Mode Switching Is the Major Mechanism of Ligand Regulation of InsP3 Receptor Calcium Release Channels

The inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R) plays a critical role in generation of complex Ca2+ signals in many cell types. In patch clamp recordings of isolated nuclei from insect Sf9 cells, InsP3R channels were consistently detected with regulation by cytoplasmic InsP3 and free Ca2+ concentrations ([Ca2+]i) very similar to that observed for vertebrate InsP3R. Long channel activity durations of the Sf9-InsP3R have now enabled identification of a novel aspect of InsP3R gating: modal gating. Using a novel algorithm to analyze channel modal gating kinetics, InsP3R gating can be separated into three distinct modes: a low activity mode, a fast kinetic mode, and a burst mode with channel open probability (Po) within each mode of 0.007 ± 0.002, 0.24 ± 0.03, and 0.85 ± 0.02, respectively. Channels reside in each mode for long periods (tens of opening and closing events), and transitions between modes can be discerned with high resolution (within two channel opening and closing events). Remarkably, regulation of channel gating by [Ca2+]i and [InsP3] does not substantially alter channel Po within a mode. Instead, [Ca2+]i and [InsP3] affect overall channel Po primarily by changing the relative probability of the channel being in each mode, especially the high and low Po modes. This novel observation therefore reveals modal switching as the major mechanism of physiological regulation of InsP3R channel activity, with implications for the kinetics of Ca2+ release events in cells

Acoustic emission source location in complex structures using full automatic delta T mapping technique

An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the “Minimum Difference” approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation

Characterisation of fatigue damage in composites using an Acoustic Emission Parameter Correction Technique

In industrial applications of composite materials, accurate characterisation of damage is vital. Acoustic Emission (AE) can be utilised to achieve this, however, in large-scale complex geometry components, traditional AE approaches have limitations. In this study a large carbon fibre specimen was used to generate different damage mechanisms under fatigue loading. The Delta T Mapping technique was used to locate damage and signal features were corrected using the Parameter Correction Technique (PCT). A comparison between results obtained using traditional signal features and those obtained using PCT is given. The results are validated using C-scanning and computed tomography. Matrix cracking and delamination were successfully identified using the PCT approach and improved location accuracy was achieved

Early Antiretroviral Therapy at High CD4 Counts Does Not Improve Arterial Elasticity: A Substudy of the Strategic Timing of AntiRetroviral Treatment (START) Trial

BACKGROUND: Both human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) may increase cardiovascular disease (CVD) risk. Vascular function assessments can be used to study CVD pathogenesis. We compared the effect of immediate versus deferred ART initiation at CD4 counts >500 cells/mm(3) on small arterial elasticity (SAE) and large artery elasticity (LAE). METHODS: Radial artery blood pressure waveforms were recorded noninvasively. Small arterial elasticity and LAE were derived from analysis of the diastolic pulse waveform. Randomized treatment groups were compared with linear models at each visit and longitudinal mixed models. RESULTS: Study visits involved 332 participants in 8 countries: mean (standard deviation [SD]) age 35 (10), 70% male, 66% nonwhite, 30% smokers, and median CD4 count 625 cells/mm(3) and 10-year Framingham risk score for CVD 1.7%. Mean (SD) SAE and LAE values at baseline were 7.3 (2.9) mL/mmHg × 100 and 16.6 (4.1) mL/mmHg × 10, respectively. Median time on ART was 47 and 12 months in the immediate and deferred ART groups, respectively. The treatment groups did not demonstrate significant within-person changes in SAE or LAE during the follow-up period, and there was no difference in mean change from baseline between treatment groups. The lack of significant differences persisted after adjustment, when restricted to early or late changes, after censoring participants in deferred group who started ART, and among subgroups defined by CVD and HIV risk factors. CONCLUSIONS: Among a diverse global population of HIV-positive persons with high CD4 counts, these randomized data suggest that ART treatment does not have a substantial influence on vascular function among younger HIV-positive individuals with preserved immunity

Sublittoral soft bottom communities and diversity of Mejillones Bay in northern Chile (Humboldt Current upwelling system)

The macrozoobenthos of Mejillones Bay (23°S; Humboldt Current) was quantitatively investigated over a 7-year period from austral summer 1995/1996 to winter 2002. About 78 van Veen grab samples taken at six stations (5, 10, 20 m depth) provided the basis for the analysis of the distribution of 60 species and 28 families of benthic invertebrates, as well as of their abundance and biomass. Mean abundance (2,119 individuals m-2) was in the same order compared to a previous investigation; mean biomass (966 g formalin wet mass m-2), however, exceeded prior estimations mainly due to the dominance of the bivalve Aulacomya ater. About 43% of the taxa inhabited the complete depth range. Mean taxonomic Shannon diversity (H', Log e) was 1.54 ± 0.58 with a maximum at 20 m (1.95 ± 0.33); evenness increased with depth. The fauna was numerically dominated by carnivorous gastropods, polychaetes and crustaceans (48%). About 15% of the species were suspensivorous, 13% sedimentivorous, 11% detritivorous, 7% omnivorous and 6% herbivorous. Cluster analyses showed a significant difference between the shallow and the deeper stations. Gammarid amphipods and the polychaete family Nephtyidae characterized the 5-mzone, the molluscs Aulacomya ater, Mitrella unifasciata and gammarids the intermediate zone, while the gastropod Nassarius gayi and the polychaete family Nereidae were most prominent at the deeper stations. The communities of the three depth zones did not appear to be limited by hypoxia during non-El Niño conditions. Therefore, no typical change in community structure occurred during El Niño 1997–1998, in contrast to what was observed for deeper faunal assemblages and hypoxic bays elsewhere in the coastal Humboldt Current system

The auditory cortex of the bat Phyllostomus discolor: Localization and organization of basic response properties

<p>Abstract</p> <p>Background</p> <p>The mammalian auditory cortex can be subdivided into various fields characterized by neurophysiological and neuroarchitectural properties and by connections with different nuclei of the thalamus. Besides the primary auditory cortex, echolocating bats have cortical fields for the processing of temporal and spectral features of the echolocation pulses. This paper reports on location, neuroarchitecture and basic functional organization of the auditory cortex of the microchiropteran bat <it>Phyllostomus discolor </it>(family: Phyllostomidae).</p> <p>Results</p> <p>The auditory cortical area of <it>P. discolor </it>is located at parieto-temporal portions of the neocortex. It covers a rostro-caudal range of about 4800 μm and a medio-lateral distance of about 7000 μm on the flattened cortical surface.</p> <p>The auditory cortices of ten adult <it>P. discolor </it>were electrophysiologically mapped in detail. Responses of 849 units (single neurons and neuronal clusters up to three neurons) to pure tone stimulation were recorded extracellularly. Cortical units were characterized and classified depending on their response properties such as best frequency, auditory threshold, first spike latency, response duration, width and shape of the frequency response area and binaural interactions.</p> <p>Based on neurophysiological and neuroanatomical criteria, the auditory cortex of <it>P. discolor </it>could be subdivided into anterior and posterior ventral fields and anterior and posterior dorsal fields. The representation of response properties within the different auditory cortical fields was analyzed in detail. The two ventral fields were distinguished by their tonotopic organization with opposing frequency gradients. The dorsal cortical fields were not tonotopically organized but contained neurons that were responsive to high frequencies only.</p> <p>Conclusion</p> <p>The auditory cortex of <it>P. discolor </it>resembles the auditory cortex of other phyllostomid bats in size and basic functional organization. The tonotopically organized posterior ventral field might represent the primary auditory cortex and the tonotopically organized anterior ventral field seems to be similar to the anterior auditory field of other mammals. As most energy of the echolocation pulse of <it>P. discolor </it>is contained in the high-frequency range, the non-tonotopically organized high-frequency dorsal region seems to be particularly important for echolocation.</p

Impact of Allogeneic Hematopoietic Stem Cell Transplantation on the HIV Reservoir and Immune Response in 3 HIV-Infected Individuals

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) can lead to significant changes to the HIV reservoir and HIV immune responses, indicating that further characterization of HIV-infected patients undergoing HSCT is warranted. Methods: We studied 3 patients who underwent HSCT after either reduced intensity conditioning or myeloablative conditioning regimen. We measured HIV antigens and antibodies (Ag/Ab), HIV-specific CD4 + T-cell responses, HIV RNA, and DNA in plasma, peripheral blood mononuclear cells, isolated CD4 + T cells from peripheral blood, and lymph node cells. The patients remained on antiretroviral therapy throughout the follow-up period. Results: All patients have been in continued remission for 4-6 years post-HSCT. Analyses of HIV RNA and DNA levels showed substantial reductions in HIV reservoir-related measurements in all 3 patients, changes in immune response varied with pronounced reductions in 2 patients and a less dramatic reduction in 1 patient. One patient experienced unexpected viral rebound 4 years after HSCT. Conclusions: These 3 cases highlight the substantial changes to the HIV reservoir and the HIV immune response in patients undergoing allogeneic HSCT. The viral rebound observed in 1 patient indicates that replication competent HIV can re-emerge several years after HSCT despite these marked changes

Stress from Uncertainty from Graduation to Retirement—A Population-Based Study of Swiss Physicians

BACKGROUND: Uncertainty shapes many decisions made by physicians everyday. Uncertainty and physicians’ inability to handle it may result in substandard care and unexplained variations in patterns of care. OBJECTIVE: To describe socio-demographic and professional characteristics of reactions to uncertainty among physicians from all specialties, including physicians in training. DESIGN: Cross-sectional postal survey. PARTICIPANT: All physicians practicing in Geneva, Switzerland (n = 1,994). MEASUREMENT: Reaction to medical care uncertainty was measured with the Anxiety Due to Uncertainty and Concern About Bad Outcomes scales. The questionnaire also included items about professional characteristics and work-related satisfaction scales. RESULTS: After the first mailing and two reminders, 1,184 physicians responded to the survey. In univariate analysis, women, junior physicians, surgical specialists, generalist physicians, and physicians with lower workloads had higher scores in both scales. In multivariate models, sex, medical specialty, and workload remained significantly associated with both scales, whereas clinical experience remained associated only with concern about bad outcomes. Higher levels of anxiety due to uncertainty were associated with lower scores of work-related satisfaction, while higher levels of concern about bad outcomes were associated with lower satisfaction scores for patient care, personal rewards, professional relations, and general satisfaction, but not for work-related burden or satisfaction with income-prestige. The negative effect of anxiety due to uncertainty on work-related satisfaction was more important for physicians in training. CONCLUSION: Physicians’ reactions to uncertainty in medical care were associated with several dimensions of work-related satisfaction. Physicians in training experienced the greatest impact of anxiety due to uncertainty on their work-related satisfaction. Incorporating strategies to deal with uncertainty into residency training may be useful

Dengue Virus Infection and Virus-Specific HLA-A2 Restricted Immune Responses in Humanized NOD-scid IL2rγnull Mice

BACKGROUND:The lack of a suitable animal model to study viral and immunological mechanisms of human dengue disease has been a deterrent to dengue research. METHODOLOGY/PRINCIPAL FINDINGS:We sought to establish an animal model for dengue virus (DENV) infection and immunity using non-obese diabetic/severe combined immunodeficiency interleukin-2 receptor gamma-chain knockout (NOD-scid IL2rgamma(null)) mice engrafted with human hematopoietic stem cells. Human CD45(+) cells in the bone marrow of engrafted mice were susceptible to in vitro infection using low passage clinical and established strains of DENV. Engrafted mice were infected with DENV type 2 by different routes and at multiple time points post infection, we detected DENV antigen and RNA in the sera, bone marrow, spleen and liver of infected engrafted mice. Anti-dengue IgM antibodies directed against the envelope protein of DENV peaked in the sera of mice at 1 week post infection. Human T cells that developed following engraftment of HLA-A2 transgenic NOD-scid IL2rgamma(null) mice with HLA-A2(+) human cord blood hematopoietic stem cells, were able to secrete IFN-gamma, IL-2 and TNF-alpha in response to stimulation with three previously identified A2 restricted dengue peptides NS4b 2353((111-119)), NS4b 2423((181-189)), and NS4a 2148((56-64)). CONCLUSIONS/SIGNIFICANCE:This is the first study to demonstrate infection of human cells and functional DENV-specific T cell responses in DENV-infected humanized mice. Overall, these mice should be a valuable tool to study the role of prior immunity on subsequent DENV infections

Equilibrium of Global Amphibian Species Distributions with Climate

A common assumption in bioclimatic envelope modeling is that species distributions are in equilibrium with contemporary climate. A number of studies have measured departures from equilibrium in species distributions in particular regions, but such investigations were never carried out for a complete lineage across its entire distribution. We measure departures of equilibrium with contemporary climate for the distributions of the world amphibian species. Specifically, we fitted bioclimatic envelopes for 5544 species using three presence-only models. We then measured the proportion of the modeled envelope that is currently occupied by the species, as a metric of equilibrium of species distributions with climate. The assumption was that the greater the difference between modeled bioclimatic envelope and the occupied distribution, the greater the likelihood that species distribution would not be at equilibrium with contemporary climate. On average, amphibians occupied 30% to 57% of their potential distributions. Although patterns differed across regions, there were no significant differences among lineages. Species in the Neotropic, Afrotropics, Indo-Malay, and Palaearctic occupied a smaller proportion of their potential distributions than species in the Nearctic, Madagascar, and Australasia. We acknowledge that our models underestimate non equilibrium, and discuss potential reasons for the observed patterns. From a modeling perspective our results support the view that at global scale bioclimatic envelope models might perform similarly across lineages but differently across regions