Sodium salicylate prevents paraquat-induced apoptosis in the rat lung

Colorimetric Detection of DNase Type I 3'OH DNA Ends Using an Isothermal Amplification-Assisted Paper-Based Analytical Device

The generation of DNase type I 3'OH DNA ends is closely related to the harm of endogenous reactive oxygen species (ROS) and environmental genotoxic agents. The evaluation of this type of DNA damage plays an important role in clinical intervention and environmental toxicity assessment. Terminal deoxynucleotidyl transferase (TdT)-assisted isothermal amplification (TAIA) offers a facile and versatile way to detect DNase type I 3'OH DNA ends. Its ability of templated-independent isothermal amplification is one unique feature. Here, we reported a paper-based analytical device (PAD) coupled with a smartphone for the detection of DNase type I 3'OH DNA ends using TAIA and colorimetric signal readout. We achieved the integration of cell lysis, DNA extraction, TAIA, horseradish peroxidase (HRP)-enabled colorimetric reaction, and signal readout. This device could achieve a limit of detection of 264 cells with a total assay time of less than 45 min. By combining PAD with a smartphone, the integrated platform could be used for the visual and quantitative analysis of DNA damages with the advantages of ease-to-use, fast response, inexpensive, and instrument free. Furthermore, successful assessment of the genotoxicity in wastewater effluents suggested the great promise of the integrated platform for on-site testing in practical applications.

An origami paper-based analytical device for DNA damage analysis

Detection and characterization of DNA damage plays a critical role in genotoxicity testing, drug screening, and environmental health. We developed a fully integrated origami paper-based analytical device (oPAD) for measuring DNA damage. This simple device allows on-paper cell lysis, DNA extraction, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) reaction and signal readout with simple operation steps, enabling rapid (within 30 min) and high throughput assessment of multiple DNA damages induced by exogenous chemical agents.

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.

Protective Effect of Anthocyanin on Paraquat-Induced Apoptosis and Epithelial-Mesenchymal Transition in Alveolar Type II Cells

BACKGROUND Paraquat (PQ) can over-accumulate in alveolar epithelial cells. Anthocyanin (An) can exert anti-oxidative properties. The role of An in PQ-induced toxicity is unclear, so we aimed to explore whether An could inhibit epithelial mesenchymal transition (EMT) induced by PQ in alveolar cells. MATERIAL AND METHODS lveolar epithelial cells were treated with PQ and An with concentration gradient for 12, 24, and 48 h. The cell viability, ROS level, and apoptosis rate were determined using the Cell Counting Kit-8 (CCK-8) and flow cytometry, respectively. The lactate dehydrogenase (LDH) leakage, methane dicarboxylic aldehyde (MDA) level, glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities were determined by spectrophotometric method. The mRNA and protein expressions were detected using quantitative real-time PCR (qPCR) and Western blot, respectively. RESULTS An reduced the PQ-induced apoptosis in a dose-dependent manner. Moreover, An reduced the ratio of Bax/Bcl-2 to ROS level. We found that An suppressed the activity of LDH and MDA and improved SOD and GPX levels. Additionally, the level of PQ-induced E-cadherin was decreased by An while the expressions of vimentin, α-smooth muscle actin (α-SMA), and collagens type I (col-I) were increased. Furthermore, An inhibited the levels of transforming growth factor β1 (TGF-β1) and activin receptor-like kinase 5 (ALK5) and reduced the phosphorylation of smad2. CONCLUSIONS Our study shows newly discovered effects of anthocyanidins on EMT and supports their chemopreventive effects in paraquat-induced apoptosis in alveolar type II cells.

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.

Paraquat initially damages cochlear support cells leading to anoikis-like hair cell death

Paraquat (PQ), one of the most widely used herbicides, is extremely dangerous because it generates the highly toxic superoxide radical. When paraquat was applied to cochlear organotypic cultures, it not only damaged the outer hair cells (OHCs) and inner hair cells (IHCs), but also caused dislocation of the hair cell rows. We hypothesized that the dislocation arose from damage to the support cells (SCs) that anchors hair cells within the epithelium. To test this hypothesis, rat postnatal cochlear cultures were treated with PQ. Shortly after PQ treatment, the rows of OHCs separated from one another and migrated radially away from IHCs suggesting loss of cell-cell adhesion that hold the hair cells in proper alignment. Hair cells dislocation was associated with extensive loss of SCs in the organ of Corti, loss of tympanic border cells (TBCs) beneath the basilar membrane, the early appearance of superoxide staining and caspase-8 labeling in SCs below the OHCs and disintegration of E-cadherin and β-catenin in the organ of Corti. Damage to the TBCs and SCs occurred prior to loss of OHC or IHC loss suggesting a form of detachment-induced apoptosis referred to as anoikis.

Eukaryotic translation initiation factor 2 subunit α (eIF2α) inhibitor salubrinal attenuates paraquat-induced human lung epithelial-like A549 cell apoptosis by regulating the PERK-eIF2α signaling pathway

Paraquat (PQ), as one of the most widely used herbicides in the world, can cause severe lung damage in humans and animals. This study investigated the underlying molecular mechanism of PQ-induced lung cell damage and the protective role of salubrinal. Human lung epithelial-like A549 cells were treated with PQ for 24h and were pre-incubated with salubrinal for 2h, followed by 500μM of PQ treatment. Silencing eIF2α gene of the A549 cells with siRNA interference method was conducted. Cell morphology, cell viability, apoptosis and caspase-3 activity were assessed by different assays accordingly thereafter. The expression of PERK, p-PERK, ATF6, c-ATF6, IRE1α, p-IRE1α, CHOP, GRP78, p-eIF2α and β-actin was assayed by western blot. The data showed that PQ significantly reduced A549 cell viability, changed cell morphology, induced cell apoptosis and significantly upregulated the levels of GRP78, CHOP, p-PERK, c-ATF6 and p-IRE1α. However, 30μM salubrinal could attenuate the effects of PQ on damages to A549 cells through upregulating p-eIF2α. In contrast, knocking down eIF2α gene inhabited the effects of salubrinal. These results suggest that PQ-induced A549 cell apoptosis involved endoplasmic reticulum (ER) stress, specially the PERK-eIF2α pathway. Salubrinal attenuated A549 cells from PQ-induced damages through regulation of the PERK-eIF2α signaling.

Paraquat induces extrinsic pathway of apoptosis in A549 cells by induction of DR5 and repression of anti-apoptotic proteins, DDX3 and GSK3 expression

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

Carvedilol attenuates paraquat-induced lung injury by inhibition of proinflammatory cytokines, chemokine MCP-1, NF-κB activation and oxidative stress mediators

Paraquat is a highly toxic herbicide that selectively accumulates in the lungs and causes pulmonary damage through the oxidative and inflammatory processes. Carvedilol is a nonselective beta and alpha-adrenergic blocking agent that has been shown to possess powerful antioxidant and anti-inflammatory properties. In the present study, we evaluated the protective effects and the underlying mechanisms of carvedilol on paraquat-induced lung injury in a mouse model. Mice were injected with a single dose of paraquat (20mg/kg, ip), and treated with carvedilol (10 and 20mg/kg/day, orally) for eight days. At the end of the experiment, lung tissue and blood samples were collected for histological and biochemical analysis. The results showed that carvedilol treatment improved the histopathological changes in the lung tissue of mice exposed to paraquat. Carvedilol significantly decreased the levels of malondialdehyde (MDA), carbonyl protein, myeloperoxidase (MPO), and nitric oxide (NO), while increased the levels of glutathione (GSH), superoxide dismutase (SOD), catalase and glutathione reductase compared with paraquat group. Carvedilol treatment also significantly reduced the levels of proinflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, transforming growth factor (TGF)-β1 and monocyte chemoattractant protein (MCP)-1 in the lung tissue. Treatment of mice with carvedilol decreased paraquat-induced expression of nuclear factor kappa B (NF-κB). In addition the plasma levels of matrix metalloproteinase (MMP)-9 and the lung hydroxyproline content significantly reduced by carvedilol treatment. Taken together, these results indicate that carvedilol is able to decrease the severity of paraquat-induced lung injury through inhibition of inflammation and oxidative stress.

Unfractionated bone marrow cells attenuate paraquat-induced glomerular injury and acute renal failure by modulating the inflammatory response

The aim of this study was to evaluate the efficacy of unfractionated bone marrow cells (BMCs) in attenuating acute kidney injury (AKI) induced by paraquat (PQ) in a mouse model. PQ (55 mg/kg BW) was intraperitoneally injected into C57BL/6 female mice to induce AKI, including renal function failure, glomerular damage and renal tubule injury. Glomerular podocytes were the first target damaged by PQ, which led to glomerular injury. Upon immunofluorescence staining, podocytes depletion was validated and accompanied by increased urinary podocin levels, measured on days 1 and 6. A total of 5.4 × 10(6) BMCs obtained from the same strain of male mice were injected into AKI mice through the tail vein at 3, 24, and 48 hours after PQ administration. As a result, renal function increased, tubular and glomerular injury were ameliorated, podocytes loss improved, and recipient mortality decreased. In addition, BMCs co-treatment decreased the extent of neutrophil infiltration and modulated the inflammatory response by shifting from pro-inflammatory Th1 to an anti-inflammatory Th2 profile, where IL-1β, TNF-α, IL-6 and IFN-γ levels declined and IL-10 and IL-4 levels increased. The present study provides a platform to investigate PQ-induced AKI and repeated BMCs injection represents an efficient therapeutic strategy.

Impairment of striatal mitochondrial function by acute paraquat poisoning

Mitochondria are essential for survival. Their primary function is to support aerobic respiration and to provide energy for intracellular metabolic pathways. Paraquat is a redox cycling agent capable of generating reactive oxygen species. The aim of the present study was to evaluate changes in cortical and striatal mitochondrial function in an experimental model of acute paraquat toxicity and to compare if the brain areas and the molecular mechanisms involved were similar to those observed after chronic exposure. Sprague-Dawley rats received paraquat (25 mg/Kg i.p.) or saline and were sacrificed after 24 h. Paraquat treatment decreased complex I and IV activity by 37 and 21 % respectively in striatal mitochondria. Paraquat inhibited striatal state 4 and state 3 KCN-sensitive respiration by 80 % and 62 % respectively, indicating a direct effect on respiratory chain. An increase of 2.2 fold in state 4 and 2.3 fold in state 3 in KCN-insensitive respiration was observed in striatal mitochondria from paraquat animals, suggesting that paraquat redox cycling also consumed oxygen. Paraquat treatment increased hydrogen peroxide production (150 %), TBARS production (42 %) and cardiolipin oxidation/depletion (12 %) in striatal mitochondria. Also, changes in mitochondrial polarization was induced after paraquat treatment. However, no changes were observed in any of these parameters in cortical mitochondria from paraquat treated-animals. These results suggest that paraquat treatment induced a clear striatal mitochondrial dysfunction due to both paraquat redox cycling reactions and impairment of the mitochondrial electron transport, causing oxidative damage. As a consequence, mitochondrial dysfunction could probably lead to alterations in cellular bioenergetics.

Caenorhabditis elegans as an alternative in vivo model to determine oral uptake, nanotoxicity, and efficacy of melatonin-loaded lipid-core nanocapsules on paraquat damage

Caenorhabditis elegans is an alternative in vivo model that is being successfully used to assess the pharmacological and toxic effects of drugs. The exponential growth of nanotechnology requires the use of alternative in vivo models to assess the toxic effects of theses nanomaterials. The use of polymeric nanocapsules has shown promising results for drug delivery. Moreover, these formulations have not been used in cases of intoxication, such as in treatment of paraquat (PQ) poisoning. Thus, the use of drugs with properties improved by nanotechnology is a promising approach to overcome the toxic effects of PQ. This research aimed to evaluate the absorption of rhodamine B-labeled melatonin (Mel)-loaded lipid-core nanocapsules (LNC) by C. elegans, the application of this model in nanotoxicology, and the protection of Mel-LNC against PQ damage. The formulations were prepared by self-assembly and characterized by particle sizing, zeta potential, drug content, and encapsulation efficiency. The results demonstrated that the formulations had narrow size distributions. Rhodamine B-labeled Mel-LNC were orally absorbed and distributed in the worms. The toxicity assessment of LNC showed a lethal dose 50% near the highest dose tested, indicating low toxicity of the nanocapsules. Moreover, pretreatment with Mel-LNC significantly increased the survival rate, reduced the reactive oxygen species, and maintained the development in C. elegans exposed to PQ compared to those worms that were either untreated or pretreated with free Mel. These results demonstrated for the first time the uptake and distribution of Mel-LNC by a nematode, and indicate that while LNC is not toxic, Mel-LNC prevents the effects of PQ poisoning. Thus, C. elegans may be an interesting alternative model to test the nanocapsules toxicity and efficacy.

Sodium salicylate reduced insulin resistance in the retina of a type 2 diabetic rat model

Sodium salicylate has been reported to reduce markers of diabetic retinopathy in a type 1 rat model. Because rates of type 2 diabetes are on the rise, we wanted to determine whether salicylate could improve insulin resistance in a type 2 rat model, as well as improve retinal function. We treated lean and obese BBZDR/Wor type 2 diabetic rats with salicylate in their chow for 2 months. Prior to salicylate treatment, rats underwent an electroretinogram to measure retinal function. After 2 months of treatment, rats underwent an additional electroretinogram prior to sacrifice. In addition to the animal model, we also treated retinal endothelial cells (REC) and rat Müller cells with salicylate and performed the same analyses as done for the rat retinal lysates. To investigate the role of salicylate in insulin signaling, we measured TNFα and caspase 3 levels by ELISA, as well as performed Western blotting for insulin receptor substrate 1, insulin receptor, SOCS3, and pro- and anti-apoptotic markers. Data demonstrated that salicylate significantly improved retinal function, as well as reduced TNFα and SOCS3-induced insulin resistance in all samples. Overall, results suggest that salicylate is effective in reducing insulin resistance in the retina of type 2 diabetic rat models.

Protective effects of intranasal curcumin on paraquot induced acute lung injury (ALI) in mice

Paraquot (PQ) is widely and commonly used as herbicide and has been reported to be hazardous as it causes lung injury. However, molecular mechanism underlying lung toxicity caused by PQ has not been elucidated. Curcumin, a known anti-inflammatory molecule derived from rhizomes of Curcuma longa has variety of pharmacological activities including free-radical scavenging properties but the protective effects of curcumin on PQ-induced acute lung injury (ALI) have not been studied. In this study, we aimed to study the effects of curcumin on ALI caused by PQ in male parke's strain mice which were challenged acutely by PQ (50mg/kg, i.p.) with or without curcumin an hour before (5mg/kg, i.n.) PQ intoxication. Lung specimens and the bronchoalveolar lavage fluid (BALF) were isolated for pathological and biochemical analysis after 48h of PQ exposure. Curcumin administration has significantly enhanced superoxide dismutase (SOD) and catalase activities. Lung wet/dry weight ratio, malondialdehyde (MDA) and lactate dehydrogenase (LDH) content, total cell number and myeloperoxidase (MPO) levels in BALF as well as neutrophil infiltration were attenuated by curcumin. Pathological studies also revealed that intranasal curcumin alleviate PQ-induced pulmonary damage and pro-inflammatory cytokine levels like tumor necrosis factor-α (TNF-α) and nitric oxide (NO). These results suggest that intranasal curcumin may directly target lungs and curcumin inhalers may prove to be effective in PQ-induced ALI treatment in near future.

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.

Metallothioneins attenuate paraquat-induced acute lung injury in mice through the mechanisms of anti-oxidation and anti-apoptosis

Paraquat (PQ) is a widely used herbicide, and lung is the primary target of PQ poisoning. Metallothionein (MT) is a potent antioxidant and free radical scavenger, and has been shown to play a protective role in lung injury induced by different stressors. This study was undertaken to evaluate the protective potential of MT against PQ-induced acute lung injury using MT-I/II null (MT(-/-)) mice. Wild-type (MT(+/+)) mice and MT(-/-) mice were given one intragastric administration of 50mg/kg PQ for 24h, and it was revealed that MT(-/-) mice were more susceptible to PQ-induced acute lung injury than MT(+/+) mice evidenced by the following findings. As compared with MT(+/+) mice, MT(-/-) mice presented more severe histopathological lesions in the lung, higher pulmonary malondialdehyde content, and more reduced pulmonary antioxidative enzymes activities. PQ also induced more apoptosis in pneumocytes from MT(-/-) mice, and the expressions of apoptosis-related proteins Bax, Bcl-2, cleaved-caspase-3, and the ratio of Bax/Bcl-2 were all more significantly increased in PQ-treated MT(-/-) mice. Our results clearly demonstrate that endogenous MT can attenuate PQ-induced acute lung injury, possibly through the mechanisms of anti-oxidation and anti-apoptosis.

Modulatory effects of sodium salicylate on the factors affecting protein aggregation during rotenone induced Parkinson's disease pathology

Sodium salicylate (SS) confers neuroprotection in various models of Parkinson's disease (PD) but the mechanisms behind its protective actions are not clear. PD pathology is multifactorial involving numerous processes such as protein aggregation, dysfunction of protein degradation machinery and apoptosis. Detailed evaluation of effects of SS on these processes can provide an insight into the mechanism of neuroprotection by SS in PD pathology. In a rotenone (2mg/kg b.w.) based rat model of PD, SS (100mg/kg b.w.) was administered in conjunction. Drug treatments continued for 5 weeks after which various analyses were conducted using mid-brain tissue. IHC analysis revealed a decline in the aggregation of α-synuclein and ubiquitin with SS supplementation. These effects might be mediated by the elevation in HSF-1, HSP-40, and HSP-27 expression following SS co-treatment. This HSP upregulation helped in the improvement in proteasome activity as well as expression. Further, IHC analysis revealed that SS co-treatment prevented the activation of astrocytes caused by rotenone. Since astrocytes are involved in maintenance of glutathione (GSH) homeostasis, it resulted in a concomitant improvement in the GSH levels. As a result, decrease in apoptosis as indicated by caspase-9 and caspase-3 expression as well as TUNEL assay was also observed in the SS conjunction group. Our results indicate that besides being a known free radical scavenger and anti-inflammatory compound, SS can provide neuroprotection by differently upregulating the HSPs and reducing the protein aggregation burden.

Neuroprotective effect of steroidal alkaloids on glutamate-induced toxicity by preserving mitochondrial membrane potential and reducing oxidative stress

Several evidences suggest that enhanced oxidative stress is involved in the pathogenesis and/or progression of several neurodegenerative diseases. The aim of this study was to investigate for the first time whether both extracts from tomato plant (Lycopersicon esculentum Mill.) leaves and their isolated steroidal alkaloids (tomatine and tomatidine) afford neuroprotective effect against glutamate-induced toxicity in SH-SY5Y neuroblastoma cells and to elucidate the mechanisms underlying this protection. Steroidal alkaloids from tomato are well known for their cholinesterases' inhibitory capacity and the results showed that both purified extracts and isolated compounds, at non-toxic concentrations for gastric (AGS), intestinal (Caco-2) and neuronal (SH-SY5Y) cells, have the capacity to preserve mitochondria membrane potential and to decrease reactive oxygen species levels of SH-SY5Y glutamate-insulted cells. Moreover, the use of specific antagonists of cholinergic receptors allowed observing that tomatine and tomatidine can interact with nicotinic receptors, specifically with the α7 type. No effect on muscarinic receptors was noticed. In addition to the selective cholinesterases' inhibition revealed by the compounds/extracts, these results provide novel and important insights into their neuroprotective mechanism. This work also demystifies the applicability of these compounds in therapeutics, by demonstrating that their toxicity was overestimated for long time.

Lysine acetylsalicylate increases the safety of a paraquat formulation to freshwater primary producers: a case study with the microalga Chlorella vulgaris

Large amounts of herbicides are presently used in the industrialized nations worldwide, with an inexorable burden to the environment, especially to aquatic ecosystems. Primary producers such as microalgae are of especial concern because they are vital for the input of energy into the ecosystem and for the maintenance of oxygen in water on which most of other marine life forms depend on. The herbicide paraquat (PQ) is known to cause inhibition of photosynthesis and irreversible damage to photosynthetic organisms through generation of reactive oxygen species in a light-dependent manner. Previous studies have led to the development of a new formulation of PQ containing lysine acetylsalicylate (LAS) as an antidote, which was shown to prevent the mammalian toxicity of PQ, while maintaining the herbicidal effect. However, the safety of this formulation to primary producers in relation to commercially available PQ formulations has hitherto not been established. Therefore, the aim of this study was to evaluate the toxicity of the PQ+LAS formulation in comparison with the PQ, using Chlorella vulgaris as a test organism. Effect criterion was the inhibition of microalgal population growth. Following a 96 h exposure to increasing concentrations of PQ, C. vulgaris growth was almost completely inhibited, an effect that was significantly prevented by LAS at the proportion used in the formulation (PQ+LAS) 1:2 (mol/mol), while the highest protection was achieved at the proportion of 1:8. In conclusion, the present work demonstrated that the new formulation with PQ+LAS has a reduced toxicity to C. vulgaris when compared to Gramoxone(®).

Single high-dose dexamethasone and sodium salicylate failed to attenuate phosgene-induced acute lung injury in rats

Life-threatening acute lung injury potentially occurs following high-level accidental exposures to phosgene gas. This situation was mirrored in rats exposed nose-only at 900-1000 mg phosgene/m(3)min. At this exposure level, previous studies on rats demonstrated sustained reflexively induced cardiopulmonary dysfunction and evidence of vascular fluid redistribution. These findings challenge the currently applied treatment strategies to mitigate the presumed non-cardiogenic lung edema by steroidal or non-steroidal anti-inflammatory drugs. This study investigates whether high doses of curatively administered dexamethasone (DX; 100 mg/kg bw, ip) and sodium salicylate (SS; 200 mg/kg bw, ip), alone or in combination, show efficacy to mitigate the phosgene-induced lung edema. Exhaled nitric oxide (eNO), animal morbidity and mortality, and increased lung weights one day postexposure served as endpoints of lung injury and drug efficacy. When applying this dosing regimen, SS showed minimal (if any) efficacy while DX, alone or in combination with SS, substantially aggravated the emerging lung edema (lung weights) with 40% mortality. The degree of acute lung injury (ALI) was mirrored by increased eNO. Its direct relationship to ALI-severity was evidenced by decreased eNO following NO-synthetase inhibitor administration (aminoguanidine-aerosol) and associated mitigation of ALI. All non-treated phosgene-exposed as well as treated but non-phosgene-exposed rats survived. This experimental evidence suggests that high-dose corticoid treatments may aggravate the pulmonary toxicity of phosgene. Similarly, this outcome supports the supposition that non-inflammatory, cardiogenic and/or neurogenic factors play a role in this type of acute lung injury.

New formulation of paraquat with lysine acetylsalicylate with low mammalian toxicity and effective herbicidal activity

BACKGROUND

Currently, the commercial formulations of the herbicide paraquat are highly toxic to humans, and no effective antidote is available for paraquat poisoning. The aim of the present study was to develop a safe formulation, combining paraquat and the known antidote lysine acetylsalicylate. The toxicity of a mixture of Gramoxone® (20% paraquat) and lysine acetylsalicylate in adult Wistar male rats and the herbicidal efficacy against grass lawn (50% of Poa pratensis and 50% of Festuca arundinacea) were evaluated. This new formulation was administered to Wistar rats by gavage at 125 mg kg(-1) of paraquat ion and lysine acetylsalicylate at 79, 158 or 316 mg kg(-1) body weight, and the survival rate was observed for 30 days.

RESULTS

The survival rate of the paraquat group was only 40%, while lysine acetylsalicylate provided effective protection, with full survival observed in the groups that received 125 mg kg(-1) of paraquat ion and 316 mg kg(-1) of lysine acetylsalicylate. Both formulations of paraquat, either in the absence or in the presence of lysine acetylsalicylate, provided the same herbicidal activity against the tested herbal species.

CONCLUSIONS

The present formulation of paraquat containing lysine acetylsalicylate, significantly decreases mammalian toxicity while maintaining effective herbicidal activity.

Differential Effects of Methyl-4-Phenylpyridinium Ion, Rotenone, and Paraquat on Differentiated SH-SY5Y Cells

Paraquat (PQ), a cationic nonselective bipyridyl herbicide, has been used as neurotoxicant to modulate Parkinson's disease in laboratory settings. Other compounds like rotenone (ROT), a pesticide, and 1-methyl-4-phenylpyridinium ion (MPP(+)) have been widely used as neurotoxicants. We compared the toxicity of these three neurotoxicants using differentiated dopaminergic SH-SY5Y human cells, aiming to elucidate their differential effects. PQ-induced neurotoxicity was shown to be concentration and time dependent, being mitochondrial dysfunction followed by neuronal death. On the other hand, cells exposure to MPP(+) induced mitochondrial dysfunction, but not cellular lyses. Meanwhile, ROT promoted both mitochondrial dysfunction and neuronal death, revealing a biphasic pattern. To further elucidate PQ neurotoxic mechanism, several protective agents were used. SH-SY5Y cells pretreatment with tiron (TIR) and 2-hydroxybenzoic acid sodium salt (NaSAL), both antioxidants, and N ω -nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric oxide synthase inhibitor, partially protected against PQ-induced cell injury. Additionally, 1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3-phenyl-propyl)piperazine (GBR 12909), a dopamine transporter inhibitor, and cycloheximide (CHX), a protein synthesis inhibitor, also partially protected against PQ-induced cell injury. In conclusion, we demonstrated that PQ, MPP(+), and ROT exerted differential toxic effects on dopaminergic cells. PQ neurotoxicity occurred through exacerbated oxidative stress, with involvement of uptake through the dopamine transporter and protein synthesis.

Recombinant adenovirus Ad-RUNrf2 reduces paraquat-induced A549 injury

OBJECTIVE

An RU486-inducible recombinant adenovirus-Nrf2 construct (Ad-RUNrf2) was constructed and expressed in H460 cells to determine whether Nrf2 gene expression can be regulated and to observe the effect of the adenovirus Ad-RUNrf2 on inflammatory cytokines, oxidative stress and apoptotic factors that mediate paraquat (PQ)-induced A549 cell injury.

METHODS

The Nrf2 gene within the RU486 (mifepristone)-inducible system was introduced into an adenovirus vector. A549 cells were transfected with Ad-RUNrf2, and Nrf2 expression was detected using Western blotting and real time-polymerase chain reaction (RT-PCR). RT-PCR, Western blots and enzyme-linked immunosorbent assay were used for observing the effect of RU486-induced Nrf2 expression on the inflammatory cytokines (interleukin-6 (IL-6), IL-10 and tumor necrosis factor-α (TNF-α)), oxidative stress factors (catalase (CAT) and malondialdehyde (MDA)) and apoptosis factors (caspase-3, caspase-9 and cytochrome C) that mediated PQ-induced A549 cell injury.

RESULTS

After infection of H460 cells by Ad-RUNrf2, RT-PCR and Western blot analyses showed that Nrf2 expression increased with additional RU486 doses. IL-6 and TNF-α protein and gene expression levels were significantly reduced, and IL-10 protein levels were significantly increased. Although IL-10 expression increased, it remained significantly lower than that of noninduced adenovirus infection and the simple virus exposure group. RU486 induced a significant reduction in MDA expression and increased CAT protein levels. Caspase-9 and caspase-3 protein and gene expression levels decreased in the RU486 induction group (p < 0.05). Cytochrome C protein levels were not significantly reduced, but its gene expression was significantly decreased (p < 0.05).

CONCLUSION

Ad-RUNrf2 adenovirus was successfully constructed and can be stably expressed and regulated in cells. Ad-RUNrf2 can reduce PQ-induced inflammation, oxidative stress and apoptosis in A549 cells.

Effects of RNA interference-induced Smad3 gene silencing on pulmonary fibrosis caused by paraquat in mice

Paraquat (PQ) poisoning induces many physiological and histological changes in the human body, but PQ-induced pulmonary fibrosis is most often associated with death. The signaling pathway associated with pulmonary fibrosis is reliant on transforming growth factor-beta 1 (tgf-β(1)) activation of Smad3, as evidenced by Smad3-deficient mice being resistant to tgf-β(1)-induced pulmonary fibrosis. Thus, we sought to determine whether targeted silencing of Smad3 gene expression could inhibit PQ-induced pulmonary fibrosis in mice. We developed an RNA interference (RNAi) method using short hairpin RNAs (shRNAs) targeting Smad3. The shRNA expression cassettes capable of effectively silencing Smad3 in L929 mouse fibroblasts were transferred to an adenovirus vector and intratracheally administered into mouse lung. Treated mice presented with inhibited Smad3 mRNA and protein and were resistant to PQ-induced pulmonary fibrosis, as evidenced by suppressed expressions of procollagen type I mRNA and hydroxyproline amino acid. Thus, silencing of Smad3 appears to be a promising alternative strategy for the treatment of PQ-induced pulmonary fibrosis.

Medical management of paraquat ingestion

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

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.

Consumption of hydrogen water reduces paraquat-induced acute lung injury in rats

Exposure to paraquat leads to acute lung injury and oxidative stress is widely accepted as a contributor to paraquat-induced acute lung injury. Recent studies have reported that consumption of water with dissolved molecular hydrogen to a saturated level (hydrogen water) prevents oxidative stress-induced diseases. Here, we investigated whether consumption of saturated hydrogen saline protects rats against paraquat-induced acute lung injury. Adult male Sprague-Dawley (SD) rats were randomly divided into four groups: Control group; hydrogen water-only group (HW group); paraquat-only group (PQ group); paraquat and hydrogen water group (PQ + HW group). The rats in control group and HW group drank pure water or hydrogen water; the rats in PQ group and PQ + HW group were intraperitonealy injected with paraquat (35 mg/kg) and then provided pure water or hydrogen water. Both biochemical and histological lung alterations were measured. The results showed that hydrogen water ameliorated these alterations, demonstrating that hydrogen water alleviated paraquat-induced acute lung injury possibly by inhibition of oxidative damage.

Growth arrest and DNA damage protein 45b (Gadd45b) protects retinal ganglion cells from injuries

We hypothesize that neurons have protective mechanisms against adverse local conditions that improve the chances of cell survival. In the present study, we find that growth arrest and DNA damage protein 45b (Gadd45b), a previously unknown molecule in neurons of any type, is neuroprotective in retinal ganglion cells (RGCs) in the retina. Gadd45b is upregulated in RGCs in response to oxidative stress, aging and elevated intraocular pressure. Using Gadd45b siRNA, we show that Gadd45b protects RGCs from dying against different neuronal injuries including oxidative stress, TNFalpha cytotoxicity, and glutamate excitotoxicity in vitro. Using Gadd45b knockout mice, we find that Gadd45b protects RGCs from dying against oxidative stress in vivo. Our data suggest that Gadd45b is an important component of the intrinsic neuroprotective mechanisms of RGC neurons in the retina and, perhaps in the CNS as well.

An effective antidote for paraquat poisonings: the treatment with lysine acetylsalicylate

Sodium salicylate (NaSAL) has been shown to have a multifactorial protection mechanism against paraquat (PQ)-induced toxicity, due to its ability to modulate inflammatory signalling systems, to prevent oxidative stress and to its capacity to chelate PQ. Considering that currently there is no pharmaceutical formulation available for parenteral administration of NaSAL, the aim of the present study was to evaluate the antidotal feasibility of a salicylate prodrug, lysine acetylsalicylate (LAS), accessible for parenteral administrations. PQ was administered to Wistar rats by gavage (125mg/kg of PQ ion) and the treatment was performed intraperitoneally with different doses (100, 200 and 400mg/kg of body weight) of LAS. Survival rate was followed during 30 days and living animals at this endpoint were sacrificed for lung, kidney, liver, jejune and heart histological analysis. It was shown, that the salicylate prodrug, LAS, available in a large number of hospitals, is also effective in the treatment of PQ intoxications. From all tested LAS doses, 200mg/kg assured animal's full survival. Comparatively to 60% of mortality observed in PQ only exposed animals, the lethality was higher (80%) in the group that received 400mg/kg of LAS 2h after PQ administration. The dose of 100mg/kg of LAS showed only a modest protection (60% of survival). Collagen deposition was observed by histological analysis in survived animals of all experimental groups, being less pronounced in animals receiving 200mg/kg of LAS, reinforcing the importance of this dose against tissue damage induced by PQ. The results allow us to suggest that LAS should be considered in the hospital treatment of PQ poisonings.

Retinoic acid induces apoptosis by a non-classical mechanism of ERK1/2 activation

Even though RA is involved in differentiation and apoptosis of normal and cancer cells, being sometimes used as adjuvant in chemotherapy, its mechanisms of action involve multiple overlapping pathways that still remain unclear. Recent studies point out that RA exerts rapid and non-genomic effects, which are independent of RAR/RXR-mediated gene transcription. In this work, we reported that RA treatment for 24 h decreases cell viability, induces apoptosis dependent on caspase-3 activation, and activates the transcription factor AP-1 in cultured Sertoli cells. Moreover, RA induced a rapid and non-classical stimulation of ERK1/2. ERK1/2 activation was mediated by MEK1/2, and the protein synthesis inhibitor cycloheximide did not alter the pattern of RA-induced ERK1/2 phosphorylation. Pharmacological inhibition of MEK1/2-ERK1/2 pathway with UO126 blocked caspase-3 activation, decreased AP-1 binding to DNA and inhibited apoptosis. Overall, our data suggest that a rapid and non-genomic effect of RA upon MEK1/2-ERK1/2 pathway leads to caspase-3 activation and caspase-3-dependent apoptosis in cultured Sertoli cells. The non-canonical RA signaling presented in this work evokes new perspectives of RA action, which may play an important role in mediating early biological effects of RA modulating cell death in normal and tumor cells.

Paraquat poisonings: mechanisms of lung toxicity, clinical features, and treatment

Paraquat dichloride (methyl viologen; PQ) is an effective and widely used herbicide that has a proven safety record when appropriately applied to eliminate weeds. However, over the last decades, there have been numerous fatalities, mainly caused by accidental or voluntary ingestion. PQ poisoning is an extremely frustrating condition to manage clinically, due to the elevated morbidity and mortality observed so far and due to the lack of effective treatments to be used in humans. PQ mainly accumulates in the lung (pulmonary concentrations can be 6 to 10 times higher than those in the plasma), where it is retained even when blood levels start to decrease. The pulmonary effects can be explained by the participation of the polyamine transport system abundantly expressed in the membrane of alveolar cells type I, II, and Clara cells. Further downstream at the toxicodynamic level, the main molecular mechanism of PQ toxicity is based on redox cycling and intracellular oxidative stress generation. With this review we aimed to collect and describe the most pertinent and significant findings published in established scientific publications since the discovery of PQ, focusing on the most recent developments related to PQ lung toxicity and their relevance to the treatment of human poisonings. Considerable space is also dedicated to techniques for prognosis prediction, since these could allow development of rigorous clinical protocols that may produce comparable data for the evaluation of proposed therapies.