Basic study on apoptosis induction into cancer cells U-937 and EL-4 by ultrasound exposure

Recently, the low invasive cancer treatments with small aftereffects have been considered. We are studying on the suppression methods of cancer cell proliferation with ultrasound. Cancer cells of mouse T lymphoma (EL-4) have been used in our study. The human histitocytic lymphoma cells (U-937) was used in this time. The cancer cells were cultured in a culture medium of RPMI1640. The standing wave acoustic field was formed in a water tank of our ultrasound exposure system by a vibrating plate driven with a Langevine type transducer. The U-937 and EL-4 were exposed to ultrasound in the acoustic field with spatial average acoustic intensity of 350 mW/cm(2) at 150 kHz. The viable rate of EL-4 decreased with the lapse of culture time after ultrasound exposure. U-937 did not show the remarkable decrease tendency. The proliferation of U-937 which exposed to ultrasound with 700 mW/cm(2) was suppressed. It can be thought that apoptosis was induced in the cancer cells in this condition. We observed the morphological change on the U-937 exposed to ultrasound with this condition. The morphological changes by apoptosis like the shrink of cells, formation of apoptotic bodies etc. can be observed with an optical microscope and a phase contrast microscope.     

Ligand dependence of pi-complex character in disilene-palladium complexes

The synthesis and structures of new 16-electron disilene palladium complexes with 2,6-dimethylphenyl isocyanide and phenyldimethylphosphine ligands [L(1)L(2)Pd{(t-BuMe(2)Si)(2)Si=Si(SiMe(2)Bu-t)(2)}, where L(1) = L(2) = PhMe(2)P; L(1) = (cyclohexyl)(3)P, L(2) = 2,6-dimethylphenyl isocyanide; L(1) = L(2) = 2,6-dimethylphenyl isocyanide] are described. Comparison of the X-ray structural parameters around the disilene moiety among these complexes and related bis(trimethylphosphine)(disilene)palladium and 14-electron (tricyclohexylphosphine)(disilene)palladium revealed that the pi-complex character is sensitive to the residual ligands and increases with decreasing the strength of sigma-donation from the ligands.     

Challenge to detect 1,4-zwitterions spectroscopically in a ketene-alkene reaction

The first example of direct spectroscopic detection of transient species, 1,4-zwitterions, generated in a ketene-alkene reaction is reported. Also, a striking result of the intervention of an unprecedented "1,4-zwitterion neutral dimer" is presented in a new mechanistic pathway; the ketene-alkene reaction gives the product cyclobutanone from the initial cycloadduct alpha-methyleneoxetane.     

An in situ M?ssbauer study using synchrotron radiation

We have been developing a system for in situ M?ssbauer studies using synchrotron radiation (SR) to elucidate the mechanism of hydrogenation processes. In the system, samples reacts in a pressure-temperature chamber and SR-based M?ssbauer spectra using variable-frequency nuclear monochromator and energy spectra of inelastic nuclear resonant scattering (NRS) of SR are measured. As a feasibility study, the temperature dependence of the M?ssbauer and inelastic NRS spectra of ⁵⁷Fe in c-GdFe₂H₃ under vacuum were measured. In both spectra, clear differences were observed between 373?K and 573?K. These differences can be interpreted by the change of microscopic environment around Fe at the dehydrogenation. Thus, it is confirmed that this system works well enough to perform the in-situ M?ssbauer study on the dehydrogenation of c-GdFe₂H₃.