalyzed by CYPs.

'Omics analysis of low dose acetaminophen intake demonstrates novel response pathways in humans

Acetaminophen is the primary cause of acute liver toxicity in Europe/USA, which led the FDA to reconsider recommendations concerning safe acetaminophen dosage/use. Unfortunately, the current tests for liver toxicity are no ideal predictive markers for liver injury, i.e. they only measure acetaminophen exposure after profound liver toxicity has already occurred. Furthermore, these tests do not provide mechanistic information. Here, 'omics techniques (global analysis of metabolomic/gene-expression responses) may provide additional insight. To better understand acetaminophen-induced responses at low doses, we evaluated the effects of (sub-)therapeutic acetaminophen doses on metabolite formation and global gene-expression changes (including, for the first time, full-genome human miRNA expression changes) in blood/urine samples from healthy human volunteers. Many known and several new acetaminophen-metabolites were detected, in particular in relation to hepatotoxicity-linked, oxidative metabolism of acetaminophen. Transcriptomic changes indicated immune-modulating effects (2g dose) and oxidative stress responses (4g dose). For the first time, effects of acetaminophen on full-genome human miRNA expression have been considered and confirmed the findings on mRNA level. 'Omics techniques outperformed clinical chemistry tests and revealed novel response pathways to acetaminophen in humans. Although no definitive conclusion about potential immunotoxic effects of acetaminophen can be drawn from this study, there are clear indications that the immune system is triggered even after intake of low doses of acetaminophen. Also, oxidative stress-related gene responses, similar to those seen after high dose acetaminophen exposure, suggest the occurrence of possible pre-toxic effects of therapeutic acetaminophen doses. Possibly, these effects are related to dose-dependent increases in levels of hepatotoxicity-related metabolites.

Predicting in vivo safety characteristics using physiochemical properties and in vitro assays

There is increasing pressure on the pharmaceutical industry to deliver safer and more effective medicines while constraining research and development costs. In order to meet these demands, the industry is looking for basic design principles in terms of physicochemical properties as well as the use of higher throughput in vitro assays to select and evaluate new molecular entities for further development. Recent advances in understanding the relationships between a chemical’s properties and its propensity for adverse events, as well as the development of new in vitro screening technologies, have enhanced our ability to potentially select molecules more likely to succeed in becoming drugs. However, these approaches are still limited by the availability of data and our lack of understanding of the mechanisms by which compounds can cause toxicity.

Beyond REACH: roadblocks and shortcuts en route to integrated risk assessment and management of chemicals

This paper addresses obstacles and opportunities for the development and application of novel methods for integrated assessment of cumulative risks from chemicals, exemplified by the REACH legislation of the EU, in the context of multiple stressors and of chemicals policy. We examine the role of such methods in connection with REACH by models of integration and innovation of risk information in multi-actor risk governance; analyses of key documents on REACH; and interviews with EU regulators and stakeholders. We first explain the emergence of REACH as a response to tensions in EU chemicals, environmental and other policies. We then analyze the present configuration of REACH particularly in relation to key dimensions of risk integration: across stressors; exposed organisms; and impacts. Among the policy aspects of integrated risk information, we focus on its interaction with management and the contesting framings and interpretations of assessment. Avenues and barriers are identified for integrated treatment of risks under REACH and with other instruments. We emphasize how bounded, formal and static assessments interact with open and informal approaches that have more flexibility in integrating risks in new ways. We conclude with a generalizing discussion on the role of novel methods of integrated risk assessment in the development of reflexive and participatory governance under REACH and beyond.

Ecotoxicological risk assessment using DNA chips and cellular reporters

Ecotoxicological risk assessment has long been based on (acute) effective concentration and lethal concentration (EC/LC50) endpoints in organisms from different trophic levels. These tests are insufficient adequately to assess the risk associated with many chemical classes. The introduction of advanced molecular techniques is leading to improved risk assessment and is also providing an alternative to the massive use of animal testing. Transcriptional profiling and DNA chips are highly informative and are among the most promising novel techniques for environmental risk assessment. Moreover, information discerned from these chips enables the identification of new discriminative biomarker genes. Based on these biomarker genes, cellular reporters can be constructed. These can be used in a high-throughput set-up and can facilitate ecotoxicological risk assessment significantly. Some important technical and interpretative hurdles still need to be overcome before a full implementation of ecotoxicogenomics in regulatory settings will occur.