Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The Auger electron emitter iodine-123 was examined in the form of 4- [12311iodoantipyrineand as [12311Nal for its effectiveness in killing cells of different sensitivity to photon irradiation. Micronucleus assays showed that 4- [12311iodoantipyrineis two to three times more effective in cell inactivation than C2311Nai.This can be attributed to the fact that antipyrine, for reason of its lipid solubility, can enter cells and can reach the cell nucleus, whereas C231]Nai is excluded from the cytoplasm. The differential targeting of intra- and extracellular compartments was confirmed by radionuclide uptake experiments. In the nucleus, Auger decay conceivably is located on the DNA where it may invoke high-LET irradiation damage. Irradiation damage by [12311Naisl by long range y-irradiation and hence low-LET. Results of the present study demonstrate however that the enhancement of MN-frequency seen with 4-[123I]iodoantipyrine over [12311Nalis similar for all cell lines and that the narrowing of MN-response expected for 4- [12311iodoantipyrinedoes not occur. Experiments with the free radical scavenger, DMSO, indicated nearly identical dose reduction factors for both iodine-123 carriers. These two observations strongly suggest that the cell inactivation by 4- [12311iodoantipyrine is not by high-LET direct ionisation of DNA, but due to an indirect effect. The indirect radiation effect of Auger decay in the nucleus is attributed to shielding of DNA by histones. Such a protection mechanism is not unrealistic if it is realised that histones and DNA associate in a 1: 1 weight ratio and that higher order folding of the nucleosome chain into solenoids, loops, and chromatids generates considerable protein density. In the nucleosome core, the histone acta mer measures 7 nm and closely approximates the 10 nm dimention of the Auger electron range. It is suggested that the interlacing of protein density with DNA density suppresses direct ionisation from Auger decay at the DNA and directs the majority of Auger decay to the histones. / AFRIKAANSE OPSOMMING: Die Auger-elektron-uitstraler, jodium-123, is ondersoek in die vorm van 4- [123l]jodoantipirien en [12311Nal om die effektiwiteit te bepaal waarmee dit selle met verskillende grade van sensitiwiteit vir fotonbestraling doodmaak. Mikrokerntellings toon aan dat 4-[123I]jodoantipirien selle twee tot drie maal meer effektief inaktiveer as [12311Nal.Dit kan toegeskryf word aan die feit dat antipirien, as gevolg van sy vetoplosbaarheidseienskappe, die selle kan binnedring en die kern bereik, teenoor [12311Nalwat uitgesluit word uit die sitoplasma. Die differensiële blootstelling van intra- en ekstrasellulere gebiede is bevestig deur radionukliedopname eksperimente. In die selkern vind Auger verval waarskynlik by die DNA plaas waar dit hoë-LET stralingskade veroorsaak. Stralingskade afkomstig van [1231]Nalis deur langafstand y-strale en dus lae-LET. Die resultate van die huidige studie bewys egter dat die verhoogde mikrokernfrekwensie van 4-[12311jodoantipirienteenoor [1231]Nal dieselfde is vir al die sellyne en dat die vernouïng van mikrokernreaksie soos verwag met 4- [12311jodoantipirien, nie plaasvind nie. Eksperimente met die vryradikaalopruimer, DMSO, dui op feitlik identiese dosis-modifiseringsfaktore vir beide jodium-123 draers. Hierdie twee waarnemings is 'n besliste aanduiding dat die selinaktivering deur 4-[12311jodoantipiriennie deur hoë-LET direkte ionisering van DNA plaasvind nie, maar eerder deur indirekte stralingsaksie. Die indirekte stralingseffek van Augerverval in die kern kan toegeskryf word aan afskerming van DNA deur histone. So 'n beskermingsmeganisme is nie onrealisties nie, as in ag geneem word dat histone en DNA in 'n 1: 1 gewigsverhouding assosieer en dat hoër orde vouïng van die nukleosoomketting tot solenoïede, lusse en chromatiede 'n beduidende protïendigtheid genereer. In die nukleosoomkern is die histoon-oktameer ongeveer 7 nm in deursnit en dus vergelykbaar met die 10 nm reikafstand van die Auger elektrone. Dit word voorgestel dat die ineengeweefdheid van die protien-digtheid met die DNA-digtheid die direkte ionisering van die DNA tydens Auger verval onderdruk en dat die meeste van die Auger verval in die histone plaasvind.

Heme is vital to a variety of cellular functions in bacteria ranging from energy generation to iron reserve. Group A streptococcus (GAS) is a prevalent bacterial pathogen that is responsible for an array of human diseases ranging from simple, self-limiting, mucosal and skin infections to invasive and systemic manifestations. GAS needs iron for growth and can satisfy this nutritional requirement by scavenging the metal from heme. The pathogen produces powerful hemolysins that facilitate heme release during infection. Heme is captured and relayed through the GAS cell wall and cytoplasmic membrane by dedicated receptors and transporters. To-date, the fate of the acquired heme is unknown in Streptococci. Although heme is nutritionally beneficial for GAS growth, its pro-oxidant and lipophilic nature makes it a liability with damaging effects on cellular components. The conundrum associated with heme use is particularly pertinent to GAS pathophysiology since invasive GAS infections involve massive hemolysis and the generation of unescorted heme in excess. In this dissertation, I aimed to describe the mechanisms that GAS uses for heme catabolism while managing its toxicity. I conducted a biochemical characterization of a new enzyme, HupZ in GAS that degrades heme in vitro. Similar to the heme oxygenase-1 (HO-1), HupZ activity leads to the formation of iron, CO, and a biliverdin-like product. I also investigated the impact of heme on GAS physiology and identified key mediators in the repair and detoxification process. This study demonstrated that heme exposure leads to a general stress response that involves the activation of antioxidant defense pathways to restore redox balance. Further, I studied a 3-gene cluster, pefRCD (porphyrin-regulated efflux RCD), which was activated by environmental heme, and provided support to my hypothesis that the pefRCD gene encodes a heme-sensing regulator (PefR) and heme efflux system (PefCD). I showed that the pef system protects GAS cells from heme-induced damage to the membrane and DNA by preventing cellular accumulation of heme. In conclusion, this dissertation addresses key knowledge gaps in GAS physiology and provides new insights into heme metabolism of GAS.

Two experiments were conducted at the University of Kentucky, Eden Shale Farm, Owenton, KY to evaluate the use of MTB-100TM (Alltech, Inc., Nicholasville, KY) to alleviate the symptoms of fescue toxicity when lactating Angus x Beefmaster cows and their calves grazed endophyte-infected KY-31 tall fescue. Experiment 1 provided a carbohydrate based toxin adsorbent, MTB-100TM, ad libitum in a commercial mineral supplement to project a daily consumption rate of 0, 20 or 40 g of MTB-100TM per cow. Cows were weighed, assigned a body condition score (BCS) and hair coat score (HC), rectal temperatures were recorded and fecal grab samples were taken for ergovaline (EV) and lysergic acid (LA) analysis every 35 days for three grazing seasons (May to September). Calves were also weighed and assigned a HC score. Although MTB-100TM did not improve cow or calf performance, cows older than 4 years and those with greater Beefmaster breeding exhibited a higher tolerance to fescue toxicity than 2 and 3-yr-olds and cows with greater Angus breeding. Experiment 2 was conducted to evaluate the response of lactating beef cows and their calves to strategic supplementation with MTB-100TM. MTB-100TM was mixed with a complete mineral so daily intake was projected to be 0 or 20 g/cow. The experimental period extended from May 5 to October 2 and was divided into 3 strategic periods: P1 = May 5 to July 5; P2 = July 5 to August 31; P3 = August 31 to October 2. Treatments were either 0 or 20 g•cow-1•d-1 MTB-100TM within a period (Treatment 1 = 0, 0, 0; Treatment 2 = 20, 0, 20; Treatment 3 = 0, 20, 0; Treatment 4 = 20, 20, 0; and Treatment 5 = 20, 20, 20). Cow and calf performance was measured the same as Exp. 1, but every 21 days. Supplementation early in the grazing season tended to improve cow weight gain and body condition; however, there was no effect on calf performance. Fecal output of EV and LA did not increase in either experiment with supplementation. In conclusion, strategically invoked MTB-100TM consumption can increase performance of cows grazing endophyte-infected tall fescue forage.

Current concerns about inorganic contaminants in food products have raised consumer awareness of anthropogenic sources of heavy metal contamination in ecosystems and their potential threat to human health. Mining and exploration of mineralized zones is a major source of such contamination. Mining throughout the Patagonia Mountains, Arizona, has left a legacy of surface water contamination by acid mine drainage (AMD). This study assessed the impacts of AMD on soils and plants throughout the study area. Concentrations, transport, and loading of heavy metals (Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, and Zn) in soils and plants was quantified using total concentrations, suggested toxic levels, and plant and soil pollution indices. Pollution indices were modified to include antimony and molybdenum. Pollution indices greater than 100 were found in areas disturbed by mining, remediation sites and beyond. Cattle grazing on grasses contaminated by metals were documented.

No description available.

AIMS: The rapidly growing industrial and medical use of nanomaterials, especially zinc oxide and titanium dioxide, has led to growing concerns about their toxicity. Accordingly, the intrinsic genotoxic and cytotoxic potential of these nanoparticles have been evaluated. MATERIALS & METHODS: Using a HEp-2 cell line, cytotoxicity was tested along with mitochondrial activity and neutral red uptake assays. The genotoxic potential was determined using the Comet and the cytokinesis-blocked micronucleus assays. In addition, tyrosine phosphorylation events were investigated. RESULTS & CONCLUSION: We found concentration- and time-dependent cytotoxicity and an increase in DNA and cytogenetic damage with increasing nanoparticle concentrations. Mainly for zinc oxide, genotoxicity was clearly associated with an increase in tyrosine phosphorylation. Our results suggest that both types of nanoparticles can be genotoxic over a range of concentrations without being cytotoxic.

Background: Previous literature showed contradictory evidence on the subject of predictors of chemotherapy-induced Palmar Plantar Erythrodysesthesia (PPE). While there is evidence to suggest that dose and schedule of the drugs play a large role, the fact that many still go on to develop severe PPE following dose reduction would indicate that there are other factors involved. Since the incidence of PPE is more prevalent during the first three cycles of treatment this would also indicate that there are factors other than a cumulative effect. The contradictory evidence in the literature relates to biographical factors, performance status, co-morbidities and renal function. There is a lack of empirical evidence to support the theory that PPE is caused by damage to the microcapillaries due to everyday activities that cause friction or pressure to the hands or feet. Purpose: The aim of this exploratory study was to identify pre-treatment risk factors for the development of PPE prior to cycle four. Patients and methods: The study was made up of two phases, a retrospective phase and a prospective phase, using mixed strategies to collect data. Thus providing two independent samples to compare and validate or refute results. Phase I: A retrospective notes review of patients who had received Infusional 5FU or capecitabine containing regimes over a 1 year period (n=392). Phase II Prospective data collection from participants receiving capecitabine monotherapy (n = 125). Data was collected during semi-structured interviews, from participant's diaries, physical examination of the hands and feet and notes review. Data relating to activities that cause friction, pressure or heat were collected during this phase. Data from both samples were analysed independently using bivariate (chi-square and t-test) tests where each independent variable was analysed against PPE. The variables which achieved statistical significance were entered into a multivariate (binary logistic regression) model. The multivariate analysis employed a specific modelling algorithm using a relaxed alpha value applied to various entry methods to produce multiple models. The outcomes from these models were entered into a ROC curve test to establish which model was the best predictor of PPE. Results: Phase I The bivariate analysis demonstrated that those at most risk of developing PPE prior to cycle 4 of capecitabine monotherapy were males with non-metastatic colorectal cancer, who had either developed PPE with previous chemotherapy regimes or not had previous chemotherapy and who started their treatment during the winter months. When variables were combined in a multivariate logistic regression model, those that were associated with an increased risk of PPE were male, no metastatic spread, no inflammatory condition as co morbidity, smoked, did not drink, had weight loss prior to treatment, a low/normal pre treatment ALP level and started their treatment during the winter. Phase II: The bivariate analysis demonstrated that those at most risk of developing PPE prior to cycle 4 of capecitabine monotherapy were those with no metastatic disease, had an inflammatory condition as co morbidity, were receiving capecitabine as adjuvant treatment, had a good performance status (0-1) and had a tendency to have warm hands. When variables were combined in a multivariate logistic regression model, those that were associated with an increased risk of PPE were younger (< 65) had no metastatic disease, an inflammatory condition as co morbidity, drank alcohol regularly, had a good performance status, had not received previous radiotherapy, were overweight or obese, had a pre treatment creatinine clearance of 30-50mls/min and had a tendency to have warm hands. Conclusions: Similarly to the literature, contradictory findings were seen between the two samples within this study. There was only one variable that was associated with the development of PPE prior to cycle 4, which was the absence of metastatic disease. Limitations of retrospective data may explain variation in some variables which may have been underreported; however it is likely that it is not possible to identify specific factors that increase the risk of PPE. This is the first study to have collected and analysed data related to friction, pressure and heat causing activities. These activities have been suggested as increasing the risk of developing PPE and form the basis of patient education to avoid these activities. Data from this study indicates that only a tendency to have warm hands is associated with an increased risk of PPE. Whilst this finding would need validating in larger studies, it is a unique contribution to the body of knowledge of PPE. This finding indicates that avoidance of activities that cause friction and pressure has no evidence base. Patients may therefore be avoiding activities that add to their enjoyment which at this stressful time in their lives may add to any psychological distress. Despite limitations of this study, the importance of the findings presented here lie in its usefulness in shaping future research to investigate identified variables, where before no direction was available.

Metalworking fluids (MWFs) are coolants and lubricants, which are widely employed in metal cutting works. They are designed to be a long lasting product. Manufacturers have designed MWFs with lack of awareness of end-of-life disposal by including biocides, which make biological treatment challenging. Here, Syntilo 9913 was used as a case study to develop a cradle-to-grave product that was biologically stable in use but amenable to sustainable hybrid biological treatment at end-of-life. The product was reverse engineered employing factorial design approach based on a priori knowledge of the product components. From the combinatorial work, it was observed that chemical interactions can results in synergistic and antagonistic effects in terms of the toxicity and biodegradability. One of the major components of most MWFs are amines such as Triethanolamine (TEA). TEA does not biodeteriorate in single compound screening, but in combination with many other components TEA was found to cause "softening" of MWF formulations. Octylamine was found to be best for "bio-hardening" but it was not economically sustainable. Hence, the modified biocide-free synthetic MWF, Syntilo 1601, was reformulated with TEA, isononanoic acid, neodecnoic acid, Cobratec TT50S, and pluronic 17R40, which were resistant to biological treatment. Although, no change in the overall oxidation state of the MWF, metabolic activity did occur as breakdown products were observed. This suggested that both raw materials and metabolic breakdown products were recalcitrant. Thus, immobilisation agents were applied to aid further biodegradation by removing toxic bottleneck compounds. It was found that hybrid nano-iron and kaffir lime leaf performed similarly in removing chemical oxygen demand and ammonium from the system. Work in this Thesis demonstrated that the combined use of biological treatment and immobilisation agents effectively overcome the limitations of biological treatment alone by removing bottleneck compounds, which allowed greater COD reduction. This laboratory scale is a proof of principle, which needs to be tested at full scale.

Introduction: Some past breast cancer radiotherapy regimens led to an increased risk of death from heart disease. Although heart dose from breast cancer radiotherapy has generally reduced over the past few decades, there may still be some cardiac risk. Estimation of future risk for women irradiated today requires both measurement of their cardiac dose and dose-response relationships, which depend on cardiac dosimetry of past regimens, in conjunction with long-term follow-up data. Methods: Virtual simulation and computed tomography 3-dimensional treatment planning on a representative patient were used to estimate mean heart and coronary artery doses for women irradiated since 1950 in 71 randomised trials in the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) overview. Patient-to-patient variability in cardiac dose was assessed. Heart and coronary artery doses were also calculated for breast cancer radiotherapy regimens used since the 1950s in Sweden. Cardiac doses from contemporary (year 2006) radiotherapy were assessed for 55 patients who received tangential breast cancer irradiation at a large UK radiotherapy centre. The maximum heart distance (i.e. the maximum distance between the anterior cardiac contour and the posterior tangential field edges) was measured for the left-sided patients, and its value as a predictor of cardiac doses assessed. Results: Mean heart dose for women irradiated in the EBCTCG trials varied from <1 to 18 Gray, and mean coronary artery dose from <1 to 57 Gray. Patient-to-patient variability was moderate. Mean heart dose for women irradiated in Sweden since the 1950s varied from <1 to 24 Gray, and mean coronary artery dose from <1 to 46 Gray. Heart dose from tangential irradiation has reduced over the past four decades. However, mean heart dose for left-sided patients irradiated in 2006 was 2 Gray and around half of them still received >20 Gray to parts of the heart and left anterior descending coronary artery. For these patients, maximum heart distance was a reliable predictor of cardiac doses. For the other patients, mean heart dose varied little and was usually less than 2 Gray. Conclusions: Cardiac doses from breast cancer radiotherapy can be estimated reliably and are now available for use in deriving dose-response relationships in the EBCTCG data and in a Scandinavian case-control study. Cardiac dose has reduced over the past four decades. Therefore the cardiac risk is also likely to have reduced. Nevertheless, for some patients, parts of the heart still receive >20 Gray in the year 2006.

Variations in drug metabolism may alter drug efficacy and cause toxicity; better understanding of the mechanisms and risks shall help to practice precision medicine. At the 21st International Symposium on Microsomes and Drug Oxidations held in Davis, California, USA, in October 2-6, 2016, a number of speakers reported some new findings and ongoing studies on the regulation mechanisms behind variable drug metabolism and toxicity, and discussed potential implications to personalized medications. A considerably insightful overview was provided on genetic and epigenetic regulation of gene expression involved in drug absorption, distribution, metabolism, and excretion (ADME) and drug response. Altered drug metabolism and disposition as well as molecular mechanisms among diseased and special populations were presented. In addition, the roles of gut microbiota in drug metabolism and toxicology as well as long non-coding RNAs in liver functions and diseases were discussed. These findings may offer new insights into improved understanding of ADME regulatory mechanisms and advance drug metabolism research. (C) 2017 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.