Incidence and clinical characteristics of Guillain-Barré syndrome in Osona (Barcelona, Spain), 2003-2016.

INTRODUCTION: According to most studies, the incidence of Guillain-Barré syndrome increases with age, with a peak incidence occurring between 70 and 80 years of age. The objective of this study is to describe the incidence (overall and by sex and age group) and clinical characteristics of Guillain-Barré syndrome in Osona (Barcelona, Spain). METHODS: We performed a retrospective, descriptive, population-based study covering the period 2003 to 2016. RESULTS: The global incidence of Guillain-Barré syndrome is 2.07 cases per 100000 person-years. Incidence increases with age, except for small peaks during childhood and between 40 and 50 years, and reaches a maximum of 6.26 cases per 100000 person-years above the age of 80. The incidences of the different variants were: AIDP, 72.1%; AMAN, 16.3%; ANSAN, 4.7%; and Miller Fisher syndrome, 4.7%. A total of 41.9% of patients had a history of respiratory tract infections, and 20.9% had a history of gastrointestinal infections. Protein in the cerebrospinal fluid was found in 76.7%. EMG findings suggested demyelination in 73.7% of the patients and axonal degeneration in 26.3%. A total of 20.9% of patients needed ventilatory support. Six-month mortality was 9.3%. Variables associated with worse prognosis were age over 80 years, delay in admission, previous gastrointestinal infection, and AMAN variant. CONCLUSIONS: The incidence observed in our study is in the upper range of estimated incidence rates reported in European and North American studies. The syndrome may be underdiagnosed in elderly patients; physicians must be vigilant to the possibility of the disease, which is associated with a high mortality rate if it is not treated early.

Inactivation of the pore-forming toxin Sticholysin I by peroxynitrite: protection by cys groups incorporated in the toxin.

Sea anemones synthesize a variety of toxic peptides and proteins of biological interest. The Caribbean Sea anemone Stichodactyla helianthus, produces two pore-forming toxins, Sticholysin I (St I) and Stichloysin II (St II), with the ability to form oligomeric pores in cell and lipid bilayers characteristically lacking cysteine in their amino acid sequences. Recently, two mutants of a recombinant variant of Sticholysin I (rSt I) have been obtained with a Cys residue in functionally relevant regions for the pore-forming activity of the toxin: r St I F15C (in the amino terminal sequence) and r St I R52C (in the binding site). Aiming at characterizing the effects of oxidants in toxins devoid (r St I) or containing -SH moieties (r St I F15C and r St I R52C), we measured their hemolytic activity and pore forming capacity prior and after their incubation with peroxynitrite (ONOO(-)). At low ONOO(-)/Toxin ratios, nearly 0.8 Trp groups are modified by each added peroxynitrite molecule, and the toxin activity is reduced in ca. 20 %. On the other hand, in -SH bearing mutants only 0.5 Trp groups are modified by each peroxynitrite molecule and the toxin activity is only reduced in 10 %. The results indicated that Cys is the initial target of the oxidative damage and that Trp residues in Cys-containing toxins were less damaged than those in r St I. This relative protection of Trp groups correlates with a smaller loss of hemolytic activity and permeabilization ability in liposomes and emphasizes the relevance of Trp groups in the pore forming capacity of the toxins.

Role of endogenous channels in red blood cells response to their exposure to the pore forming toxin Sticholysin II.

Sticholysin II (St II) is a highly hemolytic cytolysin isolated from the sea anemone Stichodactyla heliantus. The toxin hemolytic action takes place through the formation of channels that provoke an electrolyte unbalance leading to osmotic shock. The lytic event must involve the exchange of electrolytes and the entrance of water, leading to red blood cell disruption. These processes can occur through St II pores and/or the endogenous red blood cells transporters. In order to evaluate the contribution of these channels to water, anion and cation transport, we have measured the hemolysis and K+ efflux rates in the presence of several specific inhibitors. The results obtained in the presence of Hg, an AQP1 blocker, indicate that water transport through these channels is not essential for the occurrence of the lytic process induced by St II. The data also support a partial role of K+ and anion transporters. In particular, they are compatible with a preferential K+ efflux though the K(+)/Cl- co-transport as a response to the promoted swelling. Furthermore, they suggest that chloride influx, a process that can regulate both K+ efflux and lysis, is partially mediated by the endogenous cell transporters, in particular, band-3 anion exchange system being relevant at early stages of the lytic process.

Contribution of haemoglobin and membrane constituents modification to human erythrocyte damage promoted by peroxyl radicals of different charge and hydrophobicity.

We have investigated the influence of the free radical initiator characteristics on red blood cell lipid peroxidation, membrane protein modification, and haemoglobin oxidation. 2,2'-Azobis(2-amidinopropane) (AAPH) and 4,4'-azobis(4-cyanovaleric acid) (ACV) were employed as free radical sources. Both azo-compounds are water-soluble, although ACV presents a lowed hydrophilicity, evaluated from octanol/water partition constants. At physiological pH, they are a di-cation and a di-anion, respectively. AAPH and ACV readily oxidise purified oxyhemoglobin in a very efficient free radical-mediated process, particularly for ACV-derived radicals, where nearly one heme moiety was modified per radical introduced into the system, suggesting that negatively charged radicals react preferentially at the heme group. The radicals derived from both azo-compounds lead to different oxidation products. Methemoglobin, hemichromes and choleglobin were produced in AAPH-promoted hemoglobin oxidation, while ACV-derived radicals predominantly form hemichromes, with very low production of choleglobin. Red cell damage was evaluated at the level of hemoglobin and membrane constituents modification, and was expressed in terms of free radical doses. Before the onset of the lytic process, ACV leads to more lipid peroxidation than AAPH, and induces a moderate oxidation of intracellular Hb. This intracellular oxidation is markedly increased if ACV hydrophilicity is decreased by lowering the pH. On the other hand, AAPH-derived radicals are considerable more efficient in promoting protein band 3 modification and cell lysis, without significant intracellular hemoglobin oxidation. These results show that the lytic process is not triggered by lipid peroxidation or hemichrome formation, and suggest that membrane protein modification is the relevant factor leading to red blood cell lysis.

Free radical-induced protein degradation of erythrocyte membrane is influenced by the localization of radical generation.

We have investigated the role of the localization of free radical generation in erythrocyte membrane proteins degradation. The extracellular radical producer 2,2'-azobis(2-amidinopropane) hydrochloride induced a greater loss of band-3 protein in comparison with spectrin whereas the intracellular radical initiator cysteine induced the reverse effect. However, a large extent of main-chain fragmentation was observed for both proteins under the action of cysteine-derived radicals. The results show that the relative localization of the radical generation has an important influence on the degradation of specific proteins of the erythrocyte membrane.

Membrane lipid diffusion and band 3 protein changes in human erythrocytes due to acute hypobaric hypoxia.

Because it has been reported that hypoxia in rats may promote lipid peroxidation and other free radical reactions that could modify membrane lipids and proteins, the effect of acute hypobaric hypoxia on human erythrocyte membranes was investigated. 12-(1-Pyrene)dodecanoic acid fluorescent probe was used to assess short-range lateral diffusion status in the membrane bilayer. Membrane protein modification was detected by SDS-PAGE. Healthy young men were exposed for 20 min to the hypobaric hypoxia, simulating an altitude of 4,500 m. Under this condition, erythrocyte membrane lipids reached a state of higher lateral diffusivity with respect to normobaric conditions and membrane band 3 protein was modified, becoming more susceptible to membrane-bound proteinases. These observations suggest that acute hypobaric hypoxia may promote an oxidative stress condition in the erythrocyte membrane.

Protein degradation in red cells exposed to 2,2'-azo-bis(2-amidinopropane) derived radicals.

Extensive proteolysis is observed when red blood cells are exposed to free radicals produced in the thermolysis of 2,2'-azo-bis(2-amidinopropane). It is evaluated that nearly one amino terminal group is produced by each free radical introduced into the system. These groups are considered to arise mainly from band 3 fragmentation due to the action of red cell proteinases. Protein fragmentation takes place prior to significant hemolysis or lipid peroxidation, as evaluated by thiobarbituric acid-reactive substances measurements.

Thiol-induced hemoglobin oxidation.

Addition of cysteine in the mM range to purified oxyhemoglobin, red blood cell lysate or red blood cell suspensions leads to oxidation of the hemoprotein. The rate and extent of the process depend on the initial hemoglobin and cysteine concentrations, and the reaction is limited by the total destruction of the sulfhydryl groups. Similar results are obtained employing glutathione, but the rate of the process is considerably slower. Oxidation of the purified hemoprotein is faster than in the red blood cell lysate. This difference is mainly due to the inhibitory effect of catalase present in the lysate. Addition of sodium azide increases the rate of oxyhemoglobin oxidation in the lysate, while addition of catalase reduces the rate of oxidation of the purified hemoprotein. The results are interpreted in terms of a mechanism comprising the oxidation of the oxyhemoglobin by the -SH group, with concomitant formation of superoxide anion and hydrogen peroxide. These species further contribute to the oxyhemoglobin oxidation. A chain oxidation of the thiol, catalyzed by the hemoprotein, explains the extensive cysteine destruction.

Transbilayer asymmetry of pyrene mobility in human spherocytic red cell membranes.

The diffusion-dependent formation of pyrene excimers (excited dimers) was studied in normal and spherocytic red cell membranes. Pyrene emission was alternatively quenched in either bilayer half by non radiative energy transfer to haemoglobin. Pyrene excimer to monomer fluorescence intensity ratio, I'/I, was 0.35 +/- 0.03 (S.E.) in washed red blood cells obtained from normal donors (n = 8) and 0.45 + 0.03 (n = 13) in the corresponding isolated, haemoglobin-free resealed membranes (P less than 0.02). In the spherocytic condition the respective values were 0.28 +/- 0.01 (n = 9) and 0.53 +/- 0.03 (n = 9), P less than 0.001. In contrast to the decrease of I'/I in red cells as compared to isolated membranes, being 22% in normal cells and 47% in spherocytic ones, haemoglobin added to the exofacial side of isolated membranes, respectively, reduced I'/I by 18% and 5%. In normal red cell membranes, pyrene mobility appears to be higher in the inner monolayer than in the outer one. In spherocytic membranes our results indicate an enhanced transmembrane asymmetry in lipid monolayer fluidity, probably due to a defect of the membrane protein skeleton organization.

Actividade del sistema de defensa antoxidante y agresión oxidativa en eritrocitos de recién nacidos de bajo peso y distintas edades gestacionales / Activity of antioxidant defense system and oxidative stress in erythrocytes from low birth weight infants and different gestational ages

Se analizaron en este estudio muestras de sangre de cordón umbilical de 59 niños de bajo peso al nacer y distinta edad gestacional, obtenidas de la Maternidad del Hospital Paula Jaraquemada. No se encontraron diferencias significativas en la actividad de sueperóxido dismutasa, catalasa y glutatión peroxidasa en estos niños con respecto a edad gestacional y peso al nacer. Los eritrocitos de los niños de pretpermino tenían, sin embargo, un mayor nivel de malondialdehido (MDA) que los eritrocitos de los niños de término. Esto puede determinar que los eritrocitos están expuestos a distinta agresión oxidativia de acuerdo a la edad gestacional. Más estudios son necesarios para establecer una relación de estos resultados y el comportamiento fisiológico de los eritrocitos a distinta edad gestacional y la relación de estos hechos con la etiología de distintos tipos de anemia que sufren estos niños después de nacer