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Selected AbstractsAssociation between fatigue and failure to preserve cerebral energy turnover during prolonged exerciseACTA PHYSIOLOGICA, Issue 1 2003L. Nybo Abstract Aim: This study evaluated if the fatigue and apathy arising during exercise with hypoglycaemia could relate to a lowering of the cerebral metabolic rates of glucose and oxygen. Methods and results: Six males completed 3 h of cycling with or without glucose supplementation in random order. Cerebral blood flow, metabolism and interleukin-6 (IL-6) release were evaluated with the Kety,Schmidt technique. Blood glucose was maintained during the glucose trial, while it decreased from 5.2 ± 0.1 to 2.9 ± 0.3 mmol L,1 (mean ± SE) after 180 min of exercise in the placebo trial with a concomitant increase in perceived exertion (P < 0.05). During hypoglycaemia, the cerebral glucose uptake was reduced from 0.34 ± 0.05 to 0.28 ± 0.04 ,mol g,1 min,1, while the cerebral uptake of , -hydroxybutyrate increased to 5 ± 1 pmol g,1 min,1 (P < 0.05). The reduced glucose uptake was accompanied by a lowering of the cerebral metabolic rate of oxygen from 1.84 ± 0.19 mmol g,1 min,1 during exercise with glucose supplementation to 1.60 ± 0.16 mmol g,1 min,1 during hypoglycaemia (P < 0.05). In addition, the cerebral IL-6 release was reduced from 0.4 ± 0.1 to 0.0 ± 0.1 pg g,1 min,1 (P < 0.05). Conclusions: Exercise-induced hypoglycaemia limits the cerebral uptake of glucose, exacerbates exercise, reduces the cerebral metabolic rate of oxygen and attenuates the release of IL-6 from the brain. [source] Antioxidants in aerial parts of Hypericum sampsonii, Hypericum japonicum and Hypericum perforatumINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 11 2009Chung Li Chen Summary Antioxidants contents and antioxidative enzymes and their activities in fresh aerial tissues of Hypericum sampsonii (Sampson's St John's Wort), Hypericum japonicum (Japanese St John's Wort) and Hypericum perforatum were investigated. Hypericum sampsonii contained more total ascorbate [34.33 ,mol g,1 fresh weight (FW)] than H. perforatum (57% less) and H. japonicum (82% less). It also contained more thiol and phenolics than two other species. Hypericum japonicum had highest superoxide dismutase (SOD) activity (8.74 mmol min,1 g,1 FW), followed by H. sampsonii (2% less) and H. perforatum (37% less). Hot-air dried H. perforatum materials contained more thiol [208.7 ,mol g,1 dry weight (DW)] and phenolics (352.82 mg g,1 DW) than freeze-dried and fresh materials. Both drying treatments decreased the activities of antioxidative enzymes in aerial tissues of H. perforatum. However, freeze-dried H. perforatum contained the highest SOD activity (5.42 mmol min,1 g,1 DW) among the antioxidative enzymes measured from both freeze-dried and hot-air dried tissues (ranged from 0.02 to 2.65 ,mol min,1 g,1 DW). [source] Biochemical changes in cut vs. intact lamb's lettuce (Valerianella olitoria) leaves during storageINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Antonio Ferrante Summary Consumers are oriented towards fresh-cut vegetables that provide phytonutrients useful for preventing stress-related diseases. The aim of this work was to evaluate the cut operations on the quality changes of lamb's lettuce (Valerianella olitoria L.) cv. Trofy during storage at 4 °C for 8 days. Results showed that chlorophyll and carotenoids reduction was observed after 8 days of storage. In both treatments, total carotenoids after 8 days decreased from 20 to 16 mg g,1 FW. Free and total phenols increased with storage in both treatments. Total phenols were 23% higher in control (32 ,mol g,1 FW) compared to cut leaves (25 ,mol g,1 FW) after 8 days of storage. Anthocyanins increased after 8 days and reached 30 mg 100 g,1 FW without significant difference between treatments. Ascorbic acid (AsA) and dehydroascorbic (DHA) acid increased in cut leaves compared to control. After 1 day AsA concentration was 3 300 nmol g,1 FW in cut leaves, while in control leaves was 1 500 nmol g,1 FW. Analogously AsA + DHA was higher in cut leaves, 4 100 nmol g,1 FW, while in control leaves the mean was 3 000 nmol g,1 FW. After 5 days of storage the values of AsA returned to initial values, while AsA + DHA were lower. [source] Relative importance of amino acids, glycine,betaine and ectoine synthesis in the biocontrol agent Pantoea agglomerans CPA-2 in response to osmotic, acidic and heat stressLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2007T.P. Cańamás Abstract Aims:, The objective of this work was to determine the role of different compatible solutes in adaptation of Pantoea agglomerans CPA-2 at different stages of growth to solute (0·98, 0·97, 0·96 aw), heat (35 and 40°C) and acidic (pH 4·0, 5·0, 6·0) stress. Methods and Results:, Solute stress was imposed by using NaCl, glucose or glycerol, and pH was imposed with malic and citric acids. The accumulation of glycine,betaine, ectoine and amino acids in bacterial cells was quantified using high performance liquid chromathography (HPLC). There was a significant (P < 0·05) accumulation of glycine,betaine (NaCl modified, 100,150 ,mol g,1 dry weight of cells) and ectoine (glucose modified media, >340 ,mol g,1 dry weight of cells) in the cells over a 48 h incubation period when compared with controls (<10 ,mol g,1 dry weight of cells). Chromatographic profile of amino acids was different with respect to control when NaCl or glucose was used as osmolyte. Conclusions:,Pantoea agglomerans CPA-2 cells synthesised significant amounts of glycine,betaine and ectoine in response to imposed solute stress. However, these compounds and tested amino acids were not involved in cellular adaptation to either heat or pH stress. Significance and Impact of the Study:, This type of information can be effectively applied to improve ecophysiological quality of cells of bacterial biocontrol agents for better survival and biocontrol efficacy in the phyllosphere of plants. [source] Energy Transfer from Chemically Attached Rhodamine 101 to Adsorbed Methylene Blue on Microcrystalline Cellulose Particles,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2007Hernán B. Rodríguez Rhodamine 101 (R101) was chemically attached onto microcrystalline cellulose and methylene blue (MB) was adsorbed to a sample bearing nearby 6 × 10,7 mol R101 (g cellulose),1. The system was studied by reflectance and emission spectroscopy in the solid state. R101 shows no aggregation in these conditions and, while pure MB builds up dimers on cellulose even at 2 × 10,8 mol g,1, in the presence of R101 no evidence on selfaggregation or heteroaggregation is found up to around 10,6 mol g,1. No exciplex formation is found as well. The overall fluorescence quantum yield measured on thick layers, once re-absorption effects are accounted for, amounts to 0.80 ± 0.07 for pure R101 and decreases steadily on increasing the concentration of MB. Results demonstrate the occurrence of radiative and nonradiative singlet energy transfer from R101 to MB. For thick layers of particles, the combined effect of both kinds of energy transfer amounts to nearly 80% at the highest acceptor concentration, while nonradiative transfer reaches 60% both for thin and optically thick layers. The dependence of nonradiative energy transfer efficiencies on the acceptor concentration is analyzed and the origin of departures from Förster behavior at low acceptor concentration is discussed. [source] The decline of metallophyte vegetation in floodplain grasslands: Implications for conservation and restorationAPPLIED VEGETATION SCIENCE, Issue 1 2009Esther C.H.E.T. Lucassen Abstract Question: Which biogeochemical processes are responsible for the decline of endemic metallophyte vegetation in floodplain grasslands? Location: Floodplain grasslands along the River Geul (the Netherlands) and metalliferous mine spoils near the River Geul (Belgium). Methods: In order to find factors and soil processes that have caused a decline of metallophytes and an increase of pseudo-metallophytes in floodplain grasslands, a soil study was done at locations currently and formerly dominated by metallophytes. In addition, changes in soil chemistry in recent decades in floodplain grasslands were investigated. Finally, a 2-year plant growth experiment was performed in the field, to test the effects of improving soil conditions by topsoil removal. Results: Metallophytes only occur on acidic floodplain soils (pH-H2O 5.0-5.5) with relatively high Zn availability (total Zn >40 ,mol g,1; Zn/Ca>0.8; Zn-H2O>59 ,mol kg,1) combined with low phosphate availability (Olsen-P,1250 ,mol kg,1). The Olsen-P and total Ca concentrations were relatively high in topsoil (0-20 cm), while total Zn was high throughout the soil profile (0-50 cm). Removal of topsoil led to recovery of P and Zn availability. Under the new soil conditions there was almost no growth and expansion of pseudo-metalliferous grasses in time, wheras metallophytes easily established, maintained and reproduced with significant increases in cover over time. Conclusions: On a global scale, metallophyte vegetation types are increasingly under threat of extinction. Our study shows that factors leading to higher soil alkalinity inhibit Zn availability at the expense of the metallophyte vegetation. Factors leading to a higher Olsen-P concentration stimulate the growth of more competitive pseudo-metallophyte grasses. Both eutrophication and alkalinisation have contributed to the decline of metallophyte vegetation in floodplains of the River Geul. Removal of the alkaline- and phosphate-enriched soil top layer restores the original soil chemistry and enables re-colonisation by the metallophyte vegetation. The results can be applied in conservation and restoration strategies for such sites. [source] Dietary histidine affects lens protein turnover and synthesis of N-acetylhistidine in Atlantic salmon (Salmo salar L.) undergoing parr,smolt transformationAQUACULTURE NUTRITION, Issue 5 2005O. BRECK Abstract This study was conducted to investigate protein synthesis rates and metabolism of histidine (His)-derivatives in lenses of Atlantic salmon (Salmo salar L.) of different dietary His background during parr,smolt transformation. Two populations of Atlantic salmon parr of equal origin were established in freshwater (FW), 3 months prior to transfer to seawater (SW). The populations were fed either a control diet (CD) containing 8.9 g kg,1 His or the same diet added crystalline His to a total level of 14.2 g kg,1 (HD). On the basis of these two populations, 14C His force-feeding studies were performed; in FW 3 weeks prior to sea transfer and in SW 6 weeks after transfer. The studies were conducted by force-feeding the respective diets enriched with 14C labelled His, with subsequent measurements of incorporation of 14C His into lens free amino acid pool, as well as into lens proteins and other free His pool fractions. The latter included the major lens imidazole N-acetylhistidine (NAH). Lens concentrations of His and NAH were clearly influenced by dietary His history, both in parr and smolt. The lens His and NAH concentrations in the CD population were considerably lower in SW than in FW, while in the HD group the His level was equal and the NAH level 50% higher in SW than in FW. Fractional synthesis rate for NAH, KS (NAH), in FW was 8.2 and 4.2 ,mol g,1 day,1 for fish in the CD and HD populations, respectively. The corresponding KS (NAH) values in SW were 5.1 and 33.0 ,mol g,1 day,1. Our data show that free His is rapidly converted to NAH in the lens, and that NAH seems to have a very high turnover, especially in salmon reared in SW. Fractional synthesis rate for lens proteins, KS (PROTEIN), ranged between 1.8 and 17.3% day,1 (182 and 2791 ,g g,1 day,1, respectively), and was generally higher in SW than in FW (P < 0.01). In SW, KS (PROTEIN) was highest in fish in the HD population (P < 0.05), whereas lens protein retention in the HD group was significantly lower than the CD group (P = 0.01). In a second model assuming that His from lens NAH is available for protein synthesis, calculated values of KS (PROTEIN) ranged between 0.17% day,1 (17.6 ,g g,1 day,1) and 0.48% day,1 (70.2 ,g g,1 day,1). Cataract scores recorded in the His populations at a later point (day 204), showed that the CD fish had significantly higher mean cataract scores than individuals in the HD population (P < 0.01), confirming that low levels of lens His and NAH are associated with cataract development. [source] Electrical stunning of farmed Atlantic cod Gadus morhua L.: a comparison of an industrial and experimental methodAQUACULTURE RESEARCH, Issue 8 2010Hanne Digre Abstract An industrial and experimental electrical method for stunning farmed Atlantic cod in air and seawater (SW), respectively, were compared. The impacts of sedation with AQUI-SÔ and exercise to exhaustion before electrical stunning were also assessed to monitor the possible depletion of rested muscle energy levels by electrical stunning. Stress (blood glucose, haematocrit, muscle pH, muscle excitability, high-energy phosphates and rigor mortis) and flesh quality (fillet texture, colour, liquid leakage (LL), gaping, residual blood and K -value) were assessed. For the industrial stunning method, an average of 41 V, 0.2 A dc was applied to individual cod for 18,27 s. For the SW method, a bipolar square wave current (170 Hz, 33% duty cycle) was applied for 5 s. After stunning, recovery was prevented by exsanguination in chilled SW. There were no differences (P>0.05) between the two stunning methods except for a higher ultimate fillet pH for cod stunned in air 8 days postmortem. Exercise before stunning depleted muscle energy levels at slaughter, increased LL and fillets had redder and darker flesh after storage on ice for 8 days. Electrical stunning (in air) of AQUI-SÔ -treated fish partly depleted muscle energy levels (pH 7.3, ATP 18.7 ,mol g,1, PCr 70.1 ,mol g,1). However, flesh quality was not affected. Unless pre-rigor filleting is the chosen processing strategy, electrical stunning of cod seems to be a promising stunning method. [source] Effect of genipin on the biliary excretion of cholephilic compounds in ratsHEPATOLOGY RESEARCH, Issue 6 2008Masaki Mikami Aim:, Genipin, a metabolite of geniposide, is reported to stimulate the insertion of multidrug resistance protein 2 (Mrp2) in the bile canalicular membrane, and to cause choleresis by increasing the biliary excretion of glutathione, which has been considered to be a substrate of Mrp2. In the present study, the effect of colchicine on the choleretic effect of genipin was investigated. The effect of genipin on the biliary excretion of the substrates of bile salt export pump and Mrp2 was also studied. Methods:, After bile duct cannulation into rats, genipin was administered at the rate of 0.2 ,mol/min/100 g, and the effect of colchicine pretreatment (0.2 mg/100 g) was examined. Metabolites of genipin in the bile were examined by a thin layer chromatography. Taurocholate (TC), sulfobromophthalein (BSP), and pravastatin were infused at the rate of 1.0, 0.2 and 0.3 ,mol/min/100 g, respectively, and the effect of genipin co-administration was examined. Results:, Genipin increased bile flow and the biliary glutathione excretion, and those increases were not inhibited by colchicine. The biliary excretion of genipin glucuronide was less than 10% of the genipin excreted into bile. The biliary excretion of TC, BSP, and pravastatin was unchanged by genipin co-administration. Conclusion:, It was indicated that colchicine-sensitive vesicular transport has no role on the genipin-induced insertion of Mrp2 to the canalicular membrane. Choleresis of genipin is considered to be mainly due to the increased biliary glutathione excretion by genipin, not by the biliary excretion of glucuronide. TC had no effect on the biliary glutathione excretion. [source] | |||||||||||||