Basic Surface Properties of Mononuclear Cells from Didelphis marsupialis

The electrostatic surface charge and surface tension of mononuclear cells/monocytes obtained from young and adult marsupials (Didelphis marsupialis) were investigated by using cationized ferritin and colloidal iron hydroxyde, whole cell electrophoresis, and measurements of contact angles. Anionic sites were found distributed throughout the entire investigated cell surfaces. The results revealed that the anionic character of the cells is given by electrostatic charges corresponding to -18.8 mV (cells from young animals) and -29.3 mV (cells from adult animals). The surface electrostatic charge decreased from 10 to 65.2% after treatment of the cells with each one of trypsin, neuraminidase and phospholipase C. The hydrophobic nature of the mononuclear cell surfaces studied by using the contact angle method revealed that both young and adult cells possess cell surfaces of high hidrofilicity since the angles formed with drops of saline water were 42.5°and 40.8°, respectively. Treatment of the cells with trypsin or neuraminidase rendered their surfaces more hydrophobic, suggesting that sialic acid-containing glycoproteins are responsible for most of the hydrophilicity observed in the mononuclear cell surfaces from D. marsupialis.

Effects of physiological self-crowding of DNA on shape and biological properties of DNA molecules with various levels of supercoiling.

DNA in bacterial chromosomes and bacterial plasmids is supercoiled. DNA supercoiling is essential for DNA replication and gene regulation. However, the density of supercoiling in vivo is circa twice smaller than in deproteinized DNA molecules isolated from bacteria. What are then the specific advantages of reduced supercoiling density that is maintained in vivo? Using Brownian dynamics simulations and atomic force microscopy we show here that thanks to physiological DNA-DNA crowding DNA molecules with reduced supercoiling density are still sufficiently supercoiled to stimulate interaction between cis-regulatory elements. On the other hand, weak supercoiling permits DNA molecules to modulate their overall shape in response to physiological changes in DNA crowding. This plasticity of DNA shapes may have regulatory role and be important for the postreplicative spontaneous segregation of bacterial chromosomes.

Immunological and protective properties of novel malaria blood stage peptide antigens

ABSTRACT Malaria is a major worldwide public health problem, with transmission occurring throughout Africa, Asia, Oceania and Latin America. Over two billion people live in malarious areas of the world and it is estimated that 300-500 million cases and 1.5-2.7 million deaths occur annually. The increase in multi-drug resistant parasites and insecticide-resistant vectors has made the development of malaria vaccine a public health priority. The published genome offers tremendous opportunity for the identification of new antigens that can befast-tracked for vaccine development. We identified potential protein antigens present on the surface of asexual malaria blood stages through bioinformatics and published transcriptome and proteorné analysis. Amongst the proteins identified, we selected those that contain predicted a-helical coiled-coil regions, which are generally short and structurally stable as isolated fragments. Peptides were synthesized and used to immunize mice. Most peptides tested were immunogenic as demonstrated in ELISA assays, and induced antibodies of varying titres. In immunofluorescence assays, anti-sera from immunized mice reacted with native proteins expressed at different intraerythrocytic developmental stages of the parasite's cycle. In parallel in vitro ADCI functional studies, human antibodies affinity purified on some of these peptides inhibited parasite growth in association with monocytes in magnitudes similar to that seen in semiimmune African adults. Siudies using human immune sera taken from different malaria endemic regions, demonstrated that majority of peptides were recognized at high prevalence. 73 peptides were next tested in longitudinal studies in two cohorts separated in space and time in coastal Kenya. In these longitudinal analyses, antibody responses to peptides were sequentially examined in two cohorts of children at risk of clinical malaria in order to characterize the level of peptide recognition by age, and the role of anti-peptide antibodies in protection from clinical malaria. Ten peptides were associated ?with a significantly reduced odds ratio for an episode of clinical malaria in the first cohort of children and two of these peptides (LR146 and ÁS202.11) were associated with a significantly reduced odds ratio in both cohorts. This study has identified proteins PFB0145c and MAL6P1.37 among others as likely targets of protective antibodies. Our findings support further studies to systematically assess immunogenicity of peptides of interest in order to establish clear criteria for optimal design of potential vaccine constructs to be tested in clinical trials. RESUME La malaria est un problème de santé publique mondial principalement en Afrique, en Asie, en Océanie et en Amérique latine. Plus de 2 milliards de personnes vivent dans des régions endémiques et le nombre de cas par année est estimé entre 300 et 500 millions. 1.5 à 2.7 millions de décès surviennent annuellement dans ces zones. L'augmentation de la résistance aux médicaments et aux insecticides fait du développement d'un vaccin une priorité. Le séquençage complet du génome du parasite offre l'opportunité d'identifier de nouveaux antigènes qui peuvent rapidement mener au développement d'un vaccin. Des protéines antigéniques potentielles présentes à la surface des globules rouges infectés ont été identifiées par bioinformatique et par l'analyse du protéome et du transcriptome. Nous avons sélectionné, parmi ces protéines, celles contenant des motifs dits "a helical coiled-coil" qui sont généralement courts et structurellement stables. Ces régions ont été obtenues par synthèse peptidique et utilisées pour immuniser des souris. La plupart des peptides testés sont immunogéniques et induisent un titre variable d'anticorps déterminé par ELISA. Les résultats de tests d'immunofluorescence indiquent que les sera produits chez la souris reconnaissent les protéines natives exprimées aux différents stades de développement du parasite. En parallèle, des études d'ADCI in vitro montrent qué des anticorps humains purifiés à partir de ces peptides associés à des monocytes inhibent la croissance du parasite aussi bien que celle observée chez des adultes africains protégés. Des études d'antigénicité utilisant des sera de personnes protégées de différents âges vivant dans des régions endémiques montrent que la majorité des peptides sont reconnus avec une haute prévalence. 73 peptides ont été testés dans une étude longitudinale avec 2 cohortes de la côte du Kenya. Ces 2 groupes viennent de zones bien distinctes et les prélèvements n'ont pas été effectués pendant la même période. Dans cette étude, la réponse anticorps contre les peptides synthétiques a été testée dans les 2 cohortes d'enfants à risque de développer un épisode de malaria afin de caractériser le niveau de reconnaissance des peptides en fonction de l'âge et de déterminer le rôle des anticorps anti-peptides dans la protection contre la malaria. Parmi ces peptides, 10 sont associés à une réduction significative des risques de développer un épisode de malaria dans la première cohorte alors qu'un seul (LR146 et AS202.11) l'est dans les 2 cohortes. Cette étude a identifié, parmi d'autres, les protéines PFB0145c et MAL6P1.37 comme pouvant être la cible d'anticorps. Ces résultats sont en faveur de futures études qui évalueraient systématiquement l'immunogénicité des peptides d'intérêt dans le but d'établir des critères de sélection clairs pour le développement d'un vaccin. Résumé pour un large public La malaria est un problème de santé publique mondial principalement en Afrique, en Asie, en Océanie et en Amérique latine. Plus de 2 milliards de personnes vivent dans des régions endémiques et le nombre de cas par année est estimé entre 300 et 500 millions. 1.5 à 2.7 millions de décès surviennent annuellement dans ces zones. La résistance aux médicaments et aux insecticides augmente de plus en plus d'où la nécessité de développer un vaccin. Le séquençage complet du génome (ensemble des gènes) de P. falciparum a conduit au développement de nouvelles .études à large échelle dans le domaine des protéines du parasite (protéome) ; dans l'utilisation d'algorithmes, de techniques informatiques et statistiques pour l'analyse de données biologiques (bioinformatique) et dans les technologies de transcription et de profiles d'expression (transcriptome). Nous avons identifié, en utilisant les outils ci-dessus, des nouvelles protéines antigéniques qui sont présentes au stade sanguin de la malaria. Nous avons sélectionné, parmi ces protéines, celles contenant un motif dit "a-helical coiled-coil" qui sont des domaines impliqués dans un large éventail de fonctions biologiques. Des peptides représentant ces régions structurellement stables ont été synthétisés et utilisés pour immuniser des souris. La plupart des peptides testés sont immunogéniques et induisent un titre variable d'anticorps déterminé par ELISA. Les résultats de tests d'immunofluorescence indiquent que plusieurs sera de souris immunisées avec ces peptides reconnaissent les protéines natives exprimées à la surface des globules rouges infectés. En parallèle, des études d'ADCI in vitro montrent que des anticorps humains purifiés à partir de ces peptides en présence de monocytes inhibent la croissance du parasite de manière similaire à celle observée chez des adultes africains protégés. Des études d'antigénicité utilisant des sera de personnes immunes de différents âges (adultes et enfants) vivant dans des régions endémiques montrent que la majorité des peptides sont reconnus avec une haute prévalence. 73 peptides ont été testés dans des études épidémiologiques dans 2 villages côtiers du Kenya Ces 2 groupes vivent dans des zones bien distinctes et les prélèvements n'ont pas été effectués pendant la même période. Dans ces études, la réponse anticorps dirigée contre les peptides synthétiques a été testée en utilisant 467 échantillons sanguins d'enfants à risque de développer un épisode de malaria afin de caractériser le niveau de reconnaissance des peptides en fonction de l'âge et de déterminer le rôle des anticorps anti-peptides dans la protection contre la malaria cérébrale. Parmi ces peptides, 10 sont associés à une protection contre un épisode de malaria dans le premier village alors qu'un seul l'est dans les 2 villages. Ces résultats sont en faveur de futures études qui évalueraient systématiquement l'immunogénicité des peptides intéressants dans le but d'établir des critères de sélection clairs pour le développement d'un vaccin.

Imaging Properties of MS Lesions Correlate with Attention Deficits in Early Multiple Sclerosis

Introduction: Cognitive impairment affects 40-65% of multiple sclerosis (MS) patients, often since early stages of the disease (relapsing remitting MS, RRMS). Frequently affected functions are memory, attention or executive abilities but the most sensitive measure of cognitive deficits in early MS is the information processing speed (Amato, 2008). MRI has been extensively exploited to investigate the substrate of cognitive dysfunction in MS but the underlying physiopathological mechanisms remain unclear. White matter lesion load, whole-brain atrophy and cortical lesions' number play a role but correlations are in some cases modest (Rovaris, 2006; Calabrese, 2009). In this study, we aimed at characterizing and correlating the T1 relaxation times of cortical and sub-cortical lesions with cognitive deficits detected by neuropsychological tests in a group of very early RR MS patients. Methods: Ten female patients with very early RRMS (age: 31.6 ±4.7y; disease duration: 3.8 ±1.9y; EDSS disability score: 1.8 ±0.4) and 10 age- and gender-matched healthy volunteers (mean age: 31.2 ±5.8y) were included in the study. All participants underwent the following neuropsychological tests: Rao's Brief Repeatable Battery of Neuropsychological tests (BRB-N), Stockings of Cambridge, Trail Making Test (TMT, part A and B), Boston Naming Test, Hooper Visual Organization Test and copy of the Rey-Osterrieth Complex Figure. Within 2 weeks from neuropsychological assessment, participants underwent brain MRI at 3T (Magnetom Trio a Tim System, Siemens, Germany) using a 32-channel head coil. The imaging protocol included 3D sequences with 1x1x1.2 mm3 resolution and 256x256x160 matrix, except for axial 2D-FLAIR: -DIR (T2-weighted, suppressing both WM and CSF; Pouwels, 2006) -MPRAGE (T1-weighted; Mugler, 1991) -MP2RAGE (T1-weighted with T1 maps; Marques, 2010) -FLAIR SPACE (only for patient 4-10, T2-weighted; Mugler, 2001) -2D Axial FLAIR (0.9x0.9x2.5 mm3, 256x256x44 matrix). Lesions were identified by one experienced neurologist and radiologist using all contrasts, manually contoured and assigned to regional locations (cortical or sub-cortical). Lesion number, volume and T1 relaxation time were calculated for lesions in each contrast and in a merged mask representing the union of the lesions from all contrasts. T1 relaxation times of lesions were normalized with the mean T1 value in corresponding control regions of the healthy subjects. Statistical analysis was performed using GraphPad InStat software. Cognitive scores were compared between patients and controls with paired t-tests; p values ≤ 0.05 were considered significant. Spearmann correlation tests were performed between the cognitive tests, which differed significantly between patients and controls, and lesions' i) number ii) volume iii) T1 relaxation time iv) disease duration and v) years of study. Results: Cortical and sub-cortical lesions count, T1 values and volume are reported in Table 1 (A and B). All early RRMS patients showed cortical lesions (CLs) and the majority consisted of CLs type I (lesions with a cortical component extending to the sub-cortical tissue). The rest of cortical lesions were characterized as type II (intra-cortical lesions). No type III/IV lesions (large sub-pial lesions) were detected. RRMS patients were slightly less educated (13.5±2.5y vs. 16.3±1.8y of study, p=0.02) than the controls. Signs of cortical dysfunction (i.e. impaired learning, language, visuo-spatial skills or gnosis) were rare in all patients. However, patients showed on average lower scores on measures of visual attention and information processing speed (TMT-part A: p=0.01; TMT-part B: p=0.006; PASAT-included in the BRB-N: p=0.04). The T1 relaxation values of CLs type I negatively correlated with the TMT-part A score (r=0.78, p<0.01). The correlations of TMT-part B score and PASAT score with T1 relaxation time of lesions as well and the correlation between TMT-part A, TMT-part B and PASAT score with lesions' i) number ii) volume iii) disease duration and iv) years of study did not reach significance. In order to preclude possible influences from partial volume effects on the T1 values, the correlation between lesion volume and T1 value of CLs type I was calculated; no correlation was found, suggesting that partial volume effects did not affect the statistics. Conclusions: The present pilot study reports for the first time the presence and the T1 characteristics at 3 T of cortical lesions in very early RRMS (< 6 y disease duration). It also shows that CLS type I represents the most frequent cortical lesion type in this cohort of RRMS patients. In addition, it reveals a negative correlation between the attentional test TMT-part A and the T1 properties of cortical lesions type I. In other words, lower attention deficits are concomitant with longer T1-relaxation time in cortical lesions. In respect to this last finding, it could be speculated that long relaxation time correspond to a certain degree of tissue loss that is enough to stimulate compensatory mechanisms. This hypothesis is in line with previous fMRI studies showing functional compensatory mechanisms to help maintaining normal or sub-normal attention performances in RR MS patients (Penner, 2003).

On spectral properties of the modified convolution operator

Vegeu el resum a l'inici del document del fitxer adjunt.

Moduli of smoothness and growth properties of Fourier transforms: two-sided estimates

We prove two-sided inequalities between the integral moduli of smoothness of a function on R d[superscript] / T d[superscript] and the weighted tail-type integrals of its Fourier transform/series. Sharpness of obtained results in particular is given by the equivalence results for functions satisfying certain regular conditions. Applications include a quantitative form of the Riemann-Lebesgue lemma as well as several other questions in approximation theory and the theory of function spaces.

Arabidopsis NPH1: a flavoprotein with the properties of a photoreceptor for phototropism.

The NPH1 gene of Arabidopsis thaliana encodes a 120-kilodalton serine-threonine protein kinase hypothesized to function as a photoreceptor for phototropism. When expressed in insect cells, the NPH1 protein is phosphorylated in response to blue light irradiation. The biochemical and photochemical properties of the photosensitive protein reflect those of the native protein in microsomal membranes. Recombinant NPH1 noncovalently binds flavin mononucleotide, a likely chromophore for light-dependent autophosphorylation. The fluorescence excitation spectrum of the recombinant protein is similar to the action spectrum for phototropism, consistent with the conclusion that NPH1 is an autophosphorylating flavoprotein photoreceptor mediating phototropic responses in higher plants.

Enriched basaltic andesites from mid-crustal fractional crystallization, recharge, and assimilation (Pilavo Volcano, Western Cordillera of Ecuador)

The origin of andesite is an important issue in petrology because andesite is the main eruptive product at convergent margins, corresponds to the average crustal composition and is often associated with major Cu-Au mineralization. In this study we present petrographic, mineralogical, geochemical and isotopic data for basaltic andesites of the latest Pleistocene Pilavo volcano, one of the most frontal volcanoes of the Ecuadorian Quaternary arc, situated upon thick (30-50 km) mafic crust composed of accreted Cretaceous oceanic plateau rocks and overlying mafic to intermediate Late Cretaceous-Late Tertiary magmatic arcs. The Pilavo rocks are basaltic andesites (54-57 center dot 5 wt % SiO(2)) with a tholeiitic affinity as opposed to the typical calc-alkaline high-silica andesites and dacites (SiO(2) 59-66 wt %) of other frontal arc volcanoes of Ecuador (e.g. Pichincha, Pululahua). They have much higher incompatible element contents (e.g. Sr 650-1350 ppm, Ba 650-1800 ppm, Zr 100-225 ppm, Th 5-25 ppm, La 15-65 ppm) and Th/La ratios (0 center dot 28-0 center dot 36) than Pichincha and Pululahua, and more primitive Sr ((87)Sr/(86)Sr similar to 0 center dot 7038-0 center dot 7039) and Nd (epsilon(Nd) similar to +5 center dot 5 to +6 center dot 1) isotopic signatures. Pilavo andesites have geochemical affinities with modern and recent high-MgO andesites (e.g. low-silica adakites, Setouchi sanukites) and, especially, with Archean sanukitoids, for both of which incompatible element enrichments are believed to result from interactions of slab melts with peridotitic mantle. Petrographic, mineral chemistry, bulk-rock geochemical and isotopic data indicate that the Pilavo magmatic rocks have evolved through three main stages: (1) generation of a basaltic magma in the mantle wedge region by flux melting induced by slab-derived fluids (aqueous, supercritical or melts); (2) high-pressure differentiation of the basaltic melt (at the mantle-crust boundary or at lower crustal levels) through sustained fractionation of olivine and clinopyroxene, leading to hydrous, high-alumina basaltic andesite melts with a tholeiitic affinity, enriched in incompatible elements and strongly impoverished in Ni and Cr; (3) establishment of one or more mid-crustal magma storage reservoirs in which the magmas evolved through dominant amphibole and clinopyroxene (but no plagioclase) fractionation accompanied by assimilation of the modified plutonic roots of the arc and recharge by incoming batches of more primitive magma from depth. The latter process has resulted in strongly increasing incompatible element concentrations in the Pilavo basaltic andesites, coupled with slightly increasing crustal isotopic signatures and a shift towards a more calc-alkaline affinity. Our data show that, although ultimately originating from the slab, incompatible element abundances in arc andesites with primitive isotopic signatures can be significantly enhanced by intra-crustal processes within a thick juvenile mafic crust, thus providing an additional process for the generation of enriched andesites.

Specific mutations in the estrogen receptor change the properties of antiestrogens to full agonists.

The estrogen receptor (ER) stimulates transcription of target genes by means of its two transcriptional activation domains, AF-1 in the N-terminal part of the receptor and AF-2 in its ligand-binding domain. AF-2 activity is dependent upon a putative amphipathic alpha-helix between residues 538 and 552 in the mouse ER. Point mutagenesis of conserved hydrophobic residues within this region reduces estrogen-dependent transcriptional activation without affecting hormone and DNA binding significantly. Here we show that these mutations dramatically alter the pharmacology of estrogen antagonists. Both tamoxifen and ICI 164,384 behave as strong agonists in HeLa cells expressing the ER mutants. In contrast to the wild-type ER, the mutant receptors maintain nuclear localization and DNA-binding activity after ICI 164,384 treatment. Structural alterations in AF-2 caused by gene mutations such as those described herein or by estrogen-independent signaling pathways may account for the insensitivity of some breast cancers to tamoxifen treatment.

Quantifying network properties in multi-electrode recordings: spatiotemporal characterization and inter-trial variation of evoked gamma oscillations in mouse somatosensory cortex in vitro.

Linking the structural connectivity of brain circuits to their cooperative dynamics and emergent functions is a central aim of neuroscience research. Graph theory has recently been applied to study the structure-function relationship of networks, where dynamical similarity of different nodes has been turned into a "static" functional connection. However, the capability of the brain to adapt, learn and process external stimuli requires a constant dynamical functional rewiring between circuitries and cell assemblies. Hence, we must capture the changes of network functional connectivity over time. Multi-electrode array data present a unique challenge within this framework. We study the dynamics of gamma oscillations in acute slices of the somatosensory cortex from juvenile mice recorded by planar multi-electrode arrays. Bursts of gamma oscillatory activity lasting a few hundred milliseconds could be initiated only by brief trains of electrical stimulations applied at the deepest cortical layers and simultaneously delivered at multiple locations. Local field potentials were used to study the spatio-temporal properties and the instantaneous synchronization profile of the gamma oscillatory activity, combined with current source density (CSD) analysis. Pair-wise differences in the oscillation phase were used to determine the presence of instantaneous synchronization between the different sites of the circuitry during the oscillatory period. Despite variation in the duration of the oscillatory response over successive trials, they showed a constant average power, suggesting that the rate of expenditure of energy during the gamma bursts is consistent across repeated stimulations. Within each gamma burst, the functional connectivity map reflected the columnar organization of the neocortex. Over successive trials, an apparently random rearrangement of the functional connectivity was observed, with a more stable columnar than horizontal organization. This work reveals new features of evoked gamma oscillations in developing cortex.

Arterial properties in relation to genetic variations in the adducin subunits in a white population.

BACKGROUND: Adducin is a membrane skeleton protein, which consists of either alpha- and beta- or alpha- and gamma-subunits. We investigated whether arterial characteristics might be related to the genes encoding ADD1 (Gly460Trp-rs4961), ADD2 (C1797T-rs4984), and ADD3 (IVS11+386A>G-rs3731566). METHODS: We randomly recruited 1,126 Flemish subjects (mean age, 43.8 years; 50.3% women). Using a wall-tracking ultrasound system, we measured the properties of the carotid, femoral, and brachial arteries. We studied multivariate-adjusted phenotype-genotype associations, using a population- and family-based approach. RESULTS: In single-gene analyses, brachial diameter was 0.15 mm (P = 0.0022) larger, and brachial distensibility and cross-sectional compliance were 1.55 x 10(-3)/kPa (P = 0.013) and 0.017 mm(2)/kPa (P = 0.0029) lower in ADD3 AA than ADD3 GG homozygotes with an additive effect of the G allele. In multiple-gene analyses, the association of brachial diameter and distensibility with the ADD3 G allele occurred only in ADD1 GlyGly homozygotes. Otherwise, the associations between the arterial phenotypes in the three vascular beds and the ADD1 or ADD2 polymorphisms were not significant. In family-based analyses, the multivariate-adjusted heritability was 0.52, 0.38, and 0.30 for brachial diameter, distensibility, and cross-sectional compliance, respectively (P < 0.001). There was no evidence for population stratification (0.07 < or = P < or = 0.96). Transmission of the mutated ADD3 G allele was associated with smaller brachial diameter in 342 informative offspring (-0.12 +/- 0.04 mm; P = 0.0085) and in 209 offspring, who were ADD1 GlyGly homozygotes (-0.14 +/- 0.06 mm; P = 0.018). CONCLUSIONS: In ADD1 GlyGly homozygotes, the properties of the brachial artery are related to the ADD3 (A386G) polymorphism, but the underlying mechanism needs further clarification.