Plasticity of vagal afferents at the site of an incision in the wall of the stomach

Our objectives were to determine whether the vagal afferent innervation of the stomach reorganizes after surgery and to observe how different wound closure techniques might influence such a process. The smooth muscle wall of the stomach served as a model because it is densely innervated by vagal axons and is frequently compromised by gastric surgery. Male Sprague-Dawley rats were assigned to one of six groups: three groups served as controls in which the stomach was exposed surgically and a) subjected to no further manipulation, b) traumatized with suture needle punctures of the muscle wall, or c) insulted by the placement of knotted suture thread in the stomach muscle; three surgical groups received a 1.0 cm incision through the ventral muscle wall of the stomach that was closed using either a) absorbable sutures, b) fibrin glue, or c) n-butyl cyanoacrylate. Rats were killed 4 to 7 months post-surgery. Prior to euthanasia, Micro-Ruby was injected into the left nodose ganglion of each rat to label vagal afferent axons and terminals. Twelve days post-injection, the stomachs were processed for microscopy. All groups recovered quickly from surgery, without differences in body weight. The presence of suture material in the muscle wall of the stomach was sufficient to produce reorganization of nearby vagal afferents. In addition, we observed that an incision of the smooth muscle wall of the stomach and the associated damage to vagal afferents provoked reorganization and regeneration of vagal afferents. Vagal remodeling at the incision was characteristic of axonal patterns found in neuromas (unlike the organized regeneration and differentiation that can occur after axotomy central to the target organ). Vagal afferent terminals located at the site of the incision were free nerve endings and growth cone profiles, and not the characteristically complex end organs normally found in the smooth muscle. Finally, the pattern of vagal plasticity was influenced by the wound closure technique used. Overall, the remodeling of afferents was aberrant in nature, and such neural pathology could contribute to the neuropathic symptoms and hyperalgesias associated with gastrointestinal trauma and bariatric surgery.     

A technology using feedback to manage experience based learning

The aim was to establish how ICT could apply feedback principles to experience based learning. Based on a survey of student and staff requirements, we developed a personalized educational technology ('iSUS') that: (1) Made students clear what they should learn; (2) Helped them meet appropriate real patients; (3) Encouraged reflective feedback; (4) Calculated benchmarks from accumulated feedback; (5) Compared individual students' feedback against those benchmarks; (6) Matched clinical activities to curriculum objectives; (7) Gave feedback to teachers and course leads. Bench testing proved the system usable. During seven weeks of real time use, a whole year group of 111 students feedback on 1183 learning episodes. Five hundred and forty-one (46%) of feedback episodes were self initiated. We have successfully prototyped an application of feedback principles to experience based learning that students seem to find useful.     

Pulmonary cystic hydatid disease in Ireland

Background Hydatid disease is rare in Ireland and its incidence and prevalence are unknown. Most cases are diagnosed by a combination of clinical findings, morphological features on imaging and by serological testing. Aims We describe an Irish case of pulmonary hydatid disease detected at bronchoscopy by bronchoalveolar lavage, and discuss the diagnosis and treatment of the disorder.     

Suspected poisoning in children. Study of the incidence of true poisoning and poisoning scare in a defined population in North East Bristol

The distinction between true and suspected poisoning in children has not been made clear in previous work on childhood poisoning. A study of suspected poisoning in children under 15 years of age in a defined population of North East Bristol from November 1970 to July 1973 carried out by the Health Education Council Medical Research Division included 53,000 child-years at risk. The number of suspected poisonings was 3-4/1000 population aged under 15 years per year, with a higher incidence in younger age groups. Detailed investigation of the circumstances of the accidents carried out by a multidisciplinary team showed that at least 65%, and possibly as many as 78% were poisoning scares and not true poisoning. The evidence used by the casualty doctor and by the parents to diagnose poisoning was explored, and in many cases was circumstantial. Children with fathers in nonmanual occupations were over-represented. This may reflect differences in patterns of utilization behaviour rather than true differences in incidence.     

Response from lieberman and colleagues

Respond on comments on Lieberman's article: Cyclosiloxanes Produce Fatal Liver and Lung Damage in Mice. Environ Health Perspect 107:161-165     

Acute and repeated dose oral toxicity of N-acetyl-l-aspartic acid in Sprague–Dawley rats

N-acetyl-l-aspartic acid (NAA) is a constituent of the mammalian central nervous system (CNS) that has been identified in a number of commonly consumed foods. The current study reports the outcome of acute and repeated dose oral toxicology studies conducted with NAA in Sprague-Dawley (SD) rats. No mortalities or evidence of adverse effects were observed in SD rats following acute oral administration of 2000mg/kg NAA. In a separate study, NAA was added to the diets of SD rats (n=10/sex group) at concentrations corresponding to daily doses of 10, 100, or 1000mg/kg/day for 14 consecutive days and 100, 500, and 1000mg/kg/day for another 14 days. All rats survived until scheduled sacrifice and no differences in body weights, feed consumption values, or clinical signs were observed in any of the treatment groups. No biologically significant differences were observed in functional observational battery (FOB), motor activity evaluations, ophthalmologic examinations, hematology, coagulation, clinical chemistry, or organ weights of any of the NAA treatment groups. Further, no test substance-related gross or microscopic changes were observed in NAA exposure groups. Based on these results, NAA was not considered acutely toxic following oral exposure to 2000mg/kg and the no-observed-adverse-effect-level (NOAEL) for systemic toxicity from repeated dose dietary exposure to NAA is 1000mg/kg/day.     

Gold thioglucose selectively damages dorsal vagal nuclei

To characterize the lesion produced in the medulla oblongata by gold thioglucose (GTG), the present experiment quantified the medullary damage in C57B1 mice that had become obese after treatment with 800 mg/kg of GTG at 30 days of age. At the rostrocaudal level of the area postrema, the neurotoxin destroyed up to 75% of the neurons in the medial cell column of the dorsal motor nucleus of the vagus (DMX), while sparing the lateral pole of the nucleus. GTG also produced significant tissue loss in the central and commissural subnuclei of the nucleus of the solitary tract (NST). In contrast, the GTG lesion did not affect cell number in the hypoglossal nucleus or reduce the volume of the area postrema. Additional observations indicated that at 48-72 h after GTG administration the affected regions of the medulla already show advanced necrosis including cell loss and gliosis; and when the relative contributions of hypothalamic, DMX, and NST damage to the obesity that develops are evaluated statistically with partial correlational analysis, it appears the the obesity primarily correlates with the hypothalamic lesion produced by GTG.