Structure and enantioselective synthesis of polyamine toxin MG30 from the venom of the spider Macrothele gigas

A novel polyamine toxin, named MG30, was isolated from the venom of the spider, Macrothele gigas, and its structure was elucidated by two-dimensional NMR and mass analysis. In addition, the enantioselective synthesis of MG30 was achieved to assign its absolute stereochemistry.     

Major-to-ultratrace elements in bone-marrow fluid as determined by ICP-AES and ICP-MS.

The major-to-ultratrace elements in human bone-marrow fluid were determined by ICP-AES (inductively coupled plasma atomic emission spectrometry), and ICP-MS (inductively coupled plasma mass spectrometry). The bone-marrow fluid sample was centrifuged prior to acid digestion to exclude the bone piece from bone marrow, and then digested with nitric acid. As a result, 20 elements could be determined over the concentration range from 1610 microg g(-1) for Na to 0.00043 microg g(-1) for W. It was found that Fe, Zn and Sb were enriched by ca. 264-, 7- and 15-fold, respectively, in bone-marrow fluid, compared to those in human blood serum. Alkali metals (K, Rb, Cs), except for Na, were also significantly enriched in bone-marrow fluid. Furthermore, the concentrations of various elements, such as Fe, P, Al, Zn, Cu, Se, Zr, Sn, Ag and W, were significantly higher than those in open seawater.     

On the field of definition for modularity of CM elliptic curves

The purpose of this paper is to decide the conditions under which a CM elliptic curve is modular over its field of definition.     

Determination of rare earth elements in human blood serum by inductively coupled plasma mass spectrometry after chelating resin preconcentration

The determination of all rare earth elements (REEs) in human blood serum by inductively coupled plasma mass spectrometry (ICP-MS) was performed with the aid of chelating resin (Chelex 100) preconcentration after acid digestion with HNO3 and HClO4. When chelating resin preconcentration was carried out at room temperature, the recoveries of heavy REEs were lower than those of light REEs because of their stable complex formation with residual organic compounds remaining in the digested serum solution. These problems were overcome by heating the solution at 80 degrees C during the chelating resin preconcentration process. As a result, the recoveries for all REEs were improved to 92-102% in the case of a concentration factor of 4, where the analytical detection limits for REEs were below 0.2 x 10(-12) g ml-1. Consequently, all REEs in individual human blood sera collected from five healthy volunteers could be determined by ICP-MS with good precision. The concentrations of REEs in human blood serum were extremely low, in the range from ca. 1 x 10(-12) g ml-1 of Eu to ca. 230 x 10(-12) g ml-1 of Ce.     

Ab initio calculations of isomerization reaction of diphosphene 1-sulfide to thiadiphosphirane

Ab initio Calculations of the isomerization reaction of diphosphene 1-sulfide (2′) to thiadiphosphirane (3′) suggest that the energy barrier of the reaction in the ground state is 25 kcal/mol and that 2′ lies 21 kcal/mol above 3′, while the calculations show that there exists one local minimum on the lowest triplet energy surface.     

A new strategy for construction of eight-membered carbocycles by Brook rearrangement mediated [6 + 2] annulation

[reaction: see text] A newly developed strategy for construction of eight-membered carbocycles via [6 + 2] annulation that involves the combination of beta-alkenoyl acylsilanes and a vinyllithium derivative is described. A unique feature of this annulative approach is that it enables in one operation and a stereoselective manner construction of eight-membered ring systems containing useful functionalities for further synthetic elaboration from readily available six- and two-carbon components.     

Drug-plasma protein binding assay by electrokinetic chromatography-frontal analysis

We developed a rapid, microscale and reliable analytical method for binding of drugs to plasma proteins using capillary electrophoresis (CE) with ionic cyclodextrins (CD) combined with frontal analysis. These CDs were used as pseudostationary phases of electrokinetic chromatography (EKC). The CD-modified EKC (CDEKC) approach allowed us to separate anionic drugs from plasma proteins, whereas CZE could not separate these drugs from plasma proteins because they had a similar mobility like plasma proteins. CDs uniquely interact with these drugs but not with plasma proteins. Therefore, CDEKC could be coupled with frontal analysis to measure the binding of anionic drugs to plasma proteins. The binding values obtained by CDEKC were highly consistent with those determined by the ultrafiltration method. Our CDEKC approach should expand the applicability of CE to protein binding analysis.