Determination of histamine, 1-methylhistamine and N-methylhistamine by capillary electrophoresis with micelles

Urinary histamine and Ngamma-methylhistamine (1-MH), a histamine metabolite, are highly correlated with histamine in plasma. Therefore, allergic reactions can be examined by determination of histamine and 1-MH in urine. We separated histamine, 1-MH and Nalpha-methylhistamine (N-MH) by capillary electrophoresis with UV detection at 210nm, using borate buffer (pH 9) containing 100 mM SDS. The absolute detection limits were 200, 100 and 50 pg for histamine, 1-MH and N-MH, respectively. To purify histamine 1-MH and N-MH in urine, a silica cartridge was used. Recovery rates of histamine, 1-MH and N-MH in physiological saline were 90.0, 91.4 and 95.4%, respectively. We measured histamine and 1-MH levels in urine from a normal female volunteer before and after a meal, and a male bronchial asthma patient. The results showed clearly that the concentrations of histamine and its metabolite rose after eating or asthma attack. N-MH was not detected in the urine.     

Enhanced solubility of fullerene (C60) in water by inclusion complexation with cyclomaltononaose (δ-CD) using a cogrinding method

The solubilizing effects of cyclomaltononaose (δ-CD), a cyclic oligosaccharide composed of nine α-1,4-linked d-glucose units, on C₆₀ were investigated by using a ball-milling method based on a solid–solid mechanochemical reaction. The complex between C₆₀ and δ-CD was characterized by UV–VIS spectrometry, ¹³C-NMR, and fast atom bombardment mass spectrometry (FAB-MS). Coloration of the C₆₀/δ-CD system was yellowish-brown in aqueous solution, and the UV–VIS spectrum was in agreement with that of C₆₀ in hexane solution. The ¹³C-NMR spectrum of C₆₀/δ-CD system in aqueous solution revealed the presence of free δ-CD and dissolved C₆₀ giving one sharp peak at 144.4 ppm, which was close to that reported for C₆₀ in organic solvents. The FAB-MS spectrum of the C₆₀/δ-CD system showed a negative ion peak corresponding to the molecular weight of a complex between two δ-CDs and one C₆₀. Moreover, the phase solubility diagram of C₆₀ with δ-CD at 10 °C was classified as the Bs-type, resulting in a stoichiometric ratio of 1:2 (C₆₀:δ-CD), in agreement with the stoichiometry obtained from FAB-MS. These findings suggest that the solubilization of C₆₀ in water was due to complex formation of C₆₀ with δ-CD and that the stoichiometric ratio of the complex was 1:2 (C₆₀:δ-CD).     

Syntheses and crosslinking reactions of polymers containing spiroorthoester moieties

The radical copolymerization of unsaturated spiroorthoesters such as 2-methylene-1,4,6-trioxaspiro[4.6]undecane (SOE I) and 2-methylene-9-methyl-1,4,6-trioxaspiro[4,5]decane (SOE II) with vinyl monomers was carried out to find that SOE I and SOE II were copolymerized with electron-poor olefins such as methyl acrylate, acrylonitrile, and methyl methacrylate to obtain the corresponding copolymers containing spiroorthoester moieties, respectively. The obtained copolymers were treated with BF₃.OEt₂ or BzS⁺SbF to afford crosslinked polymers undergoing expansion in volume on crosslinking in those cases of copolymers of SOE I.     

Synthesis of phosphate‐pendant polymers and their application to thermally latent polymeric initiators

A novel phosphate monomer, O‐p‐(methacryloyloxymethyl)benzyl O,O‐diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2′‐azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 °C for 20 h to afford phosphate‐pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate‐pendant polymer as an initiator in the presence of ZnCl₂. The polymerization did not proceed below 90 °C but rapidly proceeded above 90 °C to afford polyGPE. The phosphate‐pendant polymer served as a good thermally latent polymeric initiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3365–3370, 2001     

Electronic effects of icosahedral carboranes: mechanistic alteration in solvolysis of α-(o-carboranyl)benzyl tosylates by electronic effect of substituents

Solvolysis of α-(o- and m-carboranyl)benzyl toluene-p-sulfonates bearing a range of substituents at the 3- or 4-position of the benzyl group has been investigated. The rates of hydrolysis of m-carboranyl derivatives increased linearly with increasing electron-releasing character of the substituent group (ρ=−5.37 correlated to σ⁺), which indicates that the hydrolysis proceeds through a typical S_N1 process. In contrast, the hydrolysis rates of the o-carboranyl derivatives with a wide range of electron-withdrawing substituents did not show significant change, but suddenly began to show a linear increase with increasing electron-releasing character of the substituents (ρ=−5.91 correlated to σ⁺). Moreover, the optical purity of the retentive hydrolysis of the o-carboranyl derivatives rapidly declined with increasing electron-donating effects of the substituents. This indicates that the mechanism of the hydrolysis changes from the retentive mechanism to an S_N1 mechanism.     

Dicarba-closo-dodecaboranes as a pharmacophore. Retinoidal antagonists and potential agonists

Synthesis and biological evaluation of the first dicarba-closo-dodecaborane (carborane) derivatives of retinoids are described. Their retinoidal activity were examined in terms of the differentiation-inducing ability toward human promyelocytic leukemia HL-60 cells. High retinoidal activity (agonist or antagonist for retinoic acid receptor (RAR) requires a carboxylic acid moiety and an appropriate hydrophobic group located at a suitable position on the molecule. The 4-carboranyl-substituted compounds (7, 11) showed antagonistic activity but no agonistic activity even in the presence of the potent synergist HX630. On the other hand, the 3-carboranyl-substituted compounds (8, 12) showed potential agonistic activity, but no antagonistic activity. The results indicates that carboranes are applicable as the hydrophobic moiety of biologically active molecules.     

Mechanism of atomic-scale passivation and flattening of semiconductor surfaces by wet-chemical preparations

Atomic arrangements of Si(001), Si(110) and 4H-SiC(0001) surfaces after wet-chemical preparations are investigated with scanning tunneling microscopy. Their passivated structures as well as the surface formation mechanisms in aqueous solutions are discussed. On both Si(001) and Si(110) surfaces, simple 1 × 1 phases terminated by H atoms are clearly resolved after dilute HF dipping. Subsequent etching with water produces the surfaces with 'near-atomic' smoothness. The mechanisms of atomic-scale preferential etching in water are described in detail together with first-principles calculations. Furthermore, 4H-SiC(0001), which is a hard material and where it is difficult to control the surface structure by solutions, is flattened on the atomic scale with Pt as a catalyst in HF solution. After a mechanism is proposed based on electroless oxidation, the flattened surface mainly composed of a 1 × 1 phase is analyzed. The obtained results will be helpful from various scientific and technological viewpoints.     

Inelastic neutron scattering study of acoustic phonons of black phosphorus

Dispersion relations of acoustic phonons of the orthorhombic black phosphorus have been measured at room temperature and atmospheric pressure. Very anisotropic dispersion surfaces were observed along the three principal directions. Comparison is made between the present measurements and the recent calculations of dispersion curves by Kaneta et al.     

Tin hyperfine fields in Co2 VSn and Co2 NbSn from Mössbauer spectroscopy

The hyperfine fields at the Sn sites in the Heusler type alloys Co₂ VSn and Co₂NbSn have been measured by the Mössbauer effect at 4.2 K to be + 9.9 and + 15.0 kOe, respectively. These anomalously small values are discussed in terms of the outer electron structure of these alloys.