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T Oura

Publications and source records attributed to T Oura.

At least 37 records · Page 2Linked to original sources
PubMed1992

[DNA diagnosis for inherited metabolic disorders].

Progress in molecular genetics has made it possible to detect the structure of cDNA and genomic DNA of enzyme and protein, as well as the mutation in DNA level. It also provides a vast amount of new information for diagnosis and treatment, and it can actually be used in prenatal diagnosis and carrier screening. There is great hope that patients with genetic disorders can be treated by somatic gene replacement. We introduced here the methods for detection of unknown mutations of inherited metabolic disorders, and screening patients for characterized mutations, and the expression analysis of mutant cDNA, as an example of phenylketonuria.

Amino Acid Metabolism, Inborn Errors↗
PubMed1991

Founder effect of a prevalent phenylketonuria mutation in the Oriental population.

A missense mutation has been identified in the human phenylalanine hydroxylase [PAH; phenylalanine 4-monooxygenase; L-phenylalanine, tetrahydrobiopterin:oxygen oxidoreductase (4-hydroxylating), EC 1.14.16.1] gene in a Chinese patient with classic phenylketonuria (PKU). A G-to-C transition at the second base of codon 413 in exon 12 of the gene results in the substitution of Pro413 for Arg413 in the mutant protein. This mutation (R413P) results in negligible enzymatic activity when expressed in heterologous mammalian cells and is compatible with a classic PKU phenotype in the patient. Population genetic studies reveal that this mutation is tightly linked to restriction fragment length polymorphism haplotype 4, which is the predominant haplotype of the PAH locus in the Oriental population. It accounts for 13.8% of northern Chinese and 27% of Japanese PKU alleles, but it is rare in southern Chinese (2.2%) and is absent in the Caucasian population. The data demonstrate unambiguously that the mutation occurred after racial divergence of Orientals and Caucasians and suggest that the allele has spread throughout the Orient by a founder effect. Previous protein polymorphism studies in eastern Asia have led to the hypothesis that "northern Mongoloids" represented a founding population in Asia. Our results are compatible with this hypothesis in that the PKU mutation might have occurred in northern Mongoloids and subsequently spread to the Chinese and Japanese populations.

Asian People↗
PubMed1991

[Prenatal diagnosis of carbamyl phosphate synthetase deficiency by fetal liver biopsy].

Carbamyl phosphate synthetase deficiency (CPSD) is one of the enzyme defects of the urea cycle and inherited as an autosomal recessive. A definitive enzymatic diagnosis of CPSD can be made by biochemical assay of liver biopsy material, but not of cultured fibroblasts. In pregnancy at risk for CPSD, prenatal diagnosis was attempted by fetal liver biopsy, performed at 22 weeks of gestation. CPS activity was present and a healthy baby was delivered at term. The technique employed for fetal liver biopsy is described together with an evaluation of its possible role in prenatal diagnosis.

Amino Acid Metabolism, Inborn Errors↗
PubMed1989

Polymorphic DNA haplotypes at the phenylalanine hydroxylase (PAH) locus in Asian families with phenylketonuria (PKU).

DNA polymorphisms at the phenylalanine hydroxylase (PAH) locus have proved highly effective in linkage diagnosis of phenylketonuria (PKU) in Caucasian families. More than 10 RFLP sites have been reported within the PAH structural locus in Caucasians. With information from affected and unaffected offspring in PKU families it is often possible to reconstruct complete RFLP haplotypes in parents and to use these haplotypes to follow the segregation of PKU within families and to determine the distribution of PKU chromosomes within populations. To establish the utility of these RFLPs in characterizing Asian families with PKU, we typed eight DNA sites in 21 Chinese families and 12 Japanese families with classical PKU. The eight RFLPs were chosen for their informativeness in Caucasians. From these families we reconstructed a total of 91 complete PAH haplotypes, 44 from non-PKU chromosomes and 47 from PKU-bearing chromosomes. Although all eight marker sites are polymorphic in both Chinese and Japanese, there is much less haplotypic variation in Asians than in Caucasians. In particular, one haplotype alone, haplotype 4, accounts for more than 77% of non-PKU chromosomes and for more than 80% of PKU-bearing chromosomes. Haplotype 4 is also relatively common in Caucasians. The next most common Asian haplotype is 10 times less frequent than haplotype 4. By contrast, in many Caucasian populations the sum of the frequencies of the five most common haplotypes is still less than 80%, and several of the most common haplotypes are equally frequent. Even though the extent of haplotypic variation in Asians is severely limited, the few haplotypes that are found often differ at a number of RFLP sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1988

[Phenylketonuria].

Explore the source record for details and available documents.

Base Sequence↗
PubMed1987

Treatment of phenylketonuria with a formula consisting of low-phenylalanine peptide. A collaborative study.

A method of preparation of a more palatable therapeutic formula for phenylketonuria (PKU), consisting of low-phenylalanine peptide (LPP), was reported. There were no adverse effects and, in fact, there was a reduced frequency of diarrhea in patients who received LPP formula for more than 6 months. The LPP formula can be used not only as a more palatable therapeutic milk for PKU, but also as an ingredient to make more palatable foods of low-phenylalanine content.

Adolescent↗
PubMed1986

Effects of phenylalanine loading on protein synthesis in the fetal heart and brain of rat: an experimental approach to maternal phenylketonuria.

Pregnant rats were loaded with L-phenylalanine, and the distributions of [14C]leucine and [14C]urea into fetal plasma and tissues were examined. Uptake of [14C]leucine into the supernatant and protein fractions of fetal plasma and tissues was low in the rats loaded with phenylalanine. In contrast, [14C]urea was distributed identically in both groups, indicating that maternal hyperphenylalaninemia did not affect blood flow across the placenta. Administration of phenylalanine and p-chlorophenylalanine produced amino acid imbalance in fetal tissues. Along with these changes, polysomes of the affected fetal heart and brain disaggregated without changes in the ribonuclease activity. These results indicate that high phenylalanine levels in maternal plasma disturb the active transport of amino acids across the placenta, causing an amino acid imbalance and disaggregation of polysomes in fetal heart and brain. These changes may contribute to the congenital heart disease and mental retardation of maternal phenylketonuria.

Animals↗
PubMed1985

Zinc status of untreated histidinemic children.

In order to study zinc status in histidinemia, serum and hair zinc concentrations were measured in 40 untreated children with histidinemia (age 2 months-5 years). In 20 children (greater than 2 years of age) zinc content and carbonic anhydrase activity of erythrocytes and urinary excretion of zinc were also studied. The amount of zinc excreted was elevated in histidinemic children and showed a positive correlation with the urinary histidine concentration (gamma = 0.57, p less than 0.005). The means of serum zinc concentration, erythrocyte zinc concentration, and erythrocyte carbonic anhydrase activity were all similar in the histidinemic and the control children. Hair zinc concentration of histidinemic children was compared with that of controls of five different age groups: less than 5 months, 5-18 months, 18 months-2 years, 2-4 years, and 4-5 years. In all of these age groups, hair zinc content was similar. The incidence of low-hair-zinc level (less than 80 micrograms/g) in histidinemic children greater than 5 months of age (9 of 34) was significantly higher than in controls (18 of 180, p less than 0.05). The observation suggested the possibility that untreated histidinemia may cause chronic mild zinc deficiency in some histidinemic children.

Ammonia-Lyases↗
PubMed1984

Follow-up study of a nation-wide neonatal metabolic screening program in Japan. A collaborative study group of neonatal screening for inborn errors of metabolism in Japan.

A nationwide neonatal screening program for phenylketonuria (PKU), maple syrup urine disease (MSUD), homocystinuria, histidinemia and galactosemia was started in Japan in 1977. The total number of infants screened had reached 6,311,754 by March, 1982. A follow-up study revealed the incidence of the disease in Japan: 1/108,823 for PKU; 1/450,840 for hyperphenylalaninemia (HPA); 1/1,577,939 for biopterin deficiency; 1/525,980 for MSUD; 1/1,051,959 for homocystinuria; 1/8,371 for histidinemia, and 1/788,969 for galactosemia type 1. The incidences of PKU, HPA, homocystinuria, and galactosemia (type 1) were found to be markedly low in Japan as compared with those in Caucasian countries. There was no great difference in the incidence of MSUD between both. On the other hand, the incidence of histidinemia was higher in Japan. It was found that most of the patients with PKU, HPA, MSUD, homocystinuria, or galactosemia are developing normally due to the early initiation of dietary treatment. These results clearly indicate that the neonatal mass screening program plays a great role in preventing the occurrence of handicapped children.

Biopterins↗
PubMed1984

Semiautomated enzyme immunoassay of thyrotropin as a mass screening test for neonatal hypothyroidism.

A sensitive, simple, and rapid semiautomated sandwich enzyme immunoassay (EIA) was developed for measuring thyrotropin in dried blood samples on filter paper for use in screening for neonatal hypothyroidism. Good correlation was found between values for thyrotropin determined by this method and those determined by radioimmunoassay (RIA) (r=0.94). In pilot tests on 17,160 newborn infants in the general population, five cases of primary hypothyroidism were detected by both EIA and RIA. The recall rate was slightly highter in EIA than in RIA.

Autoanalysis↗
PubMed1983

IgG heavy-chain (Gm) allotypes and HLA-antigens in insulin-dependent diabetes mellitus in Korea.

Eighty-eight patients with insulin-dependent diabetes mellitus (IDDM) and seventy-two unrelated normal controls in Korea were studied for Gm allotypes and HLA-antigens. Ten Gm phenotypes were found among the Korean population. The phenotype frequencies of Gm axg (1,2,21), Gm ag (1,21), Gm agb0b3b5st (1,21, 11,13,10,15,16) and Gm agfb0b1b3b4b5 (1,21,3,11,5,13,14,10) were higher than the other Gm allotypes, but there was no significant difference between patients and controls. HLA-BW54 was found in 15% of patients who had any of those Gm allotypes (Gm axg, Gm agb0b3b5st, Gm ab0b3b5st). However there was no significant difference in frequency as compared with controls.

Diabetes Mellitus, Type 1↗
PubMed1982

Normal pterin values in urine and serum in neonates and its age-related change throughout life.

Tetrahydrobiopterin (BH4) deficiency has been described as a form of hyperphenylalaninaemia in which severe neurological symptoms develop despite early treatment with low phenylalanine diet. In recent years it has become apparent that biopterin deficiency may be caused by a defect either of dihydropteridine reductase (DHPR, EC 1.6.99.10) or dihydrobiopterin synthetase (DHBS) (Niederwieser et al., 1979). Since it was proposed that treatment with precursors of the neurotransmitters involved could prevent neurological deterioration if started within the first months after birth (Curtius et al., 1979), screening of all neonates with hyperphenylalaninaemia for biopterin disorders, and a non-invasive reliable method for the diagnosis of two types of BH4 deficiency are needed urgently. Assessment of pterin derivatives in biological fluids, mostly in urine, by high performance liquid chromatography (HPLC) is proposed as a reliable diagnostic method and Crithidia fasciculata bioassay is also a very sensitive method of measuring biopterin activity. Thus normal values of pterin derivatives during the neonatal period are needed. Nevertheless, few reports on a small number of neonates have so far been found (Niederwieser et al., 1980). In this study we describe normal values of pterin derivatives in urine and biopterin activity in serum, and their age-related change in early neonates, young infants, children and adults.

Adolescent↗