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Start Over Creator Ondriaš, K.

1. An unusual temperature dependence of malondialdehyde formation in Fe2+/H2O2-initiated lipid peroxidation of phosphatidylcholine liposomes

Creator:
Mišík, V., Gergeľ, D., Alov, P., and Ondriaš, K.
Type:
article, model:article, and TEXT
Subject:
lipid peroxidation, malondialdehyde, temperature dependence, and oxygen consumption
Language:
English
Description:
Determination of malondialdehyde is a widely used procedure for measurement of lipid peroxidation. In this paper we report an unusual temperature dependence of malondialdehyde formation in egg yolk phosphatidylcholine liposomes oxidized by the Fenton system (0.1 mmol/1 FeSC>4 and 0.05 mmol/1 H2O2). The amount of malondialdehyde formed was 37 % higher in samples kept at 22 °C than at 50 °C. An alternative method for determination of lipid peroxidation, measurement of oxygen uptake, revealed complete consumption of dissolved oxygen to peroxidized lipids at 22 °C as well as 50 °C. Since oxygen is essential for the formation of cyclic peroxides - precursors of malondialdehyde - we conclude that the nature of the observed effect consists in limitation of oxygen availability at elevated temperatures.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Antioxidant and pro-oxidant effects of epinephrine and isoprenaline on peroxidation of LDL and lipid liposomes

Creator:
Ondriaš, K., Staško, A., Gergeľ, D., Hromadová, M., and Mišík, V.
Type:
article, model:article, and TEXT
Subject:
antioxidant, epinephrine, isoprenaline, peroxidation, low density lipoprotein, lipoxidase, and iron
Language:
English
Description:
Antioxidant or pro-oxidant properties of epinephrine (EPI) and isoprenaline (ISO) were studied in the absence and presence of Fe2+ , Fe3+ and Cu2+ ions. EPI and ISO (>2 /tmol/1) inhibited peroxidation of low density lipoprotein (LDL) induced by 2, 2’-azobis(2-amidino-propane) (AAPH). EPI had a similar inhibitory potency as ISO, but their potency was several times higher than the potency of a-tocopherol (a-TOC). When the LDL peroxidation was induced by 5 /tmol/1 CUSO4, EPI and ISO enhanced LDL peroxidation at low concentrations (10/mol/l) and decreased peroxidation at higher concentrations (30 /tmol/1). The compounds had a similar tendency to inhibit the peroxidation of phosphatidylcholine liposomes. EPI (3-30 //¿mol/1) inhibited lipid peroxidation of phosphatidylcholine liposomes induced by 2 mmol/1 of AAPH, but it was less effective and even increased the peroxidation, when the samples contained 2 mmol/1 AAPH with 50 /¿mol/l FeSC>4 or 2 mmol/1 AAPH with 20/imol/l FeCb. Inhibition of lipid peroxidation by EPI was also observed when studying decreased oxygen consumption, when the peroxidation of linoleic acid was induced by lipoxidase. In conclusion, EPI and ISO reduced lipid peroxidation, but they exhibit pro-oxidant properties in the presence of Fe2+, Fe3+ or Cu2+ ions, depending on the catecholamine and ionic concentration.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Comparison of the potency of five potential β-adrenoceptor blocking drugs and eight calcium channel blockers to inhibit platelet aggregation and to perturb liposomal membranes prepared from platelet lipids

Creator:
Ondriašová, E., Ondriaš, K., Staško, A., Nosál, R., and Csöllei, J.
Type:
article, model:article, and TEXT
Subject:
calcium blockers, β-Adrenoceptor blocking drugs, platelet aggregation, liposome perturbation, and EPR spectroscopy
Language:
English
Description:
Five potential /3-adrenoceptor blocking (BAB) compounds, alkylesters of 4-[(2-hydroxy-3-alkylamino)propoxy] phenylcarbamic acid, and eight calcium channel blockers (CB), i.e. nifedipine, nimodipine, niludipine, nitrendipine, verapamil, gallopamil, mepamil and diltiazem, were compared as to their inhibitory effect on thrombin induced aggregation of washed rat platelets and their effect on dynamies/disorder of liposomal membranes prepared from platelet lipids, studied by EPR spectroscopy of a lipid spin probe. The anti-aggregatory potency of the BAB and CB drugs was effective within the concentration range of 0.01-1 mmol/1. The antiaggregatory potency of BAB increased in the order BL- 143< BL-243< BL-343 < BL-443 < BL-543 and among the CB, nifedipine and diltiazem were the least potent, whereas nitrendipine and mepamil were the most potent drugs. The potency of the other CB tested was intermediate. The BAB drugs increased the dynamies/disorder of the liposomes in the same order as they inhibited platelet aggregation, whereas there was no relationship between antiaggregatory effect of CB and their influence on dynamies/disorder of the liposomes. Nifedipine, nimodipine, niludipine and nitrendipine had a minor perturbation effect on the liposomes, whereas verapamil, mepamil, gallopamil and diltiazem pronouncedly increased the dynamies/disorder of the hydro- phobic part of the liposomes. The results indicate that the anti-aggregatory activity of BAB drugs may be mediated, at least partially, through their perturbation effect on the lipid part of biological membranes.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Effect of cisplatin, carboplatin and stobadine on lipid peroxidation of kidney homogenate and phosphatidylcholine liposomes

Creator:
Gergeľ, O., Mišík, V., and Ondriaš, K.
Type:
article, model:article, and TEXT
Subject:
cisplatin, carboplatin, stobadine, kidney Homogenate, liposomes, and lipid peroxidation
Language:
English
Description:
The effects of the nephrotoxic, anticancer agents cisplatin (CDI)P) and carboplatin (CBDCA), and the free radical scavenger, stobadine, were investigated on lipid peroxidation (EI’O) of rat kidney homogenates and phosphatidylcholine (PC) liposomes. Kidney homogenates were incubated in air at 37 °C for 6-48 h and lipid peroxidation was detected spectroscopically as absorbance (533 nm) of the thiobarbituric acid- malondialdchyde (TBA-MDA) complex. CDDP (0.3-10 mmol.I'1) increased LPO of the homogenate. CBDCA decreased the TBA-MDA absorbance, yet was found to interfere with MDA, TBA and/or with the TBA-MDA complex. Thus when CBDCA is involved, the TBA- MDA method for detection of LPO is not suitable. Stobadine (0.1 mmol.I'1 ar>d 1 mmol.I1) inhibited LPO either in the control homogenate and in the homogenate where peroxidation was increased by CDDP. The effect of CDDP and CBDCA on peroxidation of PC liposomes was monitored as oxygen consumption using a Clark-type oxygen electrode. CDDP increased but CBDCA decreaed the rate of oxygen consumption during the peroxidation of liposomes induced by FcSO,». The results suggest that the effects of CDDP and CBDCA on LPO may be linked with their nephrotoxicity.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Effect of ethanol on tracheal potassium channels reconstituted into bilayer lipid membranes

Creator:
Komínková, V., Magová, M., Mojžišová, A., Máleková, Ľ., and Ondriaš, K.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, potassium channel, trachea - ethanol, bilayer lipid membrane, bronchodilation, 14, and 612
Language:
English
Description:
We examined the effect of ethanol on single potassium channels derived from plasma membranes of bovine tracheal smooth muscles. The observed potassium channels had a conductance of 296±31 pS (mean ± S.D.) in symmetrical 250 mmol/l KCl solutions, and exhibited a voltage- and Ca2+-dependence similar to BKCa channels. Ethanol at 50, 100 and 200 mM concentrations increased the probability of open potassium channels to 112±5, 127±7 and 121±13% (mean ± S.E.M.), respectively. It is suggested that increased activity of the BKCa channels by ethanol hyperpolarizes the plasma membrane and thus may contribute to relaxation of tracheal smooth muscle., V. Komínková, M. Magová, A. Mojžišová, Ľ. Máleková, K. Ondriaš., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public