The role of stress (both psychosocial and oxidative) in the pathophysiology of several chronic diseases has been documented and has become a focus for chronic disease prevention and management. Although, psychosocial stress (PS) and oxidative stress (OS) have different mechanisms through which they impact health, they both cause physiological imbalance which might subsequently lead to a disease state. Laboratory and observational studies have linked both stresses to the pathophysiology of diabetes mellitus (DM) and hypertension. However, findings from previous studies have not been entirely consistent and results have varied based on the study population and the stress-measurement tool used. Given the gaps in the literature, three studies were conducted to examine: (1) the relationship between PS and glycemic control; (2) the association between PS and estimated glomerular filtration rate (eGFR); and (3) the association between OS and hypertension among adults. In the first two studies, a longitudinal data from Kaiser Permanente Georgia (KPGA) survey on Health and Healthy Behaviors linked to patients’ laboratory and pharmacy records was used. In the third study a cross-sectional data from Study on Race, Stress and Hypertension was used. The first study examined the association between baseline measure of work-related PS and glycemic control using both cross-sectional and longitudinal designs. None of the four PS sub-scales or the overall PS measure at the work environment was significantly associated with glycemic control at either study baseline or over time. The second study examined the association between general measures of PS and changes in estimated glomerular filtration rate (eGFR) over time in a structural equation model framework. No significant direct association was observed between general PS measure and eGFR decline. However, age, race, mean arterial pressure and insulin use were found to be associated with eGFR decline. The third study examined the association between hypertension and: 1) four markers of OS (F2-Isoprostanes, Fluorescent oxidative products, copy number of mitochondrial DNA and Gamma-tocopherol); and 2) plasma nutrient based oxidative balance score (OBS). The OBS was inversely associated with hypertension, but none of the OS markers was significantly associated with hypertension after adjusting for study covariates. The current work highlights some of methodological issues in the assessment of PS to examine their relationship with DM control and complications. The study also highlights the need for more future studies to be conducted to confirm the association between OBS and hypertension, preferably longitudinal studies. If future studies confirm this finding, then the mechanisms by which OBS may influence risk of hypertension would need to be explored further.

Iron is an essential trace element for almost all living organisms. Iron overload in cells and tissues, however, leads to their disruption. Most oftenly damaged are parenchymatic organs such as the liver, pancreas and heart. The aim of this thesis was to create cellular in vitro models for the investigation of effects of excess iron on hepatocytes and pancreatic beta cells and on these models to investigate cellular processes which lead to cellular damage during iron overload. We focused on examining the presence of oxidative and endoplasmic reticulum stress and the activation of apoptotic cell death. For our experiments, we used HEP-G2 cell line which represents human hepatocytes and NES2Y cell line which represents human pancreatic beta cells. To study the mechanisms of cellular damage during iron overload, we used two approaches by which we observed both acute and long-term effects of high levels of iron on damage of the tested cell lines. When studying the acute effect of excess iron on the cells, we applied high doses of iron (using 15 mM ferric citrate in medium) that led to the activation of cell death in hours. Long-term effects of iron overload were tested on cells regularly cultivated in the presence of 50 μM and 100 μM ferric citrate over a period of several months. Iron concentrations...

Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...