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Biomedical subjects

E Tamiya

Publications and source records attributed to E Tamiya.

At least 37 records · Page 2Linked to original sources
PubMed1997

Simultaneous detection of near-field topographic and fluorescence images of human chromosomes via scanning near-field optical/atomic-force microscopy (SNOAM).

Scanning near-field optical/atomic-force microscopy (SNOAM) provided us with simultaneous topographical and optical images of human chromosomes using a sharp and bent optical fiber as a near-field optical probe. Native chromosomes were spread out onto a coverslip using the surface-spreading whole-mount method. The SNOAM system does not need pretreatment of samples such as metal coating or chemical immobilization. Near-field topographic and fluorescence images provided useful information on native chromosome structure.

B-Lymphocytes↗
PubMed1996

Intramyocardial pulsed Doppler echocardiography as a new modality for evaluation of left ventricular wall motion: assessment in normal subjects.

Doppler tissue imaging-guided pulsed Doppler echocardiography can record velocities of the regional ventricular wall, but the potential clinical applications have not yet been investigated. To propose a new modality for assessment of left ventricular wall dynamics, we investigated the longitudinal and latitudinal motions of the normal left ventricular wall with intramyocardial pulsed Doppler echocardiography under tissue imaging guidance, and characterized the velocity patterns in 31 normal subjects or normal volunteers (mean age 38 +/- 18 years old). Velocity patterns of the septal and posterior walls were recorded and compared using the parasternal and apical approaches. The apical approach showed that the entire left ventricle moved, coded in red, toward the transducer during systole, and moved away, coded in blue, during diastole. Pulsed Doppler echocardiography recorded the systolic S, early diastolic E and presystolic A waves from both windows. All three waves had higher velocities in the apical compared to the parasternal approach, and the velocities of S and E waves were increased more in the posterior wall than in the septum. Thus, the A/E ratio was significantly lower in the posterior compared to the septal wall (0.63 +/- 0.3 and 0.77 +/- 0.3, respectively, in the apical approach) and the A/E ratio of transmitral inflow was between those of the walls. Apical intramyocardial pulsed Doppler echocardiography can accurately evaluate septal and posterior wall dynamics. The present study provides important basic data for assessing regional myocardial function.

Adult↗
PubMed1995

Auditory stimuli as a major cause of syncope in a patient with idiopathic long QT syndrome.

A 35-year-old woman was hospitalized due to frequent attacks of syncope immediately after the ringing of a bell or alarm clock. Her standard electrocardiograms showed a long QT interval (QTc = 0.56 s) with a bizarre T-wave inversion in precordial leads. After admission, a total of 9 events of syncope were observed. Malignant ventricular tachyarrhythmia (torsade de pointes, ventricular flutter or fibrillation) was recorded during each episode, and DC shock was required to abolish such tachyarrhythmias on 3 occasions. On monitored electrocardiograms, an additional 8 events of ventricular tachycardia without syncope were also detected. Auditory stimuli appeared to be involved in the initiation of malignant ventricular arrhythmia. Immediately after auditory stimuli, changes in the QT interval and T-wave morphology resulted in ventricular premature beats, leading to ventricular tachycardia. The episodes of syncope or malignant ventricular arrhythmia were frequently observed early in the morning and near midnight. She had been treated with various types of antiarrhythmic agents, and propranolol was the most effective in preventing ventricular arrhythmia. These findings indicate that auditory stimuli may cause ventricular arrhythmia and subsequent cardiac syncope, or even sudden cardiac death, in some patients with long QT syndrome.

Acoustic Stimulation↗
PubMed1994

Micromachined electroporation system for transgenic fish.

Luciferase gene was introduced into fertilized eggs of medaka by a localized electric field between thin film electrodes formed on a glass plate. Miniaturization of the electrodes enabled us to apply a localized electric field to the animal pole of the fertilized egg. Biochemical luminescence and an electrophoresis pattern showed expression and integration of the gene, respectively. The presented system had a higher ratio of gene introduction than the conventional electroporation method.

Animals↗
PubMed1994

Multisample analysis using an array of microreactors for an alternating-current field-enhanced latex immunoassay.

To develop a rapid and multisample analysis system for latex immunoassay with submicroliters of sample, an array of microreactors were fabricated using micromachining techniques including photolithography, anisotropic etching, and thin gold film deposition. The chamber volume for immunoreactions of a single well was 0.4 microL. An alternating-current (ac) field was used to enhance the rate of the latex agglutination reaction. By applying an ac field for 1 min, alpha-fetoprotein in several samples could be determined simultaneously. The detection limit in this system was approximately 10 pg/mL.

Female↗
PubMed1993

Microbiosensors for acetylcholine and glucose.

Microbiosensors based on carbon and and platinum fibers are described. Carbon fibers were used to construct microelectrodes of 7 microm diameter. Electrochemical operations for pre-electrolysis and measuring were examined for the highly sensitive determination of hydrogen peroxide. A triangular potential (-2 to +2V vs Ag/AgCl) was applied before measuring each pair of double pulses (first pulse: 750 mV; second pulse: 1100 mV). The determination limit was 0.1 microM of hydrogen peroxide. The reproducible determination of hydrogen peroxide is possible even in samples containing albumin protein. The separation of hydrogen peroxide from ascorbic acid is also possible because the oxidation potential of ascorbic acid is different from that of hydrogen peroxide. An acetylcholine microsensor was fabricated by immobilizing acetylcholine esterase and choline oxidase on the carbon fiber by entrapment with poly(vinyl alcohol)-quarternized stilbazole (PVA-SbQ). This sensor gave a linear calibration plot for the range 0.1-1.0 mM with a linear correlation coefficient of 0.9842. Glucose oxidase (GOD) and glucose dehydrogenase (GDH) immobilized cylindrical platinum microelectrodes were fabricated, and their characteristics were evaluated, respectively, by using 1,4-benzoquinone (BQ) and ferricyanide as electron mediators. Each enzyme was immobilized by using PVA-SbQ on a cylindrical microelectrode of 2 microm diameter. A linear range in the calibration curve of the GOD-based glucose microsensor was observed to be wider than that obtained using a disk electrode of 1 mm diameter. The mediated response of the 2 microm glucose sensor was compared with the response resulting from hydrogen peroxide detection. This result showed that a higher response and a wider linear range were observed with highly concentrated mediator. A much higher response of the GDH immobilized 2 microm microelectrode was obtained when not only ferricyanide but also diaphorase was employed to reoxidize the NADH produced by the enzyme reaction of GDH. The GHD-based glucose microsensor was found to be unaffected by the concentration of dissolved oxygen.

Acetylcholine↗
PubMed1992

Ultramicrobiosensors for monitoring of neurotransmitters.

Carbon fiber electrodes are used to construct ultramicrobiosensors with 7-15 microns diameter. Electrochemical operations for preelectrolysis and measuring were examined for sensitive determination of hydrogen peroxide. Determination limit was 0.1 microM of hydrogen peroxide. Reproducible determination of hydrogen peroxide is possible even in samples containing albumin protein. A micro-acetylcholine sensor was fabricated by immobilizing acetylcholine esterase and choline oxidase on the carbon fiber by entrapment with PVA-SbQ. This sensor gave a linear calibration plot for the range from 0.1 to 1.0 mM with a linear correlation coefficient of 0.9842. A micro-glutamate sensor consisted of a platinized carbon fiber disk electrode modified with immobilized glutamate oxidase membrane. This sensor gave a linear calibration for the range 2 microM to 1.2 mM. Release of glutamate in the cerebellar cortex was detected after potassium stimulation.

Acetylcholine↗
PubMed1992

Bioluminescence detection system of mutagen using firefly luciferase genes introduced in Escherichia coli lysogenic strain.

A rapid and convenient microbial sensing system for mutagens was developed based upon the induction of prophage from Escherichia coli lysogenic strain and bioluminescence. The system consisted of lysogenic E. coli encoding firefly luciferase genes and a photodetection system. Measurement of mutagen mitomycin C was achieved by measuring the luminescence intensity emitted from E. coli lysogenic strain for the recombinant phage in the presence of luminescence substrates. Approximately 1 h after addition of mitomycin C, the luminescence began to be observed, and 3 h after, it attained a level of 2 times greater than that of 1 h. Irradiation with ultraviolet light also produced light based on induction of phage from the E. coli lysogenic strain for the recombinant phage. On the other hand, when nonmutagenic toxic compounds like sodium azide were added to the reaction medium, luminescence was not observed. Mitomycin C could be detected within 1 h with this sensing system, at concentrations down to 10(2) ng/assay.

Bacteriophage lambda↗
PubMed1992

A biocompatible needle-type glucose sensor based on platinum-electroplated carbon electrode.

A biocompatible needle-type glucose sensor with a 3-electrode configuration was constructed. A platinum-electroplated carbon stick was used as the working electrode, Ag/AgCl as the reference electrode, and a disposable hypodermic needle made of stainless steel as the counter electrode. A Nafion membrane, an immobilized glucose oxidase (GOD) membrane, and a biocompatible membrane with diffusion-limiting effect were coated successively onto the working electrode. The sensor showed a rapid response (< 120 s in batch operation), good reproducibility (RE < 3%), good stability (over 36 h in control serum), a wide dynamic range (5-600 mg/dL glucose), and superior biocompatibility. It was used to determine glucose in serum. The data obtained from the sensor showed good agreement with that from a clinical autoanalyzer (R > 0.95).

Biocompatible Materials↗
PubMed1992

A novel microbial sensor using luminous bacteria.

A novel microbial sensor system that uses luminous bacteria was developed for the determination of both glucose and toxic compounds. The sensor system consisted of a membrane with luminous bacteria immobilized upon it and a photomultiplier. Measurements were based on the in vivo intensity of the light emitted by the bacteria, as this is affected by their environment. A linear relationship was observed between increased luminescence and concentrations of glucose between 0.05 mM and 0.55 mM. The relative standard deviation was 10% for 0.55 mM glucose (n = 10). Toxic compounds such as benzalkonium chloride, sodium dodecyl sulphate and chromium(VI) were also detected by measuring the decrease in luminescence in their presence.

Bacteria↗
PubMed1992

Detection of coronary artery calcification by X-ray computed tomography and its significance: a new CT scoring technique.

In order to study the utility of X-ray computed tomography (CT) for the evaluation of coronary stenosis, the authors developed a scoring system for calcification seen through CT and compared the results with coronary angiographic (CAG) findings (Friesinger's scoring system). Their study included 143 patients (angina pectoris 53, myocardial infarction 44, control 46) who received both CT and CAG. Judkins method was selected for CAG, and stenosis greater than or equal to 75% was defined as significant. Horizontal slices of CT from ascending aorta to cardiac apex at 1 cm intervals were imaged without contrast enhancement. CT scoring system was as follows: no calcification = 0, the length of calcification less than 1 cm = 1, 1-2 cm = 2, more than 2 cm = 3 points. They then totaled the separate scores of all the slices for each coronary artery. Sensitivity, specificity, and predictive value of CT against coronary stenosis were good (79%, 80%, 69%, respectively). The correlation between CT and CAG scores was significant (r = 0.644, p less than 0.01). For all coronary arteries, no correlation was found between the CAG and CT findings for patients less than forty-five years of age. However, from 45 years of age upward, the results were significant. Until now, to the best of their knowledge, no satisfactory system to define the severity of coronary calcification has existed. Density cannot be used, because values are dependent on the area of the region of interest used. They demonstrated the considerable potential usefulness of CT in predicting the presence of coronary stenosis and analyzing its severity.

Calcinosis↗
PubMed1992

[Assessment of coronary artery bypass grafts by X-ray computed tomography with and without contrast enhancement].

To assess the patency of coronary artery bypass grafts, we tested the capability of X-ray computed tomography (CT) with and without contrast enhancement. This procedure was used on 63 grafts (30 in the LAD; 20 in the LCX; 13 in the RCA) in 32 patients with a mean age of 56 +/- 8 years, all of whom were referred to our department for postoperative management or evaluation. The CT scanner used was Toshiba TCT-60A with a scan time of 3 sec, 5 mm thick slices, and 512 x 512 pixels. CT scans without contrast enhancement were obtained from the level of the aortic arch to the left ventricle. Eight sec after 30 ml of contrast media was injected at a rate of 3 ml/sec into an antecubital vein, 5 scans were made at the same level of the pulmonary artery truncus. After positioning the regions of interests on the ascending aorta and grafts, we obtained time-density curves (TDCs) and compared the data with those recorded from an intraoperative electromagnetic flow meter (EMF). Fifty grafts were angiographically patent. The appearance time, build-up time, peak time, disappearance time and peak densities obtained from TDCs of grafts did not correlate with the flow volumes measured by EMF. Patent grafts were easily identified visually, without contrast enhancement (sensitivity; 88%, specificity; 100%, accuracy; 91%). Occluded grafts were not imaged on CT, either with or without contrast enhancement. We concluded that the TDCs of grafts obtained by CT are of no value for predicting the graft flow, and that plain CT without contrast enhancement is sufficiently useful for assessing the patency of such grafts.

Aged↗
PubMed1992

[Doppler and echocardiographic study of normal systolic murmurs].

To elucidate the genesis of normal ejection systolic murmurs, we performed phono and Doppler echocardiography in 42 normal subjects. Individuals with hypertension, ST.T changes on ECG, anemia or other cases with definite cardiovascular findings were excluded from the study. Their ages ranged from 22 to 61 years with an average of 48.1 years. They were classified in 2 groups; 9 with Levine 2/6 systolic murmur and 33 without murmur or with 1/6 murmur. Fifteen patients with pure aortic regurgitation or with aortic prosthesis but without significant stenosis, and 7 patients with pulmonic valvular stenosis were served as control. We correlated the intensity and timing of murmur with maximal flow velocity, acceleration time and other parameters. All systolic murmurs were early systolic. Mid-systolic murmur was not noted. Peak of flow velocity increased at the aortic orifice than at the left ventricular outflow tract or pulmonary orifice. Left-sided peak flow velocity occurred earlier than the right-sided peak flow velocity. Early systolic maximal flow velocity of the aorta significantly increased in 9 subjects with murmur than in the remaining 33 without significant murmur. Ejection fraction, hematocrit and body surface area did not differ between the groups with and without significant murmur. Systolic blood pressure and age, however, were higher in subjects with murmur. In aortic valvular disease, systolic murmurs and peak flow signals were early systolic, but in pulmonary stenosis these were mid-systolic in timing. In conclusion, normal ejection systolic murmurs were early systolic and originated at the aortic orifice. Mid-systolic murmurs were unlikely as left-sided murmur in origin. Flow velocity was the most important determinant of the intensity of ejection murmur.

Adult↗
PubMed1991

Amplification immunoassay for the determination of hepatitis B surface antigen.

A sensitive sandwich immunoassay for the determination of Hepatitis B surface antigen (HBs) was developed, using a cascade system of Limulus amebocyte lysate as a signal amplification system. Lipopolysaccharide (LPS) was conjugated to anti-HBs antibody. Anti-HBs antibody was adsorbed to polystyrene beads. First, HBs were reacted to solid phase anti-HBs antibody (a-HBs). After the reaction, the beads were rinsed, and were then reacted with a-HBs-LPS. Then, LPS activity specifically bound to the beads was measured. HBs could be measured in the range of 10(-10)-10(-12) g/mL.

Hepatitis B Antibodies↗
PubMed1991

Fluorescence polarization immunoassay employing immobilized antibody.

The use of an antibody immobilized on latex or silver colloid in fluorescence polarization immunoassay (FPI) is assessed. In FPI it is possible to detect antigens of high molecular weight because the molecular weight of the antibody is effectively increased. In the assay for rabbit immunoglobulin G a limit of detection lower by two orders of magnitude and an assay range wider by one order of magnitude can be obtained in comparison with conventional FPI. The detection limit is 10(-10) mol l-1 and the total assay time for one sample is 8 min. This assay combines a low detection limit with a short assay time.

Animals↗