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Membrane skeleton is a structure that provides strength and elasticity to the erythrocyte membrane. This features stem from the main component of this structure, a multifunctional protein called spectrin. Spectrin forms a network underlying membrane bilayer containing integral membrane proteins which interact with multiple proteins and lipid partners. Although membrane skeleton and spectrin structure have been described before, the latest discoveries show their new details and properties. In this work we summarize recent findings concerning structure and function of spectrin together with its possible role in pathology. We focus our interest on lately published structural data and we make an attempt to combine these findings with possible physiological functions.

Trans-fatty acids (TFA) are formed during the industrial process of hydrogenation of vegetable oils. The consumption of hydrogenated fats has increased significantly over the last few decades. In Poland, the average daily intake of TFA for adults was estimated to be 2.8 to 6.9 g; which greatly exceeds the recommended daily maximum of 2 g/day (less than 1% of total energy intake). Increasing trans-fatty acid intake has detrimental effects on the lipid profile: TFA raise total cholesterol, LDL-cholesterol and triglyceride concentrations, and decrease HDL-cholesterol levels. Moreover, dietary trans-fatty acids may increase plasma levels of lipoprotein (a) and biomarkers of inflammation and endothelial dysfunction. Several studies have demonstrated that a high intake of TFA is associated with an increased risk of coronary heart disease. In addition, TFA consumption has been implicated as an independent risk factor for sudden cardiac arrest. It is therefore necessary to reduce the intake of hydrogenated fats rich in trans-fatty acids in order to minimize the adverse effects of TFA on health.

Unlabelled: The mechanism of functioning of the well-balanced protection system against free radicals is based on the mutual and synergistic activity of its all elements. One of the first organism reactions to physical effort is an elevated oxygen requirement due to an increased rate of metabolism, particularly in the skeletal muscles involved in performing physical work. In case of insufficient antioxidative system of blood plasma, free radicals attack the erythrocytic membrane externally and internally, leading to formation of considerable amounts of reactive oxygen species (ROS). The aim of this study was to evaluate the influence of dosed submaximal and maximal physical exercise on the plasma total antioxidant status (TAS) concentration in professional sportsmen and in subjects of normal physical activity., Material and Methods: 41 rugby players (junior and senior group) and 20 men of normal physical activity (control group) were the subject of the study. The plasma TAS concentration was determined: before an effort in the control group, and after 30-minute restitution period in sportsmen., Results: The concentration of TAS values in subjects of normal physical activity before exercises were on average 0.65 +/- 0.15 mmol/l. In the junior group after the dosed submaximal physical exercise, the mean TAS concentration was 0.69 +/- 0.29 mmol/l, but the dosed maximal exercise lead to an increase in TAS values - 0.73 +/- 0.34 mmol/l. The higher plasma TAS concentration after the dosed submaximal physical exercise was observed in the senior group as compared to the junior group, and was on average 0.93 +/- 0.22 mmol/l. However, after the maximal exercise, the TAS concentration decreased and its average value was 0.66 +/- 0.26 mmol/l., Conclusions: The results of the study indicate that the intensity of performed exercises affects the plasma TAS concentration during a single physical activity. The plasma TAS concentration was higher in sportsmen regardless of the type of effort as compared to the control group. Supplementation of micromolecular antioxidants present in nutrients ingested by the sportsmen might have influenced the study outcomes.

We examined the activity of sodium transporting systems (STS) in a cellular membrane of erythrocytes in a group of 21 patients under chronic hemodialysis treatment with the dialyzing fluid containing glucose HD-g(+), and 22 patients dialysed with the fluid not containing glucose HD-g(-), 21 patients with chronic kidney failure already not treated with dialysis and 21 control group. We examined the concentration of antioxidative system cofactors, such as zinc, copper and selenium in erythrocytes and plasma. The marker of oxidative stress in erythrocytes and plasma was the concentration of TBARS. Among all STS we examined the activity of Na(+)/K(+) ATP-ase, Na(+)/K(+)/Cl(-); co-transport, Na(+)/Li(+) exchanger, Na(+), K(+)-outflow. Copper zinc and selenium as cofactors of antioxidative enzymes may reflect the antioxidative processes inside the organism undergoing the influence of free radicals.

Unlabelled: The aim of the study was to estimate the effects of 4-weeks therapy of fluvastatin extended release (XL) on lipids serum, C-reactive protein (CRP), erythrocyte structure membrane (thiobarbituric acid reactive substances--TBARS concentrations, membrane cholesterol and the activity of Na+K(+)-ATPase in erythrocytes) in patients with hyperlipidemia without any clinical signs of atherosclerosis., Material and Methods: The study comprised 37 persons, including 15 healthy volunteers and 22 patients with hyperlipidemia (TC > 200 mg/dl, LDL-C > 130 mg/dl, TG < 400 mg/dl) treated with fluvastatin XL 80 mg/d. Before and after 4 weeks of active treatment the following parameters were determined: lipids (by enzymatic method using BioMerieux tests), CRP (by immunoturbidimetric method), TBARS concentrations (by method of Stock and Dormandy), membrane cholesterol (method of Ilcy), Na+K(+)-ATPase activity (method of Bartosz et al.)., Results: It was noticed significantly higher concentrations of CRP, TBARS, membrane cholesterol and lower activity of Na+K(+)-ATPase in erythrocytes of patients with hyperlipidemia than in the control group. Fluvastatin XL caused a significant decrease in serum TC (by 18%), LDL-C (by 24%), TG (by 16%), CRP (by 23%) and TBARS (by 31%), membrane cholesterol (by 30%) in comparison to the initial values before active therapy. The activity of Na+K(+)-ATPase didn't significantly change. The mean values of CRP, TBARS, membrane cholesterol level after active treatment are still higher than in the control group., Conclusion: The short-term treatment of fluvastatin extended release wasn't enough efficient to compensate disorders in erythrocyte membrane structure of patients with hyperlipidemia.

Unlabelled: The aim of the study was to compare the effects in vitro of pravastatin and quercetin on the structural parameters of erythrocyte membrane of patients with hypercholesterolemia type II., Material and Method: 2% suspensions of erythrocytes from hypercholesterolemic patients (n = 30, mean age 54.2 +/- 6.9) and healthy donors (n = 22, mean age 53.1 +/- 6.1) were incubated for 24 hours at 37 degrees C with or without pravastatin (9 microM, 90 microM), quercetin (10 microM, 50 microM, 100 microM). After the incubation we assessed, the cholesterol content (by method of Ilcy), the level of TBARS (by method of Stocks and Dormandy), the membrane fluidity (by paramagnetic resonance)., Results: In erythrocytes of patients (pts) with hypercholesterolemia type II (hip II) in comparison to the control group significantly higher mean values of membrane cholesterol content (0.065 +/- 0.013 vs 0.039 +/- 0.008AU, p < 0.001), the order parameter S (0.775 +/- 0.018 vs 0.752 +/- 0.018, p < 0.001) and TBARS level (2.91 +/- 1.01 vs 1.60 +/- 0.41 mmol/gHb, p < 0.001) were observed. After incubation of erythrocytes from hypercholesterolemic patients with pravastatin it was noticed the significant decrease (in dependence on statin concentration - 9 microM, 90 microM) of mean cholesterol content (by 23% and 37%, respectively) and the order parameter S (by 2% and 3%) in comparison the values after erythrocyte incubation without statin. Pravastatin didn't influence on the level of TBARS. After incubation with quercetin it was observed the significant decrease of membrane cholesterol (26-33%), the order parameter S (maximum by 4%) i TBARS levels (16-25%)., Conclusions: 1. Pravastatin and quercetin, in vitro, in similar degree decrease the level of membrane cholesterol and advantageously influence on membrane fluidity of erythrocytes from patients with hypercholesterolemia type II. 2. Pravastatin, in vitro, in opposite to quercetin doesn't influence on lipid peroxidation in erythrocytes of patients with hypercholesterolemia type II and healthy.

The oxidative stress accompanying chronic renal failure may cause a number of harmful changes in the organism of a human being. Hemodialysis, as one of the treatment methods of chronic renal failure, increases the oxidative stress, whose destructive activity is among other things manifested by changes in the lipid profile of the membranes of erythrocytes (RBC). Disturbances in the decomposition of membrane phospholipids are the causes of a lowered viability of red blood cells and an increased oligocytosis among hemodialysed patients. So far, reports do not, however, explain in a complex way the mechanism of how reactive oxygen species affect the functioning and the lipid profile of the cell membranes of erythrocytes. Besides, studies devoted to the mentioned problem provide contradictory results. It is being searched for new ways of decreasing the effects of the oxidative stress among patients with chronic illnesses in which free radicals are at the basis. One of the most frequently used methods of dialysis therapy is the usage of polysulfone membranes which to a great degree decrease the unwanted effects of hemodialysis. The information included in this work refer to data describing the effect of the oxidative stress in chronic renal failure, hemodialysis and preventive ways of decreasing the negative effects of an increased action of reactive oxygen species.

Unlabelled: The ageing process induces age-related involutionary changes and leads to increased occurrence of many diseases. One of the most important theories of ageing and development of many pathologies is the free radical theory, which assumes that ageing process leads to lost of oxidative balance., The Aim: of the research was to evaluate the degree of membrane lipid peroxidation, internal microviscosity, activity of membrane ATPase, both total and Na(+)K(+)-dependent, and markers of oxidative damage in erythrocyte membrane protein in elderly people., Material: The examination was performed on 35 people. The examined group (15 persons, mean age 71,3) consisted of healthy elderly people. The reference group was formed with younger healthy people (20 persons, mean age 55)., Results: Erythrocyte membrane lipid peroxidation was found stronger in the group of elderly people. Erythrocyte internal microviscosity was significantly higher in the elderly. The activity of ATPase, both total and Na(+)K(+)-dependent, appeared remarkably greater in the group of younger people. Stronger membrane lipid damage was observed in older age group, which may be implied by lower--SH group concentration, and higher W/S parameter value., Conclusion: The obtained results reveal that in elderly people the intensification of oxidative stress in the entire body occurs, which may be confirmed by structural and functional oxidative erythrocyte damage. This conclusion may be significant for pathogenesis of many diseases in this period of life.

Unlabelled: The lipid composition of erythrocyte membrane is in a state of dynamic equilibrium with plasma lipoproteins and reflects the processes taking place in extracellular environment. The recent studies were devoted to the phenomenon of modification of atherosclerosis development by statins. The aim of the study was evaluation of three statins: simvastatin, atorvastatin and pravastatin on plasma lipidogram and fluidity of erythrocytes membranes in patients (pts) with hyperlipidemia (hlp) type II., Investigated Group: the study comprised 114 pts, including 94 pts with hlp type II without concomitant chronic diseases and 20 healthy volunteers. Pts were qualified to treatment with statins if their LDL-cholesterol concentration (LDL-C) was above 170 mg/dL (4,1 mmol/L), total cholesterol (TC) > 250 mg/dL (6,5 mmol/L) and triglicerydes (TG) < 400 mg/dL (4,5 mmol/L). Pts were randomised to three groups: group I-n = 31 pts treated with atorvastatin (10 mg/d); group Il-n = 31 with simvastatin (20 mg/d), group III-n = 32 with pravastatin (20 mg/d)., Methods: after 4 and 12 weeks of active treatment the following parameters were determined: TC, HDL-C, TG (by enzymatic method using BioMerieux tests); LDL-C was calculated from the Friedewald formula and erythrocyte membranes fluidity by electron paramagnetic resonance with two spin labels (5-DSA, 16-DSA)., Results: During statin therapy significant decrease of TC, LDL-C, TG was observed, both after 4 and 12 weeks, as compared with initial values. All statins after 4 weeks of therapy caused a significant increase of membrane fluidity in its surface layer at carbon 5 depth. The values of parameter S after 12 weeks did not differ significantly from the values in the control group. The percent decrease of membrane microviscosity at carbon 5 depth did not correlate significantly with percent changes plasma TC and LDL-C. Atorvastatin appeared to be the strongest drug liquidizing erythrocytes membranes. There were no significant changes in fluidity of membrane in its deeper layers (at carbon 16 level)., Conclusion: Statins therapy was beneficial not only for modification of plasma lipids but caused the increase of erythrocytes membrane fluidity in the surface layer.

Recently many researchers have described the presence of insulin resistance and hyperinsulinemia in a substantial number of patients with essential hypertension. Reduced insulin binding to the receptors may play important role in development of insulin resistance in these patients. The study was aimed to assess the value of insulin binding to erythrocyte receptors in the patients with essential hypertension and compare to values in healthy persons. Additional purpose was the evaluation of insulin degradation by erythrocytes in patients with essential hypertension. 23 patients with essential hypertension (BMI 22.7 +/- 3.2) and 21 healthy persons (with BMI value 23.3 +/- 2.9) were studied. In all examined individuals the blood glucose and blood insulin concentrations were determined, insulin binding to erythrocyte receptors and insulin degradation by erythrocytes were measured by the method of Gambhir and al. Insulin concentration was significantly higher in patients with essential hypertension than in healthy subjects. We demonstrated a statistically significant positive correlation between body weight and insulin concentration in blood serum only in healthy people. Insulin binding to the receptors of red blood cells was significantly stronger (p < 0.001) in healthy persons than in patients with essential hypertension (0.972 +/- 0.395 pg 10(11) RBC and 0.446 +/- 0.14 pg 10(11) RBC respectively). In patients with hypertension insulin binding to receptors of red blood cells does not depend on body weight and insulin concentration in blood serum. Values of insulin degradation by erythrocyte in patients with essential hypertension and healthy persons were not significantly different. It seems that decreased insulin binding to insulin receptors is an important mechanism of insulin resistance patients with essential hypertension.

The major phospholipid classes of the human red blood cell membrane are: phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and sphingomyelin. These phospholipids are distributed asymmetrically across the two halves of the lipid bilayer. This asymmetry appears to be generated and maintained by an ATP-dependent translocation of aminophospholipids from outer to inner leaflet, and by the interaction of phospholipids with skeletal proteins. The phosphoinositides account for 3-4% of total erythrocyte membrane phospholipid. They play an important role in signal transduction and are involved in other various membrane functions.

The activity of Ca(++)-Mg++ ATP-ase present in erythrocyte membranes was determined in basal conditions and following stimulation with calmodulin in 8 women with insulin-dependent diabetes and in 9 healthy women. The isolation of erythrocyte membranes and the determination of activity of Ca(++)-Mg(++)-ATP-ase were carried out according to the method of Gietzen et al. A decrease in the activity of Ca(++)-Mg(++)-ATP-ase in basal conditions was found in fractions with the highest erythrocyte content obtained from diabetic patients. After stimulation with calmodulin the activity of Ca(++)-Mg(++)-ATP-ase in all the fractions was lower in diabetic patients than in the controls. Low activities of the enzyme were accompanied by high values of HbA1c. The results suggest that glycosylation of the ATP-ase or/and calmodulin may be the main cause of the observed fall in the enzyme activity in diabetes. Also the disturbances concerning the cumulation of intracellular calcium may be related to the changes caused by glycosylation of Ca(++)-Mg(++)-ATP-ase or/and calmodulin.

The aim of this paper was search for possible relationship between cholesterol and phospholipids in erythrocyte++ membrane and pathological entities i.e. hypertension and dyslipidemia. Both are the main risk factors of atherosclerosis and in both condition disturbances at the cell membrane level were detected. 124 persons (both men and women in a age group 20-59), employees of industrial enterprise were included into study. Standard questionnaire was performed as well as body weight and height, blood pressure, biochemical tests-lipids, cell membrane lipids serum and intracellular electrocytes as well as 24 h electrolyte urine excretion. The following findings were reported: cell membrane cholesterol concentration correlates with sex, age, body weight, systolic and diastolic blood pressure and triglycerydes HDL-cholesterol and serum phospholipids. The biggest influence on cholesterol concentration in cell membrane have the following factors: sex, age and serum triglycerides. The most important finding was that the lipid metabolism disturbances has impact on triglyceride elevation in serum and that arterial hypertension is connected with decreased cholesterol concentration in erytrocyte membrane.

The concentration of glycosylated hemoglobin and (plasma) proteins has been measured in 111 workers of 6 MZRiP departments in Płock and in 54 healthy people. In all subjects the mean concentrations of glycosylated hemoglobin and glycosylated plasma proteins have been in so called "wide range of normal values". Significant shifts of glycosylated Hb concentrations have been found in two departments--those of ethylenederivatives and distillation. The concentration of glycosylated plasma proteins has been elevated only in workers of the Catalytic Processes Department.