Abstract:
:Biosynthesis of iodothyronines in thyroglobulin occurs by oxidative coupling of two iodotyrosine residues catalyzed by thyroperoxidase. To study the mechanism of iodothyronine formation, iodine-free thyroglobulin was non-enzymatically iodinated and after removal of non-incorporated iodide, incubated with lactoperoxidase and glucose oxidase between pH 4 and 9. The amount of thyroxine (T4). 3,5,3'-tri-iodothyronine (T3), 3,3',5'-tri-iodothyronine (rT3) and 3,3'-di-iodothyronine (T2) formed was measured by radioimmunoassays after hydrolysis of thyroglobulin. T4 is synthesized out of two di-iodotyrosine (DIT) residues in thyroglobulin. The pH dependence of T4 formation fits the dissociation curve of the DIT phenoxy group (pKa 6.5). The formation of T2, synthesized out of two mono-iodotyrosine (MIT) residues, shows a quite different pH dependence. Below pH 6, T2 synthesis could not be observed, while above pH 7.4 a relatively large increase occurred. The values up to pH 8 fitted the dissociation curve of the MIT-phenoxy group with a pKa of 8.7. The gradual loss in enzymatic activity of peroxidase and oxidase in the reaction made the values obtained above pH 8 unreliable. The importance of the ionization of the phenoxy group for the coupling reaction was further consolidated by showing that the pH-dependent oxidation of 2-methoxy-phenol (guaiacol) had 50% maximal product formation at pH 7, a value concordant with pKa 7.0 for the ionization of the phenoxy group of this agent. T3 and rT3 synthesis followed mainly the ionization curve of the inner-ring hydroxyl group, indicating that this ring has the greatest influence on hormonogenesis. Since anion formation facilitates the removal of an electron under oxidative conditions, the pH dependence agrees with the involvement of phenoxy radicals in iodothyronine synthesis, a process that most likely also occurs in vivo since it is mainly T4 that is formed in thyroglobulin.
journal_name
Eur J Endocrinoljournal_title
European journal of endocrinologyauthors
de Vijlder JJ,den Hartog MTdoi
10.1530/eje.0.1380227subject
Has Abstractpub_date
1998-02-01 00:00:00pages
227-31issue
2eissn
0804-4643issn
1479-683Xjournal_volume
138pub_type
杂志文章abstract::Based on experimental and animal models, epidemiological data from non-acromegaly populations, and longitudinal and cross-sectional cohorts of patients with acromegaly, a potential association between acromegaly and cancer has long been hypothesized, in particular colorectal cancer, and, to a lesser extent, breast, th...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/EJE-16-0178
更新日期:2016-10-01 00:00:00
abstract:OBJECTIVE:Endoscopic ultrasound (EUS) is a highly reliable procedure to localize insulinomas preoperatively. It has been considered to be important in planning surgical strategy, especially considering a minimal invasive approach. However, even under ideal conditions experienced examiners miss about 10-20% of insulinom...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-07-0117
更新日期:2007-08-01 00:00:00
abstract:OBJECTIVE:We studied the intervention of nitric oxide (NO), prostacyclin and endothelium-derived hyperpolarizing factor (EDHF) in mediating responses to acetylcholine in thyroid arteries from euthyroid and methimazole-treated (MT) patients. DESIGN AND METHODS:Branches of the superior thyroid artery were obtained from ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.1.01889
更新日期:2005-04-01 00:00:00
abstract::The episodicity of 24 h GH release was studied in 18 patients with active acromegaly, 12 patients 7-10 days after pituitary surgery, 14 patients long after operation (3-17 years), and 21 healthy gender- and age-matched control subjects, using a recently introduced scale- and model-independent regularity statistic, app...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1380164
更新日期:1998-02-01 00:00:00
abstract:BACKGROUND:Fetal growth restriction (FGR) has been related to several health risks, which have been generally identified in small-for-gestational age (SGA) individuals. OBJECTIVE:To evaluate the impact of FGR on body composition and hormonal status in infants born either small- or appropriate-for-gestational age (AGA)...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-07-0286
更新日期:2007-11-01 00:00:00
abstract:OBJECTIVE:Adiponectin and resistin have been linked to inflammation, endothelial dysfunction, and/or insulin secretion or resistance. It remains to be elucidated which of these adipokines is associated primarily with biomarkers of all or only some of these categories, i.e. biomarkers of inflammation, endothelial dysfun...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-09-0555
更新日期:2010-02-01 00:00:00
abstract:OBJECTIVE:Vascular endothelial growth factor (VEGF) exists in three main splice variants, characterized by 121, 165 and 189 amino acids (VEGF 121, VEGF 165 and VEGF 189) and acts via two specific receptors: VEGF-R1 or Flt-1 and VEGF-R2 or KDR. VEGF plays an important role in the pathogenesis of diabetic retinopathy. Th...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1500799
更新日期:2004-06-01 00:00:00
abstract::For patients with neuroendocrine tumours (NETs) of the gastrointestinal tract and pancreas (GEP) (GEP-NETs), excellent care should ideally be provided by a multidisciplinary team of skilled health care professionals. In these patients, a combination of nuclear medicine imaging and conventional radiological imaging tec...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/EJE-14-0077
更新日期:2014-04-10 00:00:00
abstract:BACKGROUND:Neutrophil gelatinase-associated lipocalin (NGAL) and matrix metalloproteinase-9 (MMP-9) have been considered as important mediators of vascular remodeling and plaque instability. The formation of a complex with NGAL and MMP-9 is crucial for atherotic plaque erosion and thrombus formation. In women with poly...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-07-0822
更新日期:2008-04-01 00:00:00
abstract::Phaeochromocytoma is a rare, usually benign, tumour predominantly managed by endocrinologists. Over the last decade, major advances have been made in understanding the molecular genetic basis of adrenal and extra-adrenal phaeochromocytoma (also referred to as adrenal phaeochromocytoma (aPCA) and extra-adrenal function...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/EJE-11-0497
更新日期:2012-02-01 00:00:00
abstract::Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders resulting from deficiency of one of the five enzymes required for synthesis of cortisol in the adrenal cortex. The most common form of the disease is classic 21-hydroxylase deficiency, which is characterized by decreased synthesis of gluc...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/eje.0.151u077
更新日期:2004-11-01 00:00:00
abstract:OBJECTIVE:To evaluate the effect of the growth factor activin A on the secretion of prolactin (PRL) and GH in cultured GH3 cells. METHODS:The concentrations of PRL and GH secreted from GH3 cells cultured in media with and without activin A were measured by RIA, and the expression of PRL mRNA and GH mRNA were analyzed ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1420506
更新日期:2000-05-01 00:00:00
abstract:OBJECTIVE:Chromosomal rearrangements of the RET proto-oncogene is one of the most common molecular events in papillary thyroid carcinoma (PTC). However, their pathogenic role and clinical significance are still debated. This study aimed to investigate the prevalence of RET/PTC rearrangement in a cohort of BRAF WT PTCs ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-14-0930
更新日期:2015-05-01 00:00:00
abstract::The present study examined the changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle. Total cytoplasmic RNA was analyzed by Northern blot and slot-blot hybridization to examine the prolactin mRNA level. Reverse transcription-polymerase chain reaction (RT-...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1320771
更新日期:1995-06-01 00:00:00
abstract:BACKGROUND:Phytosterolaemia (sitosterolaemia) is a rare autosomal recessive condition caused by mutations on the ABCG5 and ABCG8 gut transporter proteins. This leads to accumulation of plant-derived cholesterol-like molecules in blood and tissues. CASE:We describe a family of Bangladesh origin, where three siblings (t...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-07-0222
更新日期:2007-08-01 00:00:00
abstract::Activating mutations of G proteins, which are membrane signal transducers, have been associated recently with the development of various endocrine neoplasms. Mutations of two highly conserved codons, Arg201 and Gln227, in the alpha-subunit of the Gs protein, the adenylyl cyclase-stimulating protein, were first describ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1330166
更新日期:1995-08-01 00:00:00
abstract:Background:If biochemical control of acromegaly is not achieved by operation and medication, radiotherapy may be indicated. Objective:To describe fractionated radiotherapy (FRT) and stereotactic radiosurgery (SRS) regarding excess of IGF-1 and pituitary function. Design and methods:A retrospective analysis of 352 pat...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-19-0784
更新日期:2020-03-01 00:00:00
abstract::In the last few years, molecular studies on pituitary adenomas have yielded evidence supporting a primary pituitary origin of these tumors. Although the existence of genomic alterations in tumoral cells is strongly suggested by the fact that almost all pituitary adenomas are monoclonal in origin, structural genetic ab...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/eje.0.1300043
更新日期:1994-01-01 00:00:00
abstract:OBJECTIVE:Serum IGF-binding protein 2 (IGFBP2) concentrations are reduced in obese humans and increase after a prolonged period of fasting. We investigated the association between IGFBP2 levels and mortality together with other factors that are related to IGFBP2, including the metabolic syndrome and physical function. ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-12-0160
更新日期:2012-07-01 00:00:00
abstract:OBJECTIVE:Changes in many gastrointestinal peptides, including the anorexigenic peptide YY (PYY), which is produced by L cells, occur in both anorexia nervosa (AN) and obesity (OB). High PYY levels are present in AN, whereas in morbid OB fasting and postprandial PYY secretion is blunted. Somatostatin (somatotropin rele...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-11-0312
更新日期:2011-09-01 00:00:00
abstract::Major hormonal changes emerge during pregnancy. The pituitary gland is one of the most affected organs with altered anatomy and physiology. The pituitary gland is enlarged as a result of lactotroph hyperplasia. Due to physiological changes in the pituitary and target hormone levels, binding globulins, and placental ho...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-09-0923
更新日期:2010-03-01 00:00:00
abstract:CONTEXT:McCune-Albright syndrome (MAS) is a disorder caused by a post-zygotic gain-of-function mutation in the gene encoding the Gs-alpha protein. Sexual precocity, common in girls, has been reported in only 15% of boys, and little is known on the long-term evolution of MAS in males. OBJECTIVE:In a boy with MAS, we st...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-07-0494
更新日期:2008-06-01 00:00:00
abstract::Glucose is the main substrate utilized by the brain and as such multiple regulatory mechanisms exist to maintain glucose concentrations. When these mechanisms fail or are defective, hypoglycemia ensues. Due to these robust mechanisms, hypoglycemia is uncommon and usually occurs in the setting of the treatment of diabe...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/EJE-16-1062
更新日期:2017-07-01 00:00:00
abstract::Patients with adrenal insufficiency need lifelong glucocorticoid replacement, but many suffer from poor quality of life, and overall there is increased mortality. Moreover, it appears that use of glucocorticoids at the higher end of the replacement dose range is associated with increased risk for cardiovascular and me...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/EJE-08-0874
更新日期:2009-05-01 00:00:00
abstract::Growth hormone (GH) is used by athletes like bodybuilders to increase muscle strength and weight gain. On the other hand, chronic hypersecretion of GH in active acromegaly may result in outwardly hypertrophied but functionally weaker muscles. As a model for studying long-term effects of GH on muscle strength, we analy...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1330735
更新日期:1995-12-01 00:00:00
abstract::To evaluate the effects of two regimens of recombinant human GH (rhGH) on growth, bone growth and bone mineralization in GH deficient children, we studied two groups (A and B), each including 16 GH deficient children matched for sex, age, body mass index, height, height velocity and bone age/chronological age ratio (B...
journal_title:European journal of endocrinology
pub_type: 临床试验,杂志文章
doi:10.1530/eje.0.1420042
更新日期:2000-01-01 00:00:00
abstract:OBJECTIVE:The aim of the study was to evaluate the effect of intraoperative high-field (1.5 Tesla) magnetic resonance imaging (MRI) on the results of transsphenoidal surgery of GH-secreting pituitary macroadenomas. METHODS:Twenty-three acromegalic patients (mean tumor size, 25 +/- 12 mm; untreated preoperative GH, 4.2...
journal_title:European journal of endocrinology
pub_type: 临床试验,杂志文章
doi:10.1530/eje.1.01970
更新日期:2005-08-01 00:00:00
abstract:BACKGROUND:Glucocorticoids are the mainstay of immunosuppression for active moderate-severe Graves' orbitopathy (GO). AIM:To analyze the response to therapy and the contribution of glucocorticoid receptor (GR) gene polymorphisms to the therapeutic outcome of intravenous glucocorticoids (IVGC) in active moderate-severe...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/EJE-13-0611
更新日期:2013-11-22 00:00:00
abstract::Several bone matrix protein constituents, including the major component collagen type I and the hydroxyapatite binding protein, osteocalcin, have been implicated in the regulation of bone turnover. Cortical bone osteocalcin, collagen and mineral content were studied in autosomal dominant osteopetrosis type I (ADO), a ...
journal_title:European journal of endocrinology
pub_type: 杂志文章
doi:10.1530/eje.0.1300592
更新日期:1994-06-01 00:00:00
abstract::Osteopetrosis is a rare metabolic bone disease characterized by a generalized increase in skeletal mass. It is inherited in a number of mammalian species, including man, and results from a congenital defect in the development or function of the osteoclasts. The consequent impairment of bone resorption prevents formati...
journal_title:European journal of endocrinology
pub_type: 杂志文章,评审
doi:10.1530/eje.0.1340143
更新日期:1996-02-01 00:00:00