Search PubMed⌕ Search

Biomedical subjects

I Matsuda

Publications and source records attributed to I Matsuda.

At least 217 records · Page 12Linked to original sources
PubMed1991

Structural organization and chromosomal localization of the gene for the E1 beta subunit of human branched chain alpha-keto acid dehydrogenase.

A defect in the E1 beta subunit of the branched chain alpha-keto acid dehydrogenase (BCKDH) complex is one cause of maple syrup urine disease (MSUD). In an attempt to elucidate the molecular basis of MSUD, we isolated and characterized the cDNA of the E1 beta subunit of BCKDH. Using the cDNA as a probe, a chromosomal gene related to E1 beta subunit of human BCKDH was isolated from human gene libraries. The gene of E1 beta subunit is over 100 kilobases long and is split into 10 exons. All of the splice donor and acceptor sites conform to the GT/AG rule. The transcription initiation site was determined by nuclease S1 mapping and primer extension and was located 47 bases upstream from the initiation codon. A "CAAT" box and its reverse complement sequences were present at 39 bases and 75 bases upstream from the cap site, but there was no "TATA" box-like sequence. There were three sets of sequences resembling the transcription factor Sp1-binding sites and two sets of sequences resembling the enhancer core sequence. We also analyzed the chromosomal localization of the gene for the E1 beta subunit of BCKDH. The gene was mapped to chromosome 6. Knowledge of the gene structure of human BCKDH E1 beta subunit will facilitate further studies on the expression and regulation of this gene and provide necessary information for analyses of mutations in patients with MSUD.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1991

Characterization of the human IL-5 receptors on eosinophils.

Interleukin 5 (IL-5) receptors on the cell surface of human eosinophils and other hematopoietic cells were characterized using radiolabeled recombinant IL-5. The binding of 35S-labeled murine IL-5 to eosinophils from normal human peripheral blood was rapid and saturable within a 30-min incubation at both 4 and 37 degrees C. The binding of 35S-labeled murine IL-5 to eosinophils was inhibited by an excess of unlabeled murine and human IL-5 or by an anti-murine IL-5 monoclonal antibody (NC17) but not by other human cytokines. Scatchard plot analysis revealed that human eosinophils have a single class of high affinity receptor (Kd 170-330 pM; number of binding sites: 260-380/cell). IL-5 receptors on eosinophils from four patients with eosinophilia displayed similar characteristics. Affinity cross-linking experiments resulted in the identification of human IL-5 receptor on eosinophils with a molecular mass of 55-60 kDa. Among the various cells besides eosinophils and cell lines that we could test, a subline of HL-60 (YY-1 cells) was found to display a significant number of IL-5 receptor. These results suggest that IL-5 may act on limited types of cells in the human system.

Aged↗
PubMed1991

Retrospective survey of urea cycle disorders: Part 1. Clinical and laboratory observations of thirty-two Japanese male patients with ornithine transcarbamylase deficiency.

In a retrospective survey done from 1978-1988 in Japan, 32 male patients with ornithine transcarbamylase (OTC) deficiency were identified. We classified a neonatal and 2 late-onset groups, depending on clinical manifestations and the age at onset; group 1 (0-28 days; N = 10), group 2 (29 days-5 years; N = 13), and group 3 (greater than 5 years; N = 9). Compared to findings in the group 2 patients, there was a higher rate of mortality and a higher incidence of mental retardation in association with a great decrease in enzyme activity in group 1. In group 3, the mortality rate and enzyme activities were similar to those in group 1. However, patients in this group were asymptomatic prior to the first episode. Enzyme activities were measured mostly in autopsy samples. The serum citrulline levels (enzyme product) were highest in this group. Thus, the mutant enzymes were apparently labile with greater activities in vivo than in vitro. Treatments, including a protein-restricted diet, arginine supplementation, and sodium benzoate administration, resulted in a favorable prognosis for survivors with partial enzyme deficiency. We wish to emphasize that the incidence of late onset of this disease is higher than heretofore considered.

Child, Preschool↗
PubMed1991

Possible mapping of the gene for transient myeloproliferative syndrome at 21q11.2.

The parental origin of the extra chromosome 21 was studied in 20 patients with trisomy 21-associated transient myeloproliferative syndrome (TMS) using chromosomal heteromorphisms as markers; this was combined with a study of DNA polymorphisms in 5 patients. Of these, 10 were shown to result from duplication of a parental chromosome 21, viz., maternal in 8 and paternal in 2. A patient with Down syndrome-associated TMS had a paracentric inversion in two of his three chromosomes 21 [47,XY,-21,+inv(21)(q11.2q22.13)mat,+inv(21)(q11.2 q22.13)mat]. These findings support our hypothesis of "disomic homozygosity" of a mutant gene on chromosome 21 in 21-trisomic cells as being a mechanism responsible for the occurrence of TMS. The finding also suggests that the putative TMS gene locus is at either 21q11.2 or 21q22.13, assuming that the gene is interrupted at either site because of the inversion. The study of 5 TMS patients using DNA polymorphic markers detected a cross-over site on the duplicated chromosomes 21 between 21q11.2 (or q21.2) and 21q21.3 in one patient, and a site between 21q21.3 and q22.3 in another patient, evidence that confined the gene locus to the 21cen-q21.3 segment. These findings suggest that the putative TMS gene is located at 21q11.2. The extra chromosome 21 in the latter two TMS patients probably resulted from maternal second meiotic non-disjunction, in view of the presence of recombinant heterozygous segments on their duplicated chromosomes 21.

Chromosome Aberrations↗
PubMed1991

A novel missense mutation in exon 8 of the ornithine transcarbamylase gene in two unrelated male patients with mild ornithine transcarbamylase deficiency.

We studied two unrelated male probands with mild ornithine transcarbamylase (OTC) (E.C.2.1.3.3) deficiency presenting a similar clinical course. Previous analyses of their liver OTCs also revealed similar properties. To identify the underlying molecular defects, we first cloned the entire coding region of the OTC gene from one proband and found a single base-substitution (C to T) leading to the substitution of tryptophan for arginine at amino acid position 277. Using a genomic amplification technique followed by allele specific oligonucleotide hybridization, we identified the same point mutation in the OTC gene of the other proband. We observed the presence of the mutation among family members in at least three generations, and in one asymptomatic hemizygous sibling in each family.

Alleles↗
PubMed1991

Anti-neutrophil antibodies in patients with nutritional copper deficiency.

Ten patients with nutritional copper deficiency were studied in terms of neutrophil counts and anti-neutrophil antibodies (ANA). In four patients with severe or moderate copper deficiency, the production of ANA was positive and two patients with a severe deficiency had neutropenia. After copper supplementation, ANA titres became negative or were reduced in all patients and neutrophil counts reverted to normal in two patients. It thus appears that copper deficiency is linked to the production of ANA, a condition which partly responsible for neutropenia.

Adolescent↗
PubMed1991

Infusion of zinc inhibits serum calcitonin levels in patients with various zinc status.

Serum concentrations of ionized calcium, parathyroid hormone, and calcitonin were measured during zinc infusion in patients of short stature (n = 15); those with insulin-dependent diabetes mellitus (n = 13); and age-matched controls (n = 10). The increase in serum zinc concentrations after zinc infusion resulted in a decrease in the serum calcitonin concentrations but not in concentrations of ionized calcium and parathyroid hormone. A significant negative correlation was obtained between body zinc clearances and decreases in serum calcitonin levels at 60 minutes after the infusion of zinc. Thus, we found a relationship between infusion of zinc and the regulation of calcitonin secretion. We propose that an increase in the serum zinc pool plays a definite role in inhibiting calcitonin secretion from thyroid tissue.

Adolescent↗
PubMed1991

Molecular defect in siblings with prolidase deficiency and absence or presence of clinical symptoms. A 0.8-kb deletion with breakpoints at the short, direct repeat in the PEPD gene and synthesis of abnormal messenger RNA and inactive polypeptide.

Prolidase deficiency is an autosomal recessive disorder with highly variable symptoms, including mental retardation, skin lesions, and abnormalities of collagenous tissues. In Japanese female siblings with polypeptide negative prolidase deficiency, and with different degrees of severity of skin lesions, we noted an abnormal mRNA with skipping of 192 bp sequence corresponding to exon 14 in lymphoblastoid cells taken from these patients. Transfection and expression analyses using the mutant prolidase cDNA revealed that a mutant protein translated from the abnormal mRNA had an Mr of 49,000 and was enzymatically inactive. A 774-bp deletion, including exon 14 was noted in the prolidase gene. The deletion had termini within short, direct repeats ranging in size of 7 bp (CCACCCT). The "slipped mispairing" mechanism may predominate in the generation of the deletion at this locus. This mutation caused a 192-bp in-frame deletion of prolidase mRNA and was inherited from the consanguineous parents. The same mutation caused a different degree of clinical phenotype of prolidase deficiency in this family, therefore factor(s) not related to the PEPD gene product also contribute to development of the clinical symptoms. Identification of mutations in the PEPD gene from subjects with prolidase deficiency provides further insight into the physiological role and structure-function relationship of this biologically important enzyme.

Amino Acid Sequence↗
PubMed1991

Maple syrup urine disease caused by a partial deletion in the inner E2 core domain of the branched chain alpha-keto acid dehydrogenase complex due to aberrant splicing. A single base deletion at a 5'-splice donor site of an intron of the E2 gene disrupts the consensus sequence in this region.

We have studied the molecular bases of maple syrup urine disease by analyzing the activity, subunit structure, mRNA sequence, and the genome of the affected enzyme. The branched chain alpha-keto acid dehydrogenase (BCKDH) activity in the patient was 4.2-4.5% of the control level. Immunoblot analysis revealed that the E2 subunit of BCKDH (Mr 52,000) was absent and another protein band with an Mr of 49,000 was present. We amplified the cDNA of the E2 subunit obtained from the patient's cell using the polymerase chain reaction method, then sequenced the amplified cDNA, in which a 78-bp deletion was identified. The consanguineous parents and a sister had two species of mRNA; the one corresponding to the normal E2 subunit and the other with a 78-bp deletion, whereas findings in a brother were normal. The molecular size of the translation products as deduced from the abnormal mRNA sequence was compatible with an abnormal protein band (Mr 49,000) detected in the patient's cells by immunoblot analysis. Analysis of genomic DNA of BCKDH-E2 subunit revealed that the 78-bp deletion in the mRNA was caused by an exon skipping due to a single base deletion in the 5'-splice donor site. As a result of the mutation, part of the inner E2 core domain was omitted. The specified region of the inner E2 core domain was highly homologous to the region of the E2 subunit of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase. These observations imply the biological importance of the region in the inner E2 core domain of BCKDH to maintain normal function of the activity.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1991

Maple syrup urine disease. Complete defect of the E1 beta subunit of the branched chain alpha-ketoacid dehydrogenase complex due to a deletion of an 11-bp repeat sequence which encodes a mitochondrial targeting leader peptide in a family with the disease.

Branched chain alpha-ketoacid dehydrogenase (BCKDH) deficiency results in maple syrup urine disease (MSUD). We examined the molecular basis of familial cases of MSUD by analyzing the activity, subunit structure, mRNA sequence, and genome structure of the affected enzyme. The BCKDH activity in the proband with MSUD was approximately 6% of the normal control level. Immunoblot analysis revealed that the E1 beta subunit of BCKDH was absent and that the E1 alpha subunit of BCKDH was markedly reduced. We amplified the cDNAs of the E1 alpha subunit and the E1 beta subunit of the BCKDH complex obtained from cells of the patient, using the polymerase chain reaction method, then sequenced the amplified cDNAs. The deduced amino acid sequence for the E1 alpha subunit of the patient's cell was normal. An 11-bp deletion was identified in the region that encoded the mitochondrial targeting leader peptide in the E1 beta cDNA. This 11-bp sequence is found in the first exon of the BCKDH-E1 beta gene, as a direct tandem repeat. Amplification of genomic DNA revealed that the consanguineous parents were heterozygous for this mutant allele, and sister and brother of the patient with the disease were homozygous for this mutant allele. This 11-bp deletion mutation caused a change in the reading frame and the mature E1 beta protein was defective. These observations show the biological importance of the E1 beta subunit of BCKDH to maintain normal function of the enzyme activity. The absence of the E1 beta subunit results in instability of the E1 alpha subunit.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1991

Kinetics of zinc status in children with IDDM.

OBJECTIVE: To ascertain zinc deficiency in patients with insulin-dependent diabetes mellitus (IDDM) and evaluate the relationship between zinc clearance and body height velocity. RESEARCH DESIGN AND METHODS: Six boys and 11 girls with IDDM and zincuria and glycosuria were studied. Study quality and specific descriptive information concerning relationship and outcome measurement were assessed. RESULTS: The values of total-body zinc clearance in IDDM patients were higher than in the control subjects (24.6 +/- 1.8 vs. 15.1 +/- 0.6 ml.kg-1.h-1, P less than 0.01). There was a negative correlation between body zinc clearance values and height velocity in IDDM patients. CONCLUSIONS: Patients with IDDM have a secondary zinc deficiency, and normal growth may be stunted.

Adolescent↗