Muscarinic receptor-mediated dual regulation of ADP-ribosyl cyclase in NG108-15 neuronal cell membranes

Cyclic ADP-ribose (cADP-ribose) is an endogenous modulator of ryanodine-sensitive Ca2+ release channels. An unsolved question is whether or not cADP-ribose mediates intracellular signals from hormone or neurotransmitter receptors. The first step in this study was to develop a TLC method to measure ADP-ribosyl cyclase, by which conversion of [3H]NAD+ to [3H]cADP-ribose was confirmed in COS-7 cells overexpressing human CD38. A membrane fraction of NG108-15 neuroblastoma x glioma hybrid cells possessed ADP-ribosyl cyclase activity measured by TLC. Carbamylcholine increased this activity by 2.6-fold in NG108-15 cells overexpressing m1 or m3 muscarinic acetylcholine receptors (mAChRs), but inhibited it by 30-52% in cells expressing m2 and/or m4 mAChRs. Both of these effects were mimicked by GTP. Pretreatment of cells with cholera toxin blocked the activation, whereas pertussis toxin blocked the inhibition. Application of carbamylcholine caused significant decreases in NAD+ concentrations in untreated m1-transformed NG108-15 cells, but an increase in cholera toxin-treated cells. These results suggest that mAChRs couple to ADP-ribosyl cyclase within cell membranes via trimeric G proteins and can thereby control cellular function by regulating cADP-ribose formation.     

Linkage map of phenotype and RFLP markers in rice

The results from linkage mapping activities at Kyushu University during the last 10 years are summarized in this paper. The present paper concisely reveals present situation on linkage map of phenotype markers, the integration linkage map of phenotype and RFLP markers and the genetic stocks available. Some of the problems in this field, in addition, are pointed out and discussed.     

Fundamental optical constants of Nd-doped Y2O3 ceramic and its scintillation characteristics

Transparent Nd:Y₂O₃ ceramics were produced by vacuum sintering. Their fundamental optical constants including optical transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, and dielectric constant were evaluated. Scintillation characteristics including radio-luminescence and light yield under α (²⁴¹Am 5.5 MeV) excitation are reported as well.     

Evaluation of sintering stresses of an Al2O3 powder with a self-loading apparatus

The sintering stress of an Al₂O₃ powder, σ_s, is evaluated from an equation σ_s = F_s/ρS_a, where F_s is the uniaxial tensile force necessary to just stop the sintering contraction, ρ is the relative density, and S_a is the cross-sectional area. During densification, σ_s increases to the maximum at a relative density of 85%, and then abruptly decreases. The variation of σ_s in the intermediate sintering stage suggests a simple cubic packing of particles. Densification in the final sintering stage is explained by shrinkage of the pores at the corners where four tetrakaidecahedra meet. The present surface tensions of the Al₂O₃ powder evaluated from the σ_s roughly equal a reported value.     

Nanocrystalline Scandia Powders Via Oxalate Precipitation: The Effects of Solvent and Solution pH

Nanocrystalline Sc₂O₃ was synthesized via precipitation with scandium nitrate as the scandium source and oxalic acid as the precipitant, with investigations into the influences of solution pH and solvent type on powder properties. Three types of scandium precursors (normal oxalate, double oxalate, and oxyhydroxide) have been obtained from aqueous media by adjusting pH of the precipitant solution with ammonia water. All the precursors, however, yield severely aggregated Sc₂O₃ powders of low surface areas. Replacing water with pure ethanol as the solvent was shown to be able to yield Sc₂O₃ nanopowders of high specific surface area (35.7 m²/g) and good dispersion. The mechanisms of solution pH and solvent type on precursor properties were also discussed.     

Threshold-Volgage control schemes through substrate-bias for low-power high-speed CMOS LSI design

Lowering supply voltage,V _DD, is the most effective means to reduce power dissipation of CMOS LSI design. In lowV _DD, however, circuit delay increases and chip performance degrades. There are two means to maintain the chip performance: 1) to lower the threshold voltage,V _th, to recover circuit speed, or 2) to introduce parallel and/or pipeline architectures to make up for slow device speed. The first approach increases standby power dissipation due to lowV _th, while the second approach degrades worst case circuit speed caused byV _th fluctuation in lowV _DD. This paper presents two circuit techniques to solve these problems, in both of whichV _th is controlled through substrate bias. A Standby Power Reduction (SPR) scheme raisesV _th in a standby mode by applying substrate bias with a voltage-switch circuit. A Self-Adjusting Threshold-Voltage (SAT) scheme reducesV _th fluctuation in an active mode by adjusting substrate bias with a feed-back control circuit. Test chips are fabricated and effectiveness of the circuit techniques is examined. The SPR scheme reduces 50% of the active power dissipation while maintaining the speed and the standby power dissipation. The SAT scheme improves worst case circuit speed by a factor of 3 under a 1 VV _DD.     

The effect of an externally applied radio‐frequency electromagnetic field on the performance of a disk MHD generator

The effects of an externally applied radio‐frequency (rf) electromagnetic field on the nonequilibrium performance of a disk MHD generator were examined experimentally. As a preliminary experiment, plasma production by the applied rf electromagnetic field was attempted in the disk generator (Disk‐PIA), in which rf induction coils were embedded in the one‐side disk wall, under the conditions of no seeding, no flow, and no magnetic field. From the results of the preliminary experiment, it was confirmed that the argon plasma (～110 Torr) was produced uniformly in the azimuthal direction by the rf electromagnetic field even in the presence of exposed anodes in the faced disk wall and metallic support at the disk center. In MHD power generation experiments with the Disk‐PIA installed in the shock‐tube facility, the increase in the electrical output and more indiscrete discharge attributed to the rf electromagnetic field were verified with good reproducibility for the first time. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(4): 46–53, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10009     

Early hepatocellular carcinoma as an entity with a high rate of surgical cure

We present a case of central nervous system (CNS) infection due to Stomatococcus mucilaginosus involving a patient with leukemia and summarize 12 additional published reports of CNS infection due to this organism in immunocompromised hosts. The infection was diagnosed most commonly in the setting of hematologic malignancy accompanied by chemotherapy-induced neutropenia. S. mucilaginosus was recovered from blood prior to discovery of the CNS infection in 62% of cases. Signs or symptoms of CNS infection were observed in all patients. Although a number of patients responded to regimens containing intravenous vancomycin, the addition of intrathecal vancomycin appeared to be of benefit in some cases.