Effects of glucagon on superior mesenteric artery and femoral artery haemodynamics in humans

OBJECTIVE: It remains unclear whether glucagon is a localized splanchnic arterial vasodilator in humans. This study examined this issue by assessing the haemodynamic effect of exogenous glucagon on splanchnic and extrasplanchnic arteries. METHODS: After an overnight fast, flow velocity of superior mesenteric artery and femoral artery was recorded by means of echo-Doppler in 10 controls and 10 patients with cirrhosis. Mean arterial pressure, heart rate and plasma glucagon level were also determined. These measurements were repeated after intramuscular injection of glucagon (1 mg) at 15 min and 30 min. RESULTS: Patients with cirrhosis had much higher glucagon levels than controls (P < 0.01). Plasma glucagon level rose following glucagon administration in controls (P < 0.01) and patients with cirrhosis (P < 0.01). Glucagon administration had no effect on mean arterial pressure, heart rate and femoral artery velocity in controls and patients with cirrhosis. In contrast, superior mesenteric artery velocity significantly increased after glucagon administration in both groups (P < 0.01, P < 0.01), although the effect was less pronounced in patients with cirrhosis than in controls (P < 0.05). CONCLUSION: These data suggest that glucagon might be a localized splanchnic arterial vasodilator. Thus, glucagon may be one of the factors contributing to the pathogenesis of the splanchnic hyperdynamic circulation seen in patients with cirrhosis.     

Decentralized system identification for electric power system

Research on decentralized control of an electric power system is important for stabilizing control problems. In particular, since an electric power system is a large-scale nonlinear control system, decentralized (not divided) systems with cooperation should be constructed. This paper presents ways to construct decentralized systems for an electric power system. In section 2, swing data of a three-machine model system are obtained, in section 3, coefficient parameters of the model equation based on one-machine infinite-bus system with AVR and GOV are estimated by the least square method. In section 4, the equivalence calculated using estimated values is discussed, and the effect of conditions on fault is considered. Finally, section 5 is devoted to summarizing results of decentralized system identification.     

Effects of an AT1 receptor antagonist, an ACE inhibitor and a calcium channel antagonist on cardiac gene expressions in hypertensive rats

1. This study was undertaken to determine whether the AT1 receptor directly contributes to hypertension-induced cardiac hypertrophy and gene expressions. 2. Stroke-prone spontaneously hypertensive rats (SHRSP) were given orally an AT1, receptor antagonist (losartan, 30 mg kg-1 day-1), an angiotensin converting enzyme inhibitor (enalapril 10 mg kg-1 day-1), a dihydropyridine calcium channel antagonist (amlodipine, 5 mg kg-1 day-1), or vehicle (control), for 8 weeks (from 16 to 24 weeks of age). The effects of each drug were compared on ventricular weight and mRNA levels for myocardial phenotype- and fibrosis-related genes. 3. Left ventricular hypertrophy of SHRSP was accompanied by the increase in mRNA levels for two foetal phenotypes of contractile proteins (skeletal alpha-actin and beta-myosin heavy chain (beta-MHC)), atrial natriuretic polypeptide (ANP), transforming growth factor-beta-1 (TGF-beta 1) and collagen, and a decrease in mRNA levels for an adult phenotype of contractile protein (alpha-MHC). Thus, the left ventricle of SHRSP was characterized by myocardial transition from an adult to a foetal phenotype and interstitial fibrosis at the molecular level. 4. Although losartan, enalapril and amlodipine lowered blood pressure of SHRSP to a comparable degree throughout the treatment, losartan caused regression of left ventricular hypertrophy of SHRSP to a greater extent than amlodipine (P < 0.01). 5. Losartan significantly decreased mRNA levels for skeletal alpha-actin, ANP, TGF-beta 1 and collagen types I, III and IV and increased alpha-MHC mRNA in the left ventricle of SHRSP. Amlodipine did not alter left ventricular ANP, alpha-MHC and collagen types I and IV mRNA levels of SHRSP. 6. The effects of enalapril on left ventricular hypertrophy and gene expressions of SHRSP were similar to those of losartan, except for the lack of inhibition of collagen type I expression by enalapril. 7. Unlike the hypertrophied left ventricle, there was no significant difference between losartan and amlodipine in the effects on non-hypertrophied right ventricular gene expressions of SHRSP. 8. Our results show that hypertension causes not only left ventricular hypertrophy but also molecular transition of myocardium to a foetal phenotype and interstitial fibrosis-related molecular changes. These hypertension-induced left ventricular molecular changes may be at least in part mediated by the direct action of local angiotensin II via the AT1, receptor.     

Rapid expression and specific localization of tenascin in gastric ulcer healing in rats

This study was done to investigate the gene expression and localization of tenascin in ulcerated gastric tissues during the healing process with Northern blot analysis and immunohistochemical technique. Gastric ulcers in rats were produced by acetic acid. Tenascin mRNA levels in the ulcerated tissue were significantly increased in a biphasic manner (12 h and day 5), preceding the increase in collagen type IV and laminin mRNA levels, and returned to control levels on day 11. In intact tissues, tenascin was mainly localized in the basement membrane above the proliferative zone, in contrast to the predominant localization of collagen type IV and laminin below the proliferative zone. On the ulcer margin from 12 h to day 5, tenascin was abundantly observed in the lamina propria around nonproliferating new epithelial cells, but collagen type IV and laminin were not seen in this lamina propria. On day 7, tenascin, expressed in the lamina propria, was replaced by collagen type IV and laminin. Thus, the rapid expression and unique localization of tenascin suggest the important role of tenascin in gastric ulcer healing.     

Mechanical strength of fusion-spliced optical fibres

Mechanical strengths of optical fibres heated under different electric-discharge conditions have been systematically examined. Exclusion of fibre surface contaminations and making heating duration as short as possible are important for prevention of strength deterioration.     

A flexible OLED display with an OTFT backplane made by scalable manufacturing process

Abstract— A full‐color top‐emission AMOLED display driven by an organic TFT backplane manufactured using a scalable, lift‐off‐free, and shadow‐mask‐free process has been developed. It was shown that cost‐efficient copper can be used for S/D electrodes. The display has shown no significant degradation over a storage life of more than 10 months and operation over 25 hours during which the display is bent over 10,000 times.     

Synthesis and optical properties of europium doped zinc silicate prepared using low cost solid state reaction method

This paper presents a study on synthesis and optical properties of Zn₂SiO₄:1 wt% Eu³⁺ at different heat treatments. The objective of the research is to synthesize Zn₂SiO₄:1 wt% Eu³⁺ phosphor by using low cost solid state reaction method with recycled waste bottle glasses as the silicate source. The X-ray diffraction results showed that the prepared Zn₂SiO₄:1 wt% Eu³⁺ phosphors have a sharp diffraction peak as the heat treatment temperatures were increased from 600 to 1000 °C. Furthermore, the morphology from the Field emission scanning electron microscope analysis were shown the formation of well crystalline samples with dense packed grains due to the increment of heat treatment temperatures. Fourier transform infrared spectra has confirmed the present elements in Zn₂SiO₄:1 wt% Eu³⁺ phosphors while the narrow width of Raman line spectra were observed at temperatures ranging from 700 to 1000 °C indicates good homogeneity and crystallinity of synthesized powders. In addition, the energy band gap of europium doped zinc silicate increased dramatically up to 3.62 eV at temperature of 1000 °C. Photoluminescence measurements has also exhibited the red emission corresponding to the ⁵D₀ → ⁷F₂ (600 nm) when viewed under blue excitation.     

Flow characteristics of plunging flows in steep sloping channels with a horizontal channel portion

This paper presents the effect of an aerated inflow on flow conditions of a plunging flow region in steep sloping channels (30 and 55°) with a horizontal channel portion. The flow condition of the plunging flow region and the reverse flow length are affected by the depth averaged air-concentration ratio of the aerated inflow. For a fully aerated inflow with a large downstream depth, a high velocity jet decays in a short distance, and a hydraulic jump is formed on the sloping channel portion. However, for a non-aerated inflow with a large downstream depth, a high velocity jet continues far downstream as a wall jet. The effect of aerated inflow on the velocity field in the plunging flow region has been shown.