Changes of visually evoked potential during seizure development in kindled cats

The secondarily induced changes of brain function following seizure seen in kindling preparations were studied by means of the visually evoked potential (VEP) in unrestricted cats. The kindling was developed by repeated electrical stimulation to the visual cortex under intermittent photic stimulation (IPS). Generalized convulsion was rapidly developed with a lowering of threshold inducing afterdischarge and an earlier spreading of seizure discharge to the midbrain reticular formation as compared with the previous control experiment without IPS. Following electrical stimulation, a marked enhancement in amplitude and a prolongation in latency of the second negative component, which was not usually recognized before the electrical stimulation, was observed. Such augmentation of VEP developed progressively and finally changed into the epileptic discharge accompanied with myoclonic response. Furthermore, postictal augmentation of VEP which attained to maximum within a few minutes after the end of seizure was confirmed with an elevation of photosensitivity. It was noted that the second negative component continued significantly to exist for more than 60 min contrary to the relatively rapid restoration of the first negative component. These findings are discussed in relation to the mechanism of kindling phenomenon.

A new approach to the reactive afterdischarge in the development of kindling

Simultaneously recorded multielectrode EEG data obtained during the course of amygdaloid kindling in cats were quantitatively analyzed by means of a multidimensional autoregressive model. By the use of this method, the afterdischarge was objectively separated into propagated and reactive discharge respectively in the frequency domain and it permitted the study of the progressive development of reactive afterdischarge which has been suggested to have a functional relationship with seizure development. As a result, marked augmentation and a tendency for synchronization of reactive afterdischarge were noted in the midbrain reticular formation and anteroventral part of the thalamus along with seizure development. Furthermore, a remarkable contribution to producing afterdischarges at other brain sites was revealed. Such contribution of the reticular system as a pacemaker was also shown by analysis of the background EEG. From the above findings obtained in kindling preparation of cats through multidimensional autoregressive analysis, a new approach to the mechanism of kindling phenomenon was demonstrated and a possible mechanism was also discussed.

Enhancement of cooling and rewarming by a jet water system in surface-induced deep hypothermia

To shorten the time of cooling and rewarming in surface-induced deep hypothermia, we devised a jet water system for hypothermia which was constructed within the water bath of the operating-table. In the clinical applications for open heart surgery under surface-induced deep hypothermia, we found that the time required for cooling and rewarming, particularly the later, was significantly reduced without any adverse effects.

Intra- and postoperative autotransfusion in open heart surgery under simple hypothermia in children

A new autotransfusion unit was developed by the authors and the favorable results of 21 operations of open heart surgery under simple hypothermia were described. The patients were all children with simple congenital heart diseases. The amounts of autotransfused blood ranged from 2.8 to 15.5 ml/kg. Intraoperative autotransfusion proved to be an effective means of minimizing blood loss during surgery (range 3.2 to 12.8 ml/kg) and performing open heart surgery without donor blood transfusion. Postoperative autotransfusion (range 0 to 14.3 ml/kg) served as a supplementary means of avoiding homologous blood transfusion. Among the 21 autotransfused patients, there were no complications, while two patients developed hepatitis out of 19 patients who received homologous blood in the control group.

EEG activities during kindling in frog

The "kindling" phenomenon was investigated in relation to the EEG activities in frog, Rana nigromaculata. Repetitive electrical stimulation to the unilateral hippocampus produced the following results: (1) Prolongation in duration of after-discharges (AD) and shortening of AD intervals; (2) Appearance and enhancing of spontaneous epileptiform discharges (SEDs), which were suppressed by isolation of hippocampus; (3) Increase in power and duration of background EEG with a specific frequency (9 Hz in the nontreated group and 5 Hz in the hippocampal commissural bisected group), which coincided with the half length of the AO intervals during the steady phase; (4) Marked increase in the late components with peak latencies of 25 and 50 msec in the interhippocampal impulse responses as estimated from the bilateral background hippocampal EEG through an autoregressive model, of which the former only was suppressed by commissural section, while both were suppressed by hippocampal isolation. From the above evidences obtained in frogs, it may be inferred that the brain structures, e.g., thalamus, hypothalamus, reticular formation, etc., play an important role in kindling formation and that the alteration in background EEG generating system during kindling is closely associated with the sporadic epileptiform EEG activities.

[A study of regional cerebral blood flow by intravenous injection method of Xenon-133 (author's transl)]

Regional cerebral blood flow (rCBF) was determined in man by Xenon-133 intravenous bolus injection technique. This method is of value especially for patients with stroke. The measuring system constituted of a 16 channel cerebrograph (rCBF 1656, Meditronic, Denmark) and a minicomputer (AI Electronics, Japan). Then, for an estimation of rCBF, two compartment analysis was applied in which a special computer program was used for this purpose. Amount of Xenon-133 in expired air was used for calculation, since we confirmed that Xenon-133 clearance in expired air was similar to that in arterial blood except for those patients with obstructive lung disease and so on. In normal adults, rCBF of the gray matter was 67 +/- 13 ml/100 g brain/min. (95% confidence limits). Patients who had been TIA or RIND, revealed a decrease of rCBF of 33--49 ml/100 g brain/min. bilaterally, although they did not show any clinical signs at the time of measurement. Contrariwise, two cases of Moya-moya disease showed a normal value of rCBF at their silent periods.

Right-sided cervical aortic arch associated with tetralogy of Fallot and peculiar tortuosity of the descending aorta

A right-sided cervical aortic arch, tetralogy of Fallot, and a peculiar tortuosity of the descending aorta in which the aorta formed triple loops were diagnosed by angiocardiography in a 12-year-old girl. Histologic examination of the biopsied wall of the left subclavian artery, taken at the time of a Blalock-Taussig anastomosis, revealed no elastic-tissue defect.

Hemodynamic effects of venous valves in aorto-coronary bypass grafts

Use of the saphenous vein in aorto-coronary bypass surgery for treatment of occlusive coronary artery disease is a well-established technique. Use of the mammary artery for the same purpose has also been favorably reported. This study was undertaken to determine whether a vein graft containing a valve would have an added advantage. A comparison of the effect of competent and incompetent valves in vein grafts on the hemodynamics of coronary circulation was made. In a group of 18 dogs, a 5 cm. portion of each dog's cephalic vein containing a valve was used in a single aorto-coronary bypass graft. Flow measurements were made between the valve and the anastomosis of the graft to the left anterior descending coronary artery (LAD). The valve was made temporarily incompetent by the insertion of a spring wire basket, 3.5 mm. in diameter, through the valve via a side branch. The flow of blood through the venous graft with the competent valve was 11.0 +/- 2.6 per cent higher than with the incompetent valve. An analysis of flow patterns showed that this increased flow could be attributed to a reduction of backflow during systole and an increase in forward diastolic flow. Results suggest that postoperative myocardial perfusion is enhanced by the presence of valves in aorto-coronary bypass vein grafts.