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Transport Capacity (transport + capacity)
Kinds of Transport Capacity Selected AbstractsModeling of the Intestinal Peptide Transporter hPepT1 and Analysis of Its Transport Capacities by Docking and Pharmacophore MappingCHEMMEDCHEM, Issue 12 2008Alessandro Pedretti Dr. Abstract An early pharmacokinetic screen for peptidomimetic drugs should have the ability to predict molecules with high affinity for intestinal transporters, as peptide-like derivatives are seldom absorbed passively. Hence, the first objective of this study was to generate a reliable model for the structure of the hPepT1 protein, which is the main intestinal transporter involved in the absorption of both dietary peptides and peptidomimetics. The modeling was based on the resolved structure of the homologous bacterial lactose permease LacY using a fragmental strategy. The interaction capacities of the hPepT1 model were explored by docking a set of 50 known ligands. Despite the known predilection of hPepT1 for hydrophobic ligands, docking results unveiled the key role of the polar interactions stabilized by charged termini, especially concerning the ammonium head group. The docking results were further verified by developing a pharmacophore model that confirmed the key features required for optimal hPepT1 affinity. The consistency of the docking results and the agreement with the pharmacophore model afford an encouraging validation for the proposed model and suggest that it can be exploited to design peptide-like molecules with an improved affinity for such a transporter. [source] Effect of external pH on the growth, photosynthesis and photosynthetic electron transport of Chlamydomonas acidophila Negoro, isolated from an extremely acidic lake (pH 2.6)PLANT CELL & ENVIRONMENT, Issue 10 2005ANTJE GERLOFF-ELIAS ABSTRACT In extremely acidic lakes, low primary production rates have been measured. We assumed that proton stress might explain these observations and therefore investigated the photosynthetic behaviour of a Chlamydomonas species, a main primary producer in acidic lakes, over a range of pH values. Identified as C. acidophila using small subunit rDNA analysis, this species is identical to other isolates from acidic environments in Europe and South America, suggesting a worldwide distribution. Laboratory experiments with C. acidophila, revealed a broad pH-tolerance for growth and photosynthesis, the lower pH limit lying at pH 1.5 and the upper limit at pH 7. Growth rates at optimum pH conditions (pH 3 and 5) were equal to those of the mesophilic Chlamydomonas reinhardtii. In contrast, photosynthetic rates were significantly higher, suggesting that higher photosynthetic rates compensated for higher dark respiration rates, as confirmed experimentally. Electron transport capacities of PSI and PSII, P700+ re-reduction times and measurements of PSII fluorescence revealed the induction of alternative electron transport mechanisms, such as chlororespiration, state transitions and cyclic electron transport, only at suboptimal pH values (pH 1.5; 4 and 6,7). The results indicate, that C. acidophila is well adapted to low pH and that the relatively low primary production rates are not a result of pH stress. [source] Animal performance and stress: responses and tolerance limits at different levels of biological organisationBIOLOGICAL REVIEWS, Issue 2 2009Karin S. Kassahn ABSTRACT Recent advances in molecular biology and the use of DNA microarrays for gene expression profiling are providing new insights into the animal stress response, particularly the effects of stress on gene regulation. However, interpretation of the complex transcriptional changes that occur during stress still poses many challenges because the relationship between changes at the transcriptional level and other levels of biological organisation is not well understood. To confront these challenges, a conceptual model linking physiological and transcriptional responses to stress would be helpful. Here, we provide the basis for one such model by synthesising data from organismal, endocrine, cellular, molecular, and genomic studies. We show using available examples from ectothermic vertebrates that reduced oxygen levels and oxidative stress are common to many stress conditions and that the responses to different types of stress, such as environmental, handling and confinement stress, often converge at the challenge of dealing with oxygen imbalance and oxidative stress. As a result, a common set of stress responses exists that is largely independent of the type of stressor applied. These common responses include the repair of DNA and protein damage, cell cycle arrest or apoptosis, changes in cellular metabolism that reflect the transition from a state of cellular growth to one of cellular repair, the release of stress hormones, changes in mitochondrial densities and properties, changes in oxygen transport capacities and changes in cardio-respiratory function. Changes at the transcriptional level recapitulate these common responses, with many stress-responsive genes functioning in cell cycle control, regulation of transcription, protein turnover, metabolism, and cellular repair. These common transcriptional responses to stress appear coordinated by only a limited number of stress-inducible and redox-sensitive transcription factors and signal transduction pathways, such as the immediate early genes c-fos and c-jun, the transcription factors NF,B and HIF - 1,, and the JNK and p38 kinase signalling pathways. As an example of environmental stress responses, we present temperature response curves at organismal, cellular and molecular levels. Acclimation and physiological adjustments that can shift the threshold temperatures for the onset of these responses are discussed and include, for example, adjustments of the oxygen delivery system, the heat shock response, cellular repair system, and transcriptome. Ultimately, however, an organism's ability to cope with environmental change is largely determined by its ability to maintain aerobic scope and to prevent loss in performance. These systemic constraints can determine an organism's long-term survival well before cellular and molecular functions are disturbed. The conceptual model we propose here discusses some of the crosslinks between responses at different levels of biological organisation and the central role of oxygen balance and oxidative stress in eliciting these responses with the aim to help the interpretation of environmental genomic data in the context of organismal function and performance. [source] OCTN2 is associated with carnitine transport capacity of rat skeletal musclesACTA PHYSIOLOGICA, Issue 1 2010Y. Furuichi Abstract Aim:, Carnitine plays an essential role in fat oxidation in skeletal muscles; therefore carnitine influx could be crucial for muscle metabolism. OCTN2, a sodium-dependent solute carrier, is assumed to transport carnitine into various organs. However, OCTN2 protein expression and the functional importance of carnitine transport for muscle metabolism have not been studied. We tested the hypothesis that OCTN2 is expressed at higher levels in oxidative muscles than in other muscles, and that the carnitine uptake capacity of skeletal muscles depends on the amount of OCTN2. Methods:, Rat hindlimb muscles (soleus, plantaris, and the surface and deep portions of gastrocnemius) were used for Western blotting to detect OCTN2. Tissue carnitine uptake was examined by an integration plot analysis using l -[3H]carnitine as a tracer. Tissue carnitine content was determined by enzymatic cycling methods. The percentage of type I fibres was determined by histochemical analysis. Results:, OCTN2 was detected in all skeletal muscles although the amount was lower than that in the kidney. OCTN2 expression was significantly higher in soleus than in the other skeletal muscles. The amount of OCTN2 was positively correlated with the percentage of type I fibres in hindlimb muscles. The integration plot analysis revealed a positive correlation between the uptake clearance of l -[3H]carnitine and the amount of OCTN2 in skeletal muscles. However, the carnitine content in soleus was lower than that in other skeletal muscles. Conclusion:, OCTN2 is functionally expressed in skeletal muscles and is involved in the import of carnitine for fatty acid oxidation, especially in highly oxidative muscles. [source] Nucleoside transporter and nucleotide vesicular transporter: Two examples of mnemonic regulationDRUG DEVELOPMENT RESEARCH, Issue 1-2 2001Raquel P. Sen Abstract According to their relevant roles in the regulation and availability of extracellular levels of purinergic signals, the nucleoside transporter and the nucleotide vesicular transporter are subject to acute regulation. The plasma membrane nucleoside transporter has been shown to exhibit several regulatory mechanisms, such as regulation by long-term signals, phosphorylation/dephosphorylation processes, and allosteric modulation. The present work reviews studies concerning allosteric modulation of nucleoside and nucleotide vesicular transporters, as the first reported examples of mnemonic behavior in transporter proteins, presenting kinetic and allosteric cooperativity. This fact implies that the protein can exhibit different conformations, each one with specific kinetic parameters. Transport substrates are able to induce slow conformational changes between the different forms of the transporter. This kinetic mechanism can provide several physiological advantages, since it allows strict control of transport capacity by changes in substrate concentrations. This allosteric modulation has been confirmed in several experimental models, the nucleoside transporter in chromaffin and endothelial cells from adrenal medulla and the nucleotide vesicular transporter in the chromaffin cell granules and rat brain synaptic vesicles. Taking into account these considerations, the mnemonic regulation described here could be a widespread mechanism among transporter proteins. Drug Dev. Res. 52:11,21, 2001. © 2001 Wiley-Liss, Inc. [source] Reduced-complexity flow routing models for sinuous single-thread channels: intercomparison with a physically-based shallow-water equation modelEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2009A. P. Nicholas Abstract Reduced-complexity models of fluvial processes use simple rules that neglect much of the underlying governing physics. This approach is justified by the potential to use these models to investigate long-term and/or fundamental river behaviour. However, little attention has been given to the validity or realism of reduced-complexity process parameterizations, despite the fact that the assumptions inherent in these approaches may limit the potential for elucidating the behaviour of natural rivers. This study presents two new reduced-complexity flow routing schemes developed specifically for application in single-thread rivers. Output from both schemes is compared with that from a more sophisticated model that solves the depth-averaged shallow water equations. This comparison provides the first demonstration of the potential for deriving realistic predictions of in-channel flow depth, unit discharge, energy slope and unit stream power using simple flow routing schemes. It also highlights the inadequacy of modelling unit stream power, shear stress or sediment transport capacity as a function of local bed slope, as has been common practice in a number of previous reduced-complexity models. Copyright © 2009 John Wiley & Sons, Ltd. [source] Prescribed-fire effects on rill and interrill runoff and erosion in a mountainous sagebrush landscape ,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2009Frederick B. Pierson Abstract Changing fire regimes and prescribed-fire use in invasive species management on rangelands require improved understanding of fire effects on runoff and erosion from steeply sloping sagebrush-steppe. Small (0·5 m2) and large (32·5 m2) plot rainfall simulations (85 mm h,1, 1 h) and concentrated flow methodologies were employed immediately following burning and 1 and 2 years post-fire to investigate infiltration, runoff and erosion from interrill (rainsplash, sheetwash) and rill (concentrated flow) processes on unburned and burned areas of a steeply sloped sagebrush site on coarse-textured soils. Soil water repellency and vegetation were assessed to infer relationships in soil and vegetation factors that influence runoff and erosion. Runoff and erosion from rainfall simulations and concentrated flow experiments increased immediately following burning. Runoff returned to near pre-burn levels and sediment yield was greatly reduced with ground cover recovery to 40 per cent 1 year post-fire. Erosion remained above pre-burn levels on large rainfall simulation and concentrated flow plots until ground cover reached 60 per cent two growing seasons post-fire. The greatest impact of the fire was the threefold reduction of ground cover. Removal of vegetation and ground cover and the influence of pre-existing strong soil-water repellency increased the spatial continuity of overland flow, reduced runoff and sediment filtering effects of vegetation and ground cover, and facilitated increased velocity and transport capacity of overland flow. Small plot rainfall simulations suggest ground cover recovery to 40 per cent probably protected the site from low-return-interval storms, large plot rainfall and concentrated flow experiments indicate the site remained susceptible to elevated erosion rates during high-intensity or long duration events until ground cover levels reached 60 per cent. The data demonstrate that the persistence of fire effects on steeply-sloped, sandy sagebrush sites depends on the time period required for ground cover to recover to near 60 per cent and on the strength and persistence of ,background' or fire-induced soil water repellency. Published in 2009 by John Wiley & Sons, Ltd. [source] Use of terrain variables for mapping gully erosion susceptibility in LebanonEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2007Rania Bou Kheir Abstract This paper predicts the geographic distribution and size of gullies across central Lebanon using a geographic information system (GIS) and terrain analysis. Eleven primary (elevation; upslope contributing area; aspect; slope; plan, profile and tangential curvature; flow direction; flow width; flow path length; rate of change of specific catchment area along the direction of flow) and three secondary (steady-state; quasi-dynamic topographic wetness; sediment transport capacity) topographic variables were generated and used along with digital data collected from other sources (soil, geology) to statistically explain gully erosion field measurements. Three tree-based regression models were developed using (1) all variables, (2) primary topographic variables only and (3) different pairs of variables. The best regression tree model combined the steady-state topographic wetness and sediment transport capacity indices and explained 80% of the variability in field gully measurements. This model proved to be simple, quick, realistic and practical, and it can be applied to other areas of the Mediterranean region with similar environmental conditions, thereby providing a tool to help with the implementation of plans for soil conservation and sustainable management. Copyright © 2007 John Wiley & Sons, Ltd. [source] The interaction between armouring and particle weathering for eroding landscapesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2006Saniya Sharmeen Abstract The interaction between particle weathering and surface armouring and its effect on erosion has been investigated. The effect of soil armouring is to decrease sediment transport with time by preferentially stripping away fine particles. On the other hand the effect of weathering, which breaks down the particles in the armour, is generally believed to increase erosion. By extending an existing armouring model, ARMOUR, and using a variety of published weathering mechanisms this interaction has been explored. The model predicts that while this is generally true, in some cases erosion can be decreased by weathering. When the particles generated by weathering were approximately of equal diameter, erosion increased while armouring decreased. When weathering produced very fine particles by spalling, erosion increased and armouring also increased. When weathering produced a range of particles from fine to coarse, the armour layer broke down and erosion decreased relative to the no-weathering case. This latter decrease in erosion was due to the high entrainment of coarser transportable materials from the bed decreasing the sediment transport capacity of the flow. In these studies clear regimes could be identified where erosion was limited by either the energy of the flow alone (i.e. ,transport-limited'), or the rate of weathering (,weathering-limited'); however, for some mechanisms there was an interaction between the two, which we called ,weathering/transport limited'. Copyright © 2006 John Wiley & Sons, Ltd. [source] Measurement and data analysis methods for field-scale wind erosion studies and model validation,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2003Ted M. Zobeck Abstract Accurate and reliable methods of measuring windblown sediment are needed to con,rm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to consider in conducting ,eld-scale wind erosion studies and proposes strategies of ,eld data collection for use in model validation and development. Detailed discussions include consideration of ,eld characteristics, sediment sampling, and meteorological stations. The ,eld shape used in ,eld-scale wind erosion research is generally a matter of preference and in many studies may not have practical signi,cance. Maintaining a clear non-erodible boundary is necessary to accurately determine erosion fetch distance. A ,eld length of about 300 m may be needed in many situations to approach transport capacity for saltation ,ux in bare agricultural ,elds. Field surface conditions affect the wind pro,le and other processes such as sediment emission, transport, and deposition and soil erodibility. Knowledge of the temporal variation in surface conditions is necessary to understand aeolian processes. Temporal soil properties that impact aeolian processes include surface roughness, dry aggregate size distribution, dry aggregate stability, and crust characteristics. Use of a portable 2 tall anemometer tower should be considered to quantify variability of friction velocity and aerodynamic roughness caused by surface conditions in ,eld-scale studies. The types of samplers used for sampling aeolian sediment will vary depending upon the type of sediment to be measured. The Big Spring Number Eight (BSNE) and Modi,ed Wilson and Cooke (MWAC) samplers appear to be the most popular for ,eld studies of saltation. Suspension ,ux may be measured with commercially available instruments after modi,cations are made to ensure isokinetic conditions at high wind speeds. Meteorological measurements should include wind speed and direction, air temperature, solar radiation, relative humidity, rain amount, soil temperature and moisture. Careful consideration of the climatic, sediment, and soil surface characteristics observed in future ,eld-scale wind erosion studies will ensure maximum use of the data collected. Copyright © 2003 John Wiley & Sons, Ltd. [source] Controls on englacial sediment deposition during the November 1996 jökulhlaup, Skei,arįrjökull, IcelandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2001Matthew J. Roberts Abstract This paper presents sedimentary evidence for rapid englacial debris entrainment during jökulhlaups. Previous studies of jökulhlaup sedimentology have focused predominantly on proglacial impact, rather than depositional processes within glaciers. However, observations of supraglacial floodwater outbursts suggest that englacial sediment emplacement is possible during jökulhlaups. The November 1996 jökulhlaup from Skei,arįrjökull, Iceland presented one of the first opportunities to examine englacial flood deposits in relation to former supraglacial outlets. Using observations from Skei,arįrjökull, this paper identifies and explains controls on the deposition of englacial flood sediments and presents a qualitative model for englacial jökulhlaup deposition. Englacial jökulhlaup deposits were contained within complex networks of upglacier-dipping fractures. Simultaneous englacial deposition of fines and boulder-sized sediment demonstrates that englacial fracture discharge had a high transport capacity. Fracture geometry was an important control on the architecture of englacial jökulhlaup deposits. The occurrence of pervasively frozen flood deposits within Skei,arįrjökull is attributed to freeze-on by glaciohydraulic supercooling. Floodwater, flowing subglacially or through upglacier-dipping fractures, would have supercooled as it was raised to the surface faster than its pressure-melting point could increase as glaciostatic pressure decreased. Evidence for floodwater contact with the glacier bed is supported by the ubiquitous occurrence of sheared diamict rip-ups and intra-clasts of basal ice within jökulhlaup fractures, deposited englacially some 200,350 m above the bed of Skei,arįrjökull. Evidence for fluidal supercooled sediment accretion is apparent within stratified sands, deposited englacially at exceptionally high angles of rest in the absence of post-depositional disturbance. Such primary sediment structures cannot be explained unless sediment is progressively accreted to opposing fracture walls. Ice retreat from areas of former supraglacial outbursts revealed distinct ridges characterized by localized upwellings of sediment-rich floodwater. These deposits are an important addition to current models of englacial sedimentation and demonstrate the potential for post-jökulhlaup landform development. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effects of agrin on the expression and distribution of the water channel protein aquaporin-4 and volume regulation in cultured astrocytesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Susan Noell Abstract Agrin is a heparan sulfate proteoglycan of the extracellular matrix and is known for organizing the postsynaptic differentiation of the neuromuscular junction. Increasing evidence also suggests roles for agrin in the developing CNS, including the formation and maintenance of the blood,brain barrier. Here we describe effects of agrin on the expression and distribution of the water channel protein aquaporin-4 (AQP4) and on the swelling capacity of cultured astrocytes of newborn mice. If astrocytes were cultured on a substrate containing poly dl -ornithine, anti-AQP4 immunoreactivity was evenly and diffusely distributed. If, however, astrocytes were cultured in the presence of agrin-conditioned medium, we observed an increase in the intensity of AQP4-specific membrane-associated staining. Freeze-fracture studies revealed a clustering of orthogonal arrays of particles, representing a structural equivalent of AQP4, when exogenous agrin was present in the astrocyte cultures. Neuronal and non-neuronal agrin isoforms (agrin A0B0 and agrin A4B8, respectively) were able to induce membrane-associated AQP4 staining. Water transport capacity as well as the density of orthogonal arrays of intramembranous particles was increased in astrocytes cultured with the neuronal agrin isoform A4B8, but not with the endothelial and meningeal isoform A0B0. RT-PCR demonstrated that agrin A4B8 increased the level of the M23 splice variant of AQP4 and decreased the level of the M1 splice variant of AQP4. Implications for the regulation and maintenance of the blood,brain barrier including oedema formation under pathological conditions are discussed. [source] Ecological implications of xylem cavitation for several Pinaceae in the Pacific Northern USAFUNCTIONAL ECOLOGY, Issue 5 2000J. Pińol Abstract 1.,Xylem hydraulic properties and vulnerability to cavitation (determined using the air-injection method) were studied in six Pinaceae of the northern Rocky Mountains: Pinus ponderosa, Pseudotsuga menziesii, Larix occidentalis, Pinus contorta, Pinus albicaulis and Abies lasiocarpa. We tested whether species extending into drier habitats exhibited increased resistance to water stress-induced cavitation, and whether there is a trade-off between xylem transport capacity and resistance to cavitation. 2.,At lower elevations the more drought-tolerant P. ponderosa was much less resistant to cavitation than the codominant P. menziesii. Greater vulnerability to cavitation in P. ponderosa was compensated for, at least in part, by increased stomatal control of water loss (inferred from carbon isotope discrimination) and by increased sapwood to leaf area ratios. Similar differences, but less pronounced, were found in codominant species at higher elevations. 3.,Leaf specific hydraulic conductivity was negatively correlated with mean cavitation pressure. When species were separated into pines and non-pines, sapwood specific conductivity and mean cavitation pressure were also negatively correlated within each of the two groups. 4.,Our results indicate that within the evergreen conifers examined, greater resistance to water stress-induced cavitation is not required for survival in more xeric habitats, and that there is a trade-off between xylem conductance and resistance to cavitation. [source] Interactive effects of elevated CO2 and soil fertility on isoprene emissions from Quercus roburGLOBAL CHANGE BIOLOGY, Issue 11 2004Malcolm Possell Abstract The effects of global change on the emission rates of isoprene from plants are not clear. A factor that can influence the response of isoprene emission to elevated CO2 concentrations is the availability of nutrients. Isoprene emission rate under standard conditions (leaf temperature: 30°C, photosynthetically active radiation (PAR): 1000 ,mol photons m,2 s,1), photosynthesis, photosynthetic capacity, and leaf nitrogen (N) content were measured in Quercus robur grown in well-ventilated greenhouses at ambient and elevated CO2 (ambient plus 300 ppm) and two different soil fertilities. The results show that elevated CO2 enhanced photosynthesis but leaf respiration rates were not affected by either the CO2 or nutrient treatments. Isoprene emission rates and photosynthetic capacity were found to decrease with elevated CO2, but an increase in nutrient availability had the converse effect. Leaf N content was significantly greater with increased nutrient availability, but unaffected by CO2. Isoprene emission rates measured under these conditions were strongly correlated with photosynthetic capacity across the range of different treatments. This suggests that the effects of CO2 and nutrient levels on allocation of carbon to isoprene production and emission under near-saturating light largely depend on the effects on photosynthetic electron transport capacity. [source] Hydrological and erosional response to natural rainfall in a semi-arid area of south-east SpainHYDROLOGICAL PROCESSES, Issue 4 2001M. Martinez-Mena Abstract A better knowledge of soil erosion by water is essential for planning effective soil and water conservation practices in semi-arid Mediterranean environments. The special climatic and hydrological characteristics of these areas, however, make accurate soil loss predictions difficult, particularly in the absence of minimal data. Two zero-order experimental microcatchments (328,759 m2), representative of an extensive semi-arid watershed with a high potential erosion risk in the south-east of Spain, were selected and monitored for 3 years (1991,93) in order to provide information on the hydrological and erosional response. A pluviogram and hydrograph recorded data at 1-min intervals during each storm, after which the soil loss was collected and the particle size of the sediment was analysed. Runoff coefficients of about 9% and soil losses of between 84·83 and 298·9 g m,2 year,1 were observed in the area. Rapid response times (geometric mean values lower than 2 h) and low runoff thresholds (mean values between 3·5 to 5·9 mm) were the norm in the experimental areas. A rain intensity of over 15 mm h,1 was considered as ,erosive rainfall' in these areas because of the total soil loss and the transport capacity of the overland flow. Differences in pore-size distribution explained the different hydrological responses observed between areas. The erosional response was more complex and basically seemed to be determined by soil aggregate stability and topographical properties. A greater proportion of finer particles in the eroded material than in the soil matrix indicated selective erosion and the transport of finer material. Copyright © 2001 John Wiley & Sons, Ltd. [source] Preserved Na+/H+ exchanger isoform 3 expression and localization, but decreased NHE3 function indicate regulatory sodium transport defect in ulcerative colitis,INFLAMMATORY BOWEL DISEASES, Issue 7 2010Sunil Yeruva PhD Abstract Background: A major causative factor of diarrhea in ulcerative colitis (UC) patients is the loss of Na+ absorptive capacity of the inflamed colonic mucosa. Potential contributing mechanisms include reduced driving force for active transport, and impaired expression, mislocalization, or defective transport function of Na+ absorptive proteins. We therefore studied the expression, brush border membrane (BBM) localization, and transport capacity of the major intestinal Na+ absorptive protein, the Na+/H+ exchanger isoform 3 (NHE3) in biopsies from UC patients. Methods: In UC and control biopsies, inflammation was graded histologically, NHE3, tumor necrosis factor alpha (TNF-,), villin, as well as other housekeeping genes were analyzed by quantitative real-time polymerase chain reaction (PCR), BBM localization of NHE3 determined by immunohistochemistry, and confocal microscopy. Na+ absorptive capacity was assessed by 22Na+ isotope fluxes and NHE3 transport activity measured microfluorometrically in BCECF-loaded surface colonocytes within isolated crypts. Results: In mildly, moderately, and severely inflamed sigmoid colon of UC patients, neither NHE3 mRNA expression nor the abundance of NHE3 in the BBM was significantly altered compared to other structural components of the BBM. However, Na+ absorption was strongly reduced by ,80% and acid-activated NHE3 transport activity was significantly decreased in the surface cells of sigmoid colonic crypts even in moderately inflamed mucosa. Conclusions: In the colonic mucosa of patients with active UC, NHE3 transport capacity was found significantly decreased despite correct NHE3 location and abundance in the brush border, independent of current treatment. These findings suggest functional NHE3 transport as a novel factor for inflammatory diarrhea in UC patients. (Inflamm Bowel Dis 2010) [source] In vitro studies on the effects of Saccharomyces boulardii and Bacillus cereus var. toyoi on nutrient transport in pig jejunumJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2000G. Breves The probiotics Saccharomyces boulardii and Bacillus cereus var. toyoi are nonpathogenic microbes which have been shown to affect certain functions of the mucosal barrier in pig jejunum such as electrogenic ion transport capacity and paracellular permeability. The present studies were performed to investigate potential effects of the probiotics on jejunal nutrient transport such as sodium-dependent glucose transport or proton-dependent dipeptide transport. For this purpose the in vitro Ussing-chamber technique was applied in order to examine net electrogenic ion flux rates (short circuit currents, Isc) across isolated intact jejunal epithelia in the absence and presence of either 10 mmol/l glucose (mucosal side) or two-fold application of 5 mmol/l glycyl- l -sarcosine or glycyl- l -glutamine to the mucosal bathing solution. Brush border membrane vesicles (BBMV) were prepared in order to characterize kinetic parameters (Vmax, Km) of Na-dependent glucose transport. Intestinal tissues were obtained from growing pigs in a weight range between 23 and 33 kg. All animals were fed twice daily and received 0.8,0.9 kg/day of a standard diet. After a 9- to 10-day adaptation period the diets for treated animals were either supplemented for 8 days with 1.7×107 colony-forming units (CFU)/g feed of S. boulardii or for 3 weeks with 106 CFU/g feed B. cereus var. toyoi. Under basal conditions Isc values were not affected by different treatment protocols (controls: 0.74 ± 0.04 µeq/cm2 per h, n=9; S. boulardii: 0.74 ± 0.12 µeq/cm2 per h, n=7; B. cereus 0.68 ± 0.09 µeq/cm2 per h, n=5). Irrespective of dietary treatment, the addition of glucose resulted in significant increases of Isc indicating substantial onset of electrogenic net Na/glucose cotransport. Maximal Isc values occurred within 30 min and reached 2.79 ± 0.41 µeq/cm2 per h in control epithelia. This was significantly lower than found in S. boulardii (4.47 ± 0.43 µeq/cm2 per h, p < 0.05) and B. cereus var. toyoi tissues (4.45 ± 0.31 µeq/cm2 per h, p < 0.05). Gt values were 22.4 ± 1.3 mS/cm2 in control animals and were significantly lower as shown in S. boulardii (p < 0.01) and B. cereus var. toyoi (p < 0.01)-treated animals (28.4 ± 1.3 and 29.9 ± 0.8 mS/cm2, respectively). Vmax values of Na-dependent glucose uptake into BBMV differed significantly between controls (0.64 ± 0.08 nmol/mg protein per 10 s; n=5), S. boulardii (0.89 ± 0.06 nmol/mg protein per 10 s; n=5, p < 0.05) and B. cereus var. toyoi preparations (1.08 ± 0.05 nmol/mg protein per 10 s; n=3, p < 0.01). Km values were not significantly affected (control: 0.31 ± 0.04 mmol/l, S. boulardii: 0.29 ± 0.05 mmol/l, B. cereus var. toyoi: 0.21 ± 0.01 mmol/l). Irrespective of dietary treatment, application of the dipeptide model substances glycyl- l -sarcosine or glycyl- l -glutamine resulted in significant increases of Isc indicating marked stimulation of electrogenic net H+/dipeptide cotransport. Highest Isc responses occurred in B. cereus var. toyoi preparations and lowest were found in control tissues. However, these differences were not significant. Gt values were not affected by different dietary treatments. The results clearly demonstrate that oral administration of either S. boulardii or B. cereus var. toyoi stimulates Na-dependent glucose absorption in pig jejunum. [source] The in vivo neuron-to-astrocyte lactate shuttle in human brain: evidence from modeling of measured lactate levels during visual stimulationJOURNAL OF NEUROCHEMISTRY, Issue 2009Silvia Mangia Abstract Functional magnetic resonance spectroscopy (fMRS) allows the non-invasive measurement of metabolite concentrations in the human brain, including changes induced by variations in neurotransmission activity. However, the limited spatial and temporal resolution of fMRS does not allow specific measurements of metabolites in different cell types. Thus, the analysis of fMRS data in the context of compartmentalized metabolism requires the formulation and application of mathematical models. In the present study we utilized the mathematical model introduced by Simpson et al. (2007) to gain insights into compartmentalized metabolism in vivo from the fMRS data obtained in humans at ultra high magnetic field by Mangia et al. (2007a). This model simulates brain glucose and lactate levels in a theoretical cortical slice. Using experimentally determined concentrations and catalytic activities for the respective transporter proteins, we calculate inflow and export of glucose and lactate in endothelium, astrocytes, and neurons. We then vary neuronal and astrocytic glucose and lactate utilization capacities until close correspondence is observed between in vivo and simulated glucose and lactate levels. The results of the simulations indicate that, when literature values of glucose transport capacity are utilized, the fMRS data are consistent with export of lactate by neurons and import of lactate by astrocytes, a mechanism that can be referred to as a neuron-to-astrocyte lactate shuttle. A shuttle of lactate from astrocytes to neurons could be simulated, but this required the astrocytic glucose transport capacity to be increased by 12-fold, and required that neurons not respond to activation with increased glycolysis, two conditions that are not supported by current literature. [source] Extracellular glucose concentration alters functional activity of the intestinal oligopeptide transporter (PepT-1) in Caco-2 cellsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2003Vanessa M. D'Souza Abstract The objective of this study was to determine the effect of different cell culture media glucose concentrations on the functional activity of PepT-1 in Caco-2 cells. Uptake kinetics of Gly-Sar into Caco-2 cells that were maintained in iso-osmotic media containing 25 or 5.5 mM glucose were determined in the presence and absence of amino acid-selective chemical modifiers and dithiothreitol. Inhibition of Gly-Sar uptake into Caco-2 cells was measured in the presence of dipeptides and xenobiotics exhibiting various binding affinities for the PepT-1. The effect of extracellular glucose on PepT-1 gene expression was assessed using comparative RT-PCR. Long-term exposure of Caco-2 cells to 25 mM glucose reduced maximum transport capacity for Gly-Sar uptake without altering PepT-1 gene expression. In contrast, binding affinity of Gly-Sar and other dipeptides or xenobiotics was not significantly changed. Chemical modification of Lys and Tyr residues decreased Vmax, while Cys modification increased the maximum transport capacity of the carrier. Preincubation of Caco-2 cells with dithiothreitol restored PepT-1 activity in cells maintained at 25 mM glucose. In conclusion, cell culture media containing 25 mM glucose decreases maximum transport capacity of PepT-1 in Caco-2 cells without affecting substrate recognition, at least in part, mediated via an oxidative pathway. © 2003 Wiley-Liss Inc. and the American Pharmaeceutical Association J Pharm Sci 92:594,603, 2003 [source] A method for improving predictions of bed-load discharges to reservoirsLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2007Vicente L. Lopes Abstract Effective management options for mitigating the loss of reservoir water storage capacity to sedimentation depend on improved predictions of bed-load discharges into the reservoirs. Most predictions of bed-load discharges, however, are based on the assumption that the rates of bed-load sediment availability equal the transport capacity of the flow, ignoring the spatio-temporal variability of the sediment supply. This paper develops a semiquantitative method to characterize bed-load sediment transport in alluvial channels, assuming a channel reach is non-supply limited when the bed-load discharge of a given sediment particle-size class is functionally related to the energy that is available to transport that fraction of the total bed-load. The method was applied to 22 alluvial stream channels in the USA to determine whether a channel reach had a supply-limited or non-supply-limited bed-load transport regime. The non-supply-limited transport regime was further subdivided into two groups on the basis of statistical tests. The results indicated the pattern of bed-load sediment transport in alluvial channels depends on the complete spectrum of sediment particle sizes available for transport rather than individual particle-size fractions represented by one characteristic particle size. The application of the method developed in this paper should assist reservoir managers in selecting bed-load sediment transport equations to improve predictions of bed-load discharge in alluvial streams, thereby significantly increasing the efficiency of management options for maintaining the storage capacity of waterbodies. [source] Height-related trends in leaf xylem anatomy and shoot hydraulic characteristics in a tall conifer: safety versus efficiency in water transportNEW PHYTOLOGIST, Issue 1 2008D. R. Woodruff Summary ,,Hydraulic vulnerability of Douglas-fir (Pseudotsuga menziesii) branchlets decreases with height, allowing shoots at greater height to maintain hydraulic conductance (Kshoot) at more negative leaf water potentials (,l). ,,To determine the basis for this trend shoot hydraulic and tracheid anatomical properties of foliage from the tops of Douglas-fir trees were analysed along a height gradient from 5 to 55 m. ,,Values of ,l at which Kshoot was substantially reduced, declined with height by 0.012 Mpa m,1. Maximum Kshoot was reduced by 0.082 mmol m,2 MPa,1 s,1 for every 1 m increase in height. Total tracheid lumen area per needle cross-section, hydraulic mean diameter of leaf tracheid lumens, total number of tracheids per needle cross-section and leaf tracheid length decreased with height by 18.4 µm2 m,1, 0.029 µm m,1, 0.42 m,1 and 5.3 µm m,1, respectively. Tracheid thickness-to-span ratio (tw/b)2 increased with height by 1.04 × 10,3 m,1 and pit number per tracheid decreased with height by 0.07 m,1. ,,Leaf anatomical adjustments that enhanced the ability to cope with vertical gradients of increasing xylem tension were attained at the expense of reduced water transport capacity and efficiency, possibly contributing to height-related decline in growth of Douglas fir. [source] LATE CAMBRIAN PLECTRONOCERID NAUTILOIDS AND THEIR ROLE IN CEPHALOPOD EVOLUTIONPALAEONTOLOGY, Issue 6 2007HARRY MUTVEI Abstract:, Numerous plectronocerid nautiloids appear in the Upper Cambrian of China. We have restudied their siphuncular structure, first described some 20 years ago. The siphuncle is characterized by: (1) long and holochoanitic septal necks dorsally but short and recurved necks laterally and ventrally; (2) strongly expanded connecting rings laterally; (3) two calcified layers in each connecting ring, outer spherulitic-prismatic and inner compact, the latter perforated by numerous pore canals; and (4) highly oblique siphuncular segments. The strongly expanded lateral sides of the connecting rings, together with the highly oblique course of the siphuncular segments, considerably enlarged the surface area of the connecting rings in each chamber, thereby increasing the transport capacity of cameral liquid. Thus, from their first appearance, plectronocerid nautiloids had developed a siphuncle for the replacement of cameral liquid with gases, and this system had a better and a more sophisticated design than that seen in stratigraphically younger nautiloids. However, their small orthoconic or slightly cyrtoconic shells were not well adapted for jet-powered swimming. [source] Comparison by PAM Fluorometry of Photosynthetic Activity of Nine Marine Phytoplankton Grown Under Identical Conditions,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2005P. Juneau ABSTRACT The photosynthetic activity of marine phytoplankton from five algal classes (Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira oceanica, Thalassiosira weissflogii, Dunaliella tertiolecta, Mantoniella squamata, Emiliania huxleyi, Pavlova lutheri and Heterosigma akashiwo) was investigated under identical growth conditions to determine interspecies differences. Primary photochemistry and electron transport capacity of individual species were examined by pulse amplitude-modulated (PAM) fluorescence. Although few differences were found in maximal photosystem II (PSII) photochemical efficiency between various species, large differences were noticed in their PSII-photosystem I (PSI) electron transport activity. We found that species such as T. oceanica and M. squamata have much lower photochemical activity than H. akashiwo. It appeared that processes involved in electron transport activity were more susceptible to change during algal evolution compared with the primary photochemical act close to PSII. Large variations in the nonphotochemical energy dissipation event among species were also observed. Light energy required to saturate photosynthesis was very different between species. We have shown that M. squamata and H. akashiwo required higher light energy (>1300 ,mol m,2 s,1) to saturate photosynthesis compared with S. costatum and E. huxleyi (ca 280 ,mol m,2 s,1). These differences were interpreted to be the result of variations in the size of lightharvesting complexes associated with PSII. These disparities in photosynthetic activity might modulate algal community structure in the natural environment where light energy is highly variable. Our results suggest that for an accurate evaluation of primary productivity from fluorescence measurements, it is essential to know the species composition of the algal community and the individual photosynthetic capacity related to the major phytoplankton species present in the natural phytoplankton assemblage. [source] Using combined measurements of gas exchange and chlorophyll fluorescence to estimate parameters of a biochemical C3 photosynthesis model: a critical appraisal and a new integrated approach applied to leaves in a wheat (Triticum aestivum) canopyPLANT CELL & ENVIRONMENT, Issue 5 2009XINYOU YIN ABSTRACT We appraised the literature and described an approach to estimate the parameters of the Farquhar, von Caemmerer and Berry model using measured CO2 assimilation rate (A) and photosystem II (PSII) electron transport efficiency (,2). The approach uses curve fitting to data of A and ,2 at various levels of incident irradiance (Iinc), intercellular CO2 (Ci) and O2. Estimated parameters include day respiration (Rd), conversion efficiency of Iinc into linear electron transport of PSII under limiting light [,2(LL)], electron transport capacity (Jmax), curvature factor (,) for the non-rectangular hyperbolic response of electron flux to Iinc, ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) CO2/O2 specificity (Sc/o), Rubisco carboxylation capacity (Vcmax), rate of triose phosphate utilization (Tp) and mesophyll conductance (gm). The method is used to analyse combined gas exchange and chlorophyll fluorescence measurements on leaves of various ages and positions in wheat plants grown at two nitrogen levels. Estimated Sc/o (25 °C) was 3.13 mbar µbar,1; Rd was lower than respiration in the dark; Jmax was lower and , was higher at 2% than at 21% O2; ,2(LL), Vcmax, Jmax and Tp correlated to leaf nitrogen content; and gm decreased with increasing Ci and with decreasing Iinc. Based on the parameter estimates, we surmised that there was some alternative electron transport. [source] Functional coordination between leaf gas exchange and vulnerability to xylem cavitation in temperate forest treesPLANT CELL & ENVIRONMENT, Issue 4 2006HAFIZ MAHERALI ABSTRACT We examined functional coordination among stem and root vulnerability to xylem cavitation, plant water transport characteristics and leaf traits in 14 co-occurring temperate tree species. Relationships were evaluated using both traditional cross-species correlations and phylogenetically independent contrast (PIC) correlations. For stems, the xylem tension at which 50% of hydraulic conductivity was lost (,50) was positively associated (P < 0.001) with specific conductivity (KS) and with mean hydraulically weighted xylem conduit diameter (Dh-w), but was only marginally (P = 0.06) associated with leaf specific conductivity (KL). The PIC correlation for each of these relationships, however, was not statistically significant. There was also no relationship between root ,50 and root KS in either cross-species or PIC analysis. Photosynthetic rate (A) and stomatal conductance (gs) were strongly and positively correlated with root ,50 in the cross-species analysis (P < 0.001), a relationship that was robust to phylogenetic correction (P < 0.01). A and gs were also positively correlated with stem ,50 in the cross-species analysis (P = 0.02 and 0.10, respectively). However, only A was associated with stem ,50 in the PIC analysis (P = 0.04). Although the relationship between vulnerability to cavitation and xylem conductivity traits within specific organs (i.e. stems and roots) was weak, the strong correlation between gs and root ,50 across species suggests that there is a trade-off between vulnerability to cavitation and water transport capacity at the whole-plant level. Our results were therefore consistent with the expectation of coordination between vulnerability to xylem cavitation and the regulation of stomatal conductance, and highlight the potential physiological and evolutionary significance of root hydraulic properties in controlling interspecific variation in leaf function. [source] Adjustment of leaf photosynthesis to shade in a natural canopy: rate parametersPLANT CELL & ENVIRONMENT, Issue 3 2005A. LAISK ABSTRACT The present study was performed to investigate the adjustment of the rate parameters of the light and dark reactions of photosynthesis to the natural growth light in leaves of an overstorey species, Betula pendula Roth, a subcanopy species, Tilia cordata P. Mill., and a herb, Solidago virgaurea L., growing in a natural plant community in Järvselja, Estonia. Shoots were collected from the site and individual leaves were measured in a laboratory applying a standardized routine of kinetic gas exchange, Chl fluorescence and 820 nm transmittance measurements. These measurements enabled the calculations of the quantum yield of photosynthesis and rate constants of excitation capture by photochemical and non-photochemical quenchers, rate constant for P700+ reduction via the cytochrome b6f complex with and without photosynthetic control, actual maximum and potential (uncoupled) electron transport rate, stomatal and mesophyll resistances for CO2 transport, Km(CO2) and Vm of ribulose-bisphosphate carboxylase-oxygenase (Rubisco) in vivo. In parallel, N, Chl and Rubisco contents were measured from the same leaves. No adjustment toward higher quantum yield in shade compared with sun leaves was observed, although relatively more N was partitioned to the light-harvesting machinery in shade leaves (H. Eichelmann et al., 2004). The electron transport rate through the Cyt b6f complex was strongly down-regulated under saturating light compared with darkness, and this was observed under atmospheric, as well as saturating CO2 concentration. In vivo Vm measurements of Rubisco were lower than corresponding reported measurements in vitro, and the kcat per reaction site varied widely between leaves and growth sites. The correlation between Rubisco Vm and the photosystem I density was stronger than between Vm and the density of Rubisco active sites. The results showed that the capacity of the photosynthetic machinery decreases in shade-adjusted leaves, but it still remains in excess of the actual photosynthetic rate. The photosynthetic control systems that are targeted to adjust the photosynthetic rate to meet the plant's needs and to balance the partial reactions of photosynthesis, down-regulate partial processes of photosynthesis: excess harvested light is quenched non-photochemically; excess electron transport capacity of Cyt b6f is down-regulated by ,pH-dependent photosynthetic control; Rubisco is synthesized in excess, and the number of activated Rubisco molecules is controlled by photosystem I-related processes. Consequently, the nitrogen contained in the components of the photosynthetic machinery is not used at full efficiency. The strong correlation between leaf nitrogen and photosynthetic performance is not due to the nitrogen requirements of the photosynthetic apparatus, but because a certain amount of energy must be captured through photosynthesis to maintain this nitrogen within a leaf. [source] Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitatsPLANT CELL & ENVIRONMENT, Issue 12 2001J. Cavender-Bares Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source] Public IP network infrastructure evolutions to support emerging digital video servicesBELL LABS TECHNICAL JOURNAL, Issue 2 2009Marc Verhoeyen Of all the services offered over a worldwide public network, digital video-based services, even at this early stage of development, are growing at such an astonishing rate that they will soon constitute the largest portion of Internet traffic. We are witnessing this today with the Internet television (TV) phenomenon, with YouTube, Netflix's online offering, and BBC's iPlayer serving as prominent examples. To optimize video-dominated networks with respect to the required transport capacity (and also to reduce the response time the end user experiences), these services need to be supported by new networking capabilities. Caching in conjunction with specific unicast and multicast techniques for ingress and egress traffic can achieve this goal. In this paper we discuss how, explicitly by using cache cooperation techniques, we can deal with heterogeneous content preferences among end users. The paper shows simulation results and discusses relevant parameters with respect to the Internet TV use cases mentioned. Finally, it provides an outlook on the longer term and demonstrates that investment in these new capabilities is future-safe. © 2009 Alcatel-Lucent. [source] Uterotubal transport disorder in adenomyosis and endometriosis,a cause for infertilityBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 8 2006S Kissler Objective, Uterine hyperperistalsis and dysperistalsis are common phenomena in endometriosis and may be responsible for reduced fertility in cases of minimal or mild extent of disease. Since a high prevalence of adenomyosis uteri has been well documented in association with endometriosis, we designed a study to examine whether hyperperistalsis and dysperistalsis are caused by the endometriosis itself or by the adenomyotic component of the disease. Design, A prospective observational study. Setting, University hospital, Department of Obstetrics and Gynaecology, Division of Reproductive Medicine and Gynaecologic Endocrinology with 300 in vitro fertilisation/intracytoplasmatic sperm injection cycles and 350 intrauterine insemination cycles/year. Population, Forty-one subjects with infertility and with laparoscopically proven endometriosis and patent fallopian tubes. Thirty-five subjects (85%) additionally showed signs of adenomyosis. Methods, All subjects underwent T2-weighed magnetic resonance imaging (MRI) and hysterosalpingoscintigraphy (HSSG) during the subsequent menstrual cycle. MRI revealed the extent of the adenomyotic component of the disease and the integrity of uterotubal transport capacity was evaluated by HSSG. Main outcome measures, Influence of adenomyosis on uterotubal transport capacity in endometriosis. Results, In 35 of the 41 subjects (85%) with endometriosis, signs of adenomyosis were detected using T2-weighed MRI. Two of six (33%) subjects with no adenomyosis (group I) showed dysperistalsis and hyperperistalsis, compared with 14 of 24 (58%) women with focal adenomyosis (group II) and 10 of 11 (91%) women with diffuse adenomyosis (seven showed a failure in transport capacity and two contralateral transport). Conclusions, Our data suggest that endometriosis is associated with impeded hyperperistaltic and dysperistaltic uterotubal transport capacity. However, adenomyosis is of even more importance, especially when diffuse adenomyosis is detected. Both forms of adenomyosis are commonly found in subjects with mild to moderate endometriosis. We suggest that the extent of the adenomyotic component in subjects with endometriosis explains much of the reduced fertility in subjects with intact tubo-ovarian anatomy. [source] Liver denervation affects hepatocyte mitochondrial fatty acid transport capacityCELL BIOCHEMISTRY AND FUNCTION, Issue 1 2004Flįvia R. Carreńo Abstract The effect of liver denervation on the activity of hepatic carnitine palmitoyltransferase (CPT) system, which catalyses the transfer of long-chain fatty acids into the mitochondria, was studied in rats. Noradrenaline content in phenol-denervated liver (D) was reduced by 87%. CPT I and II activities (measured by radioassay after detergent separation of the enzymes) were decreased (p,<,0.001) in D (2.6,± 0.1 and 0.68,±,0.2 nmol,min,1,mg,1 protein, respectively) as compared with controls (4.7,±,0.3 and 2.5,±,0.2 nmol,min,1,mg,1 protein, for CPT I and II, respectively). A less intense immunoreactive band for denervated liver CPT II was obtained after Western blotting. Concomitantly, long-chain fatty acid incorporation (p,<,0.001), evaluated after administration of [14C]-oleate and total fat content (p,<,0.001) were increased in D in relation to controls, while incorporation of exogenous [14C]-oleate into secreted VLDL, was decreased (p,<,0.01). The effect of sympathetic denervation on CPT activity was different from that evoked by adrenodemedullation, which caused an augmentation of CPT activity (p,<,0.01), when compared with the liver of intact rats. The effects of denervation and adrenodemedullation on the other parameters of lipid metabolism studied, were similar. The results strongly suggest a role of liver sympathetic innervation in the regulation of liver lipid metabolism. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||