Knowledge on asthma, food allergies, and anaphylaxis: Assessment of elementary school teachers, parents/caregivers of asthmatic children, and university students in Uruguaiana, in the state of Rio Grande do Sul, Brazil.

INTRODUCTION: Allergic diseases have become an increasingly common reality in the last years, extending beyond the family context. OBJECTIVE: Assessing the level of knowledge on asthma, food allergies and anaphylaxis of asthmatic children's parents/caregivers (PC), elementary school teachers (EST) and university students (US) in Uruguaiana, RS, Brazil. METHOD: 577 individuals (PC - N=111; EST - N=177; US - N=299) took part in the study, answering the Newcastle Asthma Knowledge Questionnaire (validated for Portuguese) and another questionnaire on Food Allergy (FA) and anaphylaxis. RESULTS: Although PC have asthmatic children, their asthma knowledge level was average, slightly above that of EST and EU. The lack of knowledge on passive smoking, use of medications and their side effects should be highlighted. US have shown to be better informed about FA and anaphylaxis. However, even though a significant proportion of respondents know the most common symptoms of FA and anaphylaxis, few named subcutaneous adrenaline as the drug of choice for treating anaphylaxis. Although a significant number of respondents know about the possibility of anaphylactic reactions happening at school or in activities outside the school, we were surprised by the absence of conditions in schools to provide emergency care to such students. CONCLUSION: Despite the high prevalence of allergic diseases in childhood, asthmatic children's parents/caregivers, elementary school teachers and university students have inadequate levels of knowledge to monitor these patients.

Exercise training, creatine supplementation, and bone health in ovariectomized rats.

UNLABELLED: Evidence suggests that creatine may have some beneficial effects on bone. The study aimed to investigate the effects of exercise alone or combined with creatine on bone health in ovariectomized rats. Findings show that exercise, but not creatine, has an important role in improving bone health. INTRODUCTION: The aim of this study was to investigate the effects of exercise training alone or combined with creatine supplementation on bone health parameters in ovariectomized rats. METHODS: Wistar rats were randomly allocated into one of five groups: (i) sham-operated, (ii) ovariectomized non-trained placebo-supplemented, (iii) ovariectomized non-trained creatine-supplemented, (iv) ovariectomized exercise-trained placebo-supplemented, and (v) ovariectomized exercise-trained creatine-supplemented. Downhill running training and/or creatine supplementation (300 mg/kg body weight) were administered for 12 weeks. Bone mineral content (BMC), bone mineral density (BMD), and biomechanical and histomorphometric parameters were assessed. RESULTS: No interaction effects were observed for BMC and BMD at whole body, femur, and lumbar spine (p > 0.05). Importantly, a main effect of training was detected for whole body BMC and BMD (p = 0.003 and p < 0.001, respectively), femoral BMC and BMD (p = 0.005 and p < 0.001, respectively), and lumbar spine BMC and BMD (p < 0.001 and p < 0.001, respectively), suggesting that the trained animals had higher bone mass, irrespective of creatine supplementation. Main effects of training were also observed for maximal load (p < 0.001), stiffness (p < 0.001), and toughness (p = 0.046), indicating beneficial effects of exercise training on bone strength. Neither a main effect of supplementation nor an interaction effect was detected for biomechanical parameters (p > 0.05). No main or interaction effects were observed for any of the histomorphometric parameters evaluated (p > 0.05). CONCLUSIONS: Exercise training, but not creatine supplementation, attenuated ovariectomy-induced bone loss in this rat model.

Effects of minimally invasive surgical and miniscrew-assisted rapid palatal expansion (MISMARPE) on the nasal cavity and upper airway: a comparative cohort study.

This study was performed to evaluate the impact on the upper airway and nasal cavity of a new minimally invasive surgical and miniscrew-assisted rapid palatal expansion (MISMARPE) technique for the treatment of adult patients with transverse maxillary deficiency, in comparison to surgically assisted rapid palatal expansion (SARPE). Computed tomography scans of 21 MISMARPE and 16 SARPE patients were obtained preoperatively (T0) and at the end of the activation period (T1) and analysed. Linear and volumetric measurements were performed in the dental, alveolar, nasal cavity, and oropharynx regions. Generalised estimating equations were used to consider the intervention time and surgery type, and their interaction. In both groups, measurements were increased at T1 (P < 0.001), except for oropharynx volume (P > 0.05). A greater expansion in nasal cavity floor and median palatal suture was shown for MISMARPE when compared to SARPE (P < 0.001), with the same degree of expander activation (P = 0.094). A trapezoidal (coronal plane) and 'V' shape (axial plane) expansion pattern, was observed after MISMARPE. Both surgical techniques were effective for maxillary expansion in adults. However, MISMARPE was performed without osteotomy of the pterygomaxillary suture, in an outpatient setting and with local anaesthesia.

Should oral chlorhexidine remain in ventilator-associated pneumonia prevention bundles?

Ventilator-associated pneumonia (VAP) is related with high mortality, duration of mechanical ventilation and costs. Recent studies have questioned the safety and effectiveness of oral chlorhexidine to prevent VAP. We sought to verify whether the adverse effects of this substance outweigh its benefits. We searched several databases and selected studies that investigated the use of oral chlorhexidine and its impact on mortality. No association between oral chlorhexidine and lower VAP rates was found on meta-analyses of double-blind randomized trials, however significant increase in mortality was reported. It is speculated that chlorhexidine can cause damage to several organic sectors and cytotoxicity. Although it still can be beneficial in specific settings, robust evidence to recommend its routine application for all mechanically ventilated patients is lacking; therefore, given the possibility of harm, it would be better to follow the principle of non-maleficence until more studies becomes available.

Oxytocin depolarizes mitochondria in isolated myometrial cells.

Oxytocin is known to play important roles in uterine contractions, mediated at least in part by increasing intracellular Ca(2+) concentration ([Ca(2+)](i)), through enhancing extracellular Ca(2+) entry and Ca(2+) release from the sarcoplasmic reticulum, processes that are intimately linked with mitochondria. This study examined the effects of oxytocin on mitochondrial function. This was achieved by measuring the ratiometric JC-1 fluorescence signal in isolated myometrial cells, which provides a relative measure of the mitochondrial membrane potential (ψ(m)), and also by loading the cells with Oregon Green BAPTA-AM to examine changes in [Ca(2+)](i). Oxytocin (1 nm) depolarized the ψ(m) to 73.8 ± 3.7% of the control value (P < 0.05; perfused for 11 min) and also caused a transient increase in [Ca(2+)](i). The depolarization of mitochondrial membrane potential was effectively reversed by 2-aminoethoxydiphenyl borate, nifedipine, Ca(2+)-free solution or oligomycin, with the ratiometric JC-1 fluorescence signal becoming no different from the control value in all cases (i.e. P > 0.05). The reduction in ψ(m) is likely to occur at least in part through the oxytocin-induced increase in [Ca(2+)](i), causing enhanced mitochondrial uptake of Ca(2+) and resultant dissipation of the mitochondrial electrochemical gradient. ATP synthase is also stimulated, which would further contribute to a decrease in ψ(m).

Stability and surgical complications of tooth-borne and bone-borne appliances in surgical assisted rapid maxillary expansion: a systematic review.

The objective of this systematic review was to evaluate the stability and complications of tooth-borne (TB), bone-borne (BB) and hybrid (TB-BB) appliances in surgically assisted rapid maxillary expansion (SARME). Database searches were conducted (PubMed, Embase, Cochrane Library and SciELO), as well as a grey literature search (Google Scholar) and hand searches of reference lists. Forty-six articles were included after study selection (κ=0.854). After eligibility assessment, 16 articles and one article from the grey literature were processed (κ=0.866) and six articles were selected by hand searching, for a total of 23 articles included. Regarding stability, TB appliances showed width relapse rates ranging from 4 to 35% in canines, from 1 to 37% in premolars and from 0.2 to 49.5% in molars. In BB appliances, width relapse rates were 1.7-21% in canines, 1.5% in premolars and 4.6-11.5% in molars. In hybrid appliances, the width relapse rate was 14% in premolars, with a 1.8% overexpansion reported in the molar region. In TB and BB appliances, skeletal relapse rates were similar on the nasal floor (11-53% and 41.6%, respectively) and at the level of the maxilla (18% and 16%, respectively). The most common complications were bone resorption in TB appliances (18.14%) and appliance-related complications in BB appliances (17.9%). The risk of bias was high in 19 studies, medium in three studies and low in one study. The TB and BB appliances used in SARME were considered to have a high long-term stability. BB appliances appeared to have fewer relapses than TB appliances due to a more parallel distribution of forces exerted. However, relapse appears to be highly influenced by postorthodontic treatments, where arch-form coordination is achieved in the consolidation period with the purpose of overexpansion correction, alignment and final vertical adjustments. Further randomised controlled trials with long-term data and large sample sizes are needed to support evidence-based clinical decision-making and to allow meta-analytic studies of stability outcomes regarding the type of anchorage in SARME.

Antibiotic prophylaxis in orthognathic surgery: an overview of systematic reviews.

The purpose of this overview was to assess different antibiotic regimens used in orthognathic surgery and to establish an evidence-based protocol so that beneficial and adverse effects can be determined. A comprehensive literature search for systematic reviews and/or meta-analyses was conducted in MEDLINE (PubMed), EMBASE, and the Cochrane Library until March 2020. Grey literature was investigated in Google Scholar, and a manual search was done of references lists. Two meta-analyses and four systematic reviews met the inclusion criteria. The AMSTAR-2-tool was used to ascertain the potential risk of bias in the included studies, which presented moderate to high methodological quality. Lower infection rates were associated with long-term therapies of penicillin, cefazolin-cephalexin, and amoxicillin-clavulanic-acid, with rates varying from 0% - 3.13%. Higher rates were reported in placebo groups (52.6%) and short-term penicillin therapy (60%). Side effects were reported with cefazolin, clindamycin, and penicillin therapies, including nausea, pain, swelling, headache, vomiting, and skin rash. Evidence suggests that long-term antibiotics can reduce the risk of a surgical site infection (SSI) in orthognathic surgery, but there is uncertainty regarding the effects of one dose of antibiotics preoperatively versus short-term antibiotics. In the same way, intravenous penicillin, cefazolin, clindamycin, and amoxicillin-clavulanic acid kept the infection rates associated with bimaxillary procedures under 3.5%.

Should oral chlorhexidine remain in ventilator-associated pneumonia prevention bundles?

Ventilator-associated pneumonia (VAP) is related with high mortality, duration of mechanical ventilation and costs. Recent studies have questioned the safety and effectiveness of oral chlorhexidine to prevent VAP. We sought to verify whether the adverse effects of this substance outweigh its benefits. We searched several databases and selected studies that investigated the use of oral chlorhexidine and its impact on mortality. No association between oral chlorhexidine and lower VAP rates was found on meta-analyses of double-blind randomized trials, however significant increase in mortality was reported. It is speculated that chlorhexidine can cause damage to several organic sectors and cytotoxicity. Although it still can be beneficial in specific settings, robust evidence to recommend its routine application for all mechanically ventilated patients is lacking; therefore, given the possibility of harm, it would be better to follow the principle of non-maleficence until more studies becomes available.

Minimally invasive intraoral proportional condylectomy with a three-dimensionally printed cutting guide.

The aim of this study was to describe the steps of a minimally invasive surgical technique used to perform a proportional intraoral condylectomy with a three-dimensionally (3D) printed cutting guide. The technique consists of two steps: virtual surgical planning and intraoral condylectomy. During virtual surgical planning, the mandibular ramus was measured bilaterally, the height of the proportional condylectomy was planned virtually, and a cutting guide was 3D printed. In the intraoral condylectomy, the mandibular condyle was approached intraorally, the 3D printed cutting guide was positioned in the sigmoid notch, and the proportional condylectomy was performed. The protocol reported in this technical note is the sum of knowledge acquired from a series of studies published previously by the authors, who have jointly developed a surgical technique that is both minimally invasive and accurate for the treatment of condylar hyperplasia.

Nasolabial soft tissue effects of segmented and non-segmented Le Fort I osteotomy using a modified alar cinch technique-a cone beam computed tomography evaluation.

The aim of this study was to verify soft tissues changes and the effect of a minimally invasive surgical technique in the nasolabial region after segmented and non-segmented Le Fort I osteotomy, using cone beam computed tomography (CBCT) evaluation of three-dimensional (3D) volume surfaces. Two groups were evaluated: group 1, bimaxillary surgery with maxillary segmentation (n=40); group 2, bimaxillary surgery without maxillary segmentation (n=40). In both groups, a specific alar cinching technique was used to control nasal base broadening. CBCT evaluation was performed at three different treatment time points: T0, 1 month before surgery; T1, 1 month after surgery; T2, 1year after surgery. The results showed statistically significant differences in the nasolabial area (P<0.001). For group 1, the mean change in alar base width (Alinf-Alinf) was 1.31±1.40mm at T1 and 0.93±1.77mm at T2; for group 2 these values were 1.12±2.01mm at T1 and 0.54±1.54mm at T2. For group 1, the mean changes in inter-alar width (Al-Al) were 1.68±1.46mm at T1 and 1.49±1.33mm at T2; for group 2, they were 2.22±1.93mm at T1 and 1.34±1.79mm at T2. The alar cinch technique proposed here appears to be effective in controlling nasolabial soft tissue widening.

Hierarchy of surgical stability in orthognathic surgery: overview of systematic reviews.

The purpose was to perform an overview of systematic reviews in order to create a hierarchical scale of stability in orthognathic surgery with the aid of the highest level of scientific evidence. The systematic search was conducted in the PubMed, Embase, and Cochrane Library databases. The grey literature was investigated in Google Scholar and a manual search was done of the references lists of included studies. Fifteen studies were included in the final sample, of which eight were systematic reviews and seven were meta-analyses. These were assessed for methodological quality using the AMSTAR 2 tool and all were considered to be of medium to high methodological quality. The clinical studies included in the 15 reviews and meta-analyses were classified by the review authors as having a moderate to high potential for risk of bias. The hierarchical pyramid of stability in orthognathic surgery was established, with two surgical procedures considered highly unstable: (1) maxillary expansion with semi-rigid internal fixation evaluated at the dental level in the posterior region, and (2) clockwise rotation of the mandible with rigid internal fixation of bicortical screws in the sagittal direction.

Involvement of the Helicobacter pylori plasticity region and cag pathogenicity island genes in the development of gastroduodenal diseases.

Infection by Helicobacter pylori is associated with the development of several gastroduodenal diseases, including gastritis, peptic ulcer disease (gastric ulcers and duodenal ulcers), and gastric adenocarcinoma. Although a number of putative virulence factors have been reported for H. pylori, there are conflicting results regarding their association with specific H. pylori-related diseases. In this work, we investigated the presence of virB11 and cagT, located in the left half of the cag pathogenicity island (cagPAI), and the jhp917-jhp918 sequences, components of the dupA gene located in the plasticity zone of H. pylori, in Brazilian isolates of H. pylori. We also examined the association between these genes and H. pylori-related gastritis, peptic ulcer disease, and gastric and duodenal ulcers in an attempt to identify a gene marker for clinical outcomes related to infection by H. pylori. The cagT gene was associated with peptic ulcer disease and gastric ulcers, whereas the virB11 gene was detected in nearly all of the samples. The dupA gene was not associated with duodenal ulcers or any gastroduodenal disease here analyzed. These results suggest that cagT could be a useful prognostic marker for the development of peptic ulcer disease in the state of São Paulo, Brazil. They also indicate that cagT is associated with greater virulence and peptic ulceration, and that this gene is an essential component of the type IV secretion system of H. pylori.

Peripheral perfusion index does not accurately reflect hypoperfusion in healthy dogs undergoing elective ovariohysterectomy.

This study evaluated the variability of the peripheral perfusion index (PI) in 22 anaesthetised female dogs undergoing elective ovariohysterectomy and examined the relationship between peripheral PI and heart rate, blood pressure, blood pH, end tidal CO2 (EtCO2), O2 saturation (SpO2), core-peripheral temperature gradient (ΔTc-p), partial pressure of CO2 (PCO2), and concentrations of glucose, cortisol, lactate and bicarbonate (HCO3-). Blood pH, lactate and glucose concentrations were determined 15, 30, 45min into the ovariohysterectomy procedure and after extubation. Cortisol concentrations were assessed before anaesthesia and after extubation. Other variables were recorded at every 5min throughout the ovariohysterectomy procedure. Hyperglycaemia was observed in 59% of bitches during surgery, but serum cortisol concentrations remained unchanged. Most measures of perfusion (ΔTc-p, pH, PCO2, EtCO2, SpO2) and heart rate remained unchanged throughout anaesthesia and did not correlate with peripheral PI. Mean arterial pressure increased during the ovariohysterectomy procedure, while peripheral PI decreased, resulting in negative correlations between these variables at 30 and 45min. Lactate concentrations decreased from baseline to the time of measurement post-extubation. Peripheral PI gradually decreased during the ovariohysterectomy procedure, probably reflecting vasoconstriction induced by nociceptive stimuli. Using lactate concentrations as the reference standard for peripheral perfusion, low peripheral PI in healthy bitches undergoing ovariohysterectomy might not represent peripheral hypoperfusion.

Should oral chlorhexidine remain in ventilator-associated pneumonia prevention bundles? / ¿Debe permanecer la clorhexidina oral en los paquetes de prevención de la neumonía asociada al respirador?

Ventilator-associated pneumonia (VAP) is related with high mortality, duration of mechanical ventilation and costs. Recent studies have questioned the safety and effectiveness of oral chlorhexidine to prevent VAP. We sought to verify whether the adverse effects of this substance outweigh its benefits. We searched several databases and selected studies that investigated the use of oral chlorhexidine and its impact on mortality. No association between oral chlorhexidine and lower VAP rates was found on meta-analyses of double-blind randomized trials, however significant increase in mortality was reported. It is speculated that chlorhexidine can cause damage to several organic sectors and cytotoxicity. Although it still can be beneficial in specific settings, robust evidence to recommend its routine application for all mechanically ventilated patients is lacking; therefore, given the possibility of harm, it would be better to follow the principle of non-maleficence until more studies becomes available (AU)

La neumonía asociada al respirador (VAP) está relacionada con una elevada mortalidad, mayor duración de la ventilación mecánica y costes elevados. Estudios recientes han cuestionado la seguridad y la eficacia de la clorhexidina oral para prevenir la VAP. Hemos intentado verificar si los efectos adversos de esta sustancia superan sus beneficios. Se realizaron búsquedas en diversas bases de datos y se seleccionaron estudios que habían investigado el uso de la clorhexidina oral y su impacto sobre la mortalidad. En los metaanálisis de los ensayos aleatorizados a doble ciego no se encontró ninguna asociación entre clorhexidina oral y tasas de VAP más bajas; sin embargo, sí se informó de un aumento significativo de la mortalidad. Se especula que la clorhexidina puede causar daño a varias partes del organismo y citotoxicidad. Pese a que todavía podría ser beneficiosa en entornos específicos, no se dispone de evidencias sólidas para recomendar su aplicación rutinaria para todos los pacientes sometidos a ventilación mecánica; por lo tanto, dada la posibilidad de ocasionar daños, sería mejor seguir el principio de no maleficencia hasta que se disponga de más estudios (AU)

Age and Environment Influences on Mouse Prion Disease Progression: Behavioral Changes and Morphometry and Stereology of Hippocampal Astrocytes.

Because enriched environment (EE) and exercise increase and aging decreases immune response, we hypothesized that environmental enrichment and aging will, respectively, delay and increase prion disease progression. Mice dorsal striatum received bilateral stereotaxic intracerebral injections of normal or ME7 prion infected mouse brain homogenates. After behavior analysis, animals were euthanized and their brains processed for astrocyte GFAP immunolabeling. Our analysis related to the environmental influence are limited to young adult mice, whereas age influence refers to aged mice raised on standard cages. Burrowing activity began to reduce in ME7-SE two weeks before ME7-EE, while no changes were apparent in ME7 aged mice (ME7-A). Object placement recognition was impaired in ME7-SE, NBH-A, and ME7-A but normal in all other groups. Object identity recognition was impaired in ME7-A. Cluster analysis revealed two morphological families of astrocytes in NBH-SE animals, three in NBH-A and ME7-A, and four in NBH-EE, ME7-SE, and ME7-EE. As compared with control groups, astrocytes from DG and CA3 prion-diseased animals show significant numerical and morphological differences and environmental enrichment did not reverse these changes but induced different morphological changes in GFAP+ hippocampal astroglia. We suggest that environmental enrichment and aging delayed hippocampal-dependent behavioral and neuropathological signs of disease progression.

Stability and surgical complications in segmental Le Fort I osteotomy: a systematic review.

This systematic review was conducted to evaluate the stability and surgical complications of segmental Le Fort I osteotomy. The search was divided into a main search (PubMed, Embase, and Cochrane Library), grey literature search (Google Scholar), and manual search. Twenty-three studies were included: 14 evaluating stability as the outcome and nine evaluating surgical complications. The level of agreement between the authors was considered excellent (κ=0.893 for study selection and κ=0.853 for study eligibility). The segmental Le Fort I osteotomy provides stable outcomes in the sagittal plane, is less stable dentally than skeletally in the transverse plane, and provides little stability in the posterior segment after downward movement. The most frequent complications are oral fistula (six studies) and damage to the adjacent teeth (five studies), but the most prevalent complication is postoperative infection (32.62%). Four studies evaluating stability as the outcome showed a medium potential risk of bias, whereas all studies addressing surgical complications showed a high potential risk of bias. The segmental Le Fort I osteotomy should not be excluded from the technical armamentarium in orthognathic surgery. On the contrary, the literature consulted suggests it to be a useful tool for the three-dimensional surgical correction of maxillary malposition.

Normal esophageal pressure topography metrics for data derived from the Sandhill-Unisensor high-resolution manometry assembly in supine and sitting positions.

BACKGROUND: Normal values of the esophageal motor function parameters for high-resolution manometry (HRM-EPT) adopted by the Chicago classification were established using the proprietary system of Given Imaging. It is conceivable that normal values of a system do not apply to data from others. Most studies using HRM were based on supine swallows, whereas deglutition occurs mostly in the upright position. We wished to establish normal values for HRM-EPT parameters obtained with the Sandhill's HRM-EPT system and compare the results in supine and sitting positions. METHODS: Sixty-nine healthy volunteers, 38 females, median age 27 years, were included in this study. All underwent supine HRM, and 34 of them underwent sitting HRM, with at least 10 single 5-mL swallows for analysis obtained in each position. KEY RESULTS: The normal range (5-95th percentiles) for the following parameters was calculated: distal contractile integral (DCI), 606-4998 mmHg·s·cm; contractile front velocity (CFV), 2.0-6.5 cm/s; distal latency (DL), 5.1-8.8 s; intrabolus pressure (IBP), 1.9-17.6 mmHg; upper esophageal sphincter (UES) pressure, 45.2-186.9 mmHg; esophagogastric junction (EGJ) length, 1.8-4 cm; EGJ resting pressure, 8.1-61.6 mmHg, and integrated relaxation pressure (IRP) 2.5-23.5 mmHg. Normal values of EGJ resting pressure, IRP, DCI, and IBP but not CFV, DL, and UES resting pressure were significantly lower in the sitting posture. CONCLUSIONS & INFERENCES: Studies performed with Sandhill's HRM-EPT system should use its own specific normal data. Normal values should be established for different study.

A scintigraphic study of oropharyngeal swallowing dynamics in Chagas' disease.

We studied oropharyngeal function in patients with Chagas' disease and oesophageal disease. Twenty-four patients with Chagas' disease, 17 of them with oesophageal disease, were submitted to scintigraphic oropharyngeal transit. A single swallow of a 10-mL bolus of water labelled with 40 MBq 99m Tc-phytate, followed by image acquisition at 20 images s-1 yielded time-activity curves in which oropharyngeal dynamics was evaluated. Thirteen normal volunteers were used as controls. Oral transit was longer for chagasics with oesophageal disease than for controls (P=0.004) or for chagasics with a normal oesophagus (P=0.028). Oesophageal filling rate, measured by the slope of the ascending aspect of the oesophageal radioactivity curve, was lower for chagasics with oesophageal disease than for controls (P=0.037). Also, maximum oesophageal filling rate was lower (P=0. 021) and occurred later (P=0.003) for chagasics with oesophageal disease than for controls. Pharyngeal clearance was positively correlated with oral transit (r=0.603, P=0.002). We conclude that chagasic oesophageal disease is associated with oral transit delay and a slower oesophageal filling rate.

In vitro and in vivo effects of nitric oxide synthase inhibitors and nitric oxide inactivators on the South American opossum ileocolonic junction.

The potential role of nitrergic nerves in the regulation of the South American (SA) opossum ileocolonic junction (ICJ) function was investigated. In vitro, the effects of nitric oxide (NO) synthase inhibitors and NO inactivators on the non-adrenergic non-cholinergic (NANC) nerve-mediated relaxations of the circular muscle of the SA opossum ICJ were determined by employing isolated strips. Electrical field stimulation (0.2-8.0 Hz) caused frequency-dependent NANC relaxations. Nicotine and ATP also induced concentration dependent NANC relaxations that were abolished by tetrodotoxin (TTX). The relaxation response induced by NANC nerve activation was reduced in a dose dependent manner by NO synthase inhibitors while vasoactive intestinal peptide (VIP) and sodium nitroprusside (SNP) induced relaxations were uninfluenced by these drugs. In vivo, the NO synthase inhibitor, L-NAME, administered into the local artery caused a raise in intraluminal pressure of the ICJ in anaesthetized SA opossums in a L-arginine-preventable manner. Hydroquinone and pyrogallol, while being able to reduce, in a superoxide dimutase (SOD) reversible manner, the relaxations induced by exogenous NO failed to affect the NANC nerve-induced relaxations. Finally, neurones and nerve fibres in the myenteric plexus as well as varicose nerve fibres on the circular smooth layer were positive for NADPH-diaphorase activity. These findings indicate that nitrergic nerves inhibit ICJ circular smooth muscle in vitro and in vivo but cast doubts on the neuromediator being the NO radical.