Quantitative measurements of oxidative stress in mouse skin induced by X-ray irradiation

To find efficient methods to evaluate oxidative stress in mouse skin caused by X-ray irradiation, several markers and methodologies were examined. Hairless mice were irradiated with 50 Gy X-rays and skin homogenates or skin strips were prepared. Lipid peroxidation was measured using the skin homogenate as the level of thiobarbituric acid reactive substances. The level of lipid peroxidation increased with time after irradiation and was twice that of the control at 78 h. ESR spectra of skin strips showed a clear signal for the ascorbyl radical, which increased with time after irradiation in a manner similar to that of lipid peroxidation. To measure levels of glutathione (GSH) and its oxidized forms (GSSG) simultaneously, two HPLC methods, sample derivatization with 1-fluoro-2,4-dinitrobenzene and detection with a UV detector (method A) and no derivatization and detection with an electrochemical detector (method B), were compared and the latter was found to be better. No significant change was observed within 24 h after irradiation in the levels of GSH and GSSG measured by method B. The GSH/GSSG ratio may be a less sensitive parameter for the evaluation of acute oxidative stress caused by X-ray irradiation in the skin. Monitoring the ascorbyl radical seems to be a good way to evaluate oxidative stress in skin in vivo.     

Asymmetric synthesis,structures, and chiroptical properties of helical cycloparaphenylenes

Planar chiral carbon nanorings and nanobelts (CNRs and CNBs), the sidewall segment molecules of chiral-type carbon nanotubes (CNTs), have attracted attention owing to their characteristic chiroptical properties. From the appropriate CNTs, axially or planar chiral CNRs and CNBs have been designed and synthesized, but multiply helical sidewall segments were almost unexplored due to the difficulty in simultaneous control of multiple chiralities. In this article, we have succeeded in the perfectly diastereo- and enantiocontrolled catalytic synthesis of a cycloparaphenylene with four helical and two planar chiralities showing good chiroptical responses as chiral organic molecules. The perfectly stereocontrolled multiply helical structure was confirmed by a single-crystal X-ray diffraction analysis. The experimental and theoretical studies established the importance of the highly symmetric multiply helical structure in the cylindrical axis in obtaining good chiroptical responses.

The perfectly diastereo- and enantiocontrolled catalytic synthesis of a cycloparaphenylene with four helical and two planar chiralities showing good chiroptical responses was achieved by the rhodium-catalyzed alkyne cyclotrimerization.     

The absolute configurations of halogenated chamigrene derivatives from the marine alga, laurencia glandulifera kützing

The absolute configurations of halogenated chamigrene derivatives, isolated from L. glandulifera Kützing, 10-bromo-3,4-epoxy-α-chamigrene (1), glanduliferol (2), 10-bromo-α-chamigren-4-one (3), 4,10-dibromo-3-chloro-α-chamigrene (4) and 10-bromo-α-chamigrene (5), have been determined by X-ray diffraction analysis of 1 and subsequently, by relating 2, 3, 4 and 5 to 1 with the chemical methods. In addition, the absolute configuration of (?)-α-chamigrene (6), yielded on the process of the above chemical transformation, has been elucidated.     

Combination of an aromatic core and aromatic side chains which constitutes discotic liquid crystal and organogel supramolecular assemblies

This paper reports unique and unusual formations of columnar liquid crystals and organogels by self-assembling discotic molecules, which are composed of an aromatic hexaazatriphenylene (HAT) core and six flexible aromatic side chains. In HAT derivatives 3a, with 4'-(N,N-diphenylamino)biphenyl-4-yl chains, 3b, with 4'-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl chains, and 3c, with 4'-phenoxybiphenyl-4-yl chains, the two-dimensional hexagonal packings can be created by their self-assembling in the liquid crystalline phase, which were characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. In certain solvents, HAT molecules 3a-c can form the viscoelastic fluid organogels, in which one-dimensional aggregates composed of the HAT molecules are self-assembled and entangled into three-dimensional network structures. The organogel structures were analyzed by scanning electron microscopy observation, (1)H NMR, UV-vis, and circular dichroism spectroscopy. In contrast to 3a-c, none of the liquid crystalline and organogel phases could be formed from 3d and 3e with short aromatic side chains including a phenylene spacer, and 3f (except a few specific solutions) and 3g without terminal diarylamino and phenoxy groups. In 3a-c, the aromatic side chains with terminal flexible groups make up soft regions that cooperatively stabilize the liquid crystalline and organogel supramolecular structures together with the hard regions of the hexaazatriphenylene core.     

Oxidation of (7,16-diethyl-5,6,7,8,9,14,15,16,17,18-decahydrodibenzo[b,i][1,4,8,11]tetraazacyclotetradecine)nickel(II) complexes

The oxidation reaction of two isomers of (7,16-diethyl-5,6,7,8,9,14,15,16,17,18-decahydrodibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine)nickel(II) diperchlorate and/or dichloride (NiL¹X₂ (X = ClO₄, Cl)) in methanol in air under atmospheric pressure leads to the production of (7,16-diethyl-5,6,7,8,9-pentahydrodibenzo-[b,i][1,4,8,11]tetraazacyclotetradecinato)nickel(II) complexes (NiL²X). Proton and ¹³C nmr spectra suggest that NiL²X is formed by partial oxidation from a macrocyclic skeleton of NiL¹X₂. The dehydrogenation of NiL¹X₂ does not occur at symmetric positions such as d- and k-positions of the macrocyclic skeleton but at unsymmetrical positions such as d- and f-positions. Treatment of NiL¹X₂ and/or NiL²X in a methanol solution with an excess of bases in air gives (7,16-diethyldibenzo[b,t][1,4,8,11]tetraazacyclotetradecinato)nickel(II) (NiL³).     

New RIKEN-RAL pulsed µCF facility and X-ray studies on DT-µCF

In November 1994, the construction of a new superconducting muon channel of the RIKEN-RAL muon facility at ISIS of Rutherford Appleton Laboratory was completed. Subsequently, important features, such as the highest instantaneous intensity with a single-pulse structure and a high purity have been confirmed. Along with the installation of advanced µCF experimental equipment, including a high-purity D-T mixture target system with an in situ³He removal capability and a 4 T confinement magnet, an advanced µCF experiment, e.g. a precise X-ray measurement on µ- sticking in dtµ-µCF will be realized. An account of the commissioning experiments, a plan for the earliest phase of the µCF experiment and possible future directions are reported.     

New Combinatorial Bounds for Authentication Codes and Key Predistribution Schemes

This paper provides new combinatorial bounds and characterizations of authentication codes (A-codes) and key predistribution schemes (KPS). We first prove a new lower bound on the number of keys in an A-code without secrecy, which can be thought of as a generalization of the classical Rao bound for orthogonal arrays. We also prove a new lower bound on the number of keys in a general A-code, which is based on the Petrenjuk, Ray-Chaudhuri and Wilson bound for t-designs. We also present new lower bounds on the size of keys and the amount of users' secret information in KPS, the latter of which is accomplished by showing that a certain A-code is hiding inside any KPS.     

Trapping of fatty acid allyl radicals generated in lipoxygenase reactions in biological fluids by nitroxyl radical

Nitroxyl radicals can trap fatty acid allyl radicals on ferric‐lipoxygenases at lower oxygen content, which are an intermediate in the lipoxygenase reaction. In the present study, we examined whether nitroxyl radical‐trapping of fatty acid allyl radicals on the enzyme proceeds in biological fluids with abundant antioxidants. The fatty acid allyl radical–nitroxyl radical adducts were quantified by HPLC with electrochemical detection (HPLC‐ECD); the adducts in eluate degraded into nitroxyl radical by passing through heating coil at 100°C, and then nitroxyl radical was detected by electrochemical detector. Soybean 15‐lipoxygenase and nitroxyl radical (3‐carbamoyl‐2,2,5,5‐tetramethyl‐3‐pyrroline‐N‐oxyl, CmΔP) were mixed with rat serum prepared from fresh venous blood, and the solution was stood at 37°C for 1 h. One volume of the solution was mixed with 5 vols of cold acetonitrile. After centrifugation, the supernatant was subjected to HPLC‐ECD. Arachidonate allyl radical–CmΔP adducts as well as linoleate allyl radical–CmΔP adducts were detected in the solution, and the content of these adducts remarkably increased in the presence of phospholipase A₂. It is proved for the first time that nitroxyl radical traps fatty acid allyl radicals generated in the lipoxygenase reaction in biological fluid without competition from endogenous antioxidants. Copyright © 2010 John Wiley & Sons, Ltd.