Occupational exposure to aflatoxin B1: the case of poultry and swine production

Although there is an abundance of literature concerning the ingestion of food contaminated with aflatoxin B1 (AFB1), only a small number of studies explore mycotoxin exposure in occupational settings. Taking this into consideration, our study was developed with the intention of elucidating whether there is occupational exposure to AFB1 in Portuguese poultry and swine production facilities. A specific biomarker was used to assess exposure to AFB1. A total of 45 workers (34 from poultry farms; 11 from swine production facilities) participated in this study, providing blood samples. Additionally, a control group (n=30) composed of subjects without any type of contact with agricultural activity was considered. All participants signed a consent form and were provided with the study protocol. Eighteen poultry workers (58.6%) and six workers from the swine production facilities (54.5%) showed detectable levels of AFB1. In the control group, the AFB1 values were all below 1 ng/ml. No significant differences in AFB1 levels in serum between workers from poultry and swine farms were found. Poultry workers, however, showed the highest serum levels and a significant statistical difference between this group and the control group was found. Results suggest that exposure to AFB1 by inhalation occurs in both occupational settings representing an additional risk that needs to be recognised, assessed and prevented.

Occupational exposure to Aflatoxin B1 in Portuguese swine farms

In 1987, the International Agency for Research on Cancer concluded that there was sufficient evidence for carcinogenicity of naturally occurring aflatoxins in humans. Regarding occupational exposure to this chemical agent, farmers and other agricultural workers present a higher risk due to airborne aflatoxin via inhalation of dust. This study was carried out in 7 swine farms located at the district of Lisbon, Portugal. Blood samples were collected from a total of 11 workers. In addition, a control group (n = 25) was included that conducted administrative tasks in an educational institution without any type of agricultural activity. Results obtained suggest that occupational exposure to AFB1 by inhalation occurs and represents an additional risk in this occupational setting that need to be recognized, assessed and, most important, prevented.

Potential poultry and meat products contamination by aflatoxin B1 due to fungal presence in Portuguese poultry units

The impact of mycotoxins on human and animal health is well recognized. Aflatoxin B1 (AFB1) is by far the most prevalent and the most potent natural carcinogen and is usually the major aflatoxin produced by toxigenic fungal strains. Data available, points to an increasing frequency of poultry feed contamination by aflatoxins. Since aflatoxin residues may accumulate in body tissues, this represents a high risk to human health. Samples from commercial poultry birds have already presented detectable levels of aflatoxin in liver. A descriptive study was developed in order to assess fungal contamination by species from Aspergillus flavus complex in seven Portuguese poultry units. Air fungal contamination was studied by conventional and molecular methods. Air, litter and surfaces samples were collected. To apply molecular methods, air samples of 300L were collected using the Coriolis μ air sampler (Bertin Technologies), at 300 L/min airflow rate. For conventional methodologies, all the collected samples were incubated at 27ºC for five to seven days. Through conventional methods, Aspergillus flavus was the third fungal species (7%) most frequently found in 27 indoor air samples analysed and the most commonly isolated species (75%) in air samples containing only the Aspergillus genus...

Assessment of workers’ exposure to Aflatoxin B1 in a Portuguese waste industry

Aflatoxin B1 (AFB1) is considered by different International Agencies as a genotoxic and potent hepatocarcinogen. However, despite the fact that the fungi producing this compound are detected in some work environments, AFB1 is rarely monitored in occupational settings. The aim of the present investigation was to assess exposure to AFB1 of workers from one Portuguese waste company located in the outskirt of Lisbon. Occupational exposure assessment to AFB1 was done with a biomarker of internal dose that measures AFB1 in the serum by enzyme-linked immunosorbent assay. Forty-one workers from the waste company were enrolled in this study (26 from sorting; 9 from composting; 6 from incineration). A control group (n = 30) was also considered in order to know the AFB1 background levels for the Portuguese population. All the workers showed detectable levels of AFB1 with values ranging from 2.5ng ml−1 to 25.9ng ml−1 with a median value of 9.9±5.4ng ml−1. All of the controls showed values below the method’s detection limit. Results obtained showed much higher (8-fold higher) values when compared with other Portuguese settings already studied, such as poultry and swine production. Besides this mycotoxin, other mycotoxins are probably present in this occupational setting and this aspect should be taken into consideration for the risk assessment process due to possible synergistic reactions. The data obtained suggests that exposure to AFB1 occurs in a waste management setting and claims attention for the need of appliance of preventive and protective safety measures.

Occupational exposure to aflatoxin B1 and ochratoxin A: co-exposure in swine production

The most common scenario in occupational settings is the co-exposure to several risk factors. This aspect has to be considered in the risk assessment process because can alter the toxicity and the health effects when dealing with a co-exposure to two or more chemical agents. A study was developed aiming to elucidate if there is occupational co-exposure to aflatoxin B1 (AFB1) and ochratoxin (OTA) in Portuguese swine production. To assess occupational exposure to both mycotoxins, a biomarker of internal dose was used. The same blood samples from workers of seven swine farms and controls were consider to measure AFB1 and OTA. Twenty one workers (75%) showed detectable levels of AFB1 with values ranging from <1 ng/ml to 8.94 ng/ml and with significantly higher concentration when compared with controls. In the case of OTA, there wasn't found a statistical difference between workers and controls and the values for workers group ranged from 0.34 ng/ml to 3.12 ng/ml and 1.76 ng/ml to 3.42 ng/ml for control group. The results suggest that occupational exposure to AFB1 occurs. However, in the case of OTA results, seems that food consumption plays an important role in both groups exposure. The results claim attention for the possible implications on health of this co-exposure.

Occupational exposure to aflatoxin B1: new (old) occupational risk!

Contrary to fungi, exposure to mycotoxins is not usually identified as a risk factor present in occupational settings. This is probably due to the inexistence of limits regarding concentration of airborne mycotoxins, and also due to the fact that these compounds are rarely monitored in occupational environments. Aflatoxin B1 (AFB1) is the most prevalent aflatoxin and is associated with carcinogenicity, teratogenicity, genotoxicity and immunotoxicity but only a few studies examined exposure in occupational settings. Workers can be exposed to high airborne levels during certain operations in specific occupational settings. Aim of study: The study aimed to assess exposure to AFB1 in three settings: poultry, swine production and waste management.

Heart rate responses to a muscarinic agonist in rats with experimentally induced acute and subacute chagasic myocarditis

We administered arecoline to rats, with experimentally induced chagasic myocarditis, in order to study the sinus node sensitivity to a muscarinic agonist. Sixteen month old rats were inoculated with 200,000 T. cruzi parasites ("Y" strain). Between days 18 and 21 (acute stage), 8 infected rats and 8 age-matched controls received intravenous arecoline as a bolus injection at the following doses: 5.0, 10.0, 20.0, 40.0, and 80.0 mug/kg. Heart rate was recorded before, during and after each dose of arecoline. The remaining 8 infected animals and 8 controls were subjected to the same experimental procedure during the subacute stage, i.e., days 60 to 70 after inoculation. The baseline heart rate, of the animals studied during the acute stage (349 ± 68 bpm, mean ± SD), was higher than that of the controls (250 ± 50 bpm, p < 0.005). The heart rate changes were expressed as percentage changes over baseline values. A dose-response curve was constructed for each group of animals. Log scales were used to plot the systematically doubled doses of arecoline and the induced-heart rate changes. The slope of the regression line for the acutely infected animals (r = - 0.99, b =1.78) was not different from that for the control animals (r = - 0.97, b = 1.61). The infected animals studied during the subacute stage (r = - 0.99, b = 1.81) were also not different from the age-matched controls (r = - 0.99, b = 1.26, NS). Consequently, our results show no pharmacological evidence of postjunctional hypersensitivity to the muscarinic agonist arecoline. Therefore, these results indirectly suggest that the postganglionic parasympathetic innervation, of the sinus node of rats with autopsy proved chagasic myocarditis, is not irreversibly damaged by Trypanosoma cruzi.

Stress induced risk-aversion is reverted by D2/D3 agonist in the rat

Stress exposure triggers cognitive and behavioral impairments that influence decision-making processes. Decisions under a context of uncertainty require complex reward-prediction processes that are known to be mediated by the mesocorticolimbic dopamine (DA) system in brain areas sensitive to the deleterious effects of chronic stress, in particular the orbitofrontal cortex (OFC). Using a decision-making task, we show that chronic stress biases risk-based decision-making to safer behaviors. This decision-making pattern is associated with an increased activation of the lateral part of the OFC and with morphological changes in pyramidal neurons specifically recruited by this task. Additionally, stress exposure induces a hypodopaminergic status accompanied by increased mRNA levels of the dopamine receptor type 2 (Drd2) in the OFC; importantly, treatment with a D2/D3 agonist quinpirole reverts the shift to safer behaviors induced by stress on risky decision-making. These results suggest that the brain mechanisms related to risk-based decision-making are altered after chronic stress, but can be modulated by manipulation of dopaminergic transmission.

Efeitos do carvedilol (bloqueador b1,b2,a1) na insuficiência cardíaca refratária

OBJETIVO: Os efeitos dos beta-bloqueadores na insuficiência cardíaca (IC) refratária não têm sido adequadamente estudados. Investigamos os efeitos do carvedilol (bloqueador b1,b2,a1) nos sintomas e na função ventricular de portadores de IC refratária. MÉTODOS: Foram estudados 21 pacientes, idade média de 56±10 anos, 9 em classe funcional (CF) IV, e 12 em CF III intermitente com IV. A dose inicial de carvedilol foi de 6,25mg e, se tolerada, aumentada progressivamente. A dose média final foi 42±11mg. Os pacientes foram submetidos a avaliações clínicas e eletrocardiográficas seriadas. Realizaram-se, antes e com 196±60 dias de evolução, ecocardiograma e ventriculografia radioisotópica. RESULTADOS: O medicamento foi tolerado em 16 (76%) pacientes. Um paciente está em fase de titulação em CF II. Com 196±60 dias de evolução observaram-se 8 pacientes em CF I e 7 em II; redução da freqüência cardíaca de 96±15 para 67±10bpm (p<0,0001); redução do diâmetro diastólico final de ventrículo esquerdo (VE) de 73±13 para 66±12mm (ecocardiograma) (p<0,009); e aumento da fração de ejeção de VE de 0,21±0,06 para 0,34±0,12 (p<0,0003). CONCLUSÃO: O carvedilol devido aos seus efeitos benéficos na função ventricular, remodelamento e CF é, se tolerado, uma potencial alternativa terapêutica no tratamento medicamentoso da IC refratária. Entretanto, estudos adicionais são necessários para definição do efeito a longo prazo neste específico subgrupo de pacientes.

Simultaneous detection of cyclopiazonic acid and aflatoxin B1 by HPLC in methanol/water mobile phase

A simple procedure for the simultaneous detection of cyclopiazonic acid (CPA) and aflatoxin B1 from fungal extracts is presented, using a methanol and water mobile phase and fluorescence detection. This methodology has been tested with standard solutions of both mycotoxins CPA and Aflatoxin B1 and with methanolic extracts of Aspergillus section Flavi strains, previously characterized for their mycotoxin production profile. Previously available methodology required the use of two different chromatographic runs for these mycotoxins, with distinct columns and detectors (fluorescence detection with a post-column photochemical derivatization (PHRED) for aflatoxin B1 and UV detection for CPA). The proposed method detects both mycotoxins in a single run. Data from these assays will be presented and discussed.

Detección de genotixicidad en cerdos inducida por la ingesta de Aflatoxina B1

En cerdos la micotoxicosis representa uno de los problemas de contaminación ambiental más frecuente. La aflatoxina B1 (AFB1) producida por ciertas cepas de A. flavus y A. parasiticus, es un agente genotóxico, ya que al ingerir alimento contaminado, los metabolitos de AFB1 inducen daño cromosómico. En función de este problema se plantean las siguientes hipótesis de trabajo: 1. La ingesta de alimentos contaminados con AFB1 inducen daño cromosómico en cerdos. 2. La inducción, frecuencia y tipo de daño cromosómico es dependiente del tiempo de ingesta de AFB1. En este trabajo se evalúa el potencial genotóxico in vivo de la AFB1, mediante tres métodos distintos: Análisis de aberraciones cromosómicas, Ensayo de micronúcleos y Electroforesis en gel de células individuales. Se evaluarán dos grupos de cerdos en etapa postdestete, uno control y otro alimentado con pienso ad líbitum, con AFB1 a una determinada concentración. Se tomarán muestras de sangre a los 15, 30, 45 y 60 días. En concordancia con los antecedentes bibliográficos, se espera detectar la ocurrencia de daño cromosómico inducido por la ingesta de AFB1 a una determinada dosis. El efecto genotóxico debería ser detectado desde las tres técnicas elegidas para su estudio. Se espera poder establecer el tipo preponderante de daño inducido por la ingesta de AFB1 en cerdos posdestete, la sensibilidad de las diferentes técnicas empleadas para su detección y determinar si existe relación entre el tipo e intensidad de daño cromosómico y el tiempo de ingesta de AFB1. En virtud que Río Cuarto y la región es una zona agrícola-ganadera, donde la explotación porcina es de interés económico y la ocurrencia reiterada de brotes de micotoxicosis, plantea la necesidad de evaluar el potencial genotóxico de las micotoxinas. Considerando que gran parte de la información publicada sobre la toxicidad se refiere a estudios en animales experimentales de laboratorio, que pueden no reflejar sus efectos en seres humanos y en animales de granja, se considera relevante evaluar la toxicidad, particularmente la genotoxicidad en animales a campo y sus posibles consecuencias para la salud y producción porcina. El abordaje de la evaluación del daño genotóxico inducido por AFB1 desde tres ensayos distintos permitirá establecer cuál de éstos métodos reúne las condiciones más ventajosas en cuento a: sensibilidad, tiempo requerido, validez estadística, sencillez y economía, para ser el método de elección en posteriores estudios.

Seletividade de avermectin-B1 (MK-936) ao Trichogramma demoraesi Nagaraja, 1983 (Hym. , Trichogrammatidae), em condições de laboratório

Foi conduzido um estudo, em condições de laboratório, para se determinar alguns parâmetros relativos à seletividade de avermectin-B1 (MK-936) ao Trichogramma demoraesi Nagajara, 1983 (Hym., Trichogrammatidae), parasito de ovos de diversas espécies de pragas agrícolas. Observou-se que o produto na formulação 1,8% CE, nas dosagens de 0,1; 0,2; 0,4 e 0,8 ml/l não afetava o desenvolvimento pré-marginal do parasito, quando este ainda se encontrava no interior dos ovos parasitados. O mesmo fato foi observado quando se utilizaram dosagens extremamente elevadas, da ordem de 8,0 ml/l. Não ocorreu, também, mortalidade significativa de adultos do parasito que ovipositaram em ovos de Anagasta kuehniella (Zeller, 1879) (Lep., Pyralidade) previamente tratados com o inseticida. A ação de contacto de avermectin-B1, quando aplicada nas paredes internas dos frascos de criação, não ficou evidenciada, pela dificuldade de se discriminar seus efeitos dos da acetona usada como solvente e que, mesmo aplica da sozinha, acarretou uma mortalidade significativa de adultos. Este fato pode estar associado aos 0,001% de resíduos não voláteis do solvente em questão, embora se tornem necessários estudos mais detalhados para se verificar esta hipótese. Malathion na dosagem de 1,5 ml/l apresentou-se extremamente tóxico para T. demoraesi em todos os estudos realizados. Concluiu-se que avermectin-B1 apresenta características de seletividade para esta espécie, com potencialidade de utilização em programas de controle integrado de pragas, em locais onde sobrevivam populações nativas ou introduzidas deste parasito.

Inhibition of glial cell proinflammatory activities by peroxisome proliferator-activated receptor gamma agonist confers partial protection during antimyelin oligodendrocyte glycoprotein demyelination in vitro.

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a member of the nuclear hormone superfamily originally characterized as a regulator of adipocyte differentiation and lipid metabolism. In addition, PPAR-gamma has important immunomodulatory functions. If the effect of PPAR-gamma's activation in T-cell-mediated demyelination has been recently demonstrated, nothing is known about the role of PPAR-gamma in antibody-induced demyelination in the absence of T-cell interactions and monocyte/macrophage activation. Therefore, we investigated PPAR-gamma's involvement by using an in vitro model of inflammatory demyelination in three-dimensional aggregating rat brain cell cultures. We found that PPAR-gamma was not constitutively expressed in these cultures but was strongly up-regulated following demyelination mediated by antibodies directed against myelin oligodendrocyte glycoprotein (MOG) in the presence of complement. Pioglitazone, a selective PPAR-gamma agonist, partially protected aggregates from anti-MOG demyelination. Heat shock responses and the expression of the proinflammatory cytokine tumor necrosis factor-alpha were diminished by pioglitazone treatment. Therefore, pioglitazone protection seems to be linked to an inhibition of glial cell proinflammatory activities following anti-MOG induced demyelination. We show that PPAR-gamma agonists act not only on T cells but also on antibody-mediated demyelination. This may represent a significant benefit in treating multiple sclerosis patients.

Truncation of the receptor carboxyl terminus impairs agonist-dependent phosphorylation and desensitization of the alpha 1B-adrenergic receptor.

The alpha 1B-adrenergic receptor (alpha 1BAR) and its truncated mutant T368 lacking the last 147 amino acids were stably expressed in Rat1 fibroblasts. The wild type alpha 1BAR was rapidly phosphorylated upon exposure to the agonist epinephrine as well as to phorbol ester as assessed by immunoprecipitation of the receptor with antiserum raised against its amino-terminal portion. Exposure of cells expressing the wild type alpha 1BAR to epinephrine resulted also in rapid homologous desensitization of receptor-mediated response on polyphosphoinositide hydrolysis. On the other hand, truncation of the serine- and threonine-rich carboxyl portion of the alpha 1BAR abolished agonist-induced phosphorylation and greatly impaired homologous desensitization of the receptor. The truncated receptor T368 could undergo agonist-induced decrease of cell surface receptors but to a lesser extent, as compared with the wild type alpha 1BAR. These results demonstrate that the carboxyl portion of the alpha 1BAR plays a crucial role in the regulation of receptor function. They also suggest a strong relationship between agonist-induced phosphorylation and desensitization of the alpha 1BAR, which were both insensitive to the inhibitor of protein kinase C RO-318220. Our findings support the emerging hypothesis that the biochemical mechanisms involved in rapid agonist-dependent regulation of G protein-coupled receptors, which activate polyphosphoinositide hydrolysis, do not primarily involve protein kinase C.

Effects of the α₂-adrenergic agonist clonidine on the pharmacodynamics and pharmacokinetics of 3,4-methylenedioxymethamphetamine in healthy volunteers.

The mechanism of action of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) involves the carrier-mediated and potentially vesicular release of monoamines. We assessed the effects of the sympatholytic α₂-adrenergic receptor agonist clonidine (150 μg p.o.), which inhibits the neuronal vesicular release of norepinephrine, on the cardiovascular and psychotropic response to MDMA (125 mg p.o.) in 16 healthy subjects. The study used a randomized, double-blind, placebo-controlled crossover design with four experimental sessions. The administration of clonidine 1 h before MDMA reduced the MDMA-induced increases in plasma norepinephrine concentrations and blood pressure but only to the extent that clonidine lowered norepinephrine levels and blood pressure compared with placebo. Thus, no interaction was found between the cardiovascular effects of the two drugs. Clonidine did not affect the psychotropic effects or pharmacokinetics of MDMA. The lack of an interaction of the effects of clonidine and MDMA indicates that vesicular release of norepinephrine, which is inhibited by clonidine, does not critically contribute to the effects of MDMA in humans. Although clonidine may be used in the treatment of stimulant-induced hypertensive reactions, the present findings do not support a role for α₂-adrenergic receptor agonists in the prevention of psychostimulant dependence.