The science reports of the research institutes, Tohoku University. Ser. C, Medicine. Tohoku Daigaku最新文献

Two subcutaneous injections of N-bis(2-hydroxypropyl)nitrosamine (BHPN) to mice on day 1 and 8 induced tumors of the lung, liver, nasopharynx and pancreas, when animals were killed at the end of one year. The tumor incidences of lung were 90-100%; those of liver 60-92%; those of nasopharynx 3-13%; those of pancreas 2-3%, respectively. The average tumor nodules of lung and those of liver increased in a dose-dependent manner. Two doses of 50 mg/g body weight of BHPN induced one duct cell carcinoma and one acinar cell adenoma of pancreas in a mouse, respectively.

Chaotic behavior in cardiovascular dynamics was thought to be one of the important information to analyze the circulatory regulatory system. Several investigators studied the attractor in the signals of the electrocardiogram, and found the strange attractor, suggesting dynamics compatible with deterministic chaos, by the use of the non-linear mathematics. It is interesting problem to analyze the hemodynamic parameters by the use of non-linear mathematics for the determination of the physiologically optimal circulatory condition. In this study, Chaos analyzing system was developed to identify the deterministic chaos in cardiovascular regulatory system by the use of the non-linear mathematics including phase plane plots, embedding, and lyapunov exponents. Time series data of the hemodynamic parameters in the chronic animal experiments was analyzed by this system, and satisfactory attractor was obtained by the use of the phase plane plots and embedding techniques. Furthermore, calculation of the lyapunov exponents showed the existence of the deterministic chaos in arterial blood pressure in the chronic animal experiments using adult goats, suggesting this tool is useful for analyzing cardiovascular dynamic behavior.

The vibrating electromagnetically driven univalved artificial heart, which provided more than 10 1/min at 10 Hz/sec. vibration, was developed in our team. This vibrating electromagnetic pump (VEMP) produced the original flow pattern compared with the flow pattern of the natural heart, so that circulatory regulatory system during maintain the circulation with VEMP must be investigated before the clinical application. In order to assess the effect of high frequency blood flow produced by the VEMP from the neurophysiological point of view, power spectral analysis of the hemodynamics was performed. VEMP was implanted as the total left heart bypass in adult goats and right heart circulation was maintained by natural hearts. In arterial blood pressure during maintain circulation by the high frequency blood flow, Mayer waves (0.01-0.15 Hz) were significantly decreased, though respiratory waves (0.25-0.40 Hz) were not significantly changed. These results suggest that circulatory regulatory system was influenced by the high frequency blood flow produced by the VEMP.

Maintaining circulation with an left ventricular assist device (LVAD) alone during cardiac arrest until heart transplantation, was evaluated by the use of the sympathetic neurogram. To evaluate the influences of this method on autonomic nervous system, sympathetic neurogram was analyzed by power spectrum and coherence function. In acute animal experiments using mongrel dogs, LVAD were implanted. After the LVAD implantation, ventricular fibrillation was induced electrically. Renal sympathetic nerve activity (RSNA) was detected by the use of bipolar electrodes attached to the left renal sympathetic nerve. Values of squared coherence between the arterial pulse wave and RSNA were calculated. Under the condition of circulatory maintenance with LVAD, coherence at the cardiac rhythm frequency was decreased, and coherence at the LVAD pumping rhythm frequency was increased. These results suggest that the arterial pressure which was observed during maintaining the circulation with only LVAD contributed to sympathetic neurogram.

Idiopathic hypertrophic subaortic stenosis (IHSS) is a progressive cardiac disease known to induce sudden death occasionally. The authors tested echocardiography as a method of guiding myotomy, and observed its clinical usefulness as a safe surgical procedure for IHSS.

For patients for whom the conventional percutaneous transluminal coronary angioplasty (PTCA) did not adequately improve stenosis, or sufficient angioplasty was impossible because of occurrence of dissection, we attempted using a long-time balloon inflation for more than 10 minutes. In order to allow the use of this balloon, we instituted an active rehabilitation program using a bicycle ergometer to promote the development of the collateral circulation up to the time of performing diagnostic angiography and PTCA, while attempting to use a perfusion balloon catheter for those patients not developing sufficient collateral circulation. Of the 134 patients undergoing PTCA, unsatisfactory angiographic results were obtained in 13 patients. Of these patients, long-time balloon inflation was performed in seven and primary success was achieved in six. From this study, we believe that the long-time balloon inflation in PTCA can improve the primary success rate and reduce postoperative complications.

Effect of gravity and respiratory phase on mucociliary transport was studied in 11 normal subjects. After inhaling 99mTc-human serum albumin aerosol, each subject was positioned in right lateral decubitus and then supine position before a scintillation camera. Data in list mode and simultaneous respiratory curve were stored in a computer for 15 min each. The respiratory curve was sequentially marked at the beginning of inspiration, expiration and pause of each respiratory cycle and list mode data was converted into frame mode, respectively. The frame mode data was then sequentially connected according to the respective respiratory phase. The data in count-per-second from each lungs versus time was fitted to a straight line by regression analysis and the slope of the line was compared with each other for respective respiratory phase. Slopes of net radioactivity changes in the right and left lungs were compared to evaluate gravity effect. Neither respiratory phases nor gravity had any significant effect on mucociliary transport. Theoretical calculations have also supported the present findings.

Newly developed long time digital Holter ECG system utilizing a stamp-size non-tracking (NT) tape which can be used for 192 hours as 2ch recording, was evaluated in the clinical cases. The system has employed newly developed VLSIs and NT technology which enables to obtain reliable long time recording with smaller and lighter Holter system of ECG and variety of biological signals. The results indicated that good data reproduction was shown in this system.

beta-Lactamase activity of sputum of 39 patients with respiratory infections and that of bacterial isolates from their sputum were determined by nitrocefin method. Forty-six microbial strains (16 different species) were recovered from 39 sputum samples. The beta-lactamase activity was negative only in nine of the 46 strains. beta-lactamase-positive strains were recovered from 35 of 39 sputum samples. Of these 35 sputum samples, the beta-lactamase activity was positive in 23 and negative in 12. beta-lactamase-negative strains were recovered from 4 of 39 sputum samples, and the beta-lactamase activity was negative in all of these four sputum samples. Both beta-lactamase producing and non-producing strains were recovered in 5 of 6 sputum samples from which two to three microbes were isolated. The ratio of beta-lactamase-positive sputum sample was higher in patients who had received antibiotics than in those who had received no antibiotics. This difference was statistically significant (P < 0.025). It is possible that non-causative beta-lactamase-positive organisms enhance the pathogenicity of causative organisms that are beta-lactamase-negative.

To evaluate the various basic designs of the pump chambers used in the ventricular assist devices (VADs), hydrodynamic endurance test was performed from the viewpoint of the durability of the prosthetic valves used in the VAD. For the hydrodynamic analysis, we designed three basic types of pump (sac type, diaphragm type, and pusher plate type) using the same material and having the same capacity and shape. Prosthetic valves in these VADs were tested from the standpoint of the water hammer effect, which affects the valve durability, to determine which pump design would be most durable as a prosthetic valve in the VAD. The water-hammer phenomenon was evaluated using the maximum pressure gradient (MPG) across the prosthetic valve in the moc circulatory loop. Maximum pump output was recorded when we used the diaphragm type model, and minimum MPG in the commonly used driving condition of the VAD were recorded when we used the sac type model. The results suggest that the sac type VAD model is the most durable design for the prosthetic value.