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Biomedical subjects

T Yamane

Publications and source records attributed to T Yamane.

At least 541 records · Page 30Linked to original sources
PubMed1982

[Effect of PSK on DMH (dimethyl hydrazine) induction of cancer].

The effect of PSK on the induction of intestinal tumors by DMH in Wistar rats was examined. One hundred and fifty-one rats were divided into two groups. Seventy-two rats were treated with DMH alone and 79 rats were treated with DMH and PSK. All animals were subjected to a sequential autopsy and all lesions within the GI tract were examined macroscopically and histologically. Tumor incidence in the DMH and PSK treated group was significantly lower than that in the DMH treated alone, and peritoneal disseminations and distant metastases were also significantly decreased in the PSK treated rats. The number of circulating lymphocytes dropped in the 25th and 35th week in the group treated with DMH alone, but the drop in the PSK treated group was not remarkable. DTH reaction to PPD and antibody forming capacity to SRBC were well maintained in the PSK treated rats than in those treated with DMH alone. The most interesting findings in these experiments were the differences concerning the serum blocking activities and serum immunosuppressive factor in these two groups; these were markedly reduced in PSK-treated rats. From these experiments, the mechanisms may be explained by the competitive action of PSK against the immunosuppressive factor produced by a tumor-bearing host.

Adjuvants, Immunologic↗
PubMed1981

Discrimination between D- and L-tyrosyl transfer ribonucleic acids in peptide chain elongation.

D-Tyr-tRNA can take part in peptide bond formation with N-AcPhe-tRNA on ribosomes programmed with the hexanucleotide UUUUAC. None of the steps leading to peptide bond formation exhibit high stereoselectivity. Ternary complex formation with EF-Tu.GTP favors L-Tyr-tRNA by a factor greater than 25. The complex formed with D-Tyr-tRNA was not protected from hydrolysis, which suggests that the D-amino acid is improperly bound to the protein. The rate of EF-Tu-promoted dipeptide formation was 30-fold faster with L-Tyr-tRNA. The ratio of moles of GTP hydrolyzed to dipeptide formed was 1.4 for L-Tyr-tRNA and 4 for D-Tyr-tRNA. The excess of GTP hydrolyzed to peptide bonds formed is evidence for kinetic proofreading in AA-tRNA selection. The combined effects of the partial discrimination at each stage, from the aminoacylation to the peptide formation, favor L-tyrosine by a factor greater than 10(4) and would virtually exclude D-tyrosine from being incorporated under conditions where L-tyrosine was also present.

Escherichia coli↗
PubMed1981

Effect of transfer ribonucleic acid dimer formation on polyphenylalanine biosynthesis.

Escherichia coli tRNAPhe (anticodon GAA) as well as yeast tRNAPhe (anticodon GmAA) forms a strong complex with E. coli tRNAGlu (anticodon s2UUC) through an interaction between their complementary anticodons. This interaction inhibits aminocylation of tRNAPhe but not the formation of a complex with elongation factor Tu. Moreover, at 0 degrees C, tRNAGlu strongly inhibits the binding of Phe-tRNA to poly(U)-programmed ribosomes via either the enzymic (EF-Tu-promoted) or nonenzymic pathway. At 15 degrees C, tRNAGlu effectively inhibits polyphenylanine synthesis in the E. coli system. The inhibition is reversed at 37 degrees C, where the Phe-tRNA.tRNAGlu dimer is dissociated. Calculations based upon the E. coli intracellular concentrations of tRNAs and the published rates of association and dissociation of the tRNA dimers suggest that this interaction may inhibit protein synthesis in vivo at temperatures below 15 degrees C.

Anticodon↗
PubMed1981

Interaction of elongation factor Tu with the aminoacyl transfer ribonucleic acid dimer Phe-tRNA-Glu-tRNA.

The effect of EF-Tu.GTP on the codon-anticodon interaction of AA-tRNA was studied by using as a model system the interaction of AA-tRNAs with complementary anticodons, namely, dimerization between yeast or Escherichia coli Phe-tRNAPhe (anticodon GmAA) and E. coli Glu-tRNAGlu (anticodon s2UUC) or nonacylated tRNAGlu in the presence or absence of EF-Tu.GTP. The present data indicate that the ternary complexes Phe-tRNA-EF-Tu.GTP and Glu-tRNA-EF-Tu.GTP can form dimers with a binding constant of (0.9 +/- 0.2) X 10(6) M-1, which is identical in magnitude with that of the dimer of the nonacylated tRNAs tRNAPhe-tRNAGlu and also with that of the complex Phe-tRNA-EF-Tu.GTP with nonacylated tRNAGlu. These results show that the anticodon region is not affected by complexation with EF-Tu.GTP; however, this conclusion does not preclude the possibility of structural changes in the anticodon loop that have no effect in energetic terms. In addition, this model codon-anticodon interaction does not stimulate hydrolysis of the GTP bound in the ternary complex.

Anticodon↗
PubMed1981

Monocyte count, monocyte chemotaxis and chemotactic factor inactivator in gastric cancer patients.

The monocyte count in the peripheral blood, chemotactic responsiveness (MCR) and chemotactic factor inactivator (CFI) were measured in 66 patients with gastric cancer. Monocyte counts in advanced gastric cancer patients were significantly increased. MCR was significantly depressed in gastric cancer patients in the advanced stage of the disease, as compared with findings in the control groups. Sixty-seven percent of the patients with stage IV carcinoma had abnormally depressed responses. The CFIs were significantly higher in gastric cancer patients than in the control groups, and there was a positive correlation between the degree of inhibition and extent of cancer progress. These data support the hypothesis that qualitative and quantitative abnormalities of circulating monocytes, as macrophage precursors, may hinder immunological host defense mechanisms.

Adult↗
PubMed1981

Beta-pleated sheets in oligopeptide crystals.

Many oligopeptide crystals show the beta-pleated sheet structures. Both parallel and antiparallel chain pleated sheets are found, and also both ideal (flat) and heavily twisted sheets are found. The structural parameters, such as the T (NC alpha C') angles, the torsion angles (phi and psi), the fiber axis periods, the hydrogen bond lengths, and the interchain spacings, are studied. Some of them deviate significantly from those proposed by Pauling & Corey ()Proc. Natl. Acad. Sci. US (1953), 39, 253-256). In the heavily twisted sheets, the twists are large than those in the globular proteins, and each two neighboring chains are almost perpendicular with each other, preserving the beta-sheet type hydrogen bond system. The torsion angles in the twisted sheets are rather close to those of the poly (L-proline) II helix. It also is discussed that the T (NA alpha C') angles sometimes deviate by almost 5 degrees from the standard value depending on the structures of the main and side chains.

Crystallization↗
PubMed1981

Studies on cell-mediated immunity in patients with colorectal cancer: leucocyte migration inhibition test using allogenic 3M KCl extract.

Leucocytes from patients with colorectal and other malignant and non-malignant gastrointestinal diseases as well as those from normal subjects were tested by the leucocyte migration inhibition test (LMT), employing the method of Clausen, using five different allogenic 3M KCl soluble extracts of colorectal cancer tissue. The normal range of migration index (Ml) was found to be greater than 0.82 and less than 1.20 by calculating the mean Ml +/- 2SD of ten normal subjects with cancer extracts. Mls out of this range were considered to be pathological. In LMIT with a single tumour extract, a pathological Ml was found in 46% of 50 colorectal cancer patients, a significantly higher figure than found in the three other groups of patients (4% to 16%). In the panel mode of LMIT, that is, testing each blood sample with five different tumour extracts, 40/50 (80%) of patients with colorectal cancer were reactive, while 2/15 (13%) of gastric cancer patients showed a "positive" reaction; no positive reactivity was observed in the other two groups of patients. Thus "positive" reactivity was significantly commoner in patients with colorectal cancer than in patients belonging to the other groups. The frequency of "positive" reactivity was higher in patients with Dukes C carcinoma than in those with Dukes A or B carcinomas, though differences were not significant. In the follow-up study, marked depression of reactivity was seen 10 to 14 days after curative resection. In patients without recurrence, leucocyte migration was found to be in the normal range during the two four weeks after surgery. "Positive" reactivity reappeared in patients with local recurrence. Thus the LMIT, particularly when tested by a panel mode, by demonstrating cell-mediated immunity against tumour-associated antigens of colorectal cancer, provides a method of monitoring colorectal cancer activity.

Adult↗
PubMed1981

A simple and rapid method in the determination of urinary estrogen to creatinine ratio during pregnancy.

The fluorometry reported in this paper is a method which fulfils the necessary precision, accuracy, sensitivity and specificity for the determination of the urinary estrogen to creatinine ratio of pregnant women. With this method: (1) whole procedures are completed by single capillary specimen; (2) consequently a very small amount of urine is required; (3) only 35 min are spent completing the in vitro measurement, and (4) urinary estrogen of 5 weeks' gestation can be estimated due to its high sensitivity and specificity. Normal cases and abnormal pregnancies are discussed utilizing this method.

Circadian Rhythm↗
PubMed1981

[Urinary total estrogens in normal menstrual cycle and early pregnancy (author's transl)].

A ratio of urinary total estrogens to creatinine (E/C, micrograms/g) was measured in every morning through the cycle in normal menstruating cycling women and during her early pregnancy. The level of follicular phase was 17.7 +/- 5.4 micrograms/g, ovulatory phase 78.8 +/- 8.8 micrograms/g and luteal phase 26.7 +/- 11.2 micrograms/g. In the spontaneous pregnancies E/C levels elevated sharply after 15 weeks of gestation. In the pregnancy after induced ovulation with clomifene citrate and conjugated estrogens, E/C levels were decreased from 7 days prior to the initiation of genital bleeding of spontaneous abortion. The need for multiple determinations over considerable periods of time is solved by our methods of easily repeated sequential measurements of urinary total estrogens estimated by E/C ratio.

Adult↗
PubMed1979

Phosphorus-31 nuclear magnetic resonance studies of wild-type and glycolytic pathway mutants of Saccharomyces cerevisiae.

High-resolution phosphorus-31 nuclear magnetic resonance (31P NMR) spectra of wild-type and mutant strains of Saccharomyces cerevisiae were observed at a frequency of 145.7 MHz. Levels of various phosphorus metabolites were investigated upon addition of glucose under both aerobic and anaerobic conditions. Three mutant strains were isolated and their biochemical defects characterized: pfk lacked phosphofructokinase activity; pgi lacked phosphoglucose isomerase activity; and cif had no glucose catabolite repression of the fructose bisphosphatase activity. Each mutant strain was found to accumulate characteristic sugar phosphates when glucose was added to the cell suspension. In the case of the phosphofructokinase deficient mutant, the appearance of a pentose shunt metabolite was observed. 31P NMR peak assignments were made by a pH titration of the acid extract of the cells. Separate signals for terminal, penultimate, and central phosphorus atoms in intracellular polyphosphates allowed the estimation of their average molecular weight. Signals for glycero(3)phosphochline, glycero(3)phosphoserine, and glycero(3) phosphoethanolamine as well as three types of nucleotide diphosphate sugars could be observed. The intracellular pH in resting and anaerobic cells was in the range 6.5--6.8 and the level of adenosine 5'-triphosphate (ATP) low. Upon introduction of oxygen, the ATP level increased considerably and the intracellular pH reached a value of pH 7.2--7.3, irrespective of the external medium pH, indicating active proton transport in these cells. A new peak representing the inorganic phosphate of one of the cellular organelles, whose pH differed from the cytoplasmic pH, could be detected under appropriate conditions.

Adenosine Triphosphate↗