Enteral feeding reduces metabolic activity of the intestinal microbiome in Crohn's disease: an observational study.

BACKGROUND/OBJECTIVES: Enteral feeding will induce remission in as many as 80-90% of compliant patients with active Crohn's disease (CD), but its method of action remains uncertain. This study was designed to examine its effects on the colonic microbiome. METHODS/SUBJECTS: Healthy volunteers and patients with CD followed a regimen confined to enteral feeds alone for 1 or 2 weeks, respectively. Chemicals excreted on breath or in faeces were characterised at the start and at the end of the feeding period by gas chromatography/mass spectrometry. RESULTS: One week of feeding in healthy volunteers caused significant changes in stool colour and deterioration in breath odour, together with increased excretion of phenol and indoles on the breath. Feeding for 2 weeks in patients with CD produced significant improvements in symptoms and a decrease in the concentration of C-reactive protein. The faecal concentrations of microbial products, including short-chain fatty acids (SCFAs), and potentially toxic substances, including 1-propanol, 1-butanol and the methyl and ethyl esters of SCFAs, showed significant falls. CONCLUSIONS: A significant change occurs in the production of microbial metabolites after enteral feeding in both healthy volunteers and patients with CD. Many of those detected in CD are toxic and may feasibly lead to the immunological attack on the gut microbiota, which is characteristic of inflammatory bowel disease. The reduction in the production of such metabolites after enteral feeding may be the reason for its effectiveness in CD.

Is the donut in front of the car? An electrophysiological study examining spatial reference frame processing.

The process of describing an object's location relative to another object results in ambiguity. How do people handle this ambiguity? The present studies examined spatial language processing when use of different reference frames results in ambiguity. We investigated whether electrophysiological (ERP) measures of cognitive processing may elucidate underlying reference frame processing; in particular, we were interested in semantic integration. ERP results showed a larger N400, peaking between 300 and 375 ms, when the intrinsic frame was not used. Behavioural results mirrored this finding, indicating a reduced cognitive processing requirement for the intrinsic reference frame. Previous work has not definitively tied spatial reference frame processing to specific ERP components and their associated cognitive processes. Although the N400 peak seen in this data is early, additional work supports the N400 interpretation, thereby linking spatial frame processing to semantic integration. Results are discussed within the larger context of spatial reference frame processing.

Goal-specific influences on the representation of spatial perspective.

In two experiments, subjects learned an unfamiliar campus environment, either by studying a map or by navigating. During acquisition, the subjects had one of two spatial goals: to learn the layout of the building (survey goal) or to learn the fastest routes between locations (route goal). Spatial memory was tested with several tasks, some assessing survey perspective processing and some assessing route perspective processing. Results indicate multiple influences on the representation of spatial perspective. Learning condition influenced performance. Individuals studying maps gave more accurate responses to some survey perspective tasks, whereas individuals navigating gave more accurate responses to some route perspective tasks. Spatial goals also influenced performance. Having a route goal enhanced performance on route perspective tasks; having a survey goal enhanced performance on survey perspective tasks. These findings are discussed in the context of research indicating flexibility when processing spatial perspective. Individuals can use spatial information from different perspectives, often doing so in a goal-directed manner.