ラット ニオケル カルシウム フカカ ノ ノルエピネフリン ニヨル キュウセイ サシツ カクチョウ ショウガイ : サシツ ケッコウ ドウタイ ナラビニ シンゾウ チョウオンパホウ ニヨル ケントウ

拡張不全は左室収縮の低下を伴わない心不全で,左室収縮の低下による収縮不全とは病態,基礎疾患,予後が異なることが明らかにされつつある.しかし,その発生メカニズムについては十分に解明されていない.本研究では雄性ラット42匹を用い,対照群,塩化カルシウム投与群,ノルエピネフリン投与群,塩化カルシウム投与後,塩化カルシウム+ノルエピネフリン投与群において,左室血行動態,左室拡張障害について検討をおこなった.4群でチップ付き圧カテーテルを左室内へ挿入し,また別の4群で心臓超音波法により左室駆出率を測定した.さらに別に拡張早期急速流人期血流速波形(E波),拡張後期流人速波形(A波),E波減速時間(DCT),組織ドプラ法で拡張早期僧帽弁輪速度(Ea波)を測定した.その結果,塩化カルシウム群,ノルエピネフリン群では左室拡張末期圧は変化を認めなかったが,塩化カルシウム+ノルエピネフリン投与群で左室拡張末期圧は著しい上昇を認めた.また,塩化カルシウム+ノルエピネフリン群では左室駆出率は対照群と有意差を認めなかったが,E波,DCT,Ea波は対照群に比し有意な減少を認めた.以上より,塩化カルシウム負荷下でのノルエピネフリン投与で急激な心臓拡張障害が惹起され,心臓の拡張障害の発生にノルエピネフリンが関与している可能性が示唆された.In diastolic dysfunction, cardiac cells in the diastolic phase do not rapidly or completely return to the normal state of relaxation. However, the detailed mechanism remains unknown. To develop an acute diastolic dysfunction model in the rat, norepinephrine (30μg/kg/min) with calcium (12mg/kg/min) was administered for 20 minutes, following 20-minute administration of calcium, compared with the control group. A cardiovascular mikro-tip pressure transducer catheter was inserted into the left ventricle, and the intraventricular pressure and left ventricular end-diastolic pressure were determined. Early diastolic mitral annular velocity (Ea), E and A waves, deceleration time (DCT) and left ventricular ejection fraction were estimated using tissue Doppler imaging and echocardiography. In the norepinephrine with calcium group, no significant change in left ventricular pressure was found, but left ventricular end-diastolic pressure was markedly increased. On echocardiography, no change was found in left ventricular ejection fraction, but the E wave, DCT and Ea wave were decreased, in comparison with the control, calcium alone and norepinephrine alone groups. The results of this study could indicate that norepinephrine administration with calcium causes acute diastolic dysfunction in the rat

Quantitative analysis of defective sites in titanium(IV) oxide photocatalyst powders

The molar amounts of defective sites (Md) in several titanium(IV) oxide (TiO2) powders were determined using photoinduced reactions of electron accumulation in deaerated aqueous solutions containing sacrificial hole scavengers and subsequent reduction of methylviologen to its cation radical. Measurements of pH dependence of typical anatase and rutile TiO2 powders showed that these defective sites were of electronic energy just below the conduction band edge of TiO2 in ranges of 0–0.35 V for anatase and 0–0.25 V for rutile. A linear relation of Md with the rate constant of electron-hole recombination determined by femtosecond pump-probe diffuse reflection spectroscopy revealed that Md could be a quantitative parameter of recombination between a photoexcited electron and a positive hole. The fact that there was no linear relation between Md and the specific surface area suggests that the surface area was not directly reflected on Md. A reciprocal correlation between photocatalytic activity for water oxidation in aqueous silver sulfate solution and Md revealed that the rate of recombination is one of the predominant physical properties governing the activities of TiO2 powders in this reaction system

Surface hydrogen effects on Ge surface segregation during silicon gas source molecular beam epitaxy

Using reflection-high-energy-electron diffraction (RHEED), the temperature dependence of Ge surface segregation during silicon gas source molecular beam epitaxy (Si-GSMBE) from hydride sources was studied, and it was found that surface hydrogen, which is produced by the dissociation of Si2H6 and GeH4 on the growing surface, may act as a growth-controlling surfactant. Comparison with results from solid source growth results suggests that hydrogen significantly suppresses the Ge segregation. Segregation kinetics were examined through simulation studies and the results indicate that the addition of surface hydrogen to the system inhibits segregation due to a lowering of the Gibbs heat of segregation.link_to_subscribed_fulltex

The laser radar system for measurement of the middle atmosphere at Syowa Station in Antarctica

Multiwavelength laser radar system was installed at Syowa Station in 1983 by the 24th Japanese Antarctic Research Expedition for measurement of the middle atmospheric phenomena in cooperation with International Middle Atmosphere Program (MAP). The laser radar can simultaneously shoot two kinds of laser pulses (0.6943μm : the fundamental wave, 0.3471μm : the second harmonic wave) by means of ruby laser with regulated repetition frequencies (maximum : 1Hz) and receive scattered light by a telescope with the 50 cmφ-lens in efficient diameter. The measurement can be done by using a photon counter for each wave and A-scope for the fundamental wave. The test observation had been successfully made in Japan and it showed the remarkable increases of the strato-spheric aerosol due to the volcanic eruption of Mt. El Chichon. It was also inferred that the size distribution of the particles in the aerozol layer is inhomogeneous