Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 113-118).

Stroke is a devastating and debilitating condition resulting from a blockage or hemorrhage in the vasculature of the brain. Despite extensive research, the etiology and pathophysiology of the disease at the level of the cell membrane are poorly understood, and effective treatment has been elusive. Though much research has shown marked increases in lipid metabolism following stroke, the impact of these changes have often been overlooked given the technical challenges associated with identifying regionally specific changes in degenerating tissue. The advent of lipidomics – a systems biology approach to the large-scale profiling of individual lipid species in tissues – has renewed interest in understanding the role of membrane lipids and their metabolites in the cell and in ischemic injury. In this thesis, I have used an unbiased LC-ESI-MS-based lipidomic approach to profile the small molecular weight glycerophosphocholine second messenger lipidome in anterior and posterior regions of cortex and striatum in the forebrain of wild-type and platelet activating factor receptor (PAFR) null-mutant mice before and after middle cerebral artery occlusion (MCAO). From these profiles, I have outlined the potential use of lipid second messenger distribution as topographic landmarks to identify functional subdomains within neural tissue. Further, I have demonstrated that ischemia does not simply disrupt lipid second messenger metabolism globally but produces regionally specific changes in discrete species and that these changes are altered by the loss of lipid regulatory effectors (i.e., PAFR null mutation). Based on the lipid species identified in this profile of healthy and ischemic tissue, I proposed that tight regulation of PC(O-22:6/2:0) homeostasis by PAFR-expressing microglia is ii required for proper dopaminergic signaling in prefrontal cortex. Finally, I have outlined a model whereby increased PAF synthesis following ischemia contributes the inflammatory response by promoting blood-brain barrier permeability, microglial activation and immune cell infiltration in a PAFR-dependent manner.

Universiẗat, Diss.--Heidelberg, 1997.

Zugl.: Berlin ; Freie Univ., Diss., 2008

Thesis (M. Med. Sc.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 53-63).

Thesis (Ph. D.)--University of Virginia, 1999. / Spine title: X-ray structure of PAF acetylhydrolase. Includes bibliographical references (p. 161-175). Also available online through Digital Dissertations.

Thesis (M.Med.Sc.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 53-63). Also available in print.

Zugl.: Berlin ; Freie Universiẗat, Diss., 2008.

Stroke is a devastating and debilitating condition resulting from a blockage or hemorrhage in the vasculature of the brain. Despite extensive research, the etiology and pathophysiology of the disease at the level of the cell membrane are poorly understood, and effective treatment has been elusive. Though much research has shown marked increases in lipid metabolism following stroke, the impact of these changes have often been overlooked given the technical challenges associated with identifying regionally specific changes in degenerating tissue. The advent of lipidomics – a systems biology approach to the large-scale profiling of individual lipid species in tissues – has renewed interest in understanding the role of membrane lipids and their metabolites in the cell and in ischemic injury. In this thesis, I have used an unbiased LC-ESI-MS-based lipidomic approach to profile the small molecular weight glycerophosphocholine second messenger lipidome in anterior and posterior regions of cortex and striatum in the forebrain of wild-type and platelet activating factor receptor (PAFR) null-mutant mice before and after middle cerebral artery occlusion (MCAO). From these profiles, I have outlined the potential use of lipid second messenger distribution as topographic landmarks to identify functional subdomains within neural tissue. Further, I have demonstrated that ischemia does not simply disrupt lipid second messenger metabolism globally but produces regionally specific changes in discrete species and that these changes are altered by the loss of lipid regulatory effectors (i.e., PAFR null mutation). Based on the lipid species identified in this profile of healthy and ischemic tissue, I proposed that tight regulation of PC(O-22:6/2:0) homeostasis by PAFR-expressing microglia is ii required for proper dopaminergic signaling in prefrontal cortex. Finally, I have outlined a model whereby increased PAF synthesis following ischemia contributes the inflammatory response by promoting blood-brain barrier permeability, microglial activation and immune cell infiltration in a PAFR-dependent manner.

Within this thesis are described synthetic approaches towards the phomactins which are novel platelet activating factor antagonists. The synthesis of known alcohol 162 is described, the two key intermediates being aldehyde 160 and vinyl iodide 161. The key step of the synthesis of aldehyde 160 is a [2,3]-Wittig-Still rearrangement of stannane 159 which introduces the hindered C1-C2 bond present in the phomactins. The vinyl iodide 161 is made in four steps from 4-pentyn-1-ol. Addition of the vinyl ytterbium species derived from the vinyl iodide to aldehyde 160 gave secondary alcohol 162. Subsequent transformations furnished the bisprotected macrocyclic sulfone 174 in four steps from alcohol 162 to give the C2 SEM protected macrocycle. Elaboration of the macrocycle to ketoaldehyde 206 was made possible by the TPAP oxidation/rearrangement reaction. Reduction with DIBAL-Hgave diol 175. Attempts at removing the sulfone appendage proved difficult so the diol was protected as the bis-acetate to attempt a selective epoxidation of the D3,4 olefin in the presence of the D1,15 olefin. Although this looked promising with the formation of the mono-epoxide 213, the inefficiency of removing the SEM group at C2 prior to the epoxidation meant the route was not viable. Removing both protecting groups from macrocycle 174 was possible with refluxing TBAF and after incorporating the epoxide of the D3,4 olefin, the macrocycle was elaborated to the benzyl ether 217. Applying the TPAP oxidation/DIBAL-H reduction sequence furnished advanced intermediate 179 which has the full carbon skeleton found in phomactin A and also had oxygen functionality at all the required positions.