Norovirus: Facts and Reflections from Past, Present, and Future.

Human Norovirus is currently the main viral cause of acute gastroenteritis (AGEs) in most countries worldwide. Nearly 50 years after the discovery of the "Norwalk virus" by Kapikian and colleagues, the scientific and medical community continue to generate new knowledge on the full biological and disease spectrum of Norovirus infection. Nevertheless, several areas remain incompletely understood due to the serious constraints to effectively replicate and propagate the virus. Here, we present a narrated historic perspective and summarize our current knowledge, including insights and reflections on current points of interest for a broad medical community, including clinical and molecular epidemiology, viral-host-microbiota interactions, antivirals, and vaccine prototypes. We also include a reflection on the present and future impacts of the COVID-19 pandemic on Norovirus infection and disease.

Levels of Urgency for Orthopaedic Procedures: Reliability and Adoption of a Consensus-driven Classification.

INTRODUCTION: The current COVID-19 disease pandemic has delayed nonurgent orthopaedic procedures to adequately care for those affected by the severe acute respiratory syndrome coronavirus 2, resulting in a backlog in orthopaedic surgical care. As the capacity for orthopaedic surgeries expands or contracts, allocation of limited resources in a manner that adequately reflects medical necessity and urgency is paramount. An orthopaedic surgery-specific prioritization schema with proven reliability is lacking. The primary aim of this study was to assess the reliability of a newly developed prioritization list used for the phased reinstatement of orthopaedic surgical procedures during the COVID-19 pandemic and afterward. The secondary aim was to report its implementation. METHODS: A consensus-based, orthopaedic surgery-specific, tiered prioritization list reflecting various levels of urgency was created by a committee of orthopaedic surgeons covering all subspecialties and representing academic, multispecialty, and private community practices. Reliability was tested for 63 randomized cases representing all orthopaedic subspecialties. Four raters evaluated the cases independently at two separate time points, at least one week apart. Fleiss kappa was used to assess intrarater and interrater agreement. Implementation were assessed by surveying both surgeons and the surgery scheduling administrative personnel at each surgical facility within a large health system for any adoption issues. RESULTS: Case distributions within tiers 1, 2, 3, and 4 were 35%, 14%, 27%, and 24%, respectively. Interrater agreement ranged from 0.63 (95% confidence interval [CI] 0.57 to 0.69) to 0.72 (95% CI 0.66 to 0.78) for the ratings. Intrarater reliability ranged from 0.62 to 1.0. The highest levels of agreement were in tiers 1, 4, and the subspecialties oncology and foot/ankle. The time from development to full scale adoption and implementation by all orthopaedic surgeons was rapid. DISCUSSION: This tiered prioritization list for orthopaedic procedures is both adoptable and reliable during the phased reinstatement of procedures during the COVID-19 pandemic and afterward. Further refinements may enhance utility. LEVELS OF EVIDENCE: Reliability study: Level I (Evid Based Spine Care J 2014 October;5(2):166. doi: 10.1055/s-0034-1394106).

Sacral Dysmorphism and Lumbosacral Transitional Vertebrae (LSTV) Review.

BACKGROUND: Anatomic variation in the relationship between the lumbar spine and sacrum was first described in the literature nearly a century ago and continues to play an important role in spine deformity, low back pain (LBP), and pelvic trauma. This review will focus on the clinical and surgical implications of abnormal lumbosacral anatomy in the context of sacroiliac joint (SIJ) disease, spine deformity, and pelvic trauma. METHODS: A PubMed search using the keywords "lumbosacral transitional vertebrae," "LSTV," "transitional lumbosacral vertebrae," "TLSV," and "sacral dysmorphism" was performed. The articles presented here were evaluated by the authors. CLINICAL SIGNIFICANCE: The prevalence of LSTV varies widely in the literature from 3.9-% to 35.6% in the spine literature, and sacral dysmorphism is described in upwards of 50% of the population in the trauma literature. The relationship between LSTV and LBP is well established. While there is no agreed-on etiology, the source of pain is multifactorial and may be related to abnormal biomechanics and alignment, disc degeneration, and arthritic changes. SURGICAL IMPLICATIONS: Understanding abnormal lumbosacral anatomy is crucial for preoperative planning of SIJ fusion, spine deformity, and pelvic trauma surgery. LSTV can alter spinopelvic parameters crucial in planning spine deformity correction. Traditional safe zones for sacroiliac screw placement do not apply in the first sacral segment in sacral dysmorphism and risk iatrogenic nerve injury. CONCLUSIONS: LSTV and sacral dysmorphism are common anatomic variants found in the general population. Abnormal lumbosacral anatomy plays a significant role in clinical evaluation of LBP and surgical planning in SIJ fusion, spine deformity, and pelvic trauma. Further studies evaluating the influence of abnormal lumbosacral anatomy on LBP and surgical technique would help guide treatment for these patients.

The discovery of benzoxazine sulfonamide inhibitors of NaV1.7: Tools that bridge efficacy and target engagement.

The voltage-gated sodium channel NaV1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of NaV1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat NaV1.7 versus human NaV1.7 was observed, rendering in vivo rat pharmacology studies challenging. Herein, we report the discovery and optimization of novel benzoxazine sulfonamide inhibitors of human, rat and mouse NaV1.7 which enabled pharmacological assessment in traditional behavioral rodent models of pain and in turn, established a connection between formalin-induced pain and histamine-induced pruritus in mice. The latter represents a simple and efficient means of measuring target engagement.

Pharmacologic Characterization of AMG8379, a Potent and Selective Small Molecule Sulfonamide Antagonist of the Voltage-Gated Sodium Channel NaV1.7.

Potent and selective antagonists of the voltage-gated sodium channel NaV1.7 represent a promising avenue for the development of new chronic pain therapies. We generated a small molecule atropisomer quinolone sulfonamide antagonist AMG8379 and a less active enantiomer AMG8380. Here we show that AMG8379 potently blocks human NaV1.7 channels with an IC50 of 8.5 nM and endogenous tetrodotoxin (TTX)-sensitive sodium channels in dorsal root ganglion (DRG) neurons with an IC50 of 3.1 nM in whole-cell patch clamp electrophysiology assays using a voltage protocol that interrogates channels in a partially inactivated state. AMG8379 was 100- to 1000-fold selective over other NaV family members, including NaV1.4 expressed in muscle and NaV1.5 expressed in the heart, as well as TTX-resistant NaV channels in DRG neurons. Using an ex vivo mouse skin-nerve preparation, AMG8379 blocked mechanically induced action potential firing in C-fibers in both a time-dependent and dose-dependent manner. AMG8379 similarly reduced the frequency of thermally induced C-fiber spiking, whereas AMG8380 affected neither mechanical nor thermal responses. In vivo target engagement of AMG8379 in mice was evaluated in multiple NaV1.7-dependent behavioral endpoints. AMG8379 dose-dependently inhibited intradermal histamine-induced scratching and intraplantar capsaicin-induced licking, and reversed UVB radiation skin burn-induced thermal hyperalgesia; notably, behavioral effects were not observed with AMG8380 at similar plasma exposure levels. AMG8379 is a potent and selective NaV1.7 inhibitor that blocks sodium current in heterologous cells as well as DRG neurons, inhibits action potential firing in peripheral nerve fibers, and exhibits pharmacodynamic effects in translatable models of both itch and pain.

Crystal structures of human glycine receptor α3 bound to a novel class of analgesic potentiators.

Current therapies to treat persistent pain and neuropathic pain are limited by poor efficacy, side effects and risk of addiction. Here, we present a novel class of potent selective, central nervous system (CNS)-penetrant potentiators of glycine receptors (GlyRs), ligand-gated ion channels expressed in the CNS. AM-1488 increased the response to exogenous glycine in mouse spinal cord and significantly reversed mechanical allodynia induced by nerve injury in a mouse model of neuropathic pain. We obtained an X-ray crystal structure of human homopentameric GlyRα3 in complex with AM-3607, a potentiator of the same class with increased potency, and the agonist glycine, at 2.6-Å resolution. AM-3607 binds a novel allosteric site between subunits, which is adjacent to the orthosteric site where glycine binds. Our results provide new insights into the potentiation of cysteine-loop receptors by positive allosteric modulators and hold promise in structure-based design of GlyR modulators for the treatment of neuropathic pain.

Inhibition of Inactive States of Tetrodotoxin-Sensitive Sodium Channels Reduces Spontaneous Firing of C-Fiber Nociceptors and Produces Analgesia in Formalin and Complete Freund's Adjuvant Models of Pain.

While genetic evidence shows that the Nav1.7 voltage-gated sodium ion channel is a key regulator of pain, it is unclear exactly how Nav1.7 governs neuronal firing and what biophysical, physiological, and distribution properties of a pharmacological Nav1.7 inhibitor are required to produce analgesia. Here we characterize a series of aminotriazine inhibitors of Nav1.7 in vitro and in rodent models of pain and test the effects of the previously reported "compound 52" aminotriazine inhibitor on the spiking properties of nociceptors in vivo. Multiple aminotriazines, including some with low terminal brain to plasma concentration ratios, showed analgesic efficacy in the formalin model of pain. Effective concentrations were consistent with the in vitro potency as measured on partially-inactivated Nav1.7 but were far below concentrations required to inhibit non-inactivated Nav1.7. Compound 52 also reversed thermal hyperalgesia in the complete Freund's adjuvant (CFA) model of pain. To study neuronal mechanisms, electrophysiological recordings were made in vivo from single nociceptive fibers from the rat tibial nerve one day after CFA injection. Compound 52 reduced the spontaneous firing of C-fiber nociceptors from approximately 0.7 Hz to 0.2 Hz and decreased the number of action potentials evoked by suprathreshold tactile and heat stimuli. It did not, however, appreciably alter the C-fiber thresholds for response to tactile or thermal stimuli. Surprisingly, compound 52 did not affect spontaneous activity or evoked responses of Aδ-fiber nociceptors. Results suggest that inhibition of inactivated states of TTX-S channels, mostly likely Nav1.7, in the peripheral nervous system produces analgesia by regulating the spontaneous discharge of C-fiber nociceptors.

Analysis by rotavirus gene 6 reverse transcriptase-polymerase chain reaction assay of rotavirus-positive gastroenteritis cases observed during the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST).

During the vaccination phase of the Rotavirus Efficacy and Safety Trial (REST), the period between the administration of dose 1 through 13 days after the administration of dose 3, there were more wild-type rotavirus gastroenteritis (RVGE) cases among vaccine recipients compared with placebo recipients using the protocol-specified microbiological plaque assay in the clinical-efficacy cohort, a subset of subjects where vaccine efficacy against RVGE of any severity was assessed. In this study, a rotavirus genome segment 6-based reverse transcriptase-polymerase chain reaction assay was applied post hoc to clarify the accuracy of type categorization of all these RVGE cases in vaccine recipients during the vaccination phase of REST. The assay characterized 147 (90%) of 163 re-assayed RVGE cases or rotavirus-associated health care contacts as type-determinable: either wild-type or vaccine-type rotavirus strains. In the clinical-efficacy cohort (N = 5673), 19 (18.8%) of 101 samples from RVGE cases contained wild-type rotavirus, 70 (69.3%) vaccine virus, and 12 (11.9%) were indeterminable. In the large-scale cohort (N = 68,038), 10 (34.5%) of 29 samples from RVGE-related health care contacts contained wild-type rotavirus strains, 15 (51.7%) vaccine-type rotavirus strains, and 4 (13.8%) were indeterminable. Of the 33 samples from RVGE cases in placebo recipients, all were confirmed to contain wild-type rotaviruses. Altogether, this post-hoc re-evaluation showed that the majority (75%) of type-determinable RVGE cases or health care contacts that occurred during the vaccination phase of REST in vaccine recipients were associated with vaccine-type rotavirus strains rather than wild-type rotavirus strains.

Global Nav1.7 knockout mice recapitulate the phenotype of human congenital indifference to pain.

Clinical genetic studies have shown that loss of Nav1.7 function leads to the complete loss of acute pain perception. The global deletion is reported lethal in mice, however, and studies of mice with promoter-specific deletions of Nav1.7 have suggested that the role of Nav1.7 in pain transduction depends on the precise form of pain. We developed genetic and animal husbandry strategies that overcame the neonatal-lethal phenotype and enabled construction of a global Nav1.7 knockout mouse. Knockouts were anatomically normal, reached adulthood, and had phenotype wholly analogous to human congenital indifference to pain (CIP): compared to littermates, knockouts showed no defects in mechanical sensitivity or overall movement yet were completely insensitive to painful tactile, thermal, and chemical stimuli and were anosmic. Knockouts also showed no painful behaviors resulting from peripheral injection of nonselective sodium channel activators, did not develop complete Freund's adjuvant-induced thermal hyperalgesia, and were insensitive to intra-dermal histamine injection. Tetrodotoxin-sensitive sodium current recorded from cell bodies of isolated sensory neurons and the mechanically-evoked spiking of C-fibers in a skin-nerve preparation each were reduced but not eliminated in tissue from knockouts compared to littermates. Results support a role for Nav1.7 that is conserved between rodents and humans and suggest several possibly translatable biomarkers for the study of Nav1.7-targeted therapeutics. Results further suggest that Nav1.7 may retain its key role in persistent as well as acute forms of pain.

The public health leadership certificate: a public health and primary care interprofessional training opportunity.

This article describes a public health leadership certificate curriculum developed by the Commonwealth Public Health Training Center for employees in public health and medical trainees in primary care to share didactic and experiential learning. As part of the program, trainees are involved in improving the health of their communities and thus gain a blended perspective on the effectiveness of interprofessional teams in improving population health. The certificate curriculum includes eight one-credit-hour didactic courses offered through an MPH program and a two-credit-hour, community-based participatory research project conducted by teams of trainees under the mentorship of health district directors. Fiscal sustainability is achieved by sharing didactic courses with MPH degree students, thereby enabling trainees to take advantage of a reduced, continuing education tuition rate. Public health employee and primary care trainees jointly learn knowledge and skills required for community health improvement in interprofessional teams and gain an integrated perspective through opportunities to question assumptions and broaden disciplinary approaches. At the same time, the required community projects have benefited public health in Virginia.

Burden of rotavirus hospitalisations in young children in three paediatric hospitals in the United States determined by active surveillance compared to standard indirect methods.

AIM: The number of rotavirus hospitalisations is usually estimated from assigned diagnosis codes for gastroenteritis despite lack of validation for these indirect methods. Reliable estimates before and after introduction of vaccines are needed to quantify the absolute impact of new immunisation programs. METHODS: This 2-year study conducted at three hospitals prior to the licensure of the rotavirus vaccines in the USA compared two indirect methods for estimating hospitalisations for rotavirus gastroenteritis with estimates derived from prospective recruitment of children presenting with diarrhoea, vomiting or fever. For active surveillance, rotavirus gastroenteritis was confirmed by demonstration of stool antigen. The indirect residual and proportional methods assumed rotavirus to have caused a proportion of hospitalisations coded as acute gastroenteritis identified from computerised records. RESULTS: There were 447 rotavirus hospitalisations among inpatients 31 days through 4 years of age admitted with vomiting and/or diarrhoea, compared with 306 and 228 hospitalisations identified by the two indirect methods. Only 52% of children hospitalised with gastroenteritis received a qualifying diagnosis code at discharge. Relative to active surveillance, the sensitivity and specificity (95% confidence interval (CI)) in identifying rotavirus-attributable hospitalisations was 45% (95% CI: 43-48%) and 89% (88-90%) for the residual method and 34% (30-39%) and 92% (90-94%) for the proportional method. CONCLUSIONS: Many children admitted to the hospital with diarrhoea, vomiting or fever were not assigned discharge codes for acute gastroenteritis. Consequently, standard indirect methods missed a substantial number of rotavirus-associated hospitalisations, thereby underestimating the absolute number of children who could potentially benefit from vaccination.

Discovery and optimization of aminopyrimidinones as potent and state-dependent Nav1.7 antagonists.

Clinical genetic data have shown that the product of the SCN9A gene, voltage-gated sodium ion channel Nav1.7, is a key control point for pain perception and a possible target for a next generation of analgesics. Sodium channels, however, historically have been difficult drug targets, and many of the existing structure-activity relationships (SAR) have been defined on pharmacologically modified channels with indirect reporter assays. Herein we describe the discovery, optimization, and SAR of potent aminopyrimidinone Nav1.7 antagonists using electrophysiology-based assays that measure the ligand-receptor interaction directly. Within this series, rapid functionalization at the polysubstituted aminopyrimidinone head group enabled exploration of SAR and of pharmacokinetic properties. Lead optimized N-Me-aminopyrimidinone 9 exhibited improved Nav1.7 potency, minimal off-target hERG liability, and improved rat PK properties.

Identification of a potent, state-dependent inhibitor of Nav1.7 with oral efficacy in the formalin model of persistent pain.

Clinical human genetic studies have recently identified the tetrodotoxin (TTX) sensitive neuronal voltage gated sodium channel Nav1.7 (SCN9A) as a critical mediator of pain sensitization. Herein, we report structure-activity relationships for a novel series of 2,4-diaminotriazines that inhibit hNav1.7. Optimization efforts culminated in compound 52, which demonstrated pharmacokinetic properties appropriate for in vivo testing in rats. The binding site of compound 52 on Nav1.7 was determined to be distinct from that of local anesthetics. Compound 52 inhibited tetrodotoxin-sensitive sodium channels recorded from rat sensory neurons and exhibited modest selectivity against the hERG potassium channel and against cloned and native tetrodotoxin-resistant sodium channels. Upon oral administration to rats, compound 52 produced dose- and exposure-dependent efficacy in the formalin model of pain.

Efficacy of the pentavalent rotavirus vaccine, RotaTeq® (RV5), between doses of a 3-dose series and with less than 3 doses (incomplete regimen).

Post-hoc analyses of the Rotavirus Efficacy and Safety Trial (REST) were conducted to determine whether the pentavalent rotavirus vaccine (RV5) confers early protection against rotavirus gastroenteritis (RVGE) before completion of the 3-dose regimen. To evaluate the efficacy of RV5 between doses in reducing the rates of RVGE-related hospitalizations and emergency department (ED) visits in infants who ultimately received all 3 doses of RV5/placebo, events occurring from 2 weeks after the first and second doses to receipt of the subsequent dose (Analysis A) and events occurring from 2 weeks after the first and second doses to 2 weeks after the subsequent dose (Analysis B) were analyzed. In Analysis A, RV5 reduced the rates of combined hospitalizations and ED visits for G1-G4 RVGE or RVGE regardless of serotype between doses 1 and 2 by 100% (95% confidence interval [CI]: 72-100%) or 82% (95% CI: 39-97%), respectively, and between doses 2 and 3, RV5 reduced the rates of combined hospitalizations and ED visits for G1-G4 RVGE or RVGE regardless of serotype by 91% (95% CI: 63-99%) or 84% (95% CI: 54-96%), respectively. Similar rate reductions were observed in Analysis B. These data suggest that RV5 provides a high level of protection between doses against hospitalizations and ED visits for RVGE starting as early as 14 days after the first dose.

Rotavirus genotypes among hospitalized children in Egypt, 2000-2002.

Rotavirus type surveillance is essential to assess the success of rotavirus vaccines. Rotavirus strains collected in 2000-2002 during hospital-based surveillance for diarrhea in Egyptian children were genotyped. Of the 259 (25.2%) rotavirus-positive specimens, 82.4% were common strains (G1p[8], G2p[4], G4p[8]), and the emergent G9 type was detected in 5.3% of samples.

Robustness of the healthcare utilization results from the Rotavirus Efficacy and Safety Trial (REST) evaluating the human-bovine (WC3) reassortant pentavalent rotavirus vaccine (RV5).

BACKGROUND: The Rotavirus Efficacy and Safety Trial was a placebo-controlled Phase III study that evaluated the safety and efficacy of a three-dose pentavalent rotavirus vaccine (RV5) including its effect on healthcare utilization for rotavirus gastroenteritis (RVGE). The per-protocol (PP) analyses, which counted events occurring 14 days after dose 3 among infants without protocol violations, have already been published. This paper evaluates the consistency of the healthcare utilization results based on the modified intention to treat (MITT) analyses with the PP analyses. The MITT analyses include all infants receiving at least one dose of vaccine or placebo and follow-up begins after dose 1. The paper also explores the consistency of the results for different subgroups of the study population with different types of surveillance. METHODS: Data on healthcare utilization for acute gastroenteritis were collected via telephone interviews after administration of the first dose. Parents were either contacted every 6 weeks or every 2 weeks depending on the substudy in which they were enrolled. Those contacted every 2 weeks were also asked to complete symptom diaries. Poisson regression was used to evaluate the effect of RV5 on the rates of RVGE-associated healthcare encounters in all of the analyses. RESULTS: In the first 2 years after vaccination, RV5 reduced the combined rate of hospitalizations and emergency department (ED) visits 88.9% (95% CI: 84.9, 91.9) for all RVGE regardless of serotype in the MITT analysis compared with a 94.5% (95% CI: 91.2, 96.6) reduction based on the G1-G4 PP analysis. By type of surveillance, the rate reductions for the G1-G4 PP analysis were 91.0% (95% CI: 81.7, 95.5) and 95.9% (95% CI: 92.2, 97.8) among parents contacted every 2 weeks (number evaluable = 4,451) and every 6 weeks (number evaluable = 52,683) respectively. CONCLUSIONS: Our analyses demonstrated that the effect of RV5 on reducing the rate of hospitalizations and ED visits based on the MITT analyses were generally consistent with the PP analyses. The rate of events for subgroups with different intensities of surveillance differed but the effect of RV5 on the relative rate reductions were consistent with the results that have already been published. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT00090233.

Locomotor activity in a novel environment as a test of inflammatory pain in rats.

Creating a robust and unbiased assay for the study of current and novel analgesics has been a daunting task. Traditional rodent models of pain and inflammation typically rely on a negative reaction to various forms of evoked stimuli to elicit a pain response and are subject to rater interpretation. Recently, models such as weight bearing and gait analysis have been developed to address these drawbacks while detecting a drug's analgesic properties. We have recently developed the Reduction of Spontaneous Activity by Adjuvant (RSAA) model as a quick, unbiased method for the testing of potential analgesics. Rats, following prior administration of an activity-decreasing inflammatory insult, will positively increase spontaneous locomotor exploration when given single doses of known analgesics. The RSAA model capitalizes on a rat's spontaneous exploratory behavior in a novel environment with the aid of computer tracking software to quantify movement and eliminate rater bias.

Discovery of novel 6,6-heterocycles as transient receptor potential vanilloid (TRPV1) antagonists.

The transient receptor potential cation channel, subfamily V, member 1 (TRPV1) is a nonselective cation channel that can be activated by a wide range of noxious stimuli, including capsaicin, acid, and heat. Blockade of TRPV1 activation by selective antagonists is under investigation in an attempt to identify novel agents for pain treatment. The design and synthesis of a series of novel TRPV1 antagonists with a variety of different 6,6-heterocyclic cores is described, and an extensive evaluation of the pharmacological and pharmacokinetic properties of a number of these compounds is reported. For example, the 1,8-naphthyridine 52 was characterized as an orally bioavailable and brain penetrant TRPV1 antagonist. In vivo, 52 fully reversed carrageenan-induced thermal hyperalgesia (CITH) in rats and dose-dependently potently reduced complete Freund's adjuvant (CFA) induced chronic inflammatory pain after oral administration.

Pharmacological effects of nonselective and subtype-selective nicotinic acetylcholine receptor agonists in animal models of persistent pain.

Nicotinic acetylcholine receptors (nAChRs) are longstanding targets for a next generation of pain therapeutics, but the nAChR subtypes that govern analgesia remain unknown. We tested a series of nicotinic agonists, including many molecules used or tried clinically, on a panel of cloned neuronal nAChRs for potency and selectivity using patch-clamp electrophysiology and a live cell-based fluorescence assay. Nonselective nicotinic agonists as well as compounds selective either for alpha4beta2 or for alpha7 nAChRs were then tested in the formalin and complete Freund's adjuvant models of pain. Nonselective nAChR agonists ABT-594 and varenicline were effective analgesics. By contrast, the selective alpha4beta2 agonist ispronicline and a novel alpha4beta2-selective potentiator did not appear to produce analgesia in either model. alpha7-selective agonists reduced the pain-related endpoint, but the effect could be ascribed to nonspecific reduction of movement rather than to analgesia. Neither selective nor nonselective alpha7 nicotinic agonists affected the release of pro-inflammatory cytokines in response to antigen challenge. Electrophysiological recordings from spinal cord slice showed a strong nicotine-induced increase in inhibitory synaptic transmission that was mediated partially by alpha4beta2 and only minimally by alpha7 subtypes. Taken with previous studies, the results suggest that agonism of alpha4beta2 nAChRs is necessary but not sufficient to produce analgesia, and that the spinal cord is a key site where the molecular action of nAChRs produces analgesia.