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Paraquat (PQ) is a bipyridyl derivative herbicide known to cause lung toxicity partly through induction of apoptosis. Here we demonstrated that PQ caused apoptosis in A549 cells. PQ increased cleavage of caspase-8 and Bid, indicating caspase-8 activation and truncated Bid, the two key mediators of extrinsic apoptosis. Additionally, PQ treatment caused an increase in DR5 (death receptor-5) and caspase-8 interaction, indicating formation of DISC (death-inducing signaling complex). These results indicate that PQ induces apoptosis through extrinsic pathway in A549 cells. Moreover, PQ drastically increased DR5 expression and membrane localization. Furthermore, PQ caused prominent concentration dependent reductions of DDX3 (the DEAD box protein-3) and GSK3 (glycogen synthase kinase-3) which can associate with DR5 and prevent DISC formation. Additionally, PQ decreased DR5-DDX3 interaction, suggesting a reduction of DDX3/GSK3 anti-apoptotic complex. Inhibition of GSK3, which is known to promote extrinsic apoptosis by its pharmacological inhibitor, BIO accentuated PQ-induced apoptosis. Moreover, GSK3 inhibition caused a further decrease in PQ-reduced DR5-DDX3 interaction. Taken together, these results suggest that PQ may induce extrinsic pathway of apoptosis in A549 cells through upregulation of DR5 and repression of anti-apoptotic proteins, DDX3/GSK3 leading to reduction of anti-apoptotic complex. [ABSTRACT FROM AUTHOR]

Paraquat (1,1’-dimethyl-4,4’-bipyridinium) (PQ), is a nonselective contact herbicide that is highly toxic to humans. The kidney is affected during PQ intoxication. Dexamethasone (Dexa) has anti-inflammatory effects and is used to treat cases of PQ poisoning. We investigated in rat kidney hemodynamic effects and immunohistochemical characteristics of Dexa treatment in acute PQ poisoning. Adult male rats were divided into four groups: 1, untreated control; 2, treated with 100 mg/kg Dexa; 3, treated with 25 mg/kg PQ; 4, treated with PQ + Dexa. Mean arterial pressure (MAP) and heart rate (HR) were recorded during the experimental period (2 h). Tissues were removed after 2 h and immunohistochemistry was performed after 24 h. Paraffin sections of kidney were prepared and anti-cyclo-oxygenase-1 (COX-1), anti-cyclo-oxygenase-2 (COX-2), anti-angiotensin converting enzyme (ACE), anti-aquaporin-1 (AQU-1), anti-vascular cell adhesion molecule (VCAM) primary antibodies were used for immunohistochemical examination. Immunoreactivities were scored as: (1) minimal, (2) weak, (3) mild, (4) moderate, (5) strong and (6) very strong. MAP and HR were measured at 10 min, 20 min, 1 h and 2 h. MAP at 10 and 20 min and 1 h was increased in the Dexa group. HR also was increased in all groups compared to controls at 2 h. Compared to groups 2 and 4, MAP values decreased significantly in group 3 at 1 h. The intensity of all of immunoreactivities was decreased in group 2. In group 3, immunoreactivities of COX-1, COX-2 and ACE were decreased compared to the control and the other groups, whereas AQU-1 and VCAM immunoreactivities were the same as the control group. ACE and VCAM immunoreactivities were decreased in group 4 compared to the control group, while COX-1, COX-2 and AQU-1 immunoreactivities were close to those of the control group. Dexa appears to be useful for treating PQ intoxication. [ABSTRACT FROM PUBLISHER]

The diversity of plants in agricultural systems benefits natural enemies. Herbicides are used in weed management in corn {Zea mays L.) to reduce competition and productivity losses, but they can impact natural enemies and contaminate the environment. The objective was to evaluate toxicity of herbicides on pupae parasitoid Palmistichus elaeisis Delvare and LaSalle, 1993 (Hymenoptera: Eulophidae). The treatments were represented by the host pupae Tenebrio molitor L., 1785 (Coleóptera: Tenebrionidae) and herbicides atrazine, nicosulfuron, paraquat, and tembotrione in commercial doses compared to a control treatment with water. Pupae of T. molitor were immersed in the solution of herbicides and exposed to parasitism by six females of P. elaeisis each. The herbicides atrazine and paraquat were highly toxic and, therefore, not selective to P. elaeisis. Nicosulfuron reduced the sex ratio of P. elaeisis (0.20 ± 0.03), which may affect subsequent generations. Moreover, the herbicide tembotrione was selective to P. elaeisis, showing results comparable to the control. Floristic diversity of weeds can increase food source, habitat, shelter, breeding places and microclimates for insect parasitoids but herbicides formulations can be toxic and these products can affect P. elaeisis or its hosts by direct or indirect contact, showing the importance of selectivity studies for this natural enemy. However, the herbicide tembotrione was selective to P. elaeisis and it can be recommended for programs of sustainable management of weeds in corn crop with this parasitoid. [ABSTRACT FROM AUTHOR]

Poisoning by paraquat herbicide is a major medical problem in parts of Asia while sporadic cases occur elsewhere. The very high case fatality of paraquat is due to inherent toxicity and lack of effective treatments. We conducted a systematic search for human studies that report toxicokinetics, mechanisms, clinical features, prognosis and treatment. Paraquat is rapidly but incompletely absorbed and then largely eliminated unchanged in urine within 12-24 h. Clinical features are largely due to intracellular effects. Paraquat generates reactive oxygen species which cause cellular damage via lipid peroxidation, activation of NF-κB, mitochondrial damage and apoptosis in many organs. Kinetics of distribution into these target tissues can be described by a two-compartment model. Paraquat is actively taken up against a concentration gradient into lung tissue leading to pneumonitis and lung fibrosis. Paraquat also causes renal and liver injury. Plasma paraquat concentrations, urine and plasma dithionite tests and clinical features provide a good guide to prognosis. Activated charcoal and Fuller's earth are routinely given to minimize further absorption. Gastric lavage should not be performed. Elimination methods such as haemodialysis and haemoperfusion are unlikely to change the clinical course. Immunosuppression with dexamethasone, cyclophosphamide and methylprednisolone is widely practised, but evidence for efficacy is very weak. Antioxidants such as acetylcysteine and salicylate might be beneficial through free radical scavenging, anti-inflammatory and NF-κB inhibitory actions. However, there are no published human trials. The case fatality is very high in all centres despite large variations in treatment. [ABSTRACT FROM AUTHOR]

The article focuses on the study that develops a method using capillary electrophoresis with diode-array detection (CE-DAD) to detect paraquat in oral fluid (OF), plasma, and urine for diagnosis of acute poisoning related to herbicide. An experiment was performed on a capillary electrophresis system model Hpx3DCE provided with on-column DAD. The study reveals that the absence of extraction steps requiring the analyte chemical reduction made the method simple and lessen analysis time.

The article presents a study which examines the genotoxicity and cytotoxicity of the herbicide Paraquat (PQ) in two phylogenetically distant test-systems. The study utilized the distant-test systems such as the barley's root tip meristem cells and the human lymphocytes in vitro to determine the genotoxic and cytotoxic effects caused by the PQ herbicide. The study assessed the herbicide's cytotoxicity through the mitotic index (MI) while for genotoxicity, frequency of micronuclei (MN) and chromosome aberrations (CA) were utilized. The study showed that the human lymphocytes were more responsive to the effects of the herbicide relative to the distant test-systems used.

Four herbicides, atrazine, simazine, paraquat, and glyphosate were tested for their acute and chronic toxicity as well as repellent effects on five common carabid beetles (Amara sp., Agonum sp., Pterostichus sp., Anisodactylus sp., and Harpalus sp.) in laboratory and greenhouse experiments. These carabid species are potential biocontrol agents and interference with their biology through herbicide applications, either directly or indirectly, could lead to soil pest outbreaks. Short-term field studies also were conducted to verify laboratory and greenhouse results. The four herbicides did not have significant acute or chronic effects on male or female carabid longevity or food consumption during one year after exposure to initial field-rate applications. Only simazine and atrazine had a repellent effect on carabids, which lasted approximately three days in greenhouse studies. Behavioral studies indicate that once carabids, especially smaller ones (< 10 mm in length), establish burrows and foraging territories, they tend to remain in these areas and migrate out of them only slowly. There was no toxic or repellent effect of any herbicide in the field. Carabids, instead, apparently responded to the destruction of plant material which provided a less favorable habitat for the larger (> 10 mm length) carabids. Glyphosate and paraquat had the greatest effect on carabids by the second week in field studies, with significantly fewer large carabids found in these two treatments than in the control. Large carabids did not return to paraquat- and glyphosate-treated field areas until approximately 28 days after application; consequently, lower rates of predation of early-season lepidopteran pests by these carabid species may occur in no-tillage corn fields that utilize herbicides for weed control. [ABSTRACT FROM AUTHOR]

Objective: Paraquat is a pesticide widely used around the world as herbicide. The toxicity of this molecule on human beings is high as it induces after ingestion liver and renal failure with possible delayed pulmonary fibrosis. After numerous reports about this major toxicity the European authorities decided to withdraw this herbicide of the market in July 2007. The authors report a collective case of poisoning with paraquat in French Guiana in 2011. Method: A teenager boy and his mother ingested paraquat deliberately. Hepatic and renal failures were observed for the young male who was treated with the immunosuppressive protocol treatment in order to prevent the pulmonary complications. His mother rapidly developed multi-organic failure. Results: The young boy's hepatic and renal failure evolved quickly favorably. No respiratory disturbances were reported with him allowing a discharge after 16 days of hospitalization. His mother who ingested higher quantities of paraquat died in 2 days. Conclusion: This collective case proves that 4 years after the prohibition of paraquat in French Guiana it is still possible to observe life-threatening poisonings induced by such a dangerous herbicide. [ABSTRACT FROM AUTHOR]