The link of organophosphorus pesticides with neurodegenerative and neurodevelopmental diseases based on evidence and mechanisms

Luteolin attenuates Fipronil-induced neurotoxicity through reduction of the ROS-mediated oxidative stress in rat brain mitochondria

Luteolin (LUT) as a natural compound found in vegetables and fruits has various pharmacological effects. Fipronil (FPN), as a pesticide, has been considered for its effect on the antioxidant system and induction of oxidative stress. This study was designed to investigate the protective effects of LUT against the oxidative stress and mitochondrial toxicity induced by FPN on the rat brain. Several parameters such as mitochondrial reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP) collapse, mitochondrial swelling, cytochrome c release, mitochondrial glutathione (GSH), lipid peroxidation (LPO) and Adenosine triphosphate (ATP) levels were assessed. Results indicated that the administration of LUT (25 μM) significantly improved oxidative stress and mitochondrial damages induced via FPN (6, 12 and 24 μM) in isolated mitochondria from the brain. These results show that LUT exerted protective effects against FPN-induced neurotoxicity in vitro through improving oxidative stress and mitochondrial damages.

The negative role of histone acetylation in cobalt chloride-induced neurodegenerative damages in SHSY5Y cells

Cobalt has been known for its neurotoxicity in numerous studies. However, the molecular mechanism underlying cobalt-induced neurotoxicity remains largely unknown. In this study, two neuroblastoma (SHSY5Y and N2a) cell lines and a phaeochromocytoma (PC12) line were used as in vitro models. Cells were treated for 24 h with 50, 100, 200, 300, 400 µM cobalt chloride (CoCl₂) or cultured with 300 μM CoCl₂ for 4, 8, 12 and 24 h to investigate the effects of histone acetylation on CoCl₂-induced neurodegenerative damages. Our findings demonstrate that CoCl₂ suppresses the acetylation of histone H3 and H4 in a time-dependent and dosage-dependent manner. Furthermore, CoCl₂ selectively decreases the expression and activity of histone acetyltransferase (HAT) but has no effects on histone deacetylase (HDAC) in SHSY5Y cells. More importantly, we show that 100 ng/mL HDAC inhibitor trichostatin (TSA) pre-treatment partly attenuates 300 μM CoCl₂-induced neurodegenerative damages in SHSY5Y cells. Mechanistic analyses show that CoCl₂-induced neurodegenerative damages are associated with the dysfunction of APP, BACE1, PSEN1, NEP and HIF-1α genes, whose expression are partly mediated by histone modification. In summary, we demonstrate that histone acetylation is involved in CoCl₂-induced neurodegenerative damages. Our study indicates an important connection between histone modification and the pathological process of neurodegenerative damages and provides a mechanism for cobalt-mediated epigenetic regulation.

Emerging nanobiotechnology in agriculture for the management of pesticide residues

Utilization of pesticides is often necessary for meeting commercial requirements for crop quality and yield. However, incessant global pesticide use poses potential risks to human and ecosystem health. This situation increases the urgency of developing nano-biotechnology-assisted pesticide formulations that have high efficacy and low risk of side effects. The risks associated with both conventional and nanopesticides are summarized in this review. Moreover, the management of residual pesticides is still a global challenge. The contamination of soil and water resources with pesticides has adverse impact over agricultural productivity and food security; ultimately posing threats to living organisms. Pesticide residues in the eco-system may be treated via several biological and physicochemical processes, such as microbe-based degradation and advanced oxidation processes. With these issues in mind, we present a review that explores both existing and emerging techniques for management of pesticide residues and environmental risks. These techniques can offer a sustainable solution to revitalize the tarnished water/soil resources. Further, state-of-the-art research approaches to investigate biotechnological alternatives to conventional pesticides are discussed along with future prospects and mitigation techniques are recommended.

Organophosphorus flame retardants are developmental neurotoxicants in a rat primary brainsphere in vitro model

Due to regulatory bans and voluntary substitutions, halogenated polybrominated diphenyl ether (PBDE) flame retardants (FR) are increasingly substituted by mainly organophosphorus FR (OPFR). Leveraging a 3D rat primary neural organotypic in vitro model (rat brainsphere), we compare developmental neurotoxic effects of BDE-47-the most abundant PBDE congener-with four OPFR (isopropylated phenyl phosphate-IPP, triphenyl phosphate-TPHP, isodecyl diphenyl phosphate-IDDP, and tricresyl phosphate (also known as trimethyl phenyl phosphate)-TMPP). Employing mass spectroscopy-based metabolomics and transcriptomics, we observe at similar human-relevant non-cytotoxic concentrations (0.1-5 µM) stronger developmental neurotoxic effects by OPFR. This includes toxicity to neurons in the low µM range; all FR decrease the neurotransmitters glutamate and GABA (except BDE-47 and TPHP). Furthermore, n-acetyl aspartate (NAA), considered a neurologic diagnostic molecule, was decreased by all OPFR. At similar concentrations, the FR currently in use decreased plasma membrane dopamine active transporter expression, while BDE-47 did not. Several findings suggest astrogliosis induced by the OPFR, but not BDE-47. At the 5 µM concentrations, the OPFR more than BDE-47 interfered with myelination. An increase of cytokine gene and receptor expressions suggests that exposure to OPFR may induce an inflammatory response. Pathway/category overrepresentation shows disruption in 1) transmission of action potentials, cell-cell signaling, synaptic transmission, receptor signaling, (2) immune response, inflammation, defense response, (3) cell cycle and (4) lipids metabolism and transportation. Taken together, this appears to be a case of regretful substitution with substances not less developmentally neurotoxic in a primary rat 3D model.

Rapid and sensitive detection of diazinon in food based on the FRET between rare-earth doped upconversion nanoparticles and graphene oxide

Diazinon is a typical phosphorothionate, which is widely used to prevent and control harmful organisms that endanger the agriculture productions. However, it is among the most toxic substances and can cause damage to the environment, food and human health even in very low concentrations. Hence, ultra-sensitive screening methods are urgently required for the detection of this extensively used pesticide. In this study, a rapid and sensitive fluorescence resonance energy transfer (FRET) method was developed for low concentration detection of diazinon in food. The aptamer-modified upconversion nanoparticles (Apt-UCNPs) were synthesized and conjugated with graphene oxide (GO) through π-π interaction. Due to the FRET between UCNPs and GO, the fluorescence was quenched. When diazinon was added, the aptamer preferentially bound with it, caused the separation of GO, and resulted in the enhancement of fluorescent signal. Under the optimal conditions, a wide linear detection range from 0.05 to 500 ng/mL was achieved, with a limit of detection (LOD) of 0.023 ng/mL. The proposed method was successfully applied to measure diazinon in real samples. Results showed that the proposed nanosensor offers an efficient, specific and simple approach for the detection of diazinon in food and has a high potential for food safety and quality control.

Sol-gel fabrication and performance evaluation of graphene-based hydrophobic solid-phase microextraction fibers for multi-residue analysis of pesticides in water samples

Widespread use of organophosphorus pesticides poses serious environmental threats, and hence calls for effective analysis methods for these classes of compounds. In this study, a lab-made graphene-based solid-phase microextraction (SPME) fiber was fabricated by the sol-gel method and combined with a gas chromatography-flame photometry detector (GC-FPD) to realize the detection of trace OPPs in water samples. Compared to the commercial fiber coatings, the new sol-gel graphene fiber coatings showed advantages of good durability and solvent resistance, which were attributed to the hydrophobic and antibacterial properties of the functionalized graphene and 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride (QAS). A headspace SPME method in combination with a GC-FPD was established to evaluate the performance of the novel fibers. The proposed method showed a good linear relationship for the eight OPPs (R²≥ 0.9957) in the concentration range of 1 to 1000 μg L^-1, with limits of quantification of 0.11-3.37 μg L^-1 and limits of detection of 0.03-1.01 μg L^-1. Furthermore, the developed method also exhibited good recoveries for the analysis of OPPs both in rainwater and lake water, which demonstrates that this method is an alternative choice for multi-residue analysis of OPPs, and it has the potential for broader applications in the future.

Investigation of the effects of dichlorvos poisoning on AMPK signaling pathway in chicken brain tissues

Dichlorvos is a common crop insecticide widely used by people which causes extensive and serious environmental pollution. However, it has been shown that organophosphorus poisoning causes energy metabolism and neural disorders. The overall purpose of this study was to investigate the damage to brain tissue and the changes in AMPK signaling pathway-related gene expression after dichlorvos poisoning in chickens. White-feathered broiler chickens, as the research subjects of this experiment, were divided into three groups: control group, low-dose group (77.5% dichlorvos at 1.13 mg/kg dose) and high-dose group (77.5% dichlorvos at 10.2 mg/kg dose). Clinical symptoms were observed after modeling, and an integrative analysis was conducted using HE staining microscopy, immune-histochemical microscopy, electron microscopy and PCR arrays. The results showed that the high-dose group had more obvious dyspnea, salivation, convulsion and other neurological phenomena. Pathological sections showed that nuclear disintegration of neurons was most obvious in the low-dose group, and apoptosis of brain cells was most obvious in the high-dose group, and the mitochondrial structure was destroyed in the two poisoned group, i.e. low-dose group and high-dose group. PCR arrays showed that AMPK signaling pathway was inhibited and the expressions of genes involved in energy metabolism (ACACA and PRKAA1) were significantly changed. Furthermore, genes associated with protein synthesis (EIF4EBP1) were significantly upregulated. FASN and HMGCR expressions were significantly increased. There were significant changes in the expressions of cell cycle-related genes (STK11, TP53 and FOXO3). Organophosphate poisoning can cause a lot of nuclear disintegration of brain neurons, increases cell apoptosis, disrupts the energy metabolism of mitochondrial structure, and inhibits the AMPK signaling pathway. These results provide a certain idea and basis for studying the mechanism of AMPK signaling after organophosphorus poisoning and provide a research basis for the prevention and treatment of organophosphorus poisoning.

Distribution of residual agricultural pesticides and their impact assessment on the survival of an endangered species

This study aimed to assess the distribution of spent pesticides in an agro-farming area and to evaluate their impact on the ecological risk for an endangered species combing the health risk assessment concept with the modelling algorithm proposed by European Food Safety Authority (EFSA). An agricultural area in western Taiwan was chosen to investigate the ecological risk on Prionailurus bengalensis. Their ecological stability was evaluated in the context of the residuals' distribution of the spent pesticides in the investigated area. The pesticide residues accumulated and correlated highly to the adverse health impact on the leopard cat. In the present study, 67 pesticides were detected from 79 collected soil samples. The hazard index (HI) was found related to land use patterns and the HI values in Yuanli and Zhuolan were significantly higher than those in the other areas, increasing poisoning probability of the leopard cat. The locations of agro-chemical utilization were highly overlapped with leopard cats' activity zone, supporting the hypothesis that pesticide residues posed a potential threat to the leopard cats' health. The proposed risk assessment framework was capable of estimating the risk caused by pesticide residues and no similar study has been reported before.

Neuropathological Mechanisms Associated with Pesticides in Alzheimer's Disease

Environmental toxicants have been implicated in neurodegenerative diseases, and pesticide exposure is a suspected environmental risk factor for Alzheimer’s disease (AD). Several epidemiological analyses have affirmed a link between pesticides and incidence of sporadic AD. Meanwhile, in vitro and animal models of AD have shed light on potential neuropathological mechanisms. In this paper, a perspective on neuropathological mechanisms underlying pesticides’ induction of AD is provided. Proposed mechanisms range from generic oxidative stress induction in neurons to more AD-specific processes involving amyloid-beta (Aβ) and hyperphosphorylated tau (p-tau). Mechanisms that are more speculative or indirect in nature, including somatic mutation, epigenetic modulation, impairment of adult neurogenesis, and microbiota dysbiosis, are also discussed. Chronic toxicity mechanisms of environmental pesticide exposure crosstalks in complex ways and could potentially be mutually enhancing, thus making the deciphering of simplistic causal relationships difficult.

Extracorporeal apheresis therapy for Alzheimer disease-targeting lipids, stress, and inflammation

Current therapeutic approaches to Alzheimer disease (AD) remain disappointing and, hence, there is an urgent need for effective treatments. Here, we provide a perspective review on the emerging role of "metabolic inflammation" and stress as a key factor in the pathogenesis of AD and propose a novel rationale for correction of metabolic inflammation, increase resilience and potentially slow-down or halt the progression of the neurodegenerative process. Based on recent evidence and observations of an early pilot trial, we posit a potential use of extracorporeal apheresis in the prevention and treatment of AD. Apolipoprotein E, lipoprotein(a), oxidized LDL (low density lipoprotein)'s and large LDL particles, as well as other proinflammatory lipids and stress hormones such as cortisol, have been recognized as key factors in amyloid plaque formation and aggravation of AD. Extracorporeal lipoprotein apheresis systems employ well-established, powerful methods to provide an acute, reliable 60-80% reduction in the circulating concentration of these lipid classes and reduce acute cortisol levels. Following a double-membrane extracorporeal apheresis in patients with AD, there was a significant reduction of proinflammatory lipids, circulating cytokines, immune complexes, proinflammatory metals and toxic chaperones in patients with AD. On the basis of the above, we suggest designing clinical trials to assess the promising potential of such "cerebropheresis" treatment in patients with AD and, possibly, other neurodegenerative diseases.

Antioxidants and Nanotechnology: Promises and Limits of Potentially Disruptive Approaches in the Treatment of Central Nervous System Diseases

Many central nervous system (CNS) diseases are still incurable and only symptomatic treatments are available. Oxidative stress is suggested to be a common hallmark, being able to cause and exacerbate the neuronal cell dysfunctions at the basis of these pathologies, such as mitochondrial impairments, accumulation of misfolded proteins, cell membrane damages, and apoptosis induction. Several antioxidant compounds are tested as potential countermeasures for CNS disorders, but their efficacy is often hindered by the loss of antioxidant properties due to enzymatic degradation, low bioavailability, poor water solubility, and insufficient blood-brain barrier crossing efficiency. To overcome the limitations of antioxidant molecules, exploitation of nanostructures, either for their delivery or with inherent antioxidant properties, is proposed. In this review, after a brief discussion concerning the role of the blood-brain barrier in the CNS and the involvement of oxidative stress in some neurodegenerative diseases, the most interesting research concerning the use of nano-antioxidants is introduced and discussed, focusing on the synthesis procedures, functionalization strategies, in vitro and in vivo tests, and on recent clinical trials.

Adult exposure to insecticides causes persistent behavioral and neurochemical alterations in zebrafish

Farmers are often chronically exposed to insecticides, which may present health risks including increased risk of neurobehavioral impairment during adulthood and across aging. Experimental animal studies complement epidemiological studies to help determine the cause-and-effect relationship between chronic adult insecticide exposure and behavioral dysfunction. With the zebrafish model, we examined short and long-term neurobehavioral effects of exposure to either an organochlorine insecticide, dichlorodiphenyltrichloroethane (DDT) or an organophosphate insecticide chlorpyrifos (CPF). Adult fish were exposed continuously for either two or 5 weeks (10-30 nM DDT, 0.3-3 μM CPF), with short- and long-term effects assessed at 1-week post-exposure and at 14 months of age respectively. The behavioral test battery included tests of locomotor activity, tap startle, social behavior, anxiety, predator avoidance and learning. Long-term effects on neurochemical indices of cholinergic function were also assessed. Two weeks of DDT exposure had only slight effects on locomotor activity, while a longer five-week exposure led to hypoactivity and increased anxiety-like diving responses and predator avoidance at 1-week post-exposure. When tested at 14 months of age, these fish showed hypoactivity and increased startle responses. Cholinergic function was not found to be significantly altered by DDT. The two-week CPF exposure led to reductions in anxiety-like diving and increases in shoaling responses at the 1-week time point, but these effects did not persist through 14 months of age. Nevertheless, there were persistent decrements in cholinergic presynaptic activity. A five-week CPF exposure led to long-term effects including locomotor hyperactivity and impaired predator avoidance at 14 months of age, although no effects were apparent at the 1-week time point. These studies documented neurobehavioral effects of adult exposure to chronic doses of either organochlorine or organophosphate pesticides that can be characterized in zebrafish. Zebrafish provide a low-cost model that has a variety of advantages for mechanistic studies and may be used to expand our understanding of neurobehavioral toxicity in adulthood, including the potential for such toxicity to influence behavior and development during aging.

Enzymatic Bioremediation of Organophosphate Compounds-Progress and Remaining Challenges

Organophosphate compounds are ubiquitously employed as agricultural pesticides and maintained as chemical warfare agents by several nations. These compounds are highly toxic, show environmental persistence and accumulation, and contribute to numerous cases of poisoning and death each year. While their use as weapons of mass destruction is rare, these never fully disappear into obscurity as they continue to be tools of fear and control by governments and terrorist organizations. Beyond weaponization, their wide-scale dissemination as agricultural products has led to environmental accumulation and intoxication of soil and water across the globe. Therefore, there is a dire need for rapid and safe agents for environmental bioremediation, personal decontamination, and as therapeutic detoxicants. Organophosphate hydrolyzing enzymes are emerging as appealing targets to satisfy decontamination needs owing to their ability to hydrolyze both pesticides and nerve agents using biologically-derived materials safe for both the environment and the individual. As the release of genetically modified organisms is not widely accepted practice, researchers are exploring alternative strategies of organophosphate bioremediation that focus on cell-free enzyme systems. In this review, we first discuss several of the more prevalent organophosphorus hydrolyzing enzymes along with research and engineering efforts that have led to an enhancement in their activity, substrate tolerance, and stability. In the later half we focus on advances achieved through research focusing on enhancing the catalytic activity and stability of phosphotriesterase, a model organophosphate hydrolase, using various approaches such as nanoparticle display, DNA scaffolding, and outer membrane vesicle encapsulation.

Leek-derived codoped carbon dots as efficient fluorescent probes for dichlorvos sensitive detection and cell multicolor imaging

A biomass nitrogen and sulfur codoped carbon dots (NS-Cdots) was prepared by a simple and clean hydrothermal method using leek, and was employed as efficient fluorescent probes for sensitive detection of organophosphorus pesticides (OPs). The leek-derived NS-Cdots emitted blue fluorescence, but was quenched by H₂O₂. Due to acetylcholinesterase/choline oxidase-based cascade enzymatic reaction that produces H₂O₂ and the inhibition effect of OPs on acetylcholinesterase activity, a NS-Cdots-based fluorescence "off-on" method to detect OPs-dichlorvos (DDVP) was developed. More sensitivity and wider linear detection range were achieved from 1.0 × 10^-9 to 1.0 × 10^-3 M (limit of detection = 5.0 × 10^-10 M). This developed method was applied to the detection of DDVP in Chinese cabbage successfully. The average recoveries were in the range of 96.0~104.0% with a relative standard deviation of less than 3.3%. In addition, the NS-Cdots fluorescent probes were also employed successfully in multicolor imaging of living cells, manifesting that the NS-Cdots fluorescent probes have great application potential in agricultural and biomedical fields. Graphical Abstract.

Gestational and perinatal exposure to diazinon causes long-lasting neurobehavioral consequences in the rat

Diazinon is a widely-used organophosphate pesticide. Pulsatile exposure to diazinon during neonatal development has previously been shown cause long-term neurobehavioral impairments in rats. However, the effects of chronic low concentration exposures during perinatal development remain unclear. This experiment evaluated such effects in Sprague-Dawley rats by implanting osmotic pumps in breeder females prior to conception (N = 13-15 litters per condition) which then delivered chronic, zero order kinetic low-level infusions of 0, 114 or 228 ug/day of diazinon throughout pregnancy. One male and one female from each litter was assessed with a battery of behavioral tests that continued from four weeks of age into adulthood. Litter was used as the unit of variance for the analysis of variance test of significance, with sex as a within litter factor. Diazinon treatment condition was the between subjects factor and time or sessions were repeated measures. Chronic diazinon exposure from pre-mating until the neonatal period caused a significant (p < 0.05) increase in percent of time spent on the open arms of the elevated plus maze, an index of risk-taking behavior. Gestational and lactational diazinon exposure also caused a significant (p < 0.05) degree of hyperactivity in the Figure-8 apparatus during adolescence, specifically affecting the early part of the hour-long test session. This effect had dissipated by the time the rats reached adulthood. Diazinon exposure also caused a significant impairment in novel object recognition, a test of cognitive function. Offspring exposed to 228 ug/day diazinon (p < 0.05) showed significantly less preference for the novel vs. familiar object than controls during the first five minutes of the novel object recognition test.

Exposure of Larval Zebrafish to the Insecticide Propoxur Induced Developmental Delays that Correlate with Behavioral Abnormalities and Altered Expression of hspb9 and hspb11

Recent studies suggest that organophosphates and carbamates affect human fetal development, resulting in neurological and growth impairment. However, these studies are conflicting and the extent of adverse effects due to pesticide exposure warrants further investigation. In the present study, we examined the impact of the carbamate insecticide propoxur on zebrafish development. We found that propoxur exposure delays embryonic development, resulting in three distinct developmental stages: no delay, mild delay, or severe delay. Interestingly, the delayed embryos all physically recovered 5 days after exposure, but behavioral analysis revealed persistent cognitive deficits at later stages. Microarray analysis identified 59 genes significantly changed by propoxur treatment, and Ingenuity Pathway Analysis revealed that these genes are involved in cancer, organismal abnormalities, neurological disease, and hematological system development. We further examined hspb9 and hspb11 due to their potential roles in zebrafish development and found that propoxur increases expression of these small heat shock proteins in all of the exposed animals. However, we discovered that less significant increases were associated with the more severely delayed phenotype. This raises the possibility that a decreased ability to upregulate these small heat shock proteins in response to propoxur exposure may cause embryos to be more severely delayed.

Prenatal toxicity of the environmental pollutants on neuronal and cardiac development derived from embryonic stem cells

Pesticides, antibiotics, and industrial excipients are widely used in agriculture, medicine, and chemical industry, respectively. They often end up in the environment, not only being not easily decomposed but also being accumulated. Moreover, they may cause serious toxic problems such as reproductive and developmental defects, immunological toxicity, and carcinogenesis. Hence, they are called environmental pollutants. It is known that the environmental pollutants easily enter the body through various channels such as respiration, ingestion of food, and skin contact etc. in everyday life. If they enter the mother through the placenta, they can cause the disturbance in embryo development as well as malfunction of organs after birth because early prenatal developmental process is highly sensitive to toxic chemicals and stress. Embryonic stem cells (ESCs) that consist of inner cell mass of blastocyst differentiate into distinct cell lineages via three germ layers such as the ectoderm, mesoderm, and endoderm due to their pluripotency. The differentiation process initiated from ESCs reflects dynamic nature of embryonic development. Therefore, ESCs have been used as a useful tool to investigate early developmental toxicities of a variety of stress. Based on relatively recent scientific results, this review would address toxicity of a few chemical substances that have been widely used as pesticide, antibiotics, and industrial excipient on ESCs based-prenatal developmental process. This review further suggests how they act on the viability of ESCs and/or early stages of cardiac and neuronal development derived from ESCs as well as on expression of pluripotency and/or differentiation markers through diverse mechanisms.

Risk Factors and Emerging Therapies in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disease characterized by a permanent degeneration of both upper and lower motor neurons. Many different genes and pathophysiological processes contribute to this disease, however its exact cause remains unclear. Therefore, it is necessary to understand this heterogeneity to find effective treatments. In this review, we focus on selected environmental and genetic risk factors predisposing to ALS and highlight emerging treatments in ALS therapy. Of numerous defective genes associated with ALS, we focus on four principal genes that have been identified as definite causes of ALS: the SOD1 gene, C9orf72, TDP-43, as well as the recently identified TBK1. We also provide up-to-date information on selected environmental factors that have historically been considered as key players in ALS development and pathogenesis. In parallel to our survey of known risk factors, we also discuss emerging ALS stem cell therapies and experimental medicines currently undergoing phase II and III clinical trials.

Evaluation of a robust engineered enzyme towards organophosphorus insecticide bioremediation using planarians as biosensors

Organophosphorus compounds (OPs) are neurotoxic molecules developed as insecticides and chemical warfare nerve agents (CWNAs). They are covalent inhibitors of acetylcholinesterase (AChE), a key enzyme in central and peripheral nervous systems and are responsible for numerous poisonings worldwide. Many animal models have been studied over the years but finding a suitable in vivo model to account for both acute toxicity and long-term exposure remains a topical issue. Recently, an emerging aquatic animal model harboring a mammalian-like cholinergic nervous system, the freshwater planarian from Platyhelminthes, has been used to investigate neurotoxicity and developmental disruption. Given the tremendous toxicity of OPs, various bioremediation strategies have been considered over the years to counter their poisonous effects. Among these, enzymes have been particularly highlighted as they can degrade OPs in a fast, non toxic and environmentally friendly manner. In this article we investigated the biotechnological potential for decontaminating OPs of the previously reported variant SsoPox-αsD6 from the hyperstable enzyme SsoPox, isolated from the archaea Sulfolobus solfataricus. The capacity to hydrolyze 4 new substrates (methyl-pirimiphos, quinalphos, triazophos and dibrom) was demonstrated and the degradation products generated by enzymatic hydrolysis were characterized. We further evaluated the capacity of SsoPox-αsD6 for in vivo protection of freshwater planarians Schmidtea mediterranea (Smed). The use of SsoPox-αsD6 drastically decreased mortality and enhanced mobility of planarians. Then, an enzyme-based filtration device was developed by immobilizing intact Escherichia coli cells expressing SsoPox-αsD6 into alginate beads. The efficacy of the device was demonstrated using planarians as biosensors.

Silver-based surface enhanced Raman spectroscopy devices for detection of organophosphorus pesticides traces

The detection of traces of substances by surface-sensitive techniques such as surface enhanced Raman spectroscopy (SERS) explores the interaction of adsorbed molecules on plasmonic surfaces to improve the limit of detection of analytes. This article is an overview about recent development in SERS substrates applied in the detection of organophosphorus pesticides on plasmonic surfaces (arrays of metal nanoparticles). The morphology, roughness, chemical functionalization degree, and aggregation level of plasmonic centers are some of the critical parameters to be controlled in the optimization of SERS signal from specific analytes.

Chlorpyrifos- and Dichlorvos-Induced Oxidative and Neurogenic Damage Elicits Neuro-Cognitive Deficits and Increases Anxiety-Like Behavior in Wild-Type Rats

The execution of agricultural activities on an industrial scale has led to indiscriminate deposition of toxic xenobiotics, including organophosphates, in the biome. This has led to intoxication characterized by deleterious oxidative and neuronal changes. This study investigated the consequences of oxidative and neurogenic disruptions that follow exposure to a combination of two organophosphates, chlorpyrifos (CPF) and dichlorvos (DDVP), on neuro-cognitive performance and anxiety-like behaviors in rats. Thirty-two adult male Wistar rats (150–170 g) were randomly divided into four groups, orally exposed to normal saline (NS), DDVP (8.8 mg/kg), CPF (14.9 mg/kg), and DDVP + CPF for 14 consecutive days. On day 10 of exposure, anxiety-like behavior and amygdala-dependent fear learning were assessed using open field and elevated plus maze paradigms, respectively, while spatial working memory was assessed on day 14 in the Morris water maze paradigm, following three training trials on days 11, 12, and 13. On day 15, the rats were euthanized, and their brains excised, with the hippocampus and amygdala removed. Five of these samples were homogenized and centrifuged to analyze nitric oxide (NO) metabolites, total reactive oxygen species (ROS), and acetylcholinesterase (AChE) activity, and the other three were processed for histology (cresyl violet stain) and proliferative markers (Ki67 immunohistochemistry). Marked (p ≤0.05) loss in body weight, AChE depletion, and overproduction of both NO and ROS were observed after repeated exposure to individual and combined doses of CPF and DDVP. Insults from DDVP exposure appeared more severe owing to the observed greater losses in the body weights of exposed rats. There was also a significant (p ≤0.05) effect on the cognitive behaviors recorded from the exposed rats, and these deficits were related to the oxidative damage and neurogenic cell loss in the hippocampus and the amygdala of the exposed rats. Taken together, these results provided an insight that oxidative and neurogenic damage are central to the severity of neuro-cognitive dysfunction and increased anxiety-like behaviors that follow organophosphate poisoning.

Evaluating the link between Paraoxonase-1 levels and Alzheimer's disease development

At present, the etiopathogenesis of Alzheimer's disease (AD), the most common form of dementia, remains far to be fully deciphered. In the recent years, also the centrality of amyloid-β peptide in the pathogenesis of the neurodegenerative disease has been questioned and other hypotheses have been advanced. Notably, a common denominator of many of these theoretical models is represented by oxidative stress, which is widely proposed to play a role in the disease initiation and/or progression. Paraoxonase 1 (PON1) is a high-density lipoprotein (HDL)-associated enzyme that endows its carrier with multiple biological functions, including the ability to contrast oxidative damage to lipid components of lipoproteins and cells and protect from toxicity of specific organophosphorus pesticides. The peculiar multi-functionality nature of PON1 might be the key for explaining the vast epidemiological data showing a close association between low serum PON1 activity and risk of several diseases, including cardiovascular and neurodegenerative diseases, in particular AD. In this review, we discuss the possible link between PON1 with AD pathogenesis and we hypothesize eventual mechanistic pathways that could account from epidemiological observations. We also highlight the methodological issue limitation in PON1 studies that still impede to give a definitive and certain picture of its effective biological impact on human health including AD.