No description available.

No description available.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

In the onset of many chronic illnesses including Parkinson’s, Alzheimer’s, and cardiovascular diseases, there is evidence to support the delicate balance between prooxidant and antioxidant species is shifted in favor of the former. Under these conditions, many reactive oxygen species (ROS) including hydroxyl radicals, are generated. Hydroxyl radicals formed in close proximity to DNA, nucleotides, proteins, and lipids rapidly oxidize these biological molecules in a nonspecific way. However, their toxicity is limited by their short lifetimes. Currently, the mechanism by which hydroxyl radicals are involved in the onset of many illnesses, particularly with regard to lipid peroxidation, has yielded some controversy in the literature. Conventional studies which generate hydroxyl radicals with Fenton chemistry through bolus additions of iron and hydrogen peroxide do not mimic conditions found physiologically because there is a steady-state concentration of hydrogen peroxide concentration found in normal cellular systems. Also, former reports that used fluorescent fatty acids or free probes intercalated within liposomal membranes did not have the probes covalently attached to the phospholipids making up the liposomes. Thus, the actual placement of the probes over the analysis time may vary with experimental conditions. The objective of this research project was to prepare, characterize, and employ liposomes as models for cell membranes during free radical oxidation. Also, compared to the popularly-used technique of electron spin resonance, (ESR), our aim was to use a fluorescence-based approach which yielded the advantages of high sensitivity, fast analysis time, and less expensive equipment requirements. Degradation of fluorescently-tagged liposomes with probes covalently bound to the phospholipids was correlated with the ability of hydroxyl radicals and other possible reactive oxygen species to penetrate into the liposomes to deeper into the lipophilic layer. However, alone this experimental setup may not fully define the mechanistic role of hydroxyl radicals in lipid oxidation. Thus, a complementary approach embracing the use of MALDI-TOF mass spectrometry, lipophilic scavenger studies, and the effects of cholesterol and temperature allow a deeper understanding of the radically-driven oxidation of lipids. It was determined that hydroxyl radicals were generated and reacted with three fluorescent probes.

No description available.

Photocopy of typescript. / Digitized by Kansas Correctional Industries

We have studied the electrostatic and other interactions of the inorganic, hexavalent dye Ruthenium Red (RR) with phospholipid vesicles composed of phosphatidylcholine (PC) and phosphatidylserine (PS) or phosphatidylinositol (Pl) in various mixtures and concentrations. Experiments were based on spectrophotometric absorption measurements which compared RR concentrations in the presence and in the absence of liposomes at different dye concentrations. Multilamellar liposomes were obtained by handshaken preparations. Five freeze-and-thaw cycles of the lipid-RR suspension produced an ion equilibrium distribution at the membrane-water interface. Results are given in terms of the Gouy-Chapman-Stem adsorption theory with the linear partition coefficient and a newly introduced effective ion valency as parameters. Data on the time stability of RR solutions and their interaction with laboratory equipment are given. Furthermore, we characterize the freeze-and-thawing process and present an electron micrograph of liposomes. Two main results were found. First, the Gouy-Chapman-Stem theory correctly describes adsorption of a hexavalent ion to charged phospholipid vesicles if an effective valency is introduced. The effective valency accounts for the finite size of the ions and the repulsion between the ions. Values ranged between 2.9 and 4.1. Effective valencies decrease with increasing membrane surface charge density and are independent of the lipid concentration. Second, Ruthenium Red adsorbs to phospholipids and the adsorption is strongly related to the surface charge density of the membrane. Vesicles made from a mixture of PC and PI adsorb significantly less than vesicles made from a mixture of PC and PS. The second result is of special interest for molecular biology since biological membranes consist to a large extent of phospholipids. Sarcoplasmic reticulum (SR) membranes are discussed as an example. Liposomes (PC:PS 20: 1) with surface charge densities comparable to SR membranes adsorb a maximum of about 9±3nmol RR per mg lipid.

Graduation date: 1998

Vaccination is one of the major achievements of modern medicine. As a result of vaccination, diseases such as polio and measles have been controlled and small pox has been eliminated. However, despite these successes there are still many diseases of microbial origin that cause tremendous suffering because there are no vaccines or the vaccines available are inadequate. The development of DNA based vaccines and immunostimulatory CpG oligonucleotides (ODNs) as adjuvants offer new possibilities for developing new vaccines. The objectives of this research were to improve the delivery of polynucleotides and oligonucleotides to enhance their potency and to evaluate the feasibility of non-invasive methods for the delivery of vaccines through the skin in order to improve the safety and the ease of administration of human and veterinary vaccines. The results demonstrated that topical administration of plasmids in a lipid-based delivery system (biphasic lipid vesicles [Biphasix]) resulted in gene expression in the draining lymph nodes, as well as induction of antigen specific immune responses in mice. The use of electroporation significantly enhanced both gene expression and immune responses to DNA vaccines in pigs. Prior treatment with electroporation enhanced immune responses to both protein and DNA vaccines indicating that both gene expression and tissue damage are important mechanisms that electroporation uses to enhance immune responses. In addition, the formulation of CpG ODNs in biphasic lipid vesicles (BiphasixTM) called Vaccine-Targeting Adjuvant (VTA) enhanced immune response to protein antigens following systemic and mucosal administration.

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) have been shown to stimulate the innate immune system against a variety of bacterial, viral, and protozoan infections in a variety of vertebrate species. The objectives of this study were to investigate the immunostimulatory effect of CpG-ODN against Salmonella Typhimurium infection and the formulation and delivery of CpG-ODN by the in ovo route. Day-old broiler chicks or embryonated eggs (day 18th of incubation) received either 50 g of CpG-ODN, 50 g of non-CpG-ODN, or saline. At day four-post hatch, all birds were subcutaneously inoculated by Salmonella Typhimurium. Clinical signs, pathology, bacterial isolations from the air sacs, and mortality were observed for ten days following challenge. The survival rate of the birds that received CpG-ODN via in ovo or in vivo treatments was significantly higher than the control group. Salmonella Typhimurium level in the peripheral blood and pathology were significantly lower (p < 0.001) in CpG-ODN group compared to the control group. In order to investigate the effect of formulation of CpG-ODN, embryonated eggs (day 18th of incubation) were inoculated with either 50 g of CpG-ODN alone or CpG-ODN formulated with polyphosphazene, liposome, or Emulsigen®. Four days after administration of CpG-ODN formulations, the birds were challenged with E. coli by subcutaneous injection. Clinical signs, pathology, bacterial isolations from the air sacs, and mortality were observed for seven days following challenge. The birds that received either CpG-ODN or CpG-ODN formulated with polyphosphazene had significantly higher survival rates (30 and 60%) compared to the birds in groups receiving either non-CpG-ODN or saline. Bacterial loads in the air sacs were lower in groups treated with formulated CpG-ODN compared to the CpG-ODN alone or control groups. However, formulation of CpG-ODN with liposomes or Emulsigen® did not increase the immunoprotective effect against E. coli infection. We showed that treatment with CpG-ODN protects neonatal chickens against an intracellular bacterial infection and that co-treatment of CpG-ODN with polyphosphazene enhances the immunoprotective effect of CpG-ODN.