Phenotypic expression of homozygous hemoglobin S in relation to β-globin haplotypes, glutathione S-transferase polymorphisms and detoxification enzymes

Sickle cell anemia (SCA) shows a pathophysiology that involves multiple changes in sickle cell erythrocytes, vaso-occlusive episodes, hemolysis, activation of inflammatory mediators, endothelial cell dysfunction, and oxidative stress. These events complicate treatment and culminate in the development of manifestations such as anemia, pain crises and multiorgan dysfunction. The aim of this study was to evaluate, in SCA patients, oxidative stress and antioxidant capacity markers, correlating them to treatment with hydroxyurea (HU), β-globin haplotypes and glutathione S-transferase polymorphisms (GSTT1, GSTM1 and GSTP1), in comparison to a control group (CG). The study groups were composed of 48 individuals without hemoglobinopathies (CG), SCA patients treated with HU [AF (+HU), N = 13] and untreated SCA patients [AF (-HU), N = 15], after informed consent. The groups were analyzed using cytological, electrophoretic, chromatographic and molecular methods and information from medical records. The GSTM1 and GSTT1 polymorphisms were determined by multiplex PCR, while the GSTP1 polymorphism by PCR-RFLP. Biochemical parameters were measured using spectrophotometric methods [TBARS, TEAC and catalase (CAT) and GST activities] and a chromatographic method [glutathione (GSH)]. The fetal Hb (Hb F) levels observed in the SCA (+HU) group (10.9%) confirmed the already well-described pharmacological effect of HU, but the SCA (-HU) group also had high Hb F levels (6.1%), which may have been influenced by genetic factors not targeted in this study. We found a higher frequency of the Bantu haplotype (48.2%), followed by the Benin (32.1%) and also Cameroon haplotypes, rare in our population, and 19.7% of atypical haplotypes. The presence of Bantu haplotype was related to higher lipid peroxidation levels in patients, but also, it conferred a differential response to HU treatment, raising Hb F levels in 52.6% (P = 0.03). The protective effect of Hb F was confirmed, because the increase in their levels resulted in a 41.3% decrease in lipid peroxidation levels (r = -0.74, P = 0.0156). The genotypic frequency of the GST polymorphisms observed was similar to that of other studies in the Brazilian population, and its association with biochemical markers revealed a significant difference only for the GSTP1 polymorphism, where patients with genotype V/V showed higher GSH and TEAC levels (P = 0.04 and P = 0.03, respectively) compared to patients with genotype I/I. The TBARS levels were about five to eight times higher in the SCA (+HU) and SCA (-HU) groups, respectively, compared to controls, and HU produced a 35.2% decrease in lipid peroxidation levels in the SCA (+HU) group (P < 0.0001). Moreover, the SCA (+HU) group showed higher TEAC levels when compared to CG (P = 0.002). We did not find any significant difference in GST activity between the groups studied (P = 0.76), but CAT activity was about 17 and 30% lower in SCA (+HU) and SCA (-HU) groups, respectively (P < 0.00001). Plasma GSH levels were ~2 times higher in SCA patients than in the control group (P = 0.0005) and showed a positive correlation with TBARS levels, confirming its antioxidant function. HU treatment contributed to higher CAT activity and TEAC levels and lower lipid peroxidation, and its pharmacological effect showed a “haplotype-dependent” response. These findings may contribute to elucidating the potential of HU in ameliorating oxidative stress in SCA subjects.

Hemoglobin I-Philadelphia [alpha 16 (A14) LYS→GLU] heterozygote among blood donors from Brazil

We describe a heterozygous case of Hb I-Philadelphia [alpha 16 (A14) LYS-->GLU] in a blood donor from the Acre State Blood Bank, in the Brazilian Amazon region. We confirmed the mutation by electrophoretic and chromatographic methods and by DNA sequencing. A literature search showed that this is the first description of this alpha globin mutant in a Brazilian Caucasian group. We also emphasize the importance of the hemoglobin study in blood donors for the purpose of the genetic counseling and quality assurance of the blood to be transfused. Screening tests for hemoglobin mutants are also important for gathering anthropological information about the Brazilian population.

Hemoglobin patterns in different populations of Synbranchus marmoratus Bloch, 1795 (Pisces, Synbranchidae)

1. 1. Total hemolysates of Synbranchus marmoratus Bloch, 1795 captured at four different sites in the State of São Paulo, Brazil, showed two different hemoglobin phenotypes when submitted to agar-starch gel electrophoresis on glass slides in basic buffer. 2. 2. Phenotype I was characterized by 3 hemoglobin bands. When the total hemolysate was submitted to cellulose acetate electrophoresis in basic buffer containing 6 M urea and β-mercaptoethanol, Phenotype I showed four globins of the α 1, α 2, β and γ types, with 11.9 ± 1.9 g% total hemoglobin, 45.3 ± 3.6% globular volume, and 26.8 ± 4.4% mean corpuscular hemoglobin concentration (MCHC). 3. 3. Phenotype II showed three groups of hemoglobins, with a total of up to 12 hemoglobin bands. When the total hemolysate was submitted to cellulose acetate electrophoresis in basic buffer containing 6 M urea and β-mercaptoethanol, phenotype II showed five types of globins, denoted types α 1, α 2, γ 1, γ 2 and β, having electrophoretic positions different from those of Phenotype I globins, with 18.1 ± 3.3% total hemoglobin, 47.9 ± 6.4% globular volume, and 37.8 ± 4.4% MCHC. 4. 4. The distribution of the specimens having the two hemoglobin phenotypes is associated with the different geomorphological provinces of the State of São Paulo, suggesting the existence of at least two populational groups of Synbranchus marmoratus. © 1986.

Hemoglobin D-Punjab: origin, distribution and laboratory diagnosis

This review discusses hemoglobin D-Punjab, also known as hemoglobin D-Los Angeles, one of the most common hemoglobin variants worldwide. It is derived from a point mutation in the beta-globin gene (HBB: c.364G>C; rs33946267) prevalent in the Punjab region, Northwestern Indian. Hemoglobin D-Punjab can be inherited in heterozygosis with hemoglobin A causing no clinical or hematological alterations, or in homozygosis, the rarest form of inheritance, a condition that is commonly not related to clinical symptomatology. Moreover, this variant can exist in association with other hemoglobinopathies, such as thalassemias; the most noticeable clinical alterations occur when hemoglobin D-Punjab is associated to hemoglobin S. The clinical manifestations of this association can be similar to homozygosis for hemoglobin S. Although hemoglobin D-Punjab is a common variant globally with clinical importance especially in cases of double heterozygosis, hemoglobin S/D-Punjab is still understudied. In Brazil, for example, hemoglobin D-Punjab is the third most common hemoglobin variant. Thus, this paper summarizes information about the origin, geographic distribution, characterization and occurrence of hemoglobin D-Punjab haplotypes to try to improve our knowledge of this variant. Moreover, a list of the main techniques used in its identification is provided emphasizing the importance of complementary molecular analysis for accurate diagnosis.

The water effect on allosteric regulation of hemoglobin probed in water glucose and water glycine solutions

We have previously proposed a role of hydration in the allosteric control of hemoglobin based on the effect of varying concentrations of polyols and polyethers on the human hemoglobin oxygen affinity and on the solution water activity (Colombo, M. F., Rau, D. C., and Parsegian, V. A. (1992) Science 256, 655-659). Here, the original analyses are extended to test the possibility of concomitant solute and water allosteric binding and by introducing the bulk dielectric constant as a variable in our experiments. We present data which indicate that glycine and glucose influence HbA oxygen affinity to the same extent, despite the fact that glycine increases and glucose decreases the bulk dielectric constant of the solution. Furthermore, we derive an equation linking changes in oxygen affinity to changes in differential solute and water binding to test critically the possibility of neutral solute heterotropic binding. Applied to the data, these analyses support our original interpretation that neutral solutes act indirectly on the regulation of allosteric behavior of hemoglobin by varying the chemical potential of water in solution. This leads to a displacement of the equilibrium between Hb conformational states in proportion to their differential hydration.

Interaction of giant extracellular Glossoscolex paulistus hemoglobin (HbGp) with ionic surfactants: A MALDI-TOF-MS study

The giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) is constituted by approximately 144 subunits containing heme groups with molecular masses in the range of 16-19 kDa forming a monomer (d) and a trimer (abc), and around 36 non-heme structures, named linkers (L). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF-MS) analysis was performed recently, to obtain directly information on the molecular masses of the different subunits from HbGp in the oxy-form. This technique demonstrated structural similarity between HbGp and the widely studied hemoglobin of Lumbricus terrestris (HbLt). Indeed, two major isoforms (d(1) and d(2)) of identical proportions with masses of 16,355+/-25 and 16,428+/-24 Da, respectively, and two minor isoforms (d(3) and d(4)) with masses around 16.6 kDa were detected for monomer d of HbGp. In the present work, the effects of anionic sodium dodecyl sulfate (SDS) and cationic cethyltrimethyl ammonium chloride (CTAC) on the oligomeric structure of HbGp have been studied by MALDI-TOF-MS in order to evaluate the interaction between ionic surfactants and HbGp. The data obtained with this technique show an effective interaction of cationic surfactant CTAC with the two isoforms of monomer d, d(1) and d(2), both in the whole protein as well as in the pure isolated monomer. The results show that up to 10 molecules of CTAC are bound to each isoform of the monomer. Differently, the mass spectra obtained for SDS-HbGp system showed that the addition of the anionic surfactant SDS does not originate any mass increment of the monomeric subunits, indicating that SDS-HbGp interaction is, probably, significantly less effective as compared to CTAC-HbGp one. The acid pI of the protein around 5.5 is, probably, responsible for this behavior. The results of this work suggest also some interaction of both surfactants with linker chains as well as with trimers, as judged from observed mass increments. Our data are consistent with a recent spectroscopic study showing a strong interaction between CTAC and HbGp at physiological pH [P.S.Santiago, et al, Biochim. Biophys. Acta. 1770 (2007) 506-517.]. (C) 2007 Elsevier B.V. All rights reserved.

On the stability of the extracellular hemoglobin of Glossoscolex paulistus, in two iron oxidation states, in the presence of urea

The stability of the Glossoscolex paulistus hemoglobin (HbGp), in two iron oxidation states (and three forms), as monitored by optical absorption, fluorescence emission and circular dichroism (CD) spectroscopies, in the presence of the chaotropic agent urea, is studied. HbGp oligomeric dissociation, denaturation and iron oxidation are observed. CD data show that the cyanomet-HbGp is more stable than the oxy-form. Oxy- and cyanomet-HbGp show good fits on the basis of a two state model with critical urea concentrations at 220-222 nm of 5.1 +/- 0.2 and 6.1 +/- 0.1 mol/L, respectively. The three-state model was able to reveal a subtle second transition at lower urea concentration (1.0-2.0 mol/L) associated to partial oligomeric dissociation. The intermediate state for oxy- and cyanomet-HbGp is very similar to the native state. For met-HbGp, a different equilibrium, in the presence of urea, is observed. A sharp transition at 1.95 +/- 0.05 mol/L of denaturant is observed, associated to oligomeric dissociation and hemichrome formation. In this case, analysis by a three-state model reveals the great similarity between the intermediate and the unfolded states. Analysis of spectroscopic data, by two-state and three-state models, reveals consistency of obtained thermodynamic parameters for HbGp urea denaturation. (C) 2012 Elsevier Inc. All rights reserved.

Blood transfusions increase circulating plasma free hemoglobin levels and plasma nitric oxide consumption: a prospective observational pilot study

Introduction: The increasing number of reports on the relation between transfusion of stored red blood cells (RBCs) and adverse patient outcome has sparked an intense debate on the benefits and risks of blood transfusions. Meanwhile, the pathophysiological mechanisms underlying this postulated relation remain unclear. The development of hemolysis during storage might contribute to this mechanism by release of free hemoglobin (fHb), a potent nitric oxide (NO) scavenger, which may impair vasodilation and microcirculatory perfusion after transfusion. The objective of this prospective observational pilot study was to establish whether RBC transfusion results in increased circulating fHb levels and plasma NO consumption. In addition, the relation between increased fHb values and circulating haptoglobin, its natural scavenger, was studied. Methods: Thirty patients electively received 1 stored packed RBC unit (n = 8) or 2 stored packed RBC units (n = 22). Blood samples were drawn to analyze plasma levels of fHb, haptoglobin, and NO consumption prior to transfusion, and 15, 30, 60 and 120 minutes and 24 hours after transfusion. Differences were compared using Pearson's chi-square test or Fisher's exact test for dichotomous variables, or an independent-sample t test or Mann-Whitney U test for continuous data. Continuous, multiple-timepoint data were analyzed using repeated one-way analysis of variance or the Kruskall-Wallis test. Correlations were analyzed using Spearman or Pearson correlation. Results: Storage duration correlated significantly with fHb concentrations and NO consumption within the storage medium (r = 0.51, P < 0.001 and r = 0.62, P = 0.002). fHb also significantly correlated with NO consumption directly (r = 0.61, P = 0.002). Transfusion of 2 RBC units significantly increased circulating fHb and NO consumption in the recipient (P < 0.001 and P < 0.05, respectively), in contrast to transfusion of 1 stored RBC unit. Storage duration of the blood products did not correlate with changes in fHb and NO consumption in the recipient. In contrast, pre-transfusion recipient plasma haptoglobin levels inversely influenced post-transfusion fHb concentrations. Conclusion: These data suggest that RBC transfusion can significantly increase post-transfusion plasma fHb levels and plasma NO consumption in the recipient. This finding may contribute to the potential pathophysiological mechanism underlying the much-discussed adverse relation between blood transfusions and patient outcome. This observation may be of particular importance for patients with substantial transfusion requirements.

Role of glycated hemoglobin in the care of diabetes mellitus

Introduction: Persistently high glycemic levels are extremely harmful to the organism and can lead patients to several complications of diabetes mellitus. Glycated hemoglobin represents the glycemic levels for what patient is chronically exposed. Methods: Two virtual databases were surveyed in two languages: Portuguese and English. 12 articles were selected and reviewed. Results and discussion: The HbA1c is used since 1958 in the assessment of glycemic control in diabetic patients. It is formed by a chemical reaction between hemoglobin A and acarbohydrate. Each percentage point of glycated hemoglobin represents approximately 35mg/dL in patient's averageglycemia. Conclusion: The glycated hemoglobin should be measured at least twice per year in patients with diabetes in general. In case of change of hypoglycemic therapy, this frequency should be doubled.

Hb S-Sao Paulo: A new sickling hemoglobin with stable polymers and decreased oxygen affinity

Hb S-Sao Paulo (SP) [HBB:c.20A > T p.Glu6Val: c.196A > G p.Lys65Glu] is a new double-mutant hemoglobin that was found in heterozygosis in an 18-month-old Brazilian male with moderate anemia. It behaves like Hb S in acid electrophoresis, isoelectric focusing and solubility testing but shows different behavior in alkaline electrophoresis, cation-exchange HPLC and RP-HPLC. The variant is slightly unstable, showed reduced oxygen affinity and also appeared to form polymers more stable than the Hb S. Molecular dynamics simulation suggests that the polymerization is favored by interfacial electrostatic interactions. This provides a plausible explanation for some of the reported experimental observations. (C) 2012 Elsevier Inc. All rights reserved.

Purification and characterization of Hb 98-114: A novel hemoglobin-derived antimicrobial peptide from the midgut of Rhipicephalus (Boophilus) microplus

The antimicrobial activity of hemoglobin fragments (hemocidins) has been reported in a variety of models. The cattle tick Rhipicephalus (Boophilus) microplus is a blood sucking arthropod from where the first in vivo-generated hemocidin was characterized (Hb 33-61). In the present work we identified a novel antimicrobial peptide from the midgut of fully engorged R. (B.) microplus females, which comprises the amino acids 98-114 of the alpha subunit of bovine hemoglobin, and was designated Hb 98-114. This peptide was active against several yeast and filamentous fungi, although no activity was detected against bacteria up to 50 mu M of the synthetic peptide. Hb 98-114 was capable of permeabilizing Candida albicans cell membrane and had a fungicidal effect against this yeast. Circulardichroism (CD) and nuclear magnetic resonance (NMR) experiments showed that Hb 98-114 has a random conformation in aqueous solution but switches to an alpha-helical conformation in the presence of sodium dodecyl sulfate (SDS). This alpha helix adopts an amphipathic structure which may be the mechanism of cell membrane permeabilization. Importantly, Hb 98-114 may play an important role in defending the tick midgut against fungal pathogens and is the first hemocidin with specific antifungal activity to be characterized. (C) 2012 Elsevier Inc. All rights reserved.

Prediction of the rate of decline in fetal hemoglobin levels between first and second transfusions in red cell alloimmune disease

Objective To determine variables that predict the rate of decline in fetal hemoglobin levels in alloimmune disease. Method Retrospective review of singleton pregnancies that underwent first and second intrauterine transfusions for treatment of fetal anemia because of maternal Rh alloimmunization in a tertiary referral center. Results Forty-one first intrauterine transfusions were performed at 26.1?weeks (standard deviation, SD, 4.6), mean volume of blood transfused was 44.4?mL (SD 23.5) and estimated feto-placental volume expansion was 51.3% (SD 14.5%). Between first and second transfusion, hemoglobin levels reduced on average 0.40?g/dl/day (SD 0.25). Stepwise multiple regression analysis demonstrated that this rate significantly correlated with hemoglobin levels after the first transfusion, the interval between both procedures, and middle cerebral artery systolic velocity before the second transfusion. Conclusion The rate of decline in fetal hemoglobin levels between first and second transfusions in alloimmune disease can be predicted by a combination of hemoglobin levels after the first transfusion, interval between both procedures, and middle cerebral artery systolic velocity before the second transfusion. (C) 2012 John Wiley & Sons, Ltd.

On the temperature stability of extracellular hemoglobin of Glossoscolex paulistus, at different oxidation states: SAXS and DLS studies

Glossoscolex paulistus hemoglobin (HbGp) was studied by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). DLS melting curves were measured for met-HbGp at different concentrations. SAXS temperature studies were performed for oxy-, cyanomet- and met-HbGp forms, at several pH values. At pH 5.0 and 6.0, the scattering curves are identical from 20 to 60 degrees C, and R-g is 108 angstrom, independent of the oxidation form. At pH 7.0, protein denaturation and aggregation occurs above 55 degrees C and 60 degrees C, for oxy and met-HbGp, respectively. Cyanomet-HbGp, at pH 7.0, is stable up to 60 degrees C. At alkaline pH (8.0-9.0) and higher temperature, an irreversible dissociation process is observed, with a decrease of R-g, D-max and I(0). Analysis by p(r), obtained from GNOM, and OLIGOMER, was used to fit the SAXS experimental scattering curves by a combination of theoretical curves obtained for HbLt fragments from the crystal structure. Our results show clearly the increasing contribution of smaller molecular weight fragments, as a function of increasing pH and temperature, as well as, the order of thermal stabilities: cyanomet-> oxy- > met-HbGp. (C) 2012 Elsevier B.V. All rights reserved.