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Biomedical subjects

S Taketani

Publications and source records attributed to S Taketani.

At least 73 records · Page 4Linked to original sources
PubMed1997

Biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass.

In this study, we evaluated the biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass (CPB). Eight patients were divided into 2 groups: the control group (Group C) and heparin-coated group (Group H). In Group H, CPB circuits, including the arterial pump, oxygenator, and cannulas were heparin-coated. Before, during, and after CPB, blood samples were obtained to assess the platelet counts (Plat), alpha 2-plasmin plasminogen inhibitor complex (PIC), thrombin-antithrombin III complex (TAT), C3 activation products (C3a), interleukin (IL)-6, IL-8, and polymorphonuclear neutrophil leukocyte (PMN) elastase. There was no significant difference in Plat, PIC, or TAT between groups. Group H showed significantly low levels of C3a (during and after CPB), PMN elastase (during CPB), and IL-6 (after CPB). These data demonstrated that in pediatric CPB, heparin-coated CPB circuits reduced the activation of complements and the production of PMN elastase and IL-6, suggesting the superior biocompatibility of the heparin-coated circuits.

Anticoagulants↗
PubMed1997

Molecular defects of the coproporphyrinogen oxidase gene in hereditary coproporphyria.

Hereditary coproporphyria (HCP) is an acute hepatic porphyria, and is an autosomal dominant disorder but with a variable degree of clinical expression. Molecular cloning, sequencing and expression of the defective gene for coproporphyrinogen oxidase (CPO) in a patient with HCP were carried out. Enzyme assays revealed that CPO activity in EBV-transformed lymphoblastoid cells from the proband and one of her sisters was approximately 50% of normal. Nucleotide sequence analysis of CPO cDNAs isolated from the proband's cells demonstrated 3 base substitutions which accompanied 3 different amino acid substitutions. An A514-->C transition causing an Asn172-->His substitution occurred in one allele, while two other transitions, G265-->A and G580-->A, caused Gly89-->Ser and Val194-->Ile substitutions, respectively, in the other allele. The A514-->C and the G580-->A transitions were shown to be genetic polymorphisms. Transfection of CPO cDNA into E. coli demonstrated that cDNA with the G265-->A transition produced a protein with less than 5% of normal enzyme activity. These findings indicate that the G265-->A transition, involving the highly conserved glycine residue at the 89th position, is responsible for the CPO defect in the patient and accounts for the partial deficiency of CPO activity in this pedigree. This mutation is different from three other mutations reported in patients with HCP. Molecular defects in the porphyrias including HCP are highly heterogeneous.

Cell Line, Transformed↗
PubMed1997

[David's operation for aortic regurgitation associated with annulo-aortic ectasia].

A 54-year-old man with AR due to AAE underwent the replacement of ascending aorta by sparing an aortic valve (David operation). Under cardiopulmonary bypass, the aneurysmal aorta and the all three sinuses of valsalva were excised, leaving 5 mm of arterial wall attached to the aortic valve. The aortic valve was reimplanted inside a Dacron graft (28 mm Hemashield) which was calculated by aortic valve leaflet height as well as from the size of LVOT. The patient has survived the operative procedure and showed uneventful recovery. We believe this new procedure preserving the native aortic valve is useful for preventing from some complications associated with an artificial heart valve and improvement of QOL of patient.

Aorta↗
PubMed1996

Molecular cloning and characterization of a cDNA that encodes protoporphyrinogen oxidase of Arabidopsis thaliana.

A cDNA encoding protoporphyrinogen oxidase (PPOX), the last enzyme common to the biosynthetic pathways for chlorophylls and hemes, was obtained from a library of Arabidopsis thaliana cDNA constructed in a lambda vector by screening for complementation of a hemG mutant of Escherichia coli. Extracts of E. coli cells transformed with the Arabidopsis PPOX cDNA had high PPOX activity, and this activity was markedly inhibited by acifluorfen, a specific inhibitor of PPOX. Sequence analysis revealed that the cDNA for Arabidopsis PPOX encodes a protein of 537 amino acids (aa) with a calculated molecular mass of 57.7 kDa. The deduced aa sequence exhibited similarity to sequences of PPOX from Bacillus subtilis, mouse, and human. However, the PPOX of Arabidopsis contained a putative leader peptide for import into mitochondria (mt). southern analysis indicated that the PPOX whose cDNA we cloned is encoded by a single gene in Arabidopsis. Northern blot analysis showed that the level of expression of the gene in Arabidopsis leaves was high. whereas it was low in roots and floral buds. To our knowledge, this is the first report for the cloning of a cDNA for a plant PPOX.

Amino Acid Sequence↗
PubMed1996

Requirement of multiple DNA-protein interactions for inducible expression of RNR3 gene in Saccharomyces cerevisiae in response to DNA damage.

The RNR3 gene encodes the large subunit of ribonucleotide reductase. Transcription of this gene is induced 12-fold in response to DNA damage or by a DNA replication blocker. To investigate cis-acting regulation, deletion analysis of the promoter region of the RNR3 gene was performed and we identified two upstream-repressing sequences in the RNR3 regulatory region. An 18-base-pairs fragment, termed DNA-damage responsive element 1 (DRE1) located between -212 and -194 in this region was found to be essential for the induction of RNR3. This fragment contained a negatively acting sequence where a protein factor bound to the region during normal growth but disappeared by exposure to 4-nitroquinoline-1-oxide. The other repressive element homologue to DRE1 was located at -263 to -254. One possible upstream-activating sequence which regulates the basal expression of RNR3 was also found. These results show that at least three potential cis-elements are necessary for the inducible expression of yeast expression of yeast RNR3 in response to DNA damage.

4-Nitroquinoline-1-oxide↗
PubMed1996

Mouse coproporphyrinogen oxidase is a copper-containing enzyme: expression in Escherichia coli and site-directed mutagenesis.

We previously isolated cDNA for mouse coproporphyrinogen oxidase (CPO) and provided evidence for the induction of mRNA during differentiation of murine erythroleukemia cells (Kohno et al. (1993) J. Biol. Chem. 268, 21359-21363). To better understand the structure and the mechanisms of reaction of the enzyme, we expressed mouse CPO in Escherichia. coli and purified it to a homogeneity. Analysis of the metal content revealed that the recombinant mouse CPO contains one copper atom per polypeptide chain. When the bacterial cells were treated with D-penicillamine, a copper chelator, formation of the active CPO was partially reduced. Addition of Cu2+ in minimal medium resulted in 6-fold higher level of CPO activity. These results suggest that expression of active mouse CPO in E. coli depended on the presence of Cu2+ in the culture medium. To elucidate the apparent involvement of Cu2+ in enzyme function, a series of mutant enzymes, whose highly conserved histidine and cysteine residues were individually converted to alanine residue, were prepared by site-directed mutagenesis. Mutant enzymes were expressed in E. coli and their activities examined. Mutation at histidine 158 resulted in a complete loss of enzyme activity, yet the enzyme protein was expressed at a comparable level. Concomitantly, only a trace amount of Cu2+ was detected in the purified H158A enzyme. We propose that mouse CPO is copper-containing enzyme and Cu2+ interacts with a conserved histidine residue.

Amino Acid Sequence↗
PubMed1996

Late true aneurysm after bypass grafting for long aortic coarctation.

Two adolescent patients who underwent a repair of long aortic coarctation using bypass grafting with subsequent late true aneurysm formation are reported. To our knowledge, only 1 case of late true aneurysm formation after bypass grafting has been reported in the English-language literature.

Adolescent↗
PubMed1996

Induction of peripheral-type benzodiazepine receptors in mouse brain following thioacetamide-induced acute liver failure.

To investigate the possible role of peripheral-type benzodiazepine receptors (PBR) in hepatic encephalopathy, we examined expression of PBR in mouse brain following thioacetamide (TAA)-induced acute liver failure. Treatment of mice with TAA resulted in an increase in the number of binding sites of the PBR ligand [3H] Ro5-4864 to brain homogenates, with no significant change in affinity of the ligand. The order of potency of different ligands to compete against [3H] Ro5-4864 binding in the brain of TAA-treated mice was Ro5-4864 > PK11195 > diazepam > protoporphyrin IX, findings similar to those in the control. Northern blot analysis revealed an increase in PBR/isoquinoline binding protein (PBR/IBP) mRNA in mouse brain following TAA treatment, in a time- and dose-dependent manner. These results indicate that the increased number of PBR in the brains of TAA-treated mice relates to the induction of PBR/IBP expression and suggest that the induction of PBR in brain may contribute to pathogenesis of hepatic encephalopathy.

Animals↗
PubMed1996

Identification of three mutations and associated haplotypes in the protoporphyrinogen oxidase gene in South African families with variegate porphyria.

Mutation analysis of genomic DNA samples obtained from 17 unrelated South African patients with variegate porphyria (VP) revealed three novel missense mutations in the protoporphyrinogen oxidase (PPOX) gene. A common C to T transition at nucleotide position 452 (R59W) was identified in 15 of the patients analysed, while base changes at positions 336 (H20P) and 779 (R168C) were identified in the remaining two patients. Using protein analysis software we were able to predict that all three mutations have a similar biophysical effect on the protein, being the disturbance of amphiphatic regions within the protein, which might result in misfolding of the protein. Mutation R59W, identified in the majority of South African VP families, was shown to create a Styl restriction site, while mutation R168C would abolish a Dsal restriction site in genomic DNA of affected individuals. As 100% of the index patients analysed were molecularly characterized, the combined use of restriction enzyme and single-strand conformation polymorphism (SSCP) analysis now allows a rapid and accurate diagnosis of VP in South Africa. Mutation R59W was furthermore shown to be in association with one of four potential haplotypes defined by two newly described polymorphisms in exon 1 of the PPOX gene. Our molecular data thus strongly support the founder hypothesis for VP in South Africa.

DNA Mutational Analysis↗
PubMed1996

Human trehalase: characterization, localization, and its increase in urine by renal proximal tubular damage.

By using polymerase chain reaction, cDNA encoding human renal trehalase has been isolated. The partial amino acid sequence deduced by the cDNA showed homologies in rabbit, Tenebrio molitor and silkworm trehalase. Northern blots showed renal trehalase mRNA to be about 2.0 kb. To examine the properties of renal and urinary human trehalase, the trehalase cDNA was inserted in the pMAL-cRI vector downstream from the malE gene, which encodes maltose-binding protein. Transfection of the recombinant pMAL-cRI in Escherichia coli provided high levels of expression of the maltose binding protein-trehalase fusion protein. A rabbit was immunized with purified fusion protein, and antihuman trehalase antibodies were obtained. Immunoblot analysis disclosed that renal and urinary trehalase exhibited a molecular mass of about 75 kDa. Analysis by indirect fluorescent microscopy demonstrated that the enzyme located in only proximal tubular cells. Urinary trehalase activity was low in the healthy infants and elevated in patients with asphyxia. Markedly high activity was observed in a patient with Lowe syndrome. The immunoreactive urinary trehalase with 75 kDa was increased dependent on the elevation of the activity. On the basis of these findings, we conclude that the increase of urinary trehalase reflects the extent of renal tubular damage, and we propose that urinary trehalase can be a specific marker of renal tubular damage.

Amino Acid Sequence↗
PubMed1996

[A case of ventricular septal defect closure in patient with cytomegalo virus hepatitis].

Cytomegalovirus (CMV) infection has been reported to cause serious event in nonimmunocompromised patients after major surgery. Particularly in active case, the indication of surgical intervention is a difficult issue. A 7-months-old boy with ventricular septaldefect (VSD) has been diagnosed with CMV hepatitis. As his heart failure was not controlled with medication, he underwent closure of VSD at 9 months of age while CMV was still detected in the urine and serum by polymerase chain reaction method. During post operative course, he was treated with ganciclovir and intravenous CMV hyperimmune grobiln, and CMV in the serum became negative and he develops no aggravation of the CMV infection postoperatively.

Antiviral Agents↗
PubMed1995

Inhibition of the thiol-specific antioxidant activity of rat liver MSP23 protein by hemin.

Mouse stress-inducible 23-kDa protein (MSP23) belongs to a new type of antioxidative protein family and is highly expressed in livers. To examine its physiological role in the tissue, we have purified native MSP23 protein from the cytosolic fraction of rat liver. The purified protein showed the thiol-specific antioxidant activity and protected glutamine synthetase from inactivation by a mixed metal-thiol oxidation. We examined the effect of hemin on that activity since it was recently shown by others that the rat liver MSP23 protein had a high binding affinity to heme. We have found that hemin at low concentrations inhibits the antioxidative activity of MSP23. This result suggests that one type of oxidant damage caused by hemin to cells is due to inactivation of the antioxidative protein, MSP23.

Ammonium Sulfate↗
PubMed1995

Induction in the gene RNR3 in Saccharomyces cerevisiae upon exposure to different agents related to carcinogenesis.

The induction of the gene RNR3 was investigated in yeast Saccharomyces cerevisiae using RNR31 lacZ fusion. Gene induction was monitored by measuring beta-galactosidase activity. Various drugs that cause DNA damage effectively induced RNR3 expression; alkylating agents (cisplatin, mitomycin C and N-methyl-N'-nitro-N-nitrosoguanidine), a radical producer (bleomycin), and an intercalator (actinomycin D) induced RNR3. When yeast expressing rat CYP1A1 was exposed to 2-aminofluorene, a concentration-dependent induction of RNR3 was observed. Aflatoxin B1 also induced the expression of RNR3 in the same yeast strain concomitant with inhibition of cell growth. In control yeast, no induction of RNR3 was observed upon exposure to 2-aminofluorene or aflatoxin B1. Exposure to 2-acetylaminofluorene or benzo[a]pyrene did not lead to induction of RNR3 in yeast expressing CYP1A1. These results indicate that DNA damage by chemicals related to carcinogenesis induces RNR3, and that activation of these procarcinogens was required for DNA damage-dependent induction of RNR3.

Animals↗
PubMed1995

The human protoporphyrinogen oxidase gene (PPOX): organization and location to chromosome 1.

We determined the structure of the human protoporphyrinogen oxidase (PPOX) gene after isolation and characterization of lambda phage clones mapping discrete regions of the cDNA. Southern blotting of human genomic DNA showed that there is a single copy of the PPOX gene, and fluorescence in situ hybridization to metaphase chromosomes mapped the gene to region 1q22. The gene has 13 exons and about 8 kb. The exon/intron boundary sequences conform to consensus acceptor (GTn) and donor (nAG) sequences, and exons in the gene appear to encode functional protein domains. Primer extension analysis revealed two major transcriptional initiation sites in a region with sequence motifs characteristic of a promoter. The promoter region contains multiple Sp1 elements, CCAAT boxes, and potential GATA-1 binding sites. Mapping of the 5' end PPOX mRNA by polymerase chain reaction indicated that there are the same transcripts in erythroid and nonerythroid cells.

Bacteriophage lambda↗
PubMed1995

Cloning, expression, and chromosomal localization of a novel cadherin-related protein, protocadherin-3.

To study the diversity of the protocadherin family, the cDNA clones for a novel protocadherin were isolated by screening rat brain cDNA libraries with a cDNA fragment obtained by PCR, and some of the properties were then characterized. The overall structure of the protein defined by the clone is similar to that of previously identified protocadherins; however, the cytoplasmic domain is distinct from those of previously cloned protocadherins or any other protein sequences in the data bank. We named this protocad herin-3 (Pcdh3) since this is the third protocadherin of which the entire coding sequence has been determined. Most of the deduced amino acid sequences of other cDNA clones obtained by the screening show high homology with but are distinct from that of Pcdh3, indicating that most of these sequences correspond to homologous but different protocadherins. These results demonstrate that Pcdh3 and the protocadherins defined by these clones constitute a protocadherin subfamily. Chromosome mapping indicates that mouse Pcdh3 is located in a specific region of mouse chromosome 18, close to the location of previously cloned protocadherins, suggesting that various protocadherins form a cluster in this region. In situ hybridization results showed that Pcdh3 and its related proteins were expressed at various areas in brain. The expressed Pcdh3 protein from the cDNA in mouse L cells was about 100 kDa in molecular weight and was localized at cell-cell contact sites. In contrast to the classical cadherins, however, the expressed Pcdh3 was sensitive to trypsin even in the presence of Ca2+, and the transfectants did not show strong Ca(2+)-dependent cell aggregation activity. These results indicate the structural and possibly functional diversity of the protocadherin family and suggest a distinctive biological role for Pcdh3.

Amino Acid Sequence↗
PubMed1995

Nitric oxide-mediated inactivation of mammalian ferrochelatase in vivo and in vitro: possible involvement of the iron-sulphur cluster of the enzyme.

To investigate the role of the iron-sulphur cluster in mammalian ferrochelatases, the terminal enzyme of the haem biosynthetic pathway, we examined the interaction of nitric oxide (NO) and ferrochelatase. When macrophage cell line RAW 264.7 cells were treated with interferon-gamma and lipopolysaccharide NO synthesis in the cells was stimulated, and a decrease in ferrochelatase activity was observed, with no change in the amount of ferrochelatase. The addition of NG-monomethyl-L-arginine, a selective inhibitor of NO synthesis, reduced the effect of interferon-gamma and lipopolysaccharide, while the effect of NG-monomethyl-L-arginine was suppressed by the addition of L-arginine, a substrate of NO synthase. When purified recombinant human ferrochelatase was treated with 3-morpholinosydnonimine, a NO-generating compound, ferrochelatase activity decreased with disappearance of characteristic absorbance spectra of the iron-sulphur cluster. S-Nitroso-N-acetylpenicillamine also reduced the activity, in a dose-dependent manner. These results indicate that ferrochelatase activity can be modulated by NO synthesis probably through disruption of the iron-sulphur cluster. We propose that inactivation of ferrochelatase mediated by NO (or NO-derived species) may play a role in the regulation of haem metabolism.

Amino Acid Oxidoreductases↗
PubMed1995

Induction of the antioxidant stress proteins heme oxygenase-1 and MSP23 by stress agents and oxidised LDL in cultured vascular smooth muscle cells.

Enhanced expression of the antioxidant stress proteins heme oxygenase-1 (HO-1) and macrophage stress protein (MSP23) by oxidative stress agents and oxidatively modified low density lipoproteins (LDL) was investigated in cultured porcine aortic smooth muscle cells. Treatment of smooth muscle cells with glucose oxidase, CdCl2 or diethylmaleate resulted in a time-dependent (6-48 h) induction of HO-1 and MSP23 expression. Exposure of cells to 100 micrograms protein/ml highly oxidised LDL increased the expression of HO-1 and MSP23 within 24 h, and the induction was dependent on the degree of LDL oxidation. The induction of HO-1 and MSP23 may thus play an important cytoprotective role against oxidative stress in atherogenesis.

Animals↗