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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 523 records · Page 29Linked to original sources
PubMed1978

[Measurement of cerebral blood flow with hydrogen clearance method: technique and a comparative study with the venous out flow method (author's transl)].

Local cerebral blood flow was measured with hydrogen clearance method in fifteen dogs and compared to direct measurement obtained by Michenfelder's venous out flow method. The sagittal sinus was exposed by a midline frontooccipital incision and extensive craniectomy. A tappered catheter was passed in to the superior sagittal. sinus. For measuring hydrogen clearance, platinum wire electrodes with a red tip of 0.5 mm in length and 0.3 mm in diameter were introduced into the parietal and occipital cortex. About ten percent hydrogen gas was given directly into the endotracheal tube for three to five minutes and the obtained clearance curves were transferred to semilog graph papers. Total cerebral blood flow was caliculated by bicompartmental analysis and compared to the two minutes initial slop index. The results are as follows. 1) A linear regression analysis of flows caliculated from the initial slope and bicompartmental analysis shows a high correlation coefficient. 2) There is a high correlation between flows caliculated from electrodes used at the same experiments. 3) Cerebral blood flow from the initial slope measured by hydrogen clearance method shows a high correlation wit flows caliculated from Michenfelder's venous out flow method.

Animals↗
PubMed1978

[Measurement of spinal cord blood flow in rabbits: central gray matter flow and CO2 reactivity (author's transl)].

Spinal cord blood flow (SCBF) was measured in 20 rabbits anesthetized with sodium pentobarbital. The platinum electrodes (0.3 mm in diameter) were inserted into the central gray matter of the thoracic spinal cord (Th8-10). In all animals, blood pressure and pAO2 remained constantly in the normal range. The pACO2 was changed by ventilation. Blood gases were checked both before and after each spinal cord blood flow measurement. The results are as follows. 1. Seventy-three percent of the clearances recorded from the gray matter were monoexponential and in the white matter almost all were monoexponential. 2. The mean values of gray matter SCBF of all animals was 38.3 +/- 1.85 ml/100 g/min (SE) at normo-capnea and the white matter was 19.5 +/- 1.33 ml/100 g/min. 3. An almost linear relationship exists between the pACO2 and SCBF. The values were 0.62 ml/100 g/min/torr in the gray matter and 0.38 ml/100 g/min/torr in the white matter.

Animals↗
PubMed1975

Brain tumors of early infants.

The authors describe their experience with ten cases of brain tumors in children in whom the onset of symptoms occurred within the first year of life, but who were operated on when they were 2 months to 4 years of age. The series includes 5 gliomas (4 supratentorial, 1 cerebellar; 3 astrocytomas, 1 spongioblastoma, 1 ependymoblastoma), 2 teratomas of the lateral ventricle, and 3 single cases of third ventricle choroid plexus papilloma, temporal lobe sarcoma, and a parasellar craniopharyngioma. Six cases were partially removed, one of them was shunted. Only biopsy was carried out in two, one of which was shunted. The only case of radical removal was a lateral ventricle teratoma; this patient died at operation. Nine patients survived at surgery, three of whom are alive on the 3rd, 4th, and 7th postoperative year. There were two late deaths: one at 2 years (lateral ventricle astrocytoma, which was only biopsied) and one at 7 years and 3 months (spongioblastoma) following surgery. This series from a 40-year period (1933-1973) represents 0.4% of 2,832 brain tumors and 1.9% of 528 brain tumors in the pediatric age. The authors emphasize the need to treat brain tumors in early infancy and insist on the use of radiotherapy and chemotherapy when the lesions are not radically removed at surgery.

Astrocytoma↗
PubMed1975

Antibiotic A-16316-C, a new water-soluble basic antibiotic.

A new water-soluble basic antibiotic named antibiotic A-16316-C was isolated together with antibiotic A-396-I and hygromycin B from a streptomyces strain identified as Streptoverticullium eurocidicus. The properties of the antibiotic A-16316-C were similar to those of destomycin B. But it was found that the antibiotic A-16316-C was not identical with destomycin B on the basis of NMR analysis. On acidic degradation antibiotic A-16136-C gave N, N'-dimethyl-2-deoxystreptamine, destomic acid and D-mannose. The gross structure for antibiotic A-16136-C was deduced from chemical reactions and spectral data.

Aminoglycosides↗
PubMed1974

Separation of the polypeptides of Chlamydia and its cell walls by polyacrylamide gel electrophoresis.

The polypeptide composition of Chlamydia was examined by acrylamide gel electrophoresis. When the polypeptide patterns of purified infectious elementary bodies (EB) of C. psittaci meningopneumonitis strain, 6BC strain, and C. trachomatis T'ang strain were compared, no significant differences were observed. The polypeptide patterns of whole EB and reticulate bodies (RB) appeared to overlap, but differences were found. In EB cell walls, nine main and several minor bands of polypeptides were observed in gels containing sodium lauryl sulfate, and the eighth main band from the top of the gel stained positive with periodic acid-Schiff reagent. On the other hand, the polypeptides in bands 3, 6, and 8 in EB cell walls were missing or minor in RB cell walls, and the ninth band was clearly stained by PAS. Band 8 was also stained slightly. Purified subunits, which occur as a lattice structure on the inside layer of EB cell walls but are largely missing in RB cell walls, contained bands 4, 6, and 8, and band 8 was PAS positive. These results indicate that significant polypeptide synthesis or reorganization in the cell walls occurs during the growth cycle.

Bacterial Proteins↗
PubMed1974

Hemagglutinin in cell walls of Chlamydia psittaci.

Intact purified elementary bodies (EB) of Chlamydia psittaci agglutinate chicken erythrocytes in low titer, whereas homogenates of EB and of EB cell walls agglutinate at much higher titers depending on the extent of disruption by shaking and sonication. The hemagglutinin is contained in the cell envelope and can be purified with cell wall fractions. Treatment of cell wall with sodium dodecyl sulfate completely inactivated the hemagglutinin. Purified hemagglutinin was found to have an identical polypeptide composition to EB cell walls. Preparations of purified reticulate forms, the reproductive intracellular form of the organism, were almost totally devoid of hemagglutinin.

Animals↗
PubMed1973

Electron microscope observations on the effects of polymixin B sulfate on cell walls of Chlamydia psittaci.

The effects of polymixin B sulfate on cell walls of mature elementary body (EB) and of immature developmental reticulate body (RB) of Chlamydia psittaci were investigated. When purified EB were treated with polymixin (10(4) units per ml or more) at 37 C for 60 min, about 70% of EB was found to be covered with a number of projections. Further incubation did not increase the percentage affected. The infectivity after treatment as assayed by the inclusion counting technique was reduced by 70% of the original titer. These results suggest that EB with the projections are no longer infective. The projections had obscure outlines and were 20 to 40 nm in diameter when seen in thin sections. In the negatively stained preparations, the projections were composed of aggregations of fine particles 4 to 5 nm in diameter. Treatment with sodium dodecyl sulfate at the same concentration used for cell wall isolation removed the projections completely, and the cell walls were converted to rather ragged forms apparently composed of outside and inside layers. When RB cell walls prepared from infected cells at 18 hr after infection were treated with polymixin at the same concentration, the projections having the same morphology with those seen on treated EB cell walls were observed only on the inside surface of cell wall.

Animals↗
PubMed1971

Electron microscopic observations on the structure of the envelopes of mature elementary bodies and developmental reticulate forms of Chlamydia psittaci.

Purified suspensions of Chlamydia psittaci were prepared from L cells. Thin sections of intact elementary bodies and intact developmental reticulate bodies and of their purified envelopes were observed by electron microscopy. In both intact organisms and partially purified envelopes, two membranous structures, each appearing in electron micrographs as two darkly stained layers, were observed. In the elementary body sections, the outer membrane was round, apparently rigid, and was not soluble in 0.5% sodium dodecyl sulfate. The inner layer was irregular in shape and was completely removed by detergent treatment. We interpret these results to indicate that the outer rigid layer of the envelope is the cell wall and the inner layer is the cytoplasmic membrane. When the fragile reticulate body envelopes were similarly studied, the outer cell wall was clearly visible, and some evidence of an inner membrane was seen. After treatment with nucleases and detergent, all evidence of inner or cytoplasmic membrane was removed, but the outer cell wall remained. Thus, it appears that the cell wall of this organism is continuous throughout the growth cycle and that the fragility and lack of rigidity of the reticulate body cell is due to changes in chemical composition or structure of the cell wall.

Cell Membrane↗