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S Yabe

Publications and source records attributed to S Yabe.

At least 19 recordsLinked to original sources
PubMed1995

Complex frequency-dependent interaction of class-I antiarrhythmic drugs as they affect intraventricular conduction.

We investigated the interaction of class-I antiarrhythmic drugs as they affect intraventricular conduction of human hearts in vivo. QRS duration in signal-averaged electrocardiograms and standard electrocardiograms were measured as an index of intraventricular conduction time in 17 patients with implanted pacemakers at various pacing rates (100-180 ppm, VVI mode). Single intravenous administration of lidocaine, disopyramide or aprindine prolonged the QRS of signal-averaged electrocardiograms in a frequency-dependent manner. Lidocaine (n = 17) produced significant QRS prolongation from pre-drug control at rates > or = 120 ppm (6.2 +/- 1.4% at 180 ppm), whereas disopyramide (n = 17) and aprindine (n = 17) did so from the lowest rate (8.9 +/- 1.8% to 12.3 +/- 2.9% at 100-180 ppm with disopyramide; 14.7 +/- 1.3% to 19.3 +/- 2.2% at 100-180 ppm with aprindine). Addition of lidocaine to disopyramide (n = 17) showed an additive effect; QRS prolongation was enhanced significantly by 1.4-2.8% at rates > or = 150 ppm. In contrast, addition of lidocaine to aprindine (n = 17) showed a subtractive effect; the QRS prolongation was attenuated significantly by 1.6-2.4% at rates < 150 ppm. Combined intravenous administration of class-I antiarrhythmic drugs causes not only additive but also subtractive effects on the intraventricular conduction of the human heart, probably through their interaction on the sodium channel receptor.

Aged↗
PubMed1995

Western blot analysis of rat pituitary antigens recognized by human antipituitary antibodies.

Antipituitary antibodies have been reported to exist in sera of patients with autoimmune endocrine disorders. In order to investigate the pituitary antigens recognized by antipituitary antibodies, we studied the autoantigens in rat pituitary membrane and cytosolic fractions recognized by human antipituitary antibodies and anti-human pituitary hormone antibodies. Sera from 6 patients which showed positive antipituitary antibodies by immunofluorescence methods were studied. Each serum identified some proteins with 14.5, 22, 47, 49, 65, 84 and 97.5 kDa. Anti-GH antibodies and anti-PRL antibodies identified a positive band with 22 kDa, suggesting that anti-GH and anti-PRL antibodies may be present in patients' sera. These results indicate that Western blot analysis of rat pituitary antigens recognized by human antipituitary antibodies is a useful method to elucidate the pathophysiology of autoimmune endocrine disorders.

Animals↗
PubMed1995

[B/F non-separative method].

In homogeneous enzyme immunoassay without requirement of separation of free and bound label, the concentration of substances in samples can be detected by measurement of enzyme activity in the mixtures of samples (antigen) and reagents (labeled antigens antibodies, and enzyme substrates). The methods described herein offer the virtues of simplicity and rapidity by use of general-purpose automated clinical analyzer. The concentrations of some drugs, hormones, antibiotics, and very small amount of certain proteins are now detected by the routine examination in these techniques employing commercial diagnostic kits offered by several companies. In this manuscript, we attempted to give an overview of the principle of various methods by use of commercial diagnostic kit applied in routine clinical examinations.

Automation↗
PubMed1994

Differential expression of colony-stimulating factor (CSF) in murine macrophage clones: interferon-gamma-mediated inhibition of CSF production.

Bioassay and northern blot analyses revealed that, among several functional murine macrophage (M phi) clones, lipopolysaccharide (LPS) stimulation generated in distinct induction levels of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and macrophage colony-stimulating factor (M-CSF). When compared with these induction profiles, the M phi clones could be classified into two types; G type (G-CSF GM-CSF-M-CSF+) and GM type (G-CSF +/- GM-CSF M-CSF+) of M phi clones. Unlike G-CSF and GM-CSF that were inducible factors, M-CSF mRNA was constitutively expressed without stimulation and was differentially controlled between the G and GM types; LPS induction decreased M-CSF mRNA in the former, but increased it in the latter. Further northern blot analysis revealed that interferon-gamma (IFN-gamma) suppressed constitutive expression of M-CSF mRNA, and that costimulation with both LPS and IFN-gamma reduced expression of G-CSF and M-CSF mRNA in the G type of M phi clone, but induced higher expression of GM-CSF and M-CSF mRNAs in the GM type of M phi clone compared with LPS alone. However, in either case, IFN-gamma completely inhibited LPS-induced production of active CSF of the M phi clones, which was observed even in IFN-gamma pretreatment, and also abrogated autoactivation of GM-CSF. Our present results suggested that murine M phi clones had differentially regulated expression of CSFs and that IFN-gamma had a regulatory function of inhibiting CSF production of murine M phi s.

Animals↗
PubMed1993

Evaluation of an automatic cardiac activation detector for bipolar electrograms.

The identification of local activation events in bipolar cardiac electrograms, the first step of isochronal map construction, is a time-consuming and difficult process. Owing to the variability among bipolar activation complexes and the lack of practical knowledge concerning the relationship of the bipolar waveform to action potential characteristics, a set of empirical rules to guide the assignment of local activation times have been adopted. A computer program, called AP, has been designed, which implements these rules in the form of a syntactic analyser. Canine epicardial recordings were used to evaluate AP by comparing local activation times, assigned by AP, with times assigned independently by three investigators. The Hermes-Cox model for detector evaluation and a bootstrap statistical method were used in conjunction with ROC analysis to evaluate the ability of AP to detect events. Analysis of discrepancies among investigator-assigned times showed that the reliabilities of AP event detection and AP-assigned times were comparable to those of the investigators. The methods used in system design and evaluation are applicable to a broad range of problems in the detection and localisation of waveform components.

Animals↗
PubMed1993

[Study on consonant confusion in Japanese patients with sensorineural hearing loss].

The speech discrimination scores of a 57S word list were analyzed in 180 patients with sensorineural hearing loss. Confusion matrices were made on consonant groups of voiceless, voiced and nasal consonants. In succession, the incidence of consonants was compared between the 57S word list and Japanese conversation. Consonants with high incidence in Japanese conversation were t, h, d, g, m, and n. Patients with sensorineural hearing loss are apt to confuse t and h to k, d to b or r, g to b, d or r, m to n or r, and n to m or r. It is effective to correct these instances of consonant confusion, for improving conversational ability in Japanese patients with sensorineural hearing loss.

Hearing Loss, Sensorineural↗
PubMed1993

[Detection methods of anti-pituitary autoantibodies].

Bottazzo et al. first reported an assay method of antibodies to human pituitary endocrine cells, using an indirect immunofluorescent technique in 1975. In 1986 Sugiura et al. established a sensitive assay method for pituitary cell antibodies by biotin/avidin detection technique using rat pituitary. They also developed a sensitive assay for antibodies to anterior pituitary cell membrane by immunofluorescence methods using AtT-20 cells and GH3 cells. Recently Crock et al. reported a new approach to the detection of pituitary antibodies by immunoblotting. We focused on assay methods reported previously, including our results of pituitary antibodies in patients with autoimmune thyroid disease. The existence of autoimmune disorders of the pituitary is now accepted on both experimental and clinical grounds.

Adolescent↗
PubMed1992

Mexiletine and propafenone: a comparative study of monotherapy, low, and full dose combination therapy.

The electrophysiological effects of combination therapy of mexiletine and propafenone were assessed using standard 12-lead electrocardiogram (standard ECG), signal-averaged ECG (SAECG), and ambulatory ECG in 31 patients with ventricular arrhythmias. All patients underwent mexiletine monotherapy (M-mono), propafenone monotherapy (P-mono), low dose combination therapy (low M+P), and full dose combination therapy (full M+P). Full M+P increased the PQ interval and QRS duration to the same extent as P-mono did. Low M+P increased PQ interval and QRS duration to a lesser extent than P-mono and full M+P did. P-mono and full M+P significantly decreased root mean square (RMS) and increased f-QRS in SAECG, while M-mono and low M+P showed only a weak trend. SAECGs with late potentials increased in number with treatments; 9 in predrug control, 11 on M-mono, 15 on P-mono, 10 on low M+P, and 14 on full M+P. The percent suppression of frequent premature ventricular contractions (PVCs) (> 1,000/day) with M-mono, P-mono, low M+P, and full M+P were 46.4 +/- 9.0, 56.6 +/- 10.4, 64.4 +/- 9.2, and 71.4 +/- 7.1, respectively, and those of frequent couplets (> 10/day) were 58.3 +/- 17.7, 62.6 +/- 23.6, 87.5 +/- 6.2, and 92.1 +/- 4.0, respectively. Thus, full dose combination of mexiletine and propafenone exhibited the maximum antiarrhythmic efficacy without enhancement of effects on standard ECG and SAECG. Low dose combination therapy showed better antiarrhythmic efficacy in association with lesser effects on standard ECG and SAECG compared with propafenone monotherapy.

Arrhythmias, Cardiac↗
PubMed1992

Cardiac potential and potential gradient fields generated by single, combined, and sequential shocks during ventricular defibrillation.

BACKGROUND: Potential gradient field determination may be a helpful means of describing the effects of defibrillation shocks; however, potential gradient field requirements for defibrillation with different electrode configurations have not been established. METHODS AND RESULTS: To evaluate the field requirements for defibrillation, potential fields during defibrillation shocks and the following ventricular activations were recorded with 74 epicardial electrodes in 12 open-chest dogs with the use of a computerized mapping system. Shock electrodes (2.64 cm2) were attached to the lateral right atrium (R), lateral left ventricular base (L), and left ventricular apex (V). Four electrode configurations were tested: single shocks of 14-msec duration given to two single anode-single cathode configurations, R:V and L:V, and to one dual anode-single cathode configuration, (R+L):V; and sequential 7-msec shocks separated by 1 msec given to R:V and L:V (R:V----L:V). Defibrillation threshold (DFT) current was significantly lower for R:V----L:V than for the other configurations and markedly higher for L:V. Despite these differences, the minimum potential gradients measured at DFT were not significantly different (approximately 6-7 V/cm for each electrode configuration). Potential gradient fields generated by the electrode configurations were markedly uneven, with a 15-27-fold change from lowest to highest gradient, with the greatest decrease in gradient occurring near the shock electrodes. Although gradient fields varied with the electrode configuration, all configurations produced weak fields along the right ventricular base. Early sites of epicardial activation after all unsuccessful shocks occurred in areas in which the field was weak; 87% occurred at sites with gradients less than 15 V/cm. Ventricular tachycardia originating in high gradient areas near shock electrodes followed 11 of 67 successful shocks. CONCLUSIONS: These data suggest that 1) defibrillation fields created by small epicardial electrodes are very uneven; 2) achievement of a certain minimum potential gradient over both ventricles is necessary for ventricular defibrillation; 3) the difference in shock strengths required to achieve this minimum gradient over both ventricles may explain the differences in DFTs for various electrode configurations; and 4) high gradient areas in the uneven fields can induce ectopic activation after successful shocks.

Animals↗
PubMed1990

Application of the Karhunen-Loeve expansion to evaluate regional cardiac excitation in body surface potential maps.

The authors investigated the usefulness of the Karhunen-Loeve technique applied to body surface maps to study regional cardiac excitation. Eigenvectors were derived from the body surface potential maps of 120 healthy adults using the Karhunen-Loeve expansion theory. Then, in the maps of various types of ventricular hypertrophy, each eigenvector coefficient was calculated for a statistical comparison. The first eigenvector coefficient in early QRS and the second in mid QRS were larger in patients with asymmetrical septal hypertrophy and in patients with left ventricular hypertrophy, respectively. The third was larger in patients with right ventricular hypertrophy. In the maps of patients with previous anteroseptal myocardial infarction, the second eigenvector coefficient decreased with asynergy of the anterior to apical wall, and the first decreased with the asynergy of the interventricular septum. They conclude that some eigenvector components and coefficients at particular times in the QRS are sensitive to changes in regional cardiac excitation and that they may facilitate the detection of local excitation changes such as occur in hypertrophy or infarction.

Adult↗
PubMed1990

Conduction disturbances caused by high current density electric fields.

During internal defibrillation, potential gradients greater than 100 V/cm occur near defibrillation electrodes. Such strong fields may cause deleterious effects, including arrhythmias. This study determined 1) the effects of such strong fields on the propagation of activation and 2) whether these effects were different for monophasic and biphasic shocks. Voltages and potential gradients during the shock, as well as activation sequences before and after the shock, were mapped from 117 epicardial electrodes placed over a 3 x 3-cm area on the right ventricle in six dogs. Pacing at a cycle length of 350 msec was given from a long narrow electrode on the right side of the mapped area to generate parallel activation isochrones. A monophasic shock, 10 msec in duration, or a biphasic shock with both phases 5 msec in duration was delivered 300 msec after the last paced stimulus via a mesh electrode on the left side of the mapped area as the cathode, with the anode on the right atrium. Shocks of 70-850 V were given, and the potential gradient and current density at each recording electrode were calculated from the measured potentials and fiber orientation by using a finite element method. Pacing was resumed 200 msec after the shock, and activation sequences were mapped for up to 5 minutes. Potential gradients ranged from 1 to 189 V/cm with high fields on the left side and low fields on the right side of the mapped area. Where the potential gradient was weak, the first activation sequence after the shock was similar to that before the shock, but activation blocked without conducting into areas where the gradient was greater than 64 +/- 4 (mean +/- SD) V/cm for monophasic and greater than 71 +/- 6 V/cm for biphasic shocks. These values are significantly different (p less than 0.003). The higher the potential gradient, the longer was the duration of block before conduction returned. Block duration, however, was generally shorter for biphasic than for monophasic waveforms of the same field strength. In conclusion, conduction block can follow either waveform, but biphasic waveforms cause less block than monophasic waveforms. This effect may partially explain the increased defibrillation efficacy of biphasic shocks.

Animals↗
PubMed1989

Ventricular defibrillation using biphasic waveforms: the importance of phasic duration.

Biphasic waveforms can be used to defibrillate the heart with less energy than that used by monophasic waveforms. In 14 anesthetized open chest dogs with large contoured defibrillation electrodes, the effect on defibrillation efficacy of varying the duration of the two phases of biphasic waveforms was studied. All combinations of 0, 1, 3.5, 6 and 8.5 ms duration were used for both the first and the second phase except for the meaningless case in which both durations were 0 ms. The 3.5-2 waveform (3.5 ms first phase and 2 ms second phase) was also tested. All the hearts were defibrillated with less than or equal to 5 joules using any of the 25 waveforms. However, biphasic waveforms with the second phase shorter than or equal to the first had significantly lower defibrillation thresholds than did those with the second phase longer than the first or than did monophasic waveforms of approximately the same total duration. A plot of defibrillation threshold current strength versus second phase duration for all biphasic waveforms with a 3.5 ms first phase did not produce a hyperbolic strength-duration curve as seen with monophasic waveforms. To verify these findings, defibrillation dose-response curves were obtained for the 3.5-2, 6-6 and 3.5-8.5 biphasic waveforms in another six dogs. The 50 and 80% successful voltage doses of the 3.5-8.5 waveforms were significantly higher than those of the other two waveforms, which were not different from one another.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Diagnostic value of QRST isointegral maps in detecting myocardial infarction complicated by bundle branch block.

The clinical usefulness of QRST isointegral maps (IQRST map) for detecting myocardial infarction that was complicated by intraventricular conduction disturbances was evaluated in patients with right bundle branch block (group RBBB, 64 patients) and left bundle branch block (group LBBB, 40 patients) by comparison with the normal mean IQRST map derived from 50 normal subjects. Myocardial infarction complicated the conduction disturbances in 24 of the 64 RBBB and in 18 of the 40 LBBB patients. A correlation coefficient was used for assessing the similarity of each map pattern with the normal mean IQRST map. The difference map was made by subtracting the average normal IQRST map from each abnormal IQRST map, and those differences that were less than 2 SD from the mean were retained as a significant area. The number of leads and their sum of differences were used to represent the size of the difference map. Correlation coefficients were significantly (p less than 0.001) smaller in patients with bundle branch block complicated by myocardial infarction than in patients with conduction disturbances not complicated by myocardial infarction. A significant area emerged in the difference map in all patients with myocardial infarction complicated by conduction disturbances. The emergence of a significant area revealed high diagnostic accuracy for detecting myocardial infarction in group RBBB (89.1%). The size of a significant area in a difference map was significantly larger in cases with complicated myocardial infarction than in cases with uncomplicated myocardial infarction in either group RBBB or group LBBB (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Diagnostic value of Q waves outside standard precordial lead points in left anterior myocardial infarction undetectable by standard 12-lead electrocardiogram.

Body surface potential maps were recorded for 52 patients with solitary anterior myocardial infarction and 57 normal subjects. All patients had pure anterior wall asynergy on a left ventriculogram but no diagnostic Q wave on the standard 12-lead electrocardiogram. Q wave (greater than 30 msec) distributions on the body surface of the patients and normals were compared. The frequency of Q waves in the area above V1-V2 and in the right middle chest was significantly higher in patients than in normals. The sensitivity of Q waves for asynergy in leads from both these areas was 19-60%. The positive predictive value was 67-94%. The frequency of Q waves was significantly higher in severe asynergy than in mild asynergy. A combination of two selected unipolar leads from these areas yielded a sensitivity and specificity of 33% and 95%, respectively. With a combination of three leads, these values were 42% and 93% and with four leads 48% and 88%, respectively. The results indicate that several unipolar leads from the area above V1-V2 and from the right middle chest in addition to the standard 12-lead electrocardiogram may improve the electrocardiographic diagnostic accuracy of myocardial infarction.

Electrocardiography↗
PubMed1988

Sites of origin of ventricular premature beats in patients with and without cardiovascular disease evaluated by body surface mapping.

The site of origin of ventricular premature beats (VPBs) was estimated by QRS maps and its distribution in two patient groups was studied. VPB origin was determined by comparing the body surface map of VPBs with that during electrical stimuli applied at various sites of the ventricle. Subjects were 100 patients without obvious underlying cardiovascular disease (Group N) and 289 patients with various heart diseases (Group D). Nine sites of origin of VPB were identified. In group N, VPBs of right ventricular origin were noted in 69%, those of left ventricular origin in 6%. There was a relatively high incidence of VPBs with foci estimated to be the divisions of the left bundle branch, and the age of patients with these VPBs was young. In Group D, VPBs of left ventricular origin showed a higher incidence (34.6%) and those of right ventricular origin a lower incidence (41.2%) than those in group N. The data suggest that VPBs originating from the apex and base of the ventricle strongly indicate the presence of basic heart disease and that VPBs originating in or near the divisions of the left bundle branch in younger subjects do not necessarily indicate cardiac disease.

Adolescent↗
PubMed1987

[Eigenvector analysis in body surface potential maps for evaluating right ventricular hypertrophy in primary pulmonary hypertension].

This study related the eigenvectors derived from the QRS complex in body surface isopotential maps of normal subjects to regional myocardial excitation, with special emphasis on the right ventricle. The subjects consisted of 120 normal healthy adults and eight patients with primary pulmonary hypertension and right ventricular hypertrophy (PPH). According to the Karhunen-Loève theory, eigenvectors were derived from the normal group and the eigenvector coefficient of each subject was obtained against time for the first three components. The cumulative proportion of the first three eigenvectors was 90.3% in normals and 80.2% in PPH. The first eigenvector had a peak of eigenvector coefficients early in the QRS and had a bottom late in the QRS. The peak of the second was in the middle of the QRS. The coefficients of the third eigenvector were low compared to the former two eigenvectors, and had no characteristic time pattern. PPH had a similar time pattern of coefficients in the first eigenvector, reduced coefficients in the second, and a definite peak in the mid-QRS in the third. The average eigenvector coefficient of the third eigenvector in PPH was significantly higher than those in normal subjects (p less than 0.01). We conclude that the third eignevector derived from normal subjects strongly reflects right ventricular excitation.

Adult↗