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Biomedical subjects

A Ito

Publications and source records attributed to A Ito.

At least 1,063 records · Page 59Linked to original sources
PubMed1976

Production and properties of theta-toxin of Clostridium perfringens with special reference to lethal activity.

theta-Toxin of Clostridium perfringens produced in a synthetic medium showed high toxicity. The mouse was killed with 5-10 hemolytic units of the toxin. Neutralization experiments showed that lethal and hemolytic activities were due to the same toxic entity. The amount of theta-toxin expressed in lethal activity reached more than 30% that of alpha-toxin in the synthetic medium SM67. Although the activities of alpha-and theta-toxins were not additive in terms of LD50, increase in the ratio of theta-toxin to alpha-toxin resulted in reduction of the survival time of the mouse injected with a lethal dosis of the mixture of the two toxins when compared with alpha-toxin alone. Unlike those produced in other media, the hemolytic and lethal activities of theta-toxin produced in the synthetic medium was not activated by reduction with thioglycollate, even after partial purification. In other respects, the toxin was not different significantly from those reported in the past. The toxic form was detected also in complex medium. It was suggested that theta-toxin may be produced as a nascent entity.

Animals↗
PubMed1975

Overdrive suppression in diagnosis of sick sinus syndrome.

A criterion to determine the indication for pacemaker implantation in the sick sinus syndrome by overdrive suppression is proposed. Overdrive suppression was performed in 10 patients with the sick sinus syndrome (SSS) and another 10 patients with normal sinus rhythm (NSR) who served as controls. In the SSS group, 9 patients had complained of such severe symptoms as Adams-Stokes attack and/or congestive failure and were referred to our laboratory for pacemaker implantation. One other patient, an apparently robust young man (20 years old) referred for detailed cardiac examination, had no remarkable symptoms except for arrhythmias, but was found dead two months later. Atrial pacing for overdrive suppression was carried out at first at various rates ranging from 60 to 180 beats/min for 15 sec, and then at a rate of 100 beats/min for various durations ranging from 5 to 180 sec. After cessation of the atrial pacing, asystolic pauses were measured and the maximum (maximum pause) among the pauses obtained was used as a parameter indicating depression of cardiac automaticity. The maximum pause in the SSS group ranged from 5.6 to 9.0 sec (mean +/- SD = 7.0 +/- 1.2), WHILE THOSE IN THE NSR group ranged from 0.7 to 1.5 sec (mean +/- SD = 1.2 +/- 0.14). Therefore, the maximum pause was considered not only to reflect the severity of the symptoms necessitating pacemaker implantation in the 9 patients of the SSS group but to have warned us of sudder death in another patient. We concluded that overdrive suppression is useful as a supplementary challenge to determine indications for pacemaker implantation for the sick sinus syndrome, and that prolongation of the maximum pause beyond 5.0 sec is the critical level for pacemaker implantation.

Adult↗
PubMed1975

In vitro oncospheral agglutination given by immune sera from mice infected, and rabbits injected, with eggs of Hymenolepis nana.

Oncospheral agglutination given by sera immunized with Hymenolepis nana eggs is described as a new way of assessing H. nana infection. All sera of mice which possessed acquired protective immunity against reinfection by H. nana eggs had the potency to induce oncospheral agglutination in vitro. Only oncospheres, which had been hatched, agglutinated, no agglutination occurred in sera from uninfected mice. Oncospheral agglutination was carried out by mixing 0-1 ml of serial two-fold dilutions of serum and 0-1 ml of Hanks' balanced salt solution containing about 600 hatched oncospheres. Titre of agglutinins was indicated as a reciprocal of the final dilution capable of giving agglutination clusters made of three or more oncospheres. Agglutinins developed within 14 days after a primary infection with 500 shell-free eggs. There was no rapid increase of agglutinins within 4 days following a secondary infection. The titre increase coincided with the increase in dosages of eggs. Agglutinins were thought to be immunoglobulins, because the potency of the serum to agglutinate oncospheres was extinguished after absorption of globulins with rabbit anti-mouse globulin serum. Agglutinins were produced in rabbits by intravenous injections of shell-free eggs. The titres of the rabbit sera were much higher than those of mouse sera.

Agglutination↗
PubMed1975

Effect of serotonin depletion on the central regulation of the carotid sinus reflex in rats.

Effect of serotonin depletion in the rat brain on the sympathetic pressor response to occlusion of the common carotid arteries was examined along with the sequential transection of the brain stem. In rats with the brain serotonin depleted below 10% of control by p-chlorophenylalanine, the reflex pressor response significantly decreased, but the reflex sensitivity was unchanged in any transection regimen, suggesting the decrease originated in the associated hypertension; The infracollicular transection augmented the reflex reaction and sensitivity in both groups, and the medullospinal separation abolished the reflex; It is concluded that the brain serotonin would not be significantly involved in the central regulation of the sympathetic component of the carotid sinus reflex, and that the structure rostral to the midbrain could play an inhibitory role in the integrative regulation.

Animals↗
PubMed1975

Slowered turnover of norepinephrine in the brain associated with an acute elevation in blood pressure of rats.

Acute responses of blood pressure and turnover of norepinephrine in the brain to intracisternally injected guanethidine were studied in rats. Systolic blood pressure in guanethidine-treated rats showed a dose-relating rise for over 9 hrs, while norepinephrine contents in cortex-cerebellum, brain stem and heart were not affected. The endogenous norepinephrine in brain samples, however, did not decrease against alpha-methyl-p-tyrosine to result in regression coefficients significantly different from those in the saline-treated group whereas norepinephrine in heart was reduced similarly in the 2 groups, indicating a slowered turnover of norepinephrine selectively in the brain. The results may indicate that the retarded norepinephrine turnover in the brain is causatively related with an acute elevation in blood pressure.

Animals↗
PubMed1975

Histometrical estimation of scar tissue in hypertrophied human heart muscle.

Histometrical estimation of scar tissue was made on 28 hypertrophied human hearts obtained at autopsy in order to know the significance of scar tissue in the process of cardiac hypertrophy and in the development of cardiac failure. Estimation was made on histological specimens of the anterior wall of the left ventricle and the posteromedial papillary muscle, according to Chalkley's point counting method, and the amount of scar tissue was expressed by percentages. The mean percentages were 4.6, 8.5 and 18.3 in the epicardial, endocardial part of the left ventricle, and the papillary muscle. There were very significant differences between these 3 mean percentages. There was a very significant correlation between the percentages of scar tissue in the endocardial part of the left ventricle and heart weight. There were no definite correlations between the percentages of scar tissue in the epicardial part or in the papillary muscle and heart weight. From these results, possible causes of scar formation and significance of scar tissue to the development of cardiac failure were discussed.

Adult↗
PubMed1975

Aging and scar tissue in human heart muscle.

Histometrical estimation of scar tissue was made on 30 human hearts obtained at autopsy in order to know possible correlations between aging and scar tissue in the heart muscle. Estimation was made on histological specimens of the anterior wall of the left ventricle and the posteromedial papillary muscle, according to Chalkley's point counting method, and the amount of scar tissue was expressed in percentage. The mean percentages were 3.11, 5.26 and 9.24 in the epicardial, endocardial parts of the left ventricle and the papillary muscle, respectively. There were very significant differences between these 3 mean percentages. There were very significant correlations between the percentages of scar tissue in these 3 parts and ages. From these results, it is concluded that the scar formation increases in the heart muscle with aging.

Adolescent↗
PubMed1975

Determination of hydroxyproline content in human heart muscle.

Hydroxyproline content was chemically determined on 45 human hearts obtained at autopsy in order to study whether hydroxyproline contents vary in proportion to heart weight or not. There were no significant differences in the mean hydroxyproline content between the epicardium and the endocardium, between the left ventricle and the right ventricle, or among cardiovascular and renal disease group, malignant disease group and miscellaneous disease group. Total hydroxyproline content per mg dry weight of the left ventricle increased proportionally with heart weight. Hydroxyproline content in neutral salt soluble fraction increased more proportionally than that in acid soluble fraction. This tendency was more evident in the endocardium than in the epicardium of the left ventricle. These results seem to be well consistent with those of histometrical estimation of scar tissue in human heart muscle. Hydroxyproline content in acid soluble fraction of the right ventricle was increased proportionally with heart weight.

Adolescent↗