Mario da Silva Garrote-Filho

Effects of glycerol and sorbitol on the thermal dependence of the lysis of human erythrocytes by ethanol.

In this work, the effects of 1 mol/L glycerol or sorbitol on the thermal dependence (27-47 degrees C) of the lysis of human erythrocytes by ethanol in saline solution (0.154 mol/L NaCl) have been evaluated. Lysis was monitored by measurement of the absorbance at 540 nm. Ethanol produced either lysis or protection against lysis depending on the conditions. These antagonistic effects are attributed to the existence of expanded (R) and compacted (T) erythrocytes, present under conditions of low and high osmolarity, respectively. The transitions of lysis of the R state and formation and lysis of the T state were all found to be sigmoidally defined. The ethanol concentration at the midpoint of the lysis transition of the R state (D(50R)) was found to decrease with increasing temperature and osmolarity. In the presence of glycerol or sorbitol, an increase in temperature led to smaller decreases in D(50R) and osmotic protection against lysis. The ethanol concentration at the midpoint of formation (S(50T)) and lysis (D(50T)) of the T state also decreased with increasing temperature and osmolarity. Lysis of R state erythrocytes is determined by the chaotropic action of ethanol, but the formation and lysis of T state erythrocytes are determined by osmotic pressure effects.

Efeito da composição do solvente sobre a estabilidade de proteínas em soluções aquosas

A protein presents a native (N) macro state, which is functionally active, in equilibrium with the denatured (D) macro state, which is devoid of biological activity. An ensemble of microstates forms each macrostate. The denatured state comprises a greater ensemble of microstates than the native macrostate. The N-D equilibrium can be affected by several factors, that comprise the purity of the water, temperature, pH and solute concentration. This work discusses the influence of osmolytes and chaotropics on the N-D equilibrium in aqueous solutions.

Influence of age on the correlations of hematological and biochemical variables with the stability of erythrocyte membrane in relation to sodium dodecyl sulfate

Abstract Objectives To evaluate the influence of age on the relationships between biochemical and hematological variables and stability of erythrocyte membrane in relation to the sodium dodecyl sulfate (SDS) in population of 105 female volunteers between 20 and 90 years. Methods The stability of RBC membrane was determined by non-linear regression of the dependency of the absorbance of hemoglobin released as a function of SDS concentration, represented by the half-transition point of the curve (D50) and the variation in the concentration of the detergent to promote lysis (dD). Results There was an age-dependent increase in the membrane stability in relation to SDS. Analyses by multiple linear regression showed that this stability increase is significantly related to the hematological variable red cell distribution width (RDW) and the biochemical variables blood albumin and cholesterol. Discussion The positive association between erythrocyte stability and RDW may reflect one possible mechanism involved in the clinical meaning of this hematological index.

Effects of acute and chronic exercise on the osmotic stability of erythrocyte membrane of competitive swimmers

This study aimed to evaluate the influence of acute and chronic exercise on erythrocyte membrane stability and various blood indices in a population consisting of five national-level male swimmers, over 18 weeks of training. The evaluations were made at the beginning and end of the 1st, 7th, 13th and 18th weeks, when volume and training intensity have changed. The effects manifested at the beginning of those weeks were considered due to chronic adaptations, while the effects observed at the end of the weeks were considered due to acute manifestations of the exercise load of that week. Acute changes resulting from the exercise comprised increases in creatine kinase activity (CK) and leukocyte count (Leu), and decrease in hematocrit (Ht) and mean corpuscular volume (MCV), at the end of the first week; increase in the activities of CK and lactate dehydrogenase (LDH), in the uric acid (UA) concentration and Leu count, at the end of the seventh week; increases in CK and LDH activities and in the mean corpuscular hemoglobin concentration (MCHC), at the end of the 13th week; and decrease in the value of the osmotic stability index 1/H50 and increases in the CK activity and platelets (Plt) count, at the end of the 18th week. Chronic changes due to training comprised increase in the values of 1/H50, CK, LDH, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), serum iron (Fe), MCV and Plt. Although acute training has resulted in decrease in the osmotic stability of erythrocytes, possibly associated with exacerbation of the oxidative processes during intense exercise, chronic training over 18 weeks resulted in increased osmotic stability of erythrocytes, possibly by modulation in the membrane cholesterol content by low and high density lipoproteins.

Influence of Erythrocyte Membrane Stability in Atherosclerosis

Purpose of ReviewThe purpose of this study is to show how an excess of cholesterol in the erythrocyte membrane contributes stochastically to the progression of atherosclerosis, leading to damage in blood rheology and O2 transport, deposition of cholesterol (from trapped erythrocytes) in an area of intraplaque hemorrhage, and local exacerbation of oxidative stress.Recent FindingsCholesterol contained in the membrane of erythrocytes trapped in an intraplaque hemorrhage contributes to the growth of the necrotic nucleus. There is even a relationship between the amount of cholesterol in the erythrocyte membrane and the severity of atherosclerosis. In addition, the volume variability among erythrocytes, measured by RDW, is predictive of a worsening of this disease.SummaryErythrocytes contribute to the development of atherosclerosis in several ways, especially when trapped in intraplate hemorrhage. These erythrocytes are oxidized and phagocytosed by macrophages. The cholesterol present in the membrane of these erythrocytes subsequently contributes to the growth of the atheroma plaque. In addition, when they rupture, erythrocytes release hemoglobin, which leads to the generation of free radicals. Finally, increased RDW may predict the worsening of atherosclerosis, due to the effects of inflammation and oxidative stress on erythropoiesis and erythrocyte volume. A better understanding of erythrocyte participation in atherosclerosis may contribute to the improvement of the prevention and treatment strategies of this disease.

Correlations of the glycemic variability with oxidative stress and erythrocytes membrane stability in patients with type 1 diabetes under intensive treatment

OBJECTIVES This study aimed to evaluate the correlations of glycemic variability with erythrocyte membrane stability parameters and oxidative stress markers in patients with type 1 diabetes mellitus (T1DM) under intensive treatment. MATERIAL AND METHODS 90 patients with T1DM and under intensive treatment of the disease were evaluated in relation to anthropometric indices, records of glycemic averages and parameters of glycemic variability, biochemical dosages (glucose, uric acid, lipidogram, glycated hemoglobin, microalbuminuria, creatinine and iron) reticulocyte count, erythrocyte membrane stability parameters and oxidative stress markers (thiobarbituric acid reactive substances, TBARS, and glutathione reductase, GR). RESULTS Indicators of glycemic variability in the short and long term showed correlations with parameters of membrane stability and markers of oxidative stress (GR). In addition, the comparison of these same parameters between the subgroups consisting of quartiles of GV or glycemic control also showed significant differences. CONCLUSION In the T1DM patients studied here, glycemic variability showed correlations with oxidative stress and erythrocyte membrane stability variables. This corroborates the hypothesis that glycemic fluctuations interfere with lipid peroxidation and cell membrane behavior, emphasizing its participation in mechanisms related to the development of chronic complications of diabetes.

Kinetics of hypotonic lysis of human erythrocytes

The curve of osmotic stability of erythrocytes is based on the amount of lysis as a function of salt concentration under fixed time incubation and represents an equilibrium situation after a sufficiently long time, although lysis is a rapid process. The curve is valid for the analysis of modulating agents that have influence on this equilibrium, but not for those that have influence on the lysis kinetics. This work has developed experimental conditions to study the hemolysis kinetics based on the interruption of lysis by hypertonicity at predetermined intervals of time. These conditions were used to evaluate the kinetics of hemolysis of 17 volunteers. The lysis curve as a function of time was statistically fitted to a hyperbola, using the analytical routine of the integrated kinetic model of Michaelis–Menten to determine the time required to promote lysis of half of the population of erythrocytes (t1/2) and the maximum absorbance (Amax) reached in the test. The results showed good variance among volunteers. The constant t1/2 was negatively correlated with total and LDL-cholesterol, and Amax, as it was expected, showed significant associations with hematological variables that are under the influence of hemoglobin levels. Stratification of the study population into two age groups (18–30 and 40–90 years old) showed that the t1/2 values were significantly lower in the older population. Although the study population has been small, the study showed that this kinetic approach of the erythrocyte lysis is very promising for analyzing the myriad of variables which have influence on the cell membrane.

Influence of the use of testosterone associated with physical training on some hematologic and physical parameters in older rats with alloxan-induced diabetes

Objective This study investigated the possible blood changes in wistar rats elderly with and without treatment with anabolic steroids submitted physical training. Materials and methods Elderly rats (32) were divided into four groups: normal (N), treated normal (NT), diabetic (D) and treated diabetic (DT). They were submitted to 20 sessions of swimming with overload (5% body weight), 40 min/day for four weeks. The NT and DT groups received application of testosterone twice a week. At the end of the sessions, the animals were subjected to swimming until exhaustion and then killed for removal of blood and visceral fat. We evaluated maximum swim time, weight of visceral fat, erythrogram, leukogram, lipidogram and serum levels of glucose, lactate, aspartate aminotransferase and creatine kinase. The results were compared using one-way ANOVA followed by the post hoc Tukey test. Results In elderly diabetic rats, the use of anabolic associated with physical training in older rats resulted in improvement in erythrogram, lipidogram and physical performance for high-intensity aerobic exercise. However, it was related to changes in leukocyte count, probably associated with inflammation. Conclusion The combination of the use of testosterone with physical training, followed by maximal effort test caused changes hematological and biochemical can be associated with improvement in physiological characteristics, with increase of the swimming time and decrease of visceral fat levels, improvement in aerobic metabolism of fatty acids and glucose in normal and diabetic animals.