Resin-packed nanoelectrospray in combination with video and mass spectrometry for the direct and real-time molecular analysis of mast cells

A nano-electrospray ionization (nanoESI) emitter for analysis of a biological solution was developed by packing a nanoESI needle with two types of resins for desalting and preconcentration of target molecules. Determination of secreted histamine and serotonin molecules in cell culture buffers was demonstrated using 5-methyltryptamine as internal standard. The results showed good linearity of target signals in the concentration range from 0.25 to 50.0 ng/mL of histamine or serotonin. These molecules were monitored to be secreted by A23187 (calcium ionophore) stimulant in rat peritoneal mast cells. Using a combination of a video-microscope and a mass spectrometer, we could visualize exocytotic moments and analyze secreted molecules by mass spectrometry simultaneously. Time-dependent release of histamine and serotonin from activated mast cells showed that significant production of these molecules occurred and reached a maximal level at 15 min for serotonin and at 30 min for histamine, respectively. These results showed that this method allows the direct and timely analysis of secreted molecules in biological responses.     

Flame characteristics of small-scale pool fires under low gravity environments

The flame characteristics of pool fires such as oscillatory frequency, flame height, and so on differ depending on gravity. To improve our understanding of the effects of gravity on flame characteristics, we conducted an experimental investigation on small-scale pool fires under different gravity levels to normal. The drop tower facility at Hirosaki University in Japan was used to obtain an arbitrary low gravity environment. Our measurements include analyses of oscillatory frequency and flame height under low gravity environments and flow visualization by a particle-track laser-sheet technique (PTLS) combined with a high-speed camera. These measurements revealed that the puffing frequency and flame height declined with decreasing gravity. The puffing frequency was summarized by the relationship between the Strouhal and Froude numbers. The flame height showed a tendency to peak at a certain level of gravity. The behavior of the flame height under low gravity did not correlate to the scaling prediction previously presented, while the normal velocity component to the flame sheet declined with decreasing gravity. The chemical reaction in the flame may be restricted due to decreasing oxygen supply. Consequently, the convective heat feedback to the liquid surface falls, causing the flame height to decline with decreasing gravity.     

Asymmetric synthesis of axially chiral biaryl diphosphine ligands by rhodium-catalyzed enantioselective intramolecular double [2 + 2 + 2] cycloaddition

The concise synthesis of axially chiral biaryl diphosphine ligands by the rhodium-catalyzed intramolecular [2 + 2 + 2] cycloaddition of hexayne diphosphine oxides has been achieved. These new chiral diphosphine ligands could be employed as a ligand for the rhodium-catalyzed asymmetric catalyses.     

Synthesis, inhibitory effects on nitric oxide and structure-activity relationships of a glycosphingolipid from the marine sponge Aplysinella rhax and its analogues

The novel glycosphingolipid, β-D-GalNAcp(1-->4)[α-D-Fucp(1-->3)]-β-D-GlcNAcp(1-->)Cer (A), isolated from the marine sponge Aplysinella rhax has a unique structure, with D-fucose and N-acetyl-D-galactosamine moieties attached to a reducing-end N-acetyl-D-glucosamine through an α1-->3 and β1-->4 linkage, respectively. We synthesized glycolipid 1 and some non-natural di- and trisaccharide analogues 2-6 containing a D-fucose residue. Among these compounds, the natural type showed the most potent nitric oxide (NO) production inhibitory activity against LPS-induced J774.1 cells. Our results indicate that both the presence of a D-Fucα1-3GlcNAc-linkage and the ceramide aglycon portion are crucial for optimal NO inhibition.     

Cisplatin-encapsulated organic nanotubes by endo-complexation in the hollow cylinder

A bipolar glycolipid self-assembles into organic nanotubes upon its chelation with an anticancer drug cis-dichlorodiamineplatinum(ii) (CDDP). The facile synthesis of glycolipid, chelation-assisted formation of the nanotubes, and efficient loading and prolonged release of CDDP demonstrate a new approach to high-axial supramolecular drug nanocarriers.     

A new class of flavonoids bearing macrocyclic polyethers by stereoselective photochemical cycloaddition reaction

A new class of flavonoids bearing cyclic polyethers involving a phenyl ring was conveniently provided by the intramolecular photochemical dimerization of 2-chromonecarboxylic esters. Irradiation of 2-chromonecarboxylate with a polyether tethered at both ends promoted intramolecular [2 + 2] cyclobutane formation leading to 14- to 27-membered cyclic polyethers. The efficiency depended on the substituted position of the phenyl ring, with ortho- and meta-substituted derivatives giving cycloadducts in good chemical yields and quantum efficiencies, whereas the para-derivatives were inert toward photolysis. X-ray crystallographic analysis revealed that the stereochemistry of the macrocyclic cycloadducts exhibited C₂-symmetry.     

Highly selective recognition of adenine nucleobases by synthetic hosts with a linked five-six-five-membered triheteroaromatic structure and the application to potentiometric sensing of the adenine nucleotide

A new structure for an adenine-selective host molecule, featuring the pertinent link of five-six-five-membered heteroaromatic rings and two carbamoyl NH sites, was developed. This structure provides a correctly oriented array of complementary hydrogen bonding sites for the adenine nucleobase, which exploits both Watson-Crick and Hoogsteen-type interactions. The complexation with adenine nucleobases by multiple hydrogen bonding was supported by (1)H NMR spectroscopy. This type of host displayed high selectivity in complexation, with an accompanying fluorescent response to lipophilized adenosine in CHCl(3). Furthermore, a remarkably selective potentiometric response was attained for adenosine 5'-monophosphate over 5'-GMP, 5'-CMP, and 5'-UMP by using an ion-selective electrode with a PVC-supported solvent polymeric membrane. This indicates recognition of water-soluble nucleotide guests through the membrane-water interface. These findings are expected to form a reliable basis for the development of artificial sensing systems for mononucleotides in biological systems.     

Synthesis and structure of dipalladium complexes containing cyclooctatetraene and bicyclooctatrienyl ligands

The reaction of a substitutionally labile dipalladium(I) complex [Pd₂(CH₃CN)₆][BF₄]₂ (1) with 1,3,5,7-cyclooctatetraene (COT) in acetonitrile afforded [Pd₂(μ-η³:η³-C₈H₈)(CH₃CN)₄][BF₄]₂ (2). The reaction of 2 with COT in acetonitrile yielded [Pd₂(μ-η³:η³-C₁₆H₁₆)(CH₃CN)₄][BF₄]₂ (4), where COT is dimerized via C-C bond formation. Complexes 2 and 4 were structurally characterized by X-ray diffraction analyses. In dichloromethane, COT isomerized to styrene at room temperature in the presence of catalytic amount of 1, 2, or 4.     

Enantioselective Synthesis of [9]‐ and [11]Helicene‐like Molecules: Double Intramolecular [2+2+2] Cycloaddition

The enantioselective synthesis of completely ortho‐fused [9]‐ and [11]helicene‐like molecules has been achieved through a rhodium‐mediated, intramolecular, double [2+2+2] cycloaddition of phenol‐ or 2‐naphthol‐linked hexaynes. Crystal structures and photophysical properties of these [9]‐ and [11]helicene‐like molecules have also been disclosed.