Increased reactive oxygen species (ROS) have been reported to be at the centre of various diseases. Although several reports have implicated elevated levels of ROS in the pathogenesis of diabetes mellitus, the early detection of ROS is still not attainable. This limitation causes difficulty in the early diagnosis of ROS related disorders. The presence of high levels of ROS was reported to result in differential expression of antioxidant genes involved in protecting cells from their deleterious effects. Among the antioxidant genes that are expressed, it was postulated that expression of metallothioneins (MTs) are also induced. MTs are low molecular weight, cysteine-rich proteins involved in metal homeostasis and reported to harbour antioxidant function. The aim of this investigation was to explore MTs as biomarkers for elevated levels of ROS in whole blood of type 2 diabetic (T2D) individuals. The level of ROS in diabetic, non-diabetic as well as individuals at risk of developing T2D was determined via the use of biochemical assays. Real-Time PCR was utilised to analyse the expression of MTs and the presence of MT proteins was analysed via the ELISA. In this study it was observed that diabetic individuals had elevated levels of ROS. However, no significant difference in the expression of MTs and the presence of MT proteins between the diabetic and non-diabetic individuals was observed. In vitro experimental conditions indicated that MT expression is induced by elevated levels of ROS. In pathological conditions the ROS-dependent induction of MT expression needs to be elucidated further. It therefore can be suggested that MTs can not yet be utilised as biomarkers for the detection of elevated levels of ROS in pathological conditions with ROS aetiology. This investigation also highlights the fact that blood is not an optimal medium in which this objective can be attained. / Thesis (Ph.D. (Biochemistry))--North-West University, Potchefstroom Campus, 2005.

The prevalence of obesity has increased dramatically in the past decade. This foreshadows an increase in the rates of morbidity and mortality from obesity related diseases. The high prevalence of coronary heart disease (CHD) is a problem throughout the world as well as in South Africa The process of urbanisation of Africans from rural to urban areas is exposing the African population to Western lifestyles, with an increase in the incidence of CHD being reported. Research is more frequently proposing that obesity may be seen as a factor linking elevated C-reactive protein (CRP) concentrations and atherosclerosis. CRP is an acute phase reactant and a sensitive marker for acute and chronic inflammation of diverse causes. This poses the question of whether the increased risk of diabetes, CHD and many other chronic diseases in the obese might be explained by a state of chronic systemic inflammation. The purpose of this study was, therefore, firstly to determine whether there is an association between CRP concentrations and body composition in 19 to 60 year old black women. Partial Pearson correlations coefficients were used to determine associations between CRP and several body composition variables. Body mass index (BMI), waist circumference, percentage body fat and waist-hip-ratio (WHR) were all significantly correlated with CRP throughout the anthropometric spectrum. An analysis of variance (ANOVA) with a Games-Howell post hoc test was done to determine statistically significant differences among the different categories within each of the body composition variables. Significant differences (p < 0.05) were found within the categories of all the measured body composition variables, except for the various WHR categories. During a signal detection analysis, BMI was identified as the best predictor of increased CRP concentrations at a cut-off point of 27.68 kg/m2. The second purpose of this study was to assess the relationship of CRP to traditional cardiovascular risk factors in the study's population sample of 19 to 60 year old black women. Pearson correlation coefficients were used to analyse log-normalized CRP concentrations as the dependent variable in relation to several variables which form part of the traditional risk factors for CHD. All of the variables were significantly correlated with CRP at the level of p ≤ 0.05, except for total cholesterol and low-density lipoprotein cholesterol. BMI, percentage body fat and fibrinogen levels were associated with InCRP at a practically significant level of r ≥ 0.5. BMI and fibrinogen were also found to be independently associated with InCRP with p ≤ 0.05 during a forward stepwise multiple linear regression analysis. Within this study's population sample, it was found that those women who presented with six traditional risk factors had a three to five-fold increase in CRF' concentrations compared to women with three or less risk factors. Further research is required to determine appropriate intervention programmes which could prevent or reduce the incidence of CHD among the obese by means of weight-loss, therefore, potentially lowering elevated CRP concentrations. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2005.

Septic shock is a leading cause of death in intensive care units. As part of the septic process, the endothelium becomes activated and propagates the septic condition. It has become evident that reactive oxygen species (ROS) are involved in the signaling of mediators of sepsis, such as tumor necrosis factor-alpha (TNF-alpha) and the lipopolysaccharide coating of gram-negative bacteria (LPS). An important source of these ROS is NADPH oxidase, which is a ubiquitously expressed enzyme complex that also exists in endothelial cells (EC). We showed that O2- from NADPH oxidase was important for LPS, as well as TNF-alpha, induction of two markers of an activated endothelium, interleukin-8 (IL-8) and intercellular adhesion molecule-1 (ICAM-1) in human umbilical vein endothelial cells (HUVEC). / Expression of a gene can be increased by a rise in transcription as well as post-transcriptional changes, such as mRNA stability modifications. We assessed the role of NADPH oxidase in this process and found a complex interaction. Although LPS increases IL-8 transcription, it also destabilizes IL-8 mRNA in a p38 and extracellular signal-regulated kinase (ERK) MAPK dependent manner, which was only evident after blocking NADPH oxidase. This regulation involved the mRNA de-stabilizing factor tristetraprolin (TTP). In contrast, TNF-alpha enhanced the stability of IL-8, IL-6 and ICAM-1 mRNA in a p38 MAPK dependent, but NADPH oxidase independent manner. Furthermore, LPS did not have an effect on mRNA stability of IL-6 or ICAM-1 in our system. Thus, we conclude from our studies that the NAPDH oxidase is important for the induction of inflammatory molecules in LPS and TNF-alpha treated EC and is also involved in mRNA stability regulation of these molecules in a signal and gene specific fashion.

Reactive spray deposition technology (RSDT) is a method of depositing films or producing nanopowders through combustion of metal-organic compounds dissolved in a solvent. This technology produces powders of controllable size and quality by changing process parameters to control the stoichiometry of the final product. This results in a low-cost, continuous production method suitable for producing a wide range of fuel cell related catalyst films or powders. In this work, the system is modified for direct deposition of both unsupported and carbon supported layers on proton exchange membrane (PEM) fuel cells. The cell performance is investigated for platinum loadings of less than 0.15 mg/cm² using a heterogeneous bi-layer consisting of a layer of unsupported platinum followed by a composite layer of Nafion®, carbon and platinum. Comparison to more traditional composite cathode architectures is made at loadings of 0.12 and 0.05 mg platinum/cm². The composition and phase of the platinum catalyst is confirmed by XPS and XRD analysis while the particle size is analyzed by TEM microscopy. Cell voltages of 0.60 V at 1 A/cm² using H₂/O₂ at a loading of 0.053 mg platinum/cm² have been achieved.

Aquesta tesi centra els seus esforços en l'àmbit de la microfluídica, un camp relativament recent dins de la Mecànica de Fluids, amb un futur prometedor i amb un ritme d'investigació intens en les seves diferents especialitzacions. En aquest sentit, la tesi presenta dos aportacions científiques principals. Primer, aporta una eina numèrica d'elaboració pròpia per realitzar simulacions de fluxos reactius en microcanals. Eina que s'aplica satisfactòriament a la identificació dels principals processos de transport involucrats en la oxidació parcial del metà per a produir gas de síntesi, i a l'estudi de l'efecte que tenen alguns paràmetres d'operació en aquest procés reactiu. Segon, estén el coneixement dels fluxos multifàsics en microunions en T, estudiant experimentalment fluxos de dues fases amb fluids principalment miscibles i en condicions supercrítiques, que son portats al seu equilibri vapor-líquid. Durant aquest estudi, a més, reporta un succés inesperat que presenta futurs reptes en l'aplicació d'aquest tipus de fluxos multifàsics. / The present thesis focuses on microfluidics, a relatively recent field of Fluid Mechanics with promising expectations and with an intense scientific interest on its different areas. In this regard, the thesis aims to provide two main scientific contributions. First, it presents an in-house numerical tool to carry out simulations of reactive flows within microchannels. The tool is successfully applied to the identification of the main transport phenomena involved on the partial oxidation of methane to produce synthesis gas, and to the analysis of the effect of several operating parameters on this reactive process. Second, it extends the knowledge on multiphase flows in microfluidic T-junctions with an experimental study of two-phase flows of mixtures of potentially miscible fluids, in supercritical conditions and in vapour-liquid equilibrium. In this study it is also reported an unexpected phenomenon, which brings new challenges to the application of these kind of multiphase flows.

Previous findings have indicated that oxidative stress plays a role in the development of osteoporosis and that individual polyphenols, by virtue of their antioxidant properties, may mitigate these damaging effects. Nutritional supplements, greens+ bone builderTM, containing polyphenols and other micronutrients beneficial for bone health are of recent interest as complementary strategies in the management of osteoporosis. A randomized controlled study was conducted to explore the combined effects of the nutrients found within the supplement on bone health for 8 weeks. Total polyphenol content and antioxidant capacity increased whereas oxidative stress parameters and the bone resorption marker, crosslinked C-telopeptide of type I collagen decreased after supplementation. There was no significant change in the bone formation marker, procollagen type I N-terminal propeptide. This thesis shows an association of polyphenols with other micronutrients acts through their antioxidant capacity to decrease oxidative stress parameters and bone resorption, thus potentially reducing the risk for osteoporosis.

Lycopene is a potent carotenoid antioxidant shown to decrease the risk of chronic diseases associated with oxidative stress and has recently begun to be studied in relation to osteoporosis. However, studies specifically associating intervention with lycopene and a decreased risk for osteoporosis have not yet been conducted, and the mechanisms by which lycopene affects bone have yet to be elucidated. The purpose of this thesis was to explore the hypotheses that supplementation with lycopene would increase antioxidant capacity while decreasing oxidative stress parameters; subsequently decreasing bone turnover markers, and thus the risk of osteoporosis in postmenopausal women. Specifically, experiments were designed to determine whether lycopene acts in its antioxidant capacity to improve bone health, and to delineate the mechanisms of these effects. These hypotheses were investigated through a cross-sectional study, a randomized controlled clinical study, and in vitro studies on human osteoblast cells. The results presented in this thesis demonstrate that intervention with the potent antioxidant lycopene significantly increased concentrations of the 5-cis isomer and resulted in significantly decreased oxidative stress parameters in postmenopausal women. This decrease in oxidative stress parameters resulted in significantly decreased concentrations of the bone resorption marker crosslinked N-telopeptides of type I collagen (NTx). The typical diet of participants included a relatively low intake of lycopene, and the corresponding serum lycopene concentrations were not as effective in decreasing biomarkers of oxidative stress and bone resorption as those obtained from supplementation with lycopene to increase 5-cis serum lycopene. Studies on the paraoxonase enzyme suggest that lycopene is most effective in quenching oxidative stress to decrease bone turnover markers when the internal antioxidant defenses are insufficient or decremented. Mechanisms demonstrated by the in vitro findings suggest that cis lycopene is capable of both preventing and repairing the damaging effects of oxidative stress in osteoblasts. Overall, this thesis provides evidence that lycopene acts through its antioxidant capacity to decrease oxidative stress parameters and bone turnover markers, and may, therefore, reduce the risk for osteoporosis. Based on these findings, the consumption of lycopene by women to improve overall bone health should be considered.

Previous findings have indicated that oxidative stress plays a role in the development of osteoporosis and that individual polyphenols, by virtue of their antioxidant properties, may mitigate these damaging effects. Nutritional supplements, greens+ bone builderTM, containing polyphenols and other micronutrients beneficial for bone health are of recent interest as complementary strategies in the management of osteoporosis. A randomized controlled study was conducted to explore the combined effects of the nutrients found within the supplement on bone health for 8 weeks. Total polyphenol content and antioxidant capacity increased whereas oxidative stress parameters and the bone resorption marker, crosslinked C-telopeptide of type I collagen decreased after supplementation. There was no significant change in the bone formation marker, procollagen type I N-terminal propeptide. This thesis shows an association of polyphenols with other micronutrients acts through their antioxidant capacity to decrease oxidative stress parameters and bone resorption, thus potentially reducing the risk for osteoporosis.

Till följd av den hårda utbyggnaden av vårt samhälle åtgår en stor mängd naturresurser. Samtidigt som samhället utveckas sätts allt högre krav på att det ska hushållas med naturresurser, inte minst genom införandet av miljömålet en ”God bebyggd miljö”. Enligt detta miljömål ska användningen av såväl mark som naturresurser ske på ett så hållbart sätt som möjligt. Samtidigt med detta skapar den svenska stålindustrin över en miljon ton slagg årligen, varav en stor del deponeras. Då deponeringen är kostsam pågår i dagsläget många försök att finna användningsområden för slagg så att deponeringskostanden ska undvikas. Bland annat har slagg i vissa fall visats kunna ersätta naturmaterial i formav sten, grus och sand vid till exempel vägbyggen och deponitäckningar. Slagg har i försök även visat på en vattenrenande förmåga då föroreningar fastläggs på slaggen.Detta har lett till försök med att använda slagg som filtermaterial i reaktiva filter där sand traditionellt sett ofta används. Denna studie avsåg att undersöka om slagg från Avesta Jernverk fungerar att använda i reaktiva filter för att rena vatten som är förorenade med till exempel tungmetaller och fosfor. Detta gjordes genom att skaka tre olika slagger som produceras i Avesta med ett lakvatten från en kommunal deponi med behov att renas från bland annat fluor, fosfor, kadmium, klorider, nickel och zink. I försöken användes en EAF-slagg och två AOD-slagger. För att undersöka om upptaget av föroreningar påverkades av om slaggen hade nya ytor användes både nykrossad slagg och slagg som varit placerade utomhus under 71 dagar. Resultaten visade att slaggerna som bildas vid Avesta Jernverk har en vattenrenandeförmåga och att samtliga av de testade slaggerna sorberade aluminium, fosfor och zink. Utöver dessa ämnen sorberade flera av slaggerna även arsenik, fluor, koppar och magnesium. Resultatet visade också på ett tidsberoende hos sorptionen, då mer föroreningar togs upp om slagg och lakvatten skakades i fem dygn jämfört med om skaktiden var femton minuter eller fyra timmar. Det gick dock inte att avgöra om slagg med nygjorda ytor sorberade bättre än slaggen som stått utomhus. Beräkningar utfördes och visade att ett slaggfilter dimensionsmässigt skulle vara möjligt att bygga och att en kornstorlek som sand skulle behövas för att få rätt uppehållstid. / As a result of the harsh exploitation and development of our society, a large amount of natural resources are needed. While the society develops it becomes more and more important to economise natural resources. This is also stated as an environmental objective, called "A good built environment" by the Swedish government. According to this environmental objective, the use of both land and natural resources should be undertaken in the most sustainable way possible. At the same time the Swedish steel industry produces over one million tonnes of slag annually, which is mostly deposited. Slag is a byproduct from the steel manufacturing process. When disposal is costly, many attempts to find usage for slag are done instead. For instance, in some cases it has been as replacement for natural resources as stone, gravel and sand in road constructions and landfill covers. Slag has also been shown to have a water-purifying capacity since contamination can be sorbed by the slag. This has led to attempts to use slag as filter material in reactive filters where sand traditionally is widely used. This study aimed to investigate whether slag from Avesta Works could be used in reactivefilters to purify water that is contaminated with heavy metals and phosphorus. This was done by shaking a number of slags produced in Avesta with leachate water from amunicipal landfill, Karlslund. The leachate water needs to be purified from i.a. fluorine, phosphorus, cadmium, chloride, nickel and zinc. In the experiments an EAF slag and two AOD slags were used. To investigate if the sorption of contamination in the leachate water was affected by the age of the particle surfaces, both slags with freshly made and aged surfaces were tested. The aging of the slags was created by placing the slags outdoor for 71 days. The results showed that the slags formed at Avesta Works has a water-purifying ability and that all of the tested slags sorbed aluminum, phosphorus and zinc. Beside these substances, some of the slags also sorbed arsenic, fluorine, copper and magnesium. Theresults also showed a time-dependence of the sorption: More contaminations were sorbed after reacting slag and leachate water for five days compared with fifteen minutes or four hours. It was not possible to determine if the slags with fresh surfaces sorbed better than the slags with aged surfaces. Calculations showed that a filter containing slag should be possible to build dimensionally and that the grain size of sand would be needed to get the required retention time.

Selection for large body size can result in the development of obesity, which in mink females is associated with poor reproduction and metabolic diseases. Caloric restriction is effective in diminishing oxidative stress and delaying aging-related diseases. This study investigated the effects of moderate diet restriction (MDR) during the fall on body condition, health, and reproductive success of mink (Neovison vison) breeder females. The 100 control (CTRL) females were fed according to normal farm feeding practice and the 100 sister-pair MDR females were fed about 20% less. In the fall, more ideal body weights and body condition scores (BCS) were seen in the MDR females, and they produced larger litter sizes. In addition, the MDR females exhibited less deoxyribonucleic acid (DNA) damage than the CTRL females. Telomeres were elongated in both groups. This dietary management practice is anticipated to result in significant advancement in the fur industry, both economically and welfare-wise.