Two cases of diquat poisoning in adolescent children

Diquat (DQ) is among the most widely used herbicides, and its intake can cause severe systemic toxicity that manifests rapidly. The resultant symptoms can cause the dysfunction of a range of tissues and organs,. As there is no specific antidote for diquat poisoning and the efficacy of extant treatments is suboptimal, physicians must acquire a more comprehensive understanding of the most effective approaches to managing affected patients. Relative few studies have been published to date focused on diquat poisoning in pediatric patients. In this report, we compare two similar cases of juvenile diquat poisoning with dynamic changes in clinical manifestations, laboratory values, and imaging results. For the first time, the difference in whether to perform blood flow perfusion and the time difference of initiation of hemoperfusion had a clear clinical difference in the subsequent effects of diquat poisoning in children with diquat poisoning. Limited evidence is available regarding the efficacy of early hemoperfusion for diquat poisoning; however, the differences in clinical outcomes articulated here highlight the benefits of early and timely hemoperfusion therapy in the treatment of DQ toxicity in children, in conjunction with primary supportive care in the management of DQ poisoning in children.

[Diquat poisoning leads to ARDS: report of two cases]

Diquat (DQ) is a non-selective, foliage-applied herbicide that is known to cause liver and kidney damage, while the impact on the lungs is relatively mild. Current domestic and international reports on diquat poisoning primarily focus on liver and kidney injuries, with limited documentation of cases leading to acute respiratory distress syndrome (ARDS) and lung damage. This paper presents a retrospective analysis of two documented cases of diquat poisoning, both exhibiting ARDS. In both cases, the condition rapidly progressed upon the onset of ARDS despite aggressive treatment, ultimately resulting in the death of the patients.

Development of LC-MS/MS analytical method for the rapid determination of Diquat in water and beverages

This study aimed to develop simple, fast, and sensitive methods for the determination of diquat (DQ) in various matrices such as water and beverages. For water, direct injection was tested first, however, the sensitivity of the incurred samples were too low and couldn't possibly achieve the targeted limit of quantification. Hence, dilution with "weaker" injection solvents were tested, and the final conditions involved the dilution of water with acetonitrile (0.4 % ammonium hydroxide) which increased the sensitivity by more than ten times. Nevertheless, the beverages samples needed further treatment to achieve acceptable spiked recovery. The final conditions involved extraction using the aforementioned solvent, followed by heating and partitioning. Both of the methods satisfied the validation requirements, with an average recovery ranging from 85.9 to115 % and associated relative standard deviation (RSD %) within the range 3-8. Further applications on real samples were done to test the levels of contamination.

Imaging Findings and Toxicological Mechanisms of Nervous System Injury Caused by Diquat

Diquat (DQ) is a nonselective bipyridine herbicide with a structure resembling paraquat (PQ). In recent years, the utilization of DQ as a substitute for PQ has grown, leading to an increase in DQ poisoning cases. While the toxicity mechanism of DQ remains unclear, it is primarily attributed to the intracellular generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) through the process of reduction oxidation. This results in oxidative stress, leading to a cascade of clinical symptoms. Notably, recent reports on DQ poisoning have highlighted a concerning trend: an upsurge in cases involving neurological damage caused by DQ poisoning. These patients often present with severe illness and a high mortality rate, with no effective treatment available thus far. Imaging findings from these cases have shown that neurological damage tends to concentrate on the brainstem. However, the specific mechanisms behind this poisoning remain unclear, and no specific antidote exists. This review summarizes the research progress on DQ poisoning and explores potential mechanisms. By shedding light on the nerve damage associated with DQ poisoning, we hope to raise awareness, propose new avenues for investigating the mechanisms of DQ poisoning, and lay the groundwork for the development of treatment strategies for DQ poisoning. Trial registration number: 2024PS174K.

Simultaneous determination of diquat, paraquat, glufosinate, and glyphosate in plasma by liquid chromatography/tandem mass spectrometry: from method development to clinical application

Diquat (DQ), paraquat (PQ), glufosinate (GLU), and glyphosate (GLYP) are commonly used herbicides that have been confirmed to be toxic to humans. Rapid and accurate measurements of these toxicants in clinical practice are beneficial for the correct diagnosis and timely treatment of herbicide-poisoned patients. The present study aimed to establish an efficient, convenient, and reliable method to achieve the simultaneous quantification of DQ, PQ, GLU, and GLYP in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS) without using derivatization or ion-pairing reagents. DQ, PQ, GLU, and GLYP were extracted by the rapid protein precipitation and liquid-liquid extraction method and then separated and detected by LC-MS/MS. Subsequently, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, extraction recovery, matrix effect, dilution integrity, and stability were evaluated to validate the method based on the FDA criteria. Finally, the validated method was applied to real plasma samples collected from 166 Chinese patients with herbicide poisoning. The results showed satisfactory linearity with low LOD (1 ng/mL for DQ and PQ, 5 ng/mL for GLU, and 10 ng/mL for GLYP, respectively) and low LOQ (5 ng/mL for DQ and PQ, 25 ng/mL for GLU and GLYP, respectively). In addition, the precision, accuracy, extraction recovery, and stability of the method were acceptable. The matrix effect was not observed in the analyzed samples. Moreover, the developed method was successfully applied to determine the target compounds in real plasma samples. These data provided reliable evidence for the application of this LC-MS/MS method for clinical poisoning detection.

Autophagy mediated FTH1 degradation activates gasdermin E dependent pyroptosis contributing to diquat induced kidney injury

Acute kidney injury (AKI) induced by diquat (DQ) progresses rapidly, leading to high mortality, and there is no specific antidote for this chemical. Our limited knowledge of the pathogenic toxicological mechanisms of DQ has hindered the development of treatments against DQ poisoning. Pyroptosis is a form of programmed cell death and was recently identified as a novel molecular mechanism of drug-induced AKI. To explore the role of pyroptosis in HK-2 cells exposed to DQ, the plasma membrane damage of the cells was detected by LDH release assay. Western blot was performed to detect the cleavage of GSDME. Proteomics analysis was performed to explore the mechanism of DQ induced nephrotoxicity. FerroOrange probe was used to measure the intracellular Fe2+ levels. Herein, we show that DQ induces pyroptosis in HK-2 cells. Mechanistically, DQ induces the accumulation of mitochondrial ROS and initiates the cleavage of gasdermin E (GSDME) in an intrinsic mitochondrial pathway. Knockout of GSDME attenuated DQ-induced cell death. Further analysis revealed that loss of FTH1 induces Fe2+ accumulation, contributing to DQ-induced pyroptosis. Knockdown LC3B could help restore the expression of FTH1 and improve cell viability. Moreover, we found DFO, an iron chelator, could reduce cellular Fe2+ levels and inhibit pyroptosis. Collectively, these findings suggest an unrecognized mechanism for GSDME-dependent pyroptosis in DQ-induced AKI.

Elucidating the mechanisms underlying astrocyte-microglia crosstalk in hippocampal neuroinflammation induced by acute diquat exposure

The transition from paraquat (PQ) to diquat (DQ), both organic dication herbicides, in China has led to significant increases in the number of acute DQ poisoning cases. Case studies have shown that acute DQ poisoning resulted in injury to the central nervous system (CNS), but the mechanism underlying the injury remains to be explored. The present study aimed to investigate how DQ influenced purinergic signaling between astrocytes and microglia and whether extracellular ATP (eATP) was involved in promoting neuroinflammation induced by acute DQ toxicity through the activation of the P2X4/NLRP3 signaling pathway. We constructed a rat model of acute DQ toxicity to observe the pathological changes in hippocampal tissues after DQ exposure and measure the expression levels of IL-1β and TNF-α in the hippocampal tissue. We also established an in vitro co-culture model of C6 astrocytes and BV-2 microglia using transwell chambers, measured the amount of eATP secreted into C6 astrocytes after DQ treatment, and assessed the inflammatory response and changes in the P2X4/NLRP3 signaling pathway in BV-2 microglia. The results showed that the neurons in the hippocampal tissue of rats exhibited loose arrangement, nuclear consolidation, and necrosis after DQ exposure, and IL-1β and TNF-α levels were signification higher in the hippocampal tissue after DQ exposure. DQ exposure to the co-cultured cells induced an increase in ATP secretion from C6 astrocytes as well as a significant increase of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. In contrast, pretreatment of C6 astrocytes with apyrase (an ATP hydrolase) resulted in a significant decrease of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. Furthermore, inhibition of P2X4 expression in BV-2 microglia by transfection with si-P2X4 effectively reversed the increase of NLRP3, IL-1β, and IL-18 in BV-2 microglia induced by DQ when co-cultured with C6 astrocytes. These results indicate that astrocytes can activate the P2X4/NLRP3 signaling pathway in microglia through the DQ-induced extracellular release of ATP to promote neuroinflammation in rat hippocampal tissue.

Non-cytochrome P450 enzyme aldehyde oxidase is involved in the oxidative metabolic pathway of diquat and its detoxification effect

Diquat (DQ) poisoning has garnered attention in recent years, primarily due to the rising incidence of cases worldwide, coupled with the absence of a viable antidote for its treatment. Despite the fact that diquat monopyridone (DQ-M) has been identified as a significant metabolite of DQ, the enzyme responsible for its formation remains unknown. In this study, we have identified aldehyde oxidase (AOX) as a vital enzyme involved in DQ oxidative metabolism. The metabolism of DQ to DQ-M was significantly inhibited by AOX inhibitors including raloxifene and hydralazine. The source of oxygen incorporated into DQ-M was proved to be from water through a H218O incubation experiment which further corroborated DQ-M formation via AOX metabolism. The product of DQ-M in vitro generated by fresh rat tissues co-incubation was consistent with its AOX expression. The result of the molecular docking analysis of DQ and AOX protein showed that DQ is capable of binding to AOX. Furthermore, the cytotoxicity of DQ was significantly higher than DQ-M at the same concentration tested in six cell types. This work is the first to uncover the involvement of aldehyde oxidase, a non-cytochrome P450 enzyme, in the oxidative metabolic pathway of diquat, thus providing a potential target for the development of detoxification treatment.

Mid-to-late stage diquat accumulation in the central nervous system: A severe case of oral poisoning

A 54-year-old woman in good health was admitted to our hospital with diquat poisoning. The patient drank an unknown dose of diquat, and acute kidney injury developed early. However, there were no obvious pulmonary abnormalities and no signs of central nervous system toxicity in the early stage. The woman underwent active treatment, which resulted in a significant decrease in blood diquat levels, but her lung condition progressively worsened and neurological symptoms developed. Fortunately, the patient survived after intensive hemoperfusion combined with continuous renal replacement therapy (CRRT), intracranial pressure reduction, and anti-infective treatment. This case report highlights the importance of being aware of the development of delayed pulmonary symptoms and neurologic complications when caring for patients poisoned with diquat, even in those with low diquat blood concentrations. Interestingly, we also detected the concentration of diquat in the cerebrospinal fluid (CSF) of patients with diquat poisoning, and found that the rate of decrease of diquat concentration in the CSF was considerably slower than that in the blood.Notably, a specific correlation was observed between the concentration of diquat in the CSF, rather than in the blood, and both the intracranial pressure (ICP) and the severity of cerebral edema in this patient.

Simultaneous determination of water-soluble herbicides using hydrophilic interaction liquid chromatography-mass spectrometry

PURPOSE

The analysis of water-soluble herbicides, including glyphosate (Glyp), glufosinate (Gluf), paraquat (PQ), and diquat (DQ), is time-consuming and expensive because they cannot be analyzed using general toxicological screening methods. Thus, this study aimed to develop a simple and rapid method to simultaneously analyze these compounds without any derivatization nor ion-pairing reagents.

METHODS

The analytes were separated using hydrophilic interaction liquid chromatography and detected using tandem mass spectrometry. The developed method was applied to plant and biological samples assuming criminal damage and poisoning cases, respectively.

RESULTS

All analytes were separated well and detected with good peak shapes. For plant samples, the herbicides were specifically detected from withered leaves using a simple extraction method. For biological samples, quantitative analysis was successfully validated, and the limit of quantification values of Glyp and Gluf were 0.2 µg/mL, and those of PQ and DQ were 1 ng/mL.

CONCLUSION

The developed method had sufficient performance for practical forensic applications including poisoning cases and malicious uses to damage commercial crops.

Clinical and pathological characteristics of diquat poisoning-related acute kidney injury

Objectives: Diquat has replaced paraquat in agricultural areas as a herbicide but has led to extensive poisoning. Unlike paraquat, which targets the lungs, diquat primarily targets the kidneys. Autopsies and animal experiments suggest that interstitial kidney damage is the most critical renal lesion. Diquat is a nonselective chemical widely used for terrestrial and aquatic plants after the ban on paraquat. Although diquat is known to affect the kidneys mainly, no study has reported renal biopsy in patients with diquat poisoning.Methods: We investigated the histopathologic feature in a young man with diquat poisoning who developed acute kidney injury by renal biopsy.Results: Autopsy and animal experiments suggest that interstitial kidney inflammation is the most critical renal lesion. Surprisingly, our results showed that lipid degeneration and acute tubular injury with limited interstitial inflammation were the dominant histologic findings in this patient. Conclusions: Based on a renal biopsy, this was the first study describing the characteristics of the kidney affected by diquat poisoning. Our findings might provide information for managing patients who develop AKI due to diquat poisoning.

[A Preliminary Study on the Plasma Metabolomic Profiles of Patients Suffering From Acute Diquat Poisoning]

Objective

To analyze the plasma metabolomic features of patients suffering from acute diquat (DQ) poisoning and to explore the molecular mechanism and potential biomarkers of DQ poisoning.

Methods

A total of 7 patients suffering from acute DQ poisoning were enrolled in the DQ poisoning group. The poisoning of these patients occurred within a 12-h window at the time of enrollment. Meanwhile, 7 healthy immediate family members of the patients were enrolled as the normal controls. Liquid chromatography-mass spectrometry (LC-MS) was used to perform non-targeted metabolomic profiling of the plasma samples and to screen and identify differential metabolites and metabolic pathways.

Results

A total of 104 metabolites were screened and identified (P<0.05 and the variable importance in the projection [VIP]>1). Compared with those of the control group, 61 metabolites, such as sorbitol and galactitol, were up-regulated, and 43 metabolites, such as myo-inositol and gamma-glutamylcysteine, were down-regulated in the DQ poisoning group. Pathway enrichment analysis revealed changes in 11 metabolic pathways, including those for galactose metabolism and linoleic acid metabolism (P<0.05).

Conclusion

Metabolomics analysis of plasma samples from DQ poisoning patients shows that DQ mainly interferes with the metabolism of energy, amino acids, and lipids, thus causing metabolic disorders. Some potential biomarkers closely associated with oxidative stress and organ damage of the liver, kidney, and nervous system have been identified.

Study on the therapeutic effect of glucocorticoids on acute kidney injury in rats exposed to diquat

AIMS

To preliminarily explore, whether glucocorticoids have a therapeutic effect on diquat-induced acute kidney injury in rats.

METHOD

150 Wistar rats were randomly divided into six groups: exposure model group (DQ group), dexamethasone control group (GC group), blank control group (Ctrl group), dexamethasone 2.1 mg/kg dose group (DQ+L-GC group), dexamethasone 4.2 mg/kg dose group (DQ+M-GC group), and dexamethasone 8.4 mg/kg dose group (DQ+H-GC group), with 25 rats in each group. Each group was further divided into five subgroups, 24 h, 3 d, 7 d, 14 d, and 21 d after exposure, according to the feeding time and the course of treatment, with five animals in each subgroup. The rats in DQ, DQ+L-GC, DQ+M-GC, and DQ+H-GC groups were administered 115.5 mg/kg diquat by gavage, respectively. Moreover, 30 min after gavage, rats in DQ+L-GC group, DQ+M-GC group, DQ+H-GC group and GC group were intragastric administered dexamethasone 2.1 mg/kg, 4.2 mg/kg, 8.4 mg/kg and 8.4 mg/kg, respectively. After 7 days, the intraperitoneal injection of dexamethasone was changed to 6.3 mg/kg prednisone by intragastric administration. Subsequently, 7 days later, it was changed to 3.15 mg/kg prednisone by intragastric administration until the end of the experiment on 21 days. After the start of the experiment, changes in the conditions of the rats in each group were observed at a fixed time every day, changes in the body weight of the rats were monitored at the same time, and the death of the rats was recorded at 24 h, 3 d, 7 d, 14 d, and 21 d after exposure. The rats were sacrificed by an intraperitoneal injection of 100 mg/kg sodium pentobarbital overdose. Blood was collected by puncture of the inferior vena cava, used to determine Cr and BUN. The upper segment of the left kidney was collected for histopathological examination. Elisa was used to detect neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in the lower segment of left kidney. TLR4, Myd88, and NF-κB were detected in the right kidney.

RESULTS

(1) After exposure, most rats in DQ group, DQ+L-GC group, DQ+M-GC group and DQ+H-GC group showed shortness of breath, oliguria, diarrhea, yellow hair and other symptoms. No symptoms and related signs were observed in Ctrl group and GC group. (2) The weight of rats in the Ctrl group and the GC group increased slowly during the test. the body weight of the rats in the DQ, DQ+L-GC, DQ+M-GC, and DQ+H-GC groups continued to decrease after self-infection. Body weight dropped to the lowest point at approximately 7 d, and gradually increased from 7 d to 21 d. (3) A small amount of capillary congestion in the medulla was observed after 7 days in the GC group. The DQ group showed tubular atrophy, edema of the epithelial cells, and over time, the tubules were seen dilated and became irregular in shape; large amount of capillary congestion was also observed in the renal cortex and medulla. The renal injury in the DQ+L-GC group was less than that in the DQ group. DQ+H-GC group had no obvious injury before 7 d, but more renal tubules were seen in the DQ+H-GC group from 7 d to 14 d. (4) Compared with the DQ group, there was no difference before 14 d, and at 14 d-21 d, DQ+L-GC group, DQ+M-GC group, DQ+H-GC group all had different degrees of decline. NGAL content: Compared with the DQ group, the content of NGAL and KIM-1 in kidney tissue of the DQ+L-GC, DQ+M-GC, and DQ+H-GC groups decreased compared with the DQ group at each time node. (5) Compared with the Ctrl group, the expression of TNF-α, TLR4, MyD88, NF-κB in the DQ, DQ+L-GC, DQ+M-GC, and DQ+H-GC groups at each time node increased in the renal tissue. The content of TNF-α, TLR4, MyD88, NF-κB in kidney tissue of the DQ+L-GC, DQ+M-GC, and DQ+H-GC groups at each time node was lower than that in the DQ group.

CONCLUSION

(1) Diquat can cause kidney damage in rats, mainly manifested as renal tubular atrophy, epithelial cell edema, capillary congestion and dilation, and the renal function damage indicators have been improved to varying degrees. (2) Glucocorticoids have therapeutic effects on acute kidney injury in rats exposed to diquat. During the treatment, the efficacy of glucocorticoids did not increase with increasing doses after reaching a dose of 4.2 mg/kg. (3) TLR4 receptor-mediated TLR4/Myd88/NF-κB signaling pathway is involved in the inflammatory response of acute kidney injury in diquat poisoning rats. Glucocorticoids can inhibit the inflammatory response, thereby affecting the expression of TLR4/Myd88/NF-κB signaling pathway-related proteins.

Acute diquat poisoning case with multiorgan failure and a literature review: A case report

BACKGROUND

With the withdrawal of paraquat from the market, diquat is widely used, so the treatment of diquat poisoning has become one of the focuses of emergency poisoning diagnosis and treatment.

CASE SUMMARY

We studied the case of a 17-year-old male patient who drank 200 mL (20 g/100 mL) of diquat solution two hours before arriving at the hospital. Despite the use of treatments such as gastric lavage, hemoperfusion, continuous hemodialysis, glucocorticoids, and organ support, the patient's condition rapidly progressed to multiorgan failure, and he died 23.5 h after admission.

CONCLUSION

We summarized the clinical characteristics and treatment strategies of diquat poisoning through this case and performed a literature review to provide a basis and direction for clinical treatment.

[A case of delayed peripheral neuropathy caused by diquat poisoning]

Diquat is a kind of conductive contact-killing herbicides. The damage of central nervous system is relatively common, but the peripheral neuropathy caused by diquat has not been reported yet. In September 2021, we treated a patient with diquat poisoning. During the hospitalization, the patient was diagnosed with peripheral neuropathy. Therapy for peripheral nerve injury was given on the basis of conventional treatment of poisoning. The patient was discharged after his condition was stable. The follow-up showed that the peripheral neuropathy of patient was better than before. According to the condition of this patient, it is suggested that we should not only protect the function of gastrointestinal tract, liver, kidney, and central nervous system early, but should also pay attention to the damage of peripheral nervous system in clinical work. We should intervene earlier to improve the prognosis of patients.

Metabolomics profile of plasma in acute diquat-poisoned patients using gas chromatography-mass spectrometry

Diquat (DQ) has been confirmed to be toxic to humans and responsible for severe health impairment. While to date, very little is known about the toxicological mechanisms of DQ. Thus, investigations to discover the toxic targets and potential biomarkers of DQ poisoning are urgently needed. In this study, a metabolic profiling analysis was conducted to reveal the changes of metabolites of plasma and find out the potential biomarkers of DQ intoxication by GC-MS. First, multivariate statistical analysis demonstrated that acute DQ poisoning can lead to metabolomic changes in human plasma. Then, metabolomics studies showed that 31 of the identified metabolites were significantly altered by DQ. Pathway analysis indicated that three primarily metabolic pathways including phenylalanine, tyrosine and tryptophan biosynthesis, taurine and hypotaurine metabolism, and phenylalanine metabolism were affected by DQ, resulting in the perturbations of phenylalanine, tyrosine, taurine, and cysteine. Finally, the results of receiver operating characteristic analysis showed the above four metabolites could be used as reliable tools for the diagnosis and severity assessments of DQ intoxication. These data provided the theoretical basis for basic research to understand the potential mechanisms of DQ poisoning, and also identified the desirable biomarkers with great potential for clinical applications.

Rapid identification and quantification of diquat in biological fluids within 30 s using a portable Raman spectrometer

Rapid detection of diquat (DQ) is essential in clinical diagnosis and rescue. Here, we developed a fast, simple-yet-practical detection strategy for the reliable identification and quantification of DQ in biological fluids. Based on surface-enhanced Raman spectroscopy (SERS), point-of-care detection was realized under the acidic condition with gold nanoparticles as the substrate. Under optimal experimental conditions, the detection limits of the strategy were 17.5 ppb and 1.99 ppm in human urine and gastric juice, respectively. High specificity and selectivity of the SERS strategy were demonstrated using common pesticides and coexisting biological substances. The method was also used to detect biofluids from 5 patients and urine samples from 10 healthy volunteers. The results were in high agreement with spectrophotometric and clinical liquid chromatography-mass spectrometry methods. The volume of urine samples required for this technique is merely 20 μL, and no preparation of the samples is required. Compared to traditional methods used in clinical settings, SERS-based methods are capable of real-time measurements that accurately provide rapid detection and response in non-laboratory settings, with great potential for on-site and point-of-care testing.

[The research progress of nervous system damage caused by diquat poisoning]

In recent years, with the withdrawal of paraquat (PQ) pesticides from the market, the number of poisoning cases caused by its substitute diquat (DQ) has shown an increasing trend year by year. Among the clinical manifestations of DQ poisoning, the damage to the central nervous system is relatively common and serious, but the specific toxicity mechanism is not clear, and there is no clear treatment. This article reviews the nervous system damage caused by DQ poisoning in order to improve the understanding systen of DQ poisoning.

Metabolomics analysis of the potential toxicological mechanisms of diquat dibromide herbicide in adult zebrafish (Danio rerio) liver

Although diquat is a widely used water-soluble herbicide in the world, its sublethal adverse effects to fish have not been well characterised. In this study, histopathological examination and biochemical assays were applied to assess hepatotoxicity and combined with gas chromatography-mass spectrometry (GC-MS)-based metabolomics analysis to reveal overall metabolic mechanisms in the liver of zebrafish (Danio rerio) after diquat exposure at concentrations of 0.34 and 1.69 mg·L^-1 for 21 days. Results indicated that 1.69 mg·L^-1 diquat exposure caused cellular vacuolisation and degeneration with nuclear abnormality and led to the disturbance of antioxidative system and dysfunction in the liver. No evident pathological injury was detected, and changes in liver biochemistry were not obvious in the fish exposed to 0.34 mg·L^-1 diquat. Multivariate statistical analysis revealed differences between profiles obtained by GC-MS spectrometry from control and two treatment groups. A total of 17 and 22 metabolites belonging to different classes were identified following exposure to 0.34 and 1.69 mg·L^-1 diquat, respectively. The metabolic changes in the liver of zebrafish are mainly manifested as inhibition of energy metabolism, disorders of amino acid metabolism and reduction of antioxidant capacity caused by 1.69 mg·L^-1 diquat exposure. The energy metabolism of zebrafish exposed to 0.34 mg·L^-1 diquat was more inclined to rely on anaerobic glycolysis than that of normal zebrafish, and interference effects on lipid metabolism were observed. The metabolomics approach provided an innovative perspective to explore possible hepatic damages on fish induced by diquat as a basis for further research.

[Imaging features of 10 patients with toxic encephalopathy caused by diquat]

Objective: To explore the CT and MRI imaging findings of diquat toxic encephalopathy. Methods: CT and MRI imaging features of 10 patients with diquat poisoning encephalopathy who had been clinically diagnosed were retrospectively reviewed. Results: CT was performed in all 10 patients, and MRI was performed in 8 patients. In 10 patients, 7 had positive signs on CT, and 8 patients with MRI examination had abnormal changes in the images. The main CT findings were symmetrical hypodensity in bilateral cerebellar hemisphere, brainstem, thalamus and basal ganglia, and swelling of brain tissue. The main MRI findings were symmetrical lesions and brain edema in the deep nuclei of cerebellar hemisphere, brainstem, thalamus and basal ganglia, low signal on T1WI, high signal on T2WI and T2-FLAIR, and cytotoxic edema on diffusion weighted imaging (DWI) . On review after treatment, both CT and MRI showed resorption of the lesion, which narrowed in size. Conclusion: The imaging findings of diquat poisoning encephalopathy are characteristic and the location of the lesion is characteristic, and CT and MRI have a certain diagnostic value in diquat poisoning encephalopathy, which is important for clinical treatment.

Identification of differentially expressed genes and pathways in diquat and paraquat poisoning using bioinformatics analysis

[Objective] In this study, differentially expressed genes (DEGs) and signaling pathways involved in diquat (DQ) and paraquat (PQ) poisoning were identified via bioinformatics analysis, in order to inform the development of novel clinical treatments. [Methods] Raw data from GSE153959 were downloaded from the Gene Expression Omnibus database. DEGs of the DQ vs. control (CON) and PQ vs. CON comparison groups were identified using R, and DEGs shared by the two groups were identified using TBtools. Subsequently, the shared DEGs were searched in the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, using the Database for Annotation, Visualization, and Integrated Discovery. A protein-protein interaction (PPI) network was constructed, and hub genes were identified using the cytoHubba plug-in in Cytoscape software. Finally, Circos and contrast plots showing the DEGs shared between mouse and human chromosomes were constructed using TBtools. [Results] Thirty- one DEGs shared by the DQ and PQ groups were identified. Enriched biological process terms included positive regulation of cell proliferation and translation. Enriched cellular component terms included extracellular region, intracellular membrane- bounded organelle and mitochondrion. Enriched molecular function terms included transcription factor activity and sequence-specific double-stranded DNA binding. Enriched KEGG pathways included the interleukin- 17 signaling pathway, tumor necrosis factor signaling pathway, and human T- cell leukemia virus 1 infection. The top ten hub genes in the PPI network were Ptgs2, Cxcl2, Csf2, Mmp13, Areg, Plaur, Fosl1, Ereg, Atf3, and Tfrc. Cxcl2, Csf2, and Atf3 played important roles in the mitogen- activated protein kinase signaling pathway. [Conclusions] These pathways and DEGs may serve as targets for gene therapy.

[Analysis of 1 case of convulsion death caused by large dose of diquat poisoning]

A retrospective analysis of a case of death from sudden convulsions caused by oral high-dose diquat was conducted, and the mechanism and treatment of central damage caused by diquat were investigated to lay the foundation for increasing the success rate of treatment of high-dose diquat poisoning. At the same time, at the same time, our clinical treatment experience has also been accumulated.

Simultaneous determination of diquat and its two primary metabolites in rat plasma by ultraperformance liquid chromatography-tandem mass spectrometry and its application to the toxicokinetic study

PURPOSE

This study aimed to develop and validate an ultraperformance liquid chromatography-tandem mass spectrometry to simultaneously determine diquat (DQ) and its two primary metabolites in rat plasma and its application to the toxicokinetic study.

METHOD

The chromatographic separation of DQ and its two primary metabolites was performed with hydrophilic interaction chromatography column by adding formic acid and ammonium acetate in mobile phase in stepwise elution mode. DQ and its two primary metabolites were detected by liquid chromatography-tandem mass spectrometry in positive mode.

RESULTS

The lower limit of quantification ranging from 0.3 to 3.0 ng/mL for DQ and its two primary metabolites was achieved by using only 50 μL of rat plasma. The maximum concentration (C_max) was 977 ng/mL, half-life (t_1/2) was 13.1 h, and area under the plasma concentration-time curve (AUC_0-t) was 2770 h*ng/mL for DQ, C_max was 47.1 ng/mL, t_1/2 was 25.1 h, and AUC_0-t was 180 h·ng/mL for diquat monopyridone (DQ-M) and C_max was 246 ng/mL, t_1/2 was 8.2 h, and AUC_0-t was 2430 h·ng/mL for diquat dipyridone (DQ-D), respectively.

CONCLUSIONS

The validated method was shown to be suitable for simultaneous determination of diquat and its two primary metabolites in rat plasma. This study is the first to study the toxicokinetics of DQ and its two primary metabolites.

Wearable sensors made with solution-blow spinning poly(lactic acid) for non-enzymatic pesticide detection in agriculture and food safety

On-site monitoring the presence of pesticides on crops and food samples is essential for precision and post-harvest agriculture, which demands nondestructive analytical methods for rapid, low-cost detection that is not achievable with gold standard methods. The synergy between eco-friendly substrates and printed devices may lead to wearable sensors for decentralized analysis of pesticides in precision agriculture. In this paper we report on a wearable non-enzymatic electrochemical sensor capable of detecting carbamate and bipyridinium pesticides on the surface of agricultural and food samples. The low-cost devices (<US$ 0.08 per unit) contained three-electrode systems deposited via screen-printing technology (SPE) on solution-blow spinning mats of poly (lactic acid) (PLA). The flexible PLA/SPE sensors can be used on flat, curved and irregular surfaces of leaves, vegetables and fruits. Detection was performed using differential pulse voltammetry and square wave voltammetry with detection limits of 43 and 57 nM for carbendazim and diquat, respectively. The wearable non-enzymatic sensor can discriminate and quantify carbendazim and diquat on apple and cabbage skins with no interference from other pesticides. The use of such wearable sensors may be extended to other agrochemicals, including with incorporation of active bio (sensing) layers for online monitoring of any type of agricultural products and foods.

Ethanol-extraction SERS strategy for highly sensitive detection of poisons in oily matrix

The sensitive detection and identification of toxicants in oily matrices have suffered from difficulty in poisoning incidents, therefore it is necessary to develop the rapid and efficient analytical method to realize the on-site screening and analyzing. In this report, the surface-enhanced Raman spectroscopy (SERS) method was used to detect paraquat and diquat poisons in various oily matrix coupled with solvent extraction. The solvent extraction not only remove interfering impurities of oily substrates, but also can enrich and separate the poisons from oily matrix. It was demonstrated that the ethanol as the extractant was suitable for the rapid separation of poisons such as paraquat (PQ) and diquat (DQ) in oily matrix (soy sauce, pasta sauce, sesame oil, chili oil). Moreover, combined with a handheld Raman spectrometer, the entire detection process was completed within 8 min with the level of 10 ppb PQ and 100 ppb DQ. Furthermore, double-blind experiments verify the reliability of this method. The results demonstrate that this rapid and convenient method could be used for the effective enrichment and sensitive detection of poisons in several oily matrix and has the grate potential application in emergency response and public safety.

Clothianidin alters leukocyte profiles and elevates measures of oxidative stress in tadpoles of the amphibian, Rana pipiens

Neonicotinoid pesticide use is widespread and highly debated, as evidenced by recent attention received from the public, academics and pesticide regulatory agencies. However, relatively little is known about the physiological effects of neonicotinoid insecticides on aquatic vertebrates. Amphibians (larval stages in particular) are excellent vertebrate bioindicators in aquatic systems due to their risk of exposure and sensitivity to environmental stressors. Previous work with wood frog (Rana sylvatica) tadpoles exposed to formulated products containing thiamethoxam or clothianidin in outdoor mesocosms found significant shifts in leukocyte profiles, suggesting the tadpoles were physiologically stressed. The main objective of the present study was to characterize this stress response further using complementary measures of stress after exposure to clothianidin on northern leopard frogs (Rana pipiens) during their aquatic larval stages. Laboratory static-renewal exposures were conducted over eight weeks with the technical product clothianidin at 0, 0.23, 1, 10 and 100 μg/L, and diquat dibromide at 532 μg/L was used as a positive control. We assessed tadpole leukocyte profiles and measures of oxidative stress as these sub-lethal alterations could affect amphibian fitness. We found changes in several types of leukocytes at 1 and 10 μg/L, suggesting that these tadpoles exhibited signs of mild physiological stress. Clothianidin also induced an oxidative stress response at 0.23, 1 and 100 μg/L. However, we found no differences in survival, growth, development time or hepatosomatic index in frogs exposed to clothianidin. Our study indicates that tadpoles chronically exposed to clothianidin have increased stress responses, but in the absence of concentration-response relationships and effects on whole-organism endpoints, the implications on the overall health and fitness of these changes are unclear.

[Liquid chromatography-tandem mass spectrometry method for the determination of paraquat and diquat in plasma and urine]

Objective: To establish a LC-MS/MS method for determination of paraquat and diquat in plasma and urine samples. Methods: Plasma is precipitated by acetonitrile then diluent with phosphate buffer (pH=7) , urine is diluent with phosphate buffer (pH=7) , then diluent samples extracted with Oasis WCX solid-phase extraction column. Samples were analyzed using LC-MS/MS in multiple reaction monitoring (MRM) mode. The analytical column was XBridge®BEH-HILIC (100 mm×2.1 mm×2.5 μm) and the mobile phase were 100 mmol ammonium formate add 0.5% formic acid and acetonitrile. Paraquat was quantified by internal standard method and diquat by external standard method. Results: The calibration curves of paraquat and diquat were linear in the concentration range of 10.0~120.0 μg/L, the correlation coefficient (r) were 0.9985~0.9994. The limit of detection of paraquat in plasma and urine were 1.98 μg/L and 1.00 μg/L, respectively, the recovery rate were 100.2%~107.3%, the RSD were 1.6%~3.3%. The limit of detection of diquat in plasma and urine were 1.80 μg/L and 2.77 μg/L, respectively, the recovery rate were 85.3%~93.1%, the RSD were 1.8%~5.5%. Conclusion: This method is sensitive and accurate, and can simultaneously determine paraquat and diquat in plasma and urine.

In vitro removal of paraquat and diquat from aqueous media using raw and calcined basil seed

Raw and calcined basil seeds (BS and BS1000, respectively) were evaluated for their ability to remove herbicides such as paraquat and diquat. The physicochemical properties of BS and BS1000 were determined and the effects of contact time and initial concentration on paraquat and diquat adsorption were assessed. After calcination treatment, the number of pores in BS increased, and the specific surface area was increased from 0.265 to 86.902 m² g^-1. The quantity of herbicides adsorbed using BS1000 was greater than that using either BS or medicinal-grade carbon. Additionally, the adsorption quantity increased with the increase in contact time and initial concentration of herbicide. Therefore, BS1000 is a potential resource for the removal of herbicides. Moreover, BS and BS1000 exhibited the capacity for herbicide adsorption in simulated intestinal fluid.

High-dose diquat poisoning: a case report

Diquat is a widely used herbicide that is substituted for paraquat. With paraquat off the market, cases of diquat poisoning have been gradually increasing. The kidney is the most frequently impaired organ in diquat poisoning. Few cases of multiple organ failure caused by diquat have been reported.

We herein describe a 30-year-old man who orally ingested about 160 mL of enriched diquat. Despite aggressive treatment, the patient’s condition progressed to multiple organ failure and death. The pulmonary lesions in this patient were different from those previously reported. This patient did not die of renal failure but of severe respiratory failure. He exhibited three different stages of pulmonary disease.

The lung lesions in this case were unique. We hope that doctors will pay more attention to the lung lesions in patients with diquat poisoning in future and find new treatment methods to save the lives of such patients.

[Four cases of acute diquat poisoning with prominent epileptoid seizure and literature review]

Objective: To further improve the awareness of the clinical feature of acute diquat poisoning. Methods: A retrospective analysis was performed on 4 cases of acute diquat poisoning with epileptoid seizure as the main clinical manifestation, which were admitted and diagnosed by the Characteristic Medical Center of Chinese People's Armed Police Force from January 1, 2017 to December 31, 2019. Take "Diquat" or "Deiquat" or "Reward" as keyword search for CNKI, Pubmed, and EMbase in both Chinese and English. The date of literature retrieval was from the database founding to December 31, 2019. Results: Of the 4 patients, 3 were male and 1 female, with an average age of 28 years (22-33 years) . The estimated dose was 8-20 g. All patients were treated with gastric lavage, catharsis, fluid replacement, blood perfusion, and in the early stage of treatment of epileptic seizures, the initial routine antiepileptic drugs had poor effect. Then propofol and midazolam were injected into the treatment. The epilepsy was relieved, but the condition deteriorated rapidly, and the patients died eventually. The literature search retrieved 3 patients in the 3 literatures included in the study were analyzed, and their clinical course was similar to that of 4 cases in the center. Necropsy was performedon all 3 patients, and the results were cerebral edema, diffuse cerebral edema, and hemorrhage around the basal ganglia. Conclusion: Acute diquat poisoning can cause epileptic seizures. Once it occurs, the disease progresses rapidly and the prognosis is poor. The combination of large dose of sedative drugs can be used to treat epilepsy in order to improve the prognosis.

Exposure Impacts of Diquat dibromide herbicide formulation on amphibian larval development

Many anthropogenic chemicals in general, and specifically aquatic herbicide formulations have the potential to modulate the thyroid pathways of the endocrine system of aquatic organisms, because they are normally applied directly into the aquatic system, to manage aquatic weeds. These thyroidal effects have been widely linked with disruption in developmental and reproductive processes. In fact, the exposure impacts of many of these substances on metamorphic organisms could produce a precocious metamorphosis. Using Xenopus Metamorphosis Assay (XEMA) protocol, this study assessed the thyroidal effects of environmentally relevant concentrations of Diquat dibromide at 0.05, 0.11, and 0.14 mg/L on Xenopus laevis metamorphosis. The formulation significantly reduced both the fore and hind limb lengths, and disrupted the developmental stage at concentrations of 0.11 and 0.14 mg/L, with a median at NF-stage 57, while median of NF-stage 60 was recorded in the control. Histopathologically, although there was no significant difference in thyroid gland area, the thyroid colloidal area was significantly reduced at 0.14 mg/L, while the mean height of the thyroid follicle increased at 0.05 mg/L The result indicates an extra-thyroidal pathway, due to the dissociation between stage developmental effects and thyroid histopathology. The role of stress pathway occasioned by oxidative mode of action, involving lipid peroxidation and cell damage observed in this study need further investigation, in order to further characterize the physiological and ecological effects on wildlife.

Simultaneous determination of paraquat and diquat in human plasma by HPLC-DAD: Its application in acute poisoning patients induced by these two herbicides

Background

Paraquat and diquat are widely used in agricultural production in many countries, which are very toxic to human beings. Paraquat can be detected in some diquat solution sold in the market. The blood concentration of paraquat or diquat is an important indicator for clinical diagnosis of paraquat or diquat poisoning. So, it is very meaningful to develop a method for simultaneous determination of paraquat and diquat in human plasma.

Objective

To develop and validate a HPLC‐DAD method for simultaneous determination of paraquat and diquat in human plasma and to apply it in the acute poisoning patients by these two herbicides.

Methods

Paraquat and diquat were simultaneously determined by HPLC‐DAD. The plasma was treated using Waters OASIS^® Column and then separated on a Thermo Hypersil GOLD (250 × 4.6 mm, 5 μm) Column with the mobile phase consisted of 75 mmol/L sodium heptane sulfonate (containing 0.1 mol/L phosphoric acid, pH 3.0) and acetonitrile (87:13, v:v) at a flow rate of 1.0 mL/min. The full‐wavelength scanning was 200‐400 nm, and the detection wavelength of paraquat and diquat was 257nm and 310nm, respectively. 120 and 30 plasma samples from patients with paraquat and diquat poisoning were collected and analyzed by the established method.

Results

The standard curve for paraquat and diquat ranged from 0.05 to 20 μg/mL, and the precision of LLOQ for paraquat was 16.49%, which was required to be less than 20%. The precision of other concentrations was less than 14.14%. The recovery of paraquat and diquat was 95.38%‐103.97% and 94.79%‐98.40%, respectively. The results showed that paraquat and diquat were stable under various storage conditions. 120 plasma samples of paraquat poisoning patients and 30 plasma samples of diquat poisoning patients were determined by the established method. The blood concentration of paraquat ranged from 0.10 to 20.62 μg/mL, with an average of 3.61 μg/mL, while for diquat, the concentration ranged from 0 to 26.59 μg/mL, with an average of 2.00 μg/mL. Among the diquat suspected poisoning samples, 5 samples were detected not only diquat but also paraquat, and 2 samples were detected only paraquat, no diquat.

Conclusion

The HPLC‐DAD method established in this study was high throughput, high sensitivity, simple operation, and wide linear ranges. It can be used for the screening analysis and quantitative detection of paraquat and diquat in acute poisoning patients, which can provide basis for the treatment and prognosis of these two herbicides poisoning patients.

[The expression of Nrf2 in the lung tissue of rats with acute diquat poisoning and the distribution of diquat in lungs]

Objective: To investigate the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the lung tissue of rats with acute diquat (DQ) poisoning and the distribution of diquat in lungs. Methods: Fifty-four fasted male Wistar rats were randomized into control group (n=6) and exposure group (n=48) . According to the time point, the exposure group was divided into 2 h, 4 h, 12 h, 1 d, 3 d, 7 d, 11 d and 14 d groups with 6 rats in each group. Exposure groups were administered 11.55 mg/kg DQ (1 ml/100 g BW) by single-dose of intragastric administration, while the control group rats were given normal saline. The histopathological changes of lung tissue of rats in each group were observed. The expression of nrf2 in lung tissue was detected by immunohistochemistry, and the diquat concentration in lungs was determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) . Results: In the exposure group, DQ was detected in lungs on 2 hours after poisoning. The concentration of DQ in lung tissue decreased gradually over time, and there was no accumulation in lung tissue. The histopathological changes of lung tissue were not obvious in the early stage of poisoning. The injury was the most serious on the 3rd day, a large number of inflammatory cells could be seen in alveolar cavity and lung stroma, and the pathological injury of lung tissue began to be alleviated on the 7th day. The results of immunohistochemistry showed that Nrf2 was mainly expressed in the nucleus of pulmonery cells. The expression of Nrf2 in the exposure group was significantly higher than the control group. The expression of Nrf2 increased significantly at the 12th hour (P<0.05) , reached the peak on the 3rd day (P<0.05) . There was no difference between the control group and the 14th day (P>0.05) . Conclusion: There was no accumulation of DQ in the lung tissue for a long time, and there was a hysteresis in lung injury induced by redox reaction of DQ. Nrf2 was highly expressed in the lung tissue of rats with acute DQ poisoning, which was correlated with histopathology injury of lung tissue, suggesting that Nrf2 plays an important role in antagonizing acute lung injury induced by DQ.

[Establishment and evaluation of acute diquat poisoning model in Wistar rats]

Objective: To establish the Wistar rat model of acute diquat poisoning and observe the pathological damage of main target organs. Methods: Thirty-six Wistar rats were randomly divided into six groups (n=6) , including one normal saline control group and five treatment groups which were separately given single-dose of intragastric administration at the doses of 46.2 mg/kg, 77.0 mg/kg, 115.5 mg/kg, 231.0 mg/kg and 346.5 mg/kg. The pathological changes of lung, liver and kidney were observed by hematoxylin and eosin (HE) and Masson staining. The optimal dose was determined according to the general situation and pathological changes. Thirty-six Wistar rats were randomly divided into five treatment groups and one normal saline control group. Treatment groups were given single-dose of intragastric administration according to the optimal dose. The rats were sacrificed at 1st, 3rd, 7th, 11th and 14th day after exposed, respectively. The activity of serum glutamic-pyruvic transaminase (ALT) and glutamic-oxalacetic transaminase (AST) were measured by chemical colorimetry. The pathological changes of lung, liver and kidney were observed by HE and Masson staining. Results: According to 14 d survival rate, the toxic symptoms and pathological changes, 115.50 mg/kg was determined the best dose. Given single-dose of intragastric administration at the doses of 115.50 mg/kg, it was found that the serum AST and ALT activity of rats on the first and third day of exposure was significant higher than those in control group. The results of pathological examination exhibited that in 115.50 mg/kg group, the pathological changes of lung, liver and kidney began to appear on the first day of exposure, the pathological changes were the most serious on the third day, and then gradually alleviated. On the 14th day, the alveolar septum was slightly widened, with inflammatory cell infiltration, local alveolar cavity became narrow, atrophy, peripheral alveolar compensation, bronchi and alveolar septum collagen fiber proliferation; The local renal tubular epithelial cells were enlarged and necrotic; the central vein surrounding hepatic cells showed vacuolar degeneration with punctate necrosis. Conclusion: The rat model of acute diquat poisoning can be successfully induced by single-dose of intragastric administration. The condition of wistar rats and the pathological damage of the main target organs could be observed during the whole course of 115.50 mg/kg administration.

[The experimental study of diquat on the half-Lethal dose and pothological injuny of related organs in wistor rats]

Objective: To explore the acute toxicity of Diquat in mice and to calculate the median lethal dose (LD(50)) of Diquat to rats and observe the pathological changes of tissues and organs in rats with different concentrations of Diquat. Methods: Diquat solution of 50 mg/kg was prepared freshly with 1 000 mg of Diquat and dilute the solution with water to a total of 20 ml. A total of 99 healthy adult male Wistar rats were randomly divided into part one, part two and control groups. In the first part, 36 rats were randomly divided into 4 groups: 100 mg/kg group, 200 mg/kg group, 300 mg/kg group and 400 mg/kg group, which were treated with 100 mg/kg, 200 mg/kg, 300 mg/kg and 400 mg/kg of Diquat solution by gavage, respectively. The death and symptoms of poisoning after intragastric administration were recorded, and the maximum tolerated dose and absolute lethal dose were measured. In the second part, 54 rats were randomly divided into 6 groups: 200 mg/kg group, 220 mg/kg group, 240 mg/kg group, 260 mg/kg、280 mg/kg group and 300 mg/kg group, whichwere treated with 200 mg/kg, 220 mg/kg, 240 mg/kg, 260 mg/kg, 280 mg/kg and 300 mg/kg of Diquat solution by gavage, respectively. The survival of rats in different concentration of Diquat was observed and the LD(50) was calculated by Excel processing the formula of Koch's method. The control group were given equal volume water under the same experimental conditions. And moreover, the lungs, kidneys, hearts, livers, and brain tissues were collected and fixed by formaldehyde, embedded by paraffin, and sectioned for histopathological light microscopy. Results: The maximum tolerated dose was 240 mg/kg and the absolute lethal dose was 300 mg/kg. The LD(50) of Diquat for Rats was 280.58 mg/kg. The high-dose group had significantly more organ damage than the low-dose group after diquat poisoning. Conclusion: The determination of the half-lethal dose of diquat, at the same time observed multiple organs damaged in rats after the diquat quickly poisoned. Kidneys, lungs and heart might be the main organ which was heavily damaged. With the extension of observation time, the organ damage of rats exposed to small doses gradually stabilized.

Adsorption of the herbicides diquat and difenzoquat on polyurethane foam: Kinetic, equilibrium and computational studies

This work reports a study about the adsorption of the herbicides diquat and difenzoquat from aqueous medium employing polyurethane foam (PUF) as the adsorbent and sodium dodecylsulfate (SDS) as the counter ion. The adsorption efficiency was shown to be dependent on the concentration of SDS in solution, since the formation of an ion-associate between cationic herbicides (diquat and difenzoquat) and anionic dodecylsulfate is a fundamental step of the process. A computational study was carried out to identify the possible structure of the ion-associates that are formed in solution. They are probably formed by three units of dodecylsulfate bound to one unit of diquat, and two units of dodecylsulfate bound to one unit of difenzoquat. The results obtained also showed that 95% of both herbicides present in 45mL of a solution containing 5.5mgL^-1 could be retained by 300mg of PUF. The experimental data were well adjusted to the Freundlich isotherm (r² ≥ 0.95) and to the pseudo-second-order kinetic equation. Also, the application of Morris-Weber and Reichenberg equations indicated that an intraparticle diffusion process is active in the control of adsorption kinetics.

A full life-cycle bioassay with Cantareus aspersus shows reproductive effects of a glyphosate-based herbicide suggesting potential endocrine disruption

A full life-cycle (240 days) bioassay using the terrestrial snail, Cantareus aspersus, allowing exposure during embryogenesis and/or the growth and reproduction phases, was used to assess the effects of Bypass®, a glyphosate-based herbicide (GlyBH), on a range of endpoints, including parameters under endocrine control. As a positive control, a mixture (R-A) made of diquat (Reglone®) and nonylphenols (NP, Agral®), known for its endocrine disrupting effects in other organisms, was tested. At environmental concentrations, both pesticides (R-A mixture and GlyBH) enhanced growth but reduced reproduction. The R-A mixture acted mainly on the fecundity through a delay in egg-laying of approximately 20 days and a strongly reduced number of clutches. This latter dysfunction may be caused by a permanent eversion of the penis, suggesting a disrupting effect at the neuro-endocrine level, which prevented normal mating. GlyBH acted on fertility, possibly due to a decrease in the fertilization of eggs laid by adults exposed during their embryonic development. These results, associated with the absence of observed effects on gonad histology of GlyBH exposed snails, suggested that the underlying mechanisms are neuro-endocrine.

Diquat-induced cellular pyridine nucleotide redox changes and alteration of metabolic enzyme activities in colonic carcinoma cells

Previously we have shown that the redox cycler menadione (MQ) induced cellular pyridine nucleotide redox imbalance that was linked to a decrease in aerobic glycolysis and perturbation of the mitochondrial respiratory activity due to the redox cycling of the compound; these processes were potentiated by low glucose. In this study, we investigated how colonic epithelial cells maintained pyridine nucleotide (NAD⁺/NADH and NADP⁺/NADPH) redox homeostasis upon acute metabolic variation and exposure to the redox cycling diquat (DQ). Our results show that DQ challenge disrupted cellular NADH/NAD⁺ redox status and enhanced cellular NADPH generation. Notably, DQ-induced NADH decrease was associated with enhanced lactate production, a process that was potentiated by glucose availability, but not by the mitochondrial substrates, succinate or malate/glutamate. In addition, DQ increased glucose 6-phoshate dehydrogenase (G6PDH) activity consistent with glucose diversion towards pentose phosphate pathway. As a consequence, steady-state NADPH levels were maintained during MQ challenge at normal glucose. In contrast and despite increased G6PDH and malic enzyme (ME) activities, DQ induced cellular NADPH-to-NADP⁺ shift at low glucose, a situation that was reversed by mitochondrial substrates. Collectively, these results are consistent with increased aerobic glycolysis by DQ and specific metabolic changes leading to enhanced NADPH generation upon oxidative challenge.

Sorption of the herbicides diquat and difenzoquat from aqueous medium by polymeric resins in the presence of sodium dodecylsulfate: Kinetic and mechanistic study

The goal of this work was to propose a novel method for the solid-phase extraction of the herbicides diquat (DQT(2+)) and difenzoquat (DFQT(+)) from aqueous medium using polymeric Amberlite XAD-2 and XAD-4 resins in the presence of sodium dodecylsulfate (SDS). The addition of SDS to the medium was of fundamental importance in order to allow the formation of a negatively charged surface able to sorb the cationic solutes. Several factors that could influence the sorption process, such as SDS concentration in the medium, sorbent mass, pH, ionic strength, and initial concentration of the solutes were investigated. Kinetic studies were also performed to model the system and to identify the mechanisms that operate the sorption process of the herbicides. SDS concentration in the medium presented remarkable influence on the extraction efficiency, achieving maximum values when the ratios [SDS]/[herbicide] were approximately 90, for XAD-2, and 22 and 11 for DQT(2+) and DFQT(+), respectively, for XAD-4. The sorption process followed a pseudo second-order kinetic in all cases studied. It was also found that an intraparticle diffusion process controlled exclusively the sorption of the herbicides by the Amberlite XAD-2 and XAD-4 resins in the first 15 min, becoming less active with time.

Magnitude and characteristics of acute paraquat- and diquat-related illnesses in the US: 1998-2013

BACKGROUND

Paraquat and diquat are among the most commonly used herbicides in the world.

OBJECTIVES

Determine the magnitude, characteristics, and root causes for acute paraquat- and diquat-related illnesses in the US METHODS: Illnesses associated with paraquat or diquat exposure occurring from 1998 through 2011 were identified from the Sentinel Event Notification System for Occupational Risks (SENSOR)-Pesticides Program, the California Department of Pesticide Regulation (CDPR) Pesticide Illness Surveillance Program (PISP), and the Incident Data System (IDS). Cases identified by the National Poison Data System (NPDS) were reviewed for the years 1998-2003 and 2006-2013.

RESULTS

A total of 300 paraquat- and 144 diquat-related acute illnesses were identified by SENSOR, PISP, and IDS. NPDS identified 693 paraquat- and 2128 diquat-related acute illnesses. In SENSOR/PISP/IDS, illnesses were commonly low severity (paraquat=41%; diquat=81%); however, SENSOR/PISP/IDS identified 24 deaths caused by paraquat and 5 deaths associated with diquat. Nineteen paraquat-related deaths were due to ingestion, seven of which were unintentional, often due to improper storage in beverage bottles. In SENSOR/PISP/IDS, paraquat and diquat-related acute illnesses were work-related in 68% (n=203) and 29% (n=42) of cases, respectively. When herbicide application site was known, the vast majority of acute paraquat-related illnesses (81%) arose from agricultural applications. Common root causes of illness were failure to use adequate personal protective equipment (PPE), application equipment failure, and spill/splash of herbicide.

CONCLUSIONS

Although the magnitude of acute paraquat/diquat-related illnesses was relatively low, several fatalities were identified. Many illnesses could be prevented through stricter compliance with label requirements (e.g. ensuring proper herbicide storage and PPE use), and through enhanced training of certified applicators.

Dietary administration of diquat for 13 weeks does not result in a loss of dopaminergic neurons in the substantia nigra of C57BL/6J mice

Male and female C57BL/6J mice were administered diquat dibromide (DQ∙Br2) in their diets at concentrations of 0 (control), 12.5 and 62.5 ppm for 13 weeks to assess the potential effects of DQ on the nigrostriatal dopaminergic system. Achieved dose levels at 62.5 ppm were 6.4 and 7.6 mg DQ (ion)/kg bw/day for males and females, respectively. A separate group of mice was administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) ip as a positive control. The comparative effects of DQ and MPTP on the substantia nigra pars compacta (SNpc) and/or striatum were assessed using neurochemical, neuropathological and stereological endpoints. Morphological and stereological assessments were performed by investigators who were "blinded" to dose group. DQ had no effect on striatal dopamine concentration or dopamine turnover. There was no evidence of neuronal degeneration, astrocytic or microglial activation, or a reduction in the number of tyrosine hydroxylase positive (TH(+)) neurons in the SNpc or neuronal processes in the striatum of DQ-treated mice. These results are consistent with the rapid clearance of DQ from the brain following a single dose of radiolabeled DQ. In contrast, MPTP-treated mice exhibited decreased striatal dopamine concentration, reduced numbers of TH(+) neurons in the SNpc, and neuropathological changes, including neuronal necrosis, as well as astrocytic and microglial activation in the striatum and SNpc.

Natural oxidation of a temperature series of biochars: opposite effect on the sorption of aromatic cationic herbicides

The natural oxidation of biochar in the environment has been widely observed. However, its influence on the sorption of organic contaminants remains poorly understood. In the present study, a series of wood-based biochars prepared between 300 and 600°C (referred to as BC300-BC600) was abiotically incubated for one year to examine the aging effect of the temperature series of biochars on their sorption of aromatic cationic herbicides (ACHs, paraquat and diquat) as well as a nonpolar reference adsorbate (naphthalene). One year of oxidation showed no obvious effect on the surface area, but distinct increases in the O/C elemental ratio, density of the surface groups and cation exchange capacity (CEC) were observed. Therefore, these properties were significantly affected by the charring temperature. After incubation, high-temperature biochars (BC500 and BC600) displayed a 14.1-36.3% decrease in the sorption (qm) of ACHs. The alteration of their sorption tendency was similar to the reduced sorption of naphthalene on oxidized biochars, in which the increased surface groups lowered the surface area accessible to adsorbates because of blockage by adsorbed water molecule clusters. Conversely, a pronounced increase of ACHs sorption by 121.7-201.1% on the low-temperature biochar (BC300) was observed, presumably due to the increase of CEC values after oxidation. This result was further demonstrated by a significant linear relationship between the paraquat sorption (qm) and CEC values (R(2)=0.9895) of oxidized biochars. Interestingly, one year of oxidation simultaneously resulted in an enhanced sorption of paraquat and a reduced sorption of diquat on BC400, which indicated that the oxidation-induced sorption change of ACHs is a complex function of changes in the surface properties of the biochars as well as the molecular structure of the solute.

Diquat causes caspase-independent cell death in SH-SY5Y cells by production of ROS independently of mitochondria

Evidence indicates that Parkinson's disease (PD), in addition to having a genetic aetiology, has an environmental component that contributes to disease onset and progression. The exact nature of any environmental agent contributing to PD is unknown in most cases. Given its similarity to paraquat, an agrochemical removed from registration in the EU for its suspected potential to cause PD, we have investigated the in vitro capacity of the related herbicide Diquat to cause PD-like cell death. Diquat showed greater toxicity towards SH-SY5Y neuroblastoma cells and human midbrain neural cells than paraquat and also MPTP, which was independent of dopamine transporter-mediated uptake. Diquat caused cell death independently of caspase activation, potentially via RIP1 kinase, with only a minor contribution from apoptosis, which was accompanied by enhanced reactive oxygen species production in the absence of major inhibition of complex I of the mitochondrial respiratory chain. No changes in α-synuclein expression were observed following 24-h or 4-week exposure. Diquat may, therefore, kill neural tissue by programmed necrosis rather than apoptosis, reflecting the pathological changes seen following high-level exposure, although its ability to promote PD is unclear.

The effect of dietary tryptophan levels on oxidative stress of liver induced by diquat in weaned piglets

Oxidative stress can induce abnormal tryptophan metabolism. The present study was mainly conducted to determine the effect of dietary tryptophan levels on oxidative stress in the liver of weaned pigs challenged by diquat. A total of 36 PIC piglets weaned at 21 days of age were randomly allotted to 1 of 3 diets containing dietary tryptophan levels of 0.18, 0.30, and 0.45% for 14 d. On day 8, the piglets were injected intraperitoneally with sterile 0.9% NaCl solution or diquat (10 mg/kg body weight). During the first 7 d of trial, increasing dietary tryptophan levels enhanced average daily gain (P = 0.09) and average daily feed intake (P = 0.08), and decreased the feed efficiency (P < 0.05) of piglets. The growth performance was decreased by diquat injection (P < 0.05). Diquat injection also decreased the activities of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the plasma and liver (P < 0.05), increased plasma malondialdehyde (MDA) (P < 0.05) and urea nitrogen (P < 0.05) concentrations, and enhanced MDA concentration (P = 0.09) and tryptophan 2,3-dioxygenase (TDO) activity (P = 0.07) in liver of piglets. Increasing dietary tryptophan levels could attenuate the effects of diquat injection on the MDA (P = 0.06) concentration and the activities of SOD (P = 0.09) and GPx (P = 0.05) of the liver, and plasma urea nitrogen (P = 0.06) concentration in the piglet. There was a synergistic role for increasing TDO activity in the liver between dietary tryptophan levels and diquat injection (P < 0.05). These results suggest that increasing dietary tryptophan levels could attenuate the oxidative stress of the liver in weaned piglets intraperitoneally injected with diquat via enhancing the antioxidant capacity.