Cell cycle analysis of Chinese hamster ovary cells stimulated by phosphatidic acid in serum-free culture

When recombinant Chinese hamster ovary cells were treated with pertussis toxin or genistein, not only lysophosphatidic acid (LPA) but also phosphatidic acid (PA) failed to stimulate progression through the cell cycle in serum-free culture, suggesting that PA and LPA induce cell growth through the same signal transduction pathway. Cell cycle analysis also indicates that cell growth promoted by PA results in enhanced protein production.     

Spectroscopic studies on the rare-earth vanadites

The nature of the V/1bO/1bV interaction of the perovskite type rare-earth vanadites were studied by spectroscopic methods. Infrared and ultraviolet analyses revealed that the V/1bO bond length became shorter and that the V/1bO bond strength increased, as a function of the atomic number of lanthanide elements in LnVO₃. Judging from the x-ray fluorescent spectra of oxygen-K_α, the energy level of O^2? (p_π) orbitals of the heavier rare-earth vanadites was lower than that of the lighter rare-earth vanadites.     

The MHD effect and its relaxation process on electric current in the electrolysis of ferricyanide reduction and ferrocyanide oxidation

The electrolytic reduction of ferricyanide and the electrolytic oxidation of ferrocyanide have been carried out with exposing the magnetic field of 1000 or 1800 gauss. The current clearly increased after the magnetic exposure. The maximum current was obtained when the magnetic flux directed in parallel with the surface of electrode. These are speculated in terms of magnetohydrodynamic mechanism. The current decrease caused by relaxation process was observed after the removal of magnetic flux. The relaxation time obtained was temperature-dependent. Therefore the values of apparent transition energy, E_trans, were determined from the Arrhenius' plots of relaxation time against temperature. The magnitude of E_trans was dependent on the concentration of ferricyanide or ferrocyanide, and the viscosity and the conductivity of electrolyte solution. The activation energy of viscosity of electrolyte solution was compared with E_trans. As a conclusion, it was suggested that E_trans may be influenced by the velocity of magnetohydrodynamic flow, which was controlled by the diffusion current in electrolysis and the viscosity of electrolyte solution.     

Room temperature c.w. operation of InGaAsP/InP heterostructure lasers emitting at 1.56 ?m

Room-temperature c.w. operation of InGaAsP/InP heterostructure lasers grown by liquid-phase epitaxy was achieved at 1.56 ?m. An active InGaAsP layer was essentially sandwiched by InP, though a thin InGaAsP buffer layer was deposited to prevent the melt-back of the active layer. Threshold current was typically 300 mA for a 17 ?m wide oxide-defined stripe laser.     

Direct modulation of InGaAsP/InP double heterostructure lasers

Direct modulation of an InGaAsP/InP double heterostructure laser was investigated experimentally. Sinusoidal modulation up to 2.5 GHz was achieved with almost constant modulation efficiency. Pulse responses showed that the damped relaxation oscillation in light output was well suppressed.     

Synchronous firing and higher-order interactions in neuron pool

The stochastic mechanism of synchronous firing in a population of neurons is studied from the point of view of information geometry. Higher-order interactions of neurons, which cannot be reduced to pairwise correlations, are proved to exist in synchronous firing. In a neuron pool where each neuron fires stochastically, the probability distribution q(r) of the activity r, which is the fraction of firing neurons in the pool, is studied. When q(r) has a widespread distribution, in particular, when q(r) has two peaks, the neurons fire synchronously at one time and are quiescent at other times. The mechanism of generating such a probability distribution is interesting because the activity r is concentrated on its mean value when each neuron fires independently, because of the law of large numbers. Even when pairwise interactions, or third-order interactions, exist, the concentration is not resolved. This shows that higher-order interactions are necessary to generate widespread activity distributions. We analyze a simple model in which neurons receive common overlapping inputs and prove that such a model can have a widespread distribution of activity, generating higher-order stochastic interactions.     

Lipid peroxidation-derived cytotoxic aldehyde, 4-hydroxy-2-nonenal in smoked pork

The contents of 4-Hydroxy-2-nonenal (HNE), cytotoxic aldehyde, in smoked meat products (ham, bacon and sausage) were analyzed. All the samples analyzed contained HNE, although large differences in the contents between the different samples were observed. In one lot of ham (H1) and wiener sausage (WS1) a high level in HNE was observed. The changes of HNE contents of pork meats containing 0, 0.1, 0.5 and 1% Sugi wood vinegar (SWV) stored at 0?°C were also analyzed for 7 days. As an index of lipid peroxidation level, malonaldehyde (MA) contents were also analyzed in these samples. After 7 days of storage, HNE was detected only in pork meats containing 1% SWV and the level was similar to those of H1 and WS1. Judging from MA contents, SWV may act as a pro-oxidant in pork meats and HNE may accumulate in pork in which lipid peroxidation is in progress.     

Discrimination of psychoactive fungi (commonly called "magic mushrooms") based on the DNA sequence of the internal transcribed spacer region

'Magic mushrooms' (MMs) are psychoactive fungi containing the hallucinogenic compounds, psilocin (1) and psilocybin (2). Since June 6, 2002, these fungi have been regulated by the Narcotics and Psychotropics Control Law in Japan. Because there are many kinds of MMs and they are sold even as dry powders in local markets, it is very difficult to identify the original species of the MMs by morphological observation. Therefore, we investigated the internal transcribed spacer (ITS) region in the ribosomal RNA gene of MMs obtained in Japanese markets to classify them by a genetic approach. Based on the size and nucleotide sequence of the ITS region amplified by PCR, tested MMs were classified into 6 groups. Furthermore, a comparison of the DNA sequences of the MMs with those of authentic samples or with those found in the databases (GenBank, EMBL and DDBJ) made it possible to identify the species of tested MMs. Analysis by LC revealed that psilocin (1) was contained at the highest level in Panaeolus cyanescens among the MMs, but was absent in the Amanita species.     

Ice clouds and Asian dust studied with lidar measurements of particle extinction-to-backscatter ratio, particle depolarization, and water-vapor mixing ratio over Tsukuba

The tropospheric particle extinction-to-backscatter ratio, the depolarization ratio, and the water-vapor mixing ratio were measured by use of a Raman lidar and a polarization lidar during the Asian dust seasons in 2001 and 2002 in Tsukuba, Japan. The apparent (not corrected for multiple-scattering effects) extinction-to-backscatter ratios (Sp) showed a dependence on the relative humidity with respect to ice (RHice) obtained from the lidar-derived water-vapor mixing ratio and radiosonde-derived temperature; they were mostly higher than 30 sr in dry air (RHice < 50%), whereas they were mostly lower than 30 sr in ice-supersaturated air (RHice > or = 100%), where the apparent extinction coefficients were larger than 0.036 km(-1). Both regions showed mean particle depolarization ratios of 20%-22%. Comparisons with theoretical calculations and the previous experiments suggest that the observed dependence of Sp on RHice is attributed to the difference in the predominant particles: nonspherical aerosols (mainly the Asian dust) in dry air and cloud particles in ice-supersaturated air.