Height Fluctuations and Intermittency of V2O5V_2 O_5 Films by Atomic Force Microscopy

The spatial scaling law and intermittency of the $V_2 O_5$ surface roughness by atomic force microscopy has been investigated. The intermittency of the height fluctuations has been checked by two different methods, first, by measuring scaling exponent of q-th moment of height-difference fluctuations i.e. $C_q =$ and the second, by defining generating function $Z(q,N)$ and generalized multi-fractal dimension $D_q$. These methods predict that there is no intermittency in the height fluctuations. The observed roughness and dynamical exponents can be explained by the numerical simulation on the basis of forced Kuramoto-Sivashinsky equation.Comment: 6 pages (two columns), 11 eps. figures, late

Retrieval Practice Fails to Insulate Episodic Memories against Interference after Stroke

Recent work in cognitive psychology showed that retrieval practice of previously studied information can insulate this information against retroactive interference from subsequently studied other information in healthy individuals. The present study examined whether this beneficial effect of interference reduction is also present in patients with stroke. Twenty-two patients with stroke, 4.6 months post injury on average, and 22 healthy controls participated in the experiment. In each of two experimental sessions, participants first studied a list of items (list 1) and then underwent a practice phase in which the list 1 items were either restudied or retrieval practiced. Participants then either studied a second list of items (list 2) or fulfilled an unrelated distractor task. Recall of the two lists' items was assessed in a final criterion test. Results showed that, in healthy controls, additional study of list 2 items impaired final recall of list 1 items in the restudy condition but not in the retrieval practice condition. In contrast, in patients with stroke, list 2 learning impaired final list 1 recall in both conditions. The results indicate that retrieval practice insulated the tested information against retroactive interference in healthy controls, but failed to do so in patients with stroke. Possible implications of the findings for the understanding of long-term memory impairment after stroke are discussed

Maternal PTSD and corresponding neural activity mediate effects of child exposure to violence on child PTSD symptoms

The aim of this study was to examine the relationship of maternal interpersonal violence-related posttraumatic stress disorder (IPV-PTSD), associated neural activity in response to mother-child relational stimuli, and child psychopathology indicators at child ages 12-42 months and one year later. The study tested the hypothesis that decreased maternal neural activity in regions that subserve emotion regulation would be associated with child symptoms associated with emotional dysregulation at both time points. Functional magnetic resonance imaging of 42 mothers with or without violence-exposure and associated IPV-PTSD were assessed. Their child's life-events and symptoms/behaviors indicative of high-risk subsequent PTSD diagnosis on a maternal-report questionnaire were measured one year later. Maternal IPV-PTSD severity was significantly associated with decreased ventromedial prefrontal cortex (vmPFC) activation in response to mother-child relational stimuli. Maternal IPV-PTSD severity and decreased vmPFC activation were then significantly associated with a child attachment disturbance at 12-42 months and symptoms/behaviors one year later, that were correlated with emotional dysregulation and risk for child PTSD. Maternal IPV-PTSD and child exposure to IPV were both predictive of child PTSD symptoms with maternal IPV-PTSD likely mediating the effects of child IPV exposure on child PTSD symptoms. These findings suggest that maternal IPV-PTSD severity and associated decreased vmPFC activity in response to mother-child relational stimuli are predictors of child psychopathology by age 12-42 months and one-year later. Significant findings in this paper may well be useful in understanding how maternal top-down cortico-limbic dysregulation promotes intergenerational transmission of IPV and related psychopathology and, thus should be targeted in treatment

Seeing Emotion with Your Ears: Emotional Prosody Implicitly Guides Visual Attention to Faces

Interpersonal communication involves the processing of multimodal emotional cues, particularly facial expressions (visual modality) and emotional speech prosody (auditory modality) which can interact during information processing. Here, we investigated whether the implicit processing of emotional prosody systematically influences gaze behavior to facial expressions of emotion. We analyzed the eye movements of 31 participants as they scanned a visual array of four emotional faces portraying fear, anger, happiness, and neutrality, while listening to an emotionally-inflected pseudo-utterance (Someone migged the pazing) uttered in a congruent or incongruent tone. Participants heard the emotional utterance during the first 1250 milliseconds of a five-second visual array and then performed an immediate recall decision about the face they had just seen. The frequency and duration of first saccades and of total looks in three temporal windows ([0–1250 ms], [1250–2500 ms], [2500–5000 ms]) were analyzed according to the emotional content of faces and voices. Results showed that participants looked longer and more frequently at faces that matched the prosody in all three time windows (emotion congruency effect), although this effect was often emotion-specific (with greatest effects for fear). Effects of prosody on visual attention to faces persisted over time and could be detected long after the auditory information was no longer present. These data imply that emotional prosody is processed automatically during communication and that these cues play a critical role in how humans respond to related visual cues in the environment, such as facial expressions

Purification and Structural Characterization of Siderophore (Corynebactin) from Corynebacterium diphtheriae

During infection, Corynebacterium diphtheriae must compete with host iron-sequestering mechanisms for iron. C. diphtheriae can acquire iron by a siderophore-dependent iron-uptake pathway, by uptake and degradation of heme, or both. Previous studies showed that production of siderophore (corynebactin) by C. diphtheriae is repressed under high-iron growth conditions by the iron-activated diphtheria toxin repressor (DtxR) and that partially purified corynebactin fails to react in chemical assays for catecholate or hydroxamate compounds. In this study, we purified corynebactin from supernatants of low-iron cultures of the siderophore-overproducing, DtxR-negative mutant strain C. diphtheriae C7(β) ΔdtxR by sequential anion-exchange chromatography on AG1-X2 and Source 15Q resins, followed by reverse-phase high-performance liquid chromatography (RP-HPLC) on Zorbax C8 resin. The Chrome Azurol S (CAS) chemical assay for siderophores was used to detect and measure corynebactin during purification, and the biological activity of purified corynebactin was shown by its ability to promote growth and iron uptake in siderophore-deficient mutant strains of C. diphtheriae under iron-limiting conditions. Mass spectrometry and NMR analysis demonstrated that corynebactin has a novel structure, consisting of a central lysine residue linked through its α- and ε- amino groups by amide bonds to the terminal carboxyl groups of two different citrate residues. Corynebactin from C. diphtheriae is structurally related to staphyloferrin A from Staphylococcus aureus and rhizoferrin from Rhizopus microsporus in which d-ornithine or 1,4-diaminobutane, respectively, replaces the central lysine residue that is present in corynebactin

Complete Phenotypic Recovery of an Alzheimer's Disease Model by a Quinone-Tryptophan Hybrid Aggregation Inhibitor

The rational design of amyloid oligomer inhibitors is yet an unmet drug development need. Previous studies have identified the role of tryptophan in amyloid recognition, association and inhibition. Furthermore, tryptophan was ranked as the residue with highest amyloidogenic propensity. Other studies have demonstrated that quinones, specifically anthraquinones, can serve as aggregation inhibitors probably due to the dipole interaction of the quinonic ring with aromatic recognition sites within the amyloidogenic proteins. Here, using in vitro, in vivo and in silico tools we describe the synthesis and functional characterization of a rationally designed inhibitor of the Alzheimer's disease-associated β-amyloid. This compound, 1,4-naphthoquinon-2-yl-L-tryptophan (NQTrp), combines the recognition capacities of both quinone and tryptophan moieties and completely inhibited Aβ oligomerization and fibrillization, as well as the cytotoxic effect of Aβ oligomers towards cultured neuronal cell line. Furthermore, when fed to transgenic Alzheimer's disease Drosophila model it prolonged their life span and completely abolished their defective locomotion. Analysis of the brains of these flies showed a significant reduction in oligomeric species of Aβ while immuno-staining of the 3rd instar larval brains showed a significant reduction in Aβ accumulation. Computational studies, as well as NMR and CD spectroscopy provide mechanistic insight into the activity of the compound which is most likely mediated by clamping of the aromatic recognition interface in the central segment of Aβ. Our results demonstrate that interfering with the aromatic core of amyloidogenic peptides is a promising approach for inhibiting various pathogenic species associated with amyloidogenic diseases. The compound NQTrp can serve as a lead for developing a new class of disease modifying drugs for Alzheimer's disease