Kousuke Hagisawa

A novel method to prevent secondary exposure of medical and rescue personnel to toxic materials under biochemical hazard conditions using microwave radar and infrared thermography

In order to prevent secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, we performed a noncontact determination of exposure to toxic conditions via 1215-MHz microwave radar and thermography. A toxic condition was induced by intravenous administration of lipopolysaccharide (LPS) in rabbits. The exposure to LPS was determined by linear discriminant analysis using noncontact derived variables.

Development of a continuous temperature mapping system using a deep body thermometer

To determine continuous body temperature distribution, an inexpensive temperature mapping system was developed using a deep body thermometer adopting the finite-element method. A stripe with 16 thermocouples was wrapped around the waist of rats to measure body surface temperatures (the boundary conditions). The abdominal deep temperature of the rats was measured from the dorsum using the thermal compensation probe of a deep body thermometer. The abdominal temperature of the rats was mapped by solving a heat conduction equation using surface and deep temperatures obtained in real time. The temperature measured with a thermocouple inserted into the abdominal centre of the rats correlated well with the calculated temperature ( r = 0.93, p < 0.01 ). The system is low cost and simple to use compared with the magnetic resonance temperature mapping system. Our temperature mapping system could potentially result in improved management of patients in critical care medicine.

A novel ferromagnetic thermo-stent for plaque stabilization that self-regulates the temperature

The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization.

Determining the temperature distribution of swine aorta with simulated atheromatous plaque under pulsed laser irradiation: an experimental attempt to detect the vulnerability of atherosclerosis.

We developed a method to determine the temperature distribution of swine aortas with simulated atheromatous plaques in order to measure the temperature of atherosclerotic lesions. The inflammation associated with temperature elevation is considered to be one of the aggravating mechanisms of atherosclerosis resulting in fissuring or rupture of atheromatous plaques. The temperature distribution of plaques covered by fibrous caps cannot be measured by conventional thermistors. Indocyanine green (ICG) solution was injected into the subintima of swine aorta to simulate the light absorption coefficient of human atheromatous plaques. The temperature distribution was calculated from measured temperature changes of the aortic intima under pulsed laser irradiation. The aorta was heated from the adventitial side with a halogen lamp to simulate the temperature elevation derived from inflammation. The temperature distribution of the aorta was obtained by solving the heat transfer equation using the surface layer thickness (corresponding to the fibrous cap thickness). The surface layer thickness can be calculated using the following working formula: D( µm)=1363-398 – T +35 – T 2, where s s – T s denotes intimal surface temperature change under pulsed laser irradiation. The calculated temperature of the ICG layer (corresponding to the atheromatous core) correlated well with the measured temperature (r=0.97, p<0.0001).We developed a method to determine the temperature distribution of swine aortas with simulated atheromatous plaques in order to measure the temperature of atherosclerotic lesions. The inflammation associated with temperature elevation is considered to be one of the aggravating mechanisms of atherosclerosis resulting in fissuring or rupture of atheromatous plaques. The temperature distribution of plaques covered by fibrous caps cannot be measured by conventional thermistors. Indocyanine green (ICG) solution was injected into the subintima of swine aorta to simulate the light absorption coefficient of human atheromatous plaques. The temperature distribution was calculated from measured temperature changes of the aortic intima under pulsed laser irradiation. The aorta was heated from the adventitial side with a halogen lamp to simulate the temperature elevation derived from inflammation. The temperature distribution of the aorta was obtained by solving the heat transfer equation using the surface layer thickness (corresponding to the fibrous cap thickness). The surface layer thickness can be calculated using the following working formula: D(microm)=1363-398DeltaTs+35DeltaTs(2), where AT, denotes intimal surface temperature change under pulsed laser irradiation. The calculated temperature of the ICG layer (corresponding to the atheromatous core) correlated well with the measured temperature (r=0. 97, p<0.0001).

Significance of angioscopic morphology for the estimation of macrophage infiltration and vascular physiology.

Objective: The aim of the present study was to determine whether direct visual morphology can predict vascular physiology, macrophage infiltration and plaque architecture of atherosclerotic lesions. Methods: Twenty male New Zealand white rabbits weighing 2.5–2.8 kg (mean, 2.7 ± 0.2 kg) were used. We fed rabbits a 1% cholesterol diet after creating an injury in the middle abdominal aorta using a 2 Fr Fogarty balloon catheter. After 8 weeks, the morphology of plaque lesions was evaluated by angioscopy, and was classified as protruding or lining. Vascular endothelial function (VEF) was evaluated using a Doppler guidewire, and was expressed as ratio of basal to peak velocity (cm/s) in 30 s occlusion using a balloon catheter. Macrophages obtained from abdominal sections were stained with monoclonal antibody against rabbit macrophages (RAM-11). Density of total macrophage cell infiltration was quantified as absolute area of RAM-11 staining. Results: Macrophage density and intima/media (I/M) ratio were significantly higher in the protruding group than in the lining group: macrophage density, 40 ± 10 vs. 5 ± 10%, p < 0.01; I/M ratio, 1.2 ± 1.4 vs. 0.2 ± 4, p < 0.05. Vascular flow reserve (VFR) was lower in the protruding group than in the lining group (1.8 ± 0.7 vs. 2.2 ± 0.5, p < 0.05). There was significant negative correlation between VEF and macrophage cell density (r=−0.593, p < 0.01), whereas there was no significant correlation between VEF and I/M ratio (r=−0.332, p= 0.330). Conclusion: The present findings suggest that protruding lesions revealed by angioscopy are rich in macrophages and have a higher I/M ratio and lower VFR.