Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.8 (thyroid peroxidase)
3,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Time-courses of changes in the activities of liver and kidney glucose-6-phosphatase [EC 3.1.3.9] and hepatic tryptophan pyrrolase [EC 1.13.1.12; TPO] in rats pre-fed high-protein diets for 5 days and then shifted to zero-protein diets were studied. Liver glucose-6-phosphatase activity decreased 1 day after the dietary shift but then increased and remained significantly higher than the 0 day value for the next 2 days. Changes in liver glycogen were found to be intimately and inversely related to liver glucose-6-phosphatase activity. Changes in kidney glucose-6-phosphatase activity paralleled the pattern of changes observed in liver activity. An initial decrease in TPO activity was followed by increased enzyme activity up to the 3rd day of the dietary shift. Later there was a rapid fall in tryptophan pyrrolase activity. Changes observed in these specific enzyme proteins differed from those observed in total tissue proteins. Alterations in the activities of these enzymes and changes in other parameters are compared with those observed earlier with the reverse type of dietary shift.
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PMID:Time-course of changes of liver tryptophan pyrrolase (tryptophan oxygenase) and liver and kidney glucose-6-phosphatase in rats shifted from high- to zero-protein diets. 625 15

The cellular localization and regional distribution of insulin- and glucagonlike substance, C-peptide-like immunoreactivity, thiol:protein disulphide oxidoreductase, TPO (E.C.1.8.4.2.), and insulin/glucagon-specific proteinase, ISP (E.C.3.4.22.-), are studied in the CNS of man, adult and juvenile rats, mice, tortoises, and frogs by use of immunohistochemistry. Furthermore, the content of immunoreactive insulin, glucagon, and C-peptide was estimated in human cadaver brains by radioimmunoassay. It could be shown that insulinlike immunoreactive material is widely distributed in the human brain and the CNS of juvenile rats as well as in mice, whereas in the CNS of adult rats and nonmammalian animals (frogs, tortoises) the polypeptide is restricted to a few nerve cell populations. C-peptide immunoreactivity was demonstrated in human CNS in the same nerve cells as insulin. By use of two different glucagon-antisera it was revealed that gut-type glucagon occurs in many nerve cells of human and mouse brains, as well as in the CNS of juvenile rats. On the other hand, pancreas-type glucagon was less widely distributed in the human brain and nearly not detectable in the CNS of mice and rats. With the exception of neurosecretory nerve cells, there was a high degree of coincidence between the localization of insulin and TPO. The immunoreaction against the ISP antiserum was weak, but correlated well with the distribution of insulin-immunoreactivity. The occurrence of TPO and ISP in the brain demonstrates the ability of nervous tissue to degrade insulin and glucagon. By radioimmunoassay it was established that human brain contains insulin, glucagon and C-peptide at concentrations that exceed blood levels. We conclude from our data that, at least in part, cerebral insulin and glucagon are products of the brain itself.
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PMID:Insulin- and glucagonlike peptides in the brain. 635 89

Insulin degrading enzymes of rat liver cytosol, the so-called insulin and glucagon degrading proteinase (IGP, EC 3.4.23.5), and two forms of the insulin degrading thiol-protein-disulfide oxidoreductase/isomerase (glutathione-insulin transhydrogenase, TPO, EC 1.8.4.2/5.3.4.1) were separated from each other and partially purified on DEAE-Sephadex. The highly purified proteinase was obtained by polyacrylamide gel electrophoresis of the DEAE-Sephadex-purified enzyme fraction and was used to produce monospecific antibodies to the IGP in rabbits. Strong evidence is given that the insulin and glucagon degrading proteinase is an autonomous enzyme existing in addition to the TPO forms in the cytosol of the liver. Combined action of the proteinase and the TPO system on radioiodinated insulin under various conditions in vitro revealed an independent and non-sequential degradation of insulin by these two enzyme systems.
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PMID:The insulin and glucagon degrading proteinase of rat liver. Separation of the proteinase from the thiol-proteindisulfide oxidoreductases. 637 96

Cathepsin D (EC 3.4.23.5), the insulin and glucagon degrading proteinase (IGP, EC 3.4.22.-) and the thiol-protein disulfide oxidoreductase (TPO, EC 1.8.4.2, 5.3.4.1) participate in the intracellular protein degradation, the last one also in post-protein-synthetic processing. The distribution of these enzymes was determined in isolated liver parenchymal cells, Kupffer cells and endothelial cells by means of immunochemical methods in order to further characterize these cell types. The cathepsin D content, expressed as microgram enzyme per mg protein, is about 3 fold higher in endothelial cells and about 5 to 24 fold higher in Kupffer cells than in parenchymal cells. This result confirms an earlier report which is based on the activity determination. The TPO concentration is highest in parenchymal cells with half of that concentration in Kupffer cells and one third in endothelial cells. About 0.5% of the total liver protein is represented by this enzyme. The IGP has been found to be totally absent in non-parenchymal cells. It represents, therefore, together with the glucose-6-phosphatase a valuable marker enzyme for parenchymal cells of rat liver.
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PMID:Distribution of thiol-protein disulfide oxidoreductase, insulin-glucagon proteinase and cathepsin D in different cell types of the rat liver. 644 77

This report describes a method for measurement of TPO activity by the amount of thyroid hormone production. Thyroid hormone formation was accomplished by incubating purified iodine-poor Tg with human TPO for 60 min at 37 C in the presence of free DIT, KI, and an H2O2 source. Newly formed T3 and T4 were measured by radioimmunoassay of the Tg hydrolysates. With this method, TPO-catalyzed iodination of Tg and thyroid hormone formation were measured simultaneously from eight normal thyroid glands and 15 thyroid glands from MMI-treated patients with Graves' disease. Graves' disease TPO showed iodinating activity and T4 formation which was higher than that of TPO from normal thyroids, and there was a positive linear correlation between the iodinating activity and the amount of T4 formation. T3 production by highly active TPO, however, dissociates from the amount of T4 formation and the degree of Tg iodination. Thus, if the activity of TPO is to be measured by the amount of thyroid hormone production, T4 should be used rather than T3. The method of thyroid hormone formation described here provides a new and physiological measurement of TPO activity and should be useful for investigation of the role of human TPO in thyroid hormone formation.
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PMID:Thyroid hormone formation catalyzed by human thyroid peroxidase: a new and physiological measurement of thyroid peroxidase. 689 10

In subjects with normal vision, differences have been detected in the reactions of the main components (P100, N150, P200) of evoked potentials recorded in the Oz and TPO leads, to homogeneous stimuli, chess fields with different sizes of cells and grids differing in area and the number of orientation stripes. The data obtained are discussed in the light of V.D. Glezer's hypothesis on specialized information processing in the visual and posterior associative cortical areas and concepts on the existence of separate channels of processing different image properties.
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PMID:[Effect of parameters of spatio-structural stimuli on evoked potentials of the visual and posterior associative regions of the cortex in man]. 716 77

An ultrasonographic survey of thyroid abnormalities was conducted in 547 consecutive apparently normal overweight subjects (380 females and 167 males), aged 27-58 years in an urban area with relatively low iodine intake (mean daily urinary iodine excretion: 10.6 micrograms/dL). Individuals with any previous thyroid disease or familial thyroid pathology were excluded. In 240 subjects (44%) high resolution ultrasonography of the thyroid was considered normal. In 307 individuals (56%) abnormalities of the echo structure (39%) or thyroid nodular disease (17%) were detected by ultrasonography. Marked heterogeneity of the echo structure that was considered suggestive of chronic autoimmune thyroiditis was present in 81 subjects (15%). In 72 of these patients the serum anti-TPO levels were positive by a sensitive RIA. Thyroid nodules either solid or predominantly cystic were present in 90 subjects (17%). Eighteen patients had a relatively large nodule (diameter 15-18 mm). Eleven of these nodules were missed at clinical examination. Fine needle aspiration cytology was performed in 14 patients and 7 individuals underwent thyroid surgery. In 6 subjects the pathologic diagnosis was benign adenomatous goiter and one patient had a follicular carcinoma. Thyroid function studies confirmed subclinical hypothyroidism in 27 patients (4.9%), all of them with elevated serum anti-TPO autoantibodies levels. It was concluded that the overall occurrence of thyroid disease is more common than suspected by clinical examination.
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PMID:Prevalence of incidental thyroid disease in a relatively low iodine intake area. 748 67

We have investigated functional common T-cell epitopes between human thyroglobulin (hTg) and human thyroid peroxidase (hTPO) in mice. Four hTg peptides, Tg-P1, Tg-P2, Tg-P3 and Tg-P4, in which 5 amino acid residues are identical to those of hTPO, and 1 hTPO peptide, TPO-P4 relevant to Tg-P4, were prepared. Among these peptides, only Tg-P4 (residues 2730-2743) and TPO-P4 (residues 118-131) were highly antigenic and both peptides shared the common T-cell epitope. In addition, when the spleen cells from mice immunized with mouse Tg (mTg) were restimulated in vitro by Tg-P4 or TPO-P4 as well as by mTg, these cells transferred thyroiditis to naive recipient mice. These findings indicate that this common T-cell epitope between hTg and hTPO is immunogenic and related to the development of murine experimental autoimmune thyroiditis.
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PMID:A common T-cell epitope between human thyroglobulin and human thyroid peroxidase is related to murine experimental autoimmune thyroiditis. 750 5

Crude thyroid peroxidase extracted from human thyroid microsomes was covalently bound onto polyacrylic and polyfunctional copolymerized microparticles. We observed agglutination of the thyroid peroxidase-microparticle conjugate with 13 monoclonal antibodies (mAbs) specific for epitopes on four different antigenic domains of human thyroid peroxidase (TPO; EC 1.11.1.7), after addition of anti-mouse immunoglobulins. We quantified agglutination by measuring with a specially designed nephelometer the light scattered by the conjugates. This allowed us to develop a microparticle-enhanced nephelometric immunoassay for human anti-TPO autoantibodies (aAbs) with defined epitopic specificity, based on the ability of aAbs to inhibit mAb-induced agglutination. Applied to patients with autoimmune thyroid diseases, this assay confirmed the polyclonality of anti-TPO aAbs and their preferential reactivity toward epitopes located on the A and B antigenic domains of the TPO molecule. The same specificities seem to be present in patients with Hashimoto thyroiditis or Graves disease.
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PMID:Microparticle-enhanced nephelometric immunoassay of anti-thyroid peroxidase autoantibodies in thyroid disorders. 751 May 93

The thiol-proteindisulfide-oxidoreductase (TPO, EC 1.8.4.2., proteindisulfide isomerase, EC 5.3.4.1.) is known as an cytoplasmatic enzyme, and is thought to be involved in the post-translational folding of disulfide containing proteins. Using monoclonal and polyclonal antibodies the authors were able to prove that this enzyme or an unknown homologous protein is localized also to the plasma membrane of B lymphocytes. In peripheral blood from healthy donors 11% of the mononuclear cells (PBMNC) expressed this surface antigen whereas in PBMNC of patients with B-cell chronic lymphocytic leukaemia 76% of the MNC were positive. This value correlates well with the known B-cell markers CD19 and CD20. However, this antigen is different from all known clustered B-cell markers. Immunoprecipitation analysis of PHA-stimulated PBMNC and of cells from patients suffering from chronic lymphocytic leukaemia revealed a membrane protein with the same molecular weight (61 kDa) as the TPO. These data suggest that this enzyme is present not only in the cytoplasm but also on the surface of B cells and that it is possibly involved in the regulation of the SH-SS status of the cell membrane proteins of B lymphocytes.
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PMID:Thiol-proteindisulfide-oxidoreductase (proteindisulfide isomerase): a new plasma membrane constituent of mature human B lymphocytes. 751 32


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