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Biomedical subjects

T Yanaga

Publications and source records attributed to T Yanaga.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Pituitary hormone responses to exercise at high altitudes].

The secretory responses of the anterior pituitary hormone to physiological stress were studied in healthy male volunteers. Measurements of blood LH, FSH, Prolactin, GH, ACTH, lactate, pyruvate and hematocrit were made from blood samples taken at rest, after 15 minutes at sea level, and at an altitude of 4000 m and 5500 m modulated in a climate-controlled room. The results are summarized as follows: Blood levels of Prolactin and ACTH were increased after exercise at a high altitude. Blood levels of LH and FSH after exercise at each altitude were not significantly different from those at rest. Blood GH level was increased after exercise at any altitude. Blood levels of lactate and pyruvate were increased after exercise at any altitude. These results suggest that the secretory response of the anterior pituitary hormone to physiological stress is prominent in Prolactin, GH and ACTH but not in FSH and LH.

Adrenocorticotropic Hormone↗
PubMed1984

Influence of glucocorticoids on brain serotonin metabolism in rats.

It has been suggested brain serotonin (5HT) plays a role in regulation of the hypothalamic-pituitary-adrenal system, although none of the experimental approaches so far reported has produced unequivocal results, mainly on account of the static tissue 5HT level or the known effects of drugs being employed in interpretation of their data. The present study in rats of the possible feedback influence of glucocorticoids on the brain 5HT was designed to analyze the dynamic turnover of its metabolism. Intracisternal injection of corticosterone (COR) caused no significant changes in 5HT content but increased its turnover dose-dependently in the cortex-cerebellum and the rostral brain stem including the hypothalamus, and lowered the serum COR level at doses less than 5.0 micrograms/kg, reducing its effect with increasing doses. Intracisternal or intraperitoneal administration of miliary doses of dexamethasone (DEX) decreased 5HT turnover in the same brain portions. The effects of glucocorticoids on the brain 5HT metabolism were more potent when injected intracisternally, especially onto the rostral brain stem. Although COR and DEX played controversial roles, the present results suggest that adrenal glucocorticoids may directly act on brain 5HT metabolism and there may be a feed-back relation between adrenal glucocorticoid and brain 5HT.

Animals↗
PubMed1984

Well-controlled comparative study of the clinical effectiveness of intravenous mexiletine and procainamide on ventricular premature contraction.

In a well-controlled study the clinical efficacy of a single intravenous injection of mexiletine (3 mg/Kg) on ventricular premature contractions was compared with that of procainamide (10 mg/Kg) using continuous electrocardiographic recordings. Of the 56 subjects studied, 55 were analyzed. These consisted of 28 cases in the mexiletine group and 27 in the procainamide group. The backgrounds of both groups were considered to be equivalent. Effectiveness on VPC ("marked and moderate improvement", as judged by the subcommittee) was seen in 88% of the mexiletine group and 84.6% of the procainamide group. This difference was not significant. The duration of efficacy was almost the same in the 2 groups. Overall improvement was the same as improvement in VPC. No significant difference was observed in the incidence of side effects. Five patients in the mexiletine group and 3 in the procainamide group reported side effects. The main side effect was light-headedness in the mexiletine group and a decrease in blood pressure in the procainamide group. A decrease in blood pressure was observed in 1 case in the mexiletine group but this was restored by an intravenous infusion of noradrenaline. Mexiletine had little effect on blood pressure, while procainamide induced a drop in the systolic pressure. This difference was significant. Overall utility ("markedly and moderately useful", as judged by the subcommittee) was seen in 84.0% of the mexiletine group and 84.6% of the procainamide group. There was no significant difference between the 2 groups. From the above results, it is concluded that mexiletine (3 mg/Kg) is as efficacious as procainamide (10 mg/Kg) in the treatment of VPC but that, unlike procainamide, mexiletine has little effect on blood pressure.

Adolescent↗
PubMed1983

Studies of arrhythmias by 24-hour polygraphic recordings: relationship between atrioventricular block and sleep states.

The relationship between AV conduction disturbances and sleep states was investigated using continuous polygraphic recordings for one full night. The results were as follows: (1) In the case of first-degree AV block, the phasic shortening of the PQ interval was observed during rapid eye movement (REM) sleep. (2) In the case of second-degree AV block (Wenckebach type), the conduction ratio increased transiently during REM sleep and significant relationships were observed between the number of nonconducted P waves and the mean heart rate in each sleep stage. (3) In the case of advanced AV block, complete AV block was observed less frequently during REM sleep and the period of falling asleep. Since the reproducibility of these results from night to night has not yet been investigated, additional evaluation is required.

Adolescent↗
PubMed1983

The usefulness of Holter monitoring in the evaluation of antiarrhythmic drug efficacy for tachycardia.

Using Holter monitoring tachycardia was found in 145 out of 2058 patients suffering from various underlying diseases. Three thousand seven hundred and forty monitorings were performed. The mean age of patients was 54.5 years with a range of 19 to 83 years. The observed tachycardia was classified into three types: tachycardia with short duration, tachycardia with long duration and tachycardia with complex form. The attacks of tachycardia were more frequently observed during periods of physical activity than during sleeping periods. The relationship of the number of tachycardia with short duration between 24-hour Holter monitorings was examined in order to establish day to day variability of the attacks. The 95% confidence interval about the resultant regression line was calculated and the percent reduction required for the evaluation of drug efficacy to avoid the chances of interference of spontaneous variation was found to be about 44.0, 55.0 and 82% when the total number of attacks during a 24-hour period were 50, 100 and 1,000, respectively. Holter monitoring showed higher positive results as compared to exercise testing for detection of tachycardia. Higher correlation coefficients between numbers of premature ventricular contractions (PVCs) and the plasma concentrations of procainamide or N-acetylprocainamide were observed in 3 or more successive PVCs than in individually occurring PVCs. Using repeated 24-hour Holter monitorings a significant reduction in the number of tachycardia was observed when the therapeutic concentration was reached after the combined or single administration of the drug. These results suggest that repeated Holter monitorings, exercise testing and determination of plasma level of the drug may be useful for the evaluation of antiarrhythmic drug efficacy for tachycardia.

Adult↗
PubMed1982

Significance of the automaticity recovery phase following tachycardic overdrive.

The usefulness of automaticity recover time (ART) and automaticity recovery phase (ARP; the time requiring P-P cycles to return to the original P-P cycles following the termination of tachyarrhythmias) for evaluating the sinus node function was studied in 24 patients with tachyarrhythmias by recordings of 24-hour continuous electrocardiograms. Automaticity recovery time was not so valuable in evaluating sinus node function because the overlap of ART was observed between patients of normal sinus node function and patients with sick sinus syndrome. The pattern of ARP was classified into 4 types (I--IV). Type I showed qUick return to the original P-P after overdrive suppression, type II was characterized by first suppression and secondary acceleration, type III was the pattern characterized by repeated suppression after tachycardiac overdrive, and type IV was characterized by repetitive appearance of tachyarrhythmia and bradycardia. The period of each ARP was measured and the period of type II (42.2 +/- 16.6 sec) or III ARP (48.4 +/- 21.4 sec) was significantly longer than type I (22.1 +/- 11.1 sec). Type III ARP was considered to suggest sinus node dysfunction. In conclusion, it was suggested that not only the observation of ART but also ARP were valuable for evaluating more precise sinus node function. The observation of ARP is easily obtained from 24-hour continuous recordings of electrocardiograms.

Adolescent↗
PubMed1982

Observations of the effect of arrhythmias on the cerebral function by recordings of 24-hour continuous electrocardiograms. Comparison between the sick sinus syndrome and atrio-ventricular block.

The influence of arrhythmias on cerebral function was investigated in 8 patients with sick sinus syndrome (bradycardia tachycardia syndrome) and 8 patients with advanced or complete atrioventricular block using 24-hour continuous recordings of the electrocardiogram and conventional electroencephalogram recordings. Syncope was observed more frequently in the atrio-ventricular block group, and was observed frequently when the longest heart beat pause during a 24-hour day was longer than 2.2 sec. Cerebral infarction as a complication of these arrhythmias was observed only with the sick sinus syndrome group. The maximum heart rate during a 24-hour day and the difference between maximum and minimum heart rate were significantly lower in the atrioventricular block group than in the sick sinus syndrome group. The electroencephalogram results showed a slight slowing of the background activity and the appearance of slow wave bursts in both groups. These abnormal findings were improved during intracardiac pacing in the atrio-ventricular block group. A quantitative analysis of the frequency of the electroencephalogram at various heart rates demonstrated the optimum pacing rate for the cerebral function. These results suggest that both the cerebral function and the cardiac function must be considered in the treatment of patients with bradycardia arrhythmias.

Adult↗
PubMed1982

Sleep and night-type arrhythmias.

The relationship between arrhythmias and sleep states was investigated in patients with night-type arrhythmias, which were detected by 24-hour electrocardiogram recordings using the Holter Avionics system. These patients were examined using all-night polygraphic recordings and sleep states were divided in to 5 groups according to the standard sleep stage scoring manual as stage I, II, III, IV, and REM sleep. Patients were divided into 5 groups: (1) grade 2 ventricular premature contractions (VPCs), (2) grade 4a VPCs, (3) grade 4b VPCs, (4) supraventricular premature contractions, and (5) paroxysmal tachyarrhythmias such as paroxysmal atrial fibrillation or paroxysmal supraventricular tachycardia. The paroxysmal tachyarrhythmia group showed a significant increase in arrhythmia incidence during REM sleep (p less than 0.05). However, the subjects with other arrhythmias showed no significant increase during REM sleep, but grade 2 VPCs showed a tendency to increase in sleep stage IV (0.05 less than p less than 0.1). These results suggest that there are 2 types of arrhythmias influenced by sleep. The first type is affected by a phasic increase in sympathetic nervous tone during REM sleep and the second type is related to an increase in vagal tone during the night.

Adolescent↗
PubMed1981

Usefulness of 24-hour recordings of electrocardiogram for the diagnosis and treatment of arrhythmias with special reference to the determination of indication of artificial cardiac pacing.

Twenty-four-hour recordings of electrocardiogram (ECG) were obtained from 1528 subjects. Sick sinus syndrome (SSS) was observed in 34 and advanced or complete AV block (CAVB) in 13 subjects. During the period studied 21 patients had died, who showed complicated ventricular premature contractions in 9 (multiform 6, short run 2, repetitive 2). Seventy-three patients with artificial cardiac pacing who were admitted at three different institutions were analyzed. The discrepancy of degree of block was observed between His bundle electrocardiographic findings and 24-hour ECG recordings. In 15 patients there was no correlation between sinus node recovery time following overdrive suppression and pauses following the termination of tachycardia (r = 0.0896, N. S.). In 49 normal subjects 24-hour heart rate ranged from a high of 170 to a low of 36 beats/min. Longest R-R interval ranged from 2.08 to 0.86 sec (mean 1.25 +/- 0.22 sec). The critical level of longest R-R interval to differentiate between normal group and groups with SSS or CAVB was about 1.6 sec. Above results suggest that Holter monitoring permits a precise diagnosis of arrhythmias and that both HBE and Holter monitoring should be used for the determination of pacemaker implantation especially in those with syncope or dizziness but without evidence of marked bradycardia.

Adolescent↗