Dynamic Compaction of Amorphous Co_<70.3>Fe_<4.7>Si_<15>B_<10> Alloy Powders Obtained by a Cavitation Method

Amorphous Co_Fe_Si_B_ alloy powders prepared by a cavitation method were dynamically compacted by using a propellant gun. The compacts retained amorphism when they were formed under shock pressures below 8GPa. The highest degree of compaction gave a density of 7.67 Mg/m^3 or 99.6% of that of the amorphous ribbons. After proper heat-treatment, the compact of 0.13mm thick gave a coercive force of 10mOe and a permeability at 100Hz of 12000. Further annealing in rotating magnetic field was found to make the permeability higher. An evident effect of powder size on the soft magnetic properties of compacted powders was also found

Carbenoxolone-sensitive and cesium-permeable potassium channel in the rod cells of frog taste discs

The rod cells in frog taste discs display the outward current and maintain the negative resting potential in the condition where internal K+ is replaced with Cs+. We analyzed the properties of the Cs+-permeable conductance in the rod cells. The current-voltage (I/V) relationships obtained by a voltage ramp were bell-shaped under Cs+ internal solution. The steady state I/V relationships elicited by voltage steps also displayed the bell-shaped outward current. The activation of the current accelerated with the depolarization and the inactivation appeared at positive voltage. The gating for the current was maintained even at symmetric condition (Cs+ external and internal solutions). The wing cells did not show the properties. The permeability for K+ was a little larger than that for Cs+. Internal Na+ and NMDG+ could not induce the bell-shaped outward current. Carbenoxolone inhibited the bell-shaped outward Cs+ current dose dependently (IC50: 27μM). Internal arachidonic acid (20μM) did not induce the linear current-voltage (I-V) relationship which is observed in two-pore domain K+ channel (K2P). The results suggest that the resting membrane potentials in the rod cells are maintained by the voltage-gated K+ channels

Postoperative Prognosis of Breast Cancer Patients Predicted by p53 Gene Mutation in Cancer Cells Obtained by Aspiration Biopsy

The method of cytological examination by fine needle aspiration biopsy (FNAB) was developed clinically in breast cancer and enabled us to prepare cancer cell nuclei for the detection of p53 gene mutation. In the expectation that this method would improve the prediction of postoperative prognosis, the observation of 10 year survival for breast cancer patients with p53 gene mutations was done. The DNA of the aspirated cells was examined preoperatively for gene alterations in 53 patients with breast cancer. The p53 protein accumulation, DNA ploidy pattern, estrogen receptor (ER) , and clinicopathological factors were examined postoperatively The postoperative follow up was conducted over 10 years and evaluated the status of p53 gene mutation. In 26 patients (49.1%) , 29 p53 gene mutations were shown. p53 protein accumulations and DNA aneuploidy patterns were detected in 33 (62.3%) and 42 (79.2%) cases, respectively, and both significantly correlated with p53 gene mutations. With regard to the postoperative prognosis, in over 10 years of observation, the patients who showed p53 mutations had a significantly worse prognosis in both disease free survival and overall survival than those showing negative p53 mutation. A similar tendency was also seen in patients with histologic grade 3. Using FNAB, the usefulness of the preoperative detection of p53 gene mutation was revealed, suggesting its clinical benefits for predicting a patient\u27s prognosis

High Extracellular Ca2+ Stimulates Ca2+-Activated Cl− Currents in Frog Parathyroid Cells through the Mediation of Arachidonic Acid Cascade

Elevation of extracellular Ca2+ concentration induces intracellular Ca2+ signaling in parathyroid cells. The response is due to stimulation of the phospholipase C/Ca2+ pathways, but the direct mechanism responsible for the rise of intracellular Ca2+ concentration has remained elusive. Here, we describe the electrophysiological property associated with intracellular Ca2+ signaling in frog parathyroid cells and show that Ca2+-activated Cl− channels are activated by intracellular Ca2+ increase through an inositol 1,4,5-trisphophate (IP3)-independent pathway. High extracellular Ca2+ induced an outwardly-rectifying conductance in a dose-dependent manner (EC50∼6 mM). The conductance was composed of an instantaneous time-independent component and a slowly activating time-dependent component and displayed a deactivating inward tail current. Extracellular Ca2+-induced and Ca2+ dialysis-induced currents reversed at the equilibrium potential of Cl− and were inhibited by niflumic acid (a specific blocker of Ca2+-activated Cl− channel). Gramicidin-perforated whole-cell recording displayed the shift of the reversal potential in extracellular Ca2+-induced current, suggesting the change of intracellular Cl− concentration in a few minutes. Extracellular Ca2+-induced currents displayed a moderate dependency on guanosine triphosphate (GTP). All blockers for phospholipase C, diacylglycerol (DAG) lipase, monoacylglycerol (MAG) lipase and lipoxygenase inhibited extracellular Ca2+-induced current. IP3 dialysis failed to induce conductance increase, but 2-arachidonoylglycerol (2-AG), arachidonic acid and 12S-hydroperoxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12(S)-HPETE) dialysis increased the conductance identical to extracellular Ca2+-induced conductance. These results indicate that high extracellular Ca2+ raises intracellular Ca2+ concentration through the DAG lipase/lipoxygenase pathway, resulting in the activation of Cl− conductance

Interaction between gustatory depolarizing receptor potential and efferent-induced slow depolarizing synaptic potential in frog taste cell.

Electrical stimulation of parasympathetic nerve (PSN) efferent fibers in the glossopharyngeal nerve induced a slow depolarizing synaptic potential (DSP) in frog taste cells under hypoxia. The objective of this study is to examine the interaction between a gustatory depolarizing receptor potential (GDRP) and a slow DSP. The amplitude of slow DSP added to a tastant-induced GDRP of 10 mV was suppressed to 60% of control slow DSPs for NaCl and acetic acid stimulations, but to 20-30% for quinine-HCl (Q-HCl) and sucrose stimulations. On the other hand, when a GDRP was induced during a prolonged slow DSP, the amplitude of GDRPs induced by 1 M NaCl and 1 M sucrose was suppressed to 50% of controls, but that by 1 mM acetic acid and 10 mM Q-HCl unchanged. It is concluded that the interaction between GDRPs and efferent-induced slow DSPs in frog taste cells under hypoxia derives from the crosstalk between a gustatory receptor current across the receptive membrane and a slow depolarizing synaptic current across the proximal subsynaptic membrane of taste cells

Softening of Co-base Amorphous Alloys at High Temperatures

The change of elongation of Co-Si-B amorphous alloys at a continuous heating rate has been investigated in order to search the best condition for hot working. In the case of Co_Si_B_x and Co_Si_B_x amorphous alloys, Co_Si_B_ was found to be the most suitable alloy composition for hot working. The degree of softening at high temperature, α_2, remarkably increased with increase in the Fe content. The value of α_2 of Co_Fe_5Si_B_ amorphous alloy was one and a half times as large as that of Co_Si_B_ amorphous alloy. The dramatic change in elongation due to softening at high temperatures is caused by viscous flow

Effect of gap junction blocker beta-glycyrrhetinic acid on taste disk cells in frog.

A gap junction blocker, 18beta-glycyrrhetinic acid (beta-GA), increased the membrane resistance of Ia, Ib and II/III cells of frog taste disk by 50, 160, and 300 M Omega, respectively, by blocking the gap junction channels and hemichannels. The amplitudes of gustatory depolarizing potentials in the disk cells for 4 basic taste stimuli were reduced to 40-60% after intravenous injection of beta-GA at 1.0 mg/kg. beta-GA of 1.0 mg/kg did not affect the resting potentials and the reversal potentials for tastant-induced depolarizing potentials in any taste disk cells. The percentage of cells responding to each of 4 basic taste stimuli and varying numbers of 4 taste qualities did not differ between control and beta-GA-treated taste disk cells. This implies that gustatory depolarizing response profiles for 4 basic taste stimuli were very similar in control and beta-GA-treated taste disk cells. It is concluded that beta-GA at 1.0 mg/kg reduced the amplitude of gustatory depolarizing potentials in taste disk cells by strongly blocking depolarizing currents flowing through the gap junction channels and hemichannels, but probably weakly affected the gustatory transduction mechanisms for 4 taste stimuli

Static Consolidation of Co-base Amorphous Alloy Powders and Their Mechanical and Magnetic Properties

Amorphous Co_Si_B_ alloy powders which show a remarkable softening between T_g and T_x and a wide temperature range, ΔT(T_x-Tg=59 K), were subjected to consolidation in a vacuum with a hot press apparatus. Amorphous alloy bulk which has 5 mm in diameter, 1.7 mm in height and 96% in compaction degree was obtained at the optimum temperature and pressure. This alloy bulk exhibited a compression strength as high as 1.38 GPa. It was confirmed that a higher pressure was merely effective to densificate the compact but that a proper temperature for softening of powders as well as pressure was required to perform denser and stronger consolidation. Magnetic properties of the amorphous alloy bulk obtained were compared with those of the dynamic alloy compacted bulk. Soft magnetic properties of the hot-pressed compact was superior to those of the dynamical compact before heat-treatments. However, those properties of dynamical compact was improved by annealing, while those of the hot-pressed one were entirely insensitive to annealing treatments