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- Abrahamsson, Hans, 1966, et al.
(författare)
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Pulsed Hot-Wire Measurements in Two- and Three-Dimensional Wall Jets
- 1999
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Ingår i: Experiments in Fluids. ; 27, s. 210-218
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed Hot-Wire Anemometry (PHWA) measurements are performed in well defined two- and three-dimensional turbulent wall jets. For the two-dimensional wall jet the objective is to study reported differences between conventional Hot-Wire Anemometry (HWA) and Laser Doppler Anemometry (LDA) results. In the three-dimensional wall jet, new improved data are provided, employing a measuring technique suitable for highly turbulent flows. This, since only hot-wire results previously have been published for this flow. The pulsed wire results show good agreement with existing Laser Doppler anemometer data in the two-dimensional wall jet, both reporting significantly higher turbulence levels in the outer region of the flow than hot-wires do. The hot-wire anemometer errors generally increase with increasing local turbulence intensity and since the three-dimensional wall jet has a higher turbulence level than its two-dimensional equivalent, the new pulsed hot-wire results improve the information available for the turbulence field in this flow significantly.
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- Abrahamsson, Kate, 1959, et al.
(författare)
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Impaired ketogenesis in carnitine depletion caused by short-term administration of pivalic acid prodrug.
- 1994
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Ingår i: Biochemical medicine and metabolic biology. - : Elsevier BV. - 0885-4505. ; 52:1, s. 18-21
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Tidskriftsartikel (refereegranskat)abstract
- Long-term treatment with pivalic acid prodrug results in impaired ketone-body production. Therefore, it was of interest to investigate whether short-term treatment had any influence on the fatty acid oxidation. In this study six healthy males were given 1200 mg per day of pivmecillinam for 12 days to induce carnitine deficiency. The concentration of free carnitine in serum was reduced from a mean of 42.8 mumol/liter (range, 31-48) to 11.6 mumol/liter (range, 7.0-24), but the muscle carnitine concentration was not reduced. A 36-h fasting test was performed before and after drug administration to study the effect on ketone-body production. After treatment, the two subjects with the lowest level of serum free carnitine at the end of the fasting period had impaired ketogenesis. This indicates a carnitine deficiency in the liver which was reflected in the free carnitine concentration for by mobilization of muscle carnitine. We conclude that there is a substantial risk to develop carnitine deficiency and impaired fatty acid oxidation in the liver during short-term treatment with drugs conjugated with pivalic acid.
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- Abrahamsson, Kate, 1959, et al.
(författare)
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Pivalic acid-induced carnitine deficiency and physical exercise in humans.
- 1996
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Ingår i: Metabolism: clinical and experimental. - : Elsevier BV. - 0026-0495. ; 45:12, s. 1501-7
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Tidskriftsartikel (refereegranskat)abstract
- To study the effect of carnitine depletion on physical working capacity, healthy subjects were administered pivaloyl-conjugated antibiotics for 54 days. The mean carnitine concentration in serum decreased from 35.0 to 3.5 mmicromol/L, and in muscle from 10 to 4.3 micromol/g noncollagen protein (NCP). Exercise tests were performed before and after 54 days' administration of the drug. At submaximal exercise, there was a slight increase in the concentration of 3-hydroxybutyrate in serum, presumably caused by decreased fatty acid oxidation in the liver. There was also a decreased consumption of muscle glycogen, indicating decreased glycolysis in the skeletal muscle. The muscle presumably had enough energy available, since there was no significant decrease in the concentration of adenosine triphosphate (ATP) and creatine phosphate during exercise. The work at maximal oxygen uptake (VO2max) and the maximal heart rate were reduced. Since VO2max is considered dependent on heart function, carnitine depletion seemed to affect cardiac function.
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- Abrahamsson, Kate, 1959, et al.
(författare)
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Transient reduction of human left ventricular mass in carnitine depletion induced by antibiotics containing pivalic acid.
- 1995
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Ingår i: British heart journal. - : BMJ. - 0007-0769. ; 74:6, s. 656-9
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Tidskriftsartikel (refereegranskat)abstract
- To study the effect of induced carnitine depletion on myocardial structure and function.7 healthy adult volunteers given 1200 mg pivmecillinam per day for 7-8 weeks were studied by echocardiography before and after 7-8 weeks of treatment and a 15 months follow up after the treatment period.Teaching hospital.Carnitine concentration in serum, urine, and muscle and echocardiographic measurements.After 7-8 weeks of treatment the median free serum carnitine concentration was reduced to 7% and the median total muscle carnitine concentration to 46% of the pretreatment levels. The median diastolic interventricular septum thickness decreased by 14% (mean 26%, P = 0.028) and the median left ventricular mass by 10% (mean 20%, P = 0.018). Fifteen months later these dimensions had increased but not completely returned to pretreatment values.Extended treatment with pivalic acid containing antibiotics causes carnitine depletion which may lead to changes in cardiac structure.
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