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Secretagogin is a recently cloned human [beta]-cell-expressed EF-hand [Ca.sup.2+]-binding protein. Converging evidence indicates that it exerts [Ca.sup.2+] sensor activity and is involved in regulation of insulin synthesis and secretion. To obtain a potent tool for the extension of its functional analysis in rat in vitro systems, we cloned the rat homolog of human secretagogin. Using comparative sequence analysis, immunostaining, and immunoblotting, we demonstrated a high degree of sequence homology and similar tissue expression patterns of human and rat secretagogin. Highest rat secretagogin expression levels were found in pancreatic [beta]-cells. On the basis of newly generated anti-rat secretagogin antibodies, we established a rat secretagogin-specific sandwich capture ELISA and demonstrated release of secretagogin from viable Rin-5F cells. Dexamethasone treatment of Rin-5F cells resulted in an increased secretagogin release rate, which was inversely correlated with insulin secretion. In contrast, the secretagogin transcription rate was markedly reduced. This resulted in a decreased intracellular secretagogin content under the influence of dexamethasone. Sucrose gradient cell fractionation analysis of Rin-5F cells confirmed the predominant cytosolic localization of secretagogin, with only limited association of secretagogin with insulin granules. The loss of intracellular secretagogin alter dexamethasone treatment affected predominantly the insulin granule-associated secretagogin fractions. The sequence homology and the comparable tissue expression patterns of human and rat secretagogin indicate conserved intracellular functions. The effects of dexamethasone on the total secretagogin content in Rin-5F cells and on its intracellular distribution might result in an impaired [Ca.sup.2+] sensitivity of dexamethasone-treated insulin-secreting cells. EF-hand protein; insulin granules; dexamethasone; calcium sensor doi:10.1152/ajpendo.00055.2007

The design and analysis of the mechanical structure of the Nuclotron-type SIS100 magnets are studied. Results suggest that the coil support structure is suitable for better stabilization of the coil, while also offering other advantages.

For the FAIR project's SIS100 synchrotron, a series of 113 fast ramped dipoles will be built. This contribution reports about the manufacturing process of the “First Of Series” (FOS) dipole. Special attention is given to the progress achieved during the technological optimization phase for appropriate implementation of a new magnet design taking into account the experience obtained with prototypes. This work was performed jointly by Babcock Noell GmbH (BNG) and GSI. We describe the crucial steps of the manufacturing and assembly processes. Experience from the manufacturing of the cable is reported and the tooling and production process will be discussed. [ABSTRACT FROM PUBLISHER]

Abstract: In a gene chip analysis of common pituitary tumor types, one of the genes with the most impressive tissue-specific expression regulation was delta-like 1 (DLK1), which was strongly expressed in GH-secreting (GH-S) pituitary tumors. In addition to pituitary adenomas, various endocrine tumors were subjected to real-time-quantitative PCR revealing high expression of DLK1 in normal pituitary tissue, in GH-S-, in one prolactin-secreting pituitary adenoma and in pheochromocytomas. Additionally, three DLK1 gene-derived subvariants were identified. The first, lacking 204bp—coding for epidermal growth factor-like domain 6 and parts of the juxtamembrane region—was named Secredeltin. In the other two splice variants (named Brevideltin and Brevideltinin), a stop codon is introduced due to a frame-shift, leading to truncated proteins of 204 and 213aas, respectively. [Copyright &y& Elsevier]

Mounting evidence suggests cell cycle dysregulation is involved in the pathogenesis of Alzheimer's disease (AD) and that this failure is systemic, affecting not only neurons but also peripheral blood lymphocytes (PBLs). This study analyzed if differences in PBL proliferation activity could be used as a diagnostic biomarker for AD. CD69 and CD28 expressions on PBL T, B, and monocyte cells were measured by flow cytometry with and without mitogenic stimulation in healthy controls (HC), probable AD, and Parkinson's disease dementia (PDD) subjects. Univariate and multivariate scoring models were employed to evaluate the data relative to the clinical diagnoses. Eleven CD expression markers were significantly altered in AD subjects compared with a mixed pool of PDD and HC subjects using univariate models. Using multivariate models, seven CD expression markers were significantly altered in AD subjects compared with PDD subjects. Multivariate scoring demonstrated up to a 91% positive and 92% negative agreement with subject clinical diagnosis and had little correlation with the severity of dementia. Present findings suggest that with further development this analytical and multivariate modeling procedure could aid the current differential diagnosis of Alzheimer's disease., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Renal cell carcinomas are divided into several subgroups according to their histopathologic characteristics. The outcome, therapy responses, and the applicability of molecular-targeted therapies depend on the tumor classification and on the tumor stage. Recent advances within the biomarker research facilitated the exact classification of the molecular character of the renal tumor. For example, the calcium-binding proteins parvalbumin and S-100A1 are characteristically expressed in renal cell carcinoma subgroups. This led us to investigate the expression of the novel calcium-binding protein secretagogin in renal cell carcinomas. Tissue microarray cylinders including 94 clear-cell renal cell carcinomas, 61 non-clear-cell renal cell carcinomas (37 papillary renal cell and 24 chromophobe carcinomas), and 30 oncocytomas were analyzed by immunohistochemistry. This showed remarkable secretagogin expression in 37% of the clear-cell renal cell carcinomas. Non-clear-cell renal cell carcinomas and oncocytomas were completely negative. Consequently performed immunoblotting analyses confirmed this expression profile. Because publicly available data direct toward a formation of a hierarchical cluster of secretagogin overexpressing clear-cell renal cell carcinomas, we conducted a clinical follow-up of the patients with clear-cell renal cell carcinoma. This revealed significantly more metastasis within the secretagogin-positive clear-cell renal cell carcinoma subgroup (49% versus 28%; P < .05). In conclusion, we report on detection of the novel calcium-binding protein secretagogin within a subgroup of clear-cell renal cell carcinomas. The increased metastasis rates within the secretagogin-positive subgroup of clear-cell renal cell carcinomas direct toward a clinical impact of our findings., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Frequent concomitant manifestation of type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) has been recently demonstrated by epidemiological studies. This might be due to functional similarities between β-cells and neurons, such as secretion on demand of highly specific molecules in a tightly controlled fashion. An additional similarity represents the age-related alteration of hyperphosphorylated tau in AD patients. Similarly, alterations have been identified in β-cells of T2DM patients. The islet amyloid polypeptide has been associated with β-cell apoptosis. As a consequence of increasing age, the accumulation of highly modified proteins together with decreased regenerative potential might lead to increasing rates of apoptosis. Moreover, reduction of β-cell replication capabilities results in reduction of β-cell mass in mammals, simultaneously with impaired glucose tolerance. The new challenge is to learn much more about age-related protein modifications. This can lead to new treatment strategies for reducing the incidence of T2DM and AD.

Neuropeptide Y (NPY) is an important hormone in appetite regulation. Although the contribution of NPY to metabolic disease has been previously demonstrated, there are only a few reports addressing NPY plasma levels under distinct diabetic conditions. In this study we evaluated NPY plasma levels in diabetes mellitus type 2 (DM2) patients with (n=34) and without (n=34) diabetic polyneuropathy (PNP) and compared these with age and gender matched healthy controls (n=34). We also analyzed NPY plasma levels in gestational diabetes mellitus (GDM) patients with age and pregnancy-week matched controls with normal glucose tolerance (NGT). NPY concentration was determined using a commercially available radioimmunoassay kit. In addition, metabolic parameters of DM2 and GDM patients were recorded. One-way ANOVA tests with appropriate post hoc corrections showed elevated levels of NPY in DM2 patients with and without PNP when compared with those of healthy controls (122.32±40.86 and 117.33±29.92 vs. 84.65±52.17 pmol/L; p<0.001, p<0.005, respectively). No significant difference was observed between diabetic patients with and without PNP. The NPY levels were similar in the GDM group and in pregnant women with NGT (74.87±14.36 vs. 84.82±51.13 pmol/L, respectively). Notably, the NPY concentration correlated positively with insulin levels in DM2 patients (R=0.35, p<0.01). Our data suggest a potential involvement of circulating NPY in DM2 pathology., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

We detected distinct plasma concentration profiles of S100B, neuropeptide Y, and secretagogin in 3 of 191 patients enrolled in a previous study investigating brain-tissue-related markers in the blood of patients with atrial fibrillation. Intriguingly, 2 of these 3 patients, both of whom were without neurological symptoms at the time of blood sampling, were diagnosed with malignant glioma (MG) approximately 1 year later. To our knowledge, this is the first report indicating that distinct blood biomarker profiles may be detected long before clinical manifestation of MG.

Tauopathies have been associated with Alzheimer's disease (AD), which frequently manifests together with diabetes mellitus type 2. Calcium-binding proteins such as the recently identified secretagogin (SCGN) might exert protective effects. As pancreatic beta-cells and neurons share common electrophysiological properties, we investigated the appearance of TAU (listed as MAPT in the HUGO and MGI Databases) protein at the islets of Langerhans and beta-cell-derived cell lines which highly express the neuroendocrine-specific protein SCGN. Six predominant TAU isoforms could be identified by immunoblotting, which formed TAU deposits detectable by immunofluorescence and sarkosyl-insoluble pellets. Using GST-SCGN pull-down assays, a calcium-dependent SCGN-TAU interaction was found. In this line, sucrose density gradient fractionation and differential ultracentrifugation studies of TAU and SCGN revealed co-appearance of both proteins. Co-localization of TAU and SCGN within insulinoma cells and islets of Langerhans mainly restricted to insulin-positive beta-cells was demonstrated by confocal microscopy. Motivated by these findings, we looked if SCGN overexpression could exert protective function on Rin-5F cells, which showed differences in TAU levels. Testing the vulnerability of Rin-5F clones by MTT assay, we revealed that high TAU levels going along with highest TAU aggregates could not be antagonized by high levels of SCGN protein. Our findings demonstrated for the first time the association of TAU and the calcium-binding protein SCGN and support earlier results implicating that beta-cells might represent an extra cerebral site of tauopathy.

Background: Angiopoiesis and angiopoietic growth factors are of considerable importance in the development and progression of intracranial tumours. However, knowledge of the plasma detectability of distinct angiogenic factors in patients with brain tumour is very limited. This study evaluates the plasma concentrations of the angiogenic factors angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF) and platelet-derived growth factor BB (PDGF-BB) in patients with brain tumour., Patients and Methods: Plasma samples of 78 patients suffering from various types of intracranial tumours (glioblastoma multiforme, GBM, n = 22; astrocytoma, n = 12; meningioma, n = 16; and intracranial metastasis, n = 28) were analysed. For determination of plasma concentrations of angiogenic factor, highly specific enzyme-linked immuno sorbent assays (ELISAs) were used., Results: Ang-2 plasma concentration in GBM patients was significantly lower when compared with that in patients with meningioma and intracranial metastasis. Highest levels of VEGF concentrations were detected in plasma derived from patients suffering from meningioma. Interestingly, VEGF plasma levels depended on the number of intracranial lesions, with significantly higher concentrations in patients with 3 or more lesions when compared with those with 2 or fewer lesions. However, no correlation between the survival time of the patients and the plasma levels of the tested growth factors was obtained. Plasma levels of PDGF-BB did not differ between the individual tumour groups., Conclusion: The detectability of the angiogenic factors Ang-2 and VEGF, as well as of PDGF-BB, in the plasma of patients suffering from various types of brain tumours is described. The plasma detectability of the individual angiopoetic factors seems to depend at least partly on the tumour type as well as on tumour progression. This might be of prognostic and therapeutic relevance.

Objective: Identification of plasma markers indicative for atrial fibrillation-associated silent brain lesions., Design and Methods: 1. Comparative determination of the plasma concentrations of secretagogin, S100B, neuropeptide Y, brain fatty acid binding protein, matrix metalloprotease 9, brain natriuretic peptide, and of D-Dimer in 222 patients with atrial fibrillation and 28 controls by immunoassays. 2. Correlation of the biochemical marker plasma concentration with the extent of silent white matter brain lesions, as determined by the Fazekas score and N-acetylaspartate-spectroscopy., Results: 1. Plasma concentrations of brain natriuretic peptide, of neuropeptide Y, and of matrix metalloprotease 9 were significantly higher (all with a p<0.05) in patients suffering from atrial fibrillation than in control subjects. 2. Brain natriuretic peptide correlated significantly with the Fazekas score (R=0.41; p<0.005). 3. Brain natriuretic peptide plasma concentrations were significantly higher in patients with a pathological N-acetylaspartate magnetic resonance-spectrometry (p<0.05)., Conclusion: Brain natriuretic peptide plasma concentrations correlate with the extent of atrial fibrillation-associated silent brain lesions.

Problem: Expression of heat shock proteins has been described in different tissues relevant to human reproduction, including placenta. AlphaB-crystallin is a member of the small heat shock protein family (sHsp) exerting biologically important chaperon functions., Method of Study: Immunofluorescence; immunoblot analysis; quantitative real-time-PCR; CpG island methylation analysis., Results: In this study, we once again describe the expression of alphaB-crystallin in the stroma of the placental villi and in the cytoplasm of decidual cells by immunofluorescence. In contrast, Hsp27--another sHsp family member--was detected exclusively in the syncytiotrophoblast layer. This varying expression pattern provides additional support to earlier reports of functional differences between both proteins. Semi-quantitative immunoblot analysis of placenta tissue specimens (n = 6) revealed Hsp27 expression exceeding that of alphaB-crystallin, albeit with interindividual variations. Inter-individual alphaB-crystallin expression variations were confirmed by quantitative RT-PCR. CpG island methylation was ruled out as the underlying cause for the inter-individual alphaB-crystallin expression variations. However, the expression extent of GATA3, which is a transcription factor with corresponding elements within the alphaB-crystallin gene (CRYAB) promoter, paralleled that of alphaB-crystallin. We demonstrated remarkable GATA3 expression in placental tissue, exceeding that of other endocrine organs., Conclusion: We can conclude that the differential expression patterns of alphaB-crystallin and Hsp27 indicate functional differences between these highly related proteins in placental tissues.

In the present study, we characterized the gene product of open reading frame 3 encoded at human chromosome 20 (C20orf3), which represents a member of the lactonohydrolase super family. Multiple-tissue Northern blot analysis showed ubiquitous expression of the 2.4 kb transcript coding for 416 amino acids, with highest levels in human liver, placenta and kidney. After recombinant production of protein variants in Escherichia coli and insect cells, antibodies directed against different epitopes within the C20orf3 gene product were generated. Using these immunoreagents, protein expression was demonstrated in the liver, and glomerular and tubular structures of the kidney, as well as in endothelial cells and arterial wall. Positive staining was also observed at the pancreatic islets of Langerhans. Using immunoblotting, we identified three size variants. In line with the results of in silico analysis demonstrating a single transmembrane sequence (amino acids 40-61) at the N-terminus of the full-length protein, FACS cell-surface staining confirmed a mainly extracellular localization of the full-length protein. Sucrose density gradient cell fractionation revealed membrane association of the dominant 50 kDa variant in HepG2 and Rin-5F cells. The finding of a strong arylesterase activity with beta-naphthyl acetate and phenyl acetate of the C20orf3 protein-containing fractions suggests potential involvement of this protein in enzymatic processes. C20orf3 promoter-driven reporter assays, which were verified by gene-specific RT-qPCR (real-time quantitative PCR) showed a strong inhibitory effect of human serum on transcription using the HEK-293 human embryonic kidney cell line. In conclusion, we characterized the structure and expression pattern of the C20orf3 gene product. According to a series of analogies with PON (paraoxonase) family members, we speculate that the C20orf3 gene product represents a new member of this important protein family present at the cellular level.

Aiming to identify signalling pathways relevant for ss-cell growth we performed an explorative micro-array analysis comparing the gene expression profiles of three human insulinomas and one normal pancreatic islet preparation. This revealed an insulinoma-associated down-regulation of the transforming growth factor beta 1 (TGF-beta1) and its target genes. Comparative quantitative real-time PCR (qRT-PCR) including an expanded sample number of both insulinomas (n=9) and pancreatic islet preparations (n=4) confirmed the decreased TGF-beta1 expression and its target molecules (TGFBI, NNMT, RPN2) in insulinomas. Similarly, TGF-beta1 immunofluorescence analysis revealed reduced expression in insulinomas when compared to pancreatic islets. In contrast, TGFBR2 (transforming growth factor beta receptor II) was found up-regulated. However, the consistent down-regulation of the TGF-beta1 targets TGFBI (transforming growth factor, beta-induced), NNMT (nicotinamide N-methyltransferase), RPN2 (ribophorin II) indicates that the parallel up-regulation of TGFBR2 does not compensate for the only marginal TGF-beta1 expression levels in insulinomas. TGFBR2 expression was confirmed at the protein level in insulinomas. SMAD2/3 protein expression was found at higher levels in human pancreatic islets when compared with insulinomas by dual colour confocal microscopy. TGF-beta1 signalling is known to be involved in cell replication and is abrogated in ductal pancreatic tumours. The down-regulation of TGF-beta1 expression and its target molecules in insulinomas is a new aspect of this cytokine. Our data underline parallels in endocrine and exocrine pancreatic tumour development, which may implicate common progenitor cells.

Disturbed calcium homeostasis plays a crucial role in the aetiology of Alzheimer's disease (AD) and the aging process. We evaluated immunoreactivity of secretagogin, a recently cloned calcium binding protein, in hippocampus and adjacent entorhinal cortex of 30 neuropathologically examined post mortem brains (m:f=12:18; mean age, 79.8+/-15.1 years). The study group consisted of 15 cases fulfilling the criteria for high probability of AD according to the NIA-Reagan Institute Criteria and 15 cases with no to medium probability. Sections were incubated with secretagogin-specific antibodies and the number of immunoreactive neurons as well as staining intensities in both neurons and neuropil were assessed. Both cellular and neuropil immunoreactivity were restricted to subiculum and Ammons horn. Cellular immunoreactivity was further restricted to pyramidal neurons and showed a hierarchical distribution: the mean percentage of immunoreactive neurons was highest in sector CA3 (64.41%), followed by CA2 (44.09%), CA4 (34.38%), CA1 (10.9%), and the subiculum (2.92%; P<0.001, except CA2-CA4, P>0.05), while it did not differ significantly between groups with different degrees of AD pathology. The pattern of secretagogin immunoreactivity resembles that of calcium sensor proteins as it is restricted to a subset of neurons and therefore secretagogin could serve highly specialized tasks in neuronal calcium signalling.

To identify proteins with colorectal cancer-specific regulation, comparative 2-DE of individual-matched normal and neoplastic colorectal tissue specimens was performed. We found 15 protein spots with concordantly increased and 20 protein spots with concordantly decreased intensity in tumor tissue (expression regulation more than fivefold). Nine of these proteins were identified by MS/MS. Interestingly, one of the proteins, which exhibited a marked down-regulation in colorectal cancer tissues, was the recently identified endocrine cell-expressed protein secretagogin. The reduction of the secretagogin content in colorectal cancer tissues was confirmed by comparative immunoblotting (n = 17) and RT-PCR (n = 22) as well as by immunohistochemistry (n = 45) of individual-matched neoplastic and normal colorectal tissue specimens. Immunohistochemistry revealed absence of secretagogin-expressing cells in most of the colorectal cancer tissue specimens. However, some colorectal cancers were characterized by secretagogin-expressing cells. In normal mucosa, positively stained cells exhibited a neuroendocrine cell-characteristic morphology and mucosal location. In colorectal cancer tissues, secretagogin-expressing cells were characterized by a malignant morphology. Our findings might represent the basis for the clinical application of secretagogin as a biomarker for a distinct subgroup of colorectal cancers.

Objective: Long-term in vitro maintenance of human insulin-secreting insulinoma cells., Methods: (1) Cell culture of ex vivo-derived insulinoma cell suspensions from 8 individual human donors, using various cell culture medium supplementations; (2) determination of insulin synthesis and secretion using immunocytochemistry and insulin and pro-insulin radioimmunoassays; (3) nestin-immunostaining of long-term in vitro grown insulinoma cell suspensions, and (4) phase-contrast light microscopy for analyzing the in vitro growth characteristics of the insulinoma cells., Results: (1) Parallel persistence of in vitro insulinoma cell proliferation as well as insulin-synthesizing and -secreting capacity depended on both the co-culture of insulinoma cells with human fibroblasts and the supplementation of the cell culture medium with tissue culture supernatant derived from the rodent pituitary adenoma cell line GH-3; (2) immunostaining for insulin and secretagogin confirmed the neuroendocrine origin of the insulinoma cells grown in vitro; (3) insulin secretion capability persisted up to an observation period of 25 weeks; (4) insulin secretion rates after 6 weeks of in vitro growth ranged from 3.5 to 83.3 muU/ml/h/60,000 cells plated, and (5) after long-term in vitro growth of insulinoma-derived cell suspensions with persistent insulin-secreting capacity, nestin staining was observed predominantly in co-cultured fibroblasts., Conclusion: Our data describe for the first time the long-term in vitro culture of insulin-secreting human insulinomas and highlight the importance of beta-cell trophic factors for insulinoma cell growth.

Expression of the small heat shock protein alphaB-crystallin in differentiated thyroid tumors has been described recently. In this study, we investigated the molecular mechanisms that affect the expression of alphaB-crystallin in benign goiters (n = 7) and highly malignant anaplastic thyroid carcinomas (ATCs) (n = 3). AlphaB-crystallin expression was compared with that of Hsp27-1. Immunoblot and quantitative real-time (RT) polymerase chain reaction revealed marked downregulation of alphaB-crystallin in all the tested ATCs and the ATC-derived cell line C-643 . In contrast, considerable expression of Hsp27-1 in benign and malignant thyroid tissue was demonstrated. Immunofluorescence analysis revealed no relevant topological differences between benign and malignant thyrocytes in the cytoplasmic staining of both proteins. Consistent and marked downregulation of TFCP2L1 was identified as one of the main mechanisms contributing to CRYAB gene silencing in ATCs. In addition, CRYAB gene promoter methylation seems to occur in distinct ATCs. In silico analysis revealed that the differential expression of alphaB-crystallin and Hsp27-1 results from differences between the alphaB-crystallin and Hsp27-1 promoter fragments (712 bp upstream from the transcriptional start site). Biological activity of the analyzed promoter element is confirmed by its heat shock inducibility. In conclusion, we demonstrate downregulation of alphaB-crystallin expression in highly dedifferentiated ATCs because of a tumor-specific transcription factor pattern. The differential expression of alphaB-crystallin and Hsp27-1 indicates functional differences between both proteins.

Multiple RET proto-oncogene transcripts, due to genomic variations and alternate splicing, have been described. To investigate endocrine tumor tissue characteristic RET proto-oncogene expression, we performed quantitative RT-PCR, Northern blot and Southern blot analyses of benign and malignant endocrine-derived tissues. We newly describe RET proto-oncogene expression in carcinoid-, gastrinoma- and insulinoma-derived tissue samples. In addition, the presence of a 3'-terminally truncated RET proto-oncogene mRNA variant in benign and malignant thyroid neoplasias, as well as in a pheochromocytoma, an ovarian carcinoma and a medullary thyroid carcinoma, is demonstrated. Southern blot analysis revealed no evidence of gross RET proto-oncogene rearrangements or deletions. As the underlying cause for a bi-allelic TaqI restriction fragment length polymorphism (RFLP), a C (allele 1)/T (allele 2) transition within intron 19, was characterized. This polymorphism is close to a recently described polyadenylation site and lies within a binding site for the nucleic acid binding protein Pbx-1. Screening of healthy subjects and of patients suffering from various endocrine malignancies revealed exclusively allele 1 homozygous and allele 1/allele 2 heterozygous genotypes. Heterozygous genotypes were found in a significantly higher percentage in samples derived from endocrine tumor patients when compared with those from healthy control subjects. Homozygosity for allele 2 was found exclusively in somatic DNA derived from endocrine tumors with high malignant potential. Analysis of DNA derived from varying regions within individual anaplastic thyroid carcinomas revealed an allele 1/allele 2 switch of the RFLP banding pattern, indicating loss of heterozygosity at the RET proto-oncogene locus. In conclusion, our data demonstrate presence of a 5'-terminal RET proto-oncogene transcript in endocrine tissues and reveal a bi-allelic RET proto-oncogene polymorphism. A heterozygous genotype for this polymorphism is found in a considerable number of endocrine tumor patients.

We describe two new variants of the recently identified hexa-EF-hand calcium binding protein secretagogin. The first variant (secretagogin-R22) is characterized by one single amino acid exchange (Q/R) at codon 22, most likely due to RNA editing. The second variant of secretagogin (setagin) consists of 49 amino acids. Due to a frame shift, only the first 27 amino acids are identical to secretagogin. We demonstrate that this protein truncation results in complete loss of the calcium binding capacity. Setagin expression was found in considerable amounts in the pancreas whereas secretagogin and secretagogin-R22 were also found in the central nervous system and organs containing neurendocrine cells.

Our previous microarray-based studies identified secretagogin to be highly expressed in normal colon mucosa compared to basal expression in colon adenocarcinomas. The aim of this study was to analyze the differential expression of secretagogin in normal mucosa, adenocarcinomas, and neuroendocrine tumors. Western blotting, immunohistochemistry, immunofluorescence microscopy and ELISA were applied. Western blot analysis detected a 32-kDa secretagogin band in samples from normal mucosa. Immunohistochemical analyses on tissue specimens showed that secretagogin is exclusively expressed in neuroendocrine cells and nerve cells in normal mucosa of the digestive tract. Tissues adjacent to benign hyperplasic polyps and adenomas showed a decreased number of secretagogin-expressing neuroendocrine cells. Secretagogin co-localized with neuroendocrine markers (chromogranin A, neuron-specific enolase, synaptophysin) in neuroendocrine cells in crypts of normal mucosa, and in tumor cells of carcinoids. Secretagogin was strongly expressed in the cytosol and the nucleus of 19 well-differentiated neuroendocrine carcinoids and carcinoid metastases, as well as in neuroendocrine tumors from the lung, pancreas and adrenal gland. Secretagogin was detected in plasma from carcinoid patients with distant metastasis. Combined immunohistochemical analysis of secretagogin and FK506-binding protein 65, a protein de novo synthesized in adenocarcinomas, distinguished well-differentiated carcinoids, adenocarcinoids and undifferentiated carcinomas. We conclude that secretagogin is a novel marker for neuroendocrine differentiation.

Little is known about the reaction of normal thyroid glands to the iodine load given by x-ray dyes. We have therefore investigated the short-term effects of high doses of iodine on thyroid parameters in euthyroid patients. We measured free triiodothyronine (FT3), free thyroxine (FT4), and thyrotropin (TSH) serum concentrations before and daily for 1 week after parenteral application of x-ray dyes (coronary angiography: n = 16; computed tomography [CT] of either thorax or abdomen: n = 6; iodine dose range from 300-1221 mg of iodine per kilogram). Inclusion criteria were as follows: normal FT4, normal TSH, negative thyroid antibodies, urinary iodine excretion below 30 microg/dL, no palpable goiter and no euthyroid sick syndrome. All but one patient reacted with a TSH increase. Mean TSH values increased significantly 3-5 days after the iodine load within the normal range. Four patients (18%) had a TSH increase above normal, the maximal observed value being 6.4 microU/mL. Basal TSH values of these four patients were above 2 microU/mL. The day peak TSH concentrations were reached varied from day 1 to day 7, the majority (32%) having the peak on day 3. Peak TSH was significantly correlated with basal TSH values (r = 0.794, p < 0.0001). FT4 and FT3 remained unchanged and there was no significant correlation between the dose of iodine and the TSH reaction. In conclusion, iodine-containing contrast media can induce transiently subclinical hypothyroidism even in euthyroid patients. The TSH reaction seems to depend on the preexisting state of thyroid function.

The two LOV domains, LOV1 and LOV2, from Chlamydomonas reinhardtii were investigated by light-induced FT-IR difference spectroscopy and compared to the LOV domain of Bacillus subtilis (YtvA-LOV). It is shown that the two S-H conformations of the reactive LOV1 cysteine C57(1) are exposed to environments of different hydrogen bonding strength. Thus, the two rotamer configurations of C57 might be related to the fact that the triplet state decays bi-exponentially into the LOV1-390 photoproduct. Exchange of the two other cysteines of LOV1 (C32S and C83S) does not alter the S-H stretching band providing evidence that this band feature arises solely from C57. The reactive cysteine of LOV2 from Chlamydomonas reinhardtii (C250) and of YtvA-LOV (C62) exhibit both a homogenous S-H stretching vibrational band which suggests a single conformer of the amino acid side chain. Finally, the FT-IR difference spectrum of YtvA from Bacillus subtilis comprising the light absorbing LOV domain and the putative signaling STAS (sulfate transporter/antisigma-factor antagonist) domain, reveals conformational changes in the latter after blue-light excitation.

In order to identify neuroendocrine tumour-specific protein expression, we generated monoclonal antibodies (mAbs) with a tumour-related reaction pattern using a human insulinoma as immunogen. One of the generated mAbs (mAb 1D4) exhibited striking immunoreactivity against various neuroendocrine tumours without staining pancreatic islets of Langerhans. Furthermore, mAb 1D4 immunostained a characteristic subtype of hypothalamic neurones. Using two-dimensional (2-D) gel electrophoresis, mAb 1D4 immunoblotting and mass spectrometry, heat shock protein 70 (Hsp70) isoforms were identified as the mAb 1D4-specific antigen. In hypothalamic tissue, the presence of two different Hsp70 isoforms (Hsp70-8 and Hsp70-1) was revealed by 2-D gel immunoblots and consecutive mass spectrometric peptide analysis. In contrast, insulinoma and other neuroendocrine tumours displayed solely Hsp70-8 expression. Moreover, the tumour-specific presence of an additional mAb 1D4 immunoreactive protein of 40 kDa was observed in eight out of eight tested neuroendocrine tumours. For this variant, exclusively, peptides derived from the C terminus excluding the 299 amino-terminal residues were detected. In cultured tumour-derived fibroblasts, expression of the truncated Hsp70-8 subtype was not present. In conclusion, we have demonstrated a neuroendocrine tumour-specific expression pattern of Hsp70 isoforms and identified an as yet unknown N-terminally truncated Hsp70-8 variant., (Copyright 2004 Society for Endocrinology)