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Biomedical subjects

M Mishina

Publications and source records attributed to M Mishina.

At least 199 records · Page 11Linked to original sources
PubMed1982

DNA sequences required for transcription in vivo of the human corticotropin-beta-lipotropin precursor gene.

The cloned human corticotropin-beta-lipotropin precursor gene, when joined with an SV40 vector and introduced into COS monkey cells, is transcribed from its own promoter. The DNA sequences required for promoter function have been identified by using 5' deletion mutants of the fusion gene AT which contains the 5'-flanking sequence and capping site of the human corticotropin-beta-lipotropin precursor gene and the structural sequence of the herpes simplex virus thymidine kinase gene. The deletion of the sequence located between 53 and 59 bp upstream of the capping site enhances the transcription approximately 3-fold, while the deletion of the TATA box region abolishes the transcription.

Adrenocorticotropic Hormone↗
PubMed1982

Left ventricular-right atrial communication with an aneurysm of the atrioventricular membranous septum. A case report.

A 40-year-old man with combination of left ventricular-right atrial communication and aneurysm of the atrioventricular membranous septum is presented. A supravalvular type defect, 14 X 15 mm in size, was closed with a Teflon patch. An oval shaped aneurysm of the atrioventricular membranous septum, 20 X 17 mm in size was also noted, but was left untouched. To our knowledge, this is the first reported case with this combination in Japan.

Adult↗
PubMed1980

Yeast mutants defective in acetyl-coenzyme A carboxylase and biotin: apocarboxylase ligase.

Among more than 7000 mutants of Saccharomyces cerevisiae, requiring saturated fatty acids, 61 acetyl-CoA-carboxylase-deficient strains have been identified. According to their mutual complementation characteristics these mutants have been assigned to two different genes, acc1 and acc2. Both acetyl-CoA carboxylase genes are unlinked to each other and to the fatty acids synthetase genes fas1 and fas2. The acetyl-CoA carboxylases of several acc1 and acc2 mutants have been purified and assayed for their overall and component enzyme activities. Besides overall acetyl-CoA carboxylation, which was lost in all cases, both component enzymes, biotin carboxylase and transcarboxylase, were simultaneously affected in most mutants, though often to a different relative extent. Similarly, the comparison of biochemical and genetic complementation data revealed no basis for a clear distinction between specific biotin carboxylase and transcarboxylase mutants. These results suggest that acc1 is a cluster gene coding for a multifunctional protein harboring both acetyl-CoA carboxylase component enzyme activities on the same polypeptide chain. The acetyl-CoA carboxylase isolated from acc2 mutants was free of biotin. Correspondingly, biotin:apoacetyl-CoA-carboxylase ligase activity was missing in acc2 mutants. Therefore, it is concluced that the primary defect in acc2 mutants is in the biotin:apocarboxylase ligase. In agreement with this conclusion, the acc2 acetyl-CoA carboxylase can be activated, in the presence of biotin and ATP, by ligase preparations from wild-type or acc1 mutant cells. By the use of these mutants, evidence was obtained that in vivo the biotinylation of both acetyl-CoA carboxylase and pyruvate carboxylase is catalyzed by the same ligase.

Acetyl-CoA Carboxylase↗
PubMed1979

Acyl-coenzyme-A synthetase I from Candida lipolytica. Purification, properties and immunochemical studies.

Acyl-coenzyme-A synthetase I from Candida lipolytica has been purified to homogeneity as evidenced by polyacrylamide gel electrophoresis in the presence and absence of dodecylsulfate as well as by Ouchterlony double-diffusion analysis. The purification procedure involves resolution of cellular particles with Triton X-100 and chromatography on phosphocellulose, Blue-Sepharose and Sephadex G-100. The purified enzyme exhibits a specific activity of 20--24 U/mg protein at 25 degree C, which is about 100-fold higher than those of long-chain acyl-CoA synthetases hitherto reported. The molecular weight of the enzyme has been estimated by polyacrylamide gel electrophoresis in the presence of dodecylsulfate to be approximately 84 000. The enzyme is specific for fatty acids with 14--18 carbon atoms regardless of the degree of unsaturation. Studies with the use of specific antibody to acyl-CoA synthetase I have indicated that this enzyme is immunochemically distinguishable from acyl-CoA synthetase II.

Candida↗
PubMed1979

Involvement of long-chain acyl coenzyme A for lipid synthesis in repression of acetyl-coenzyme A carboxylase in Candida lipolytica.

Mutant strains of Candida lipolytica defective in acyl-CoA synthetase II [acid:CoA ligase (AMP-forming), EC 6.2.1.3] have been isolated. The mutants fail to grow on fatty acid as a sole carbon source but are capable of incorporating exogenous fatty acid into cellular lipids. This observation, together with our previous finding that mutant strains defective in acyl-CoA synthetase I cannot incorporate exogenous fatty acid into cellular lipids but are able to degrade fatty acid via beta-oxidation, indicates the presence of two functionally distinct long-chain acyl-CoA pools in the cell--i.e., one for lipid synthesis and the other for beta-oxidation. Unlike the wild-type and the revertant strains as well as the mutants lacking acyl-CoA synthetase II, the mutants defective in acyl-CoA synthetase I do not exhibit the repression of acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] by exogenous fatty acid. Measurement of the two long-chain acyl-CoA pools with the aid of appropriate mutant strains has indicated that the long-chain acyl-CoA to be utilized for lipid synthesis, but not that to be degraded via beta-oxidation, is involved in the repression of acetyl-CoA carboxylase.

Acetyl-CoA Carboxylase↗
PubMed1978

Subcellular localization of two long-chain acyl-coenzyme-A synthetases in Candida lipolytica.

Studies have been made on the subcellular localization of two long-chain acyl-coenzyme-A synthetases as well as glycerolphosphate acyltransferase and the acyl-CoA-oxidizing system in Candida lipolytica grown on oleic acid. Acyl-CoA synthetase I is distributed among different subcellular fractions, including microsomes and mitochondria where glycerolphosphate acyltransferase is located. On the other hand, acyl-CoA synthetase II is localized in microbodies where the acyl-CoA-oxidizing system is located. These results support our previous conclusion that acyl-CoA synthetase I is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids, while acyl-CoA synthetase II provides acyl-CoA that is exclusively degraded via beta-oxidation.

Candida↗
PubMed1977

Candida lipolytica mutants defective in an acyl-coenzyme A synthetase: isolation and fatty acid metabolism.

Mutant strains of Candida lipolytica defective in an acyl-CoA synthetase [acid:CoA ligase (AMP-forming); EC 6.2.1.3]were isolated. The mutant strains apparently exhibited no acyl-CoA synthetase activity in vitro and were, in contrast to the wild-type strain, incapable of growing in the presence of exogenous fatty acid when cellular synthesis de novo of fatty acid was blocked. However, the mutant strains grew on either fatty acid or n-alkane as a sole carbon source at rates comparable to that observed for the wild-type strain. Analysis of the fatty acid composition of the lipids from the mutant cells grown on odd-chain-length fatty acid as well as [14C]oleic acid incorporation studies have shown that the mutant cells, unlike the wild-type cells, cannot incorporate exogenous fatty acid as a whole into cellular lipids, but utilize the fatty acid that is synthesized de novo from acetyl-CoA produced by degradation of exogenous fatty acid. This finding indicates the presence of at least two acyl-CoA synthetases that activate long-chain fatty acid. One, designated acyl-CoA synthetase I, which is absent in the mutant strains, is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids. The other acyl-CoA synthetase provides actyl-CoA that is exclusively degraded via beta-oxidation to yield acetyl-CoA.

Candida↗
PubMed1977

Evaluation of surgical treatments for the major lesion of bilateral silicotuberculosis.

The present communication deals with the follow-up study of 24 patients with bilateral silicotuberculosis in whom only unilateral operation was carried out for major lesions. The operative procedure consisted of pulmonary resection, thoracoplasty or combined operation such as cavernostomy, intracavitary filling of a pedunculated muscle flap and thoracoplasty. The follow-up period ranged 1 year to 12 years and 5 months. The results of surgical treatment for unilateral major lesions and their effect on the contralateral minor lesions were clinically assessed by alterations in the chest x-ray findings and tubercle bacilli in sputum. In 16 of 24 patients (67%) alleviation was obtained, whereas no change occurred in 3 (13%) and aggravation in 5 (21%). The surgical treatment for unilateral major lesion brought about 41% of improvement in the contralateral minor lesions. Contralateral minor lesions remained unchanged in 46% of patients and aggravated in 14%. This shows a value of the surgical threatment for bilateral silicotuberculosis. It should be emphasized that surgical treatments more aggressive than have been heretofore practiced can be employed.

Adult↗
PubMed1976

Acetyl-coenzyme-A carboxylase of Candida Lipolytica. 1. Purification and properties of the enzyme.

Acetyl-coenzyme-A carboxylase has been isolated in homogeneous form from Candida lipolytica. The homogeneity of the enzyme preparation is evidenced by analytical ultracentrifugation, dodecyl-sulfate-polyacrylamide gel electrophoresis and Ouchterlony double-diffusion analysis. The purified enzyme exhibits a specific activity of 8.0 U/mg protein at 25 degrees C and contains 1 mol biotin/263000 g protein. The sedimentation coefficient (S20,W) of the enzyme is 18 S. It has been shown by dodecyl-sulfate-polyacrylamide gel electrophoresis that the enzyme possesses only one kind of subunit with a molecular weight of 230000. This finding, together with the biotin content, indicates that the C. lipolytica enzyme has a highly integrated subunit structure. The C. lipolytica enzyme is very labile, but is stabilized by glycerol. The enzyme is markedly activated by poly(ethyleneglycol), the activation being due principally to a decrease in the Km values for substrates. Even in the presence of this activator, the Km value for acetyl-CoA of the C. lipolytica enzyme is much higher than that of the enzyme from Saccharomyces cerevisiae and animal tissues. The C. lipolytica enzyme, unlike the enzyme from animal tissues, is not activated by citrate.

Acetyl-CoA Carboxylase↗
PubMed1976

Acetyl-coenzyme-A carboxylase of Candida lipolytica. 2. Regulation of cellular content and synthesis of the enzyme.

The level of acetyl-coenzyme-A carboxylase activity in Candida lipolytica undergoes large variations depending upon the carbon source on which the yeast is grown. Cells grown on n-alkanes or fatty acids exhibit a lower activity level than do cells grown on glucose. Among the n-alkanes and fatty acids tested, n-heptadecane, n-octadecane, oleic acid and linoleic acid reduce the enzyme activity to the lowest levels, which are 16-18% of the activity level in glucose-grown cells. Immunochemical titrations and Ouchterlony double-diffusion analysis with specific antibody as well as kinetic studies have indicated that the observed decrease in the level of acetyl-CoA carboxylase activity is due to a reduction in the cellular content of the enzyme. Furthermore, isotopic leucine incorporation studies with the use of the immunoprecipitation technique have demonstrated that the relative rate of synthesis of the enzyme in oleic-acid-grown cells is diminished to 12% of that in glucose-grown cells. Evidence has also been obtained to support the view that the enzyme in this yeast is not degraded at a rate high enough to contribute to the marked decrease in the cellular content of the enzyme. Thus, it is concluded that the reduction in acetyl-CoA carboxylase content in fatty-acid-grown cells is due to diminished synthesis of the enzyme.

Acetyl-CoA Carboxylase↗
PubMedDate not supplied

Expression of functional acetylcholine receptor from cloned cDNAs.

The cloned cDNAs encoding the four subunits of the Torpedo californica acetylcholine receptor, each carried by a simian virus 40 vector, direct the synthesis of the functional receptor in a combined expression system consisting of COS monkey cells and Xenopus oocytes. Our results suggest that all four subunits are required to elicit a normal nicotinic response to acetylcholine, whereas only the alpha-subunit is indispensable for alpha-bungarotoxin binding activity.

Animals↗
PubMedDate not supplied

Location of functional regions of acetylcholine receptor alpha-subunit by site-directed mutagenesis.

The availability of cloned cDNAs encoding the four subunits of the Torpedo acetylcholine receptor, which can be expressed to make functional receptors in Xenopus oocytes, has made possible a detailed investigation of the functions of the different structural components of the receptor. The functional analysis of receptors with alpha-subunits altered at specific sites by site-directed mutagenesis of the cDNA has allowed the location of specific regions of the alpha-subunit molecule involved in acetylcholine binding and forming a transmembrane ionic channel.

Animals↗