Hiroshi Yagi

Lipoxygenase inhibition decreases neointimal formation following vascular injury.

Our aim was to assess the potential role of lipoxygenase (LO) products in neointimal formation following vascular injury. We investigated the effect of LO pathway inhibition, by phenidone, on the concentration of 12- and 5-hydroxyeicosatetraenoic acid (12- and 5-HETE) in rat whole blood and in aortic tissue. We also examined the effect of phenidone on myoneointimal formation in balloon-injured rat carotid arteries. Phenidone significantly decreases the concentration of HETEs in aortic tissue, and decreases neointimal size even though there is no difference in the BrdU index. These data indicate that the LO product participates in developing neointima following balloon-induced vascular injury, and that the LO blocker phenidone decreases neointimal size possibly by suppressing migration of smooth muscle cells.

Localized right ventricular structural abnormalities in patients with idiopathic ventricular fibrillation: magnetic resonance imaging study.

SummaryLethal arrhythmias, including ventricular tachycardia and ventricular fibrillation, may occur in the absence of apparent morphological abnormalities. However, a recent study using magnetic resonance imaging (MRI) has suggested that localized, minor structural abnormalities of the right ventricle are responsible for right ventricular outflow tract ventricular tachycardia in a number of patients. We demonstrated regional wall thinning and systolic dyskinesia of the right ventricle by MRI in two patients with idiopathic ventricular fibrillation in whom other cardiac imaging modalities failed to show abnormalities. This finding implies that minor structural abnormalities do exist in patients with so-called idiopathic ventricular fibrillation.

Field measurement and modeling of near-bed sediment transport processes with fluid mud layer in Tokyo Bay

Tokyo Bay is one of the estuaries in Japan with a high population of almost 26 million people in the basin area. One of the major concerns for the environment in this water area is the decreasing ecosystem functions including the deterioration of water and sediment qualities caused by various anthropogenic activities. Since the bottom sediments around almost the entire area of the inner bay consist of fine materials with a high organic content, which cause the deterioration of water quality through processes such as hypoxia, an understanding of the fine sediment dynamics in the Bay is crucial for an environmental assessment of the water area. This paper proposes a model for the key processes of fine sediment dynamics, which reflects field data about muddy bed structures and their dynamics obtained during the monitoring campaign in 2007. One of the specific features of the sediment in the Bay at present is the persistent existence of fluid mud layers (water content over 300xa0%) with a thickness of around a few decimeters, which might be caused by deposition of abundant organic particles due to eutrophication. The present study shows that diffusion flux model delivers quite reliable results for estimating erosion flux from the top of fluid mud layers after calibrating the model parameter against the time series data of vertical flux measured by an acoustic Doppler velocimeter system. This study also derives analytical solutions, based on the Bingham fluid concept, of advection flux in the fluid mud layer on which external shear stress force is applied.

Bottom Turbidity, Boundary Layer Dynamics, and Associated Transport of Suspended Particulate Materials off the Fukushima Coast

Long-term monitoring and intensive field experiments for the bottom layer off the Fukushima coast were performed from October 2012 to November 2014 to understand the bottom processes, which are closely related to the spatial distribution and temporal variations of radiocesium in sea sediment. In this section, focusing on autumn 2012, we examine the bottom processes for a 32-m depth site (Sta. B) off Iwaki, Fukushima. Observational results showed that the bottom shear stresses from waves generally dominated over those from currents in this depth region, and the bottom turbidity increased in high wave conditions. Stepwise and significant southward cumulative transports of bottom turbidity were observed when high waves with long periods (LPW) coming from an E–ENE direction were superimposed on the southward current flow that has a periodicity of 5 days; both phenomena are influenced by successive passages of low pressure systems and the associated spatial distribution of atmospheric pressure. The combination of waves and currents caused by meteorological disturbance is a key process in the transport of suspended particulate material off the Fukushima coast.

Quantifying the Fate of Captured Carbon: From Seagrass Meadows to the Deep Sea

To help evaluate the sequestration and carbon dioxide storage function of seagrass meadows, we describe the processes by which carbon is sequestered in eelgrass beds and transported from shallow coastal waters to the deep sea. A part of the carbon taken up by eelgrass is decomposed and returned to biological production or the water column’s dissolved inorganic carbon pool, some is accumulated and stored in the shallow sea bottom, and the rest flows out into the deep sea. Here, we describe the growth of eelgrasses and the processes of decomposition, sedimentation, and transportation of eelgrass-derived organic carbon using the Seto Inland Sea as a model site. We estimated the amount of carbon sequestered and stored in eelgrass beds, the fate of eelgrass-derived organic carbon, and the amounts accumulated in the shallow coastal water and transported to the deep sea. According to our estimates based on calculations from tracking carbon over a 1-year period, of the 73,000 tons of carbon sequestered by eelgrass annually in the Seto Inland Sea, 40.9% is accumulated in the Seto Inland Sea and 8.3% flows out to the deep sea. In other words, the eelgrass beds in the Seto Inland Sea have an annual potential capacity of 36,000 tons of carbon storage. In addition, most of the organic carbon was accumulated in the shallow coastal waters rather than in the deep sea.

A Study of Damage Mechanism on Fishery Port Facilities at Taro Fishery Port due to TOHOKU Earthquake Tsunami

In order to investigate the damage mechanism on fishery port facilities at Taro fishery port, field surveys were conducted and stabilities of the facility bodies was examined using the tsunami simulation modeled with flooding. The east and south breakwaters were found to be collapsed inward of the port, wave-dissipating blocks were found scattered in all directions and the breakwater substructions were also destroyed. The modeled results were verified with the flood areas as well as with the height of the watermarks. The results revealed that the height of the watermarks could not be reproduced without the facility collapses in the model. The stability analysis of structures was consistent with the survey results well, in which the east, south and west breakwaters collapsed while the offshore breakwater was intact.

Long-term Prognosis for Non-ischemic Heart Disease Patients with Premature Ventricular Contraction and Non-sustained Ventricular Tachycardia

There are few long‐term reports of patients with frequent PVCs in the absence of ischemic heart disease. In 86 patients without ischemic heart disease, who had 1000 or more PVCs in 24‐hour Holter ECG, the number of PVCs during 24‐hours Holter ECG and echocardiographic parameters were followed at least 1 year (66.5 ± 39.7 months). PVC was significantly reduced in the patients with or without underlying diseases (UD). The reduction rate in the number of PVCs was prominent in patients with UD. PVC was significantly reduced in patients under medication, but not in patients without medication. In the comparison between the initial and follow up observation using Wilcoxons rank test, the number of PVC was significantly reduced (P < 0.05), and EF was also improved (P < 0.05) in angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) group, and in β‐blocker group. In Ca‐antagonist group and antiarrhythmic drug group, the number of PVCs was also significantly reduced (P < 0.05). Multivariate analysis revealed significantly higher incidence (60% or more with PVC reduction) in ACEI/ARB group.

Field Observations of Sedimentary Characteristics of Muddy Sediment around Tama River Mouth

Field observations were carried out to investigate sedimentary characteristics at the estuarine area of Tama river, where a national project for future extension of Haneda international airport is undergoing.The survey includes sediment core samplings and acoustic sub-bottom profilings of the site.Based on the analysis of the core samples, spatial distribution of thickness of fluid mud layer has been obtained and it develops to the off shore from mouth of the river. Acoustic images have clearly shown the difference of the sedimentary structures between shallower monitoring point inside the river and offshore point with higher mud content.The images were evaluated by comparison with analysis data, such as water content, of bottom sediment samples.

Basic Autonomic Nervous Function in Patients with Neurocardiogenic Syncope

Basic autonomic nervous function was evaluated in patients with neurocardiogenic syncope (NCS). Atropine, isoproterenol, propranolol, phenylephrine, and phentolamine were administered successively, and parasympathetic nerve activity and β- (and α-) activity, sensitivity, and secretion of the sympathetic nerve were determined in patients with NCS and control subjects. In patients with NCS, β- and α- sensitivity were higher and β-activity and β- and α-secretion lower than in control subjects. In patients with NCS, the increased basic β-sensitivity may contribute to induce strong cardiac contractions and augment ventricular mechanoreceptor response, and a compensatory state against diminished neuronal sympathetic activity is suggested by the increased α-sensitivity.