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Biomedical subjects

S Asai

Publications and source records attributed to S Asai.

At least 163 records · Page 9Linked to original sources
PubMed1984

The site of action of Ptychodiscus brevis toxin within the parasympathetic axonal sodium channel h gate in airway smooth muscle.

The red tide toxin produced by Ptychodiscus brevis ( PBTX ) may cause cough, sneezing, and asthma. Previous in vitro studies with isolated canine tracheal smooth muscle demonstrated that PBTX stimulates sodium channels of parasympathetic nerve endings and thus causes a contractile response. The present study investigated the mechanism of the PBTX effect on canine tracheal smooth muscle. Repeated exposure of the muscle strip to PBTX (final concentration 46 micrograms/ml) followed by washout of the toxin resulted in reestablishment of baseline tension but a failure of contraction on further addition of PBTX . However, veratridine and scorpion toxin (SCT), which are voltage-sensitive sodium channel activators, still induced contraction. Furthermore, the contraction caused by veratridine was enhanced by a high dose of PBTX , whereas contraction caused by SCT was not. Responses to veratridine and SCT as well as PBTX (previously reported) were blocked by tetrodotoxin (a sodium channel blocker), while acetylcholine responsiveness remained intact. These results indicate that PBTX receptors in parasympathetic nerves influence Na+ flux at the h gate, that these receptors differ from the veratridine and SCT receptors, and that the conformational change in the receptors induced by PBTX affects the tissue response to veratridine.

Animals↗
PubMed1984

Ultrastructural studies on human lymphoblastoid cells treated with n-butyrate and 12-O-tetradecanoylphorbol-13-acetate.

The effects of n-butyrate and/or 12-O-tetradecanoylphorbol-13-acetate (TPA) on Raji and P3HR-1 cells were examined using electron microscopy. n-Butyrate treatment caused a decrease in the number and elongation of surface microvilli. In addition, well-developed rough endoplasmic reticulum and a marked decrease in condensed chromatin clumps were observed in the nucleus. The filamentous structures and nuclear membrane-like structures, which were not reported previously, appeared occasionally in the nucleus. On the other hand, in the cells treated with TPA no marked morphological changes were observed except the higher cytoplasmic:nuclear ratio. n-Butyrate-induced morphological changes were not inhibited when combined with TPA or retinoic acid. Electron microscopic studies showed remarkable differences in morphological change in these cells treated with n-butyrate and/or TPA.

Antigens, Viral↗
PubMed1983

Invasion of Burkitt's lymphoma cell lines by Yersinia enterocolitica.

We attempted to determine whether or not Yersinia enterocolitica could invade two cell lines derived from Burkitt's lymphoma (BL), P3HR-1, and Raji cells, and if the expression of Epstein-Barr virus (EBV) genome could be activated by the invasion of the organisms into the cells. The invasiveness of Y. enterocolitica into BL cells was examined morphologically, using transmission and scanning electron microscopy, and the induction of EBV antigens in the BL cells was examined by indirect immunofluorescence. Y. enterocolitica was clearly observed to invade P3HR-1 and Raji cells within 2 hr incubation at 37 degrees, after bacterial challenge. However, the invaded BL cells did not show significant induction of EBV early antigen after cultivation for 72 hr at 37 degrees. Although the present experiment failed to yield positive findings pertaining to the activation of EBV genome, our experimental system per se may still be a useful model when attempting to assess the effects of invading bacteria on the viral genome persistently carried in the host cells.

Burkitt Lymphoma↗
PubMed1982

Effects of toxin of red tide, Ptychodiscus brevis, on canine tracheal smooth muscle: a possible new asthma-triggering mechanism.

The red tide toxin produced by Ptychodiscus brevis becomes airborne by the thrashing action of the surf and wind and induces cough, rhinorrhea, watery eyes, and sneezing in normal humans and wheezing in asthmatic patients. The mechanism of the contractile response induced by P. brevis toxin (PBTX) was investigated with isolated canine tracheal smooth muscle. Tetrodotoxin and atropine blocked the contractile effect of PBTX, and neostigmine potentiated the contraction. Mepyramine, phentolamine, methysergide, and chlorisondamine did not inhibit the effect of PBTX. This is the first description of a naturally occurring airborne substance that causes smooth muscle contraction by stimulating the axon sodium channels, resulting in the release of acetylcholine at postganglionic parasympathetic efferent nerve endings. The in vitro effect of PBTX on canine tracheal smooth muscle indicates that PBTX is capable of causing respiratory irritation and thus may precipitate an asthmatic attack. It is possible, however, that the mechanism is vivo may also include stimulation of a cough receptor reflex and/or stimulation of sodium channels of afferent vagus nerve fibers. In vitro evidence suggests that isoproterenol, atropine, and verapamil may be used to eliminate or prevent the respiratory symptoms that follow exposure to airborne red tide toxin. The use of high-pressure liquid chromatography separated fractions indicates that the neurotoxic component, not the hemolytic component, is responsible for contractions.

Acetylcholine↗
PubMed1978

Mass spectrometry of medicines. Quantitative determination by direct probe inlet system mass chromatography.

A fundamental study was performed to establish a method of quantitative analysis using mass chromatography by the direct inlet system. The samples were aspirin, phenacetin and caffeine, which are often used as cold medicines, and barbital, allobarbital, phenobarbital and phenytoin which are difficult to analyse by gas chromatography in their intact states. N-acetylsulfamine and ethyl p-aminobenzoate were used as internal standards. Direct inlet mass chromatography was performed by an on-line system of the Shimadzu LKB-9000 and the GC-MSPAC 300. The ratio of the cumulative ions of certain peaks of sample and the internal standard was studied. It was found that, whether the sample is a pure reagent or a mixture, the ratio of cumulative ions of a peak specific to the sample and of a selected peak of the internal standard is proportional to the sample size, the error being less than +/- 3.5% for aspirin, phenacetin and caffeine, and less than +/- 2.7% for barbital, allobarbital and phenobarbital. The same relationship was observed for the phenobarbital and phenytoin mixed in rat plasma, the error being less than +/- 2.0%. It can be concluded that this method is applicable to the quantiative determination of medicines in urine, body fluids and other biological samples.

Aspirin↗
PubMed1978

On early and mid-adolescent schizophrenia.--Part II: prognosis, course and defect.

Twenty-three adolescent schizophrenics were studied in regard to the problems of the course of illness, prognosis and defect. Illustrations of cases (follow-up for three to 15 years) were presented. 1) The course was considered chiefly from the viewpoint of positive symptoms, namely paranoid-hallucinatory experiences. It was divided into the following four categories; remittent, persistent, scanty and fading types. At the same time, general characteristics of each type were discussed. 2) As to the changes in clinical forms, hebephrenia was gradually manifested in more than half of the cases. There were some cases in which the expansion of paranoid activities were observed. These two prominent tendencies might be explained in terms of personality disintegration and maturation. We were impressed, in this regard, that autistic tendencies and behavior disturbances were more manifest in the initial stages in patients who later turned more hebephrenic. 3) A mild defect was observed in fourteen cases, while a medium or severe defect was recognized in eight cases. Generally, the degree of defect seemed to be more manifest in female patients than in males. Moreover, the defect was generally more severe in early adolescent cases and in patients with insidious onsets as well as in those with a longer duration of illness than in mid-adolescent patients and those with acute onsets and a shorter duration of illness. 4) As the result of this investigation, it was substantiated that the prognosis in adolescent schizophrenia, especially in early adolescence, was unfavorable. 5) Finally, we were impressed by the fact that there were many patients who were treated mainly in ambulatory clinics or who stayed at home in spite of the above-mentioned unfavorable prognosis.

Adolescent↗
PubMed1978

On early and mid-adolescent schizophrenia. Part 1: Phenomenological aspects.

One hundred and seventy-three early and mid-adolescent schizophrenic patients were investigated during the 18-year period from April 1958 to March 1976 and the results concerning phenomenological aspects were reported here along with some considerations. 1. Hereditary predispositions were found in 43 cases among 161 patients. Male patients seemed to be more predisposed than female patients. The incidence of schizophrenia was the highest among other mental disorders, while it was most frequently observed in mothers and siblings among other kinships. 2. Precipitative factors were recognized in 45 cases. Among them, primary social factors and physical conditions seemed to play a rather important role. These factors seemed more frequent in males than in females. 3. As to birth order, the incidence of adolescent schizophrenia seemed to be higher in the last half of sibships than in the first half but the difference was significant at a five-percent level when the sibship sizes were 5--9. From the comparison of our results with the national statistics of the birth order in general population, the incidence of adolescent schizophrenia seemed to be lowest in the sublings of the second birth. 4. We divided the onset into three types; acute, intermediate and insidious. We were impressed that the acute onset seemed gradually to increase in mid-adolescence and the insidious onset vice versa. In addition, the insidious onset was found chiefly in cases with hebephrenic pictures except hebe-paranoid. 5. Hebephrenic form and simple form were frequently observed but catatonic form was relatively few. Genuine paranoid form was not found in our materials. Hebephrenic and catatonic forms were more frequently seen in males, while hebe-paranoid form was more frequent in females. 6. Main symptoms at the onset were discussed. Delusional activities, still vague and fragmentary, were observed in about half of our materials, being mostly persecutory. It seemed that they were strongly influenced by the state of mood of patients. Hallucinations, mostly auditory of verbal nature, were observed in more than one-fourth of our patients. On the contrary, the cases with visual and bodily hallucinations were a few in number. Autistic tendency and refusal of scholastic activities were more frequently seen in early adolescence, while suicidal attempts or self-injuring tendency, manic or depressive tinge, "gemachte Erlebnisse", "Eigengeruchsparanoia" were rather prevalent or first observed in mid-adolescence. Various symptoms, in general, seemed to become gradually more prominent along with the progression of ages. 7. EEG findings and treatment were reported at the same time. But the course and the problem of defect will be discussed in another paper. 8. Finally, the summaries of sex differences and of the comparison between early and mid-adolescence were supplemented.

Adolescent↗