Shoji Noda

ESR and Optical Studies of Acyl Radicals Produced from Acyl Chlorides by Dissociative Electron Attachment in γ‐Irradiated Organic Glasses at 77°K

Dissociative electron attachment by acyl chlorides in γ‐irradiated organic glasses at 77°K has been investigated by ESR and optical absorption measurements. The MTHF and 3MP glasses containing acyl chlorides (CH3COCl, C2H5COCl, C6H5CH2COCl, C6H5COCl, C6H5CH=CHCOCl) display a similar ESR singlet. 3‐Methylpentane glass containing CH3COCl exhibits an ESR singlet or triplet depending upon solute concentration. γ‐irradiated MTHF glasses containing these solutes give the optical absorption spectra having the characteristic absorption bands in the visible and uv region. These ESR and optical absorption spectra have been assigned to acyl radicals. Illumination of γ‐irradiated samples with visible light yields alkyl radicals from CH3CO· and C2H5CO·, benzyl radicals from C6H5CH2CO·, and brings about no change in C6H5CO· and C6H5CH=CHCO·. The decay of alkyl radicals formed in 3MP has been measured at 77°K.

Effects of a new vasodilator, nicorandil, on exercise-induced impairment of left ventricular function in patients with old myocardial infarction.

Hemodynamic effects of nicorandil on exercise-induced impairment of left ventricular function were studied in nine patients with old myocardial infarction but without angina pectoris. Hemodynamic data were obtained by symptom-limited supine multistage bicycle ergometer exercise testing before and 1 h after single oral administration of 15 mg of nicorandil. Systolic and diastolic blood pressure at rest decreased significantly after nicorandil administration (p < 0.01). A most remarkable change in the hemodynamic response to supine dynamic exercise after nicorandil was a decrease in pulmonary artery wedge pressure (both at rest and at peak exercise, p < 0.001). An index of cardiac function, obtained from the relation between pulmonary artery wedge pressure and left ventricular stroke work index, improved significantly after nicorandil. The ratio of pressure-rate product to coronary sinus flow, which is an index of the ratio of myocardial oxygen consumption to myocardial oxygen supply, decreased significantly (p < 0.05) after nicorandil administration. Reproducibility of the testings was also studied in six patients with old myocardial infarction. Invasive hemodynamic variables between two successive symptom-limited supine leg exercise testings, except pulmonary artery wedge pressure, were reproducible in patients with old myocardial infarction but without angina pectoris. Only pulmonary artery wedge pressure at rest in the second exercise testing showed a significantly lower value (p < 0.05). It is concluded that nicorandil is a useful drug for improvement of exercise-induced impairment of left ventricular function with an increase in myocardial oxygen supply.

Effects of isosorbide-5-mononitrate on exercise-induced hemodynamic changes in angina pectoris

Hemodynamic effects of isosorbide-5-mononitrate (ISMN) were studied in 14 patients with effort angina pectoris. Hemodynamic and echocardiographic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and 120 minutes after single oral administration of 20 mg of ISMN. Compared with control exercise testing, the ST segment at peak exercise showed less depression after administration of ISMN (p less than 0.001). At rest, systolic and diastolic blood pressure decreased significantly after administration of ISMN (p less than 0.001 and p less than 0.01, respectively). At rest and at peak exercise, pulmonary artery wedge pressure (both p less than 0.001), left atrial volume (both p less than 0.001) and left ventricular end-diastolic volume (both p less than 0.05) decreased, whereas cardiac index, pressure-rate product and systemic vascular resistance did not change significantly after administration of ISMN. Average time to peak plasma ISMN concentration was 90 minutes and average peak plasma concentration was 460 ng/ml with an elimination half-life of 7 hours. These data suggest that the main mechanism of the antianginal action of ISMN is a reduction in left ventricular preload followed by diminution of myocardial oxygen requirements.

Effects of a new second generation calcium channel blocker, nilvadipine (FR34235), on exercise-induced hemodynamic changes in stable angina pectoris.

The mechanism of the antianginal actions of nilvadipine was investigated in 11 patients with effort angina pectoris. Hemodynamic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and after a single 6 mg dose of nilvadipine. Compared with chest pain during control exercise testing, pain at peak exercise disappeared or abated and the ST segment at peak exercise also showed less significant depression after administration of nilvadipine. At rest and at peak exercise, mean blood pressure, pulmonary artery wedge pressure and systemic vascular resistance decreased significantly, whereas heart rate and cardiac index increased significantly after nilvadipine. Rate-pressure product and stroke volume index did not change significantly. Coronary sinus flow at peak exercise increased significantly and total coronary vascular resistance at rest and at peak exercise decreased significantly after nilvadipine. The plasma concentrations of nilvadipine 1.5 hours after administration ranged from 1.15 to 8.23 ng/ml. These data suggest that the principal factors in the antianginal actions of nilvadipine are an increase in myocardial oxygen supply due to increased coronary blood flow and a reduction in myocardial oxygen demand mainly by a decrease in afterload and additionally by a decrease in preload.

Prognostic value of abnormal postexercisesystolic blood peessure response: Prehospital discharge test after myocardial infarction in Japan

To assess the prognostic value of an abnormal postexercise response in systolic blood pressure (SBP), treadmill exercise testing was performed in 217 survivors of acute myocardial infarction at an average of 9.3 weeks after infarction. During the mean follow-up period of 4 years, cardiac events were noted in 34 patients (16%), including cardiac death in 13 (6%), nonfatal reinfarction in 12 (6%), and coronary artery bypass graft surgery in nine (4%). An abnormal postexercise SBP response was defined as the ratio of SBP at 3 minutes of recovery to peak exercise SBP of 0.9 or more, on the basis of the cutoff point with the highest sensitivity and specificity to predict cardiac events. An abnormal postexercise SBP response occurred in 90 patients (42%). Patients with an abnormal postexercise SBP response had more exercise-induced myocardial ischemia. more left ventricular impairment, and more extensive coronary artery lesions than those without. Cox proportional hazards model demonstrated that the abnormal postexercise SBP response was ranked first in ability to predict cardiac death (p = 0.025, relative risk 15.41). Bypass surgery was associated with an abnormal postexercise SBP ratio (p less than 0.05). Nonfatal reinfarction could not be predicted by any clinical or exercise variables. In conclusion, an abnormal postexercise SBP response could be useful for predicting cardiac death and the need for bypass surgery after myocardial infarction. This response is probably the result of myocardial ischemia and left ventricular impairment.

Usefulness of rate responsive atrial pacing in patients with sick sinus syndrome.

We studied heart rate response and blood lactate changes during treadmill exercise testing in 10 patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction in whom an activity detecting multi‐programmable rate responsive pacemaker was implanted for atrial pacing (AAI pacing). Treadmill exercise testing was performed twice in each patient under the two different AAI pacing modes: rate responsive function off (fixed rate 60 pulses per minute [ppm]; RR‐off) and rate responsive function on (rate response 10, activity threshold medium, basic rate 60 ppm, and maximum rate 150 ppm; RR‐on). Chronotropic response and blood lactate change during exercise were compared among patients under each pacing mode and eight healthy volunteers of ages matching those of the patients. In patients under the RR‐off pacing mode (RR‐off patients), chronotropic response was lower (P < 0.01) and blood lactate level was higher (P < 0.05) than those in patients under the RR‐on pacing mode (RR‐on patients) and volunteers during exercise. In RR‐on patients, however, both chronotropic response and lactate level changes during exercise were comparatively improved, with no significant differences between RR‐on patients and volunteers. These data suggested that improvement of chronotropic response by rate responsive pacing, in comparison with nonrate responsive pacing, increased the blood supply to the working muscles and resulted in less lactate production during exercise. It was concluded that rate responsive AAI pacing which could maintain AV synchrony and normal intraventricular conduction was an optimal physiological pacing mode for SSS patients with normal AV conduction.

Correlation between the direction of the interventricular septum estimated with transmission computed tomography and the initial QRS vectors.

A correlative study was performed to relate the interventricular septal angle (As degrees) evaluated by transmission computed tomography to the azimuth of initial QRS vectors in 52 patients. Patients were divided into five groups: RV volume overloading (RVO), RV pressure overloading (RSO), LV volume overloading (LVO), LV pressure overloading (LSO), and normal control with no cardiopulmonary disease. For measurement of As degrees, the leftward and forward directions were designated as zero and 90 degrees, respectively. The mean value of As degrees was significantly smaller in RVO (14.4 degrees) and RSO (41.1 degrees) than in normal controls (50.4 degrees) and in LVO (53.2 degrees). The mean value of the azimuth of the initial 12-msec instantaneous QRS vectors (H 12 degrees) was significantly smaller in RVO (80.5 degrees), RSO (81.7 degrees), and LSO (81.3 degrees) than in normal controls (113.8 degrees and in LVO (113.7 degrees). A significant linear correlation was shown between As degrees and H12 degrees in a combined group consisting of RVO, LVO, and normal controls (r = 0.70, p less than 0.001), and also in another combined group consisting of RSO, LSO, and normal controls (r = 0.52, p less than 0.01). It was concluded that the orientation of the interventricular septum was one of the major determinants of the direction of initial QRS vectors, especially in patients with ventricular volume overload or without cardiopulmonary disease.

Free radical intermediates in the photoreduction of p-benzoquinone in ethanol solution

To gain deeper insight into the mechanism of photoreduction of p-benzoquinone in ethanol, free radicals from solvent ethanol have been studied by means of e.s.r. using phenyl-N-t-butyl nitrone as a spin trap, and compared with supplementary results for semiquinone intermediates and the final photoreduction products. Ethoxyl radical and p-benzosemiquinone anion have been detected as primary intermediates. The efficiency of their formation can be correlated with the absorption spectrum of the quinone. These results support an ‘anionic mechanism’ for the photoreduction of the quinone to the hydroquinone. The photo-induced one-electron transfer results in the formation of the ethanol positive ion and the semiquinone anion, the former is transformed into the ethoxyl radical by rapid proton transfer, the latter into a dinegative ion by a disproportionation reaction, and this is protonated to give the final product, hydroquinone.

Trapped electrons in alkylamine glasses at 77°K

Abstract Trapped electrons produced in γ-irradiated alkylamins glasses at 77°K have been observed by ESR and optical absorption. It has been found that a correlation exists between the ESR linewidth and the wavelength of maximum absorption in the optical spectrum. It is also shown that the ESR and optical results obtained are related to the type of amine.

A MODEL FOR THE SOLVATED DIELECTRON IN DIELECTRIC MEDIA

A continuous dielectric model is presented for the solvated dielectron in dielectric media. On the basis of this model, the energy levels, excitation energy and charge distribution of the solvated dielectron in liquid ammonia have been calculated using the electronic adiabatic approximation. An estimation has also been made of the heat of reaction for electron pairing in this system.