PCBs are among the most problematic marine contaminants. Converging towards the oceans via the rivers and the atmosphere, they concentrate in sediments where they become a permanent threat to organisms living at their contact. PCBs are extremely resistant, bioaccumulated and some congeners are considered as highly toxic. The North Sea is considered as a highly contaminated area ;however little information is available regarding the impact of PCBs on key benthic organisms of this region.<p>Ubiquist, abundant and generally recognized as a good bioindicator species, the common NE Atlantic sea star Asterias rubens (L.) is an ecosystem-structuring species in the North Sea and was chosen as an experimental model. The present study focused on the characterization of PCB bioaccumulation in A. rubens exposed through different routes (seawater, food, sediments) and on subsequent biological responses, at immune and sucellular levels. The considered responses were respectively (i) the production of reactive oxyggen species (ROS) by sea stars amoebocytes, which constitutes the main line of defence of echinoderms against pathogenic challenges and (ii) the induction of a cytochrome P450 immunopositive protein (CYP1A IPP) which, in vertebrates, is involved in PCB detoxification.<p>Experimental exposures carried out have shown that A. rubens efficiently accumulates PCBs. Exposure concentrations were always adjusted to match those encountered in the field. PCB concentrations reached in sea stars during the experiments matched the values reported in field studies ;therefore our experimental protocol was found to accurately simulate actual field situations. Uptake kinetics were related to the planar conformation of the considered congeners :non-coplanar PCB uptake was described using saturation models, whereas coplanar PCBs (c-PCBs) were bioaccumulated according to bell-shaped kinetics. Non-coplanar congeners generally reached saturation concentrations whithin a few days or a few weeks, which means that sea stars can be used to pinpoint PCB contamination shortly after occurrence. On the other hand, c-PCB concentrations reached a peak followed by a sudden drop, indicating the probable occurrence of c-PCB-targeted metabolization processes in sea stars. Our experimental studies also demonstrated that seawater was by far the most efficient route for PCB uptake in sea stars and that even if PCB levels in seawater are extremely low compared to sediment-associated concentrations, seawater constitutes a non-negligible route for PCB uptake in marine invertebrates. Among the different body compartments, bodywall displayed the highest bioaccumulative potency and can therefore be considered as particularly interesting for field biomonitoring applications. Rectal caeca, which play a central role in digestion and excretion processes in sea stars, have also rised particular interest as results suggest these organs could be involved in the elimination of PCB 77 degradation products. <p>The field work carried out during the present study showed that PCB concentrations measured in A. rubens tissues reflect environmental levels of certain congeners. As it was the case in experimental conditions, A. rubens differentially accumulated PCB congeners according to their planarity. Strong relationships were found between concentrations measured in sediments and those determined in sea stars body wall for certain non-coplanar congeners (e.g. 118 and 138), thus allowing to consider A. rubens as a suitable bioindicator species for medium-chlorinated PCB congeners. On the other hand, sea stars appeared to be able to regulate -to a certain extent- their content in coplanar PCBs. This implies that (i) A. rubens cannot be strictly considered as an indicator organism for c-PCBs and (ii) c-PCBs probably affect essential aspects of sea star biology, potentially leading to deleterious effects.<p>The present study addressed effects of PCB exposure on A. rubens biology, in both experimental and field conditions. In experimental conditions, PCBs were found to significantly alter ROS production by sea stars amoebocytes. This alteration also occurred in a congener-specific way :c-PCBs were found to significantly affect, and probably impair sea stars immune system, whereas non-coplanar congeners had no effect. In the field, the PCB contribution to immunotoxicity could not be determined because none of our studies considered ROS production along with c-PCB concentration measurements. However, the levels of ROS production by sea stars amoebocytes measured in field and experimental conditions were found to potentially lead to altered immunity, and therefore to impair sea stars defence against pathogenic agents. <p>A specially designed ELISA was used to measure CYP1A IPP in experimental and field conditions. Experimental work has shown that the induction of this protein was related to PCB exposure in a congener-specific fashion :c-PCBs alone were found to strongly induce the production of CYP1A IPP according to a dose-dependent relationship. These results have highlighted many similarities between the dioxin-like responsiveness of CYP1A IPP induction in sea stars and that occurring in vertebrates. This strongly suggests similarities in the toxicity-triggering mechanism of dioxins and c-PCBs. In the field, CYP1A IPP induction was found to be significantly related to PCB levels determined in bottom sediments. It can thus be considered as a valuable biomarker. Further research is however needed to better characterize the influence of physico-chemical and physiological parameters on CYP1A induction to refine the interpretation of the information gathered via this biomarker. <p>Results obtained in our study have lead to questionning international regulations applying to PCB biomonitoring in the marine environment. For instance, we strongly suggest that the selection of congeners to be systematically considered should be revised to include c-PCBs. Indeed, in our experiments PCB toxicity was almost always attributable to the sole c-congeners. Historically, determination of c-PCB concentrations was extremely difficult due to analytical limitations ;however, nowadays, these problems have been overcome and do no more justify their exclusion from monitoring studies. <p>Although A. rubens appeared to be quite resistant to PCB contamination, levels measured in sea stars from the southern North Sea can possibly affect their immune and endocrine systems in a subtle way, but with relatively low risk for this species at the short-term. However, this does not mean that other species in this region undergo similarly low risks, or that sea star-structured ecosystems may not become affected in the long-term<p> / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished

The blood-brain barrier (BBB) is a dynamic interface, mainly consisting of highly specialized brain microvascular endothelial cells (BMECs) that segregate the central nervous system (CNS) from the peripheral circulation. Impairment of the BBB, due to disruption of tight junction (TJ) proteins and inflammatory responses, may initiate and/or contribute to the progress of CNS disorders, including stroke. Stroke is the second leading cause of death worldwide. It has been shown that aging and environmental pollutants can induce brain endothelium dysfunction, and are considered as risk factors for stroke. Deficiency of telomerase is highly linked with aging-associated vascular diseases. Evidence indicates that patients with shorter telomere length are at higher risk of heart disease or stroke. Results in this dissertation address the influence of telomerase reverse transcriptase (TERT), a key component of telomerase, on the BBB integrity in the context of ischemic stroke induced brain injury. Our results indicate that aging-related BBB alterations aggregate the stroke outcomes by inducing oxidative stress and stimulating proinflammatory responses on the brain microvessels. The ability of the BBB to protect the brain from harmful compounds indicates that the BBB may be targeted by chemical toxicants in the peripheral circulation. Polychlorinated biphenyls (PCBs) are persistent organic pollutants that frequently bind to nanoparticles (NPs) in the environment. Our results demonstrate that binding PCB153, one of the most abundant PCB congeners in the environment, to silica nanoparticles (PCB153-NPs) potentiates cerebrovascular toxicity and stroke outcomes via stimulation of inflammatory responses and disruption of BBB integrity. These events are mediated by activation of toll-like receptor 4 (TLR4), which subsequently recruits tumor necrosis factor-associated factor 6 (TRAF6) and initiates the production of multiple inflammatory mediators. Research presented in this dissertation demonstrates that aging and environmental pollutants play crucial roles in modifying the function of the BBB through alterations of inflammatory responses and TJ protein expression, which further contribute to the progression of stroke-induced cerebral ischemic injury.

Bifenilas policloradas (PCBs) foram produzidas comercialmente entre 1929 e meados da década de 1980 para propósitos industriais. As mesmas propriedades que despertaram o interesse industrial, tais como: inércia química, alta constante dielétrica, resistência à queima; foram responsáveis pelo espalhamento dos PCBs em todos os compartimentos ambientais, de tal forma que são encontrados em amostras de tecidos adiposos de animais e humanos, leite, sedimentos dentre outras matrizes. Enormes quantidades de PCBs continuam em uso ou estão estocadas a espera de uma destinação final. No presente estudo demonstramos o uso da reação de hidrodescloração catalítica como forma de destruição/destoxificação de bifenilas policloradas. Para tanto, a reação foi estudada em amostras reais de PCBs (óleo dielétrico - Ascarel®), amostras comerciais (Aroclor® 1242 e 1254) e amostra sintética (2,4-diclorobifenila). O estudo se baseia no uso de solventes orgânicos como meio reacional e paládio suportado em carvão ativado como catalisador, devido à sua seletividade para a reação desejada, bem como sua baixa capacidade de hidrogenar compostos aromáticos. xii A condição experimental ótima para a hidrodescloração foi determinada a partir da aplicação de planejamento experimental do tipo Doehlert. Esta condição ótima foi aplicada com sucesso a PCBs contidos em outras matrizes. A cinética da reação é apresentada para o 2,4-diclorobifenila como estudo de caso e uma proposta de mecanismo da reação de hidrodescloração de PCBs é apresentada baseada nos resultados experimentais. / Polychlorinated biphenyls (PCBs) were produced between 1929 and the 1980s for industrial applications. The same properties that make it a chemical of interest for industrial applications, such as: chemical inertness, high dielectric constant, fire resistance; were responsible for the widespreading of PCBs over all enviornmental compartments. They can be found in samples of fat tissues of humans and animals, milk, sediments, among other matrices. Enormous quantities of PCBs are still in use or stocked waiting for a final destination. In the present study, we have shown the use of catalytic hydrodechlorination as an alternative for the destruction/detoxification of polychlorinated biphenyls. For this, the reaction was studied in real samples of PCBs (dielectric oil - Ascarel®), commercial samples (Aroclor® 1242 e 1254) and pure chlorinated biphenyls (2,4-dichlorobiphenyl). The study is based in the use of organic solvents as reactional media and palladium supported in activated carbon as catalyst, due to its selectivity for the desired reaction and to its low capacity to hydrogenate aromatic compounds. xiv The optimal hydrodechlorination condition was determined through the application of a Doehlert experimental planning. This optimal condition was applied with success to PCBs contained in other matrices. The reaction kinetics for 2,4-dichlorobiphenyl was presented as a case study and a mechanistic proposal was presented for the hydrodechlorination of PCBs based on these experimental conditions.

A reação de hidrodescloração catalítica (HDC) de bifenilas policloradas (PCB) foi estudada em diversos sistemas reacionais: solventes orgânicos, dióxido de carbono supercrítico, presença e natureza de aditivos (bases e co-solventes) a temperaturas na faixa de 25 &#176;C a 100 &#176;C e pressões de 1 bar até 250 bar. Os reagentes utilizados foram um composto modelo (2,4- diclorobifenil), misturas comerciais de PCB (Aroclor, Ascarel) e outros compostos halogenados (clorobenzenos e bromoclorobenzeno). Os catalisadores avaliados, paládio suportado em carvão ativo (Pd/C), paládio suportado em sílica mesoporosa (Pd/SiO2), nanopartículas ferromagnéticas de paládio (FFSiNH2Pd), e nanopartículas ocas de paládio (PdNP) e de platina (PtNP), mostraram-se versáteis nas mais diversas condições, quer sejam condições supercríticas, presença ou não de água, presença e natureza da base e diferentes doadores de hidrogênio. Em dióxido de carbono, dois regimes reacionais foram avaliados: dióxido de carbono subcrítico, onde o gás atua como agente expansor da fase líquida ao se dissolver nela permitindo que a reação ocorra em uma fase líquida rica em gás hidrogênio; e dióxido de carbono supercrítico, sistema onde a temperatura influencia fortemente a reação e a pressão tende a ter efeito negativo sobre a velocidade de reação, devido a efeitos de diluição e de competição das moléculas do gás com as moléculas dos reagentes. A condição reacional ótima foi determinada para o regime supercrítico e dados cinéticos foram obtidos para os regimes sub- e supercrítico. / The catalytic hydrodechlorination reaction (HDC) of polychlorinated biphenyls (PCB) was studied in several reactional systems: organic solvents, supercritical carbon dioxide, presence and nature of additives (bases and co-solvents), in temperatures of 25 &#176;C to 100 &#176;C and pressures of 1 bar to 250 bar. The reagents used were: a model compound, 2,4-dichlorobiphenyl, commercial mixtures of PCB (Aroclor, Ascarel) and other halogenated compounds (chlorobenzenes and bromochlorobenzene). The catalysts evaluated, palladium supported in activated carbon (Pd/C), palladium supported in mesoporous silica (Pd/SiO2), palladium ferromagnetic nanoparticles (FFSiNH2Pd), and hollow palladium ((PdNP) and platinum (PtNP) nanoparticles, showed to be versatile in several conditions, either supercritical conditions, presence or not of water, nature of the base, and different hydrogen donors. In carbon dioxide, two reaction regimes were evaluated: subcritical carbon dioxide, where the gas acts as an expansion agent of the liquid phase when it dissolves in it, allowing that the reaction happens in a liquid phase rich in hydrogen; and supercritical carbon dioxide, a system where the temperature has a strong influence over the reaction and the pressure has a negative effect on the rate of the reaction, due to dilution and the competition of gas molecules with the reagents molecules for the catalyst. The optimal reaction condition was determined for the supercritical regime and kinetic data were obtained for both the sub and supercritical regimes.

The aim of this study was to investigate a potential impact of the old polychlorinated biphenyls (PCBs) dump on their occurrence in Bezdrevsky stream basin. Wastes, containing PCBs, were illegally stored in the area of ex-agrochemical factory in Lhenice village. Six localities were chosen for sampling by the method of integrative passive samplers SPMD, which provides more valuable information about contamination than commonly used grab samples. Passive samplers were exponated for 18 days in June 2017. The samples extraction was performed at the Laboratory of environmental chemistry and biochemistry (Faculty of fisheries and protection of waters), followed by clean up and preparation of these extracts for analysis with gas chromatograph coupled to tandem mass spectrometer (GC-MS/MS). Obtained data on PCBs amount in the samples were recalculated to their concentration in water. Concentration of seven indicator PCBs congeners (PCB 28 + 31, PCB 52, PCB 101, PCB 118, PCB 138, PCB 153 a PCB 180) was determined. These congeners are typical for technical PCBs mixtures which were produced in Czechoslovakia in the past. From their relative abundance, the potential source and an age of the contamination were estimated. Their total sum indicated significant exceedance of the limit only for the first locality, in the reservoir draining the dump area. There was found the concentration of 100 ng.l-1 of the 7 indicator PCBs sum. Concentrations at other localities complied with required limits and varied between hundredths to tenths of ng.l-1. In comparison with older data acquired from this area, the concentration at the first locality did not change, whereas PCBs concentration at the second and third locality downstream is currently lower than in past. Our data were compared to the latest data of PCBs concentrations in selected localities in CZ, which were received from Czech hydrometeorological intitute. From measured values can be stated, that the basin of Bezdrevsky stream and its fish pond system are not endangered by the presence of PCBs. Only two localities situated near the source of PCBs are comparable with localities in CZ which are influenced by the long term industry presence.

Presented is a study of persistent organic pollutants in Australian sewage sludge, focusing on environmental monitoring and a sewage sludge land application human health risk contaminated with these compounds. The chemicals of concern were: • Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and

The Arctic has long been considered to be a pristine environment, far from population centers and pollution sources. The detection of synthetic organochlorine compounds in various elements of the Arctic food web has confirmed the global dispersion of pollutants, particularly of persistent compounds such as organochlorines and heavy metals. Levels of heavy metals, although elevated, appear to be naturally so throughout much of the Arctic. Arctic pollution is both a humanitarian and ecological concern. Many arctic coastal communities depend heavily on marine mammal fat for sustenance, and are therefore potentially exposed to high levels of organochlorines and some metals. From an ecological perspective, the structure of arctic food webs, the importance of lipid mobilization for winter survival, and the adaptive physiologies of arctic organisms may result in an enhanced response to contaminant exposure. This thesis assesses the exposure and effect of organochlorine and heavy metal exposure in inland freshwater ecosystems of Arctic Alaska, and evaluates the physiological response of arctic grayling to experimental polychlorinated biphenyl (PCB) exposure. / Graduation date: 1995

Vitamin A, protein, iron, zinc, and polychlorinated biphenyls (PCBs) were studied in the food system of the Sahtu (Hareskin) Dene/Metis of Fort Good Hope (FGH) and Colville Lake (CL), NWT. Traditional foods contributed significantly more (p 00% of the Canadian Recommended Nutrient Intake (RNI) for protein, iron, and zinc but vitamin A consumption was generally $<$50% RNI. In all seasons, market foods provided significantly more vitamin A (p $ le$ 0.05) than traditional foods for FGH adults. Body weights were assessed for comparison of PCB intakes with the tolerable daily intake level (TDI) $(<$1 ug/kg body wt/day). Women $ ge$19 yrs weighed 59.9 $ pm$ 10.7 kg while men weighed 71.7 $ pm$ 11.4 kg. Most of the adult population consumed $<$25% TDI for PCBs.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xxi, 117 leaves / The aromatic compounds Polychlorinated Biphenyls (PCBs) are one of the largest groups of environmental pollutants. The greatest concern is the release of PCBs in the water systems by industrial effluent, accidental spillages or leaks. PCBs are able to bioaccumulate in the fatty tissues of animals, fish and humans. The impact on human health due to PCBs has prompted interest in their degradation. The application of microbial degradation of PCBs can transform many PCB metabolites. There are a wide variety of microorganisms that can degrade PCBs or utilise them as sole carbon sources. This study focused on isolating microrganisms from industrial wastewater capable of aerobic degradation of PCBs. The degradation potential of the selected isolates were investigated by using different analytical techniques viz. ultra violet or visible spectrophotometer (UV/Vis), thin layer chromatography (TLC) and gas chromatography electron capture detector (GC-ECD).

Recent advancements have uncovered environmental contributions to obesity and diabetes etiology. In fact, perinatal malnutrition resulting in low birth weight (LBW) has been shown to correlate with later life obesity and impaired glucose tolerance in aged offspring. LBW can result from a myriad of developmental perturbations including macronutrient restriction, hypoxia, maternal stress and toxin exposure. Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants that bioaccumulate in the food chain resulting in dietary exposure in humans. Maternal and cord blood PCB levels are inversely associated with birth weight, and recent studies indicate that perinatal exposures to PCBs contribute to gender-specific obesity development in children. PCBs have also been shown to enter breast milk resulting in direct exposure in early postnatal life. Therefore, we hypothesized that perinatal PCB exposure cause developmental blight resulting in decreased birth weight and increased adiposity and glucose intolerance with aging. We found that mice perinatally exposed to PCBs did not differ in birth weight, but exhibited sex-specific effects on adiposity. Females perinatally exposed to PCBs were significantly more obese at 7 weeks of age while male offspring exhibited no difference in fat mass but had decreased lean mass compared to controls. With aging, the differences in females dissipated while the male offspring decreased lean mass persisted. Male offspring perinatally exposed to PCBs displayed impaired glucose tolerance at 7 weeks of age but normalized over time, while the females were glucose intolerant only after 6 months of age. This impairment of glucose tolerance was not attributed to insulin resistance. These data illustrate time-dependent and sex-specific perturbations of maternal PCB exposure on offspring body composition and glucose homeostasis. As the liver is a major facilitator in glucose homeostasis and xenobiotic detoxification, we investigated PCB-induced alterations in hepatic gene expression and found attenuated expression of glycolytic genes and increased expression of detoxifying and antioxidant genes in both PCB-exposed maternal and offspring livers. Taken together, these data demonstrate a role for perinatal pollutant exposure in the etiology of glucose intolerance. Further studies are required to elucidate the mechanisms causing sex-specific modulation of body composition and glucose intolerance.