Oxidative protein folding within the ER depends on the enzymatic action of numerous chaperones and oxidoreductases. In addition, this process requires the influx of metabolites and energy, including FAD (flavin adenine dinucleotide) and molecular oxygen. Secretory proteins and proteins destined to the secretory pathway need to undergo this process in order to obtain stability and full functionality. Since secretory proteins that fail to fully fold are eliminated by degradation, the process of ER oxidative protein folding is part of a group of ER-associated mechanisms commonly referred to as ER quality control. Interestingly, the proteins that mediate ER quality control can be found in a variety of diverse subdomains of the ER. We have found that the ER-oxidoreductase Ero1 is located on the mitochondria-associated-membrane, the MAM. This specialized subdomain of the ER has been shown to be crucial for a number of processes such as the synthesis of phospholipids as well as calcium-channelling between the ER and mitochondria. The goal of this thesis was to identify possible retention mechanisms and motifs of Ero1 to the MAM.

Malaria remains a major cause of morbidity and death, especially in developing countries. The effectiveness of conventional antimalarial drugs is waning and there is an urgent need for novel therapeutic approaches. An understanding of malaria parasite biology should facilitate the development of effective therapies that prevent and/or treat malaria. The present studies explore the potential of vitamin A (retinol) as an antimalarial agent. Retinol may act by changing the oxidant milieu within the malaria parasite. Therefore, the nature and consequences of oxidant injury during malaria infection, and its treatment with retinol, have also been explored. The antimalarial potential of retinol was characterised using an established in vitro culture system allowing assessment of efficacy through [3H]-hypoxanthine uptake at different erythrocytic stages of development of Plasmodium falciparum. Retinol losses during culture were significant (>50%). After adjusting for these losses, all parasite stages (early rings to mature trophozoites) showed similar retinol sensitivity, with values of the mean assayed concentration resulting in 50% growth inhibition (IC50) ranging from 10.1 to 21.4 μM. This range was above that in normal human serum (<3 μM) but below that associated with haemolysis in culture (>43 μM). Retinol pre-treatment of uninfected erythrocytes did not inhibit merozoite invasion. Retinol-treated parasites exhibited vacuolisation of the food vacuole and membrane rupture. A P. berghei murine model was used to determine the in vivo preventive and therapeutic efficacy of retinol. Multiple-dose retinol given to healthy Swiss mice before parasite inoculation reduced parasitaemia by 30%, a result comparable to the previously reported reduction in morbidity after vitamin A supplementation in children. A lesser reduction in parasitaemia of 10% was observed when retinol was given after the parasitaemia reached 10-15%. Retinol was ineffective in reducing parasitaemia when given either as single-dose supplementation post-inoculation or at regular intervals before and after infection. Retinol supplementation did not change plasma retinol concentrations during malaria infection whether or not retinol was given, but malaria attenuated the increase in liver retinol content. These data suggest that retinol has most value as prophylaxis. In contrast to published data from humans, previously healthy mice did not develop low plasma retinol concentrations during acute infection

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available online.

Diss. (sammanfattning) Uppsala : Univ., 2001. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Tartu, 2004. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Louisville, 2003. / Department of Pharmacology and Toxicology. Vita. "December 2003." Includes bibliographical references (leaves 161-185).

Thesis (M. Med. Sc.)--University of Hong Kong, 2006.

Theses (M.S.)--Marshall University, 2007. / Title from document title page. Includes abstract. Includes vitae. Document formatted into pages: contains ix, 81 pages including illustrations. Bibliography: p. 69-77.

Iron is an essential element for living organisms. However, as it is a transition metal, it can participate in Fenton reaction resulting in generation of free radicals and oxidative damage to tissues. Antioxidants may prevent possible iron toxicity by chelating free iron or scavenging free radicals. Falvonoids are naturally occurring substances that are capable of formation of complexes with metals, including iron. T h e y have been show to possess antioxidant activity, which depends on molecular complexity of numerous types of flavonoids, e.g. quercetin and silibinin. Bisphosphonates are synthetic drugs used to treat various metabolic diseases of bones. Their principál effect is an inhibition of osteclast activity leading to a decreased bone resorption. Bisphosphonates have been however shown to exert some antioxidant activity in in vitro experiments, too. The aim of this PhD thesis was to investigate the role of iron in toxicity of other metals (cadmium) and the effect of flavonoids (quercetin and silibinin) and bisphosphonates (clodronate, etidronate and risedronate) on iron-induced oxidative damage in vivo. Experiments were performed in male mice (CD-1, Charles River, 25-35 body weight). Iron was administered intraperitoneally or in the diet. Cadmium was administered subcutaneously. Flavonoids and...