Electrical Cell-substrate Impedance Sensing (ECIS)法を用いた培養細胞の微細挙動の定量的評価法 - 細胞-細胞間隙と細胞-電極間隙の評価 -

We have proposed a mathematical model for the micro-dynamics for cultured cells measured with ECIS system for the detection of nanometer-order dynamics of cells cultured on a small gold electrode and could separately evaluate cell-to-cell distance (A) and cell-to-substrate distance (h). For wide applications of this method, we constructed mathematical models which express cell-to-electrode impedances for some kinds of confluent conditions. Based on this mathematical model, we defined new parameters S(A) and S(h) in order to evaluate cell-to-cell distance and cell-to-substrate distance. As the application, we investigated the effect of X-irradiation to bovine aortic endothelial cell (BAEC). We analyzed the micro-dynamics of cells from the impedance of BAEC before and after X-irradiation. It was proved that the stimulation of 100 Gy X-irradiation to the BAEC resulted in the large scale of increase in the cell-to-cell distances (A), and the slight increase in the cell-to-substrate distances (h) accompany with continuous fluctuations.[背景] Electrical Cell-substrate Impedance Sensing (ECIS)は培養細胞の電気的計測により,その微細挙動を評価する工学的手法である｡我々はECISを用いてこの微細挙動を細胞-細胞間隙と細胞-電極間隙に分離して推定することが可能な数学的モデルを提案してきた｡本研究ではこの数学的モデルを使用して,Ⅹ線を照射した牛大動脈内皮細胞(bovine aortic endothelial cell : BAEC)の微細挙動の経時変化を評価した｡ [方法と結果] ECISシステム(Model 1600R Applied BioPhysics)を用いてBAECのコンフルエント到達前後で計測を行い,数学的モデルを構築した｡このモデルは細胞の微細挙動を検出するために重要な周波数レンジである1-10kHzにおいて測定結果とよく一致し,Cole-Cole円弧則に従う｡さらに細胞-細胞間距離Aの増減に対応する校正定数S(A)と細胞-電極間距離hの増減に対応する校正定数S(h)を導入し,ベクトルインピーダンスの変化に対応した値を算出することで細胞の微細挙動を評価することとした｡次に本法によりX線(150kV, 100Gy)を照射したBAECの微細挙動を評価した｡Ⅹ線照射細胞では時間経過と共に抵抗成分の変化が支配的なインピーダンスの減少が確認された｡この現象はS(A)の大きな増加とS(h)の微小な減少をもたらした｡このパラメータの変化は細胞間隙が拡大したことを示しており,Ⅹ線照射による細胞内損傷により細胞密度が低下したと考えられた｡ [結論] 本法は培養細胞の微細動態の変化を細胞-細胞間隙と細胞-電極間隙に分けてリアルタイムに定量評価することが可能であり,各臓器の細胞レベルでの薬物の治療効果や Ⅹ線に対する耐性の評価に適応できるものと考える

Consideration of conditions required for multi-channel simultaneous bioimpedance measurement

Impedance techniques have been widely applied to the biomedical engineering field. In order to obtain definite results from bioimpedance, multi-channel measurement is effective. A linearity of biological tissue and fundamental technical parameters for the instrument must be confirmed. In this study, the fundamental conditions have been investigated for multi-channel bioimpedance measurement and the condition of measurement for biological tissue has been confirmed. The differences of every measurement frequency should be appropriate to 1 kHz and it has been shown that the linearity of biological tissue is maintained. Based on these results, a two-channel bioimpedance measurement instrument has been constructed </p

Recent trend of research on the adaptive response induced by low dose radiation and its significance

本総説は,低線量放射線に対する生体の適応応答(以下,適応応答)に関してその効果を含む最近の研究動向,さらに放射線防護との関係についてまとめたものである｡特にこの分野で最も検討が進んでいる｢低線量放射線照射の生物学的影響｣に関する国際研究組織(BELLE)での動向を中心に報告するものである｡即ち,ヒトと自然放射線との共存などヒトの生活環境と適応応答について,適応応答の短期的･長期的効果など適応応答の効果とその生物学的意義について言及した｡次に,適応応答の医療などへの応用の可能性について,また,適応応答と放射線防護との関係についても言及した｡ここで,低線量放射線にはヒトへの有益な効果があるとの多くの報告例がある半面,放射線防護の面では微量放射線でも危険とする考え方がその根拠にあることがわかった｡このため,今後は更なる低線量放射線の生体影響研究を進めるとともに,両者の間の隙間をなくす現実的･合理的な対応が求められている｡We reviewed the recent trend of research on the adaptive response induced by low dose radiation and its significance. The following view were obtained. Risk assessment is fundamental to the protection of public health from radiation exposure, but any estimate of risk is subject to numerous major uncertainties. In view of the uncertainties surrounding the shape of dose-response curves at low doses of ionizing radiation. the linear nonthreshold dose-response model is now widely accepted as a paradigm in radiation protection practice and risk analysis. However, interest among scientists in obtaining a more conclusive understanding of the effects of low dose radiation has been evident in recent initiatives, such as adaptive response of low dose radiation, in part to help verify or disprove the linear model. A vigorous worldwide effort is now apparently underway to understand the basic mechanisms underlying the biological effects of low dose radiation. This review presents a series of papers representing the progress going on, which will undoubtably make an important contribution to this field of research

Skin Electrical Impedance Model for Evaluation of the Thickness and Water Content of the Stratum Corneum

Deterioration of the skin barrier function causes symptoms such as allergies because various chemical substances may enter the human body. Quantitative evaluation of the thickness and water content of the stratum corneum is useful as a measure of the skin barrier function in domains such as dermatology, nursing science, and cosmetics development. The stratum corneum is responsible for most of the skin barrier function, and two factors—the thickness and water content of the stratum corneum—are thus important. In this paper, the stratum corneum is regarded as a parallel model of resistance and capacitance. From measurements of the electrical impedance of the skin, we propose a new model for simultaneous estimation of the thickness and water content of the stratum corneum conventionally measured by a confocal laser scanning microscope and a confocal Raman spectrometer, respectively, and we discuss the results of the measurements. The electrical impedance of the skin was measured using a device that we developed. The measurement began 3 seconds after the electrodes on the measurement head of the device came into contact with the skin, and parameters including the impedance, which was obtained by applying an alternating current signal at two frequencies, were measured. We measured the thickness and water content of the stratum corneum using confocal laser microscopy and confocal Raman spectroscopy, respectively; investigated the relationship of the thickness and water content of the stratum corneum with the electrical impedance of the skin; and established a new potential model for estimating the thickness and water content of the stratum corneum from the parallel resistance and capacitance. The correlation coefficients of the verification data were 0.931 and 0.776, respectively; and the root-mean-squared error of the thickness of the stratum corneum was 2.3 µm, while the root-mean-squared error of the water content at the surface of the stratum corneum was 5.4 points. These findings indicate the feasibility of quantitative evaluation of the thickness and water content of the stratum corneum by measuring skin electrical impedance

Evaluating object and region of concentric electrode in bio-electrical impedance measurement

Concentric electrode is easy to use and used widely for measuring bio-electrical impedance. But, its evaluating region was not investigated in detail. Then, the characteristics of concentric electrode were studied from various points of view. In case of use without electrode paste, impedance is determined with the contacting condition between electrode and skin surface over all frequency range. In case of use with electrode past, impedance is composed of stratum corneum in the frequency range of 20 Hz-1 kHz and is mainly composed of subcutaneous tissue in the range of 200 kHz-1 MHz. In the high frequency range, evaluating region of concentric electrode is the area less than the radius or the gap of center electrode

Effectiveness of impedance parameters for muscle quality evaluation in healthy men

We investigated the relationship between impedance parameters and skeletal muscle function in the lower extremities, as well as the effectiveness of impedance parameters in evaluating muscle quality. Lower extremity impedance of 19 healthy men (aged 23–31 years) measured using the direct segmental multi-frequency bioelectrical impedance analysis were arc-optimized using the Cole–Cole model, following which phase angle (PA), Ri/Re, and β were estimated. Skeletal muscle function was assessed by muscle thickness, muscle intensity, and isometric knee extension force (IKEF). IKEF was positively correlated with PA (r = 0.58, p < 0.01) and β (r = 0.34, p < 0.05) was negatively correlated with Ri/Re (r = − 0.43, p < 0.01). Stepwise multiple regression analysis results revealed that PA, β, and Ri/Re were correlated with IKEF independently of muscle thickness. This study suggests that arc-optimized impedance parameters are effective for evaluating muscle quality and prediction of muscle strength

Development of stepping measurement device for evaluation of and training in walking

日常生活で杖をついたり,老人車などを押したりなど歩行能力の低下した人に対する簡便･安価で効果的な歩行訓練方法,訓練機器はない｡歩行能力の低下した人が体の移動を伴う歩行訓練をする場合,常に転倒の危険性を伴うために,介護者が必要であったり,転倒の不安のために動作が消極的になり,訓練の効果が半減する｡これに対して,ゆっくりとした足踏みは歩行能力の低下した人に対しては下肢筋力の強化,バランス訓練となり,歩行能力を向上させる｡しかし,足踏みが適切におこなわれているか,訓練の効果の程度についての評価ができなかった｡そこで,歩行能力の評価･訓練のために足踏み状態をモニタすることができる足踏み測定器を開発した｡本装置は,足踏みをするマット2枚およびノートパソコンなどから構成されている｡足踏み中における両脚立脚,左右それぞれの片脚遊脚の状態をマットスイッチのON,OFF状態にて判断する｡測定後,歩数,平均両脚立脚時間,平均片肺立脚時間などの解析･表示を行う｡最後に歩行能力が低下した被験者の足踏みを測定して,杖歩行など日常の歩行状態と足踏みの状態との関係を示し,足踏み測定の有効性についても検討した｡Although gait training equipment such as the bicycle ergometer and treadmill exists for patients whose walking ability is high, there is no appropriate gait training method or training instrument for patients whose walking ability has become impaired, who often use a cane or walker, etc. in the course of daily life. In the case of gait training for persons whose walking ability involves impaired locomotion, there is always the danger of a fall. Consequently, a caregiver is required, and the effect of the training is cut by half because the patient's anxiety about falling is exacerbated. Slow stepping affords strengthening and balance training of the leg muscles for patients whose walking ability has become low, and walking ability is improved. However, whether such training appropriately carries out stepping and the degree of the effect of such training has not been evaluated. Therefore, we have developed a stepping measurement device that monitors stepping for evaluation and training of walking ability. This system consists of two mat switches for stepping, a measuring circuit for stepping detection, and a book-sized personal computer with a PC card-type AD converter. This system can detect a left or right single stance phase and a double stance phase relative to the ON, OFF condition of the mat switch. After measurement, the following items are analyzed and displayed: ・number of steps, ・average time of double stance phase, ・the average time of single stance phase, and so on. Finally, we measured the stepping of subjects whose walking ability is low, and showed the relationship between daily walking conditions and stepping conditions. The effectiveness of this system was considered in light of the results

Development of human limb volume meter for evaluation of edema

周産期医学にとって浮腫の定量評価は重要である｡これまでは,測定部位の2箇所の周囲長をメジャーで測り,その変化により浮腫を評価している｡また周囲長により容積を推定する方法も提案されている｡しかしながら,この方法ではメジャーの測定部位への巻き付け方による誤差や容積を推定する根拠となる測定部位のモデル形状と実際の測定部位の形状との誤差など様々な誤差の影響により,精度の点からは十分とはいえない｡そこで,本研究では浮腫評価のための高精度で日常的な使用に適した体肢容積計を開発した｡この測定原理はアルキメデスの原理を適用したもので,水を入れた水槽に測定部位を入れる前後の質量変化により,その容積を量るしくみである｡まず,この容積計の出力の線形性,分解能,安定性,再現性について検討を行った｡この結果,本装置の仕様は最大計測容積25,000cm(3),分解能1cm(3),非直線性0.007%以下となり,非常に高精度であるといえる｡また,被験者3名の足部,下腿部の容積の日内変化を測定した結果,各被験者の容積変化の特徴を明らかにすることができ,浮腫評価への応用ができることを確認した。Quantitative evaluation of the edema is important for perinatal medicine. In a conventional method, the volume of human limb has been estimated by 2 circumferences of the measurement position, which is measured with the tape measure. However, the following errors makes this measurement insufficient; ・the error by the way of winding of a measure to the measurement position, ・the error between volume of model geometry of measurement position and one of real shape of measurement position and so on. Then, we have developed a volume meter of human limb for the edema evaluation, which is high precision and suitable for the everyday use. Archimedes' principle was applied as this measurement principle. The mass change of water tank with water, when the measurement part water in, was converted to volume of measurement part. The linearity, resolution, stability. reproducibility of the volume meter was investigated. Considering these results, we found that the specification of this equipment was high precise as follows; maximum volume of 25,000 cm(3), resolution of 1 cm(3), nonlinearity of 0.007%. We also measured the diurnal volume change of foot and lower leg in three subjects. We found that the differences between foot and lower leg or among the subjects. The developed volume meter can be expected to apply to quantitative evaluation of the edema