The thrombotic potential of oral pathogens

In recent times the concept of infectious agents playing a role in cardiovascular disease has attracted much attention. Chronic oral disease such as periodontitis, provides a plausible route for entry of bacteria to the circulation. Upon entry to the circulation, the oral bacteria interact with platelets. It has been proposed that their ability to induce platelet aggregation and support platelet adhesion is a critical step in the pathogenesis of the infection process. Many published studies have demonstrated multiple mechanisms through which oral bacteria are able to bind to and activate platelets. This paper will review the various mechanisms oral bacteria use to interact with platelets

Identification of Neural Outgrowth Genes using Genome-Wide RNAi

While genetic screens have identified many genes essential for neurite outgrowth, they have been limited in their ability to identify neural genes that also have earlier critical roles in the gastrula, or neural genes for which maternally contributed RNA compensates for gene mutations in the zygote. To address this, we developed methods to screen the Drosophila genome using RNA-interference (RNAi) on primary neural cells and present the results of the first full-genome RNAi screen in neurons. We used live-cell imaging and quantitative image analysis to characterize the morphological phenotypes of fluorescently labelled primary neurons and glia in response to RNAi-mediated gene knockdown. From the full genome screen, we focused our analysis on 104 evolutionarily conserved genes that when downregulated by RNAi, have morphological defects such as reduced axon extension, excessive branching, loss of fasciculation, and blebbing. To assist in the phenotypic analysis of the large data sets, we generated image analysis algorithms that could assess the statistical significance of the mutant phenotypes. The algorithms were essential for the analysis of the thousands of images generated by the screening process and will become a valuable tool for future genome-wide screens in primary neurons. Our analysis revealed unexpected, essential roles in neurite outgrowth for genes representing a wide range of functional categories including signalling molecules, enzymes, channels, receptors, and cytoskeletal proteins. We also found that genes known to be involved in protein and vesicle trafficking showed similar RNAi phenotypes. We confirmed phenotypes of the protein trafficking genes Sec61alpha and Ran GTPase using Drosophila embryo and mouse embryonic cerebral cortical neurons, respectively. Collectively, our results showed that RNAi phenotypes in primary neural culture can parallel in vivo phenotypes, and the screening technique can be used to identify many new genes that have important functions in the nervous system

Hippocampal pyramidal cells: the reemergence of cortical lamination

The increasing resolution of tract-tracing studies has led to the definition of segments along the transverse axis of the hippocampal pyramidal cell layer, which may represent functionally defined elements. This review will summarize evidence for a morphological and functional differentiation of pyramidal cells along the radial (deep to superficial) axis of the cell layer. In many species, deep and superficial sublayers can be identified histologically throughout large parts of the septotemporal extent of the hippocampus. Neurons in these sublayers are generated during different periods of development. During development, deep and superficial cells express genes (Sox5, SatB2) that also specify the phenotypes of superficial and deep cells in the neocortex. Deep and superficial cells differ neurochemically (e.g. calbindin and zinc) and in their adult gene expression patterns. These markers also distinguish sublayers in the septal hippocampus, where they are not readily apparent histologically in rat or mouse. Deep and superficial pyramidal cells differ in septal, striatal, and neocortical efferent connections. Distributions of deep and superficial pyramidal cell dendrites and studies in reeler or sparsely GFP-expressing mice indicate that this also applies to afferent pathways. Histological, neurochemical, and connective differences between deep and superficial neurons may correlate with (patho-) physiological phenomena specific to pyramidal cells at different radial locations. We feel that an appreciation of radial subdivisions in the pyramidal cell layer reminiscent of lamination in other cortical areas may be critical in the interpretation of studies of hippocampal anatomy and function

Role of cytoskeletal abnormalities in the neuropathology and pathophysiology of type I lissencephaly

Type I lissencephaly or agyria-pachygyria is a rare developmental disorder which results from a defect of neuronal migration. It is characterized by the absence of gyri and a thickening of the cerebral cortex and can be associated with other brain and visceral anomalies. Since the discovery of the first genetic cause (deletion of chromosome 17p13.3), six additional genes have been found to be responsible for agyria–pachygyria. In this review, we summarize the current knowledge concerning these genetic disorders including clinical, neuropathological and molecular results. Genetic alterations of LIS1, DCX, ARX, TUBA1A, VLDLR, RELN and more recently WDR62 genes cause migrational abnormalities along with more complex and subtle anomalies affecting cell proliferation and differentiation, i.e., neurite outgrowth, axonal pathfinding, axonal transport, connectivity and even myelination. The number and heterogeneity of clinical, neuropathological and radiological defects suggest that type I lissencephaly now includes several forms of cerebral malformations. In vitro experiments and mutant animal studies, along with neuropathological abnormalities in humans are of invaluable interest for the understanding of pathophysiological mechanisms, highlighting the central role of cytoskeletal dynamics required for a proper achievement of cell proliferation, neuronal migration and differentiation

Oxidation of Phenolic and Heterocyclic Amine Systems with Diphenylselenium Bis(Trifluoroacetate).

As part of an effort to design mild and selective two-electron oxidants for phenolic compounds, the new organoselenium(IV) reagent, diphenylselenium bis(trifluoroacetate) 1, was developed. Two basic oxidations of phenolic compounds with 1 were studied: oxidative aryl coupling and hydroxylation to form p-benzoquinone systems. The oxidation of secondary and tertiary amines was also investigated. The two-electron oxidation of the 4-hydroxyphenyl moiety of some diarylalkanes resulted in electrophilic aromatic substitution of the second, electron-rich aryl ring to provide, overall, intramolecular oxidative phenolic coupling. Oxidation of 1-(3,4-methylenedioxyphenyl)-3-(4-hydroxyphenyl) propane and 1-(3-hydroxy-4-methoxyphenyl)-3-(4-hydroxyphenyl) propane gave the corresponding spirodienones in 76% and 65% yield, respectively. Ethyl 2-carboethoxy-2-(3,5-dimethoxy-4-hydroxybenzyl)-4-(3,4-methylenedioxyphenyl) butyrate was oxidized to a p-quinone methide intermediate; aryl-benzyl coupling gave 1-(3',5'-dimethoxy-4'-hydroxyphenyl)-2,2-dicarboethoxy-6,7-methylenedioxytetralin in 75% yield. The addition of phenols, unsubstituted in the para position, to an excess of the reagent 1 and lithium trifluoroacetate gave yields of 60-82% of the p-benzoquinone. The skin allergen primin, 2-methoxy-6-pentyl-p-benzoquinone, was synthesized with this method in 80% yield from 2-methoxy-6-pentylphenol. Similarly, 2,6-dimethylaniline was oxidized to 2,6-dimethyl-p-benzoquinone in 72% yield. Oxidation of the secondary and tertiary amine-nitrogen of 1,2,3,4-tetrahydroisoquinoline compounds, as well as 1,2,3,4-tetrahydro-(beta)-carboline, with the reagent 1 gave the corresponding 3,4-dihydro-compounds in greater than 80% yield. A 1-benzyl-1,2,3,4-tetrahydroisoquinoline compound and the (beta)-carboline could be oxidized further to the fully aromatic compounds in 75% and 61% yield, respectively. Oxidative decarboxylation of 3-carboxy-1,2,3,4-tetrahydroisoquinoline with the reagent 1 gave isoquinoline in 26% yield; 3-carbomethoxyisoquinoline was isolated as well in 40% yield after addition of diazomethane. The methyl ester of the acid and an analogous (beta)-carboline were dehydrogenated cleanly to the fully aromatic 3-carbomethoxy-compounds in 100% and 71% yield, respectively. The reagent 1 offers a new method for the mild and selective two-electron oxidation of phenols and heterocyclic amine systems. It can be used in a stoichiometric fashion and is an improvement over many existing methods.Ph.D.Organic chemistryUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159032/1/8224991.pd