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Biomedical subjects

N Suzumura

Publications and source records attributed to N Suzumura.

At least 19 recordsLinked to original sources
PubMed1991

Individual custom-designed modelling for the finite element method to be used in the forward calculation of a body surface isopotential map.

Body surface potential maps differ considerably in their pattern even among normals, depending upon torso configuration. Thus individualized modelling of the heart-torso model is certainly desirable for a forward problem if it can be achieved without much effort. In this paper such a heart-torso model which is flexible enough to adapt to different body shapes with ease will be reported. As its basic structure, the innermost sphere represents the electromotive force of the heart, the outermost ellipsoid surface representing the torso surface and nine similar ellipsoid surfaces intervening between the two with step-wise increasing diameters were considered. We made 98 radiating penetration points for the innermost sphere as well as the 10 intervening ellipsoid surfaces. By making use of neighboring points of penetration as corners, the heart-torso model was divided into 4992 tetrahedral elements for a finite element method calculation. Once this basic structure was established, it was found to be very easy to be modified in a computer in order to make it fit to individual torso configurations quite faithfully by deforming the outermost ellipsoid. Individualized torso-heart models were built and their maps were simulated using data obtained from several healthy subjects. This paper discusses the results of two individuals, one muscular and the other slender, who exhibited considerably different body surface potential maps.

Adult↗
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↗
PubMed1989

Difference in content ratio of components among horse serum transferrin variants.

Each of five genetic variants of horse serum transferrin (Tf), D, F, H, O, and R, was separated into two bands by polyacrylamide gel isoelectric focusing (PAGIEF). The more acidic band, termed component a, was more abundant than the other one, termed component b, in all variants. Components a and b of TFO variant were immunologically indistinguishable from each other by double immunodiffusion test. Determination of the content ratio of component a to component b in each variant revealed that the variants were classified into two groups: one group (D, F, and H) had a relatively high ratio within a range from 3.4 to 4.0 and the other group (O and R) had a relatively low ratio of 1.8 to 2.3. From these results and reference data on carbohydrate compositions of components a and b, it was proposed that there is a difference in glycosylation between the two groups.

Animals↗
PubMed1989

[Changes and stability of the cant of occlusal plane following orthodontic treatment].

The purpose of this study was to investigate the changes of the cant of occlusal plane during and after orthodontic treatment. Materials consisted of lateral roentgenocephalograms of 42 patients treated with full brackets system. Cephalograms were taken at following 4 stages; the beginning of orthodontic treatment, the beginning of retention, the end of mechanical retention and 3 years after the end of retention. Measurements were done at following angles and distance. 1. SN--occlusal plane angle 2. palatal plane--occlusal plane angle 3. mandibular plane--occlusal plane angle 4. Xi point--occlusal plane distance The results were as follows: 1. The SN-occlusal plane angle tended to decrease as time passed, although the pattern of the changes was different among Cl. I, Cl. II and Cl. III groups. 2. The changes of the occlusal plane mainly occurred within the limit of alveolar process. 3. Extension line of the occlusal plane tended to be close to the Xi point as time passed. 4. When the SN--occlusal plane angle was changed largely during the orthodontic treatment, it tended to relapse more after treatment.

Adolescent↗
PubMed1989

[Coagulation disorders during orthotopic liver transplantation].

Coagulation disorders have been noted during orthotopic liver transplantation (OLT) especially just after reperfusion of the grafted liver. This study was undertaken to clarify the coagulation disorders following reperfusion of the liver graft. OLT was carried out in adult mongrel dogs using a cuff technique. Fresh and 24-hour preserved livers were grafted. Platelet count (P1), activated partial thromboplastin time (A-PTT), prothrombin time (PT) and plasma fibrinogen levels (Fng) were measured before and after OLT. Next perfusate obtained from fresh livers or preserved livers for 24-hours or 48-hours was determined for their ability of inducing coagulation disorders when infused in untreated dogs, and was also tested for their activity of platelet aggregation, tissue thromboplastin (F-III), and plasminogen activator (PA). All dogs which received preserved livers showed a marked coagulation disorders including a decrease in P1 and Fng, and prolongation of A-PTT and PT, but the dogs with fresh liver grafts did not. Infusion of the perfusate collected from a perfusion of the preserved liver induced similar coagulation disorders in untreated dogs. The perfusate obtained from the preserved liver showed significant increased F-III activity as compared with that from fresh liver. On the other hand, neither direct platelet aggregation activity nor PA activity was seen or very low if any. These results indicate that F-III liberated from a damaged liver is responsible for the coagulation disorders after reperfusion of the graft in liver transplantation.

Animals↗
PubMed1986

Automatic reregistration for correction of localized misregistration artifacts in digital subtraction angiography of the head and neck.

A new automatic computer program, to remove misregistration artifacts secondary to motions such as rotation, contraction and relaxation of the body, has been developed. This program is called automatic reregistration and consists of determination of distortion vectors of corresponding segments of the mask and live images by detection of the peak value of two-dimensional cross correlation, followed by obtaining distortion vectors of other pixels through interpolation. Shift of the coordinate of the distorted live image is subtracted. Clinical evaluation of this new program, in comparison with already developed remasking and manual reregistration, have proved that some misregistration artifacts, uncorrectable by the latter two methods, have been removed to some extent. The new program has proven to be clinically useful.

Angiography, Digital Subtraction↗
PubMed1978

On the stationarity and normality of the electroencephalographic data during sleep stages.

In this paper, we show techniques to examine the stationarity and the normality of time series as well as results obtained by applying these techniques to EEG data during sleep stages. Many statistical analyses of the EEG data are based on the assumption that the EEG data are stationary and normally distributed. However, the problem is to know the length of data which is most appropriate for the statistical analysis. From the analysis, it is found that a decreased length of data implies an increased degree of stationarity and normality in each stage of sleep. However, for the practical stationary analysis of EEG data, it is shown that it is appropriate to take about 5 s during sleep state. Stationarity is fulfilled to a relatively large extent in REM but more seldom in stage 2. In the case of short data, asymmetric distribution occupies the large parts of non-normal distribution. As the length of data increases the proportion which is symmetric but sharper or flatter than the normal distribution increases.

Computers↗
PubMed1977

Stationarity and normality test for biomedical data.

Biomedical data, such as EEG, EMG and neural impulse sequences, are regarded as the stochastic phenomena of biological systems, and the statistical properties of such time series are often examined. Most of the statistical analysis processed in the frequency and the time domain are based on the assumption that the time series is weakly stationary and normally distributed. Therefore, as the basis of the statistical analysis of the biomedical data, it is necessary to know whether they satisfy the conditions of weak stationarity and normality. However, impulse response and evoked potential biomedical data, are not regarded as the stationary time series. Therefore, other analysis is required. In this paper, the authors present four programs, TEST1, TEST2, TEST3 and TEST4, to examine above conditions. Furthermore, in order to clarify the characteristic of each program, the time series were generated by the computer and examined by the test programs.

Diagnosis, Computer-Assisted↗