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Biomedical subjects

S Miyabayashi

Publications and source records attributed to S Miyabayashi.

At least 37 records · Page 2Linked to original sources
PubMed1994

Fetal liver biopsy for prenatal diagnosis of carbamoyl phosphate synthetase deficiency.

Carbamoyl phosphate synthetase deficiency is a type of an inborn error of metabolism with a poor prognosis. Carbamoyl phosphate synthetase is a liver-specific enzyme, and its deficiency can only be diagnosed by enzyme assay using liver biopsy specimens. A pregnant woman at risk for carbamoyl phosphate synthetase deficiency was evaluated for the purpose of prenatal diagnosis of the condition. Fetal liver biopsy was performed at the 22nd week of gestation. The results of enzyme assays on fetal liver biopsy revealed normal enzymatic activity and the diagnosis of carbamoyl phosphate synthetase deficiency was ruled out prenatally. Methods and safety of fetal liver biopsy are discussed. Measurements of activity of liver-specific enzymes were evaluated with respect to methodology and manner of assessment. Prenatal diagnosis of deficiencies in liver-specific enzymes, which have hitherto been considered difficult to detect before birth, has now become possible.

Adult↗
PubMed1993

Accumulation of mtDNA with a mutation at position 3271 in tRNA(Leu)(UUR) gene introduced from a MELAS patient to HeLa cells lacking mtDNA results in progressive inhibition of mitochondrial respiratory function.

A new mitochondrial DNA (mtDNA) mutation of tRNA(Leu)(UUR) at nucleotide position 3271 (MELAS3271) was determined to be involved in the pathogenic process of mitochondrial diseases MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) using intercellular transfer of patient-derived mtDNA to mtDNA-less HeLa cells (rho 0 HeLa cells). Cybrid clones containing imported mtDNA exclusively from a MELAS patient with MELAS3271 mtDNA were isolated, and the influence of MELAS3271 mtDNA on mitochondrial translation activity and mitochondrial respiratory complex I enzyme activity were examined. Accumulation of more than 87% MELAS3271 mutant mtDNA in the cybrid clones induced both low complex I activity and abnormal mtDNA-encoded polypeptide synthesis including at least complex I subunit ND6. suggesting involvement of the new MELAS-associated mutation in the pathogenesis.

Blotting, Southern↗
PubMed1993

Quantitative evaluation of electron transport system proteins in mitochondrial encephalomyopathy.

The levels of mitochondrial electron transport system proteins cytochrome c oxidase (COX) and complex III were measured in muscle fibers of patients with mitochondrial encephalomyopathy using quantitative immunoelectron microscopy. In a patient with Leigh's encephalopathy, immunoreactive COX protein was decreased to 20% of the normal mean value in all muscle fibers examined, while the amount of complex III was within the normal range. In a patient with fatal infantile COX deficiency, the level of COX protein was found to be decreased to 27-40% of the normal value in all muscle fibers examined. In patients with mitochondrial myopathy, encephalopathy, lactic acidosis associated with stroke-like episodes (MELAS) and chronic progressive external ophthalmoplegia (CPEO), COX protein levels were decreased to 20% of normal in muscle fibers lacking COX activity. In normal fibers, however, COX protein levels were also normal. The amount of complex III protein was normal in COX-deficient muscle fibers. In two patients, in situ hybridization was performed for detection of mitochondrial mRNA. Mitochondrial mRNAs were found to be abundant in muscle fibers with decreased COX protein, suggesting a defect at the mitochondrial protein-synthesis level in a COX-deficient muscle fiber.

Adult↗
PubMed1993

[A study of myocardial disorders in an autopsy case of mitochondrial encephalomyopathy].

We report an autopsy case of a 19 year-old man with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) a subgroup of mitochondrial encephalomyopathy presenting cardiomyopathy. He had repeatedly suffered from transient unconsciousness, hemiplegia, hemianopsia and convulsion attacks since the age of 9, and he died of severe congestive heart failure. In laboratory findings, blood lactate and pyruvate were markedly increased. Skeletal muscle biopsy demonstrated numerously scattered ragged-red fibers with modified Gomori's trichrome staining. Enzymatic activities of the mitochondrial respiratory chain showed a marked decrease of NADH cytochrome c reductase (complex I). In postmortem examination, the heart was 310g in weight and had right ventricular dilatation. Microscopically, degenerated and scattered myocardial cells (ragged-red fibers), interstitial edema and microvascular hyperplasia were demonstrated in the myocardium. Under the electron microscope, abnormal mitochondria proliferated and myofibrils were unusually sparse. Immunohistochemical studies with specific antibodies against the mitochondrial electron transfer enzyme subunits revealed a reduction of immunoreactive materials for complex I in the myocardium. These results suggested the relationship of myocardial disorders and decreased activity of complex I in electron transfer enzymes in this patient.

Adult↗
PubMed1992

Prenatal diagnosis in high risk pregnancies for Zellweger syndrome.

Zellweger syndrome is a lethal disorder. At present, no effective therapies are known for the patients of Zellweger syndrome. Recently a typical case of Zellweger syndrome in Japan was observed. In spite of intensive care, the patient died at the age of 3 months. Following this, the parents requested prenatal diagnosis for their following two pregnancies. We investigated levels of very long chain fatty acids (VLCFA), levels of bile acids in amniotic fluid and immunoblotting of peroxisomal beta-oxidation enzymes in cultured amniocytes. We report that immunoblotting using cultured amniocytes is an effective method for prenatal diagnosis of Zellweger syndrome. Furthermore, if we use immunoblotting for prenatal diagnosis, we can discriminate pseudoZellweger syndrome from pseudoneonatal adrenoleucodystrophy. Following prenatal diagnosis, two healthy babies were delivered. After birth, no abnormal levels of VLCFA in either serum or red blood cell membranes were confirmed. In this paper, we report that we can diagnose a healthy fetus in a high risk pregnancy for Zellweger syndrome.

Amniocentesis↗
PubMed1992

Thiamine responsive pyruvate dehydrogenase deficiency.

We studied a PDH deficient patient who is clinically responsive to thiamine. High Km and low Vmax values for the TPP were identified in the patient's cultured cells. Immunoblot analysis detected trace amount of mutant E1 alpha polypeptide which was 3.5 KD larger than normal in size. Four-nucleotide deletion in the E1 alpha gene causes a reading frame shift, producing an abnormal polypeptide with additional 31 amino acids at C-terminus of the E1 alpha subunit. The tryptophan (codon 383) and lysine (385) residues near the C-terminus might play a crucial role in the binding of TPP to the E1.

Amino Acid Sequence↗
PubMed1991

Genetic heterogeneity of propionic acidemia: analysis of 15 Japanese patients.

Propionic acidemia is an autosomal recessive metabolic disease resulting from a deficiency of propionyl CoA carboxylase (PCC) activity. We have analyzed the molecular heterogeneity of Japanese propionic acidemia patients using anti-human PCC antiserum and cDNA clones coding for the two protein subunits (alpha and beta) of the enzyme. The steady state levels of both alpha and beta subunits of PCC from 15 Japanese patients were determined by Western blot. Three patients had neither alpha nor beta subunits, and the amounts of both alpha and beta subunits were low in 3 other patients. According to our previous data, we classified these 6 patients as having alpha subunit deficiency. In the remaining 8 patients, alpha subunits were normal, but the beta subunits were aberrant. Two patients had low levels of normal-sized beta subunits and 6 had beta subunits smaller than normal in size and greatly reduced in quantity. These 8 patients were assigned to the beta subunit deficiency category. One patient had apparently normal alpha and beta subunits. We could not determine this patient's primary defect. These data reveal the genetic heterogeneity of molecular defects causing propionic acidemia in the Japanese. Southern blot analysis did not reveal any gross alteration in gene structure when DNA was digested with HindIII, EcoRI and TaqI. However, DNA from 3 beta-subunit-deficient patients, when digested with MspI and probed with beta PCC cDNA, revealed a unique 2.7-kb band not observed in blots of DNA from any other patient or 15 normal controls. We conclude that this altered MspI restriction map is the result of a mutation in the beta subunit gene of these patients.

Blotting, Southern↗
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↗
PubMed1990

Identification of a common mutation in patients with medium-chain acyl-CoA dehydrogenase deficiency.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is one of the most common recessively inherited metabolic diseases in man. We have studied fibroblast cultures obtained from three patients with MCAD deficiency by sequencing the entire coding region of MCAD mRNA. A single A to G nucleotide replacement which resulted in lysine329-to-glutamic acid329 substitution of the MCAD protein was identified in all cultures. Furthermore, this point mutation was present in 91% (31 of 34) of mutant MCAD alleles, indicating that the majority of cases with MCAD deficiency are caused by this type of mutation.

Acyl-CoA Dehydrogenase↗
PubMed1990

Mosaicism of mitochondria in mitochondrial myopathy: an electronmicroscopic analysis of cytochrome c oxidase.

Electron microscopic histochemistry was applied to the study of cytochrome c oxidase activity in each mitochondrion of biopsied muscles from four patients with mitochondrial myopathy [one case of fatal infantile mitochondrial myopathy, one case of myoclonus epilepsy associated with ragged-red fibers (MERRF), and two cases of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS)]. In the patient with fatal infantile mitochondrial myopathy, intercellular heterogeneity of mitochondria was recognized. In the three patients with either MERRF or MELAS, cytochrome c oxidase activity was segmentally changed from positive to negative within single muscle fibers. In the two patients with MELAS, small groups of positive-stained mitochondria were located among negative-stained mitochondria in the negative segment of a few muscle fibers. These findings revealed that there were heterogeneous populations of normal and abnormal mitochondria intracellularly or intercellularly within the muscles of these patients.

Adult↗