Yousuke Kinouchi

Measurement of the Electrical Bio-Impedance of Breast Tumors

A new impedance analytical system was developed, and measurements were performed over a frequency range of 0-200 kHz by the three-electrode method. The three electrodes consist of a coaxial needle electrode inserted into the tumor and a large reference electrode on the upper abdominal wall. The electrical bio-impedance was measured in 54 patients with breast tumors. The biological tissue can be regarded electrically as an equivalent consisting of extracellular resistance (Re), intracellular resistance (Ri), and electrical capacitance of the cell membrane (Cm). These three parameters were calculated from the measured values of electrical bio-impedance by the curve-fitting technique using a computer program. It was found that Re and Ri of breast cancers were significantly higher than those of benign tumors (p less than 0.01), and that Cm of breast cancers was significantly lower than that of benign tumors (p less than 0.01). Measurement of the electrical bio-impedance of breast tumors may have value in the differential diagnosis of breast lesions.

Fastin vivo measurements of local tissue impedances using needle electrodes

The objective of the research is to show an in vivo, fast method of measurement of local tissue bio-impedance in the beta dispersion region (0–200 kHz). A needle electrode is used for the purpose. The performances with respect to circuits, electrodes, measurement area and electrical representations are evaluated. A measurement example is shown, and the electrical representations are discussed and compared using it. The method discussed, although invasive, is considered to be useful for local tissue diagnoses concerning structures and physiological functions.

Electrical properties of extracted rat liver tissue

We attempted to investigate the process of ischemia-induced disturbances in the rat liver, employing the electrical bio-impedance technique. The electrical bio-impedance was measured continuously over 6h by the 4-electrode method, at various incubation temperatures, in six liver samples extracted from male Wistar rats. The electrical properties of biological tissues can be expressed in terms of three parameters: extracellular resistance (Re), intracellular resistance (Ri) and cell membrane capacitance (Cm). These three parameters were calculated from the measured values of the electrical impedance by the curve-fitting technique, using a computer program. The Re value increased rapidly after the rat livers were extracted, and then decreased slowly. The Revalue reached a peak after about 13 min at 36°C, and then decreased slowly, becoming constant after 3h. There was a negative correlation between the Tmax of Re (the time when Re reached a maximum) and the incubation temperature (R=−0.973,P<0.001). The Ri value decreased once in the early stage after extraction, followed by almost no change and then an increase after 4h at 36°C. The Cm showed a similar pattern of change to the Re value, and a negative correlation was also found between the Tmax of Cm and the incubation temperature (R=−0.969,P<0.001). The increases in the Re and Cm values, and the decrease in the Ri value for quite long periods after the blood flow has stopped, suggest an increase in the resistance of extracellular fluid due to a decrease in its volume, an increase in cell membrane capacitance due to cell swelling, and a decrease in cellular fluid resistance due to an increase in its volume. The time when the Cm value decreases rapidly after an initial gradual decrease after the peak corresponds well with the time when the Ri value begins to increase, from which it is estimated that cell lysis proceeds and that the flow of extracellular fluid into the cell begins at this time. The findings of this study suggest the possibility of estimating the changes in liver tissue or the tissue structure due to ischemia.

Blood flow in the carotid artery during breath-holding in relation to diving bradycardia

Abstract The present study investigated the mechanism of diving bradycardia. A group of 14 healthy untrained male subjects were examined during breath-holding either out of the water (30–33°C), in head-out immersion, or in whole-body submersion (27–29°C) in a diving pool. Blood velocity, blood volume flow in the carotid artery, diastolic blood pressure and electrocardiogram were measured and recorded during the experiments. The peak blood velocity increased by 13.6% (P < 0.01) and R-wave amplitude increased by 57.1% (P < 0.005) when the subjects entered water from air. End-diastolic blood velocity in the carotid artery increased significantly during breath-holding, e.g. increased from 0.20 (SD 0.02) m · s−1 at rest to 0.33 (SD 0.04) m · s−1 (P < 0.001) at 50.0 s in breath-hold submersion to a 2.0-m depth. Blood volume flow in the carotid artery increased by 26.6% (P < 0.05) at 30 s and 36.6% (P < 0.001) at 40 s in breath-hold submersion to a 2.0-m depth. Diastolic blood pressure increased by 15.4% (P < 0.01) at 60 s during breath-holding in head-out immersion. Blood volume flow, and diastolic blood pressure increased significantly more and faster during breath-holding in submersion than out of the water. There was a good negative correlation with the heart rate: the root mean square correlation coefficient r was 0.73 (P < 0.001). It was concluded that an increased accumulation of blood in the aorta and arteries at end-diastole and decreased venous return, caused by an increase in systemic peripheral resistance during breath-holding, underlies diving bradycardia.

Synchronized measurements of blood flow velocity distributions in carotid, brachial and femoral arteries, and ECG in human during exercise

A measurement system was developed, which was able to measure synchronously blood flow velocity distributions and ECG during exercise. It was found from the results of experiments that the slower maximum blood flow velocity and the faster wave propagation time were observed for standing posture as compared with those for supine. Similarly, it was found that these became faster in proportion to work rate during walking on a treadmill.

Simultaneous Irradiation with Different Wavelengths of Ultraviolet Light has Synergistic Bactericidal Effect on Vibrio parahaemolyticus

Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320–400 nm), UVB (280‐320 nm), and UVC (<280 nm). We previously developed UVA sterilization equipment with a UVA light‐emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA‐LED and another UV wavelength. An oxidative DNA product, 8‐hydroxy‐2’‐deoxyguanosine (8‐OHdG), increased after irradiation by UVA‐LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA‐LED and UVC‐induced additional bactericidal effects, simultaneous irradiation with UVA‐LED and UVC‐induced bactericidal synergistic effects. The 8‐OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response‐deficient mutants, such as the recA and lexA strains. Because recA‐ and lexA‐mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on the suppression of the CPDs repair. The simultaneous irradiation of UVA‐LED and UVC is a candidate new procedure for effective water disinfection.

High frequency region of the snore spectra carry important information on the disease of sleep apnoea

Snoring is the most common symptom of obstructive sleep apnoea (OSA). Several researchers have reported differences between the power spectra of non-OSA and OSA snorers. The traditional approach over the years has been to record snore sounds at a bandwidth of < 5 kHz. Narrowing of the upper airways during OSA events and the resulting upward shift of snore frequencies also lend support to the idea of examining snore sounds beyond 5 kHz. In this paper, we compute the power spectra of snores in three different bands defined as: low-frequency band (LFB: < 5 kHz); middle-frequency band (MFB: 5–10 kHz) and high-frequency band (HFB: 10–20 kHz). We illustrate that there is a significant difference between non-OSA snorers (Apnoea Hypopnoea Index (AHI) < 10) and OSA snorers (AHI > 10) in the region > 5 kHz. We then develop a feature to diagnose OSA based on the spectral differences in the high frequency region and evaluate its performance on a database of 20 subjects. Our results strongly suggest that the high-frequency region of the snore sounds carry information, hitherto disregarded, on the disease of sleep apnoea.

MI sensor-aided screening system for assessing swallowing dysfunction: Application to the repetitive saliva-swallowing test

PURPOSE Assessment of swallowing dysfunction, particularly the risk of aspiration, is extremely important to clinicians because it provides crucial information for preventing morbidity and mortality from dysphagia. The purpose of this study was to describe a magneto-impedance sensor-aided screening system (MISS) for assessing swallowing function and clarify its effectiveness with the repetitive saliva-swallowing test (RSST). METHODS An MI sensor attached to the skin over the sternum detected the distance from a magnet attached to the skin over the thyroid cartilage during swallowing as the change of magnetic fields. The MISS was validated by videofluoroscopic and videoendoscopic observations. Further, the swallowing behavior of 93 individuals was assessed by using the MISS and then analyzed with the RSST. Swallowing behavior can be recorded and investigated objectively by signal inspection in the MISS compared with the conventional methods. The MISS is a simple and straightforward method for recording and safe because of dry swallow. The MISS system was validated by using simultaneous recordings with videofluoroscopic or videoendoscopic examinations, and compared with the conventional RSST method. CONCLUSIONS The MISS combined with the RSST is an effective screening test for swallowing function.

The Development of Remote Monitoring System Using International Standard

Telemedicine has become an indispensable reinforcement in many medical fields, and in the future will become more important for both medical staffs and patients to make the treatment easier faster and safer. We developed a Remote Monitoring System using 3G mobile phone for patients in ICU/CCU. By introducing into the system, the Java application installed on the mobile phone is available for doctors to check the vital physiological data of patients in ICU/CCU. In this study, data collection of this system use an international protocol. Two protocols, HL7(Health Level seven) and MFER(Medical waveform Format Encoding Rules) are used the Remote Monitoring System. The previous system supported only one central monitor. Because it used proprietary protocol to obtain vital inform from central monitor. Other medical equipments are supported by use these protocol. The proposed system can provide patient monitoring to doctors and do a supporting to save patient’s live when doctors are outside the hospital.

Synchronized measurements of maximum blood flow velocities in carotid, brachial and femoral arteries, and ECG in human posture changes

In this research, a system has been developed to measure the maximum blood flow velocity simultaneously by an ultrasonic Doppler technique in three arteries during posture changes. As a peculiarity of this system, two semicircular transducers of 15.0 mm in diameter were used as a transmitter to irradiate a wide ultrasonic beam and a receiver. Because, the position relation between an artery and transducers change rapidly during exercise. This system could be applied to a human body changing from a sitting position to an erect position with voluntary muscle constriction. As a result of measurements, the maximum blood flow velocity in femoral artery has been increased significantly in posture changes like the above.