Although nicotinic agonists can modulate sensory transmission, particularly nociceptive signaling, remarkably little is known about the functional expression of nicotinic acetylcholine receptors (nAChRs) on primary sensory neurons. We have utilized molecular and electrophysiological techniques to characterize the functional diversity of nAChR expression on mammalian dorsal root ganglion (DRG) neurons. RT-PCR analysis of subunit mRNA in DRG tissue revealed the presence of nAChR subunits alpha2-7 and beta2-beta4. Using whole cell patch-clamp recording and rapid application of nicotinic agonists, four pharmacologically distinct categories of nicotinic responses were identified in cultured DRG neurons. Capacitance measurements were used to divide neurons into populations of large and small cells, and the prevalence of nicotinic responses was compared between groups. Category I (alpha7-like) responses were seen in 77% of large neurons and 32% of small neurons and were antagonized by 10 nM methyllycaconitine citrate (MLA) or or 50 nM alpha-bungarotoxin (alpha-BTX). Category II (alpha3beta4-like) responses were seen in 16% of large neurons and 9% of small neurons and were antagonized by 20 microM mecamylamine but not 10 nM MLA or 1 microM DHbetaE. Category II responses had a higher sensitivity to cytisine than nicotine. Two other types of responses were identified in a much smaller percentage of neurons and were classified as either category III (alpha4beta2-like) or category IV (subtype unknown) responses. Both the alpha7-like and alpha3beta4-like responses could be desensitized by prolonged applications of the analgesic epibatidine.

SummaryMacrophages can fuse to form osteoclasts in bone or multinucleate giant cells (MGCs) as part of the immune response. We use a systems genetics approach in rat macrophages to unravel their genetic determinants of multinucleation and investigate their role in both bone homeostasis and inflammatory disease. We identify a trans-regulated gene network associated with macrophage multinucleation and Kcnn4 as being the most significantly trans-regulated gene in the network and induced at the onset of fusion. Kcnn4 is required for osteoclast and MGC formation in rodents and humans. Genetic deletion of Kcnn4 reduces macrophage multinucleation through modulation of Ca2+ signaling, increases bone mass, and improves clinical outcome in arthritis. Pharmacological blockade of Kcnn4 reduces experimental glomerulonephritis. Our data implicate Kcnn4 in macrophage multinucleation, identifying it as a potential therapeutic target for inhibition of bone resorption and chronic inflammation.

Objectives To provide a clinical laboratory perspective on the Verifying Accurate Leading-edge IVCT Development Act (VALID) discussion draft. This potential legislative effort, if enacted, would overhaul the regulatory oversight of in vitro diagnostics (IVDs) in the United States and create a single system for regulation of conventional IVDs and laboratory-developed tests (LDTs). Methods A concise literature-based review of LDT regulation is presented followed by a discussion of key concerns pertinent to clinical laboratories that should be considered in future IVD regulatory reform efforts. Results Key issues identified include the importance of fostering innovation, preserving patient safety, protecting the practice of laboratory medicine, and minimizing undue regulatory burden. Clinical laboratories are not equivalent to manufacturing facilities and would therefore encounter challenges in implementing device-centric regulatory oversight models. Conclusions It is imperative that a clinical laboratory perspective on LDTs is understood and incorporated prior to advancement of future legislative proposals.

A wealth of pharmacological and behavioral data suggests that spinally projecting serotonergic cells mediate opioid analgesia. A population of medullary neurons, located within raphe magnus (RM) and the neighboring reticular nuclei, contains serotonin and is the source of serotonin in the spinal dorsal horn. To test whether serotonergic neurons mediate opioid analgesia, morphine was administered during recordings from medullary cells that were physiologically characterized as serotonergic (5HTp) by their slow and steady discharge pattern in the lightly anesthetized rat. Selected 5HTp cells (n = 14) were intracellularly labeled, and all contained serotonin immunoreactivity. The discharge of most 5HTp cells was not affected by an analgesic dose of systemic morphine. In a minority of cases, 5HTp cells either increased or decreased their discharge after morphine administration. However, morphine altered the discharge of some 5HTp cells in the absence of producing analgesia and conversely did not alter the discharge of most 5HTp cells in cases in which analgesia occurred. RM cells with irregular discharge patterns and excitatory or inhibitory responses to noxious tail heat were classified as ON and OFF cells, respectively. All ON and OFF cells that were intracellularly labeled (n = 9) lacked serotonin immunoreactivity. All ON cells were inhibited, and most OFF cells were excited by systemic morphine. Because 5HTp cells do not consistently change their discharge during morphine analgesia, they are unlikely to mediate the analgesic effects of morphine. Instead, nonserotonergic cells are likely to mediate morphine analgesia in the anesthetized rat. In light of the sensitivity of morphine analgesia to manipulations of serotonin, serotonin release, although neither necessary nor sufficient for opioid analgesia, is proposed to facilitate the analgesic effects of nonserotonergic RM terminals in the spinal cord.

Ependymal cells line the cerebral ventricles and are located in an ideal position to detect central nervous system injury and inflammation. The signaling mechanisms of ependymal cells, however, are poorly understood. As extracellular adenosine 5′-triphosphate is elevated in the context of cellular damage, experiments were conducted to determine whether ependymal cells along the mouse subventricular zone (SVZ) express functional purinergic receptors. Using whole-cell patch clamp recording, widespread expression of P2X 7 receptors was detected on ependymal cells based on their antagonist sensitivity profile and absence of response in P2X 7 −/− mice. Immunocytochemistry confirmed the expression of P2X 7 receptors, and electron microscopy demonstrated that P2X 7 receptors are expressed on both cilia and microvilli. Ca 2+ imagingshowed that P2X 7 receptors expressed on cilia are indeed functional. As ependymal cells are believed to function as partner cells in the SVZ neurogenic niche, P2X 7 receptors may play a role in neural progenitor response to injury and inflammation.

BACKGROUND: Twenty-five years ago, the Food and Drug Administration (FDA) asserted in a draft document that "home brew" tests-now commonly referred to as laboratory-developed tests (LDTs)-are subject to the same regulatory oversight as other in vitro diagnostics (IVDs) 4 . In 2010, the FDA began work on developing a proposed framework for future LDT oversight. Released in 2014, the draft guidance sparked an intense debate over potential LDT regulation. While the proposed guidance has not been implemented, many questions regarding LDT oversight remain unresolved. CONTENT:This review provides an overview of federal statutes and regulations related to IVDs and clinical laboratory operations, with a focus on those potentially applicable to LDTs and proposed regulatory efforts. Sources reviewed include the Code of Federal Regulations, the Federal Register, congressional hearings, guidance and policy documents, position statements, published literature, and websites.

Sumatriptan caused a significant improvement in the quality of life of patients with very severe migraine. This improvement was measurable by both the general quality of life instrument and the pain-specific questionnaire.

Spinal administration of nicotinic agonists can produce both hyperalgesic and analgesic effects in vivo. The cellular mechanisms underlying these behavioral phenomena are not understood. As a possible explanation for nicotinic hyperalgesia, we tested whether nicotinic acetylcholine receptors (nAChRs) could enhance excitatory transmission onto spinal cord dorsal horn neurons. Whole-cell patch-clamp recordings were performed in neonatal rat spinal cord slices. Activation of nAChRs enhanced glutamatergic synaptic transmission in 59% of dorsal horn neurons tested, and this effect was blocked by methyllycaconitine (10 nM), suggesting a key role for ␣7 nAChRs. Inhibition of acetylcholinesterase with methamidophos also enhanced transmission, demonstrating a similar effect of endogenous acetylcholine. nAChR activation also enhanced transmission by dorsal root entry zone stimulation, suggesting that ␣7 nAChRs on the central terminals of DRG afferents mediate this effect. Paired pre-and postsynaptic stimulation induced long-term potentiation of excitatory inputs to some of the dorsal horn neurons. Long-term potentiation induction was much more prevalent when nicotine was applied during stimulation. This effect also depended on both ␣7 nAChRs and N-methyl-D-aspartate glutamate receptors. Our findings demonstrate that ␣7 nAChRs can contribute to both short-and long-term enhancement of glutamatergic synaptic transmission in the spinal cord dorsal horn and provide a possible mechanism for nicotinic hyperalgesia.E ffective pain management is a major challenge for modern healthcare. Most pain medications fall under two classes of compounds, opioids and nonsteroidal antiinflammatory drugs. Recently, structural analogs of nicotine have also demonstrated strong analgesic potency (1, 2). Although these agents may provide alternate pain therapies, a number of issues remain to be resolved, such as addictive profiles and side effects, including paradoxical hyperalgesia. Considerable research has focused on the analgesic effects of nicotine and its analogs (2-7), yet the mechanisms underlying nicotinic hyperalgesia are not well understood.Hyperalgesia and͞or irritation have been observed after central injections of nicotinic agonists (8-10), systemic injections of subanalgesic doses (11), and intrathecal applications (12,13). This intrathecal effect is associated with significant increases in excitatory transmitter release (14), and both nicotinic and glutamate receptor antagonists can decrease this hyperalgesia (15, 16). Although dorsal horn neurons are excited by nicotine (17), it is not known which subtypes of nicotinic acetylcholine receptors (nAChRs) are expressed by dorsal horn neurons or on presynaptic afferent terminals. For example, nicotinic enhancement of synaptic activity has been noted in the spinal cord dorsal horn (SCDH) in mice that lack the ␣4 nAChR subunit, but the nAChR subtype(s) that mediate this effect is unknown (5).Neuronal nAChRs are pentameric ligand-gated ion channels, and molecular cloning has identified nin...