Canadian Medical Association Journal

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ISSN / EISSN : 0820-3946 / 1488-2329
Published by: Joule Inc. (10.1503)
Total articles ≅ 52,349
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Dana Saleh, Scott Lucyk, Eric McGillis
Published: 16 October 2022
Journal: Cmaj
Marie K. Christakis, Lindsay Shirreff
Published: 16 October 2022
Journal: Cmaj
Neil Chanchlani, Emily Chesshyre, James W. Hart
Published: 16 October 2022
Journal: Cmaj
Abstract:
Our senses often receive conflicting multisensory information, which our brain reconciles by adaptive recalibration. A classic example is the ventriloquism aftereffect, which emerges following both cumulative (long-term) and trial-wise exposure to spatially discrepant multisensory stimuli. Despite the importance of such adaptive mechanisms for interacting with environments that change over multiple timescales, it remains debated whether the ventriloquism aftereffects observed following trial-wise and cumulative exposure arise from the same neurophysiological substrate. We address this question by probing electroencephalography recordings from healthy humans (both sexes) for processes predictive of the aftereffect biases following the exposure to spatially offset audiovisual stimuli. Our results support the hypothesis that discrepant multisensory evidence shapes aftereffects on distinct timescales via common neurophysiological processes reflecting sensory inference and memory in parietal-occipital regions, while the cumulative exposure to consistent discrepancies additionally recruits prefrontal processes. During the subsequent unisensory trial, both trial-wise and cumulative exposure bias the encoding of the acoustic information, but do so distinctly. Our results posit a central role of parietal regions in shaping multisensory spatial recalibration, suggest that frontal regions consolidate the behavioral bias for persistent multisensory discrepancies, but also show that the trial-wise and cumulative exposure bias sound position encoding via distinct neurophysiological processes. SIGNIFICANCE STATEMENT Our brain easily reconciles conflicting multisensory information, such as seeing an actress on screen while hearing her voice over headphones. These adaptive mechanisms exert a persistent influence on the perception of subsequent unisensory stimuli, known as the ventriloquism aftereffect. While this aftereffect emerges following trial-wise or cumulative exposure to multisensory discrepancies, it remained unclear whether both arise from a common neural substrate. We here rephrase this hypothesis using human electroencephalography recordings. Our data suggest that parietal regions involved in multisensory and spatial memory mediate the aftereffect following both trial-wise and cumulative adaptation, but also show that additional and distinct processes are involved in consolidating and implementing the aftereffect following prolonged exposure.
Chaocheng Liu, Ian T.Y. Wong, Sheila Au
Published: 16 October 2022
Journal: Cmaj
Abstract:
Objective HCV is characterised by its ability to establish chronic infection in hepatocytes and to replicate in the presence of an inflammation. We mimicked this situation in vivo in immune-competent mice by syngeneic transplantation of HCV replicon-containing mouse hepatoma cells. Design A total of 5 million H-2b positive Hep56.1D cells, carrying a subgenomic genotype (gt) 2a replicon (HCV replicon cells) or stably expressing comparable levels of the HCV NS3/4A protease/helicase complex (NS3/4A hepatoma cells), were injected subcutaneously into syngeneic H-2b-restricted mice. Kinetics of tumour growth, HCV RNA replication levels and HCV-specific immune responses were monitored. For immune monitoring, new H-2b-restricted cytotoxic T cell epitopes within the gt2a NS3/4A region were mapped. Immune mice were generated by DNA-based vaccination. Results HCV replicon and NS3/4A hepatoma cells generated solid tumours in vivo. Similar to what is seen in human HCV infection did HCV RNA replicate in the presence of inflammation. NS3/4A-specific CD8+ T cells seemed to transiently reduce HCV RNA levels. Both CD4+ and CD8+ T cells were required for protection against tumour growth. Vaccine-induced NS3/4A(gt2a)-specific T cells protected against HCV replicon tumours in wild-type, but not in HCV NS3/4A(gt1a)-transgenic mice with dysfunctional HCV-specific T cells. Importantly, as in human HCV infection, HCV replicon cells neither primed nor boosted a strong NS3/4A-specific T cell response. Conclusion Syngeneic transplantation of mouse HCV replicon cells into immune-competent animals mirrors many in vivo events in humans. This system is versatile and can be applied to any genetically modified H-2b-restricted mouse strain.
David M. Rodrigues, Eugene Hsieh, Michael Bernstein, David N. Juurlink
Published: 16 October 2022
Journal: Cmaj
Correction
Published: 16 October 2022
Journal: Cmaj
Abstract:
Summary Plants respond to the surrounding environment in countless ways. One of these responses is their ability to sense and orient their root growth toward the gravity vector. Root gravitropism is studied in many laboratories as a hallmark of auxin-related phenotypes. However, manual analysis of images and microscopy data is known to be subjected to human bias. This is particularly the case for manual measurements of root bending as the selection lines to calculate the angle are set subjectively. Therefore, it is essential to develop and use automated or semi-automated image analysis to produce reproducible and unbiased data. Moreover, the increasing usage of vertical-stage microscopy in plant root biology yields gravitropic experiments with an unprecedented spatiotemporal resolution. To this day, there is no available solution to measure root bending angle over time for vertical-stage microscopy. To address these problems, we developed ACORBA (Automatic Calculation Of Root Bending Angles), a fully automated software to measure root bending angle over time from vertical-stage microscope and flatbed scanner images. Moreover, the software can be used semi-automated for camera, mobile phone or stereomicroscope images. ACORBA represents a flexible approach based on both traditional image processing and deep machine learning segmentation to measure root angle progression over time. By its automated nature, the workflow is limiting human interactions and has high reproducibility. ACORBA will support the plant biologist community by reducing time and labor and by producing quality results from various kinds of inputs. Significance statement ACORBA is implementing an automated and semi-automated workflow to quantify root bending and waving angles from images acquired with a microscope, a scanner, a stereomicroscope or a camera. It will support the plant biology community by reducing time and labor and by producing trustworthy and reproducible quantitative data.
Lauren Vogel
Published: 16 October 2022
Journal: Cmaj
Abstract:
Currently, few researchers think about the carbon footprint of their trial. The Sustainable Trials Study Group reports that clinical trials are carbon intensive and suggests ways to make them more efficient
Rahat Hossain, Joanne Leung-Yee, Mark Sinyor
Published: 16 October 2022
Journal: Cmaj
Abstract:
Background Physical therapy for youth with cerebral palsy (CP) who are ambulatory includes interventions to increase functional mobility and participation in physical activity (PA). Thus, reliable and valid measures are needed to document PA in youth with CP. Objective The purpose of this study was to evaluate the inter-instrument reliability and concurrent validity of 3 accelerometer-based motion sensors with indirect calorimetry as the criterion for measuring PA intensity in youth with CP. Methods Fifty-seven youth with CP (mean age=12.5 years, SD=3.3; 51% female; 49.1% with spastic hemiplegia) participated. Inclusion criteria were: aged 6 to 20 years, ambulatory, Gross Motor Function Classification System (GMFCS) levels I through III, able to follow directions, and able to complete the full PA protocol. Protocol activities included standardized activity trials with increasing PA intensity (resting, writing, household chores, active video games, and walking at 3 self-selected speeds), as measured by weight-relative oxygen uptake (in mL/kg/min). During each trial, participants wore bilateral accelerometers on the upper arms, waist/hip, and ankle and a portable indirect calorimeter. Intraclass coefficient correlations (ICCs) were calculated to evaluate inter-instrument reliability (left-to-right accelerometer placement). Spearman correlations were used to examine concurrent validity between accelerometer output (activity and step counts) and indirect calorimetry. Friedman analyses of variance with post hoc pair-wise analyses were conducted to examine the validity of accelerometers to discriminate PA intensity across activity trials. Results All accelerometers exhibited excellent inter-instrument reliability (ICC=.94–.99) and good concurrent validity (rho=.70–.85). All accelerometers discriminated PA intensity across most activity trials. Limitations This PA protocol consisted of controlled activity trials. Conclusions Accelerometers provide valid and reliable measures of PA intensity among youth with CP.
Gabriella Jacob, Melissa Schorr, Louise M. Moist
Published: 16 October 2022
Journal: Cmaj
Abstract:
Aim To document the changing pattern of nosocomial infection on a tertiary neonatal unit before and after the introduction of an infection control care bundle. Nosocomial sepsis is a serious problem for neonates admitted for intensive care and may be related to suboptimal infection control measures.1 Methods Retrospective data on all positive blood cultures and infants admitted to the NICU were obtained for the periods 2002–2009 straddling the introduction of a range of measures in 2007 including improved skin antisepsis, hand washing training, audit and a standardised line handling e-learning module. Nosocomial sepsis was defined as a positive blood culture after 72 h of life. Results Gestation, sex and birth weight were comparable in each period. The number of positive blood cultures (after 72 h) declined sequentially from 28.7 (2007) to 20.3 (2009) per 1000 ITU days, an overall 29.3% reduction. The number of infection episodes/1000 ITU days fell from 16.7 (2007) to 13.4 (2008) and 11.1 (2009). CONS were the predominant isolate (66.2% 2002–2007, 61.7% 2008–2009). CONS in addition to Staphylococcus aureus (20.2%) accounted for 82% of all nosocomial infections during 2008–2009. Gram negative organisms accounted for 8% in 2002–2007 as compared to 6.4% in 2008–2009. Conclusion The introduction of a bundled infection control intervention on our unit is associated with a progressive decrease in the incidence of nosocomial infection.
Justin White, Joanne Hickey, Donna Gilmour, Afshin Ansari
Published: 10 October 2022
Journal: Cmaj
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