Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants that can be modified to oxygenated PAH (oxyPAHs) derivatives. It is well known that oxyPAHs tend to be much more reactive than their parent compounds. Toxicity can be attributed to direct interaction with target molecules or generation of reactive oxygen species (ROS). Metals are another class of contaminant found ubiquitously throughout the environment. Some metals are toxic at levels below the 1:1 ratio predicted by the biotic ligand model and are thought to manifest toxicity through ROS generation. Often metals and PAHs occur as co-contaminants in industrialized environments, yet little is known about their potential co-toxicity or mechanisms of action in mammalian reproductive function. Previously, we described that a PAH, 9, 10-phenanthrenequinone (PHEQ), inhibited LH-stimulated progesterone secretion in dispersed rat corpus luteal (CL) cells (Nykamp et al., 2001). Viability was decreased in CL cells exposed to PHEQ and 1,2-dihydroxy-anthraquinone (1,2-dhATQ), but not their parent compounds phenanthrene (PHE) or anthracene (ANT). Similarly, LH-stimulated progesterone production in CL cells was inhibited by PHEQ and 1,2-dhATQ, but not PHE. Further investigation revealed that PHEQ, but not PHE, ANT nor 1,2-dhATQ generated ROS in CL cells. Viability experiments were repeated using the choriocarcinoma cell line JEG-3 with similar results. Various metals were assessed for their toxicity to both CL and JEG-3 cells. The endpoints used to measure viability were metabolic activity and membrane integrity. In general, metabolic activity was a more sensitive indicator of toxicity than membrane integrity. The order of toxicity for metals in CL cells was Hg2+ > Cd2+ > Zn2+ > Ni2+ > Cu2+ for metabolic activity and Hg2+ ≈ Zn2+ > Cd2+ > Cu2+ > Ni2+ for membrane integrity. Only Hg2+ and Cu2+ were tested in JEG-3 cells. While Cu2+ was non-toxic, EC50s for Hg2+ metabolic activity and membrane integrity were 20 mM and 23 mM, respectively. Experiments were designed to study the mixtures of metals and PAHs on viability, ROS production, and LH-stimulated progesterone production in CL cells. Mixtures of each metal with either PHEQ or 1,2-dhATQ were incubated with CL cells and their effect on metabolic activity and membrane integrity assessed. Generally, most metal/oxyPAH mixtures displayed only additive toxicity. However, mixtures of Cu2+ and PHEQ showed synergistic toxicity to both metabolic activity and membrane integrity. Mixture studies in JEG-3 cells used only combinations of Cu2+ or Hg2+ with PHEQ or 1,2-dhATQ. Similar results to metabolic activity and membrane integrity in CL cells were observed. Mixtures of Cu2+ and PHEQ or 1,2-dhATQ were tested in CL cells for their effect on LH-stimulated progesterone secretion and ROS production. Additive effects were observed in both LH-stimulated progesterone secretion and ROS production for Cu2+/1,2-dhATQ mixtures while synergistic effects for both parameters were seen with Cu2+/PHEQ. Efforts to determine the site of action for mixtures of Cu2+/PHEQ involved adding the cholesterol analogue, 22-OH cholesterol (22-OHC) to CL cells in the absence of LH. Cytochrome P450 side-chain cleavage (CYP450scc) enzyme operates constitutively and the addition of 22-OHC to CL cells resulting in a 5-fold increase in progesterone production without added LH. Kinetic assays with 22-OHC show that while progesterone secretion was inhibited with PHEQ addition alone, a further significant reduction with both Cu2+ and PHEQ was not observed. The use of forskolin, an activator of adenylate cyclase, did not show any significant enhancement of progesterone secretion with the addition of Cu2+/PHEQ compared to PHEQ alone. The potential targets of Cu2+/PHEQ mixture include any step in the steroidogenic cascade from activation of protein kinase A onward with the proteins of the mitochondria, cytochrome P450 side chain cleavage enzyme and steroidogenic acute regulatory protein, being the most likely. Differential display polymerase chain reaction (ddPCR) was a molecular approach taken to determine the effect of PHEQ on JEG-3 gene expression. The genes whose expression appeared to be up-regulated with PHEQ exposure were serine protease inhibitor, Alu repeat sequence, heterogeneous ribonuclear ribonucleoprotein C (hnRNP C), eukaryotic translation initiation factor 3 (eIF3), nucleoporin-like protein, eukaryotic translation elongation factor 1a1 (eEF1 a 1), autophagy-linked FYVE domain (Alfy), spectrin, and proteasome. Apparent down-regulated genes in JEG-3 cells after PHEQ exposure included poly(ADP-ribose) polymerase 10 (PARP10), polyglutamine binding protein-1 (PQBP-1), heterogeneous ribonuclear ribonucleoprotein C (hnRNP C), eukaryotic translation initiation factor 5A (eIF5A), and keratin. In both cell types, oxyPAHs were more toxic than their parent compounds. Metals showed greater toxicity to metabolic activity than to membrane integrity. Of the combinations tested, only PHEQ and Cu2+ exhibited synergistic toxicity. ROS generation was the likely mechanism behind PHEQ/Cu2+ toxicity. Both cell types used represent critical roles in human reproductive health. The proper production of progesterone, a critical hormone for the maintenance of pregnancy in mammals, represents a unique endpoint for the assessment of toxicity. These results illustrate the need to study modified oxyPAHs, metals and metal/oxyPAH mixtures for their potential impact on human reproductive health.

The need to assess human exposures to foodborne and environmental carcinogens, particularly in populations at high risk for cancer and disease, has led to the development of chemical-specific biomarkers. Sensitive biomarkers for aflatoxin and polycyclic aromatic hydrocarbons (PAHs) have been useful in providing information on population exposure and reducing associated public health impacts. Aflatoxins are fungal metabolites found in a variety of foods. Among these toxins, aflatoxin B1 (AFB1) is the most predominant and hepatocarcinogenic. Acutely, AFB1 can cause disease and death, necessitating safe and effective intervention strategies. Inclusion of NovaSil (NS) clay in the diet represents a practical, sustainable approach. NS has been shown to prevent aflatoxicosis in multiple animal species by binding aflatoxins in the gastrointestinal tract, reducing toxin bioavailability. Co-exposure to PAHs, hazardous environmental contaminants, has been shown to increase the risk for hepatocellular carcinoma (HCC). Therefore, objectives of this research were to utilize biomarkers to assess aflatoxin and PAH exposures in susceptible populations in Ghana and the U.S. and to evaluate the safety and efficacy of NS intervention in Ghana (a population at risk for aflatoxicosis). After 3-month intervention with 3.0g NS/day, median aflatoxin M1 (an AFB1 metabolite) was significantly reduced (up to 58 percent) compared to the placebo group. Furthermore, no significant differences were found in levels of nutrient minerals between NS and placebo groups at baseline and 3-months suggesting NS can be used to effectively sorb AFB1 without affecting serum concentrations of important minerals. PAH biomarker results showed participants in Ghana were significantly exposed to high levels of PAHs based on the presence of 1-hydroxypyrene (1-OHP) in the majority of urines (98.9 percent). NS treatment had no effect on 1-OHP levels, further confirming the preferential binding of aflatoxins by NS. U.S. population data from a Hispanic community in Texas with an elevated incidence of HCC demonstrated a lower percentage and level of aflatoxin and PAH biomarkers. Aflatoxin M1 excretion, however, was associated with increased consumption of certain foods prone to aflatoxin contamination; thus, some individuals may be more vulnerable to exposure and associated interactions that increase the risk for HCC (e.g., PAHs or hepatitis infection).

The objective of this study was to investigate the spatial and temporal distribution of black carbon (BC) and possible sources by analyzing BC contents in core and sediment trap samples collected from Kao-ping submarine Canyon and surficial sediments collected from Love River, Chianjen River, Kaohsiung Harbor, Kao-ping River and adjacent coastal area. In addition, sediment core and trap samples of Kao-ping submarine Canyon, and suspended solids of Kao-ping estuary were analyzed to estimate the BC loading from Kao-ping River and the flux in Kao-ping submarine Canyon. The concentrations of BC ranged from 0.38 to 3.29 mg g-1 in this study. The results we found in coastal sediments were comparable to those in Asia, but lower than those in America and Europe. Black carbon found in surficial sediments of D2, L1 and of stations from Love River, Chianjen River and Kaohsiung Harbor were contributed from vehicle emission or coal combustion. Correlation coefficients of BC versus total polycyclic aromatic hydrocarbon (PAH) concentrations, combustion PAHs, total organic carbon (TOC) and grain size were significant in the sediments of Kao-ping River adjacent coast. Regrading to the temporal distribution of BC in Kao-ping submarine Canyon, BC and PAHs increased in the deposited sediment after 1970, that was probably related to prosperous industrial activities for last decades in Taiwan. Surficial sediments could be grouped into three clusters by hierarchical cluster analysis (HCA). Results of principal component analysis (PCA) showed principal component 1 (PC 1) could explain 35 % of total variances. Significant PC 1 compound loadings were found mostly from high molecular weight PAHs which derived mainly from combustion processes. This result was supported by the significant correlation (p<0.05) of PC 1 scores versus BC concentrations which were also mainly derived from combustion. BC fluxes for sediment cores, S1 and S37, and sediment trap of Kao-ping submarine Canyon, 0.59 g m-2 yr-1, 2.03 g m-2 yr-1 and 23 g m-2 yr-1, respectively, were comparable to those reported for surficial sediments in literature. However, BC fluxes in this study were lower than those in the sediments from Mouth of Providence River, Palos Verdes Shelf and New England Harbors, but higher than those in pelagic sediments of the Pacific Ocean. In addition, we also measured BC concentrations in suspended solid samples to estimate loadings of Kao-ping estuary which ranged from 33 to 1765 kg day-1 with an average of 602 kg day-1. Annual BC loading of Kao-ping River was roughly estimated as 29.55¡Ñ104 tons which was lower than that of the Mississippi River.

The extraction procedures for the determination of polycyclic aromatic hydrocarbons (PAH) concentrations in sediment samples had been developed by using GC-FID and GC-MS. The optimized methods were soxhlet extraction, ultrasonic bath extraction and solid phase micro extraction (SPME). In order to search out the main factors affecting extraction efficiencies of the methods, factorial design was used. The best extraction method was chosen and optimum values for main factors were selected for the development of the extraction method for PAH determination in sediment samples. The accuracy of the method was verified by analyzing NIST SRM 1597 (complex mixture of polycyclic aromatic hydrocarbons from coal tar). The selectivitiy and sensitivity obtained were quite adequate for the determination of PAHs in sediment sample. The best extraction and analysis methods were then applied to determine 16 PAHs in sea sediments from &Ouml / l&uuml / deniz Lagoon, Mugla, Turkey and 19 PAHs in Ikizcetepeler Dam Lake, Balikesir, Turkey sediments to illustrate the capability of the selected extraction and analysis method to detect PAHs and to determine the status of the contamination.

published_or_final_version / Earth Sciences / Master / Master of Philosophy

Alkylphenanthrenes such as retene (7-isopropyl-1-methylphenanthrene) are aquatic contaminants commonly found in anthropogenically-, industrially-, and petroleum-contaminated environments, and have been implicated in crude oil toxicity. In the early life stages (ELS) of fish, exposures to alkylphenanthrenes produce signs of toxicity typical of those observed in exposures to halogenated aromatic hydrocarbons, particularly to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD, the most toxic congener, serves as the basis of the current mechanism-based risk assessment model. The model assumes that congeners that produce TCDD-like toxicity share a common mode of action and act additively. The mechanism of TCDD-like toxicity is assumed to be mediated by the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor involved in the xenobiotic response (e.g., induction of cytochrome P450 1A enzymes; CYP1A) and in normal development. CYP1A enzymes are not involved in the mechanism of TCDD toxicity. Alkylphenanthrenes toxic to the ELS of fish are AhR ligands, but in contrast to TCDD, are readily metabolized by CYP1A enzymes. The byproducts of CYP1A metabolism have been implicated in retene toxicity. However, the target tissue of retene and the direct roles of AhR and CYP1A in retene toxicity are unknown, but are expected to be similar to those of TCDD. The results presented in this thesis suggest that in the ELS of fish: (1) the primary target of retene is the cardiovascular system (Chapters 2 & 5); (2) retene toxicity is stage-specific (Chapter 2); (3) the mechanism of retene toxicity is mediated by AhR2, and is independent of CYP1A enzymes (Chapter 5); (4) multiple CYP1A-independent toxicities can result from exposures to different mixtures of CYP1A inducing (retene) and CYP1A inhibiting (alpha-naphthoflavone or 2-aminoanthracene) PAHs (Chapters 3 & 4); and (5) multiple concentration-dependent mechanisms of toxicity (i.e., synergism and response addition) can occur in co-exposures of a CYP1A inducer (retene) with a range of CYP1A inhibitor (alpha-naphthoflavone) concentrations (Chapter 3). Thus, retene toxicity is mechanistically similar to that of TCDD toxicity, suggesting alkylphenanthrenes can be included in the current risk assessment model. However, the observed variable mixture toxicities and species differences in retene toxicity raise questions about the effectiveness of this model. / Thesis (Ph.D, Biology) -- Queen's University, 2009-01-13 12:10:31.373

Carbon nanoribbons are today of great interest as graphene segments with modulable electronic properties. Whilst top down techniques give giant ribbons, bottom-up organic synthesis may lead to exactly designed nanoribbons of controlled geometries. The Scholl reaction is a precious chemical tool for that purpose since it yields efficiently to the graphitization of long and flexible polyphenylene precursors.Surprisingly, twisted structures may be obtained preferentially even if less crowded isomers are also feasible. It has been shown that, against all expectation, even a strong steric hindrance has no marked effect on regioselectivity and highly twisted polycyclic aromatic hydrocarbons are sometimes preferentially formed, whereas their flat and more symmetrical isomers are only obtained in minority. Highly twisted structures such as hexabenzotriphenylene (HBTP) may then be obtained very easily from flexible polyphenylene precursors.After discovering this unexpected regioselectivity, we used it on purpose to form polyhelicenic species. Attempts to prepared hexaphenanthrotriphenylene (HPTP) were unsuccessful due to reactivity issues when synthesizing the corresponding flexible precursors. By using a new versatile strategy leading to an advanced common precursor, several C3-symmetrical flexible substrates have been synthesized and submitted to Scholl reaction. The expected [6]helicenes were not obtained and rearranged products were formed instead, but TMS-bearing HBTP could be prepared, as well as a hexabenzocoronene (HBC) which exceptionnal solubility is due to the distortion of the aromatic core under the effect of bulky tert-butyl substituents in bay regions.The easily formed [5]helicene fragment has been incorporated in the design of twisted carbon nanoribbons that would be composed of a succession of such motifs. As a test reaction, the corresponding monomer and dimer have been synthesized with an excellent yield and fully characterized. Their X-ray structures have even been determined, giving interesting information about their configuration. A more general strategy has then been developed and optimized for the systematic synthesis of longer oligomers of twisted nanoribbons. Using this technique, the trimer and tetramer have been synthesized and characterized by mass spectrometry.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 355-382).

Orientador: Mary Rosa Rodrigues de Marchi / Banca: Christine Laure Marie Bourote / Banca: Annibal Duarte Pereira Netto / Banca: Nilva Ré Poppi / Banca: Roma Tauler / Resumo: No Brasil, a queima da cana de açúcar é utilizada para facilitar a colheita, mas este procedimento causa grande poluição ambiental devido a quantidade de fuligem lançada na atmosfera. O material particulado (MP) emitido contém inúmeros contaminantes, tais como: hidrocarbonetos policíclicos aromáticos (HPAs) e elementos. A cidade de Araraquara/SP possui cerca de 200.000 habitantes e é cercada por plantações de cana de açúcar, sendo que a prática de queimada é constante no período da safra (abril-novembro, todos os anos). Neste trabalho, determinou-se a concentração elementar e de HPAs em MP na cidade de Araraquara durante o período da safra (S) e da entre safra (E) da cana de açúcar. Foram coletadas 60 amostras (E) e 220 amostras (S) para a análise de HPAs, e 10 amostras (E) e 10 amostras (S) para a análise elementar. As amostras foram coletadas utilizando um amostrador dicotômico (vazão: 10 L min-1, 24 h) com filtros de PTFE (37 mm, 2 μm de tamanho de poro). Para a análise de HPAs, dez filtros de PTFE contendo o MP foram extraídos em banho de ultrassom com acetona/n-hexano (1:1 v/v), sendo que as análises foram efetuadas por HPLC/FLD. A análise elementar foi efetuada por fluorescência de raios X por energia dispersiva (EDXRF), sem tratamento prévio das amostras. A concentração mediana de HPAs totais foi de 1,9 ng m-3 (E) e 6,2 ng m-3 (S). A concentração mediana de benzo[a]pireno, HPA considerado carcinogênico, foi de 0,026 ng m-3 e 0,15 ng m-3 para os períodos de E e S, respectivamente. O risco potencial de câncer associado à exposição a HPAs por inalação, foi estimado com base na concentração de benzo[a]pireno equivalente (BaPeq), onde a toxicidade de uma mistura de HPAs é definida pela concentração de cada substância multiplicada pelo seu fator de equivalência de toxicidade relativa (FET). Os valores medianos encontrados para... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In Brazil, the sugar cane crops are burned to facilitate the harvesting, this procedure causes environmental pollution from the large amounts of soot that are released into the atmosphere. This particulate matter (MP) contains numerous contaminants such as polycyclic aromatic hydrocarbons (PAHs) and metals. The city of Araraquara, located at central area from São Paulo State, has around 200,000 inhabitants and is surrounded by sugarcane plantations (46,994 ha of total cultivated area, in the harvest 2008/2009). In this study, PAHs concentrations and elemental composition in the MP were determined in Araraquara city during the sugarcane harvesting (HV) and non-harvesting (NHV) seasons. 60 samples were collected during the NHV and 220 samples during the HV seasons for the analysis of PAHs. 10 samples were collected during the NHV and 10 samples during the HV season for the analysis of Si, K, Ca, Ti, V, Fe, Sr, Cr, Ni, Mn, Cu, Zn, As, Cd, Pb, Sb, Al, S and Cl. The samples were collected using a dichotomous sampler (10 L min-1, 24 h) with PTFE filters. Ten filters sets were extracted (ultrasonic bath with hexane/acetone (1:1 v/v)) and analyzed by HPLC/FLD for the analysis of PAHs. Information concerning the bulk elemental concentration was provided by energy-dispersive x-ray fluorescence (EDXRF). The median concentration for total PAHs was 1.9 ng m-3 (NHV) and 6.2 ng m-3 (HV). Benzo[a]pyrene median concentration was 0.026 ng m-3 and 0.15 ng m-3 for the NHV and HV seasons, respectively. The potential cancer risk associated to inhalation exposure was estimated based on the benzo[a]pyrene toxic equivalence (BaPeq), where the overall toxicity of a PAH mixture is defined by the concentration of each compound multiplied... (Complete abstract click electronic access below) / Doutor