Associations between laboratory parameters and outcome of paraquat poisoning

Roles of oxidative stress/JNK/ERK signals in paraquat-triggered hepatic apoptosis

Paraquat (PQ), a toxic and nonselective bipyridyl herbicide, is one of the most extensively used pesticides in agricultural countries. In addition to pneumotoxicity, the liver is an important target organ for PQ poisoning in humans. However, the mechanism of PQ in hepatotoxicity remains unclear. In this study, we found that exposure of rat hepatic H4IIE cells to PQ (0.1-2 mM) induced significant cytotoxicity and apoptosis, which was accompanied by mitochondria-dependent apoptotic signals, including loss of mitochondrial membrane potential (MMP), cytosolic cytochrome c release, and changes in the Bcl-2/Bax mRNA ratio. Moreover, PQ (0.5 mM) exposure markedly induced JNK and ERK1/2 activation, but not p38-MAPK. Blockade of JNK and ERK1/2 signaling by pretreatment with the specific pharmacological inhibitors SP600125 and PD98059, respectively, effectively prevented PQ-induced cytotoxicity, mitochondrial dysfunction, and apoptotic events. Additionally, PQ exposure stimulated significant oxidative stress-related signals, including reactive oxygen species (ROS) generation and intracellular glutathione (GSH) depletion, which could be reversed by the antioxidant N-Acetylcysteine (NAC). Buffering the oxidative stress response with NAC also effectively abrogated PQ-induced hepatotoxicity, MMP loss, apoptosis, and phosphorylation of JNK and ERK1/2 protein, however, the JNK or ERK inhibitors did not suppress ROS generation in PQ-treated cells. Collectively, these results demonstrate that PQ exposure induces hepatic cell toxicity and death via an oxidative stress-dependent JNK/ERK activation-mediated downstream mitochondria-regulated apoptotic pathway.

The acute paraquat poisoning mortality (APPM) score to predict the risk of death in paraquat-poisoned patients

CONTEXT

Mortality prediction in paraquat poisoning is a major issue since most prediction rules are inapplicable if the exact ingestion time cannot be determined and/or the serum paraquat concentration is not readily available, as in most countries. Therefore, we aimed to develop and validate a new prediction rule not requiring these two parameters.

METHODS

We designed a 10-year observational cohort study including all consecutive paraquat-poisoned patients managed in two Taiwanese hospitals. We built one cohort to define and one cohort to validate this prediction rule. Parameters independently related to mortality determined using a multivariate analysis were used to formulate the Acute Paraquat Poisoning Mortality (APPM) score.

RESULTS

Overall, 321 paraquat-poisoned patients were included, 156 in the derivation and 165 in the validation cohort. Mortality rates in the derivation and validation cohorts were 73% and 81%, respectively (p = 0.20). The three parameters chosen of 28-day mortality at presentation were urine paraquat level >10 ppm (using a colorimetric sodium dithionite-based test; odds ratio (OR), 12.70; 95% confidence interval (CI), 2.64-61.24), white blood cells >13.0 G/L (OR, 5.50; CI, 1.41-21.48) and blood glucose >140 mg/dL [7.8 mmol/L] (OR, 7.45; CI, 1.70-32.86). In the derivation cohort, the area under the ROC curve (AUC-ROC) of the APPM score did not significantly differ from AUC-ROCs of serum paraquat (0.95, p = 0.25) and the Severity Index of Paraquat Poisoning (0.95, p = 0.33). AUC-ROCs of the APPM score in the derivation and validation cohorts were 0.91 and 0.94, respectively.

CONCLUSION

We built and validated a reliable score to predict 28-day mortality in paraquat-poisoned patients at presentation, independently from the ingestion time and serum paraquat measurement.

Development and Validation of a Radiomics Nomogram for Prognosis Prediction of Patients with Acute Paraquat Poisoning: A Retrospective Cohort Study

Objective

To evaluate the efficiency of a radiomics model in predicting the prognosis of patients with acute paraquat poisoning (APP).

Materials and Methods

Chest computed tomography images and clinical data of 80 patients with APP were obtained from November 2014 to October 2017, which were randomly assigned to a primary group and a validation group by a ratio of 7 : 3, and then the radiomics features were extracted from the whole lung. Principal component analysis (PCA) and least absolute shrinkage and selection operator (LASSO) regression were used to select the features and establish the radiomics signature (Rad-score). Multivariate logistic regression analysis was used to establish a radiomics prediction model incorporating the Rad-score and clinical risk factors; the model was represented by nomogram. The performance of the nomogram was confirmed by its discrimination and calibration.

Result

The area under the ROC curve of operation was 0.942 and 0.865, respectively, in the primary and validation datasets. The sensitivity and specificity were 0.864 and 0.914 and 0.778 and 0.929, and the prediction accuracy rates were 89.5% and 87%, respectively. Predictors included in the individualized predictive nomograms include the Rad-score, blood paraquat concentration, creatine kinase, and serum creatinine. The AUC of the nomogram was 0.973 and 0.944 in the primary and validation datasets, and the sensitivity and specificity were 0.943 and 0.955, respectively, in the primary dataset and 0.889 and 0.929 in the validation dataset, and the prediction accuracy was 94.7% and 91.3%, respectively.

Conclusion

The radiomics nomogram incorporates the radiomics signature and hematological laboratory data, which can be conveniently used to facilitate the individualized prediction of the prognosis of APP patients.

Fetal outcomes after intentional ingestion of paraquat: A case report

RATIONALE

Despite the fact that treatment of paraquat poisoning in pregnant women and their fetuses is challenging and raises ethical issues, it is rarely reported in the literature. We report the case of a pregnant woman who took paraquat intentionally.

PATIENT CONCERNS

A 36-year-old woman at 38 weeks gestational age, in an apparent suicide attempt, drank 1 mouthful (about 20 ml) of paraquat solution. Ten hours later, her urine dithionate test showed light blue color with a plasma paraquat concentration of 0.547 μg/ml. Six hours after admission, a male infant, whose plasma paraquat concentration was 0.761 μg/ml, together with 0.673 μg/ml in the amniotic fluid measured by high-performance liquid chromatography, was delivered but the woman's lung, liver, and kidney function declined rapidly.

DIAGNOSIS

INTERVENTIONS:: Because of placenta previa and multiple organ failure, emergency cesarean section, and panhysterectomy were performed for the pregnant woman. Intravenous injection of antibiotic to prevent infection and dexamethasone 30 mg once a day were administered. Mechanical ventilation was performed for the infant and meropenem and penicillin injection was administered.

OUTCOMES

The infant died 33 hours after birth while the mother died on the 3rd day after ingestion.

LESSONS

Paraquat can enter the fetus through the placenta and the amniotic fluid via fluid exchange. The pathological changes of fetal organs may relate to gestational age, and the prognosis was very poor in both the mother and the fetus.

Clinical features and risk factors of acute kidney injury in children with acute paraquat intoxication

Objective

This study aimed to investigate the clinical features and risk factors of acute kidney injury (AKI) in children with acute paraquat intoxication.

Methods

A retrospective study of 110 hospitalized children with acute paraquat intoxication in West China Second University Hospital, Sichuan University was conducted from January 2010 to May 2017. The Kaplan–Meier method was used to compare the survival rates of children with different AKI stages. Multivariate logistic regression was applied to analyse the risk factors for paraquat-induced AKI.

Results

AKI occurred in 42 of 110 (38.2%) children. We observed AKI stage 1 in two (4.8%) children, AKI stage 2 in 11 (26.2%), and AKI stage 3 in 29 (69.0%). The survival rate of children in AKI stage 3 (34.5%) was significantly lower than that in children in AKI stage 2 (63.6%) and AKI stage 1 (100%). Multivariate analysis showed that oral ulcers and elevated blood glucose levels were significant independent risk factors for paraquat-induced AKI in children (odds ratio = 4.223 and 5.545, respectively).

Conclusions

The incidence and mortality rates of paraquat-induced AKI in children are high. Oral ulcers and elevated blood glucose levels are independent risk factors affecting the occurrence of paraquat-induced AKI in children.

Monocytes as an Early Predictor for Patients with Acute Paraquat Poisoning: A Retrospective Analysis

BACKGROUND

The predictive values of monocytes in the prognosis of patients with acute paraquat (PQ) poisoning are unclear. This retrospective study investigated the predictive values of monocytes in the prognosis of patients with acute PQ poisoning.

METHODS

Adult patients who suffered from acute PQ poisoning in the emergency care unit of Cangzhou Central Hospital from May 2012 to December 2018 were enrolled. The patients were divided into groups, namely, survival and nonsurvival, according to a 90-day prognosis. Moreover, correlation, logistic regression, receiver-operator characteristic (ROC), and Kaplan-Meier curve analyses were applied to evaluate the monocyte values used to predict the prognosis of patients with acute PQ poisoning.

RESULT

Among the 109 patients, 45 survived within 90 days after the poisoning, resulting in a 41.28% survival rate. The monocyte count of the nonsurvivors was significantly higher than that of the survivors (P< 0.001). Correlation analysis showed that monocyte count positively correlated with plasma PQ concentration (r= 0.413; P< 0.001) and negatively correlated with survival time (r= 0.512; P< 0.001) and 90-day survival (r= 0.503; P< 0.001). Logistic regression analysis showed that elevated monocytes were the independent risk factors for the 90-day survival. The area under the ROC curve of the monocyte count used to predict the 90-day survival was 0.826 (95% CI: 0.751-0.904), the optimal cut-off was 0.51×109/L, sensitivity was 73.4%, and specificity was 86.7%.

CONCLUSION

This study demonstrated that elevated monocyte count is a useful early predictor of 90-day survival in patients with acute PQ poisoning. However, further studies are warranted to draw firm conclusions.

Sequential organ failure assessment in predicting mortality after paraquat poisoning: A meta-analysis

Sequential organ failure assessment (SOFA) score is commonly used to determine disease severity and predict prognosis in critically ill patients. However, the prognostic value of SOFA after acute paraquat (PQ) poisoning remains unclear. This meta-analysis aimed to study the capability of SOFA to predict mortality in patients with PQ poisoning. Databases that included PubMed, Embase, Web of Science, ScienceDirect, Embase, and Cochrane Library were searched through May 2018. Six studies involving 946 patients were included in the meta-analysis. Study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, and then ORs with 95% CIs were pooled for the estimation of the prognostic role of SOFA in patients with PQ poisoning. Results showed that higher SOFA in patients with PQ poisoning was related to severe mortality (OR = 8.14, 95%CI 4.26–15.58, p<0.001). The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic OR, and area under the curve were 72% (95%CI 0.65–0.79), 75% (95%CI 0.65–0.83), 2.9 (95%CI 2.0–4.1), 0.37 (95%CI 0.28–0.41), 8 (95%CI 4–14), and 0.79 (95%CI 0.76–0.83), respectively. No evidence of publication bias was detected by funnel plot analysis and formal statistical tests. Sensitivity analyses showed no important differences in the estimates of effects. The high SOFA score (8.1-fold) was associated with severe mortality in patients with PQ poisoning.

Clinical features and prognosis of paraquat poisoning in French Guiana: A review of 62 cases

Paraquat is a nonselective contact herbicide of great toxicological importance, being associated with high mortality rates. Because of its high toxicity, the European Union withdrew it from its market in 2007. The aim of this study is to analyze all cases of paraquat poisoning hospitalized in French Guiana in order to assess their incidence and main characteristics.Medical records of all paraquat intoxicated patients hospitalized from 2008 until 2015 were reviewed in this retrospective study.Demographics, clinical presentation, and laboratory data were evaluated.A total of 62 cases were reviewed. The incidence of paraquat poisoning was 3.8/100,000 inhabitants/year. There were 44 adults and 18 children younger than 16 years of age. The median ages were 31 years [18.08-75.25] in adults and 13.4 years [0.75-15.08] in children, respectively. The median duration of hospitalization was longer in children [15.5 days (1-24)] than in adults [2 days (1-30)], P < .01. The majority of cases was due to self-poisoning (84%).Children had ingested a lower quantity of paraquat [48.8 mg/kg (10-571.1)] than adults [595.8 mg/kg (6-3636.4), P = .03]. There were more deaths among adults (65%) than in children (22%), P = .004. The severity and outcome was determined primarily by the amount of paraquat ingested.In conclusion, French Guiana has the largest cohort of paraquat poisonings in the European Union. The major factor affecting the prognosis of patients was the ingested amount of paraquat. The administration of activated charcoal or Pemba, in situ, within the first hour after ingestion of paraquat is essential.

Point-of-care testing in the early diagnosis of acute pesticide intoxication: The example of paraquat

Acute pesticide intoxication is a common method of suicide globally. This article reviews current diagnostic methods and makes suggestions for future development. In the case of paraquat intoxication, it is characterized by multi-organ failure, causing substantial mortality and morbidity. Early diagnosis may save the life of a paraquat intoxication patient. Conventional paraquat intoxication diagnostic methods, such as symptom review and urine sodium dithionite assay, are time-consuming and impractical in resource-scarce areas where most intoxication cases occur. Several experimental and clinical studies have shown the potential of portable Surface Enhanced Raman Scattering (SERS), paper-based devices, and machine learning for paraquat intoxication diagnosis. Portable SERS and new SERS substrates maintain the sensitivity of SERS while being less costly and more convenient than conventional SERS. Paper-based devices provide the advantages of price and portability. Machine learning algorithms can be implemented as a mobile phone application and facilitate diagnosis in resource-limited areas. Although these methods have not yet met all features of an ideal diagnostic method, the combination and development of these methods offer much promise.

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.

Health effect of agricultural pesticide use in China: implications for the development of GM crops

It is notable that the adoption of GM glyphosate-tolerant crops increases glyphosate use but reduces non-glyphosate herbicide use; and adoption of GM insect-resistant crops significantly reduces insecticide use. While the health hazard of pesticide use has been well documented, little literature evaluates the health effects of different pesticides related to GM crops in an integrated framework. This study aims to associate the uses of different pesticides related to GM crops with the blood chemistry panel and peripheral nerve conduction of Chinese farmers. Pesticides used by farmers were recorded and classified as glyphosate, non-glyphosate herbicides, chemical lepidopteran insecticides, biological lepidopteran insecticides, non-lepidopteran insecticides and fungicides. The multivariate regression results show that none of the examined 35 health indicators was associated with glyphosate use, while the use of non-glyphosate herbicides was likely to induce renal dysfunction and decrease of serum folic acid. The use of chemical lepidopteran insecticides might be associated with hepatic dysfunction, serum glucose elevation, inflammation and even severe nerve damage. In this context, if GM crops are adopted, the alterations in pesticide use may benefit farmer health in China and globe, which has positive implications for the development of GM crops.

Hyperamylasemia as an Early Predictor of Mortality in Patients with Acute Paraquat Poisoning

Background

Paraquat (PQ) is a non-selective and fast-acting contact herbicide which has been widely used in developing countries. Hyperamylasemia was reported in patients with PQ poisoning. This study investigated the predictive value and clinical characteristics of hyperamylasemia in patients with PQ poisoning.

Material/Methods

This study included 87 patients with acute PQ poisoning admitted from July 2012 to May 2015. Data were collected from medical records. Receiver operating characteristic (ROC) analysis was conducted to analyze the discriminatory potential of serum amylase with respect to 90-day mortality.

Results

Of 87 patients, 29 patients had elevated serum amylase. We found that serum amylase was significantly higher among patients with AKI than those with non-AKI (p<0.001), and was an independent predictor of mortality (hazard ratio [HR]=3.644; 95% [CI], 1.684–7.881; p=0.001). The area under the ROC curve for the serum amylase (area under curve [AUC]=0.796; 95% [CI], 0.690–0.903) had a better discriminatory potential than plasma PQ concentration (0.698;0.570–0.825) or urinary PQ concentration (0.647;0.514–0.781) in predicting 90-day mortality.

Conclusions

Hyperamylasemia is a valuable early predictor of 90-day mortality in PQ poisoning.

Predicting the probability of survival in acute paraquat poisoning

BACKGROUND

Paraquat (PQ) concentration-time data have been used to predict prognosis for 3 decades. The aim of this study was to find a more accurate method to predict the probability of survival.

METHODS

This study included 788 patients with PQ poisoning who were diagnosed using plasma PQ concentration between January 2005 and August 2012. We divided these patients into 2 groups (survivors vs. nonsurvivors), compared their clinical characteristics, and analyzed the predictors of survival.

RESULTS

The mean age of the included patients was 57 years (range, 14-95 years). When we compared clinical characteristics between survivors (n = 149, 19%) and nonsurvivors (n = 639, 81%), survivors were younger (47 ± 14 years vs. 59 ± 16 years) and had lower plasma PQ concentrations (1.44 ± 8.77 μg/mL vs. 80.33 ± 123.15 μg/mL) than nonsurvivors. On admission, serum creatinine was lower in survivors than in nonsurvivors (0.95 ± 0.91 mg/dL vs. 1.88 ± 1.27 mg/dL). In multivariate logistic regression analysis, age and logarithmically converted serum creatinine [ln(Cr)], [ln(time)], and [ln(PQ)] were assessed as prognostic factors to predict survival in PQ poisoning. The predicted probability of survival using significant prognostic factors was exp (logit)/[1 + exp(logit)], where logit = -1.347 + [0.212 × sex (male = 1, female = 0)] + (0.032 × age) + [1.551 × ln(Cr)] + [0.391 × ln(hours since ingestion)] + [1.076 × ln(plasma PQ μg/mL)]. With this equation, the sensitivity and specificity were 86.5% and 98.7%, respectively.

CONCLUSION

Age, ln(Cr), ln(time), and ln(PQ) were important prognostic factors in PQ poisoning, and our equation can be helpful to predict the survival in acute PQ poisoning patients.

The significance of serum uric acid level in humans with acute paraquat poisoning

Hyperuricemia is a strong and independent predictor of all-cause mortality in cardiovascular disease and has been found to play a role in diseases exacerbated by oxidative stress and inflammation. This study aimed to evaluate whether serum uric acid (UA) level is an indicator of outcome in patients with acute paraquat poisoning. A total of 205 subjects who had attempted suicide by oral ingestion of paraquat were admitted to the emergency room between January 2009 and June 2014. Initial serum UA level and other laboratory parameters were measured. A total of 66 patients died during the 30 days after admission, corresponding to a 32.2% cumulative incidence of mortality. UA levels were higher in non-survivors than survivors (P < 0.001) and 30-day mortality increased with increasing baseline serum UA level (P < 0.001). In a prediction analysis for 30-day mortality, the serum UA level had a cut-off concentration of 284 µmol/L in female patients and 352 µmol/L in male patients. Multivariate Cox proportional hazards regression analyses showed that white blood cell counts and UA were independent prognostic factors. In conclusion, we showed that serum UA may be an independent predictor of 30-day mortality in patients with paraquat poisoning.

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.

Prospective experimental studies on the renal protective effect of ulinastatin after paraquat poisoning

BACKGROUND

Paraquat (PQ) is an effective herbicide and is widely used in agricultural production, but PQ poisoning is frequently seen in humans with the lung as the target organ. Currently, there are many studies on lung injury after PQ poisoning. But the kidney as the main excretory organ after PQ poisoning is rarely studied and the mechanisms of this poisoning is not very clear. In this study, we observed the expression of caspase-3 and livin protein in rat renal tissue after PQ poisoning as well as the therapeutic effects of ulinastatin.

METHODS

Fifty-four Sprague-Dawley (SD) rats were randomly divided into three experimental groups: control group (group A), paraquat poisoning group (group B) and ulinastatin group (group C), with 18 rats in each group. Rats in group B and group C were administered intragastrically with 80 mg/kg PQ, rats in group C were injected peritoneally with 100 000 U/kg ulinastatin once a day, while rats in group A were administered intragastrically with the same volume of saline as PQ. At 24, 48, 72 hours after poisoning, the expression of livin in renal tissue was detected by Westen blotting, the expression of caspase-3 was detected by immunohistochemistry, and the rate of renal cell apoptosis was tested by TUNEL detection. The histopathological changes were observed at the same time.

RESULTS

Compared to group A, the expression of caspase-3 in the renal tissue of rats in groups B and C increased significantly at any time point. Compared with group B, the expression of caspase-3 in renal tissue of rats in group C decreased. Compared with group A, the expression of livin in renal tissue in rats of groups B and C increased significantly at any time point (P<0.01), especially in group C (P<0.01). TUNEL method showed that the rate of renal cell apoptosis index was higher in group B at corresponding time points than in group A (P<0.01), and was lower in group C at corresponding time points than in group B (P<0.01).

CONCLUSION

UTI has a protective effect on the renal tissue of rats after paraquat poisoning through up-regulating the expression of livin and down-regulating the expression of caspase-3, but the regulation path still needs a further research.

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 28^th 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 28^th 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.

Hemolytic uremic syndrome associated with paraquat intoxication

We report a case of a 66-year-old patient with paraquat intoxication resulting in the requirement for hemoperfusion, hemodialysis, and plasma exchange. His initial serum paraquat level was 0.24 µg/mL (0.0-0.1 µg/mL). Activated charcoal (50 g) was administered orally, and high-dose N-acetylcysteine (150 mg/kg) was administered intravenously. In addition, immediate 4 h hemoperfusion was also performed for three consecutive days after admission. Hemodialysis was started on the 4th day after admission because of uremia. On the 9th day after admission, laboratory findings demonstrated hemolytic uremic syndrome (HUS): microangiopathic hemolytic anemia (MAHA), thrombocytopenia, elevated reticulocyte count, and lactate dehydrogenase (LDH). Plasma exchange was performed three times consecutively. Anemia and thrombocytopenia were improved, and LDH was normalized after plasma exchange. Urine output increased to 2240 mL/day on the 18th day after admission, and hemodialysis was discontinued. He is currently being observed at our follow-up clinic without renal impairment or pulmonary dysfunction for 1.5 years since discharge. We should suspect paraquat-associated HUS when thrombocytopenia and anemia are maintained for a long time after paraquat intoxication.

Paraquat poisoning induces TNF-α-dependent iNOS/NO mediated hyporesponsiveness of the aorta to vasoconstrictors in rats

Paraquat is a toxic herbicide that may induce acute lung injury, circulatory failure and death. The present work aimed at investigating whether there is systemic inflammation and vascular dysfunction after paraquat exposure and whether these parameters were related. There was neutrophilia and accumulation of neutrophils in lung and bronchoalveolar lavage of animals given paraquat. This was associated with an increase in serum levels of TNF-α. In rats given paraquat, the relaxant response of aortic rings to acetylcholine was not modified but the contractile response to phenylephrine was greatly reduced. Endothelium removal or treatment with non-selective (L-NAME) or selective (L-NIL) inhibitors of inducible nitric oxide synthase (iNOS) restored contraction of aortas. There was greater production of nitric oxide (NO), which was restored to basal level by L-NIL, and greater expression of iNOS in endothelial cells, as seen by Western blot analyses and confocal microscopy. Blockade of TNF-α reduced pulmonary and systemic inflammation and vascular dysfunction. Together, our results clearly show that paraquat causes pulmonary and systemic inflammation, and vascular dysfunction in rats. Vascular dysfunction is TNF-α dependent, associated with enhanced expression of iNOS in aortic endothelial cells and greater NO production, which accounts for the decreased responsiveness of aortas to vasoconstrictors. Blockers of TNF-α may be useful in patients with paraquat poisoning.

Relationship between hepatic dysfunction and prognosis in patients with paraquat poisoning: Clinical effects of hemopurification therapy

AIM: To investigate the relationship between hepatic dysfunction and prognosis in patients with paraquat poisoning, and to assess the clinical effects of hemopurification therapy [hemoperfusion (HP), continuous venovenous hemodiafiltration (CVVHDF), plasma exchange (PE)] in these patients.

METHODS: The clinical data for 55 patients with paraquat poisoning who were treated at EICU in our hospital from January 2009 to October 2012 were analyzed retrospectively. The patients were divided into two groups, death group and survival group. ALT, AST, TBIL and DBIL were measured on the 1st, 4th, 7th and 14th day after poisoning. The patients were then divided into two groups according to the use of CVVHDF therapy or not to evaluate the effect of this treatment on hepatic function.

RESULTS: At each time point, the levels of all the hepatic function parameters in the death group were significantly higher than those in the survival group (all P < 0.05). HP was performed in all patients. Two patients who received PE treatment were dead. The mortality in the CVVHDF group was significantly higher than that in the non-CVVHDF group (P < 0.01), and there was no significant difference for all liver function parameters at each time point between the CVVHDF group and non-CVVHDF group.

CONCLUSION: Paraquat poisoning can cause hepatic dysfunction. The changes in liver function parameters, especially high bilirubin, might be reliable predictors of prognosis. Hemopurification therapy, especially CVVHDF, is useless in patients with paraquat poisoning in terms of improving liver function and decreasing mortality.

Biochemical and molecular mechanisms of N-acetyl cysteine and silymarin-mediated protection against maneb- and paraquat-induced hepatotoxicity in rats

Oxidative stress is one of the major players in the pathogenesis of maneb (MB) and paraquat (PQ)-induced disorders. N-acetyl cysteine (NAC), a glutathione (GSH) precursor and silymarin (SIL), a naturally occurring antioxidant, encounter oxidative stress-mediated cellular damage. The present study was aimed to investigate the effects of NAC and SIL against MB and/or PQ-induced hepatotoxicity in rats. The levels of hepatotoxicity markers - alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and total bilirubin, histological changes, oxidative stress indices, phase I and phase II xenobiotic metabolizing enzymes - cytochrome P450 (CYP) and glutathione S-transferase (GST) and pro-inflammatory molecules - inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured in animals treated with MB and/or PQ in the presence or absence of NAC and SIL. MB and/or PQ augmented ALT, AST, total bilirubin, lipid peroxidation and nitrite contents and catalytic activities of superoxide dismutase and glutathione peroxidase however, the GSH content was attenuated. NAC and SIL restored the above-mentioned alterations towards basal levels but the restorations were more pronounced in SIL treated groups. Similarly, MB and/or PQ-mediated histopathological symptoms and changes in the catalytic activities/expressions of CYP1A2, CYP2E1, iNOS, TNF-α, and IL-1β were alleviated by NAC and SIL. Conversely, MB and/or PQ-induced GSTA4-4 expression/activity was further increased by NAC/SIL and glutathione reductase activity was also increased. The results obtained thus suggest that NAC and SIL protect MB and/or PQ-induced hepatotoxicity by reducing oxidative stress, inflammation and by modulating xenobitic metabolizing machinery and SIL seems to be more effective.

Paraquat detoxification with p-sulfonatocalix-[4]arene by a pharmacokinetic study

The p-sulfonatocalix[n]arenes are supposed to show potential application in the clinical treatment of viologen poisoning. In the present study, p-sulfonatocalix[4]arene (C4AS), the most common derivative of p-sulfonatocalix[n]arenes, is used to study the antidotic mechanism for paraquat (PQ) by pharmacokinetics in vivo. A high-performance liquid chromatography (HPLC) method was established to determine the concentration of PQ in rat plasma. The results showed that the peak plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC(0-t)) were significantly lower after C4AS intervention than in the PQ intoxication group. It was considered that C4AS has great effective detoxication to PQ poisoning, and the results of in vitro intestinal absorption studies showed that C4AS can inhibit the absorption of PQ via oral administration by forming a stable inclusion constant.

The efficacy of high doses of vitamin C in patients with paraquat poisoning

Paraquat (PQ) poisoning is an extremely difficult condition to manage clinically because of the lack of effective treatments. The purpose of this study was to assess the effect of high doses of vitamin C in combination with anti-inflammatory and immunosuppressant therapy in patients with PQ poisoning. The medical records of 134 patients who presented to the emergency department within 24 hours after PQ poisoning were reviewed retrospectively. The 57 patients presented between January 2004 and September 2005 were group 1; they received pulse therapy, which included cyclophosphamide and methylprednisolone, followed by the administration of dexamethasone over 2 weeks. The 77 patients that presented between October 2005 and January 2008 were group 2; they received the above-mentioned therapy and high-dose vitamin C for 2 weeks. There was no difference in the distribution of baseline variables between the 2 groups. However, group 2 showed a significant reduction in acute kidney injury related to PQ. Furthermore, a multivariate logistic regression analysis showed that the addition of vitamin C to the treatment was significantly associated with an increased survival of the patients. Larger trials will be needed to verify the effect of high-dose vitamin C on survival in patients with PQ poisoning.

Rapid analysis of plasma paraquat using sodium dithionite as a predictor of outcome in acute paraquat poisoning

BACKGROUND

Paraquat poisoning can be lethal, and aggressive treatments might have little or no effect on severely poisoned patients. Accordingly, a convenient prognostic test is necessary to guide therapy for acute paraquat poisoning. Sodium dithionite reduces paraquat to a blue radical form in alkaline plasma with a paraquat detection sensitivity of 2.0 mg/L, which is a 100% lethal concentration at 10 to 12 hours postingestion. The prognostic utility of this simple reaction was examined prospectively.

METHODS

Of 233 paraquat-poisoned patients, who were taken to the hospital within 12 hours after ingestion, the plasma samples obtained on arrival were tested using the sodium dithionite reaction. Standard saline containing 2.0 mg/L paraquat was used as the positive control. The test result was interpreted as being positive when the plasma test yielded a blue color darker than that of the positive control. The effects of aggressive treatment, including cyclophosphamide pulse and continuous venovenous hemofiltration, were evaluated retrospectively.

RESULTS

The discharge survival rate was 41.6% (97 of 233). Ninety-seven of 142 patients with negative or equivocal plasma dithionite test survived. However, all 91 patients with positive plasma dithionite test died of multiorgan failure. Cyclophosphamide and/or continuous venovenous hemofiltration could not improve survival.

CONCLUSIONS

In this single-center study, a positive plasma dithionite test was associated with 100% mortality, despite aggressive treatment. In contrast, negative or equivocal tests were associated with a 68% survival rate. It is believed that after further verification, this test can be used to guide therapy and predict the outcomes of patients suffering acute paraquat poisoning.

The area of ground glass opacities of the lungs as a predictive factor in acute paraquat intoxication

Even though plasma paraquat (PQ) levels have known to be an informative predictor, many patients succumb at low PQ levels in acute PQ intoxication. This study was designed to see whether the high resolution computerized tomography (HRCT) of the lungs would be a predictive measure in acute PQ intoxication. HRCT of the lungs was obtained from 119 patients with acute PQ intoxication on 7 days after PQ ingestion. The areas with ground glass opacities (GGOs) were evaluated at five levels with the area measurement tool of the picture archiving and communication systems. Among 119 patients, 102 survived and 17 died. The plasma PQ levels were significantly higher in the non-survivors than in the survivors (2.6+/-4.0 microg/mL vs. 0.2+/-0.4 microg/mL, P=0.02). The area with GGOs was 2.0+/-6.4% in the survivors and 73.0+/- 29.9% in the non-survivors (P<0.001). No patients survived when the area with GGOs was more than 40% but all of the patients survived when the area affected by GGOs was less than 20%. In conclusion, the area of GGOs is a useful predictor of survival in acute PQ intoxication, especially in patients with low plasma PQ levels.

The level and clinical significance of pancreatic enzymes in survivors of acute paraquat poisoning

INTRODUCTION

Acute paraquat poisoning is often fatal. When ingested, paraquat affects multiple organs including the lung, gastrointestinal tract, pancreas, kidney, heart, and central nervous system. Our center previously found that initial pancreatic function was related to the prognosis of patients with acute paraquat poisoning. However, pancreatic injury after paraquat intoxication has been incompletely studied.

METHODS

This study analyzed the clinical outcome and extent of pancreatic injury in 34 survivors of acute paraquat poisoning. Paraquat exposure was assessed based on a quantitative measure of the plasma level of paraquat by high-performance liquid chromatography. The subsequent variations in the level of pancreatic enzymes, clinical symptoms, and abdominal computed tomography were obtained. Outcomes after acute paraquat poisoning were categorized as pancreatic enzyme elevation group (elevation group: amylase >160 IU/L and lipase >100 IU/L) and nonelevation group.

RESULTS

Pancreatic enzyme elevations occurred in seven cases (20.6%), and the level of pancreatic enzymes peaked at day 7. The elevation in pancreatic enzymes after paraquat ingestion was positively correlated with the plasma paraquat level (p < 0.05 at days 4 and 7). Creatinine was higher in the elevation group. Abdominal computed tomography of the seven cases showed no evidence of pancreatitis, and significant abdominal pain was not observed.

DISCUSSION

Pancreatic enzyme elevation reflects the systemic toxicity and multiorgan involvement following acute paraquat poisoning.

CONCLUSIONS

Pancreatic injury was subtle and the elevation of pancreatic enzymes in survivors is clinically benign.

Serum total antioxidant statuses of survivors and nonsurvivors after acute paraquat poisoning

INTRODUCTION

The plasma paraquat (PQ) concentration is an excellent prognostic indicator. However, at the bedside, it is difficult to predict survivors even with known PQ concentrations. We examined the association of total antioxidant status (TAS) in serum to clinical outcome in patients with acute PQ intoxication.

METHODS

After acute PQ intoxication, 296 patients were admitted to the Institute of Pesticide Poisoning, Soonchunhyang University Cheonan Hospital, from January through December 2007. Serum total antioxidant levels in emergency department were compared between a survivor group and a nonsurvivor group.

RESULTS

Age, the amount of PQ ingested, plasma PQ concentration, leukocyte count, blood urea nitrogen (BUN), serum creatinine, uric acid, aspartate aminotransferase, alanine aminotransferase (ALT), and amylase in the emergency department were individually associated with the clinical outcome (p < 0.001), but TAS was not. Multiple logistic regression found the odds ratio (95% confidence interval) to be 10.79 (3.45-33.74) for plasma PQ concentration, but 0.43 (0.02-8.52) for TAS in serum. TAS was not associated with survival.

CONCLUSION

TAS in serum was not a significant influence on the clinical outcome in patients with acute PQ intoxication.

The clinical features of acute kidney injury in patients with acute paraquat intoxication

BACKGROUND

Paraquat (PQ) is a non-selective herbicide that generates reactive oxygen species in vivo. We hypothesized that acute kidney injury (AKI) in patients with acute PQ poisoning would provide a model for the clinical features of ROS-induced AKI.

METHODS

From January 2007 to December 2007, 278 patients with acute PQ intoxication were included in the study. AKI was defined based on the RIFLE classification. The serial changes of creatinine (Cr), the incidence of AKI and the mortality according to the RIFLE classification were analysed.

RESULTS

An initial serum Cr >1.2 mg/dL was a significant predictor of mortality [odds ratio 9.00, 95% C.I. (4.747, 17.061), P < 0.01]. The incidence of AKI was 51.4% among the 173 patients who had an initial serum Cr < or =1.2 mg/dL. Among them, 34.7% were the failure group and oliguric AKI was observed in 10 patients. The average peak serum Cr level, among the 13 survivors in the failure group, was 4.38 mg/dL at the fifth day, after ingestion, and their Cr level normalized within 3 weeks. None of the 13 survivors had permanent loss of renal function. The estimated amount of PQ ingestion was a predictor of the incidence of AKI. The mortality risk was significantly higher in the failure group than in the group without failure.

CONCLUSION

The clinical feature was characterized by fully developed AKI at the fifth day after PQ ingestion and normalized within 3 weeks without exception.

Plasma surfactant D in patients following acute paraquat intoxication

Free radical-induced lung injury is a major problem that occurs because of paraquat intoxication. Serum surfactant protein D (SP-D) reflects the severity of various lung diseases. The purpose of this study is to investigate the changes in plasma SP-D concentrations and to correlate disease severity with SP-D concentrations in patients with acute paraqaut intoxication. Twelve paraquat-intoxicated patients participated in this study. Their paraquat exposure was assessed by their plasma's paraquat level. Serial plasma SP-Ds were measured by ELISA. SP-D was decreased two and three days after the initial measurement within 2 to 72 hours of ingestion. There was no difference in initial SP-D levels between survivors and non-survivors. The SP-D test revealed a significant positive correlation between the SP-D level and PaO(2) (r = 0.384, p = 0.003, N = 57). SP-D did not predict the likelihood of survival, but it was positively correlated with PaO(2). This finding suggests that low concentrations of plasma SP-D could reflect hypoxia due to free radical-induced injury.

Hypokalemia and hypothermia are associated with 30-day mortality in patients with acute paraquat poisoning

BACKGROUND

Clinical predictors associated with acute paraquat (PQ) poisoning have not been systematically studied.

OBJECTIVE

To identify independent predictors of death in patients with acute PQ poisoning.

METHODS

This is a retrospective study executed in the emergency department of a university hospital. One hundred three consecutive patients poisoned with PQ between January 1999 and December 2004 were enrolled. Urine PQ concentration, electrolyte and renal function, detailed history, and Acute Physiology and Chronic Health Evaluation II were extracted from medical records. The outcome measure was 30-day mortality. Multivariate analysis was done by Cox-proportional hazard regression model. Receiver operating characteristics area under the curve was calculated for selected predictors.

RESULTS

The crude 30-day mortality was 67.9% (70 of 103). Independent predictors of death were acute renal failure (hazard ratio, 3.53; 95% confidence interval, 1.97-6.32), hypokalemia (2.07, 1.21-3.51), hypothermia (2.91, 1.67-5.07), suicide (2.11, 1.04-4.29), and self-reported ingested dose (2.06, 1.38-3.06). The receiver operating characteristics area under the curve of serum potassium concentrations, maximal urine PQ concentrations, and Acute Physiology and Chronic Health Evaluation II scores were 0.75 (95% confidence interval, 0.60-0.81), 0.71 (0.66-0.84), and 0.80 (0.71-0.88), respectively. Under the cutoff value of 3.6 mEq/L, hypokalemia had a sensitivity of 75% and specificity of 54% in predicting mortality.

CONCLUSION

The identified risk factors may allow better identification of those at greater mortality risk. Future development of a tailored clinical scoring system incorporating the identified risk factors for acute PQ poisoning may be of great help.

Protective effect of U-74389G on paraquat induced pneumotoxicity in rats

Paraquat is a very toxic herbicide and a dangerous pollutant of the environment. It forms reactive oxygen species and increases the lipid peroxidation in the pulmonary cells. Our aim in this study was to estimate the protective effects of the lazaroid U-74389G possessing antilipidperoxidation activity and membrane-stabilizing effect. The experiment was carried out with 96 male Wistar rats. Paraquat dichloride was administered orally at 80mg/kg. The lazaroid U-74389G was injected intraperitoneally twice - 2h before receiving the paraquat with 10mg/kg and four hours later with 5mg/kg. Isolated application of paraquat increased enzyme activities of lactate dehydrogenase (LDH) and acid phosphatase (AcP) and the total protein content in bronchoalveolar lavage fluid (BALF). In the same experimental group the number of polymorphonuclear cells (PMNs) in BALF is elevated significantly on days 1 and 3. The combined treatment with paraquat and U-74389G did not increase the total protein content and the number of PMNs and it elevated the enzyme activities of LDH and AcP significantly less than the alone application of paraquat. It is concluded that the lazaroid U-74389G reduces the pneumotoxic effects of paraquat, estimated by sensitive cytologic and biochemical markers in BALF. The protective effect of U-74389G is well-expressed until day 3 after the treatment.

No direct hepatotoxic potential following a multiple-low dose paraquat exposure in rat as related to its bioaccumulation

Paraquat (PQ) is a well-known toxic bipyridyl herbicide commonly used in agricultural countries. Pulmonary toxicity is the main cause of death but damage to other organs has also been reported. PQ is also classified as a "direct hepatotoxicant" following an acute high dose exposure. The evidence of multi-low dose toxicity of PQ was scarce. Therefore, the aim of this study was to examine the effect of multiple low doses of PQ on the liver function and xenobiotic-metabolizing enzyme activities including CYP1A1, 2E1, and 3A4, and to correlate the effects with its tissue accumulation. PQ, at the dose range 4.0-6.0 mg/kg day, was subcutaneously administered to male Wistar rats for seven consecutive days. The prominent feature of toxic response was lung toxicity. Interestingly, PQ-treatment caused a dose- and time-dependent reduction of plasma transaminase activity. Hypobilirubinemia and hypoalbuminemia were also observed without significant alteration in the liver morphology. Of all the xenobiotic-metabolizing enzymes being studied, only the activity of CYP1A1-related 7-ethoxyresorufin-O-deethylase was reduced following the highest dose of PQ administration. Plasma and tissue concentrations and accumulation of PQ analyzed by HPLC were dose-dependent showing much higher concentration (approximately 13 times) in the lung than that in the liver whereas it was undetectable in the plasma at the same time point. It can be concluded that multi-low dose PQ might affect certain synthetic function of the liver or activity of some hepatic xenobiotic-metabolizing enzymes. Minimal PQ accumulation in the liver is one of the explanations for the lack of cytotoxic hepatic injury in this study. Plasma PQ concentration may not be a good marker of exposure and toxicity after a prolonged exposure to PQ.

Paraquat-induced Fanconi syndrome

The ingestion of paraquat, a non-selective herbicide, can be fatal in humans. Paraquat is toxic to multiple organs, including the kidney, heart, gastrointestinal tract and central nervous system. Although paraquat has been established as one cause of acute tubular necrosis, Fanconi syndrome presenting as severe hypophosphataemia after paraquat intoxication has not been reported. Here, we report the case of a 44-year-old Korean woman who presented with generalized proximal tubular dysfunction including aminoaciduria, phosphaturia and glycosuria after paraquat intoxication. We found that severe hypophosphataemia induces deep drowsiness. Renal biopsy findings indicated the presence of acute tubular necrosis that may be reversible.

Clinical Implications of the Ethane in Exhaled Breath in Patients With Acute Paraquat Intoxication

STUDY OBJECTIVES

Pulmonary fibrosis due to lipid peroxidation is a major symptom of paraquat intoxication. Ethane in the expired breath (exEth) reflects lipid peroxidation and may be a measure of the damage effected by oxygen radicals in acute lung injury. The purpose of this study was to evaluate the clinical efficacy of exEth as a measure of exposure to paraquat and as an indicator of lung damage.

DESIGN

Exposure levels were evaluated by the amount ingested, semiquantitative measurement of urine paraquat levels, and plasma paraquat concentration. End-tidal breath was collected for measurement of ethane 24 h after paraquat ingestion. Renal function and blood gas analyses were conducted on the same day as the breath collection, and the final clinical outcome was defined as either recovery or death. Associations between exEth and paraquat exposure profiles and clinical outcomes were assessed using linear regression models.

PATIENTS

Twenty-one patients poisoned by paraquat were selected for the study during 2001 and 2002.

RESULTS

exEth could not be used as a predictor of laboratory parameters such as Pa(O2), Pa(CO2), serum creatinine, and lung injury (as graded by high-resolution CT). A logistical analysis revealed that only the amount of paraquat ingested was a significant predictor of fatality (p = 0.021). The strength of the association between exEth and fatality was unaffected by the addition of potential confounders such as age, sex, and time interval and paraquat concentration.

CONCLUSION

exEth cannot be used as either an independent predictor of survival or a specific marker of lung injury in patients with acute paraquat poisoning.

Toxic nephropathy: environmental chemicals

The kidney is the target of numerous xenobiotic toxicants, including environmental chemicals. Anatomical, physiological, and biochemical features of the kidney make it particularly sensitive to many environmental compounds. Factors contributing to the sensitivity of the kidney include: large blood flow, the presence of a variety of xenobiotic transporters and metabolizing enzymes, and concentration of solutes during urine production. In many cases, the conjugation of environmental chemicals to glutathione and/or cysteine targets these chemicals to the kidney where inhibition of renal function occurs through a variety of mechanisms. For example, heavy metals such as mercury and cadmium target the kidney after glutathione/cysteine conjugation. Trichloroethlene and bromobenzene are metabolized and conjugated to glutathione in the liver before renal uptake and toxicity. In contrast, renal injury produced by chloroform and aristolochic acids is dependent on renal cytochrome P450 metabolism to toxic metabolites. Other compounds, such as paraquat or diquat, damage the kidney via the production of reactive oxygen species. Finally, the low solubility of ethylene glycol metabolites causes crystal formation within the tubular lumen and nephrotoxicity. This chapter explores mechanisms of nephrotoxicity by environmental chemicals, using these example compounds. What remains to be accomplished and by far the most difficult process is the elucidation of the detailed mechanisms of tubular cell injury after toxicant uptake and metabolism. The large number of individuals experiencing a decline in renal function with age makes the search for these mechanisms very compelling.

Prospects for treatment of paraquat-induced lung fibrosis with immunosuppressive drugs and the need for better prediction of outcome: a systematic review

BACKGROUND

Acute paraquat self-poisoning is a significant problem in parts of Asia, the Pacific and the Caribbean. Ingestion of large amounts of paraquat results in rapid death, but smaller doses often cause a delayed lung fibrosis that is usually fatal. Anti-neutrophil ('immunosuppressive') treatment has been recommended to prevent lung fibrosis, but there is no consensus on efficacy.

AIM

To review the evidence for the use of immunosuppression in paraquat poisoning, and to identify validated prognostic systems that would allow the use of data from historical control studies and the future identification of patients who might benefit from immunosuppression.

DESIGN

Systematic review.

METHODS

We searched PubMed, Embase and Cochrane databases for 'paraquat' together with 'poisoning' or 'overdose'. We cross-checked references and contacted experts, and searched on [www.google.com] and [www.yahoo.com] using 'paraquat', 'cyclophosphamide', 'methylprednisolone' and 'prognosis'.

RESULTS

We found ten clinical studies of immunosuppression in paraquat poisoning. One was a randomized controlled trial (RCT). Seven used historical controls only; the other two were small (n = 1 and n = 4). Mortality in controls and patients varied markedly between studies. Three of the seven non-RCT controlled studies measured plasma paraquat; analysis using Proudfoot's or Hart's nomograms did not suggest that immunosuppression increased survival in these studies. Of 16 prognostic systems for paraquat poisoning, none has been independently validated in a large cohort.

DISCUSSION

The authors of the RCT have performed valuable and difficult research, but their results are hypothesis-forming rather than conclusive; elsewhere, the use of historical controls is problematic. In the absence of a validated prognostic marker, a large RCT of immunosuppression using death as the primary outcome is required. This RCT should also prospectively test and validate the available prognostic methods, so that future patients can be selected for this and other therapies on admission.

Predictors of survival after acute paraquat poisoning

Acute paraquat poisoning is often fatal. Many studies have investigated successful treatment modalities, but no standard treatment yet exists. The purpose of this study was to determine the predictors of survival after acute paraquat poisoning in 602 patients. The paraquat exposure was assessed based on the amount of ingested paraquat and a semiquantitative measure of the urine level of paraquat. Initial clinical parameters including vital signs, hemoglobin, white-blood-cell count, pH, PaCO2, PaO2, blood urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, total bilirubin, amylase, and glucose were obtained at the time of arrival at the emergency room. Outcomes after acute paraquat poisoning were categorized as survivors and nonsurvivors. Multiple logistic regression analysis was applied to assess the predictors of survival after acute paraquat poisoning. Some patients (55.5%) survived after oral ingestion of paraquat, whereas all those exposed to paraquat percutaneous or inhalational route survived. The amount of paraquat (24.5% concentrate of 1,1'-dimethyl-4,4'-bipyridium dichloride) ingested was 45.6 +/- 74.1 mL (mean +/- SD). In addition to degree of paraquat exposure, survival after acute paraquat poisoning was associated with age, respiratory rate, pH, PaCO2, hemoglobin, white-blood-cell count, blood urea nitrogen, amylase, and the number of failed organs in multiple logistic regression analysis. In conclusion, young age, percutaneous or inhalational route, exposure to less paraquat, and lesser degrees of leukocytosis, acidosis, and renal, hepatic, and pancreatic failures on admission are good prognostic factors of survival after acute paraquat poisoning.

Paraquat intoxication in Korea

In this study, the authors explored acute paraquat intoxication and determined potential factors related to paraquat fatalities. During 1999, 154 patients with paraquat intoxication were admitted to the Institute of Pesticide Poisoning at the Soonchunhyang University Chunan Hospital. The authors assessed paraquat exposure by quantifying the amount of ingested paraquat and by semiquantitative assay of paraquat in urine. Outcomes of paraquat intoxication were categorized as recovery or death. Among all the patients, 139 (90.3%) were transferred from other medical facilities to the Institute of Pesticide Poisoning following a mean exposure time of 20.1 hr (standard deviation = 2.6 hr). Intentional ingestion of paraquat accounted for 73.4% (113/154 patients) of all paraquat poisonings, and it represented a significantly higher fatality rate (53.2%) than did accidental ingestion (19.1% [p < .001]). The overall paraquat fatality was 43.8%. Multiple logistic-regression analysis revealed that the risk of fatality increased significantly with (1) the quantity of paraquat ingested and (2) a positive urinary paraquat test. The results indicated that paraquat is potentially lethal in humans, and the risk of fatality is directly related to the amount ingested and absorbed.

Effect of vitamin C on plasma total antioxidant status in patients with paraquat intoxication

This study was conducted to evaluate whether vitamin C (VC) was associated with total antioxidant status (TAS) in human plasma and to determine the usefulness of VC on TAS in the treatment of patients with paraquat poisoning. VC and TAS were measured in 56 healthy subjects. Then, various concentrations (1-100 mg/dl) of VC in pooled plasma from 10 volunteers were constructed in vitro and TAS was measured. The VC and TAS were measured in vivo at 0.5, 1, 2, 3, 5, 7, 9, and 11 h after injection of VC (50 mg/kg) in seven volunteers and pharmacokinetic data were calculated. Finally, various amounts of VC (100, 500, 1000, 3000 mg/day, and 3000 mg/8 h) were given to 10 paraquat-poisoned patients for 5 consecutive days, and blood was taken for TAS 1 h after each injection. The means (SD) of VC and TAS in healthy subjects were 2.22 (0.16) mmol/l and 0.48 (0.10) mg/dl, respectively. Positive correlation between VC and TAS was observed in both in vitro and in healthy volunteers. The pharmacokinetic results in vivo were as follows: means (SD) of distribution volume, area under curve, plasma clearance, half life, C(max), and T(max) were 32.0 (4.4) l, 36.4 (11.3) mg h/dl, 2.13 (1.36) l/h, 10.2 (7.8) h, 17.1 (7.1) mg/dl, and 0.64 (0.24) h, respectively. Estimated loading and maintenance doses of VC were 2278 mg and 146 mg/h, respectively. The means of TAS were increased over 5 consecutive days as 2.26, 2.76, 2.81, 3.18, and 3.58 mmol/l in paraquat patients. All patients were recovered within mean (SD) 21.2 (5.4) admission days. Our data suggested that VC was a significant antioxidant as TAS in human plasma and that increased TAS by high doses of VC could be useful as a free radical scavenger for paraquat poisoned patients.