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Biomedical subjects

M Matsuo

Publications and source records attributed to M Matsuo.

At least 199 records · Page 11Linked to original sources
PubMed1997

Purification and characterization of a flavohemoglobin from the denitrifying fungus Fusarium oxysporum.

A flavohemoprotein was purified to homogeneity from the denitrifying fungus Fusarium oxysporum. The purified protein existed as a monomer with a molecular weight of 44 kDa. It was purified in an oxidized form and exhibited the absorption maxima at 401, 540 and 643 nm in its resting form, and at 434 and 555 nm upon reduction with dithionite, respectively. The protein contained 0.5 mol protoheme/mol and 1.1 mol FAD/mol, respectively. When the resting flavohemoprotein was aerobically incubated with NAD(P)H, it was converted to a spectral species that is spectrally very similar to oxyhemoglobins. These properties are characteristics of flavohemoglobins (FHb) of Alcaligenes eutrophus, Escherichia coli, and baker's yeast. Further the amino terminal amino acid sequence of the protein of F. oxysporum was similar to those of these FHbs. These results suggest that the isolated flavohemoprotein of F. oxysporum would be a counterpart of the proteins in the FHb family.

Amino Acid Sequence↗
PubMed1997

Biosynthesis of archaeosine, a novel derivative of 7-deazaguanosine specific to archaeal tRNA, proceeds via a pathway involving base replacement on the tRNA polynucleotide chain.

Archaeosine is a novel derivative of 7-deazaguanosine found in transfer RNAs of most organisms exclusively in the archaeal phylogenetic lineage and is present in the D-loop at position 15. We show that this modification is formed by a posttranscriptional base replacement reaction, catalyzed by a new tRNA-guanine transglycosylase (TGT), which has been isolated from Haloferax volcanii and purified nearly to homogeneity. The molecular weight of the enzyme was estimated to be 78 kDa by SDS-gel electrophoresis. The enzyme can insert free 7-cyano-7-deazaguanine (preQ0 base) in vitro at position 15 of an H. volcanii tRNA T7 transcript, replacing the guanine originally located at that position without breakage of the phosphodiester backbone. Since archaeosine base and 7-aminomethyl-7-deazaguanine (preQ1 base) were not incorporated into tRNA by this enzyme, preQ0 base appears to be the actual substrate for the TGT of H. volcanii, a conclusion supported by characterization of preQ0 base in an acid-soluble extract of H. volcanii cells. Thus, this novel TGT in H. volcanii is a key enzyme for the biosynthetic pathway leading to archaeosine in archaeal tRNAs.

Amino Acid Sequence↗
PubMed1997

Characterization of the genomic structure and promoter of the mouse NAD+-dependent 15-hydroxyprostaglandin dehydrogenase gene.

The mouse NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) gene and its 5'-flanking region was cloned from a 129 mouse ES bacteriophage P1 genomic library. The gene contains 7 exons and 6 introns and is 11.3 kb in length. The transcription initiation site was mapped at 35 bases upstream from the ATG start codon. The nucleotide sequence of the 1.6 kb promoter region contains two TATA boxes and a number of potential regulatory elements including Sp1, CRE, GRE, AP1, AP2, NF-IL6 and estrogen receptor binding site. Studies of the promoter's activity showed that the first 400 nucleotides of 5'-flanking region efficiently drove the transcription of the luciferase reporter gene in U936 cells upon stimulation with a phorbol ester.

Animals↗
PubMed1997

Oxidative injury of synapse and alteration of antioxidative defense systems in rats, and its prevention by vitamin E.

In order to define whether active oxygen species actually induce oxidative damage to the nervous system, and how antioxidative defense systems are changed by oxidative stress, morphological and functional changes in the nervous system and antioxidant status were investigated. When rats were exposed to 100% oxygen in a chamber, many morphological changes, e.g. swollen astrocytes around vessels, deformed nuclei in nerve cells, pigmentation, swollen mitochondria, and abnormal accumulation of synaptic vesicles in swollen nerve terminals, were observed by electron microscopy. When synaptosomes isolated from oxygen-exposed rats were stimulated by KCl, acetylcholine release from the terminal was decreased more significantly than in synaptosomes from unexposed rats (P < 0.01). Synaptic plasma membrane fluidity decreased in response to oxygen exposure, and plasma membrane permeability to sucrose was increased significantly (P < 0.05). The cholesterol/phospholipid ratio of the plasma membranes was increased by oxidative stress and the content of unsaturated fatty acids, especially arachidonic acid and docosahexaenoic acid, decreased. The levels of thiobarbituric-acid-reactive substances in the plasma membranes of oxygen-exposed rats were significantly higher than in unexposed rats (P < 0.01). These results suggest that free radicals derived from oxygen may attack nerve terminals and peroxidize the plasma membrane. It was found that in response to the oxidative stress, the status of the defense system in synapse, i.e. the concentration of vitamin E, activities of superoxide dismutase and glutathione peroxidase changed, and that many of the changes observed were reduced remarkably by the intraperitoneal administration of vitamin E prior to stress. Data support the idea that vitamin E contributes to the protection against nerve dysfunction caused by oxidative stress.

Acetylcholine↗
PubMed1997

Cloning and expression of the cDNA for rat NAD+-dependent 15-hydroxyprostaglandin dehydrogenase.

The cDNA for rat NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) was cloned from an intestinal cDNA library. The sequence of this cDNA was found to be identical to that of the reverse transcription-polymerase chain reaction (RT-PCR) product obtained using rat lung RNA as a template. The cDNA contains a 798-bp open reading frame that codes for a protein of 266 amino acids (M(r) 28,775) which shares 88.7% identity with the human 15-PGDH and 92.1% identity with the mouse 15-PGDH protein. The regions that are believed to be the NAD+ binding domain and the active site are conserved in the enzymes from the three different species. However, the sequence of the C-terminal 9 amino acids appears to be significantly different. The authenticity of the rat cDNA was confirmed by the expression of an enzymatically active 15-PGDH in E. coli.

Amino Acid Sequence↗
PubMed1997

Hunter disease in a girl caused by R468Q mutation in the iduronate-2-sulfatase gene and skewed inactivation of the X chromosome carrying the normal allele.

Hunter disease is an X-linked recessive mucopolysaccharide storage disorder caused by iduronate-2-sulfatase deficiency and is rare in females. We describe here findings in a girl with Hunter disease of the severe type. She had a normal karyotype but a marked deficiency of iduronate-2-sulfatase activity in lymphocytes and cultured fibroblasts. In a sequence analysis of the iduronate-2-sulfatase gene, evidence was obtained for the R468Q (G1403 to A) mutation, a common one in Hunter disease. RT-PCR showed her cDNA to represent only the R468Q allele, although at the genomic level she was a heterozygote with one normal allele. Her brother had the R468Q mutation, and their mother was a carrier of this mutation. The fusion products of CHO (TG(R),Neo(R)) with patient's fibroblasts cultured in HAT/G418 selective medium, carried only the maternal allele. However, in genomic DNA from the patient's fibroblasts, only the paternal allele of the androgen receptor gene, a gene subjected to differential methylation of the inactive X-chromosome, was methylated. These findings strongly suggest that the severe form of Hunter disease in this girl was the result of selective expression of the maternal allele carrying the missense mutation R468Q, which in turn resulted from skewed X inactivation of the paternal nonmutant X chromosome.

Alleles↗
PubMed1997

Screening the p53 status of human cell lines using a yeast functional assay.

We have screened the p53 status of 156 human cell lines, including 142 tumor cell lines from 27 different tumor types and 14 cell lines from normal tissues by using functional analysis of separated alleles in yeast. This assay enables us to score wild-type p53 expression on the basis of the ability of expressed p53 to transactivate the reporter gene HIS3 via the p53-responsive GAL1 promotor in Saccharomyces cerevisiae. Of 142 tumor cell lines, at least 104 lines (73.2%) were found to express the mutated p53 gene: 94 lines (66.2%) were mutated in both alleles, three lines (2.1%) were heterozygous, and no p53 cDNA was amplified from seven lines (4.9%). Of the 14 cell lines originating from normal tissues, all the transformed or immortalized cell lines expressed mutant p53 only. Yeast cells expressing mutant p53 derived from 94 cell lines were analyzed for temperature-sensitive growth. p53 cDNA from eight cell lines showed p53-dependent temperature-sensitive growth, growing at 30 degrees C but not at 37 degrees C. Four temperature-sensitive p53 mutations were isolated: CAT-->CGT at codon 214 (H214R), TAC-->TGC at codon 234 (Y234C), GTG-->ATG at codon 272 (V272M), and GAG-->AAG (E285K). Functionally wild-type p53 was detected in 38 tumor cell lines (26.8%) and all of the diploid fibroblasts at early and late population doubling levels. These results strongly support the previous findings that p53 inactivation is one of the most frequent genetic events that occurs during carcinogenesis and immortalization.

Alleles↗
PubMed1997

Deletion of twenty seven nucleotides within exon 11 of the band 3 gene identified in ovalocytosis in Lombok Island, Indonesia.

This study reports the molecular characterization of ovalocytosis in Lombok Island, Indonesia. The analysis of genomic DNA by polymerase chain reaction shows that all 21 ovalocytotic individuals have two amplified products of different size from a region encompassing exon 11 of the band 3 gene. The sequence of the larger product matched perfectly with that of normal individuals. In the sequence of the smaller product, 27 nucleotides within exon 11 were deleted. The heterozygous presence of the deletion identified in other parts of Southeast Asia was confirmed in patients with ovalocytosis in an isolated island of eastern Indonesia.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1997

A comprehensive method to scan for point mutations of the glucose 6 phosphate dehydrogenase gene.

We have developed a fast and comprehensive method to scan for point mutations in a gene on X chromosome. A target region of the gene is first amplified. Then, using the amplified product as a template, PCR is carried out with multiple short-length forward primers arrayed in tandem in the scanned region, and a common reverse primer. The absence of amplified product defines the site of a mutation within a narrow region of the primer recognition site. To evaluate our method, point mutations in exon 12 of the human glucose-6-phosphate dehydrogenase (G6PD) gene were used as a model system. Out of 12 Singaporean G6PD-deficient patients, 6 cases were shown by the method to have a nucleotide change in this exon. Sequence analysis confirmed the presence of a nucleotide change in the region identified by our scanning. Thus, our method is accurate in localizing mutations within a narrow region, and allows large numbers of samples to be handled simultaneously.

Chromosomes, Human, X↗
PubMed1997

The common marmoset (Callithrix jacchus) as a model for neuroleptic-induced acute dystonia.

To examine whether acute dystonia is induced by neuroleptic treatment, common marmosets were treated with haloperidol orally twice a week over 25 weeks until dystonic behavior was elicited. Movement disorders such as acute dystonia were observed 6 weeks after the initial treatment, and had appeared in all treated animals by 25 weeks. Once these movement disorders were induced, they consistently reappeared after further treatment with haloperidol, and once haloperidol dosing was discontinued, the episodes vanished. Then, various neuroleptic drugs (bromperidol, chlorpromazine, risperidone thioridazine, sulpiride, tiapride, and clozapine) or a nonneuroleptic drug (diazepam) were administered orally instead of haloperidol in the above animals. All the neuroleptic drugs except for clozapine elicited similar abnormal behavior, while diazepam failed to induce any dystonia. An anticholinergic drug, trihexyphenidyl, which is known to reduce acute dystonia in patients, was also given orally to the above haloperidol-sensitized animals, followed by further treatment with haloperidol 30 min later. This clearly suppressed the induction of dystonia by haloperidol. The similarity between these findings for haloperidol-pretreated common marmosets and clinical findings suggests that the present model is useful for predicting the potential of antipsychotics to induce acute dystonia in humans.

Acute Disease↗
PubMed1997

Retarding effect of dietary restriction on the accumulation of 8-hydroxy-2'-deoxyguanosine in organs of Fischer 344 rats during aging.

An age-related accumulation in rats of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, and the effect of dietary restriction on the accumulation of 8-OHdG were examined. The 8-OHdG concentrations of nuclear DNA in organs of ad libitum fed rats were similar in young and middle age, but increased significantly in kidney at 24 months of age, in heart and liver at 27 months of age, and in brain at 30 months of age. The 8-OHdG concentration in dietary-restricted rats showed no changes in any organ up to 30 months of age and then was increased at 33 months of age. Dietary restriction retarded the onset of the age-related increase in 8-OHdG concentration, although it did not reduce the concentration in young and middle age. These results suggest that the effect of dietary restriction on the extension of life-span in rats might be related to a reduction in oxidative damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

High-performance liquid chromatographic assay of arachidonic acid metabolites from cultured rat glial cells.

Although various methods can be used for detection of arachidonic acid (AA) metabolites, only few of them allow rapid and precise analysis of both cyclooxygenase and lipoxygenase metabolites in a single assay. We have developed a simple and rapid method to evaluate overall profiles of AA metabolites produced by primary cultured glial cells from newborn rats by using reversed-phase, high-performance liquid chromatography (RP-HPLC) and on-line radioisotope detection.

Animals↗
PubMed1997

Ascorbic acid and reducing agents regulate the fates and functions of S-nitrosothiols.

Although S-nitrosoglutathione (GS-NO) and other S-nitrosothiols (RS-NO) exhibit activity attributable to nitric oxide (NO), the dynamic aspects of their metabolism remain to be elucidated. To determine the fates and functions of RS-NO, the stability of GS-NO was analyzed in plasma, and various fractions of liver and kidney. GS-NO was fairly stable under physiological conditions in plasma and buffer solutions. However, GS-NO was rapidly decomposed in the presence of either homogenates of rat liver and kidney or their supernatant fractions. The ability of the supernatants to decompose GS-NO remained unchanged after the removal of proteins and large molecular weight compounds. Physiological levels of reducing agents, such as reduced glutathione (GSH), ascorbic acid (AsA), and cysteine, also enhanced the decomposition of RS-NO; the order of their potency was AsA > cysteine >GSH. Considering their intra-cellular concentrations and potency, AsA might principally be responsible for the enhanced decomposition of GS-NO. NO, GS-NO, and related RS-NO inhibited the respiration of Ehrlich ascites tumor cells. The inhibitory effect of GS-NO was enhanced by the reducing agents (cysteine>AsA>GSH). Intravenously administered GS-NO exhibited a depressor action through some ascorbic acid enhancable mechanism. Thus, the metabolism and biological function of GS-NO and related RS-NO might be affected by AsA and other reducing agents.

Animals↗
PubMed1997

Early onset of immunological heparin-induced thrombocytopenia in acute myocardial infarction.

We studied five patients who developed a decrease in platelet count of more than 30000 x 10(6)/l within 24 h of heparin treatment and direct percutaneous transluminal coronary angioplasty and/or intracoronary thrombolytic therapy among 38 consecutive patients with acute myocardial infarction (AMI). Anti-platelet factor 4 (PF4)-heparin complex antibodies were detected in the sera of these five patients, although they had never previously been exposed to heparin. These patients might have had specific antibodies before heparin treatment. PF4 might be released from activated platelets and bind to endogenous heparin-like molecules, and antibodies with cross-reactivity to the PF4-heparin complex may have been generated by the endogenous complex before the first heparin treatment. We conclude that it is worthwhile to check the platelet count and screen for anti-PF4-heparin complex antibody in advance to prevent thrombotic complications due to heparin treatment in patients with AMI.

Acute Disease↗
PubMed1997

Factor VII R353Q polymorphism and lacunar stroke in Japanese hypertensive patients and normotensive controls.

Elevated plasma factor VII (FVII) levels are reported to be associated with cardiovascular disease in both Caucasians and Japanese. Recent reports indicate that individuals with the FVII 353Q allele have decreased plasma FVII levels. Thus, we investigated the association between lacunar stroke and the FVII R353Q polymorphism in 137 hypertensive patients with silent or overt lacunar stroke (stroke group), 83 non-stroke hypertensives without any lacunae detected by magnetic resonance imaging (non-stroke group), and 97 normotensive control subjects matched for age, sex, and smoking status recruited at an annual health examination (normotensive control group). The frequency of the FVII 353Q allele was 0.057 in the normotensive control group, 0.051 in the non-stroke group and 0.061 in the stroke group. These frequencies, as well as genotype distribution, were not significantly different from each other, even when we subclassified the ischemic group into silent (n = 54) and clinically overt (n = 64) lacunar stroke subgroups. These results suggest that the FVII 353Q allele is not an important genetic determinant for cerebrovascular disease in Japanese individuals.

Adult↗