Translocation of sLe(x) on the azurophilic granule membrane to the plasma membrane in activated human neutrophils

Using immunogold electron microscopy, we found that human neutrophilic sialyl Lewis x (sLe(x)), an adhesive ligand for selectins, detectable by a monoclonal antibody, KM-93, is present in the sacculi of the Golgi apparatus as well as on the membranes of large electron-lucent azurophilic granules and the plasma membrane, including surface projections and microvilli. Neutrophilic sLe(x), however, was not detected on the membranes of specific granules. In comparison with the distribution of sLe(x), CD18 was localized on the plasma membrane and specific granule membrane but not on the azurophilic granule membrane. We also found by immunogold electron microscopy and flow cytometry that treatment of neutrophils with sialidase resulted in a loss of sLex on the plasma membrane. In contrast, intracellular sLex on the azurophilic granule membrane was not destroyed by sialidase. When sialidase-treated neutrophils were stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP), an inflammatory mediator peptide, in the presence of cytochalasin B, we observed by immunogold electron microscopy and flow cytometry that sLe(x) again appeared on the plasma membrane. These results indicate that stimulation by fMLP induces the up-regulation of sLe(x) on the cell surface by promoting translocation of sLe(x) from the azurophilic granule membrane to the plasma membrane in human neutrophils.     

Radical-initiator-Induced solid-state polymerization of butadiyne nanocrystals in water and their dispersion stabilization

Butadiyne nanocrystals in water are usually polymerized by UV or gamma-ray irradiation to give polydiacetylene (PDA) nanocrystals. In this study, we confirmed that solid-state polymerization of 1,6-di(N-carbazolyl)-2,4-hexadiyne (DCHD) and 5,7-dodecadiyn-1,12-diyl bis[N-(butoxycarbonyl-methyl)carbamate] (4BCMU) could be stimulated by water-soluble radical initiators. The radical initiators used were potassium peroxodisulfate, three kinds of azo-type compounds and a redox initiator. In all cases, the solid-state polymerization was confirmed by color change into blue indicating that PDA modified by the radical residues at the end was formed. However, nanocrystal cohesion occurred especially when the concentration of the initiators was high or the dispersion was kept for a long time. In order to improve the dispersion stability, two kinds of surfactants, i.e., sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTMAC), were added to the DCHD nanocrystal aqueous dispersion. As a result, when anionic SDS was added, the solid-state polymerization of nanocrystals proceeded without coagulation and quantitative conversion was confirmed for all initiators. Cationic DTMAC has no effect on dispersion stabilization. PDA nanocrystal surfaces in water are negatively charged in nature and electric interaction of nanocrystals with the cations results in decrease of surface charge and aggregation of nanocrystals.     

200 Channel Semiconductor Detectors for X-Ray Computed Tomography

Prototype 200 channel semiconductor detectors for third generation X-ray computed tomography have been developed using surface-barrier diodes fabricated from high-purity n-type silicon. The image reconstruction test was successful, and the relationship between the image quality and the detector characteristics has been studied.     

Peculiar sandwich-like π–π interaction regulating the nonplanarity of the model heme crystals

X-ray crystallographic analysis of bis(pyridine N-oxide) complexes of iron(III) porphyrinates has revealed that the two pyridine rings of the axial ligands correctly sandwich the porphyrin ring to induce the deformation of commonly observed S₄ saddled porphyrin ring.