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Biomedical subjects

K Seto

Publications and source records attributed to K Seto.

At least 127 records · Page 7Linked to original sources
PubMed1984

The action of the A1 noradrenergic region on phasically firing neurons in the rat paraventricular nucleus.

Electrical stimulation of the rat A1 noradrenergic region produced orthodromic inhibition (34%), excitation (23%) or excitation-inhibition sequence (25%) of the spontaneous activity of phasically firing units in the paraventricular nucleus of the hypothalamus (PVH). Excitatory responses could be distinguished into two types on the basis of their latency and duration. Both the primary and post-excitatory inhibitory responses were significantly attenuated by intravenous injection of propranolol, a beta-adrenoceptor antagonist, whereas neither type of excitatory response was affected.

Animals↗
PubMed1984

Influence of lesions in the limbic-hypothalamic system on metabolic response of acetate to daily repeated immobilization stress.

The effects of lesions in the basal medial hypothalamus and limbic structure on the acetate metabolic responses to daily repeated exposure to immobilization stress in the liver of rabbits have been investigated. The experimental results were as follows: (1) The acetate metabolic response to the 1st exposure to immobilization stress (exposure on the 1st day) were considerably altered by lesions in the periventricular arcuate nucleus (ARC) ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) The acetate metabolic responses to immobilization stress were completely abolished by seven times repetition of immobilization stress in the rabbits with lesions in ARC, VMH and FX; they were similar to sham-operated groups. (3) In rabbits with ST lesions, the acetate metabolic responses to the 7th exposure (exposure on the 7th day) to immobilization stress were exactly the same as those after the 1st exposure of immobilization stress, but these metabolic responses were completely abolished by the seven times repetition of exposure in the sham-operated animals. (4) These results suggest that firstly, the ARC, VMH, amygdala(AMYG)-ST system and dorsal hippocampus(HPC)-FX system are involved in the acetate metabolic responses to the 1st exposure of immobilization stress, and secondly, that only the AMYG-ST is involved in the disappearance process of acetate metabolic responses to immobilization stress by the daily repetition of immobilization stress.

Acetates↗
PubMed1984

Influence of lesions in the limbic-hypothalamic system on metabolic response of acetate to daily repeated heat exposure in rabbit.

The effects of lesions in the basal medial hypothalamus and limbic structure on the acetate metabolic responses to daily repeated heat exposure in the liver of rabbits have been investigated. The results obtained were summarized as follows: (1) THe acetate metabolic responses to the 1st heat exposure (heat exposure on the 1st day) were altered by the lesions in the periventricular arcuate nucleus (ARC), ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) The acetate metabolic responses to heat exposure were completely abolished by the ten times repetition of heat exposure in the rabbits with lesions in ARC or VMH. They were similar to sham-operated animals. (3) The acetate metabolic responses to heat exposure remained even after the ten times repetition of heat exposure in the rabbits with lesions in ST and FX indicating the differences from sham-operated animals. (4) From these results, it might be suggested that the basal medial hypothalamus and limbic structure participated in the mechanism of acetate metabolic response to the 1st heat exposure, but only these limbic structure played some roles in the complete disappearance process of acetate metabolic responses to heat exposure by the ten times repetition of heat exposure.

Acetates↗
PubMed1984

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

The effects of lesions in the basal medial hypothalamus and limbic structures on the responses in plasma levels of insulin and glucose to daily repeated cold exposure in rabbits have been investigated. The results obtained were summarized as follows: (1) The 1st cold exposure (cold exposure on the 1st day) decreased insulin levels and increased glucose levels, and these responses of insulin and glucose to cold exposure gradually decreased and then completely abolished by daily repetition of exposures in intact rabbits and each sham-operated group. (2) The lesions of periventricular arcuate nucleus (ARC), stria terminalis (ST) and dorsal fornix (FX) had no effects on the insulin responses to the 1st cold exposure, but the rates of insulin responses to the 1st cold exposure were decreased by the lesions of ventromedial hypothalamus (VMH). (3) The ARC lesions had no effects on the glucose responses to the 1st cold exposure, but the glucose responses to the 1st cold exposure were abolished by VMH lesions and were altered by lesions of ST and FX. (4) The insulin responses to cold exposure were abolished by daily repetition of exposures in rabbits with ARC lesions as same in the cases of sham-operated animals, but the insulin responses to cold exposure persisted even after daily repetition of exposures in rabbits with lesions of VMH, ST and FX different from sham-operated animals. (5) The glucose responses to cold exposure were abolished by daily repetition of exposures in rabbits with lesions of ARC and ST as same as in the cases of sham-operated animals, but the glucose responses to cold exposure persisted even after daily repetition of exposures in rabbits with FX lesions different from sham-operated animals.

Animals↗
PubMed1984

Antibiotic resistance of Erysipelothrix rhusiopathiae isolated from pigs with chronic swine erysipelas.

The susceptibility of 258 isolates of Erysipelothrix rhusiopathiae from slaughtered pigs affected with chronic erysipelas in Japan to antimicrobial agents was determined. A total of 111 (43.0%) strains showed resistance to erythromycin, oleandomycin, oxytetracycline, or dihydrostreptomycin. Plasmids were not detected. This is the first report of resistance of E. rhusiopathiae to these antibiotics.

Animals↗
PubMed1984

Cross protection in mice and swine immunized with live erysipelas vaccine to challenge exposure with strains of Erysipelothrix rhusiopathiae of various serotypes.

Mice and swine immunized subcutaneously with live vaccine prepared from acriflavine-fast attenuated Erysipelothrix rhusiopathiae, strain Koganei (serotype 2), were challenge exposed to virulent strains of E rhusiopathiae of various serotypes. Vaccinated mice did not die after challenge exposure to serotypes 1a, 1b, 2, 3, 5, 6, 7, 8, 9, 11, 12, 15, 16, 18, 19, 21, or N, but 20% to 30% mortality occurred in vaccinated mice challenge exposed to serotypes 10, 14, 20, or 22. Nonvaccinated control mice died after challenge exposure to all serotypes tested. Vaccinated swine challenge exposed to strain 14B (serotype 9) or strain 2179 (serotype 10) developed localized urticarial lesions at the site of intradermal exposure. Vaccinated swine challenge exposed to serotypes 1a, 1b, 2, 5, 8, 11, 12, 18, 19, or 21 did not have clinical signs of acute erysipelas. Nonvaccinated control swine developed acute generalized erysipelas or localized lesions at the site of intradermal exposure.

Animals↗
PubMed1983

Theoretical analysis on relationship between the neural activity and the EEG.

Firstly, a collective oscillation mode of the neural activity is derived from the neural network system by using the multicompartment equation and the projection operator technique. This technique takes into account higher order interactions among neurons. The solution of the equation gives a chain structure with an infinite number of circuit loops in which each of them is only composed of four neurons. The obtained eigenvalues are quite similar to the spectrum of frequencies of the EEG. Secondly, the time-dependent behavior of the observed EEG is simulated by starting from the elementary process of action potential trains of neurons, which includes the effect of the collective oscillation mode mentioned above. This gives a comprehensive derivation of the EEG from the neural activity of action potentials. The simulation assumes that information of the action potential trains can be transmitted to the EEG through the intermediate states of the postsynaptic potential trains and the slow waves. The paper reports that a slightly modulated activity of a relatively small amount of neurons can cause a strong influence on the shape of the global EEG and that the calculated results reproduce the characteristic features of the EEG in a rat such as the theta rhythm, the spindle wave and the arousal wave.

Action Potentials↗
PubMed1983

Effects of estrogen on the excitability of neurons projecting from the noradrenergic A1 region to the preoptic and anterior hypothalamic area.

Estradiol benzoate administered to ovariectomized female rats significantly elevated the mean spontaneous firing rate and frequency of successful antidromic propagation into the somatodendritic spike and significantly reduced the strength of post-stimulus inhibition in presumed A1 noradrenergic neurons projecting directly to the preoptic and anterior hypothalamic area. The occurrence of both antidromic spikes and post-stimulus inhibition of the majority of these neurons was completely abolished by the injection of 6-hydroxydopamine but not by 5, 7-dihydroxytryptamine directly into the medial forebrain bundle.

5,7-Dihydroxytryptamine↗
PubMed1983

Isolation and serological typing of ureaplasma in human saliva.

Ureaplasmas were detected in the saliva of 3.5 per cent (12/342) of subjects. A total of 60 isolated strains did not revert to bacterial forms on repeated subculture in antibacterial agent-free media, failed to grow in serum-free media, were inhibited by digitonin and hydrolysed urea but not glucose or arginine. Twenty-five strains were divided into serotypes: I (5), II (3), III (5), IV (4) and VI (8 strains). Ureaplasmas of serotype I, II, III, IV and VI were harboured by 2, 1, 1, 1 and 3 subjects respectively and the remaining 4 subjects harboured 2 different serotypes. Ureaplasma-positive subjects were young and middle-aged and, except for 1 subject with mandibular arthrosis, suffered from periodontitis, pericoronitis, gingivitis and maxillary sinusitis. These accounted for only 6.1 per cent (11/180) of the series of subjects examined.

Adolescent↗
PubMed1983

Changes in pituitary-adrenal function under continuous exposure to hypoxia in male rats.

The plasma corticosterone concentration and incorporation of 14C-1-acetate into adrenocortical hormones were measured in male rats exposed to hypoxia (12.5% O2 in N2 balance) for periods of 30 min--14 days. Hypoxia significantly increased the weight of the adrenal and pituitary glands in early stages of exposure. However, weight returned to the control level on the 14th day of exposure. Hypoxia consistently decreased the weight of the thymus. Hypoxia elevated the plasma corticosterone concentration in the early stages of exposure. However, the elevated corticosterone level gradually decreased by the 7th day. The corticosterone level at this stage was lower than in the control. The corticosterone concentration returned to the control level on the 14th day. Hypoxia significantly facilitated incorporation of 14C-1-acetate into corticosterone and cortisol in the adrenal homogenate. The elevated incorporation was maintained until the 7th day and gradually decreased to the control level there after. Body weight was decreased by hypoxia (12 gram in 24 hours). On the 5th day, the weight returned to the control level. Hematocrit increased gradually during 14 days of hypoxia exposure. These results suggest that pituitary-adrenal function is greatly facilitated by 1-6 hours of hypoxia exposure, and hypoxia acclimatization is accomplished humorally within 14 days of exposure in rats.

Acetates↗
PubMed1983

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

In order to elucidate the role of the limbic-hypothalamic system in the adrenocortical responses to repeated immobilization stress, the influences of daily repeated exposures of immobilization stress on the adrenocorticoid formation in adrenal slices of rabbits with lesions of various sites of the hypothalamus and limbic structures had been investigated. The experimental results obtained were as follows: (1) Lesions in periventricular arcuate nucleus (ARC) and ventromedial hypothalamus (VMH) decreased the rates of adrenocortical responses to the 1st immobilization exposure (exposure on the 1st day), but did not alter the rates of adrenocortical responses to the 4th immobilization exposure (exposure on the 4th day). (2) Lesions in stria-terminalis (ST) and dorsal fornix (FX) did not alter the rates of adrenocortical responses to the 1st immobilization exposure, but increased the rates of adrenocortical responses to the 4th immobilization exposure. (3) The adrenocortical responses to immobilization stress were completely abolished by the seven times repetition of exposures in each sham-operated group and in the animals with lesions of ARC and VMH, but in the rabbits with lesions of ST and FX the adrenocortical responses to immobilization stress were not abolished by the seven times repetition of exposures. (4) These results suggested that such basal medial hypothalamus participated in the mechanisms of adrenocortical responses to the 1st exposure of immobilization stress, but did not participate in the disappearance process of adrenocortical responses to immobilization stress by the seven times repetition of exposures. On the other hand, it might be supposed that the amygdala(AMYG)-ST system and dorsal hippocampus(HPC)-FX system do not participate in the mechanism of adrenocortical responses to the 1st immobilization exposure, but these limbic areas played some roles in the disappearance process of the adrenocortical responses to immobilization stress by the seven times repetition of exposures.

Adrenal Cortex↗
PubMed1983

Influence of electrical stimulation of the limbic structure on insulin level in rabbit's plasma.

The amygdala (AMYG) stimulation caused a marked decrease in the circulating level of insulin coincident with a considerable rise in the glucose level in rabbits. The stimulation of dorsal hippocampus (DHPC), on the other hand, greatly increased the insulin level and decreased the glucose level. The results suggested that the reciprocal influence of AMYG and DHPC on plasma levels of insulin and glucose played some roles in the regulation of insulin release and the homeostasis glucose metabolism in rabbits.

Amygdala↗