Modification of physicochemical properties of actin filaments suppresses cell fragmentation in the execution phase of staurosporine-induced apoptotic processes

Effects of jasplakinolide (JSP), a stabilizer of F-actin, and latrunculin A (LTA), a destabilizer of F-actin, on a series of events occurring in the execution phase of staurosporine (STS)-induced apoptotic processes were studied using human osteosarcoma 143B cells. Time-dependent apparent increases of the population of cells with collapsed membrane potential of mitochondria (Delta Psi(m)) caused by STS treatment were not due to actual decreases in the Delta Psi(m) per cell, but due to the fragmentation of cells resulting in decreases in the number of active mitochondria per cell. Decreases in the Delta Psi(m) in fragmented cells occurred late in the execution phase. Both JSP and LAT failed to prevent STS-induced release of cytochrome c from mitochondria followed by the activation of caspases 3 and 9, the cleavage of poly (ADP-ribose) polymerase (PARP) and apoptotic nuclear fragmentation. However, both drugs prevented STS-induced apoptotic cell fragmentation and decreases in the Delta Psi(m). These results indicate that physicochemical states of actin filaments play a certain role in the execution phase of STS-induced apoptotic processes.     

Solid phase synthesis of oligomannopeptoids that mimic the concanavalin A-binding trimannoside

Oligomannopeptoids from the dimer to the hexamer were produced by solid phase synthesis and their abilities to bind to concanavalin A (ConA) were assessed. The assessment indicated similarity between the oligomannopeptoids and the naturally occurring oligomannosides in the enthalpy of the binding and the valence number vs binding strength relationship, encouraging the use of the oligomannopeptoids as oligomannoside mimics.     

Synthesis and Spectral Characterization of Difunctional Fullerenes

The oxidation of C₆₀ with m-chloroperbenzoic acid gave C₆₀O₂ with a high positional selectivity, as the ¹³C NMR analysis suggested. Diadducts C₆₀CCI₂O, C₆₀CCl₂(anthracene), C₆₀CCl₂[(CH₂CH₂)₂N₂], and C₆₀CCI₂[Pt-(PPh₃)₂] were synthesized, isolated, and characterized by negative ion FAB mass spectroscopy.     

The phase reversal effect of a fiber Bragg grating and its application to optical switches

We propose an interferometer‐type multistate optical switch and an interferometer‐type digital performance switch using a fiber Bragg grating (FBG) and the phase reversal effect. The effect is a reversing phenomenon of optical phase difference between the reflected and transmitted light from an FBG on a reflectivity spectrum dip between the main reflection band and first sideband. By combining this effect and reflectivity change, the multistate switch including only a single FBG can perform as a four‐state switch. In this paper we describe the principle of the phase reversal effect and some novel optical switch structures, and also the results of experimental examination. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(3): 38–48, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10136     

Intentional side etching to achieve low-noise GaAs f.e.t.

A very-low-noise 0.5 ?m-gate GaAs f.e.t. is realised by using intentional side etching of an Au/Ti double layer as the Schottky-gate metal. At 12 GHz, the minimum noise figure is 2.1 dB, with 7.6 dB associated gain at a bias of VD = 4 V, ID= 10 mA. Maximum stable gain is 14 dB at VD = 4 V, ID = 30 mA.     

Novel method for numerical analysis of electron trajectories in electrostatic fields of implicit functional forms

A novel method for calculating 2-dimensional electron trajectories is given, which is useful for the case when the electric fields are expressed by implicit functional forms which are not suited to a conventional electron-trajectory analysis. This method is applied to parallel-plate and parallel-cylinder deflection systems.     

Role of mitochondria in the switch mechanism of the cell death mode from apoptosis to necrosis--studies on rho0 cells

Detailed mechanisms of the switch of the cell death mode from apoptosis to necrosis remain to be solved, although the intracellular level of ATP and that of free radicals have been postulated to be the major factors involved in the mechanisms. In the present study menadione (MEN)-induced cell injury processes were studied using rho0 cells derived from human osteosarcoma 143B cells and parental rho+ cells co-treated with inhibitors of electron transfer chain of mitochondria or oligomycin, an inhibitor of ATP synthesis. Treatment of rho+ cells with 100 microM MEN induced apoptosis, which reached the maximum at 6 h, and was followed by an abrupt decrease thereafter, while necrotic cells (NC) increased continuously when they were judged by Annexin V and PI double staining. On the other hand, MEN induced apoptotic and necrotic changes much faster in rho0 cells compared to rho+ cells. The frequency to find apoptotic cells (AP) in the former cells was distinctly smaller than that to find NC judged by Annexin V and PI double staining. Electron microscopically, a major population of rho0 cells treated with MEN for 6 h consisted of intermediate cells, and a small number of AP co-existed. At 9 h of the treatment intermediate cells were exclusively seen, and AP were hardly detected. When parental rho+ cells were treated with MEN in the presence of oligomycin or oligomycin plus antimycin A both apoptotic and necrotic changes of the cells were distinctly accelerated. The intracellular level of superoxide in rho0 cells continuously increased after the MEN treatment, whereas that of ATP remained distinctly low before and after the MEN treatment compared to that in rho+ cells. These data suggest that the intracellular level of superoxide may be a key factor controlling the switch from apoptosis to necrosis.