Early administration of broad-spectrum antibiotics is the first goal in sepsis treatment. Besides from bacteriostatic/bactericidal effects, some antibiotics may also modify the host´s response to infection. The novel antibiotic tigecycline may exert such properties; however, this property has not been evaluated in large-animal trials. We compared tigecycline with doxycycline and placebo in relation to anti-inflammatory, circulatory and organ dysfunction effects in a sterile pig model of sepsis. Doxycycline, but not tigecycline, reduced the inflammatory response as manifested by tumor necrosis factor alpha levels in plasma. Tigecycline, however, had a stabilizing effect on the circulation not exerted by doxycycline or placebo. To achieve rapid restoration of the circulating blood volume - another major goal in sepsis treatment - fluid bolus administration of is some-times practiced. In addition to crystalloids, albumin-containing solutions are suggested. Yet, some animal-experimental data suggests that rapid bolus administration of albumin reduces albumin’s plasma-expanding effect. We compared a rapid intravenous bolus of radiolabeled albumin with a slow infusion in a sterile pig model of sepsis. Rapid bolus of administration did not reduce plasma levels of albumin following administration and did not increase the amount of albumin that left the circulation. Inadequate oxygen delivery (DO2) by the circulation to the tissues may cause increased plasma lactate, which is the most striking effect of sepsis on the metabolism. However, experimental data and clinical trials refute this link, instead, suggesting other mechanisms, including impaired oxygen extraction, mitochondrial dysfunction and accelerated aerobic glycolysis. We investigated the impact of DO2, oxygen consumption (VO2), hemodynamic parameters and inflammatory response on plasma lactate and organ dysfunction in two experimental sepsis models. In the most severe cases of shock, with DO2, there was an increase in plasma lactate, but without a decrease in VO2, invalidating the assumption that the increase in lactate is due to anaerobic metabolism. To identify critical steps in the sepsis-induced increase in lactate, we inhibited the major energy-producing step in the electron transport chain (ETC). The combination of sepsis and ETC inhibition led to a cellular energy crisis. This finding suggests that early sepsis induces a partial mitochondrial dysfunction.

Dans le cadre de la synthèse totale de la leucophyllidine, un alcaloïde bis-indolique, des réactions de carbo- et sulfonyl-cyanation radicalaires sans étain ont été développées. Les cyanures de sulfonyle RSO2CN, préparés à partir des thiocyanates correspondant par une nouvelle méthode d’oxydation, sont utilisés comme pièges radicalaires. Ces réactifs fragmentent en présence d’initiateur thermique (carbo-cyanation) ou par le biais de la catalyse photoredox (sulfonyl-cyanation). Dans ce dernier cas, une étude mécanistique approfondie sur le cycle photo-catalytique a été accomplie. Ces méthodologies introduisent un nitrile sur une chaîne carbonée insaturée par voie radicalaire, fournissant des intermédiaires avancés pour la synthèse totale d’alcaloïdes. Pour la synthèse asymétrique de l’eucophylline, le fragment sud de la leucophyllidine, la sulfonyl-cyanation de cyclobutènes énantioenrichis a montré d’excellentes diastéréosélectivités. Différentes stratégies d’ouverture de cycle ont ensuite été examinées. / During our efforts directed toward the total synthesis of leucophyllidine, a bis-indole alkaloid, the tin-free radical carbo-cyanation and sulfonyl-cyanation of olefins were developed. The sulfonyl cyanides, acting as radical traps, were synthesized through a new oxidation of the corresponding thiocyanate. These reagents were found to fragment under thermal initiation (carbo-cyanation) or using the photoredox catalysis (sulfonyl-cyanation). A thorough mechanistic study was accomplished for the sulfonyl-cyanation. These methodologies install a nitrile onto an olefin backbone, furnishing advanced intermediates for the total synthesis of alkaloids. For the asymmetric synthesis of eucophylline, the south fragment of leucophyllidine, the sulfonyl-cyanation of optically pure cyclobutenes showed excellent diastereoselectivities. Different ring-opening reactions of the corresponding cyclobutane were then examined.

Thesis (M.S.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).