Biomedical subjects

Zbigniew Figaszewski

Publications and source records attributed to Zbigniew Figaszewski.

7 recordsLinked to original sources

PubMed2006

Parameters characterizing acid-base equilibria between cell membrane and solution and their application to monitoring the effect of various factors on the membrane.

The cell membrane is an extremely complicated object. It participates in a large number of equilibria. For this reason, it is impossible to determine the parameters of all of them. It is the purpose of this work to define a limited number of averaged parameters in order to describe the equilibria between cell membrane components and environmental components. These parameters are the total acidic functional group concentration as well as the basic group concentration and their association constants with hydrogen or hydroxyl ions. The parameters were determined using the pH dependence of the electric surface charge density. The usefulness of these parameters was checked by studying the effect of green tea on liver cells in ethanol poisoning. Ethanol provokes an increase in concentration of functional groups, positively and negatively charged, as well as an increase in the basic groups association constant and a decrease in acidic groups association constant. Administering green tea partly compensates the changes provoked by ethanol poisoning. The parameters proposed in this work, C(TA), C(TB), K(AH) and K(BOH), are suited for monitoring the changes caused by various factors.

Acid-Base Equilibrium↗

PubMed2005

Impedance analysis of phosphatidylcholine membranes modified with valinomycin.

The effect of the ion carrier valinomycin on the electrochemical features of the phosphatidylcholine membrane was investigated by electrochemical impedance spectroscopy. Phosphatidylcholine and valinomycin were chosen for the study because they fulfil essential functions in lively organisms. The experimental impedance values obtained in the presence of different amounts of carrier, studied with several potassium ion concentrations, were used for the research ability of valinomycin to form a 1:1 potassium ion complex on the lipid bilayer/electrolyte solution interface. Based on derived mathematical equations, the heterogeneous equilibrium constant (K (h)), association rate constant of the complex (k (R)) and dissociation rate constant of the complex (k (D)) were calculated. The result of the investigation is the proposal of a new method for the determination of the parameters used to describe the chemical reaction at the interface between a carrier molecule from the membrane and a monovalent ion from the aqueous phase.

Electric Capacitance↗

PubMed2005

Protective effect of green tea on erythrocyte membrane of different age rats intoxicated with ethanol.

It is known that aging is characterized by changes in cell metabolism resulting in modification of the structure and function of cell membrane components which is mainly the consequence of reactive oxygen species action. These disturbances are also enhanced by different xenobiotics, e.g. ethanol. Therefore, the aim of this paper is to examine green tea influence on total antioxidant status (TAS) and on composition and electric charge of erythrocyte membrane phospholipids in ethanol intoxicated rats of various ages. Antioxidant abilities of erythrocytes were estimated by measuring TAS. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC, while the extent of erythrocytes lipid peroxidation was estimated by HPLC measurement of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels. Electrophoresis was used to determine the surface charge density of the rat erythrocyte membrane. It was shown that the process of aging was accompanied by a decrease in TAS and in the total amount of phospholipids as well as by enhancement of lipid peroxidation and increase in surface charge density of erythrocyte membrane. Ethanol administration caused, in term, decrease in TAS and increase in the level of all phospholipids and lipid peroxidation products. Ethanol as well significantly enhanced changes in surface charge density of erythrocyte membrane. The ingestion of green tea partially prevented decrease in erythrocyte antioxidant abilities observed during aging and ethanol intoxication. Moreover, long-term drinking of green tea protects the structure of the erythrocytes membrane disturbed during aging process and/or chronic ethanol intoxication.

Aging↗

PubMed2005

Changes in electric charge and phospholipids composition in human colorectal cancer cells.

Cancer cells perform their malicious activities through own cell membranes that screen and transmit inhibitory and stimulatory signals out of the cells and into them. This work is focused on changes of phospholipids content (PI-phosphatidylinositol, PS-phosphatidylserine, PE-phosphatidylethanolamine, PC-phosphatidylcholine) and electric charge that occur in cell membranes of colorectal cancer of pT 3 stage, various grades (G2, G3) and without/with metastasis. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC (high-performance liquid chromatography). The surface charge density of colorectal cancer cell membranes was measured using electrophoresis. The measurements were carried out at various pH of solution. It was shown that the process of cancer transformation was accompanied by an increase in total amount of phospholipids as well as an increase in total positive charge at low pH and total negative charge at high pH. A malignant neoplasm cells with metastases are characterized by a higher PC/PE ratio than malignant neoplasm cells without metastases.

Chromatography, High Pressure Liquid↗

PubMed2004

Green tea modulation of the biochemical and electric properties of rat liver cells that were affected by ethanol and aging.

The oxidative stress induced by chronic ethanol consumption, particularly in concert with the aging process, has been implicated in changes in the structure and functions of liver cell components including membrane phospholipids. To counteract such changes, particularly those resulting from lipid peroxidation, antioxidants may be applied. Green tea contains large amounts of polyphenols, mainly catechins, which possess antioxidant properties. The aim of this study was to estimate the efficacy of green tea's influence on the physicochemical and biochemical properties of the rat liver as affected by the aging process and/or chronic ethanol intoxication. Several methods were used to evaluate this effect. Antioxidant properties were evaluated by vitamin E and antioxidant status determination. The liver trigliceride and cholesterol levels were also estimated. The extent of lipid peroxidation was determined by measuring the level of lipid peroxidation products as thiobarbituric reactive substances (TBARS). The surface charge density of the rat liver cells was measured using electrophoresis. The concentration of the marker enzymes of liver damage (alanine aminotransferase and aspartate aminotransferase) in the blood serum was also evaluated. Relative to the controls, aging was found to cause a decrease in the liver's antioxidant abilities and provoke an increase in the level of lipid peroxidation; it also increased the surface charge density of the rat liver cell membrane. Ethanol significantly aggravated these changes. This might have resulted in the liver cell membrane damage visible as a leak of alanine aminotransferase and aspartate aminotransferase into the blood. The ingestion of green tea with ethanol partially prevented these aging and/or ethanol-induced changes. Long-term drinking of green tea partially prevents the changes in the structure and function of the cell membrane caused by chronic ethanol intoxication.

Aging↗

PubMed2003

Impedance analysis of phosphatidylcholine membranes modified with gramicidin D.

Electrochemical impedance spectroscopy (EIS) was used to the study of gramicidin D (GD) dimerization and to transport of monovalent cations across lipid bilayers by the dimers. Phosphatidylcholine (PC) membranes were studied, unmodified and modified with very low GD concentrations in the presence of various potassium ion concentrations. A new method was proposed to determine the parameters used to describe the gramicidin dimer: gramicidin surface concentration (c(GG)), area occupied by individual channel (A(G)) and gramicidin dimerization equilibrium constant (K(GG)). It was shown that electrochemical impedance spectroscopy measurements of lipid bilayer membranes yielded the K(GG) and A(G) values of the same order of magnitude as other measurement techniques.

Dimerization↗

PubMed2002

Changes in physico-chemical properties of human large intestine tumour cells membrane.

Tumour cells produce and excrete to blood many substances which are present in the cell itself in trace amounts only. Our work has been aimed at the determination of changes in electric charge and in phospholipid composition of large intestine normal mucosa and colorectal cancer cells. Surface charge density of tumour unaffected mucosa and of tissue sections from tumours, was measured by electrophoresis. The measurements were carried out at various pH of solution. Membrane isoelectric point was determined by measuring its electric charge in function of pH as well as total positive charge at low pH and total negative charge at high pH. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC. Four phospholipid classes were identified: PI, PS, PE and PC and their surface concentrations were determined. The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized. The electric charge calculated from phospholipid concentrations is by three orders of magnitude higher than that determined electrophoretically. It indicates that the groups present in the membrane surface are involved in equilibria in which the charge is neutralized. Tumour changes provoke an increase in surface charge density of large intestine membrane, whereas the content of individual phospholipids increased or decreased depending on a patient.

Cell Membrane↗