Total synthesis of (+/-) maculalactone A, maculalactone B and maculalactone C and the determination of the absolute configuration of natural (+) maculalactone A by asymmetric synthesis

Maculalactones A, B and C from the marine cyanobacterium Kyrtuthrix maculans are amongst the only compounds based on the tribenzylbutyrolactone skeleton known in nature and (+) maculalactone A from the natural source possesses significant biological activity against various marine herbivores and marine settlers. We now report a concise synthesis of racemic maculalactone A in five steps from inexpensive starting materials. Maculalactones B and C were synthesized by a minor modification to this procedure, and the synthetic design also permitted an asymmetric synthesis of maculalactone A to be achieved in around 85% ee. The (+) and (-) enantiomers of maculalactone A were assigned, respectively, to the S and R configurations on the basis of the chiral selectivity expected for catecholborane reduction of an unsymmetrical ketone in the presence of Corey's oxazoborolidine catalyst. Surprisingly, it appeared that natural (+) maculalactone A was biosynthesized in K. maculans in a partially racemic form, comprising ca. 90-95% of the (S) enantiomer and 5-10% of its (R) enantiomer. Coincidentally therefore, the percentage enantiomeric excess of the product obtained from asymmetric synthesis almost exactly matched that found in nature. (C) 2004 Elsevier Ltd. All rights reserved.

Measurement of the Lifetime of the B-c(+/-) Meson in the Semileptonic Decay Channel

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Measurement of gamma + b + X and gamma + c + X Production Cross Sections in pp > Collisions at s=1.96 TeV

First measurements of the differential cross sections d(3)sigma/(dp(T)(gamma)dy(gamma)dy(jet)) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30 < p(T)(gamma)< 150 GeV, photon rapidities |y(gamma)|< 1.0, jet rapidities |y(jet)|< 0.8, and jet transverse momenta p(T)(jet)> 15 GeV. The results are based on an integrated luminosity of 1 fb(-1) in pp collisions at s=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.

Influence of N-methyl-D-aspartate receptors on ouabain activation of nuclear factor-kappa B in the rat hippocampus

It has been shown that ouabain (OUA) can activate the Na,K-ATPase complex and mediate intracellular signaling in the central nervous system (CNS). Inflammatory stimulus increases glutamatergic transmission, especially at N-methyl-D-aspartate (NMDA) receptors, which are usually coupled to the activation of nitric oxide synthase (NOS). Nuclear factor-kappa B (NF-kappa B) activation modulates the expression of genes involved in development, plasticity, and inflammation. The present work investigated the effects of OUA on NF-kappa B binding activity in rat hippocampus and the influence of this OUA-Na,K-ATPase signaling cascade in NMDA-mediated NF-kappa B activation. The findings presented here are the first report indicating that intrahippocampal administration of OUA, in a concentration that did not alter Na,K-ATPase or NOS activity, induced an activation of NF-kappa B, leading to increases in brain-derived neurotrophic factor (Bdnf), inducible NOS (iNos), tumor necrosis factor-alpha (Tnf-alpha), and B-cell leukemia/lymphoma 2 (Bcl2) mRNA levels. This response was not linked to any significant signs of neurodegeneration as showed via Fluoro-Jade B and Nissl stain. Intrahippocampal administration of NMDA induced NF alpha B activation and increased NOS and alpha 2/3-Na,K-ATPase activities. NMDA treatment further increased OUA-induced NF-kappa B activation, which was partially blocked by MK-801, an antagonist of NMDA receptor. These results suggest that OUA-induced NF-kappa B activation is at least in part dependent on Na,K-ATPase modulatory action of NMDA receptor in hippocampus. The interaction of these signaling pathways could be associated with biological mechanisms that may underlie the basal homeostatic state linked to the inflammatory signaling cascade in the brain. (c) 2011 Wiley Periodicals, Inc.

Crash protection systems for handicapped school and transit bus occupants. Volume III: appendices A, B, C and D. Interim report.

National Highway Traffic Safety Administration, Washington, D.C.

Asiatic Art, VII century B.C.-XVIII century A.D., including sculpture in bronze & stone, ceramics, miniatures and textiles.

Exhibition and sale at the American Art Galleries, New York.

Geology and ore-deposits of Rossland, B.C. /

Vita.

East and west through fifteen centuries; being a general history from B.C. 44 to A.D. 1453,

No more published.

A B C de l'apiculture; encyclopédie de tout ce qui a rapport à l'abeille, miel, ruches, instruments, plantes mellifères, etc., résultats d'observations et d'expériences de milliers d'apiculteurs, contrôlées ensuite par un travail pratique dans nos propres ruchers.

p. 518-524 advertising.

The Roman empire : B. C. 29-A. D. 476 /

Includes index.

Athenian letters: or, The epistolary correspondence of an agent of the king of Persia, residing at Athens during the Peloponnesian war. A new edition; to which is prefixed a geographical index. In two volumes. Illustrated with engravings, and a map of ancient Greece ...

The work of a group of English writers each letter being signed by an initial indicating the author, as follows. P.-Philip Yorke; C.-Charles Yorke; R.-G.H. Rooke; G.-John Green; W.-Daniel Wray; H.-Henry Heaton; E.-Wm. Heberden; O.-Henry Coventry; L.-John Lawry; T.-Catherine Talbot; B.-Thomas Birch; S.-Samuel Salter. The work was edited by Thomas Birch, the brothers Yorke having the largest share in the composition of the letters.

Report of the d'Hauteville case: The commonwealth of Pennsylvania, at the suggestion of Paul Daniel Gonsalve Grand d'Hauteville, versus David Sears, Miriam C. Sears, and Ellen Sears Grand d'Hauteville. Habeas corpus for the custody of an infant child.

In the Court of general sessions for the city and county of Philadelphia. Habeas corpus for the custody of Frederick Sears Grand d'Hauteville.

Stories from English history from B. C. 55 to A. D. 1901;

Mode of access: Internet.