Publications (30) View all
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Article: Does the augmentation index of pulse waves truly increase with progression of atherosclerosis? An experimental study with hypercholesterolemic rabbits.
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ABSTRACT: BACKGROUND Recently, the central augmentation index (AIx) has been reported to show a nonlinear correlation with age. We investigated whether the AIx of the central artery changes with the progression of atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits. METHODS We simultaneously recorded pressure and flow waves in the ascending aorta in normal and KHC rabbits aged 10-12, 22-24, and 34-36 months, under pentobarbital anesthesia. RESULTS The systolic, diastolic, and mean arterial pressures and total peripheral vascular resistance were significantly higher in KHC rabbits than in their age-matched controls. The systolic pressure of the KHC rabbits increased with age. Additionally, the AIx of the KHC rabbits was significantly higher than that of their age-matched controls, although the AIx did not show a significant age-dependent increase in either of the two rabbit groups. However, the development of atherosclerotic lesions progressed markedly in KHC rabbits, and the early and late (pulse pressure [PP]) systolic waves increased progressively in amplitude with age in the KHC rabbits. On the other hand, no significant differences were seen in the normal and KHC rabbits' cardiac output (CO), stroke volume (SV), or heart rate (HR) at any age, nor did the two strains show significant age-related changes in these variables. Aortic compliance (SV/PP) was significantly lower in the 22-24- and 34-36-month-old KHC rabbits than in their age-matched controls, and decreased with age in the KHC rabbits. CONCLUSIONS Although the progression of atherosclerosis stiffened the aortic wall, it did not affect the AIx. This was partly the result of the decreased distensibility of the wall, in which the pressure waves used to determine AIx were measured.American Journal of Hypertension 03/2013; 26(3):311-7. · 3.18 Impact Factor -
Article: Differences in rates of decrease of environmental radiation dose rates by ground surface property in fukushima city after the fukushima daiichi nuclear power plant accident.
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ABSTRACT: After the Great East Japan Earthquake on 11 March 2011, the environmental radiation dose in Fukushima City increased. On 11 April, 1 mo after the earthquake, the environmental radiation dose rate at various surfaces in the same area differed greatly by surface property. Environmental radiation measurements continue in order to determine the estimated time to 50% reduction in environmental radiation dose rates by surface property in order to make suggestions for decontamination in Fukushima. The measurements were carried out from 11 April to 11 November 2011. Forty-eight (48) measurement points were selected, including four kinds of ground surface properties: grass (13), soil (5), artificial turf (7), and asphalt (23). Environmental radiation dose rate was measured at heights of 100 cm above the ground surface. Time to 50% reduction of environmental radiation dose rates was estimated for each ground surface property. Radiation dose rates on 11 November had decreased significantly compared with those on 11 April for all surface properties. Artificial turf showed the longest time to 50% reduction (544.32 d, standard error: 96.86), and soil showed the shortest (213.20 d, standard error: 35.88). The authors found the environmental radiation dose rate on artificial materials to have a longer 50% reduction time than that on natural materials. These results contribute to determining an order of priority for decontamination after nuclear disasters.Health physics 01/2013; 104(1):102-7. · 0.92 Impact Factor -
Article: Reducing radiation exposure using commonly available objects.
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ABSTRACT: OBJECTIVES: One and a half years have passed since the Fukushima Daiichi nuclear power plant disaster. The environmental radiation dose rate was not critical, but an existing exposure situation has been identified in a large part of Fukushima Prefecture. Although people continue to live and work in the contaminated area, they are not provided with sufficient information to reduce their exposure to radiation by themselves. In this study, we attempt to evaluate the efficiency of radiation shielding by using everyday items widely available to people. METHODS: NaI scintillation and Geiger-Müller survey meters were used to measure the radiation dose of (1) contaminated soil and (2) soil covered with commonly available items. RESULTS: In the soil at a depth of 10 cm from the surface, the radiation dose rate decreased from 3.36 to 0.65 μSv/h, and the count rate decreased from 3,120 to 352 cpm. Both the radiation dose rate and count rate reduced when the soil was covered with everyday items, such as a magazine more than 20 mm thick, a polystyrene foam board, and a wooden board of the same thickness. CONCLUSIONS: To protect residents from unnecessary radiation exposure in the existing exposure situation, covering contaminated soil with a wooden board or a magazine, either of them 20 mm thick, is useful to reduce the radiation dose.Environmental Health and Preventive Medicine 11/2012; -
Article: Aquaporin AqpZ is Involved in Cell Volume Regulation and Sensitivity to Osmotic Stress in Synechocystis sp. PCC 6803.
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ABSTRACT: The moderately halotolerant cyanobacterium Synechocystis sp. PCC 6803 contains a plasma membrane aquaporin, AqpZ. We previously reported that AqpZ plays a role in glucose metabolism under photomixotrophic growth conditions, suggesting involvement of AqpZ in cytosolic osmolarity homeostasis. To further elucidate the physiological role of AqpZ, we have studied its gene expression profile and its function in Synechocystis. The expression level of aqpZ was regulated by the circadian clock. AqpZ activity was insensitive to mercury in Xenopus oocytes and in Synechocystis, indicating that the AqpZ can be categorized as a mercury-insensitive aquaporin. Stopped-flow light-scattering spectrophotometry showed that addition of sorbitol and NaCl led to a slower decrease in cell volume of the Synechocystis ΔaqpZ strain compared to the wild type. The ΔaqpZ cells were more tolerant to hyperosmotic shock by sorbitol than the wild type. Consistent with this, recovery of oxygen evolution after a hyperosmotic shock by sorbitol was faster in the ΔaqpZ strain than in the wild type. In contrast, NaCl stress had only a small effect on oxygen evolution. The amount of AqpZ protein remained unchanged by the addition of sorbitol, but decreased after addition of NaCl. This decrease is likely to be a mechanism to alleviate the effects of high salinity on the cells. Our results indicate that Synechocystis AqpZ functions as a water transport system that responds to daily oscillations of intracellular osmolarity.Journal of bacteriology 10/2012; · 3.94 Impact Factor -
Article: Improved Islet Yield and Function by Use of a Chloride Channel Blocker During Collagenase Digestion
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ABSTRACT: Background. Protection of pancreatic islets during isolation procedures is mandatory for successful islet transplantation. Chloride channel inhibition has been reported to prevent cell death induced by various stimuli. We examined the effects of the chloride channel blocker, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid disodium salt (DIDS) and extracellular Cl−-free conditions on islet isolation outcomes. Methods. Experimental groups were created based on the collagenase solutions used for Wistar rat islet isolation: control group, Hanks' balanced salt solution; DIDS group, 200 μM DIDS; and Cl−-free group, sodium gluconate substituted for sodium chloride. We determined whether collagenase digestion induced the death of islet cells through Cl− influx into the cells. We then assessed islet yield and the viability of isolated islets. Results. We observed an increase in intracellular Cl− concentration under collagenase digestion conditions using a Cl−-sensitive fluorescent dye and subsequent rupture of islet cells. Consequently, islet yields were significantly higher in the DIDS and Cl−-free groups than in the control group, and islet morphology of the former groups was preserved. Of streptozotocin-induced diabetic severe combined immunodeficiency mice transplanted with a marginal dose of islets, all seven mice in the DIDS group and six of the seven mice in the Cl−-free group became normoglycemic, compared with two of seven mice in the control group (control vs. DIDS, P=0.010; control vs. Cl− free, P=0.051). Conclusion. Our results indicate that DIDS inhibition of Cl− influx into islets protects islets during digestion procedures, offering a new strategy for the improvement of islet isolation outcomes.Transplantation 10/2011; 92(8):871-877. · 4.00 Impact Factor
