Relation between oxidative stress markers and antioxidant endogenous defences during exhaustive exercise

Hydrogen peroxide (H₂O₂) could induce oxidative damage at long distance from its generation site and it is also an important signalling molecule that induces some genes related to oxidative stress. Our objective was to study the plasma and blood cells capability to detoxify H₂O₂ after intense exercise and its correlation with oxidative damage. Blood samples were taken from nine professional cycling, participating in a mountain stage, under basal conditions and 3 h after the competition. Catalase and glutathione peroxidase activities decreased (40 and 50% respectively) in neutrophils after the cycling stage, while glutathione peroxidase increased (87%) in lymphocytes. Catalase protein levels and catalase specific activity maintained basal values after the stage in plasma. Catalase protein levels decreased (48%) in neutrophils and its specific activity increased up to plasma values after exercise. Myeloperoxidase (MPO) increased (39%) in neutrophils after the cycling stage. Exercise-induced hemolysis and lymphopenia inversely correlated with cellular markers of oxidative stress. Plasma malondialdehyde (MDA) directly correlated with neutrophil MPO activity and erythrocytes MDA. Intense exercise induces oxidative damage in blood cells as erythrocytes and lymphocytes, but not in neutrophils.     

Overlapping expression patterns of the multiligand endocytic receptors cubilin and megalin in the CNS, sensory organs and developing epithelia of the rodent embryo

Cubilin and megalin are multiligand epithelial endocytic receptors well characterized in the adult kidney and ileum where they form a complex essential for protein, lipid and vitamin uptake. Although inactivation of the megalin gene leads to holoprosencephaly and administration of anti-cubilin antibodies induces fetal resorptions or cranio-facial malformations their function in the developing embryo remains unclear. We recently showed that both proteins are strongly expressed by the maternal-fetal interfaces and the neuroepithelium of the early rodent embryo where they co-localize and form a complex important for nutrient uptake. The aim of the present study was the further investigation of cubilin expression at later developmental stages of the rodent embryo and its correlation to that of megalin. Immunohistochemical and in situ hybridization analysis showed striking similarities in the spatial and temporal expression patterns of cubilin and megalin. The electrophoretic mobility of both proteins was identical to that of the adult as revealed by Western blot analysis. Cubilin and megalin were strongly expressed in the sensory organs, the central nervous system, the respiratory and urogenital tracts as well as in the thymus, parathyroids and thyroid. In each site, the expression mainly concerned epithelial structures and correlated with the onset of epithelial induction. Depending on the site, a decreased or restricted expression was observed by the end of the gestation for both proteins.     

Enhanced or Reduced Fetal Growth Induced by Embryo Transfer into Smaller or Larger Breeds Alters Post-Natal Growth and Metabolism in Pre-Weaning Horses

In equids, placentation is diffuse and nutrient supply to the fetus is determined by uterine size. This correlates with maternal size and affects intra-uterine development and subsequent post-natal growth, as well as insulin sensitivity in the newborn. Long-term effects remain to be described. In this study, fetal growth was enhanced or restricted through ET using pony (P), saddlebred (S) and draft (D) horses. Control P-P (n = 21) and S-S (n = 28) pregnancies were obtained by AI. Enhanced and restricted pregnancies were obtained by transferring P or S embryos into D mares (P-D, n = 6 and S-D, n = 8) or S embryos into P mares (S-P, n = 6), respectively. Control and experimental foals were raised by their dams and recipient mothers, respectively. Weight gain, growth hormones and glucose homeostasis were investigated in the foals from birth to weaning. Fetal growth was enhanced in P-D and these foals remained consistently heavier, with reduced T₃ concentrations until weaning compared to P-P. P-D had lower fasting glucose from days 30 to 200 and higher insulin secretion than P-P after IVGTT on day 3. Euglycemic clamps in the immediate post-weaning period revealed no difference in insulin sensitivity between P-D and P-P. Fetal growth was restricted in S-P and these foals remained consistently lighter until weaning compared to S-D, with elevated T₃ concentrations in the newborn compared to S-S. S-P exhibited higher fasting glycemia than S-S and S-D from days 30 to 200. They had higher maximum increment in plasma glucose than S-D after IVGTT on day 3 and clamps on day 200 demonstrated higher insulin sensitivity compared to S-D. Neither the restricted nor the enhanced fetal environment affected IGF-1 concentrations. Thus, enhanced and restricted fetal and post-natal environments had combined effects that persisted until weaning. They induced different adaptive responses in post-natal glucose metabolism: an early insulin-resistance was induced in enhanced P-D, while S-P developed increased insulin sensitivity.     

Increased lymphocyte antioxidant defences in response to exhaustive exercise do not prevent oxidative damage

It has been reported that exercise induces oxidative stress and causes adaptations in antioxidant defences. The aim of this study was to determine the adaptations of lymphocytes to the oxidative stress induced by an exhaustive exercise. Nine voluntary male subjects participated in the study. The exercise was a cycling mountain stage (171.8 km), and the cyclists took a mean of 283 min to complete it. Blood samples were taken the morning of the cycling stage day, after overnight fasting, and 3 h after finishing the stage. We determined the blood glutathione redox status (GSSG/GSH), lymphocyte antioxidant enzyme activities and superoxide dismutase (SOD) levels; the plasma and lymphocyte vitamin E levels; the serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities and urate levels; the plasma carotene and malonaldehyde (MDA) levels; and the lymphocyte carbonyl index. The cycling stage induced significant increases in blood-oxidized (glutathione/GSSG), plasma MDA and serum urate levels. The exercise also produced increases in CK and LDH serum activities. The mountain cycling stage induced significant increases in lymphocyte vitamin E levels, glutathione peroxidase and glutathione reductase activities as well as increased SOD activity and protein levels. The protein carbonyl levels increased significantly in lymphocytes after the stage. In conclusion, in spite of increasing antioxidant defences in response to the oxidative stress induced by the exhaustive exercise, lymphocyte oxidative damage was produced after the stage as demonstrated by the increased carbonyl index even in very well trained athletes.     

Neutrophil tolerance to oxidative stress induced by hypoxia/reoxygenation

Repetitive episodes of hypoxia/reoxygenation induce cellular adaptations resulting in a tolerance process against oxidative stress. We studied the effects of chronic episodes of hypoxia/reoxygenation on neutrophil antioxidant defenses, neutrophil oxidative capability, and oxidative damage induced in neutrophils and plasma. Seven professional apnea divers participated in the study. Blood samples were taken under basal conditions, after a diving apnea session, and under basal conditions after five consecutive days of diving apnea sessions (basal post-diving). Chronic episodes of hypoxia/reoxygenation increased malondialdehyde (MDA), carbonyl derivates and creatine kinase (CPK) in plasma. Neutrophil catalase (CAT) levels were higher in basal post-diving. Neutrophil oxidative burst was maintained after diving, although the maximum response was delayed in basal post-diving. Neutrophil thioredoxin reductase (TR) activity increased in basal post-diving, and glutathione reductase (GR) activity was maintained. Chronic, repetitive episodes of diving apnea induce neutrophil adaptations in order to delay the oxidative burst response and to facilitate protein reduction. Diving apnea could be a good model to study tolerance to the oxidative stress generated by hypoxia/reoxygenation.     

Structure of the BgK-Kv1.1 complex based on distance restraints identified by double mutant cycles. Molecular basis for convergent evolution of Kv1 channel blockers

A structural model of BgK, a sea anemone toxin, complexed with the S5-S6 region of Kv1.1, a voltage-gated potassium channel, was determined by flexible docking under distance restraints identified by a double mutant cycles approach. This structure provides the molecular basis for identifying the major determinants of the BgK-Kv1.1 channel interactions involving the BgK dyad residues Lys(25) and Tyr(26). These interactions are (i) electrostatic interactions between the extremity of Lys(25) side chain and carbonyl oxygen atoms of residues from the channel selectivity filter that may be strengthened by solvent exclusion provided by (ii) hydrophobic interactions involving BgK residues Tyr(26) and Phe(6) and Kv1.1 residue Tyr(379) whose side chain protrudes in the channel vestibule. In other Kv1 channel-BgK complexes, these interactions are likely to be conserved, implicating both conserved and variable residues from the channels. The data suggest that the conservation in sea anemone and scorpion potassium channel blockers of a functional dyad composed of a lysine, and a hydrophobic residue reflects their use of convergent binding solutions based on a crucial interplay between these important conserved interactions.     

Key Role of the GITR/GITRLigand Pathway in the Development of Murine Autoimmune Diabetes: A Potential Therapeutic Target

Background

The cross-talk between pathogenic T lymphocytes and regulatory T cells (Tregs) plays a major role in the progression of autoimmune diseases. Our objective is to identify molecules and/or pathways involved in this interaction and representing potential targets for innovative therapies. Glucocorticoid-induced tumor necrosis factor receptor (GITR) and its ligand are key players in the T effector/Treg interaction. GITR is expressed at low levels on resting T cells and is significantly up-regulated upon activation. Constitutive high expression of GITR is detected only on Tregs. GITR interacts with its ligand mainly expressed on antigen presenting cells and endothelial cells. It has been suggested that GITR triggering activates effector T lymphocytes while inhibiting Tregs thus contributing to the amplification of immune responses. In this study, we examined the role of GITR/GITRLigand interaction in the progression of autoimmune diabetes.

Methods and Findings

Treatment of 10-day-old non-obese diabetic (NOD) mice, which spontaneously develop diabetes, with an agonistic GITR-specific antibody induced a significant acceleration of disease onset (80% at 12 weeks of age). This activity was not due to a decline in the numbers or functional capacity of CD4⁺CD25⁺Foxp3⁺ Tregs but rather to a major activation of ‘diabetogenic’ T cells. This conclusion was supported by results showing that anti-GITR antibody exacerbates diabetes also in CD28^−/− NOD mice, which lack Tregs. In addition, treatment of NOD mice, infused with the diabetogenic CD4⁺BDC2.5 T cell clone, with GITR-specific antibody substantially increased their migration, proliferation and activation within the pancreatic islets and draining lymph nodes. As a mirror image, blockade of the GITR/GITRLigand pathway using a neutralizing GITRLigand-specific antibody significantly protected from diabetes even at late stages of disease progression. Experiments using the BDC2.5 T cell transfer model suggested that the GITRLigand antibody acted by limiting the homing and proliferation of pathogenic T cells in pancreatic lymph nodes.

Conclusion

GITR triggering plays an important costimulatory role on diabetogenic T cells contributing to the development of autoimmune responses. Therefore, blockade of the GITR/GITRLigand pathway appears as a novel promising clinically oriented strategy as GITRLigand-specific antibody applied at an advanced stage of disease progression can prevent overt diabetes.     

Interaction of the prion protein fragment PrP 185–206 with biological membranes: effect on membrane permeability

Amyloids are proteinaceous aggregates related to the so‐called conformational diseases, such as Alzheimer's and prion diseases. The cytotoxicity of amyloids may be related to the interaction of the amiloidogenic peptides or proteins with the cell membrane. In order to gain information on the physico‐chemical effects of amyloids on membranes, we have studied the interaction of the human prion amyloidogenic fragment PrP 185–206 with negatively charged model membranes. The results show that the peptide causes the destabilization of the membrane, making it permeable to potassium ions and to charged organic compounds. This effect correlates with the interaction of the peptide with the membrane, causing a variation in the magnitude of the electrostatic surface and dipole membrane potentials. This effect on the electrostatic properties of the membranes may help explaining the observed permeability: a neutralization of the surface negative charge and a decrease of the inside‐positive dipole potential would facilitate the translocation of positive ions. The structural analysis of the peptide in the presence of model membranes reveals that it adopts a predominantly unordered structure without any signs of amyloid formation. The results may be relevant in relation to the recently described cell toxic capacity of the peptide. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

The impact of stroke on emotional intelligence

Background

Emotional intelligence (EI) is important for personal, social and career success and has been linked to the frontal anterior cingulate, insula and amygdala regions.

Aim

To ascertain which stroke lesion sites impair emotional intelligence and relation to current frontal assessment measurements.

Methods

One hundred consecutive, non aphasic, independently functioning patients post stroke were evaluated with the Bar-On emotional intelligence test, "known as the Emotional Quotient Inventory (EQ-i)" and frontal tests that included the Wisconsin Card Sorting Test (WCST) and Frontal Systems Behavioral Inventory (FRSBE) for correlational validity. The results of a screening, bedside frontal network syndrome test (FNS) and NIHSS to document neurological deficit were also recorded. Lesion location was determined by the Cerefy digital, coxial brain atlas.

Results

After exclusions (n = 8), patients tested (n = 92, mean age 50.1, CI: 52.9, 47.3 years) revealed that EQ-i scores were correlated (negatively) with all FRSBE T sub-scores (apathy, disinhibition, executive, total), with self-reported scores correlating better than family reported scores. Regression analysis revealed age and FRSBE total scores as the most influential variables. The WCST error percentage T score did not correlate with the EQ-i scores. Based on ANOVA, there were significant differences among the lesion sites with the lowest mean EQ-i scores associated with temporal (71.5) and frontal (87.3) lesions followed by subtentorial (91.7), subcortical gray (92.6) and white (95.2) matter, and the highest scores associated with parieto-occipital lesions (113.1).

Conclusions

1) Stroke impairs EI and is associated with apathy, disinhibition and executive functioning. 2) EI is associated with frontal, temporal, subcortical and subtentorial stroke syndromes.

     

A configuration space of homologous proteins conserving mutual information and allowing a phylogeny inference based on pair-wise Z-score probabilities

Background  

Popular methods to reconstruct molecular phylogenies are based on multiple sequence alignments, in which addition or removal of data may change the resulting tree topology. We have sought a representation of homologous proteins that would conserve the information of pair-wise sequence alignments, respect probabilistic properties of Z-scores (Monte Carlo methods applied to pair-wise comparisons) and be the basis for a novel method of consistent and stable phylogenetic reconstruction.