Arsenic (As) exposure is associated with cancer, lung and cardiovascular disease, yet the mechanisms involved are not clearly understood. Elevated matrix metalloproteinase-9 (MMP-9) levels are also associated with these diseases, as well as with exposure to water As. Our objective was to evaluate the effects of dietary components of inorganic As (iAs) intake on serum MMP-9 concentration at differing levels of tap water As. In a cross-sectional study of 214 adults, dietary iAs intake was estimated from 24-h dietary recall interviews using published iAs residue data; drinking and cooking water As intake from water samples and consumption data. Aggregate iAs intake (food plus water) was associated with elevated serum MMP-9 in mixed model regression, with and without adjustment for covariates. In models stratified by tap water As, aggregate intake was a significant positive predictor of serum MMP-9 in subjects exposed to water As≤10 μg/l. Inorganic As from food alone was associated with serum MMP-9 in subjects exposed to tap water As≤3 μg/l. Exposure to iAs from food and water combined, in areas where tap water As concentration is ≤10 μg/l, may contribute to As-induced changes in a biomarker associated with toxicity.

Orientador: André Henrique Rosa / Resumo: When introduced in environment, manufactured nanoparticles (NPs) can interact with biotic and abiotic molecules yielding a transformed NP usually coated with these molecules (natural coating). These different forms of the NPs should be considered as new materials because them distinct properties from the released NPs forms. In fact, these in situ transformations of the NPs have relevant impacts on their toxicological effects, having new or additional risks still not studied. This project aims to determine, understand and predict the impact of natural molecules in the transformations and bio-effects of Ag NPs, widely used as antibacterial agents. Despite the growing interest and use of these NPs, the gathered knowledge on their environmental consequences is still scarce, since the large majority of the studies do not consider the effect of the presence of natural coatings around the particles. In fact, most of the studies do not even determine the effects of the presence of manufactured coatings. Generally, NPs manufacturers add ionic or polymeric coatings to improve their mobility and stabilization in terms of size. Although the possible effects of these manufactured coatings in the NPs behavior there is not systematically studied about their impact. This project aims to overcome the current uncertainty about the environmental safety of manufactured coated NPs, and explore the impact of natural molecules on their environmental risk. The project objectives are: i) characterize... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

1 Abstract The goal of the thesis is to determine acute toxicity indices of seven alcohols (2-ethoxyethanol, 1-propanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 3-hexanol, 2-methyl-3-hexanol, 1-nonanol) by two different alternative methods. Another goal is to create QSAR models to predict the acute toxicities of alcohols which belong into model limits. First of the methods used is based on the movement inhibition of lower animals Tubifex tubifex. The method provides the acute toxicity indices EC50. The second method uses the cell line of mouse fibroblasts called Balb/c 3T3 and it provides the acute toxicity indices IC50. The IC50 were recalculated to the LD50 values that correspond to the oral administration of alcohols to a rat. It has been found that 1-nonanol is included into the category of alcohols classified as acute oral toxic according to the EU CLP system. Other six alcohols are non-classified as acute oral toxic. Subsequently, accurate QSAR models has been created in order to predict the acute toxicity of other alcohols using Tubifex tubifex specie or Balb/c 3T3 cell line. The models are suitable for saturated, branched, ethoxy- and cyclic alcohols with the log POW value from −0.74 to 3.07. It was necessary to exclude the acute toxicity indices of 1-nonanol from these models as some solubility...

Diclofenac has previously been shown to be toxic in three species of Gyps vultures (G. bengalensis, G. tenuirostris, and G. indicus) on the Indian subcontinent. Due to the devastating effect on the population of vultures (>99.9% species mortality), numerous efforts were initiated in order to protect the species. One such effort involved the removal of further threats to the species. At present the major threat identified has been the other non-steroidal drugs (NSAIDs) available for veterinary use. From research on ketoprofen and meloxicam (the former toxic and the latter safe), it was evident that toxicity was not general for the class of NSAIDs and that other factors played a role in toxicity. This unfortunately meant that each drug had to be tested individually in the vulture. While possible, the endangered status of vulture globally makes this approach unethical. As a result an alternate method of testing needed to be validated or sought. It was believed that a surrogate model could be the answer. The aim of this study was to establish if the crow could serve as such a surrogate model. The toxic effect of diclofenac in crows (n=6) was evaluated in a two cross over studies at doses of 0.8 and 10 mg/kg. No signs of toxicity were evident during the period of clinical monitoring, or necropsy or clinical pathology. In addition the drug was barely detectable in the birds and was described by a half-life of elimination of approximately 2.5 hours. To better explain the absence of observable toxicity, a follow-up study was initiated using freshly harvested renal tubular epithelial (RTE) cells and hepatocytes in a cell culture assay previously validated for cytotoxicity and reactive-oxidative generation. In general, the in vitro study results showed the hepatocytes and RTE cells to be tolerant to the presence of diclofenac, with cell viability remaining in the region of 80%. In contrast meloxicam appeared to be more toxic as previously seen with chicken primary RTE cells. Based on the in vivo and in vitro culture results, it was speculated that the absence of toxicity in the crow was due to a combination of rapid half-life of metabolism in combination with low susceptibility of the cells to toxicity. To further explain the role of metabolism in toxicity, meta-analysis of pharmacokinetic data for the domestic chicken (Gallus gallus</i.), African White-backed (Gyps africanus), Cape Griffon (Gyps coprotheres) and Turkey vultures (<i<Cathartes aura) were evaluated for trends in toxicity. The data clearly showed a trend toward toxicity when the half-life of elimination increased. It was therefore concluded that toxicity in Gyps species is probably related to zero-order metabolism, and therefore cannot be predicted by a surrogate model due to inter-species differences in metabolism. The crow is therefore not a surrogate model for toxicity testing in the place of the vulture. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Paraclinical Sciences / unrestricted

This study was designed to confirm the toxicity of a plant implicated in an outbreak in Frankfort, Free State Province, Republic of South Africa. Cows died acutely after being introduced into a camp, where an abundant, green shrublet was noted to be heavily grazed. The plant was subsequently identified as Senecio inaequidens DC. (Asteraceae) by the South African National Biodiversity Institute (SANBI). Extraction and chemical analyses for pyrrolizidine alkaloids (PA's) in Senecio inaequidens revealed the presence of four different compounds, namely retrorsine and senecionine (known to be hepatotoxic) and two unidentified compounds. The total alkaloid content (free bases plus N-oxides) in the dried, milled S. inaequidens plant material was 0.18%. Four (4) male Sprague Dawley rats, aged 8-9 weeks were dosed per os. Each rat received a different dose; ranging from 0.049 mg/g b.w. to 0.25 mg/g b.w.; of the crude Senecio inaequidens extract. No clinical signs were observed in the rat receiving the lowest dose. Rats receiving higher doses showed depression, an unsteady gait, pilo-erection and jaundice, which was particularly noticeable in the ears. Clinical chemistry evaluation revealed an increase in the activities of ALP, AST (except Rat 1) and GGT in all animals. Total serum bilirubin, creatinine and urea concentrations were also elevated. All rats had low serum globulin concentrations with an A/G ratio above 1.88 (except Rat 1). Post mortem examination of the rats revealed marked hepatic lesions. Histopathological changes were characterized by necrosis (variable in extent) of the centrilobular and midzonal hepatocytes, sparing the portal hepatocytes, with extensive haemorrhage and congestion. Proliferation of the bile ducts, fibrosis and oedema was also present. Ultrastructural changes in affected rats were characterized by margination of chromatin, the presence of numerous autolysosomes in necrotic hepatocytes, intramitochondrial woolly inclusions and changes in the endoplasmic reticulum. A sheep was also dosed in an attempt to reproduce the intoxication. The sheep did not exhibit clinical signs, clinical chemistry aberrations or macroscopic lesions. Histopathological and ultrastructural changes, although milder, were similar to those displayed by the rats. Pyrrolizidine alkaloids were extracted from the liver and kidneys of the rats and sheep. Retrorsine was also detected in the lungs, urine and bile of the sheep. / Dissertation (MSc (Paraclinical Science))--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

The burden of ticks in semi-arid lands of Ethiopia is not as pronounced as in some more humid areas of the continent. Nevertheless, the increasing recourse to chemicals smuggled by illegal traders has led to serious problems, including poisoning of humans and animals, discontinuous and irrational treatment regimens, tick-resistance to acaricidal products, loss of traditional knowledge and weakening of social structures. In order to encourage a resumption of the long-established ethnoveterinary practices, a survey on plants locally used in tick control was undertaken, and plant species used in other parts of the continent for the same purpose were considered. On these bases, 28 plant species or varieties were collected in the study area: Acacia seyal var. seyal, Adenium somalense, Aloe calidophila, Aloe parvidens, Azadirachta indica, Boscia angustifolia, Calotropis procera, Calpurnia aurea, Cissus quadrangularis, Commiphora erythraea, Cordia africana, Croton macrostachys, Croton megalocarpus, Datura stramonium, Euphorbia candelabrum, Euphorbia tirucalli, Ficus sycomorus, Ficus thonningii, Lantana camara, Maerua triphylla, Ocimum suave, two varieties of Ricinus communis (one with green fruits and another with red ones), Solanum incanum, Solanum somalense, Sterculia rhynchocarpa, Tagetes minuta and Vernonia amygdalina. In general, leaves were collected and used. However, due to the scarcity of foliar material, the whole plant of T. minuta and O. suave, the whole stem of A. somalense and C. quadrangularis, the branches of E. candelabrum and E. tirucalli, the bark in the case of A. seyal, C. erythraea and S. rhynchocarpa, were examined. After drying and grinding, the plant material was extracted with hexane and acetone, and made up to different concentrations to test the relevant repellent and toxic properties on adult Rhipicephalus pulchellus unfed ticks. For every bioassay, four replications, each using ten ticks, were performed. For the repellency bioassays, ticks were placed on a rectangular polystyrene platform stuck in a plastic basin and surrounded by water, in order to prevent them from moving away. Two glass rods, each provided with filter paper at the top and at the base, were inserted at opposite edges of the platform. The two filter papers of one rod were impregnated with the testing solution (i.e. solvent plus extract) at different concentrations while those of the other rod were treated with the pertinent extractant (hexane or acetone). Because of their inherent tendency to climb, most of the ticks settled onto the rods (mainly at the top), and their distribution was different depending on the repellency capacity of the extracts. The relevant data were then converted into repellency indexes using the formula [(Nc - Nt)/(Nc + Nt)] x 100, where Nc refers to the number of ticks on the control rod and Nt to the number of ticks on the test rod (Lwande et al., 1999; Pascual-Villalobos and Robledo, 1998). For the toxicity bioassays, 1 ìl of the extract at different concentrations was placed onto each tick and the mortality or weakening ratio was recorded after 24 hours. Because of the intrinsic toxicity of hexane, only acetone extracts were used for these assays. Due to the efficacy in extracting volatile compounds, hexane extracts had, for 24 plant species, better repellent properties than acetone extracts. Moreover, at a concentration of 10%, four species had negative repellency indexes with hexane extracts and five with acetone ones. At such concentration, these extracts therefore seemed to attract the ticks rather than repel them. At a concentration of 10%, thirteen hexane and five acetone extracts had repellency indexes > 50. At a concentration of 5%, only five hexane extracts and no acetone ones exceeded this value. Finally, only one species had a repellency index > 50 with the hexane extract at a 1% concentration. The plants showing good repellency indexes with at least one of the two solvents were A. calidophila, C. quadrangularis, C. erythraea, C. macrostachys, C. megalocarpus, D. stramonium, L. camara, M. triphylla, O. suave, the two varieties of R. communis and T. minuta. Amomg them, from a practical point of view, it is suitable to concentrate on O. suave, T. minuta and, to a certain extent, A. calidophila. In fact, C. quadrangularis, C. erythraea, C. macrostachys, D. stramonium, M. triphylla and the two varieties of R. communis had good repellent properties using hexane extracts at 10%, but not at 5%. Because trees like C. erythraea, C. macrostachys, C. megalocarpus and M. triphylla are highly valuable in a very dry environment, an excessive exploitation can put them in danger. Since D. stramonium, L. camara and R. communis are toxic plants, their extracts can be a serious threat for both humans and animals. Furthermore, L. camara is one of the worst weeds in the world, making it very inappropriate for lands already subject to the problem of bush encroachment. For all these reasons, T. minuta and O. suave appear to be the most promising plants; moreover, they are very well known in Southern Ethiopia and occur widely all over the area. On the contrary, A. calidophila is limited to just some places and the cultivation of Aloe species needs special attention, so it is not very suitable for people with a nomadic lifestyle. Concerning the toxicity bioassays, C. aurea extracts yielded by far the best results. In fact, all the ticks used had severe movement impairment when put in contact with acetone extracts at the concentrations of 20% and 10%. At a 5% concentration, 85% of the ticks had the same symptoms. In a separate test, a 10% water extract had a similar effect on 30 ticks out of 40, demonstrating the ease of extraction and application of the active compounds. The plant is well known, mainly by the Borana pastoralists, and is resistant to drought. It is also well able to grow in overgrazed areas, and its cultivation does not require special skills. Some of the extracts of other species gave good or fair results in the toxicity bioassays but, apart from S. incanum, only at a very high concentration (20%). Further studies may include isolation and characterization of the active compounds from the best species, setting up of a suitable plan for livestock treatment, and organization of a production and distribution cycle of appropriate phytomedicines in the pertinent pastoral area. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

BACKGROUND Yellow fever (YF) is a non-contagious, mosquito borne haemorrhagic fever caused by a single-strand RNA flaviviruses. YF is endemic in the tropics primarily in South America and Africa although the vectors are present in Asia, Europe, Pacific and Middle East. Human beings serve as viraemic hosts for mosquito infection. YF carries a high burden of disease, particularly in developing countries with up to 200 000 cases reported annually and a case fatality rate of 20-50%.The pathogenesis is poorly understood and little research has been conducted .There is no known cure or specific treatment for YF and prevention remains the mainstay the public health approach in terms of effectiveness and cost. The World Health Organisation (WHO) conventions have made vaccination mandatory for travel to endemic countries to prevent outbreaks and transmission to susceptible individuals. YF vaccine is one of the oldest vaccines known and in use and is derived from an attenuated virus strain 17D originally produced in the 1930s. The vaccine has historically been considered effective and safe. However, severe life-threatening side effects to the vaccine have been reported in the past 20 years. Acute vaccinerelated viscerotropic (AVD) and neurotropic (AND) side effects have been reported globally particularly in the elderly. The adverse reactions typically present as YF- like illness resulting in multi-organ failure with death as a possible outcome. OBJECTIVES To estimate the immunogenicity and toxicity of 17D and 17DD YF vaccines by summarizing the available data from randomised controlled trials. STUDY DESIGN A summary of randomized controlled trials (RCT) of YF vaccine immunogenicity and safety and tolerability was obtained using standard meta-analysis methodologies. METHODS A comprehensive literature search was conducted in order to identify trial that met with predetermined inclusion and exclusion criteria. Features of each study were noted taking into account the type of vaccine used, the duration of follow up, assignment to intervention, blinding and randomization methods. Three studies were eventually pooled and effect size estimates reported in each study were noted and analysed using meta-analysis software, MIX. Reports on the side effects post vaccination were summarized and analysed. RESULTS The difference in outcomes between the standard 17DD YF vaccines intervention, traded as Arilvax ® and the 17D YF vaccines traded as YF-Vax ® and Stamaril ® was negligible in terms of effect size. Effect sizes that considered the means between the treatment and control groups demonstrated a difference that favoured the control group viz. Arilvax ®. The pooled results also showed significant publication bias most likely attributable to the small number of studies considered. The pooled and annotated forest plot supported the available literature in confirming the effectiveness of YF vaccines in conferring immunity. A summary of tolerability events CONCLUSIONS This study has confirmed the effectiveness of YF vaccines in terms of immunogenicity and also demonstrated that YF vaccines are well tolerated and safe The small number of study units considered in this study presented challenges for analysis and for interpretation but highlighted the need for more research to be conducted in this area. The results are in keeping with the existing body of evidence supporting the robustness of the immunological response to YF vaccination. The safety and tolerability of the vaccine established in this study was also consistent with known literature. There are important implications for further research and implementation that became evident such as the need for further studies to be conducted in African populations where the burden of disease is highest. / Dissertation (MSc)--University of Pretoria, 2010. / Clinical Epidemiology / unrestricted

Toxicity testing is moving from animal-based studies to faster, more ethical in vitro approaches that focus on mechanistic toxicology. The use of bisphenol A (BPA) replacement compounds is increasing and there is limited toxicity data available for these compounds in avian species. The overall goals of this thesis were to: a) determine if avian cell lines are suitable alternatives to primary hepatocytes for chemical screening; b) generate toxicity data for five BPA replacement compounds: bis(4-hydroxyphenyl)methane (BPF), bis(3-allyl-4-hydroxyphenyl)sulfone (TGSH), 7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane (DD-70), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (BPAF) and 4-hydroxyphenyl 4-isoprooxyphenylsulfone (BPSIP) in three in vitro models: primary chicken embryonic hepatocytes (CEH), double-crested cormorant (DCCO) embryonic hepatocytes (DCEH) and chicken LMH cell line; and 3) prioritize two replacements for early-life stage testing (ELS). LMH cells cultured as 3D spheroids, as opposed to 2D monolayer, had enhanced mRNA expression and CYP1A activity and were therefore used for screening. Additionally, an immortalized DCCO hepatic cell line, DCH22, was established, which may be useful for future avian toxicity testing. DD-70 and BPAF were the most cytotoxic across the three in vitro models. TGSH and DD-70 altered expression of genes associated with multiple toxicity pathways, but not estrogen response, and are potential non-estrogenic replacements. BPAF, BPF and BPSIP are potential estrogenic replacements. In general, the replacements were more cytotoxic and/or transcriptionally active than BPA. There was species-specific variability in toxicity; the replacements were more transcriptionally active in CEH compared to DCEH. LMH spheroids were more sensitive to estrogenic endpoints than CEH. DD-70 and BPAF were prioritized for ELS studies based on in vitro results. All of the replacements modulated the expression of genes related to bile acid regulation in vitro and an increase in gallbladder mass was observed in chicken embryos after exposure to DD-70 or BPAF. Overall, this thesis evaluated the utility of LMH cells cultured as spheroids as an animal free alternative for chemical screening, established a DCCO cell line, and generated novel cytotoxicity and gene expression data for five BPA replacement compounds in three in vitro avian models and determined ELS toxicity of two replacement compounds.

Clean and spiked sediment formulations of various silt sand and clay sand ratios were tested for toxicity using a bioassay that utilizes bioluminescent bacteria Measured toxicities of clean and copper sulfate–spiked sediments were negatively but nonlinearly related with percent silt and percent clay, but no significant relationship existed between measured toxicity and sediment composition for methyl parathion–spiked formulations Results suggest that solid phase sediment bioassays using bioluminescent bacteria may be useful for testing the toxicities of single contaminants in formulated artificial sediments of known particle size composition, and for repeated samples collected from the same site However, extreme caution must be taken when testing sediments of varying composition or which may be differentially contaminated or contain a suite of contaminants.

An ion-specific electrode measured cupric ion activity modulated by fulvic acid (FA) and pH in a series of modified Frog Embryo Teratogenesis Assay- Xenopus (FETAX) toxicity assays. Hydrogen ion concentration was the primary determinant of cupric ion activity, while FA played a smaller but significant role. Fulvic acid was a weak copper complexing agent at pH 5.50. At pH 5.50 there was slight reduction of ionic activity and a subsequent attenuation of copper toxicity with 5.0 mg/L FA. At pH 7.50, FA also had a mild attenuating effect on copper toxicity. At pH 6.50, copper was strongly complexed by FA at total copper (TCu) concentrations below its pH-dependent solubility limit. At TCu concentrations above the solubility limit FA enhanced toxicity. There was more cupric ion activity measured in the presence of 0.5 and 5.0 mg/L FA than without it at TCu concentrations above the solubility limit. The proposed mechanism for this behavior was FA action as a nucleation inhibitor. Under the chemical conditions of the pH 6.50 experiments, a stable supersaturation of copper was formed, resulting in a more toxic aqueous matrix.