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Cyclosporin A-dependent induction of lipid peroxidation in rat liver and kidney
Lipid Damage and Repair 13.25
VITAMIN E IN MEMBRANES INVESTIGATED WITH ~ B q C E ~ G. van Ginkel, A.A. van't Veld, F. Siemssen and Y.K. Levine Dept of Molecular Biophysics, Buys Ballot Laboratory, Princetonplein 5, Utrecht 3584 CC, The Netherlands. Vitamin E (u-tocopherol and other tocopherols) interacts with other membrane lipide in physiological processes. The question is how this interaction affects membrane organization. Answers can be obtained using the fluorescence emission of vitamin E itself and of added fluorescent probe molecules. The fluorescence decay of cetocopherol in both ethanol and cyclohexane does not change with concentration. In ethanol the decay is monoexponential, average lifetime < ~ > = 2.04 ns. In cyclohexane and various lipide a biexponential decay is found, with <.c> between 1.3 and 2.0 ns. Angle-resolved fluorescence depolarization (AFD) measurements in planar bilayers (DOPC, POPC, DLPC or PLPC), using DPH as a probe, show that o~-tocopherol hardly affects membrane structure (molecular order) but changes membrane dynamics (=fluidity) in a concentration dependent manner. Time-resolved anisotropy and AFD measurements show that at high concentrations (1:50 and 1:100 relative to DOPC) cx-tocopherol does not move within the time window of its fluorescence decay. At 1:100 ratio the ~-tocopherol chromophore is oriented perpendicular to the DOPC membrane plane, whereas at a 1:50 ratio it is oriented parallel.
13.27
MEASUR~4]~qT OF FREE RADICAL DAMAGE IN LUNG DISEASE IN PRETF/IM I~FANTS i D van Zo~ren-Grobben~,2JHN Lindema~ ,i E Houdkamp , H Griffiths , HM Berger . Neonatal Unit, University Hospital2Leiden, PO Box 9600 Leiden, The Netherlands. University of Birmingham UK. Oxygen induced free radicals play a role in diseases of the preterm infant (PT) e.g. bronchopulmonary dysplasia (BPD). We measured parameters of free radical damage: protein fluorescence (PF) and thiobarbituricacid reactive substances (TBARS) and the total antioxidant capacity (TRAP) in 14 healthy PT and 8 sick PT with pulmonary hyaline membrane disease (HMD) (which can be complicated by BPD) on day 0, 3 and 7. Comparing both groups: PF and TRAP did not differ, TBARS were higher in the HMD group at d7 (p<0.01). In both groups PF rose after birth [mean (SD): healthy dO: 6.03(2.83), dT: 9.12(2.93) p<0.001, HMD dO: 6.95(2.00), d7: 10.57(3.54) NS], as well as TBARS [healthy dO: 9.75(5.95), d7: 16.78(4.25) p<0.001, HMD dO: 14.37(6.72), d7: 24.06(6.12) p<0.001]. TRAP values fell in both groups [healthy dO: 956.0(229.0), d7: 685.3(149.7) p<0.01, HMU dO: 891.2(355.9), d7: 727.3(130.5) NS]. Free radical damage occurs in sick PT with HMD. The factors which make HMD infants more susceptible to free radical damage (e.g. oxygen therapy, parenteral feeding) must be eludicated. Supported by Milupa,
The Netherlands.
123
INFLUENCE OF STORAGE, TUBE FEEDING AND EXPOSURE TO LIGHT ON LIPID PEROXIDATION OF HUMAN MILK (HM) D. van Zoeren-Grobbe, R. Moison, W.M. Ester, H.M. Berger Neonatal Unit, University Hospital, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
13.26
Banked HM (refrigerated or deep frozen) is often used to feed preterm infants. Previously we reported that its vitamin C content decreases during storage and tube feeding (Arch Dis Child 1987;62:167). We have now studied the influence of these factors on the lipoperoxide (LP) concentration, measured by GCMS. LP increased after storage of I0 HM samples for 4 days at 4°C: - mean (SD) of ratio peroxidized linoleic acid nM/linoleic acid uM day O: 1.56 (i.01) vs day 4 : 3 . 0 6 (1.17) p<0.01. However, freezing did not have any effect. Tube feeding (simulating clinical conditions) with or without phototherapyexposure over 6 hours did not increase LP. More prolonged phototherapy produced a slight increase (ratio 1.86 (1.30) NS). In conclusion: storage of HM increases the exogenous load of LP in babies already at risk for free radical damage e.g. necrotising enterocolitis. Supported by Milupa, The Netherlands Gisela Thier foundation.
and the
CYCLOSPORIN A-DEPENDENT INDUCTION OF LIPID PEROXIDAT%ON IN RAT LIVER ANDKIDNEY Armin Wolf and Peter Donatsch Drug Safety Assessment, Department of Toxicology, Sandoz Pharma Ltd, CH-4002 Basle, Switzerland In man, Sandimmun a (SIM, CsA) has successfully been used in organ transplantation and in the treatment of autolmmune diseases. The drug, however has an adverse reaction profile which is mainly characterized by an impairment of liver and kidney functions. The mechanism by which these adverse reactions occur are not yet fully understood. There is some indirect evidence that activated oxygen species are involved in the pathomechanlsm of the drug. A project was therefore initiated in order to evaluate the importance of lipid peroxldatlon In the major target organs. For this reason rats were administered SIN at dose levels up to 80 mg/kg/day by garage for i0 days. Liver and kidneys were removed, homogenized and analyzed for thlobarblturic acld reactlve substances (Halondlaldehyde, MDA). The results showed that SIN treatment causes a dose dependent increase of MDA formed in vlvo both in liver and kidneys. These data were further supported by the evaluation of the remaining peroxidlzable capacity of the same tissues by in vitro measurements of the ADP-iron ascorbate induced -'C-~emiluminescence (CL). The CL, which is the result of the formation of lipid peroxlradlcals and s t n g l e t oxygen g e n e r a t i o n , was h a r d l y decreased both in l i v e r s and kidneys of SIM t r e a t e d a ni ma l s i n comparison to t h a t of placebo c o n t r o l s . This i n d i c a t e s t h a t the peroxldlzable components in these tissues were already to a great extent consumed. Preliminary results from trials to prevent lipid damage with three diets ¢ontaining various amounts of vitamin E showed that the concomitant application of SIM and the scavenger slightly improved liver and kidney functions without changing the pharmacokinetlc or immunosuppressive action of CsA. These results suggest that SIM induces lipid peroxidatlon in vlvo and that free radical formation might be involved in the pathomechanlsm of the drug.
13.28
VITAMIN E IN MEMBRANES INVESTIGATED WITH ~ B q C E ~ G. van Ginkel, A.A. van't Veld, F. Siemssen and Y.K. Levine Dept of Molecular Biophysics, Buys Ballot Laboratory, Princetonplein 5, Utrecht 3584 CC, The Netherlands. Vitamin E (u-tocopherol and other tocopherols) interacts with other membrane lipide in physiological processes. The question is how this interaction affects membrane organization. Answers can be obtained using the fluorescence emission of vitamin E itself and of added fluorescent probe molecules. The fluorescence decay of cetocopherol in both ethanol and cyclohexane does not change with concentration. In ethanol the decay is monoexponential, average lifetime < ~ > = 2.04 ns. In cyclohexane and various lipide a biexponential decay is found, with <.c> between 1.3 and 2.0 ns. Angle-resolved fluorescence depolarization (AFD) measurements in planar bilayers (DOPC, POPC, DLPC or PLPC), using DPH as a probe, show that o~-tocopherol hardly affects membrane structure (molecular order) but changes membrane dynamics (=fluidity) in a concentration dependent manner. Time-resolved anisotropy and AFD measurements show that at high concentrations (1:50 and 1:100 relative to DOPC) cx-tocopherol does not move within the time window of its fluorescence decay. At 1:100 ratio the ~-tocopherol chromophore is oriented perpendicular to the DOPC membrane plane, whereas at a 1:50 ratio it is oriented parallel.
13.27
MEASUR~4]~qT OF FREE RADICAL DAMAGE IN LUNG DISEASE IN PRETF/IM I~FANTS i D van Zo~ren-Grobben~,2JHN Lindema~ ,i E Houdkamp , H Griffiths , HM Berger . Neonatal Unit, University Hospital2Leiden, PO Box 9600 Leiden, The Netherlands. University of Birmingham UK. Oxygen induced free radicals play a role in diseases of the preterm infant (PT) e.g. bronchopulmonary dysplasia (BPD). We measured parameters of free radical damage: protein fluorescence (PF) and thiobarbituricacid reactive substances (TBARS) and the total antioxidant capacity (TRAP) in 14 healthy PT and 8 sick PT with pulmonary hyaline membrane disease (HMD) (which can be complicated by BPD) on day 0, 3 and 7. Comparing both groups: PF and TRAP did not differ, TBARS were higher in the HMD group at d7 (p<0.01). In both groups PF rose after birth [mean (SD): healthy dO: 6.03(2.83), dT: 9.12(2.93) p<0.001, HMD dO: 6.95(2.00), d7: 10.57(3.54) NS], as well as TBARS [healthy dO: 9.75(5.95), d7: 16.78(4.25) p<0.001, HMD dO: 14.37(6.72), d7: 24.06(6.12) p<0.001]. TRAP values fell in both groups [healthy dO: 956.0(229.0), d7: 685.3(149.7) p<0.01, HMU dO: 891.2(355.9), d7: 727.3(130.5) NS]. Free radical damage occurs in sick PT with HMD. The factors which make HMD infants more susceptible to free radical damage (e.g. oxygen therapy, parenteral feeding) must be eludicated. Supported by Milupa,
The Netherlands.
123
INFLUENCE OF STORAGE, TUBE FEEDING AND EXPOSURE TO LIGHT ON LIPID PEROXIDATION OF HUMAN MILK (HM) D. van Zoeren-Grobbe, R. Moison, W.M. Ester, H.M. Berger Neonatal Unit, University Hospital, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
13.26
Banked HM (refrigerated or deep frozen) is often used to feed preterm infants. Previously we reported that its vitamin C content decreases during storage and tube feeding (Arch Dis Child 1987;62:167). We have now studied the influence of these factors on the lipoperoxide (LP) concentration, measured by GCMS. LP increased after storage of I0 HM samples for 4 days at 4°C: - mean (SD) of ratio peroxidized linoleic acid nM/linoleic acid uM day O: 1.56 (i.01) vs day 4 : 3 . 0 6 (1.17) p<0.01. However, freezing did not have any effect. Tube feeding (simulating clinical conditions) with or without phototherapyexposure over 6 hours did not increase LP. More prolonged phototherapy produced a slight increase (ratio 1.86 (1.30) NS). In conclusion: storage of HM increases the exogenous load of LP in babies already at risk for free radical damage e.g. necrotising enterocolitis. Supported by Milupa, The Netherlands Gisela Thier foundation.
and the
CYCLOSPORIN A-DEPENDENT INDUCTION OF LIPID PEROXIDAT%ON IN RAT LIVER ANDKIDNEY Armin Wolf and Peter Donatsch Drug Safety Assessment, Department of Toxicology, Sandoz Pharma Ltd, CH-4002 Basle, Switzerland In man, Sandimmun a (SIM, CsA) has successfully been used in organ transplantation and in the treatment of autolmmune diseases. The drug, however has an adverse reaction profile which is mainly characterized by an impairment of liver and kidney functions. The mechanism by which these adverse reactions occur are not yet fully understood. There is some indirect evidence that activated oxygen species are involved in the pathomechanlsm of the drug. A project was therefore initiated in order to evaluate the importance of lipid peroxldatlon In the major target organs. For this reason rats were administered SIN at dose levels up to 80 mg/kg/day by garage for i0 days. Liver and kidneys were removed, homogenized and analyzed for thlobarblturic acld reactlve substances (Halondlaldehyde, MDA). The results showed that SIN treatment causes a dose dependent increase of MDA formed in vlvo both in liver and kidneys. These data were further supported by the evaluation of the remaining peroxidlzable capacity of the same tissues by in vitro measurements of the ADP-iron ascorbate induced -'C-~emiluminescence (CL). The CL, which is the result of the formation of lipid peroxlradlcals and s t n g l e t oxygen g e n e r a t i o n , was h a r d l y decreased both in l i v e r s and kidneys of SIM t r e a t e d a ni ma l s i n comparison to t h a t of placebo c o n t r o l s . This i n d i c a t e s t h a t the peroxldlzable components in these tissues were already to a great extent consumed. Preliminary results from trials to prevent lipid damage with three diets ¢ontaining various amounts of vitamin E showed that the concomitant application of SIM and the scavenger slightly improved liver and kidney functions without changing the pharmacokinetlc or immunosuppressive action of CsA. These results suggest that SIM induces lipid peroxidatlon in vlvo and that free radical formation might be involved in the pathomechanlsm of the drug.
13.28