Lead was shown to inhibit both callus initiation and callus growth in cultures of Daucus carota L. subsp. sativus (Hoff. Thell.) cv. Nantes ''Tiptop'' and ''Nanthya''. Taproot explants of Daucus carota were stressed with lead. The callus cell lines which initiated under this stress were shown to exhibit resistance to the effects of lead ions. The growth of the selected and nonselected cell lines on non-lead containing media was comparable and the resistance possessed by the selected cell lines did not result in reduced growth rates in the presence of lead. The resistance characteristic was shown to be stable and to be successfully transmitted over mitotic and meiotic barriers. Plants were regenerated from the selected cell lines and ion uptake studies were conducted on isolated cortical tissue from mature taproots. The uptake of lead into the cortical cell tissue from the selected lines was shown to be reduced and a greater proportion of the lead that did enter the tissue was present in the Apparent Free Space and did not enter the cells. The regenerated plants were self-pollenated to produce an F1 generation. F1 plantlets were grown in hydroponic culture containing various concentrations of lead. The selected plants were seen to be resistant to the lead stress. The sites of lead accumulation in these roots were determined using x-ray microanalysis in a scanning electron microscope with a cryo-stage. The lead was found to be associated with the epidermal layer and cell walls. The mechanism of the lead resistance is discussed along with the implications of selection for somaclonal variants from initiating callus cultures.

The contents of this thesis describes the development of an analytical method to determine the chemical speciation of heavy metals in soils contaminted by sewage sludge and distillery wastes. Chapter one serves as an introduction discussing the various heavy metal species that can occur in soils. The chapter also contains a review of the analytical methods that have already been used in speciation studies and discusses their suitability for this particular problem. Chapter two is mainly concerned with the derivation of a relationship between the electrical conductivity and ionic strength of soil solutions. Chapter three describes the development of suitable sampling techniques for the study of chemical speciation in soils. Chapter four describes rhe development of the size Exclusion Chromatography (SEC) separation technique chosen to separate the species of interest. The chapter also describes how this technique was interfaced to Graphite Furnace Atomic Absorption Spectrometry in order to detect the copper content of the various soil solution species. Chapter five extends the above technique to the studv of the long term partioning of copper in water extracts of sewage sludge and distillery waste polluted soils and compares the results with those obtained from previous studies on the same sampling sites. Chapter six investigates the possibility of utilizing Inductively Coupled Plasma Optical Emission Spectrometry as a detector for the SEC separation technique. Chapter seven contains suggestions for future research.

Models of aqueous metal speciation and ecotoxicity have become commonplace due to their ability to estimate metal behaviour. This study evaluated commonly used aqueous geochemical speciation and ecotoxicity models with application to a mine impacted lake in northern Manitoba. The geochemical speciation model Winderemere Humic Aqueous Model (WHAM) was compared with Diffusive Gradients in Thinfilm (DGT) measurements of zinc and copper. DGT measurements in the water column corresponded well with WHAM-estimated Zn2+, Cu2+ was off by up to 100x. Additional metal, either from small organic bound species or dissolution of metal sulphides from resuspended sediment, served to improve model estimates. The single metal Biotic Ligand Model (BLM) predicted acute toxicity to Daphnia magna attributable to copper but not zinc, at low pH (3.55 – 5.5). Comparison of results did not show a significant difference between the single and mixture BLMs, suggesting a non-interactive effect on metal toxicity for measured water chemistry.

Models of aqueous metal speciation and ecotoxicity have become commonplace due to their ability to estimate metal behaviour. This study evaluated commonly used aqueous geochemical speciation and ecotoxicity models with application to a mine impacted lake in northern Manitoba. The geochemical speciation model Winderemere Humic Aqueous Model (WHAM) was compared with Diffusive Gradients in Thinfilm (DGT) measurements of zinc and copper. DGT measurements in the water column corresponded well with WHAM-estimated Zn2+, Cu2+ was off by up to 100x. Additional metal, either from small organic bound species or dissolution of metal sulphides from resuspended sediment, served to improve model estimates. The single metal Biotic Ligand Model (BLM) predicted acute toxicity to Daphnia magna attributable to copper but not zinc, at low pH (3.55 – 5.5). Comparison of results did not show a significant difference between the single and mixture BLMs, suggesting a non-interactive effect on metal toxicity for measured water chemistry.

The Canada-wide Standards for Petroleum Hydrocarbons (PHC CWS) in soils are remedial standards based on four petroleum distillates (Fraction 1 [F1; ECN C6-C10], Fraction 2 [F2; ECN >C10-C16], Fraction 3 [F3; ECN >C16-C34], and Fraction 4 [F4; ECN >C34-C50]). Knowledge gaps regarding petroleum toxicity to soil organisms were identified including concerns that the ecological values for F3 were overly conservative, possibly due to differences in toxicity between the low and high boiling point constituents of this distillate, and unexpected less-than-concentration-additive toxicity of binary mixtures of distillates to earthworms. An understanding of petroleum toxicokinetics with soil organisms was also needed to interpret toxicity results. Toxicity studies with one plant and two invertebrate (earthworm and collembolan) species were conducted with F3 and two subfractions of F3, F3a (ECN >C16-C22) and F3b (ECN >C22-C34), to determine if the toxicities of F3a and F3b were sufficiently different to recommend regulating the two separately. The difference in toxicities between the two was generally within the range of variability noted for the toxicity tests and thus it was not recommended to regulate the two separately. The toxicity data indicated that the exposure duration of standard test methods may be insufficient for determining the toxicity of higher distillate ranges. Toxicokinetic studies conducted with earthworms and F2, F3a, and F3b confirmed that standard test durations generally were not of sufficient duration to attain maximum body residues with F3b and sometimes F3a. Internal exposure scenarios also differed among distillates, with various accumulation curves noted and attributed to differences in loss of distillate from the soil and changes in bioavailability. Aromatics were disproportionally accumulated by earthworms relative to the ratio of aromatics to aliphatics in soil, suggesting that aromatics were the main contributors to earthworm toxicity. Toxicity and toxicokinetic studies with binary combinations of F2, F3a, and/or F3b and earthworms demonstrated that, on a soil concentration basis, toxicity was less-than-additive. Toxicokinetics indicated that this was due to a decrease in the bioavailability of distillates when a second distillate was present presumably as a non-aqueous phase liquid. However, on an internal tissue concentration basis, results were closer in agreement with concentration-addition.

Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are major constituents of crude oil, and the 3-5 ringed alkyl-PAHs have been identified as the main components chronically toxic to fish. While chysene homologues have higher cytochrome P4501A (CYP1A) induction potencies than alkyl-phenanthrenes, there is little characterization of toxicity for 4-ringed alkyl PAHs. This study measured the chronic toxicity of chrysene, benz[α]anthracene, and some alkylated congeners to the embryos of Japanese medaka (Oryzias latipes) using the partition-controlled delivery method (PCD) of exposure. This exposure method relies on the partitioning of chemicals from polydimethylsiloxane (PDMS) films, loaded with various concentrations of test chemical, to embryo rearing solutions. The objectives of this thesis were: (1) to further characterize the PCD method with a series of 4-ringed PAHs; (2) to evaluate the effects of different chemical structures on the toxicity of test compounds; and (3) to extend structure toxicity relationships from alkyl-phenanthrenes. The PCD method generated a gradient of aqueous concentrations for test compounds, and these exposure concentrations were maintained constant for the 17-day period. Benz[α]anthracene showed higher toxicity than chrysene. Toxicity increased with the degree of alkylation on the ring structures, except that 2-methylbenz[α]anthracene was less toxic than the unsubstituted benz[α]anthracene. Substitutions at the middle region contributed to a higher toxicity than substitutions at the distal region. While actual mechanisms for these compounds to cause toxicity are unknown, the narcotic mode of action seems to be not involved due to the lack of mortality. Within the range of test concentrations, the chronic sublethal toxicity was limited by the low solubility of the test compounds. A structure toxicity relationship was illustrated by the regression between log EC50s and log Kow values. In addition to hydrophobicity represented by log Kow, structural dissimilarities between compounds and physical characteristics such as aqueous solubility limits should be taken into account in toxicity assessments with alkyl-PAHs. This research is the first toxicological assessment of alkyl-chrysenes and benz[α]anthracenes which is essential for a better understanding of structure toxicity relationships of alkyl-PAHs, and will contribute to more accurate ecological risk assessments of PAH contamination. / Thesis (Master, Biology) -- Queen's University, 2014-01-10 16:35:00.232

Statins are the mainstay of cholesterol-lowering therapy and are taken by millions of people worldwide. These drugs are generally well-tolerated but can cause myopathy ranging from mild muscle pain to fatal rhabdomyolysis. The mechanism of statin-induced myopathy (SIM) is not fully understood and there is currently no convenient and reliable marker of SIM, but mitochondrial dysfunction has been implicated. We sought to investigate the effect of statins on mitochondrial DNA (mtDNA) levels in order to gain information on the mechanism of SIM and to explore the possibility of utilizing changing mtDNA levels as a marker of SIM. Several approaches were used. First, mtDNA levels were quantified in skeletal muscle biopsies collected from a previously published 8-week clinical trial of high-dose simvastatin or atorvastatin versus placebo. Forty-eight hypercholesterolemic subjects were randomly assigned to receive placebo (N=16), high dose atorvastatin 40mg/day (N=16), or high dose simvastatin 80mg/day (N=16) for 8 weeks. Muscle mtDNA content was assessed by real-time PCR atbaseline and after 8-weeks on statin treatment and found to be significantly reduced in the groupreceiving simvastatin (P=0.005) but not the other two. In addition, a significant positive correlation was observed between mtDNA and muscle ubiquinone in all groups (R=0.63, P<0.01), with the strongest association found in the simvastatin-treated subjects (R=0.75, P=0.002). Next, in an attempt to determine whether statin-induced muscle pain may be associated with muscle mtDNA depletion, archived muscle biopsies collected from statin users with muscle complaints were sought through a review of a muscle biopsy database and possible study samples were identified; however, this was put on hold as too much information was missing from the pathology reports. Third, a series of cell culture experiments were carried out in which human skeletal muscle myotubes were exposed to various concentrations of simvastatin or atorvastatin, in order to determine an appropriate dose range for subsequent mitochondrial toxicity experiments. Lastly, mtDNA content and expression was quantified in skeletal muscle biopsies collected from 10 patients with statin-induced rhabdomyolysis (SIR) and compared to 8 healthy controls to investigate whether muscle mtDNA is altered in rhabdomyolysis. No differences in mtDNA content or expression were observed between the two study groups, but this may have been be due to the SIR subjects' marked heterogeneity. Statin therapy can be associated with considerable alterations in mtDNA content, which may play a role in the aetiology of SIM. MtDNA levels alterations with statin exposure should be investigated further to explore the involvement of mitochondrial alterations in the mechanism of SIM, and determine whether these may represent a useful clinical tool for assessing statin-induced muscle toxicity.

Background: A third of HIV-infected patients are co-infected with HCV in the developed world, and more of co-infected patients than ever before are dying because of liver related diseases today. Drug-related hepatotoxicity is a growing concern among human immunodeficiency virus (HIV) / hepatitis C virus (HCV) co-infected population. Nucleotide analogues containing HIV antiretroviral therapy, namely highly active anti-retroviral therapy (HAART), can induce mitochondrial toxicity. However, little is known about the effect of nucleotide analogues on the liver at the cellular and molecular level, and how it may affect treatment. Objective: To investigate whether liver tissue from HIV/HCV co-infected individuals will show greater liver mitochondrial toxicity if currently receiving antiviral HIV medication, compared to those who are not taking it. Methods: Liver biopsies were collected from 23 HIV/HCV co-infected males. Fourteen patients were on stable HAART (ON-HAART) and 9 were OFF-HAART, including 4 who stopped HAART >6 months prior and 5 who were HAART-nave. Liver mitochondrial toxicity was assessed by transmission electron microscopy-based quantitative stereological analyses of hepatocyte and mitochondrial morphometry, as well as by mitochondrial DNA (mtDNA) and mtRNA (COX1/(ß-actin) real-time-PCR quantification. Results: Hepatocytes tended to be larger in the ON-HAART group than in the OFF-HAART group (p=0.05), but they both showed similar mitochondrial volume fraction of the cell and mitochondrial crista density. Liver mtDNA and mtRNA levels were not significantly differentbetween ON-HAART and OFF-HAART. Hepatocyte lipid accumulation was significantly higher in HCV genotype 3 compared to genotype 1 infection ()=0.002), but was not associated with HAART status. Conclusions: We found no evidence or trend of increased mitochondrial toxicity in HIV/HCV co-infected individuals currently on HAART compared to those who are not. This finding could be relevant to the decision-making process with respect to initiating HCV therapy in this population.

The spectrum of drugs used in HIV-infected patients has dramatically changed since triple antiretroviral combinations were introduced, albeit at the expense of some severe adverse events, in 1996. Long term complications of antiretroviral drug exposure, such as HIV lipodystrophy, as well as organ-specific disease of heart and bone are, therefore, a critical issue when designing antiretroviral regimens. Because it is difficult to predict the occurrence of lipodystrophy, and because there is no therapeutic agents able to combat lipodystrophy once established, avoidance of thymidine nucleoside analogues remains the most useful strategy to prevent and treat lipoatrophy; although this approach can worsen dyslipidaemia. Metabolic syndrome can and should be assessed as it predicts type 2 diabetes as well as cardiovascular events in HIV-infected individuals. Ongoing HIV replication is a risk factor for serious non-AIDS events including cardiovascular disease, as well as for AIDS. Therefore, HIV RNA suppression is imperative in all patients requiring antiretroviral therapy. Finally, HIV-infected adults on antiretroviral therapy, particularly in those receiving a boosted protease inhibitor, have a high prevalence of low bone mineral density. The estimation of fracture risk with the WHO FRAXTM tool deserves further validation in HIV-infected adults.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 171-183). Also available via the Internet.