Libuša šikurová - Academia.edu (original) (raw)
Papers by Libuša šikurová
SPIE Proceedings, 1995
The fluorescence lifetimes of merocyanine 540 (MC 540) in ethanol, methanol, and suspensions of D... more The fluorescence lifetimes of merocyanine 540 (MC 540) in ethanol, methanol, and suspensions of DMPC and DPPC liposomes were studied using a laser-based time-correlated single photon counting system. Time-resolved fluorescence of MC 540 in methanol and ethanol can be analyzed with a single-exponential model, fluorescence decays of MC 540 in lecithin suspensions show biexponential behavior. We also present basic information about time-resolved fluorescence analysis software, designed and used by the authors as an integrated data station.
Cytometry, 2002
Platelet activation leads to the loss of a natural asymmetry of membrane phospholipids (PL) and t... more Platelet activation leads to the loss of a natural asymmetry of membrane phospholipids (PL) and the subsequent exposure of negatively charged PL in platelets with procoagulant activity that can be monitored routinely with annexin V (AN-V). Flow cytometric analysis of merocyanine 540 (MC540) binding may be the alternate choice for the monitoring of platelet procoagulant activity. Due to the increased partition of negatively charged phosphatidylserine (PS) in the membrane outer leaflet of activated platelets, the interaction with MC540 is reduced. Collagen, which facilitated platelet PL bilayer symmetrization, vastly reduced MC540 fluorescence and augmented AN-V binding to platelets. Such a collagen-induced symmetrization was further augmented in the presence of thrombin receptor-activating peptide (TRAP, SFLLRNPNDKYEPF). In the presence of VO(4) ((-3)) (the inhibitor of aminophospholipid translocase), the rebuilt of membrane asymmetry was attenuated, which resulted in further reduced MC540 fluorescence and enhanced AN-V binding in activated cells. In platelets incubated with thapsigargin, the inhibitor of platelet tubular system Ca(2+) ATP-ase, which elevates intraplatelet Ca(2+) concentration, TRAP increased AN-V and reduced MC540 binding. The chelating of Ca(2+) with EGTA outside of activated platelets reduced AN-V binding, but did not affect MC540-positive platelets. The fluctuations in reduced staining with MC540 paralleled enhanced AN-V binding (r = -0.481, P < 0.01), especially for strong "procoagulant" activating agents. (1) MC540 may be used in whole blood flow cytometry for the monitoring of platelet membrane symmetrization as an alternate or compounding method to AN-V. (2) Platelet staining with MC540 is sensitive to the fluctuations in the intraplatelet [Ca(2+)] during platelet activation. (3) Use of MC540 is characterized by improved diagnostic precision and reliability compared with AN-V.
Laser Study of Macroscopic Biosystems, 1993
ABSTRACT The influence of Nd/YAG laser irradiation (532 nm) on the MC-540 stained POPC and DMPC l... more ABSTRACT The influence of Nd/YAG laser irradiation (532 nm) on the MC-540 stained POPC and DMPC liposomes (lipid:dye ratio 42:1 - 20:1) was studied by absorption spectroscopy in the range of 380 - 700 nm. Two absorption bands (533 nm and 567 nm) corresponding to two colored species of the dye -- monomers and dimers -- were observed for MC-540 in phospholipid liposomes. MC-40 monomer-dimer distribution was shown to depend on the liposome composition and lipid:dye ratio. Irradiation of the samples by laser light of fluence rate 3000 W/m2 resulted only in MC-540 monomer-dimer distribution changes. The variation of this effect was observed as the kind of liposomes (alcoholic or ultrasonic) were changed. MC-540 monomer-dimer distribution is one of the factors that affect the dye- mediated photoinactivation. Illumination by intensive laser light (60,000 W/m2) caused color fading of the MC-540 dye.
Cellular & molecular biology letters, 2002
Merocyanine 540 is an anionic fluorescent probe which has a wide range of applications in biomemb... more Merocyanine 540 is an anionic fluorescent probe which has a wide range of applications in biomembrane research, having, as it does, a high affinity to the lipid phase of biological membranes. Thus, its interactions with model phospholipid membranes with defined structures are an important starting point in the quantification of its photophysical and photochemical characteristics. In this study, we used Langmuir type multilayers and liposomes composed of various phospholipids as model membrane systems. These systems were used for the determination of the difference in the electric dipole moments of MC 540 between the ground and first electronically excited states, for the determination of monomer-dimer distributions and equilibrium constants, for the evaluation of thermodynamic parameters (enthalpy and entropy changes) of the probe in a membrane, and for the estimation of effective values of dielectric permittivity of the probe s environment in membranes.
European Surgical Research, 1997
Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial ... more Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial function (EF) have reported conflicting results. We aimed to investigate the effects of supplementation with antioxidant vitamins C and E on EF and to explore factors that may provide explanations for the inconsistent results. We searched four databases (MEDLINE, Embase, Cochrane Library and Scopus) from inception until May 2014 for RCT involving adult participants aged $18 years who were supplemented with vitamins C and E alone or in combination for more than 2 weeks and reporting changes in EF measured using flow mediated dilation or forearm blood flow. Data were pooled as standardised mean difference (SMD) and analysed using a random-effects model. Significant improvements in EF were observed in trials supplementing with vitamin C alone (500-2000 mg/d) (SMD: 0•25, 95 % CI 0•02, 0•49, P¼0•043) and vitamin E alone (300-1800 IU/d; 1 IU vitamin E ¼ 0•67 mg natural vitamin E) (SMD: 0•48, 95 % CI 0•23, 0•72, P¼ 0•0001), whereas co-administration of both vitamins was ineffective (vitamin C: 500-2000 mg/d; vitamin E: 400-1200 IU/d) (SMD: 0•12, 95 % CI 20•18, 0•42, P¼0•428). The effect of vitamin C supplementation on EF increased significantly with age (b 0•023, 95 % CI 0•001, 0•05, P¼ 0•042). There was a significant negative correlation between baseline plasma vitamin E concentration and the effect of vitamin E supplementation on EF (b 2 0•03, 95 % CI 20•06, 2 0•001, P¼0•029). Supplementation with either vitamin C or vitamin E alone improves EF. However, subgroup analysis emphasises the importance of careful characterisation and selection of a population group which may benefit from such supplementation.
Chemical Physics, 2001
Solvent effects on the photophysical properties of Bu 4 N[(4,4′-bpy)Re(CO) 3 (bpy-5,5′-diCOO)] co... more Solvent effects on the photophysical properties of Bu 4 N[(4,4′-bpy)Re(CO) 3 (bpy-5,5′-diCOO)] complex. A combined experimental and computational study,
Biochimica et Biophysica Acta (BBA) - General Subjects, 2006
Hydrolysis of acetylsalicylic acid (ASA, aspirin), an antiplatelet drug commonly used in the prev... more Hydrolysis of acetylsalicylic acid (ASA, aspirin), an antiplatelet drug commonly used in the prevention of stroke and myocardial infarction, seems to play a crucial role in its pharmacological action. Thirty-eight healthy volunteers and 38 type 2 diabetic patients were enrolled to test the hypothesis that the enhanced plasma degradation and lowered bioavailability of ASA in diabetic patients is associated with the attenuation of platelet response. Aspirin esterase activities were tested at pH 7.4 and 5.5. A significantly higher overall aspirin esterase activity was noted at pH 7.4 in the diabetic patients (P b 0.003), corresponding to faster ASA hydrolysis (P b 0.006). This increased activity was attributable to butyrylcholinesterase and probably to albumin, because it was effectively inhibited by eserine and 4-bis-nitrophenyl phosphate (P b 0.01). No significant differences between control and diabetic subjects were found at pH 5.5 in either enzymatic activities or ASA hydrolysis rates. The enhanced plasma ASA degradation in diabetic subjects was significantly associated with the refractoriness of blood platelets to ASA (P b 0.05) and modulated by plasma cholesterol (P b 0.01). No direct effects of plasma pH or albumin were observed. In conclusion, higher aspirin esterase activity contributes to the lowered response of diabetic platelets to ASA-mediated antiplatelet therapy.
XXth International Congress of the ISTH, Sydney, Australia
Bratislavské lekárske listy, 2000
Non-enzymatic glycation, accompanied by the formation of free radicals, represents a serious prob... more Non-enzymatic glycation, accompanied by the formation of free radicals, represents a serious problem in diabetes mellitus. It is supposed to be the cause of the development of long-term diabetic complications. The aim of this work was to estimate the effect of treatment with vitamin C (1 g per day) and E (600 mg per day) on selected biochemical parameters as well as to determine the physicochemical state of erythrocyte membranes in diabetics. The paper also compares the physicochemical state of diabetic and control erythrocyte membranes. The changes in the values of glycaemia, glycated haemoglobin, and fructosamine were insignificant after three months of treatment. This points out that the doses used could be low or that the patient compliance was poor. An anionic fluorescent probe merocyanine 540 (MC540) was used to monitor possible changes in the physicochemical properties of isolated diabetic erythrocyte membranes. Significantly higher affinity of MC540 monomers to the membrane ...
Journal of Molecular and Cellular Cardiology, 2007
Physiological Research, 2012
Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are effective d... more Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are effective drugs in the treatment of hypercholesterolemia, however, their undesirable actions are not fully known. We investigated the effects of atorvastatin on the oxidative phosphorylation and membrane fluidity in liver mitochondria, and also on the coenzyme Q (CoQ) content in the mitochondria, liver tissue, and plasma of rats on a standard (C) and hypercholesterolemic (HCh) diet. Atorvastatin was administered at either low (10 mg kg-1) or high dose (80 mg kg-1) for four weeks. The high dose of the drug decreased the concentrations of total cholesterol and triacylglycerols in the plasma and liver of rats on a HCh diet. Administration of atorvastatin was associated with decreased oxygen uptake (state 3), and oxidative phosphorylation rate in the mitochondria of both C and HCh rats. Further, the drug influenced mitochondrial membrane fluidity and dose-dependently reduced concentrations of oxidized ...
Analytica Chimica Acta, 1995
General physiology and biophysics, 2000
Changes in the physico-chemical properties of erythrocyte membranes induced by nonenzymatic glyca... more Changes in the physico-chemical properties of erythrocyte membranes induced by nonenzymatic glycation as well as the possible prevention of their rise were studied. Using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH), fluorescence anisotropy values were determined in erythrocyte membranes isolated from type 1 and type 2 diabetic patients with and without complications. The mean anisotropy values for the groups of diabetic patients were significantly higher than those for the control group (p < 0.01). This indicated pathologically decreased fluidity in cell membranes in the diabetics regardless of the type of diabetes or the presence of complications. The fluorescence anisotropy positively correlated (p < 0.01) with clinical parameters, such as glycohaemoglobin and plasma cholesterol content, which are important for the monitoring of the compensation status of the diabetic patient. Our results support the suggestion that protein crosslinking and oxidative stress ind...
Canadian Journal of Physiology and Pharmacology, 2007
In this study, we report for the first time concurrent measurements of membrane potential and dyn... more In this study, we report for the first time concurrent measurements of membrane potential and dynamics and respiratory chain activities in rat heart mitochondria, as well as calcium transients in the hearts of rats in an early phase of streptozotocin diabetes, not yet accompanied with diabetes-induced complications. Quantitative relationships among these variables were assessed. The mitochondria from diabetic rats exhibited decreased fluorescence anisotropy values of diphenylhexatriene. This indicates that hydrophobic core of the membranes was more fluid compared with controls (p < 0.05). We discuss the changes in fluidity as having been associated with augmented energy transduction through the diabetic membranes. Reduced ratio of JC-1 fluorescence (aggregates to monomers) in the mitochondria from diabetic hearts reflected descendent transmembrane potential. A significant negative association between membrane fluidity and potential in the diabetic group was found (p < 0.05; r ...
Bladder cancer (BC) is the most common type of carcinoma of the urological system. Recently, ther... more Bladder cancer (BC) is the most common type of carcinoma of the urological system. Recently, there has been an increasing interest in non-invasive diagnostic tumor markers due to the invasive attribute of cystoscopy, which is still considered the gold standard diagnostic method. However, markers published in the literature so far do not meet expectations for replacing cystoscopy due to their low specificity and excessively high false-positive results, which can be mainly caused by frequently occurring hematuria also in benign cases. No reliable non-invasive method has yet been identified that can distinguish patients with bladder cancer and non-malignant hematuria patients. Our work examined the possibilities of non-targeted biomarkers of urine to distinguish patients with malignant and non-malignant diseases of the bladder using 3D HPLC in combination with computer processing of multiple datasets. Urine samples from 47 patients, 23 patients with bladder cancer (BC) and 24 patients ...
Physiol. Res, 2008
The aim of present study was to investigate functional and physical alterations in membranes of h... more The aim of present study was to investigate functional and physical alterations in membranes of heart mitochondria that are associated with remodeling of these organelles in acute phase of streptozotocin-induced diabetes and to elucidate the role of these changes in adaptation of the heart to acute streptozotocininduced diabetes (evaluated 8 days after single dose streptozotocin application to male Wistar rats). Action of free radicals on the respiratory chain of diabetic-heart mitochondria was manifested by 17 % increase (p<0.05) in oxidized form of the coenzyme Q 10 and resulted in a decrease of states S3 and S4 respiration, the respiratory control index, rate of phosphorylation (all p<0.01) and the mitochondrial transmembrane potential (p<0.05), but the ADP/O ratio decreased only moderately (p>0.05). On the contrary, membrane fluidity and the total mitochondrial Mg 2+-ATPase activity increased (both p<0.05). In diabetic heart mitochondria, linear regression analysis revealed a reciprocal relationship between the increase in membrane fluidity and decrease in trans-membrane potential (p<0.05, r = 0.67). Changes in membrane fluidity, transmembrane potential, Mg 2+-ATPase activity and the almost preserved ADP/O ratio appear as the manifestation of endogenous protective mechanisms participating in the functional remodeling of mitochondria which contributes to adaptation of the heart to diabetes.
SPIE Proceedings, 1995
The fluorescence lifetimes of merocyanine 540 (MC 540) in ethanol, methanol, and suspensions of D... more The fluorescence lifetimes of merocyanine 540 (MC 540) in ethanol, methanol, and suspensions of DMPC and DPPC liposomes were studied using a laser-based time-correlated single photon counting system. Time-resolved fluorescence of MC 540 in methanol and ethanol can be analyzed with a single-exponential model, fluorescence decays of MC 540 in lecithin suspensions show biexponential behavior. We also present basic information about time-resolved fluorescence analysis software, designed and used by the authors as an integrated data station.
Cytometry, 2002
Platelet activation leads to the loss of a natural asymmetry of membrane phospholipids (PL) and t... more Platelet activation leads to the loss of a natural asymmetry of membrane phospholipids (PL) and the subsequent exposure of negatively charged PL in platelets with procoagulant activity that can be monitored routinely with annexin V (AN-V). Flow cytometric analysis of merocyanine 540 (MC540) binding may be the alternate choice for the monitoring of platelet procoagulant activity. Due to the increased partition of negatively charged phosphatidylserine (PS) in the membrane outer leaflet of activated platelets, the interaction with MC540 is reduced. Collagen, which facilitated platelet PL bilayer symmetrization, vastly reduced MC540 fluorescence and augmented AN-V binding to platelets. Such a collagen-induced symmetrization was further augmented in the presence of thrombin receptor-activating peptide (TRAP, SFLLRNPNDKYEPF). In the presence of VO(4) ((-3)) (the inhibitor of aminophospholipid translocase), the rebuilt of membrane asymmetry was attenuated, which resulted in further reduced MC540 fluorescence and enhanced AN-V binding in activated cells. In platelets incubated with thapsigargin, the inhibitor of platelet tubular system Ca(2+) ATP-ase, which elevates intraplatelet Ca(2+) concentration, TRAP increased AN-V and reduced MC540 binding. The chelating of Ca(2+) with EGTA outside of activated platelets reduced AN-V binding, but did not affect MC540-positive platelets. The fluctuations in reduced staining with MC540 paralleled enhanced AN-V binding (r = -0.481, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01), especially for strong &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;procoagulant&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; activating agents. (1) MC540 may be used in whole blood flow cytometry for the monitoring of platelet membrane symmetrization as an alternate or compounding method to AN-V. (2) Platelet staining with MC540 is sensitive to the fluctuations in the intraplatelet [Ca(2+)] during platelet activation. (3) Use of MC540 is characterized by improved diagnostic precision and reliability compared with AN-V.
Laser Study of Macroscopic Biosystems, 1993
ABSTRACT The influence of Nd/YAG laser irradiation (532 nm) on the MC-540 stained POPC and DMPC l... more ABSTRACT The influence of Nd/YAG laser irradiation (532 nm) on the MC-540 stained POPC and DMPC liposomes (lipid:dye ratio 42:1 - 20:1) was studied by absorption spectroscopy in the range of 380 - 700 nm. Two absorption bands (533 nm and 567 nm) corresponding to two colored species of the dye -- monomers and dimers -- were observed for MC-540 in phospholipid liposomes. MC-40 monomer-dimer distribution was shown to depend on the liposome composition and lipid:dye ratio. Irradiation of the samples by laser light of fluence rate 3000 W/m2 resulted only in MC-540 monomer-dimer distribution changes. The variation of this effect was observed as the kind of liposomes (alcoholic or ultrasonic) were changed. MC-540 monomer-dimer distribution is one of the factors that affect the dye- mediated photoinactivation. Illumination by intensive laser light (60,000 W/m2) caused color fading of the MC-540 dye.
Cellular & molecular biology letters, 2002
Merocyanine 540 is an anionic fluorescent probe which has a wide range of applications in biomemb... more Merocyanine 540 is an anionic fluorescent probe which has a wide range of applications in biomembrane research, having, as it does, a high affinity to the lipid phase of biological membranes. Thus, its interactions with model phospholipid membranes with defined structures are an important starting point in the quantification of its photophysical and photochemical characteristics. In this study, we used Langmuir type multilayers and liposomes composed of various phospholipids as model membrane systems. These systems were used for the determination of the difference in the electric dipole moments of MC 540 between the ground and first electronically excited states, for the determination of monomer-dimer distributions and equilibrium constants, for the evaluation of thermodynamic parameters (enthalpy and entropy changes) of the probe in a membrane, and for the estimation of effective values of dielectric permittivity of the probe s environment in membranes.
European Surgical Research, 1997
Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial ... more Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial function (EF) have reported conflicting results. We aimed to investigate the effects of supplementation with antioxidant vitamins C and E on EF and to explore factors that may provide explanations for the inconsistent results. We searched four databases (MEDLINE, Embase, Cochrane Library and Scopus) from inception until May 2014 for RCT involving adult participants aged $18 years who were supplemented with vitamins C and E alone or in combination for more than 2 weeks and reporting changes in EF measured using flow mediated dilation or forearm blood flow. Data were pooled as standardised mean difference (SMD) and analysed using a random-effects model. Significant improvements in EF were observed in trials supplementing with vitamin C alone (500-2000 mg/d) (SMD: 0•25, 95 % CI 0•02, 0•49, P¼0•043) and vitamin E alone (300-1800 IU/d; 1 IU vitamin E ¼ 0•67 mg natural vitamin E) (SMD: 0•48, 95 % CI 0•23, 0•72, P¼ 0•0001), whereas co-administration of both vitamins was ineffective (vitamin C: 500-2000 mg/d; vitamin E: 400-1200 IU/d) (SMD: 0•12, 95 % CI 20•18, 0•42, P¼0•428). The effect of vitamin C supplementation on EF increased significantly with age (b 0•023, 95 % CI 0•001, 0•05, P¼ 0•042). There was a significant negative correlation between baseline plasma vitamin E concentration and the effect of vitamin E supplementation on EF (b 2 0•03, 95 % CI 20•06, 2 0•001, P¼0•029). Supplementation with either vitamin C or vitamin E alone improves EF. However, subgroup analysis emphasises the importance of careful characterisation and selection of a population group which may benefit from such supplementation.
Chemical Physics, 2001
Solvent effects on the photophysical properties of Bu 4 N[(4,4′-bpy)Re(CO) 3 (bpy-5,5′-diCOO)] co... more Solvent effects on the photophysical properties of Bu 4 N[(4,4′-bpy)Re(CO) 3 (bpy-5,5′-diCOO)] complex. A combined experimental and computational study,
Biochimica et Biophysica Acta (BBA) - General Subjects, 2006
Hydrolysis of acetylsalicylic acid (ASA, aspirin), an antiplatelet drug commonly used in the prev... more Hydrolysis of acetylsalicylic acid (ASA, aspirin), an antiplatelet drug commonly used in the prevention of stroke and myocardial infarction, seems to play a crucial role in its pharmacological action. Thirty-eight healthy volunteers and 38 type 2 diabetic patients were enrolled to test the hypothesis that the enhanced plasma degradation and lowered bioavailability of ASA in diabetic patients is associated with the attenuation of platelet response. Aspirin esterase activities were tested at pH 7.4 and 5.5. A significantly higher overall aspirin esterase activity was noted at pH 7.4 in the diabetic patients (P b 0.003), corresponding to faster ASA hydrolysis (P b 0.006). This increased activity was attributable to butyrylcholinesterase and probably to albumin, because it was effectively inhibited by eserine and 4-bis-nitrophenyl phosphate (P b 0.01). No significant differences between control and diabetic subjects were found at pH 5.5 in either enzymatic activities or ASA hydrolysis rates. The enhanced plasma ASA degradation in diabetic subjects was significantly associated with the refractoriness of blood platelets to ASA (P b 0.05) and modulated by plasma cholesterol (P b 0.01). No direct effects of plasma pH or albumin were observed. In conclusion, higher aspirin esterase activity contributes to the lowered response of diabetic platelets to ASA-mediated antiplatelet therapy.
XXth International Congress of the ISTH, Sydney, Australia
Bratislavské lekárske listy, 2000
Non-enzymatic glycation, accompanied by the formation of free radicals, represents a serious prob... more Non-enzymatic glycation, accompanied by the formation of free radicals, represents a serious problem in diabetes mellitus. It is supposed to be the cause of the development of long-term diabetic complications. The aim of this work was to estimate the effect of treatment with vitamin C (1 g per day) and E (600 mg per day) on selected biochemical parameters as well as to determine the physicochemical state of erythrocyte membranes in diabetics. The paper also compares the physicochemical state of diabetic and control erythrocyte membranes. The changes in the values of glycaemia, glycated haemoglobin, and fructosamine were insignificant after three months of treatment. This points out that the doses used could be low or that the patient compliance was poor. An anionic fluorescent probe merocyanine 540 (MC540) was used to monitor possible changes in the physicochemical properties of isolated diabetic erythrocyte membranes. Significantly higher affinity of MC540 monomers to the membrane ...
Journal of Molecular and Cellular Cardiology, 2007
Physiological Research, 2012
Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are effective d... more Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are effective drugs in the treatment of hypercholesterolemia, however, their undesirable actions are not fully known. We investigated the effects of atorvastatin on the oxidative phosphorylation and membrane fluidity in liver mitochondria, and also on the coenzyme Q (CoQ) content in the mitochondria, liver tissue, and plasma of rats on a standard (C) and hypercholesterolemic (HCh) diet. Atorvastatin was administered at either low (10 mg kg-1) or high dose (80 mg kg-1) for four weeks. The high dose of the drug decreased the concentrations of total cholesterol and triacylglycerols in the plasma and liver of rats on a HCh diet. Administration of atorvastatin was associated with decreased oxygen uptake (state 3), and oxidative phosphorylation rate in the mitochondria of both C and HCh rats. Further, the drug influenced mitochondrial membrane fluidity and dose-dependently reduced concentrations of oxidized ...
Analytica Chimica Acta, 1995
General physiology and biophysics, 2000
Changes in the physico-chemical properties of erythrocyte membranes induced by nonenzymatic glyca... more Changes in the physico-chemical properties of erythrocyte membranes induced by nonenzymatic glycation as well as the possible prevention of their rise were studied. Using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH), fluorescence anisotropy values were determined in erythrocyte membranes isolated from type 1 and type 2 diabetic patients with and without complications. The mean anisotropy values for the groups of diabetic patients were significantly higher than those for the control group (p < 0.01). This indicated pathologically decreased fluidity in cell membranes in the diabetics regardless of the type of diabetes or the presence of complications. The fluorescence anisotropy positively correlated (p < 0.01) with clinical parameters, such as glycohaemoglobin and plasma cholesterol content, which are important for the monitoring of the compensation status of the diabetic patient. Our results support the suggestion that protein crosslinking and oxidative stress ind...
Canadian Journal of Physiology and Pharmacology, 2007
In this study, we report for the first time concurrent measurements of membrane potential and dyn... more In this study, we report for the first time concurrent measurements of membrane potential and dynamics and respiratory chain activities in rat heart mitochondria, as well as calcium transients in the hearts of rats in an early phase of streptozotocin diabetes, not yet accompanied with diabetes-induced complications. Quantitative relationships among these variables were assessed. The mitochondria from diabetic rats exhibited decreased fluorescence anisotropy values of diphenylhexatriene. This indicates that hydrophobic core of the membranes was more fluid compared with controls (p < 0.05). We discuss the changes in fluidity as having been associated with augmented energy transduction through the diabetic membranes. Reduced ratio of JC-1 fluorescence (aggregates to monomers) in the mitochondria from diabetic hearts reflected descendent transmembrane potential. A significant negative association between membrane fluidity and potential in the diabetic group was found (p < 0.05; r ...
Bladder cancer (BC) is the most common type of carcinoma of the urological system. Recently, ther... more Bladder cancer (BC) is the most common type of carcinoma of the urological system. Recently, there has been an increasing interest in non-invasive diagnostic tumor markers due to the invasive attribute of cystoscopy, which is still considered the gold standard diagnostic method. However, markers published in the literature so far do not meet expectations for replacing cystoscopy due to their low specificity and excessively high false-positive results, which can be mainly caused by frequently occurring hematuria also in benign cases. No reliable non-invasive method has yet been identified that can distinguish patients with bladder cancer and non-malignant hematuria patients. Our work examined the possibilities of non-targeted biomarkers of urine to distinguish patients with malignant and non-malignant diseases of the bladder using 3D HPLC in combination with computer processing of multiple datasets. Urine samples from 47 patients, 23 patients with bladder cancer (BC) and 24 patients ...
Physiol. Res, 2008
The aim of present study was to investigate functional and physical alterations in membranes of h... more The aim of present study was to investigate functional and physical alterations in membranes of heart mitochondria that are associated with remodeling of these organelles in acute phase of streptozotocin-induced diabetes and to elucidate the role of these changes in adaptation of the heart to acute streptozotocininduced diabetes (evaluated 8 days after single dose streptozotocin application to male Wistar rats). Action of free radicals on the respiratory chain of diabetic-heart mitochondria was manifested by 17 % increase (p<0.05) in oxidized form of the coenzyme Q 10 and resulted in a decrease of states S3 and S4 respiration, the respiratory control index, rate of phosphorylation (all p<0.01) and the mitochondrial transmembrane potential (p<0.05), but the ADP/O ratio decreased only moderately (p>0.05). On the contrary, membrane fluidity and the total mitochondrial Mg 2+-ATPase activity increased (both p<0.05). In diabetic heart mitochondria, linear regression analysis revealed a reciprocal relationship between the increase in membrane fluidity and decrease in trans-membrane potential (p<0.05, r = 0.67). Changes in membrane fluidity, transmembrane potential, Mg 2+-ATPase activity and the almost preserved ADP/O ratio appear as the manifestation of endogenous protective mechanisms participating in the functional remodeling of mitochondria which contributes to adaptation of the heart to diabetes.