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Biomedical subjects

S Sakamoto

Publications and source records attributed to S Sakamoto.

At least 721 records · Page 40Linked to original sources
PubMed1983

Biosynthesis of O-phosphoserine-containing phosphoproteins by isolated bone cells of mouse calvaria.

Five groups of isolated bone cells from mouse calvaria were incubated with [3H]serine and the presence and amount of O-[3H]phosphoserine used as an indication of phosphoprotein synthesis. Cells in the osteoblastic fraction were the most active in synthesizing phosphoproteins, and unlike the other cell groups, released most of the phosphoproteins into the tissue culture medium. When subjected to molecular sieving and ion-exchange chromatography, the phosphoproteins synthesized by the bone cells of the osteoblastic group behaved like the phosphoproteins extracted from mouse calvaria by EDTA.

Animals↗
PubMed1983

Effects of estrogen and progesterone on thymidine kinase activity in the immature rat uterus.

The effects of progesterone and/or 17 beta-estradiol on thymidine kinase activity and autoradiograms were investigated in immature rats. Thymidine kinase activity increased more than thirtyfold above the control level 30 hours after 17 beta-estradiol injection. The enzyme activity induced by 17 beta-estradiol was suppressed by progesterone, the dose of which was approximately 1,000-fold that of 17 beta-estradiol. The specific thymidine kinase isozyme, which was separated from 17 beta-estradiol-induced uterine thymidine kinase by diethylaminoethyl (DEAE) cellulose column chromatography and not affected by deoxycytidine triphosphate, was involved in the DNA replication and inhibited by progesterone. The autoradiogram revealed many grains due to 3H-thymidine in the endometrial epithelium, stroma, and the myometrium in the immature rat 30 hours after 17 beta-estradiol injection, whereas progesterone reduced remarkably the number of grains induced by 17 beta-estradiol in the epithelium. Progesterone seems to inhibit the increment of the specific thymidine kinase isozyme induced by 17 beta-estradiol in the endometrial epithelium.

Animals↗
PubMed1983

Synergistic effect of estrogen and androgen on induction of uterine thymidine kinase activities in immature rats.

Estradiol-17 beta induced a significant increase in the uterine thymidine kinase activity with a characteristic isozyme pattern 30 h after injection into immature rats. Testosterone propionate also revealed a similar increase. Following combined injection of estradiol-17 beta and testosterone propionate, the overall and separate isozyme activities of thymidine kinase increased to nearly the total amount of those when each hormone was injected separately.

Animals↗
PubMed1983

[Preparation of progesterone secreting cells from rat ovaries by a density gradient].

Isolation of progesterone secreting cells from the ovaries of immature rats pretreated with pregnant mare serum gonadotropin (PMS) was conducted by a simple procedure which combined the collagenase digestion with a density gradient method. After digestion of the ovarian tissue slices by the enzyme, the residue was gently pressed and placed on a sucrose density gradient. Three bands appearing in the tube after centrifugation were designated as S-1, S-2 and S-3 from the top to the bottom, respectively. The S-1 cells from the ovaries at 6 days after PMS secreted the greatest amount progesterone, i.e. approximately 430 ng per 10(5) cells during the 18th incubation. Progesterone secretion from the S-2 cells was less than 48% of that from the S-1 cells. A physiological interrelation between the S-1 and S-2 cells remains unexplained by the present experiment. The luteal cells were yellow, spheroidal and 15 to 40 mus in diameter. Many vesicle-like particles were found on the cell surfaces. Progesterone secretion from the prepared cells was stimulated significantly by hCG in vitro. This result indicates that progesterone secreting cells isolated by the collagenase-sucrose density gradient preserve their native function as luteal cells. The procedure for preparation of luteal cells in the present report may provide a suitable model for in vitro studies on the corpus luteum.

Animals↗
PubMed1983

Differentiation of human leukemia cells and its usefulness for clinical diagnosis.

Various chemical inducers have effects on the induction of terminal differentiation of human myelogenous leukemia cell lines. We studied morphological and functional changes of human leukemia cells freshly obtained from patients using 12-0-tetradecanoyl phorbol-13-acetate (TPA), retinoic acid (RA) or dimethyl sulphoxide (DMSO). The myeloid leukemia cells cultured with TPA became adherent to plastic culture dishes, and then developed macrophage-like morphology with long filamentous pseudopods within 48 h incubation. They showed marked enhancement of the ability to phagocytose latex particles. But these acquired properties did not always parallel each other, suggesting that the mechanism of functional maturation of leukemic cells induced by chemical agents was not identical with that of morphological changes. On the other hand, the lymphoid leukemia cells did not show morphological and functional changes when cultured with the above inducers. It is suggested that exposure of leukemic cells to TPA for relatively short times (12-24 h) may be useful for determining whether they are of myeloid or lymphoid origin. These characteristic changes were also observed in leukemic cells from the myeloid or lymphoid crisis of chronic myelogenous leukemia.

Cell Differentiation↗
PubMed1983

In-vitro production of prostaglandin E, F and 6-oxo-prostaglandin F1 alpha by the uterine and ovarian tissues of pseudopregnant rabbits.

The production of prostaglandin (PG) E, PGF and 6-oxo-PGF1 alpha by the uterine and ovarian tissues of pseudopregnant rabbits was investigated at the various stages of pseudopregnancy. The production of PGE, PGF and 6-oxo-PGF1 alpha in the tissues tested was expressed as mean (+/-S.E.M.) ng/mg protein per 6h. The production of PGE by endometrial tissue was found to be slightly raised with levels ranging from 2.15 to 2.92 on days 13 - 19 compared with values on day 5 (P less than 0.01). Subsequently PGE production declined on day 22 to the same level as that on day 5. In the myometrial tissue the same tendency in PGE production was observed as in the endometrial tissue. A significant increase in PGF production in the endometrial tissues was observed on day 13 (4.08 +/- 0.56) compared with that on day 12 (1.28 +/- 0.17) (P less than 0.001). The highest activity was detected on day 19 (7.19 +/- 0.29). An abrupt decrease occurred on day 20. In the myometrial tissues there was a slight and gradual increase in PGF production from day 12 (1.88 +/- 0.18) until day 16 (3.22 +/- 0.21). A sudden decline in the activity was detected after day 17. A marked increase of the 6-oxo-PGF1 alpha production activity in the myometrial tissues was observed on days 12 - 20 ranging from 14.60 to 19.25 compared with that on day 5 (P less than 0.001). The maximum activity was detected on day 16 (19.25 +/- 2.76). In the endometrium significant increase ranging from 4.85 to 8.31 occurred continuously from days 14 - 20 compared with that of day 12 (P less than 0.01). The myometrial tissue was shown to be significantly more potent in 6-oxo-PGF1 alpha production than endometrial tissue (P less than 0.01). No significant increase of PGE and PGF production activity was detected in the ovarian tissues throughout pseudopregnancy. The corpora lutea were shown to have very low 6-oxo-PGF1 alpha production activity. The 6-oxo-PGF1 alpha production activity of the remaining ovarian tissue was demonstrated to be significantly (P less than 0.01) more potent than the corpus luteum. The endometrial tissue of pseudopregnant rabbits has marked PGF2 alpha production activity in the late stage of pseudopregnancy, whereas the myometrial tissue is remarkably potent in 6-oxo-PGF1 alpha synthesis. Conversely, ovarian tissues showed much lower PG production activity than the uterine tissues. These experiments suggest that the main site of PGF production in luteolysis may be the endometrium and not the ovary itself. The physiological significance of PG production in relation to luteolysis is discussed.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

5-methyltetrahydrofolate-related enzymes and DNA polymerase alpha in normal and malignant hematopoietic cells.

The activities of 5-methyltetrahydrofolate (5-CH3-THF)-related enzymes [5-CH3-THF homocysteine methyltransferase and 5,10-methylenetetrahydrofolate (5,10-CH2-THF) reductase] and DNA polymerase alpha were measured in normal and malignant hematopoietic cells. The 5-CH3-THF homocysteine methyltransferase activity was significantly correlated with 5,10-CH2-THF reductase activity, indicating that the hematopoietic cells with active biosynthesis of tetrahydrofolate from 5-CH3-THF also actively synthesize 5-CH3-THF from 5,10-CH2-THF. The activities of 5-CH3-THF-related enzymes had a tendency to be high in lymphoid cells and low in myeloid cells, and were not correlated with the percentage of blasts and immature cells in the samples examined. Fairly good correlations were observed among these three enzymes in non-malignant bone marrow cells. However, the activities of two of the enzymes correlated only weakly overall with DNA polymerase alpha activity in normal and malignant hematopoietic cells. Generally speaking, DNA polymerase alpha activity correlated well with the percentage of blasts and immature cells in the samples examined.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1983

Antigenic characteristics and genome composition of a naturally occurring recombinant influenza virus isolated from a pig in Japan.

We performed antigenic analysis of the haemagglutinin and neuraminidase subunits of a recombinant virus (A/swine/Kanagawa/2/78) isolated from a pig in Japan in 1978, using a series of monoclonal antibodies to H1 (Hsw1) haemagglutinin and N2 neuraminidases of H2N2 and H3N2 viruses. Results obtained in haemagglutination inhibition tests with five monoclonal antibodies to the haemagglutinin of A/NJ/8/76 (H1N1) revealed that the haemagglutinin of three H1N1 and the recombinant viruses were indistinguishable from that of A/NJ/8/76. The neuraminidase of A/swine/Kanagawa/2/78 was found to be antigenically similar to A/Kumamoto/22/76 (H3N2, A/Victoria/3/75-like strain). The oligonucleotide maps of the entire RNAs of H1N1, H1N2 and H3N2 viruses showed that A/swine/Kanagawa/2/78 (H1N2) virus was more similar to swine (H1N1) virus than to A/Kumamoto/22/76 (H3N2) virus. Radioactive cDNA was prepared by reverse transcription of the recombinant virus RNA using a dodecadeoxyribonucleotide primer and used in DNA-RNA hybridization experiments. The results obtained in molecular hybridization based on blotting procedures showed that all cDNA segments except gene 6 hybridized efficiently with RNAs of swine (H1N1) influenza virus. The sixth cDNA segment was homologous to the corresponding RNA segment of H3N2 virus. The genetic relatedness of A/swine/Kanagawa/2/78 (H1N2) with either A/swine/Kanagawa/4/78 (H1N1) or A/Kumamoto/22/76 (H3N2) was clearly established by hybridization between the cDNA segment probes and viral RNA. It was concluded that the neuraminidase gene of A/swine/Kanagawa/2/78 (H1N2) was derived from a human H3N2 virus, while the seven other genes were from a swine H1N1 virus.

Animals↗
PubMed1983

T cell-activating monokines in guinea pigs: comparison of high and low molecular weight factors.

Guinea pig monokines produced by lipopolysaccharide-stimulated peritoneal macrophages were found in high (50,000-80,000) and low (10,000-30,000) molecular weight (m.w.) fractions by gel filtration. Both showed enhancing activity on the proliferative response of guinea pig and mouse thymocytes to PHA, but the high m.w. (65K) monokine was much more efficient than the low m.w. (15K) monokine in enhancing the response of lymph node T cells to PHA, suggesting its importance in the activation of peripheral T cells. The 65K monokine was coeluted with BSA present in the culture medium by DEAE-cellulose chromatography, but was clearly separated from it by hydroxylapatite chromatography. The immunoadsorption experiment with anti-BSA-coupled gel also indicated that 65K monokine is not a complex of low m.w. monokine with BSA. Our series of studies showed that most monokine activities were always found in the 65K fraction in guinea pigs. Thus, in guinea pigs, the 65K component appears to constitute a major class of T cell-activating monokines.

Animals↗
PubMed1983

Platelet reactivity and its dependence on alpha-adrenergic receptor function in patients with ischaemic heart disease.

We studied 57 patients admitted to hospital with ischaemic heart disease, including nine patients with variant angina, to evaluate platelet reactivity and its dependence on alpha-adrenergic receptor function. The threshold concentration for biphasic platelet aggregation in response to adrenaline and adenosine diphosphate was measured in fresh platelet rich plasma. There were age related alterations in platelet responsiveness to adrenaline. In 27 age matched control subjects platelets showed adrenaline induced aggregation at a concentration higher than 0.1 mumol. The threshold concentrations for adrenaline and adenosine diphosphate were 0.91 mumol and 4.68 mumol. In 16 patients with acute infarction, 14 with old infarction, nine with effort angina, and nine with rest angina, mean values of platelet aggregation threshold for both adrenaline and adenosine diphosphate were not altered significantly when compared with control subjects. In contrast, the values for adrenaline and adenosine diphosphate in nine patients with variant angina were 0.012 mumol and 2.24 mumol and seven of them showed obvious platelet hyperactivity to adrenaline at a concentration lower than 0.1 mumol. The threshold concentration for adrenaline induced aggregation did not correlate with serum cholesterol and triglyceride levels.

Adenosine Diphosphate↗
PubMed1983

Metabolism of 14C-pregnenolone in the placenta throughout pregnancy in organ culture.

The present study was undertaken to assess the metabolism of radiolabeled pregnenolone in the placenta throughout pregnancy in organ culture. The product generated from pregnenolone was only progesterone regardless of the weeks of gestation. The amount of progesterone formed by the placenta was 5.60 +/- 0.15 x 10(-11) moles/mg protein/hour in the 1st trimester (n = 4), 6.47 +/- 0.09 x 10(-11) moles/mg protein/hour in the 2nd trimester (n = 3) and 7.72 +/- 0.25 x 10(-11) moles/mg protein/hour in the 3rd trimester (n = 6). The increase in the formation of progesterone as gestation advanced was statistically significant. The increase in the placental weight throughout pregnancy was in proportion to the rise in maternal plasma levels of progesterone. These data indicate that the manifold increase in progesterone in the maternal circulation as gestation advances mainly reflects the increase in the functional mass of the placenta rather than the increased rate of production of progesterone in the placenta.

Carbon Radioisotopes↗
PubMed1983

Beneficial effects of the coronary collateral circulation on tachycardia-induced myocardial ischemia during experimental coronary stenosis.

This study was designed to determine whether coronary collaterals have preventive effects on tachycardia-induced myocardial ischemia under partial restriction of proximal coronary artery inflow. Studies were carried out in dogs with developed coronary collaterals and control dogs. ST-elevation in epicardial and intramyocardial electrograms was used for assessing the degree of regional myocardial ischemia. In control dogs with coronary constriction (80% reduction of i.d.) pacing-induced tachycardia produced significant ST-elevation, 1.48 +/- 0.17 mV in the inner layer and 0.79 +/- 0.29 mV in the middle layer at a cardiac rate of 150/min, 3.58 +/- 0.38 mV in the inner layer, 2.73 +/- 0.38 mV in the middle layer, and 1.93 +/- 0.36 mV in the outer layer at a rate of 180/min. In dogs with moderate collaterals ST-segment elevation was only 1.41 +/- 0.18 mV in the inner layer and 0.96 +/- 0.24 mV in the middle layer at a rate of 180/min. In dogs with abundant collaterals there was no significant ST-elevation during tachycardia. These findings indicate that blood supply to the affected myocardium via developed collaterals is sufficient to meet graded increases in metabolic requirements under the condition of limited coronary flow reserve in an experimental model simulating angina pectoris.

Animals↗
PubMed1983

Effects of ergonovine-induced vasoconstriction on the genesis of myocardial ischemia during coronary stenosis in dogs.

We developed a canine model with coronary stenosis produced by intraluminal obstruction with a micro-balloon occluder to assess the role of vasomotor tone of a large coronary artery with a preexisting fixed stenosis in the genesis of myocardial ischemia. Hemodynamic and electrocardiographic responses to ergonovine, an agent capable of provoking coronary spasm, were evaluated. In the absence of coronary stenosis, intracoronary infusion of 4 micrograms/min ergonovine had no systemic and coronary hemodynamic effects. Similarly, with various degrees of external obstruction created by a screw-type metal constrictor, ergonovine had little hemodynamic effects. By contrast, with a stenosis greater than 28.4 +/- 5.0 mmHg in pressure gradient, created by intraluminal obstruction which preserved active arterial vasomotion, ergonovine-induced vasoconstriction produced a marked decrease in coronary blood flow and distal coronary pressure, followed by ST-elevation. These deleterious effects of ergonovine on coronary hemodynamics were reversed completely by intracoronary infusion of nitroglycerin. Our results indicate that the effects of normal coronary arterial vasomotor activity on a stenosed vessel can cause myocardial ischemia.

Animals↗