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Biomedical subjects

T Mihara

Publications and source records attributed to T Mihara.

At least 91 records · Page 5Linked to original sources
PubMed1980

[Contribution of 210Bi beta-ray induced bremsstrahlung to the emission of Pb-KX-rays observed in the lead shielded gamma-ray background spectrum (author's transl)].

Observation of gamma-ray background has been done by using a Ge(Li) semiconductor detector when it was placed inside the lead shielding material. With the aid of a very simple model calculation, the concentration of 210Pb radioisotope embedded in the lead material has been estimated to be 0.1-0.4 (Bq/Pb-g) (3-12 (pCi/Pb-g). The origin of Pb-KX-ray emission, the highest peak in the background spectrum, has been investigated by comparing the 210Pb-47 keV gamma-ray and Pb-KX-ray peak counts. As the results, about 50 +/- 30% of Pb-KX-ray production is estimated to be due to the Pb-K shell photoionization which is induced by the bremsstrahlung of 210Bi beta-ray.

Background Radiation↗
PubMed1979

Small ventricles detected by CT-scanning in epileptic patients.

Relatively young 119 cases of generalized epilepsy and 99 controls of an identical age were selected. The bicaudate CVI was measured and the results were as follows: 1) In our cases, the mean of bicaudate CVI showed a smaller value than those of Hahn's in both epilepsy and control groups. 2) When the value of bicaudate CVI was set up below the point of 8.5 as "excessively small ventricle," the incidence rate of "excessively small ventricle" was 9% in the control group and 31% in the epilepsy group. The data showed higher incidences of small ventricles in the epilepsy group, and that the younger females have a tendency to have higher incidences of small ventricles. 3) To make clear the reason for the higher incidences of small ventricles in epilepsy, the small ventricle group and the non-small ventricle group in epilepsy were compared with each other from the points of the clinical course, EEG findings and frequency of attacks. No correlation or difference between them was found. Further investigation will be needed to make clear the etiology of small ventricles in epilepsy. However, it could be said at the present stage that not so many atrophic changes were observed in the younger patients of generalized epilepsy.

Adolescent↗
PubMed1976

A morphological study on vascular changes in the surgically resected tissues of temporal lobe epilepsy-with a special reference to the etiology.

(1) Twenty-one out of 23 cases surgically resected specimens of TLE presented the common histological findings; sclerotic changes of the tissues. And the other two cases encountered the small tumors which might be called "cryptic". (2) Since circulatory disturbance is generally accepted to explain the cause of TLE we reexamined vascular behaviors in detail and found the quantitative and qualitative abnormaltities which reached the high rate of 71% (17 out of 21 cases) except two cases of small tumors. Moreover, it is remarkably noteworthy that these vascular changes adjoin the sclerosed parenchymal tissue. (3) It may be said that vascular changes have exerted some influences on the formation of inferomedial temporal sclerosis from the standpoint of the histological findings, though they are alone not fully sufficient to explain the etiology of TLE.

Brain Neoplasms↗
PubMed1975

A nucleoside triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. The mode of action of the enzyme.

The acid-soluble products of exhaustive digestion of native DNA with Bacillus laterosporus DNase consist of 6.5% of mononucleotides and 93.5% of oligonucleotides with an average chain length of 3.2. The results of viscometric studies and inactivation of transforming DNA indicate the existence of acid-insoluble intermediates and the selective degradation of the population of substrate molecules rather than a random nucleolytic action. Furthermore, sucrose density gradient analysis of partially digested DNA showed that the initial DNA added as a substrate disappeared progressively during the reaction, being replaced by much more slowly sedimenting acid-insoluble materials, which were eventually degraded into acid-soluble end products during the reaction; products intermediate in size between these two components were not detectable. Studies with DNA labeled at the 3'-terminus indicate that Bacillus laterosporus DNase does not attack DNA from 3'-hydroxyl ends to yeild acid-soluble or acid-insoluble materials in a random manner. The results presented in this paper indicate that the nature of the attack of B. laterosporus nuclease is similar to that previously proposed for Micrococcus luteus DNase. The possibility of the sequential release of acid-insoluble intermediate fragments as well as acid-soluble products from the terminal portion of DNA by the enzyme is discussed.

Bacillus↗
PubMed1975

[A clinical survey of brain abscess (3rd report): special reference to chronological analysis of EEG on brain abscess (author's transl)].

The attention of those concerned with the management of intracranial abscess has been largely directed to a study of the findings in clinicopathological and neuroradiological investigations. Our object, in this communication is to arouse interest in the electroencephalographic survey, especially chronological electroencephalographic study of absecess patients. The clinical material forming the basis of this study is drawn from a series of 46 consecutive cases of intracranial abscess treated, during 3 years, in the neurosurgical department of Tokyo Women's Medical College.

Adolescent↗
PubMed1975

A nucleoside triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. Purification and characterization of the enzyme.

A deoxyribonuclease, which requires nucleoside triphosphate for reaction, has been purified about 150-fold from extracts of Bacillus laterosporus. Potassium phosphate and ethylene glycol stabilize the purified enzyme. The enzyme degrades double-stranded DNA about 100 times faster than heat-denatured DNA in the presence of nucleoside triphosphate. Double-stranded DNA is not degraded to any measurable extent in the absence of ATP, but the enzyme exhibits activity toward denatured DNA in the absence of nucleoside triphosphate, and this activity seems to be an intrinsic property of this enzyme protein. The optimum pH is 8.5 and the maximum activity is obtained in the copresence of Mg2+ (8.0 X 10(-3)M) and Mn2+ (7.0 X 10(-5)M). ATP and dATP are most effective and nucleoside di- or monophosphates are ineffective. ATP is converted to ADP and inorganic phosphate during the reaction and the ratio of the amount of ATP cleaved to that of hydrolyzed phosphodiester bonds of DNA is about 3:1. An inhibitor of the enzyme was observed in bacterial extracts prepared by sonic disruption; the inhibitory substance is produced in the bacteria in the later stages of cell growth. Preliminary results show that the inhibitor emerged near the void volume of a Sephadex G-200 column, and was relatively heat-stable, RNase-resistant, and DNase-sensitive.

Adenosine Triphosphate↗