published_or_final_version / abstract / toc / Chemistry / Doctoral / Doctor of Philosophy

Nustatyti vitamininių – mineralinių priedų – „Sel-PlexTM“, „Suplex E-50000/K/Selenium“, „Suplex E/Selenium“ (savo sudėtyje turinčių seleno) ir „Oxistop“ – pasižyminčių antioksidaciniu veikimu, įtaką, kiaulių hematologiniams, mėsos fiziniams ir cheminiams bei zootechniniams produktyvumo rodikliams. Remdamiesi atliktų bandymų duomenimis, paruoštos kiaulininkystės ūkiams ir ūkininkams rekomendacijos dėl vitamininių – mineralinių priedų, savo sudėtyje turinčių organinio ir neorganinio seleno formų ir pasižyminčių antioksidaciniu veikimu panaudojimo ir šėrimo efektyvumo penimoms kiaulėms. Pirmą kartą Lietuvos sąlygomis ištirtas kiaulių kraujyje fermento glutationo peroksidazės kiekis ir jo kitimas per visą bandymo laikotarpį, priklausomai nuo seleno koncentracijos ir formos racione. Ištirta vitamininių – mineralinių „Sel-PlexTM“, „Suplex E-50000/K/Selenium“, „Suplex E/Selenium“ ir „Oxistop“ priedų įtaka kiaulių augimui, kraujo biocheminiams ir morfologiniams rodikliams, mėsos fizinėms savybėms ir cheminei sudėčiai bei įvertintas seleno kiekis nustatant jį kraujyje ir dengiamuosiuose plaukuose (šeriuose). / To determine the influence of vitamin-mineral supplements -„Sel-PlexTM“, „Suplex E-50000/K/Selenium“, „Suplex E/Selenium“ (containing selenium) and „Oxistop“ (having antioxidational effect) on pig‘s haematological, meat‘s physical, chemical and zootechnical rates of productivity. First time in Lithuania the enzyme glutathione peroxidase in pig‘s blood and its change during the experimental period, depending on selenium concentration and form in ration was examined. The influence of vitamin-mineral supplements - „Sel-PlexTM“, „Suplex E-50000/K/ Selenium“, „Suplex E/Selenium“ and „Oxistop“ on pig‘s growing, blood biochemical and morphological rates, meat‘s physical and chemical composition was examined. Also the amount of selenium in blood and hair was evaluated. Appealing to the test data, recomendations about pig‘s feeding effectivity and using vitamin-mineral supplements containing organic and inorganic forms of selenium and having antioxidational effect were prepared for swine-breeding farms and farmers.

Using computational methods, the formation pathways and structures of four experimentally-observed DNA intrastrand cross-links are determined. These lesions originate from the uracil radical and are of particular importance due to their potential role in the activity of the 5-halouracils as radiosensitizing agents in anti-tumour treatments. The formation pathways are studied with density functional theory under conditions relevant to both UV and ionizing radiation. Results reveal these intrastrand cross-links are likely to form under therapeutic conditions and provide an explanation for their observed formation preferences. The structures of the cross-links in DNA are determined with molecular dynamics simulations to reveal the distortions these lesions induce to the helix. This has provided information about the potential biological implications of these lesions, where results indicate intrastrand cross-links are likely both mutagenic and cytotoxic. Therefore, these lesions may contribute to tumour cell death in the therapeutic use of halouracils. / xvi, 147 leaves : ill. (chiefly col.) ; 29 cm + 1 CD-ROM

Suspensions of pancreatic islet cells from ob/ob-mice were incubated with Trypan Blue. Microscope photometry showed that apparently viable cells excluded the dye completely, whereas the nuclei of non-viable cells accumulated Trypan Blue by a saturable process. Alloxan rapidly increased the permeability of the plasma membrane in mouse 3-cells; the exclusion of Trypan Blue is a valid and useful measure of islet cell viability following alloxan exposure. The diabetogenic action of alloxan may be mediated by hydroxyl radicals. In several biological systems hydroxyl radicals are formed by an iron-catalyzed reaction between superoxide anion radicals and hydrogen peroxide. To test whether this applies to alloxan diabetogenicity, the effects of superoxide dismutase, catalase, scavengers of hydroxyl radicals, and metal ion chelators were tested (a) in a cell-free radical-generating system and (b) on islets and islet-cells exposed to alloxan In vitro. The effect of longtime-circulating superoxide dismutase injected prior to alloxan was tested on mice in vivo. Luminol chemiluminescence was used to monitor alloxan-dependent radical production. Accumulation of 8^Rb+ and exclusion of Trypan Blue were used as cell viability criteria in isolated mouse islets and islet-cells. Blood glucose was determined to monitor the development of diabetes in living animals. Superoxide dismutase, catalase, scavengers of hydroxyl radicals, and metal ion chelators inhibited the alloxan-dependent chemiluminescence and decreased the toxic effects on Rb+ accumulation or Trypan Blue exclusion in islets and islet-cells. Superoxide dismutase, linked to polyethylene glycol and injected 12 hours before alloxan, largely prevented the development of alloxan diabetes. Alloxan toxicity _in vitro and in vivo seems to depend on the formation of superoxide radicals and hydrogen peroxide which in turn form the noxious hydroxyl radical via an iron-catalyzed Haber-Weiss reaction. As free radicals and hydrogen peroxide can be formed by other chemicals and during inflammation, and inflammation may accompany the outbreak of human diabetes, studies on the beneficiary effects of superoxide dismutase and other scavengers of free radicals in other forms of diabetes seem warranted. / <p>S. 1-38: sammanfattning, s. 39-74: Härtill 6 uppsatser</p> / digitalisering@umu

Using computational methods, we have investigated the chemistry of 3-phenylpropyl radical systems. These systems are of importance to polymer chemistry as free radical additions involving these species are integral in the production of styrene-containing plastics. Although the addition reactions have been well studied, the other reaction pathways, namely f3-fragmentation and cyclization, have not been as comprehensively studied. As a result, our computational study involved 3-phenylpropyl radical systems that had been systematically mono-substituted at five positions, two on the propyl chain and three on the aromatic ring. This computational analysis consisted of calculation of optimized geometries and energies for reactants, products, and transition states, followed by examination of derived thermochemical quantities (enthalpies of activation and reaction), and critical structural parameters (transition bond lengths and bond angles) of the systems. Finally correlation of structure and reactivity of the various systems was attempted. Density functional theory (DFT) using the B3-LYP functional and the 6-31 G(d) basis set was selected as the level of theory. / Department of Chemistry

Regular physical activity (PA) leads to an increased quality of life by means of certain physiological adaptations. Regular PA is beneficial to the human body and its functionality, including the physiological, biochemical and even psychological modalities. During PA an increased burden is placed on all physiological mechanisms due to the increased energy demand, resulting in an adaptation of the physiological systems. Currently the biochemical mechanisms by which these adaptations occur are not well understood or defined. During the flow of electrons through the electron transport chain in the mitochondria free radicals and reactive oxygen species (ROS) are produced. PA results in increased ROS production. The relationship of different exercise intensities and ROS production with resulting DNA damage is unclear. These free radicals and ROS disturb the pro-oxidant anti-oxidant balance resulting in oxidative stress. When this balance is disturbed oxidative stress could lead to potential oxidative damage, Oxidative damage occurs in lipid, protein and nucleic acid macromolecules. ROS can attack DNA bases or deoxyribose residues to produce damaged bases and/or single and double strand breaks. When the DNA is regarded and the damages are replicated it could cause mutations or apoptosis, affecting the cell function and physiology. The purpose of this study was to investigate the influence of different aerobic intensities on oxidative DNA damage and repair in middle aged men by means of the Comet assay. Five PA males and five physically inactive males were assigned to an experimental and control group respectively. The subjects did not differ significantly at baseline. The VO2-max of each subject was determined at baseline. Subjects were then randomly assigned to 60, 70, 80 and 90% of individual baseline VO2-max intensities for an acute exercise intervention of 30 minutes on a bicycle ergometer. Blood sampling was done at baseline, post-exercise and 24 hours post-exercise for oxygen radical absorbance capacity (ORAC) and hydroperoxide analysis (dROM). Peripheral blood was obtained for DNA damage testing by means of Comet analysis at baseline, post-exercise, 5, 15, 30 minutes, and also 6, 12, 24, 48 and 72 hours after exercise. The results obtained indicated that subjects who regularly participate in PA had an increased baseline reading of ORAC and dROM values. ORAC levels after each acute exercise session increased, with the highest increase in the control group, with a decrease in the direction of baseline readings 24 hours post exercise. A biphasic damage-repair cycle over the 72 hour period was observed with the Comet analysis. The most damaged cells occur directly after acute exercise. The highest incidence of DNA damage over a 72 hour period was observed at 70% VO2-max, with the least amount of damage after 90% VO2-max. In conclusion the study indicates stress proteins or other kinds of physiological reaction to minimize the damaging effect of oxidative stress, is in place to restore the cell's homeostasis. Thus PA results in the development of oxidative DNA damage. To minimize DNA damage the optimal intensity for acute physical exercise is between 70-80% VO2-max. At higher intensities the release of stress proteins are initiated to buffer the damaging effect of oxidative stress and to restore homeostasis. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007.

Tyrimo metodai: Ląstelių sėjimo metodika; ląstelių tankio nustatymas; ląstelių gyvybingumo nustatymas MTT testu; neuronų žūties įvertinimas fluorescencinės mikroskopijos metodu; viduląstelinių RS kiekio įvertinimas; ekstraląstelinių RS kiekio įvertinimas; statistinė analizė. Tyrimo tikslas: Ištirti įvairių koncentracijų lektinų, išskirtų iš Phaseolus vulgaris L., antioksidacinį/ prooksidacinį poveikį ir įtaką C6 ląstelių gyvybingumui. Tyrimo uždaviniai: 1. Atlikti literatūros duomenų analizę apie lektinų, išskirtų iš Phaseolus vulgaris L., biologinį poveikį; 2. Nustatyti įvairių koncentracijų lektinų, išskirtų iš Phaseolus vulgaris L., antioksidacinį/prooksidacinį aktyvumą; 3. Nustatyti įvairių koncentracijų lektinų poveikį C6 ląstelių kultūros gyvybingumui. Tyrimų rezultatai: 1. Buvo matuojami vandenilio peroksido pokyčiai esant 1 - 10 µg lektino koncentracijoms ir nustatyta, kad skirtingų koncentracijų lektinas neveikia neutralizuojančiai vandenilio peroksido kiekio. 2. Atlikti vandenilio peroksido matavimai DMEM terpėje su 1 - 10 µg lektino koncentracijoms parodė, kad lektinas, priklausomai nuo jo koncentracijos, negeneruoja laisvųjų radikalų. 3. Buvo matuojamas glioblastomos C6 ląstelių gyvybingumas su MTT po 24 valandų ir nustatyta, kad didėjant lektino koncentracijai ląstelių gyvybingumas sparčiai mažėjo: 5 µg koncentracijos lektinas gyvybingumą sumažino beveik 2 kartus (iki 57,2111.16%), o 10 µg koncentracijos lektinas ląstelių gyvybingumą sumažino beveik 13... [toliau žr. visą tekstą] / Methods: The cell cultivation method; measurement of cell density; determination of cell viability with MTT assay; assessment of neuronal death with fluorescent microscopy; measurement of intracellular RS; measurement of extracellular RS; statistical analysis. The aim of research: To investigate antioxidative/prooxidative effects of different concentrations of the lectin, isolated from Phaseolus vulgaris L., and influence on the viability of the C6 cells. Goals of the study: 1. To perform an analysis of the literature on the biological effects of lectin, isolated from Phaseolus vulgaris L.; 2. To determine antioxidative/prooxidative activity of different concentrations of the lectin, isolated from Phaseolus vulgaris L.; 3. To determine effect on viability of the C6 cell culture using different concentrations. Results: 1. Concentrations of hydrogen peroxide were measured with 1 - 10 µg concentrations of lectin and it was found, that different concentrations of lectin did not neutralize hydrogen peroxide. 2. Measurements of hydrogen peroxide in DMEM medium with 1-10 mg concentrations of lectin showed, that the lectin, depending on it's concentration, did not generate free radicals. 3. Viability of cells was measured in C6 glioblastoma cells with MTT after 24 hours and it was found, that when concentration of lectin increased, viability of cells rapidly decreased: 5 µg concentration of lectin reduced the viability of almost 2 times ( up to 57.21% ± 11.16% ) and at 10 µg... [to full text]

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Diabetes mellitus is a chronic syndrome affecting carbohydrate, protein, and fat metabolism. It is characterized primarily by relative or absolute insufficiency of insulin secretion (type I diabetes or IDDM) or concomitant insensitivity / resistance to the metabolic action of insulin on target tissues (Type II diabetes or NIDDM), both resulting in hyperglycaemia. Diabetes mellitus is known to induce microvascular changes and alterations to neuronal functions. The neurovascular system comprising of unmyelinated primary afferent sensory neurones and the microvasculature innervated by these nerves play a major role in modulating inflammatory and tissue repair processes. Sensory nerve terminals respond to injury via the release of sensory neuropeptides which mediate inflammation and tissue repair. These processes are known to be altered in diabetes. This thesis is concerned with the role of diabetes in modulating microvascular blood flow directly and indirectly via modulating sensory nerve activity and the effect of these changes on repair processes in skin of 4 weeks streptozotocin (STZ)-induced diabetic rats. The following hypotheses were examined: 1. That factors implicated in long-term diabetic vascular damage play a role in altering skin microvascular function in early diabetes. 2. That preventing the deleterious effects of these factors could improve skin microvascular blood flow and skin repair processes in early diabetes. (For complete abstract open document)

Thesis (Ph.D.)--McMaster University (Canada), 1991. / Source: Dissertation Abstracts International, Volume: 53-01, Section: B, page: 0308. Supervisor: John Warkentin.