Increased peroxidase activity in Pendred's syndrome with hypothyroidism.

Yamamoto, Makiko; Saito, Shintaro; Sakurada, Toshzro; Yoshida, Katsumi; Yoshinaga, Kaoru

doi:10.1620/tjem.119.103

Cited by 1 publication

(2 citation statements)

References 26 publications

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“…According to our results and those reported by other investigators (Ljung¬ gren et al 1973;Burrow et al 1973;Yamamoto et al 1976;Milutinovic et al 1969; Cave 8c Dunn 1975) Pendred's thyroids would normally account for the four major components of the iodination process. A cytostructural defect, precluding the meeting of the iodination components to the iodination site, was postulated a few years ago as a theoretical cause of iodine organification defect (Niepomniszcze et al 1972).…”

Section: Discussionsupporting

confidence: 87%

“…Ljunggren et al (1973) were the first to demonstrate normal thyroid pe¬ roxidase activity in patients with Pendred's syndrome. Although these findings have been corroborated by other investigators (Burrow et al 1973;Yamamoto et al 1976), no studies on the qualitative properties of the peroxidase have as yet been presented. Burrow et al (1973) have shown normal NADPH-cytochrome c reducíase activity in the thyroid of a patient with Pendred's syn¬ drome, and the iodine receptor protein, thyroglobulin, has also been found in this disease (Burrow et al 1973;Milutinovic et al 1969;Yamamoto et al 1976).…”

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confidence: 58%

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Biochemical Studies on the Iodine Organification Defect of Pendred's Syndrome

Nièpomniszcze¹,

Ah²,

Degrossi³

et al. 1978

Acta Endocrinologica

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Biochemical studies were performed on the thyroid of a typical case of Pendred's syndrome who underwent total thyroidectomy. The patient, a euthyroid 14 year old female, presented congenital nerve deafness, goitre and impairment of thyroidal iodine organification. Thyroid peroxidase (TPO) activity was quantitatively normal. Using crude preparations, enzyme activity ranged from 176\p=n-\366 nmoles of I \ m= -\ \ x = r e q -\ incorporated (inc.) to tyrosine/g of tissue. Normal values are 220\p=n-\410 nmoles I\m=-\inc./g. Digitonin pseudosolubilized TPO, assayed by the tyrosine-iodinase method, showed 44.9 nmoles I\m=-\ inc./mg of protein for the Pendred's tissue, and 44.5 nmoles I\m=-\ inc./mg for the control glands. Soluble TPO was utilized for enzyme-kinetic studies. The Km for H2O2, obtained in the triiodide assay with iodide as hydrogen donor, was in the same order of magnitude for both Pendred's and control thyroids, being 3 \ m=x\ 10\m=-\4 m and 3.5 \ m=x\10\m=-\4 m, respectively. In the guaiacol assay, the Pendred's Km value of 4 \ m=x\10\m=-\4 m was also normal for H2O2. Pre-incubation of enzyme preparations with 5 \m=x\10\m=-\5m haematin did not stimulate TPO activity. Thyroidal NADPH-cytochrome c reductase and monoamine oxidase activities were normal. A low concentration, 37 mg/g, of a qualitatively normal thyroglobulin was found in Pendred's goitre. The iodine content of thyroglobulin was 0.19 %.

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