Injúrias mecânicas e seus efeitos na qualidade de mamões golden

O objetivo do trabalho foi identificar as injúrias mecânicas que ocorrem em mamões 'Golden' e avaliar seus efeitos na qualidade dos frutos armazenados a 22ºC e 85% UR durante 10 dias. As injúrias identificadas como abrasão, corte e amassado foram reproduzidas nos frutos. As abrasões foram provocadas com lixa grão 200, numa área de 6cm². Os cortes foram realizados com incisões de 30 mm de comprimento e 5 mm de profundidade. O amassado foi provocado pelo impacto dos frutos, que foram deixados cair de uma altura de 2 m. Cada fruto recebeu 2 injúrias em lados opostos, na região de maior diâmetro. Mamões intactos foram utilizados como controle. A região danificada pela abrasão não desenvolveu cor amarelo-alaranjada; ocorreu escurecimento da casca, comprovado pelos menores valores de luminosidade e cromaticidade. Abrasão e impacto levaram a maior redução da firmeza da polpa e perda de massa. Imagens de ressonância magnética revelaram que frutos danificados pelas injúrias perderam sua integridade, o que foi identificado por áreas claras devido à presença de água livre. A qualidade de mamões 'Golden' é prejudicada por injúrias mecânicas, principalmente pelo impacto pela abrasão.

Protein oligomers studied by solid-state NMR the case of the full-length nucleoid-associated protein histone-like nucleoid structuring protein

Members of the histone-like nucleoid structuring protein (H-NS) family play roles both as architectural proteins and as modulators of gene expression in Gram-negative bacteria. The H-NS protein participates in modulatory processes that respond to environmental changes in osmolarity, pH, or temperature. H-NS oligomerization is essential for its activity. Structural models of different truncated forms are available. However, high-resolution structural details of full-length H-NS and its DNA-bound state have largely remained elusive. We report on progress in characterizing the biologically active H-NS oligomers with solid-state NMR. We compared uniformly ((13)C,(15)N)-labeled ssNMR preparations of the isolated N-terminal region (H-NS 1-47) and full-length H-NS (H-NS 1-137). In both cases, we obtained ssNMR spectra of good quality and characteristic of well-folded proteins. Analysis of the results of 2D and 3D (13)C-(13)C and (15)N-(13)C correlation experiments conducted at high magnetic field led to assignments of residues located in different topological regions of the free full-length H-NS. These findings confirm that the structure of the N-terminal dimerization domain is conserved in the oligomeric full-length protein. Small changes in the dimerization interface suggested by localized chemical shift variations between solution and solid-state spectra may be relevant for DNA recoginition.

Brain functional abnormality in schizo-affective disorder: an fMRI study.

Background.Schizo-affective disorder has not been studied to any significant extent using functional imaging. The aim of this study was to examine patterns of brain activation and deactivation in patients meeting strict diagnostic criteria for the disorder. METHOD: Thirty-two patients meeting research diagnostic criteria (RDC) for schizo-affective disorder (16 schizomanic and 16 schizodepressive) and 32 matched healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups. RESULTS: Controls showed activation in a network of frontal and other areas and also deactivation in the medial frontal cortex, the precuneus and the parietal cortex. Schizo-affective patients activated significantly less in prefrontal, parietal and temporal regions than the controls, and also showed failure of deactivation in the medial frontal cortex. When task performance was controlled for, the reduced activation in the dorsolateral prefrontal cortex (DLPFC) and the failure of deactivation of the medial frontal cortex remained significant. CONCLUSIONS: Schizo-affective disorder shows a similar pattern of reduced frontal activation to schizophrenia. The disorder is also characterized by failure of deactivation suggestive of default mode network dysfunction.

Correlation of the EPR properties of perchlorotriphenylmethyl radical and their efficiency as DNP polarizers

Water soluble perchlorinated trityl (PTM) radicals were found to be effective 95 GHz DNP (dynamic nuclear polarization) polarizers in ex situ (dissolution) 13C DNP (Gabellieri et al., Angew Chem., Int. Ed. 2010, 49, 3360). The degree of the nuclear polarization obtained was reported to be dependent on the position of the chlorine substituents on the trityl skeleton. In addition, on the basis of the DNP frequency sweeps it was suggested that the 13C NMR signal enhancement is mediated by the Cl nuclei. To understand the DNP mechanism of the PTM radicals we have explored the 95 GHz EPR characteristics of these radicals that are relevant to their performance as DNP polarizers. The EPR spectra of the radicals revealed axially symmetric g-tensors. A comparison of the spectra with the 13C DNP frequency sweeps showed that although the solid effect mechanism is operational the DNP frequency sweeps reveal some extra width suggesting that contributions from EPR forbidden transitions involving 35,37Cl nuclear flips are likely. This was substantiated experimentally by ELDOR (electron-electron double resonance) detected NMR measurements, which map the EPR forbidden transitions, and ELDOR experiments that follow the depolarization of the electron spin upon irradiation of the forbidden EPR transitions. DFT (density functional theory) calculations helped to assign the observed transitions and provided the relevant spin Hamiltonian parameters. These results show that the 35,37Cl hyperfine and nuclear quadrupolar interactions cause a considerable nuclear state mixing at 95 GHz thus facilitating the polarization of the Cl nuclei upon microwave irradiation. Overlap of Cl nuclear frequencies and the 13C Larmor frequency further facilitates the polarization of the 13C nuclei by spin diffusion. Calculation of the 13C DNP frequency sweep based on the Cl nuclear polarization showed that it does lead to an increase in the width of the spectra, improving the agreement with the experimental sweeps, thus supporting the existence of a new heteronuclear assisted DNP mechanism.

On the origin of the selectivity of plasmidic H-NS towards horizontally acquired DNA: Linking H-NS oligomerization and cooperative DNA binding

The nucleoid-associated protein H-NS is a global modulator of the expression of genes associated with adaptation to environmental changes. A variant of H-NS expressed in the R27 plasmid was previously shown to selectively modulate the expression of horizontally acquired genes, with minimal effects on core genes that are repressed by the chromosomal form of H-NS. Both H-NS proteins are formed by an oligomerization domain and a DNA-binding domain, which are connected by a linker that is highly flexible in the absence of DNA. We studied DNA binding by means of oligomer-forming chimeric proteins in which domains of the chromosomal and plasmidic variants are exchanged, as well as in monomeric truncated forms containing the DNA-binding domain and variable portions of the linker. Point mutations in the linker were also examined in full-length and truncated H-NS constructs. These experiments show that the linker region contributes to DNA binding affinity and that it is a main component of the distinct DNA binding properties of chromosomal and plasmidic H-NS. We propose that interactions between the linker and DNA limit the flexibility of the connection between H- NS oligomerization and DNA binding and provide an allosteric indirect readout mechanism to detect long- range distortions of DNA, thus enabling discrimination between core and horizontally acquired DNA.

Virtual milgram : empathic concern or personal distress? Evidence from functional MRI and dispositional measures

One motive for behaving as the agent of another"s aggression appears to be anchored in as yet unelucidated mechanisms of obedience to authority. In a recent partial replication of Milgram"s obedience paradigm within an immersive virtual environment, participants administered pain to a female virtual human and observed her suffering. Whether the participants" response to the latter was more akin to other-oriented empathic concern for her well-being or to a self-oriented aversive state of personal distress in response to her distress is unclear. Using the stimuli from that study, this event-related fMRI-based study analysed brain activity during observation of the victim in pain versus not in pain. This contrast revealed activation in pre-defi ned brain areas known to be involved in affective processing but not in those commonly associated with affect sharing (e.g., ACC and insula). We then examined whether different dimensions of dispositional empathy predict activity within the same pre-defi ned brain regions: While personal distress and fantasy (i.e., tendency to transpose oneself into fi ctional situations and characters) predicted brain activity, empathic concern and perspective taking predicted no change in neuronal response associated with pain observation. These exploratory fi ndings suggest that there is a distinct pattern of brain activity associated with observing the pain-related behaviour of the victim within the context of this social dilemma, that this observation evoked a self-oriented aversive state of personal distress, and that the objective"reality" of pain is of secondary importance for this response. These fi ndings provide a starting point for experimentally more rigorous investigation of obedience.

Rotational Doppler effect in magnetic resonance

We compute the shift in the frequency of the spin resonance in a solid that rotates in the field of a circularly polarized electromagnetic wave. Electron-spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are considered. We show that contrary to the case of the rotating LC circuit, the shift in the frequency of the spin resonance has strong dependence on the symmetry of the receiver. The shift due to rotation occurs only when rotational symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape of the body or by magnetocrystalline anisotropy. General expressions for the resonance frequency and power absorption are derived and implications for experiment are discussed.

Implicación del patrón radiológico en el pronóstico de los tumores oligodendrogliales: correlación con el perfil genético

Introducción. La codeleción 1p19q (LOH1p19q) confiere a los tumores oligodendrogliales quimiosensibilidad y un mejor pronóstico en relación con otros gliomas. La investigación dirigida a identificar características radiológicas asociadas a LOH1p19q ha despertado gran interés en los últimos años. Objetivos. Confirmar la existencia de heterogeneidad regional de los parámetros moleculares en los gliomas oligodendrogliales, valorar la asociación entre el perfil genético y determinadas características radiológicas y clínicas, y analizar el valor pronóstico de éstas. Pacientes y métodos. Se incluyeron 54 pacientes tratados según un protocolo preestablecido común. Se valoraron las secuencias T1, con/sin gadolinio, y T2 de la resonancia magnética preoperatoria a ciegas de la información molecular y clínica. El análisis de LOH se efectuó sobre muestras pareadas de ADN tumoral y genómico. Resultados. La presencia de LOH1p se halló fuertemente asociada a LOH19q (p < 0,0001). LOH1p19q resultó más frecuente en los tumores situados en el lóbulo frontal (odds ratio, OR = 5,38; intervalo de confianza del 95%, IC 95% = 1,51-19,13; p = 0,007) y sin necrosis radiológica (OR = 0,17; IC 95% = 0,03-0,80; p = 0,02). La localización frontal (riesgo relativo, RR = 4,499; IC 95% = 1,027-193,708; p = 0,046), la necrosis radiológica (RR = 0,213; IC 95% = 0,065-0,700; p = 0,011) y el grado de resección (RR = 9,231; IC 95% = 1,737-49,050; p = 0,009) resultaron factores pronósticos independientes de supervivencia global. Conclusiones. En los tumores oligodendrogliales, además del análisis histológico y el estudio genético-molecular, la valoración de determinadas características radiológicas puede resultar de gran utilidad para definir subgrupos de pacientes con pronóstico y respuesta al tratamiento similares. Los esfuerzos deben dirigirse, por tanto, hacia la utilización combinada de todos los recursos disponibles en cada centro.

Classifier combination for in vivo magnetic resonance spectra of brain tumours

Peer-reviewed

Synthesis and antitumor activity of mechercharmycin A analogues

Several analogs of the cytotoxic thiopeptide IB-01211 or Mechercharmycin A (1) have been synthetized. The cytotoxicity of 1 and the synthetized analogs was evaluated against a panel of three human tumor cell lines. Thiopeptide 1 and the most active derivatives, 2 and 3c, were chosen for further studies like effects on cell cycle progression and induction of apoptosis. Interestingly, the inhibition of cell division and activation of a programmed cell death by apoptosis was detected.

Aprendizaje de palabras nuevas concretas y abstractas

El significado de una palabra nueva puede adquirirse extrayéndolo de un contexto lingüístico, tanto durante la lectura como durante una conversación. Aún no sabemos cómo nuestro cerebro lleva a cabo este proceso de extracción y posterior aprendizaje del significado de nuevas palabras. En esta investigación hemos simulado el aprendizaje de palabras nuevas concretas y abstractas a partir de información contextual verbal, con el fin de caracterizar las regiones cerebrales implicadas durante el curso de este proceso

Imaging bilinguals: When the neurosciences meet the languange sciences

The starting point of our investigation was the longstanding notion that bilingual individuals need effective mechanisms to prevent interference from one language while processing material in the other (e.g. Penfield and Roberts, 1959). To demonstrate how the prevention of interference is implemented in the brain we employed event-related brain potentials (ERPs; see Munte, Urbach, ¨ Duzel and Kutas, 2000, for an introductory review) ¨ and functional magnetic resonance imaging (fMRI) techniques, thus pursuing a combined temporal and spatial imaging approach. In contrast to previous investigations using neuroimaging techniques in bilinguals, which had been mainly concerned with the localization of the primary and secondary languages (e.g. Perani, Paulesu, Galles, Dupoux, Dehaene, Bettinardi, Cappa, Fazio and Mehler, 1998; Chee, Caplan, Soon, Sriram, Tan, Thiel and Weekes, 1999), our study addressed the dynamic aspects of bilingual language processing.

Functional connectivity of reward processing in the brain

Controversial results have been reported concerning the neural mechanisms involved in the processing of rewards and punishments. On the one hand, there is evidence suggesting that monetary gains and losses activate a similar fronto-subcortical network. On the other hand, results of recent studies imply that reward and punishment may engage distinct neural mechanisms. Using functional magnetic resonance imaging (fMRI) we investigated both regional and interregional functional connectivity patterns while participants performed a gambling task featuring unexpectedly high monetary gains and losses. Classical univariate statistical analysis showed that monetary gains and losses activated a similar fronto-striatallimbic network, in which main activation peaks were observed bilaterally in the ventral striatum. Functional connectivity analysis showed similar responses for gain and loss conditions in the insular cortex, the amygdala, and the hippocampus that correlated with the activity observed in the seed region ventral striatum, with the connectivity to the amygdala appearing more pronounced after losses. Larger functional connectivity was found to the medial orbitofrontal cortex for negative outcomes. The fact that different functional patterns were obtained with both analyses suggests that the brain activations observed in the classical univariate approach identifi es the involvement of different functional networks in the current task. These results stress the importance of studying functional connectivity in addition to standard fMRI analysis in reward-related studies.

Reward networks in the brain as captured by connectivity measures

An assortment of human behaviors is thought to be driven by rewards including reinforcement learning, novelty processing, learning, decision making, economic choice, incentive motivation, and addiction. In each case the ventral tegmental area/ventral striatum (nucleus accumbens) (VTAVS) system has been implicated as a key structure by functional imaging studies, mostly on the basis of standard, univariate analyses. Here we propose that standard functional magnetic resonance imaging analysis needs to be complemented by methods that take into account the differential connectivity of the VTAVS system in the different behavioral contexts in order to describe reward based processes more appropriately. We fi rst consider the wider network for reward processing as it emerged from animal experimentation. Subsequently, an example for a method to assess functional connectivity is given. Finally, we illustrate the usefulness of such analyses by examples regarding reward valuation, reward expectation and the role of reward in addiction.

TCDI vs TCD for stroke risk prevention in children with sickle cell anemia: a cross-sectional study

Children with sickle cell anemia (SCA) are at increased risk of stroke. Elevated blood-flow velocities in the middle cerebral artery detected by Transcranial Doppler (TCD) are a good predictor of stroke risk in these children. Velocities obtained by TCD are measured by using a specific parameter, the time-averaged mean of the maximum velocity (TAMM). Children with TAMM velocities ≥200 cm/sec are at high risk of stroke, and transfusions as primary prevention might be done. Transcranial Doppler-imaging (TCDI) is now widely available and it allows the visualization of intracranial vessels.Few studies have compared the TAMM in TCD and TCDI, and no studies have established a cutoff point for TAMM in TCDI equivalent to the STOP criteria of “normal”, “conditional” and “abnormal”, which could predict a high risk of stroke in children with SCAObjectives: To compare the TAMM velocity obtained by TCDI with the TAMM velocity obtained with TCD in the middle cerebral artery, and to determine a cutoff point for TAMM in TCDI that could predict a high risk of stroke in children with SCAMethods: This study is a cross-sectional study of a diagnostic test. 78 children with sickle cell anemia between 2 to 16 years will be evaluated with both TCD and TCDI in order to determinate the TAMM with the two devices. Velocities obtained with both Doppler techniques will be compared using an intraclass correlation coefficient