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1

Response of Acanthamoeba castellanii mitochondria to oxidative stress

100%
Trocha L. K., Stobienia O.
Acta Biochimica Polonica
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2007
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tom 54
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nr 4
797-803
The purpose of this study was to examine the effects of oxidative stress caused by hydroperoxide (H2O2) in the presence of iron ions (Fe2+) on mitochondria of the amoeba Acanthamoeba castellanii. We used isolated mitochondria of A. Castellanii and exposed them to four levels of H2O2 concentration: 0.5, 5, 15, and 25 mM. We measured basic energetics of mitochondria: oxygen consumption in phosphorylation state (state 3) and resting state (state 4), respiratory coefficient rates (RC), ADP/O ratios, membrane potential (ΔΨm), ability to accumulate Ca2+ , and cytochrome crelease. Our results show that the increasing concentrations of H2O2 stimulates respiration in states 3 and 4. The highest concentration of H2O2 caused a 3-fold increase in respiration in state 3 compared to the control. Respiratory coefficients and ADP/O ratios decreased with increasing stress conditions. Membrane potential significantly collapsed with increasing hydroperoxide concentration. The ability to accumulate Ca2+ also decreased with the increasing stress treatment. The lowest stress treatment (0.5 mM H2O2) significantly decreased oxygen consumption in state 3 and 4, RC, and membrane potential. The ADP/O ratio decreased significantly under 5 mM H2O2 treatment, while Ca2+ accumulation rate decreased significantly at 15 mM H2O2. We also observed cytochrome crelease under increasing stress conditions. However, this release was not linear. These results indicate that as low as 0.5 mM H2O2 with Fe2+ damage the basic energetics of mitochondria of the unicellular eukaryotic organism Acanthamoeba castellanii
2

Determination of hydroperoxides in aqueous solutions containing surfactants by the ferrous oxidation-xylenol orange method

84%
Meisner P., Gebicki J. L.
Acta Biochimica Polonica
|
2009
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tom 56
|
nr 3
523-527
 Some surfactants widely used as additives in food, pharmaceuticals, and cosmetic formulations are susceptible to peroxidation resulting in accumulation of hydroperoxides (HP). Our investigation was aimed to study the possible influence of different surfactants on the proportionality and reproducibility of the ferrous oxidation-xylenol orange method developed originally for the determination of hydroperoxides. We also attempted to apply this method to determine hydroperoxides produced radiolytically in surfactant molecules. From our preliminary studies we conclude that the method can be applied for determination of hydroperoxides in systems containing non-ionic or anionic surfactants provided careful calibration is performed for each surfactant.
3

Immunolocalization of lipoxygenase in the anther of Gagea lutea (L.) Ker.-Gaw.

84%
Szczuka E., Skorzynska-Polit E., Pawlikowska-Pawlega B., Sobieska J., Gawron A.
Acta Biologica Cracoviensia. Series Botanica. Supplement
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2005
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tom 47
|
nr 1
4

Mimicking of glutathione peroxidase deficiency by exposition of JAR cells to increased level of synthetic hydroperoxide

84%
Hallmann A., Milczarek R., Szkatula M., Wozniak M., Spodnik J. H., Klimek J.
Folia Morphologica
|
2005
|
tom 64
|
nr 4
304-308
A short chain synthetic analogue of lipid hydroperoxides was used to overload glutathione peroxidase (GPx) in human choriocarcinoma cell line JAR cells. Cells exposed to 100 µM tBuOOH displayed a 40% reduction in ATP level and significantly increased in membrane permeability, visualised by the lactate dehydrogenase (LDH) release into the extracellular medium. The intracellular level of oxygen free radicals measured as an oxidation of the dichlorodihydro-fluorescein diacetate (H₂DCF-DA) significantly increased after 2 hours of cell exposition to 100 µM tBuOOH. Concomitantly MDA, 4-HNE level increased to 2 nmol/mg of cell protein after 2 hours. Mitochondria stained with MitoTracker Red CMXRos displayed a filamentous appearance in control cells but changed into granular less energised organelles after exposition to tBuOOH. Collectively, the above results indicate the importance of the contribution of oxidative stress in the development of pre-eclampsia.
5

Rosemary extract as an inhibitor of oxidation of cold-pressed flaxseed and rapeseed oils

84%
Sielicka M., Malecka M.
Towaroznawcze Problemy Jakości. Polskie Towarzystwo Towaroznawcze
|
2013
|
nr 4
6

Decomposition of lipid hydroperoxides enhances the uptake of low density lipoprotein by macrophages

84%
Babiy A. V., Gebicki J. M.
Acta Biochimica Polonica
|
1999
|
tom 46
|
nr 1
This study examined the roles of low-density lipoprotein (LDL) lipid oxidation and peroxide breakdown in its conversion to a form rapidly taken up by mouse peritoneal macrophages. Oxidation of the LDL without decomposition of the hydroperoxide groups was performed by exposure to gamma radiation in air-saturated solutions. Virtually complete decomposition of the hydroperoxides was achieved by treatment of the irradiated LDL with Cu2+ under strictly anaerobic conditions. No uncontrolled LDL uptake by macrophages occurred when the lipoprotein contained less than 150 hydroperoxide groups per particle. More extensively oxidized LDL was taken up and degraded by mouse macrophages significantly faster than the native lipoprotein. The uptake was greatly enhanced by treatment of the oxidized LDL with Cu2+. A significant proportion of the LDL containing intact or copper-decomposed LDL hydroperoxide groups accumulated within the macrophages without further degradation. Treatment of the radiation-oxidized LDL with Cu2+ was accompanied by aggregation of the particles. Competition studies showed that the oxidized LDL was taken up by macrophages via both the LDL and the scavenger receptors, whereas the copper-treated lipoprotein entered the cells only by the scavenger pathway. Phagocytosis also played an important role in the metabolism of all forms of the extensively modified LDL. Our results suggest that minimally-oxidized LDL is not recognized by the macrophage scavenger receptors unless the lipid hydroperoxide groups are decomposed to products able to derivatize the apo B protein.
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