No description available.

Diabetic cardiomyopathy is one of the causes of mortality and morbidity associated with diabetes. Diabetes is a disorder characterised by chronic hyperglycaemia and cardiovascular complications. The relationship between these integrally linked conditions has long been recognised, and for a significant portion of individuals the two conditions co-exist as part of metabolic syndrome. The presence of diabetes increases the risk of heart failure up to fivefold and three-fold in women and men, respectively, when compared to individuals without diabetes. While there has been a significant declining trend in cardiovascular mortality and morbidity in the general population over the past two decades, unfortunately such trends have not been seen among diabetic patients. As a result, this has persuaded many health professionals to re-evaluate their current treatment and pharmacological regimens. It is a well established fact that oxidative stress is a contributory mechanism in many agerelated disorders including T2DM, especially in those with poor glycaemic control. Thus far, clinical trials with antioxidant or carbonyl-trapping agents have produced mixed results, suggesting that the mechanisms underlying this disorder may be more complex than previously thought. Although altered systemic regulation of trace metals in diabetes has been previously investigated, it is still unclear whether changed trace metal metabolism would cause heart disease in common forms of diabetes and whether metal chelation can reverse this condition. Our hypothesis is that the accumulation of redox-active trace metals including Cu and Fe in cardiac muscle may, at least in part, result in cardiomyopathy through the generation of excess reactive oxygen species. We believed that the administration of a specific metal chelator should ameliorate this process by increasing the excretion of free systemic Cu and Fe, consequently limiting the production of superoxide oxygen free radicals and arresting the process of diabetic cardiomyopathy. Data from pre-clinical studies conducted in our laboratory using diabetic animal model with diabetes-induced abnormal Cu metabolism have been remarkably consistent in demonstrating that oral dosing with triethylenetetramine (TETA) can effectively remove systemic Cu via increased urinary Cu excretion, improve cardiomyocyte structure, reverse elevations in left ventricular collagen and β1-integrin, and alleviate heart failure, all in the presence of a consistently high circulating blood glucose profile. Taken together, these findings support the beneficial role of TETA in diabetic animal model and lay the foundation for its potential therapeutic effect in humans with diabetes. This thesis describes a series of randomised, placebo-controlled clinical trials that have investigated the metabolism of Cu and Fe and seven other trace metals in patients with chronic T2DM compared with non-diabetic control subjects. This thesis also examines the mechanism of action of TETA and addresses the hypothesis that a decrease in body systemic Cu pool through chelation therapy may improve cardiac complication in diabetic subjects. Trial 1 is a randomised, double-blind, placebo- and diet-controlled study which measured the 6d balance of Cu and Fe and seven other essential trace metals, in twenty male T2DM and twenty age-matched control subjects in whom we later probed systemic metal balance with oral TETA. Basal urinary output and balance of Cu and Fe was significantly elevated in diabetes, and the two output values correlated strongly (p<0.05). 6d treatment with 2400mg/d dose of TETA (maximum Wilson’s disease dose) has increased the urinary excretion of Cu, which was predicted by basal urinary Cu excretion, thereby causing a positive Cu balance to become negative in diabetes. Regulation of Cu metabolism was shown to be abnormal in diabetes and was selectively modified by TETA, which did not concomitantly modify Fe metabolism. Moreover, TETA did not cause a negative balance in any of the other seven trace metals monitored. These findings are consistent with TETA reversing the accumulation of free systemic Cu in diabetes, which may help to explain its potential therapeutic effects in some diabetic complications. Trial 2 investigated the acute response effect of a single 2400mg dose of TETA on urinary and serum trace metals in the first 10hr and 10~24hr post-dose. The results showed that TETA markedly increased the urinary Cu and Zn excretion in diabetes for the duration of 10hrs with the maximum excretion phase between 4~6hr post-drug (p<0.05). TETA did not change the metabolism of Mg and six other essential trace metals monitored. Trial 3 examined the dose-response effect of TETA, at and below the dose given to patients with the Wilson’s disease over a 7d period, on Cu and eight other trace metals in a subgroup of seven T2DM and seven control subjects who had completed trial 1. The results of this i i trial showed that there was a linear dose-response relationship over the dose range 300~2400 mg/d on urinary Cu excretion in both T2DM and control subjects. However, there was no significant difference between the two subject groups at any of the four doses tested. In addition, 300mg/d of TETA was effective in mobilizing Cu in both T2DM and healthy control subjects. Trial 4 described the full work-up of a sensitive LC-MS methodology to identify and quantify TETA and its metabolite(s) in human urine. Using the LC-MS, TETA metabolism and excretion was investigated by analysing the urine of seven T2DM and seven control subjects who received escalating doses of TETA (samples obtained from trial 3). I have successfully identified and characterised two major metabolites of TETA in the urine of both T2DM and control subjects, N1-monoacetytriethylenetetramine (MAT) and diacetytriethylenetetramine (DAT), the latter which has not been previously reported. The results from urinary TETA excretion analyses also showed that T2DM may metabolise TETA more extensively than control subjects, which in turn is associated with its higher uptake or bioavailability. Urinary Zn excretion was mainly linked with urinary TETA and MAT in T2DM and healthy controls, respectively, whereas urinary Cu excretion was associated with urinary TETA excretion in healthy controls and urinary TETA+MAT excretion in T2DM subjects. These results suggest that MAT may also be involved in the mechanism by which TETA extracts systemic free Cu in diabetes. The identification of the two major metabolites of TETA and the development of a robust analytical LC-MS methodology reported in this study is an important step to further investigate the pharmacological actions of TETA in diabetic individuals. Collectively, the results presented in this thesis and in association with previous animal and clinical studies from our laboratory have provided consistent supporting evidences for the use of TETA clinically as a safe and effective therapy to prevent the genesis of some diabetic complications, in conjunction with conventional complication modifying therapies.

Diabetic cardiomyopathy is one of the causes of mortality and morbidity associated with diabetes. Diabetes is a disorder characterised by chronic hyperglycaemia and cardiovascular complications. The relationship between these integrally linked conditions has long been recognised, and for a significant portion of individuals the two conditions co-exist as part of metabolic syndrome. The presence of diabetes increases the risk of heart failure up to fivefold and three-fold in women and men, respectively, when compared to individuals without diabetes. While there has been a significant declining trend in cardiovascular mortality and morbidity in the general population over the past two decades, unfortunately such trends have not been seen among diabetic patients. As a result, this has persuaded many health professionals to re-evaluate their current treatment and pharmacological regimens. It is a well established fact that oxidative stress is a contributory mechanism in many agerelated disorders including T2DM, especially in those with poor glycaemic control. Thus far, clinical trials with antioxidant or carbonyl-trapping agents have produced mixed results, suggesting that the mechanisms underlying this disorder may be more complex than previously thought. Although altered systemic regulation of trace metals in diabetes has been previously investigated, it is still unclear whether changed trace metal metabolism would cause heart disease in common forms of diabetes and whether metal chelation can reverse this condition. Our hypothesis is that the accumulation of redox-active trace metals including Cu and Fe in cardiac muscle may, at least in part, result in cardiomyopathy through the generation of excess reactive oxygen species. We believed that the administration of a specific metal chelator should ameliorate this process by increasing the excretion of free systemic Cu and Fe, consequently limiting the production of superoxide oxygen free radicals and arresting the process of diabetic cardiomyopathy. Data from pre-clinical studies conducted in our laboratory using diabetic animal model with diabetes-induced abnormal Cu metabolism have been remarkably consistent in demonstrating that oral dosing with triethylenetetramine (TETA) can effectively remove systemic Cu via increased urinary Cu excretion, improve cardiomyocyte structure, reverse elevations in left ventricular collagen and β1-integrin, and alleviate heart failure, all in the presence of a consistently high circulating blood glucose profile. Taken together, these findings support the beneficial role of TETA in diabetic animal model and lay the foundation for its potential therapeutic effect in humans with diabetes. This thesis describes a series of randomised, placebo-controlled clinical trials that have investigated the metabolism of Cu and Fe and seven other trace metals in patients with chronic T2DM compared with non-diabetic control subjects. This thesis also examines the mechanism of action of TETA and addresses the hypothesis that a decrease in body systemic Cu pool through chelation therapy may improve cardiac complication in diabetic subjects. Trial 1 is a randomised, double-blind, placebo- and diet-controlled study which measured the 6d balance of Cu and Fe and seven other essential trace metals, in twenty male T2DM and twenty age-matched control subjects in whom we later probed systemic metal balance with oral TETA. Basal urinary output and balance of Cu and Fe was significantly elevated in diabetes, and the two output values correlated strongly (p<0.05). 6d treatment with 2400mg/d dose of TETA (maximum Wilson’s disease dose) has increased the urinary excretion of Cu, which was predicted by basal urinary Cu excretion, thereby causing a positive Cu balance to become negative in diabetes. Regulation of Cu metabolism was shown to be abnormal in diabetes and was selectively modified by TETA, which did not concomitantly modify Fe metabolism. Moreover, TETA did not cause a negative balance in any of the other seven trace metals monitored. These findings are consistent with TETA reversing the accumulation of free systemic Cu in diabetes, which may help to explain its potential therapeutic effects in some diabetic complications. Trial 2 investigated the acute response effect of a single 2400mg dose of TETA on urinary and serum trace metals in the first 10hr and 10~24hr post-dose. The results showed that TETA markedly increased the urinary Cu and Zn excretion in diabetes for the duration of 10hrs with the maximum excretion phase between 4~6hr post-drug (p<0.05). TETA did not change the metabolism of Mg and six other essential trace metals monitored. Trial 3 examined the dose-response effect of TETA, at and below the dose given to patients with the Wilson’s disease over a 7d period, on Cu and eight other trace metals in a subgroup of seven T2DM and seven control subjects who had completed trial 1. The results of this i i trial showed that there was a linear dose-response relationship over the dose range 300~2400 mg/d on urinary Cu excretion in both T2DM and control subjects. However, there was no significant difference between the two subject groups at any of the four doses tested. In addition, 300mg/d of TETA was effective in mobilizing Cu in both T2DM and healthy control subjects. Trial 4 described the full work-up of a sensitive LC-MS methodology to identify and quantify TETA and its metabolite(s) in human urine. Using the LC-MS, TETA metabolism and excretion was investigated by analysing the urine of seven T2DM and seven control subjects who received escalating doses of TETA (samples obtained from trial 3). I have successfully identified and characterised two major metabolites of TETA in the urine of both T2DM and control subjects, N1-monoacetytriethylenetetramine (MAT) and diacetytriethylenetetramine (DAT), the latter which has not been previously reported. The results from urinary TETA excretion analyses also showed that T2DM may metabolise TETA more extensively than control subjects, which in turn is associated with its higher uptake or bioavailability. Urinary Zn excretion was mainly linked with urinary TETA and MAT in T2DM and healthy controls, respectively, whereas urinary Cu excretion was associated with urinary TETA excretion in healthy controls and urinary TETA+MAT excretion in T2DM subjects. These results suggest that MAT may also be involved in the mechanism by which TETA extracts systemic free Cu in diabetes. The identification of the two major metabolites of TETA and the development of a robust analytical LC-MS methodology reported in this study is an important step to further investigate the pharmacological actions of TETA in diabetic individuals. Collectively, the results presented in this thesis and in association with previous animal and clinical studies from our laboratory have provided consistent supporting evidences for the use of TETA clinically as a safe and effective therapy to prevent the genesis of some diabetic complications, in conjunction with conventional complication modifying therapies.

Diabetic cardiomyopathy is one of the causes of mortality and morbidity associated with diabetes. Diabetes is a disorder characterised by chronic hyperglycaemia and cardiovascular complications. The relationship between these integrally linked conditions has long been recognised, and for a significant portion of individuals the two conditions co-exist as part of metabolic syndrome. The presence of diabetes increases the risk of heart failure up to fivefold and three-fold in women and men, respectively, when compared to individuals without diabetes. While there has been a significant declining trend in cardiovascular mortality and morbidity in the general population over the past two decades, unfortunately such trends have not been seen among diabetic patients. As a result, this has persuaded many health professionals to re-evaluate their current treatment and pharmacological regimens. It is a well established fact that oxidative stress is a contributory mechanism in many agerelated disorders including T2DM, especially in those with poor glycaemic control. Thus far, clinical trials with antioxidant or carbonyl-trapping agents have produced mixed results, suggesting that the mechanisms underlying this disorder may be more complex than previously thought. Although altered systemic regulation of trace metals in diabetes has been previously investigated, it is still unclear whether changed trace metal metabolism would cause heart disease in common forms of diabetes and whether metal chelation can reverse this condition. Our hypothesis is that the accumulation of redox-active trace metals including Cu and Fe in cardiac muscle may, at least in part, result in cardiomyopathy through the generation of excess reactive oxygen species. We believed that the administration of a specific metal chelator should ameliorate this process by increasing the excretion of free systemic Cu and Fe, consequently limiting the production of superoxide oxygen free radicals and arresting the process of diabetic cardiomyopathy. Data from pre-clinical studies conducted in our laboratory using diabetic animal model with diabetes-induced abnormal Cu metabolism have been remarkably consistent in demonstrating that oral dosing with triethylenetetramine (TETA) can effectively remove systemic Cu via increased urinary Cu excretion, improve cardiomyocyte structure, reverse elevations in left ventricular collagen and β1-integrin, and alleviate heart failure, all in the presence of a consistently high circulating blood glucose profile. Taken together, these findings support the beneficial role of TETA in diabetic animal model and lay the foundation for its potential therapeutic effect in humans with diabetes. This thesis describes a series of randomised, placebo-controlled clinical trials that have investigated the metabolism of Cu and Fe and seven other trace metals in patients with chronic T2DM compared with non-diabetic control subjects. This thesis also examines the mechanism of action of TETA and addresses the hypothesis that a decrease in body systemic Cu pool through chelation therapy may improve cardiac complication in diabetic subjects. Trial 1 is a randomised, double-blind, placebo- and diet-controlled study which measured the 6d balance of Cu and Fe and seven other essential trace metals, in twenty male T2DM and twenty age-matched control subjects in whom we later probed systemic metal balance with oral TETA. Basal urinary output and balance of Cu and Fe was significantly elevated in diabetes, and the two output values correlated strongly (p<0.05). 6d treatment with 2400mg/d dose of TETA (maximum Wilson’s disease dose) has increased the urinary excretion of Cu, which was predicted by basal urinary Cu excretion, thereby causing a positive Cu balance to become negative in diabetes. Regulation of Cu metabolism was shown to be abnormal in diabetes and was selectively modified by TETA, which did not concomitantly modify Fe metabolism. Moreover, TETA did not cause a negative balance in any of the other seven trace metals monitored. These findings are consistent with TETA reversing the accumulation of free systemic Cu in diabetes, which may help to explain its potential therapeutic effects in some diabetic complications. Trial 2 investigated the acute response effect of a single 2400mg dose of TETA on urinary and serum trace metals in the first 10hr and 10~24hr post-dose. The results showed that TETA markedly increased the urinary Cu and Zn excretion in diabetes for the duration of 10hrs with the maximum excretion phase between 4~6hr post-drug (p<0.05). TETA did not change the metabolism of Mg and six other essential trace metals monitored. Trial 3 examined the dose-response effect of TETA, at and below the dose given to patients with the Wilson’s disease over a 7d period, on Cu and eight other trace metals in a subgroup of seven T2DM and seven control subjects who had completed trial 1. The results of this i i trial showed that there was a linear dose-response relationship over the dose range 300~2400 mg/d on urinary Cu excretion in both T2DM and control subjects. However, there was no significant difference between the two subject groups at any of the four doses tested. In addition, 300mg/d of TETA was effective in mobilizing Cu in both T2DM and healthy control subjects. Trial 4 described the full work-up of a sensitive LC-MS methodology to identify and quantify TETA and its metabolite(s) in human urine. Using the LC-MS, TETA metabolism and excretion was investigated by analysing the urine of seven T2DM and seven control subjects who received escalating doses of TETA (samples obtained from trial 3). I have successfully identified and characterised two major metabolites of TETA in the urine of both T2DM and control subjects, N1-monoacetytriethylenetetramine (MAT) and diacetytriethylenetetramine (DAT), the latter which has not been previously reported. The results from urinary TETA excretion analyses also showed that T2DM may metabolise TETA more extensively than control subjects, which in turn is associated with its higher uptake or bioavailability. Urinary Zn excretion was mainly linked with urinary TETA and MAT in T2DM and healthy controls, respectively, whereas urinary Cu excretion was associated with urinary TETA excretion in healthy controls and urinary TETA+MAT excretion in T2DM subjects. These results suggest that MAT may also be involved in the mechanism by which TETA extracts systemic free Cu in diabetes. The identification of the two major metabolites of TETA and the development of a robust analytical LC-MS methodology reported in this study is an important step to further investigate the pharmacological actions of TETA in diabetic individuals. Collectively, the results presented in this thesis and in association with previous animal and clinical studies from our laboratory have provided consistent supporting evidences for the use of TETA clinically as a safe and effective therapy to prevent the genesis of some diabetic complications, in conjunction with conventional complication modifying therapies.

Diabetic cardiomyopathy is one of the causes of mortality and morbidity associated with diabetes. Diabetes is a disorder characterised by chronic hyperglycaemia and cardiovascular complications. The relationship between these integrally linked conditions has long been recognised, and for a significant portion of individuals the two conditions co-exist as part of metabolic syndrome. The presence of diabetes increases the risk of heart failure up to fivefold and three-fold in women and men, respectively, when compared to individuals without diabetes. While there has been a significant declining trend in cardiovascular mortality and morbidity in the general population over the past two decades, unfortunately such trends have not been seen among diabetic patients. As a result, this has persuaded many health professionals to re-evaluate their current treatment and pharmacological regimens. It is a well established fact that oxidative stress is a contributory mechanism in many agerelated disorders including T2DM, especially in those with poor glycaemic control. Thus far, clinical trials with antioxidant or carbonyl-trapping agents have produced mixed results, suggesting that the mechanisms underlying this disorder may be more complex than previously thought. Although altered systemic regulation of trace metals in diabetes has been previously investigated, it is still unclear whether changed trace metal metabolism would cause heart disease in common forms of diabetes and whether metal chelation can reverse this condition. Our hypothesis is that the accumulation of redox-active trace metals including Cu and Fe in cardiac muscle may, at least in part, result in cardiomyopathy through the generation of excess reactive oxygen species. We believed that the administration of a specific metal chelator should ameliorate this process by increasing the excretion of free systemic Cu and Fe, consequently limiting the production of superoxide oxygen free radicals and arresting the process of diabetic cardiomyopathy. Data from pre-clinical studies conducted in our laboratory using diabetic animal model with diabetes-induced abnormal Cu metabolism have been remarkably consistent in demonstrating that oral dosing with triethylenetetramine (TETA) can effectively remove systemic Cu via increased urinary Cu excretion, improve cardiomyocyte structure, reverse elevations in left ventricular collagen and β1-integrin, and alleviate heart failure, all in the presence of a consistently high circulating blood glucose profile. Taken together, these findings support the beneficial role of TETA in diabetic animal model and lay the foundation for its potential therapeutic effect in humans with diabetes. This thesis describes a series of randomised, placebo-controlled clinical trials that have investigated the metabolism of Cu and Fe and seven other trace metals in patients with chronic T2DM compared with non-diabetic control subjects. This thesis also examines the mechanism of action of TETA and addresses the hypothesis that a decrease in body systemic Cu pool through chelation therapy may improve cardiac complication in diabetic subjects. Trial 1 is a randomised, double-blind, placebo- and diet-controlled study which measured the 6d balance of Cu and Fe and seven other essential trace metals, in twenty male T2DM and twenty age-matched control subjects in whom we later probed systemic metal balance with oral TETA. Basal urinary output and balance of Cu and Fe was significantly elevated in diabetes, and the two output values correlated strongly (p<0.05). 6d treatment with 2400mg/d dose of TETA (maximum Wilson’s disease dose) has increased the urinary excretion of Cu, which was predicted by basal urinary Cu excretion, thereby causing a positive Cu balance to become negative in diabetes. Regulation of Cu metabolism was shown to be abnormal in diabetes and was selectively modified by TETA, which did not concomitantly modify Fe metabolism. Moreover, TETA did not cause a negative balance in any of the other seven trace metals monitored. These findings are consistent with TETA reversing the accumulation of free systemic Cu in diabetes, which may help to explain its potential therapeutic effects in some diabetic complications. Trial 2 investigated the acute response effect of a single 2400mg dose of TETA on urinary and serum trace metals in the first 10hr and 10~24hr post-dose. The results showed that TETA markedly increased the urinary Cu and Zn excretion in diabetes for the duration of 10hrs with the maximum excretion phase between 4~6hr post-drug (p<0.05). TETA did not change the metabolism of Mg and six other essential trace metals monitored. Trial 3 examined the dose-response effect of TETA, at and below the dose given to patients with the Wilson’s disease over a 7d period, on Cu and eight other trace metals in a subgroup of seven T2DM and seven control subjects who had completed trial 1. The results of this i i trial showed that there was a linear dose-response relationship over the dose range 300~2400 mg/d on urinary Cu excretion in both T2DM and control subjects. However, there was no significant difference between the two subject groups at any of the four doses tested. In addition, 300mg/d of TETA was effective in mobilizing Cu in both T2DM and healthy control subjects. Trial 4 described the full work-up of a sensitive LC-MS methodology to identify and quantify TETA and its metabolite(s) in human urine. Using the LC-MS, TETA metabolism and excretion was investigated by analysing the urine of seven T2DM and seven control subjects who received escalating doses of TETA (samples obtained from trial 3). I have successfully identified and characterised two major metabolites of TETA in the urine of both T2DM and control subjects, N1-monoacetytriethylenetetramine (MAT) and diacetytriethylenetetramine (DAT), the latter which has not been previously reported. The results from urinary TETA excretion analyses also showed that T2DM may metabolise TETA more extensively than control subjects, which in turn is associated with its higher uptake or bioavailability. Urinary Zn excretion was mainly linked with urinary TETA and MAT in T2DM and healthy controls, respectively, whereas urinary Cu excretion was associated with urinary TETA excretion in healthy controls and urinary TETA+MAT excretion in T2DM subjects. These results suggest that MAT may also be involved in the mechanism by which TETA extracts systemic free Cu in diabetes. The identification of the two major metabolites of TETA and the development of a robust analytical LC-MS methodology reported in this study is an important step to further investigate the pharmacological actions of TETA in diabetic individuals. Collectively, the results presented in this thesis and in association with previous animal and clinical studies from our laboratory have provided consistent supporting evidences for the use of TETA clinically as a safe and effective therapy to prevent the genesis of some diabetic complications, in conjunction with conventional complication modifying therapies.

>Magister Scientiae - MSc / Electrochemical platforms were developed based on pencil graphite electrodes (PGEs) modified with electrochemically deposited graphene (EG) sheets and Nafion-graphene (NG) nanocomposites in conjunction with an in situ plated bismuth-film (EG-PG-BiE and NG-PG-BiE). The EG- and NG-PG-BiEs were used as sensing platforms for determining Zn2+, Cd2+ and Pb2+ by square wave anodic stripping voltammetry (SWASV). EG sheets were deposited onto pencil graphite electrodes by cyclic voltammetric reduction from a graphene oxide (GO) solution, while a dip coating method was used to prepare the NG-PG-BiE. The GO and graphene, with flake thicknesses of 1.78 (2 sheets) and 2.10 nm (5 sheets) respectively, was characterized using FT-IR, HR-SEM, HR-TEM, AFM, XRD and Raman spectroscopy. Parameters influencing the electroanalytical response of the EG-PG-BiE and NG-PG-BiE such as, bismuth ion concentration, deposition potential, deposition time and rotation speed were investigated and optimized. The EG-PG-BiE gave well-defined, reproducible peaks with detection limits of 0.19 μg L-1, 0.09 μg L-1 and 0.12 μg L-1 for Zn2+, Cd2+ and Pb2+ respectively, at a deposition time of 120 seconds. The NG-PG-BiE showed similar detection limits of 0.167 μg L-1, 0.098 μg L-1 and 0.125 μg L-1 for Zn2+, Cd2+ and Pb2+ respectively. For real sample analysis, the enhanced voltammetric sensor proved to be suitable for the detection and quantitation of heavy metals below the US EPA prescribed drinking water standards of 5 mg L-1, 5 μg L-1 and 15 μg L-1 for Zn2+, Cd2+ and Pb2+ respectively.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Karolína Pelnářová Supervisor: Prof. Přemysl Mladěnka, PharmD., Ph.D. Consultant: Václav Tvrdý, MSc.; Marcel Hrubša, MSc. Title of diploma thesis: Searching of effective cobalt chelators - 8-hydroxyquinolines Cobalt is one of the essential trace elements present in the human body. It forms a part of the organometallic complex of vitamin B12, which is essential for many physiological functions. Both overload and lack of cobalt in the body is associated with pathological conditions. Manifestations of deficiency can lead up to pernicious anemia or hypofunction of the thyroid gland. Cobalt intoxication can occur in an industrial environment, such as by cobalt metal dust during heavy metal processing, or by its release due to corrosion from orthopedic prostheses. Systemic toxicity is manifested by a number of endocrine, cardiovascular and neurological symptoms. The main aim of this diploma thesis was to find effective chelators of cobalt from the group of substances derived from 8-hydroxyquinoline. In vitro spectrophotometric measurement was used to determine the degree of chelation. The effect of chelation was also monitored ex vivo in rat erythrocytes. All tested chelators - 8-hydroxyquinoline,...

We investigated the transport of dissolved arsenic in groundwater, surface water and the hyporheic zone in a stream-aquifer system influenced by an abandoned arsenopyrite mine. Mine tailing piles consisting of a host of arsenic-bearing minerals including arsenopyrite and scorodite remain adjacent to the stream and represent a continuous source of arsenic. Arsenic loads from the stream, springs, and groundwater were quantified at the study reach on nine dates from January to August 2005 and a mass-balance approach was used to determine hyporheic retention. Arsenic loading from the groundwater was the dominate source of arsenic to the stream, while loads from springs represented a substantial proportion of the total arsenic load during spring. Arsenic loads in surface and groundwater were significantly elevated during summer. Elevated temperatures during summer may lead to increased arsenic loading by increasing dissolution rate of arsenic source minerals and/or increases in microbially-mediated dissolution processes. The hyporheic zone was shown to be retaining arsenic in the upstream-most sub-reach. Retention most likely occurs through the sorption of dissolved arsenic onto hyporheic sediments. In downstream sub-reaches, hyporheic sediments are derived from mine-tailing piles which have high arsenic content. The hyporheic zone in these sub-reaches was shown to be releasing dissolved arsenic. The historic influence of mining activity has resulted in multiple sources of arsenic to the stream which has increased arsenic contamination of the surface waters. / Master of Science

No description available.

The global marine distributions of Cd and phosphate are closely correlated, which has led to Cd being considered as a marine micronutrient. Recent developments in Cd stable isotope mass spectrometry have revealed that Cd uptake by phytoplankton causes isotopic fractionation in the open ocean and in culture. The explanation for this nutrient-like behaviour is unknown as there is only one identified biochemical function for Cd, an unusual Cd/Zn carbonic anhydrase (CdCA1). This thesis investigates why Cd appears to act as an algal nutrient by performing subcellular analyses of microorganisms genetically-modified to express the CdCA1 gene. It was found that CdCA1 was not a significant contributor to whole-cell Cd isotope compositions. Instead, a large proportion of the internalized Cd is sequestered into cell membranes with a similar direction and magnitude of Cd isotopic fractionation as seen in surface seawater. This observation is explained if Cd is mistakenly imported with other divalent metals and subsequently managed by binding within the cell to avoid toxicity. This result implies that surface seawater Cd isotope compositions, if captured by an appropriate archive, may be invaluable for reconstructions of past marine productivity. The role of environmental factors in modulating the inorganic partitioning of Cd isotopes into calcite was investigated through a series of laboratory analogue experiments. In seawater, the light isotopes of Cd are always preferred in calcite. The magnitude of fractionation showed no response to temperature, ambient [Mg], or precipitation rate. To further identify suitable palaeaoceanographic archives, the Cd isotopic composition of a suite of modern deep-sea corals were investigated. It was found that the Cd/Ca and Cd isotope composition of coralline calcium carbonate followed the predicted trend for closed-system Rayleigh fractionation in the calcifying space. The lack of isotopic offsets between some corals and seawater will simplify the application of Cd isotopes in deep-sea corals -- and potentially other marine calcifying organisms that vacuolize seawater prior to calcium carbonate precipitation -- to palaeoceanography.