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T Beppu

Publications and source records attributed to T Beppu.

At least 91 records · Page 5Linked to original sources
PubMed1997

[A case of meningioma en plaque: review of 73 cases].

The patient was a 41-year-old female who became aware of a protuberance in the right frontoparietal vault 2 years ago. Three dimensional CT showed a hyperostosis involving the diploe of the skull, and the rough surface of the inner table. In the gadolinium--DTPA enhanced MR images, an entity with a flame-like appearance invading the swollen skull rose from thick homogenously-enhanced dura. The lesion was surgically resected in a circle, and removed with the adherent dura. Histologically, this lesion exhibited a lobular pattern of meningothelial cells, and roughly invaded into the Haversian canals of the skull through the dura. Postoperatively, there was no neurological or physical deficit. In this paper, we reviewed clinical and pathological features of 73 meningioma en plaque cases including the present case.

Adult↗
PubMed1996

Excessive production of nitric oxide in rat solid tumor and its implication in rapid tumor growth.

BACKGROUND: Rapid tumor growth is caused by angiogenesis factors, growth factors, etc. We previously reported a possible connection between nitric oxide (NO) and enhanced vascular permeability in solid tumor. In the present experiment, the role of NO in solid tumor pathology was further investigated in animal tumor. METHODS: To identify NO formed in solid tumor (AH136B) implanted in the feet of rats, electron paramagnetic resonance (EPR) spectroscopy was performed directly on the frozen tumor tissue at 110K by measuring endogenous nitrosyl iron-sulfur complexes, and by using exogenously added NO capturing agents, i.e., diethyldithiocarbamate (DETC)-Fe2+ and N-(dithiocarboxy) sarcosine (DTCS)-Fe2+ complexes. Induction of inducible isoform of nosymthase iNOS mRNA was examined with reverse transcriptase-polymerase chain reaction (RT-PCR) combined with Southern blot analysis. In addition, vascular permeability was assessed by measuring extravasation of 51Cr-labeled bovine serum albumin in solid tumor. RESULTS: Strong EPR signals from NO adducts of DETC-Fe2+ and DTCS-Fe2+ as well as strong signals from NO-hemoglobin and dinitrosyl iron sulfur complex were generated by tumor. The signal height of NO-(DTCS)2-Fe2+ observed in AH136B solid tumor was increased as the tumor gained up to 1.75 g. Induction of iNOS mRNA expression was confirmed by the above methods. Enhanced vascular permeability was suppressed by NOS inhibitors N omega- monomethyl-L-arginine or S-methylisothiourea sulfate and augmented with administration of L-arginine. CONCLUSIONS: Excessive NO production by iNOS in solid tumor was identified unequivocally by EPR spectroscopy. NO formed in solid tumor can be involved in enhanced vascular permeability and increased blood flow, and hence sustain tumor growth.

Animals↗
PubMed1996

The aerial mycelium-defective phenotype of Streptomyces griseus resulting from A-factor deficiency is suppressed by a Ser/Thr kinase of S. coelicolor A3(2).

A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone) is essential for aerial mycelium formation and streptomycin (Sm) production in Streptomyces griseus. A protein Ser/Thr kinase (AfsK), the product of the Streptomyces coelicolor A3(2) afsK gene, controlling secondary metabolism in this strain, reversed the aerial mycelium-negative phenotype of an A-factor-deficient mutant strain, S. griseus HH1, and induced sporulation without affecting A-factor productivity or Sm production. A mutant AfsK protein lacking kinase activity failed to induce aerial mycelium formation which indicates the importance of the kinase activity for suppression in S. griseus. These data suggest that a Ser/Thr kinase functionally similar to S. coelicolor A3(2) AfsK plays a regulatory role in aerial mycelium formation in S. griseus, either as a member in the A-factor regulatory network or independently of this network.

4-Butyrolactone↗
PubMed1996

Genes, enzymes and secondary metabolites in industrial microorganisms. The 1995 Thom Award Lecture.

Apparently contrasting approaches, ie genetic engineering and screening of new microorganisms, play essential complementary roles to develop current industrial microbiology. Three topics, production and modification of milk-clotting proteinases by genetic engineering, hormonal control of secondary metabolism in streptomycetes, and screening of bioactive metabolites, are introduced as cases of such a hybrid approach, while symbiotic microorganisms are discussed as an example of the vast terra incognita still remaining for the future microbiology.

Animals↗
PubMed1996

Integrative transformation of the zygomycete Rhizomucor pusillus by homologous recombination.

For development of a homologous transformation system for the zygomycete fungus, Rhizomucor pusillus, the isopropylmalate isomerase (leuA) gene was cloned from R. pusillus IFO 4578 by the DNA-probing method with the leuA sequence of Mucor circinelloides as probe. The nucleotide sequence revealed that leuA of R. pusillus encoded a 755-amino-acid protein of 82.5 kDa with no intron. The leuA gene on pUC19 (plasmid pRPLeu10) was introduced by polyethyleneglycol-assisted transformation into protoplasts of a leuA- mutant of R. pusillus that was obtained by UV mutagenesis. Transformation under optimal conditions yielded 20 Leu+ transformants (micrograms pRPLeu10 DNA)-1 (1 x 10(6) viable protoplasts)-1. Blot analysis of DNA from the transformants showed that the pRPLeu10 sequence was integrated into the genome by homologous recombination at the leuA locus.

Amino Acid Sequence↗
PubMed1996

Involvement of a residue at position 75 in the catalytic mechanism of a fungal aspartic proteinase, Rhizomucor pusillus pepsin. Replacement of tyrosine 75 on the flap by asparagine enhances catalytic efficiency.

Residue 75 on the flap, a beta hairpin loop that partially covers the active site cleft, is tyrosine in most members of the aspartic proteinase family. Site-directed mutagenesis was carried out to investigate the functional role of this residue in Rhizomucor pusillus pepsin, an aspartic proteinase with high milk-clotting activity produced by the fungus Rhizomucor pusillus. A set of mutated enzymes with replacement of the amino acid at position 75 by 17 other amino acid residues except for His and Gly was constructed and their enzymatic properties were examined. Strong activity, higher than that of the wild-type enzyme, was found in the mutant with asparagine (Tyr75Asn), while weak but distinct activity was observed in Tyr75Phe. All the other mutants showed markedly decreased or negligible activity, less than 1/1000 of that of the wild-type enzyme. Kinetic analysis of Tyr75Asn using a chromogenic synthetic oligopeptide as a substrate revealed a marked increase in kcat with slight change in K(m), resulting in a 5.6-fold increase in kcat/K(m). When differential absorption spectra upon addition of pepstatin, a specific inhibitor for aspartic proteinase, were compared between the wild-type and mutant enzymes, the wild-type enzyme and Tyr75Asn, showing strong activity, had spectra with absorption maxima at 280, 287 and 293 nm, whereas the others, showing decreased or negligible activity, had spectra with only two maxima at 282 and 288 nm. This suggests a different mode of the inhibitor binding in the latter mutants. These observations suggest a crucial role of the residue at position 75 in enhancing the catalytic efficiency through affecting the mode of substrate-binding in the aspartic proteinases.

Amino Acid Sequence↗
PubMed1996

Determination of covalently bound hypusine and deoxyhypusine to protein using submilligram of protein samples by HPLC.

A sensitive and reliable method for the determination of hypusine and deoxyhypusine in eIF-5A protein, an initiation factor of protein synthesis, was developed. An advantage of this method is the use of N epsilon-(5-aminopentyl)lysine, an analogue of deoxyhypusine, as an internal standard. The application made it possible to determine hypusine in less than a mg of protein samples from cultured HTC cells and rat organs. After acid hydrolysis of protein samples to which had been added the internal standard, the hydrolysates were fractionated by carboxymethyl cellulose column chromatography. Also, diamine fractions containing a few pmol of hypusine and deoxyhypusine were successfully analyzed by a reversed phase HPLC with a fluorescence detection of o-phthalaldehyde. The method was applied for the determination of hypusine and deoxyhypusine in drug-treated HTC cells and normal rat organs. The results from HTC cells were discussed based on the known effects of each drug on hypusine biosynthesis.

Animals↗
PubMed1996

[Non-decompression surgery for esophagogastric varices--indication and postoperative result of esophageal transection with paraesophagogastric devascularization and Hassab procedure].

A total of 548 patients had an non-decompression surgery for esophagogastric varices in our hospital, from September 1979 to August 1995. Type of operation includes 402 cases of esophageal transection with paraesophagogastric devascularization (via thoracic approach). 40 cases via abdominal approach, and 106 cases of Hassab procedure. The origin was cirrhosis in 454 patients, IPH in 46, extrahepatic portal occlusion in 29, primary biliary cirrhosis in 6, Budd-Chiari syndrome in 4 and others in 9. Operative mortality rate was less than 1% in child A group, although overall mortality rate including child B, C was 5.0%. By thoracic approach, residual esophageal varices were observed only in 2.5%. Postoperative variceal recurrence were appeared high in cases with hepatocellular carcinoma (HCC). Cumulative recurrence rates at 15 years after surgery were 20.2%, unless HCC had occurred. Cumulative survival rates at 10, 15 years were 52.1%, 45.6% respectively in liver cirrhosis without HCC. Present study confirmed that our operation is effective in controlling esophagogastric varices in long term of periods. Esophagogastric varices of IPH, EHO, and liver cirrhosis of Child A group should be treated by non-decompression surgery.

Esophageal and Gastric Varices↗
PubMed1995

A K-252a-resistance gene, sks1+, encodes a protein similar to the Caenorhabditis elegans F37 A4.5 gene product and confers multidrug resistance in Schizosaccharomyces pombe.

A gene named sks1+ was cloned as a suppressor of the K-252a-sensitivity phenotype of Schizosaccharomyces pombe (Sp) from a gene library of the parental Sp chromosomal DNA constructed with a multicopy vector pDB248'. The gene encoded a 308-amino-acid (aa) protein similar to the Caenorhabditis elegans F37 A4.5 gene product and to the mouse and Drosophila Mov34 gene products. The sks1+ null mutants obtained by gene disruption were non-viable, indicating that sks1+ is essential for vegetative growth. The parental Sp strain carrying multiple copies of sks1+ showed distinct cross-resistance to staurosporine, thiabendazole and vanadate in addition to K-252a, although Sks1 has no similarity in aa sequence to those of ATP-binding cassette (ABC)-type transporters. The multicopy plasmid containing sks1+ conferred multidrug resistance (MDR), even in a mutant cell defective in pmd1+ encoding an ABC-type transporter. It is therefore unlikely that the function of pmd1+ is involved in MDR conferred by sks1+. These results suggest that sks1+ is a functionally novel MDR gene.

Amino Acid Sequence↗
PubMed1995

Radicicol, a protein tyrosine kinase inhibitor, suppresses the expression of mitogen-inducible cyclooxygenase in macrophages stimulated with lipopolysaccharide and in experimental glomerulonephritis.

Two isoforms of cyclooxygenase (COX) have been identified in eukaryotic cells: a constitutively expressed COX-1 and mitogen-inducible COX-2, which is selectively expressed in response to various inflammatory stimuli. Thus, COX-2 instead of COX-1 is implicated to produce prostanoids mediating inflammatory responses. Major efforts have been focused on identifying nonsteroidal anti-inflammatory drugs (NSAIDS) which can selectively inhibit the enzyme activity of COX-2. Such NSAIDS would be more desirable anti-inflammatory agents in comparison to NSAIDS which inhibit both COX-1 and COX-2. Other than glucocorticoids, pharmacological agents which can selectively suppress the expression of COX-2 without affecting that of COX-1 have not been identified. We report here that radicicol, a fungal antibiotic, is a potent protein tyrosine kinase inhibitor, and that it inhibits the expression of COX-2 without affecting COX-1 expression in lipopolysaccharide (LPS)-stimulated macrophages with the IC50 value of 27 nM. Radicicol inhibited tyrosine phosphorylation of p53/56lyn, a Src family tyrosine kinase and one of the major tyrosine-phosphorylated proteins in LPS-stimulated macrophages. Radicicol also inhibited COX-2 expression in vivo in glomeruli of rats with experimental glomerulonephritis induced by the anti-glomerular basement membrane antibodies, in which COX-2 expression is known to be enhanced. The enzyme activity of COX-1 or COX-2 was not affected by radicicol in macrophages. Radiciciol also suppressed the COX-2 expression induced by IL-1 beta in rat smooth muscle cells. Other protein tyrosine kinase inhibitors suppressed the LPS-induced COX-2 expression in macrophages but at much higher concentrations than needed for radicicol. Radicicol did not inhibit the COX-2 expression induced by phorbol 12-myristate 13-acetate in macrophages. These results suggest that the activation of tyrosine-specific protein kinases is the proximal obligatory step in the LPS-induced signal transduction pathway leading to the induction of COX-2 expression in macrophages. The magnitude of the inhibition of COX-2 protein synthesis by radicicol was much greater than that of the steady state levels of COX-2 mRNA. These results suggest that radicicol inhibits COX-2 expression mainly at post-transcriptional steps.

Animals↗
PubMed1995

Trichostatin A and trapoxin: novel chemical probes for the role of histone acetylation in chromatin structure and function.

Reversible acetylation at the epsilon-amino group of lysines located at the conserved domain of core histones is supposed to play an important role in the regulation of chromatin structure and its transcriptional activity. One promising strategy for analyzing the precise function of histone acetylation is to block the activities of acetylating or deacetylating enzymes by specific inhibitors. Recently, two microbial metabolites, trichostatin A and trapoxin, were found to be potent inhibitors of histone deacetylases. Trichostatin A reversibly inhibits the mammalian histone deacetylase, whereas trapoxin causes inhibition through irreversible binding to the enzyme. The histone deacetylase from a trichostatin A-resistant cell line is resistant to trichostatin A, indicating that the enzyme is the primary target. Both of the agents induce a variety of biological responses of cells such as induction of differentiation and cell cycle arrest. Trichostatin A and trapoxin are useful in analyzing the role of histone acetylation in chromatin structure and function as well as in determining the genes whose activities are regulated by histone acetylation.

Acetylation↗
PubMed1995

Secretion by Saccharomyces cerevisiae of rat apolipoprotein E as a fusion to Mucor rennin.

As the first step for production of rat apolipoprotein E (rApoE) in Saccharomyces cerevisiae, the rApoE cDNA was cloned and its nucleotide sequence was determined. When the intact rApoE gene including the presequence-encoding region was expressed under the control of the yeast GAL7 promoter, no protein immunoreactive with anti-rApoE antibody was detected either in the culture medium or inside the cells. For the purpose of the extracellular production of rApoE, three fusion genes were constructed in which the mature rApoE-encoding sequence was connected after the pre, prepro, and whole regions of the gene encoding a fungal aspartic proteinase, Mucor pusillus rennin (MPP), since MPP is efficiently secreted from recombinant S. cerevisiae containing the MPP gene. When these three fusion genes were expressed under the control of the GAL7 promoter, only one, encoding the mature rApoE connected to the whole MPP sequence, directed efficient secretion of the fused protein. The maximum yield of the fused protein secreted into the medium reached 11.8 mg/l and the calculated rApoE part was 5.3 mg in the fused protein. The excreted fusion protein was glycosylated at the original two sites in the MPP part. The fused protein was gradually degraded in the medium probably by proteases of the host cell, because no such degradation occurred in a yeast pep4mutant strain.

Amino Acid Sequence↗