Atlas-based knee osteophyte assessment with ultrasonography and radiography: relationship to arthroscopic degeneration of articular cartilage.

OBJECTIVES: To investigate intra- and inter-reader agreement of ultrasonography (US) and conventional radiography (CR) for the evaluation of osteophyte presence and size within the tibiofemoral joint. In addition, to correlate these findings with arthroscopic degeneration of the articular cartilage. METHOD: Forty adult patients with knee pain were enrolled in this study. Knee CR and US scanning of the medial and lateral bone margins were performed on all patients. A novel atlas for the US grading of knee osteophytes was used in the evaluation. The number and size of the osteophytes were evaluated semi-quantitatively in two rounds from both the CR images (four readers) and the US images (14 readers). The Noyes grading system was used for the evaluation of arthroscopic degeneration of the articular cartilage in 26 patients. RESULTS: On average, intra- and inter-reader US and CR agreement was substantial and comparable to each other (κ = 0.60-0.72). US detected more osteophytes than CR at both the medial (65% vs. 48%) and lateral (70% vs. 60%) compartments. A statistically significant correlation between CR- or US-based osteophyte and arthroscopy grades was observed only for US at the medial compartment (rs = 0.747, p < 0.001). CONCLUSIONS: The detection of knee osteophytes using the novel US atlas is as reproducible as reading conventional radiographs. US is more sensitive to detect knee osteophytes than CR. Furthermore, osteophytes detected with US correlate significantly with arthroscopic cartilage changes at the medial knee compartment whereas those detected by CR do not.

Persistence of subclinical sonographic joint activity in rheumatoid arthritis in sustained clinical remission.

BACKGROUND: Sonographic assessment, measuring grey scale (GS) and power Doppler (PD) signals, is a sensitive tool for the evaluation of inflammatory joint activity in patients with rheumatoid arthritis (RA). We evaluated the persistence of PD and GS signals in previously clinically active RA joints that have reached a state of continuous clinical inactivity. METHODS: We performed sonographic imaging of 22 joints of the hands of patients with RA, selected all joints without clinical activity but showing ongoing sonographic signs of inflammation, and evaluated the time from last clinical joint activity. RESULTS: A total of 90 patients with RA with 1980 assessed joints were included in this study. When comparing the mean time from clinical swelling, we found a significantly longer period of clinical inactivity in joints showing low sonographic activity (mean±SD time from swelling of 4.1±3.2 vs 3.1±2.9 years for PD1 vs PD≥2, p=0.031 and 4.5±3.4 vs 3.3±3.2 years for GS1 vs GS≥2, p≤0.0001). CONCLUSIONS: We conclude that subclinical joint activity is long-lasting in RA joints in clinical remission, but attenuates over time. The latter conclusion is based on the observed shorter time duration from last clinical activity for strong compared with weaker sonographic signals.

Relationship between radiographic joint space narrowing, sonographic cartilage thickness and anatomy in rheumatoid arthritis and control joints.

OBJECTIVE: To validate ultrasound (US) for measuring metacarpal cartilage thickness (MCT), by comparing it with anatomical measurement using cadaver specimens. To correlate US MCT with radiographic joint space narrowing (JSN) or width (JSW) in patients with rheumatoid arthritis (RA). METHODS: Bilateral metacarpophalangeal (MCP) joints of 35 consecutive outpatients, with recent hand X-rays, were included in the analysis. Metacarpal and phalangeal cartilage of MCP 2-5 was assessed bilaterally by US. JSW and JSN were evaluated on X-rays by the van der Heijde modified Sharp method (vdHS). In addition, cadaver specimens of MCP 2-5 joints (n=19) were evaluated by anatomical measurement and US. RESULTS: The agreement (intraclass correlation coefficient) between sonographic and anatomical MCT on cadaver specimens of MCP joints was 0.61. MCT of individual MCP joints correlated with individual MCP JSN (r=-0.32, p<0.001) and individual MCP JSW (r=0.72, p<0.001). No correlation was found between phalangeal cartilage thickness and JSN in individual MCP joints. The US MCT summary score for MCP joints 2-5 correlated with summary scores for JSW (r=0.78, p<0.001), JSN (r=-0.5, p<0.001), erosion score of the vdHS (r=-0.39, p<0.001) and total vdHS (r=-0.47, p<0.001). CONCLUSIONS: Sonographic cartilage assessment in MCPs is closely related to anatomical cartilage thickness. Both JSW and JSN by radiography represent cartilage thickness in the MCP joints of patients with RA quite well. Thus, US is a valid tool for measuring MCT if radiographs are not available or in case of joint malalignment.

EULAR recommendations for the use of imaging in the diagnosis and management of spondyloarthritis in clinical practice.

A taskforce comprised of an expert group of 21 rheumatologists, radiologists and methodologists from 11 countries developed evidence-based recommendations on the use of imaging in the clinical management of both axial and peripheral spondyloarthritis (SpA). Twelve key questions on the role of imaging in SpA were generated using a process of discussion and consensus. Imaging modalities included conventional radiography, ultrasound, magnetic resonance imaging, computed tomography (CT), positron emission tomography, single photon emission CT, dual-emission x-ray absorptiometry and scintigraphy. Experts applied research evidence obtained from systematic literature reviews using MEDLINE and EMBASE to develop a set of 10 recommendations. The strength of recommendations (SOR) was assessed by taskforce members using a visual analogue scale. A total of 7550 references were identified in the search process, from which 158 studies were included in the systematic review. Ten recommendations were produced using research-based evidence and expert opinion encompassing the role of imaging in making a diagnosis of axial SpA or peripheral SpA, monitoring inflammation and damage, predicting outcome, response to treatment, and detecting spinal fractures and osteoporosis. The SOR for each recommendation was generally very high (range 8.9-9.5). These are the first recommendations which encompass the entire spectrum of SpA and evaluate the full role of all commonly used imaging modalities. We aimed to produce recommendations that are practical and valuable in daily practice for rheumatologists, radiologists and general practitioners.

Metrologic properties of ultrasound versus clinical evaluation of synovitis in rheumatoid arthritis: results of a multicenter, randomized study.

OBJECTIVE: To evaluate the intraobserver reliability, face validity, and discriminant capacity of different global ultrasound (US) scoring systems for measuring synovitis in rheumatoid arthritis (RA). METHODS: This study was ancillary to a 52-week, multicenter, prospective, randomized, open-label, parallel-group outpatient study conducted in patients with moderate RA who were randomized to receive either etanercept combined with methotrexate or various disease-modifying antirheumatic drugs. A total of 66 different synovitis scoring systems were constructed and evaluated, including 11 different joint combinations; data derived from clinical findings, gray-scale US, and power Doppler US (PDUS); and both binary counts and semiquantitative scores. RESULTS: Due to discontinuation of the trial, only 62 patients, a subset of the initially planned number of patients, were included in this study. Reliability was found to be better for gray-scale US and PDUS than for clinical evaluation of synovitis in patients with stable disease between the screening and baseline visits (range for intraclass correlation coefficient 0.6, 0.95 for gray-scale US and 0.56, 0.93 for PDUS versus 0.31, 0.75 for clinical indices). The median (range) difference in the discriminant capacities of clinical indices versus gray-scale US and versus PDUS was 0.25 (-0.64, 0.96) and -0.025 (-0.59, 0.53), respectively, in the period from baseline to 12 weeks. No relevant differences in metrologic properties were observed regarding the number and composition of joints between the different scoring systems. Our findings suggested that a simplified scoring system referring to gray-scale US and PDUS findings might be sufficient. CONCLUSION: Our findings indicate that gray-scale US and PDUS have better reliability than generally used clinical indices for evaluating synovitis in RA. PDUS has at least as good discriminant capacity as clinical assessment of synovitis for distinguishing between treatment arms.

Which knee and probe position determines the final diagnosis of knee inflammation by ultrasound? Results from a European multicenter study.

PURPOSE: To investigate which knee and probe position best identifies knee inflammation and to determine a cut-off level for abnormal synovial effusion. MATERIALS AND METHODS: 18 experienced sonographers (all rheumatologists) performed ultrasound examinations of the knee joint in patients with knee symptoms and in healthy controls. Each sonographer performed longitudinal suprapatellar ultrasound scans using 9 different configurations at each knee: Midline, parapatallar lateral and parapatellar medial from midline in neutral position (0°) with and without quadriceps muscle contraction and in 30° flexion of the knee. The presence of synovial effusion (SE), the effusion measured in millimeters and the presence of synovial hypertrophy (SH) was noted. RESULTS: A total of 298 knees of 149 subjects (129 patients and 20 controls) were examined. The detection of SH is more sensitive and specific than the detection of SE, independently of the knee and probe position, for the final diagnosis of abnormality. The detection of both synovial hypertrophy and effusion in the knee in neutral position (0°) with quadriceps contraction and with the probe in the midline position, are the best independent predictors for knee abnormalities. Knee effusion > 3.2 mm measured with the probe in the lateral aspect of the knee is the best diagnostic characteristics for predicting pathological SE. CONCLUSION: The best combination for detecting SH and SE is obtained by placing the probe in the midline position with the knee in 0° with quadriceps contraction. A cut-off value for pathological effusion may be obtained in the lateral aspect of the knee.

Structural damage in rheumatoid arthritis assessed by musculoskeletal ultrasound: A systematic literature review by the Structural Joint Damage Task Force of the OMERACT Ultrasound Working Group.

OBJECTIVES: To identify and synthesize the evidence for the use and measurement properties of musculoskeletal ultrasound in assessing structural joint damage in patients with rheumatoid arthritis (RA). METHODS: A systematic literature search (SLR) of the PubMed, Embase and Cochrane Library was performed. Original articles were included published in English reporting on ultrasound of bone erosion, cartilage damage and the measurement properties of ultrasound according to the OMERACT filter 2.1. RESULTS: Of the 1.495 identified articles 149 were included in the final review, most of which reported on cross-sectional studies and used the OMERACT definitions for ultrasonographic pathology. Among these, bone erosions were assessed in 139 (93.3%), cartilage damage in 24 (16.1%), enthesophytes in 8 (5.4%), osteophytes in 15 (10.1%) and malalignment and ankylosis in a single (0.9%) study, respectively. Most studies (126/149, 84.6%) assessed the joints of the hands. The overwhelming majority of studies (127/149, 85.2%) assessed structural joint damage bilaterally. Validity, reliability and responsiveness were assessed in 21 (14.1%), 34 (22.8%) and 17 (11.4%) studies, respectively. CONCLUSION: While the results of this SLR suggest that ultrasound is a sensitive, reliable and feasible tool to detect damage in RA, they also highlight the need for further research and validation. Findings of this SLR will inform the next steps of the OMERACT Ultrasound Working Group in developing an ultrasound score for assessing structural joint damage in patients with RA.

Comorbidity clusters in generalized osteoarthritis among female patients: A cross-sectional study.

OBJECTIVES: To investigate the prevalence of comorbidities among female patients with generalized osteoarthritis (GOA) in comparison to an age- and sex matched control group. To identify clusters of comorbidities in both groups. METHODS: An observational, cross-sectional study was conducted. Consecutive female patients with hand and knee osteoarthritis according to the American College of Rheumatology (ACR) classification criteria were invited to participate in the study. A control group of participants without musculoskeletal symptoms, history or evidence of osteoarthritis or inflammatory rheumatic disease were also included. Cardiovascular, obstructive pulmonary, gastrointestinal, endocrine, neurological, malignant diseases and depression were recorded in both groups. In both study groups comorbidity cluster and factor analysis was performed. RESULTS: The study population included 200 GOA and 200 control participants. The following comorbidities were observed adjusted to Bonferroni correction with a significantly higher prevalence among individuals with GOA: hypertension, uterine leiomyoma, gastroesophageal reflux disease, diverticulosis, upper gastrointestinal tract ulcers, depression, diseases with vertigo (benign paroxysmal positional vertigo and vertebrobasilar insufficiency) and surgery due to otoclerosis. In the GOA group 5 clusters were identified with different comorbidity patterns. CONCLUSION: We report a high comorbidity rate in GOA. Cluster analysis allowed us to identify different comorbidity subsets for vascular, gastrointestinal and malignant gynaecological disorders. Further research is required to understand the links between GOA and non-musculoskeletal comorbidities.

Role of presynaptic nicotinic acetylcholine receptors in the regulation of gastrointestinal motility.

Presynaptic nicotinic acetylcholine receptors (nAChRs) located on cholinergic terminals facilitate the release of acetylcholine (ACh), thereby constituting a fail-safe mechanism at strategic locations, such as the neuromuscular junction, where reliable transmission is vital. Accumulating data indicate that myenteric neurons in the enteric nervous system possess not only somatodendritic nAChRs, which mediate cholinergic transmission between neurons, but also presynaptic nAChRs. Functional evidence shows that these receptors mediate a positive feedback with respect to ACh release from myenteric motoneurons, and might therefore play an important role in the regulation of gastrointestinal motility. These presynaptic nAChRs were found to be more sensitive to nicotinic ligands than somatodendritic nAChRs and could therefore be primary targets of exogenous compounds, such as nicotine. This interaction might provide a neurochemical basis for the effect of smoking on gastrointestinal motility. Another important human pharmacological implication is based on our recent observation that monoamine uptake inhibitor-type antidepressant drugs are able to inhibit presynaptic nAChRs in the enteric nervous system. The disruption of the nAChR-mediated positive feedback modulation by antidepressants might explain the frequent occurrence of constipation, a common side effect, attributed to these drugs. Clarification of the role of presynaptic nAChRs in feedback mechanisms in the enteric nervous system might be instrumental in the development of new drugs affecting gastrointestinal motility.

Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses.

OBJECTIVE: To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses. METHODS: A Delphi-based procedure with 24 recommendations covering five main areas (Duration and place of the course; Faculty members; Content of the course; Evaluation of the teaching skills; TTT competency assessment) was distributed among a group of experts involved in MSUS teaching, in addition to an advisory educational expert being present. Consensus for each recommendation was considered achieved when the percentage of agreement was >75%. RESULTS: 21 of 24 invited participants responded to the first Delphi questionnaire (88% response rate). All 21 participants also responded to the second round. Agreement on 19 statements was obtained after two rounds. CONCLUSIONS: This project has led to the development of guidelines for the conduct, content and format of teaching at the EULAR MSUS TTT Courses that are organised annually, with the aim of training future teachers of EULAR MSUS Courses, EULAR Endorsed MSUS Courses, as well as national and local MSUS Courses. The presented work gives indications on how to homogenise the teaching at the MSUS TTT Courses, thus resolving current discrepancies in the field.

Defining enthesitis in spondyloarthritis by ultrasound: results of a Delphi process and of a reliability reading exercise.

OBJECTIVE: To standardize ultrasound (US) in enthesitis. METHODS: An initial Delphi exercise was undertaken to define US-detected enthesitis and its core components. These definitions were subsequently tested on static images taken from spondyloarthritis patients in order to evaluate their reliability. RESULTS: Excellent agreement (>80%) was obtained for including hypoechogenicity, increased thickness of the tendon insertion, calcifications, enthesophytes, erosions, and Doppler activity as core elementary lesions of US-detected enthesitis. US definitions were subsequently obtained for each elementary component. On static images, the intraobserver reliability showed a high degree of variability for the detection of elementary lesions, with kappa coefficients ranging from 0.13-1. The interobserver kappa values were variable, with the lowest kappa coefficient for enthesophytes (0.24) and the highest coefficient for Doppler activity at the enthesis (0.63). CONCLUSION: This is the first consensus-based US definition of enthesitis and its elementary components and the first step performed to ensure a higher degree of homogeneity and comparability of results between studies and in daily clinical work.

Clinical and ultrasound-based composite disease activity indices in rheumatoid arthritis: results from a multicenter, randomized study.

OBJECTIVE: To evaluate the metrologic properties of composite disease activity indices in rheumatoid arthritis (RA), utilizing information derived from clinical, gray-scale (GS), and power Doppler (PD) ultrasound examinations, and to assess the classification of patients according to disease activity using such indices. METHODS: This ancillary study utilized data from a multicenter, prospective, randomized, parallel-group study conducted in subjects with moderate RA randomized to receive etanercept and methotrexate (ETN + MTX) or usual care (various disease-modifying antirheumatic drugs [DMARDs]). In multimodal indices, the 28 swollen joint count was either supplemented or replaced by clinically nonswollen joints in which the presence of synovitis was detected either by GS and/or PD and was calculated according to the Disease Activity Score in 28 joints (DAS28) or the Simplified Disease Activity Index (SDAI). Reliability, external validity, and discriminative capacity were calculated at baseline/screening by intraclass correlation coefficient, Pearson's correlation, and standardized response mean, respectively. RESULTS: Data from 62 patients (mean ± SD age 53.8 ± 13.2 years, mean ± SD disease duration 8.8 ± 7.7 years, mean ± SD disease activity 4.6 ± 0.5 [DAS28] and 20.9 ± 5.9 [SDAI]) were analyzed, with 32 receiving ETN + MTX and 30 receiving DMARDs. The metrologic properties were at least as good for GS- and/or PD-based indices as for their clinical counterparts. Using GS- and PD-supplemented indices, an additional 67.8% and 32.3% of patients (DAS28-derived and SDAI-derived indices, respectively) could be classified as having high disease activity at the screening visit. CONCLUSION: Multimodal indices incorporating ultrasound and clinical data had similar metrologic properties to their clinical counterparts; certain indices allowed for a significantly larger number of patients to be classified to either high or moderate disease activity at the screening visit.

Ultrasound evaluation of fluid in knee recesses at varying degrees of flexion.

OBJECTIVE: Various methods are utilized in daily practice to obtain optimal information on effusion in the knee. Our aim is to investigate which scanning position provides the best information about synovial fluid in the knee by using ultrasound and to evaluate the magnitude of difference for measuring synovial fluid in 3 major recesses (suprapatellar, medial parapatellar, and lateral parapatellar) of the knee according to various degrees of flexion. METHODS: Sonographers in 14 European centers documented bilateral knee joint ultrasound examinations on a total of 148 knee joints. The largest sagittal diameter of fluid was measured in scans corresponding to the 3 major recesses at different (0°, 15°, 30°, 45°, 60°, and 90°) degrees of flexion of the knee. The difference of measurement of effusion according to transducer position, knee position, and the interaction between them was investigated by analysis of variance followed by Tukey's test. RESULTS: No correlation was noted between patient characteristics and ultrasound detection of effusion. The sagittal diameter of synovial fluid in all 3 recesses was greatest at 30° flexion. Analysis of variance and Tukey's test revealed that the suprapatellar scan and 30° flexion is the best combination for detecting effusion as confirmed by receiver operator characteristic curve analysis. CONCLUSION: The suprapatellar scan of the knee in 30° flexion was the most sensitive position to detect fluid in knee joints. Sagittal diameter of fluid in all 3 recesses increased with the knee in the 30° flexed position as compared to the extended position.

Cigarette smoking and psychiatric disorders in Hungary.

Data from the United States and from several European countries show that patients with major mood disorders, schizophrenia and social phobia smoke at significantly higher rates than the general population. However, there are no published results on this field from Central Europe, including Hungary. In the present study, the rate of current and lifetime smoking of the consecutively screened outpatients with DSM-IV unipolar major depression (n=92), bipolar disorder (n=60), schizophrenia (n=80), schizoaffective disorder (n=42) and panic disorder without major depression (n=60) were assessed and the data were compared to the controls (n=5503), representative for the general population of Hungary. The results showed that, compared to controls, the rates of current and lifetime smoking were significantly higher among patients with unipolar major depression, bipolar disorder, schizophrenia and schizoaffective disorder, but not among patients with panic disorder without major depression. The findings support previous findings from other countries on the strong relationship between cigarette smoking and major mood and schizophrenic spectrum disorders.

Social planning with the urban poor: new government strategies in the making.

PIP: The problem of a rapidly increasing and disorganized urban population has not received its deserved attention. Recently, the magnitude of the problem of unplanned urban growth has become more apparent, and governments are directing their attention to remedial efforts. The biggest challenge, is to devise strategies appropriate to the diverse regions involved and to secure the cooperation of the urban populations in carrying out these strategies. Shortage of funds again makes it imperative to involve communities productively. Micro projects which were considered adequate in the past are proving to be unequal to this new task. The theme of this journal issue is the development of policies, strategies and programs to effectively meet the needs of women and children living in slums and shanty towns, and on finding ways in which the basic services strategy can be applied in urban underprivileged areas. 4 case studies, 2 in Latin America and 2 in Asia, of innovative approaches assisted by UNICEF are included in this issue. The different settings of Rio de Janeiro, Lima, Kuala Lumpur and Colombo reveal large differences in the scope and nature of the problem and the means used to correct it. Also included are the results of field research in 6 developing countries which provide recommendations for alternative approaches to child care in keeping with mothers' work schedules in both rural and urban areas.^ieng

The condition of women and children's well-being.

PIP: The contents of a volume devoted to the condition of women and children's welfare demonstrate that women's legal status, economic resources, and access to skills all influence their ability to fulfill their various maternal roles. Women participate in economic development, but in the lowest paid categories of the labor force. Existing national government structures for women are usually restricted to welfare concerns and have had limited overall effectiveness in raising the status of women. Many of women's health problems are related to their low status in society and could be substantially reduced. Women in developing countries are increasingly faced with economic and social constraints which discourage breast feeding. A number of case studies emphasize different aspects of women's needs, but all recognize women's overwork and lack of time; the necessity of income-generating activities that will allow women to meet their children's needs, and the fact that none of the income-generating projects examined is integrated into an overall governmental development strategy. Structural changes are required to alleviate the problems of women.^ieng

Accelerated immunization programmes and CSDR: their meaning and broader implications for development.

PIP: This editorial introduces a special issue of "Assignment Children" devoted to the theme of universal child immunization by 1990. Not only will this campaign significantly reduce morbidity and mortality from 6 childhood diseases, but it will also, through the experience of massive public participation, create conditions favorable for achieving development goals in areas other than health care. Immunization is a means for enabling those who have grasped the concept of protection of one's children to carry this effort into other areas for other goals. If families are to be empowered in this way, the knowledge and know-how held by the experts at the top must be melded with traditional knowledge and the wish of parents to protect their children from disease and death. The usual concept of development conveys ethnocentric and central power biases as well as a fragemented and sectoral approach. In contrast, accelerated immunization programs represent an example of action within a new development paradigm. This approach addresses not just symptoms, but fundamental causes of underdevelopment in the areas of health and survival. Although the underlying causes of poverty are only marginally affected by such campaigns, the validation of important goals of the majority of the population can release social energy and increase individuals' control over other aspects of their life.^ieng

Some examples of the many models of rooming-in.

PIP: Description of alternatives to the western practice of early postpartum separation of mother and infant, a custom encountered less frequently in less developed countries. The increasing incidence of early mother-child separation is reflected in a concurrent decrease in the number of breastfed babies. Close parent-child contact and feeding on demand also tend to be neglected. The infants thus deprived have increased susceptibility to illness. Changes in hospital practices allowing for rooming-in seem to be correlated with a higher prevalence and duration of breastfeeding after discharge. In rooming-in the newborn infant is kept within easy reach of its mother 24 hours a day. To provide this proximity while minimizing irritation to others sharing the room, as well as decreasing opportunities for neonatal infection, while necessitating as little renovation as possible, several innovative designs have been forwarded. An early model utilizes crib-drawers built into a separating wall between mother's room and nursery; this allows the mother to pull the baby's crib into her room or to push it back into the nursery as desired. Another model utilizes a small sound proof nursery within a larger mother's room (capacity 4-5). In other cases, cribs have been equipped with rollers and mothers allowed free access to the nursery. The thrust, though, is now toward total rooming in; some facilities are being built to accommodate 2 or 3 mothers at most, with their newborns in the same room. It is not yet acceptable in industrialized countries for mother and newborn to share the same bed; however, this is the norm in many underdeveloped countries.^ieng

Functional neurochemical evidence for the presence of presynaptic nicotinic acetylcholine receptors at the terminal region of myenteric motoneurons: a study with epibatidine.

The aim of this study was to verify the presence of presynaptic nicotinic acetylcholine receptors (nAChRs) at the terminals of myenteric motoneurons using a potent and highly selective nicotinic agonist, epibatidine. We examined contraction, and release of [3H]ACh on a guinea-pig longitudinal muscle strip preparation. First, we compared the ability of epibatidine and nicotine to induce isometric contraction and found epibatidine (EC50 = 23.1 nM) to be 300-fold more potent than nicotine (EC50 = 7.09 microM). The release and contraction induced by 30 nM epibatidine were inhibited by the nicotinic antagonist mecamylamine (3 microM) and the Na(+)-channel blocker TTX (1 microM), indicating that the effects are mediated via nAChRs and are fully dependent on the propagation of action potentials. Atropine (0.1 microM) significantly increased the [3H]ACh release but could not block contraction suggesting that a substantial part of the response develops via a noncholinergic mechanism. Epibatidine at a higher concentration (300 nM) induced contraction, which was only partly (45%) inhibited by TTX (1 microM). The TTX-resistant contraction, however, was completely blocked by mecamylamine (3 microM). Our data provide functional neurochemical evidence for the existence of presynaptic nAChRs at myenteric motoneuron terminals and suggest that these receptors can be activated only/by a higher concentration of agonists.