McMaster University

About: McMaster University is a education organization based out in Hamilton, Ontario, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 41361 authors who have published 101269 publications receiving 4251422 citations.

Topological phases and the quantum spin Hall effect in three dimensions

Abstract: We show the existence of topological phases of Bloch insulators with time-reversal symmetry in three dimensions. These phases are characterized by topological ${Z}_{2}$ invariants whose stability is studied using band-touching arguments. Unlike insulators which break time-reveral symmetry, some of these topological phases are intrinsically three dimensional. The number of invariants (four) needed to specify the phase of these insulators also differs from the time-reversal-breaking case. The relation between these phases and the quantum spin Hall effect in three dimensions is investigated.

Intestinal microbiota in functional bowel disorders: a Rome foundation report

Abstract: It is increasingly perceived that gut host–microbial interactions are important elements in the pathogenesis of functional gastrointestinal disorders (FGID) The most convincing evidence to date is the finding that functional dyspepsia and irritable bowel syndrome (IBS) may develop in predisposed individuals following a bout of infectious gastroenteritis There has been a great deal of interest in the potential clinical and therapeutic implications of small intestinal bacterial overgrowth in IBS However, this theory has generated much debate because the evidence is largely based on breath tests which have not been validated The introduction of culture-independent molecular techniques provides a major advancement in our understanding of the microbial community in FGID Results from 16S rRNA-based microbiota profiling approaches demonstrate both quantitative and qualitative changes of mucosal and faecal gut microbiota, particularly in IBS Investigators are also starting to measure host–microbial interactions in IBS The current working hypothesis is that abnormal microbiota activate mucosal innate immune responses which increase epithelial permeability, activate nociceptive sensory pathways and dysregulate the enteric nervous system While we await important insights in this field, the microbiota is already a therapeutic target Existing controlled trials of dietary manipulation, prebiotics, probiotics, synbiotics and non-absorbable antibiotics are promising, although most are limited by suboptimal design and small sample size In this article, the authors provide a critical review of current hypotheses regarding the pathogenetic involvement of microbiota in FGID and evaluate the results of microbiota-directed interventions The authors also provide clinical guidance on modulation of gut microbiota in IBS

The role of the hippocampus in the pathophysiology of major depression.

Abstract: Converging lines of research suggest that the hippocampal complex (HC) may have a role in the pathophysiology of major depressive disorder (MDD). Although postmortem studies show little cellular death in the HC of depressed patients, animal studies suggest that elevated glucocorticoid levels associated with MDD may negatively affect neurogenesis, cause excitotoxic damage or be associated with reduced levels of key neurotrophins in the HC. Antidepressant medications may counter these effects, having been shown to increase HC neurogenesis and levels of brain-derived neurotrophic factor in animal studies. Neuropsychological studies have identified deficits in hippocampus-dependent recollection memory that may not abate with euthymia, and such memory impairment has been the most reliably documented cognitive abnormality in patients with MDD. Finally, data from imaging studies suggest both structural changes in the volume of the HC and functional alterations in frontotemporal and limbic circuits that may be critical for mood regulation. The extent to which such functional and structural changes determine clinical outcome in MDD remains unknown; a related, but also currently unanswered, question is whether the changes in HC function and structure observed in MDD are preventable or modifiable with effective treatment for the depressive illness.