The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Hoda M. Eid - One of the best experts on this subject based on the ideXlab platform.
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model
European Journal of Nutrition, 2016Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Purpose Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [ Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. Methods C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Results Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Conclusions Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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a combination of catechin and epicatechin underlies the in vitro adipogenic action of labrador tea Rhododendron Groenlandicum an antidiabetic medicinal plant of the eastern james bay cree pharmacopeia
Journal of Ethnopharmacology, 2016Co-Authors: Meriem Ouchfoun, Hoda M. Eid, Ammar Saleem, Jose A Guerreroanalco, Brendan WalsherousselAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada. Objectives In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte. Materials and methods Isolation and identification of the crude extract’s active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry. Results Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (−)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (−)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant’s crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%). Conclusion Results demonstrate that the mixture of (+)-catechin and (−)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. Groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
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A combination of (+)-catechin and (-)-epicatechin underlies the in vitro adipogenic action of Labrador tea (Rhododendron Groenlandicum), an antidiabetic medicinal plant of the Eastern James Bay Cree pharmacopeia.
Journal of Ethnopharmacology, 2016Co-Authors: Hoda M. Eid, Michel Rapinski, Lina Musallam, Alain Cuerrier, Meriem Ouchfoun, Ammar Saleem, José A. Guerrero-analco, Brendan Walshe-roussel, Louis C. Martineau, John T. ArnasonAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada. Objectives In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte. Materials and methods Isolation and identification of the crude extract’s active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry. Results Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (−)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (−)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant’s crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%). Conclusion Results demonstrate that the mixture of (+)-catechin and (−)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. Groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model.
European Journal of Nutrition, 2015Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
Meriem Ouchfoun - One of the best experts on this subject based on the ideXlab platform.
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model
European Journal of Nutrition, 2016Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Purpose Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [ Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. Methods C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Results Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Conclusions Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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a combination of catechin and epicatechin underlies the in vitro adipogenic action of labrador tea Rhododendron Groenlandicum an antidiabetic medicinal plant of the eastern james bay cree pharmacopeia
Journal of Ethnopharmacology, 2016Co-Authors: Meriem Ouchfoun, Hoda M. Eid, Ammar Saleem, Jose A Guerreroanalco, Brendan WalsherousselAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada. Objectives In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte. Materials and methods Isolation and identification of the crude extract’s active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry. Results Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (−)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (−)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant’s crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%). Conclusion Results demonstrate that the mixture of (+)-catechin and (−)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. Groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
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A combination of (+)-catechin and (-)-epicatechin underlies the in vitro adipogenic action of Labrador tea (Rhododendron Groenlandicum), an antidiabetic medicinal plant of the Eastern James Bay Cree pharmacopeia.
Journal of Ethnopharmacology, 2016Co-Authors: Hoda M. Eid, Michel Rapinski, Lina Musallam, Alain Cuerrier, Meriem Ouchfoun, Ammar Saleem, José A. Guerrero-analco, Brendan Walshe-roussel, Louis C. Martineau, John T. ArnasonAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada. Objectives In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte. Materials and methods Isolation and identification of the crude extract’s active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry. Results Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (−)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (−)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant’s crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%). Conclusion Results demonstrate that the mixture of (+)-catechin and (−)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. Groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model.
European Journal of Nutrition, 2015Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
Brendan Walsheroussel - One of the best experts on this subject based on the ideXlab platform.
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a combination of catechin and epicatechin underlies the in vitro adipogenic action of labrador tea Rhododendron Groenlandicum an antidiabetic medicinal plant of the eastern james bay cree pharmacopeia
Journal of Ethnopharmacology, 2016Co-Authors: Meriem Ouchfoun, Hoda M. Eid, Ammar Saleem, Jose A Guerreroanalco, Brendan WalsherousselAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada. Objectives In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte. Materials and methods Isolation and identification of the crude extract’s active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry. Results Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (−)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (−)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant’s crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%). Conclusion Results demonstrate that the mixture of (+)-catechin and (−)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. Groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.
Nelson Thiffault - One of the best experts on this subject based on the ideXlab platform.
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Silviculture to sustain productivity in black spruce paludified forests
Forest Ecology and Management, 2016Co-Authors: Benoit Lafleur, Nelson Thiffault, Nicole J. Fenton, David Paré, Martin Simard, Sébastien M. Renard, Cécile Leroy, Sylvie Gauthier, Alain Leduc, Yves BergeronAbstract:Abstract Fire is considered the major disturbance in boreal forests. Nonetheless, in several areas logging has become the primary driver of forest dynamics. In many areas of the boreal forest, stands may undergo paludification (i.e. the accumulation of thick, poorly decomposed organic layers over the mineral soil) in the prolonged absence of fire, which reduces forest productivity. Whereas high-severity fires (HSF) may restore forest productivity by burning the soil organic layer (SOL), low-severity fires (LSF) mainly burn the soil surface and do not significantly reduce SOL thickness. In the Clay Belt region of eastern Canada, an area prone to paludification, forest stands have historically been harvested by clearcutting (CC), but concerns about the protection of soils and tree regeneration lead to the replacement of CC by careful logging (CL). Whereas CC disturbs the SOL and is thought to favor tree growth, CL has little impact on the SOL. Furthermore, it has been suggested that prescribed burning after clearcut (CCPB) could also be used to control paludification. Using a retrospective approach, this study sought to understand how CC, CL, and CCPB compare to LSF and HSF with respect to soil properties, SOL thickness, vegetation ground cover, tree nutrition, and stand height in paludified black spruce stands of the Clay Belt region. HSF led to significantly taller trees than CL and LSF, but did not differ from CC and CCPB. Foliar N was significantly higher in HSF and CCPB sites relative to CL and LSF, with an intermediate value in CC sites. Ground cover of Rhododendron Groenlandicum was significantly lower in HSF and CC sites relative to LSF, with intermediate values in CL and CCPB sites. Sphagnum spp. ground cover was significantly lower in HSF and CCPB sites relative to CL, with intermediate values in CC and LSF sites. High-severity fire sites had a significantly thinner SOL than the four other disturbances. Finally, regression tree analysis showed that SOL thickness represented the best predictor of tree height, whereas segmented regression showed that tree height was negatively correlated to SOL thickness and revealed a cut-off point circa 23 cm, which suggests that tree growth is impeded beyond this threshold. These results support the idea that management strategies intending to regenerate paludified forests should primarily aim at reducing organic layer thickness, either through mechanical disturbance or combustion.
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Ecological gradients driving the distribution of four Ericaceae in boreal Quebec, Canada.
Ecology and Evolution, 2015Co-Authors: Nelson Thiffault, Pierre Grondin, Jean Noël, Véronique PoirierAbstract:Understory species play a significant role in forest ecosystem dynamics. As such, species of the Ericaceae family have a major effect on the regeneration of tree species in boreal ecosystems. It is thus imperative to understand the ecological gradients controlling their distribution and abundance, so that their impacts can be taken into account in sustainable forest management. Using innovative analytical techniques from landscape ecology, we aimed to position, along ecological gradients, four Ericaceae found in the boreal forest of Quebec (Canada) (Rhododendron Groenlandicum, Kalmia angustifolia, Chamaedaphne calyculata, and Vaccinium spp), to regionalize these species into landscape units relevant to forest management, and to estimate the relative importance of several ecological drivers (climate, disturbances, stand attributes, and physical environment) that control the species distribution and abundance. We conducted our study in boreal Quebec, over a study area covering 535,355 km2. We used data from 15,339 ecological survey plots and forest maps to characterize 1422 ecological districts covering the study region. We evaluated the relative proportion of each ericaceous species and explanatory variables at the district level. Vegetation and explanatory variables matrices were used to conduct redundancy, cluster, and variation partitioning analyses. We observed that ericaceous species are mainly distributed in the western part of the study area and each species has a distinct latitudinal and longitudinal gradient distribution. On the basis of these gradients, we delimited 10 homogeneous landscape units distinct in terms of ericaceous species abundance and environmental drivers. The distribution of the ericaceous species along ecological gradients is closely related to the overlaps between the four sets of explanatory variables considered. We conclude that the studied Ericaceae occupy specific positions along ecological gradients and possess a specific abundance and distribution controlled by the integration of multiple explanatory variables.
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the biology of canadian weeds 146 Rhododendron Groenlandicum oeder kron and judd
Canadian Journal of Plant Science, 2011Co-Authors: Francois Hebert, Nelson ThiffaultAbstract:Hebert, F. and Thiffault, N. 2011. The Biology of Canadian Weeds. 146. Rhododendron Groenlandicum (Oeder) Kron and Judd. Can. J. Plant Sci. 91: 725-738. Rhododendron Groenlandicum (Oeder) Kron and Judd, bog Labrador tea, is an evergreen shrub from the Ericacae family native to North America. Bog Labrador tea is associated with the later stages of forest successions in black spruce forest stands of the boreal ecosystems with cool climates, but responds aggressively to forest openings where it is already present. In general, bog Labrador tea is associated with nutrient-poor, acidic soils, with drainage ranging from moist to wet. Layering is the main regeneration strategy of the species; evidence suggests that this could be especially true following disturbances that open the forest canopy. Sexual reproduction maintains viability in undisturbed communities through wind or water dispersal. Rhododendron Groenlandicum acclimates more rapidly relative to black spruce after perturbations through a higher rate of resource utilization when resources are available. The species is a highly competitive shrub for soil nutrients; it competes with regenerating conifers for soil nitrogen and phosphorus. It can also assimilate organic nitrogen from the soil through its mycorhizae. These characteristics may lead to the formation of ericaceous heaths that can stay unforested indefinitely. However, this species can be eradicated by herbicides (glyphosate) and heavy site scarification can limit its propagation.
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Does Trait Plasticity of Three Boreal Nutrient-Conserving Species Relate to their Competitive Ability?
Écoscience, 2011Co-Authors: Francois Hebert, Nelson Thiffault, Alison D. MunsonAbstract:Abstract: The present study investigates potential differences in trait plasticity as an additional contributing mechanism explaining ericaceous shrub dominance during different periods after logging. Two ericaceous species (Kalmia angustifolia, Rhododendron Groenlandicum), and black spruce plants (Picea mariana), were submitted to combinations of 3 light levels and 2 levels of nitrogen addition during a simulated growing season of 9 weeks under greenhouse conditions. Plant traits related to light (photosynthesis, leaf mass per unit of area, leaf and aboveground biomass allocation, foliar N concentration) and nutrient acquisition (root mass ratio, specific absorption ratio, absorption of 15N) were measured in response to the manipulation of these resources. The leaf mass per unit of area (LMA) of both ericaceous species was significantly reduced by shading; LMA of Rhododendron and Kalmia was, respectively, 54% and 31% higher in the highest light treatment. The LMA of black spruce was unchanged in response...
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Comparative physiological responses of Rhododendron Groenlandicum and regenerating Picea mariana following partial canopy removal in northeastern Quebec, Canada
Canadian Journal of Forest Research, 2010Co-Authors: Francois Hebert, Nelson Thiffault, Jean-claude Ruel, Alison D. MunsonAbstract:In boreal black spruce (Picea mariana (Mill.) BSP) dominated stands, careful logging around advance regenera- tion contributes to protect the shrub layer while increasing light availability. Therefore, it may promote expansion of bog Labrador tea (Rhododendron Groenlandicum (Oeder) Kron & Judd), which can impair black spruce growth by direct com- petition for nutrients and by alteration of soil biochemical conditions. Such harvesting approaches may not be suited for ir- regular, uneven-aged black spruce stands in the context of ecosystem-based management. Our objectives were to evaluate the effects of different intensities of partial harvest on critical resource availability and to compare the physiological and morphological responses of black spruce and Rhododendron to different intensities of partial harvest treatments. Two years after harvest, photosynthesis rate of black spruce was unchanged and was lower than that of Rhododendron, which was 63% higher after harvest. Nitrogen and water use efficiency were, respectively, 171% and 42% higher in Rhododendron than in black spruce after logging. Following harvest, black spruce physiology appeared to be regulated by the atmospheric humidity deficit, but for Rhododendron, physiology was regulated by light availability. The high plasticity of Rhododen- dron leaf traits could be indicative of the future advantage of this species in these stands following canopy removal associ- ated with harvest. Resume´ : Dans les peuplements boreaux domines par l'epinette noire (Picea mariana (Mill.) BSP), la coupe avec protec- tion de la regeneration preetablie contribue a proteger la strate arbustive tout en augmentant la disponibilitede la lumiere. Ainsi, cette coupe peut favoriser l'expansion du thedu Labrador (Rhododendron Groenlandicum (Oeder) Kron & Judd), ce qui peut reduire la croissance de l'epinette noire causee par la competition directe pour les nutriments et de l'alteration des conditions biochimiques du sol. Dans un contexte d'amenagement ecosystemique, de telles approches de recolte peu- vent ne pas convenir aux peuplements d'epinette noire irreguliers et inequiens. Nos objectifs consistaient aevaluer les ef- fets de differentes intensites de coupe partielle sur la disponibilitedes ressources critiques et acomparer les reactions physiologiques et morphologiques de l'epinette noire et du Rhododendron aux differentes intensites de coupe partielle. Deux ans apres coupe, le taux de photosynthese de l'epinette noire est demeureinchangeet etait plus faible que celui du Rhododendron qui etait 63 % plus eleveapres la coupe. Les valeurs d'efficacited'utilisation de l'azote et de l'eau du Rho- dodendron apres la coupe etaient, respectivement, 171 % et 42 % plus elevees que celles de l'epinette noire. Apresl a coupe, la physiologie de l'epinette noire semblait controlee par le deficit hydrique de l'atmosphere alors que la lumiere controlait celle du Rhododendron. La grande plasticitedes traits foliaires du Rhododendron pourrait etre un indice que cette espece serait avantagee dans le futur par l'elimination du couvert ala suite d'une coupe dans ces peuplements. (Traduit par la Redaction)
Pierre S. Haddad - One of the best experts on this subject based on the ideXlab platform.
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model
European Journal of Nutrition, 2016Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Purpose Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [ Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. Methods C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Results Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Conclusions Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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Rhododendron Groenlandicum (Labrador tea), an antidiabetic plant from the traditional pharmacopoeia of the Canadian Eastern James Bay Cree, improves renal integrity in the diet-induced obese mouse model
Pharmaceutical Biology, 2016Co-Authors: Antoine Brault, Mayra Luz Sanchez Villavicencio, Pierre S. HaddadAbstract:AbstractContent Our team has identified Labrador tea [Rhododendron Groenlandicum L. (Ericaceae)] as a potential antidiabetic plant from the traditional pharmacopoeia of the Eastern James Bay Cree. In a previous in vivo study, the plant extract was tested in a high-fat diet (HFD)-induced obese model using C57BL/6 mice and it improved glycaemia, insulinaemia and glucose tolerance.Objective In the present study, we assessed the plant’s potential renoprotective effects.Materials and methods Rhododendron Groenlandicum was administered at 250 mg/kg/d to mice fed HFD for 8 weeks to induce obesity and mild diabetes. Histological (periodic acid–Schiff (PAS), Masson and Oil Red O staining), immunohistochemical (IHC) and biochemical parameters were assessed to evaluate the renoprotective potential of R. Groenlandicum treatment for an additional 8 weeks.Results Microalbuminuria and renal fibrosis were developed in HFD-fed mice. Meanwhile, there was a tendency for R. Groenlandicum to improve microalbuminuria, with the...
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Labrador tea (Rhododendron Groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model.
European Journal of Nutrition, 2015Co-Authors: Meriem Ouchfoun, John T. Arnason, Antoine Brault, Lina Musallam, Hoda M. Eid, Diane Vallerand, Pierre S. HaddadAbstract:Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron Groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec. C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant’s molecular mechanisms. Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %). Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.
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Adipogenic Activity of Wild Populations of Rhododendron Groenlandicum, a Medicinal Shrub from the James Bay Cree Traditional Pharmacopeia
Evidence-Based Complementary and Alternative Medicine, 2015Co-Authors: Michel Rapinski, John T. Arnason, Pierre S. Haddad, Lina Musallam, Alain CuerrierAbstract:The traditional medicinal plant, Labrador tea (Rhododendron Groenlandicum (Oeder) Kron & Judd; Ericaceae), present in the pharmacopoeia of the Cree of Eeyou Istchee, has shown glitazone-like activity in the 3T3-L1 adipogenesis bioassay. This activity has been attributed to phenolic compounds, which have been shown to vary in this plant as a function of insolation parameters. The goal of this study was to determine if these changes in phenolic content were pharmacologically significant. Leaves were harvested in 2006 throughout the James Bay region of Northern Quebec and ethanol extracts were tested in vitro using the 3T3-L1 murine cell line adipogenesis bioassay. This traditional medicinal plant was found active in the assay. However, there was no detectable spatial pattern in the accumulation of intracellular triglycerides, suggesting that such patterns previously observed in the phenolic profile of Labrador tea were not pharmacologically significant. Nonetheless, a reduction in the adipogenic activity was observed and associated with higher concentrations of quercetin for which selected environmental variables did not appropriately explain its variation.
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The effect of Cree traditional medicinal teas on the activity of human cytochrome P450-mediated metabolism.
Journal of Ethnopharmacology, 2014Co-Authors: Teresa W. Tam, John T. Arnason, Pierre S. Haddad, Rui Liu, Ammar Saleem, Anthony Krantis, Brian C. FosterAbstract:Abstract Ethnopharmacological relevance Rhododendron Groenlandicum (Bog Labrador tea) , Rhododendron tomentosum (Marsh Labrador tea) and Juniperus communis (Juniper) are used in medicinal teas by Canadian aboriginal cultures alone and in combination with conventional drug products. The safety of this combination had not been previously examined and this study was initiated to examine the potential of medicinal teas to inhibit the major human drug metabolizing enzyme, cytochrome P450 3A4 (CYP3A4). Materials and methods The decoctions of Rhododendron Groenlandicum and Rhododendron tomentosum leaves a nd Juniperus communis berries were examined in a microtiter fluorometric assay to examine their potential to inhibit CYP-mediated metabolism. Results The decoctions showed progressive inhibition towards CYP3A4 the longer the leaves or berries were brewed. R. Rhododendron Groenlandicum and Juniperus communis may have the potential to inhibit CYP3A4-mediated metabolism. Conclusions The findings of this study with these traditional medicines are significant in that they provide mechanistic support that these products have the potential to affect the safety and efficacy of other health and medicinal products. As this study only examined CYP3A4, it is possible that these medicinals contain substances that could also affect other metabolic enzymes.