Linear bipolar OTAs based on a triple-tail cell employing exponential circuits

Two types of new operational transconductance amplifiers (OTA), which are composed of exponential circuits and a triple-tail cell, are presented. The linear input voltage ranges of the proposed OTAs are wider than that of the triple-tail cell and have lower current consumption. The improvement of the signal-to-noise ratio is confirmed. The results of SPICE simulation show that the OTAs have good frequency responses. Monte Carlo simulation shows that the transconductance deviation of the proposed OTAs due to process variation is comparatively similar to that of the triple-tail cell.     

Induced excitation and synchronization of nerve impulses in two parallel unmyelinated fibers

The interaction of nerve impulses in two adjacent fibers has been treated quantitatively. Calculations were made on the basis of equations describing the propagation of impulses in electrically equivalent parallel transmission lines that contain the active membrane current elements proposed by Hodgkin and Huxley. The coupling between adjacent fibers is simulated by a resistive network. The effects of coupling appear to be as follows: while an impulse is traveling along one fiber, a change in the excitability of the other develops, and it has also been confirmed that, in the special case of strongly coupled fibers, excitation of the parallel fiber can be induced by the active one. In the case of parallel conduction of impulses in each fiber, synchronization of their conduction velocities becomes apparent when the inherent velocities of the impulses differ by not more than 20 percent. In general, the closer fibers approach one another and/or the greater the resistance of the interstitial fluid, the stronger is the apparent effect of interaction between impulses. The results of the present simulation are compared with the experimental observation by Katz and Schmitt.     

Effect of UFT on treatment of urological cancer--effect of UFT on treatment of invasive bladder cancer and advanced prostate cancer. Ibaraki Urological Cancer Chemotherapy Study Group

A prospective randomized joint study was conducted to evaluate the usefulness of UFT 1) as a postoperative adjuvant therapy in patients with invasive bladder cancer who had undergone curative combination therapy with operation and/or chemotherapy and/or radiation therapy, 2) as an endocrine chemotherapy in patients with newly diagnosed stage C/D prostate cancer, for a period of 3 years from January, 1992. For bladder cancer, of 36 patients with invasive bladder cancer, clinically cured by combination therapy, 20 patients were treated with UFT as an adjuvant chemotherapy over 12 months, and they were compared to 16 patients with no adjuvant therapy. After excluding 10 inappropriate patients, 12 patients in the UFT treatment group and 14 patients with no adjuvant treatment group were observed. For prostate cancer, of 29 patients with clinically stage C/D prostate cancer, 13 were treated with endocrine therapy in combination with UFT, and 16 patients were treated with endocrine therapy alone. After excluding 7 inappropriate patients, 10 patients with endocrine chemotherapy and 12 patients with hormonal therapy were observed. The non-recurrence rate, survival rate and side effects of UFT were evaluated. In the study of bladder cancer, neither a significant difference of non-recurrent rate nor of survival rate was seen between the two groups. In the study of prostate cancer, neither a significant difference of non-recurrent rate nor of survival rate was seen between the two groups. These findings suggest UFT is less useful as an adjuvant therapy for the invasive bladder cancer and as an endocrine chemotherapy for newly diagnosed advanced prostate cancer.     

Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1

Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway.     

Evaluation of the genotoxicity of stevioside and steviol using six in vitro and one in vivo mutagenicity assays

Stevioside, a constituent of Stevia rebaudiana, is commonly used as a non-caloric sugar substitute in Japan. The genetic toxicities of stevioside and its aglycone, steviol, were examined with seven mutagenicity tests using bacteria (reverse mutation assay, forward mutation assay, umu test and rec assay), cultured mammalian cells (chromosomal aberration test and gene mutation assay) and mice (micronucleus test). Stevioside was not mutagenic in any of the assays examined. The aglycone, steviol, however, produced dose-related positive responses in some mutagenicity tests, i.e. the forward mutation assay using Salmonella typhimurium TM677, the chromosomal aberration test using Chinese hamster lung fibroblast cell line (CHL) and the gene mutation assay using CHL. Metabolic activation systems containing 9000 g supernatant fraction (S9) of liver homogenates prepared from polychlorinated biphenyl or phenobarbital plus 5,6-benzoflavone-pretreated rats were required for mutagenesis and clastogenesis. Steviol was weakly positive in the umu test using S.typhimurium TA1535/pSK1002 either with or without the metabolic activation system. Steviol, even in the presence of the S9 activation system, was negative in other assays, i.e. the reverse mutation assays using S.typhimurium TA97, TA98, TA100, TA102, TA104, TA1535, TA1537 and Escherichia coli WP2 uvrA/pKM101 and the rec-assay using Bacillus subtilis. Steviol was negative in the mouse micronucleus test. The genotoxic risk of steviol to humans is discussed.     

InP/InGaAsP p-type substrate and mass transported doubly buried heterostructure laser

A novel InP/InGaAsP buried heterostructure laser diode on p-type InP substrate has been developed. The laser has achieved a threshold current as low as 20 mA DC with high power output of 50 mW under CW operation in the fundamental transverse mode.     

Effect of matrix's type on the dynamic properties for short fiber-elastomer composite

The dynamic moduli, E′ and E″, and tan δ for PET–CR, PET–EPDM, and PET–UR composites with unidirectional short fibers were studied as a function of temperature by using a Rheovibron. The temperature dependence of tan δ showed three peaks for PET–elastomer composites. The peaks at the low temperature corresponded to the main dispersion of the respective matrixes and the peak at about 140°C to the α-dispersion of PET fiber. A small and broad peak observed at a temperature between 60 and 120°C may be caused by the relaxation of the interface region between fibers and matrix. The longitudinal storage modulus for the composite E was given by the parallel model as \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm E'}_\parallel = V_f \cdot E'_f + V_m \cdot E'_m $\end{document}, where E and E are the storage moduli for fiber and matrix and V_f and V_m are the volume fraction of fiber and matrix, respectively. In the transverse direction of fibers, the composite modulus E was expressed by the logarithmic law of mixing as follows: \documentclass{article}\pagestyle{empty}\begin{document}$ \log E'_ \bot = V_f \cdot \log E'_f + V_m \cdot \log E'_m $\end{document}. The peak values of tan δ from the main dispersion of the respective matrixes were given by the equation, (tan δ_⊥max)_c/(tan δ_max)_m 1 ? β · V_f, where (tan δ_⊥max)_c and (tan δ_max)_m are the maximum values of the loss tangent for the composite and matrix, respectively, and β is coefficient depending on matrix's type. The β value of PET–CR composite is the largest one among those of the composites.