Kiichi Tsuji

In vitro effects of diacerein on NO production by chondrocytes in response to proinflammatory mediators.

Recently, expired gases are analyzed non-invasively for monitoring the substances in the blood. Breath ammonia has been shown to correlate with BUN (blood urea nitrogen) and Cr (creatinine), both of which are indicators of solute removal in hemodialysis. In this study, breath ammonia concentration was continuously measured using a crystal oscillator QCM (quartz crystal microbalance) during the expiration of patients undergoing dialysis treatment. The results show that NH3 (ammonia) decreased gradually as the treatment proceeded. A strong correlation was observed between changes in the frequency of the QCM gas sensor and both the pre-dialysis BUN level (r = 0.71, p< 0.05) and the post-dialysis BUN level (r = 0.90, p< 0.05). NH3 was found to fall precipitously during dialysis. The differences were statistically significant. In addition, we found a statistically significant correlation between BUN and NH3 in expired gas. These results suggest that continuous measurement of NH3 is useful to assess the status of solute removal during hemodialysis.

Evaluation of blood access dysfunction based on a wavelet transform analysis of shunt murmurs.

We investigated shunt murmurs based on wavelet transform analysis as a new method for assessing vascular access function. In the present study, in patients with venous stenosis near an arteriovenous fistula (A-V fistula), a sensor was placed at different positions around the stenosis and shunt murmur signals obtained using a measurement system were subjected to time–frequency analysis based on wavelet transforms. The shunt murmurs obtained from the stenotic region closely represented some features of murmurs that are often referred to as “high-pitch” murmurs in the clinical setting. In contrast, shunt murmurs obtained about 5 cm downstream of the stenotic region closely represented some features of murmurs that are often referred to as “low-pitch” murmurs in the clinical setting. Furthermore, with the aim of extending the lifespan of arteriovenous grafts (A-V grafts) by detecting and treating stenotic lesions before the A-V graft becomes occluded, we evaluated the possibility of utilizing the present shunt murmur analysis for monitoring stenosis in such A-V grafts. When shunt murmurs from patients with A-V grafts were analyzed, the results suggested that the blood flow through the venous anastomosis of the graft was the most turbulent. This present method whereby blood flow in an A-V fistula is assessed based on the frequency distribution on a time–frequency plane by wavelet transform analysis is advantageous because findings are not markedly affected by sensor attachment. Furthermore, because the sensor is attached using an adhesive collar, measurements can be taken over a short period of time before each dialysis session.

Study on the effect of ultrasound condition upon suppression of cancer cells proliferation: Consideration of ultrasound exposure system with balloon

When an ultrasound wave is irradiated into water, active oxygen is generated together with a shock wave by a cavitation. We studied a method of cancer treatment using the cavitation and active oxygen generated by ultrasound exposure. In this study, an ultrasound exposure system using a balloon with an ultrasound horn was developed taking into clinical applications account. The cancer cells were induced apoptosis. Proliferation of cancer cells was suppressed by the developed ultrasound exposure system.

Phantom and Human Experiments for Breast Cancer Detection by Ultrasound Transmission Technique

A new technique named the ultrasound transmission technique has been proposed by the authors. The idea was developed from the clinical findings that sound velocity in breast cancer is higher than in normal tissue by 49-90 m/s. Phantom experiments were conducted. Plexiglas (PMMA) plates 3 mm, 2 mm, or 1 mm thick were put into a cubic container (86 × 86 × 86 mm) filled with degassed water. In the echogram, the apparent distance between the back wall of the container and transducer was shortened because of the higher velocity of sound waves in plexiglas (2700 m/s) than degassed water (1500 m/s). This result showed the validity of the method. A breast to be examined can be sandwiched between a planar ultrasound transducer and reflector plate. Similar experiments were performed using a slice of pork (42 mm thick) instead of degassed water. The shortening of the reflector was apparent. The forearm of a human volunteer was also examined with plexiglas 2mm or 1 mm thick with similar results, suggesting the validity of the method.

Basic experiments of elastograpy for breast cancer by water bag pressing for obtaining elastic modulus

Measurement of elastic modulus by water bag pressing is under development in our laboratories. Basic experiments were performed by pressing breast cancer phantom by water bag. The phantom is made of 10 weight percent gelatin of the thickness of 40mm, in which Plexiglas cylinder of the diameter of 10mm, mimicking the cancer, was placed in 10mm and 20mm depth from each surface. Phantoms was placed on the desk and pressed by a balloon filled with water with the pressure. The height of the vessel of water was adjusted to change the pressure in the balloon. Deformation of the phantom was detected by ultrasound echo technique. Ultrasound frequency was 11MHz. The gelatin phantom (density of 1.03) was deformed around Plexiglas cylinder by water pressure of 1.1 to 2.4kPa. Apparent differences of gelatin surface deformation depending on different water pressure was confirmed from echogram thus obtained. The experimental results were simulated by computer using Finite Element Method (ANSYS 9.0) to confirm the experimental findings. The elastic modulus of gelatin phantom was compared to computer simulation using Finite Element Method (ANSYS 9.0) assuming Poisson ratio of gelatin of 0.49 and/or 0.45 to give the elastic modulus of gelatin to be 6kPa to 9kPa The apparent difference of elastic modulus seems to be due to stretching force of rubber of balloon containing water. Computer simulation by Finite Element Method were achieved for future experiments, showing simpler geometry is beneficial.