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Oxidation Capacity (oxidation + capacity)

Distribution by Scientific Domains

Earth and Environmental Science	66%
Medical Sciences	25%

Selected Abstracts

Correlation of Hippocampal Glucose Oxidation Capacity and Interictal FDG-PET in Temporal Lobe Epilepsy

EPILEPSIA, Issue 2 2003
Stefan Vielhaber
Summary: ,Purpose: Interictal [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) demonstrates temporal hypometabolism in the epileptogenic zone of 60,90% of patients with temporal lobe epilepsy. The pathophysiology of this finding is still unknown. Several studies failed to show a correlation between hippocampal FDG-PET hypometabolism and neuronal cell loss. Because FDG is metabolized by hexokinase bound to the outer mitochondrial membrane, we correlated the glucose-oxidation capacity of hippocampal subfields obtained after surgical resection with the corresponding hippocampal presurgical FDG-PET activity. Methods: In 16 patients with electrophysiologically confirmed temporal lobe epilepsy, we used high-resolution respirometry to determine the basal and maximal glucose-oxidation rates in 400-,m-thick hippocampal subfields obtained after dissection of human hippocampal slices into the CA1 and CA3 pyramidal subfields and the dentate gyrus. Results: We observed a correlation of the FDG-PET activity with the maximal glucose-oxidation rate of the CA3 pyramidal subfields (rp = 0.7, p = 0.003) but not for the regions CA1 and dentate gyrus. In accordance with previous studies, no correlation of the FDG-PET to the neuronal cell density of CA1, CA3, and dentate gyrus was found. Conclusions: The interictal hippocampal FDG-PET hypometabolism in patients with temporal lobe epilepsy is correlated to the glucose-oxidation capacity of the CA3 hippocampal subfield as result of impaired oxidative metabolism. [source]

,-Oxidation capacity in liver increases during parr-smolt transformation of Atlantic salmon fed vegetable oil and fish oil

JOURNAL OF FISH BIOLOGY, Issue 2 2006
I. Stubhaug
Atlantic salmon Salmo salar were fed diets containing 100% fish oil (FO; capelin oil) or 100% vegetable oil (VO) from start of feeding until the fish reached the size of 2·5 kg. Samples were taken during the period of the parr-smolt transformation (October 2002 to February 2003). The VO diet consisted of a blend of 55% rapeseed oil, 30% palm oil and 15% linseed oil to maintain the sum of saturated, monounsaturated and polyunsaturated fatty acids between the two diets, although with differences in the individual chain length of fatty acids. Na+/K+ -ATPase activity in the gills, total ,-oxidation capacity in muscles and liver and total lipid, glycogen and dry matter content in the muscles were measured during the parr-smolt transformation and after seawater transfer. Na+/K+ -ATPase activity in gills increased prior to seawater transfer, showing an adaptation for seawater survival. Major changes in the lipid and glycogen content in the fillet and in ,-oxidation capacity were found in the tissues measured. ,-oxidation capacity increased significantly in liver and decreased in red muscle, prior to seawater transfer, giving liver an important role in energy production during this period. Results also indicated that feeding Atlantic salmon a diet where 100% of FO was replaced with VO did not have any negative effects on lipid metabolism during parr-smolt transformation. [source]

Mitochondrial and peroxisomal ,-oxidation capacities in various tissues from Atlantic salmon Salmo salar

AQUACULTURE NUTRITION, Issue 2 2000
FrØyland
In order to investigate the capacities of different tissues to oxidize fatty acids, total ,-oxidation (mitochondrial and peroxisomal) of [1,14C]palmitoyl-CoA was determined in liver and red- and white muscle from adult and juvenile Atlantic salmon Salmo salar. By including potassium cyanide (KCN) in the assay medium, it was possible to differentiate between mitochondrial and peroxisomal ,-oxidation capacities. Mitochondrial ,-oxidation dominated in all tissues except in livers from juvenile fish where the peroxisomal ,-oxidation dominated. In general, the red muscle possesses the highest fatty acid oxidation capacity, however, by taking into consideration the fact that white muscle occupies approximately 60% of the total body weight, this study demonstrates that the white muscle is an important tissue in the overall fatty acid catabolism. [source]

Hepatic phenylalanine metabolism measured by the [13C]phenylalanine breath test

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2001
T. Kobayashi
Background The amino acid clearance test including phenylalanine is known to reflect liver functional reserve, which correlates with surgical outcome; however, the procedure is not clinically useful because of its laborious and time-consuming nature. This study evaluates whether phenylalanine oxidation capacity measured by a breath test could reflect liver functional reserve. Design We determined phenylalanine oxidation capacity in 42 subjects using the l -[1- 13C]phenylalanine breath test (PBT). The 13CO2 breath enrichment was measured at 10-min intervals for 120 min after oral administration of 100 mg of l -[1- 13C]phenylalanine. Subjects were divided into the following three groups according to their plasma retention rate of indocyanine green at 15 min (ICG R15): Group I (ICG R15 <,10%), Group II (ICG R15 10,20%), and Group III (ICG R15 >,20%). First, we determined the parameters of the phenylalanine oxidation capacity that differentiated these groups and then, using these parameters, we compared the PBT with the ICG clearance test, Child,Pugh classification score and standard liver blood tests. Results The %13C dose h,1 at 30 min and cumulative excretion at 80 min were significantly different among the three groups (P < 0·05). These two parameters significantly correlated with the ICG R15, Child,Pugh classification score (P < 0·0001) and results of standard liver blood tests (P < 0·05). Conclusions Phenylalanine oxidation capacity measured by the PBT was reduced according to the severity of liver injury assessed by the ICG clearance test, Child,Pugh classification, and standard liver blood tests. These results indicate that the PBT can be used as a noninvasive method to determine liver functional reserve. [source]

,-Oxidation capacity in liver increases during parr-smolt transformation of Atlantic salmon fed vegetable oil and fish oil

Seasonally changing metabolism in Atlantic salmon (Salmo salar L.) II ,, -oxidation capacity and fatty acid composition in muscle tissues and plasma lipoproteins

AQUACULTURE NUTRITION, Issue 5 2003
U. Nordgarden
Abstract With the aim of elucidating seasonally changing lipid metabolism in immature Atlantic salmon (Salmo salar L.) in sea water, one group was reared under simulated natural light, while one group was reared under continuous light. Fatty acid profile in plasma lipoproteins did not vary during the experiment, while , -oxidation capacity increased during spring, concurrent with decreasing temperatures. Simultaneously, the relative level of monounsaturated fatty acids (MUFA) in muscle tissue decreased (42,36%). Muscle levels of saturated fatty acids were low during early spring (19%), but then increased slowly, and muscle levels of polyunsaturated fatty acids increased during spring (from 36% to 39%). It is suggested that increased spring growth and the concomitant energy demand was met by increased lipid oxidation, where MUFA were preferred as energy substrate. [source]

Mitochondrial and peroxisomal ,-oxidation capacities in various tissues from Atlantic salmon Salmo salar

Reduced sexual maturation in male post-smolt 1+ Atlantic salmon (Salmo salar L.) by dietary tetradecylthioacetic acid

AQUACULTURE RESEARCH, Issue 5 2009
Henriette Alne
Abstract In the present study, the possible effect of dietary treatment on early sexual maturation in post-smolt Atlantic salmon, without any negative effect regarding growth, was investigated. The experiment was performed using 4400 individually marked (Pit tag) 1+ salmon, fed either a control diet or a diet supplemented with 0.5% tetradecylthioacetic acid (TTA) in duplicates for 3, 6 or 12 weeks after sea transfer. Compared with the control, dietary supplementation of TTA resulted in a threefold reduction in incidence of sexual mature males (0.6% vs. 1.8%). A curve-linear relationship between relative reduction in maturation and weeks of feeding TTA was found, indicating that the effect is most marked as a result of the first weeks of feeding and then levelling off. No negative dietary impact on growth was observed. As the level of fat in the muscle was reduced by dietary TTA, it seems that post-smolt supplemented dietary TTA do not accumulate high enough energy stores to start the maturation process, whereas the energy-enhancing effect of TTA due to increased fatty acid oxidation capacity may maintain the growth potential. Compared with immature salmon, sexually maturing fish revealed increased spring growth before the onset of maturation. [source]

Oxidative Degradation of Azo Dyes by Manganese Peroxidase under Optimized Conditions

BIOTECHNOLOGY PROGRESS, Issue 2 2003
I. Mielgo
The application of enzyme-based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme manganese peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H2O2 addition, Mn2+ concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L,1). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H2O2 addition. The continuous addition at a controlled flow permitted the progressive participation of H2O2 in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn3+ was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems. [source]

Pharmacokinetics of sabeluzole and dextromethorphan oxidation capacity in patients with severe hepatic dysfunction and healthy volunteers

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 2 2001
G. P. Pageaux
Aims, The primary objective of this study was to determine how the pharmacokinetics of sabeluzole, an investigational drug with specific effects on memory and learning abilities, are affected by chronic liver disease. Since sabeluzole is metabolised by CYP2D6, a secondary objective was to study the correlation between CYP2D6 activity (as assessed by the dextromethorphan dextrorphan metabolic ratio) and hepatic dysfunction. Methods, The single-dose pharmacokinetics of sabeluzole (10 mg) was compared in 10 healthy Caucasian subjects and 10 patients with severe hepatic dysfunction. The urinary dextromethorphan/dextrorphan (DMP/DRP) metabolic ratio was determined after intake of 20 mg dextromethorphan (NODEX® capsules). Results, The terminal half-life of sabeluzole was significantly prolonged in subjects with severe hepatic dysfunction vs healthy subjects (respectively 39.3 ± 11.5 h; 17.5 ± 10.2 h (mean ±,s.d.)). The areas under the curve (AUC) were significantly higher in subjects with severe hepatic dysfunction than in healthy volunteers (681 ± 200 ng ml ,1h vs 331 ± 282 ng ml ,1h). There was a significant correlation between the AUC(0,,) and the DMP/DRP metabolic ratio in healthy volunteers and subjects with severe hepatic dysfunction. AUC was greater and elimination of sabeluzole slower in poor metabolizers compared with extensive metabolizers. Conclusions, These results suggest that a) sabeluzole dose should be reduced in patients with severe hepatic dysfunction and b) the AUC of sabeluzole is linked to individual CYP2D6 activity. [source]