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Tapan K Basu - One of the best experts on this subject based on the ideXlab platform.

  • dietary rhubarb rheum rhaponticum Stalk Fibre does not lower plasma cholesterol levels in diabetic rats
    British Journal of Nutrition, 2003
    Co-Authors: Sukhinder K Cheema, Vinti Goel, Tapan K Basu, Luis B Agellon
    Abstract:

    Rhubarb (Rheum rhapontiam) Stalk Fibre was previously shown to be hypolipidaemic under clinical and experimental conditions. The present study was undertaken to investigate whether rhubarb Stalk Fibre has a hypolipidaemic effect under diabetic conditions. Two models of diabetic rats were used: streptozotocin-induced diabetic rats, and diabetes-prone BB (BBdp) rats. The plasma cholesterol and triacylglycerol concentrations were elevated after the onset of diabetes in BBdp rats, but not in sterptozotocin-induced diabetic rats. The rhubarb-Fibre diet had no effect on the plasma cholesterol or triacylglycerol concentrations of diabetic rats. The hypolipidaemic effect of rhubarb Stalk Fibre has been suggested to be due to the bile-acid-binding capacity of rhubarb Fibre, which in turn up regulates cholesterol 7alpha-hydroxylase (cyp7a) activity. cyp7a is the first and the rate-limiting enzyme in the breakdown of cholesterol to bile acids. We measured the cyp7a activity and mRNA levels in control and diabetic rats fed rhubarb- and cellulose-Fibre diets. The cyp7a activity and mRNA abundance were increased in both diabetic rat models, indicating that bile acid synthesis is enhanced in diabetes. Feeding a diet enriched with rhubarb Fibre caused a slight but significant increase (P<0.05) in cyp7a enzyme activity in BBdp rats, but no change in cyp7a mRNA abundance was detected. These results suggest that although a rhubarb-Fibre-enriched diet increased cyp7a activity in BBdp rats, there was no apparent therapeutic benefit in terms of lowering plasma cholesterol concentrations.

  • dietary rhubarb rheum rhaponticum Stalk Fibre stimulates cholesterol 7α hydroxylase gene expression and bile acid excretion in cholesterol fed c57bl 6j mice
    British Journal of Nutrition, 1999
    Co-Authors: Vinti Goel, Buncha Ooraikul, Sukhinder K Cheema, Luis B Agellon, Tapan K Basu
    Abstract:

    Both experimental and clinical studies have indicated that a novel source of dietary Fibre, produced from rhubarb (Rheum rhaponticum) Stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this Fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb Fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb Fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb Fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-Fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb Fibre.

Luis B Agellon - One of the best experts on this subject based on the ideXlab platform.

  • dietary rhubarb rheum rhaponticum Stalk Fibre does not lower plasma cholesterol levels in diabetic rats
    British Journal of Nutrition, 2003
    Co-Authors: Sukhinder K Cheema, Vinti Goel, Tapan K Basu, Luis B Agellon
    Abstract:

    Rhubarb (Rheum rhapontiam) Stalk Fibre was previously shown to be hypolipidaemic under clinical and experimental conditions. The present study was undertaken to investigate whether rhubarb Stalk Fibre has a hypolipidaemic effect under diabetic conditions. Two models of diabetic rats were used: streptozotocin-induced diabetic rats, and diabetes-prone BB (BBdp) rats. The plasma cholesterol and triacylglycerol concentrations were elevated after the onset of diabetes in BBdp rats, but not in sterptozotocin-induced diabetic rats. The rhubarb-Fibre diet had no effect on the plasma cholesterol or triacylglycerol concentrations of diabetic rats. The hypolipidaemic effect of rhubarb Stalk Fibre has been suggested to be due to the bile-acid-binding capacity of rhubarb Fibre, which in turn up regulates cholesterol 7alpha-hydroxylase (cyp7a) activity. cyp7a is the first and the rate-limiting enzyme in the breakdown of cholesterol to bile acids. We measured the cyp7a activity and mRNA levels in control and diabetic rats fed rhubarb- and cellulose-Fibre diets. The cyp7a activity and mRNA abundance were increased in both diabetic rat models, indicating that bile acid synthesis is enhanced in diabetes. Feeding a diet enriched with rhubarb Fibre caused a slight but significant increase (P<0.05) in cyp7a enzyme activity in BBdp rats, but no change in cyp7a mRNA abundance was detected. These results suggest that although a rhubarb-Fibre-enriched diet increased cyp7a activity in BBdp rats, there was no apparent therapeutic benefit in terms of lowering plasma cholesterol concentrations.

  • dietary rhubarb rheum rhaponticum Stalk Fibre stimulates cholesterol 7α hydroxylase gene expression and bile acid excretion in cholesterol fed c57bl 6j mice
    British Journal of Nutrition, 1999
    Co-Authors: Vinti Goel, Buncha Ooraikul, Sukhinder K Cheema, Luis B Agellon, Tapan K Basu
    Abstract:

    Both experimental and clinical studies have indicated that a novel source of dietary Fibre, produced from rhubarb (Rheum rhaponticum) Stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this Fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb Fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb Fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb Fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-Fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb Fibre.

Vinti Goel - One of the best experts on this subject based on the ideXlab platform.

  • dietary rhubarb rheum rhaponticum Stalk Fibre does not lower plasma cholesterol levels in diabetic rats
    British Journal of Nutrition, 2003
    Co-Authors: Sukhinder K Cheema, Vinti Goel, Tapan K Basu, Luis B Agellon
    Abstract:

    Rhubarb (Rheum rhapontiam) Stalk Fibre was previously shown to be hypolipidaemic under clinical and experimental conditions. The present study was undertaken to investigate whether rhubarb Stalk Fibre has a hypolipidaemic effect under diabetic conditions. Two models of diabetic rats were used: streptozotocin-induced diabetic rats, and diabetes-prone BB (BBdp) rats. The plasma cholesterol and triacylglycerol concentrations were elevated after the onset of diabetes in BBdp rats, but not in sterptozotocin-induced diabetic rats. The rhubarb-Fibre diet had no effect on the plasma cholesterol or triacylglycerol concentrations of diabetic rats. The hypolipidaemic effect of rhubarb Stalk Fibre has been suggested to be due to the bile-acid-binding capacity of rhubarb Fibre, which in turn up regulates cholesterol 7alpha-hydroxylase (cyp7a) activity. cyp7a is the first and the rate-limiting enzyme in the breakdown of cholesterol to bile acids. We measured the cyp7a activity and mRNA levels in control and diabetic rats fed rhubarb- and cellulose-Fibre diets. The cyp7a activity and mRNA abundance were increased in both diabetic rat models, indicating that bile acid synthesis is enhanced in diabetes. Feeding a diet enriched with rhubarb Fibre caused a slight but significant increase (P<0.05) in cyp7a enzyme activity in BBdp rats, but no change in cyp7a mRNA abundance was detected. These results suggest that although a rhubarb-Fibre-enriched diet increased cyp7a activity in BBdp rats, there was no apparent therapeutic benefit in terms of lowering plasma cholesterol concentrations.

  • dietary rhubarb rheum rhaponticum Stalk Fibre stimulates cholesterol 7α hydroxylase gene expression and bile acid excretion in cholesterol fed c57bl 6j mice
    British Journal of Nutrition, 1999
    Co-Authors: Vinti Goel, Buncha Ooraikul, Sukhinder K Cheema, Luis B Agellon, Tapan K Basu
    Abstract:

    Both experimental and clinical studies have indicated that a novel source of dietary Fibre, produced from rhubarb (Rheum rhaponticum) Stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this Fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb Fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb Fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb Fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-Fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb Fibre.

Sukhinder K Cheema - One of the best experts on this subject based on the ideXlab platform.

  • dietary rhubarb rheum rhaponticum Stalk Fibre does not lower plasma cholesterol levels in diabetic rats
    British Journal of Nutrition, 2003
    Co-Authors: Sukhinder K Cheema, Vinti Goel, Tapan K Basu, Luis B Agellon
    Abstract:

    Rhubarb (Rheum rhapontiam) Stalk Fibre was previously shown to be hypolipidaemic under clinical and experimental conditions. The present study was undertaken to investigate whether rhubarb Stalk Fibre has a hypolipidaemic effect under diabetic conditions. Two models of diabetic rats were used: streptozotocin-induced diabetic rats, and diabetes-prone BB (BBdp) rats. The plasma cholesterol and triacylglycerol concentrations were elevated after the onset of diabetes in BBdp rats, but not in sterptozotocin-induced diabetic rats. The rhubarb-Fibre diet had no effect on the plasma cholesterol or triacylglycerol concentrations of diabetic rats. The hypolipidaemic effect of rhubarb Stalk Fibre has been suggested to be due to the bile-acid-binding capacity of rhubarb Fibre, which in turn up regulates cholesterol 7alpha-hydroxylase (cyp7a) activity. cyp7a is the first and the rate-limiting enzyme in the breakdown of cholesterol to bile acids. We measured the cyp7a activity and mRNA levels in control and diabetic rats fed rhubarb- and cellulose-Fibre diets. The cyp7a activity and mRNA abundance were increased in both diabetic rat models, indicating that bile acid synthesis is enhanced in diabetes. Feeding a diet enriched with rhubarb Fibre caused a slight but significant increase (P<0.05) in cyp7a enzyme activity in BBdp rats, but no change in cyp7a mRNA abundance was detected. These results suggest that although a rhubarb-Fibre-enriched diet increased cyp7a activity in BBdp rats, there was no apparent therapeutic benefit in terms of lowering plasma cholesterol concentrations.

  • dietary rhubarb rheum rhaponticum Stalk Fibre stimulates cholesterol 7α hydroxylase gene expression and bile acid excretion in cholesterol fed c57bl 6j mice
    British Journal of Nutrition, 1999
    Co-Authors: Vinti Goel, Buncha Ooraikul, Sukhinder K Cheema, Luis B Agellon, Tapan K Basu
    Abstract:

    Both experimental and clinical studies have indicated that a novel source of dietary Fibre, produced from rhubarb (Rheum rhaponticum) Stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this Fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb Fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb Fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb Fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-Fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb Fibre.

N G Inmanbamber - One of the best experts on this subject based on the ideXlab platform.

  • modelling genetic and environmental control of biomass partitioning at plant and phytomer level of sugarcane grown in controlled environments
    Crop & Pasture Science, 2011
    Co-Authors: A Singels, N G Inmanbamber
    Abstract:

    Sucrose content has reached ceiling levels in several countries despite aggressive crossing and selection programmes aimed at improving this important trait for the sugarcane industry. Much of the recent research effort has been directed towards molecular means for improving sucrose content and while some breakthroughs have been made in the laboratory, no plants modified for this purpose have been grown successfully in the field. Sugarcane grown mainly for its sucrose in the past is now being considered for its Fibre content as well because of increased interest in renewable energy. The paper offers an account of the variation in Fibre, sucrose and hexoses in aboveground organs in relation to genotype, temperature and water regime with the aim of an improved understanding of biomass partitioning needed to effectively exploit sugarcane's potential for multiple production streams. Previous studies often focused on single genotypes and on partitioning within Stalks and ignored the effects of whole-plant structural partitioning on sugar accumulation. A mathematical model was constructed of biomass partitioning (at whole-plant and phytomer levels) of two high and two low sucrose clones of sugarcane from data collected in two controlled environment experiments, with water and temperature as treatments. The model tested the hypothesis that genetic differences in sucrose accumulation and responses to water and temperature can be explained by differences in plant development and partitioning to structural components such as leaf and Stalk Fibre. Whole-plant biomass partitioning between leaf, Stalk structure and stored sugars was adequately simulated using clone-specific partitioning fractions modified by water status and temperature. Leaf partitioning fractions varied significantly between clones (low sucrose clones had high leaf fractions) but not between treatments. Stalk Fibre partitioning fractions did not vary between clones but increased with improved water status and increased temperature. These aspects were mostly represented successfully in the model mainly because partitioning parameters were derived from the same data. Sugar accumulation was simulated, reasonably successfully, as the remainder of the biomass pool after partitioning to structural pools. Phyllochron intervals determined the rate at which phytomers ceased structural growth and commenced sugar accumulation. Low sucrose clones had longer intervals and so started sucrose accumulation later than high sucrose clones. There were also clonal differences in the ratio of hexose to sucrose (low sucrose clones had high ratios) and this could largely be explained by the structural mass fraction present in biomass. Although the data did not allow independent tests of all model assumptions, modelling these experiments did assist in gaining improved understanding of the underlying mechanisms of genetic and environmental control of biomass partitioning at whole-plant and phytomer levels. Results suggest that a way to enhance sucrose yields could be to breed genotypes with appropriate phenological and structural partitioning traits such as rapid phytomer development and low leaf partitioning fractions. This needs to be confirmed by further studies on more genotypes and environments.

  • phytomer level source sink model of biomass production and partitioning in sugarcane
    Proceedings of the 82nd Annual Congress of the South African Sugar Technologists' Association Durban South Africa 26-28 August 2009., 2009
    Co-Authors: A Singels, N G Inmanbamber
    Abstract:

    A framework for above-ground biomass partitioning between competing sinks is proposed where partitioning depends on temperature, water status, the physiological age of the leaf and associated internode (phytomer), and on the structural demands imposed by the phenological development of leaves and tillers. This hypothesis was tested by comparing simulations from a model with observations from two glasshouse experiments. In these experiments, net photosynthesis, expansive growth, biomass production (at a plant level) and partitioning (at plant and internode levels) were measured for four genetically diverse sugarcane clones grown in two water and two temperature regimes. Although whole plant assimilation was simulated accurately for most treatments, the model did not provide for the observed clonal differences in response to low temperature. Whole plant partitioning response to water stress and temperature was simulated well when simulated assimilation was forced to measured values. Internode profiles of Stalk Fibre and sugar storage were adequately mimicked with functions that accounted for growth and development at internode level. A useful platform has been created for testing theories of genetic and environmental control of assimilate production and partitioning at whole plant and phytomer level.

  • sugarcane water stress criteria for irrigation and drying off
    Field Crops Research, 2004
    Co-Authors: N G Inmanbamber
    Abstract:

    In Australia about 60% of sugar produced from sugarcane depends to some extent on irrigation. Regional water supplies are often limited and the pressure on irrigators to defend or improve their farming practices can be quite severe. Compared to other crops, little is known about how far water can be stretched in sugarcane without affecting sugar yield. In particular, there is little information on the response of important yield forming processes to soil water deficits. Two experiments were designed to follow the effect of increasing soil water deficit (SWD) on processes such as leaf appearance, leaf and Stalk extension, leaf area development, biomass and sucrose accumulation and dry matter partitioning. The first experiment was designed to coincide with a period of high evaporative demand and the second experiment with a period of low evaporative demand. As SWD increased in the first experiment reductions occurred first in leaf and Stalk extension rate, then in green leaves per Stalk, then in biomass accumulation and finally in sucrose accumulation. The data indicated that irrigation can be used more sparingly since biomass accumulation (hence net photosynthesis) can tolerate greater deficits than previously recognized. Water stress resulted in marked changes in dry matter partitioning. In the second experiment sucrose yield was increased at one point to more than 3 t/ha over the yield of the control treatment. Dry matter was diverted from tops (green leaves and immature stem) and from Stalk Fibre to make up the additional sucrose yield. Simple crop measurements (leaf or Stalk extension, green leaf number) are suggested as indicators of when to irrigate to avoid reductions in biomass accumulation or when to harvest in order to benefit most from changes in dry matter partitioning due to water stress. Suggestions are also made for improving process level growth models of sugarcane.