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Biomedical subjects

H Homma

Publications and source records attributed to H Homma.

At least 145 records · Page 8Linked to original sources
PubMed1985

Temperature dependent redistribution among the multiple forms of rat Yb-glutathione-S-transferase.

Anionic (Yb) rat liver glutathione-S-transferases are susceptible to temperature or pH dependent transitions to more basic forms of this class of proteins. At elevated temperatures (25-30 degrees) or at pH values above 9.0 the protein is rapidly and irreversibly converted to forms that are no longer retained by anion exchange resins and display basic components in chromatofocusing systems, because bound glutathione is removed at the higher temperatures or pH. Sharp increases in enzymatic activity with 1,2-dichloro-4-nitrobenzene as a substrate, accompany the temperature induced changes. Microheterogeneity patterns for this protein are contingent upon these interconversions, and the results explain apparent variations in relative amounts of the multiple forms under different conditions in terms of glutathione binding.

Animals↗
PubMed1985

[Value of Doppler and duplex sonography studies of the extracranial carotid system performed by technical assistants].

The results of Doppler sonographic and Duplex sonographic examinations of the extracranial carotid artery carried out in 100 patients by two sonographers were compared with angiographic findings. The accuracy and quality of the ultrasonic examinations did not differ from those of documented examinations performed by physicians. The percentage of error due to mistakes on the part of sonographer vas 1.3%. We conclude that sonographers are qualified for performing carotid Doppler and duplex sonography, provided that they are well-trained, experienced and supervised.

Angiography↗
PubMed1985

Identification of Yb-glutathione-S-transferase as a major rat liver protein labeled with dexamethasone 21-methanesulfonate.

Dexamethasone 21-methanesulfonate, an affinity label for glucocorticoid-binding proteins, was incubated with rat liver cytosol preparations. The predominant covalently labeled component was identified as Yb-glutathione-S-transferase on the basis of chromatographic properties, electrophoretic mobility, and specific retention by an anti-Yb-immunoadsorbent. Affinity labeling of this protein was blocked by excess dexamethasone. Preferential reactivity of dexamethasone 21-methanesulfonate with the Yb subclass of glutathione-S-transferase (glutathione transferase, EC 2.5.1.18) was also evident with mixtures containing the multiple forms of the enzyme. Yb-glutathione-S-transferase, the nonsaturable glucocorticoid-binding component of rat liver cytosol should, therefore, be reclassified; because of its high concentration and selective interaction with steroids, this enzyme may be an intracellular glucocorticoid-binding protein and, thereby, influence transport, metabolism, and action of the steroids.

Affinity Labels↗
PubMed1985

Gene organization of pldA and pldB, the structural genes for detergent-resistant phospholipase A and lysophospholipase L2 of Escherichia coli.

The genes coding for the phospholipid degradation enzymes in E. coli, detergent-resistant (DR-) phospholipase A (pldA) and lysophospholipase L2 (pldB), were cloned together on the plasmid pKO1 (Homma, H., Kobayashi, T., Ito, Y., Kudo, I., Inoue, K., Ikeda, H., Sekiguchi, M., & Nojima, S. (1983) J. Biochem. 94, 2079-2081). To study their gene organization, a transducing lambda phage, lambda pldApldB, carrying both the pldA and pldB genes was constructed in vitro from plasmid pKO1. Viable deletion mutants of lambda pldApldB were isolated by EDTA killing, and their deleted DNA regions were determined by electron microscopic analysis of appropriate heteroduplexes. The activities of DR-phospholipase A and lysophospholipase L2 were also measured in lysates of cells infected with the deletion phages. The DNA region essential for the expression of each lipolytic activity was determined. In addition, proteins coded by the bacterial DNA on the plasmids containing the pldApldB region to various extents were detected by the maxicell system. The results showed that the product of the pldB gene is a protein with molecular weight of 40,000. It was also shown that the pldB gene is located at a region about 3 kilobase from the pldA gene.

Bacteriophage lambda↗
PubMed1984

Isolation of two kinds of E. coli K-12 mutants for lysophospholipase L2: one with an elevated level of the enzyme and the other defective in it.

Two kinds of E. coli K-12 mutants for lysophospholipase L2 (located in the inner membrane) were isolated, using an improved version of the colony autoradiographic method developed by Raetz; these were, 1) strains carrying an elevated level of the enzyme and 2) strains defective or temperature-sensitive in the enzyme. Characterization of the crude lysates of these mutants revealed that the differences of lysophospholipase L2 activity are not due to the presence or absence of regulatory factors. Evidence was obtained, by using these mutants, that this lysophospholipase L2 transfers the acyl group of 2-acyl lysophospholipid to phosphatidylglycerol, forming acyl phosphatidylglycerol.

Autoradiography↗
PubMed1984

Characteristics of detergent-resistant phospholipase A overproduced in E. coli cells bearing its cloned structural gene.

Detergent-resistant phospholipase A (DR-phospholipase A) of E. coli is a 28K-dalton protein and is exclusively located in the outer membrane. We cloned the pldA gene of E. coli, which is responsible for the activity of DR-phospholipase A. Strains bearing the plasmid which contained the pldA gene yielded a large amount of the outer membrane protein with a molecular weight of about 28K daltons and overproduced 20 to 65 times as much DR-phospholipase A activity as the wild type strain. Experiments with minicells and maxicells revealed that the pldA-containing plasmid was coding for a 28K protein. These results strongly indicated that pldA is the structural gene for DR-phospholipase A. There was apparently no difference with respect to the association of the enzyme with the envelope fraction between the overproducer and the wild type strain. The overproduced enzyme was properly transported to the outer membrane. Neither the growth rate nor the phospholipid composition of the overproducer was remarkably different from in the wild type strain. Thus, the overproduction of DR-phospholipase A apparently caused no phenotypic variations. E. coli has very excessive ability to transport and integrate the outer membrane protein.

Bacterial Proteins↗
PubMed1984

The DNA sequence encoding pldA gene, the structural gene for detergent-resistant phospholipase A of E. coli.

The nucleotide sequence of the pldA gene of Escherichia coli K-12, which codes for detergent-resistant phospholipase A (DR-phospholipase A), located in the outer membrane, was determined and the amino acid sequence of DR-phospholipase A was deduced. DR-phospholipase A contains 269 amino acids, resulting in a protein with a molecular weight of 30,809. It does not contain any cysteine residues and seems to be synthesized first as a precursor with a typical signal peptide composed of 20 amino acids. The NH2-terminus of the mature protein is glutamine, a polar amino acid, while other outer membrane proteins so far determined have a nonpolar amino acid there. The hydropathy profile of the deduced amino acid sequence of DR-phospholipase A was studied. Most of the region was rather hydrophilic and there were no stretches of hydrophobic amino acids. Computer analysis showed that there are no homologies between DR-phospholipase A and other extracellular phospholipases whose amino acid sequences are known. The candidates for the promoter region of the pldA gene, the 5'-flanking region, have a significantly high AT content, while the AT content of the coding region is about the same as the average AT content of the E. coli chromosome. A typical rho-independent transcription termination site is also present at the 3'-flanking region. This is the first example of the primary structure of a membrane-bound phospholipase.

Amino Acid Sequence↗
PubMed1984

Lymphatic system or hydro-oncotic forces. Which is more significant in drainage of pleural fluid?

Artificial pleural fluids, containing plasma protein from 0.1 to 9.0 g per 100 ml, indocyanine green (ICG) and para-aminohippurate (PAH), were injected into the pleural cavity of dogs. The concentration of these two indicators were measured at a regular time interval, and the lymphatic and non-lymphatic flows and PAH clearance were calculated by Stewart's and Takashina's equations. When the protein concentration in the pleural fluid was less than 4 g per 100 ml, the pleural fluid volume decreased at a rate of 0.20 ml/kg/hour. The decrease was due to pleural fluid drainage by the lymphatic flow, because the inward and outward non-lymphatic flows due to hydro-oncotic forces balanced each other and the net non-lymphatic flow was essentially zero. When the protein concentration was 6 g per 100 ml or more, the decrease of pleural fluid was remarkably attenuated, because of an increase of the inward non-lymphatic flow due to an increase of protein concentration in the pleural fluid. Even in these situations, the lymphatic flow was kept at the rate of 0.20 ml/kg/hour, similarly with the former conditions. From these results, it may be concluded that the lymphatic system is a principal factor, and that factors governed by hydro-oncotic elements have additive effect to that of the lymphatic system in the regulation of pleural fluid dynamics.

Animals↗
PubMed1983

Identification and cloning of the gene coding for lysophospholipase L2 of E. coli K-12.

E. coli bearing hybrid plasmid pKOl (Oeda et al. (1981) Mol. Gen. Genet. 184, 191-199) expressed a large amount of lysophospholipase L2 activity. When a mutant which was defective in lysophospholipase L2 activity was transformed with plasmid pKOl, it overproduced lysophospholipase L2 activity. The gene responsible for the lysophospholipase L2 activity was designated as pld B. On the same hybrid plasmid another gene (pld A) coding for detergent-resistant phospholipase A (DR-phospholipase A) was also identified. These facts together with the results of a Pl transduction experiment revealed that the pld B gene must be between the pld A and met E genes on the E. coli chromosome.

Cloning, Molecular↗