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K Mitsui

Publications and source records attributed to K Mitsui.

At least 145 records · Page 8Linked to original sources
PubMed1992

[A resected case of thymolipoma].

We reported a resected case of thymolipoma, which has been hardly experienced. The patient was 21-year-old female and consulted a doctor for general fatigue. Chest roentgenogram revealed a mass-like shadow at the right lower mediastinum, which was suspected mediastinal tumor. The mass of right anteroinferior mediastinum, which was clearly shown by chest CT scan and MRI, was continued to the right lobe of the thymus. Under a diagnosis of anterior mediastinal tumor, operation was carried out. The tumor, which was 10 x 8 x 7 cm in diameter and 160 g in weight, was removed together with right lobe of the thymus. Histological diagnosis of thymolipoma was obtained from the resected specimen.

Adult↗
PubMed1992

[Use of airway stent subsequent to endoscopic Nd-YAG laser treatment in central airway obstruction].

Ten cases of central airway obstruction mainly caused by extrinsic compression due to the growth of extratracheal malignant tumors or longitudinal extension of tracheal adenoid cystic carcinomas, underwent palliative intubation subsequent to endoscopic Nd-YAG laser treatment. Mean length of the severe stenosis in these cases was 4.4 cm (3-7 cm). Sole application of endoscopic Nd-YAG laser to the stenosis failed relief of the symptom and an immediate palliative intubation was recommended. Mean time of the temporary intubation was 7 days (4-11 days). Airway was maintained by this intubation and also retained enough after extubation. Therefore, it seemed that, in a palliative treatment of the central airway severe stenosis, usefulness of the combination management of Nd-YAG laser with following temporary intubation was revealed. However, in order to maintain the airway for recurrence of the obstruction, use of indwelling airway stents seemed a better application. The longest period of follow-up in the cases treated by indwelling airway stents was 6 months and one of the cases is a now in comfortable state.

Adult↗
PubMed1991

Factor IX Amagasaki: a new mutation in the catalytic domain resulting in the loss of both coagulant and esterase activities.

Factor IX Amagasaki (AMG) is a naturally occurring mutant of factor IX having essentially no coagulant activity, even though normal levels of antigen are detected in plasma. Factor IX AMG was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Factor IX AMG was cleaved normally by factor VIIa-tissue factor complex, yielding a two-chain factor IXa. Amino acid composition and sequence analysis of one of the tryptic peptides isolated from factor IX AMG revealed that Gly-311 had been replaced by Glu. We identified a one-base substitution of guanine to adenine in exon VIII by amplifying exon VIII using the polymerase chain reaction method and sequencing the product. This base mutation also supported the replacement of Gly-311 by Glu. In the purified system, factor IXa AMG did not activate factor X in the presence of factor VIII, phospholipids, and Ca2+, and no esterase activity toward Z-Arg-p-nitrobenzyl ester was observed. The model building of the serine protease domain of factor IXa suggests that the Gly-311----Glu exchange would disrupt the specific conformational state in the active site environment, resulting in the substrate binding site not forming properly. This is the first report to show the experimental evidence for importance of a highly conserved Gly-142 (chymotrypsinogen numbering) located in the catalytic site of mammalian serine proteases so far known.

Amino Acid Sequence↗
PubMed1991

Bilateral hydrophobic zipper as a hypothetical structure which binds acidic ribosomal protein family together on ribosomes in yeast Saccharomyces cerevisiae.

Acidic ribosomal protein family of yeast Saccharomyces cerevisiae consists of four species of 13-kDa proteins and one species of 38-kDa protein. These proteins are thought to form a complex on ribosomes functioning in the translational elongation reaction, but the structural basis how to associate with one another is not known. In this communication, we show for the first time the presence of a structure equivalent to the leucine zipper on a putative alpha-helix in the 38-kDa acidic ribosomal protein, A0. Then, all the 13-kDa acidic ribosomal proteins are shown to have two periodic arrays of hydrophobic amino acid residues arranged on the opposite sides of a putative alpha-helix, which is referred to as the "bilateral hydrophobic zipper". Therefore, it is proposed that one of the 13-kDa acidic ribosomal proteins associates with 38-kDa protein A0 via the hydrophobic zipper and then the other 13-kDa proteins associate side by side via the bilateral hydrophobic zippers.

Amino Acid Sequence↗
PubMed1991

A cytolysin, theta-toxin, preferentially binds to membrane cholesterol surrounded by phospholipids with 18-carbon hydrocarbon chains in cholesterol-rich region.

We have previously suggested the existence of two distinctive states of cholesterol in erythrocyte and lymphoma cell membranes as revealed by high- and low-affinity binding sites for theta-toxin of Clostridium perfringens [Ohno-Iwashita, Y., Iwamoto, M., Mitsui, K., Ando, S., & Nagai, Y. (1988) Eur. J. Biochem. 176, 95-101; Ohno-Iwashita, Y., Iwamoto, M., Ando, S., Mitsui, K., & Iwashita, S. (1990) Biochim. Biophys. Acta 1023, 441-448]. To understand factor(s) which determine membrane cholesterol heterogeneity, we analyzed toxin binding to large unilamellar liposomes composed of cholesterol and phospholipids (phosphatidylcholine/phosphatidylglycerol = 82:18, mol/mol). Liposomes containing phospholipids with 18-carbon hydrocarbon chains at both positions 1 and 2 of the glycerol have both high- and low-affinity toxin-binding sites with Kd values similar to those of intact erythrocytes, whereas liposomes with hydrocarbon chains containing 16 or fewer carbons at either position 1 or 2 have only low-affinity toxin-binding sites. The cholesterol/phospholipid ratio, in addition to the length of phospholipid hydrocarbon chain, also determines the number of toxin-binding sites, indicating that at least these two factors determine the topology of membrane cholesterol by creating distinctively different affinity sites for the toxin. Since theta-toxin binding detects specific populations of membrane cholesterol that are not detectable by the measurements of susceptibility to cholesterol oxidase and cholesterol desorption from membranes, the toxin could provide a unique probe for studying the organization of cholesterol in membranes.

Bacterial Toxins↗
PubMed1991

Increased plasma concentrations of endothelin-1 during and after pulmonary surgery.

We studied the involvement of endothelin-1 (ET-1) in the physiological response to surgical stress. Plasma concentrations of ET-1 were measured by a sandwich-type enzyme immunoassay. The blood samples were collected from the pulmonary artery (PA), the left atrium (LA), and the median cubital vein (MCV) in four patients who had undergone pulmonary lobectomy. The samples were collected before, during, and after surgery. Plasma ET-1 concentrations increased in the blood from all sampling sites. The highest concentration of plasma ET-1 was observed at 6 h after surgery in MCV (3.97 +/- 1.47 pg/ml, mean +/- SD) and at the end of surgery in PA (1.79 +/- 0.48 pg/ml) and in LA (1.93 +/- 0.43 pg/ml). These values returned to the baseline value within 72 h after surgery [1.21 +/- 0.19 (MCV), 1.00 +/- 0.18 (PA)]. Although the lung has a large capacity to remove ET-1 from the circulating blood, ET-1 concentrations measured in plasma samples obtained from the LA were not different from those obtained from the PA. This may suggest that the lungs have the ability to absorb and release ET-1 simultaneously during pulmonary surgery. The increase of ET-1 in MCV was greater than that in PA or in LA. This suggests the possibility of ET-1 release from the forearm.

Endothelins↗
PubMed1991

Multiple neurite formation in neuroblastoma cell lines by griseolic acid, a potent inhibitor of cyclic nucleotide phosphodiesterases.

The morphological change of several neuroblastoma cell lines induced by griseolic acid, a novel and potent inhibitor of cyclic nucleotide phosphodiesterase (PDE), was examined. In the cell lines tested, Neuro-2a (a murine neuroblastoma cell line) showed dose-dependent (1 microM-1 mM) neurite extension. Griseolic acid markedly increased the intracellular cyclic AMP level of Neuro-2a cells, suppressed DNA synthesis (82% at 1 mM), and induced multipolar (multiple-neurite-bearing)-type neuritogenesis. A similar type of neurite outgrowth was induced by 8-bromo-cyclic AMP, which also elevated the intracellular cyclic AMP concentration. In contrast, when Neuro-2a cells were treated with retinoic acid, neurite formation was of the monopolar (single-neurite-bearing) type. Papaverine and theophylline, which have been frequently used as PDE inhibitors, failed to induce these morphological changes up to 1 mM, probably owing to the lesser potency of these compounds as compared with griseolic acid on the inhibition of PDE. Retinoic acid, theophylline, and papaverine were ineffective at elevating the intracellular cyclic AMP level. These results suggest that multipolar-type cell shape change in Neuro-2a cells is correlated with the accumulation of intracellular cyclic AMP and that griseolic acid is a useful compound to induce neuroblastoma cells into terminal differentiation.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1991

A case of renin producing leiomyosarcoma originating in the lung.

A 54-year-old woman was referred to our hospital for the treatment of a tumor of the right chest wall. Clinical examination revealed hypertension, hypokalemia, metabolic alkalosis, hyperaldosteronism and hyperreninemia. Computed tomography and an abdominal echogram indicated a tumor in the right phrenic area and two tumors in the retroperitoneum near the pancreas head. After the surgical resection of these tumors, the primary reninism was diminished. The pathological diagnosis of these tumors was leiomyosarcoma. Plasma active and inactive (trypsin-activated) renin activities (PRA) were 85.7 and 38.9 ng angiotensin I/ml/h, respectively. These PRA did not respond to either postural stimulation or suppression by the volume expansion. Active and inactive renin activities in a right phrenic area tumor were 208 and 32 ng angiotensin I/mg protein /h, respectively. Those of an abdominal tumor were 196 and 30 ng angiotensin I/mg protein/h, respectively. Renin mRNA identical in molecular size to that of the human kidney was identified by northern blot analysis. This is the first case report of renin producing leiomyosarcoma derived from the lung, which is characterized by relatively lower plasma prorenin concentrations.

Abdomen↗
PubMed1991

[Recurrent herpetic keratitis in mice].

In order to investigate the mechanism of recurrence in herpes simplex keratitis, it is very important to establish an animal model. As a first step, mice were examined with the slit-lamp biomicroscope to determine whether they spontaneously showed recurrent epithelial keratitis after healing of primary herpetic keratitis. Among 90 eyes of 45 inbred C57BL/6 mice, recurrent epithelial keratitis stained with fluorescein was observed in 10 eyes of 9 mice during the observation period up to 50 days after the primary corneal infection with herpes simplex virus (HSV) type I Amakata strain (virulent strain). Recurrent epithelial keratitis was observed in 17 eyes of 15 mice among 116 eyes of 58 ddy mice infected with HSV-I Ska strain (avirulent strain). The epithelial lesions showed punctate or dendritic patterns and continued for one to 7 days. HSV antigen was detected by the fluorescent antibody technique in the cornea of 5 out of 8 eyes which showed recurrent epithelial keratitis using another ddy mice group tested. It was limited in the epithelium of the cornea. These results show that mice herpetic keratitis recurs spontaneously.

Animals↗
PubMed1990

Examination of the role of serine phosphorylation in phospholipase C-gamma and its related P47 in cAMP-mediated depression of epidermal growth factor signal transduction.

Forskolin-pretreatment of A431 cells reduced both intrinsic and epidermal growth factor (EGF)-induced EGF receptor phosphorylation, however, phosphorylation of phospholipase C-gamma (PLC-gamma) was stimulated under the same conditions. No significant difference was detected in the amount of phosphotyrosine of PLC-gamma between two cultures with or without forskolin treatment followed by EGF. On the other hand, phosphorylation of a 47 kDa protein (P47) which cross-reacted with an anti-PLC-gamma monoclonal antibody, was stimulated by both forskolin and EGF. Phosphorylation was exclusively on serine residues in this case. These results indicate that both PLC-gamma and P47 are phosphorylated by a cAMP-dependent protein kinase and the EGF-stimulated serine kinase, and suggest that serine phosphorylation of PLC-gamma has no effect on ligand-dependent coupling with the EGF receptor.

Colforsin↗
PubMed1990

cAMP-mediated modulation of signal transduction of epidermal growth factor (EGF) receptor systems in human epidermoid carcinoma A431 cells. Depression of EGF-dependent diacylglycerol production and EGF receptor phosphorylation.

While a cAMP-dependent protein kinase (protein kinase A) has been suggested to phosphorylate epidermal growth factor (EGF) receptor in vitro, both intrinsic and EGF- or potent phorbol tumor promoter-induced phosphorylation of EGF receptor were found to be depressed in human epidermoid carcinoma A431 cells by prior incubation of the cells with various protein kinase A activators (e.g. cholera toxin, forskolin, cAMP analogues, or a combination of prostaglandin E1 and 3-isobutyl-1-methylxanthine). Protein kinase A activators did not change significantly either the number of EGF receptors or their affinity for EGF. The tryptic phosphopeptide map of EGF receptors from cells treated with cholera toxin alone or cholera toxin followed by EGF revealed unique peptides whose serine phosphorylation was preferentially depressed. However, the catalytic subunit of protein kinase A phosphorylated no threonine and little serine in the EGF receptors in the plasma membranes of isolated A431 cells in vitro, while serine residues in an unidentified 170-kDa membrane protein(s) other than EGF receptor were heavily phosphorylated. Pretreatment of the cells with forskolin blocked 1,2-diacylglycerol induction by EGF; growth inhibition by nanomolar levels of EGF could be partially restored by the presence of forskolin. These results indicate that an increase in intracellular cAMP modulates the EGF receptor signal transduction system by reducing EGF-induced production of diacylglycerol without direct phosphorylation of EGF receptors by protein kinase A in A431 cells.

1-Methyl-3-isobutylxanthine↗
PubMed1990

A modified theta-toxin produced by limited proteolysis and methylation: a probe for the functional study of membrane cholesterol.

A derivative of cytolytic theta-toxin from Clostridium perfringens was prepared by limited proteolytic digestion of the native toxin followed by methylation. Among the chloroform/methanol-extractable, lipid components of sheep and human erythrocytes, the proteinase-nicked and methylated derivative (MC theta) specifically binds to cholesterol. While MC theta retains binding affinity comparable to that of intact toxin, it causes no obvious membrane damage, resulting in no hemolysis at temperatures of 37 degrees C or lower. Using MC theta, we demonstrated the possible existence of high- and low-affinity sites for theta-toxin on sheep erythrocytes at both 37 degrees C and 10 degrees C. The number of high-affinity sites on sheep erythrocytes was estimated to be approximately 3-times larger at 37 degrees C than that at 10 degrees C. In addition, high- and low-affinity sites were demonstrated in human erythrocytes and a lymphoma B cell line, BALL-1 cells. Both binding sites disappear upon simultaneous treatment of cells with sublytic doses of digitonin, suggesting that cholesterol is an essential component of both the high- and low-affinity sites and that the mode of cholesterol existence in plasma membranes is heterogeneous in these cells. Because of its high affinity for membrane cholesterol without causing any obvious membrane changes at physiological temperatures, MC theta may provide a probe for use in the functional study of membrane cholesterol.

Animals↗
PubMed1990

A high-performance liquid chromatography method for separation of purine bases, nucleosides and ureides: application to studies on purine catabolism in higher plants.

Mixtures of purine nucleotides, nucleosides, nucleobases, uric acid, allantoin and allantoic acid were fractionated by high-performance liquid chromatography on a polyvinyl alcohol gel column, Asahipak GS-320H, with isocratic elution by sodium phosphate. Application of this system to the determination of the sizes of cellular pools of purine derivatives in plant cells and of the activity of related enzymes, as well as to the purification of enzymatically synthesized radioactive compounds, is described.

Cells, Cultured↗
PubMed1990

Detection of tumour necrosis factor/cachectin in pleural effusion of patients with lung cancer.

We have found that the pleural effusion obtained from a patient with lung cancer (adenocarcinoma) has cytotoxic activity against the patient's lung cancer cells. This finding occurred in the course of establishing a lung cancer cell line from the patient's pleural effusion. The cytotoxic factor was partially purified from the pleural effusion and characterized. It had cytotoxicity against L-929 mouse fibroblasts in the standard 18-h killing assay of tumour necrosis factor (TNF). By molecular sieving chromatography, the activity appeared at molecular weight of 50,000. This activity was completely blocked by a monoclonal antibody to TNF. From these results, we conclude that the cytotoxic factor in the pleural effusion is TNF. The concentration of TNF in the pleural effusion was 34.5 pg/ml by radioimmunoassay. In addition, we detected TNF activity and protein in two other cases of carcinomatous pleural effusion. Therefore, it would appear that in vivo TNF displays cytotoxic activity against cancer cells.

Adenocarcinoma↗
PubMed1990

Inhibition of proliferative responses and interleukin 2 productions by salazosulfapyridine and its metabolites.

Mixed lymphocytes reactions (MLR) and concanavalin A (Con A)- or phytohemagglutinin (PHA)-stimulated proliferative responses were dose-dependently inhibited by salazosulfapyridine (SASP) and cyclosporin A (CsA) in the concentration ranges of 1 x 10(-5) -5 x 10(-4) M and 10-1000 ng/ml, respectively. Such a significant inhibition was not observed with metabolites of SASP, sulfapyridine (SP) and 5-aminosalicylic acid (5-ASA). In addition, SASP and CsA inhibited the production of interleukin 2 (IL-2) from splenocytes in these experiments. The inhibitory effect of CsA on IL-2 production practically correlated with that on proliferative responses, whereas SASP showed a less marked inhibitory effect on IL-2 production than on proliferative responses. Neither SP nor 5-ASA inhibited the IL-2 production. In the Con A-induced proliferative response, SASP showed a full inhibition even when added after 4-8 hr of culture, but CsA did not. The splenocytes that were pulsed with Con A for 4 hr could proliferate in response to Con A-supernatant or purified IL-2. CsA exhibited the inhibitory activity only when present during the time of Con A-pulsing, while SASP acted on the subsequent stage of the response, exerting its inhibitory effect. These findings suggest that SASP down-regulates the immune response by a mechanism apparently distinct from that of CsA.

Aminosalicylic Acids↗