Toxicity of carcinogenic and non-carcinogenic Polycyclic Aromatic Hydrocarbons and their mixtures to aquatic organisms under ecologically-relevant scenarios

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous priority pollutants that tend to be trapped in aquatic sediments due to their high hydrophobicity. Nonetheless, the differential toxicological effects and mechanisms between the various classes of PAHs and their mixtures, as they invariably occur in the environment, are scarcely known, especially under ecologically-relevant scenarios. This thesis aimed at establishing a bridge between the study of mechanistic pathways and environmental monitoring of carcinogenic and non-carcinogenic PAHs, by introducing ecological-relevance in the research with model PAHs. A first bioassay conducted in situ with the mussel Mytilus edulis demonstrated that, dredging operations in harbours increase PAH bioavailability, eliciting genotoxicity, and showed that established environmental guidelines underestimate risk. Subsequent ex situ bioassays were performed with the carcinogenic benzo[b]fluoranthene (B[b]F) and non-carcinogenic phenantrene (Phe), selected following preceding results, and revealed that low-moderate concentrations of these PAHs in spiked sediments induce genotoxic effects to the clam Ruditapes decussatus, therefore contradicting the general notion that bivalves are less sensitive to PAHs than vertebrates due to inefficient bioactivation. Also, it was demonstrated that passive samplers permit inferring on PAH bioavailability but not on bioaccumulation or toxic effects. On the other hand, sea basses (Dicentrarchus labrax), yielded a complex pattern of effects and responses, relatively to genotoxicity, oxidative stress and production of specific metabolites, especially when exposed to mixtures of the PAHs which led to additive, if not synergistic, effects. It was shown that Phe may elicit significant genotoxicity especially in presence of B[b]F, even though the low, albeit realistic, exposure concentrations diluted dose- and time-independent relationships. The present work demonstrated that environmental quality guidelines underestimate the effects of PAHs in realistic scenarios and showed that the significant genotoxic and histopathological effects caused by mixed PAHs may not be reflected by oxidative stress- or CYP-related biomarkers. Besides important findings on the metabolism of PAH mixtures, the work calls for the need to re-evaluate the criteria for assessing risk and for the disclosure of more efficient indicators of toxicological hazard.

The computational role of short-term plasticity and the balance of excitation and inhibition in neural microcircuits: experimental and theoretical analysis

The computations performed by the brain ultimately rely on the functional connectivity between neurons embedded in complex networks. It is well known that the neuronal connections, the synapses, are plastic, i.e. the contribution of each presynaptic neuron to the firing of a postsynaptic neuron can be independently adjusted. The modulation of effective synaptic strength can occur on time scales that range from tens or hundreds of milliseconds, to tens of minutes or hours, to days, and may involve pre- and/or post-synaptic modifications. The collection of these mechanisms is generally believed to underlie learning and memory and, hence, it is fundamental to understand their consequences in the behavior of neurons.(...)

Can the complex mixture of sediment contaminants cause endocrine disruption on a benthic fish? A case study with Solea senegalensis

Pollution in coastal ecosystems is a serious threat to the biota and human populations there residing. Anthropogenic activities in these ecosystems are the main cause of contamination by endocrine disruption compounds (EDCs), which can interfere with hormonal regulation and cause adverse effects to growth, stress response and reproduction. Although the chemical nature of many EDCs is unknown, it is believed that most are organic contaminants. Under an environmental risk assessment for a contaminated estuary (the Sado, SW Portugal), the present work intended to detect endocrine disruption in a flatsfish, Solea senegalensis Kaup, 1858, and its potential relationship to organic toxicants. Animals were collected from two areas in the estuary with distinct influences (industrial and rural) and from an external reference area. To evaluate endocrine disruption, hepatic vitellogenin (VTG) concentrations in males and gonad histology were analysed. As biomarkers of exposure to organic contaminants, cytochrome P450 (CYP1A) induction and the ethoxyresorufin-O-deethylase (EROD) activity were determined. The results were contrasted to sediment contamination levels, which are overall considered low, although the area presents a complex mixture of toxicants. Either males or females were found sexually immature and showed no significant evidence of degenerative pathologies. However, hepatic VTG concentrations in males from the industrial area in estuary were superior than those from the Reference, even reaching levels comparable to those in females, which may indicate an oestrogenic effect resulting from the complex contaminant mixture. These individuals also presented higher levels of CYP1A induction and EROD activity, which is consistent with contamination by organic substances. The combination of the results suggest that the exposure of flatfish to an environment contaminated by mixed toxicants, even at low levels, may cause endocrine disruption, therefore affecting populations, which implies the need for further research in identification of potential EDCs, their sources and risks at ecosystem scale.

Evaluation of uv spectrophotometry for estimation of nitrite and nitrate in nitrified urine

Water is a limited resource for which demand is growing. Contaminated water from inadequate wastewater treatment provides one of the greatest health challenges as it restricts development and increases poverty in emerging and developing countries. Therefore, the connection between wastewater and human health is linked to access to sanitation and to human waste disposal. Adequate sanitation is expected to create a barrier between disposed human excreta and sources of drinking water. Different approaches to wastewater management are required for different geographical regions and different stages of economic governance depending on the capacity to manage wastewater. Effective wastewater management can contribute to overcome the challenges of water scarcity. Separate collection of human urine at its source is one promising approach that strongly reduces the economic and load demands on wastewater treatment plants (WWTP). Treatment of source-separated urine appears as a sanitation system that is affordable, produces a valuable fertiliser, reduces pollution of water resources and promotes health. However, the technical realisation of urine separation still faces challenges. Biological hydrolysis of urea causes a strong increase of ammonia and pH. Under these conditions ammonia volatilises which can cause odour problems and significant nitrogen losses. The above problems can be avoided by urine stabilisation. Biological nitrification is a suitable process for stabilisation of urine. Urine is a highly concentrated nutrient solution which can lead to strong inhibition effects during bacterial nitrification. This can further lead to process instabilities. The major cause of instability is accumulation of the inhibitory intermediate compound nitrite, which could lead to process breakdown. Enhanced on-line nitrite monitoring can be applied in biological source-separated urine nitrification reactors as a sustainable and efficient way to improve the reactor performance, avoiding reactor failures and eventual loss of biological activity. Spectrophotometry appears as a promising candidate for the development and application of on-line nitrite monitoring. Spectroscopic methods together with chemometrics are presented in this work as a powerful tool for estimation of nitrite concentrations. Principal component regression (PCR) is applied for the estimation of nitrite concentrations using an immersible UV sensor and off-line spectra acquisition. The effect of particles and the effect of saturation, respectively, on the UV absorbance spectra are investigated. The analysis allows to conclude that (i) saturation has a substantial effect on nitrite estimation; (ii) particles appear to have less impact on nitrite estimation. In addition, improper mixing together with instabilities in the urine nitrification process appears to significantly reduce the performance of the estimation model.

Needs assessment of people with severe mental illnesses and their families in Azerbaijan

RESUMO: Os indivíduos com doença mental grave, assim como os seus familiares, podem ser caracterizados como uma população em que ocorre uma combinação complexa de necessidades médicas e psicossociais, nomeadamente a nível do diagnóstico e do acesso aos serviços de saúde mental. A avaliação de necessidades pode fornecer informações importantes para o desenvolvimento de intervenções eficazes, tanto a nível da população como a nível individual. Este estudo teve como objetivo determinar as diferentes necessidades reportadas pelos pacientes com doença mental grave e seus familiares , assim como investigar as possíveis relações entre o estado de necessidades e as variáveis sócio-demográficas e clínicas. Simultaneamente, o estudo teve como objetivo avaliar a sobrecarga familiar e a satisfação dos utentes com os serviços de saúde mental. Foi elaborado um estudo transversal, realizado numa amostra de conveniência de cinquenta díades de paciente/membro da família, seguidos em regime de ambulatório no Centro Nacional de Saúde Mental. Foram utilizados como instrumentos de avaliação um questionário sociodemográfico, a Escala Breve de Avaliação Psiquiátrica (BPRS), o questionário de Avaliação de Necessidades de Camberwell (CAN), o Questionário de Avaliação do Envolvimento (IEQ) e a Escala de Verona de Satisfação com os Serviços (VSSS). As mais frequentes necessidades não-satisfeitas foram o ‘sofrimento psicológico’, as ‘atividades sociais’ e os ‘benefícios sociais’. O estudo mostrou uma sobrecarga significativa nas famílias que cuidam de pessoas com doença mental grave, que se correlacionou com as suas opiniões sobre as necessidades dos pacientes e teve um impacto negativo sobre o bem-estar psicológico. Os três mais importantes predictores de sofrimento psíquico em familiares foram o sexo, a situação laboral e a relação com o paciente. A avaliação da satisfação com os serviços revelou a existência de um hiato significativo entre os serviços prestados e os serviços desejados, reportados pelos pacientes e seus familiares. A maioria dos participantes do estudo desejavam ter um trabalho protegido, ou receber ajuda para encontrar emprego. Os resultados deste estudo poderão ser usados para fins de planeamento desenvolvimento e avaliação de serviços de saúde mental no Azerbeijão. Algumas recomendações sobre a melhoria dos serviços de saúde mental para pacientes com doença mental grave e suas famílias são feitas na secção final do trabalho.----------ABSTRACT: Patients suffering from severe mental illness, in addition to their family members, may be characterized as a population with a complex combination of medical and psychosocial needs, which are under-recognized and under-addressed by mental health services. At the same time, needs assessment provides important information necessary for developing effective interventions at both population and individual level. The study was aimed to determine various needs perceived by patients with SMI and their family members, as well as to find out possible relations between the needs and socio-demographic and clinical variables. Similarly the study was intended to evaluate family burden and users’ satisfaction with services. This was a cross-sectional study conducted on a convenience sample. Fifty dyads of a patient and family member applying for out-patient services to the National Mental Health Centre participated in the study. Sociodemographic questionnaire, Brief Psychiatric Rating Scale, Camberwell Assessment of Need, Involvement Evaluation Questionnaire, and Verona Service Satisfaction Scale were used as assessment tools. The most prominent unmet needs reported by people with SMI and their relatives were psychological distress, social activities and welfare benefits. The study showed significant burden in families caring for people with SMI, which correlated with their views about patients’ needs and had a negative impact on the psychological well-being. The three most important predictors of psychological distress in family members were gender, employment status and relationship to patient. Evaluation of satisfaction with services pointed out the gap between provided and desired services reported by patients and their relatives. Most of study participants wished to have sheltered work, or receive help in finding employment. The results of this study may be used for the purposes of mental health service planning, development and evaluation in our country. Some recommendations on improvement of mental health services for patients with SMI and their families have been made in the conclusion.

Analysis of the interaction of polycyclic aromatic compounds in a model organism: integration of genotoxic and histopathological effects

Due to their toxicity, especially their carcinogenic potential, polycyclic aromatic hydrocarbons (PAHs) became priority pollutants in biomonitoring programmes and environmental policy, such as the European Water Framework Directive. The model substances tested in this study, namely benzo[b]fluoranthene (B[b]F), considered potentially carcinogenic to humans and an effector carcinogenic PAH to wildlife, and phenanthrene (Phe), deemed a non-carcinogenic PAH, are common PAHs in coastal waters, owning distinct properties reflected in different, albeit overlapping, mechanisms of toxicity. Still, as for similar PAHs, their interaction effects remain largely unknown. In order to study the genotoxic effects of caused by the interaction of carcinogenic and non-carcinogenic PAHs, and their relation to histopathological alterations, juvenile sea basses, Dicentrarchus labrax, a highly ecologically- and economically-relevant marine fish, were injected with different doses (5 and 10 μg.g-1 fish ww) of the two PAHs, isolated or in mixture, and incubated for 48 h. Individuals injected with B[b]F and the PAH mixture exhibited higher clastogenic/aneugenic effects and DNA strand breakage in blood cells, determined through the erythrocytic nuclear abnormalities (ENA) and Comet assays, respectively. Also, hepatic histopathological alterations were found in all animals, especially those injected with B[b]F and the PAH mixture, relating especially to inflammation. Still, Phe also exhibited genotoxic effects in sea bass, especially in higher doses, revealing a very significant acute effect that was accordant with the Microtox test performed undergone in parallel. Overall, sea bass was sensitive to B[b]F (a higher molecular weight PAH), likely due to efficient bioactivation of the pollutant (yielding genotoxic metabolites and reactive oxygen species), when compared to Phe, the latter revealing a more significant acute effect. The results indicate no significant additive effect between the substances, under the current experimental conditions. The present study highlights the importance of understanding PAH interactions in aquatic organisms, since they are usually present in the aquatic environment in complex mixtures.