Paraquat poisoning. An overview of the current status

Differential redox sensitivity of tRNA dihydrouridylation

Various transfer RNA (tRNA) modifications have recently been shown to regulate stress-dependent gene expression by modulating messenger RNA translation. Among these modifications, dihydrouridine stands out for its increase of tRNA structural flexibility. However, whether and how dihydrouridine synthesis reacts to environmental stimuli is largely unknown. In this study, we manipulated the intracellular redox state of Escherichia coli using paraquat, revealing differential sensitivities of the three tRNA-dihydrouridine synthases towards oxidative stress. Using liquid chromatography-mass spectrometry quantification of dihydrouridine in various knockout strains, we validated the use of a specific RNA sequencing method, namely AlkAnilineSeq, for the precise mapping of dihydrouridines throughout E. coli tRNAs. We found DusA showing high activity, followed by DusB and DusC, whose activity was decreased under paraquat treatment. The relative sensitivity is most plausibly explained by a paraquat-dependent drop of NADPH availability. These findings are substantiated by in vitro kinetics, revealing DusA as the most active enzyme, followed by DusB, while DusC showed little activity, likely related to the efficacy of the redox reaction of the flavin coenzyme with NADPH. Overall, our study underscores the intricate interplay between redox dynamics and tRNA modification processes, revealing a new facet of the regulatory mechanisms influencing cellular responses to oxidative stress.

Regulation of macrophage polarization and glucose metabolism by the ERK/MAPK-HK1 signaling pathway in paraquat-induced acute lung injury

Acute lung injury is the leading cause of paraquat (PQ) poisoning-related mortality. The mechanism by which macrophages are involved in PQ-induced acute lung injury remains unclear. In recent years, the role of metabolic reprogramming in macrophage functional transformation has received significant attention. The current study aimed to identify the role of altered macrophage glucose metabolism and molecular mechanisms in PQ poisoning-induced acute lung injury. We established a model of acute lung injury in PQ-intoxicated mice via the intraperitoneal injection of PQ. PQ exposure induces macrophage M1 polarization and promotes the release of inflammatory factors, which causes the development of acute lung injury in mice. In vitro analysis revealed that PQ altered glucose metabolism, which could be reversed by siRNA transfection to silence the expression of HK1, a key enzyme in glucose metabolism. RNA sequencing revealed that the ERK/MAPK pathway was the crucial molecular mechanism of PQ pathogenesis. Further, U0126, an ERK inhibitor, could inhibit PQ-induced HK1 activation and macrophage M1 polarization. These findings provide novel insights into the previously unrecognized mechanism of ERK/MAPK-HK1 activation in PQ poisoning.

Ferulic acid grafted into β-cyclodextrin nanosponges ameliorates Paraquat-induced human MRC-5 fibroblast injury

Paraquat (PQ) is a commercially important and effective herbicide in the world. Nevertheless, it has higher toxicity causing acute organ damage and different complications, mainly in the lungs and kidneys. Ferulic acid (FA), 4-hydroxy-3-methoxycinnamic acid imposes multiple pharmacological impacts. No protective effect of FA on PQ poisoning-caused human embryonic lung fibroblast damage has not been reported. Despite their many beneficial effects, FA is characterized by poor water solubility, low bioavailability, and phytochemical instability. To solve the problem, β-cyclodextrin nanosponge (β-CD NSs) was utilized to increase the solubility of FA so that it was grafted into β-CD NSs to establish β-CD@FA NSs. The purpose of this work was to examine for the first time the protective effect of β-CD@FA NS on MRC-5 human lung cells damages induced by PQ poisoning. MTS assay was performed to investigate the viability of MRC-5 cells at different concentrations of FA/β-CD@FA NSs when cells were co-cultured with 0.2 μg/mL PQ. The flow cytometry study was carried out to determine apoptosis. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were detected using appropriate biochemistry kits. Compared with the PQ group, the cell activity, CAT, and SOD levels were significantly increased in the FA and chiefly in β-CD@FA NSs intervention groups, whereas apoptosis and MDA levels were markedly decreased. The inflammatory factors tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 22 (IL-22) were detected. The results demonstrate that β-CD@FA NSs can inhibit PQ-induced cell damage by enhancing antioxidant stress capacity and regulation of inflammatory responses.

Acute paraquat poisoning complicated by acute kidney injury and lung fibrosis: a case report from Nepal

Introduction and importance

While incidents are rare elsewhere, paraquat herbicide poisoning is a serious medical issue in some parts of Asia. It can cause the failure of various organs, including the heart, kidneys, liver, adrenal glands, central nervous system, muscles, and spleen. Due to its inherent toxicity and lack of available therapies, paraquat has a very high case fatality rate.

Case presentation

The authors discuss a case of a 15-year-old female with an alleged history of paraquat ingestion who presented with complaints of vomiting, abdominal pain, and loose stools. Initially, she had gastrointestinal symptoms, but she developed renal failure and respiratory symptoms and died of multiple organ failure.

Clinical discussion

Acute gastrointestinal tract necrosis and multiorgan failure are the initial effects of paraquat intake, and among those who survive the immediate post-ingestion interval, the lung is the target organ for poisoning. Ingestion of large amounts of liquid concentrates results in fulminant organ failure: pulmonary edema, cardiac, renal, and hepatic failure, and convulsions. The course of treatment can range from supportive care alone to various integration of immune modulation, antioxidant therapy, hemoperfusion, and hemodialysis.

Conclusion

Patients presenting to the emergency department with an alleged history of ingestion of paraquat poisoning should be admitted even if they have mild symptoms initially. There is no specific antidote available. Early renal failure, along with progressive pulmonary fibrosis, can lead to death.

Aging, Parkinson's Disease, and Models: What Are the Challenges?

Parkinson's disease (PD) is a chronic, neurodegenerative condition characterized by motor symptoms such as bradykinesia, rigidity, and tremor, alongside multiple nonmotor symptoms. The appearance of motor symptoms is linked to progressive dopaminergic neuron loss within the substantia nigra. PD incidence increases sharply with age, suggesting a strong association between mechanisms driving biological aging and the development and progression of PD. However, the role of aging in the pathogenesis of PD remains understudied. Numerous models of PD, including cell models, toxin-induced models, and genetic models in rodents and nonhuman primates (NHPs), reproduce different aspects of PD, but preclinical studies of PD rarely incorporate age as a factor. Studies using patient neurons derived from stem cells via reprogramming methods retain some aging features, but their characterization, particularly of aging markers and reproducibility of neuron type, is suboptimal. Investigation of age-related changes in PD using animal models indicates an association, but this is likely in conjunction with other disease drivers. The biggest barrier to drawing firm conclusions is that each model lacks full characterization and appropriate time-course assessments. There is a need to systematically investigate whether aging increases the susceptibility of mouse, rat, and NHP models to develop PD and understand the role of cell models. We propose that a significant investment in time and resources, together with the coordination and sharing of resources, knowledge, and data, is required to accelerate progress in understanding the role of biological aging in PD development and improve the reliability of models to test interventions.

The efficacy of hemodialysis on paraquat poisoning mortality: A systematic review and meta-analysis

BACKGROUND

Paraquat (PQ) poisoning is a serious public health concern, especially in developing countries, due to its easy access and lack of awareness of potential harms. No effective treatment has been reported yet. Conventional hemodialysis (HD) is still used in many centers for excreting PQ or reducing acute kidney injury, but there is no consensus on its efficacy. Therefore, we aimed to review the HD efficacy in PQ poisoning mortality.

MATERIALS AND METHODS

We searched Web of Science, PubMed, Excerpta Medical Database, Google Scholar, Scopus, Cochrane, Web of Knowledge, Pro-Quest, ScienceDirect, Springer, Clinical Key, Scientific Information Database, Magiran, and Iran-doc, in publications before January 1, 2020. We compared patients who underwent HD (Group 1) with those who did not (Group 2). The outcome was considered mortality/survival. The data were analyzed by Comprehensive Meta-analysis Software.

RESULTS

This systematic review and meta-analysis included five studies with a combined total of 203 patients. The patients in the Group 1 had higher mortality than Group 2 (odds ratio, 2.84; 95% confidence interval: 1.22-6.64; P = 0.02). There was no evidence of publication bias (P value for Egger's test = 0.833).

CONCLUSION

Although HD did not affect the survival of patients, other variables such as the amount of ingested PQ, poisoning severity, the time between PQ ingestion and the start of HD, duration, and times of HD sessions may influence the results regarding mortality.

Injection of Paraquat in the Neck: A Rare Complicated Case Report

Paraquat is a highly toxic compound and a widely used herbicide that causes serious morbidity and mortality. The most well-known route of poisoning is oral ingestion, whereas parenteral injection of paraquat is individually uncommon. We present a case who injected paraquat in his neck in an attempt to commit suicide. His general condition got worsened gradually over 3 days. He received early hemodialysis in 4 h after self-injection and then supportive treatment in intensive care unit. Early hemodialysis helped him survive, but during hospitalization, some rare complications occurred, and unfortunately, he died after 3 months. Despite the high-risk route of poisoning, the patient survived for 3 months. Our patient was protected from renal and hepatic damage may be because of early hemodialysis but suffered from central nervous system and pulmonary damage.

Paraquat Poisoning Associated With Daisley Barton Syndrome: A Case Report

Pesticides include insecticides, herbicides, and rodenticides. Pesticide poisoning can be intentional, accidental, or occupational. Around 385 million cases of unintentional acute pesticide poisoning occur annually worldwide, with approximately 11,000 fatalities. Herbicides are used to kill weeds and can include chlorophenoxy compounds, bipyridyls, urea-substituted herbicides, organophosphates, and glyphosate. Paraquat is a bipyridyl nonselective contact herbicide with high mortality rates upon exposure in humans. Paraquat poisoning causes acute lung injury, rarely leading to pneumothorax and pneumomediastinum, referred to as Daisley Barton Syndrome. We report a case of a 22-year-old female from Uttarakhand, India, who accidentally ingested paraquat. She was initially asymptomatic, but later developed lung, liver, and kidney injuries as well as pneumomediastinum and pneumothorax.

A review on importance of bioactive compounds of medicinal plants in treating idiopathic pulmonary fibrosis (special emphasis on isoquinoline alkaloids)

Background

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease of unknown cause which disrupts the normal lung architecture and functions by deregulating immune responses and ultimately leads to the death of the individual. A number of factors can lead to its development and currently there is no cure for this disease.

Main text

There are synthetic drugs available to relieve the symptoms and decelerate its development by targeting pathways involved in the development of IPF, but there had also been various side effects detected by their usage. It is known since decades that medicinal plants and their compounds have been used all over the world in natural medicines to cure various diseases. This review article is focused on the effects of various natural bioactive compounds of 26 plant extracts that show prophylactic and therapeutic properties against the disease and so can be used in treating IPF replacing synthetic drugs and reducing the side effects.

Short conclusion

This review includes different mechanisms that cause pulmonary fibrosis along with compounds that can induce fibrosis, drugs used for the treatment of pulmonary fibrosis, diagnosis, the biochemical tests used for the experimental study to determine the pathogenesis of disease with a special note on Isoquinoline alkaloids and their role in reducing various factors leading to IPF thus providing promising therapeutic approach.

Alveolar-arterial partial pressure difference as an early predictor for patients with acute paraquat poisoning

Objective

Paraquat (PQ) is associated with high mortality rates in acute poisoning. This study aimed to determine the importance of the alveolar–arterial partial pressure difference (A-aDo₂) in the expected consequences of acute PQ poisoning.

Methods

Patients who were hospitalized for PQ poisoning in 2018 were enrolled in this retrospective study. A-aDo₂ data were collected. Multivariate analysis was performed using binary logistic regression to determine whether A-aDo₂ is an independent risk factor for mortality from PQ.

Results

A total of 352 cases were analyzed. The mean PQ dose was 36.84 ± 50.30 mL (0.3–500 mL). There were 185 survivors and 167 non-survivors. The mean A-aDo₂ was not significantly correlated between survivors and non-survivors on day 1. However, there were significant differences in A-aDo₂ between survivors and non-survivors on days 3, 7, 14, and 21. Increased A-aDo₂ values were correlated with an increased mortality rate. The mean A-aDo₂ on day 14 showed the most significant difference between survivors and non-survivors.

Conclusion

Our study suggests that A-aDo₂ plays an important role as a reference index, which could be a useful predictor in assessing acute PQ poisoning, especially on the 14th day after onset of poisoning.

Protective effect of genistein pre-treatment on paraquat hepatotoxicity in rats

Paraquat (PQ), an herbicide widely used in agriculture, is considered a highly toxic compound. In hepatocytes, P-glycoprotein (P-gp/Abcb1) is a canalicular transporter involved in PQ extrusion from the cell. Previously, we demonstrated that genistein (GNT) induces P-gp in rat liver. In this study, the protective role of GNT pretreatment towards hepatic damage in a model of acute intoxication with PQ in rats, was investigated. Wistar rats were randomized in 4 groups: Control, GNT (5 mg/kg/day sc, 4 days), PQ (50 mg/kg/day ip, last day) and GNT+ PQ. Hepatic lipoperoxidation (LPO) was evaluated by the thiobarbituric acid reactive substances method. Hepatic levels of 4-hydroxynonenal protein adducts (4-HNEp-add) and glutathione-S-transferase alpha (GSTα) protein expression were evaluated by Western blotting. Hepatic glutathione levels and plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST) were also measured. Biliary excretion of PQ was studied in vivo and in isolated perfused liver. PQ was quantified by HPLC. PQ significantly increased AST and ALT activities, malondialdehyde and 4-HNEp-add levels, whereby pretreatment with GNT ameliorated this effect. PQ biliary excretion remained unchanged after treatments in both experimental models. Hepatic GSTα expression was augmented in GNT group. GNT pretreatment increased hepatic glutathione levels in PQ + GNT group. These results agree with the lower content of 4-HNEp-adds in GNT + PQ group respect to PQ group. Unexpectedly, increased activity of P-gp did not enhance PQ biliary excretion. Thus, GNT protective mechanism is likely through the induction of GSTα which results in increased 4-HNE metabolism before formation of protein adducts.

Curcumin Modulates Paraquat-Induced Epithelial to Mesenchymal Transition by Regulating Transforming Growth Factor-β (TGF-β) in A549 Cells

Paraquat (PQ), a widely used potent herbicide, generates superoxide anions and other free radicals, leading to severe toxicity and acute lung injury. PQ induces pulmonary fibrosis through epithelial to mesenchymal transition (EMT) characterized by increased number of myofibroblasts. Time-dependent PQ-induced EMT has been evaluated in present investigation where intracellular ROS levels were significantly enhanced after 24 h of PQ intoxication. Anti-inflammatory effects of curcumin have been studied where alveolar epithelial cells (A549 cells) were incubated with curcumin (30 μΜ) for 1 and 3 h before PQ intoxication (700 μM). Western blot and immunocytochemistry studies revealed that pretreatment of A549 cells with curcumin for 3 h before PQ exposure has maintained E-cadherin expression and inhibited PQ induced α-smooth-muscle actin (α-SMA) expression. Transforming growth factor-β (TGF-β) that seems to be involved in PQ-induced EMT was enhanced after PQ intoxication, but curcumin pretreatment has effectively inhibited its expression. Immunostaining studies have shown that curcumin pretreatment has significantly reduced matrix metalloproteinase-9 (MMP-9) expressions, which were elevated after PQ intoxication. These results demonstrate that curcumin can regulate PQ-induced EMT by regulating the expression of TGF-β.

Paraquat exposure delays late-stage Leydig cell differentiation in rats during puberty

Paraquat is a fast and non-selective herbicide that is widely used in crop cultivation and conservation tillage systems. Animal experiments have shown that paraquat decreases sperm quality and testicular organ coefficient, but its effects on the development of Leydig cells remain unclear. The objective of the current study was to investigate the effects of paraquat exposure on the Leydig cell development in rats during puberty. Twenty-eight male 35-day-old Sprague-Dawley rats were divided into 4 groups: 0, 0.5, 2.0, and 8 mg kg^-1 d^-1 paraquat. Paraquat was gavaged for 10 d. Adult Leydig cells were isolated and treated with paraquat for 24 h. Paraquat in vivo significantly decreased body and testis weights at 8 mg kg^-1 and lowered serum testosterone levels at 2 and 8 mg kg^-1 without affecting the levels of serum luteinizing hormone and follicle-stimulating hormone. Paraquat did not alter Leydig cell number and PCNA labeling index. Real-time PCR showed that paraquat down-regulated the expression of Lhcgr, Scarb1, Cyp11a1, Cyp17a1, and Hsd17b3 genes and their proteins at 2 or 8 mg kg^-1, while it up-regulated the expression of Srd5a1 at 8 mg kg^-1. Paraquat increased ROS and decreased testosterone production by Leydig cells at 1 and 10 μM after in vitro 24-h exposure. Vitamin E (40 μg/ml) reversed paraquat-induced ROS and suppression of testosterone synthesis in vitro. In conclusion, paraquat directly delays Leydig cell differentiation to block testosterone synthesis via down-regulating the expression of critical testosterone synthesis-related genes and up-regulating the expression of testosterone metabolic enzyme (Srd5a1) gene and possibly via increasing ROS production.

Hepatoprotective effect of N-acetylcystein loaded niosomes on liver function in paraquat-induced acute poisoning

Paraquat (PQ) is widely used as a herbicide around the world. PQ intoxication causes liver disease mainly in mammals. N-acetyl cysteine (NAC) is a medication that has positive effects in reducing the liver intoxication caused by PQ. Here, after formulating a NAC noisome nanoparticle (NACNP), we compared the niosomes and NAC on liver toxicity caused by PQ. Thirty male rats were divided into 5 groups and were treated intraperitoneally with PQ and NAC and NACNP for 24 h. PQ group received 35 mg/kg/day of PQ, while NAC and NACNP groups were administered with 25 mg/kg/day of NAC and NACNP, respectively. In addition, 6 rats receiving saline solution were considered as control group. Serum and liver tissue samples were collected from all rats. Alanine (AST) and aspartate (ALT) aminotransferase levels, and oxidative stress biomarkers including total antioxidant capacity (TAC), lipid peroxidation (LPO), and total thiol groups (TTG) levels were determined. Histological samples were also analyzed using hematoxylin and eosin staining slides. PQ administration resulted in hepatic injury as evidenced by increases in serum AST and ALT levels (p < .001). NACNP decreased LPO, TAC, and TTG levels compered to PQ group in liver tissue. Treatment of animals with NACNP was significantly more effective than free NAC in reducing PQ-induced hepatotoxicity (p < .05). Histological evaluation showed that PQ caused tissue inflammation, which was reduced by NAC treatment. This reduction was stronger for NACNP. Given these results, the use of NACNP, compared to NAC, was more protective against the development of the PQ-induced liver toxicity.

Paraquat exposure delays stem/progenitor Leydig cell regeneration in the adult rat testis

Paraquat, a widely used nonselective herbicide, is a serious hazard to human health. However, the effects of paraquat on the male reproductive system remain unclear. In this study, adult male Sprague Dawley rats were intraperitoneally injected ethane dimethane sulfonate (EDS, 75 mg/kg) to initiate a regeneration of Leydig cells. EDS-treated rats were orally exposed to paraquat (0.5, 2, 8 mg/kg/day) from post-EDS day 17 to day 28 and effects of paraquat on Leydig and Sertoli cell functions on post-EDS day 35 and day 56 were investigated. Paraquat significantly decreased serum testosterone levels at 2 and 8 mg/kg. Paraquat lowered Leydig cell Hsd17b3, Srd5a1, and Hsd11b1 mRNA levels but increased Hsd3b1 on post-EDS day 35. Paraquat lowered Cyp11a1, Cyp17a1, and Hsd11b1 but increased Srd5a1 on post-EDS day 56. However, paraquat did not alter Leydig cell number and PCNA labeling index. Epididymal staining showed that few sperms were observed in paraquat-treated rats. Primary culture of adult Leydig cells showed that paraquat diminished testosterone output and induced reactive oxygen species generation at 1 and 10 μM and apoptosis rate at 10 μM. In conclusion, a short-term exposure to paraquat delays Leydig cell regeneration from stem/progenitor Leydig cells, causing low production of testosterone and an arrest of spermatogenesis.

Does hemoperfusion in combination with other treatments reduce the mortality of patients with paraquat poisoning more than hemoperfusion alone: A systematic review with meta-analysis

BACKGROUND

Paraquat (PQ) poisoning is a serious public health problem in many countries. In spite of different treatments, the mortality is still high. We performed a meta-analysis to see whether hemoperfusion (HP) in combination with other treatments reduces the mortality more than HP alone in patients with PQ poisoning.

MATERIALS AND METHODS

We searched EMBASE, PubMed, Google Scholar, ISI Web of Knowledge, Cochrane Central Register of Controlled Trials, Scopus, Springer, TRIP, ProQuest, and references of the included studies from January 2000 to August 2017. Two reviewers independently searched and extracted data. We measured I 2 to determine variance contributed by heterogeneity. To investigate the publication bias, Begg's and Egger's tests were used along with funnel plot analysis.

RESULTS

Ultimately 12 articles were included in the meta-analysis. Five articles compared HP with conventional therapy with a total of 1311 patients, and seven articles compared mortality of patients received HP versus those received HP in combination with an additional treatment. HP alone reduced the odds of death (odds ratio [OR] = 0.20; 95% confidence interval [CI]: 0.11-0.40, P < 0.0001) compared to conventional therapy. Furthermore, the odds of death was higher in HP group compared to those received HP in combination of additional treatments (OR = 1.24; 95% CI: 1.05-1.46, P = 0.01).

CONCLUSION

The mortality was less in HP-treated group compared to those received only conventional therapy. Addition of other treatments with HP reduced the mortality more than HP alone.

Prolonged low-dose cyclophosphamide treatment after pulse therapy attenuates lung injury in rats with paraquat intoxication

BACKGROUND/AIMS

This study tested the hypothesis that prolonged low-dose cyclophosphamide (CTX) treatment after pulse therapy attenuate paraquat (PQ)-induced lung injury in rats.

METHODS

PQ (25 mg/kg) was administered intraperitoneally to induce PQ-intoxicated rat model. The rats were randomly divided into four groups: control group (1 mL/day saline solution for 14 days), PQ group (1 mL/day saline solution for 14 days after PQ exposure), pulse group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1 mL/day saline solution for 12 days), and prolonged low-dose group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1.5 mg/kg/day CTX in 1 mL of saline solution for 12 days). A 14-day follow-up was conducted to determine the survival rat, and lung hydroxyproline (HYP), wet-to-dry weight ratios (W/Dc) and histopathological changes were evaluated.

RESULTS

Results showed similar survival rate (55% vs. 50%, p > 0.05) between prolonged low-dose and pulse groups. Lung W/Dc (4.94 ± 0.38 vs. 5.47 ± 0.28, p < 0.01), HYP (3.34 ± 0.29 µg/mg vs. 3.65 ± 0.19 µg/mg, p < 0.001), and fibrosis score (2.69 ± 0.84 vs. 3.13 ± 0.63, p < 0.05) were lower in prolonged low-dose group than those in the pulse group.

CONCLUSION

These findings suggested prolonged low-dose CTX treatment after pulse therapy could attenuate PQ-induced lung injury in rats.

Development of a physiologically based pharmacokinetic model of paraquat

Paraquat (N, N'-dimethyl-4,4'-bipyridium dichloride) is a potent and widely used herbicide in agricultural countries, including Thailand. The presence of this chemical in the body can lead to toxic effects in the liver, kidney, and lung. Pulmonary toxicity has been identified as the main cause of acute toxicity in animals and humans. Chronic exposure to paraquat is associated with Parkinson's disease in humans. Paraquat is transported into the lungs by neutral amino acid transporter. Therefore, a physiologically based pharmacokinetic (PBPK) model of paraquat was developed with a description of the protein transporter mechanism. To develop a PBPK model of paraquat, a pharmacokinetic study of paraquat in rats was selected from the ThaiLIS and Pubmed database. The selected study contained tissue-specific concentration-time course information such as paraquat concentration levels in liver, kidney and lung. Physiologic parameters were acquired from the literature or determined using a Markov-Chain Monte Carlo (MCMC) technique. The developed PBPK model consisted of 5 organ compartments (i.e. kidney, liver, slowly perfused organs, richly perfuse organs and lung), featuring an incorporation of neutral amino acid transporter in the lung. Our model simulations could explain the data from the literature and adequately describe pharmacokinetics of paraquat in the rats. This developed PBPK model may be able help in understanding of paraquat-induced Parkinson's disease as well as in risk assessment of paraquat.

Increased plasma prothrombin time is associated with poor prognosis in patients with paraquat poisoning

BACKGROUND

Paraquat can cause severe injury to vascular endothelial cells and lead to coagulation dysfunction when it is taken into the blood by oral ingestion. In this study, we aim to find a routine coagulation index to serve as an indicator of outcome in patients with acute paraquat poisoning.

METHODS

Between January 2012 and December 2016, 209 patients who attempted suicide by oral ingestion of paraquat were admitted to the emergency room. Routine coagulation indices, including plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fbg), thrombin time (TT), and D-dimer were measured to analyze the trend of changes and their relationship with prognosis.

RESULTS

The results showed that the PT and APTT values in the ≥30 mL group were significantly greater than those in the <30 mL group (both P < .01). Within 1 week of admission, PT and APTT values gradually decreased, while Fbg levels gradually increased. Univariate and multivariate Cox regression analysis indicated that sex, ingestion volume, and PT were independent predictors of mortality within 40 days. The cumulative survival rates differed significantly (P = .001) between patients with PT <12 seconds and PT ≥12 seconds.

CONCLUSIONS

Coagulation status in patients with PQ poisoning was closely related to prognosis. Routine monitoring of coagulation function, particularly PT in plasma, is helpful for analysis of the condition and prognosis of patients with PQ poisoning.

A facile fluorescent "turn-off" method for sensing paraquat based on pyranine-paraquat interaction

Development of a technically simple yet effective method for paraquat (PQ) detection is of great importance due to its high clinical and environmental relevance. In this study, we developed a pyranine-based fluorescent "turn-off" method for PQ sensing based on pyranine-PQ interaction. We investigated the dependence of analytical performance of this method on the experimental conditions, such as the ion strength, medium pH, and so on. Under the optimized conditions, the method is sensitive and selective, and could be used for PQ detection in real-world sample. This study essentially provides a readily accessible fluorescent system for PQ sensing which is cheap, robust, and technically simple, and it is envisaged to find more interesting clinical and environmental applications.

Paraquat treatment modulates integrin associated protein (CD47) and basigin (CD147) expression and mitochondrial potential on erythroid cells in mice

The present study is focused on the interaction of paraquat with the erythroid system in bone marrow and spleen of mice. Administration of paraquat (10 mg/kg of body weight i.p. on alternate days in C57Bl/6 mice) induced the level of reactive oxygen species in bone marrow (BM) on 7, 14, and 21 day time points but it was unchanged in spleen erythroid cell. A marked induction of CD147 expression in BM and spleen erythroid cells was observed in the paraquat treated mice. Paraquat treatment also modulated the CD47 expression in erythroid cells and its expression level was significantly higher on day 14, 21 and 28 in bone marrow and on day 14 and 21 in spleen. The expression level of mitochondrial potential and antioxidant genes SOD1, SOD2, GPX1 and FOXO3 expression was significantly reduced in BM erythroid cells but a reverse response was seen in spleen. Taken together, this study demonstrates that paraquat treatment modulates ROS production, mitochondrial membrane potential, and oxidative stress markers gene expression in the erythroid systems of C57Bl/6 mice.

Case Series of Paraquat Poisoning in Tuen Mun Hospital

Paraquat is highly toxic to human and is widely used in agriculture as a contact herbicide. However, it is easily accessible in agricultural product shops. Seven cases of paraquat poisoning were treated in Tuen Mun Hospital from 1998–2005. The mortality (4 out of 7) was very high. One patient died after oral exposure to paraquat despite immunosuppressive and antioxidant therapies. The mechanism of toxicity and potential new therapies of paraquat poisoning are discussed in the article.

Pneumocystis Pneumonia Infection in a Survivor of Paraquat Intoxication

Patients who survived recent paraquat intoxication might be treated with glucocorticoid andcyclophosphamide to avoid further lung fi brosis. Such patients might be susceptible to opportunistic infections. Pneumocystis pneumonia (PCP) is an important opportunistic lung infection in hematologic malignancy patients on chemotherapy. We report a patient who recently survived paraquat intoxication and presented with acute respiratory insuffi ciency post glucocorticoid and cyclosporine treatment. A fulminant clinical course, and a clear medical history of immunocompromised state draw physician's attention to the possible opportunistic lung infection. PCP infection was confi rmed by a PCP deoxyribonucleic acid test. The symptoms improved markedly after appropriate antibiotics treatment. This report suggests that clinicians should consider PCP infection in patients who develop secondary pneumonia after paraquat intoxication. PCP treatment as part of empirical antibiotics should be added, especially in such patients presented with rapidly progressive course.

Discernment scheme for paraquat poisoning: A five-year experience in Shiraz, Iran

AIM

To evaluate various schemes for paraquat poisoning and different variables that influence the outcome of acute paraquat poisoning.

METHODS

In a cross-sectional study, the information about all cases of acute paraquat poisoning who were admitted to teaching hospitals affiliated to Shiraz University of Medical Sciences, in a five year period (September 2010 to September 2015) were evaluated. The variables included: Demographic data, medical assessment, therapeutic options, laboratory findings, and the outcomes. Data were analyzed using SPSS, version 22. Significant difference between groups was tested using t-test for continues outcomes and χ² test for categorical. The significance level was considered to be P < 0.05.

RESULTS

A total of 104 patients (66.3% male) were evaluated. The mean age of the female patients was 22.81 ± 9.87 years and the male patients’ was 27.21 ± 11.06 years. Ninety seven (93.3%) of all the cases were suicide attempts with mortality rate of 43.2%. Despite the necessity for emergency hemodialysis during the first 6 h of intoxication, none of the patients had dialysis during this time. Immunosuppressive and corticosteroid medications were not administrated in adequate dosage in 31.1% and 60% of the patients, respectively. Ingestion of more than 22.5 cc of paraquat and increase in creatinine level were the most important predictors of mortality.

CONCLUSION

Treatment should start immediately for these patients. Moreover, creating a clinical guideline according to the findings can have an impact on the treatment procedure which seems to be necessary.

Antioxidant effects of aqueous extract of Salep on Paraquat-induced rat liver injury

AIM

To evaluate the effects of aqueous extract of Salep on Paraquat-mediated liver injury.

METHODS

In this experimental study, 56 adult male Wistar rats were divided randomly to 7 groups as control, sham, and 5 experimental groups. In control group, rats did not receive any substance during experiment. In Sham group, rats were given distilled water according to their body weight and in experimental groups, Paraquat alone and with different doses of Salep aqueous extract (40, 80, 160 and 320 mg/kg) was given intraperitoneal daily for 14 d. After that, liver biochemical parameter and histologic changes were analyzed and compared in different groups.

RESULTS

Paraquat compared to control and sham groups, significantly (P < 0.05) increased serum level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), bilirubin, malondialdehyde (MDA) and total oxidant capacity (TOC); while level of total protein, albumin and total antioxidant capacity (TAC) were remarkably decreased by Paraquat. Salep at doses of 80, 160 and 320 mg/kg significantly decreased serum level of ALT, AST, ALP, bilirubin, MDA and TOC and significantly increased total protein, albumin and TAC level as compared to Paraquat exposed group in dose dependent manner. Aqueous extract of Salep at doses of 40 mg/kg made no significant changes in serum level of mentioned biochemical parameters. Liver microscopic observation revealed that Paraquat could cause hepatocyte necrosis, degenerative changes, proliferation and activation of Kupffer cells (sporadically) which were reduced by Salep treatment.

CONCLUSION

Salep possesses remarkable hepatoprotection activity against Paraquat-induced hepatic injury by having antioxidant activity and reducing lipid peroxidation and oxidative stress.

Hepatoprotective role of captopril on paraquat induced hepatotoxicity

Paraquat (PQ) is a highly toxic herbicide that is used in most of the countries without restriction. The cytotoxic effect of PQ is mediated by radicals, which are the products of PQ reduction in cells. The anti-oxidative action of captopril, an angiotensin-converting enzyme inhibitor, appears to be through its ability to scavenge reactive oxygen species. In this study, the heptoprotective effect of captopril against PQ-induced hepatotoxicity was evaluated using primary cultured rat hepatocytes. Hepatocytes were isolated from male Wistar rats using a two-step collagenase perfusion, following incubation in the presence of captopril at 0.1, 0.2, 0.4 and 0.8 mM with or without PQ (5 mM). Hepatoprotective effects of captopril were studied indicating glutathione level intensity, thiobarbituric acid reactive substances (TBARs) formation, lactate dehydrogenase (LDH) leakage and cell viability every 70 min for 210 min. Captopril at 0.2 mM concentration maintained the LDH leakage, glutathione level and cell viability in the presence of 5 mM PQ. In spite of a significant elevation in TBARs formation in the PQ group, captopril did not show any significant protection. In conclusion, our data reveals that incubation of freshly isolated rat hepa-tocytes with captopril (0.2 mM) significantly protected the hepatocytes against the cytotoxicity of PQ ( P < 0.05). Human & Experimental Toxicology (2007) 26, 789— 794

Effect of haemoperfusion on plasma paraquat concentration in vitro and in vivo

This study was to observe the paraquat (PQ) reduction rate after haemoperfusion (HP) on the groups of a relatively large number: 50 survivors out of 105 patients with acute PQ poisoning. We started off by measuring the clearance of haemodialysis (HD) and HP for the PQ in vitro. At the blood flow of 250 mL/min, the PQ clearance was greater in HP than in HD during the first 90 minutes: 215 versus 175 mL/min at 30 minutes, 213 versus 201 mL/min at 60 minutes, and 199 versus 179 mL/min at 90 minutes. The clearance in HP decreased rapidly after two hours. By the end of the dialysis, however, the final concentration in container decreased to 5.7 mg/mL in HD and 1.5 mg/mL in HP, which implied that although HD was cleared more effectively during the later stages, the overall elimination was greater in HP. Following this preliminary investigation, we performed HP on all the patients in order to assess the extracorporeal elimination.

One hundred and five patients who had swallowed one to three mouthfuls of PQ (24.5% w/v) solution were subjected to the in vivo study. The reduction rate of PQ was checked out by measuring the PQ concentration in plasma before and after four hours of HP. Seeing the reduction rate was significantly higher in the survivors group than in the nonsurvivors group (80.39 ± 19.9 versus 67.29 ± 19.2%, P <0.01), we concluded that adequate HP appears to be an indispensable treatment for patients with acute PQ poisoning.

Acute paraquat exposure determines dose-dependent oxidative injury of multiple organs and metabolic dysfunction in rats: impact on exercise tolerance

This study investigated the pathological morphofunctional adaptations related to the imbalance of exercise tolerance triggered by paraquat (PQ) exposure in rats. The rats were randomized into four groups with eight animals each: (a) SAL (control): 0.5 ml of 0.9% NaCl solution; (b) PQ10: PQ 10 mg/kg; (c) PQ20: PQ 20 mg/kg; and (d) PQ30: PQ 30 mg/kg. Each group received a single injection of PQ. After 72 hours, the animals were subjected to an incremental aerobic running test until fatigue in order to determine exercise tolerance, blood glucose and lactate levels. After the next 24 h, lung, liver and skeletal muscle were collected for biometric, biochemical and morphological analyses. The animals exposed to PQ exhibited a significant anticipation of anaerobic metabolism during the incremental aerobic running test, a reduction in exercise tolerance and blood glucose levels as well as increased blood lactate levels during exercise compared to control animals. PQ exposure increased serum transaminase levels and reduced the glycogen contents in liver tissue and skeletal muscles. In the lung, the liver and the skeletal muscle, PQ exposure also increased the contents of malondialdehyde, protein carbonyl, 8-hydroxy-2'-deoxyguanosine, superoxide dismutase and catalase, as well as a structural remodelling compared to the control group. All these changes were dose-dependent. Reduced exercise tolerance after PQ exposure was potentially influenced by pathological remodelling of multiple organs, in which glycogen depletion in the liver and skeletal muscle and the imbalance of glucose metabolism coexist with the induction of lipid, protein and DNA oxidation, a destructive process not counteracted by the upregulation of endogenous antioxidant enzymes.

Paraquat Poisoning in Patients With HIV Infection: A Case Report and Literature Review

Paraquat poisoning is very severe. Most victims, including those who have ingested a small amount, will die from Paraquat poisoning. The cause of death in the majority of such cases is lung fibrosis. Paraquat poisoning in patients with positive human immunodeficiency virus (HIV) infection status has seldom been reported. Herein, we report a case of an HIV patient with Paraquat poisoning who had an excellent outcome even without standard treatment. Currently, only 3 such cases have been reported in the literature and in each case there was a good outcome, which was not expected according to predictive models. A possible mechanism may involve the relative lack of functional macrophages in HIV patients, which would tend to result in much less severe lung injury. None of the available predictive models of Paraquat poisoning appear to be appropriate for HIV patients.Paraquat poisoning in HIV patients may have better survival due to less lung injury.

Effects of high doses of dexamethasone on hemodynamic and immunohistochemical characteristics of acute paraquat intoxication in rat kidneys

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.

Abnormal pancreatic enzymes and their prognostic role after acute paraquat poisoning

Ingestion of paraquat causes multi-organ failure. Prognosis is best estimated through measurement of blood paraquat concentrations but this facility is not available in most hospitals. We studied the prognostic significance of abnormal pancreatic enzymes for survival. Patients with acute paraquat poisoning were recruited. An extensive series of blood tests including serum amylase were serially checked. Patients were sorted according to their serum amylase activity (normal [<220 U/L], mildly elevated [220 to 660 U/L], elevated [>660 U/L]), and survival compared between groups. 177 patients were enrolled to the study, of whom 67 died and 110 survived. 122 (70.62%), 27 (15.25%) and 25 (14.13%) patients were in the normal, mildly elevated and elevated amylase activity groups, respectively. The case fatality in the elevated group was 100% compared to 17% in the normal group (P < 0.001). We found four independent factors for paraquat death prediction: amylase, PaCO₂, leukocyte number, and neutrophil percentage. Models using pancreatic enzyme activity showed good prediction power. We have found that abnormal pancreatic enzymes are useful prognostic marker of death after acute paraquat poisoning. Including serum amylase activity into a prognostic model provides a good prognostication.

Metabolic changes in rat urine after acute paraquat poisoning and discriminated by support vector machine

Paraquat is quick-acting and non-selective, killing green plant tissue on contact; it is also toxic to human beings and animals. In this study, we developed a urine metabonomic method by gas chromatography-mass spectrometry to evaluate the effect of acute paraquat poisoning on rats. Pattern recognition analysis, including both partial least squares discriminate analysis and principal component analysis revealed that acute paraquat poisoning induced metabolic perturbations. Compared with the control group, the levels of benzeneacetic acid and hexadecanoic acid of the acute paraquat poisoning group (intragastric administration 36 mg/kg) increased, while the levels of butanedioic acid, pentanedioic acid, altronic acid decreased. Based on these urinary metabolomics data, support vector machine was applied to discriminate the metabolomic change of paraquat groups from the control group, which achieved 100% classification accuracy. In conclusion, metabonomic method combined with support vector machine can be used as a useful diagnostic tool in paraquat-poisoned rats.

Pneumomediastinum predicts early mortality in acute paraquat poisoning

CONTEXT

In paraquat (PQ) poisoning, death often occurs after the appearance of pneumomediastinum (PM). However, the clinical features and eventual outcome of PM in PQ intoxication remains unclear.

OBJECTIVE

We aimed to characterize PM following PQ poisoning and its prognostic value for predicting mortality.

MATERIALS AND METHODS

Enrolled PQ-poisoned patients (n = 75) were divided into two groups according to whether PM could be detected by chest computed tomography or not. The study outcomes included 5- and 90-day death after intoxication. Survival curves were derived using the Kaplan-Meier method, and mortality risk factors were analyzed by forward stepwise Cox regression analysis.

RESULTS

PM was documented in 21.3% of the patients (16/75); in 13 of them PM set in within 3 days of PQ ingestion. 15 patients died within 3 days of appearance of PM. Compared with patients without PM, those with PM were younger (P = 0.011), and had higher scores of Acute Physiology and Chronic Health Evaluation (P < 0.001) and Sequential Organ Failure Assessment (P = 0.003). In addition, patients with PM had a higher incidence of acute renal failure (P = 0.001), toxic hepatitis (P = 0.008), and respiratory insufficiency (P = 0.003). PM predicted an increased risk of 90-day death (93.8% of patients with PM vs. 40.7% among those without PM; hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.0-5.6; P = 0.045), and increased risk of 5-day death (81.3% vs. 27.1%; HR, 3.2; 95% CI, 1.2-8.1; P = 0.017).

DISCUSSION AND CONCLUSION

Early PM, occurring within 8 days, is a specific predictor of mortality in PQ poisoning.

Pulmonary Proteome and Protein Networks in Response to the Herbicide Paraquat in Rats

Paraquat (PQ) has been one of the most widely used herbicides in the world. PQ, when ingested, is toxic to humans and may cause acute respiratory distress syndrome. To investigate molecular perturbation in lung tissues caused by PQ, Sprague Dawley male rats were fed with PQ at a dose of 25 mg/kg body weight for 20 times in four weeks. The effects of PQ on cellular processes and biological pathways were investigated by analyzing proteome in the lung tissues in comparison with the control. Among the detected proteins, 321 and 254 proteins were over-represented and under-represented, respectively, in the PQ-exposed rat lung tissues in comparison with the no PQ control. All over- and under-represented proteins were subjected to Ingenuity Pathway Analysis to create 25 biological networks and 38 pathways of interacting protein clusters. Over-represented proteins were involved in the C-jun-amino-terminal kinase pathway, caveolae-mediated endocytosis signaling, cardiovascular-cancer-respiratory pathway, regulation of clathrin-mediated endocytosis, non-small cell lung cancer signaling, pulmonary hypertension, glutamate receptor, immune response and angiogenesis. Under-represented proteins occurred in the p53 signaling pathway, mitogen-activated protein kinase signaling pathway, cartilage development and angiogenesis inhibition in the PQ-treated lungs. The results suggest that PQ may generate reactive oxygen species, impair the MAPK/p53 signaling pathway, activate angiogenesis and depress apoptosis in the lungs.

Demographics, clinical characteristics and management of herbicide poisoning in tertiary care hospital

Herbicide poisoning is most common method of suicide in India and it is associated with high morbidity and mortality. Among different herbicidal poisonings the most predominantly found poisonings are paraquat and glyphosate. These compounds are highly toxic and their poisonings require proper management techniques. High fatality is seen in these cases which are mainly due to its inherent toxicity and lack of effective treatment. Common symptoms of these poisonings includes gastrointestinal corrosive effects with mouth and throat, epigastric pain and dysphagia, acid-base imbalance, pulmonary edema, shock and arrhythmia. Long term health effects include pulmonary fibrosis, renal failure, hepatic failure, heart failure, multi-organ failure or death. No proven antidote exists for these poisonings. So the treatment is mainly supportive. Initially gastric lavage or whole-gut irrigation using adsorbents such as Fuller's earth, bentonite or activated charcoal is recommended. In case of renal failure hemodialysis or hemoperfusion may be considered. However novel approaches like treatment with N-acetylcysteine, vitamin C, vitamin E, cyclophosphamide may also be helpful.

Elimination of young erythrocytes from blood circulation and altered erythropoietic patterns during paraquat induced anemic phase in mice

Paraquat a widely used herbicide causes a variety of toxic effects on humans and animals. The present study is focused on the interaction of paraquat with the mouse erythroid system. Administration of paraquat (10 mg/kg body weight i.p. on alternate days in C57Bl/6 mice) induced a significant fall in blood erythrocyte count on 7, 14, and 21 day time points but the erythrocyte count reverted back to normal by 28th day indicating the emergence of refractoriness to paraquat. A marked surge in the blood reticulocyte count was observed in paraquat treated mice that also subsided by 28th day. Young erythrocytes in circulation were randomly eliminated from blood circulation in paraquat treated mice and a significant elevation in the level of reactive oxygen species (ROS) was also observed maximally the erythrocytes of this age group. Cells representing various stages of erythroid differentiation in bone marrow and spleen were identified and enumerated flow cytometrically based on their expression of Ter119 and transferrin (CD71) receptor. Proliferative activity of erythroid cells, their relative proportion as well as their absolute numbers fell significantly in bone marrow of paraquat treated mice but all these parameters were significantly elevated in spleens of paraquat treated mice. These changes were essentially restricted to the cells belonging to the two earliest stages of erythroid differentiation. Taken together our results indicate that paraquat treatment causes a transient anemia in mice resulting from random elimination of young circulating erythrocytes as well as depressed erythropoietic activity in bone marrow. Spleen erythropoietic activity however was elevated in paraquat treated mice.

Paraquat poisoning: A case report and review of literature

Paraquat (1, r-dimethyl-4,4’-bipyridium dichloride), a brown syrupy liquid is an effective herbicide that has low chronic toxicity because of its rapid deactivation on contact with soil. A high dose of paraquat or severe poisoning has a poor prognosis. At present there is no specific antidote to paraquat poisoning, hence the need to focus on prevention and in case of exposure or ingestion, aggressive decontamination to prevent further absorption. Although uncommon, paraquat ingestion can lead to severe and often fatal toxicity. However, despite its widespread availability, reports of this herbicide poisoning in India are uncommon.

Paraquat poisonings in France during the European ban: experience of the Poison Control Center in Marseille

Paraquat, a widely used herbicide in the world, has caused severe and fatal poisonings. Because of its high toxicity, the European Union withdrew paraquat from its market in July 2007. The purpose of this report is to describe cases of paraquat poisoning recorded at the Poison Control Center in Marseille over the 9-year period starting and ending 4.5 years before and after the paraquat ban. Data analysis showed that the most severe exposures were linked to ingestion. The fatality rate of deliberate consumption was near 50 % (34 suicide attempts and 15 deaths). Our data showed a marginal decline in total number of poisonings observed after the paraquat ban (38 vs 33 after the ban) mostly due to a decrease in the number of unintentional exposure (21 vs 16 after the ban). However, there was no apparent change in the number suicidal attempts using paraquat. Regarding geographical distribution, data showed that most poisonings in mainland France were unintentional, while poisonings in overseas French territories were mostly voluntary. Despite the European ban and the preventive measures, paraquat continues to contribute to severe and life-threatening poisonings in Southeastern and overseas France.

Diphenyl diselenide prevents hepatic alterations induced by paraquat in rats

This study aimed to investigate the beneficial effect of diphenyl diselenide (PhSe)₂ on paraquat (PQ) induced alterations in rats liver. Adult male Wistar rats received (PhSe)₂ at 10 mg kg(-1), by oral administration (p.o.), during five consecutive days. Twenty-four hours after the last (PhSe)₂ dose, rats received PQ at 15 mg kg(-1), in a single intraperitoneally injection (i.p.). Seventy-two hours after PQ exposure, animals were sacrificed by decapitation for blood and liver samples obtainment. Histological alterations induced by PQ exposure, such as inflammatory cells infiltration and edema, were prevented by (PhSe)₂ administration. Moreover, (PhSe)₂ prevented hepatic lipid peroxidation (LPO) induced by PQ and was effective in reducing the myeloperoxidase (MPO) activity in liver, which was enhanced by PQ exposure. (PhSe)₂ also was effective in protecting against the reduction in ascorbic acid and non-protein thiols (NPSH) levels induced by PQ. The inhibition of glutathione S-transferase (GST) activity, in rats exposed to PQ, was normalized by (PhSe)₂ pre-treatment, whereas the inhibition of catalase (CAT) activity was not prevented by (PhSe)₂. The serum alkaline phosphatase (ALP) inhibition, induced by PQ administration, was also prevented by (PhSe)₂ pre-treatment. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were not modified by PQ and/or (PhSe)₂ administration. Therefore, (PhSe)₂ pre-treatment was effective in protecting against the hepatic alterations induced by PQ in rats. This protective effect can involve the antioxidant and anti-inflammatory properties of (PhSe)₂.

A survey of the protective effects of some commercially available antioxidant supplements in genetically and chemically induced models of oxidative stress in Drosophila melanogaster

Oxidative stress remains one of the most well studied, albeit somewhat contentious, causes of age-related changes in humans. Consequently, a large number of putative antioxidant compounds are freely available in myriad formulations that are often not tested for their efficacy or regulated for quality control. Following the development of a Drosophila model of oxidative-stress dependent aging (p38 MAP K (p38K) mutants) in our laboratory, we attempted to test the protective effect of some of these commonly available formulations against oxidative stress, in the p38K model. As environmental exposure to oxidizing toxins has been linked to a variety of human diseases, we also tested the efficacy of these supplements on chemically-induced models of oxidative stress (paraquat and hydrogen peroxide exposure). Our results suggest that when added as a dietary supplement, some of these over-the-counter compounds, notably containing açai extracts, confer significant protection for both the p38K-dependent genetic model as well as the toxin-induced model. These products were also remarkably effective at dampening stress-induced expression of the detoxifying enzyme GSTD1 and eliminating paraquat induced circadian rhythm deficits. Overall, our results suggest potential benefits of dietary supplementation with some of these compounds, especially under conditions of elevated oxidative stress. These findings should be assessed in the context of other studies that seek to identify active principles in these extracts, determine their effective dosage for human consumption and evaluate the safety of long-term prophylactic applications.

Role of thioredoxin in lung disease

Thioredoxin system is a ubiquitous thiol oxidoreductase system that regulates cellular reduction/oxidation (redox) status. It includes thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH. Trx plays an essential role in cell function by limiting oxidative stress directly via antioxidant effects and indirectly by proteins interaction with key signal transduction molecules. A variety of signaling molecules have been implicated in the cytoprotection conferred by Trx, such as autophagic proteins, p38 mitogen-activated protein kinase, nuclear factor-κB, phosphatidylinositol 3-kinase. Recent studies indicated that Trx may contribute to the pathogenesis of COPD, asthma and lung injury. Enhanced Trx expression or application of recombinant Trx afforded protection in preclinical models of pulmonary tissue injury, which suggested Trx may be used in future therapeutic applications. The focus of this review is on the significance of Trx in various pulmonary diseases, which as a potential therapeutic strategy to protect against oxidative stress and inflammation.

Effect of Bark Extract of Bathysa cuspidata on Hepatic Oxidative Damage and Blood Glucose Kinetics in Rats Exposed to Paraquat

This study investigated the effect of bark extract of Bathysa cuspidata on hepatic oxidative damage and blood glucose kinetics in rats exposed to paraquat. Wistar rats were exposed to a single dose of paraquat (30 mg/kg, i.p.) and treated with an ethanolic extract of Bathysa cuspidata (200 and 400 mg/kg). Analyses were conducted of liver edema, blood glucose, serum transaminases, alkaline phosphatase, collagen, malondialdehyde, catalase, superoxide dismutase, and histomorphometry. In the animals intoxicated with paraquat and treated with 400 mg/kg of extract, edema, hypertrophy of the nucleus of hepatocytes, serum transaminases, alkaline phosphatase, and malondialdehyde levels decreased significantly ( p < .05). Catalase and superoxide dismutase activity, the number of hepatocytes per unit volume, and the glycogen proportion were maintained. The increase followed by progressive reduction of blood glucose observed in paraquat-exposed groups was significantly attenuated in the group treated with 400 mg/kg of extract ( p < .05). Phytochemical analysis of the extract revealed the presence of flavonoids, proanthocyanidins, and phenolic compounds. The bark extract of Bathysa cuspidata was able to inhibit large variations in blood glucose and reduce hepatic damage in rats exposed to paraquat. This finding suggests a contribution of the extract in reducing lipid peroxidation and the morphofunctional damage to the liver parenchyma.