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Biomedical subjects

T Hirota

Publications and source records attributed to T Hirota.

At least 199 records · Page 11Linked to original sources
PubMed1987

A new glucocorticoid receptor detected in host rat liver but not in various hepatomas.

Previously a new glucocorticoid receptor (Peak C), which eluted with 0.12 to 0.14 M NaCl from DEAE-cellulose column, was identified in addition to another receptor (Peak B), a classic type of glucocorticoid receptor, which eluted with 0.05 to 0.08 M NaCl. Peak C appeared after stress or injection of a high dose (20 micrograms/100 g body weight) of dexamethasone into rats. Peak C was also detected in the liver of rats bearing various tumors, but it was not found in malignant tumors (Yoshida sarcoma and Yoshida ascites hepatoma AH 130), a less malignant Yoshida ascites hepatoma (LY-5), or in minimal deviation-type hepatomas (Morris hepatomas 7316A and 7794A). The absence of Peak C in these tumors coincided with the inability of the glucocorticoid to induce tryptophan oxygenase in these tumors and in the liver of rats during early postnatal development. Peak B was consistently observed in various hepatomas and immature rat liver with capability to induce tyrosine aminotransferase. Thus Peak C appeared to be a highly differentiated type of glucocorticoid receptor mediating specific hormone actions and to be present in mature liver cells, but not in immature liver or tumor cells, even of the minimal deviation type.

Animals↗
PubMed1987

Structure-activity relationship of gramicidin S analogues on membrane permeability.

The previous study of the action of gramicidin S on bacteria (Katsu, T., Kobayashi, H. and Fujita, Y. (1986) Biochim. Biophys. Acta 860, 608-619) prompted us to investigate further the structure-activity relationship of the gramicidin S analogues on membrane permeability. Two types of the gramicidin S analogues were used in the present study: (1) cyclo(-X-D-Leu-D-Lys-D-Leu-L-Pro-)2, where X = Gly, D-Leu and D-cyclohexylalanine (D-cHxAla); (2) N,N'-diacetyl derivative of gramicidin S (diacetyl-gramicidin S) which lacks a cationic moiety of gramicidin S. All the analogues have a beta-sheet conformation as gramicidin S. The following cellular systems were used: Staphylococcus aureus as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria, human erythrocytes, rat liver mitochondria and artificial liposomal membranes. It was found that gramicidin S and one of the type 1 analogues having X = D-cHxAla induced the efflux of K+ through the cytoplasmic membrane of all types of the cells. In addition, these two peptides had the ability to lower the phase transition temperature of dipalmitoylphosphatidylcholine. Accordingly, it was concluded that, if peptides can expand greatly the membrane structure of neutral lipids which constitute main parts of the biological membrane, they can stimulate the permeability of cells without any selectivity. The action of the type 2 peptide, diacetyl-gramicidin S, was strongly cell dependent. Although this peptide stimulated the efflux of K+ from mitochondria, it did not do so efficiently, if at all, from S. aureus, E. coli and erythrocytes. In experiments using liposomes, diacetyl-gramicidin S increased markedly the permeability of liposomes composed of egg phosphatidylcholine. The presence of egg phosphatidylethanolamine or cholesterol reduced its activity. These results on liposomes explained well the low sensitivity of diacetyl-gramicidin S against E. coli and erythrocytes in terms of lipid constituents of the membranes. The mechanism of action of diacetyl-gramicidin S was discussed from the formation of a boundary lipid induced by this peptide.

Animals↗
PubMed1987

Isolation of N-phenylprotoporphyrin IX from the red cells and spleen of the phenylhydrazine-treated rat.

Blood and spleens of phenylhydrazine-injected rats were treated with a solution of acidic methanol and zinc ion to isolate a green pigment. The pigment was resolved into two, I and II, by thin-layer chromatography. Pigment I was a mixture of two isomers of zinc complex of esterified N-phenylprotoporphyrin IX, in which vinyl-substituted pyrrole rings A and B were phenylated; and pigment II was a mixture of two isomers of the porphyrin complex with the N-phenyl group on propionic acid-substituted rings C and D. These pigments were also chemically prepared from the reaction of phenylhydrazine with oxyhemoglobin, independently characterized, and used to confirm the structures of the biological pigments. Determination revealed that the total amount of pigments found in the blood and spleen at 24 h after injection of phenylhydrazine corresponds to about 0.4% of the injected phenylhydrazine.

Animals↗
PubMed1987

Simple and sensitive determination of methylglyoxal in biological samples by gas chromatography with electron-capture detection.

Methylglyoxal was allowed to react with 4,5-dichloro-1,2-phenylenediamine, and the 6,7-dichloro-2-methylquinoxaline formed was determined by gas chromatography with electron-capture detection. The standard curve of the quinoxaline was linear up to 160 pmol/ml. The recoveries of methylglyoxal from coffee and rat liver homogenate were 84.1 and 77.6%, respectively. This procedure was very selective and so sensitive that as little as 9 fmol of the quinoxaline could be measured in biological and food samples.

Aldehydes↗
PubMed1987

Development of a selective clean-up method using immobilized antibody and its application to HPLC and GC/MS determination of a carbacyclin derivative, CS-570, in plasma.

Methods for the determination of CS-570, a chemically stable prostacyclin analogue, in plasma were developed by using an immobilized antibody column followed by fluorescence HPLC and GC/MS. The CS-570 antibody, obtained from rabbit plasma by giving CS-570-BSA for a few months, was coupled to Sepharose 4B and used as extraction phase for sample clean-up and extraction of the drug. A plasma sample was applied to this column, washed with water and the drug was eluted with 90% acetonitrile. 0.02% (w/v) 9-anthryldiazomethane (ADAM) was added to the extract to form a fluorescent derivative. The CS-570-ADAM adduct exhibited high sensitivity when applied to HPLC with fluorescence detection and column switching. The detection limit was 1 ng/mL when 1 mL of plasma was available. Additionally, a pentafluorobenzyltrimethylsilyl derivative of CS-570 showed excellent sensitivity when determined by capillary GC interfaced to negative ion chemical ionization MS using a stable isotope labelled analogue as an internal standard.

Animals↗
PubMed1987

Immunogold labeling of blood-group antigens in human salivary glands using monoclonal antibodies and the streptavidin-biotin technique.

We investigated the localization of blood-group antigens A, B, and H in human labial salivary and submandibular glands by applying a postembedding immunogold method using monoclonal antibodies in combination with the streptavidin-biotin bridge technique. The H, A, and B antigens were only detected in mature secretory granules (SGs), which were mainly found in cells in the late phase of the maturation cycle. In immature SGs, which were present in cells in the early or middle phases of the maturation cycle, these antigens were not detected. All other cytoplasmic organelles were not labeled by the monoclonal antibodies used. In blood-group-O secretors, H antigen was present in almost all of the mature SGs. In blood-group-A secretors, the labeling for H antigen exhibited a mosaic-like pattern, i.e. only some of the mature SGs contained H antigen. With respect to the A and B antigens, a similar mosaic-like pattern of staining was observed in blood-group-A and -B secretors, respectively. To the best of our knowledge, this is the first time that the distribution of blood-group antigens A, B, and H in human tissues has been demonstrated at the electron-microscope-level using monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1987

Localization of dehydropeptidase-I, an enzyme processing glutathione, in the rat kidney.

An antibody prepared against dehydropeptidase-I, one of the glutathione processing enzymes, from the renal membrane fraction of rats was employed to localize at the light microscopic level the enzyme in the kidney using the avidin/biotin-peroxidase complex method. Dehydropeptidase-I was found to be present on both the brush border and the basolateral membranes of proximal tubular cells. Furthermore, the enzyme activity in the isolated brush border and basolateral membrane fractions was also determined. Distribution profiles of the enzyme activity showed good agreement with the results of the immunohistochemical observations.

Animals↗
PubMed1987

Immunoelectron microscopic study of glomerular lesions using a postembedding method with a protein A-gold complex.

Renal biopsy tissue from 33 children with various glomerular diseases has been investigated by electron microscopy using a postembedding immunostaining technique with a protein A-gold complex in order to establish more precise correlations between immunopathologic and morphologic findings in glomeruli. This technique could detect immunoglobulins (IgG, IgA, and IgM), complement factor (C3c), and fibrinogen-related antigen. The immunoreactivity of these antigens was essentially confined to the mesangial, paramesangial, subendothelial, and subepithelial 'electron-dense deposits' in the glomeruli. Except for IgM and C3c in the case of glomerular sclerosis, the distribution of the mentioned factors was even in the electron-dense deposits, as could be shown by 'double-immunolabeling'. From the above-mentioned findings one can conclude that several of the localized factors are associated with the formation of electron-dense deposits, the ultrastructural hallmarks of glomerular disease.

Antigens↗
PubMed1987

Histochemical reactivity of soybean agglutinin with blood group antigens and their precursor substances in acinar cells of human pancreas.

In human pancreas, soybean agglutinin (SBA) conjugated to horseradish peroxidase reacted with the acinar cells secreting blood group A and/or H antigen, but not with those secreting only B antigen. For detailed histochemical characterization of SBA staining, the effects of treatment with unlabeled lectins and of digestion of certain enzymes on SBA staining were investigated in formalin-fixed, paraffin-embedded pancreatic tissue from individuals of different blood groups. Pre-incubation of sections with unlabeled Dolichos biflorus agglutinin to block A antigen eliminated subsequent SBA staining in the cells secreting A antigen, although failing to induce any effects in those secreting H antigen. In contrast, pre-incubation with unlabeled Ulex europaeus agglutinin-I (UEA-I) to block H antigen abolished SBA staining in cells secreting H antigen but not in those secreting A antigen. Treatment with galactose oxidase yielded the same results as those with unlabeled UEA-I, i.e., SBA reactivity was significantly diminished in cells secreting H antigen but not in those secreting A antigen. Digestion with beta-galactosidase resulted in a slight decrease of SBA staining in the cells secreting H antigen. Accompanying the decrease of SBA staining, reactivity with Griffonia simplicifolia agglutinin-II (GSA-II) appeared for the first time in the enzyme-susceptible, SBA-reactive cells secreting H antigen. Pre-treatment with galactose oxidase abolished this effect of beta-galactosidase. The GSA-II reactivity disclosed by treatment with galactosidase was completely eliminated by digestion with beta-N-acetylhexosaminidase, indicating that GSA-II staining after digestion with galactosidase is due to exposed penultimate beta-N-acetyl-D-glucosamine residues. These results demonstrate that at least two substances react with SBA in acinar cells of human pancreas, one being terminal beta-N-acetyl-D-galactosamine residues of A antigen, and the other being terminal beta-D-galactose-(1----3 or 1----4)-beta-N-acetyl-D-glucosamine dimers in the precursor of blood group H antigen. Such dimers may exist in close proximity to L-fucose residues of H antigen, since unlabeled UEA-I blocked SBA staining.

ABO Blood-Group System↗
PubMed1987

Extrarenal metabolism of N-ethyl [2, 3-14C] maleimide-S-glutathione, a model compound of glutathione conjugate.

Radioactive N-ethyl [2, 3-14C]maleimide-S-glutathione (14C-NEM-S-G) was used as a model compound of glutathione conjugate. The metabolism of the conjugate in the extrarenal tissues was investigated in nephrectomized rats and perfused rat livers. When 14C-NEM-S-G was injected intravenously into nephrectomized rats, a significant amount of 14C-NEM-S-cysteine (14C-NEM-S-Cys) was detected in the blood, demonstrating that the conjugate could be metabolized to its cysteine form by extrarenal gamma-glutamyl transferase and dehydropeptidase-I. In the isolated liver perfusion with Krebs-Henseleit buffer containing 25 mM Hepes, both 14C-NEM-S-Cys and 14C-NEM-S-cysteinylglycine (14C-NEM-S-Cys-Gly) were formed from 14C-NEM-S-G. Furthermore, 14C-NEM-S-Cys-Gly was converted to 14C-NEM-S-Cys in the plasma, although 14C-NEM-S-G was not metabolized by the plasma itself. These results demonstrate that the liver and plasma contribute to the metabolism of glutathione conjugates in vivo.

Animals↗
PubMed1987

Derivation of a murine monoclonal antibody useful for immunohistochemical diagnosis of human adenoid cystic carcinoma and stomach cancer.

A monoclonal antibody, NCC-SG-007, was raised with a formalin-fixed adenoid cystic carcinoma of the salivary gland as the immunogen. The reactivity of the antibody was tested on paraffin sections using the avidin-biotin-peroxidase complex (ABC) method. NCC-SG-007 reacted with 36% of the adenoid cystic carcinomas, 42% of the pleomorphic adenomas and 14% of the mucoepidermoid tumors of the salivary gland which were tested. The antibody also reacted with some normal tissues and various other tumors. Surprisingly, NCC-SG-007 showed a reactivity as high as 94% with gastric carcinomas. The antigenic determinant was revealed to be a carbohydrate chain with no terminal sialic acid, the molecular weight of which was estimated to be 1.5 X 10(6) daltons. This antigen differed from other previously reported gastrointestinal cancer-associated antigens. The antibody should be useful for studying adenoid cystic carcinomas of the salivary gland and gastric cancers.

Animals↗
PubMed1987

Role of dehydropeptidase-I in the metabolism of glutathione and its conjugates in the rat kidney.

14C-N-Ethylmaleimide-S-cysteinylglycine was used to investigate the role of dehydropeptidase-I in the metabolism of glutathione conjugates. The dipeptide was rapidly hydrolyzed to 14C-N-ethylmaleimide-S-cysteine in isolated rat renal cells, and subsequently acetylated to 14C-N-ethylmaleimide-S-N-acetylcysteine. Cilastatin, a specific inhibitor of dehydropeptidase-I, strongly inhibited the hydrolysis of the dipeptide by the isolated cells. In rat kidney homogenates, the marked inhibitory effect of cilastatin was also observed on the hydrolysis of cystinyl-bis-glycine and leukotriene D4, which are dipeptide intermediates in the biotransformation of oxidized glutathione and endogenous glutathione conjugate, respectively. In contrast, the inhibitory effect of bestatin, a potent inhibitor of aminopeptidase-M, was much smaller than that of cilastatin on the hydrolysis of these dipeptides by the renal cells and homogenates. These results suggest that dehydropeptidase-I plays a more important role in the metabolism of glutathione and its conjugates than aminopeptidase-M does.

Animals↗