Influence of acute exercise on the osmotic stability of the human erythrocyte membrane.

This study evaluated the effects of 2 different types of acute aerobic exercise on the osmotic stability of human erythrocyte membrane and on different hematological and biochemical variables that are associated with this membrane property. The study population consisted of 20 healthy and active men. Participants performed single sessions of 2 types of exercise. The first session consisted of 60 min of moderate-intensity continuous exercise (MICE). The second session, executed a week later, consisted of high-intensity interval exercise (HIIE) until exhaustion. The osmotic stability of the erythrocyte membrane was represented by the inverse of the salt concentration (1/H50) at the midpoint of the sigmoidal curve of dependence between the absorbance of hemoglobin and the NaCl concentration. The values of 1/H50 changed from 2.29±0.1 to 2.33±0.09 after MICE and from 2.30±0.08 to 2.23±0.12 after HIIE. During MICE mean corpuscular volume increased, probably due to in vivo lysis of older erythrocytes, with preservation of cells that were larger and more resistant to in vitro lysis. The study showed that a single bout of acute exercise affected erythrocyte stability, which increased after MICE and decreased after HIIE.

Bivariate and multivariate analyses of the correlations between stability of the erythrocyte membrane, serum lipids and hematological variables.

The observation that the fluidity must remain within a critical interval, outside which the stability and functionality of the cell tends to decrease, shows that stability, fluidity and function are related and that the measure of erythrocyte stability allows inferences about the fluidity or functionality of these cells. This study determined the biochemical and hematological variables that are directly or indirectly related to erythrocyte stability in a population of 71 volunteers. Data were evaluated by bivariate and multivariate analysis. The erythrocyte stability showed a greater association with hematological variables than the biochemical variables. The RDW stands out for its strong correlation with the stability of erythrocyte membrane, without being heavily influenced by other factors. Regarding the biochemical variables, the erythrocyte stability was more sensitive to LDL-C. Erythrocyte stability was significantly associated with RDW and LDL-C. Thus, the level of LDL-C is a consistent link between stability and functionality, suggesting that a measure of stability could be more one indirect parameter for assessing the risk of degenerative processes associated with high levels of LDL-C.

Evolution of nutritional, hematologic and biochemical changes in obese women during 8 weeks after Roux-en-Y gastric bypasss.

Obesity is a chronic disease of multifactorial origin and currently is a serious public health problem. The treatment of morbid obesity can be effectively done by bariatric surgery. The present study aimed to evaluate the influence of changes in food intake on body composition and some hematologic and biochemical variables in the period of eight weeks after Roux-en-Y gastric bypass (RYGB). The study included 22 women submitted to RYGB. We evaluated anthropometric, nutritional, hematologic and biochemical variables before and 14, 28, 42 and 56 days after surgery. The patients showed a decrease in caloric intake and hence macro- and micronutrients, with significant loss of weight and decrease in body mass index (BMI). Decreases in body weight and BMI were associated with reduced blood levels of total cholesterol, VLDL-C, LDL-C, triglycerides and glucose with time after surgery. The decrease in caloric intake was also associated with decreased intake of protein, iron and calcium, with a decline in hemoglobin, hematocrit and red blood count, and RDW increased after surgery.

Influence of the albumin concentration and temperature on the lysis of human erythrocytes by sodium dodecyl sulfate.

The stability of human erythrocytes to sodium dodecyl sulfate (SDS) was assessed spectrophotometrically in the presence of different concentrations of bovine serum albumin (BSA) and at different temperatures (27-45 °C). The absorbance at 540 nm (A540) was correlated with the SDS concentration by sigmoidal regression based on the Boltzmann equation. Erythrocyte stability was characterized on the basis of the SDS concentration that induces hemolysis in 50% of the cells (D50). Progressive increases in the albumin concentration led to increases in the D50 value. The protective effect of BSA against SDS-induced hemolysis was attributed to the binding of the surfactant to the hydrophobic binding sites of this protein. The D50 values decreased sigmoidally with an increase in the temperature. This trend, which could not be explained by changes in the spectral properties of hemoglobin, maybe due to heterogeneity in the erythrocyte population.

Purification and biochemical characterization of Eumiliin from Euphorbia milii var. hislopii latex.

A protease, which we designate Eumiliin, was isolated from the latex of Euphorbia milii var. hislopii by a combination of ion-exchange chromatographic steps using DEAE-Sephacel and gel-filtration with Sephadex G-75. Eumiliin is a monomeric protein with an apparent molecular mass of 30 kDa by SDS-PAGE under reducing conditions and gave one main peak at 29,814 KDa in MALDI-TOF/TOF mass spectrometry. Eumiliin has caseinolytic and fibrinogenolytic activities, but no hemorrhagic or defibrinating activities. The enzyme readily hydrolyzes the Aalpha-chain of fibrinogen and, more slowly, the Bbeta-chain. Its fibrinogenolytic activity is inhibited by beta-mercaptoethanol and leupeptin. In contrast, EDTA and benzamidine did not affect the activity of Eumiliin. The caseinolytic activity of Eumiliin had a pH optimum of 8.0 and was stable in solution at up to 40 degrees C; activity was completely lost at >or=80 degrees C. Intraplantar injection of Eumiliin (1-25 microg/paw) caused a dose- and time-dependent hyperalgesia, which peaked 1-5h after enzyme injection. Intraplantar injection of Eumiliin (1-25 microg/paw) also caused an oedematogenic response that was maximal after 1h. Morphological analyses indicated that Eumiliin induced an intense myonecrosis, with visible leukocyte infiltrate and damaged muscle cells 24h after injection.

Dependence of the geriatric depression scores on age, nutritional status, and haematologic variables in elderly institutionalized patients.

OBJECTIVE: To evaluate the relationships between depression and ageing, nutrition, and selected haematologic variables. MEASUREMENTS: A cross-sectional study was performed in elderly institutionalized patients (n=100) of all nursing homes in the Brazilian city of Uberlandia, with determination of the Geriatric Depression Scale (GDS) and the Mini-Nutritional Assessment (MNA) scores, and selected haematologic variables. RESULTS: GDS had a significant negative dependence with the MNA for the entire institutionalized population. The prevalence of depression was higher among females, but significant correlations existed between GDS scores and erythrocytes counts, haemoglobin levels, or haematocrit values for the males only. However, a borderline correlation existed between GDS and the mean corpuscular volume (MCV) values in the females. CONCLUSIONS: Depression was associated with worsening of nutritional status and the degree of anemia of the entire elderly population and the male, but not the female subjects. The borderline correlation observed between the GDS and MCV for the female subjects suggests that the nutritional deficiencies responsible for the MCV increase are a cause, and not an effect, of depression.

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.

Effects of glycerol on the thermal dependence of the stability of human erythrocytes.

Incubation of human blood in saline solution of 0-36% (v/v) ethanol for 30 min produces lysis or stabilization of erythrocytes depending on the ethanol concentration. Under less elevated concentrations of ethanol, erythrocytes are present in expanded shapes (R state) that present lower stability and suffer lysis with increase in the ethanol concentration. Under more elevated concentrations of ethanol, erythrocytes are present in contracted shapes (T state) that have higher stability and suffer lysis at even more elevated ethanol concentrations. This work evaluated the effects of glycerol (0 to 2.0 M) and temperature (7 to 47 degrees C) on the stability of the R erythrocytes, characterized by the ethanol concentration at the mid-transition point (D (50R )) of the hemolysis curve (D (50R )). D (50R ) declined sigmoidally with increase in the glycerol concentration or temperature, due to transition of the R to the T state erythrocytes. In 1.5 M glycerol, the erythrocytes stability decreased below 32 but increased above 37 degrees C. The combination of temperature, glycerol and ethanol actions generates a critical value of osmotic pressure below which the R state predominates and above which the T state predominates. At 7 degrees C 1.5 M glycerol decreased the erythrocytes stability against ethanol but increased the erythrocytes stability against hypotonic shock. Those conditions favor the R state, which has a lower stability against ethanol; however, in the absence of ethanol, glycerol determines less water entrance in the erythrocytes, making more difficult its lysis by hypotonicity.

The substituent effect on complex formation between alpha-trypsin and para-substituted benzamidinium ions: a thermodynamic study.

1. Dissociation constants, Ki, were determined spectrophotometrically by measuring the absorbance at 410 nm, using N alpha-benzoyl-D,L-arginine-para-nitroanilide (Bz-D,L-Arg-Nan) as substrate. The Ki values for the complexes of alpha-trypsin with each of the para-derivatives of the benzamidinium ion -NH2, -CH3, -H, -F, -Cl, -Br, -COOEt, and -NO2 were measured at six temperatures (8, 15, 20, 25, 29 and 33 degrees C), in order to determine the thermodynamic parameters delta G0, delta H0, delta S0, and delta C0P for complex formation. 2. The standard enthalpy change (delta H0) was constant (-12.45 kcal/mol) and all other parameters were also negative. The large negative values obtained for the standard heat capacity change (delta C0P) suggest that the process occurs with a conformational adaptation in the enzyme structure. 3. The apparent partial specific volumes of free alpha-trypsin and alpha-trypsin bound to benzamidinium ion indicated that there is a decrease of approximately 0.10 cm3/g in the enzyme volume when the inhibitor binds. This contraction is consistent with the release of about 130 water molecules per enzyme molecule.