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Biomedical subjects

M Owada

Publications and source records attributed to M Owada.

At least 19 recordsLinked to original sources

Effectiveness of 1,25-dihydroxyvitamin D supplementation on blood pressure reduction in a pseudohypoparathyroidism patient with high renin activity.

A 42-year-old man had biochemical and somatic abnormalities compatible with pseudohypoparathyroidism type I (PsHP) and also had high plasma renin activity (PRA). After 1,25-dihydroxyvitamin D (calcitriol) supplementation the systolic/diastolic blood pressure, assessed by 24-hour non-invasive ambulatory blood pressure monitoring, was reduced from 145/96 mm Hg to 128/85 mm Hg with normalization of the serum calcium level and its related hormones, as well as decreased PRA. Calcitriol supplementation successfully reduced the blood pressure in this patient with PsHP and a high PRA, suggesting that calcium-related hormones and/or the renin-angiotensin system were involved in lowering the blood pressure.

Adult

A novel mutation at a probable heme-binding ligand in neutrophil cytochrome b558 in atypical X-linked chronic granulomatous disease.

A membrane-bound cytochrome b558, a heterodimer consisting of gp91-phox and p22-phox, is a critical component of the superoxide (O2-)-generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. Chronic granulomatous disease (CGD) is characterized by recurrent bacterial infection caused by a defect of the oxidase. Both subunits are absent from phagocytes in typical X-linked recessive CGD patients who are primarily defective in gp91-phox. We report here an atypical case of X-linked CGD in which neutrophils showed a complete absence of O2--forming NADPH oxidase activity, but a small amount (about 10% of control) of both subunits was detected by immunoblot analysis. Spectrophotometric studies of the neutrophils with a recently developed sensitive method gave no evidence for the heme spectrum in the cytochrome b558, of this CGD. Reverse transcription/polymerase chain reaction and sequence analysis revealed a C to T transition replacing histidine at amino acid position 101 (His101) by tyrosine in gp91-phox. These results provide evidence that His101 of gp91-phox is the one of the heme-binding ligands of cytochrome b558.

Adolescent

Brainstem pathology of infantile Gaucher's disease with only wave I and II of auditory brainstem response.

We studied the auditory brainstem response (ABR) and neuropathology in a female infant who died at six months of age because of typical infantile Gaucher's disease. The patient was hospitalized for hepatosplenomegaly and failure to thrive. Her ABR showed only waves I and II. The neuropathological study disclosed that: (1) Gaucher's cells were found in the perivascular region of the cerebrum and anterior ventral nucleus of the thalamus. (2) Gliosis was found in the dorsal part of the brainstem rather than the ventral part. (3) Neuronal cells in the superior olivary nucleus were lost, and marked gliosis was found in the cochlear nucleus. The disappearance of wave III and later waves of ABR could be supported by these pathological findings.

Brain Stem

Increased incidence of non-insulin dependent diabetes mellitus among Japanese schoolchildren correlates with an increased intake of animal protein and fat.

Non-insulin dependent diabetes (NIDDM) was diagnosed in 188 of more than 7 million Tokyo schoolchildren tested between 1974 and 1994 for glycosuria followed by oral glucose tolerance testing. The incidence rate of NIDDM in youth has continued to increase since 1976. While the daily energy intake has not changed significantly, the consumption of animal protein and fat by the Japanese population has greatly increased during the past two decades, and this change in diet, with low levels of physical activity, may exacerbate insulin resistance and glucose intolerance.

Adolescent

Treatment of NIDDM in youth.

This study presents the characteristics of 20 children (17 female) with NIDDM who required oral hypoglycemic agent (OHA) therapy. A family history of NIDDM was present in 55%. None had islet cell antibodies (ICA) or glutamic acid decarboxylase (GAD) antibodies. Tolbutamide was the drug of choice; glibenclamide was introduced if glycemic control was not obtained after 2 to 3 months of tolbutamide therapy. Seven of the patients eventually required insulin therapy.

Adolescent

[Cystinuria].

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Amino Acid Transport Systems, Basic

6-Pyruvoyl-tetrahydropterin synthase deficiency with generalized dystonia and diurnal fluctuation of symptoms: a clinical and molecular study.

We report the case of a 44-year-old woman with a partial 6-pyruvoyl tetrahydropterin synthase (6-PTS) deficiency, whose predominant clinical symptom was generalized dystonia with marked diurnal fluctuation. Dystonia was present in the eyelids, oromandibular region, trunk, and extremities (Meige syndrome plus double hemiplegia-like dystonia). A marked and sustained positive response to levodopa was observed. A molecular genetic study revealed a homozygous mutation (I114V) in the 6-PTS gene. This study indicates that genetic abnormality in the 6-PTS gene may be a hereditary dystonia disorder. We speculate that our patient has residual 6-PTS activity in the central nervous system, such as in the liver, and we suggest that residual, but insufficient production of tetrahydrobiopterin may play an important role in causing diurnal fluctuation of symptoms.

Adult

Molecular analysis of dihydropteridine reductase deficiency: identification of two novel mutations in Japanese patients.

Mutations in the dihydropteridine reductase (DHPR) gene result in hyperphenylalaninaemia and deficiency of various neurotransmitters in the central nervous system, causing severe neurological symptoms. We studied two Japanese patients with DHPR deficiency and identified a missense and a splicing error mutation, respectively. A homozygous missense mutation (tryptophan36-to-arginine) was detected in patient 1. The mutation abolished DHPR activity according to in vitro expression studies. The DHPR mRNA in patient 2 was markedly decreased. Reverse transcription-polymerase chain reaction of the mRNA generated a cDNA fragment with a 152-bp insertion. The inserted sequence contained a termination codon, which was likely to affect the stability of the mRNA. Analysis of genomic DNA showed that the insertion was derived from putative intron 3 of the DHPR gene, and an intronic A-to-G substitution was present adjacent to the 3'-end of the inserted sequence. The nucleotide change generated a sequence similar to an RNA splice donor site and probably activated an upstream cryptic acceptor site, thus producing an abnormal extra exon.

Amino Acid Metabolism, Inborn Errors

A newly identified exonic mutation of the WT1 gene in a patient with Denys-Drash syndrome.

An 11 month old boy with hypospadias and bilateral undescended testes developed renal failure. Denys-Drash syndrome was suspected and molecular analysis of the WT1 gene was performed, although no Wilms' tumor was identified. Direct sequencing analysis of genomic DNA from this patient revealed a G to A transition resulting in 366Arg to Leu substitution in exon 8 which has hitherto not been described. This newly identified mutation will help in the understanding of functional domains and in making a diagnosis of Denys-Drash syndrome.

DNA Mutational Analysis