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.

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.

Obesity is a prevalent disease in which, when compared to individuals of normal weight, obese individuals have noted pathophysiological alterations including increased adiposity and fat mass which may alter toxicokinetics of xenobiotics and therefore alter their toxicities. However, the effects of obesity and the altered pathophysiology accompanying this condition on the toxicity of many widely utilized pesticides have not been established. Organophosphate (OP) pesiticides, including chlorpyrifos (CPS), have historically been widely used for agricultural purposes. CPS and several other notable OPs are no longer registered for household use but still used mainly in agriculture by registered users. CPS is bioactivated to form chlorpyrifos-oxon (CPO) in liver by cytochrome P450 isozymes. Acute toxicity of CPS exposure is inhibition of acetylcholinesterase (AChE) in the central and peripheral nervous systems. The other targets following CPS exposure are the noncholinergic serine hydrolase enzymes: carboxylesterase (CES), fatty acid amide hydrolase (FAAH), and monoacylglycerol lipase (MAGL). Therefore the current study was designed to: 1) determine the time and concentration-dependent effects of CPS on noncholinergic endpoints of OP toxicity utilizing hepatoma cells under normal and steatotic conditions 2) determine if obese phenotype altered the toxicity of CPS, including both cholinergic and non-cholinergic endpoints and 3) determine the effects of high fat diet on CPS bioaccumulation and detoxication by determining CPS and 3,5,6-trichloro-2-pyridinol (TCP) levels at different time points. The current in vitro studies determined that CES is more sensitive to CPS mediated inhibition in normal and steatotic conditions compared to FAAH and MAGL. The in vivo studies determined that CPS (2 mg/kg) exposure produced a greater inhibitory effect on hepatic CES and FAAH in obese animals compared to lean animals which indicates that the obese animals may be at greater risk for CPS mediated alterations in hepatic lipid metabolism upon chronic exposure. Our toxicokinetic studies using a higher dose of CPS (25 mg/kg) did not inhibit AChE in CNS and did not alter the overall CPS levels between normal and obese animals. Peak levels of TCP were decreased in liver of obese animals at 3 hours and overall hepatic TCP levels were significantly decreased in obese animals.

Although the production of polychlorinated biphenyl (PCB) technical mixtures has been banned in the U.S. since the 70’s, they remain ubiquitous in the environment, particularly in indoor and ambient air. Due to the presence of PCB’s in air, inhalation is a significant route of exposure. PCBs released from various building materials have been shown to contaminate the indoor air in homes and schools. In the AESOP Study, an epidemiologic study of PCB exposures among school children and their mothers, PCB28 was found in the serum of over 20% of participants. Data are lacking on the absorption, distribution, metabolism, and excretion (ADME) of inhaled PCBs and on the biological fate and dose-specific toxicological endpoints. In order to inform toxicokinetic modeling for risk-assessment, we are conducting ADME toxicological studies with lung exposure to a representative trichlorobiphenyl, and evaluating the uptake from the lung and the distribution, metabolism, and excretion. Male Sprague-Dawley rats were exposed to [14C]PCB28 via intratracheal instillation at two different doses (42 µg/rat and 4.2 µg/rat). Digestive matter from five separate compartments of the gastrointestinal tract and thirty-six tissue types were excised and measured by scintillation counting. Exhaled air and excreta were also collected and analyzed. Measurements for the high dose were made at 12, 25, 50, 100, 200, 400, 720, and 1440 min, and for the low dose at 2, 12, 50, 200, and 720 min post-exposure. Data show that pulmonary uptake exceeded 99% in both doses. [14C]PCB28 entered the blood stream and distributed quickly to all tissues within minutes of dosing. In the high dose, the majority of radioactivity initially went to the muscle and liver, while in the low dose [14C]PCB28 initially distributed to the muscle, esophagus, and trachea, before being redistributed to the skin and adipose tissue, where it accumulated in both doses. In most tissues, elimination was biphasic, consisting of an initial fast phase with a half-life (t1/2) of 7-93 min (high dose) and t1/2 of 6-60 min (low dose), followed by a slower phase with t1/2 of 5-18 hours (high dose) and t1/2 of 3-18 hours (low dose). The metabolism of PCB28 was not extensive, with the parent compound as the major component in liver, kidney, serum, and adipose tissue. Excretion via urine and feces was limited, with 92% (high dose) and 88% (low dose) of radioactivity remaining in the tissues by the end of the time course, primarily in skin and adipose tissue. Low urinary concentration relative to serum, suggested that parent PCB28 in serum would serve as an accurate biomarker for assessment of exposure to inhaled trichlorobiphenyls. The time course and tissue distribution is comparable to [14C]PCB11, while metabolism and excretion of [14C]PCB28 is much less extensive.

Bitumen extraction in the Athabasca oil sands in Alberta releases metals to the region. In this study, I performed an uptake-elimination experiment with wood frog tadpoles (Lithobates sylvaticus) to determine the bioaccumulation potential of metals from exposure to MacKay River sediment, an area affected by oil sands contamination, and to uncontaminated reference sediment. Wood frog tadpoles, Gosner stages 28-32, were exposed to two sediments: (1) MacKay River sediment that is enriched in petrogenic hydrocarbons from natural and anthropogenic sources; and (2) an uncontaminated reference sediment. Tadpole exposures to sediments lasted 4 days, followed by a depuration phase for an additional 4 days where tadpoles were allowed to eliminate excess metals from their bodies. The metal concentrations at various time points during the uptake and elimination phases were determined in order to define toxicokinetic parameters, such as uptake and elimination first order rate constants, accumulation by ingestion, and assimilation efficiencies for specific metals. It was determined that tadpoles exposed to the MacKay sediment had higher concentrations of Al, Co, Cu, Cr, Mg, Ni, Pb, V, and Zn throughout the uptake phase of the study compared to tadpoles exposed to reference sediment. We also observed little to no decrease in concentrations of Al, Co, Cu, Cr, Mg, Ni, Pb, V, and Zn throughout the elimination phase of the study. In addition, biota-sediment accumulation factors (BSAF) revealed that Cu, Zn, Cr, and V had among the highest bioaccumulation potential in our trials. The experiment was subsequently repeated by preventing direct contact of the tadpoles to sediment with a screen, exposing tadpoles only to metals in water. By comparing tadpole exposures to metals from ‘aqueous’ and ‘aqueous +sediment’ in separate trials, and by tracking sediment ingestion rates, I am able to show that sediment ingestion constitutes the primary source of metal bioaccumulation by tadpoles. Not only were metal concentrations higher in tadpoles that were ingesting sediment, but they also had greater metal uptake rates compared to tadpoles that were only exposed to contaminated water. It was also determined that assimilation efficiencies were higher in tadpoles exposed to reference sediment compared to ones exposed to MacKay River sediment. Using toxicokinetic parameters defined by the uptake-elimination experiment, I developed a computational model using STELLATM system dynamics software to accurately estimate first order uptake and depuration rate constants for metals in exposed aquatic animals. The model estimated metal uptake and depuration kinetics with a mean relative error of 2.25 ± 0.93 % (±SE, n=9) for the uptake study and 2.53 ± 2.61 % (±SE, n=9) for the depuration study. With increased oil-sands production anticipated, we recommend continued monitoring of contaminants from oil-sands for the purpose of understanding the potential risks they may have on northern Alberta’s ecosystems.

Pyrethroid insecticides applied on crops and in urban areas are being found in aquatic ecosystems due to natural processes, such as run-off. Although highly toxic to invertebrates and fish, populations of Hyalella azteca have become resistant to some of these compounds, which pose risks to not only their populations, but higher trophic level populations via bioaccumulation (in this thesis, the Inland silverside (Menidia beryllina)). Concurrently, the impact of global climate change (GCC) is impacting environmental water parameters, such as temperature and salinity. The objective of this thesis was to analyze the relationship between varying water parameters due to GCC on the fate of permethrin (a type of pyrethroid) in resistant H. azteca (by measuring toxicokinetic rates) and in M. beryllina (by measuring bioaccumulation after consuming permethrin-dosed resistant H. azteca). Permethrin bioconcentration testing used two distinct populations (Mosher Slough and Escondido Creek) of pyrethroid-resistant H. azteca and showed that temperature and salinity affected toxicokinetic rates. Statistical differences in metabolite formation rates (km) across temperatures were found between and within populations. Salinity also exhibited statistical differences in the elimination of parent compound (kep). No statistically significant differences in uptake rates (ku) were found for either population. In the M. beryllina testing, the ability for the fish to bioaccumulate permethrin via a dietary route of exposure was confirmed, contradicting previous findings. Statistically significant bioaccumulation was found across salinities, whereas no statistically significant temperature effects were observed. With the predicted increased use of pyrethroids over the course of the next century, the emergence of resistant populations of H. azteca may increase, simultaneously increasing the risk for bioaccumulation by higher trophic species. With rates of biotransformation in H. azteca affected by changing water parameters due to GCC change, the ratio of parent and metabolite compound transferred to fish will also be altered. Pyrethroid metabolites in fish act as endocrine disruptors rather than inhibit nerve function like the parent compound, which can significantly affect fish development. Overall, this thesis demonstrates important potential effects of GCC on the rates and biological transfer of pyrethroids by aquatic species, and the potential combined effects of these multiple stressors on two trophic levels of aquatic organisms.

Aux Antilles Françaises, les animaux d’élevage sont susceptibles d’être exposés à la chlordécone (CLD), Polluant Organique Persistant (POP) présent dans leur environnement. Afin de sécuriser les Denrées Alimentaires d’Origine Animale (DAOA) destinées à la consommation humaine, nos travaux ont porté sur l’étude du devenir de la CLD chez la brebis. Les objectifs de ces travaux étaient de comprendre comment s’effectue l’élimination de la molécule depuis l’organisme animal c’est-à-dire de déterminer par quelle(s) voie(s), sous quelle(s) forme (s), en combien de temps, en quelle quantité et par quels mécanismes s’élimine la CLD. Pour cette étude, deux volets ont été considérés : un volet analytique et un volet toxicocinétique. En effet, les méthodes de dosage connues des métabolites de la CLD ne permettaient pas d’obtenir la sensibilité et la fiabilité attendues pour nos travaux. Ainsi, un développement analytique de méthodes de dosage de la CLD et de ses métabolites dans les matrices d’intérêt a été mené. Ces travaux analytiques se sont appuyés sur une méthodologie d’extraction de type Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS), une analyse par chromatographie en phase liquide couplée à la spectrométrie de masse en tandem (LC-MS/MS) et l’utilisation d’étalons internes isotopiques. Ce développement permet de disposer de méthodes de dosage sensibles, rapides et fiables de la CLD et de ses métabolites dans différentes matrices animales. A l’issue de l’étape de développement analytique, les méthodes dans le foie, les fèces et les urines ont été validées à l’aide de profils d’exactitude établis selon la norme V03-110 et le guide SANTE de référence pour les pesticides. Pour exemple, dans la matrice foie, des limites de quantification de 1,36 µg kg-1 PF et de 2,50 µg kg-1 PF respectivement de chlordécone et de chlordécol (métabolite de la CLD) ont été retrouvées. Le deuxième volet de cette thèse s’est appuyé sur deux protocoles toxicocinétiques réalisés chez la brebis. A l’aide de ces expérimentations, il a été possible de combler une partie des lacunes sur la toxicocinétique de la CLD chez la brebis. Nos travaux ont démontré que la CLD est partiellement métabolisée en chlordécol (CLDOH) par la chlordécone réductase dans le foie des brebis. Par la suite, la CLD et le CLDOH peuvent être métabolisés à l’aide d’UDP-glucuronosyl-transferases et de sulfo-transferases en métabolites conjugués de la CLD et du CLDOH (CLD-C et CLDOH-C). Le CLDOH est un métabolite intermédiaire qui n’est quasiment jamais quantifié dans l’organisme animal hormis dans le tissu gras. L’élimination de la CLD se fait majoritairement via les fèces : 1/3 de la molécule parent CLD est éliminé sous forme de CLD et 1/6 est éliminé sous forme de CLDOH. La voie urinaire est une voie mineure d’élimination de la CLD. A l’aide de ces travaux, un modèle compartimental a été proposé. Sur la base de ce modèle, des travaux de modélisation seront possibles et permettront la proposition et la mise en place de stratégies de décontamination des ovins aux Antilles Françaises / In the French West Indies (FWI), farming animals can be exposed to CLD, a persistent organic pollutant (POP) bound to soil in contaminated areas. In order to produce safe animal products, this thesis was focused on the CLD’s fate in ewes. The aims were to determine by which way(s), in which form(s), in how much time, in which quantities and by which mechanisms, CLD would be eliminated from the animal body. In this thesis, two complementary approaches were followed. First it was necessary to improve the analytical methods especially for the metabolites in order to obtain more sensitive and reliable methods than the actual ones. In the analytical approach, methods for CLD and its metabolites were developed in various animal matrices suitable for the toxicokinetic studies. The extraction method was based on the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) methodology and the analysis was performed with a liquid chromatography with tandem mass spectrometry (LC-MS/MS). Isotopic Standards were also used. Thanks to this work, sensitive, quick and reliable methods were obtained in animal matrices. The set-up methods in liver, feces and urine were validated with accuracy profiles according to the French Standard NF V03-110 and European Union guidelines. Limits of quantifications of 1.36 μg kg−1 and 2.50 μg kg−1 of fresh liver were respectively found for chlordecone and chlordecol (the CLD’s metabolite). Secondly, and thanks to the analytical development, in vivo toxicokinetic studies were performed to determine the fate of CLD in ewes. The second approach of this thesis was based on two toxicokinetic protocols realized in ewes. The results revealed that CLD is partially metabolized in chlordecol (CLDOH) by the chlordecone reductase in ewe’s liver. Then, CLD and CLDOH can be conjugated by UDP-glucuronosyl-transferases and sulfo-transferases in conjugated metabolites (CLD-C and CLDOH-C). It appeared that CLDOH is only an intermediate metabolite which is almost never quantified in the organism except in fat tissue. The major route of CLD elimination is in feces: 1/3 of the molecule is eliminated in its CLD’s form and 1/6 in its CLDOH’s form. The urinary way of CLD elimination is minor. Based on the obtained results, a compartmental model was proposed. It will allow to propose and to establish ovine decontamination strategies in the FWI

This study was designed to observe the effects of selenium from plant material in sheep after a single, oral dose. Purified sodium selenite and selenomethionine were given as positive controls. The plant Symphyotrichum spathulatum (Western Mountain Aster) was collected, analyzed for selenium content, and administered orally to sheep at varying doses according to body weight. Clinical signs were observed for 7 days during which time whole blood, serum, and expired air were collected. Following euthanasia, tissues were collected for histopathological analysis and mineral analysis. Clinical signs were less apparent than expected and included depression and mild dyspnea in sheep receiving the highest doses of selenium as plant material, whereas pathologic lesions were prominent. Acute myocardial degeneration and necrosis was most severe in the highest dose animals, but present to lesser degrees as dose decreased. Pulmonary lesions of edema and congestion were less frequently observed. Thirteen animals died prior to study completion. Selenium concentration in tissues, brain, liver, kidney cortex, atrium, ventricle, and skeletal muscle, increased with increasing dose of plant material. Treatment had a significant impact on selenium concentration in all tissues collected for mineral analysis (P < 0.01). Whole blood and serum were collected to study the toxicokinetics of selenium in these sheep. Serum kinetic parameters that increased significantly with increasing dose included the elimination rate constant, peak selenium concentration, and area under the selenium concentration versus time curve. Serum kinetic parameters that significantly decreased with increasing dose included the absorption and elimination half-lives. Whole blood kinetic parameters that increased significantly with increasing dose included the elimination rate constant, peak selenium concentration, and area under the curve. Expired air was collected to study the respiratory toxicokinetics of selenium in the sheep. The selenium concentration in expired air from sheep receiving selenomethionine was significantly greater than all other treatments (P < 0.0001) at all collection time points. But an intriguing finding was the dramatic differences in elimination profile curves as selenium dose increased with the plant material. The highest dose group elimination curve continually increased through all collection time points. All other groups dosed with plant material saw a decrease in selenium elimination by the last collection time point.

<p>Metotreksat kao antagonista folne kiseline ima &scaron;iroku upotrebu za lečenje brojnih maligniteta, primenjen u visokim dozama i u&nbsp; kombinciji&nbsp; sa leukovorinom. Iako&nbsp; je&nbsp; terapija&nbsp; visokim&nbsp; dozama&nbsp; metotreksata drastično pobolj&scaron;ala&nbsp; prognozu pacijenata sa malignitetom, te&scaron;ki neželjeni efekti terapije predstavljaju stalan klinički problem. Ciljevi istraživanja bili su određivanje serumske koncentracije metotreksata i izračunavanje farmakokinetičkih&nbsp; parametara&nbsp; metotreksata kod dece obolele od malignih&nbsp; bolesti&nbsp; koja su na terapiji visokim dozama metotreksata (2&nbsp; g/m² i&nbsp; 5&nbsp; g/m² ); ispitivanje postojanja uticaja primenjene doze metotreksata, demografskih i kliničkih karakteristika ispitanika&nbsp; na koncentracije i farmakokinetičke parametare. Ispitivano je prisustvo i stepen kliničkih i laboratorijskih znakova toksičnosti metotreksata, kao i uticaj primenjene&nbsp; doze&nbsp; metotreksata&nbsp; i demografskih karakteristika ispitanika&nbsp; na pojavu i stepen toksičnosti . U okviru retrospektivno - prospektivne&nbsp; studije&nbsp; ukjučeno&nbsp; je&nbsp; četrdeset&nbsp; i dva pedijatrijska&nbsp; pacijenta&nbsp; uzrasta od&nbsp; 0,75 do 17,75 godina (medijana 5,75&nbsp; godina). Svi pacijenti&nbsp; su lečeni&nbsp; u&nbsp; Službi&nbsp; za&nbsp; hematologiju i&nbsp; onkologiju&nbsp; Instituta&nbsp; za&nbsp; zdravstvenu za&scaron;titu dece i omladine Vojvodine (Novi Sad, Srbija) u periodu od juna 2004. godine do juna 2012. godine. Trideset i osam ispitanika&nbsp; je lečeno pod dijagnozom akutne limfoblastne leukemije&nbsp; prema dva&nbsp; uzastopna&nbsp; protokola ALL IC - BFM 2002 i ALL IC - BFM 2009 Internacionalne&nbsp; BFM studijske&nbsp; grupe &bdquo;I - BFM - SG&ldquo;&nbsp; (International Berlin -Frankfurt - M&uuml;nster Study Group) za proučavanje i lečenje dečje non-B akutne limfoblastne leukemije. Četvoro je&nbsp; imalo&nbsp; dijagnozu non - Hodgkin limfoma&nbsp; i bili su uključen i u&nbsp; protokol NHL - BFM&nbsp; 95. Istraživanje je obuhvatilo 113 ciklusa terapije metotreksatom (1&ndash; 4 ciklusa po pacijentu) sa 386 izmerenih serumskih koncentracija metotreksata. Raspon primenjenih doza metotreksata kretao se od 800 do 10.000 mg. Koncentracije metotreksata su merene 24, 36 i 42 sata nakon započinjanja infuzije metotreksata, a po potrebi i u dužim vremenskim intervalima. Za izračunavanje farmakokinetičkih parametara kori&scaron;ćen je dvokompartmanskih farmakokinetički&nbsp; model posle obustavljanja&nbsp; intravenske&nbsp; infuzije,&nbsp; gde&nbsp; postoje relacije&nbsp; za&nbsp; farmakokinetičke&nbsp; tačke. Podaci o kliničkim i laboratorijskim znacima toksičnosti metotreksata prikupljani su iz medicinske dokumentacije, a za stepenovanje toksičnosti kori&scaron;ćen je skor sistem - Common Terminology Criteria for&nbsp; Adverse&nbsp; Events (CTCAE), Version 4.0, U.S. Department&nbsp; of&nbsp; health&nbsp; and&nbsp; human services, National Institute of Health, National Cancer Institute. U cilju utvrđivanju uticaja karakteristika ispitanika, primenjene doze i prisustva produžene eliminacije na posmatrane parametre, vr&scaron;eno je poređenje tri grupe&nbsp; pacijenata (doza 2 g/m² bez produžene eliminacije, 5 g/m² bez produžene liminacije i 5 g/m² sa produženom eliminacijom metotreksata). Za celokupnu grupu ispitanika,&nbsp; medijane&nbsp; koncentracije metotreksta&nbsp; bile&nbsp; su 25,82 &mu;mol/l u 24. satu, 0,68 &mu;mol/l u 36. satu i 0,24 &mu;mol/l u 42. satu merenja. Najizraženija interindividualna varijabilnost u koncentracijama metotreksata bila je u 42. satu merenja, dok je&nbsp; intraindividualna varijabilnost bila najizraženija u 36. satu merenja. Medijana&nbsp; klirensa&nbsp;&nbsp; metotreksata&nbsp;&nbsp; bila&nbsp; je 8,32&nbsp;&nbsp; l/h. Farmakokinetički parametri&nbsp; redom bili su:&nbsp; medijana&nbsp; volumena&nbsp; centralnog&nbsp; kompartmana V₁ 28,47&nbsp; l, medijane konstanti k₁₀ 0,206, k₁₂ 0,0245, k₂₁ 0,1114. Najizraženiji uticaj primenjene doze na koncentracije metotreksata pokazan je u 24.&nbsp; satu&nbsp; merenja, dok uticaj doze na klirens&nbsp; metotreksata nije&nbsp; pokazan. Prisustvo produžene eliminacije metotreksata dovodi do smanjenih vrednosti konstanta k₁₀ i k₂₁. Nije pokazana statistički značajna&nbsp; interakcija ispitivanih demografskih karakteristika (uzrast, telesna povr&scaron;ina i pol)&nbsp; i koncentracija metotreksata, kao ni klirensa metotreksata. Pokazana je značajna interakcija između koncentracija metotreksata i nivoa laktat dehidrogenaze, kao i klirensa metotreksata i nivoa kreatinina i laktat dehidrogenaze. Većina ispoljenih&nbsp; toksičnosti bila je umerenog stepena (&lt;3 stepena). Najzastupljeniji klinički znak toksičnosti bio je oralni mukozitis, koji je bio većeg stepena u grupi sa većom primenjenom dozom metotreksata&nbsp; (5g/m²). Najzastupljeniji&nbsp; laboratorijski toksični efekti&nbsp; metotreksata bili su leukopenija i anemija. Najteži stepeni laboratorijskih znakova toksičnosti (leukopenija, anemija, porast&nbsp; AST,&nbsp; ALT i GGT) nalazili su se u grupi sa većom dozom&nbsp; (5 g/m²) i&nbsp; sa produženom eliminacijom metotreksata. Osnov&nbsp; za&nbsp; kliničko&nbsp; vođenje&nbsp; pacijenata&nbsp; na&nbsp; terapiji visokim dozama metotreksata je terapijsko praćenje leka (therapeutic drug monitoring &ndash; TDM) zbog velikih&nbsp; interindividualnih i intraindividualnih&nbsp; varijabilnosti&nbsp; u&nbsp; farmakokinetici&nbsp; leka. Rutinsko praćenje koncentracija metotreksata važno je za identifikaciju pacijenata sa povećanim rizikom od razvoja toksičnosti ,&nbsp; te&nbsp; je TDM&nbsp; standardna&nbsp; praksa&nbsp; za smernice spasavanja leukovorinom, naročito za pacijente za koje se zna da imaju smanjen&nbsp;&nbsp; klirens metotreksata ili druge rizike povezane sa prolongiranim citotoksičnim koncentracijama (bubrežna ili jetrena o&scaron;tećenja, kolekcije tečnosti u &ldquo;trećem prostoru&rdquo;, gastrointestinalna opstrukcija). Veliki&nbsp; broj&nbsp; istraživanja&nbsp; kod pedijatrijskih pacijenata pokazao je vezu između sistemskog izlaganja metotreksatu i&nbsp; efikasnosti&nbsp; i&nbsp; toksiĉnosti&nbsp; metotreksata. Ipak, ne postoji dovoljno&nbsp; informacija o farmakokinetici metotreksata kod dece obolele od akutne limfoblastne leukemije. Takođe, ova istraživanja nisu do sada sprovođena kod dece koja su lečena u na&scaron;oj sredini.</p> / <p>Methotrexate&nbsp; is&nbsp; an&nbsp; antifolate&nbsp; drug&nbsp; widely&nbsp; used&nbsp; for&nbsp; treatment&nbsp; of&nbsp; various malignant&nbsp; tumours.&nbsp; It&nbsp; is&nbsp; used&nbsp; at&nbsp; high&nbsp; doses&nbsp; and&nbsp; in&nbsp; combination&nbsp; with leucovorin rescue.&nbsp; Although&nbsp; high - dose&nbsp; MTX&nbsp; therapy&nbsp; dramatically&nbsp; improves&nbsp; the&nbsp; prognosis&nbsp; of patients with malignancies, severe adverse events are constant clinical concern. The&nbsp; aims&nbsp; of&nbsp; this&nbsp; stydy&nbsp; were&nbsp; to&nbsp; determine&nbsp; the&nbsp; serum&nbsp; concentration&nbsp; of&nbsp; methotrexate&nbsp; and&nbsp; to&nbsp; calculate&nbsp; the&nbsp; pharmacokinetic&nbsp; parameters&nbsp; of&nbsp; methotrexate&nbsp; in children&nbsp; suffering&nbsp; from&nbsp; malignant&nbsp; deseases&nbsp; who&nbsp; are&nbsp; treated&nbsp; with&nbsp; high&nbsp; doses&nbsp; of metotrexate&nbsp; (2&nbsp; g/m² i&nbsp; 5&nbsp; g/m² );&nbsp; furthermore,&nbsp; to&nbsp; investigate&nbsp; the&nbsp; effects&nbsp; of&nbsp; the&nbsp; applied doses of methotrexate, and demographic and clinical characteristics of the examinees on&nbsp;&nbsp; the&nbsp;&nbsp; concentration&nbsp;&nbsp; and&nbsp;&nbsp; pharmacokinetic&nbsp;&nbsp; parameters&nbsp;&nbsp; of&nbsp;&nbsp; the&nbsp;&nbsp; drug.&nbsp;&nbsp; The&nbsp;&nbsp; study investigated the&nbsp;&nbsp; presence&nbsp;&nbsp; and&nbsp;&nbsp; the&nbsp;&nbsp; degree&nbsp;&nbsp; of&nbsp;&nbsp; clinical&nbsp;&nbsp; and&nbsp;&nbsp; laboratory&nbsp;&nbsp; signs&nbsp;&nbsp; of metotrexate&nbsp; toxicity,&nbsp; as&nbsp; well&nbsp; as&nbsp; the&nbsp; effect&nbsp; of&nbsp; the&nbsp; applied&nbsp; doses,&nbsp; and&nbsp; demographic characteristics of the examinees on the appearance and the degree of toxicity. The retrospective - prospective study included 42&nbsp; pediatric patients aged from 0.75&nbsp; to&nbsp; 17.75&nbsp; years&nbsp; (median&nbsp; 5.75&nbsp; years).&nbsp; All&nbsp; patients&nbsp; were&nbsp; threated&nbsp; at&nbsp; the&nbsp; Children and Youth Health Care Institute of Vojvodina (Novi Sad, Serbia), Hemathology and Oncology&nbsp; Section,&nbsp; in&nbsp; the&nbsp; period&nbsp; from&nbsp; June&nbsp; 20 04&nbsp; to&nbsp; June&nbsp; 2012.&nbsp; 38&nbsp; examinees diagnosed as acute lymphoblastic leukemia were treated according to two subsequent protocols,&nbsp; ALL&nbsp; IC - BFM&nbsp; 2002&nbsp; and&nbsp; ALL&nbsp; IC - BFM&nbsp; 2009&nbsp; of&nbsp; the&nbsp; International&nbsp; BFM study&nbsp; group &bdquo;I - BFM - SG&ldquo; (International Berlin - Frankfurt - M&uuml;nster&nbsp; Study&nbsp; Group)&nbsp; for management&nbsp;&nbsp; of&nbsp;&nbsp; childhood&nbsp;&nbsp; non - B&nbsp;&nbsp; acute&nbsp;&nbsp; lymphoblastic&nbsp;&nbsp; leukemia.&nbsp;&nbsp; 4&nbsp;&nbsp; examinees diagnosed&nbsp; as&nbsp; non - Hodgkin&nbsp; lymphoma&nbsp; were&nbsp; treated&nbsp; according&nbsp; to&nbsp; the&nbsp; NHL - BFM&nbsp; 95 protocol. The study included 113 cycles of therapy with methotrexate (1-4 cycles per patient)&nbsp; with&nbsp; 3 86&nbsp; measured&nbsp; serum&nbsp; concentrations&nbsp; of&nbsp; methotrexate.&nbsp; The&nbsp; range&nbsp; of&nbsp; the applied doses was between 800 and 10,000 mg. The&nbsp; concentration&nbsp; of&nbsp; methotrexate&nbsp; was&nbsp; measured&nbsp; 24,&nbsp; 36&nbsp; and&nbsp; 42&nbsp; hours&nbsp; after the initiation of the methotrexate infusion, as well as in longer time intervals when needed.&nbsp; To&nbsp; calculate&nbsp; the&nbsp; pharmacokinetic&nbsp; parameters,&nbsp; the&nbsp; study&nbsp; applied&nbsp; the&nbsp; two - compartment&nbsp; pharmacokinetic&nbsp; model&nbsp; after&nbsp; the&nbsp; termination&nbsp; of&nbsp; intravenous&nbsp; infusion, when&nbsp; relations&nbsp; for&nbsp; pharmacokinetic&nbsp; points&nbsp; existed.&nbsp; Data&nbsp; on&nbsp; clinical&nbsp; and&nbsp; laboratory signs of methotrexate toxicity were collected&nbsp; from medical documentation, and the Common&nbsp; Terminology&nbsp; Criteria&nbsp; for&nbsp; Adverse&nbsp; Events&nbsp; (CTCAE),&nbsp; Version&nbsp; 4.0,&nbsp; U.S. Department&nbsp; of&nbsp; health&nbsp; and&nbsp; human&nbsp; services,&nbsp; National&nbsp; Institute&nbsp; of&nbsp; Health,&nbsp; National Cancer&nbsp; Institute, was&nbsp; used&nbsp; as&nbsp; the&nbsp; score&nbsp; system&nbsp; for&nbsp; toxicity&nbsp; ranking.&nbsp; In&nbsp; order&nbsp; to determine&nbsp; the&nbsp; effects&nbsp; of&nbsp; the examinees&rsquo;&nbsp; characteristics, applied&nbsp; doses&nbsp; and&nbsp; the presence&nbsp; of&nbsp; prolonged&nbsp; elimination on&nbsp; the&nbsp; parameters&nbsp; of&nbsp; interest,&nbsp; three&nbsp; groups&nbsp; of patients were&nbsp; compared (2 g/m² dose without prolonged elimination, 5 g/m² without prolonged elimination and 5 g/m² with prolonged elimination of methotrexate). In the&nbsp; entire&nbsp; group of&nbsp; examinees, the median&nbsp; concentration of methotrexate was&nbsp; 25.82 &mu;mol/l in the 24th hour, 0.68 &mu;mol/l in the 36th&nbsp; hour&nbsp; and 0.24 &mu;mol/l in the 42nd hour of&nbsp; observation. The largest inter - individual variability of methotrexate concentration&nbsp; was&nbsp; observed&nbsp; in&nbsp; the&nbsp; 24th&nbsp; hour&nbsp; while&nbsp; the&nbsp; largest&nbsp; intra - individual variability&nbsp; was&nbsp; recorded&nbsp; in&nbsp; the&nbsp; 36th&nbsp; hour&nbsp; of&nbsp; observation.&nbsp; The&nbsp; median&nbsp; clearance&nbsp; of methotrexate&nbsp; was&nbsp; 8.32l/h.&nbsp; Pharmacokinetic&nbsp; parameters&nbsp; were&nbsp; the&nbsp; following:&nbsp; median volume&nbsp; of&nbsp; the&nbsp; central&nbsp; compartment V₁ 28.47&nbsp; l,&nbsp; median&nbsp; constants k₁₀ 0,206, k₁₂ 0,0245, k₂₁ 0,1114, respectively. The&nbsp;&nbsp; strongest&nbsp;&nbsp; influence&nbsp;&nbsp; of&nbsp;&nbsp; the&nbsp;&nbsp; applied&nbsp;&nbsp; dose&nbsp;&nbsp; on&nbsp;&nbsp; the&nbsp;&nbsp; methotrexate concentration was recorded in the 24th hour of observation while no influence on the methotrexate&nbsp; clearance&nbsp; was&nbsp; found.&nbsp; The&nbsp; presence&nbsp; of&nbsp; prolonged&nbsp; elimination&nbsp; of methotrexate&nbsp;&nbsp; causes&nbsp;&nbsp; lower&nbsp; constants k₁₀ and&nbsp;&nbsp; k₂₁. There&nbsp;&nbsp; was&nbsp;&nbsp; no&nbsp;&nbsp; statistically significant&nbsp; interaction&nbsp; between&nbsp; the&nbsp; investigated&nbsp; demographic&nbsp; characteristics&nbsp; (age, body&nbsp; surface&nbsp; and&nbsp; gender)&nbsp; and&nbsp; the&nbsp; methotrexate&nbsp; concentration,&nbsp; nor&nbsp; between&nbsp; the demographic&nbsp;&nbsp; characteristics&nbsp;&nbsp; and&nbsp;&nbsp; the&nbsp;&nbsp; methotrexate&nbsp;&nbsp; clearance.&nbsp;&nbsp; A&nbsp;&nbsp; significant interaction was found between methotrexate concentration and lactat dehydrogenase level, as&nbsp;&nbsp; well&nbsp;&nbsp; as&nbsp;&nbsp; between&nbsp;&nbsp; methotrexate&nbsp;&nbsp; clearance&nbsp;&nbsp; and&nbsp;&nbsp; creatinine&nbsp;&nbsp; and&nbsp;&nbsp; lactate dehydrogenase level, respectively. Most of the observed toxicities were of moderate degree (&lt; 3 degrees). Oral mucositis&nbsp; was&nbsp; the&nbsp; most&nbsp; represented&nbsp; clinical&nbsp; sign&nbsp; of&nbsp; toxicity,&nbsp; and&nbsp; it&nbsp; was&nbsp; of&nbsp; higher degree&nbsp; in&nbsp; the&nbsp; group&nbsp; where&nbsp; the&nbsp; applied&nbsp; dose&nbsp; of&nbsp; methotrexate&nbsp; was&nbsp; higher&nbsp; (5&nbsp; g/m² ). Leucopenia&nbsp; and&nbsp; anemia&nbsp; were&nbsp; the&nbsp; most&nbsp; represented&nbsp; laboratory&nbsp; toxic&nbsp; effects.&nbsp; The most severe laboratory signs of toxicity&nbsp; (leucopenia, anemia, increase in AST, ALT and&nbsp; GGT&nbsp; activity)&nbsp; were&nbsp; observed&nbsp; in&nbsp; the&nbsp; group&nbsp; with&nbsp; the&nbsp; higher&nbsp; dose&nbsp; (5&nbsp; g/m² )&nbsp; and prolonged methotrexate elimination. Due to high inter- and&nbsp;&nbsp; intra-individual&nbsp;&nbsp;&nbsp; variability&nbsp; of&nbsp; the drug pharmacokinetics,&nbsp; the&nbsp; basis&nbsp; for&nbsp; the&nbsp; clinical&nbsp; care&nbsp; of&nbsp; patients&nbsp; on&nbsp; high&nbsp; methotrexate dosage&nbsp; therapy&nbsp; is&nbsp; therapeutic&nbsp; drug&nbsp; monitoring &ndash; TDM.&nbsp; Routine&nbsp; monitoring&nbsp; of methotrexate serum concentration is important for the identification of patients with a high&nbsp; risk&nbsp; of&nbsp; toxicity,&nbsp; and&nbsp; thus&nbsp; TDM&nbsp; is&nbsp; used&nbsp; as&nbsp; a&nbsp; standard&nbsp; procedure&nbsp; which&nbsp; provides guidelines&nbsp; for&nbsp; leucovorin&nbsp; rescue,&nbsp; particularly&nbsp; for&nbsp; patients&nbsp; with&nbsp; a&nbsp; lower&nbsp; methotrexate clearance or other risks associated with prolonged cytotoxic concent rations (kidney or liver&nbsp; damage,&nbsp; body&nbsp; fluid&nbsp; accumulation&nbsp; in&nbsp; the&nbsp; &ldquo;third&nbsp; space&rdquo;,&nbsp; gastrointestinal obstruction). Numerous studies involving pediatric patients have documented the link between&nbsp; a&nbsp; systemic&nbsp; methotrexate&nbsp; exposure&nbsp; on&nbsp; one&nbsp; hand,&nbsp; and&nbsp; the&nbsp; efficiency&nbsp; and toxicity of&nbsp; ethotrexate on the other hand. However, there is no sufficient data on the methotrexate&nbsp;&nbsp;&nbsp; pharmacokinetics&nbsp;&nbsp; in&nbsp;&nbsp; children&nbsp;&nbsp; suffering&nbsp;&nbsp; from&nbsp;&nbsp; acute&nbsp;&nbsp; lymphoblastic leukemia.&nbsp;&nbsp; Moreover,&nbsp;&nbsp; this&nbsp;&nbsp; type&nbsp;&nbsp; of&nbsp;&nbsp; research,&nbsp;&nbsp; involving&nbsp;&nbsp; children&nbsp;&nbsp; treated&nbsp;&nbsp; in&nbsp;&nbsp; the geographical region of this study, have not been conducted.</p>

<p>Per- and polyfluoroalkyl substances (PFAS) are a group of emerging global contaminants used in a variety of industrial processes and consumer products, such as personal care products and fast-food wrappers. However, due to their carbon-fluorine bonds, these chemicals resist degradation and persist in the environment. PFAS toxicity is driven by a compound’s functional group and chain length with perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide dimer acid (GenX) being of focal concern due to their toxicity to wildlife and presence in the environment. Despite growing concern regarding these contaminants, inadequate attention has been given to evaluating what organismal characteristics influence uptake and depuration of these chemicals, such as life stage and sex. <em>Xenopus laevis</em> tadpoles are a useful model to assess the influence of sex on PFAS kinetics since they have a life history that includes a gill to lung transition. Previous studies have shown that air-breathing organisms depurate PFAS more slowly than water-breathing organisms, but this relationship has never been directly tested. Sex has been shown to be an important factor in the depuration of PFOA for rats, with female rats depurating PFOA in four hours while males depurate in four days. The early portion of bioaccumulation curves are also understudied even though tadpoles accumulate PFAS rapidly, reaching steady state within 48 hours of exposure. <em>Xenopus laevis</em> are used to study multiple endpoints for endocrine disrupting chemicals including PFAS. Despite this, toxicity reference values (TRVs) have not been described for the uptake and elimination of PFAS using <em>X. laevis</em>. To address these gaps in knowledge, I first developed TRVs for <em>X. laevis</em> tadpoles exposed to PFOA throughout metamorphosis and evaluated the influence of sex on phenotypic endpoints. Results showed a no observed effect concentration (NOEC) of 11.1 ppm for body mass at day 14 and no effect of sex on apical endpoints. Next, I described the early bioaccumulation of four PFAS with differing structure (chain lengths and functional groups). PFOS was the only chemical to bioaccumulate with a log bioconcentration factor (BCF) at 10 and 1,000 ppm of 1.33 and 1.18, respectively. PFHxS, PFOA, and GenX had BCFs less than 0. Finally, I examined the impact of life-stage and sex on <em>X. laevis</em> tadpole and juvenile depuration rates. Larval tadpoles depurated four times faster than juveniles, indicating a significant effect of life stage on elimination rates. Sex had no influence on elimination rates. These are the first studies conducted evaluating the significance of life stage and sex in toxicokinetics of PFAS in amphibians.</p>