Differential Sialylation Modulates Voltage-gated Na+ Channel Gating throughout the Developing Myocardium

Voltage-gated sodium channel function from neonatal and adult rat cardiomyocytes was measured and compared. Channels from neonatal ventricles required an ∼10 mV greater depolarization for voltage-dependent gating events than did channels from neonatal atria and adult atria and ventricles. We questioned whether such gating shifts were due to developmental and/or chamber-dependent changes in channel-associated functional sialic acids. Thus, all gating characteristics for channels from neonatal atria and adult atria and ventricles shifted significantly to more depolarized potentials after removal of surface sialic acids. Desialylation of channels from neonatal ventricles did not affect channel gating. After removal of the complete surface N-glycosylation structures, gating of channels from neonatal atria and adult atria and ventricles shifted to depolarized potentials nearly identical to those measured for channels from neonatal ventricles. Gating of channels from neonatal ventricles were unaffected by such deglycosylation. Immunoblot gel shift analyses indicated that voltage-gated sodium channel α subunits from neonatal atria and adult atria and ventricles are more heavily sialylated than α subunits from neonatal ventricles. The data are consistent with approximately 15 more sialic acid residues attached to each α subunit from neonatal atria and adult atria and ventricles. The data indicate that differential sialylation of myocyte voltage-gated sodium channel α subunits is responsible for much of the developmental and chamber-specific remodeling of channel gating observed here. Further, cardiac excitability is likely impacted by these sialic acid–dependent gating effects, such as modulation of the rate of recovery from inactivation. A novel mechanism is described by which cardiac voltage-gated sodium channel gating and subsequently cardiac rhythms are modulated by changes in channel-associated sialic acids

Effects of aging on identifying emotions conveyed by point-light walkers

M.G. was supported by EC FP7 HBP (grant 604102), PITN-GA-011-290011 (ABC) FP7-ICT-2013-10/ 611909 (KOROIBOT), and by GI 305/4-1 and KA 1258/15-1, and BMBF, FKZ: 01GQ1002A. K.S.P. was supported by a BBSRC New Investigator Grant. A.B.S. and P.J.B. were supported by an operating grant (528206) from the Canadian Institutes for Health Research. The authors also thank Donna Waxman for her valuable help in data collection for all experiments described here.Peer reviewedPostprin

Residential Mobility During Adolescence: Even Upward Moves Predict High School Dropout

Racial and economic segregation have long endured as systemic challenges in U.S. metropolitan areas. To combat the inequalities of segregation, two broad policy approaches have emerged: (1) preservation stresses investment in low-income neighborhoods, and (2) mobility stresses moving households in low-income areas to more affluent areas. Our recent study reveals some possible unintended consequences of the latter approach, particularly for adolescents. We find that moving during adolescence is associated with decreased odds of graduating from high school, even when moving to significantly higher income neighborhoods

Effects of aging on face identification and holistic face processing

AbstractSeveral studies have shown that face identification accuracy is lower in older than younger adults. This effect of aging might be due to age differences in holistic processing, which is thought to be an important component of human face processing. Currently, however, there is conflicting evidence as to whether holistic face processing is impaired in older adults. The current study therefore re-examined this issue by measuring response accuracy in a 1-of-4 face identification task and the composite face effect (CFE), a common index of holistic processing, in older adults. Consistent with previous reports, we found that face identification accuracy was lower in older adults than in younger adults tested in the same task. We also found a significant CFE in older adults that was similar in magnitude to the CFE measured in younger subjects with the same task. Finally, we found that there was a significant positive correlation between the CFE and face identification accuracy. This last result differs from the results obtained in a previous study that used the same tasks and which found no evidence of an association between the CFE and face identification accuracy in younger adults. Furthermore, the age difference was found with subtraction-, regression-, and ratio-based estimates of the CFE. The current findings are consistent with previous claims that older adults rely more heavily on holistic processing to identify objects in conditions of limited processing resources

Impact of more intensive grazing on nitrogen and phosphorus in shallow aquifers of the Southern Perth Basin

This study reports on the nutrient content, pH and salinity of groundwater samples collected from the watertable and within the Superficial and the upper Leederville Aquifers from the Southern Perth Basin, south of Pinjarra, Western Australia. Sampling was undertaken to determine the impact of intensification of broadscale grazing on groundwater nutrients in the area

The effects of aging on orientation discrimination

AbstractThe current experiments measured orientation discrimination thresholds in younger (mean age≈23 years) and older (mean age≈66 years) subjects. In Experiment 1, the contrast needed to discriminate Gabor patterns (0.75, 1.5, and 3c/deg) that differed in orientation by 12deg was measured for different levels of external noise. At all three spatial frequencies, discrimination thresholds were significantly higher in older than younger subjects when external noise was low, but not when external noise was high. In Experiment 2, discrimination thresholds were measured as a function of stimulus contrast by varying orientation while contrast was fixed. The resulting threshold-vs-contrast curves had very similar shapes in the two age groups, although the curve obtained from older subjects was shifted to slightly higher contrasts. At contrasts greater than 0.05, thresholds in both older and younger subjects were approximately constant at 0.5deg. The results from Experiments 1 and 2 suggest that age differences in orientation discrimination are due solely to differences in equivalent input noise. Using the same methods as Experiment 1, Experiment 3 measured thresholds in 6 younger observers as a function of external noise and retinal illuminance. Although reducing retinal illumination increased equivalent input noise, the effect was much smaller than the age difference found in Experiment 1. Therefore, it is unlikely that differences in orientation discrimination were due solely to differences in retinal illumination. Our findings are consistent with recent physiological experiments that have found elevated spontaneous activity and reduced orientation tuning on visual cortical neurons in senescent cats (Hua, T., Li, X., He, L., Zhou, Y., Wang, Y., Leventhal, A. G. (206). Functional degradation of visual cortical cells in old cats. Neurobiology Aging, 27(1), 155–162) and monkeys (Yu, S., Wang, Y., Li, X., Zhou, Y. & Leventhal, A. G. (2006). Functional degradation of visual cortex in senescent rhesus monkeys. Neuroscience, 140(3), 1023–1029; Leventhal, A. G., Wang, Y., Pu, M., Zhou, Y. & Ma. Y. (2003). GABA and its agonists improved visual cortical function in senescent monkeys. Science,300 (5620), 812–815)

The rapid emergence of stimulus specific perceptual learning

Is stimulus specific perceptual learning the result of extended practice or does it emerge early in the time course of learning? We examined this issue by manipulating the amount of practice given on a face identification task on Day 1, and altering the familiarity of stimuli on Day 2. We found that a small number of trials was sufficient to produce stimulus specific perceptual learning of faces: on Day 2, response accuracy decreased by the same amount for novel stimuli regardless of whether observers practiced 105 or 840 trials on Day 1. Current models of learning assume early procedural improvements followed by late stimulus specific gains. Our results show that stimulus specific and procedural improvements are distributed throughout the time course of learning

Multi-technique characterisation of MOVPE-grown GaAs on Si

The heterogeneous integration of III-V materials on a Si CMOS platform offers tremendous prospects for future high speed and low power logic applications. That said this integration generates immense scientific and technological challenges. In this work multi-technique characterisation is used to investigate properties of GaAs layers grown by Metal-Organic Vapour Phase Epitaxy (MOVPE) on Si substrates - (100) with 4⁰ offset towards - under various growth conditions. This being a crucial first step towards the production of III-V template layers with a relatively lower density of defects for selective epitaxial overgrowth of device quality material. The optical and structural properties of heteroepitaxial GaAs are first investigated by micro-Raman spectroscopy and photoluminescence and reflectance measurements. High-resolution X-ray diffraction (HR-XRD) is used to investigate structural properties. Advanced XRD techniques, including double-axis diffraction and X-ray crystallographic mapping are used to evaluate degrees of relaxation and distribution of the grain orientations in the epilayers, respectively. Results obtained from the different methodologies are compared in an attempt to understand growth kinetics of the materials system. The GaAs overlayer grown with annealing at 735⁰C following As predeposition at 500⁰C shows the best crystallinity. Close inspection confirms the growth of epitaxial GaAs preferentially oriented along (100) embedded in a highly-textured polycrystalline structure

Generalized remote state preparation: Trading cbits, qubits and ebits in quantum communication

We consider the problem of communicating quantum states by simultaneously making use of a noiseless classical channel, a noiseless quantum channel and shared entanglement. We specifically study the version of the problem in which the sender is given knowledge of the state to be communicated. In this setting, a trade-off arises between the three resources, some portions of which have been investigated previously in the contexts of the quantum-classical trade-off in data compression, remote state preparation and superdense coding of quantum states, each of which amounts to allowing just two out of these three resources. We present a formula for the triple resource trade-off that reduces its calculation to evaluating the data compression trade-off formula. In the process, we also construct protocols achieving all the optimal points. These turn out to be achievable by trade-off coding and suitable time-sharing between optimal protocols for cases involving two resources out of the three mentioned above.Comment: 15 pages, 2 figures, 1 tabl

Inversion Leads to Quantitative, Not Qualitative, Changes in Face Processing

AbstractHumans are remarkably adept at recognizing objects across a wide range of views. A notable exception to this general rule is that turning a face upside down makes it particularly difficult to recognize [1–3]. This striking effect has prompted speculation that inversion qualitatively changes the way faces are processed. Researchers commonly assume that configural cues strongly influence the recognition of upright, but not inverted, faces [3–5]. Indeed, the assumption is so well accepted that the inversion effect itself has been taken as a hallmark of qualitative processing differences [6]. Here, we took a novel approach to understand the inversion effect. We used response classification [7–10] to obtain a direct view of the perceptual strategies underlying face discrimination and to determine whether orientation effects can be explained by differential contributions of nonlinear processes. Inversion significantly impaired performance in our face discrimination task. However, surprisingly, observers utilized similar, local regions of faces for discrimination in both upright and inverted face conditions, and the relative contributions of nonlinear mechanisms to performance were similar across orientations. Our results suggest that upright and inverted face processing differ quantitatively, not qualitatively; information is extracted more efficiently from upright faces, perhaps as a by-product of orientation-dependent expertise