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.

GDF15 Is an Inflammation-Induced Central Mediator of Tissue Tolerance

Growth and differentiation factor 15 (GDF15) is an inflammation-associated hormone with poorly defined biology. Here, we investigated the role of GDF15 in bacterial and viral infections. We found that inflammation induced GDF15, and that GDF15 was necessary for surviving both bacterial and viral infections, as well as sepsis. The protective effects of GDF15 were largely independent of pathogen control or the magnitude of inflammatory response, suggesting a role in disease tolerance. Indeed, we found that GDF15 was required for hepatic sympathetic outflow and triglyceride metabolism. Failure to defend the lower limit of plasma triglyceride levels was associated with impaired cardiac function and maintenance of body temperature, effects that could be rescued by exogenous administration of lipids. Together, we show that GDF15 coordinates tolerance to inflammatory damage through regulation of triglyceride metabolism.

Abnormal methylation of imprinted genes in human sperm is associated with oligozoospermia

Genomic imprinting marks in the male germ line are already established in the adult germinal stem cell population. We studied the methylation patterns of H19 and MEST imprinted genes in sperm of control and oligozoospermic patients, by bisulphite genomic sequencing. We here report that 7 out of 15 (46.7%) patients with a sperm count below 10 x 10(6)/ml display defective methylation of H19 and/or MEST imprinted genes. In these cases, hypomethylation was observed in 5.54% (1.2-8.3%) and complete unmethylation in 2.95% (0-5.9%) of H19 clones. Similarly, for the CTCF-binding site 6, hypomethylation occurred in 4.8% (1.2-8.9%) and complete unmethylation in 3.7% (0-6.9%) of the clones. Conversely, hypermethylation occurred in 8.3% (3.8-12.2%) and complete methylation in 6.1% (3.8-7.6%) of MEST clones. Of the seven patients presenting imprinting errors, two had both H19 hypomethylation and MEST hypermethylation, whereas five displayed only one imprinted gene affected. The frequency of patients with MEST hypermethylation was highest in the severe oligozoospermia group (2/5 patients), whereas H19 hypomethylation was more frequent in the moderate oligozoospermia (2/5 patients). In all cases, global sperm genome methylation analysis (LINE1 transposon) suggested that defects were specific for imprinted genes. These findings could contribute to an explanation of the cause of Silver-Russell syndrome in children born with H19 hypomethylation after assisted reproductive technologies (ART). Additionally, unmethylation of the CTCF-binding site could lead to inactivation of the paternal IGF2 gene, and be linked to decreased embryo quality and birth weight, often associated with ART.

Cardiac valve calcification in haemodialysis patients: role of calcium-phosphate metabolism

BACKGROUND

Cardiac valve calcification (VC) has been detected with increased frequency in haemodialysis (HD) patients, making it necessary to determine the potential pathogenic factors in uraemic patients.

METHODS

A total of 92 chronic HD patients (39 female, 53 male) and 92 age and gender-matched nondialysis control subjects were evaluated by echocardiography and a severity score for VC was determined. Calcium phosphate metabolism was evaluated at the beginning of haemodialysis.

RESULTS

We found a greater prevalence of VC in dialysis patients than in normal patients (mitral annulus 44.5% vs 10%, P = 0.02; aortic annulus 52% vs 4.3%, P = 0.01). HD patients with mitral calcification were found to be older than patients without calcification, were on long-term renal replacement therapy, had longer duration of predialysis arterial hypertension, had greater values of the highest value of mean calcium phosphate product in 6 successive months (CaxP) and the highest absolute value of calcium-phosphate product (CaxPmax). We also found a positive correlation between calcification score, age, and CaxP. No correlation was found between actual VC and arterial hypertension or parathyroid hormone. Multiple stepwise regression analysis selected age and CaxP as the most predictive parameters for mitral calcification (r = 0.47). Mitral calcification was associated more frequently with rhythm and cardiac conduction defects, valvular insufficiency and with peripheral vascular calcification. Aortic calcification was correlated with age (r = 0.42) and longer duration of predialysis arterial hypertension.

CONCLUSION

Our study confirmed an increased prevalence of VC in HD patients and selected age and calcium phosphate product as the most predictive parameters. These findings support careful monitoring of calcium metabolism beginning at the early stages of end-stage renal failure to reduce the risk of heart disease.

Paraquat exposure as an etiological factor of Parkinson's disease

Parkinson's disease (PD) is a multifactorial chronic progressive neurodegenerative disease influenced by age, and by genetic and environmental factors. The role of genetic predisposition in PD has been increasingly acknowledged and a number of relevant genes have been identified (e.g., genes encoding alpha-synuclein, parkin, and dardarin), while the search for environmental factors that influence the pathogenesis of PD has only recently begun to escalate. In recent years, the investigation on paraquat (PQ) toxicity has suggested that this herbicide might be an environmental factor contributing to this neurodegenerative disorder. Although the biochemical mechanism through which PQ causes neurodegeneration in PD is not yet fully understood, PQ-induced lipid peroxidation and consequent cell death of dopaminergic neurons can be responsible for the onset of the Parkinsonian syndrome, thus indicating that this herbicide may induce PD or influence its natural course. PQ has also been recently considered as an eligible candidate for inducing the Parkinsonian syndrome in laboratory animals, and can therefore constitute an alternative tool in suitable animal models for the study of PD. In the present review, the recent evidences linking PQ exposure with PD development are discussed, with the aim of encouraging new perspectives and further investigation on the involvement of environmental agents in PD.

Do metals inhibit acetylcholinesterase (AChE)? Implementation of assay conditions for the use of AChE activity as a biomarker of metal toxicity

The enzymatic activity of acetylcholinesterase (AChE) has been shown to be altered by environmental contaminants such as metals. However, the available literature illustrates a background of contradictory results regarding these effects. Therefore, the main purpose of this study was to investigate the potential of five metal ions (nickel, copper, zinc, cadmium and mercury) to inhibit AChE activity in vitro. First, to accomplish this objective, the possible interference of metals as test toxicants in the Ellman's assay, which is widely used to assess AChE activity, was studied. The potential influence of two different reaction buffers (phosphate and Tris) was also determined. The results suggest that the selected metals react with the products of this photometric technique. It is impossible to ascertain the artefactual contribution of the interaction of the metals with the technique when measuring AChE inhibition. This constitutes a major obstacle in obtaining accurate data. The presence of phosphate ions also makes enzymatic inhibition difficult to analyse. Attending to this evidence, an assay using the substrate o-nitrophenyl acetate and Tris buffer was used to investigate the effects of metals on AChE activity. O-nitrophenyl acetate is also a substrate for esterases other than cholinesterases. It is therefore only possible to use it for the measurement of cholinesterase activity with purified enzymes or after a previous verification of the absence of other esterases in the sample tissue. Under these conditions, the results indicate that with the exception of nickel, all tested metals significantly inhibit AChE activity.

BioTIME: A database of biodiversity time series for the Anthropocene

MOTIVATION

The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

MAIN TYPES OF VARIABLES INCLUDED

The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

SPATIAL LOCATION AND GRAIN

BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2).

TIME PERIOD AND GRAIN

BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

MAJOR TAXA AND LEVEL OF MEASUREMENT

BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

SOFTWARE FORMAT

.csv and .SQL.

Antioxidant activity of Centaurium erythraea infusion evidenced by its superoxide radical scavenging and xanthine oxidase inhibitory activity

Centaurium erythraea Rafin. (Gentianaceae) has long been used in traditional medicine. This plant contains considerable amounts of polyphenolic compounds, namely, xanthones and phenolic acids as the main constituents. Because phenolic groups exhibit activity as radical scavengers and/or metal chelators, this study evaluated the superoxide radical scavenging properties of a lyophilized infusion obtained from C. erythraea flowering tops. Superoxide radical scavenging activity was assayed using enzymatic (xanthine/xanthine oxidase) and nonenzymatic (NADH/phenazine methosulfate) superoxide generating systems. This study provided evidence that C. erythraea exhibits interesting antioxidant properties, expressed either by the capacity to scavenge superoxide radical or to noncompetitively inhibit xanthine oxidase. The main phenolic compounds present in this extract were several esters of hydroxycinnamic acids, namely, p-coumaric, ferulic, and sinapic acids.

Immunohistochemical study of the expression of MUC6 mucin and co-expression of other secreted mucins (MUC5AC and MUC2) in human gastric carcinomas

To investigate the expression of MUC6 mucin in gastric carcinomas, we generated a novel monoclonal antibody (MAb CLH5) using an MUC6 synthetic peptide. MAb CLH5 reacted exclusively with the MUC6 peptide and with native and deglycosylated mucin extracts from gastric tissues. MAb CLH5 immunoreactivity was observed in normal gastric mucosa restricted to pyloric glands of the antrum and mucopeptic cells of the neck zone of the body region. In a series of 104 gastric carcinomas, 31 (29.8%) were immunoreactive for MUC6. The expression of MUC6 was not associated with histomorphological type or with clinicopathological features of the carcinomas. Analysis of the co-expression of MUC6 with other secreted mucins (MUC5AC and MUC2) in 20 gastric carcinomas revealed that different mucin core proteins are co-expressed in 55% of the cases. MUC6 was co-expressed and co-localized with MUC5AC in 45% and with MUC2 in 5% of the cases. Expression of MUC2 alone was observed in 25% of the cases. All carcinomas expressing MUC2 mucin in more than 50% of the cells were of the mucinous type according to the WHO classification. The co-expression of mucins was independent of the histomorphological type and stage of the tumors. In conclusion, we observed, using a novel well-characterized MAb, that MUC6 is a good marker of mucopeptic cell differentiation and is expressed in 30% of gastric carcinomas, independent of the clinicopathological features of the cases. Furthermore, we found that co-expression and co-localization of mucins in gastric carcinomas is independent of histomorphology and staging. Finally, we observed that intestinal mucin MUC2 is expressed as the most prominent mucin of the mucins tested in mucinous-type gastric carcinomas.

Human and experimental toxicology of diquat poisoning: Toxicokinetics, mechanisms of toxicity, clinical features, and treatment

Diquat (1,1'-ethylene-2,2'-bipyridinium ion; DQ) is a nonselective quick-acting herbicide, which is used as contact and preharvest desiccant to control terrestrial and aquatic vegetation. Several cases of human poisoning were reported worldwide mainly due to intentional ingestion of the liquid formulations. Its toxic potential results from its ability to produce reactive oxygen and nitrogen species through redox cycling processes that can lead to oxidative stress and potentially cell death. Kidney is the main target organ due to DQ toxicokinetics and redox cycling. There is no antidote against DQ intoxications, and the efficacy of treatments currently applied is still unsatisfactory. The aim of this work was to review the most relevant human and experimental findings related to DQ, characterizing its chemistry, activity as herbicide, mechanisms of toxicity, consequences of poisoning, and potential therapeutic approaches taking into account previous experience in developing antidotes for paraquat, a more toxic bipyridinium herbicide.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

MUC1 gene polymorphism and gastric cancer--an epidemiological study

Gastric carcinoma is a major cause of cancer death worldwide and, like most human cancers, probably develops after environmental insults acting on normal individuals and/or individuals with increased genetic susceptibility. Mucins are attractive molecules to study the relationship between genetics and environment because they play an important role in the protection of gastric mucosa against environmental insults and exhibit a highly polymorphic genetic variation. We performed a case-control study using Southern blot analysis to evaluate the MUC1 gene polymorphism in a series of blood donors (n = 324) and in patients with gastric carcinoma (n = 159). We found that the distribution of MUC1 alleles is significantly different in the two populations and that small MUC1 alleles and small MUC1 genotypes are significantly more frequent in patients with gastric carcinoma than in controls. Individuals with small MUC1 genotypes are at increased risk for gastric carcinoma development.

Condições de trabalho e saúde dos professores da rede particular de ensino de Vitória da Conquista, Bahia, Brasil

A literatura científica sobre a saúde dos professores é escassa e recente, enfocando especialmente o desgaste e estresse. Este trabalho objetivou descrever as condições de trabalho e saúde dos professores da rede particular de ensino da cidade de Vitória da Conquista, Bahia, Brasil. Num questionário auto-aplicado foram coletadas informações de 250 professores de dez escolas. Entre as características do trabalho docente, avaliadas pelo Job Content Questionnaire, destacaram-se ritmo acelerado de trabalho, ser criativo e ter boas relações com as pessoas no trabalho. As queixas de saúde mais freqüentes estavam relacionadas à postura corporal, à saúde mental e a queixas relacionadas à voz. A prevalência de distúrbios psíquicos menores (DPM), medida pelo Self Reporting Questionnaire-20, foi de 41,5% e estava fortemente associada a longos períodos de intensa concentração em uma mesma tarefa e volume excessivo de trabalho. Os resultados sugerem relação entre a prevalência de DPM e algumas características do trabalho docente, evidenciando desgaste psicológico do educador.

Contribution of catecholamine reactive intermediates and oxidative stress to the pathologic features of heart diseases

Pathologic heart conditions, particularly heart failure (HF) and ischemia-reperfusion (I/R) injury, are characterized by sustained elevation of plasma and interstitial catecholamine levels, as well as by the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Despite the continuous and extensive research on catecholamines since the early years of the XX(th) century, the mechanisms underlying catecholamine-induced cardiotoxicity are still not fully elucidated. The role of catecholamines in HF, stress cardiomyopathy, I/R injury, ageing, stress, and pheochromocytoma will be thoroughly discussed. Furthermore and although the noxious effects resulting from catecholamine excess have traditionally been linked to adrenoceptors, in fact, several evidences indicate that oxidative stress and the oxidation of catecholamines can have important roles in catecholamine-induced cardiotoxicity. Accordingly, the reactive intermediates formed during catecholamine oxidation have been associated with cardiac toxicity, both in in vitro and in vivo studies. An insight into the influence of ROS, RNS, and catecholamine oxidation products on several heart diseases and their clinical course will be provided. In addition, the source and type of oxidant species formed in some heart pathologies will be referred. In this review a special focus will be given to the research of cardiac pathologies where catecholamines and oxidative stress are involved. An integrated vision of these matters is required and will be provided along this review, namely how the concomitant surge of catecholamines and ROS occurs and how they can be interconnected. The concomitant presence of these factors can elicit peculiar and not fully characterized responses on the heart. We will approach the existing data with new perspectives as they can help explaining several controversial results regarding cardiovascular diseases and the redox ability of catecholamines.

Heavy metals and DNA damage in blood cells of insectivore bats in coal mining areas of Catarinense coal basin, Brazil

We assessed the content of heavy metals in the liver and the DNA damage in blood cells of insectivore bats in the Catarinense Carboniferous Basin, Southern Brazil. Three bats species (Molossus molossus, Tadarida brasiliensis and Eptesicus diminutus) were collected in a coal mining area and in a control area. The heavy metal content in bats was detected according to the PIXE technique and the DNA damage was assessed by the Comet assay. The contents of Cr, Ni, Cu and Pb in M. molossus and of Cu and Fe in T. brasiliensis from the coal mining area was higher than in the animals from the control area. In both areas differences in metal contents in the liver were observed between the bat species. The parameters assessed by the Comet assay were significantly higher in E. diminutus as compared to M. molossus and T. brasiliensis. Values of both Comet assay parameters were significantly higher in the mining area as compared to the control area only for T. brasiliensis.

Acute toxicity of widely used pharmaceuticals in aquatic species: Gambusia holbrooki, Artemia parthenogenetica and Tetraselmis chuii

Pharmaceuticals are continuously dispersed into the environment as a result of human and veterinary use, posing relevant environmental concerns. This study evaluated the acute toxicity of three therapeutic agents (diazepam, clofibrate, and clofibric acid) and a detergent (sodium dodecyl sulfate; SDS) in three aquatic species, namely the euryhaline fish Gambusia holbrooki, the hypersaline crustacean Artemia parthenogenetica, and the marine algae Tetraselmis chuii. The ranking of 50% lethal concentrations (LC50) for the two animal species and 50% inhibitory concentration (IC50) for the algal species was, in decreasing order, clofibric acid > SDS > diazepam > clofibrate for G. holbrooki, clofibric acid > clofibrate > SDS > diazepam for A. parthenogenetica, and clofibric acid > clofibrate > SDS > diazepam for T. chuii. These differences show that the intrinsic nature of test organisms must be considered when evaluating the toxicity of these agents to aquatic ecosystems.

Neurotoxicity mechanisms of thioether ecstasy metabolites

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy"), is a widely abused, psychoactive recreational drug that is known to induce neurotoxic effects. Human and rat hepatic metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, which are both catechols that can undergo oxidation to the corresponding ortho-quinones. Ortho-quinones may be conjugated with glutathione (GSH) to form glutathionyl adducts, which can be transported into the brain and metabolized to the correspondent N-acetylcysteine (NAC) adducts. In this study we evaluated the neurotoxicity of nine MDMA metabolites, obtained by synthesis: N-Me-alpha-MeDA, alpha-MeDA and their correspondent GSH and NAC adducts. The studies were conducted in rat cortical neuronal cultures, for a 6 h of exposure period, under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings show that thioether MDMA metabolites are strong neurotoxins, significantly more than their correspondent parent catechols. On the other hand, N-Me-alpha-MeDA and alpha-MeDA are more neurotoxic than MDMA. GSH and NAC conjugates of N-Me-alpha-MeDA and alpha-MeDA induced a concentration dependent delayed neuronal death, accompanied by activation of caspase 3, which occurred earlier in hyperthermic conditions. Furthermore, thioether MDMA metabolites time-dependently increased the production of reactive species, concentration-dependently depleted intracellular GSH and increased protein bound quinones. Finally, thioether MDMA metabolites induced neuronal death and oxidative stress was prevented by NAC, an antioxidant and GSH precursor. This study provides new insights into the neurotoxicity mechanisms of thioether MDMA metabolites and highlights their importance in "ecstasy" neurotoxicity.

Behaviour and biomarkers of oxidative stress in Gambusia holbrooki after acute exposure to widely used pharmaceuticals and a detergent

Pharmaceuticals are continuously dispersed into the environment, as a result of human and veterinary use, and have become a relevant environmental concern. In the present study, the acute toxicity of three therapeutic agents (diazepam, clofibrate, and clofibric acid) and a detergent, sodium dodecylsulphate (SDS), to the euryhaline fish Gambusia holbrooki was evaluated. Special attention was devoted to oxidative stress parameters. G. holbrooki males, captured in the estuary of the Minho River (NW Portugal), were exposed for 96 h to the selected compounds. The following oxidative stress biomarkers were evaluated in gills and liver tissues: reduced and oxidised glutathione, lipid peroxidation, and several antioxidant enzymes, namely (1) total and selenium-dependent glutathione peroxidase (GPx), (2) glutathione reductase (GRed), (3) copper-zinc superoxide dismutase (Cu-ZnSOD) and manganese superoxide dismutase (MnSOD), and (4) glutathione-S-transferases (GSTs). In the particular case of diazepam, swimming behaviour was also evaluated. The obtained results indicate an overall diminished oxidative stress response caused by SDS and diazepam. Oxidative-based alterations were observed after exposure to clofibrate and clofibric acid, with modifications of several enzymatic activities. Diazepam caused evident behavioural changes: animals showed dark pigmentation and also abnormal postures, namely lethargy and anomalous movement.

Immune sensing of food allergens promotes avoidance behaviour

In addition to its canonical function of protection from pathogens, the immune system can also alter behaviour1,2. The scope and mechanisms of behavioural modifications by the immune system are not yet well understood. Here, using mouse models of food allergy, we show that allergic sensitization drives antigen-specific avoidance behaviour. Allergen ingestion activates brain areas involved in the response to aversive stimuli, including the nucleus of tractus solitarius, parabrachial nucleus and central amygdala. Allergen avoidance requires immunoglobulin E (IgE) antibodies and mast cells but precedes the development of gut allergic inflammation. The ability of allergen-specific IgE and mast cells to promote avoidance requires cysteinyl leukotrienes and growth and differentiation factor 15. Finally, a comparison of C57BL/6 and BALB/c mouse strains revealed a strong effect of the genetic background on the avoidance behaviour. These findings thus point to antigen-specific behavioural modifications that probably evolved to promote niche selection to avoid unfavourable environments.

P-glycoprotein induction: an antidotal pathway for paraquat-induced lung toxicity

The widespread use of the nonselective contact herbicide paraquat (PQ) has been the cause of thousands of deaths from both accidental and voluntary ingestion. The main target organ for PQ toxicity is the lung. No antidote or effective treatment to decrease PQ accumulation in the lung or to disrupt its toxicity has yet been developed. The present study describes a procedure that leads to a remarkable decrease in PQ accumulation in the lung, together with an increase in its fecal excretion and a subsequent decrease in several biochemical and histopathological biomarkers of toxicity. The administration of dexamethasone (100 mg/kg ip) to Wistar rats, 2 h after PQ intoxication (25 mg/kg ip), decreased the lung PQ accumulation to about 40% of the group exposed to only PQ and led to an improvement in tissue healing in just 24 h as a result of the induction of de novo synthesis of P-glycoprotein (P-gp). The involvement of P-gp in these effects was confirmed by Western blot analysis and by the use of a competitive inhibitor of this transporter, verapamil (10 mg/kg ip), which, given 1 h before dexamethasone, blocked its protective effects, causing instead an increase in lung PQ concentration and an aggravation of toxicity. In conclusion, the induction of P-gp, leading to a decrease in lung levels of PQ and the consequent prevention of toxicity, seems to be a new and promising treatment for PQ poisonings that should be further clinically tested.

Full survival of paraquat-exposed rats after treatment with sodium salicylate

Over the past decades, there have been numerous fatalities resulting from accidental or voluntary ingestion of the widely used herbicide paraquat dichloride (methyl viologen; PQ). Considering that the main target organ for PQ toxicity is the lung and involves the production of reactive oxygen and nitrogen species, inflammation, disseminated intravascular coagulation, and activation of transcriptional regulatory mechanisms, it may be hypothesized that an antidote against PQ poisonings should counteract all these effects. For this purpose, sodium salicylate (NaSAL) may constitute an adequate therapeutic drug, due to its ability to modulate inflammatory signaling systems and to prevent oxidative stress. To test this hypothesis, NaSAL (200 mg/kg ip) was injected in rats 2 h after exposure to a toxic dose of PQ (25 mg/kg, ip). NaSAL treatment caused a significant reduction in PQ-induced oxidative stress, platelet activation, and nuclear factor (NF)-kappaB activation in lung. In addition, histopathological lesions induced by PQ in lung were strongly attenuated and the oxidant-induced increases of glutathione peroxidase and catalase expression became absent. These effects were associated with a full survival of the PQ-treated rats (extended for more than 30 days) in comparison with 100% of mortality by Day 6 in animals exposed only to PQ, suggesting that NaSAL constitutes an important and valuable therapeutic drug to be used against PQ-induced toxicity. Indeed, NaSAL constitutes the first compound with such degree of success (100% survival).

Endothelium-derived oxidative stress may contribute to exercise-induced muscle damage

In exercise-induced muscle damage, oxidative stress derived from the liberation of reactive oxygen species (ROS) is assumed to be of etiological importance. Xanthine oxidase (XO) located in capillary endothelium is one of the possible sources for ROS, mainly investigated so far under conditions of ischemia/reperfusion. XO can be inhibited by allopurinol. To investigate the contribution of XO for the oxidative stress-induced development of muscle damage, mice were subjected to a single bout of exhaustive running exercise. Another exercised group received allopurinol. The reduced form of glutathione (GSH) was measured to estimate the amount of oxidative stress in soleus muscle, and the same muscle was examined in the light and electron microscope at different periods of time (0, 48, 96 h) after exercise. While exercise alone resulted in a marked reduction of GSH indicative for oxidative stress, which only recovered at 96 h, the administration of allopurinal to exercised animals induced a complete recovery already at 48 h after exercise. Muscle damage was more pronounced in the exercised animals which had not been treated with allopurinol. It is concluded that endothelium-derived ROS contribute reasonably to oxidative stress to exercised muscle and to fiber and capillary damage.

Acetyl-L-carnitine provides effective in vivo neuroprotection over 3,4-methylenedioximethamphetamine-induced mitochondrial neurotoxicity in the adolescent rat brain

3,4-Methylenedioximethamphetamine (MDMA, ecstasy) is a worldwide abused stimulant drug, with persistent neurotoxic effects and high prevalence among adolescents. The massive release of 5-HT from pre-synaptic storage vesicles induced by MDMA followed by monoamine oxidase B (MAO-B) metabolism, significantly increases oxidative stress at the mitochondrial level. l-Carnitine and its ester, acetyl-l-carnitine (ALC), facilitate the transport of long chain free fatty acids across the mitochondrial membrane enhancing neuronal anti-oxidative defense. Here, we show the potential of ALC against the neurotoxic effects of MDMA exposure. Adolescent male Wistar rats were assigned to four groups: control saline solution, isovolumetric to the MDMA solution, administered i.p.; MDMA (4x10 mg/kg MDMA, i.p.); ALC/MDMA (100 mg/kg 30 min of ALC prior to MDMA, i.p.) and ALC (100 mg/kg, i.p.). Rats were killed 2 weeks after exposure and brains were analyzed for lipid peroxidation, carbonyl formation, mitochondrial DNA (mtDNA) deletion and altered expression of the DNA-encoded subunits of the mitochondrial complexes I (NADH dehydrogenase, NDII) and IV (cytochrome c oxidase, COXI) from the respiratory chain. Levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) were also assessed. The present work is the first to successfully demonstrate that pretreatment with ALC exerts effective neuroprotection against the MDMA-induced neurotoxicity at the mitochondrial level, reducing carbonyl formation, decreasing mtDNA deletion, improving the expression of the respiratory chain components and preventing the decrease of 5-HT levels in several regions of the rat brain. These results indicate potential benefits of ALC application in the prevention and treatment of neurodegenerative disorders.

Ecstasy-induced cell death in cortical neuronal cultures is serotonin 2A-receptor-dependent and potentiated under hyperthermia

Studies on 3,4-methylenedioxymethamphetamine ("ecstasy")-induced neurotoxicity mainly focus on damage of serotonergic terminals. Less attention has been given to neuronal cell death produced by 3,4-methylenedioxymethamphetamine and other amphetamines in areas including the cortex, striatum and thalamus. In the present study we investigated 3,4-methylenedioxymethamphetamine-induced neurotoxicity in neuronal serum free cultures from rat cortex. Since 3,4-methylenedioxymethamphetamine intake induces hyperthermia in both animals and humans, the experiments were performed under normal (36.5 degrees C) and hyperthermic conditions (40 degrees C). Our findings showed a dose-, time- and temperature-dependent apoptotic cell death induced by 3,4-methylenedioxymethamphetamine in cortical neurons. 3,4-Methylenedioxymethamphetamine-induced damage was potentiated under hyperthermia. The neurotoxicity was reduced by the serotonin 2A-receptor antagonists, ketanserin and (2R,4R)-5-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxy]ethyl]-1-methyl-3-pyrrolidinol hydrochloride, in both normothermic and hyperthermic conditions. (+/-)-2,5-Dimethoxy-4-iodoamphetamine hydrochloride, a model agonist for the serotonin 2A-receptor, also induced a dose- and time-dependent apoptotic cell death. Again, protection was provided by ketanserin and (2R,4R)-5-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxy]ethyl]-1-methyl-3-pyrrolidinol hydrochloride against (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride-induced neurotoxicity, thereby indicating that the 3,4-methylenedioxymethamphetamine stimulation of the serotonin 2A-receptor leads to neurotoxicity. This study provides for the first time evidence that direct 3,4-methylenedioxymethamphetamine serotonin 2A-receptor stimulation leads to neuronal cortical death. alpha-Phenyl-N-tert-butyl nitrone a free radical scavenger and the nitric oxide synthase inhibitor Nomega-nitro-L-arginine as well as the NMDA-receptor antagonist MK-801 provided protection under normothermia and hyperthermia, thereby suggesting the participation of free radicals in 3,4-methylenedioxymethamphetamine-induced cell death. Since 3,4-methylenedioxymethamphetamine serotonin 2A-receptor agonistic properties lead to neuronal death, clinically available atypical antipsychotic drugs with serotonin 2A-antagonistic properties could be a valuable therapeutic tool against 3,4-methylenedioxymethamphetamine-induced neurodegeneration.

Body mass index and waist circumference in non-alcoholic fatty liver disease

OBJECTIVE

To evaluate the association of anthropometric indexes (body mass index and waist circumference) in patients with non-alcoholic fatty liver disease (NAFLD), and its association with insulin resistance (IR), metabolic syndrome (MS) and histological findings.

METHODS

From August 2003 to July 2004 a case series of 81 outpatients with clinic and/or histological diagnosis of NAFLD were selected at the Bahia University Gastro-Hepatology Clinic, Brazil. Liver function tests, lipid profile, glucose and insulin were performed in all patients. Body mass index (BMI) and waist circumference (WC) were determined according to WHO criteria. IR was measured by means of the homeostasis model assessment (HOMA) and IR was considered with HOMA > or =3. MS was defined according to the Adult Treatment Panel III (ATP III). Liver biopsy was performed in 37 cases.

RESULTS

Body mass index > or = 30 kg m(-2) (obesity) was found in 39% of the cases and BMI > or = 25-29.9 kg m(-2) (overweight) in 53%. BMI was correlated with IR (r = 0.29; P = 0.02) and WC with ALT (r = 0.02; P = 0.03). Increased WC also was related to IR and to MS. The presence of steatohepatitis with fibrosis on liver biopsy was associated with overweight (68%) and increase of WC (41%).

CONCLUSIONS

Body mass index and WC are frequent associated with MS, IR and histological findings (steatohepatitis and fibrosis) in patients with NAFLD.