Biology subjects

Gill, L.

Publications and source records attributed to Gill, L..

4 recordsLinked to original sources

bioRxiv2026

Longitudinal neurochemical profiling after experimental stroke using edited MR spectroscopy

Background: Alterations in excitatory and inhibitory neurotransmission contribute to stroke pathology and recovery, yet longitudinal assessment of these changes in vivo remains limited. We investigated the feasibility of longitudinal edited proton magnetic resonance spectroscopy (1H-MRS) to quantify {gamma}-aminobutyric acid (GABA) and glutamate following experimental focal cerebral ischaemia. Methods: Male rats underwent endothelin-1-induced striatal ischaemia or sham surgery. Longitudinal edited 1H-MRS was performed at baseline and 2-, 7- and 30-days post-stroke at 7-tesla with a MEGA-sLASER sequence. A voxel was positioned within the ipsilesional motor cortex adjacent to the lesion. Behavioural outcomes (grip strength, adhesive removal and CatWalk gait analysis) were assessed alongside spectroscopy, and immunohistochemistry for Iba1, GFAP and ICAM-1 was performed at 30 days. Results: Stroke induced a transient reduction in GABA+/tCr within the ipsilesional motor cortex, with significantly lower concentrations than sham animals at 7 days (p<0.05), returning to baseline by 30 days. Glutamate/tCr and GABA/glutamate ratio were unchanged throughout the study. Behavioural deficits were mild, with significant effects on motor outcomes such as grip strength, gait swing speed and paw placement, while sensory areas of the brain seemed largely unaffected. Histological analysis revealed no persistent differences in cortical Iba1, GFAP or ICAM-1 immunoreactivity at 30 days. Conclusions: Longitudinal 1H-MRS is a feasible approach for monitoring dynamic changes in inhibitory neurochemistry following experimental stroke. The transient reduction in peri-lesional GABA, despite minimal behavioural impairment and an absence of persistent cortical inflammation, supports the use of edited spectroscopy as a translational tool to investigate neurochemical mechanisms underlying network dynamics in post-stroke recovery.

neuroscience↗

bioRxiv2025

Navigating methodological decisions: Balancing rigor and data volume of the Canadian Living Planet Index

The Living Planet Index -- a biodiversity indicator that assesses the relative change of aggregate vertebrate abundance data -- is an indicator used in global and national biodiversity monitoring frameworks. In Canada, the LPI has been modified (C-LPI) -- adopting differing methodological choices relative to the global LPI. However, there is no clear consensus on the most appropriate analytical methods, particularly as they pertain to the treatment of zeros, confidence intervals and uncertainty, time series length and number of data points required, modelling of short time series, removal of outliers, weighting species, and the impact of baseline year selection. Our analysis transparently explores multiple methodological options and the consequent C-LPI output for each of these decision points. Our research does not evaluate the superiority of a single approach but rather provides transparency and accountability in C-LPI reporting. We hope that this will further strengthen the utility of the C-LPI and provide decision makers with the necessary information to appropriately interpret patterns, evaluate progress towards biodiversity targets, and inform conservation action.

ecology↗

bioRxiv2020

Functional maturation of the gut microbiota at weaning is influenced by maternal environment in piglets

The objective of this study was to analyze in piglets the impact of weaning on the production of metabolites by gut bacteria and to determine whether early life environment influences the functional maturation of the gut microbiota. Fecal metabolome and microbiome were analyzed in piglets raised in two separate maternity farms and mixed at weaning. In piglets from both maternity farms, the relative abundance of Lactobacillus and of the predicted function "Fucose degradation" decreased after weaning while the relative abundance of Ruminococcus 2 and of the predicted function "Starch degradation" increased. In piglets from the first maternity farm, the relative concentration of biogenic amines and the relative abundance of Escherichi-Shigella decreased after weaning while the relative concentration of short chain fatty acids and the relative abundance of Christensenellaceae R-7 group and Ruminococcaceae UCG-002 increased. These changes were not observed at weaning in piglets from the second maternity farm probably because they already had high relative concentration of short chain fatty acids and higher relative abundance of Christensenellaceae R-7 group and Ruminococcaceae UCG-002 during the suckling period. In conclusion, the functional maturation of the microbiota at weaning is highly dependent on the maternal environment in piglets. ORIGINALITY - SIGNIFICANCE STATEMENTBacterial metabolites are key molecular intermediates between the gut microbiota and host cells. Our study in piglets reveals that the metabolic activity of the gut microbiota shifts at weaning, a key developmental period for intestinal and immune health. We also show that this functional maturation of the gut microbiota is strongly influenced by maternal environment. Thus, targeting early life environmental factors is a promising strategy to program health trough the production of beneficial bacterial metabolites at the suckling-to-weaning transition.

microbiology↗

bioRxiv2019

Does the margin of stability measure predict stability of gait with a constrained base of support?

This study aimed to determine the validity of the centre of mass position (COM) position and extrapolated COM (XCOM), relative to the base of support, for predicting stability during a walking task where the base of support is constrained. Nine young healthy participants walked on a narrow beam. Three-dimensional motion capture was used to calculate the COM and XCOM relative to the base of support. Steps were classified as having either the COM or XCOM inside or outside the base of support, and were classified as successful (stable - foot placed on the beam) or failed (unstable - foot stepped off the beam). If the COM or XCOM are valid measures of stability, they should be within the base of support for successful steps and outside the base of support for failed steps. Classifying the COM and XCOM inside or outside the base of support correctly predicted successful or failed steps in 69% and 58% of cases, respectively. When the COM or XCOM were outside the base of support, walking faster seemed to help participants to maintain stability. The further the COM or XCOM were outside the base of support during a successful step, the more likely participants were to fail on a subsequent step. The results of this study suggest that both COM and XCOM are valid measures of stability during a beam walking task, but that classifying COM and XCOM as inside or outside the base of support may be over-simplistic.

bioengineering↗