Publications by authors named "M K Dyck"

278 Publications

Proliferation of Peripheral Blood Mononuclear Cells From Healthy Piglets After Mitogen Stimulation As Indicators of Disease Resilience.

J Anim Sci 2021 May 4. Epub 2021 May 4.

Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, SK, Canada.

Disease resilience refers to productivity of an animal under disease. Given the high biosecurity of pig nucleus herds, traits that can be measured on healthy pigs and that are genetically correlated with disease resilience, i.e. genetic indicator traits, offer a strategy to select for disease resilience. Our objective was to evaluate mitogen stimulation assays on peripheral blood mononuclear cells from young healthy pigs as genetic indicators for disease resilience. Data were from a natural disease challenge in which batches of 60 or 75 naïve Yorkshire x Landrace piglets were introduced every three weeks into a continuous flow barn that was seeded with multiple diseases. In this environment, disease resilience traits, including growth, treatment, and mortality rates, were recorded on 3136 pigs that were genotyped with a high-density marker panel. Peripheral blood mononuclear cells from 882 of these pigs from 19 batches were isolated from whole blood collected prior to the disease challenge and stimulated with five mitogens: concanavalin A (ConA), phytohemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS), and phorbol myristate acetate (PMA). Proliferation of cells was evaluated at 48, 72, and 96 hrs and compared to unstimulated samples (rest count). Heritabilities of cell proliferation were estimated using a model with batch as a fixed effect, covariates of entry age, rest count, and complete blood count proportions of lymphocytes, monocytes, eosinophils, and basophils, and pen, litter, and animal genetics as random effects. Heritability estimates were highest for response to ConA (0.30+0.09, 0.28+0.10, 0.17+0.10, and 0.25+0.10 at 48, 72, and 96 hrs after stimulation and for area under the curve across the three time points, respectively). Estimates were in a similar range for response to PHA and PMA, but low for PWM and LPS. Responses to ConA, PHA, and PMA were moderately genetically correlated with several disease resilience traits and in the expected direction but individual estimates were not significantly different from zero due to large standard errors. In conclusion, although validation is needed, mitogen stimulation assays, in particular based on ConA, show promise as genetic indicator traits for disease resilience.
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http://dx.doi.org/10.1093/jas/skab084DOI Listing
May 2021

Dietary Fibre Intake Is Associated with Serum Levels of Uraemic Toxins in Children with Chronic Kidney Disease.

Toxins (Basel) 2021 03 19;13(3). Epub 2021 Mar 19.

Nephrology Section, Department of Internal Medicine and Paediatrics, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium.

Imbalanced colonic microbial metabolism plays a pivotal role in generating protein-bound uraemic toxins (PBUTs), which accumulate with deteriorating kidney function and contribute to the uraemic burden of children with chronic kidney disease (CKD). Dietary choices impact the gut microbiome and metabolism. The aim of this study was to investigate the relation between dietary fibre and gut-derived PBUTs in paediatric CKD. Sixty-one (44 male) CKD children (9 ± 5 years) were prospectively followed for two years. Dietary fibre intake was evaluated by either 24-h recalls (73%) or 3-day food records (27%) at the same time of blood sampling for assessment of total and free serum levels of different PBUTs using liquid chromatography. We used linear mixed models to assess associations between fibre intake and PBUT levels. We found an inverse association between increase in fibre consumption (g/day) and serum concentrations of free indoxyl sulfate (-3.1% (-5.9%; -0.3%) ( = 0.035)), free p-cresyl sulfate (-2.5% (-4.7%; -0.3%) ( = 0.034)), total indole acetic acid (IAA) (-1.6% (-3.0%; -0.3%) ( = 0.020)), free IAA (-6.6% (-9.3%; -3.7%) ( < 0.001)), total serum p-cresyl glucuronide (pCG) (-3.0% (-5.6%; -0.5%) ( = 0.021)) and free pCG levels (-3.3% (-5.8%; -0.8%) ( = 0.010)). The observed associations between dietary fibre intake and the investigated PBUTs highlight potential benefits of fibre intake for the paediatric CKD population. The present observational findings should inform and guide adaptations of dietary prescriptions in children with CKD.
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http://dx.doi.org/10.3390/toxins13030225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003569PMC
March 2021

Non-stationary response of rain-fed spring wheat yield to future climate change in northern latitudes.

Sci Total Environ 2021 Jun 30;772:145474. Epub 2021 Jan 30.

Watershed Science and Modeling Laboratory, Department of Earth and Atmospheric Sciences, Faculty of Science, University of Alberta, Edmonton, AB T6G 2R3, Canada. Electronic address:

The non-stationary response of crop growth to changes in hydro-climatic variables makes yield projection uncertain and the design and implementation of adaptation strategies debatable. This study simulated the time-varying behavior of the underlying cause-and-effect mechanisms affecting spring wheat yield (SWY) under various climate change and nitrogen (N) application scenarios in the Red Deer River basin in agricultural lands of the western Canadian Prairies. A calibrated and validated Soil and Water Assessment Tool and Analysis of Variance decomposition methods were utilized to assess the contribution of crop growth parameters, Global Climate Models, Representative Concentration Pathways, and downscaling techniques to the total SWY variance for the 2040-2064 period. The results showed that the cause-and-effect mechanisms, driving crop yield, shifted from water stress (W-stress) dominated (27 days of W-stress days) during the historical period to nitrogen stress (N-stress) dominated (27 to 35 N-stress days) in the future period. It was shown that while higher precipitation, warmer weather, and early snowmelts, along with elevated CO may favor SWY in cold regions in the future (up to 50% more yields in some sub-basins), the yield potentials may be limited by N-stress (only up to 0.7% yield increase in some sub-basins). The N-stress might be partially related to the N deficiency in the soil, which can be compensated by N fertilizer application. However, inadequate N uptake due to limited evapotranspiration under elevated atmospheric CO might pose restrictions to SWY potentials even in the least N deficient regions. This study uncovers important information on the understanding of spatiotemporal variability of hydrogeochemical processes driving crop yields and the non-stationary response of yields to changing climate. The results also underscore spatiotemporal variability of N-stress due to N deficiency in the soil or N uptake by crops, both of which may restrain SWY by changes in atmospheric CO concentrations in the future.
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http://dx.doi.org/10.1016/j.scitotenv.2021.145474DOI Listing
June 2021

Long-term durability of bicuspid aortic valve repair: a comparison of 2 annuloplasty techniques.

Eur J Cardiothorac Surg 2021 Jan 25. Epub 2021 Jan 25.

Pôle de Recherche Cardiovasculaire, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium.

Objectives: To compare long-term outcomes after bicuspid aortic valve (BAV) repair utilizing the Cabrol annuloplasty versus valve sparing Reimplantation technique.

Methods: From 1996 to 2018, 340 consecutive patients underwent BAV repair. Eighty underwent Cabrol annuloplasty and 189 underwent Reimplantation. Exclusion criteria were re-repairs (n = 6), active endocarditis (n = 4), no annuloplasty (n = 41) and ring or suture annuloplasty (n = 20). We compared both groups for survival, reoperations, valve related events and recurrent severe aortic regurgitation (AR > 2+). Inverse probability weighting (IPW) was used to balance the 2 groups. Cox regression analysis was used to identify outcome predictors.

Results: After weighting, pre- and intraoperative characteristics were similar between groups, except for aorta replacement techniques and operative time, which was longer in the Reimplantation group (P < 0.001). At 12 years, overall survival was similar between groups (IPW: Cabrol 97 ± 2% vs Reimplantation 94 ± 3%, P = 0.52). Freedom from reoperation and freedom from AR > 2+ were significantly lower in the Cabrol group (reoperation IPW: 69 ± 9% vs 91 ± 4%, P = 0.004 and AR > 2+ IPW: 71 ± 8% vs 97 ± 2%, P < 0.001). The Reimplantation technique was the only independent predictor of reoperation (hazard ratio 0.31; confidence interval 0.19-0.7; P = 0.005).

Conclusions: In this study, comparing 2 annuloplasty strategies for BAV repair, we found statistically significant differences in long-term durability favouring the Reimplantation technique, and no differences in overall survival. The results support our current strategy of Reimplantation technique and repair of AR in patients with BAV. Cabrol annuloplasty is obsolete and should be generally abandoned in patients undergoing BAV repair for AR.
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http://dx.doi.org/10.1093/ejcts/ezaa471DOI Listing
January 2021

Inter-rater Reliability of the McKenzie Method of Mechanical Diagnosis and Therapy for the Provisional Classification of Low Back Pain in Adolescents and Young Adults.

J Man Manip Ther 2021 Jan 24:1-7. Epub 2021 Jan 24.

McGill University, Montreal, Canada.

: To investigate the inter-rater reliability of Mechanical Diagnosis and Therapy (MDT)-trained Diplomats in classifying adolescents and young adults with lumbar pain.: Forty-three participants (mean age 15 ± 2 years) with lumbar pain, with or without lower extremity symptoms, were assessed simultaneously by three MDT Diploma holders and classified into one of three groups: 1) Derangement, 2) Dysfunction, 3) Postural/OTHER. Inter-rater reliability was calculated using the Fleiss kappa statistics with 95% confidence intervals (CI). Analyses were repeated with the younger (11 to 15 years old) and older (16 to 21 years old) age groups.: There was moderate reliability (Fleiss kappa = 0.50, 95% CI = 0.45 to 0.54) for the entire sample, which was statistically significant (p < 0.001). There was good reliability in older participants (Fleiss kappa = 0.63, 95% CI = 0.57 to 0.70), but poor reliability in younger participants (Fleiss kappa = 0.33, 95% CI = 0.27 to 0.39). There was 100% agreement in classifications among assessors for 70% of participants.: The MDT system has moderate reliability when classifying lumbar pain in adolescents and young adults. Future reliability studies may include a balanced group for classifications or a second session.
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http://dx.doi.org/10.1080/10669817.2021.1874189DOI Listing
January 2021