84 results on '"Bélanger, N."'
Search Results
2. Contrasted growth response of hybrid larch (Larix × marschlinsii), jack pine (Pinus banksiana) and white spruce (Picea glauca) to wood ash application in northwestern Quebec, Canada
- Author
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Bélanger N, Palma Ponce G, and Brais S
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Wood Ash ,Fertilization ,Boreal Forest ,Soil Properties ,Foliar Nutrition ,Tree Growth ,Forestry ,SD1-669.5 - Abstract
The use of wood ash as a soil amendment in afforestation and reforestation efforts is increasing. While most studies suggest benefits or neutral results on tree growth and survival, a few studies indicate adverse effects. Hybrid larch, jack pine and white spruce were studied at three northwestern Quebec plantation sites after they received wood ash at two application rates. Soil chemical properties, foliar nutrients and seedling growth and mortality were monitored over a period of eight years. The response of soil to ash application was mostly observed in the forest floor and was more pronounced in year 3 than year 8, likely due to the acidifying nature of the boreal soils studied. Jack pine growth increased linearly with wood ash application rates, white spruce growth showed an inconsistent and delayed positive response under the higher application rate, and hybrid larch growth and survival were either increased or decreased under the lower application rate depending of site but decreased at all sites under the higher application rate. The divergence in growth response between tree species underlines a trade-off between species with rapid acquisition of resources (e.g., pine, larch) to species that use more conservative strategies and store nutrients in their tissues for longer periods (e.g., spruce). In the case of hybrid larch, it accumulated larger amounts of Mn in its needles under the higher application rate and thus, the high bioavailability of Mn appears to have been detrimental to its survival and growth. Its higher sensitivity to Mn addition from ash is likely due to its highly acquisitive (nutrients) nature compared to other coniferous species as well as the initial levels of available Mn levels in the soil. The contrasted growth responses reported here under similar growing conditions highlight the importance of identifying suitable species, sites and application rates to maximize the benefits of wood ash amendments for future tree plantations in the boreal forest.
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- 2021
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3. A GLYCOSYLATED HEMOGLOBIN ABOVE 6% IS ASSOCIATED WITH A HIGH RISK OF DEVELOPING CYSTIC FIBROSIS–RELATED DIABETES AND A LOWER PROBABILITY OF WEIGHT GAIN IN BOTH ADULTS AND CHILDREN WITH CYSTIC FIBROSIS
- Author
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Potter, K., primary, Racine, F., additional, Bonhoure, A., additional, Boudreau, V., additional, Bélanger, N., additional, Coriati, A., additional, Shohoudi, A., additional, Lavoie, A., additional, Senior, P., additional, Mailhot, G., additional, and Rabasa-Lhoret, R., additional
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- 2023
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4. First Rotation Biomass Production and Nutrient Cycling within Short-Rotation Coppice Willow Plantations in Saskatchewan, Canada
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Hangs, R. D., Schoenau, J. J., Van Rees, K. C. J., Bélanger, N., Volk, T., and Jensen, T.
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- 2014
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5. Leaf Litter Decomposition and Nutrient-Release Characteristics of Several Willow Varieties Within Short-Rotation Coppice Plantations in Saskatchewan, Canada
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Hangs, R. D., Schoenau, J. J., Van Rees, K. C. J., Bélanger, N., and Volk, T.
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- 2014
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6. Chemical composition of forest floor and consequences for nutrient availability after wildfire and harvesting in the boreal forest
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Thiffault, E., Hannam, K. D., Quideau, S. A., Paré, D., Bélanger, N., Oh, S.-W., and Munson, A. D.
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- 2008
7. A GLYCOSYLATED HEMOGLOBIN ABOVE 6% IS ASSOCIATED WITH A HIGH RISK OF DEVELOPING CYSTIC FIBROSIS–RELATED DIABETES AND A LOWER PROBABILITY OF WEIGHT GAIN IN BOTH ADULTS AND CHILDREN WITH CYSTIC FIBROSIS
- Author
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Potter, K., Racine, F., Bonhoure, A., Boudreau, V., Bélanger, N., Coriati, A., Shohoudi, A., Lavoie, A., Senior, P., Mailhot, G., and Rabasa-Lhoret, R.
- Published
- 2023
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8. Rapid biomass estimation using optical stem density of willow ( Salix spp.) grown in short rotation
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Ens, J.A., Farrell, R.E., and Bélanger, N.
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- 2009
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9. Is the past history of acidic deposition in eastern Canada reflected in sugar maple's tree rings 87Sr/86Sr, Sr and Ca concentrations?
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Houle, D., primary, Marty, C., additional, Gagnon, C., additional, Gauthier, S. Bilodeau, additional, and Bélanger, N., additional
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- 2021
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10. Abstracts of the Poster Sessions
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Brack, C., Beyer, P., Dinkelacker, G., Müller, H. P., Ball, P., Knuppen, R., Sack, J., Blum, M., Raker, Z., Tulchinsky, T., Gutekunst, R., Akstein, A., Albisu, M., Potau, N., Maya, A., Gussiner, M., Vicens-Calvet, E., Vaandrager, G. J., Wilma, T., Gons, M. H., Vijlder, J. J. M., Vulsma, T., Colon, C., Alonso-Fernandez, J. R., Castineiras, D. E., Romero, M. E., Fraga, J. M., Pena, J., Ackermann, G., Ackernmsnn, W., Willgerodt, H., Fiebig, H., Thiele, H. J., Morissette, J., Bélanger, N., Fiset, P., Dussault, J. H., Laberge, C., Fukushi, M., Arai, O., Mitzushima, Y., Takasugi, N., Eàndo, M., Matsuura, N., Fujimoto, S., Sinha, A. K., Al-Mazidi, A., Elvira, M. C. Ruiz, Brook, C. G. D., Ekins, R. P., Rubinstein, M., Jeghers, O., Mathur, R., Maerschalk, C., Errons, A. M., Gruters, A., Bogner, U., Schleusener, H., Helge, H., Hsiao, K. J., Shieh, M. J., Chiang, S. H., Su, F. Y., Chiovato, L., Giusti, F. L., Santini, F., Bassi, P., Vitti, P., Marcocci, C., Tonacchera, M., Ciampi, M., Fenzi, G. F., Pinchera, A., Brown, R. S., Keating, P., Mitchell, E., Ilirki, A., Larsson, A., Karlssan, F. A., Capiau, H., Roelen, L., Clara, R., Addison, G. M., Rosenthal, M., Price, D. A., Sorcini, M. Carta, Carta, S., Diodato, A., Fazzini, C., Grandolfo, M. E., Donati, L., Romagnoli, C., Luciano, R., Bourdoux, P., Delange, F., Mengreli, C., Pantelakis, S., Swennen, B., Vanderpas, J., Abeele, P., Gillies, J., Thilly, C., Schepper, J., Wolf, D., Smits, L., Chanoine, J. P., Steppe, M., Bergmann, P., Biarent, D., Delaet, M. H., Bouton, J. M., Hayashi, M., Shimohira, M., Saisho, S., Suzuki, H., Shimozawa, K., Iwakawa, Y., Bellisario, R., Freligh, L. J., Wiley, A. M., Cower, M. L., Pandian, M. R., Bruyn, R., Grant, D. B., Eldar, D., Amado, O., Péter, F., Blatniczky, L., Breyer, H., Ng, W. K., Leung, S. P., Hulse, J. A., Bovet, J., Ehrlich, R., Sorbara, D., Rickards, A., Coakley, J., Francis, I., Armstrong, S., Medson, H., Connelly, J., Fuggle, P., Murphy, G., Thorley, G., Toublanc, J. E., Rives, S., Job, J. C., Ibanez, L., Group, Catalan Collaborative, Rondanini, G. F., Bollati, A., Porta, V. Della, Cerabolini, R., Lenti, C., Rovey, L., Manzoni, A., Chiumello, G., Bargagna, S., Cittadoni, L., Falciglia, G., Ferretti, G., Marcheschi, M., Giovato, L., Sorhara, D., Delange, François, editor, Fisher, Delbert A., editor, and Glinoer, Daniel, editor
- Published
- 1989
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11. Periglacial fires and trees in a continental setting of Central Canada, Upper Pleistocene
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Bélanger, N., primary, Carcaillet, C., additional, Padbury, G. A., additional, Harvey-Schafer, A. N., additional, and Van Rees, K. J. C., additional
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- 2014
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12. Soil weathering rates in 21 catchments of the Canadian Shield
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Houle, D., primary, Lamoureux, P., additional, Bélanger, N., additional, Bouchard, M., additional, Gagnon, C., additional, Couture, S., additional, and Bouffard, A., additional
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- 2012
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13. Soil weathering rates in 21 catchments of the Canadian Shield
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Houle, D., primary, Lamoureux, P., additional, Bélanger, N., additional, Bouchard, M., additional, Gagnon, C., additional, Couture, S., additional, and Bouffard, A., additional
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- 2011
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14. Influence of landscape on the apportionment of Ca nutrition in a Boreal Shield forest of Saskatchewan (Canada) using 87Sr/86Sr as a tracer
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Bélanger, N., primary and Holmden, C., additional
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- 2010
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15. Calcium isotope fractionation in a boreal forest ecosystem
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Holmden, C., primary and Bélanger, N., additional
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- 2006
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16. Determination of exchangeable hydrogen ions in boreal shield soils of Quebec
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Bélanger, N., primary, MacDonald, J D, additional, Paré, D., additional, Thiffault, E., additional, Claveau, Y., additional, and Hendershot, W H, additional
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- 2006
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17. Identification des compartiments responsables de la qualité des eaux de surface d'un petit bassin versant du centre du Nouveau-Brunswick (Canada): application et analyse du modèle hydrochimique EMMA
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Bélanger, N., primary, Hendershot, W. H., additional, Bouchard, M., additional, and Jolicoeur, S., additional
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- 2005
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18. Wavelength tunable, modelocked semiconductor fibre ring laser incorporating a high-birefringence Sagnac loop
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Chen, L.R., primary and Bélanger, N., additional
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- 2005
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19. Column Leaching Using Dry Soil to Estimate Solid-Solution Partitioning Observed in Zero-Tension Lysimeters. 1. Method Development
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MacDonald, J D, primary, Bélanger, N., additional, and Hendershot, W H, additional
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- 2004
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20. Column Leaching using Dry Soil to Estimate Solid-Solution Partitioning Observed in Zero-Tension Lysimeters. 2. Trace Metals
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MacDonald, J D, primary, Bélanger, N., additional, and Hendershot, W. H., additional
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- 2004
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21. Planar waveguides in ZBLAN fabricated by He ion implantation
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Zhao, Y., primary, LaRochelle, S., additional, Knystautas, É.J., additional, Bélanger, N., additional, Villeneuve, A., additional, and Saad, M., additional
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- 2000
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22. Rms characteristics of pulses in nonlinear dispersive lossy fibers (Optics Comm. 117 (1995) 56)
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Bélanger, P.-A., primary and Bélanger, N., additional
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- 1996
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23. Bright solitons on a cw background
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Bélanger, N., primary and Bélanger, P.-A., additional
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- 1996
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24. Dispersion and Self-Phase Modulation Compensation Based on a Negative Nonlinearity
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Paré, C., primary, Villeneuve, A., additional, Bélanger, P.-A., additional, Bélanger, N., additional, and Doran, N.J., additional
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- 1996
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25. Bright Soliton-Like Pulses in Self-Defocusing Material
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Bélanger, N., primary, Villeneuve, A., additional, and Aitchison, J. S., additional
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- 1996
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26. Rms characteristics of pulses in nonlinear dispersive lossy fibers
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Bélanger, P.-A., primary and Bélanger, N., additional
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- 1995
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27. Soil weathering rates in 21 catchments of the Canadian Shield.
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Houle, D., Lamoureux, P., Bélanger, N., Bouchard, M., Gagnon, C., Couture, S., and Bouffard, A.
- Abstract
Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K) for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmol
c ha-1 yr-1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r =0.80 and 0.64) with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51 %. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas as well as adequately predict absolute weathering rates values for the sum of base cations, Ca and Mg. [ABSTRACT FROM AUTHOR]- Published
- 2011
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28. Low-power configurable and generic shift register hardware realisations for convolutional encoders and decoders.
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Dubois, M., Savaria, Y., Haccoun, D., and Bélanger, N.
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FIELD programmable gate arrays ,SHIFT registers ,DECODERS & decoding ,REGISTERS (Computers) ,GATE array circuits ,PROGRAMMABLE logic devices - Abstract
Novel methods for implementing low-power hardware and configurable architectures comprising several different kinds of shift registers in field programmable gate arrays are presented. New approaches are also described to reduce the power dissipation of shift register structures without compromising their configurability. The proposed structures are particularly effective to reduce the power dissipation of shift registers of medium and large lengths. A systematic method to select the best shift register structure is also provided. The proposed structures and the selection method are generic, and they can be configured statically or dynamically. It is shown that they are well suited for implementing powerful convolutional encoders and suitable decoders associated with forward error correction techniques such as iterative threshold decoding. [ABSTRACT FROM AUTHOR]
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- 2006
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29. Feasibility and accuracy of at-home glucose tolerance tests for cystic fibrosis related diabetes screening.
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Alexandre-Heymann L, Boudreau V, Bélanger N, Mostkowska A, Bonhoure A, Lavoie A, Rabasa-Lhoret R, and Coriati A
- Abstract
Background: Adult people living with Cystic Fibrosis (CF) undergo annual screening for CF-related diabetes. These tests represent a burden and can lead to undesirable effects resulting in low adherence. The objectives of this study were to 1) compare gold-standard in-hospital oral glucose tolerance testing (OGTT) with at-home options, and 2) evaluate acceptability of at-home options., Methods: A total of 34 adults living with CF undertook 3 types of OGTTs in standardized conditions within two weeks: 1) in a hospital using a 75 g glucose beverage, 2) at home with the same glucose beverage, and 3) at home using a standardized quantity of candy. Glucose levels were measured prior to the OGTT, after 1 and 2 hours. Concordance of glucose measurement, side effects and general appreciation were assessed across the three options., Results: Mean blood glucose was comparable among the three tests. Glucose tolerance categorization (normal, impaired glucose tolerance, or diabetes) was concordant with the hospital reference test in 59 % of participants for the glucose beverage and 75 % for the candies. Side effects were mild with all types of OGTTs, and 94 % of participants preferred the home options. Among the at-home OGTTs, the glucose beverage was preferred to the candy option., Conclusions: Home-based OGTT could be an alternative to gold standard hospital-based OGTT testing, improving adherence to annual testing and reducing costs. However, the discrepancy between various OGTT testing methods could lead to diagnosis dilemma. This approach should be tested on a larger sample size., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This work was supported by a CF Circle of care grant from Vertex Pharmaceuticals Incorporated awarded to R. Rabasa-Lhoret. Vertex was not involved in the study design, collection, analysis, interpretation of data, writing of the report or in the decision to submit the article for publication., (Copyright © 2024 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.)
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- 2024
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30. Association between cystic fibrosis transmembrane regulator genotype and clinical outcomes, glucose homeostasis indices and CF-related diabetes risk in adults with CF.
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Bélanger N, Bonhoure A, Kherani T, Boudreau V, Tremblay F, Lavoie A, Carricart M, Marwaha A, Rabasa-Lhoret R, and Potter KJ
- Abstract
People living with cystic fibrosis (pwCF) homozygous for F508del present more severe phenotypes. PwCF with compound heterozygous genotypes F508del /A455E and F508del /L206W may have milder cystic fibrosis (CF) phenotypes. We compared F508del homozygotes and common compound heterozygotes (F508del and a second pathogenic variant) in adult patients. Nutritional, pulmonary function and glucose homeostasis indices data were collected from the prospective Montreal CF cohort. Two-hundred and three adults with CF having at least one F508del variant were included. Individuals were divided into subgroups: homozygous F508del/F508del (n=149); F508del/621+1G>T (n=17); F508del/711+1G>T (n=11); F508del/A455E (n=12); and F508del/L206W (n=14). Subgroups with the F508del/L206W and F508del/A455E had a lower proportion with pancreatic exocrine insufficiency (p<0.0001), a higher fat mass (p<0.0001), and lower glucose area under the curve (AUC) (p=0.027). The F508del/L206W subgroup had significantly higher insulin secretion (AUC; p=0.027) and body mass index (p<0.001). Pulmonary function (FEV1) was significantly higher for the F508del/L206W subgroup (p<0.0001). Over a median of 7.37 years, the risk of developing CFRD in 141 patients was similar between groups. PwCF with heterozygous F508del/L206W and F508del/A455E tended to have pancreatic exocrine sufficiency, better nutritional status, improved pulmonary function and better diabetogenic indices, but this does not translate into lower risk of CF-related Diabetes.
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- 2024
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31. A glycosylated hemoglobin A1c above 6% (42 mmol/mol) is associated with a high risk of developing Cystic Fibrosis-Related Diabetes and a lower probability of weight gain in both adults and children with Cystic Fibrosis.
- Author
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Potter KJ, Racine F, Bonhoure A, Boudreau V, Bélanger N, Coriati A, Shohoudi A, Lavoie A, Senior PA, Mailhot G, and Rabasa-Lhoret R
- Subjects
- Humans, Adult, Child, Glycated Hemoglobin, Blood Glucose, Cross-Sectional Studies, Weight Gain, Cystic Fibrosis complications, Cystic Fibrosis epidemiology, Cystic Fibrosis diagnosis, Diabetes Mellitus epidemiology, Diabetes Mellitus diagnosis, Glucose Intolerance complications
- Abstract
Objectives: The classical glycosylated hemoglobin A1c threshold of 6.5% is an insensitive screening test for cystic fibrosis-related diabetes (CFRD). We sought to identify CF-specific A1C thresholds associated with 1) risk of progression to CFRD and 2) changes in body mass index (BMI) and forced expiratory volume (FEV1)., Methods: We studied the cross sectional and longitudinal associations between A1c, BMI, and FEV1 in 2 cohorts of 223 children (followed for up to 8 years) and 289 adults (followed for a mean of 7.5 ± 4.3 years) with CF but without diabetes at baseline and undergoing regular assessments including Oral Glucose Tolerance Test (OGTT)., Results: For the onset of OGTT-defined CFRD optimal A1c threshold was 5.9% in adults (sensitivity: 67% and specificity: 71%) and 5.7% for children (sensitivity: 60% and specificity: 47%). Kaplan-Meier analysis of progression to CFRD according to baseline A1C showed increased the risk of developing CFRD for A1c ≥ 6.0% in adults (P = 0.002) and ≥ 5.5% in children (p = 0.012). Temporal changes in BMI and FEV1 according to baseline A1C in adults were assessed with a linear mixed-effect model, BMI significantly increased over time in subjects with a baseline A1c < 6%, but those with a A1C ≥ 6.0% gained significantly less weight over time (P = 0.05). There was no difference in FEV1 according to baseline A1c category., Conclusion: An A1C above 6% may be associated with a high risk of developing CFRD and a lower probability of weight gain in both adults and children with CF., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)
- Published
- 2023
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32. New-onset Obesity After Lung Transplantation: Incidence, Risk Factors, and Clinical Outcomes.
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Jomphe V, Bélanger N, Beauchamp-Parent C, Poirier C, Nasir BS, Ferraro P, Lands LC, and Mailhot G
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- Humans, Incidence, Retrospective Studies, Obesity complications, Obesity epidemiology, Body Mass Index, Risk Factors, Metabolic Syndrome complications, Lung Transplantation adverse effects, Diabetes Mellitus diagnosis, Diabetes Mellitus epidemiology, Diabetes Mellitus etiology
- Abstract
Background: Lung transplant (LTx) recipients who gain weight after transplantation may experience an upward shift in body mass index (BMI) that places them in the obese category. The incidence, risk factors, and impact on metabolic health and mortality of new-onset obesity have not been documented in the LTx setting., Methods: This single-center retrospective study included 564 LTx recipients. Individuals were stratified according to their BMI trajectories from pretransplant evaluation up to 10 y posttransplant. New-onset obesity was defined as a pretransplant BMI <30 kg/m 2 and posttransplant BMI >30 kg/m 2 . The incidence, risk factors, and posttransplant diabetes mellitus, metabolic syndrome, and mortality of recipients with new-onset obesity were compared with those of nonobese (BMI <30 kg/m 2 , pre/post-LTx), consistently obese (BMI >30 kg/m 2 , pre/post-LTx), and obese recipients with weight loss (BMI >30 kg/m 2 pre-LTx, BMI <30 kg/m 2 post-LTx)., Results: We found that 14% of recipients developed obesity after transplantation. Overweight individuals (odds ratio [OR]: 9.01; 95% confidence interval [CI] [4.86-16.69]; P < 0.001) and candidates with chronic obstructive pulmonary disease (OR: 6.93; 95% CI [2.30-20.85]; P = 0.001) and other diagnoses (OR: 4.28; 95% CI [1.22-14.98]; P = 0.023) were at greater risk. Multivariable regression analysis showed that new-onset obesity was associated with a greater risk of metabolic syndrome (hazard ratio: 1.70; 95% CI [1.17-2.46]; P = 0.005), but not of posttransplant diabetes mellitus, than nonobesity. Recipients with new-onset obesity had a survival comparable to that of consistently obese individuals., Conclusions: A greater understanding of the multifaceted nature of post-LTx obesity may lead to interventions that are better tailored to the characteristics of these individuals., Competing Interests: G.M. was a Junior 2 scholar from Fonds de recherche du Québec-Santé when this study was carried out. The other authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2022
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33. Forest soil biotic communities show few responses to wood ash applications at multiple sites across Canada.
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Smenderovac E, Emilson C, Porter T, Morris D, Hazlett P, Diochon A, Basiliko N, Bélanger N, Markham J, Rutherford PM, van Rees K, Jones T, and Venier L
- Subjects
- Biota, Forestry, Forests, Soil chemistry, Soil Pollutants analysis
- Abstract
There is interest in utilizing wood ash as an amendment in forestry operations as a mechanism to return nutrients to soils that are removed during harvesting, with the added benefit of diverting this bioenergy waste material from landfill sites. Existing studies have not arrived at a consensus on what the effects of wood ash amendments are on soil biota. We collected forest soil samples from studies in managed forests across Canada that were amended with wood ash to evaluate the effects on arthropod, bacterial and fungal communities using metabarcoding of F230, 16S, 18S and ITS2 sequences as well as enzyme analyses to assess its effects on soil biotic function. Ash amendment did not result in consistent effects across sites, and those effects that were detected were small. Overall, this study suggests that ash amendment applied to managed forest systems in amounts (up to 20 Mg ha
-1 ) applied across the 8 study sties had little to no detectable effects on soil biotic community structure or function. When effects were detected, they were small, and site-specific. These non-results support the application of wood ash to harvested forest sites to replace macronutrients (e.g., calcium) removed by logging operations, thereby diverting it from landfill sites, and potentially increasing stand productivity., (© 2022. The Author(s).)- Published
- 2022
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34. Loss of Mitochondrial Function Impairs Lysosomes.
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Demers-Lamarche J, Guillebaud G, Tlili M, Todkar K, Bélanger N, Grondin M, Nguyen AP, Michel J, and Germain M
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- Animals, Apoptosis Inducing Factor genetics, Apoptosis Inducing Factor metabolism, Cell Line, Electron Transport Chain Complex Proteins genetics, Electron Transport Chain Complex Proteins metabolism, GTP Phosphohydrolases genetics, GTP Phosphohydrolases metabolism, Lysosomes genetics, Lysosomes pathology, Mice, Mice, Knockout, Mitochondria genetics, Mitochondria pathology, Neurodegenerative Diseases genetics, Neurodegenerative Diseases metabolism, Neurodegenerative Diseases pathology, Protein Kinases genetics, Protein Kinases metabolism, Reactive Oxygen Species metabolism, Lysosomes metabolism, Mitochondria metabolism
- Abstract
Alterations in mitochondrial function, as observed in neurodegenerative diseases, lead to disrupted energy metabolism and production of damaging reactive oxygen species. Here, we demonstrate that mitochondrial dysfunction also disrupts the structure and function of lysosomes, the main degradation and recycling organelle. Specifically, inhibition of mitochondrial function, following deletion of the mitochondrial protein AIF, OPA1, or PINK1, as well as chemical inhibition of the electron transport chain, impaired lysosomal activity and caused the appearance of large lysosomal vacuoles. Importantly, our results show that lysosomal impairment is dependent on reactive oxygen species. Given that alterations in both mitochondrial function and lysosomal activity are key features of neurodegenerative diseases, this work provides important insights into the etiology of neurodegenerative diseases., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2016
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35. Characterization and genus identification of rhizobial symbionts from Caragana arborescens in western Canada.
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Moukoumi J, Hynes RK, Dumonceaux TJ, Town J, and Bélanger N
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- Carbon analysis, DNA, Bacterial genetics, DNA, Ribosomal genetics, Genes, Bacterial, Genes, rRNA, Mesorhizobium isolation & purification, Mesorhizobium metabolism, Nitrogen analysis, Nitrogen Fixation, Phylogeny, Plant Leaves chemistry, RNA, Ribosomal, 16S genetics, Saskatchewan, Caragana microbiology, Mesorhizobium classification, Mesorhizobium physiology, Root Nodules, Plant microbiology, Symbiosis
- Abstract
Naturally occurring nitrogen-fixing symbionts from root nodules of caragana (Caragana arborescens) growing in central Saskatchewan were isolated following surface sterilization of caragana root nodules and squashing and spreading of the contents on yeast extract - mannitol medium. The symbiotic nature of the strains was confirmed following inoculation onto surface-sterilized C. arborescens seed in a gnotobiotic Leonard jar system. The Rhizobium isolates from C. arborescens root nodules were intermediate in generation time (g) (mean g of 5 isolates was 6.41 h) compared with the fast growers, Rhizobium leguminosarum NRG457 (g: 4.44 h), Rhizobium tropici 899 (g: 3.19 h), and Sinorhizobium meliloti BALSAC (g: 3.45 h), but they were faster than the slow-growing Bradyrhizobium japonicum USDA 110 (g: 13.86 h) and similar to Mesorhizobium amorphae (g: 7.76 h). Nitrogen derived from fixation by measuring changes in δ(15)N natural abundance in plant tissue confirmed the effectiveness of the strains; approximately 80% N2 from fixation. Strain identification was carried out by determining the sequences of 3 genes: 16S rRNA-encoding genes, cpn60, and recA. This analysis determined that the symbiotic partner of Canadian C. arborescens belongs to the genus Mesorhizobium and seems more related to M. loti than to previously described caragana symbionts like M. caraganae. This is the first report of Mesorhizobium sp. nodulating C. arborescens in western Canada.
- Published
- 2013
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36. The influence of predicted arm biomechanics on decision making.
- Author
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Cos I, Bélanger N, and Cisek P
- Subjects
- Adult, Electromyography, Evoked Potentials, Motor physiology, Female, Humans, Male, Models, Biological, Muscle, Skeletal physiology, Predictive Value of Tests, Torque, Arm physiology, Biomechanical Phenomena physiology, Decision Making, Movement physiology
- Abstract
There is considerable debate on the extent to which biomechanical properties of movements are taken into account before and during voluntary movements. For example, while several models have described reach planning as primarily kinematic, some studies have suggested that implicit knowledge about biomechanics may also exert some influence on the planning of reaching movements. Here, we investigated whether decisions about reaching movements are influenced by biomechanical factors and whether these factors are taken into account before movement onset. To this end, we designed an experimental paradigm in which humans made free choices between two potential reaching movements where the options varied in path distance as well as biomechanical factors related to movement energy and stability. Our results suggest that the biomechanical properties of potential actions strongly influence the selection between them. In particular, in our task, subjects preferred movements whose final trajectory was better aligned with the major axis of the arm's mobility ellipse, even when the launching properties were very similar. This reveals that the nervous system can predict biomechanical properties of potential actions before movement onset and that these predictions, in addition to purely abstract criteria, may influence the decision-making process.
- Published
- 2011
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- View/download PDF
37. Estradiol modulation of cortical, striatal and raphe nucleus 5-HT1A and 5-HT2A receptors of female hemiparkinsonian monkeys after long-term ovariectomy.
- Author
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Sánchez MG, Estrada-Camarena E, Bélanger N, Morissette M, and Di Paolo T
- Subjects
- Animals, Autoradiography, Cerebral Cortex metabolism, Corpus Striatum metabolism, Female, Macaca fascicularis, Ovariectomy, Raphe Nuclei metabolism, Cerebral Cortex drug effects, Corpus Striatum drug effects, Estradiol pharmacology, Estrogens pharmacology, Parkinson Disease, Secondary metabolism, Raphe Nuclei drug effects, Receptor, Serotonin, 5-HT1A metabolism, Receptor, Serotonin, 5-HT2A metabolism
- Abstract
Depression is common in Parkinson's disease and an imbalance in serotonin neurotransmission could be implicated. Estradiol is reported to modulate brain serotonin systems of rodents and monkeys, but this has not been explored in primate models of Parkinson's disease. Thus, the present study investigated the effect of estradiol on 5-HT(1A) and 5-HT(2A) serotonin receptors in the cortex, striatum and raphe nucleus of long-term ovariectomized hemiparkinsonian monkeys. Seven monkeys were ovariectomized and received a month later a unilateral lesion with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Four years after lesion and ovariectomy, three received a month of treatment with 17β-estradiol and four the vehicle. Autoradiography of [(3)H]8-OH-DPAT specific binding to 5-HT(1A) receptors showed a decrease in the frontal cortex of monkeys treated with 17β-estradiol in both hemispheres of the brain. [(3)H]ketanserin specific binding to 5-HT(2A) receptors was increased in the frontal cortex and the striatum of monkeys treated with 17β-estradiol in both the lesioned and intact sides of the brain. Autoradiography of [(35)S]GTPγS specific binding stimulated with R-(+)-8-OH-DPAT showed a decrease in the percentage of stimulation in the frontal cortex of monkeys treated with 17β-estradiol in both hemispheres of the brain and in the dorsal raphe nucleus. Treatment with 17β-estradiol was initiated a long time after ovariectomy in monkeys to model post menopausal hormonal conditions and showed that serotonin receptors were still responsive in the brain regions investigated. These results support a role for 17β-estradiol on serotonin activity in Parkinson's disease and could be useful for treatment of depression associated with this disease., (Copyright © 2010 Elsevier Ltd. All rights reserved.)
- Published
- 2011
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38. Striatal Akt/GSK3 signaling pathway in the development of L-Dopa-induced dyskinesias in MPTP monkeys.
- Author
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Morissette M, Samadi P, Hadj Tahar A, Bélanger N, and Di Paolo T
- Subjects
- Animals, Antiparkinson Agents adverse effects, Benzoxazoles therapeutic use, Cabergoline, Corpus Striatum metabolism, Disease Models, Animal, Drug Interactions, Dyskinesia, Drug-Induced etiology, Enzyme Inhibitors pharmacology, Ergolines therapeutic use, Female, Levodopa adverse effects, Macaca fascicularis, Parkinsonian Disorders drug therapy, Phosphorylation drug effects, Piperidines therapeutic use, Serine metabolism, Signal Transduction drug effects, Statistics as Topic, Corpus Striatum drug effects, Dyskinesia, Drug-Induced pathology, Glycogen Synthase Kinase 3 metabolism, Oncogene Protein v-akt metabolism, Signal Transduction physiology
- Abstract
L-Dopa treatment, the gold standard therapy for Parkinson's disease, is hampered by motor complications such as dyskinesias. Recently, impairment of striatal Akt/GSK3 signaling was proposed to play a role in the mechanisms implicated in development of L-Dopa-induced dyskinesias in a rodent model of Parkinson's disease. The present experiment investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) monkeys, the effects on Akt/GSK3 of chronic L-Dopa treatment inducing dyskinesias compared to L-Dopa with CI-1041 (NMDA receptor antagonist) or a low dose of cabergoline (dopamine D2 receptor agonist) preventing dyskinesias. The extensive dopamine denervation induced by MPTP was associated with a decrease by about half of phosphorylated Akt(Ser473) levels in posterior caudate nucleus, anterior and posterior putamen; smaller changes were observed for phosphorylated Akt(Thr308) levels that did not reach statistical significance. Dopamine depletion reduced phosphorylated GSK3beta(Ser9) levels, mainly in posterior putamen whereas pGSK3beta(Tyr216) and pGSK3alpha(Ser21) were unchanged. In posterior caudate nucleus, anterior and posterior putamen of dyskinetic L-Dopa-treated MPTP monkeys, pAkt(Ser473) and pGSK3beta(Ser9) were elevated whereas L-Dopa+cabergoline treated MPTP monkeys without dyskinesias had lower values in posterior striatum as vehicle-treated MPTP monkeys. In non-dyskinetic MPTP monkeys treated with L-Dopa+CI-1041, putamen pAkt(Ser473) and pGSK3beta(Ser9) levels remained elevated as in dyskinetic monkeys while in posterior caudate nucleus, these levels were low as vehicle-treated and lower than L-Dopa treated MPTP monkeys. Extent of phosphorylation of Akt and GSK3beta in putamen correlated positively with dyskinesias scores of MPTP monkeys; these correlations were higher with dopaminergic drugs (L-Dopa, cabergoline) suggesting implication of additional mechanisms and/or signaling molecules in the NMDA antagonist antidyskinetic effect. In conclusion, our results showed that in MPTP monkeys, loss of striatal dopamine decreased Akt/GSK3 signaling and that increased phosphorylation of Akt and GSK3beta was associated with L-Dopa-induced dyskinesias., (Copyright 2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
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39. Use of prosodic cues in the production of idiomatic and literal sentences by individuals with right- and left-hemisphere damage.
- Author
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Bélanger N, Baum SR, and Titone D
- Subjects
- Analysis of Variance, Cues, Female, Humans, Male, Reading, Speech Production Measurement, Time, Brain Diseases physiopathology, Cerebral Cortex physiopathology, Functional Laterality, Semantics, Speech
- Abstract
The neural bases of prosody during the production of literal and idiomatic interpretations of literally plausible idioms was investigated. Left- and right-hemisphere-damaged participants and normal controls produced literal and idiomatic versions of idioms (He hit the books.) All groups modulated duration to distinguish the interpretations. LHD patients, however, showed typical speech timing difficulties. RHD patients did not differ from the normal controls. The results partially support a differential lateralization of prosodic cues in the two cerebral hemispheres [Van Lancker, D., & Sidtis, J. J. (1992). The identification of affective-prosodic stimuli by left- and right-hemisphere-damaged subjects: All errors are not created equal. Journal of Speech and Hearing Research, 35, 963-970]. Furthermore, extended final word lengthening appears to mark idiomaticity.
- Published
- 2009
- Full Text
- View/download PDF
40. Basal ganglia group II metabotropic glutamate receptors specific binding in non-human primate model of L-Dopa-induced dyskinesias.
- Author
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Samadi P, Grégoire L, Morissette M, Calon F, Hadj Tahar A, Bélanger N, Dridi M, Bédard PJ, and Di Paolo T
- Subjects
- Amino Acids pharmacology, Animals, Autoradiography, Behavior, Animal drug effects, Cabergoline, Caudate Nucleus drug effects, Caudate Nucleus metabolism, Data Interpretation, Statistical, Ergolines pharmacology, Excitatory Amino Acid Antagonists pharmacology, Female, Macaca fascicularis, Ovariectomy, Putamen drug effects, Putamen metabolism, Receptors, Metabotropic Glutamate drug effects, Xanthenes pharmacology, Antiparkinson Agents adverse effects, Antiparkinson Agents metabolism, Basal Ganglia metabolism, Dyskinesia, Drug-Induced metabolism, Levodopa adverse effects, Levodopa metabolism, Receptors, Metabotropic Glutamate metabolism
- Abstract
L-Dopa-induced dyskinesias (LIDs), the disabling abnormal involuntary movements induced by chronic use of L-Dopa, limit the quality of life in Parkinson's disease (PD) patients. Modulation of group II metabotropic glutamate receptors (mGluR2/3) in the basal ganglia, a brain region critically involved in motor control, is considered as an alternative approach in therapy of PD. In this study, receptor binding autoradiography of [3H]LY341495, a mGluR2/3 selective radioligand, was used to investigate possible changes in mGluR2/3 in the basal ganglia of L-Dopa-treated 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) monkeys having developed LIDs compared to animals in which LIDs were prevented by adjunct treatments with CI-1041, a selective antagonist of the NR1A/2B subtype of NMDA receptor, or low doses of the dopamine D2 receptor agonist, cabergoline. Our study is the first to provide evidence of: (1) the similar localization of [3H]LY341495 specific binding to mGluR2/3 in the primate basal ganglia as compared to receptor distribution measured by immunohistochemistry in human and rat as well as this ligand binding in intact rat brain; (2) no change of [3H]LY341495 specific binding in basal ganglia after nigrostriatal denervation by MPTP; and (3) a widespread reduction of [(3)H]LY341495 specific binding to mGluR2/3 in the caudate nucleus (-17% to -31%), putamen (-12% to -45%) and globus pallidus (-56 to -59%) of non-dyskinetic animals treated with L-Dopa+cabergoline as compared to controls, MPTP monkeys treated with saline, L-Dopa alone (dyskinetic) or L-Dopa+CI-1041 (non-dyskinetic). This study is the first to propose a close interaction between mGluR2/3 and dopamine D2 receptors activation in the basal ganglia.
- Published
- 2008
- Full Text
- View/download PDF
41. Random variability in congenital hypothyroidism from thyroid dysgenesis over 16 years in Québec.
- Author
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Deladoëy J, Bélanger N, and Van Vliet G
- Subjects
- Adolescent, Choristoma epidemiology, Databases, Factual, Environment, Female, Humans, Infant, Newborn, Male, Neonatal Screening, Quebec epidemiology, Seasons, Thyrotropin blood, Congenital Hypothyroidism epidemiology, Thyroid Dysgenesis epidemiology
- Abstract
Context: Research on the etiology of congenital hypothyroidism from thyroid dysgenesis (CHTD) (comprising mostly ectopy and agenesis) over the past decade has focused on genetic mechanisms. However, the possibility that environmental factors might be involved has been raised by studies showing a seasonal variability of the incidence of CHTD., Objectives: The objective of this study was to assess the variability in incidence of CHTD in the province of Québec, Canada., Design, Setting, Patients, and Main Outcome Measure: The Québec provincial newborn screening database was analyzed from January 1990 to December 2005. Only cases of permanent congenital hypothyroidism with thyroid ectopy or agenesis on scintigraphy were analyzed., Results: During the study period, 1,303,341 children were screened, and 424 cases of permanent congenital hypothyroidism were diagnosed, giving an overall incidence of 1:3074. Of these, 306 had CHTD (overall incidence 1:4259) from either ectopy (n = 231) or agenesis (n = 75). Over the 16 yr of the study, this incidence remained stable (P = 0.57), and no significant variability in monthly incidence was found (P = 0.87)., Conclusions: The incidence of CHTD did not vary over the observation period, and its monthly variation was random. Therefore, environmental factors do not appear to play a significant role in the etiology of CHTD.
- Published
- 2007
- Full Text
- View/download PDF
42. DHEA improves symptomatic treatment of moderately and severely impaired MPTP monkeys.
- Author
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Bélanger N, Grégoire L, Bédard PJ, and Di Paolo T
- Subjects
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine, Animals, Antiparkinson Agents administration & dosage, Antiparkinson Agents blood, Antiparkinson Agents pharmacokinetics, Dehydroepiandrosterone administration & dosage, Dehydroepiandrosterone blood, Dehydroepiandrosterone pharmacokinetics, Dyskinesia, Drug-Induced psychology, Female, Levodopa administration & dosage, Levodopa pharmacokinetics, Levodopa pharmacology, Macaca fascicularis, Motor Activity, Parkinsonian Disorders chemically induced, Parkinsonian Disorders physiopathology, Parkinsonian Disorders psychology, Severity of Illness Index, Antiparkinson Agents pharmacology, Dehydroepiandrosterone pharmacology, Dyskinesia, Drug-Induced drug therapy, Parkinsonian Disorders drug therapy
- Abstract
The steroid dehydroepiandrosterone (DHEA) is abundant in men and women and decreases rapidly during aging. Parkinson's disease (PD) is the second most common neurodegenerative disorder just behind Alzheimer. l-3,4-Dihydroxyphenylalanine (l-Dopa) therapy remains the most effective treatment but many patients develop motor complications. This study investigated the acute effect of DHEA alone and with l-Dopa in 12 females monkeys lesioned with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to model PD. DHEA administration alone improved the mean parkinsonian score at 1, 5 and 15mg/kg in moderately and severely impaired MPTP monkeys and increased blood DHEA concentrations. DHEA with a low dose of l-Dopa increased the l-Dopa effect in moderately and severely impaired MPTP monkeys. DHEA lengthened duration of the effect of the low dose of l-Dopa by 15-45min. DHEA at 1, 5 and 15mg/kg combined with a high dose of l-Dopa did not increase dyskinesias. DHEA could act by reducing inhibitory GABAergic activity in the striatal output pathways. DHEA could also be metabolized into estradiol in the brain and increase acutely dopamine activity.
- Published
- 2006
- Full Text
- View/download PDF
43. Trapping light in a ring resonator using a grating-assisted coupler with asymmetric transmission.
- Author
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Kulishov M, Laniel J, Bélanger N, and Plant D
- Abstract
A recently proposed concept suggests that a matched periodic modulation of both the refractive index and the gain/loss of the media breaks the coupling symmetry of the two co-propagating modes and allows only a unidirectional coupling from the i-th mode to j-the mode but not the opposite. This concept has been used to design a ring resonator coupled through a complex grating composed of both real (index) and imaginary (loss/gain) parts according to Euler relation: n = n0 exp(-jkx) = n0 (cos(kx) - j sin(kx)). Such asymmetrical coupling allows light to be coupled into the ring without letting it out. We present a detailed theoretical analysis of the ring resonator in the linear regime, and we investigate its linear temporal dynamics. Three possible states of the complex grating leads to the possibility of developing a dynamic optical memory cell where, for example, a data modulated train of optical pulses can be stored. This data can be accessed without destroying it, and can also be erased thus permitting the storage of a new bit. Finally, the ring can be used for pulse retiming.
- Published
- 2005
- Full Text
- View/download PDF
44. Nonreciprocal waveguide Bragg gratings.
- Author
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Kulishov M, Laniel J, Bélanger N, Azaña J, and Plant D
- Abstract
The use of a complex short-period (Bragg) grating which combines matched periodic modulations of refractive index and loss/gain allows asymmetrical mode coupling within a contra-directional waveguide coupler. Such a complex Bragg grating exhibits a different behavior (e.g. in terms of the reflection and transmission spectra) when probed from opposite ends. More specifically, the grating has a single reflection peak when used from one end, but it is transparent (zero reflection) when used from the opposite end. In this paper, we conduct a systematic analytical and numerical analysis of this new class of Bragg gratings. The spectral performance of these, so-called nonreciprocal gratings, is first investigated in detail and the influence of device parameters on the transmission spectra of these devices is also analyzed. Our studies reveal that in addition to the nonreciprocal behavior, a nonreciprocal Bragg grating exhibits a strong amplification at the resonance wavelength (even with zero net-gain level in the waveguide) while simultaneously providing higher wavelength selectivity than the equivalent index Bragg grating. However, it is also shown that in order to achieve non-reciprocity in the device, a very careful adjustment of the parameters corresponding to the index and gain/loss gratings is required.
- Published
- 2005
- Full Text
- View/download PDF
45. Relevance of the MPTP primate model in the study of dyskinesia priming mechanisms.
- Author
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Blanchet PJ, Calon F, Morissette M, Hadj Tahar A, Bélanger N, Samadi P, Grondin R, Grégoire L, Meltzer L, Di Paolo T, and Bédard PJ
- Subjects
- Animals, Dyskinesias prevention & control, Haplorhini, Humans, Parkinsonian Disorders prevention & control, Disease Models, Animal, Dyskinesias metabolism, Parkinsonian Disorders metabolism
- Abstract
For nearly 20 years, the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) primate model has allowed great strides to be made in our understanding of the maladaptive changes underlying the levodopa-related motor response complications occurring in most parkinsonian patients. Studies indicate that sustained dopamine D2 receptor occupancy can prevent and reverse existing dyskinesias. Recent experiments in levodopa-treated MPTP animals, co-administered either a threshold dose of cabergoline or a glutamate NMDA NR2B-selective antagonist (CI-1041), have afforded protection against dyskinesia, perhaps through presynaptic inhibition of glutamate release and blockade of supersensitive postsynaptic NMDA receptors in the striatum, respectively. Some of the biochemical events that have correlated with dyskinesias, namely upregulated GABA(A) receptors in the internal pallidum, rise in pre-proenkephalin-A gene expression in the striatum, and upregulated striatal glutamate ionotropic receptors and adenosine A(2a) receptors, may be counteracted by these preventive strategies.
- Published
- 2004
- Full Text
- View/download PDF
46. Effect of a selective glutamate antagonist on L-dopa-induced dyskinesias in drug-naive parkinsonian monkeys.
- Author
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Hadj Tahar A, Grégoire L, Darré A, Bélanger N, Meltzer L, and Bédard PJ
- Subjects
- Animals, Benzoxazoles therapeutic use, Corpus Striatum drug effects, Corpus Striatum metabolism, Corpus Striatum physiopathology, Disease Models, Animal, Drug Interactions, Dyskinesia, Drug-Induced metabolism, Dyskinesia, Drug-Induced physiopathology, Excitatory Amino Acid Antagonists therapeutic use, Female, Levodopa adverse effects, Macaca fascicularis, Parkinson Disease drug therapy, Piperidines therapeutic use, Receptors, N-Methyl-D-Aspartate metabolism, Treatment Outcome, Benzoxazoles pharmacology, Dyskinesia, Drug-Induced drug therapy, Excitatory Amino Acid Antagonists pharmacology, Glutamic Acid metabolism, Levodopa antagonists & inhibitors, Piperidines pharmacology, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors
- Abstract
Alterations of striatal glutamate receptors are believed to be responsible, at least in part, for the pathogenesis of L-dopa-induced dyskinesias (LID). To evaluate whether co-administration of CI-1041, a novel NMDA receptor antagonist selective for the NR1A/NR2B subtype, with L-dopa might prevent the appearance of this side effect, eight de novo parkinsonian monkeys were treated chronically orally with either L-dopa alone or L-dopa plus CI-1041 (n= 4 for each group). After 4 weeks of treatment with L-dopa alone, all four animals developed moderate dyskinesias either choreic or dystonic in nature. CI-1041 co-treatment completely prevented the induction of dyskinesias in three animals and only one monkey developed mild dyskinesias at the end of the fourth week of treatment in the L-dopa + CI-1041 group. The magnitude and duration of the antiparkinsonian action of L-dopa was similar in both groups. These results suggest that selective NMDA receptor antagonism may be interesting for managing LID in Parkinson's disease patients.
- Published
- 2004
- Full Text
- View/download PDF
47. Chronic treatment with small doses of cabergoline prevents dopa-induced dyskinesias in parkinsonian monkeys.
- Author
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Bélanger N, Grégoire L, Hadj Tahar A, and Bédard PJ
- Subjects
- Animals, Behavior, Animal drug effects, Cabergoline, Disease Models, Animal, Dopamine Agonists administration & dosage, Drug Administration Schedule, Ergolines administration & dosage, Female, Locomotion drug effects, Macaca fascicularis, Posture, 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine adverse effects, Antiparkinson Agents adverse effects, Dopamine Agonists therapeutic use, Dyskinesia, Drug-Induced etiology, Dyskinesia, Drug-Induced prevention & control, Ergolines therapeutic use, Parkinson Disease drug therapy
- Abstract
Levodopa continues to be the most effective agent for the symptomatic treatment of Parkinson's disease (PD). But over time, initial benefits decline in efficacy because of a rise in adverse effects such as dyskinesias. The pathophysiology of levodopa-induced dyskinesias (LID) is not completely understood, but it appears to result from deficient regulation by dopamine of corticostriatal glutamatergic inputs leading to a cascade of neurochemical changes in the striatum and the output pathways. In the present study, we examined if the addition of small doses of cabergoline (a long-acting D(2) receptor agonist) to levodopa could prevent LID. The major hypothesis is that sustained activation of postsynaptic D(2) receptors on medium spiny neurons even by small doses of cabergoline could prevent or reduce LID. The minor hypothesis, and the more controversial of the two, is that the long-acting stimulation by small doses of cabergoline could diminish the release of glutamate by the corticostriatal pathway and prevent LID. Eight MPTP-treated monkeys with a long-standing and stable parkinsonian syndrome and having never received dopaminergic agents were used. Two groups of four were treated for 1 month with levodopa/benserazide administered orally (100 mg/25 mg). The second group received in addition a threshold dose of cabergoline (dose ranging from 0.015 to 0.035 mg/kg, SC). During the treatment, we observed LID in the levodopa group but not in the group receiving levodopa+cabergoline. Furthermore, the combination produced a comparable antiparkinsonian effect in terms of quality but prolonged the duration (by 1 to 2 hours) and increased the locomotion (mean for 2 weeks congruent with 104%). Our data suggest that a small dose of a long-acting D(2) agonist combined with high doses of levodopa could be preventive of LID in patients with PD and could be an alternative to using antiglutamatergic agents for this purpose., (Copyright 2003 Movement Disorder Society)
- Published
- 2003
- Full Text
- View/download PDF
48. Estradiol and dehydroepiandrosterone potentiate levodopa-induced locomotor activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine monkeys.
- Author
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Bélanger N, Grégoire L, Bédard P, and Di Paolo T
- Subjects
- Animals, Dose-Response Relationship, Drug, Drug Synergism, Female, Functional Laterality physiology, Macaca fascicularis, Ovariectomy, Parkinson Disease, Secondary chemically induced, 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine, Dehydroepiandrosterone pharmacology, Dopamine Agents pharmacology, Estradiol pharmacology, Levodopa pharmacology, Motor Activity drug effects, Parkinson Disease, Secondary psychology
- Abstract
Six monkeys were rendered hemiparkinsonian with a unilateral injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. These monkeys displayed ipsilateral circling under basal conditions, and after dopaminergic stimulation with levodopa they decreased their ipsilateral circling and started turning to the contralateral side of their lesion. The effect of 17beta-estradiol and dehydroepiandrosterone (DHEA) was investigated in these animals. 17beta-Estradiol (0.1 mg/kg) added to a threshold dose of levodopa significantly potentiated contralateral circling (mean/30 min) compared to saline or threshold levodopa treatment whereas the duration of circling remained unchanged. DHEA (1-15 mg/kg) alone induced contralateral circling, compared to saline treatment, for 90 min. In addition, DHEA (1-15 mg/kg) potentiated the contralateral circling (mean/30 min) induced by a threshold dose of levodopa and did not change the duration of levodopa circling. A maximal response was observed with 1 or 5 mg/kg of DHEA combined with levodopa depending on the monkey. No correlation was found between the dose for the maximal DHEA response and baseline circling or threshold dose of levodopa. These results suggest that 17beta-estradiol or DHEA is able to potentiate locomotor activity of hemiparkinsonian monkeys. The DHEA doses investigated are similar to those presently used in humans. DHEA may be an alternative to 17beta-estradiol to modulate dopaminergic activity.
- Published
- 2003
- Full Text
- View/download PDF
49. [The patient-centered interview and the way it is taught. What do family physicians who have recently received their degree think?].
- Author
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Côté L, Bélanger N, and Blais J
- Subjects
- Data Collection, Humans, Family Practice education, Internship and Residency, Interviews as Topic, Patient-Centered Care, Physician-Patient Relations
- Abstract
Objective: To describe how family physicians perceive the patient-centred interview (PCI) and the way in which it is taught during residency training., Design: Mailed survey., Setting: Family physicians from a variety of practice settings in Quebec., Participants: Ninety-one family physicians who graduated from Laval University between 1996 and 1998., Method: Survey was conducted in 1999 using the modified Dillman method. The original questionnaire had mainly open-ended questions on perception of the PCI and learning activities associated with it during residency training. All qualitative data were subject to content analysis using triangulation strategies., Main Findings: A PCI mainly involves exploring patients' experience of their illnesses; this helps physicians to better understand patients. Patients are more content with this type of interview and are, therefore, more likely to follow physicians' recommendations. Respondents reported the main drawback to be longer interview times; this was particularly true for emergency and walk-in care. The most useful learning activities during residency were reported to be supervision by direct observation and observation of supervisor-patient consultations., Conclusion: Patient-centred interviews enabled physicians to understand and help their patients better. Results of this study can help teachers who are developing and consolidating activities to teach residents how to conduct PCIs and how to integrate them into practice.
- Published
- 2002
50. [Rally-resources. The integration of community principles].
- Author
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Légaré F, Bélanger N, and Doyon H
- Subjects
- Attitude of Health Personnel, Hospitals, University, Humans, Learning, Program Development, Program Evaluation, Quebec, Teaching methods, Community Health Services classification, Community Health Services organization & administration, Community-Institutional Relations, Family Practice education, Health Resources classification, Health Resources organization & administration, Internship and Residency
- Abstract
Problem Being Addressed: Family medicine training programs are required to teach the four principles of family medicine, two of which deal with community responsibilities. Teachers in the Family Practice Unit at the Centre hospitalier de Québec, pavillon St-François d'Assise (UMF-SFA) have developed a learning activity that introduces residents to community agencies in the area., Objective of Program: To introduce family medicine residents to community aspects of the principles of family medicine, to help them identify community resources in the area served by UMF-SFA, to discuss these services so that they can use them effectively, and to offer new residents an opportunity to become better acquainted with these services and with the UMF-SFA team., Main Components of Program: In early September, a half-day is set aside for a rally during which mixed teams of supervisors and residents (four to eight to a team) visit about 10 community agencies in the vicinity of UMF-SFA. Walking from place to place, the teams spend 15 to 20 minutes with staff or users of each agency. The informal tone of the rally makes it easier for residents to understand these agencies., Conclusion: Each year for the past 10 years, all UMF-SFA members have taken part in a rally that introduces residents to the community-based resources of family medicine.
- Published
- 2000
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