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Biomedical subjects

H Hirayama

Publications and source records attributed to H Hirayama.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Are directional coronary atherectomy and Palmaz-Schatz stent more efficacious than conventional balloon angioplasty for treating de novo coronary artery lesions?].

It is unclear whether new devices such as directional coronary atherectomy (DCA) or Palmaz-Schatz stent implantation improve long-term outcomes compared with conventional balloon angioplasty in patients with stable angina and de novo coronary artery lesions of type A or type B except for complete occlusive lesions investigated by the American College of Cardiology/American Heart Association task force on percutaneous transluminal coronary angioplasty. A total of 146 patients with stable angina and simple lesions were assigned to either conventional balloon angioplasty (62 patients), DCA (50 patients), or Palmaz-Schatz implantation (34 patients). The acute results and late outcomes were assessed by coronary angiography. The results of the three procedures were similar with respect to procedural success and complications. Patients who underwent stenting or DCA had a larger immediate increase in the diameter of the lumen and a larger luminal diameter immediately after the procedure than those who underwent balloon angioplasty. At six months follow-up, the patients treated by stenting continued to have a larger luminal diameter and a lower rate of restenosis than those treated with balloon angioplasty (2.30 +/- 0.66 vs 1.85 +/- 0.83 mm, p < 0.005; 5.9% vs 29%, p < 0.05) and DCA (2.30 +/- 0.66 vs 1.90 +/- 0.96 mm, p < 0.05; 5.9% vs 24%, NS). The patients treated with balloon angioplasty had a smaller late loss than those treated with DCA or Palmaz-Schatz stent. The patients treated with DCA had a larger loss index than those treated with balloon angioplasty or Palmaz-Schatz stent. Stenting was a significant factor in decreasing the rate of restenosis by logistic regression analysis, compared with balloon angioplasty. The angiographic outcomes were better in patients who received a stent than in those who received other treatments. This study suggests that even lesions stable for treatment by balloon angioplasty and DCA can also be treated with Palmaz-Schatz stents.

Aged↗
PubMed1996

Improved immobilization of DNA to microwell plates for DNA-DNA hybridization.

An improved and simplified protocol for DNA immobilization was developed to enhance DNA-DNA hybridization on microwell plates. Target DNA was immobilized by simple dry-adsorption. Efficiencies of DNA immobilization and retention were enhanced 1.4-6.5 times and 4.2-19.6 times, respectively, compared with a conventional method. The overall hybridization efficiency was increased 3.1-5.2 times. This simple new protocol can reduce the consumption of scarce DNA samples.

Adsorption↗
PubMed1996

Body surface distribution of significant changes in QRST time-integral values after radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome.

We analyzed 87-lead body surface QRST time-integral values (QRST values) in 29 patients with Wolff-Parkinson-White syndrome (group A, 17 patients with manifest left-sided accessory pathway; group B, 6 patients with manifest right-sided accessory pathway; and group C, 6 patients with concealed left-sided accessory pathway), before, 1 day after, and 1 week after radiofrequency catheter ablation (RCA). The number of leads with abnormal QRST values was significantly lower 1 week after RCA compared with those before RCA and 1 day after RCA in groups A and B (p < 0.05); there was no significant difference in QRST values before and 1 day after RCA in groups A and B. The QRST values over areas with preexisting repolarization abnormalities were significantly altered 1 week after RCA compared with before and 1 day after RCA in groups A and B (p < 0.01). However, there was no significant difference in the QRST values over areas without preexisting abnormalities before RCA. In group C, there were no significant differences in the QRST values or the number of leads with abnormal QRST values before, 1 day and 1 week after RCA. In conclusion, RCA did not significantly influence repolarization properties over areas without preexisting abnormalities, but gradually reduced preexisting repolarization abnormalities, which were closely related to the location of the accessory pathway in patients with manifest Wolff-Parkinson-White syndrome. Our results suggest that body surface QRST values are useful for assessment of repolarization abnormalities during the periablation period.

Adolescent↗
PubMed1996

Linear systems analysis of activating processes of complement system as a defense mechanism.

The complement system is an important element of the host defense mechanism, although its kinetics and characteristics as a system are still unclear. We have investigated its temporal changes and system properties from the view point of system engineering. The temporal changes of sequential activating processes of the system were expressed by 26 non-linear differential equations using reported values of rate constants and serum concentration for each component. The intermediate products in the activating processes increased parabolically while the membrane attack component as the final product, increased linearly. The little change in inactive precursors afforded validity for system linearization. Linear systems analysis revealed that the system which was insensitive to the changes in rate constants was unstable. The system became stable when the feed-back input from the final product was set to operate on the first step of the activating processes. Seven uncontrollable variables were insensitive to changes in rate constants or system optimization that minimized the changes in concentrations of components in the complement system. The singular values of the complement system were reduced and the impulse responses of the system were improved when the system was optimized. When stronger minimization was imposed on the changes of concentration of the components in the complement system, the singular values were reduced more, the magnitude of the impulse responses was depressed further and the responses terminated earlier than those when the elements in the weighting matrix of concentration of the components were set to be unity. By this potent minimization, the influences of changes in rate constants on the singular values were diminished. The present theoretical analysis is presented to evaluate the ability of defense mechanism of complement system.

Animals↗
PubMed1996

Analysis of nonlinear properties of immune network reactions.

On the basis of biochemical reaction dynamics, the temporal behavior of the immune network system was analyzed theoretically to promote the analysis of quantitative changes in the reactions of immune disorders and organ substitution. The idiotype immune network reaction system was expressed by 64 nonlinear differential equations that comprised four kinds of antibodies and B-cell subpopulations. All four kinds of antibodies decreased rapidly. With the progress of the reactions, they have increased gradually. The single and double bound antibodies increased rapidly from the onset of the reaction. The single-bound antibodies did not show a definite increase after the rapid increasing phase. The antibody-antibody complex increased parallel with the double bound antibodies. The effects of rate constant expand to all the immune complexes in the network system. The double bound antibodies and antibody-antibody complexes were oscillatory functions of a given antibody. Therefore, the idiotypic immune network system must be a chaotic one. The present theoretical method is available to evaluate the total ability of immune reaction system that operates as a network system.

Antibodies↗
PubMed1996

Transient giant negative T wave in acute anterior myocardial infarction predicts R wave recovery and preservation of left ventricular function.

OBJECTIVE: To investigate the value of a giant negative T wave (> or = 1.0 mV) in precordial leads of 12-lead electrocardiograms in the acute phase of Q wave myocardial infarction as a predictor of myocardial salvage. METHODS: Coronary angiographic and electrocardiographic findings, left ventricular ejection fraction in the chronic stage, and levels of cardiac enzymes were compared in patients with myocardial infarction with (group GNT, n = 31) and without (group N, n = 20) a giant negative T wave. GNT patients were divided into two subgroups according to the presence (GNT:R[+], n = 10) or absence (GNT: R[-], n = 21) of R wave recovery with an amplitude > or = 0.1 mV in at least one lead that had shown Q waves. RESULTS: The maximum level of creatine kinase and the total creatine kinase were lower in group GNT compared with group N (P < 0.05). The left ventricular ejection fraction was higher in group GNT than in group N (P < 0.05). The maximum creatine kinase and total creatine kinase were lower in GNT:R(+) than in GNT:R(-) (P < 0.01). The left ventricular ejection fraction was higher in GNT:R(+) than in GNT:R(-) (P < 0.01). The frequency of R wave recovery was significantly higher when giant negative T waves appeared within 100 h of myocardial infarction or when the maximum potential was > or = 1.4 mV. The appearance of a giant negative T wave > or = 1.4 mV had a sensitivity of 90%, a specificity of 71.4%, a diagnostic accuracy of 77.4%, a positive predictive value of 60%, and a negative predictive value of 93.8% for prediction of R wave recovery. CONCLUSIONS: The appearance of a giant negative T wave, especially within 100 h of the onset of myocardial infarction, with a maximum potential of > or = 1.4 mV, may predict a reappearance of the R wave and a better left ventricular function in patients in the chronic stage of anterior myocardial infarction.

Cardiac Catheterization↗
PubMed1996

[Colouration of toki-shakuyaku-san extract granules and the production of high-molecular compounds under heat-stress storages].

We previously suggested that the colouration (browning) of Toki-shakuyaku-san extract granules (TJ-23) was related to the Maillard reaction under heat-stress storage. In this study, we investigate the production of browning high-molecular compounds and discuss the relationships among the respective contents of these compounds, amino acids and reducing sugars and the colouration (delta E*(ab)) of TJ-23 under heat-stress conditions. As a result of the investigation, it was found that peaks corresponding to the high-molecular compounds were separated from the heat-stressed samples of TJ-23 at each molecular weight of about 5,000, 1,0000, 230,000 and 3,000,000, and especially the latter two peaks increased in areas up to about 11 times and 4 times at 60 degrees C from 10 through 90d respectively. At the same time, it was confirmed that the content of amino acids and reducing sugars decreased with an increase in storage temperature at 10d. Furthermore, it has become apparent that the content of high molecular compounds was correlated with colour differences (delta E*(ab)) of heat-stressed TJ-23, and then those compounds were related to the decreases of glucose and amino acids. From these results, we confirmed that the browning of Kampo medicines extract granules might proceed partially by Maillard reaction under higher temperature and/or longer time conditions.

Amino Acids↗
PubMed1996

Implementing public policies and services in rural Japan: issues and problems.

While the sharply increased services for the elderly in the revised Gold Plan--announced in 1994--are noteworthy, implementation of the revised Plan is expected to present numerous issues and problems, particularly in the rural areas of Japan, because of unique circumstances such as depopulation and the presence of a disproportionately large number of elderly; geographical and physical isolation; a conservative and tradition-bound political climate; and conservative attitudes of the elderly. This article examines the current state of policy implementation, identifying issues and problems that are being encountered in the rural areas of Japan. Such issues as economic and family life, health care, and service delivery for the elderly are examined.

Aged↗
PubMed1995

Absorbed dose measurements and calculations in phantoms for 1.5 to 50 keV photons.

A Monte Carlo code EGS4 expanded for low energy photon transport was validated by measuring absorbed doses in a phantom for 30 and 10 keV monoenergetic photons from synchrotron radiation. Using the EGS4 code, depth doses at 0.07 mm, 0.02 to 0.1 mm, and 10 mm in the ICRU slab phantoms were calculated for 1.5 to 50 keV photons using the updated photon cross section data PHOTX. The results show that the doses at 0.02 to 0.1 mm below 10 keV are practical indices of effective dose as calculated by others, based on the 1990 ICRP recommendations (1991).

Humans↗
PubMed1994

Comparative study of five types of IABP balloons in terms of incidence of balloon rupture and other complications: a multi-institutional study.

The Multi-Institutional IABP Balloon Study Group in Japan (14 institutions) conducted a retrospective nonrandomized study to elucidate the incidence and type of IABP balloon-related complications relative to design and durability of five different clinically available balloons: TMP (n = 960), Kontron (n = 943). Datascope (n = 485), Mansfield (n = 226), and Aries (n = 189) balloons. A total of 2,803 patients (1,973 males, 830 females, mean age 62.1 years) spent a total of 243,856 h on the pump. Forty-nine balloons (1.7%) ruptured as recognized by the appearance of blood in the catheter (39 cases) or console alarm (4 cases). Ten patients required surgical removal of the balloon due to entrapment. Other IABP balloon-related complications requiring surgical intervention or with a lethal outcome occurred in 89 patients (3.2%). They included lower limb ischemia (61 cases), hematoma (11 cases), extensive dissection (6 cases), perforation (5 cases), entrapment without balloon rupture (3 cases), and mesenteric infarction (3 cases). The incidence of rupture, other major complications, and total complications, respectively, for each balloon was 0, 2.7, and 2.7 for TMP, 1.6, 4.3, and 5.9% for Kontron, 4.1, 1.9, and 6.0% for Datascope, 1.3, 2.7, and 4.0% for Mansfield, and 5.8, 3.7, and 9.5% for Aries. In conclusion, the TMP balloon demonstrates a significantly lower rate of rupture while the incidence of other complications for the 5 balloons is not significantly different.

Equipment Failure↗
PubMed1994

Long-term efficacy of acute thrombolytic therapy for myocardial infarction.

We conducted a retrospective study (1981-1990) to determine whether the efficacy of intracoronary thrombolysis (ICT) could be evaluated from data obtained solely after recanalization. We investigated 55 successful ICT patients (38 with anterior and 17 with inferior myocardial infarction (MI)), and 31 control infarct patients without recanalization. The total serum creatine phosphokinase release (sigma CPK), the extent of infarction measured by T1-201 single photon emission computed tomography (total DS) and the disturbance of regional wall motion (asyn.%) were investigated as parameters for distinguishing the successful ICT and control groups. Discriminatory ability for the two groups was highest with the total DS in all patients. Only the total DS differed significantly between the two groups in patients with inferior infarction. Misidentification of control patients as successful patients was least frequent (25.5%) when using the total DS. These findings suggest that the effectiveness of ICT for acute MI may be assessed on the basis of data obtained solely after recanalization, with the total DS being particularly useful.

Adult↗
PubMed1994

A prospective study for validation of Bayesian prediction approach to adjust individual lidocaine dosage.

A Bayesian approach, in which the estimates of the population pharmacokinetic parameters of lidocaine reported by Vozeh et al. [1984 a and b] and one measurement of serum lidocaine concentration as feedback information were utilized, was prospectively evaluated in 20 Japanese patients. The concentration of lidocaine in serum sampled from each patient at 1.5 to 3 hours after the commencement of i.v. lidocaine therapy was measured and the most likely pharmacokinetic parameters of that patient were predicted by the Bayesian program for microcomputer. Having the predicted parameters, we got the concentrations of lidocaine at 12 and 24 hours (C12 and C24) after starting the therapy within the recommended therapeutic range (2-5 micrograms/ml) by adjusting the individual dosage. As a result, the values of C12 and C24 remained within the therapeutic range in all patients and in all except one, respectively. The mean % prediction error (measured minus predicted concentration standardized by measured one) and its 95% confidence interval were 1.8% and -11.4 to 14.7% for C12, and -2.3% and -11.9 to 7.4% for C24, showing that the prediction of both C12 and C24 was not biased. The correlation coefficients between the measured and predicted concentrations were 0.574 for C12 and 0.721 for C24 (p < 0.01). From these findings, the present Bayesian method implemented with the estimates of pharmacokinetic parameters in a Swiss patient population is useful for sufficiently accurate and precise assessment of individual dosage requirement within a few hours after starting lidocaine therapy.

Acute Disease↗