Evaluation of developmental toxicity of chlorpyrifos through new approach methodologies: a systematic review.

Chlorpyrifos (CPF) is an organophosphorus pesticide of concern because many in vivo animal studies have demonstrated developmental toxicity exerted by this substance; however, despite its widespread use, evidence from epidemiological studies is still limited. In this study, we have collected all the information generated in the twenty-first century on the developmental toxicity of CPF using new approach methodologies. We have critically evaluated and integrated information coming from 70 papers considering human, rodent, avian and fish models.

Human Skin Fibroblasts as an In Vitro Model Illustrating Changes in Collagen Levels and Skin Cell Migration Under the Influence of Selected Plant Hormones.

Human skin fibroblasts are an excellent in vitro model for tracking the processes occurring in human skin and studying the potential impact of various biologically active substances on these processes. Two plant hormones, which are included in the cytokinins group-kinetin (K) and N-6-benzyladenine (BA)-have a positive effect on human skin. Therefore, an attempt was made to examine the effect they have on key skin functions, cell proliferation, and migration, as well as collagen synthesis in them.

Inhibition with simultaneous spontaneous reactivation and aging of acetylcholinesterase by organophosphorus compounds: Demeton-S-methyl as a model.

The kinetic analysis of esterase inhibition by acylating compounds (organophosphorus, carbamates and sulfonylfluorides) sometimes cannot yield consistent results by fitting simple inhibition kinetic models to experimental data of complex systems. In this work kinetic data were obtained for demeton-S-methyl (DSM) with human acetylcholinesterase in two kinds of experiments: (a) time progressive inhibition with a range of concentrations, (b) progressive spontaneous reactivation starting with pre-inhibited enzyme. DSM is an organophosphorus compound used as pesticide and considered a model for studying the dermal exposure of nerve agents such as VX gas.

Investigation of the Effects of Metallic Nanoparticles on Fertility Outcomes and Endocrine Modification of the Hypothalamic-Pituitary-Gonadal Axis.

Nanotechnology is a very disruptive twenty-first-century revolution that will allow social and economic welfare to increase although it also involves a significant human exposure to nanoparticles. The aim of the present study was to contribute to the elucidation on whether metallic nanoparticles have a potential to induce fertility impairments. Regulatory studies that observed official OECD guidelines 415, 416 and 422 have failed to detect any fertility alterations caused by nanoparticle exposure.

Reference Values on Children's Hair for 28 Elements (Heavy Metals and Essential Elements) Based on a Pilot Study in a Representative Non-Contaminated Local Area.

Studies have been published, and laboratories offer services of measuring elements in hair as biomarkers of environmental exposure and/or control of essential elements (trace or macro). These reported values can have only sense if compared with adopted reference values. In this work, we propose provisional reference values based on a pilot child population.

Human-Based New Approach Methodologies in Developmental Toxicity Testing: A Step Ahead from the State of the Art with a Feto-Placental Organ-on-Chip Platform.

Developmental toxicity testing urgently requires the implementation of human-relevant new approach methodologies (NAMs) that better recapitulate the peculiar nature of human physiology during pregnancy, especially the placenta and the maternal/fetal interface, which represent a key stage for human lifelong health. Fit-for-purpose NAMs for the placental-fetal interface are desirable to improve the biological knowledge of environmental exposure at the molecular level and to reduce the high cost, time and ethical impact of animal studies. This article reviews the state of the art on the available in vitro (placental, fetal and amniotic cell-based systems) and in silico NAMs of human relevance for developmental toxicity testing purposes; in addition, we considered available Adverse Outcome Pathways related to developmental toxicity.

A Transcriptomic Analysis of T98G Human Glioblastoma Cells after Exposure to Cadmium-Selenium Quantum Dots Mainly Reveals Alterations in Neuroinflammation Processes and Hypothalamus Regulation.

Quantum dots are nanoparticles with very promising biomedical applications. However, before these applications can be authorized, a complete toxicological assessment of quantum dots toxicity is needed. This work studied the effects of cadmium-selenium quantum dots on the transcriptome of T98G human glioblastoma cells.

Interactions of human acetylcholinesterase with phenyl valerate and acetylthiocholine: Thiocholine as an enhancer of phenyl valerate esterase activity.

Phenyl valerate (PV) is a neutral substrate for measuring the PVase activity of neuropathy target esterase (NTE), a key molecular event of organophosphorus-induced delayed neuropathy. This substrate has been used to discriminate and identify other proteins with esterase activity and potential targets of organophosphorus (OP) binding. A protein with PVase activity in chicken (model for delayed neurotoxicity) was identified as butyrylcholinesterase (BChE).

Case study: risk associated to wearing silver or graphene nanoparticle-coated facemasks for protection against COVID-19.

The world is living a pandemic situation derived from the worldwide spreading of SARS-CoV-2 virus causing COVID-19. Facemasks have proven to be one of the most effective prophylactic measures to avoid the infection that has made that wearing of facemasks has become mandatory in most of the developed countries. Silver and graphene nanoparticles have proven to have antimicrobial properties and are used as coating of these facemasks to increase the effectivity of the textile fibres.

DAEH N-terminal sequence of avian serum albumins as catalytic center of Cu (II)-dependent organophosphorus hydrolyzing A-esterase activity.

O-hexyl O-2,5-dichlorophenyl phosphoramidate (HDCP) induces delayed neuropathy. The R (+)-HDCP inhibits and caused the so call "aging reaction" on inhibited-NTE. This enantiomer is not hydrolyzed by Ca(II)-dependent A-esterases in mammal tissues but is hydrolyzed by Cu(II)-dependent chicken serum albumin (CSA).

Titanium Dioxide, but Not Zinc Oxide, Nanoparticles Cause Severe Transcriptomic Alterations in T98G Human Glioblastoma Cells.

Titanium dioxide and zinc oxide are two of the most widely used nanomaterials. We assessed the effects of noncytotoxic doses of both nanomaterials on T98G human glioblastoma cells by omic approaches. Surprisingly, no effects on the transcriptome of T98G cells was detected after exposure to 5 µg/mL of zinc oxide nanoparticles during 72 h.

Effects of silver nanoparticles on T98G human glioblastoma cells.

Nanotechnology has been well developed in recent decades because it provides social progress and welfare. Consequently, exposure of population is increasing and further increases in the near future are forecasted. Therefore, assessing the safety of applications involving nanoparticles is strongly advisable.

Case study: Is bisphenol S safer than bisphenol A in thermal papers?

The Risk Assessment Committee of the European Chemical Agency released a scientific opinion alerting that the risk associated with dermal occupational exposure to bisphenol A (BPA) via thermal paper might not be adequately controlled because the estimated exposure was around twice the Derived No Effect Level (DNEL) and the European Commission will effectively restrict BPA in thermal paper as soon as 2020. Bisphenol S (BPS) is currently being used as a BPA surrogate and is already widespread in thermal paper receipts. Based on publically available information in the scientific literature, we assessed the risk associated with dermal BPS exposure via thermal paper for the general and occupational populations to compare with BPA situation.

Cholinesterase and phenyl valerate-esterase activities sensitive to organophosphorus compounds in membranes of chicken brain.

Some effects of organophosphorus compounds (OPs) esters cannot be explained by action on currently recognized targets acetylcholinesterase or neuropathy target esterase (NTE). In previous studies, in membrane chicken brain fractions, four components (EPα, EPβ, EPγ and EPδ) of phenyl valerate esterase activity (PVase) had been kinetically discriminated combining data of several inhibitors (paraoxon, mipafox, PMSF). EPγ is belonging to NTE.

Hydrolyzing activities of phenyl valerate sensitive to organophosphorus compounds paraoxon and mipafox in human neuroblastoma SH-SY5Y cells.

The molecular targets of best known neurotoxic effects associated to acute exposure to organophosphorus compounds (OPs) are serine esterases located in the nervous system, although there are other less known neurotoxic adverse effects associated with chronic exposure to OPs whose toxicity targets are still not identified. In this work we studied sensitivity to the non-neuropathic OP paraoxon and to the neuropathic OP mipafox of phenyl valerate esterases (PVases) in intact and lysed human neuroblastoma SH-SY5Y cells. The main objective was to discriminate different unknown pools of esterases that might be potential targets of chronic effects from those esterases already known and recognized as targets to these acute neurotoxicity effects.

Albumin, the responsible protein of the Cu-dependent hydrolysis of O-hexyl O-2,5-dichlorophenyl phosphoramidate (HDCP) by chicken serum "antagonistic stereoselectivity".

O-hexyl O-2,5-dichlorophenyl phosphoramidate (HDCP) is a chiral analogous compound of the methamidophos insecticide that induces delayed neuropathy, and the R-(+)-HDCP enantiomer is an inhibitor of neuropathy target esterase (NTE). This enantiomer is not hydrolized by Ca-dependent phosphotriesterases in mammal tissues. Our group had reported R-(+)-HDCP hydrolysis in chicken serum enhanced by 30-250 μM copper in ex vivo assays, which we call "antagonistic stereoselectivity".

Copper activation of organophosporus compounds detoxication by chicken serum.

Avian species contain low levels of enzymes that hydrolyze organophosphorus compounds (OPs), and chickens are used as a model of OPs delayed neurotoxicity. For both reasons, we studied the ability of chicken tissue for OP detoxication. A significant activating effect of Cu on the hydrolysis of O-hexyl O-2,5-dichlorophenyl phosphoramidate (HDCP) was observed in hen plasma and the microsomal fractions of the liver, brain, and mainly in hen serum, by spectrophotometric and chiral chromatography methods.

Acetylcholine-hydrolyzing activities in soluble brain fraction: Characterization with reversible and irreversible inhibitors.

Some effects of organophosphorus compounds (OPs) esters cannot be explained through actions on currently recognized targets acetylcholinesterase or neuropathy target esterase (NTE). In soluble chicken brain fraction, three components (Eα, Eβ and Eγ) of pheny lvalerate esterase activity (PVase) were kinetically discriminated and their relationship with acetylcholine-hydrolyzing activity (cholinesterase activity) were studied in previous works. In this work, four enzymatic components (CS1, CS2, CS3 and CS4) of cholinesterase activity have been discriminated in soluble fraction, according to their sensitivity to irreversible inhibitors mipafox, paraoxon, PMSF and iso-OMPA and to reversible inhibitors ethopropazine and BW284C51.

Roles of NTE protein and encoding gene in development and neurodevelopmental toxicity.

Neuropathy Target Esterase (NTE) is a membrane protein codified by gene PNPLA6. NTE was initially discovered as a target of the so-called organophosphorus-induced delayed polyneuropathy triggered by the inhibition of the NTE-associated esterase center by neuropathic organophosphorus compounds (OPs). The physiological role of NTE might be related to membrane lipid homeostasis and seems to be involved in adult organisms in maintaining nervous system integrity.

Effects of mipafox, paraoxon, chlorpyrifos and its metabolite chlorpyrifos-oxon on the expression of biomarker genes of differentiation in D3 mouse embryonic stem cells.

Chlorpyrifos (CPS) is an organophosphorus compound (OP) capable of causing well-known cholinergic and delayed syndromes through the inhibition of acetylcholinesterase and Neuropathy Target Esterase (NTE), respectively. CPS is also able to induce neurodevelopmental toxicity in animals. NTE is codified by the Pnpla6 gene and plays a central role in differentiation and neurodifferentiation.

Expression of biomarker genes of differentiation in D3 mouse embryonic stem cells after exposure to different embryotoxicant and non-embryotoxicant model chemicals.

There is a necessity to develop in vitro methods for testing embryotoxicity (Romero et al., 2015) [1]. We studied the progress of D3 mouse embryonic stem cells differentiation exposed to model embryotoxicants and non-embryotoxicants chemicals through the expression of biomarker genes.

RNA transcripts for the quantification of differentiation allow marked improvements in the performance of embryonic stem cell test (EST).

Embryonic stem cell test (EST) is an in vitro validated assay for testing embryotoxicity. The EST needs improvements before being used for regulatory purposes, but also needs technical simplification for use in high throughput screenings. We propose the quantification in alterations of the differentiation of D3 monolayer cells cultures through the expression of biomarker genes in a shorter (5-day) and technically simpler (we use only monolayer cultures) test.

Silencing of PNPLA6, the neuropathy target esterase (NTE) codifying gene, alters neurodifferentiation of human embryonal carcinoma stem cells (NT2).

Neuropathy target esterase (NTE) is a protein involved in the development of a polyneuropathy caused by exposure to certain organophosphorus compounds. In vivo and in vitro studies have also associated NTE with embryonic development since NTE null mice embryos are non-viable, and silencing the NTE-codifying gene (Pnpla6) in mouse embryonic stem cells strongly alters the differentiation of vascular and nervous systems. In this paper, human embryonal carcinoma stem cells human-derived NTera2/D1 (hNT2) are used as an in vitro neurodifferentiation model to determine whether PNPLA6 silencing is able to alter the differentiation process.