Search

Otitis media (OM) is common among young children and is related to hearing loss. We investigated the association between maternal insecticide use, from conception to the first and second/third trimesters, and OM events in children in the first year of age. Data from Japan Environment and Children's Study were used in this prospective cohort study. Characteristics of patients with and without history of OM during the first year of age were compared. The association between history of OM in the first year and insecticide use was evaluated using logistic regression analysis. The study enrolled 98,255 infants. There was no significant difference in the frequency of insecticide use between groups. Insecticide use of more than once a week from conception to the first trimester significantly increased the occurrence of OM in children in the first year (odds ratio [OR] = 1.30, 95% confidence interval [CI] 1.01–1.67). The association between OM in the first year and insecticide use from conception to the first trimester was only significant in the group without daycare attendance (OR 1.76, 95% CI 1.30–2.38). Maternal insecticide use more than once a week from conception to the first trimester significantly increased OM risk in offspring without daycare attendance.

This study aimed to clarify the effects of television/digital versatile disc (TV/DVD) viewing time and portable electronic device (PED) usage time on sleep duration and bedtime and the difference between the effects of TV/DVD and PED on sleep. The effect of TV/DVD viewing time or PED usage time on sleep duration and bedtime was analyzed using a multiple logistic regression analysis adjusted for covariates. A total of 74,525 participants were included in the analysis, using data from Japan Environment and Children’s Study. TV/DVD viewing was not associated with short sleep duration, but PED usage was associated with short sleep duration. In addition, the risk of short sleep duration increased as PED usage time increased. We also investigated the effects of sleep habits at age 1 year on sleep at age 3 years. This study showed that late bedtime at age 1 year posed a significant risk of late bedtime at age 3 years. In summary, particular caution should be paid to PED use from a child’s health perspective, and sleep habits should be focused on bedtime from the age of 1 year.

Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder that results in progressive muscle atrophy and weakness. As new therapies for SMA have been developed, newborn screening for SMA can lead to early diagnosis and treatment. The objective of this study was to gather the general population’s view on screening of SMA in newborns in Japan. A questionnaire survey was conducted on two general population groups in Japan. A total of 269 valid responses were obtained. In the general population, about half of the participants had no knowledge about SMA, and more than 90% did not know about new therapies for SMA. Conversely, more than 95% of the general population agreed with screening newborns for SMA because they believed that early diagnosis was important, and treatments were available. This study revealed that the general population in Japan mostly agreed with screening for SMA in newborns even though they did not know much about SMA. Newborn screening for SMA is promising, but it is in very early stages. Therefore, SMA newborn screening should be performed with sufficient preparation and consideration in order to have a positive impact on SMA patients and their families.

Although many of its effects have not been clarified, it is well known that the carotid sinus reflex has a profound influence on the cardiovascular system. The purpose of this paper is to investigate the effect of the carotid sinus reflex on the canine heart.The present experiments were performed on the in situ canine heart: 1) during sinus rhythm, 2) during electrically driven rhythm, and 3) during electrically driven rhythm after the administration of atropine. Before and during carotid sinus stimulation, the intracellular and surface electrograms, standard lead II electrocardiograms and aortic blood pressure were simultaneously recorded. The intracellular and surface electrograms were obtained from the epicardial surfaces of the right atrium and the left ventricle.Atrium. The duration of the membrane action potential (MAP) shortened during sinus rhythm and electrically driven rhythm. There were no significant changes in the amplitude of the MAP and the membrane resting potential (MRP). The PQ interval in the standard lead II electrocardiogram became significantly prolonged during both types of rhythm. The P amplitudes decreased during sinus rhythm. The shortening of the duration of the MAP was almost entirely inhibited by atropine.Ventricle. The duration of the MAP during sinus rhythm showedsignificant widening. The ST segment in the surface electrogram became significantly elevated during sinus rhythm and during electrically driven rhythm. The QT interval in the standard lead II electrocardiogram prolonged significantly during sinus rhythm, but less so during electrically driven rhythm. The RR interval became significantly prolonged during sinus rhythm. After atropine, the duration of the MAP widened very slightly during electrically driven rhythm.The following possibilities are discussed: Electrical behavior in atrial muscle is mainly mediated by the cholinergic nervous system. The response of the sinoatrial node is caused by cholinergic activity as well as by the decrease in adrenergic activity.The effect of carotid sinus stimulation on intracellular electrograms is more apparent in atrial muscle and in the sinoatrial node than in ventricular muscle.

The theoretical explanation of the genesis of electrocardiographic T wave is subjected to one of the most perplexing points of debate. Various hypotheses to give its explanation have been proposed by different investigators, however, their explanations would seem to be rather inadequate as compared with that of the genesis of QRS complex. For the electrical activity of the heart during depolarization, its electrical source can be equivalently represented by the electrical double layer at the border of activation wave front. Furtheremore, the activation process during depolarization can be determined by means of the intrinsic deflection on the relevant electrocardiogram, when the tracing of a unipolar or contiguous bipolar lead is obtained from the surface of the heart or from the intramural cardiac mass. On the other hand, at the time of repolarization, there is no discernible intrinsic deflection to be registered by the extracellular lead, therefore, the repolarization process can not be easily investigated by any electrogram recorded extracellularly. At the present time, the re-polarization process can be observed only at the limited portion of the heart, that is, at the individual cardiac muscle fiber of the subepicardial layer by means of the intracellular microelectrode technique. In this study, using the tracing of repolarization phase of transmembrane action potential, the electromotive force during repolarization was discussed, and the construction of normal T wave was carried out, by using the speculated difference in pattern of the transmembrane action potential of cardiac fiber in the various layers of the heart muscle. Theory and Computation : It is considered that the electrocardiogram is the total sum or the superposition of the action current generated by individual excited cardiac muscle fiber, which is a spatial and time-varying function. The transmembrane action potential of its fiber can be registered by means of microelectrode method, although its action current can not.

Genetic factors in the formation of the long R-R interval in ventricular arrhythmia associated with atrial fibrillation were investigated in the isolated rabbit heart which was perfused using Langendorff's technique. The trans-membrane action potentials recorded from a single cell within the A-V node or within its vicinity were analyzed, and contiguous bipolar-lead electrograms simultaneously recorded from the right atrium and ventricle. Atrial fibrillation was induced by the combined application of acetylcholine solution and electrical stimulation. Atrial excitation was mainly blocked in the right atrium and in the anterior half of the A-V node. To clarify further the time-correlation between the right atrial electrogram and the A-V nodal responses, the pattern of atrio-ventricular conduction was studied by applying only the electrical stimulation at high frequency without acetylcholine. The conduction was mainly blocked in the same sites as in the above experiment and the pattern of the conduction block in Wenckebach rhythm was observed. The conduction block within the anterior half of the A-V node may be the most important factor in producing the long R-R interval in atrial fibrillation. It was shown that the pattern of the conduction block can be explained by the Wenckebach rhythm.

Surface and intracellular electrograms and ventricular pressures were used to study the effects of epinephrine and propranolol on electrophysiological properties in the in situ heart of 21 anesthetized dogs. Five sec. after the infusion of epinephrine, the ST segment became slightly depressed. About 10 to 20sec. after epinephrine, the ST segment became elevated and the negative T wave became more inverted. Initially, the upward convexity of phase III of the membrane action potential deepened slightly. Phase II of the membrane action potential gradually decreased in amplitude and became prolonged in duration. Phase III of the membrane action potential increased slightly. The membrane resting potential remained almost unchanged. Intracellular electrographic changes due to epinephrine were of abnormal configuration. That epinephrine may cause anginal pain is well known. Propranolol inhibits epinephrine's effects on the electrophysiologic properties of the heart. It is thought that propranolol helps to relieve the pain of angina pectoris by decreasing cardiac work and by increasing coronary blood flow.

1. The ventricular propagation process in the right bundle branch block (RBBB) was simulated in the ventricular model stored in digital computer and its QRS complexes were reconstructed mathematically. The block was established in the model by laying a lesion on different levels along the right side of the specialized conducting system in different fashions. In total, five different assumptions in regard to the site and fashions of block were adopted, each of which corresponded to one of interpretations of RBBB obtained from animal experiment. 2. QRS complexes reconstructed from the assumptions where a conduction block was placed on the main right bundle branch showed R configuration in lead V1 and QrS in lead V5. These complexes displayed a significant changes in the initial parts in comparison with the normal simulated ones. It suggested that the rather little alteration in the initial parts of QRS complexes in clinical RBBB can not be explained by the lesion laid on the main right bundle branch. On the other hand, QRS complexes reconstructed from the assumption that excitation conducts through the main right bundle branch without block but the Purkinje system in the right ventricular free wall was not utilized for the conduction showed rsR' configuration in lead V1 and qRs in lead V5, not showing discernible change in their initial parts. 3. Based on the above results it was proposed that the QRS patterns in clinical RBBB is not attributable to the block at the main right bundle branch but a likely cause for the pattern is the conduction block at the level distal to the main right bundle branch along the right specialized conduction system.

(1) The main purpose of this communication is to introduce a newly devised experimental technique for studying electrocardiography and vectorcardiography: a canine heart perfused by means of Langendorff's technique was placed within a transparent plastic molded human torso model filled with Tyrode solution at the physiological temperature of 36°C, the heart was kept beating regularly by the sinus rhythm for more than 2 hours, and it was succeeded in obtaining recordings of the electrical activity of the heart by Frank lead system and by the conventional electrocardiographic leads.(2) This method contains advantages inherent in both the simplified physical model experiment and the in situ experiment without including disadvantages ascribed to each of the 2 experimental approaches. It can be expected that this method be adopted in many aspects of electrophysiological investigation of the heart.(3) As an application of this technique, relationship between rotation angle of the suspended canine heart and changes in QRS pattern of electrocardiogram and vectorcardiogram were investigated.