Technology and Health Care - Volume 15, issue 2

Authors: Duan, Xudong | Tashiro, Manabu | Wu, Di | Yambe, Tomoyuki | Wang, Qingtian | Sasaki, Takehisa | Kumagai, Kazuaki | Luo, Yun | Nitta, Shin-ichi | Itoh, Masatoshi

Article Type: Research Article

Abstract: Changes in the autonomic nervous activity can be induced by various sensory and emotional stimuli. The authors examined whether the power spectral analysis of heart rate variability (HRV) could detect changes in autonomic tone following a lavender aroma treatment or not. Healthy young women (n=10, 23±3 years old) underwent continuous electrocardiographic (ECG) monitoring before and after (10, 20, 30 minutes) the lavender fragrance stimuli. HRV was expressed by three indices: low (0.04–0.15 Hz) and high (0.15–0.40 Hz) frequency components (nLF and nHF, respectively) as well as LF/HF ratio. Increases in the parasympathetic tone were observed after the lavender fragrance stimulus …as seen as increases in the HF component and decreases in the LF/HF. Additional measurement with positron emission tomography (PET) demonstrated the regional metabolic activation in the orbitofrontal, posterior cingulate gyrus, brainstem, thalamus and cerebellum, as well as the reductions in the pre/post-central gyrus and frontal eye field. These results suggested that lavender aromatic treatment induced not only relaxation but also increased arousal level in these subjects. Show more

Keywords: Lavender, heart rate variability (HRV), positron emission tomography (PET), relaxation, aroma-therapy

DOI: 10.3233/THC-2007-15201

Citation: Technology and Health Care, vol. 15, no. 2, pp. 69-78, 2007

Authors: Fukui, Tomohiro | Parker, Kim H. | Tsubota, Ken-ichi | Wada, Shigeo | Yamaguchi, Takami

Article Type: Research Article

Abstract: Pulse Wave Velocity (PWV) is recognized by clinicians as an index of the mechanical properties of human blood vessels. However, the measured PWV of real human blood vessels will not always obey the Moens-Korteweg equation, which describes the PWV in ideal elastic tubes. Waveform analysis has been studied as an alternative diagnosis for cardiovascular disease, and reflected waves that occur in the diseased region may be a key for the estimation of the severity of disease. In this study, we modeled stenosed and aneurysmal arteries in a three-dimensional coupled fluid-solid interaction scheme, and analyzed the pulse wave propagation in order …to assess the reflected waves that occurred in the diseased region. A commercial code (Radioss, MECALOG, France) was used to solve the fluid-solid interactions. A steady flow with Reynolds number 1000 was imposed at the inlet of the artery as the basic flow, then a single rectangular pulse with Reynolds number 4000 was imposed upon the basic flow to produce a propagating wave. We showed that the reflected waves from the stenosis and the aneurysm are different in their phase, and the wavelength of the reflected waves from the aneurysm is affected by the aneurysm length. Show more

Keywords: Pulse wave propagation, stenosis, aneurysm, reflected waves, fluid-solid interaction, wavelength

DOI: 10.3233/THC-2007-15202

Citation: Technology and Health Care, vol. 15, no. 2, pp. 79-90, 2007

Authors: Ito, Kazushi | Sakamoto, Naoya | Ohashi, Toshiro | Sato, Masaaki

Article Type: Research Article

Abstract: Endothelial cells are known to adapt their morphology and functions in response to different types of fluid flow. In vivo, endothelial cells are exposed to varying frequencies of pulsatile flow. Therefore, in this study, the effects of frequency of pulsatile flow on morphology and αv β3 integrin expression of bovine aortic endothelial cells (BAEC) were investigated. A newly developed flow-system was used to apply pulsatile flow at frequencies of 0.5, 1.0, and 1.5 Hz to BAEC for 12 h. At 1.0 Hz, the expression of αv β3 integrin was significantly higher at the central regions of cells than …at the upstream regions. In contrast, at 0.5 and 1.5 Hz, the expression of αv β3 integrin was significantly higher at the upstream regions than at the central regions. Morphological observation revealed that BAEC under pulsatile flow frequencies of 0.5 and 1.0 Hz exhibited elongated morphologies and oriented with the direction of flow. In addition, stress fibers developed parallel to the cell major axis. Similar results were obtained under steady flow conditions. In contrast, BAEC under 1.5 Hz elongated but with a random orientation. These results suggest that BAEC morphology and integrin expression may be modulated by the frequency of pulsatile flow. In particular, BAEC exposed to 1.5 Hz pulsatile flow may not be able to align with the direction of flow, possibly indicating the presence of a critical value for living systems. Show more

Keywords: Endothelial cells, remodeling, pulsatile flow, integrin expression, cytoskeleton

DOI: 10.3233/THC-2007-15203

Citation: Technology and Health Care, vol. 15, no. 2, pp. 91-101, 2007

Authors: Nakajima, Toshi | Mushiake, Hajime | Inui, Toshio | Tanji, Jun

Article Type: Research Article

Abstract: To investigate the involvement of primate non-primary motor cortices in bimanual sequential movements, we recorded neuronal activity in the supplementary motor area (SMA) and presupplementary motor area (pre-SMA) while an animal was performing bimanual motor tasks that required two sequential arm movements consisting of either pronation or supination of the right or left arms with delay periods. We also recorded electromyograms (EMGs) from the arm while the animal performed the bimanual task to compare muscle and neuronal activity. This paper focuses on the neuronal activity before the onset of sequential movements. We found that the prime-mover forelimb muscles were selectively …active when an impending arm movement involved recorded muscles, but was not dependent on whether the arm movements were bimanual or unimanual. In contrast, we found that neurons in the non-primary motor cortices showed different activity depending on whether the forthcoming sequential arm movements were unimanual or bimanual. Our results suggest that neuronal activity in the SMA and pre-SMA reflects higher-order information about arm use before motor execution. By extracting this type of information, we can use it to control prosthetic arms in a more intelligent manner through a brain-machine interface. Show more

Keywords: Brain-Machine Interface (BMI), non-primary motor cortices, higher-order motor information

DOI: 10.3233/THC-2007-15204

Citation: Technology and Health Care, vol. 15, no. 2, pp. 103-110, 2007

Authors: Nakamura, Masanori | Wada, Shigeo | Yamaguchi, Takami

Article Type: Research Article

Abstract: The combined hemodynamics in the left ventricle and aorta were analyzed numerically to investigate how the hemodynamics in the aorta varies with changes in left ventricular systolic function quantified as the ejection fraction (EF). EFs of 0.3, 0.5, and 0.7 were defined by controlling the total volume ejected during systole, while maintaining the ventricular volume at the end of diastole. The results showed that although the variation in left ventricular systolic function resulted in a change in the magnitude of the flow velocity, the intraventricular and aortic flows, including the secondary flows at the aortic valve orifice, were essentially the …same regardless of the EF. To evaluate the strength of the secondary flow relative to the axial flow, the flow momentum index, FMI, was proposed. Spatiotemporal maps of the FMI obtained with different EFs had similar topological patterns, suggesting that the left ventricular systolic function contributed less to the efficiency of conveying blood in the axial direction in the aorta. Systolic function had a minimal effect on the spatiotemporal distribution of the maximum wall shear stress (WSS). A comparison of the spatiotemporal maps of the FMI and WSS revealed that the spatiotemporal maximum of WSS that occur in peak systole did not correspond to that of the FMI, demonstrating that the spatiotemporal maximum WSS was not induced by the helical flow. These results demonstrated that the left ventricular systolic function is not reflected in the global hemodynamics in the aorta and addressed potential of the FMI as an index to quantify the aortic flow disturbances. Show more

Keywords: Blood flow, CFD, circulation, cardiovascular system, heart, biofluid

DOI: 10.3233/THC-2007-15205

Citation: Technology and Health Care, vol. 15, no. 2, pp. 111-120, 2007

Authors: Seto, Fumi | Hirata, Yasuhisa | Kosuge, Kazuhiro

Article Type: Research Article

Abstract: In this paper, we propose a cooperating motion generation method for man-machine cooperation systems in which the machines are controlled based on the intentional force applied by a human/humans for realizing several tasks in cooperation with a human/humans. By applying this method, the systems could avoid self-collisions, collisions with obstacles and other dangerous situations during the tasks. Proposed method consists of two parts; representation method of robots' body referred to as “RoBE (Representation of Body by Elastic elements)”, and cooperating motion generation method using RoBE. As the application examples of proposed method, we focused on robots cooperating with a human/humans …and surgery robot tools from the aspect of medical and welfare field. We did the experiments using human-friendly robot, referred to as MR Helper, for illustrating the validity of the proposed method. We also did the computer simulation to indicate the prospects of applications of our self-collision avoidance method to surgery robot tools. Show more

Keywords: Man-machine system, self-collision, collision avoidance, RoBE

DOI: 10.3233/THC-2007-15206

Citation: Technology and Health Care, vol. 15, no. 2, pp. 121-130, 2007

Authors: Shirai, Atsushi | Fujita, Ryo | Hayase, Toshiyuki

Article Type: Research Article

Abstract: The concentration of neutrophils in the pulmonary microvasculature is higher than in large systemic vessels. It is thought that the high concentration of neutrophils facilitates their effective recruitment to sites of inflammation. Thus, in order to understand the role of neutrophils in the immune system, it is important to clarify their flow characteristics in the pulmonary microvasculature. In a previous study, we developed a model to simulate the flow of neutrophils in a capillary network, in which the cells were modeled as spheres of a Maxwell material with a cortical tension and the capillary segments were modeled as arc-shaped constrictions …in straight pipes. In the present paper, the flow of neutrophils in a simplified alveolar capillary network model is investigated for various constriction shapes and cell stiffnesses. Finally, it is shown that both the coefficient of variation of the transit time of the cells, which is the standard deviation divided by the mean transit time, and the mean transit time increase as the capillary segments become steep or tight, or when the cells become hard. The mean value of the transit time exceeds the median for all of the conditions that occur in real lungs, although the difference between them is small. Show more

DOI: 10.3233/THC-2007-15207

Citation: Technology and Health Care, vol. 15, no. 2, pp. 131-146, 2007

Authors: Yamamoto, Shuji | Horiuchi, Tetsuya | Sekiguchi, Junko | Wada, Shigeo | Komizu, Mitsuru | Yamaguchi, Takami

Article Type: Research Article

Abstract: During the past decade, there has been a notable worldwide increase in the number of computed tomographic (CT) examinations. Since the radiation exposure to the patient during CT examinations is relatively high, it is important to optimize the dose so that it is set as low as possible but remains consistent with the required diagnostic image quality. Therefore we have developed a Digital Imaging and Communications in Medicine (DICOM) image-based program that calculates organ dose and effective dose values corresponding to tube current modulation. The values for primary radiation were derived from manufacturer specifications with international recommendations and from reference …values (ICRP publication 60). Based on these values, organ doses can be computed by the program for arbitrary scan protocols in conventional and in spiral CT. In contrast to similar programs for CT dose assessment, our developed program can perform automatic extraction of the scan protocols from the DICOM tag. Users can easily reproduce and recalculate values by loading DICOM data without the requirement for time-consuming work. Additionally, further extensions are planned to our developed software. Show more

Keywords: DICOM, computed tomography (CT), effective dose

DOI: 10.3233/THC-2007-15208

Citation: Technology and Health Care, vol. 15, no. 2, pp. 147-156, 2007