Electrical Impedance Method Research Articles

B116 電気インピーダンス法を用いた関節軟骨の力学特性の評価(B1-4 関節・人工関節)

B116 電気インピーダンス法を用いた関節軟骨の力学特性の評価(B1-4 関節・人工関節)

Changes in the intracranial rheoencephalogram at lower limit of cerebral blood flow autoregulation

Cerebral blood flow (CBF) reactivity monitoring is an appropriate primary parameter to evaluate cerebral resuscitation due to a systemic or regional cerebral injury leading to possible irreversible brain injury. Use of the electrical impedance method to estimate CBF is rare, as the method's anatomical background is not well understood. Use of intracranial rheoencephalography (iREG) during hemorrhage and comparison of iREG to other CBF measurements have not been previously reported. Our hypothesis was that iREG would reflect early cerebrovascular alteration (CBF autoregulation). Studies comparing iREG, laser Doppler flowmetry and ultrasound were undertaken on anesthetized rats to define CBF changes during hemorrhage. Blood was removed at a rate required to achieve a mean arterial blood pressure (MABP) of 40 mm Hg over 15 min. Estimation of CBF was taken with intracranial, bipolar REG (REG I; n = 14), laser Doppler flowmetry (LDF; n = 3) and carotid flow by ultrasound (n = 11). Data were processed off-line. During the initial phase of hemorrhage, when MABP was close to 40 mm Hg, intracranial REG amplitude transiently increased (80.94%); LDF (77.92%) and carotid flow (52.04%) decreased and changed with systemic arterial pressure. Intracranial REG amplitude change suggests classical CBF autoregulation, demonstrating its close relationship to arteriolar changes. The studies indicate that iREG might reflect cerebrovascular responses more accurately than changes in local CBF measured by LDF and carotid flow. REG may indicate promise as a continuous, non-invasive life-sign monitoring tool with potential advantages over ultrasound, the CBF measurement technique normally applied in clinical practice. REG has particular advantages in non-hospital settings such as military and emergency medicine.

1210 効果的レーザー刺激部位検出装置の開発(G02-1 医療とバイオエンジニアリング(1),G02 バイオエンジニアリング)

This paper describes the development of device that can detect effective treatment point for laser stimulation quickly and easily. The effect of the relaxation can be achieved by irradiating the laser to a specific acupuncture point. However, it was not effective because the method of detecting the acupuncture point was difficult in the past. As for the method for the easy detection of the specific acupuncture point, it was reported that there are an electric impedance method and an acoustic method. However, the method of detecting these was not effective enough. Therefore, it is necessary to investigate an electric characteristic of the acupuncture point more in detail.

445 電気インピーダンス法を利用した培養軟骨の評価(GS-13 : 骨・軟骨(2))

445 電気インピーダンス法を利用した培養軟骨の評価(GS-13 : 骨・軟骨(2))

Assessment of Stroke Volume Using Electrical Impedance Method

Assessment of Stroke Volume Using Electrical Impedance Method

Electrical impedance change method for moisture absorption monitoring of CFRP

Health monitoring techniques for CFRP composite structures have been developed to assure structural integrity. An electric impedance method is cost-effective and easy to apply to various structures. In an actual environment, moisture absorption may affect the electric impedance change of CFRP. In this paper, the influence of moisture absorption is investigated experimentally. The electric impedances both in the fiber direction and the transverse direction were measured during moisture absorption. For both directions, it was found that the electric impedance increased with moisture absorption. Furthermore, a monitoring method of moisture content near the surface is proposed and experimentally investigated. As a result, it is shown that the change of the electric impedance is relevant to the moisture content near the surface.

Low frequency electrical bioimpedance for the detection of inflammation and dysplasia in Barrett's oesophagus

Biological tissues undergoing inflammation and dysplasia seem to exhibit changes in the intercellular space that can be sensed using low frequency electrical impedance methods. Basically, low frequency electric current flows through this space and its widening as well as the disruption of the tight junction decrease the resistance, facilitating current flow. The electrical changes accompanying structural changes from columnar tissue to adenocarcinoma in Barrett's metaplastic mucosa and gastric tissue are illustrated using resected tissue from 32 patients. Two hundred and fifty-eight biopsies were analysed, correlating their electrical resistivity (R) at 9.6 kHz and their histopathological interpretation. Compared to non-inflamed non-dysplastic columnar tissue (R = 4.9 Ω m), the results suggest a small but statistically significant decrease of electrical impedance in columnar tissue showing inflammation (R = 4.2 Ω m, p = 0.016) and a larger decrease when dysplasia is present (R = 3.4 Ω m, p = 0.040). If this method is validated further, this technique could be used to obtain guided biopsies from patients undergoing surveillance programmes for Barrett's oesophagus. We aim to refine this technique using a new system with lower frequencies and, possibly, in vitro (cultured cells) and in vivo (rats) models of Barrett's oesophagus.

Experimental Detection of Reinforcing Bar Corrosion Using Nondestructive Geophysical Techniques

This research used electrical impedance and ground penetrating radar (GPR) methods to indicate corrosion of steel reinforcing bars embedded in a concrete block. Corrosion of the reinforcing bars was accelerated using an anodic polarization technique. Measurements were collected using both geophysical techniques before and after the corrosion experiments. Analysis of the geophysical measurements indicated the potential benefits and limitations of the 2 geophysical methods for assessing corrosion of reinforcing bars. GPR methods have the advantage of providing a quick indication of alterations at the interface of the rebar surface and the surrounding concrete, and they have the potential to yield very high spatial resolution data. Indications that corrosion had occurred were independently and consistently obtained from the 2 geophysical methods, and observations were also corroborated by visual examination of the rebar corrosion state by destructive analysis of the experimental block.

Inflammatory Markers and Platelet Aggregation Tests as Predictors of Hemoglobin and Endogenous Erythropoietin Levels in Hemodialysis Patients

Background/Aims: Chronic inflammation is a common cause of severe anemia and hyporesponsiveness to recombinant erythropoietin (EPO) therapy in maintenance hemodialysis (HD) patients. We compared various acute-phase markers and ex vivo platelet aggregation tests in relation to clinical conditions in order to find factors predictive of hemoglobin (Hb) and endogenous EPO levels in a cross-section of clinically stable HD patients. Methods: In 100 subjects, pre-HD blood levels of C-reactive protein (CRP), α₁-acid-glycoprotein (AGP), α₁-antitrypsin (AT), immunoglobulin (Ig) M and G (by nephelometry), antigens of endothelial von Willebrand factor (vWF), type 1 plasminogen activator inhibitor and thrombomodulin, interleukin-6, lipoprotein(a) [Lp(a)] and EPO (by ELISA), and albumin, fibrinogen, iron metabolism indices, thyroid-stimulating hormone, phosphorus, parathormone, total cholesterol, triglycerides, viral hepatitis B/C markers, liver enzyme, and aluminium were determined. Platelet aggregations in response to ristocetin (RIPA), adenosine diphosphate, and collagen were measured in whole blood (electric impedance method) and platelet-rich plasma (optical aggregometry). Results: Hb levels inversely correlated with IgM, Lp(a), soluble vWF antigen, phosphorus, and all platelet aggregations in whole blood, but not in platelet-rich plasma. HD duration and triglycerides were positive correlates of anemia. In a multivariable analysis, increased IgM, short HD duration, increased Lp(a) and enhanced whole blood RIPA (in descending order of significance) were independent predictors of low Hb levels. In 51 patients not treated with recombinant EPO, serum levels of this hormone inversely correlated with whole blood RIPA, AT, age, vWF antigen, AGP, and positively with viral hepatitis marker. Anemia and EPO levels were not affected by gender, body mass index, cause of renal failure, residual renal function, HD dose, protein catabolic rate, use of different heparins or dialysate buffers, ACE inhibitor therapy, and parathyroid or thyroid function. In additional 10 patients, single HD session resulted in an increase in IgM levels associated with a fall in total lymphocyte counts. Conclusion: Subclinical inflammation is an important determinant of anemia in maintenance HD patients. Increased serum IgM reflecting a microinflammatory effect of HD procedures, enhanced whole blood RIPA as a surrogate of vascular endothelial damage, and Lp(a) as its promoter could be markers of such impaired erythropoiesis.

Ethanol-induced swelling in neonatal rat primary astrocyte cultures

We tested the hypothesis that astrocytes swell in response to ethanol (EtOH) exposure. The experimental approach consisted of an electrical impedance method designed to measure cell volume. In chronic experiments, EtOH (100 mM) was added to the culture media for 1, 3, or 7 days. The cells were subsequently exposed for 15 min to isotonic buffer (122 mM NaCl) also containing 100 mM EtOH. Subsequently, the cells were washed and exposed to hypotonic buffer (112 mM NaCl) containing 100 mM mannitol. Chronic exposure to EtOH led to a marked increase in cell volume compared with control cells. Specific anion cotransport blockers, such as SITS, DIDS, furosemide, or bumetanide, when simultaneously added with EtOH to hyponatremic buffer, failed to reverse the EtOH-induced effect on swelling. In acute experiments, confluent neonatal rat primary astrocyte cultures were exposed to isotonic media (122 mM NaCl) for 15 min, followed by 45-min exposure to hypotonic media (112 mM NaCl, mimicking in vivo hyponatremic conditions associated with EtOH withdrawal) in the presence of 0–100 mM EtOH. This exposure led to a concentration-dependent increase in cell volume. Combined, these studies suggest that astrocytes exposed to EtOH accumulate compensatory organic solutes to maintain cell volume, and that in response to hyponatremia and EtOH withdrawal their volume increases to a greater extent than in cells exposed to hyponatremia alone. Furthermore, the changes associated with EtOH are osmotic in nature, and they are not reversed by anion cotransport blockers.

K-2324 サンドイッチ積層板に対する欠陥検知に対する電気インピーダンス変化法の適用(J03-5 ひずみ計測)(J03 知的材料・構造システム)

K-2324 サンドイッチ積層板に対する欠陥検知に対する電気インピーダンス変化法の適用(J03-5 ひずみ計測)(J03 知的材料・構造システム)

Methylmercury-induced astrocytic swelling is associated with activation of the Na +/H + antiporter, and is fully reversed by amiloride

Astrocytes are a known `sink' for brain methylmercury (MeHg) deposition. Yet, the significance of the preferential accumulation of MeHg within these cells is imprecisely defined. To determine whether MeHg in isotonic buffer has the potential to interfere with homeostatic functions, we measured its effect on astrocytic volume using an electrical impedance method [E.R. O'Connor, H.K. Kimelberg, C.R. Keese, I. Giaever, Electrical impedance method for measuring volume changes in astrocytes, Am. J. Physiol. 264 (1993) C471–C478.]. In addition, we have characterized the alterations in astrocytic ion permeability associated with exposure to this organometal. The results show that MeHg rapidly induces astrocytic swelling, and that this effect is secondary to increased astrocytic Na + uptake. Furthermore, the effect of MeHg on astrocytic swelling is completely inhibited by amiloride, but not by SITS (4-acetamido-4′-isothiocyanatostilbene-2,2′-disulfonic acid), furosemide, or bumetanide. Accordingly, increased cellular permeability to Na + via the Na +/H + antiporter is invoked as the primary mechanism of MeHg-induced astrocytic swelling.

Investigation into the effects of haematocrit and temperature on the resistivity of mammalian blood using a four-electrode probe.

Haematocrit and temperature effects on resistivity are investigated using the electrical impedance method. Measurements are made extensively for pig's blood. The experimental set-up basically involves four ring electrodes being placed around a wooden probe that is subsequently immersed into a syringe containing pig's blood. The syringe is then submerged in water maintained at a constant temperature while measurements are taken. The resistivity of blood is found to increase linearly by approximately 2.9% as the haematocrit level increases from 18% to 49% at a fixed temperature of 37 degrees C. Furthermore, the resistivity is found to decrease linearly by approximately 22% with temperature increasing from 33 degrees C to 42 degrees C for all practical levels of haematocrit.

Pharmacological characterization of swelling-induced D-[3H]aspartate release from primary astrocyte cultures.

During stroke or head trauma, extracellular K+ concentration increases, which can cause astrocytes to swell. In vitro, such swelling causes astrocytes to release excitatory amino acids, which may contribute to excitotoxicity in vivo. Several putative swelling-activated channels have been identified through which such anionic organic cellular osmolytes can be released. In the present study, we sought to identify the swelling-activated channel(s) responsible for D-[3H]aspartate release from primary cultured astrocytes exposed to either KCl or hypotonic medium. KCl-induced D-[3H]aspartate release was inhibited by the anion channel inhibitors 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), dideoxyforskolin, L-644711, ATP, ITP, 3'-azido-3'-deoxythymidine, DIDS, and tamoxifen but not by cAMP. The cell swelling caused by raised KCl was not inhibited by extracellular ATP or tamoxifen as measured by an electrical impedance method, which suggests that these anion channel inhibitors directly blocked the channel responsible for efflux. Extracellular nucleotides and DIDS, however, had no or only partial effects on D-[3H]aspartate release from cells swollen by hypotonic medium, but such release was inhibited by NPPB, dideoxyforskolin, and tamoxifen. Of the swelling-activated channels so far identified, our data suggest that a volume-sensitive outwardly rectifying channel is responsible for D-[3H]aspartate release from primary cultured astrocytes during raised extracellular K+ and possibly during hypotonic medium-induced release.

MAXIMAL OXYEN UPTAKE AT IDEAL BODY WEIGHT

428 Maximal oxygen uptake (MVO2) is conventionally expressed in ml/min/kg considering differences in the body size. However, with this practice MVO2 in obese subjects is rendered disproportionately low. We propose the concept of MVO2 at the ideal body weight to alleviate this problem. The data of 566 men(M) and 1723 women(W) in the age range of 20-69 who underwent health check was analyzed. BMI ranged from 17 to 34. MVO2 was calculated from the test duration in the symptom-limited maximal bicycle exercise. The direct and indirect methods of obtaining MVO2 in a preliminary study agreed well (r=0.97, n=38). Fat-free body weight was calculated by the electrical impedance method. Based on previous studies on animals of different sizes, MVO2(ml/min) was divided by the body height(m) squared. Then it was multiplied by a constant of 22. In essence, this is MVO2 per ideal body weight (body weight at BMI=22, MVO2id) and expressed in the widely used unit of ml/kg/min. The conventional MVO2 per weight had a strong negative correlation with body weight (M:r=-0.47, W:r=-0.50, p<0.01), yet MVO2id was much less affected by weight (M:r=0.11, W:r=0.10, p<0.05). MVO2id correlated with MVO2 per fat free body weight(M:r=0.77,W:r=0.78, P<0.01). In conclusion, maximal oxygen uptake may be easily expressed as one per ideal body weight by utilizing the ideal BMI. This will of great convenience when MVO2 needs to be evaluated in weight-unsupported situations, particularly in obese subjects.

ELECTRICAL IMPEDANCE METHODS FOR ASSESSING FRUIT QUALITY: AVOIDANCE OF ELECTRODE ARTIFACTS

When assessing fruit or vegetable quality by electrical impedance methods, it is necessary to avoid the influence of interfacial impedances between the electrodes and the tissue. I describe these effects, and consider methods for minimising or compensating for them. Compensated 3-electrode techniques suitable for use with currently-available impedance analysers, are presented. The techniques are illustrated by examples of their effectiveness at suppressing impedance artefacts with a novel tissue-probe and a non-invasive measurement. The superior speed and resolution of these methods are expected to be suitable for the useful development of non-invasive measurements.

Elastic wave propagation in porous piezoelectric ceramics

Abstract The elastic wave propagation in piezoelectric ceramics with pore volume fractions up to 0.6 has been investigated. The samples have been prepared by tape casting starting from lead zirconate-titanate (PZT) powder with mean particle diameter 1.4 μm. Sample analysis performed by intrusion mercury porosimeter revealed interconnected porosity with narrow size distribution. The samples were cleaned, silver metallized on two opposite surfaces and polarized in a silicon oil bath by applying an electric field of approximately 3 kV/mm at 120 °C for 1 h. After polarizing, the samples were thoroughly cleaned in an ultrasonic bath in acetone. The elastic properties of the samples were measured by different techniques: the electrical impedance method and acoustic wave transmission. From these measurements, the elastic wave velocities, elastic moduli and attenuation were obtained as a function of pore volume fraction, p . It has been found that wave velocities decrease continuously with p . Effective medium models predictions fit well only in a low p range; therefore, we addressed the problem through percolation theories developed for high p systems. We find that our samples can be assimilated with percolation systems in the high p range and calculated the critical exponent of the elastic moduli as well as the percolation threshold. The ultrasonic attenuation experiments were performed in the 1–11 MHz frequency range. The attenuation observed in porous samples is much larger than in bulk PZT, implying that the attenuation is not caused by the usual sound absorption mechanisms in PZT, but is probably associated with scattering from geometric disorder. It has been found that the frequency dependence of the attenuation follows a power law, with the measured exponents in the range 1.3–1.8, depending on porosity and on pore size distribution. We believe that the very large attenuations observed in our samples at high frequencies can be associated with a transition to localized vibrational modes in porous media, as predicted for percolating systems at length scales near the percolation correlation lengths.

Modulation of hematopoiesis by ketanserin in erythropoietin-treated uremic patients: evidence from platelet studies

Recombinant human erythropoietin (EPO) not only ameliorates the anemia of renal failure but also modulates platelet function and corrects uremic platelet serotonin (5-hydroxytryptamine, 5-HT) storage pool deficiency. We studied if ketanserin, a blocker of platelet and vascular smooth muscle receptors for 5-HT, could reverse any EPO-induced changesin hemostasis. A complete blood count, immunoreactive serum EPO concentration, skin bleeding time (BT) and whole blood platelet aggregation (electric impedance method) induced by ristocetin and ADP, and intraplatelet and whole blood 5-HT, were determined in seven chronic hemodialysis (HD) patients before and after 1, 2, 4 and 8 weeks of EPO therapy, and repeated after a 4-week co-treatment with oral ketanserin. Stimulation of erythropoiesis was accompanied by a rise in the platelet count ( P < 0.05), shortening of the BT ( P < 0.02), an increase in platelet aggregability, and by replenished intraplatelet 5-HT store. Ketanserin co-treatment produced an unexpected 33% fall in serum EPO level ( P < 0.02), a decrease in the platelet count ( P < 0.05), prolongation of the BT ( P < 0.05) and depressed platelet aggregation in response to both agonists. There wasno change in the amount of intraplatelet 5-HT while whole blood 5-HT concentration decreased significantly ( P < 0.02). Strong positive correlations between the decrease in whole blood 5-HT and the prolongation of the BT ( r = 0.786, P < 0.05), and between the former parameter and the fall in the platelet count ( r = 0.820, P < 0.05) were found. In conclusion, we report dual erythro- and thrombocytopoietic effects of EPO combined with correction of a platelet defect in thestorage of 5-HT and enhanced platelet aggregability. The ketanserin-induced falls in serum EPO concentration and the platelet count provide new evidence of the dependency of thrombocytopoiesis on EPO in the initial weeks of the therapy. The 'antiplatelet' effects of ketanserin observed in this study seem to be due to reduction in circulating thrombocyte number rather than from any inhibitory effect on their aggregation.

Electrical Impedance of Nodular Basal Cell Carcinoma: A Pilot Study

Background: Previously, we have explored the use of measurements of electrical impedance and devised 4 physically distinct indices named magnitude index (MIX), phase index, real part index and imaginary part index (IMIX) from the impedance data. Our results indicated that these indices could characterize contact reactions. Objective: The goal of the present study was to use the electrical impedance method for the preoperative assessment of nodular basal cell carcinoma (BCC). Methods: We included 11 patients with a total of 12 nodular BCC, diagnosed clinically and histologically. The noninvasive measurements were performed by transepidermal water loss (TEWL) and electrical impedance. For reference, normal looking contralateral or ipsilateral skin was used. Results: Compared to controls, the mean TEWL of BCC was increased, but this finding was not statistically significant. The electrical impedance measurements of BCC tissue revealed statistically significant changes of the impedance indices MIX and IMIX (p ≤0.001). Conclusion: The results suggest that the measurement of electrical impedance might become useful for investigations of BCC.

Unusual eosinophilia not detected by an automated haematological analyser in a patient with liver cirrhosis.

The use of automated haematological analysers to differentiate leucocytes has become more widespread. Unusual eosinophilia in a 57 year old man with liver cirrhosis, caused by hepatitis C infection, and...