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Biomedical subjects

S Sawada

Publications and source records attributed to S Sawada.

At least 397 records · Page 22Linked to original sources
PubMed1988

Additive feature of long-term potentiation and phorbol ester-induced synaptic enhancement in the mossy fiber-CA3 synapse.

Application of phorbol esters, selective activators of protein kinase C (PKC), causes a long-lasting enhancement of synaptic transmission in the hippocampus. We examined the relationship between this phorbol ester-induced enhancement of synaptic transmission and long-term potentiation (LTP) quantitatively in the mossy fiber-CA3 synapse of the guinea pig hippocampus in vitro. Potentiating action of 0.5 microM phorbol 12,13-diacetate (PDAc) on synaptic transmission was almost unaffected by preceding tetanic stimuli which had caused a full development of LTP. Tetanic stimulation induced LTP even after synaptic transmission had been enhanced by 0.5 microM PDAc. Quantitative estimations revealed that PDAc-induced synaptic enhancement and LTP were simply additive to each other. The relation between LTP and PKC activation is discussed.

Action Potentials↗
PubMed1988

Reversed dose-rate effect and RBE of 252-californium radiation in the induction of 6-thioguanine-resistant mutations in mouse L5178Y cells.

The effects of californium-252 radiation (average neutron energy E = 2.13 MeV) were investigated using mouse leukemia L5178Y cells. No dose-rate effect was detected for cell killing, but a 'reversed' dose-rate effect was observed for mutation induction. The frequency of 6-thioguanine-resistant mutations increased linearly up to 100 cGy (1 Gy = 100 rad), then began to level off at a dose rate of 1.2 cGy/min, while it increased continuously up to 200 cGy at a reduced dose rate of 0.16 cGy/min. Compared with results obtained using 60Co gamma-rays, the ratio of the initial slope of each dose-response curve was 4-5 for cell killing, and more than 11 for mutagenesis. Since one-third of 252Cf radiation consists of gamma-rays, the relative biological effectiveness (RBE) of 252Cf neutrons would be even greater, 16 or more, for mutation induction in the present assay.

Animals↗
PubMed1988

Serum lipid levels in elementary and junior high school children and their relationship to relative weight.

Serum lipid levels were measured in 2,626 schoolchildren ages 7 to 15 years in three elementary schools and one junior high school in a suburban area of Osaka during 1984-1985. The mean cholesterol levels increased with age in boys ages 7 to 10 years (from 156 to 177 mg/dl) and then decreased at age 13, after which the levels again increased slightly until age 15. Girls showed a similar tendency with a peak at age 10 and a minimum at age 12. Cholesterol levels were significantly lower in junior high school boys (a mean of 154-161 mg/dl for ages 13-15 years) than in girls of the same age or in boys and girls ages 10 to 12 years in the upper grades of elementary school. Cholesterol and triglyceride levels tended to be lower or the high-density lipoprotein cholesterol levels higher in elementary schools where boys and girls engaged in physical exercise than in schools where the children were not strongly encouraged to exercise. About 50% of the hypertriglyceridemic children were obese.

Adolescent↗
PubMed1988

Soft X-ray dosimetry and RBE for survival of Chinese hamster V79 cells.

Dosimetry and biological effects of 40 and 50 keV low-energy X-rays generated by a SOFTEX Model CMBW-2 apparatus were studied. Doses were measured using a thin-window parallel-plate ionization chamber; beam quality was assessed using aluminum absorbers; exposure rates per unit current were determined according to the X-ray tube current and exposure times; and thermoluminescent (BeO chip) dosimeters were used to ascertain dose distributions in the irradiation field. The average correction factors for nonuniformity were calculated from the measured dose distributions. The means for ascertaining accurate exposures and doses using these methods are discussed. The dose-survival relationship of Chinese hamster V79 cells were assessed by irradiating them with 40 and 50 kV soft X-rays, 180 kV X-rays, and 60 Co gamma rays. Soft X-rays with three distinct effective energies were tested by changing the tube voltage kV and aluminium filter thicknesses; namely (1) 40 kV without filter, (2) 40 kV with a 0.2 mm thick aluminium filter and (3) 50 kV with a 0.7 mm thick aluminium filter. The effective energies obtained according to attenuation measurements using aluminium for these soft X-rays were 8.1, 11.7 and 18.5 kV, respectively. In this study the relative biological effectiveness (RBE) at 10 per cent survival compared with 60Co gamma rays ranged from 1.5 to 1.6. The RBE of 180 kV X-rays relative to 60Co gamma rays was 1.29. This study provided experimental data for the RBE of V79 cells in the intermediate energy range between hard and ultrasoft X-rays, data for which were previously reported by Goodhead and co-workers (1977, 1979, 1981).

Aluminum↗
PubMed1988

Monte Carlo calculations of doses to tiles irradiated by 60Co and 252Cf simulating atomic bomb gamma-ray fluences.

Dose calculations for tiles exposed to the Hiroshima atomic bomb radiations were undertaken. A Monte Carlo code, ABOMB, was developed which considers the characteristics of atomic bomb gamma-ray fluences and geometrical configurations. ABOMB was applied to tile dose calculations for the available photon sources with definite fluences. Its validity was tested by comparing the depth-dose curves calculated for 60Co and 252Cf beams with the equivalent experimental data obtained in the laboratory. Selection of parameters, contribution of backscattering, and computing time also were considered. Present calculations are considered to be accurate with uncertainties less than +/- 10%, and may be useful for correcting or reinforcing atomic bomb gamma-ray doses, together with tile dose measurements by thermoluminescent (TL) dosimetry.

Californium↗
PubMed1988

Medical x-ray exposure doses as contaminants of atomic bomb doses.

Since 1967 at the times of their biennial ABCC/RERF radiological examinations, all Adult Health Study (AHS) subjects have been interviewed to determine the exposures to medical x-rays they experienced in institutions other than RERF in order to estimate the numbers of examinations and corresponding doses which they received. These data have been stored on computer tapes together with the doses these subjects received during their radiological examinations in the ABCC/RERF Department of Radiology. Thus, their medical x-ray doses are available along with their atomic bomb doses (tentative 1965 doses revised, T65DR) for assessment of the role of ionizing radiation in the development of diseases. The medical x-ray doses incurred at RERF were assessed by means of phantom dosimetry. Those at other institutions were determined using phantom dosimetry data and results of surveys for trends in radiological examinations in Hiroshima and Nagasaki. By the end of 1982, the average medical x-ray doses to the active bone marrow were 12.04 mGy for A-bomb exposed groups and 8.92 mGy for control groups (not-in-cities); to the male gonads, 2.26 mGy and 1.89 mGy, respectively; and to the female gonads, 17.45 mGy and 12.58 mGy, respectively. Results for Hiroshima and Nagasaki were similar. The main impact of medical x-ray doses was in the lowest T65DR group. Medical x-ray active bone marrow doses ranged from 0.05-500% (mean, 35%) of A-bomb doses in the 10-99 mGy T65DR group. In the 100-999 mGy T65DR group, medical x-ray active bone marrow doses ranged from 0.005-50% (mean, 5%) of their T65DR. In the greater than 1,000-mGy T65DR group, medical x-ray exposures were proportionally less. Female active bone marrow and gonad doses were similar in magnitude to the male active bone marrow doses. Medical x-ray exposures produced smaller doses to the gonads of males than to those of the females. The use of medical x-rays is steadily increasing. Careful consideration of doses from medical sources is essential for reliable assessments of the effects from exposures to the atomic bombs.

Adult↗
PubMed1988

Iodized oil in the portal vein after arterial embolization.

Transcatheter embolization with a relatively large amount (average, 17 mL) of iodized oil and doxorubicin hydrochloride with or without gelatin sponge particles was performed in 50 patients with hepatocellular carcinoma and in eight patients with liver metastases. After an intraarterial hepatic injection of an emulsion of iodized oil and doxorubicin hydrochloride, iodized oil was seen in the portal vein; the amount correlated with the amount that was injected, despite the lack of arterioportal shunting. Prominent portal vein appearances were seen in six of 21 cases (29%) given 10 mL or less of iodized oil, in 14 of 21 cases (67%) with 10-20 mL, and in 18 of 21 cases (86%) with more than 20 mL. Iodized oil may enter the portal vein through an arterioportal communication after pooling in the sinusoids.

Animals↗
PubMed1988

Fibrinopeptide A (FPA) levels in atrial fibrillation and the effects of heparin administration.

It has been reported that a patient with atrial fibrillation (AF) is in the hypercoagulable state and that this state results in a high incidence of systemic thromboembolisms. In this paper, we have investigated plasma fibrinopeptide A (FPA) levels and the effects of subcutaneous administration of heparin on these levels in patients with AF. Forty-five patients with hypertension (HT) or mitral stenosis (MS) were classified into four groups according to whether they had AF complications; i.e. HT with normal sinus rhythm (NSR), HT with AF, MS with NSR and MS with AF. Patients with AF demonstrated significantly higher plasma FPA levels and lower plasma antithrombin III (AT III) activities than those with NSR. When low dose heparin was administered to patients with AF, plasma FPA levels were decreased to the near normal range, accompanied by an increase in heparin-AT III complex activity and heparin concentration 0.5-1.0 h after injection. These levels were maintained for 5 h. From these results it was concluded that patients with AF were in the hypercoagulable state and that the measurement of plasma FPA levels provided a possibility to detect the underlying activation of blood coagulation.

Atrial Fibrillation↗
PubMed1988

[Functions of large granular lymphocytes--a case of large granular lymphocytosis with characteristic cell surface antigens].

A 58-year-old male visited the hematological clinic of Surugadai Nihon University Hospital, Tokyo, complaining of numbness around both elbows. The peripheral leukocyte count was 12,400/microliters, and large granular lymphocytes (LGL) occupied 79% of the leukocytes. The cell surface antigen studied by flow cytometry were the positive CD 2, 3, 5, 8, 11, and Leu-7, and the negative CD1, 4, 10, 16 (Leu-11), 19, 20, and OKTIa1. IgG-FCR checked by mean of the EA-rosette formation was positive. The LGL showed the negative NK cell activity and the positive ADCC and LAK cell activities. It was interesting that LGL was negative for CD16 (Leu-11) while they had ADCC activity. Since the rearrangement of the receptor gene in T-cells was demonstrated by the southern blot analysis, the proliferation of LGL was considered to be a clonal one. LGL did not inhibit the colony formation of granulocyte and erythrocyte precursors in the plasma clot culture. It was thus considered that this might partially explain the fact that the patient's neutrophil, Hb and platelet levels remained normal.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1988

[The influence of radiotherapy on T lymphocyte subpopulations analyzed by monoclonal antibodies].

The effect of therapeutic irradiation upon the lymphocyte subpopulation has been investigated in patients with cervical uterine cancer. The influence of radiotherapy was studied on lymphocyte subpopulations analyzed by monoclonal antibodies such as anti-Leu 2a, anti-Leu 3a, anti-Leu 4, anti-Leu 12, and anti-Leu 11a by a FACS analyzer, and by the PHA (phytohemagglutinin) response in 29 patients with cervical uterine cancer. The absolute counts of the various lymphocyte subpopulations were seen to remarkably decrease during radiation therapy, however, their percentages remained unchanged. As for 17 patients with cervical uterine cancer who each received a radical operation, the Th/Ts (T helper T/suppressor) ratio was seen to slightly decrease during radiation therapy. In contrast, in the remaining 12 patients with cervical uterine cancer who each received radiotherapy alone, the Th/Ts ratio was found to be higher than the former cases. This suggests that this phenomenon might be caused by the presence or absence of a tumor.

Antibodies, Monoclonal↗