Biomedical subjects

Ralf Paschke

Publications and source records attributed to Ralf Paschke.

At least 19 recordsLinked to original sources

PubMed2006

Growth hormone induces apelin mRNA expression and secretion in mouse 3T3-L1 adipocytes.

Recently, apelin was characterised as a novel adipose-expressed factor which is upregulated in rodent and human obesity and influences cardiovascular function, as well as insulin secretion. To clarify expression and regulation of this adipokine, apelin mRNA was measured by quantitative real-time reverse transcription-polymerase chain reaction in mouse 3T3-L1 adipocytes after treatment with various hormones known to induce insulin resistance. Interestingly, apelin synthesis was significantly upregulated by growth hormone (GH) and insulin in these cells whereas TNFalpha and isoproterenol did not have any effect. Thus, 500 ng/ml GH acutely induced apelin mRNA by up to 4-fold in a time-dependent fashion with significant stimulation seen at concentrations as low as 5 ng/ml effector. Furthermore, apelin secretion was assessed by enzyme-linked immunoassay in mouse adipocytes. Here, secretion of this adipokine was induced 2.85-fold by GH. Studies using pharmacological inhibitors suggested that the positive effect of GH on apelin mRNA synthesis is at least in part mediated by janus kinase 2 and phosphatidylinositol 3-kinase. Taken together, our results show a significant induction of apelin mRNA synthesis and protein secretion by GH.

3T3-L1 Cells↗

PubMed2006

Contacts between extracellular loop two and transmembrane helix six determine basal activity of the thyroid-stimulating hormone receptor.

A number of alanine mutations in extracellular loop two (ECL2) of the thyroid-stimulating hormone receptor (TSHR) were found to increase or decrease basal activity when compared with the wild type receptor. K565A was identified as a mutant with decreased basal activity, and strongly impaired hormone induced signaling activity. To gain insights into how ECL2 mutants affect basal activity, we focused on constitutively activating pathogenic mutant I568V in ECL2, which exhibits elevated basal activity. Because our molecular model suggests that Ile-568 is embedded in an environment of hydrophobic residues provided by transmembrane helix bundle, we tested mutants in this region to identify potential interaction partner(s) for Ile-568. Indeed, the double mutant I568V/I640L (ECL2/TMH6) suppresses the increased basal activity exhibited by I568V alone. We suggest a spatial and functional relationship between ECL2 and TMH6 in which side chain interaction between Ile-568 and Ile-640 constrains the receptor in a conformation with low basal activity. Although the single mutant I640L exhibits basal activity lower than wild type, its differently branched and bulkier side chain complements the reduced side chain bulk in I568V, restoring wild type basal activity to the double mutant. This scenario is confirmed by the reciprocal double mutant I640V/I568L. The combination of basally increased activity of I640V and basally decreased activity of mutant I568L also restores basal activity of wild type TSHR. These and other mutant phenotypes reported here support a dynamic interface between TMH6 and ECL2. Disruption of this critical interface for signaling by introduction of mutations in TSHR can either increase or decrease basal activity.

Amino Acid Sequence↗

PubMed2006

Structural determinants for G-protein activation and specificity in the third intracellular loop of the thyroid-stimulating hormone receptor.

The selectivity of G-protein recognition is determined by the intracellular loops (ICLs) of seven-transmembrane-spanning receptors. In a previous study, we have shown that the N-terminal and central portions of ICL2 from F525 to D530 participate in dual Galphas-/Galphaq-protein activation by the thyroid-stimulating hormone receptor (TSHR). ICL3 is another major determinant for G-protein activation. Therefore, the aim of our study was to identify important amino acids within ICL3 of the TSHR to gain insight in more detail about its specific function for Galphas- and Galphaq-protein activation and selectivity. Single-alanine substitutions of residues in the N-terminal, middle, and C-terminal region of ICL3 were generated. N-terminal residues Y605 and V608 and C-terminal positions K618, K621, and I622 were identified as selectively important for Galphaq activation, whereas mutations in the center of ICL3 had no effect on TSHR signaling. Our findings provide evidence for an amino acid pattern in the N- and C-terminal part of ICL3, which is involved in Galphaq-mediated signaling. Furthermore, molecular modeling of interaction of TSHR ICL2 and 3 with Galphaq suggests three potential contact sites: TSHR C-terminal ICL3 with beta5-6 loop of Galphaq, TSHR ICL2 residues I523-R531 with beta2-3 loop and N-terminal helix of Galphaq, and TSHR ICL2/transmembrane helix (TMH) 3+ICL3/TMH6 with C-terminal tail of Galphaq.

Alanine↗

PubMed2006

Significance of ectodomain cysteine boxes 2 and 3 for the activation mechanism of the thyroid-stimulating hormone receptor.

Recently, we identified constitutively activating mutations at positions Asp-403, Glu-404, and Asn-406 in the third extracellular cysteine box (C-b3) of the thyroid-stimulating hormone receptor. We hypothesized that this region could act as a molecular interface between the extracellular and serpentine domain. In this study we present a model for properties of potential interaction partners for this region. Moreover, we show that Pro-400 and Pro-407 adjacent to this epitope are also important for stabilizing the partially active, basal conformation of the wild-type (WT) thyroid-stimulating hormone receptor. Furthermore, the mutation K291A in the second extracellular cysteine box (C-b2) was identified as a new constitutively activating mutation that releases the basal conformation of the WT receptor like the known tryptic cleavage in its close vicinity. Taken together, we provide an activation scenario at the C-b2/C-b3 unit. Three anchor fragments (anchors I-III) most likely constrain the basal conformation. The three anchor fragments are tightly packed. A disulfide bridge holds the C-b2/C-b3 portions in close positions. Independent of the type of conformational interference such as side chain modifications, tryptic cleavage, or hormone stimulation that act on the constrained C-b2/C-b3 WT conformation, it will always release one of the anchor fragments. Subsequently, this results in a conformational displacement of the C-b2/C-b3 portions relative to each other, inducing receptor activation.

Animals↗

PubMed2006

Evaluation of small-molecule modulators of the luteinizing hormone/choriogonadotropin and thyroid stimulating hormone receptors: structure-activity relationships and selective binding patterns.

The substituted thieno[2,3-d]pyrimidine 3 (Org 41841), a partial agonist for the luteinizing hormone/choriogonadotropin receptor (LHCGR) and the closely related thyroid-stimulating hormone receptor (TSHR), was fundamentally altered, and the resulting analogues were analyzed for their potencies, efficacies, and specificities at LHCGR and TSHR. Chemical modification of the parent compound combined with prior mutagenesis of TSHR provided compelling experimental evidence in support of computational models of 3 binding to TSHR and LHCGR within their transmembrane cores. Biochemical analysis of a specific modification to the chemical structure of 3 provides additional evidence of a H-bond between the ligand and a glutamate residue in transmembrane helix 3, which is conserved in both receptors. Several key interactions were surveyed to determine their respective biochemical roles in terms of both van der Waals dimensions and hydrogen bond capacity and the respective relationship to biological activity.

Binding Sites↗

PubMed2006

Pituitary adenoma predisposition caused by germline mutations in the AIP gene.

Pituitary adenomas are common in the general population, and understanding their molecular basis is of great interest. Combining chip-based technologies with genealogy data, we identified germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene in individuals with pituitary adenoma predisposition (PAP). AIP acts in cytoplasmic retention of the latent form of the aryl hydrocarbon receptor and also has other functions. In a population-based series from Northern Finland, two AIP mutations account for 16% of all patients diagnosed with pituitary adenomas secreting growth hormone and for 40% of the subset of patients who were diagnosed when they were younger than 35 years of age. Typically, PAP patients do not display a strong family history of pituitary adenoma; thus, AIP is an example of a low-penetrance tumor susceptibility gene.

Adenoma↗

PubMed2006

Plasminogen activator inhibitor-1 expression and secretion are stimulated by growth hormone and interleukin-6 in 3T3-L1 adipocytes.

Various adipocytokines have been described which influence insulin sensitivity and vascular function profoundly and might, therefore, potentially link obesity, insulin resistance, and atherosclerosis. Among those, plasminogen activator inhibitor (PAI)-1 is an adipose-secreted factor upregulated in obesity and insulin resistance that inhibits fibrinolysis. Furthermore, recent studies in knockout mice suggest that PAI-1 directly impairs insulin sensitivity. In the current study, the impact of growth hormone (GH) and interleukin (IL)-6 on PAI-1 mRNA synthesis and secretion was determined in 3T3-L1 adipocytes. Interestingly, 500 ng/ml GH and 30 ng/ml IL-6 increased PAI-1 secretion five-fold and 3.6-fold, respectively. Furthermore, GH and IL-6 induced PAI-1 mRNA by up to 7.3-fold, and 3.6-fold, respectively, in a time-dependent fashion with significant stimulation seen at concentrations as low as 5 ng/ml GH and 10 ng/ml IL-6. Other insulin resistance-inducing hormones which stimulated PAI-1 synthesis included insulin, TNFalpha, and dexamethasone. Studies using pharmacological inhibitors suggested that basal and GH-induced PAI-1 synthesis were at least in part mediated by p44/42 mitogen-activated protein kinase but not janus kinase 2 and phosphatidylinositol 3-kinase. Taken together, our results show a differential regulation of PAI-1 mRNA by insulin resistance-inducing hormones including GH and IL-6.

3T3-L1 Cells↗

PubMed2006

Somatic VHL gene alterations in MEN2-associated medullary thyroid carcinoma.

BACKGROUND: Germline mutations in RET are responsible for multiple endocrine neoplasia type 2 (MEN2), an autosomal dominantly inherited cancer syndrome that is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and parathyroid hyperplasia/adenoma. Recent studies suggest a "second hit" mechanism resulting in amplification of mutant RET. Somatic VHL gene alterations are implicated in the pathogenesis of MEN2 pheochromocytomas. We hypothesized that somatic VHL gene alterations are also important in the pathogenesis of MEN2-associated MTC. METHODS: We analyzed 6 MTCs and 1 C-cell hyperplasia (CCH) specimen from 7 patients with MEN2A and RET germline mutations in codons 609, 618, 620, or 634, using microdissection, microsatellite analysis, phosphorimage densitometry, and VHL mutation analysis. RESULTS: First, we searched for allelic imbalance between mutant and wild-type RET by using the polymorphic markers D10S677, D10S1239, and RET on thyroid tissue from these patients. Evidence for RET amplification by this technique could be demonstrated in 3 of 6 MTCs. We then performed LOH analysis using D3S1038 and D3S1110 which map to the VHL gene locus at 3p25/26. VHL gene deletion was present in 3 MTCs. These 3 MTCs also had an allelic imbalance between mutant and wild-type RET. Mutation analysis of the VHL gene showed a somatic frameshift mutation in 1 MTC that also demonstrated LOH at 3p25/26. In the 2 other MTCs with allelic imbalance of RET and somatic VHL gene deletion, no somatic VHL mutation could be detected. The CCH specimen did neither reveal RET imbalance nor somatic VHL gene alterations. CONCLUSION: These data suggest that a RET germline mutation is necessary for development of CCH, that allelic imbalance between mutant and wild-type RET may set off tumorigenesis, and that somatic VHL gene alterations may not play a major role in tumorigenesis of MEN2A-associated MTC.

Carcinoma, Medullary↗

PubMed2006

Isoproterenol stimulates monocyte chemoattractant protein-1 expression and secretion in 3T3-L1 adipocytes.

Recently, monocyte chemoattractant protein (MCP)-1 has been characterized as a novel adipocytokine upregulated in obesity and insulin resistance which impairs insulin signaling in muscle and fat in vitro. Growing evidence, on the other hand, suggests that increased activity of the sympathetic nervous system is an integral part in the development of insulin resistance. In the current study, the impact of the beta-adrenergic agonist isoproterenol on MCP-1 mRNA synthesis and secretion was determined in 3T3-L1 adipocytes. Interestingly, isoproterenol increased MCP-1 secretion 3-fold. Furthermore, 10 microM isoproterenol acutely induced MCP-1 mRNA by up to 5.3-fold in a time-dependent fashion with significant stimulation seen at concentrations as low as 0.3 microM effector. Studies using pharmacological inhibitors suggested that basal and isoproterenol-induced MCP-1 expressions are mediated via beta-adrenergic receptors and protein kinase A. Moreover, acute activation of adenylyl cyclase by forskolin was sufficient to mimic the effects of isoproterenol. Taken together, our results demonstrate that isoproterenol induces MCP-1 expression and secretion via a classical GS-protein-coupled pathway and support the notion that MCP-1 might be an interesting novel candidate linking obesity and insulin resistance.

3T3 Cells↗

PubMed2006

Ectopic Cushing' syndrome caused by a neuroendocrine carcinoma of the mesentery.

BACKGROUND: ACTH overproduction within the pituitary gland or ectopically leads to hypercortisolism. Here, we report the first case of Cushing' syndrome caused by an ectopic ACTH-secreting neuroendocrine carcinoma of the mesentery. Moreover, diagnostic procedures and pitfalls associated with ectopic ACTH-secreting tumors are demonstrated and discussed. CASE PRESENTATION: A 41 year-old man presented with clinical features and biochemical tests suggestive of ectopic Cushing's syndrome. First, subtotal thyroidectomy was performed without remission of hypercortisolism, because an octreotide scan showed increased activity in the left thyroid gland and an ultrasound revealed nodules in both thyroid lobes one of which was autonomous. In addition, the patient had a 3 mm hypoenhancing lesion of the neurohypophysis and a 1 cm large adrenal tumor. Surgical removal of the pituitary lesion within the posterior lobe did not improve hypercortisolism and we continued to treat the patient with metyrapone to block cortisol production. At 18-months follow-up from initial presentation, we detected an ACTH-producing neuroendocrine carcinoma of the mesentery by using a combination of octreotide scan, computed tomography scan, and positron emission tomography. Intraoperatively, use of a gamma probe after administration of radiolabeled (111)In-pentetreotide helped identify the mesenteric neuroendocrine tumor. After removal of this carcinoma, the patient improved clinically. Laboratory testing confirmed remission of hypercortisolism. An octreotide scan 7 months after surgery showed normal results. CONCLUSION: This case underscores the diagnostic challenge in identifying an ectopic ACTH-producing tumor and the pluripotency of cells, in this case of mesenteric cells that can start producing and secreting ACTH. It thereby helps elucidate the pathogenesis of neuroendocrine tumors. This case also suggests that patients with ectopic Cushing's syndrome and an octreotide scan positive in atypical locations may benefit from explorative radioguided surgery using (111)In-pentetreotide and a gamma probe.

Adrenocorticotropic Hormone↗

PubMed2006

The human thyrotropin receptor is predominantly internalized by beta-arrestin 2.

The beta-arrestin-dependent endocytosis of the beta2-adrenergic receptor (beta2AR) has been demonstrated by confocal fluorescence microscopy. Furthermore, a constitutively activated beta2AR is also constitutively desensitized and down-regulated. To clarify the function of beta-arrestin 1 or 2 for TSH receptor (TSHR) desensitization and examine whether constitutively activated TSHR mutants are internalized in a different way, we investigated the TSHR trafficking in association with beta-arrestins in cotransfection experiments in HEK 293 cells using confocal laser-scanning microscopy. We found that both beta-arrestins are able to internalize the TSHR in HEK 293 cells. However, whereas the beta-arrestin 1-mediated TSHR internalization reached its maximum 20 min after TSH stimulation, the beta-arrestin 2-mediated TSHR internalization already reached its maximum 5 min after TSH stimulation. Furthermore, an increased basal desensitization and internalization of constitutively activated TSHR mutants N670S, S505N, and F631L cotransfected with beta-arrestin 2 could not be found. After TSH stimulation the constitutively activated mutants showed the same time course for internalization as the wild-type-TSHR. In summary, contrary to data obtained for the beta2AR, the constitutive activation of the TSHR does not influence the desensitization and time course for internalization of the receptor, and in agreement with findings for the FSH and LH receptors, these results characterize the TSH receptor as a member of the class A of G protein-coupled receptors, which have a higher affinity to beta-arrestin 2 than beta-arrestin 1 and do not colocalize with beta-arrestins in endosomes.

Arrestins↗

PubMed2006

A low molecular weight agonist signals by binding to the transmembrane domain of thyroid-stimulating hormone receptor (TSHR) and luteinizing hormone/chorionic gonadotropin receptor (LHCGR).

Many cognate low molecular weight (LMW) agonists bind to seven transmembrane-spanning receptors within their transmembrane helices (TMHs). The thienopyrimidine org41841 was identified previously as an agonist for the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) and suggested to bind within its TMHs because it did not compete for LH binding to the LHCGR ectodomain. Because of its high homology with LHCGR, we predicted that thyroid-stimulating hormone receptor (TSHR) might be activated by org41841 also. We show that org41841 is a partial agonist for TSHR but with lower potency than for LHCGR. Analysis of three-dimensional molecular models of TSHR and LHCGR predicted a binding pocket for org41841 in common clefts between TMHs 3, 4, 5, 6, and 7 and extracellular loop 2 in both receptors. Evidence for this binding pocket was obtained in signaling studies with chimeric receptors that exhibited improved responses to org41841. Furthermore, a key receptor-ligand interaction between the highly conserved negatively charged E3.37 and the amino group of org41841 predicted by docking of the ligand into the three-dimensional TSHR model was experimentally confirmed. These findings provide the first evidence that, in contrast to the ectodomain binding of cognate ligands, a LMW agonist can bind to and activate glycoprotein hormone receptors via interaction with their transmembrane domain.

Amino Acid Sequence↗

PubMed2006

Meta- and reanalysis of gene expression profiles of hot and cold thyroid nodules and papillary thyroid carcinoma for gene groups.

CONTEXT: There are an increasing number of studies analyzing gene expression profiles in various benign and malignant thyroid tumors. This creates the opportunity to validate results obtained from one microarray study with those from other data sets. This process requires rigorous methods for accurate comparison. OBJECTIVE: The ability to compare data sets derived from different Affymetrix GeneChip generations and the influence of intra- and interindividual comparisons of gene expression data were evaluated to build multigene classifiers of benign thyroid nodules to verify a previously proposed papillary thyroid carcinoma (PTC) classifier and to look for molecular pathways essential for PTC oncogenesis. METHODS: Gene expression profile data sets from autonomously functioning and cold thyroid nodules and from PTC were analyzed by support vector machines. GenMAPP analysis was used for PTC data analysis to examine the expression patterns of biologically relevant gene sets. RESULTS: Only intraindividual reference samples allowed the identification of subtle changes in the expression patterns of relevant signaling cascades, such as the MAPK pathway in PTC. Using an artificial intelligence approach, the autonomously functioning and cold thyroid nodule multigene classifiers were derived and evaluated by cross-comparisons. CONCLUSION: We recommend defining classifiers within one generation of gene chips and subsequently checking them across different array generations. Using this approach, we have demonstrated the specificity of a previously reported PTC classifier on an independent collection of benign tumors. Moreover, we propose multigene classifiers for different types of benign thyroid nodules.

Algorithms↗

PubMed2006

Comparison of differential gene expression of hot and cold thyroid nodules with primary epithelial cell culture models by investigation of co-regulated gene sets.

Both autonomously functioning thyroid nodules (AFTNs) and cold thyroid nodules (CTNs) are characterized by an increased proliferation, however, they have opposite functional activities. Therefore, with the aim to further understand the distinct molecular pathology of each entity and to discover common mechanisms like those leading to increased proliferation in both, AFTNs and CTNs, we now compared gene expression of AFTNs and CTNs with in vitro model systems (TSH-stimulated and ras-transfected primary cultures (PC)) whose gene expression patterns can be attributed to specific molecular alterations. Since combinations of co-regulated genes are more likely to reveal molecular mechanisms, we used a procedure which groups co-regulated genes within "gene sets". We found a co-regulated gene set in the AFTNs that overlaps with differential expression in TSH-stimulated PCs but not in CTNs or ras-transfected PCs. In addition to thyroid peroxidase and sialyltransferase 1, this set of co-regulated genes comprises metallothioneins and the G-protein-coupled receptor 56. Although their role in the thyroid is unknown so far, their appearance in one group indicates a functional relevance in TSH-TSH receptor-stimulated mechanisms. Furthermore, we identified down-regulated gene sets with concordant expression patterns in AFTNs, CTNs and ras-transfected PCs. However, these expression patterns are not of relevance in the TSH-stimulated PCs. These findings suggest that TSH-stimulated PCs can be used as a model of increased thyroid function (AFTNs), whereas the ras-transfected PCs better reflect the increased proliferation of both AFTNs and CTNs.

Algorithms↗

PubMed2006

Impaired enteral levothyroxine absorption in hypothyroidism refractory to oral therapy after thyroid ablation for papillary thyroid cancer: case report and kinetic studies.

We present a 49-year-old patient suffering from hypothyroidism (thyrotropin [TSH], 20-80 mU/L) refractory to oral levothyroxine (LT(4)) substitution after total thyroidectomy and radioiodine therapy for papillary thyroid cancer. Extensive, repetitive work-up excluded small bowel, liver, and pancreatic disease and drug interactions. Triiodothyronine/thyroxine (T(3)/T(4)) antibodies were negative and reverse T(3) levels were normal. Supervised absorption tests of several LT(4) preparations in increasing dosages (250-1500 microg/d) confirmed an insufficient rise in serum T(4) levels following oral drug administration. Thus, intravenous LT(4) application (5 times per week) was commenced to restore at least normal range TSH levels. Repetition of absorption tests 1 year later, after a documented period of more than 3 months of stable euthyroidism, showed a considerable improvement of intestinal LT(4) uptake. Subsequently, the patient was managed on large doses of oral LT(4) (1500-2100 microg/d) alone, but this was found to be insufficient so that continuous intravenous LT(4) was administered via a morphine pump device to ultimately achieve stable euthyroidism. Of note, at 4-year follow-up there was no evidence of recurrent or metastasized papillary thyroid cancer. The reason for the disturbed intestinal LT(4) absorption in this patient remains unresolved. However, we would like to suggest the possibility of a specific intestinal uptake deficit, which will only become apparent in the case of previous thyroid ablation.

Administration, Oral↗

PubMed2006

Toward the application of proteomics to human thyroid tissue.

CONTEXT: In this paper we describe for the first time a systematic approach to proteome analysis of human thyroid tissue. OBJECTIVE AND DESIGN: We report different methods to decrease the complexity of the human thyroid tissue proteome by applying different solubilization strategies and correcting for thyroglobulin protein abundance; to increase the protein resolution by prefractionation and by the use of narrow-range pH gradients; to detect proteins using sensitive and quantitative stains; and to identify soluble and membrane-bound thyroid tissue proteins by mass spectrometry analysis. MAIN OUTCOME/RESULTS: We found that buffers containing high contents of urea and detergents allow the best solubilization of human thyroid tissue proteins; highly variable abundance of thyroglobulin is a major pitfall of human thyroid proteome analysis, which in contrast to centrifugal ultrafiltration, size-exclusion chromatography and microdissection, can be countered best by adapting the protein amount to the thyroglobulin content per sample; prefractionation leads to a significant enrichment of proteins and allows subcellar localization of thyroid proteins; application of narrow-range immobilized pH gradient (IPG) strips allows further improvement of spot detection and separation; and protein detection with the fluorescent stain ruthenium II Tris bathophenanthroline disulfonate (RuBPs) is a highly sensitive and reliable tool for quantitative proteome analysis. Finally, in a pilot study of four patients with benign nodular thyroid disease we found that the described procedures allow a highly reproducible detection and identification of alterations in protein expression between nodular and corresponding normal thyroid tissues. CONCLUSIONS: Application of the described methods provides the basis for a highly sensitive and reproducible proteome analysis of the human thyroid, providing an additional novel tool to elucidate complex proteins changes in human thyroid biology as well as pathophysiology of human thyroid disease.

Cell Fractionation↗

PubMed2006

Effect of a 4 week physical training program on plasma concentrations of inflammatory markers in patients with abnormal glucose tolerance.

OBJECTIVE: Subclinical chronic inflammation could be a unifying factor linking type 2 diabetes (T2D) and atherosclerosis. The beneficial effects of physical activity on a reduced risk of coronary heart disease could at least in part be mediated by improved markers of inflammation. RESEARCH DESIGN AND METHODS: The aim of this study was to determine the effect of 4 weeks of physical training on plasma concentrations of interleukin (IL)-6, C-reactive protein (CRP), adiponectin and IL-10 in 60 individuals with normal glucose tolerance, impaired glucose tolerance (IGT) or T2D. RESULTS: In patients with IGT and T2D, significant improvement in body fat, fitness level, glucose metabolism and insulin sensitivity after 4 weeks of physical training was associated with significantly improved plasma concentrations of adiponectin and CRP, but not IL-6. Regression analysis demonstrated only for the anti-inflammatory parameters adiponectin and IL-10 a significant relationship with the decrease in fasting plasma glucose, whereas changes in IL-6 and CRP were not significantly related to changes in fasting plasma glucose, body fat, maximal oxygen uptake, or insulin sensitivity. In a multivariate linear regression analysis, only changes in circulating adiponectin, fasting plasma glucose and percentage body fat were determinants of changes in insulin sensitivity. CONCLUSIONS: Physical training was associated with a near normalization of adiponectin and CRP plasma concentrations in subjects with IGT and T2D. Increased insulin sensitivity after training was most strongly related to changes in adiponectin plasma concentrations, in fasting plasma glucose and percentage body fat, whereas changes in IL-6, IL-10 and CRP plasma concentrations did not significantly contribute to improved insulin sensitivity.

Adiponectin↗

PubMed2006

Similar prevalence of somatic TSH receptor and Gsalpha mutations in toxic thyroid nodules in geographical regions with different iodine supply in Turkey.

OBJECTIVE: Differences in iodine intake could account for the variable prevalences reported for somatic TSH receptor (TSHR) mutations in toxic thyroid nodules (TTNs). However, this question has not been settled, since no study has yet determined the TSHR mutation prevalence in regions with different iodine supplies in the same population using the same methodology. Therefore, we studied the prevalence of somatic TSHR mutations in TTNs from patients living in iodine-deficient or -sufficient regions in Turkey. DESIGN AND METHODS: We screened 74 TTNs for somatic TSHR mutations. Exons 9 and 10 of the TSHR and 7 and 8 of the Gsalpha were screened by denaturing gradient gel electrophoresis. Determination of X-chromosome inactivation was used for clonality analysis. RESULTS: TSHR mutations were identified in 52 (70.2%) of 74 TTNs. A Gsalpha mutation was identified in one TTN. Three new TSHR mutations were detected (A627V, I640K, I486N). No significant difference between frequencies of TSHR mutations in iodine deficient/sufficient regions was found. The frequency of non-random X-chromosome inactivation was similar in iodine-sufficient or -deficient regions and in TSHR mutation positive or negative hot nodules. CONCLUSIONS: These findings suggest that TTNs in iodine deficient/sufficient areas predominantly arise from aberrant growth of a single cell. Our results suggest that neither the prevalence of TSHR mutations nor that of monoclonal TTNs is related to iodine supply.

Adult↗