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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 487 records · Page 27Linked to original sources
PubMed1987

5-Hydroxytryptamine agonistic action of methysergide and the absence of supersensitivity to 5-HT agonists in spinal flexor reflexes in rats.

The intravenous administration of L-5-hydroxytryptophan (5-HTP), 5-methoxy-N,N-dimethyltryptamine (5-MeODMT), p-chloroamphetamine (PCA), LSD and methysergide to acute spinal rats, transected at C1, stimulated the flexor reflexes induced by electrical stimulation applied to the skin of the toe. The enhancement produced by 5-HTP, 5-MeODMT and PCA, was not antagonized by the prior administration of a dose of LSD or methysergide, although the enhancement produced by 5-MeODMT, LSD and methysergide, but not that produced by 5-HTP and PCA, was antagonized by cyproheptadine. In rats treated with 5,6-dihydroxytryptamine (intracisternal administration, 2 weeks previously) supersensitivity was observed to the effects of 5-HTP, a precursor of 5-HT, while subsensitivity was observed for the effects of PCA, a releaser of 5-HT. However, no supersensitivity was observed for the effects of 5-MeODMT, LSD and methysergide. These results suggest that methysergide may have an agonistic action on the 5-HT receptors in spinal cord and that supersensitivity to 5-HTP in rats treated with 5,6-dihydroxytryptamine was due to the lack of uptake of 5-HT into terminals of descending 5-HT fibres or to the change in 5-HT receptors which were not sensitive to 5-MeODMT, LSD, methysergide or cyproheptadine.

5,6-Dihydroxytryptamine↗
PubMed1987

Characteristics of memory impairment in cerebral embolized rats at the chronic stage.

The effect of cerebral embolization on learning and memory in rats was studied at the chronic stage (8 weeks or more after embolization). At the chronic stage, embolized rats showed no significant change in emotional behavior, but exhibited an increase in ambulation in the open-field test. Rats with cerebral embolization exhibited marked impairment of the response was observed at the chronic stage. In a two-way active avoidance task, embolized rats showed accelerated acquisition of the avoidance response in comparison with a sham-operated control group. However, at the chronic stage, embolized rats exhibited marked impairment of light-dark discrimination learning. Spatial memory impairment was also observed in embolized rats, as demonstrated by a significant decrease in initial correct responses and an increase in total errors in the radial maze task. Upon microscopic examination, multi-focal necroses were detected in several brain regions, being particularly obvious in the hippocampus and internal capsule of the embolized hemisphere. These results demonstrate that embolized rats show definite impairment of memory and learning at the chronic stage, and suggest that the impairment may be qualitatively different from that observed at the early stage.

Animals↗
PubMed1987

Effects of idebenone, a cerebral metabolism activator, on muricidal behavior in rats with raphe lesions.

The effects of idebenone, a cerebral metabolism activator, on mouse-killing behavior (muricide) in rats with lesions of the midbrain raphe nuclei were studied. Single administration of idebenone (30 and 100 mg/kg, IP) inhibited the muricidal behavior in the raphe-lesioned rats in a dose-dependent manner. Idebenone also suppressed muricide in the olfactory bulbectomized rats, although the effect was less marked than that shown in the raphe-lesioned rats. In addition, the antimuricidal effect of idebenone was augmented with repeated administration. These results support previous findings that idebenone has an activating action on central serotonergic neurons in rats and in patients with cerebrovascular dementia, and suggest that idebenone may improve some of the depressive symptoms often observed in patients with cerebrovascular lesions and other forms of brain disturbance.

Aggression↗
PubMed1987

Anti-TSH antibody with high specificity to human TSH in sera from a patient with Graves' disease: its isolation from, and interaction with, TSH receptor antibodies.

A patient with thyrotoxic Graves' disease had an apparent measurable level of serum TSH (2.5 microU/ml) by double-antibody radioimmunoassay (RIA). The serum IgG bound with both [125I]human(h)TSH and [125I]bovine(b)TSH. The [125I]hTSH binding was more effectively displaced by human than bovine TSH, whereas [125I]bTSH binding was displaced exclusively by bTSH. Scatchard analyses revealed that [125I]hTSH binding showed two components, whereas [125I]bTSH binding had only one component. Serum TSH determined by RIA became undetectable 21 months after antithyroid drug treatment with a parallel decrease of [125I]hTSH binding IgG activity. Four thyrotrophin binding inhibitory immunoglobulins (TBII) from other patients did not interfere with the binding of the patient's serum to [125I]h- or bTSH. Furthermore, the in-vitro thyroid stimulating activities of three thyroid stimulating antibodies (TSAb) were not affected by the addition of this patient's IgG. On the other hand, this patient's Ig (3 mg/ml) abolished the in-vitro thyroid stimulation by bTSH (100 microU/ml), but did not affect that by hTSH (100 microU/ml). The anti-hTSH antibody, TSH receptor antibody and anti-bTSH antibody in the serum, which contains TSAb as well as anti-TSH antibodies, could be partially purified by hTSH-agarose and subsequently by guinea pig fat cell membrane affinity absorptions. However, the anti-hTSH antibody fraction obtained had both hTSH binding activity and thyroid stimulating activity, and this fraction did not show any inhibitory effect on the in-vitro thyroid stimulation of autologous TSH receptor antibody or hTSH. The possible significance of anti-TSH antibodies is discussed.

Adult↗
PubMed1987

Effects of plasticizers and plastic bags on granulocyte function during storage.

The influence of the plasticizers, di-(2-ethylhexyl)phthalate (DEHP) and tri-(2-ethylhexyl)trimellitate (TOTM), on granulocyte function was examined. Polyvinyl chloride (PVC) bags with DEHP (DEHP-PVC) leaked DEHP into plasma, but TOTM did not dissolve in plasma under the same conditions. Glow discharge treatment inhibited the leakage of DEHP from DEHP-PVC bags. Depending on the amount of DEHP added into granulocyte suspension, chemotaxis and bactericidal activity decreased, but cell counts and phagocytosis were not affected. During storage for 24 h at 22 degrees C, granulocyte function decreased greatly in DEHP-PVC, but was well maintained in the bags which did not leak plasticizers, TOTM-PVC and glow-discharged DEHP-PVC.

Benzoates↗
PubMed1987

Disappearance of blocking type thyrotropin binding inhibitor immunoglobulin (TBII) during thyroid and steroid medication in a patient with autoimmune thyroiditis.

A 55 year-old female had suffered from 3 consecutive diseases for a year. The diseases were ulcerative colitis, primary hypothyroidism and idiopathic thrombocytopenic purpura, and had been treated with L-thyroxine (50 micrograms daily) and betamethasone (0.5 to 1.5 mg daily). On examination, the thyroid gland was not palpable at all, thyroid 99 mTc pertechnetate uptake was 0%, and an echogram revealed the existence of an atrophic gland. Thyrotropin binding inhibitor immunoglobulin (TBII) in the serum was elevated to 58.0% and her IgG almost completely inhibited the in vitro cAMP increase due to bTSH. After 5 months TBII turned out to be negative and the inhibitory IgG activity was reduced significantly. The thyroid gland also became visible scintigraphically. Thyroid medication was then stopped. Four months after the cessation of thyroxine, she felt quite well and her thyroid functions remained within the normal ranges. Antibody to Yersinia enterocolitica was positive at a low titer (X20) in the early stages, but elevated reciprocally with the fall in TBII and finally reached X320. In conclusion, evidence of the disappearance of blocking type TBII from the serum was demonstrated for the first time. Steroid might have caused some favorable effects, and this clinical report indicates the possibility that remission of hypothyroidism due to blocking type TBII can be expected.

Antibodies, Bacterial↗
PubMed1987

[Inhibitive effects of observer's presence on the choice latency].

The purpose of the present experiment was to compare the relative usefulness of drive and self-presentation approaches to social facilitation. Thirty-nine undergraduates were divided into two groups for the experiment. Group 1 was given a delayed choice reaction task under two different conditions. The first session was done with the subjects in isolation, and the second session was done with the subjects in front of an audience. Group 2 was given a delayed choice reaction task under the condition of isolation only. Latency was found to be substantially longer under the audience condition. There were, however, no significant effects on the mean number of the correct responses. These results point to inadequacies in drive approach and give support to self-presentation view, which assumes that subjects may scan more carefully and attempt to exhibit a socially valued behavior in others' presence.

Adult↗
PubMed1987

Comparison of the effects of the new anxiolytic suriclone and benzodiazepines on motor function and electroencephalogram.

(6-(7-Chloro-1,8-naphthyridin-2-yl)-7-oxo-2,3,6,7-tetrahydro-5H- 1,4- dithiino[2,3-c]pyrrol-5-yl)-4-methyl-1-piperazinecarboxylate (suriclone, RP 31264), a new anxiolytic, produced behavioral effects similar to those of diazepam and lorazepam, had a protective effect against electroshock convulsion and potentiated the sleeping effect of hexobarbital in mice. It inhibited crossed extensor reflexes in chicks and augmented the dorsal root reflex potential, the increase of which is considered to be an index of increased GABAergic presynaptic inhibition. Suriclone produced high-amplitude slow waves in the amygdala and cerebral cortex and desynchronization of theta waves in the hippocampus in rat electroencephalogram (EEG). These observations were quantitatively confirmed by power spectrum analysis of EEG. The mechanisms of action of suriclone on the CNS are discussed in relation to those of benzodiazepines.

Animals↗
PubMed1987

A case with silent type of pseudo-acholinesterasemia.

One case of pseudo-acholinestrasemia was experienced in our hospital. The patient was a 54-year-old female with sigmoid colon cancer. A preoperative examination showed that her cholinesterase (ChE) level was 7 IU/L (normal range: 3,700-5,400 IU/L) although no abnormalities were found in other enzymes derived from the liver, total protein and albumin level in the serum. An investigation of eight family members over two generations revealed two cases of acholinesterasemia in addition to the patient. Immunological examination by Ouchterlony's method and isoenzyme analysis by polyacrylamide gel electrophoresis showed that ChE production was absent in this case, while dibucaine or fluoride number was normal among the family members. Based on these results, it was concluded that this patient belonged to the silent type of homozygote. A case of pseudo-acholinesterasemia, which is very rare in Japan, is described.

Blood Transfusion↗
PubMed1987

[The effect of low-dose total body irradiation on tumor control].

Total body irradiation (TBI) is considered to bring about an immunosuppressive effect on an organism, on the basis of data obtained from sublethal doses of TBI. However, there are no data on how low-dose TBI affects an organism. Over the last five years, we have been studying the effects of low-dose TBI on normal or tumor-bearing mice and the immunological background of these effects. In experimental studies, an increase in the TD50 value (the number of cells required for a tumor incidence of 50%) in mice exposed to 10 rad was recognized and showed a remarkable increase at 6 hours to 15 hours after irradiation. TBI of 10 rad also showed an enhancement effect on tumor cell killing when given 12 hours before local tumor irradiation. In order to clarify the mechanism of this kind of effect, some immunological studies were performed using several immunological procedures, and the results suggested that 10 rad of TBI caused increasing tumor immunity in irradiated mice. Clinical trials in some patients with advanced tumors are now being undertaken on the basis of these experimental data, and the effect of TBI on tumor control appears promising, although it is too early to draw conclusions.

Aged↗
PubMed1987

[Anti-tumor effect of total body irradiation of low doses on WHT/Ht mice].

The effect of low dose (0.05-1.0 Gy) of total body irradiation (TBI) on non-tumor bearing and tumor bearing mice were investigated. Mice received TBI of 0.1 Gy during 6-12 hours before tumor cell inoculation demonstrated to need larger number of tumor cells (approximately 2.5 times) for 50 per cent tumor incidence, compared to recipient mice not to receive TBI. On the other hand, in tumor bearing mice given 0.1 Gy of TBI only tumor cell killing effect was not detected, however enhancement of tumor cell killing effect and prolonged growth delay were observed when tumor bearing mice were treated with 0.1 Gy of TBI in combined with local irradiation on tumors, especially cell killing effect was remarkable in dose range over 6 Gy of local exposure. The mechanism of the effect of 0.1 Gy TBI is considered to be host mediated reactions from the other our experimental results.

Animals↗
PubMed1987

[Fundamental and clinical studies of low-dose total body irradiation in tumor control].

Total body irradiation of 10 rad showed an enhancement effect on tumor cell killing when given 12 hours before local tumor irradiation. In order to clarify the mechanism of this kind of effect, some immunological studies were performed using several immunological procedures, and the results suggested that 10 rad of total body irradiation caused increasing tumor immunity in irradiated tumor bearing mice. Clinical trials in some patients with advanced tumors are now being undertaken on the basis of these experimental data, and the effect of total body irradiation tumor control appears promising although it is too early to draw conclusions.

Animals↗