Magnetic resonance relaxation measurements using open-geometry sensors to assess the clog state of constructed wetlands

Monitoring the T1 relaxation of wetland clog matter has previously been identified as a gauge of its clogged state [1]. Magnetic resonance MR)sensors explored in other work have typically been of a bore-whole configuration, which may not be ideal in a wetland environment where the sensitive volume of the sensor may become physically clogged and therefore inoperable. This work investigates two open-geometry sensor designs and a short study is presented to determine the suitability of the sensors for monitoring the clog state of wetlands. It was shown that a bar magnet geometry has a higher stray field than that of the four magnet surface sensor also presented, leading to a prohibitively short T2eff. This means that the T1 values collected are notably shorter and not useful for distinguishing between clog state for the single magnet sensor. By contrast the four magnet surface sensor has a longer T2eff, making it more suitable for T1 measurements; where T1 = 915 ± 212 ms for a very thinly clogged sample, and T1 = 127 ± 27 ms for a heavily clogged sample. This offers a clearly resolvable difference in the T1 values allowing the clogging state to be easily determined and making this sensor the desirable choice for long-term embedding

Amygdala responses to fearful and happy facial expressions under conditions of binocular suppression

The human amygdala plays a crucial role in processing affective information conveyed by sensory stimuli. Facial expressions of fear and anger, which both signal potential threat to an observer, result in significant increases in amygdala activity, even when the faces are unattended or presented briefly and masked. It has been suggested that afferent signals from the retina travel to the amygdala via separate cortical and subcortical pathways, with the subcortical pathway underlying unconscious processing. Here we exploited the phenomenon of binocular rivalry to induce complete suppression of affective face stimuli presented to one eye. Twelve participants viewed brief, rivalrous visual displays in which a fearful, happy, or neutral face was presented to one eye while a house was presented simultaneously to the other. We used functional magnetic resonance imaging to study activation in the amygdala and extrastriate visual areas for consciously perceived versus suppressed face and house stimuli. Activation within the fusiform and parahippocampal gyri increased significantly for perceived versus suppressed faces and houses, respectively. Amygdala activation increased bilaterally in response to fearful versus neutral faces, regardless of whether the face was perceived consciously or suppressed because of binocular rivalry. Amygdala activity also increased significantly for happy versus neutral faces, but only when the face was suppressed. This activation pattern suggests that the amygdala has a limited capacity to differentiate between specific facial expressions when it must rely on information received via a subcortical route. We suggest that this limited capacity reflects a tradeoff between specificity and speed of processing

Survivin a radiogenetic promoter for glioblastoma viral gene therapy independently from CArG motifs

BACKGROUND: Radiogenetic therapy is a novel approach in the treatment of cancer, which employs genetic modification to alter the sensitivity of tumor cells to the effect of applied radiation. AIM: To select a potent radiation inducible promoter in the context of brain tumors and to investigate if CArG radio responsive motifs or other elements in the promoter nucleotide sequences can correlate to its response to radiation. METHODS: To select initial candidates for promoter inducible elements, the levels of mRNA expression of six different promoters were assessed using Quantitative RTPCR in D54 MG cells before and after radiation exposure. Recombinant Ad/reporter genes driven by five different promoters; CMV, VEGF, FLT-1, DR5 and survivin were constructed. Glioma cell lines were infected with different multiplicity of infection of the (promoter) Ad or CMV Ad. Cells were then exposed to a range of radiation (0–12 Gy) at single fraction. Fluorescent microscopy, Luc assay and X-gal staining was used to detect the level of expression of related genes. Different glioma cell lines and normal astrocytes were infected with Ad survivin and exposed to radiation. The promoters were analyzed for presence of CArG radio-responsive motifs and CCAAT box consensus using NCBI blast bioinformatics software. RESULTS: Radiotherapy increases the expression of gene expression by 1.25–2.5 fold in different promoters other than survivin after 2 h of radiation. RNA analysis was done and has shown an increase in copy number of tenfold for survivin. Most importantly cells treated with RT and Ad Luc driven by survivin promoter showed a fivefold increase in expression after 2 Gy of radiation in comparison to non-irradiated cells. Presence or absence of CArG motifs did not correlate with promoter response to radiation. Survivin with the best response to radiation had the lowest number of CCAAT box. CONCLUSION: Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs

Summation of visual motion across eye movements reflects a nonspatial decision mechanism

Human vision remains perceptually stable even though retinal inputs change rapidly with each eye movement. Although the neural basis of visual stability remains unknown, a recent psychophysical study pointed to the existence of visual feature-representations anchored in environmental rather than retinal coordinates (e.g., "spatiotopic" receptive fields; Melcher and Morrone, 2003). In that study, sensitivity to a moving stimulus presented after a saccadic eye movement was enhanced when preceded by another moving stimulus at the same spatial location before the saccade. The finding is consistent with spatiotopic sensory integration, but it could also have arisen from a probabilistic improvement in performance due to the presence of more than one motion signal for the perceptual decision. Here we show that this statistical advantage accounts completely for summation effects in this task. We first demonstrate that measurements of summation are confounded by noise related to an observer's uncertainty about motion onset times. When this uncertainty is minimized, comparable summation is observed regardless of whether two motion signals occupy the same or different locations in space, and whether they contain the same or opposite directions of motion. These results are incompatible with the tuning properties of motion-sensitive sensory neurons and provide no evidence for a spatiotopic representation of visual motion. Instead, summation in this context reflects a decision mechanism that uses abstract representations of sensory events to optimize choice behavior. Copyright © 2010 the authors

Audio versus written feedback: exploring learners’ preference and the impact of feedback format on students’ academic performance

Very little is known about the impact of the different types of feedback on students’ academic performance. This paper explores students’ preference in the use of audio and written feedback and how each type of feedback received by students impact on their academic performance in subsequent assignments. The study involved 68 students who were divided into two groups that received either audio or written feedback in their first assignment which was then recalled and applied into the second assignment. An analysis of results obtained in the second assignment was conducted and comparisons made between students in the audio and written feedback group. Students were also surveyed using an online questionnaire to ascertain their perceptions about the type of feedback they had received. The study established that the type of feedback received did not impact on students’ grades in the subsequent assignment. In addition, while students were broadly positive about audio feedback, they indicated a strong preference for written feedback in future assignments. The study recommends, among other things, further investigation into the link between students’ learning styles and their preferences for different types of feedback

Deciphering interplay between Salmonella invasion effectors

Bacterial pathogens have evolved a specialized type III secretion system (T3SS) to translocate virulence effector proteins directly into eukaryotic target cells. Salmonellae deploy effectors that trigger localized actin reorganization to force their own entry into non-phagocytic host cells. Six effectors (SipC, SipA, SopE/2, SopB, SptP) can individually manipulate actin dynamics at the plasma membrane, which acts as a ‘signaling hub’ during Salmonella invasion. The extent of crosstalk between these spatially coincident effectors remains unknown. Here we describe trans and cis binary entry effector interplay (BENEFIT) screens that systematically examine functional associations between effectors following their delivery into the host cell. The results reveal extensive ordered synergistic and antagonistic relationships and their relative potency, and illuminate an unexpectedly sophisticated signaling network evolved through longstanding pathogen–host interaction

A pilot study comparing the metabolic profiles of elite-level athletes from different sporting disciplines

Background: The outstanding performance of an elite athlete might be associated with changes in their blood metabolic profile. The aims of this study were to compare the blood metabolic profiles between moderate- and high-power and endurance elite athletes and to identify the potential metabolic pathways underlying these differences. Methods: Metabolic profiling of serum samples from 191 elite athletes from different sports disciplines (121 high- and 70 moderate-endurance athletes, including 44 high- and 144 moderate-power athletes), who participated in national or international sports events and tested negative for doping abuse at anti-doping laboratories, was performed using non-targeted metabolomics-based mass spectroscopy combined with ultrahigh-performance liquid chromatography. Multivariate analysis was conducted using orthogonal partial least squares discriminant analysis. Differences in metabolic levels between high- and moderate-power and endurance sports were assessed by univariate linear models. Results: Out of 743 analyzed metabolites, gamma-glutamyl amino acids were significantly reduced in both high-power and high-endurance athletes compared to moderate counterparts, indicating active glutathione cycle. High-endurance athletes exhibited significant increases in the levels of several sex hormone steroids involved in testosterone and progesterone synthesis, but decreases in diacylglycerols and ecosanoids. High-power athletes had increased levels of phospholipids and xanthine metabolites compared to moderate-power counterparts. Conclusions: This pilot data provides evidence that high-power and high-endurance athletes exhibit a distinct metabolic profile that reflects steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. Replication studies are warranted to confirm differences in the metabolic profiles associated with athletes’ elite performance in independent data sets, aiming ultimately for deeper understanding of the underlying biochemical processes that could be utilized as biomarkers with potential therapeutic implications

Rapid relaxation NMR measurements to predict rate coefficients in ionic liquid mixtures. An examination of reaction outcome changes in a homologous series of ionic liquids

A series of ionic liquids based on the 1-alkyl-3-methylimidazolium cations were examined as components of the solvent mixture for a bimolecular substitution process. The effects on both the rate coefficient of the process and the NMR spin-spin relaxation of the solvent components of changing either the alkyl chain length or the amount of ionic liquid in the reaction mixture were determined. At a constant mole fraction, a shorter alkyl chain length resulted in a greater rate coefficient enhancement and a longer relaxation time, with the opposite effects for a longer alkyl chain length. For a given ionic liquid, increasing the proportion of salt in the reaction mixture resulted in a greater rate coefficient and a shorter relaxation time. The microscopic origins of the rate coefficient enhancement were determined and a step change found in the activation parameters on increasing the alkyl chain length from hexyl to octyl, suggesting notable structuring in solution. Across a range of ionic liquids and solvent compositions, the relaxation time from NMR measurements was shown to relate to the reaction rate coefficient. The approach of using fast and simple NMR relaxation measurements to predict reaction outcomes was exemplified using a morpholinium-based ionic liquid

Differences in the signaling pathways of α1A- and α1B-adrenoceptors are related to different endosomal targeting

Aims: To compare the constitutive and agonist-dependent endosomal trafficking of α1A- and α1B-adrenoceptors (ARs) and to establish if the internalization pattern determines the signaling pathways of each subtype. Methods: Using CypHer5 technology and VSV-G epitope tagged α1A- and α1B-ARs stably and transiently expressed in HEK 293 cells, we analyzed by confocal microscopy the constitutive and agonist-induced internalization of each subtype, and the temporal relationship between agonist induced internalization and the increase in intracellular calcium (determined by FLUO-3 flouorescence), or the phosphorylation of ERK1/2 and p38 MAP kinases (determined by Western blot). Results and Conclusions: Constitutive as well as agonist-induced trafficking of α1A and α1B ARs maintain two different endosomal pools of receptors: one located close to the plasma membrane and the other deeper into the cytosol. Each subtype exhibited specific characteristics of internalization and distribution between these pools that determines their signaling pathways: α1A-ARs, when located in the plasma membrane, signal through calcium and ERK1/2 pathways but, when translocated to deeper endosomes, through a mechanism sensitive to β-arrestin and concanavalin A, continue signaling through ERK1/2 and also activate the p38 pathway. α1B-ARs signal through calcium and ERK1/2 only when located in the membrane and the signals disappear after endocytosis and by disruption of the membrane lipid rafts by methyl-β-cyclodextrin

UBC-Nepal expedition: markedly lower cerebral blood flow in high-altitude Sherpa children compared with children residing at sea level

Developmental cerebral hemodynamic adaptations to chronic high-altitude exposure, such as in the Sherpa population, are largely unknown. To examine hemodynamic adaptations in the developing human brain, we assessed common carotid (CCA), internal carotid (ICA), and vertebral artery (VA) flow and middle cerebral artery (MCA) velocity in 25 (9.6 ± 1.0 yr old, 129 ± 9 cm, 27 ± 8 kg, 14 girls) Sherpa children (3,800 m, Nepal) and 25 (9.9 ± 0.7 yr old, 143 ± 7 cm, 34 ± 6 kg, 14 girls) age-matched sea level children (344 m, Canada) during supine rest. Resting gas exchange, blood pressure, oxygen saturation and heart rate were assessed. Despite comparable age, height and weight were lower (both P < 0.01) in Sherpa compared with sea level children. Mean arterial pressure, heart rate, and ventilation were similar, whereas oxygen saturation (95 ± 2 vs. 99 ± 1%, P < 0.01) and end-tidal Pco2 (24 ± 3 vs. 36 ± 3 Torr, P < 0.01) were lower in Sherpa children. Global cerebral blood flow was ∼30% lower in Sherpa compared with sea level children. This was reflected in a lower ICA flow (283 ± 108 vs. 333 ± 56 ml/min, P = 0.05), VA flow (78 ± 26 vs. 118 ± 35 ml/min, P < 0.05), and MCA velocity (72 ± 14 vs. 88 ± 14 cm/s, P < 0.01). CCA flow was similar between Sherpa and sea level children (425 ± 92 vs. 441 ± 81 ml/min, P = 0.52). Scaling flow and oxygen uptake for differences in vessel diameter and body size, respectively, led to the same findings. A lower cerebral blood flow in Sherpa children may reflect specific cerebral hemodynamic adaptations to chronic hypoxia