P. Gróf | Semmelweis University (original) (raw)

Related Authors

Szabolcs Béni

Abdel Omri

Laura Ciani

Alejandro Duque

Alicia Alonso

Alicia Alonso

University of the Basque Country, Euskal Herriko Unibertsitatea

Uploads

Papers by P. Gróf

Research paper thumbnail of Studies on molecular interactions between nalidixic acid and liposomes

International journal of pharmaceutics, Jan 26, 2004

The interaction between nalidixic acid sodium salt (NANa) and liposomes prepared from alpha-L-dip... more The interaction between nalidixic acid sodium salt (NANa) and liposomes prepared from alpha-L-dipalmitoyl-phosphatidylcholine (DPPC) or from its binary mixture with dioleoyl-phosphatidylcholine (DOPC) was studied with differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) spectroscopy. We evaluated the role of broadband ultraviolet-B (UV-B) irradiation on the molecular interactions between the lipids and the NANa, and determined the decay-kinetics of the incorporated spin labeled fatty-acid free radicals. Multilamellar and unilamellar vesicles were prepared by sonication and extrusion. The entrapment efficiencies were determined spectrophotometrically. The size-distribution of the liposomes and its change in time was checked by dynamic light scattering (DLS). Our results indicate that NANa mainly interacts with lipid head groups. However, its effect and presumably the formation of the free radicals, induced by broadband ultraviolet-B, is not localized only...

Research paper thumbnail of Biological UV dosimeters in the assessment of the biological hazard from environmental radiation

Journal of photochemistry and photobiology. B, Biology

To determine the impact of environmental UV radiation, biological dosimeters that weight directly... more To determine the impact of environmental UV radiation, biological dosimeters that weight directly the incident UV components of sunlight have been developed, improved and evaluated in the frame of the BIODOS project. Four DNA-based biological dosimeters ((i) phage T7, (ii) uracil thin layer, (iii) spore dosimeter and (iv) DLR-biofilm) have been assessed from the viewpoint of their biological relevance, spectral response and quantification of their biological effectiveness. The biological dosimeters have been validated by comparing their readings with weighted spectroradiometer data, by comparison with other biological doses, as well as with the determined amounts of DNA UV photoproducts. The data presented here demonstrate that the biological dosimeters are potentially reliable field dosimeters for measuring the integrated biologically effective irradiance for DNA damage.

Research paper thumbnail of Combined Supporting Information S1

Research paper thumbnail of Biological UV dosimeters in the assessment of the biological hazard from environmental radiation

Journal of Photochemistry and Photobiology B: Biology, 1999

S 1 0 1 1 -1 3 4 4 ( 9 9 ) 0 0 1 2 3 -2 Thursday Dec 23 09:03 AM StyleTag --Journal: JPB (J. Phot... more S 1 0 1 1 -1 3 4 4 ( 9 9 ) 0 0 1 2 3 -2 Thursday Dec 23 09:03 AM StyleTag --Journal: JPB (J. Photochem. Photobiol. B: Biol.) Article: 7887 www.elsevier.nl/locate/jphotobiol J.

Research paper thumbnail of Effect of UVA radiation on membrane fluidity and radical decay in human fibroblasts as detected by spin labeled stearic acids

Journal of Photochemistry and Photobiology B: Biology, 2004

The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a sourc... more The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a source of oxidative stress to cells via generation of reactive oxygen species. We report here some consequences of the UVA irradiation on cell membranes detected by electron paramagnetic resonance (EPR) spectroscopy. Paramagnetic nitroxide derivatives of stearic acid bearing the monitoring group at different depths in the hydrocarbon chain were incorporated into human fibroblasts membranes to analyze two main characteristics: kinetics of the nitroxide reduction and membrane fluidity. These two characteristics were compared for control and UVA-irradiated (0-250 kJ/m 2 ) cells. The term relative redox capacity (RRC) was introduced to characterize and to compare free radical reduction measured by EPR with some well-known viability/clonogenicity tests. Our results showed that UVA-irradiation produces a more rigid membrane structure, especially at higher doses. Furthermore, we found that trends agree in survival measured by neutral red (NR), trypan blue (TB), and clonogenic efficiency compared with RRC values measured by EPR for low and medium exposure doses. Above 100 kJ/m 2 , differences between these tests were observed. Antioxidant effect was modeled by a-tocopherolacetate treatment of the cells before UVA irradiation. While NR, TB and clonogenicity tests showed protection at the highest UVA doses (>100 kJ/m 2 ), results obtained with EPR measurements, both membrane fluidity and kinetics, or using MTT test did not exhibit this protective effect.

Research paper thumbnail of Studies on molecular interactions between nalidixic acid and liposomes

International journal of pharmaceutics, Jan 26, 2004

The interaction between nalidixic acid sodium salt (NANa) and liposomes prepared from alpha-L-dip... more The interaction between nalidixic acid sodium salt (NANa) and liposomes prepared from alpha-L-dipalmitoyl-phosphatidylcholine (DPPC) or from its binary mixture with dioleoyl-phosphatidylcholine (DOPC) was studied with differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) spectroscopy. We evaluated the role of broadband ultraviolet-B (UV-B) irradiation on the molecular interactions between the lipids and the NANa, and determined the decay-kinetics of the incorporated spin labeled fatty-acid free radicals. Multilamellar and unilamellar vesicles were prepared by sonication and extrusion. The entrapment efficiencies were determined spectrophotometrically. The size-distribution of the liposomes and its change in time was checked by dynamic light scattering (DLS). Our results indicate that NANa mainly interacts with lipid head groups. However, its effect and presumably the formation of the free radicals, induced by broadband ultraviolet-B, is not localized only...

Research paper thumbnail of Biological UV dosimeters in the assessment of the biological hazard from environmental radiation

Journal of photochemistry and photobiology. B, Biology

To determine the impact of environmental UV radiation, biological dosimeters that weight directly... more To determine the impact of environmental UV radiation, biological dosimeters that weight directly the incident UV components of sunlight have been developed, improved and evaluated in the frame of the BIODOS project. Four DNA-based biological dosimeters ((i) phage T7, (ii) uracil thin layer, (iii) spore dosimeter and (iv) DLR-biofilm) have been assessed from the viewpoint of their biological relevance, spectral response and quantification of their biological effectiveness. The biological dosimeters have been validated by comparing their readings with weighted spectroradiometer data, by comparison with other biological doses, as well as with the determined amounts of DNA UV photoproducts. The data presented here demonstrate that the biological dosimeters are potentially reliable field dosimeters for measuring the integrated biologically effective irradiance for DNA damage.

Research paper thumbnail of Combined Supporting Information S1

Research paper thumbnail of Biological UV dosimeters in the assessment of the biological hazard from environmental radiation

Journal of Photochemistry and Photobiology B: Biology, 1999

S 1 0 1 1 -1 3 4 4 ( 9 9 ) 0 0 1 2 3 -2 Thursday Dec 23 09:03 AM StyleTag --Journal: JPB (J. Phot... more S 1 0 1 1 -1 3 4 4 ( 9 9 ) 0 0 1 2 3 -2 Thursday Dec 23 09:03 AM StyleTag --Journal: JPB (J. Photochem. Photobiol. B: Biol.) Article: 7887 www.elsevier.nl/locate/jphotobiol J.

Research paper thumbnail of Effect of UVA radiation on membrane fluidity and radical decay in human fibroblasts as detected by spin labeled stearic acids

Journal of Photochemistry and Photobiology B: Biology, 2004

The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a sourc... more The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a source of oxidative stress to cells via generation of reactive oxygen species. We report here some consequences of the UVA irradiation on cell membranes detected by electron paramagnetic resonance (EPR) spectroscopy. Paramagnetic nitroxide derivatives of stearic acid bearing the monitoring group at different depths in the hydrocarbon chain were incorporated into human fibroblasts membranes to analyze two main characteristics: kinetics of the nitroxide reduction and membrane fluidity. These two characteristics were compared for control and UVA-irradiated (0-250 kJ/m 2 ) cells. The term relative redox capacity (RRC) was introduced to characterize and to compare free radical reduction measured by EPR with some well-known viability/clonogenicity tests. Our results showed that UVA-irradiation produces a more rigid membrane structure, especially at higher doses. Furthermore, we found that trends agree in survival measured by neutral red (NR), trypan blue (TB), and clonogenic efficiency compared with RRC values measured by EPR for low and medium exposure doses. Above 100 kJ/m 2 , differences between these tests were observed. Antioxidant effect was modeled by a-tocopherolacetate treatment of the cells before UVA irradiation. While NR, TB and clonogenicity tests showed protection at the highest UVA doses (>100 kJ/m 2 ), results obtained with EPR measurements, both membrane fluidity and kinetics, or using MTT test did not exhibit this protective effect.

Log In