41 research outputs found
A Critical Evaluation of sst3 and sst5 Immunohistochemistry in Human Pituitary Adenomas.
No full textBACKGROUND
Somatostatin receptor (sst) overexpression in neuroendocrine tumors allows sst-targeted tumor imaging and therapy with long-acting, cold, or radioactive somatostatin analogs. sst2 has been most important, owing to its wide overexpression and high affinity for somatostatin analogs, but other sst subtypes become of increasing clinical interest due to drug development. Immunohistochemistry is the preferred method to detect sst in resected tumor tissues. While it is established for sst2 using the antibody UMB-1, there is less experience for other sst subtypes.
METHODS
sst3 and sst5 immunohistochemistry using the antibodies UMB-5 and UMB-4 was evaluated in 60 pituitary adenomas and compared with in vitro sst autoradiography (ARG), the in vitro gold standard method to assess sst.
RESULTS
UMB-4 immunohistochemistry for sst5 yielded membranous staining of tumor cells. It correlated fairly well with ARG, results matching in 80% of tumors. UMB-5 immunohistochemistry for sst3 showed not only a membranous, but also cytoplasmic background staining. Agreement with ARG was limited. All tumors showed UMB-5 staining, while only 57% were positive by ARG. In comparison, UMB-1 staining levels showed a highly significant correlation with autoradiographic sst2 density levels (R2 = 0.797). Not only tumor cells, but also intratumoral blood vessels were immunohistochemically positive for sst2, 3, and 5.
CONCLUSION
UMB-1 immunohistochemistry for sst2 is excellent. sst3 immunohistochemistry using UMB-5 is not yet optimal, with suspected limited specificity, and should be applied with caution. UMB-4 immunohistochemistry for sst5 appears to be equivalent to sst5-ARG and suitable for diagnostic applications
Modernisation, smoking and chronic disease: Of temporality and spatiality in global health
No full textAbstractThis article explores the spatio-temporal logics at work in global health. Influenced by ideas of time–space compression, the global health literature argues that the world is characterised by a convergence of disease patterns and biomedical knowledge. While not denying the influence of these temporalities and spatialities of globalisation within the global health and chronic disease field, the article argues that they sit alongside other, often-conflicting notions of time and space. To do so, it explores the spatio-temporal logics that underpin a highly influential epidemiological model of the smoking epidemic. Unlike the temporalities and spatialities of sameness described in much of the global health literature, the article shows that this model is articulated around temporalities and spatialities of difference. This is not the difference celebrated by postmoderns, but the difference of modernisation theorists built around nations, sequential stages and progress. Indeed, the model, in stark contrast to the ‘one world, one time, one health’ globalisation mantra, divides the world into nation–states and orders them along epidemiological, geographical and development lines
Neuropeptide Y modulates steroid production of human adrenal H295R cells through Y1 receptors
No full textNeuropeptide Y (NPY) is abundantly expressed in the nervous system and acts on target cells through NPY receptors. The human adrenal cortex and adrenal tumors express NPY receptor subtype Y1, but its function is unknown. We studied Y1-mediated signaling, steroidogenesis and cell proliferation in human adrenal NCI-H295R cells. Radioactive ligand binding studies showed that H295R cells express Y1 receptor specifically. NPY treatment of H295R cells stimulated the MEK/ERK1/2 pathway, confirming that H295R cells express functional Y1 receptors. Studies of the effect of NPY and related peptide PYY on adrenal steroidogenesis revealed a decrease in 11-deoxycortisol production. RIA measurements of cortisol from cell culture medium confirmed this finding. Co-treatment with the Y1 antagonist BIBP2336 reversed the inhibitory effect of NPY on cortisol production proving specificity of this effect. At mRNA level, NPY decreased HSD3B2 and CYP21A2 expression. However NPY revealed no effect on cell proliferation. Our data show that NPY can directly regulate human adrenal cortisol production
Analgesic activity of a non-peptide imidazolidinedione somatostatin agonist: in vitro and in vivo studies in rat
No full textSeveral lines of evidence support an important role for somatostatin receptors (SSTRs) in pain modulation. The therapeutic use of established SSTR peptide agonists for this indication is limited by their broad range of effects, need for intrathecal delivery, and short half-life. Therefore, the goal of the present study was to investigate the analgesic effect of SCR007, a new, highly selective SSTR2 non-peptide agonist. Behavioral studies demonstrated that paw withdrawal latencies to heat were significantly increased following intraplantar SCR007. Furthermore, both intraperitoneal and intraplantar injection of SCR007 significantly reduced formalin- and capsaicin-induced flinching and lifting/licking nociceptive behaviors. Recordings from nociceptors using an in vitro glabrous skin-nerve preparation showed that SCR007 reduced heat responses in a dose-dependent fashion, bradykinin-induced excitation, heat sensitization and capsaicin-induced excitation. In both the behavioral and single fiber studies, the SCR007 effects were reversed by the SSTR antagonist cyclo-somatostatin, demonstrating receptor specificity. In the single fiber studies, the opioid antagonist naloxone did not reverse SCR007-induced anti-nociception suggesting that SCR007 did not exert its effects through activation of opioid receptors. Analysis of cAMP/protein kinase A (PKA) involvement demonstrated that SCR007 prevented forskolin- and Sp-8-Br-cAMPS (a PKA activator)-induced heat sensitization, supporting the hypothesis that SCR007-induced inhibition could involve a down-regulation of the cAMP/PKA pathway. These data provide several lines of evidence that the non-peptide imidazolidinedione SSTR2 agonist SCR007 is a promising anti-nociceptive and analgesic agent for the treatment of pain of peripheral and/or central origin
Comparison of the binding and internalization properties of 12 DOTA-coupled and 111In-labelled CCK2/Gastrin receptor binding peptides: a collaborative project under COST Action BM0607
No full textSpecific overexpression of cholecystokinin 2 (CCK2)/Gastrin receptors has been demonstrated in several tumors of neuroendocrine origin. In some of these cancer types, such s medullary thyroid cancer (MTC), there are no effective systemic treatments for metastatic disease. Peptide Receptor Radionuclide Therapy (PRRT) may be a viable therapeutic strategy in the management of these patients. Several CK2R targeted radiopharmaceuticals have been described in recent years. As part of the EU COST action BM0607 we studied the in vitro and in vivo characteristics of 12 DOTA‐conjugated CK2R binding peptides. In the present study, we analyzed binding and internalization characteristics. Stability, biodistribution, and imaging studies have been performed in parallel. methods. Determination of IC50 was performed using autoradiography, with peptides complexed to Indium‐115 displacing 125I‐CCK on tissue sections from human tumors. Saturation binding and internalization experiments were performed using 111In‐labelled peptides (specific activity 2‐10 MBq/nmol). The rat AR42J cell line and the human A431‐CCK2R transfected cell line were utilized for in vitro experiments. Dissociation constants (Kd) and apparent number of binding sites (Bmax) were determined with the aid of graphical analysis software. Internalization was determined in receptor expressing cells by incubating with tracer amounts of peptide at 37 and 4°C for different times up to 120 min. Surface bound peptide was then stripped either by acid wash or incubation with 1μM cold peptide at 4°C. Results. All peptides showed high and similar receptor affinity with IC50 values ranging from 0.2 to 3.4 nM. Saturation experiments also showed high affinity with Kd values in the 10‐9 ‐10‐8 M range. Bmax values estimated in A431‐CCK2R cells ranged from 1 .0‐ 4.6 E6 per cell. Slight differences in the levels of non‐specific binding to cells were observed for the different peptides. All peptides showed high levels of internalization when incubated at 37°C. Conclusion. All DOTA‐conjugated peptides showed similar receptor binding and internalization properties. Issues pertaining to in
vivo stability and biodistribution will be important in determining the most promising candidates for further development and clinical application. This study is part of COST Action BM0607‐WG
Comparison of biological stability and metabolism of CCK2 receptor targeting peptides, a collaborative project under COST BM0607.
No full textItem does not contain fulltextPURPOSE: Stability of radiolabelled cholecystokinin 2 (CCK2) receptor targeting peptides has been a major limitation in the use of such radiopharmaceuticals especially for targeted radionuclide therapy applications, e.g. for treatment of medullary thyroid carcinoma (MTC). The purpose of this study was to compare the in vitro stability of a series of peptides binding to the CCK2 receptor [selected as part of the COST Action on Targeted Radionuclide Therapy (BM0607)] and to identify major cleavage sites. METHODS: Twelve different 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-minigastrin/CCK conjugates were provided within an European COST Action (BM0607) by different laboratories and radiolabelled with (177)Lu. Their in vitro stabilities were tested in fresh human serum. Radiochemical yields (RCY) and intact radioligands for half-life calculations were determined by radio-HPLC. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) analysis of metabolites was performed to identify cleavage products using conjugates labelled with excess stable (nat)Lu, incubated in serum at 37 degrees C. Urine metabolite analysis after injection in normal mice was performed by radio-HPLC analysis. RESULTS: Variable stability in human serum was found for the different peptides with calculated half-lives between 4.5 +/- 0.1 h and 198 +/- 0.1 h (n = 2). In urine of normal mice only metabolised peptide fragments were detected even at short times after injection for all peptides. MALDI-TOF MS revealed a major cleavage site of all minigastrin derivatives between Asp and Phe-NH(2) at the C-terminal end. CONCLUSION: Development of CCK2 receptor ligands especially for therapeutic purposes in patients with MTC or small cell lung cancer (SCLC) is still ongoing in different laboratories. This comparative study provided valuable insight into the importance of biological stability especially in the context of other results of this comparative trial within the COST Action BM0607.01 augustus 201
Incretin receptors in non-neoplastic and neoplastic thyroid C cells in rodents and humans: relevance for incretin-based diabetes therapy
No full textWhile incretins are of great interest for the therapy of diabetes 2, the focus has recently been brought to the thyroid, since rodents treated with glucagon-like peptide-1 (GLP-1) analogs were found to occasionally develop medullary thyroid carcinomas. Incretin receptors for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) were therefore measured in various rodent and human thyroid conditions. In vitro GLP-1 and GIP receptor autoradiography were performed in normal thyroids, C-cell hyperplasia and medullary thyroid carcinomas in rodents. Receptor incidence and density were assessed and compared with the receptor expression in human thyroids, medullary thyroid carcinomas, and TT cells. GLP-1 receptors are expressed in C cells of normal rat and mice thyroids. Their density is markedly increased in rat C-cell hyperplasia and medullary thyroid carcinomas, where their incidence amounts to 100%. GIP receptors are neither detected in normal rodent thyroids nor in C-cell hyperplasia, but are present in all rat medullary thyroid carcinomas. No GLP-1 or GIP receptors are detected in normal human thyroids. Whereas only 27% of all human medullary thyroid carcinomas express GLP-1 receptors, up to 89% express GIP receptors in a high density. TT cells lack GLP-1 receptors but express GIP receptors. GLP-1 receptors are frequently expressed in non-neoplastic and neoplastic C cells in rodents while they are rarely detected in human C-cell neoplasia, suggesting species differences. Conversely, GIP receptors appear to be massively overexpressed in neoplastic C cells in both species. The presence of incretin receptors in thyroid C cell lesions suggests that this organ should be monitored before and during incretin-based therapy of diabetes
Glucagon-like peptide-1 (GLP-1) receptors are not overexpressed in pancreatic islets from patients with severe hyperinsulinaemic hypoglycaemia following gastric bypass
No full textGlucagon-like peptide-1 (GLP-1) receptors are highly overexpressed in benign insulinomas, permitting in vivo tumour visualisation with GLP-1 receptor scanning. The present study sought to evaluate the GLP-1 receptor status in vitro in other pancreatic disorders leading to hyperinsulinaemic hypoglycaemia, specifically after gastric bypass surgery
