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Biomedical subjects

S Miyata

Publications and source records attributed to S Miyata.

At least 235 records · Page 13Linked to original sources
PubMed1984

Neurotransmitters in dementia.

Changes in the activity of neurotransmitters in dementia were studied by measuring the activities of each of choline acetyltransferase (CAT), dopamine-beta-hydroxylase (DBH) and hydroxylase cofactor (tetrahydrobiopterine; BPH4), and the concentrations of homovanillic acid (HVA) and vasopressin. CAT activity was low in the cerebral cortex of patients with senile dementia of Alzheimer's type (SDAT). The CAT activity was high in the nucleus basalis, which correlated well with the CAT activity in the cerebral cortex, Brodmann areas 22 and 17. DBH activity was lower in the cerebrospinal fluid (CSF) of SDAT and multi-infarct dementia (MID) patients than in that of control subjects. No age-related change was observed in control subjects. Serum DBH activity was decreased in patients with SDAT but not in patients with MID. DBH activity was especially low in the serum of SDAT patients with a low dementia rating score and/or severe brain atrophy shown on computed tomography (CT) scan. Serum DBH activity was also decreased in older normal subjects (greater than or equal to 80 years). The concentration of HVA in the CSF of control subjects decreased with the advance of age, but the decrease in HVA concentration was more pronounced in the CSF of SDAT patients, which would reflect the lowered dopaminergic activity in SDAT. BPH4 activity was also decreased in the CSF of SDAT patients. Arginine-vasopressin was widely demonstrated in the cerebral cortex of control subjects but could not be detected in many areas of the cerebral cortices of demented patients. These results suggest that a deficit of dopamine, noradrenaline or vasopressin as well as acetylcholine may occur in the brain of SDAT patients. The evidence presented points toward areas for consideration in the search for methods of therapy or prevention of SDAT.

Adult↗
PubMed1984

[Effect of CAF'-endocrine therapy on advanced and recurrent breast cancer].

Two cases of primary advanced breast cancer and 4 cases of recurrent breast cancer were treated with cyclophosphamide, Adriamycin and FT-207 combined with hormone therapy. Adriamycin (20 mg) was injected twice a week, and an intravenous drip infusion of cyclophosphamide 150 mg), and FT-207 (400 mg) was administered daily for 3 weeks. Oophorectomy was performed in 4 cases and combination administration of tamoxifen and calcitonin was continued. CR was achieved in one of the primary cases, PR was obtained in 4 cases but one patient with pulmonary metastasis died without showing any clinical response. All cases with bone metastasis responded well. Leucopenia, alopecia, nausea and masculinization were easily controlled. No cardiac toxicity was observed.

Adult↗
PubMed1983

Increased manganese level in spinal cords of amyotrophic lateral sclerosis determined by radiochemical neutron activation analysis.

The manganese distribution in the cross-section of the cervical, thoracic and lumbar portion of the spinal cords from 7 autopsied cases with amyotrophic lateral sclerosis (ALS) and 6 control subjects were determined by radiochemical neutron activation analysis. It was possible to determine 1 ng levels of manganese content accurately in the small tissues about 1 mg of dried weight using wet ashing and chemical separation after neutron activation. The dried weight of spinal cord was about 1/3 of the wet weight. Manganese concentration in the wet tissue was calculated from the ratio of dried to wet weight. In the anterior horn of the cervical cords of ALS, manganese concentration was the highest; 1.75 +/- 0.39 ng/mg of dried weight and 0.59 +/- 0.09 ng/mg of wet weight, respectively. These were significantly higher (P less than 0.01) compared to those in controls; 1.02 +/- 0.12 ng/mg of dried weight and 0.35 +/- 0.04 ng/mg of wet weight, respectively. The elevation of manganese level in the spinal cords of ALS was more prominent in the anterior horn and lateral column than in the posterior column both in dried and wet tissues. Since manganese inhibits neuronal transmission, it is likely that neurological degenerative changes occur as a result of local disturbances of manganese metabolism in the spinal cord of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1983

Biosynthesis of rice seed alpha-amylase: proteolytic processing and glycosylation of precursor polypeptides by microsomes.

Microsomes prepared from the rice seed scutellum were incubated in wheat germ extracts (S-100 fraction) to direct the synthesis of alpha-amylase, a secretory protein subject to proteolytic processing (cleavage of the N-terminal signal sequence) as well as glycosylation during its biosynthesis. The characterization and identification of the immunoprecipitable products synthesized were performed by SDS gel electrophoresis and subsequent fluorography. The molecular weight of the alpha-amylase synthesized by the microsomes was found to be identical with that of the mature secretory form of the enzyme on the basis of electrophoretic mobilities. A significant portion of the enzyme molecules synthesized was shown to be segregated into the microsomal vesicles and protected against digestion by endo-beta-N-acetylglucosaminidase, indicating that both proteolytic processing and glycosylation of the precursor polypeptide chains take place in the microsomes. The modification of the polypeptide chains was further examined by disrupting the microsomal membranes with Triton X-100. Detergent treatment of the microsomes prior to protein synthesis caused an inhibition of both proteolytic processing and glycosylation of the polypeptide chains, leading to the synthesis of the unprocessed nascent (precursor I), processed but nonglycosylated nascent (precursor II) forms, in addition to the mature form of alpha-amylase. Furthermore, the results of time-sequence analysis of the inhibitory effect of Triton X-100 on the modification of the polypeptide chains have led us to conclude that both proteolytic processing and subsequent glycosylation occur in the microsomes during the biosynthesis of alpha-amylase.

Acetylglucosaminidase↗
PubMed1983

Enzymic mechanism of starch breakdown in germinating rice seeds : 15. Immunochemical study on multiple forms of amylase.

The formation of multiple forms of amylases in germinating rice (Oryza sativa L. cv Kimmaze) grains was examined by means of isoelectric focusing, cross-immunoelectrophoresis, and rocket-line immunoelectrophoresis followed by a reaction of enzymic characterization by using beta-limit dextrin or starch as substrate. The constituents detected by isoelectric focusing were identified as three electrophoretically heterogeneous antigens. The major alpha-amylase bands A and B corresponded to a same antigen, the main portion of which was produced within 2 days' germination. The bulk of alpha-amylase D appeared between 2 and 4 days' germination. Component E, a debranching enzyme according to its action on the beta-limit dextrin, already exists in the ungerminated seeds; its amount decreases within the first 2 days of germination and increases again thereafter.Evidence showing that beta-amylase (band C) is produced by the scutellum at an early stage of germination was provided. The enzyme appeared in a suspension of the scutellum after a prolonged incubation.

Journal Article↗
PubMed1982

Selective inhibition of DNA synthesis by a protein released from spleen cells.

Spleen cells cultured release proteins into the culture medium, some of which shows both binding activity to single stranded DNA (ss-DNA) and inhibitory activity to 3H-thymidine incorporation into cells. The inhibitory protein of DNA synthesis was purified to near homogeneity by ammonium sulfate precipitation, ss-DNA-cellulose affinity chromatography, and gel filtration chromatography. The molecular weight of the major band of this protein, as estimated by sodium dodecyl-sulfate gel electrophoresis, was approximately 14,000. The effect of the protein was compared with various cell lines and primary cell culture, and it was found that the protein strongly inhibited DNA synthesis of HeLa, L, and HEp2 cells, but only inhibited to a minor extent synthesis of Ehrlich cells and primary culture of mouse embryo.

Animals↗
PubMed1982

Metal contents in duodenal aspirates of normal subjects during pancreozymin-secretin test.

The calcium, magnesium, zinc, copper and manganese concentrations in the duodenal aspirates obtained during pancreozymin-secretin tests were measured in 16 normal subjects. Total outputs of calcium, magnesium, zinc, copper and manganese during the 70 minute period (10 minutes after pancreozymin injection and 60 minutes after secretin injection) were 4.91 +/- 3.47 mg, 1.88 +/- 0.96 mg, 180 +/- 42 micrograms, 162 +/- 104 micrograms and 16.9 +/- 14.2 micrograms (mean +/- S.D.), respectively. The concentrations of metals were the highest in P fraction (during 10 minutes after pancreozymin injection) and the lowest is S3 fraction (during the 20-40 minute period after secretin injection). Although calcium, magnesium, copper and manganese concentrations varied widely from case to case especially in P fraction, zinc concentration exhibited comparatively small variation in every fraction. Magnesium, copper and manganese concentrations exhibited significant correlations with icterus indices of the aspirates. Zinc and magnesium concentrations correlated with amylase activity and magnesium concentration exhibited an inverse relation to bicarbonate concentration. Most metal concentrations correlated well each other, but there were no correlations between zinc and calcium and between zinc and manganese concentrations. Zinc seemed to be excreted mainly with pancreatic juice and copper and manganese mainly with bile.

Adult↗
PubMed1982

alpha-Amylase biosynthesis: evidence for temporal sequence of NH2-terminal peptide cleavage and protein glycosylation.

During the biosynthesis of secretory proteins, an NH2-terminal peptide, referred to as a signal peptide, is cotranslationally cleaved off after the protein enters the cisternal space of the endoplasmic reticulum. It also has been reported that the core glycosylation reaction of some secretory and viral membrane glycoproteins occurs as a cotranslational event. However, despite a huge amount of work, no decisive answer has been given as to the temporal sequence of proteolytic cleavage of the signal peptide and glycosylation on the polysomes for any secretory or membrane glycoprotein. We show here that proteolytically processed and already glycosylated chains of rice seed alpha-amylase exist on the polysomes; furthermore, our results provide direct evidence that glycosylation is preceded by proteolytic processing during the biosynthesis of the alpha-amylase molecule.

Amylases↗
PubMed1982

alpha-Amylase biosynthesis: signal sequence prevents normal conversion of the unprocessed precursor molecule to the biologically active form.

Recently, we showed that completion of the polypeptide chains on the polysomes isolated from germinating rice seed scutellum in a cell-free translation system can direct the synthesis of (i) unprocessed polypeptide containing the signal sequence (precursor 1), (ii) signal sequence-cleaved but nonglycosylated polypeptide (precursor 2), and (iii) the fully processed and glycosylated form of alpha-amylase molecules. The two precursors as well as the mature form of alpha-amylase can thus be produced in almost the same condition. Here, the binding affinity of the enzyme molecule to the substrate analogue beta-cyclodextrin was used as a probe to compare the conformations of the three distinctly different polypeptide chains produced on the polysomes. It was found that the mature secretory form and the nonglycosylated precursor form (precursor 2) specifically bind to beta-cyclodextrin immobilized on an epoxy-activated Sepharose 6B column but the form that has an attached signal sequence (precursor 1) does not. The results provide evidence that the NH2-terminal signal sequence prevents acquisition of beta-cyclodextrin-binding activity, indicating that, in rice seed alpha-amylase, the signal sequence impairs conversion of the unprocessed polypeptide to the enzymically active configuration.

Amylases↗
PubMed1982

Properties of a DNA-binding protein in a culture medium of thymus cells.

A DNA-binding protein, which migrated as one major protein band, with a molecular weight of 14,000, on sodium dodecylsulfate polyacrylamide gel, was purified from a culture medium of mouse thymus cells. The interaction of the isolated protein with DNA in vitro was assayed by a nitrocellulose filter binding technique. Equilibrium competition experiments demonstrated that the DNA-binding protein had the ability to differentiate among sequences of polynucleotides, indicating that the DNA-binding protein-DNA interaction was at least partially specific. This protein increased the helix melting temperature of DNA and inhibited the incorporation of [3H]dTMP into DNA by the DNA polymerase of calf thymus in vitro.

Animals↗
PubMed1982

Enzymic mechanism of starch breakdown in germinating rice seeds : 12. Biosynthesis of alpha-amylase in relation to protein glycosylation.

The biosynthetic mechanism of alpha-amylase synthesis in germinating rice (Oryza sativa L. cv. Kimmazé) seeds has been studied both in vitro and in vivo. Special attention has been focused on the glycosylation of the enzyme molecule. Tunicamycin was found to inhibit glycosylation of alpha-amylase by 98% without significant inhibition of enzyme secretion. The inhibitory effect exerted by the antibiotic on glycosylation did not significantly alter enzyme activity.In an in vitro system using poly-(A) RNA isolated from rice scutellum and the reticulocyte lysate translation system, a precursor form of alpha-amylase (precursor I) is formed. Inhibition of glycosylation by Tunicamycin allowed detection of a nonglycosylated precursor (II) of alpha-amylase. The molecular weight of the nonglycosylated precursor II produced in the presence of Tunicamycin was 2,900 daltons less than that of the mature form of alpha-amylase (44,000) produced in the absence of Tunicamycin, and 1,800 daltons less than the in vitro synthesized molecule.The inhibition of glycosylation by Tunicamycin as well as in vitro translation helped clarify the heterogeneity of alpha-amylase isozymes. Isoelectrofocusing (pH 4-6) of the products, zymograms, and fluorography were employed on the separated isozyme components. The mature and Tunicamycin-treated nonglycosylated forms of alpha-amylase were found to consist of three isozymes. The in vitro translated precursor forms of alpha-amylase consisted of four multiple components. These results indicate that heterogeneity of alpha-amylase isozymes is not due to glycosylation of the enzyme protein but likely to differences in the primary structure of the protein moiety, which altogether support that rice alpha-amylase isozymes are encoded by multiple genes.

Journal Article↗
PubMed1981

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds: 10. IN VIVO AND IN VITRO SYNTHESIS OF alpha-AMYLASE IN RICE SEED SCUTELLUM.

Scutellar tissues were dissected from germinating rice seeds and the incorporation of [(35)S]methionine into the alpha-amylase molecule was examined by in vivo and in vitro assay systems. Immunoprecipitation with monospecific anti-alpha-amylase immunoglobulin G raised against the purified enzyme preparation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography were used to identify alpha-amylase and its possible precursor molecule. Using freshly prepared scutellar tissues, it was demonstrated that alpha-amylase is synthesized de novo in the scutellar epithelium and secreted into endosperm. The synthesis of alpha-amylase directed by the polyadenylic acid-containing ribonucleic acid isolated from the scutellar tissues was also established using the translation system of either wheat germ extract or reticulocyte lysate. The immunoprecipitable product obtained in the in vitro translation system was smaller in molecular weight than that synthesized in vivo on the basis of mobilities in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results are discussed in relation to the processing of the nascent polypeptide precursor of the enzyme molecule and the introduction of the oligosaccharide chain to the cleaved polypeptide to make up the mature form of alpha-amylase.

Journal Article↗