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K Hiramoto

Publications and source records attributed to K Hiramoto.

At least 19 recordsLinked to original sources
PubMed1992

Unique karyotypes in two patients with Prader-Willi syndrome.

A physical disruption of the Prader-Willi syndrome (PWS) chromosome region is thought to cause PWS. We describe 2 girls with PWS phenotype, who had unique chromosome 15 abnormalities. The first patient showed mosaicism: 45,XX,t(15;15)(qter----p11.1::q11.200----qter)/46,XX,t(15;15)(qter----p1 1.1::q 11.200----qter), +mar. The band 15q11.2 apparently remained intact in the t(15;15) chromosome, and the mar chromosome was considered as r(15) (p11.1q11.1). The second patient had a karyotype of 47,XX,del(15)(q11.200----q11.207), +idic (15)(pter----q11.1::q11.1----pter). The complex breakage and reunion involving the 15q11.2 regions of the father's homologous chromosomes 15 at meiosis appeared to have resulted in the idic(15) and the del(15) chromosomes. These cytogenetic findings suggest that the PWS chromosome region may be localized on the very proximal portion of band 15q11.2.

Child↗
PubMed1992

DNA strand breakage by hydroxyphenyl radicals generated from mutagenic diazoquinone compounds.

The mutagenic diazoquinone compounds p-diazoquinone (p-DQ), o-diazoquinone (o-DQ) and 3-diazo-N-nitrosobamethan (D-BM) cleaved the phosphodiester bond of lambda DNA, phi X174 RFI DNA and M13mp8ss DNA. p-DQ also cleaved the phosphodiester bond of bis(p-nitrophenyl)phosphate. The breakage of the phosphodiester bond was inhibited by the antioxidant butyl hydroxyanisole (BHA), ethanol, the spin trapping agent DMPO, cysteine and 2-mercaptoethanol. While incubation of p-DQ and o-DQ alone gave p-hydroquinone and catechol, respectively, incubation of these compounds in the presence of BHA and ethanol gave phenol in large yields. Incubation of p-DQ and o-DQ with the spin trapping agents DMPO and PBN gave spin adducts assignable as p- and o-hydroxyphenyl adducts, respectively. The breakage of the phosphodiester bond of DNA by the diazoquinone compounds is suggested to be due to the hydroxyphenyl radicals generated during incubation.

Bacteriophages↗
PubMed1991

Changes in ovalbumin and protein synthesis in vivo in the magnum of laying hens during the egg formation cycle.

1. The present study was carried out to investigate whether or not the rate of synthesis of total protein in various oviducal segments and ovalbumin, a major egg white protein, in the magnum fluctuated during the egg formation cycle in laying hens. 2. Synthesis of total protein and ovalbumin was measured in vivo by the incorporation of [15N]methionine after a primed continuous infusion of tracer for 3 hr. 3. Protein and ovalbumin contents in the magnum and the entire oviduct decreased sharply when an ovum moved down from the magnum to the isthmus, probably due to the secretion of egg white proteins. 4. In contrast, total protein and ovalbumin synthesis in the magnum was significantly higher when an ovum was in there than when it was in any other segments. Fluctuations of ovalbumin synthesis and total protein synthesis in the magnum were roughly parallel to those of total protein synthesis in the entire oviduct. 5. It was concluded, therefore, that the changes seen in total protein synthesis in the whole oviduct during the egg formation cycle were mainly attributable to those in magnum protein synthesis, of which a significant portion was accounted for by the synthesis of ovalbumin.

Animals↗
PubMed1990

Loss of the 3p25.3 band is critical in the manifestation of del(3p) syndrome: karyotype-phenotype correlation in cases with deficiency of the distal portion of the short arm of chromosome 3.

Two patients with monosomy for the distal portion of the short arm of chromosome 3 are described. Chromosome analysis on prometaphase cells demonstrated a karyotype of 46,XX,del(3) (p25.3) in one patient and 46,XX,r(3)(p26.1q29) in the other. The former patient showed characteristic clinical manifestations of the 3p- syndrome, including growth failure, mental retardation, microcephaly with a flat occiput, triangular face, synophrys, blepharoptosis, hypertelorism, broad and flat nose, long philtrum, down-turned mouth, micrognathia, apparently lowset and malformed ears, fingers abnormalities, and deafness. The latter patient had a nonspecific phenotype with mental retardation, growth failure and microcephaly. Karyotype-phenotype comparisons in the present cases and 16 previously reported cases with deficiency of the distal portion of 3p suggests that deficiency of the 3p25.3 band is critical to produce the main clinical manifestations of the del(3p) syndrome.

Chromosome Deletion↗
PubMed1990

Synchronization culture of amniotic fluid cells using excess thymidine block followed by deoxycytidine release and its application to high-resolution banding analysis of chromosomes.

We describe a simple synchronization culture technique of amniotic fluid (AF) cells to yield many earlier mitotic divisions with extended chromosomes. AF cell samples obtained by amniocentesis were cultured in the usual manner. Thirty hours after the first subculture, they were exposed to excess thymidine (0.5 mM). This cell cycle block was released by adding deoxycytidine (10 microM) 18 hr after synchronization. At exactly 7.5 hr after the release, the cultures were treated with Colcemid (0.02 microgram/ml) for 20 min then harvested. The mitotic index and the ratio of cells in the earlier mitotic stages were much higher in the synchronized cultures than in the control cultures. The same favorable effects were obtained also in AF cell cultures by combining this technique with ethidium bromide or actinomycin D treatment. The technique was less toxic to the cells, and was simple and reproducible. It was successfully applied to prenatal cytogenetic diagnosis of 2 families with a subtle inherited chromosome abnormality, so it is recommended for high-resolution banding analysis of AF cells and possibly chorionic villus samples.

Amniotic Fluid↗
PubMed1990

Strain differences in whole-body protein turnover in the chicken embryo.

1. Whether or not there is a strain difference in embryonic whole-body protein turnover rates was tested using the chicken embryos of Rhode Island Red carrying a sex-linked dwarf gene (dwarf), White Leghorn (layer), and White Cornish X White Plymouth Rock (broiler) strains on day 12 of incubation. 2. Whole-body protein synthesis was estimated by injecting L-[15N]-phenylalanine either intraperitoneally or intravenously on day 12 of incubation in order to investigate the effect of the route of isotope administration. The results showed that the values for fractional and absolute synthesis rates were approximately 13% higher by intravenous injection than by intraperitoneal injection. 3. Whole-body protein turnover, both in terms of fractional and absolute rates, was significantly faster in dwarf than in broiler embryos, with intermediate values in layer embryos, although no growth differences were observed on day 12. 4. Difference in egg weight, measured before incubation, did not affect protein turnover. 5. It was concluded that the strain difference manifested in whole-body protein turnover of the chicken embryo would probably be a reflection of differences in genetic background.

Animals↗
PubMed1990

Importance of albumen content in whole-body protein synthesis of the chicken embryo during incubation.

The importance of egg albumen content in whole-body protein synthesis was investigated in developing chicken embryos by using lines genetically selected for high and low albumen contents and by removing albumen from eggs before incubation. 2. Whole-body protein synthesis was estimated by injecting L-[15N]-phenylalanine intravenously on day 12 of incubation. 3. Embryos from high albumen eggs had higher whole-body protein synthesis rates than those from low albumen eggs. 4. Whole-body protein synthesis was reduced by the removal of albumen from eggs before incubation. 5. It was concluded that albumen content per se was of crucial importance in regulating whole-body protein synthesis in chicken embryos during incubation.

Animals↗
PubMed1990

Effect of methionine and lysine deficiencies on protein synthesis in the liver and oviduct and in the whole body of laying hens.

For laying hens, protein synthesis in the liver, in the oviduct (magnum and remaining portions), and in the whole body was measured in vivo in order to investigate the effect of a dietary deficiency of methionine or lysine. The rate of protein synthesis in tissues was calculated from the incorporation of L-[15N]phenylalanine into the protein fraction; whole-body protein synthesis was estimated from the plateau enrichment of free [15N]phenylalanine in plasma. The enrichment of labeled phenylalanine was analyzed by using a gas-chromatograph mass spectrometer, following a primed infusion of the isotope for 6 h. The whole-body protein synthesis of laying hens fed diets deficient in amino acids was significantly lower than that of control hens. Protein synthesis in the liver, magnum, and remainder of the oviduct was decreased by a dietary deficiency of the amino acids studied with larger rates of decrease than for the whole-body analysis. The proportion of reduction in protein synthesis resulting from the sum of the tissues studied, compared with that of the whole body, was 36 and 50%, respectively, for a deficiency of methionine and lysine.

Animals↗
PubMed1990

Protein synthesis in tissues and in the whole body of laying hens during egg formation.

The present study was conducted to investigate whether or not protein synthesis in tissues and in the whole body of laying hens would be affected by the position of an ovum passing along the oviduct during egg formation. Protein synthesis in tissues was measured in vivo by a primed-continuous infusion of [15N]methionine for 3 h, finishing at the time when an ovum would have stayed at one of the segments within the oviduct, i.e., infundibulum, magnum, isthmus, uterus, or vagina. The dissection of the entire oviduct immediately after the isotope infusion confirmed whether or not the ovum was in the expected position. Whole-body protein synthesis, estimated from plateau enrichment of free [15N]methionine in plasma at the end of the infusion, was not significantly affected by the position of an ovum along the various segments of the oviduct. The highest values were observed in the entire oviduct when an ovum was in the magnum portion, both for protein synthesis and protein synthesis per unit of RNA. Protein synthesis per unit of RNA in the sum of tissues other than the liver and oviduct was highest when an ovum was in the isthmus. The synthesis of liver protein was relatively constant and was not significantly affected by the position of the ovum passing along the oviduct.

Animals↗
PubMed1988

Superoxide dismutase-mediated reversible conversion of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole, the N-hydroxy derivative of Trp-P-2, into its nitroso derivative.

Aerobic oxidation of 3-hydroxyamino-1-methyl-5H-pyrido-[4,3-b]indole [Trp-P-2(NHOH)] in neutral aqueous solution was greatly accelerated by copper-zinc superoxide dismutase (SOD). The major product in this SOD-mediated reaction was identified as 3-nitroso-1-methyl-5H-pyrido[4,3-b]indole [Trp-P-2(NO)]. This conversion was accompanied by a decrease of the mutagenicity of the mixture, as monitored by the direct-acting mutagenicity on Salmonella typhimurium TA98; a rapid change to approximately 1/3 of the original mutagenicity was followed by no further decrease of the activity. In contrast, in the spontaneous aerobic oxidation of Trp-P-2-(NHOH), the mutagenicity slowly and continuously decreased, until it was finally lost almost completely. Similar acceleration by SOD of aerobic oxidation was found for 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole [Glu-P-1(NHOH)]. Again, mutagenicity of approximately 1/4 that of the original was retained in the SOD-mediated decomposition, while a complete loss of the mutagenicity was observed in the spontaneous decomposition. When Trp-P-2(NO) was treated with the superoxide-generating system, xanthine oxidase plus xanthine, Trp-P-2(NHOH) was formed. Therefore, the role of SOD in the conversion of Trp-P-2(NHOH) into Trp-P-2(NO) is the removal of superoxide anions generated by reduction of aerobic oxygen, thereby inhibiting the reverse reactions, i.e. the reduction of Trp-P-2(NO) and that of the putative intermediate nitroxide radical. In support of this proposed mechanism, phenylhydroxylamine underwent a SOD-accelerated conversion to nitrosobenzene, and nitrosobenzene was reduced to phenylhydroxylamine by the action of the xanthine oxidase-xanthine system. Hence, this reversible interchange between an arylhydroxylamine and its nitroso compound, coupled with the oxygen-superoxide cycle, may be a general phenomenon. A consequence of this finding is that the xenobiotic N-hydroxylamines may be converted by the action of SOD in the biological settings into nitroso compounds, which are chemically more stable, serving as a reservoir for mutagenicity.

Carbolines↗
PubMed1988

Generation of intracellular active oxygens in mouse FM3A cells by 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole, the activated Trp-P-2.

Mouse FM3A cells in culture were treated with a reactive metabolite of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2-(NHOH]. When the treated cells, which were judged as viable on the basis of trypan-blue exclusion, were subjected to nitroblue tetrazolium staining, formazan was formed inside the cells, a fact suggesting the intracellular presence of superoxide. No formazan formation was detected on treatment of the cells with Trp-P-2. Single-strand breaks in the cellular DNA took place during this treatment with Trp-P-2(NHOH). Since Trp-P-2(NHOH) in solution generates superoxide anion accompanying its oxidative degradation, we conclude that the Trp-P-2(NHOH) treatment produces intracellular active oxygens that can damage DNA.

Animals↗
PubMed1987

Inhibitory effect of myoglobin and hemoglobin on the direct-acting mutagenicity of protein pyrolysate heterocyclic amine derivatives.

We have shown in our earlier reports (Arimoto et al., 1980a, b) that hemin and some other porphyrins can inhibit the mutagenicity in Salmonella of heterocyclic amines derived from cooking of proteins. A direct interaction between hemin and the mutagens was implicated on the basis of the observation that some of the mutagens were inactivated when they had been metabolically converted into direct-acting mutagens before the treatment with hemin. Hemin is a bound constituent of various proteins including hemoglobin and myoglobin, which are abundantly present in the blood and muscles, respectively. An interesting question is whether or not hemoglobin and myoglobin can inhibit the activities of the mutagenic heterocyclic amines.

Amines↗