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Biomedical subjects

S Antoku

Publications and source records attributed to S Antoku.

At least 37 records · Page 2Linked to original sources
PubMed1983

Protection of cultured mammalian cells by S-2-(3-aminopropylamino)ethylphosphorothioic acid(WR-2721).

The ability of WR-2721 to protect cultured mammalian cells against radiation-induced killing was nearly the same as that of cysteamine when WR-2721 was activated by mouse liver extract. Without the liver extract, protection by WR-2721 required long incubations with the cells prior to irradiation. The protective activity increased in proportion to the cell concentration. The dose reduction factor at a concentration of 4 mM WR-2721 was 1.11 and 1.41 for 1.5 X 10(5) cells/ml and 15 X 10(5) cells/ml of cultured cells, respectively. A non-protein bound sulfhydryl group was detected in cell suspensions after incubation with WR-2721, but it was not a dephosphorylated product of WR-2721.

Amifostine↗
PubMed1983

Radiosensitization and radioprotection of E. coli by thiourea in nitrous oxide saturated suspensions.

N2O did not modify the radiosensitivity of E. coli BH and H/r-30 strains as to colony-forming ability and DNA single-strand breaks. In N2O-saturated suspensions of E. coli, thiourea and thiosemicarbasite sensitized at low concentrations, while cysteamine and cysteine protected at all concentrations. Protection by thiourea in N2O-saturated suspensions was observed only in the frozen state. These results suggest that the conversion of e-aq to OH radicals may be responsible for sensitization and this sensitization is probably due to the thiourea and thiosemicarbasite radicals produced extracellularly.

Cysteamine↗
PubMed1982

A device for the reduction of population dose.

Conventional dental radiographic procedures do not permit direct visualization of the radiation field or the central ray. As a result, it is necessary to use a beam diameter larger than the film in order to prevent an unnecessarily high number of cone cuts or other errors during visual alignment of the cone and film. The modification of a conventional dental x-ray cone which permits the central ray to be depicted by a beam of light is described. The use of the device significantly reduced the number of cone cuts, even when small beam diameters were used. Visualization of the central ray improved radiographic accuracy and has the potential to significantly reduce the over-all dose to the population by reducing the size of the field used for dental radiography.

Equipment Design↗
PubMed1981

Malignant neoplasms among atomic bomb survivors following radiation therapy.

A second follow-up survey for radiation therapy exposure among a fixed cohort of A-bomb survivors originally numbering 20 000 persons identified 55 more who had received radiation therapy, and 7 more therapy-associated malignancies. In the previous and present investigations, 12 postirradiation malignancies were identified among 190 cohort members (6%) who received radiation therapy. This investigation underscored the necessity for documenting exposures to ionizing radiation for medical reasons, especially exposures incurring relatively high doses, among persons at relatively high risk of developing neoplasms, such as A-bomb survivors, and in malignancy epidemiology to exclude bias in estimates of risk.

Adolescent↗
PubMed1977

A semi-automated measurement of urinary catecholamines using high-speed ion-exchange column chromatography.

Semi-automated measurement of urinary catecholamines, specific for dopa, noradrenaline, adrenaline and dopamine and other metabolites has been developed. Steps included alumina extraction, separation by high-speed ion-exchange column chromatography and fluorescent development by trihydroxyindole (THI) method without interference by other fluorescent substances. Recovery, reproducibility and sensitivity were satisfactory. alpha-Methyldopa, a metabolite of alpha-methyldopa, and isoproterenol were separated completely without interfering with the measurement of noradrenaline, adrenaline and dopamine.

Adult↗
PubMed1977

Effect of oxygen on bacteria and cultured mammalian cells irradiated in the frozen state.

The oxygen effect for bacteria and cultured mammalian cells at -196 degrees C was studied, using suspensions to which were added cryoprotective and chemical protective agents. The oxygen enhancement ratio (o.e.r.) in the frozen state was dependent on the chemicals added to the suspensions. When the chemicals had a high competitive reactivity with oxygen to the damage, the o.e.r. in the frozen state was comparable to that in the liquid suspensions. Without chemicals, the o.e.r. in the frozen state decreased significantly, probably because of the low competitive activity of endogenous SH compounds. In general, the systems with a higher o.e.r. in the liquid state had a lower o.e.r. in the frozen state.

Cell Survival↗
PubMed1976

Doses to critical organs from dental radiography.

Participants in the jointly sponsored Atomic Bomb Casualty Commission and Japanese National Institute of Health (ABCC-JNIH) Adult Health Study, a fixed-population sample under continual observation for late effects of the atomic bombs, are also being evaluated for their exposure to other sources of ionizing radiation. In the present study, the subjects' thyroid, lens, pituitary, bone marrow, and gonadal doses acquired during dental radiography were estimated from dosimetry of simulated human material exposed according to technical factors as ascertained in previously reported surveys of patients, dental clinics and hospitals, and dosimetry with phantom human material containing lithium fluoride thermoluminescence dosimeters and ionization chambers. Dental radiography comprised a relatively small segment of the contaminating sources of ionizing radiation exposure among this population sample. Efforts should be made to improve exposure conditions, especially in view of the increasing frequency of dental x-ray examinations.

Head↗
PubMed1976

Radiation therapy among A-bomb survivors.

Survey of hospitals and clinics where atomic bomb survivors and their comparisons reported having received radiation therapy confirmed that 137 were so treated. The malignancies of five subjects were possibly related to their earlier radiation therapy rather than their atomic bomb radiation exposure, stressing the importance of recording all medical X-ray exposures as a potential variable in epidemiological studies of cancer etiology.

Environmental Exposure↗