Some clinical and laboratory studies of large pituitary tumours treated with dopamine agonists

The patient with a large pituitary tumour presents a number of management problems and conventional treatment with surgery and radiotherapy is unsatisfactory. Reports between 1978 and 1982 showed that some tumours regress during dopamine agonist (DA) therapy, though thiB does not produce a permanent cure (Chapter 1). The aim of the present work was to clarify the effect of DA therapy on different types of large pituitary tumour and to characterise cells from both responsive and unresponsive tumours. Three conclusions resulted from the clinical studies (Chapter 2): (1) Most macroprolactinomas shrink during DA therapy but the shrinkage is often asymmetrical and results in fibrosis during long-term therapy, both of which hamper subsequent surgery. (2) Disconnection hyperprolactinaemia may be considerable and lead to inappropriate DA therapy for non-adenomatous lesions. (3) Non-functioning tumours do not regress during DA therapy. Tumour cells were characterised by tumour cell perifusion (methods described in Chapters 3 and 4), dopamine receptor measurement using [ H]spiperone as radioligand (methods described in Chapter 5) and immunocytochemistry. Prolactin secretion rates from bromocriptinetreated macroprolactinomas were greatly reduced compared with untreated tumours. Most prolactinomas showed dose-related inhibition of prolactin secretion by dopamine and bromocriptine but one tumour was partially bromocriptine resistant in-vivo and in-vitro (Chapter 6). Fifty percent of the non-functioning tumours did not contain, secrete or immunostain for any known anterior pituitary peptide. The remainder secreted small amounts of gonadotrophins or alpha subunit, but the secretion was not inhibited by dopamine, immunostaining was confined to <102! of cells and tumour contents were low (Chapter 7). Despite their failure to regress during bromocriptine treatment, non¬ functioning tumours were shown to possess similar dopamine receptors to prolactinomas and normal anterior pituitary (Chapter 8). Using a novel immunoassay, bromocriptine was shown to be bound to non-functioning tumour dopamine receptors in-vivo. In contrast, two TSH-secreting adenomas were also unresponsive to dopaminergic manipulation but lacked membrane-bound dopamine receptors (Chapter 9). From these results, future clinical practice demands greater care in selecting patients for dopamine agonist or surgical treatments. The finding of dopamine receptors in non-functioning tumours suggests future research on these enigmatic tumours aimed at defining the cell type represented and post-dopamine receptor mechanisms (Chapter 10)

Selective internalization of sodium channels in rat dorsal root ganglion neurons infected with herpes simplex virus-1

The neurotropic virus, herpes simplex type 1 (HSV-1), inhibits the excitability of peripheral mammalian neurons, but the molecular mechanism of this effect has not been identified. Here, we use voltage-clamp measurement of ionic currents and an antibody against sodium channels to show that loss of excitability results from the selective, precipitous, and complete internalization of voltage-activated sodium channel proteins from the plasma membrane of neurons dissociated from rat dorsal root ganglion. The internalization process requires viral protein synthesis but not viral encapsulation, and does not alter the density of voltage-activated calcium or potassium channels. However, internalization is blocked completely when viruses lack the neurovirulence factor, infected cell protein 34.5, or when endocytosis is inhibited with bafilomycin A1 or chloroquine. Although it has been recognized for many years that viruses cause cell pathology by interfering with signal transduction pathways, this is the first example of viral pathology resulting from selective internalization of an integral membrane protein. In studying the HSV-induced redistribution of sodium channels, we have uncovered a previously unknown pathway for the rapid and dynamic control of excitability in sensory neurons by internalization of sodium channels

The roles of iPLA2, TRPM8 and TRPA1 in chemically induced cold hypersensitivity

<p>Abstract</p> <p>Background</p> <p>The cooling agents menthol and icilin act as agonists at TRPM8 and TRPA1. <it>In vitro</it>, activation of TRPM8 by icilin and cold, but not menthol, is dependent on the activity of a sub-type of phospholipase A2, iPLA2. Lysophospholipids (e.g. LPC) produced by PLA2 activity can also activate TRPM8. The role of TRPA1 as a primary cold sensor <it>in vitro</it> is controversial, although there is evidence that TRPA1 plays a role in behavioural responses to noxious cold stimuli. In this study, we have investigated the roles of TRPM8 and TRPA1 and the influence of iPLA2 on noxious cold sensitivities in naïve animals and after local administration of menthol, icilin and LPC. The roles of the channels in cold sensitivity were investigated in mice lacking either TRPM8 (<it>Trpm8</it>^-/-) or TRPA1 (<it>Trpa1</it>^-/-).</p> <p>Results</p> <p>Intraplantar administration of icilin evoked a dose-dependent increase in sensitivity to a 10°C stimulus that was inhibited by iPLA2 inhibition with BEL. In contrast the cold hypersensitivities elicited by intraplantar menthol and LPC were not inhibited by BEL treatment. BEL had no effect on basal cold sensitivity and mechanical hypersensitivities induced by the TRPV1 agonist, capsaicin, and the P2X3 agonist α,β-methylene ATP. Both <it>Trpm</it>8^-/-and <it>Trpa1</it>^-/-mice showed longer latencies for paw withdrawal from a 10°C stimulus than wild-type littermates. Cold hypersensitivities induced by either icilin or LPC were absent in <it>Trpm8</it>^-/-mice but were retained in <it>Trpa1</it>^-/-mice. In contrast, cold hypersensitivity evoked by menthol was present in <it>Trpm8</it>^-/-mice but was lost in <it>Trpa1</it>^-/-mice.</p> <p>Conclusions</p> <p>The findings that iPLA2 inhibition blocked the development of cold hypersensitivity after administration of icilin but failed to affect menthol-induced hypersensitivity agree well with our earlier <it>in vitro </it>data showing a differential effect of iPLA2 inhibition on the agonist activities of these agents. The ability of LPC to induce cold hypersensitivity supports a role for iPLA2 in modulating TRPM8 activity <it>in vivo</it>. Studies on genetically modified mice demonstrated that the effects of icilin and LPC were mediated by TRPM8 and not TRPA1. In contrast, menthol-induced cold hypersensitivity was dependent on expression of TRPA1 and not TRPM8.</p

Establishing the research priorities of paediatric emergency medicine clinicians in the UK and Ireland

Objective: Paediatric Emergency Research in the UK and Ireland (PERUKI) is a collaborative clinical studies group established in August 2012. It consists of a network of 43 centres from England, Ireland, Northern Ireland, Scotland and Wales, and aims to improve the emergency care of children through the performance of robust collaborative multicentre research within emergency departments. A study was conducted regarding the research priorities of PERUKI, to establish the research agenda for paediatric emergency medicine in the UK and Ireland. Methods: A two-stage modified Delphi survey was conducted of PERUKI members via an online survey platform. Stage 1 allowed each member to submit up to 12 individual questions that they identified as priorities for future research. In stage 2, the shortlisted questions were each rated on a seven-point Likert scale of relative importance. Participants: Members of PERUKI, including clinical specialists, academics, trainees and research nurses. Results: Stage 1 surveys were submitted by 46/91 PERUKI members (51%). A total of 249 research questions were generated and, following the removal of duplicate questions and shortlisting, 60 questions were carried forward for stage 2 ranking. Stage 2 survey responses were submitted by 58/95 members (61%). For the 60 research questions that were rated, the mean score of 'relative degree of importance' was 4.70 (range 3.36-5.62, SD 0.55). After ranking, the top 10 research priorities included questions on biomarkers for serious bacterial illness, major trauma, intravenous bronchodilators for asthma and decision rules for fever with petechiae, head injury and atraumatic limp. Conclusions: Research priorities of PERUKI members have been identified. By sharing these results with clinicians, academics and funding bodies, future research efforts can be focused to the areas of greatest need

Stimulation of GLP-1 secretion downstream of the ligand-gated ion channel TRPA1.

Stimulus-coupled incretin secretion from enteroendocrine cells plays a fundamental role in glucose homeostasis and could be targeted for the treatment of type 2 diabetes. Here, we investigated the expression and function of transient receptor potential (TRP) ion channels in enteroendocrine L cells producing GLP-1. By microarray and quantitative PCR analysis, we identified trpa1 as an L cell-enriched transcript in the small intestine. Calcium imaging of primary L cells and the model cell line GLUTag revealed responses triggered by the TRPA1 agonists allyl-isothiocyanate (mustard oil), carvacrol, and polyunsaturated fatty acids, which were blocked by TRPA1 antagonists. Electrophysiology in GLUTag cells showed that carvacrol induced a current with characteristics typical of TRPA1 and triggered the firing of action potentials. TRPA1 activation caused an increase in GLP-1 secretion from primary murine intestinal cultures and GLUTag cells, an effect that was abolished in cultures from trpa1(-/-) mice or by pharmacological TRPA1 inhibition. These findings present TRPA1 as a novel sensory mechanism in enteroendocrine L cells, coupled to the facilitation of GLP-1 release, which may be exploitable as a target for treating diabetes.This is an author-created, uncopyedited electronic version of an article accepted for publication in Diabetes. The American Diabetes Association (ADA), publisher of Diabetes, is not responsible for any errors or omissions in this version of the manuscript or any version derived from it by third parties. The definitive publisher-authenticated version will is available in Diabetes online at http://diabetes.diabetesjournals.org/content/early/2014/10/13/db14-0737.short?rss=1&patientinform-links=yes&legid=diabetes;db14-0737v1

Autoantibodies produce pain in complex regional pain syndrome by sensitizing nociceptors

Complex regional pain syndrome (CRPS) is a post-traumatic pain condition with an incompletely understood pathophysiological basis. Here, we have examined the cellular basis of pain in CRPS using behavioral and electrophysiological methods in mice treated with IgG from CRPS patients, in combination with a paw incision. Mice were subjected to a hind paw skin-muscle incision alone, or in combination with administration of IgG purified from either healthy control subjects (HC) or patients with persistent CRPS. Nociceptive function was examined behaviorally in vivo, and electrophysiologically in vitro using skin-nerve preparations to study the major classes of mechanosensitive single units. Administration of IgG from CRPS patients exacerbated and prolonged the post-surgical hypersensitivity to noxious mechanical, cold and heat stimulation, but did not influence tactile sensitivity following a paw incision. Studies of IgG preparations pooled from patient cohorts (n=26-27) show that pathological autoantibodies are present in the wider population of patients with persistent CRPS, and that patients with more severe pain have higher effective autoantibody titres than patients with moderate pain intensity. Electrophysiological investigation of skin-nerve preparations from mice treated with CRPS IgG from a single patient identified both a significantly increased evoked impulse activity in A- and C-nociceptors, and an increased spontaneous impulse rate in the intact saphenous nerve. Our results show that painful hypersensitivity in persistent CRPS is maintained by autoantibodies, which act by sensitizing A- and C-nociceptors

Winston Churchill's "crazy broadcast": party, nation, and the 1945 Gestapo speech

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