Development and validation of a hydrophilic interaction chromatography–tandem mass spectrometry for quantification of nicotine and its metabolites in human maternal and cord sera

A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd.     

Sub-micrometer patterns of molecular photo-switches using laser induced molecular implantation techniques (LIMIT)

Using laser induced molecular implantation techniques (LIMIT) in thin polymer films highly space selective patterning of photochromic molecules has been created of 800 nm dimensions. In this way diffraction gratings have been fabricated which operate as photo-switching devices. These transient gratings are permanent molecular implants in a polymer films that can be UV-irradiation activated or thermally deactivated. No further grating writing is required for this transient switching effect once the permanent implantation has been made.     

After effects of ec decay of57Co in Mg(1-x)FexSO4.7H2O mixed crystals

After effects due to the EC decay of⁵⁷Co in the mixed crystals (Mg,Fe)SO₄·7H₂O were studied. When the Fe concentrationx=Fe/(Fe+Mg) is 0.4≈0.5, the surroundings of⁵⁷Fe have the characteristics of orthorhombic MgSO₄·7H₂O although the crystal structure is monoclinic. This fact suggests a possibility of transient release of the Jahn-Teller transformation.     

Universal reconnection of non-Abelian cosmic strings

We show that local and semilocal strings in Abelian and non-Abelian gauge theories with critical couplings always reconnect classically in collision, by using moduli space approximation. The moduli matrix formalism explicitly identifies a well-defined set of the vortex moduli parameters. Our analysis of generic geodesic motion in terms of those shows right-angle scattering in head-on collision of two vortices, which is known to give the reconnection of the strings.     

Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts

Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product.     

Asymmetric Total Synthesis of ent‐Pyripyropene A

An asymmetric total synthesis of ent‐pyripyropene A was achieved by a convergent synthetic route. We used our originally developed Ti^III‐catalyzed radical cyclization to construct an AB‐ring portion that consisted of a trans‐decalin skeleton with five contiguous stereogenic centers. The coupling between the AB‐ring and the DE‐ring portions, and a subsequent C‐ring cyclization, led to the total synthesis of ent‐pyripyropene A. An evaluation of the insecticidal activity of ent‐pyripyropene A against two aphid species revealed that ent‐pyripyropene A was 35–175 times less active than naturally occurring pyripyropene A. This result indicated that the biological target of pyripyropene A recognizes the absolute configuration of pyripyropene A.     

Total synthesis and structure revision of deacetylravidomycin M

Total synthesis of the unnatural enantiomer of deacetylravidomycin M was accomplished. The key steps include, (1) aryl C-glycosidation of the azido-bearing fucosyl acetate 2 by using catalytic Sc(OTf)₃, (2) the [2+2] cycloaddition reaction of alkoxybenzyne bearing an azido sugar to ketene silyl acetal, and (3) the ring expansion reaction of alkoxybenzocyclobutenone. The synthesis revealed that the natural product is not the proposed amine, but the corresponding N-oxide.     

Total synthesis of citridone A

The first total synthesis of citridone A has been achieved through regioselective intramolecular iodocyclization and regio- and stereoselective Pd(0)-catalyzed coupling as key reactions.     

Abnormal phospholipids distribution in the prefrontal cortex from a patient with schizophrenia revealed by matrix-assisted laser desorption/ionization imaging mass spectrometry

Schizophrenia is one of the major psychiatric disorders, and lipids have focused on the important roles in this disorder. In fact, lipids related to various functions in the brain. Previous studies have indicated that phospholipids, particularly ones containing polyunsaturated fatty acyl residues, are deficient in postmortem brains from patients with schizophrenia. However, due to the difficulties in handling human postmortem brains, particularly the large size and complex structures of the human brain, there is little agreement regarding the qualitative and quantitative abnormalities of phospholipids in brains from patients with schizophrenia, particularly if corresponding brain regions are not used. In this study, to overcome these problems, we employed matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS), enabling direct microregion analysis of phospholipids in the postmortem brain of a patient with schizophrenia via brain sections prepared on glass slides. With integration of traditional histochemical examination, we could analyze regions of interest in the brain at the micrometric level. We found abnormal phospholipid distributions within internal brain structures, namely, the frontal cortex and occipital cortex. IMS revealed abnormal distributions of phosphatidylcholine molecular species particularly in the cortical layer of frontal cortex region. In addition, the combined use of liquid chromatography/electrospray ionization tandem mass spectrometry strengthened the capability for identification of numerous lipid molecular species. Our results are expected to further elucidate various metabolic processes in the neural system.