Transient receptor potential (TRP) channels are involved in a wide range of processes ranging from osmoregulation, thermal, chemical and sensory signalling, and potentially in the pathophysiology associated with several diseases. Patents for TRPV1 antagonists alone span diseases ranging across chronic pain, neuropathies, headache, bladder disorders, irritable bowel syndrome (IBS), gastro-oesophageal reflux disease (GORD), and cough amongst others. Most research is currently focused around those TRP channels involved in sensory processes, with the neurogastroenterology and motility field playing a major role, for example, through recent discoveries of differential roles for TRPV receptor subtypes in chemosensitivity and mechanosensitivity of visceral afferents. At this time, however, the understanding of the role of even TRPV1, let alone most of the other TRP channels in disease pathophysiology is only just beginning, and although enthusiasm around the therapeutic potential for modulators of these channels is understandable, based largely upon the experience of the effects of natural ligands, such as capsaicin, the sheer size and complexity of the TRP family as a whole must serve as a warning against expecting too much too soon from drug discovery efforts.
Chromosome studies were done on 82 patients with multiple myeloma, 11 with amyloidosis, 2 with multiple myeloma and amyloidosis, and 5 with plasma cell leukemia to investigate their chromosomal abnormalities and to determine the usefulness of cytogenetic studies. A chromosomally abnormal clone was found in 29 patients but was observed most often in those with active disease: in 18% of patients with newly diagnosed multiple myeloma, in 63% with aggressive disease, and in 40% with plasma cell leukemia. Survival among the newly diagnosed patients was significantly shorter (P = .0089) for those in whom an abnormal clone was identified (median survival, six months) than for those in whom only normal metaphases were observed (median survival, greater than 12 months). Among all of the patients, survival from the time of chromosome analysis was shorter for those in whom a chromosomally abnormal clone was found: the median survival was three months for patients with all abnormal metaphases and eight months for patients with normal and abnormal metaphases and has not yet been reached for patients with only normal metaphases. The most common anomalous chromosomes in patients with a plasma cell proliferative disorder were 1, 11, and 14: 11 patients had an abnormality involving chromosome 14q32 and nine patients had an anomalous chromosome 11. The single most common abnormality, a t(11;14)(q13;q32), occurred in three patients. Among the patients who developed preleukemia or acute nonlymphocytic leukemia, the most common anomaly involved chromosome 7. The results suggest that cytogenetic studies are useful for identifying patients who have a poor prognosis and can help distinguish patients with a cytopenia because of preleukemia from those with an aggressive plasma cell proliferative process.
Actions of the 5-HT(4) serotonergic receptor partial agonist, tegaserod, were investigated on mucosal secretion in the guinea-pig and human small intestine and on electrophysiological behaviour of secretomotor neurons in the guinea-pig small intestinal submucosal plexus. Expression of 5-HT(4) receptor protein and immunohistochemical localization of the 5-HT(4) receptor in the submucosal plexus in relation to expression and localization of choline acetyltransferase and the vesicular acetylcholine (ACh) transporter were determined for the enteric nervous system of human and guinea-pig small intestine. Immunoreactivity for the 5-HT(4) receptor was expressed as ring-like fluorescence surrounding the perimeter of the neuronal cell bodies and co-localized with the vesicular ACh transporter. Exposure of mucosal/submucosal preparations to tegaserod in Ussing chambers evoked increases in mucosal secretion reflected by stimulation of short-circuit current. Stimulation of secretion had a relative high EC(50) of 28.1 +/- 1.3 mumol L(-1), was resistant to neural blockade and appeared to be a direct action on the secretory epithelium. Tegaserod acted at presynaptic 5-HT(4) receptors to facilitate the release of ACh at nicotinic synapses on secretomotor neurons in the submucosal plexus. The 5-HT(2B) receptor subtype was not involved in actions at nicotinic synapses or stimulation of secretion.
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