Seiji Suzuki

Stimulation of guanosine 3′,5′-cyclic monophosphate accumulation in rat anterior pituitary gland in vitro by synthetic somatostatin

Abstract Synthetic somatostatin stimulated cyclic GMP accumulation with dose dependency (10 ng/ml – 10 μg/ml in a dose examined) in rat anterior pituitary gland in vitro. The stimulation of cyclic GMP levels in the gland was observed after 2 min incubation with somatostatin. Cyclic AMP production induced by TRH or PGE 1 was supressed by this GH release inhibiting factor, while cyclic GMP concentration in the gland was elevated. The present results seem to suggest that inhibitory effect on GH release by somatostatin in anterior pituitary gland is mediated through change in concentration of cyclic AMP and cyclic GMP in the target cells.

Role of hydrogen during rapid vapor-phase doping analyzed by x-ray photoelectron spectroscopy and Fourier-transform infrared-attenuated total reflection

The surface of boron-doped layers formed by rapid vapor-phase doping was analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared-attenuated total reflection (FTIR-ATR), to determine the role of the hydrogen carrier gas. Boron doping was carried out with a B2H6 source gas and a hydrogen carrier gas at 800 and 900u2009°C. A nitrogen carrier gas was also used for comparison. Using hydrogen carrier gas, no evidence of boron segregation was observed in the XPS spectra. FTIR-ATR analysis confirmed that the hydrogen termination of the surface was maintained during doping. Using nitrogen carrier gas, layers that included segregated boron and silicon nitride were produced on the surface, which led to poor controllability of the boron concentration. When a hydrogen carrier gas is used, the hydrogen termination should promote the surface migration of adsorbed species. The hydrogen carrier gas plays an important role in terminating the silicon dangling bonds, thus preventing excessive chemisorption of boron.The surface of boron-doped layers formed by rapid vapor-phase doping was analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared-attenuated total reflection (FTIR-ATR), to determine the role of the hydrogen carrier gas. Boron doping was carried out with a B2H6 source gas and a hydrogen carrier gas at 800 and 900u2009°C. A nitrogen carrier gas was also used for comparison. Using hydrogen carrier gas, no evidence of boron segregation was observed in the XPS spectra. FTIR-ATR analysis confirmed that the hydrogen termination of the surface was maintained during doping. Using nitrogen carrier gas, layers that included segregated boron and silicon nitride were produced on the surface, which led to poor controllability of the boron concentration. When a hydrogen carrier gas is used, the hydrogen termination should promote the surface migration of adsorbed species. The hydrogen carrier gas plays an important role in terminating the silicon dangling bonds, thus preventing excessive chemisorpt...

Effect of glucose on protein phosphorylation in rat pancreatic islets

Isolated rat pancreatic islets, incubated in the presence of extracellular 32Pi to steady state 32P incorporation into cellular phosphopeptides, were exposed to glucose for 10 min. Glucose (16.7 mM) significantly stimulated the phosphorylation of six phosphoproteins with molecular weights of 15,000, 35,000, 49,000, 64,000, 93,000 and 138,000. Mannoheptulose (16.7 mM) markedly inhibited glucose-stimulated phosphorylation of these six phosphoproteins. This protein phosphorylation might be important in mediating glucose-stimulated insulin release.

Effect of an intracellular calcium antagonist (TMB-8) on carbamylcholine-induced amylase release from dispersed rat pancreatic acini

During 10-min incubation with increasing concentrations of carbamylcholine (carbachol), amylase release from dispersed rat pancreatic acini increased, became maximal at 2 X 10(-6)M and then decreased. In the concentration range of 10(-7)M to 10(-4)M, 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8) caused a dose-dependent inhibition of amylase release induced by a submaximal concentration of carbachol. No inhibitory effect was observed on basal and secretin-stimulated amylase release. TMB-8 showed a significantly greater ability of blocking the action of carbachol than verapamil and diltiazem. TMB-8 could reverse the submaximal stimulation of amylase release caused by supramaximal concentrations of carbachol to a maximal stimulation, while verapamil and diltiazem could not. These results confirm the hypothesis that mobilization of intracellular calcium is the primary step in the action of carbachol on pancreatin acinar cells and contributes to the submaximal secretory response of acinar cells induced by high concentrations of carbachol.

Effect of secretin on protein phosphorylation in dispersed acini from rat pancreas.

Dispersed acini from rat pancreas, incubated in the presence of KH2(32)PO4 to steady state 32P incorporation into cellular proteins, were exposed to secretin. 32P incorporated into selected proteins, separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, reached a plateau by 150 min. Effect of secretin on amylase release, cellular cyclic AMP levels and protein phosphorylation was then examined. Stimulation of amylase release was apparent with 10(-10)M and was maximal with 10(-7)M by 10 min incubation. Almost maximal increase in cellular cyclic AMP levels and 32P incorporation into selected proteins was also observed with 10(-7)M secretin by 10 min in the presence of 10 mM theophyllin. Both secretin (10(-8)M) and dibutyryl cyclic AMP (10(-3)M) induced the phosphorylation of similar proteins analyzed by counting 32P content in each peptide band after SDS gel electrophoresis. Addition of cyclic AMP (10(-6)M) to homogenates of acini also augmented 32P incorporation from [gamma-32P]ATP into similar proteins. These results indicate that secretin enhances protein phosphorylation in pancreatic acinar cells and cyclic AMP may mediate the action of secretin on protein phosphorylation.

Dynamic Floating Body Effects in Fully Depleted SOI MOSFET's

L.Abstract By using high-frequency Ring Oscillators, the dynamic Floating Body Effect(FBE) and delay time on fully depleted Silicon-on-insulator(FD-Sol) CMOS inverters have been evaluated, for the first time, up to 500 MIIZ. As a result of dynamic FBE, an increase of inverter delay time is observed for frequencies above 150 MIIZ for the 0.25un1 and 0.35um FD-SOI evaluated devices. 2. Introduction SOI devices are recently notable for low-power portable terminal applications. As traditional study, characteristics of IID-SOI are as follows. Steep subthreshold[L], Kinkless[2], Enhancement of current driver-ability[3],[4], Stability for floating body effects[5],[6] However the body potential of FD-SOI is not fixed because of device structure. Therefore FD-SOI characteristics fluctuate by the body potential variation. In this paper, we describe the delay characteristics for dynamic IIBE by evaluating the ring-oscillator circuits fabricated by 0.25um and 0.35um FD-SOI technologies. From the analysis of delay characteristics, the delay time instability is caused by the dynamic body potential variation owing to the unbalance of charging of floating body by impact ionization and discharge of diode currents. 3. Experiment The dymamic floating body effects are evaluated by measuring the propagation delay time(tpd) for various CMOS inverter-type ring-oscillators with different number of stages(f{).[fro=L/2NTpd, with N=11,23,37,47,79,L011 The measured circuits which include a 256-divider due to be measurable high-frequency is shown in Fig. 1. Brief transistor description and characteristics to demonstrate the transistors are really FD are shown in Table L and Fig.2., respectively. 4. Results and Discussion Dependence of delay on oscillating frequency The dependence of delay time on oscillating frequency is shown in Fig. 3 at Vdd=lV. When the oscillating frequency is over 150 MlIz, the propagation delay time increases with increase of oscillating frequency. The Maximum increase rate is 9.6% at 48L MHz and room temperature. The above phenomenon in PD-SOI has been observed, and it is caused by the majority carrier re-distribution effect[7]. However this majority carrier re-distribution effect does not occul in FD-SOI, since the body is usually depleted. Inlluence of fixed body potential Extended Abstracts of the 2002 International Conference on Solid State Devices and Materials, Nagoya, 2002, pp.796-797