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Journal of Pharmaceutical Analysis Apr 2021A highly sensitive and selective method was developed for both UV-vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method...
A highly sensitive and selective method was developed for both UV-vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method used silver nanoparticles (AgNPs) modified with graphitic carbon nitride (g-CN). The AgNPs reduced the fluorescence intensity of g-CN. Acetylthiocholine (ATCh) could be catalytically hydrolyzed by acetylcholinesterase (AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-CN, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 μg/L (S/N = 3). In addition, the absorption of the g-CN/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.
PubMed: 34012694
DOI: 10.1016/j.jpha.2020.04.007 -
Current Opinion in Structural Biology Aug 2021The evolution of novel enzymes has fueled the diversification of life on earth for billions of years. Insights into events that set the stage for the evolution of a new... (Review)
Review
The evolution of novel enzymes has fueled the diversification of life on earth for billions of years. Insights into events that set the stage for the evolution of a new enzyme can be obtained from ancestral reconstruction and laboratory evolution. Ancestral reconstruction can reveal the emergence of a promiscuous activity in a pre-existing protein and the impact of subsequent mutations that enhance a new activity. Laboratory evolution provides a more holistic view by revealing mutations elsewhere in the genome that indirectly enhance the level of a newly important enzymatic activity. This review will highlight recent studies that probe the early stages of the evolution of a new enzyme from these complementary points of view.
Topics: Evolution, Molecular; Mutation; Proteins
PubMed: 33865035
DOI: 10.1016/j.sbi.2021.03.001 -
Heliyon Feb 2021This study assessed pesticide usage practices, knowledge and health effects of pesticides through occupational exposure in randomly selected horticultural farmers in...
This study assessed pesticide usage practices, knowledge and health effects of pesticides through occupational exposure in randomly selected horticultural farmers in Imenti North, Imenti South and Buuri Sub-counties in Meru, Kenya, where horticultural crops are grown intensively for export and local consumption. The study was done through use of questionnaire distributed to farmers' households, agricultural extension workers and health care workers. The survey established that various classes of pesticides were used in horticultural crop farming and animal production in all the three sub-counties, with the most frequently used (>60 respondents out of 173) being parathion, diazinon, dimethoate, permethrin, pirimiphos methyl, endrin, deltamethrin, dieldrin, propoxur and endosulfan. It was found that there is a gap between the existing government regulations on pesticide use and safe handling and the implementation of these regulations by dealers, farmers and farm workers in the three sub-counties as some of the pesticides that were being used such as parathion, endrin, dieldrin and carbofuran had been banned by the government. Although most farmers had general information on pesticide usage through various social groups and contact with agricultural extension workers, only 32-43 % of the farmers had received training on pesticide handling and use. Most farmers (65%) had knowledge of safe pesticide handling procedures including reading labels on packages and wearing protective clothing; but many farmers (44% in Buuri, 57% in Imenti South and 60% in Imenti North) did not wear the requisite protective clothing when applying pesticides. The agricultural extension workers (52%) and health care workers (59%) were trained in their work and had at least a certificate level qualification from a tertiary institution. Most agricultural extension workers (95%) and health care workers (71%) had experience of dealing with pesticides and knew how to administer 1 AID against pesticide poisoning, respectively. Farmers (26%) reported experiencing health effects after using pesticides, with most effects being felt after using dimethoate, malathion, carbofuran, carbaryl and heptachlor. There was a statistically significant (p < 0.05) association between various factors (availability of protective clothing, hiring of labourers, farm land size, expenditure on pesticides and expenditure on treatment, respectively) on intoxication from pesticide exposure.
PubMed: 33659728
DOI: 10.1016/j.heliyon.2021.e06118 -
International Journal of Environmental... Feb 2021(1) Background: Organophosphorus pesticides (OPPs) are major chemicals used in agriculture for eradication of insecticides/pesticides. Unfortunately, the longtime...
(1) Background: Organophosphorus pesticides (OPPs) are major chemicals used in agriculture for eradication of insecticides/pesticides. Unfortunately, the longtime exposure of human beings to OPPs could lead to metabolic disorder such as high blood pressure, hyperglycemia, overweight or dyslipidemia. The aim of this research is to evaluate the possible metabolic dysregulations as a consequence of chronic OPPs exposure to individuals in Cameroon and Pakistan. (2) Methods: Blood samples were collected from 300 participants in each country, into ethylenediaminetetraacetic acid (EDTA) tubes. The samples were extracted with solid phase extraction (methanol/water) for analysis of OPPs with gas chromatography mass spectrometry. The spectrophotometry and Enzyme Linked ImmunoSorbent Assay (ELISA) were used to measure the hepatic, renal, pancreatic and cardiovascular functions. The atherogenic index (AI) was also determined in OPPs exposed and nonexposed cohorts. (3) Results: The results showed the presence of malathion, parathion and chlorpyrifos OPPs residues in Cameroonians, and malathion and chlorpyrifos in Pakistani samples, respectively. Elevated Body Mass Index (BMI), insulin, blood glucose, dyslipidemia and hypertension were noted in OPPs chronic exposed groups. In addition, dysregulated liver and kidney function profiles were observed in all participants regardless of gender and age groups. (4) Conclusions: The study concludes that both the study cohorts showed several metabolic dysregulations attributable to chronic exposure to a mixture of OPPs which may provide precursors for establishment of metabolic syndrome and other chronic diseases. Further different extended population-based studies are suggested to understand the differential metabolic dysfunctions caused by structurally different OPPs mixtures exposure.
Topics: Cameroon; Humans; Insecticides; Organophosphorus Compounds; Pakistan; Pesticides
PubMed: 33652791
DOI: 10.3390/ijerph18052310 -
Oncology Reports Apr 2021Cancer development is a multistep process that may be induced by a variety of compounds. Environmental substances, such as pesticides, have been associated with...
Cancer development is a multistep process that may be induced by a variety of compounds. Environmental substances, such as pesticides, have been associated with different human diseases. Organophosphorus pesticides (OPs) are among the most commonly used insecticides. Despite the fact that organophosphorus has been associated with an increased risk of cancer, particularly hormone‑mediated cancer, few prospective studies have examined the use of individual insecticides. Reported results have demonstrated that OPs and estrogen induce a cascade of events indicative of the transformation of human breast epithelial cells. studies analyzing an immortalized non‑tumorigenic human breast epithelial cell line may provide us with an approach to analyzing cell transformation under the effects of OPs in the presence of estrogen. The results suggested hormone‑mediated effects of these insecticides on the risk of cancer among women. It can be concluded that, through experimental models, the initiation of cancer can be studied by analyzing the steps that transform normal breast cells to malignant ones through certain substances, such as pesticides and estrogen. Such substances cause genomic instability, and therefore tumor formation in the animal, and signs of carcinogenesis . Cancer initiation has been associated with an increase in genomic instability, indicated by the inactivation of tumor‑suppressor genes and activation of oncogenes in the presence of malathion, parathion, and estrogen. In the present study, a comprehensive summary of the impact of OPs in human and rat breast cancer, specifically their effects on the cell cycle, signaling pathways linked to epidermal growth factor, drug metabolism, and genomic instability in an MCF‑10F estrogen receptor‑negative breast cell line is provided.
Topics: Animals; Breast; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Epithelial Cells; Estrogens; Female; Genomic Instability; Humans; Insecticides; Malathion; Parathion; Rats; Signal Transduction
PubMed: 33649804
DOI: 10.3892/or.2021.7975 -
Neurotoxicology Mar 2021Due to the increasing number of drugs and untested environmental compounds introduced into commercial use, there is recognition for a need to develop reliable and... (Comparative Study)
Comparative Study
Due to the increasing number of drugs and untested environmental compounds introduced into commercial use, there is recognition for a need to develop reliable and efficient screening methods to identify compounds that may adversely impact the nervous system. One process that has been implicated in neurodevelopment is neurite outgrowth; the disruption of which can result in adverse outcomes that persist later in life. Here, we developed a green fluorescent protein (GFP) labeled neurite outgrowth assay in a high-content, high-throughput format using induced pluripotent stem cell (iPSC) derived human spinal motor neurons and cortical glutamatergic neurons. The assay was optimized for use in a 1536-well plate format. Then, we used this assay to screen a set of 84 unique compounds that have previously been screened in other neurite outgrowth assays. This library consists of known developmental neurotoxicants, environmental compounds with unknown toxicity, and negative controls. Neurons were cultured for 40 h and then treated with compounds at 11 concentrations ranging from 1.56 nM to 92 μM for 24 and 48 h. Effects of compounds on neurite outgrowth were evaluated by quantifying total neurite length, number of segments, and maximum neurite length per cell. Among the 84 tested compounds, neurite outgrowth in cortical neurons and motor neurons were selectively inhibited by 36 and 31 compounds, respectively. Colchicine, rotenone, and methyl mercuric (II) chloride inhibited neurite outgrowth in both cortical and motor neurons. It is interesting to note that some compounds like parathion and bisphenol AF had inhibitory effects on neurite outgrowth specifically in the cortical neurons, while other compounds, such as 2,2',4,4'-tetrabromodiphenyl ether and caffeine, inhibited neurite outgrowth in motor neurons. The data gathered from these studies show that GFP-labeled iPSC-derived human neurons are a promising tool for identifying and prioritizing compounds with developmental neurotoxicity potential for further hazard characterization.
Topics: Cell Line; Genes, Reporter; Green Fluorescent Proteins; High-Throughput Screening Assays; Humans; Induced Pluripotent Stem Cells; Neural Stem Cells; Neuronal Outgrowth; Neurons; Risk Assessment; Toxicity Tests
PubMed: 33508353
DOI: 10.1016/j.neuro.2021.01.003 -
Journal of Health & Pollution Dec 2020Cowpea is a leguminous crop commonly grown and eaten in Nigeria. Organophosphate insecticides are frequently used to control insect populations in cowpea crops.
BACKGROUND
Cowpea is a leguminous crop commonly grown and eaten in Nigeria. Organophosphate insecticides are frequently used to control insect populations in cowpea crops.
OBJECTIVES
The present study was conducted to investigate the concentrations of organophosphate insecticide residues in cowpea varieties in Gwagwalada, Nigeria, and assess health risks to consumers.
METHODS
Samples of brown and white cowpea varieties were collected from Gwagwalada market, Abuja, Nigeria. Concentrations of organophosphate insecticide residues in the cowpea samples were analyzed by gas chromatography-mass spectrometry with selective ion monitoring. Risk evaluation was carried out by the determination of estimated daily intake, hazard quotient and chronic hazard index.
RESULTS
The organophosphates detected in the cowpea varieties were malathion, parathion, ethion and carbophenothion. The concentrations of insecticides in the cowpea types were higher than the maximum residue limits recommended by the European Union (EU) and the Agency for Toxic Substances and Disease Registry (ATSDR). The hazard quotient values were less than 100% for malathion, parathion and ethion in the cowpea varieties for adults and children. The hazard quotient of carbophenothion for adults was below 100% for the cowpea types, while the hazard quotient surpassed 100% for children. The chronic hazard indexes for children were 364% and 276% for the brown and white cowpea types, respectively.
CONCLUSIONS
The results obtained in the present study indicate that consumers, particularly children, may be exposed to health risks through the consumption of cowpea types. Consequently, monitoring and regulation of organophosphate insecticide usage in Nigeria should be intensified.
PubMed: 33324500
DOI: 10.5696/2156-9614-10.28.201203 -
Frontiers in Microbiology 2020is an attractive host for the directed evolution of the enzymes whose substrates cannot be transported across cell membrane. However, the generation of a mutant library...
is an attractive host for the directed evolution of the enzymes whose substrates cannot be transported across cell membrane. However, the generation of a mutant library in suffers problems of small library size, plasmid instability, and heterozygosity. Here, a large library of random mutant was created by inserting error-prone PCR (epPCR) products to the chromosome of . Specifically, the epPCR product was fused with flanking regions and antibiotic resistant marker using a PCR-based multimerization method, generating insertion construct. The epPCR product was integrated into the chromosome via homologous recombination after the insertion construct was transformed into the supercompetent cells of strain SCK6. The transformation efficiency of the insertion construct was improved through co-expressing homologous recombination-promoting protein NgAgo, raising the number of competent cells, and increasing the length of flanking regions. A library containing 5.31 × 10 random mutants was constructed using per μg insertion construct, which is sufficient for directed evolution. The library generation process was accomplished within 1 day. The effectiveness of this method was confirmed by improving the activity of Methyl Parathion Hydrolase (MPH) toward chlorpyrifos and by enhancing the secretion level of MPH in . Taken together, the present work provides a fast and efficient method to integrate epPCR products into the chromosome of , facilitating directed evolution and expression optimization of target proteins.
PubMed: 33281764
DOI: 10.3389/fmicb.2020.570280 -
Frontiers in Public Health 2020Organophosphates (OP) are a major agrochemical. The application of OP pesticides is expected to increase multifold in the coming decades. The etiology of diabetic...
Organophosphates (OP) are a major agrochemical. The application of OP pesticides is expected to increase multifold in the coming decades. The etiology of diabetic diseases is attributed to multiple factors including OP pesticide exposure. The present study investigates pancreatic dysregulation with respect to exocrine enzymes and diabesity in groups of Pakistani and Cameroonian people exposed to a mixture of OP pesticides. Nine hundred and four OP exposed individuals were enrolled for this cross-sectional study after due consent and approval from an ethical review committee. Pesticides' residues were measured by GC-MS spectrometry. Cholinergic enzymes were measured by Elman's method. Serum glucose, insulin, serum amylase, lipase, and triglyceride were measured by spectrophotometry and ELISA; HOMA-IR was determined in OP exposed and non-exposed participants. Stata 15 and R 3.2.0 software were used for statistical analysis of the data. Malathion, chlorpyrifos, and parathion residues were evident in plasma samples. RBC-acetylcholinesterase was significantly depressed in OP exposed groups. In both population samples, investigated pancreatic functions were found to be statistically significantly more dysregulated than non-exposed. OP exposure indicated risk of diabetes and insulin, glycaemia, adiponectin, triglycerides, and TNF-α dysregulations. The study concludes that both OP exposed population groups exhibited a mixture of OP residues and pancreatic dysregulation, although the effect was more pronounced in the Cameroonian population. In addition, serum lipase has a positive correlation with OP exposure and diabetes and may be suggested as an alternate/additional diagnostic marker for diabesity under OP exposure. However, screening of other environmental co-factors with OP for pancreatic dysregulation is suggested.
Topics: Chlorpyrifos; Cross-Sectional Studies; Humans; Insecticides; Organophosphorus Compounds; Pesticides
PubMed: 33194944
DOI: 10.3389/fpubh.2020.534902 -
Beilstein Journal of Nanotechnology 2020Methyl parathion (MP) is one of the most neurotoxic pesticides. An inexpensive and reliable one-step degradation method of MP was achieved through an aqueous suspension...
Methyl parathion (MP) is one of the most neurotoxic pesticides. An inexpensive and reliable one-step degradation method of MP was achieved through an aqueous suspension of copper(I) oxide nanoparticles (NPs). Three different NPs sizes (16, 29 and 45 nm), determined with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), were synthesized using a modified Benedict's reagent. H nuclear magnetic resonance (NMR) results show that the hydrolytic degradation of MP leads to the formation of 4-nitrophenol (4-NPh) as the main product. While the P=S bond of MP becomes P=O, confirmed by P NMR. Although CuO is a widely known photocatalyst, the degradation of methyl parathion was associated to the surface basicity of CuO NPs. Indirect evidence for the basicity of CuO NPs was achieved through UV-vis absorption of 4-NPh. Likewise, it was shown that the surface basicity increases with decreasing nanoparticle size. The presence of CuCO on the surface of CuO, identified using X-ray photoelectron spectroscopy (XPS), passivates its surface and consequently diminishes the degradation of MP.
PubMed: 33133999
DOI: 10.3762/bjnano.11.137