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Biomedical subjects

M Terada

Publications and source records attributed to M Terada.

At least 577 records · Page 32Linked to original sources
PubMed1981

Changes in amount of hypo-modified tRNA having guanine in place of queuine during erythroid differentiation of murine erythroleukemia cells.

The amounts of hypo-modified tRNAs having guanine in place of queuine in murine erythroleukemic cells decreased markedly when the cells differentiated into mature erythroid cells. The amounts of these hypo-modified tRNAs can be determined easily by measuring incorporation of labeled guanine into tRNA with Escherichia coli tRNA--guanine transglycosylase. The decrease was detected at on early stage of erythroid differentiation: namely, before any detectable increase in the percentage of cells containing hemoglobin. The amount of guanine-accepting tRNA species was nearly proportional to the percentage of undifferentiated cells in the population, regardless of the type of inducer used. Decrease in the amounts of hypo-modified tRNAs in the cells was effectively blocked by 12-O-tetradecanoylphorbol 13-acetate, which inhibits differentiation of these cells. 8-Azaguanine, which is known to be substrate of tRNA--guanine transglycosylase, was incorporated almost exclusively into the first position of hypo-modified tRNA in murine erythroleukemic cells when they were pulse-labeled in culture with 8-azaguanine, suggesting strongly that tRNA-guanine transglycosylase in the cells is actually involved in incorporation of 8-azaguanine into tRNA in vivo. The amount of 8-azaguanine incorporated into tRNA in differentiated cells was one third of that in undifferentiated cells, the decrease being parallel with that in the amount of guanine-accepting tRNA in these cells. The results suggest that the appearance of hypo-modified tRNAs in the transformed cells was due to lack of substrate for queuosine biosynthesis in tRNA.

Animals↗
PubMed1980

Induction of differentiation of human and murine myeloid leukemia cells in culture by tunicamycin.

Tunicamycin, an antibiotic that specifically blocks the synthesis of N-acetylglucosamine-lipid intermediates and thereby prevents glycosylation of glycoproteins, induced differentiation of both human (HL-60) and murine (M1) myeloid leukemia cell lines in culture. At 0.1-1.0 microgram/ml, it induced differentiation of both HL-60 and M1 cells, characterized by increase in phagocytic cells and changes to resemble mature myeloid cells. Fc receptors were also induced in M1 but not in HL-60 cells; induction of intracellular lysozyme activity was not detected in either HL-60 or M1 cells. With this concentration of tunicamycin, there was marked decrease in rate of incorporation of radioactive glucosamine into macromolecules and a decrease in the rate of DNA synthesis. These data show that glycosylation of cellular proteins has an important role in maintaining these myeloid leukemia cells in an undifferentiated state in culture. The results also indicate that induction of phagocytosis in both HL-60 and M1 myeloid leukemia cells and of Fc receptors in M1 cells does not require continued synthesis of the oligosaccharide portions of cellular proteins by the lipid-linked pathway.

Cell Differentiation↗
PubMed1980

A low-molecular-weight translocation modulator and its interaction with a macromolecular translocation inhibitor of the activated receptor-glucocorticoid complex.

When rat liver cytoplasm free of glucocorticoid receptors was dialyzed, its inhibitory effect on nuclear uptake or binding of already "activated" receptor-glucocorticoid complex increased. A macromolecular fraction and a low-molecular-weight fraction separated from the cytoplasm by gel filtration both inhibited nuclear uptake or binding of the activated complex. The macromolecular fraction was much more inhibitory than the low-molecular-weight fraction. When the two components were mixed, their inhibitory effects decreased. These results suggest that, in addition to the macromolecular translocation inhibitor(s) known to be present in rat liver cytoplasm, there is a low-molecular-weight factor(s) which is also involved in the process of translocation of the activated receptor-glucocorticoid complex to the nucleus. The mechanism of action of this modulator is unknown, but its inhibitory effect seems to be due to its direct interaction with the activated receptor-steroid complex.

Animals↗
PubMed1980

Spasmogenic effects of L-ascorbic acid on the guinea pig isolated ileum preparation.

The mechanism of actions of L-ascorbic acid (AA) on the guinea pig isolated ileum wasstudied. AA (neutralized, 10(-3) M) produced a stimulated motility (A effect) and a potentiation in acetylcholine (ACh)-induced contraction (B effect). The A effect showed a tachyphylaxis, and was inhibited by tetrodotoxin, atropine, adenosine, morphine, strychnine, Mg2+, papaverine and glucose- and Ca2+-free medium, but was stimulated by eserine. Thus, AA appears to have not only a direct myogenic effect but also a neurogenic effect by stimulating ACh release from intramural cholinergic nerves.

Adenosine↗
PubMed1980

Effect of l-ascorbate 2-sulfate on fatty liver and hyperlipidemia induced by various treatments in rats and guinea pigs.

Effects of L-ascorbate 2-sulfate (AAS) on fatty liver and hyperlipidemia induced by various treatments were studied in rats and guinea pigs. L-Ascorbic acid (AA) (50 or 175 mg/kg), a reference compound, lowered the lipid levels in the serum and/or liver in guinea pigs, while AA had little effect in rats. On the other hand, AAS (300 mg/kg) was effective in both animals. In rats, AAS lowered cholesterol and triglycerides in the serum from ethionine-treated animals and in the liver from orotic acid-supplemented animals. In guinea pigs, this compound lowered cholesterol and triglycerides in the serum from ethionine-treated animals, lipids in the liver from cholesterol-supplemented animals, and lipids in the serum and liver from scorbutic animals. AA markedly increased the content of AA in the organs in all experiments, while AAS had a slight effect. Thus, it is suggested that AAS exerts its hypolipidemic and lipotropic effects by the specific actions of AAS.

Animals↗
PubMed1980

Aminotransferase activities and involution of the thymus in rats bearing AH 130 tumors.

Involution of the thymus was observed in rats bearing AH 130 (solid-type) tumors. The thymus weight decreased with tumor growth. Daily injection of a pharmacological dose of hydrocortisone into normal rats resulted in involution of the thymus and marked increase in alanine aminotransferase activity. This treatment also caused slight increase in the activity of tyrosine aminotransferase but not of aspartate aminotransferase in these animals. Involution of the thymus in tumor-bearing rats, however, was not accompanied by appreciable increases in the activities of these aminotransferases, even at an advanced stage of tumor growth when the plasma corticosterone level was very high and significant increase in the activities of all these enzymes was observed in the liver. Further, additional injections of hydrocortisone into rats with tumors weighing more than 5% of the body weight did not cause any appreciable change in alanine aminotransferase activity in the thymus, although in rats with smaller tumors it slightly increased the enzyme activity in the thymus. Furthermore, in normal rats, increase in alanine aminotransferase activity in the thymus with involution of the glands was observed with a dose of corticosterone close to the physiological range attained in rats with tumors in an advanced stage.

Alanine Transaminase↗
PubMed1980

[The specificity of pharmacological responses in Ascaris muscle (author's transl)].

To investigate the pharmacological properties of Ascaris muscle, comparative studies were undertaken on the actions of various drugs on Ascaris muscle, guinea pig isolated ileum and frog isolated rectus preparations. In Ascaris muscle and frog isolated rectus preparations, the contractile activities with acetylcholine (ACh, 10(-5) g/ml in Ascaris and 10(-6) g/ml in frog rectus) and 1, 1-dimethyl-4-phenylpiperazinium (DMPP, 10(-6) g/ml) were inhibited significantly and reversely by d-tubocurarine (d-Tc, 10(-5) g/ml) and mecamylamine (Meca, 10(-5) g/ml), and slightly by atropine (Atr, 10(-4) g/ml) and hexamethonium (C6, 10(-4) g/ml). In guinea pig isolated ileum preparation, the contractile activity with ACh (10(-6) g/ml) was inhibited markedly and reversely but Atr (10(-6) g/ml), while the activity with DMPP (10(-6) g/ml) was similarly inhibited by Meca (10(-6) g/ml), C6 (10(-6) g/ml) and Atr (10(-6) g/ml). Although frog isolated rectus preparation was contracted with 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium (McN-A-343, 10(-5) g/ml) but not with pilocarpine (10(-4) g/ml), Ascaris muscle preparation was not affected by these agonists. Frog isolated rectus preparation was contracted with 5-hydroxytryptamine (5 HT, 10(-4) g/ml) but was not affected by histamine (His, 10(-3) g/ml) and gamma-aminobutyric acid (GABA, 10(-4) g/ml), whereas Ascaris muscle was contracted with His (10(-3) g/ml) and relaxed with 5-HT (10(-4) g/ml) and GABA (10(-5) g/ml). These results suggest that Ascaris muscle as well as skeletal muscle have nicotinic receptors and that the Ascaris muscle has properties which differ specifically from skeletal muscle.

Acetylcholine↗
PubMed1979

Induction of erythroid differentiation of murine erythroleukemia cells by nicotinamide and related compounds.

Nicotinamide and its analogues were evaluated for their activity as inducers of differentiation of murine erythroleukemia cells in culture. N'-Methylnicotinamide was the most effective of the compounds tested; at its optimal concentration it was more effective than dimethyl sulfoxide. With 8-10 mM N'-methylnicotinamide, almost all the cells contained hemoglobin (benzidine-reactive) after a 60-hr culture. Commitment to differentiate, assayed by transfer of the cells to semisolid medium without inducers, occurred much earlier and was more extensive with N'-methylnicotinamide than that with dimethyl sulfoxide or nicotinamide. Increase in globin mRNA was greater in the cells cultured with N'-methylnicotinamide than in cells cultured with dimethyl sulfoxide or nicotinamide. The relationship between the inducing activities of nicotinamide analogues and their effect on poly(ADP-ribose) polymerase in vitro was studied. All the compounds studied that had strong inhibitory effects on poly(ADP-ribose) polymerase in vitro induced differentiation of erythroleukemia cells in culture. This property is not a prerequisite of inducers; N'-methylnicotinamide did not inhibit the enzyme in vitro.

Animals↗
PubMed1979

[Clinical investigation on a new penicillin derivative, bacampicillin (author's transl)].

A clinical investigation was carried out on a new penicillin derivative, bacampicillin with the following results. (1) Clinical effect--Bacampicillin was administered orally to 18 patients with acute simple cystitis, acute simple pyelonephritis, chronic prostatitis and acute gonorrhoic urethritis. Daily doses ranged from 750 mg to 1,000 mg. The administration continued for 4 to 14 days. Clinical effect was excellent in 10 patients and good in 5 patients. (2) Side effect--Side effects were noticed in 4 patients, one was allergic eruption and other 3 were gastralgia. In a patient the drug was discontinued to administer.

Adult↗
PubMed1979

Alteration in binding of dexamethasone to glucocorticoid receptors in regenerating rat liver after partial hepatectomy.

Changes in binding of dexamethasone (9 alpha-fluoro-11 beta, 17 alpha, 21-trihydroxy-16 alpha-methylpregna-1,4-diene-3,20-dione) to its receptors in regenerating rat liver after 70% hepatectomy were examined. Specific receptors for dexamethasone in the liver remnants of adrenalectomized rats decreased significantly during the period of DNA synthesis after 70% hepatectomy; then, they increased to above the control values between Days 4 and 7 after partial hepatectomy and subsequently returned to the control values. During the period of DNA synthesis, decreased binding was observed in partially hepatectomized rats with or without adrenals, but later enhanced binding was not prominent in rats with adrenals.

Adrenal Glands↗
PubMed1978

Erythroid cell differentiation.

Normal and transformed erythroid cell precursors provide the opportunity for study of a number of problems relevant to the regulation of proliferation and differentiation in a developmental system. Evidence is presented which suggests that the hormone, erythropoietin, has a primary role in regulating precursor cell proliferation. A wide variety of chemicals can modify the rate at which proliferating transformed precursors initiate expression of the genetic program characteristic of terminal erythroid differentiation. Several sites of inducer action, including the plasma membrane and chromatin, are suggested as part of the pathway which leads to the complex pattern of gene transcription responsible for differentiation.

Acetamides↗