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Biomedical subjects

K Seto

Publications and source records attributed to K Seto.

At least 145 records · Page 8Linked to original sources
PubMed1983

Influence of lesions of the limbic-hypothalamic system on adrenocortical responses to daily repeated heat exposures in rabbits.

The effects of lesions in the basal medial hypothalamus and limbic structure upon the responses of adrenocorticoids formation in adrenal slices of rabbits to daily repeated heat exposures has been investigated. (1) The adrenocortical responses to heat exposure on the 1st day were decreased by lesions in the periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) There were no effects of heat exposure on the 10th day upon the adrenocorticoid formation in either the sham-lesioned rabbits or the rabbits with the lesions of ARC, VMH and ST. (3) In rabbits with the FX lesions, the adrenocorticoids formation was significantly increased by heat exposure on the 10th day. (4) These results suggested that the basal medial hypothalamus, amygdala (AMYG)-ST system and dorsal hippocampus (HPC)-FX system participated in the mechanisms of adrenocortical responses to heat exposure on the 1st day, but only the HPC-FX system played some roles in complete disappearance process of adrenocortical responses to heat exposure by repetition of exposures.

Acclimatization↗
PubMed1983

Influence of lesion of the limbic-hypothalamic system on metabolic responses of acetate to daily repeated cold exposures in rabbits.

The effects of the lesions of basal medial hypothalamus and limbic structure on the acetate metabolic responses to daily repeated cold exposures in rabbit's liver has been investigated. The results obtained were summarized as follows: (1) The lesions of periventricular arcuate nucleus (ARC) had no effects on the acetate metabolism and on the acetate metabolic responses to the 1st cold exposure (cold exposure on the 1st day). (2) The metabolic pattern of acetate and the acetate metabolic responses to the 1st cold exposure were altered by the lesions of ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (3) The effects of cold exposure on the acetate metabolism were completely abolished by the seven times repetition of cold exposures in the rabbits with the lesions of ARC, VMH or ST, as the same as in each sham-operated group. (4) The acetate metabolic responses to cold exposure remained after the seven times repetition of cold exposure in the rabbits with the lesions of FX, but those disappeared completely in sham-operated animals. (5) From these results, it might be suggested that the VMH, amygdala(AMYG)-ST system, dorsal hippocampus(HPC)-FX system played some roles in the metabolic regulation of acetate and in the mechanisms of acetate metabolic responses to the 1st cold exposure, but the ARC did not participate in those mechanisms. And it was suggested that the HPC-FX system participated in the acetate metabolic adaptation to daily cold exposures, but the basal medial hypothalamus and AMYG-ST system did not participate in this process.

Acetates↗
PubMed1982

Antidromic identification of neurons in the ventrolateral part of the medulla oblongata with ascending projections to the preoptic and anterior hypothalamic area (POA/AHA).

Seventy neurons in the ventrolateral medulla oblongata were antidromically activated by electrical stimulation of the preoptic and anterior hypothalamic area (POA/AHA) in female rats under urethane anesthesia. These identified cells were located within and adjacent to the nucleus reticularis lateralis and could be readily distinguished into at least two types of neurons, designated as "fast' and "slow' cells, on the basis of their waveform and conduction velocity.

Action Potentials↗
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↗
PubMed1982

Influence of repeated cold exposures on adrenocorticoid formation in rabbits with lesioned limbic-hypothalamic system.

Experiments were carried out in the rabbit, with view to elucidating the role of limbic-hypothalamic system in the adrenocortical responses to repeated cold exposures. In each sham-lesioned group, in the rabbit with lesioned in bilateral stria terminalis and dorsal fornix, the formation of adrenocorticoids in adrenal was markedly increased by 1st cold exposure (cold exposure on 1st day), with the adrenocortical responses to 1st cold exposure being nearly the same in these groups. The bilateral lesions in periventricular arcuate nucleus and ventromedial hypothalamus decreased the adrenocortical responses to 1st cold exposure. In each sham-lesioned group, and in the rabbits with lesioned in bilateral periventricular arcuate nucleus, ventromedial hypothalamus and dorsal fornix, there were no effects of 7th cold exposure (cold exposure on 7th day) on the formation of adrenocorticoids. However, in the rabbits with lesioned in bilateral stria terminalis, the formation of adrenocorticoids was markedly increased by the 7th cold exposure. From these results it might be suggested that periventricular arcuate nucleus and ventromedial hypothalamus participated to adrenocortical response to 1st cold exposure, and the amygdala-stria terminalis system played some role in the establishment of adaptation to repeated cold exposures in adrenocortical responses.

Adrenal Cortex↗
PubMed1981

Effect of acupuncture on adrenocortical hormone production in rabbits with a central lesion.

A study was made of adrenocortical hormone production under electroacupuncture stimulation of the Tsu-San-Li locus in rabbits with a lesion in the fornix, stria terminalis, ventromedial nucleus or arcuate nucleus. In rabbits with a lesion in the stria terminalis or ventromedial nucleus, electroacupuncture stimulation of Tsu-San-Li resulted in no increase in phase 1 but an increase in phase 2 of adrenocortical hormone production. In rabbits with a lesion in the fornix or arcuate nucleus electroacupuncture stimulation of Tsu-San-Li was followed by increased adrenocortical hormone production in the both phases. These results show that the stria terminalis and the ventromedial nucleus play a major role in the augmentation of adrenocortical hormone production by electroacupuncture stimulation of Tsu-San-Li.

Acupuncture Therapy↗