936 research outputs found

    A Method to Identify and Isolate Pluripotent Human Stem Cells and Mouse Epiblast Stem Cells Using Lipid Body-Associated Retinyl Ester Fluorescence.

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    We describe the use of a characteristic blue fluorescence to identify and isolate pluripotent human embryonic stem cells and human-induced pluripotent stem cells. The blue fluorescence emission (450–500 nm) is readily observed by fluorescence microscopy and correlates with the expression of pluripotency markers (OCT4, SOX2, and NANOG). It allows easy identification and isolation of undifferentiated human pluripotent stem cells, high-throughput fluorescence sorting and subsequent propagation. The fluorescence appears early during somatic reprogramming. We show that the blue fluorescence arises from the sequestration of retinyl esters in cytoplasmic lipid bodies. The retinoid-sequestering lipid bodies are specific to human and mouse pluripotent stem cells of the primed or epiblast-like state and absent in naive mouse embryonic stem cells. Retinol, present in widely used stem cell culture media, is sequestered as retinyl ester specifically by primed pluripotent cells and also can induce the formation of these lipid bodies

    Use of diffusion tensor imaging to assess the impact of normobaric hyperoxia within at-risk pericontusional tissue after traumatic brain injury

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    Ischemia and metabolic dysfunction remain important causes of neuronal loss after head injury, and we have shown that normobaric hyperoxia may rescue such metabolic compromise. This study examines the impact of hyperoxia within injured brain using diffusion tensor imaging (DTI). Fourteen patients underwent DTI at baseline and after 1 hour of 80% oxygen. Using the apparent diffusion coefficient (ADC) we assessed the impact of hyperoxia within contusions and a 1 cm border zone of normal appearing pericontusion, and within a rim of perilesional reduced ADC consistent with cytotoxic edema and metabolic compromise. Seven healthy volunteers underwent imaging at 21%, 60%, and 100% oxygen. In volunteers there was no ADC change with hyperoxia, and contusion and pericontusion ADC values were higher than volunteers (P < 0.01). There was no ADC change after hyperoxia within contusion, but an increase within pericontusion (P < 0.05). We identified a rim of perilesional cytotoxic edema in 13 patients, and hyperoxia resulted in an ADC increase towards normal (P=0.02). We demonstrate that hyperoxia may result in benefit within the perilesional rim of cytotoxic edema. Future studies should address whether a longer period of hyperoxia has a favorable impact on the evolution of tissue injury

    Normobaric hyperoxia does not improve derangements in diffusion tensor imaging found distant from visible contusions following acute traumatic brain injury

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    We have previously shown that normobaric hyperoxia may benefit peri-lesional brain and white matter following traumatic brain injury (TBI). This study examined the impact of brief exposure to hyperoxia using diffusion tensor imaging (DTI) to identify axonal injury distant from contusions. Fourteen patients with acute moderate/severe TBI underwent baseline DTI and following one hour of 80% oxygen. Thirty-two controls underwent DTI, with 6 undergoing imaging following graded exposure to oxygen. Visible lesions were excluded and data compared with controls. We used the 99% prediction interval (PI) for zero change from historical control reproducibility measurements to demonstrate significant change following hyperoxia. Following hyperoxia DTI was unchanged in controls. In patients following hyperoxia, mean diffusivity (MD) was unchanged despite baseline values lower than controls (p < 0.05), and fractional anisotropy (FA) was lower within the left uncinate fasciculus, right caudate and occipital regions (p < 0.05). 16% of white and 14% of mixed cortical and grey matter patient regions showed FA decreases greater than the 99% PI for zero change. The mechanistic basis for some findings are unclear, but suggest that a short period of normobaric hyperoxia is not beneficial in this context. Confirmation following a longer period of hyperoxia is required.Dr. Veenith was supported by clinical research training fellowship from National institute of Academic Anaesthesia and Raymond Beverly Sackler studentship. VFJN is supported by a Health Foundation/Academy of Medical Sciences Clinician Scientist Fellowship. JPC was supported by Wellcome trust project grant. DKM is supported by an NIHR Senior Investigator Award. This work was supported by a Wellcome Trust Project Grant (WT093267) and Medical Research Council (UK) Program Grant (Acute brain injury: heterogeneity of mechanisms, therapeutic targets and outcome effects (G9439390 ID 65883)), the UK National Institute of Health Research Biomedical Research Centre at Cambridge, and the Technology Platform funding provided by the UK Department of Health. The funders had no role in study design, data collection and analyses, decision to publish, or preparation of the manuscript

    Antibacterial and antioxidant potential of biosynthesized copper nanoparticles mediated through Cissus arnotiana plant extract

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    © 2019 Elsevier B.V. Environment friendly methods for the synthesis of copper nanoparticles have become a valuable trend in the current scenario. The utilization of phytochemicals from plant extracts has become a unique technology for the synthesis of nanoparticles, as they possess dual nature of reducing and capping agents to the nanoparticles. In the present investigation we have synthesized copper nanoparticles (CuNPs) using a rare medicinal plant Cissus arnotiana and evaluated their antibacterial activity against gram negative and gram positive bacteria. The morphology and characterization of the synthesized CuNPs were studied and done using UV-Visible spectroscopy at a wavelength range of 350–380 nm. XRD studies were performed for analyzing the crystalline nature; SEM and TEM for evaluating the spherical shape within the size range of 60–90 nm and AFM was performed to check the surface roughness. The biosynthesized CuNPs showed better antibacterial activity against the gram-negative bacteria, E. coli with an inhibition zone of 22.20 ± 0.16 mm at 75 μg/ml. The antioxidant property observed was comparatively equal with the standard antioxidant agent ascorbic acid at a maximum concentration of 40 μg/ ml. This is the first study reported on C. arnotiana mediated biosynthesis of copper nanoparticles, where we believe that the findings can pave way for a new direction in the field of nanotechnology and nanomedicine where there is a significant potential for antibacterial and antioxidant activities. We predict that, these could lead to an exponential increase in the field of biomedical applications, with the utilization of green synthesized CuNPs, due to its remarkable properties. The highest antibacterial property was observed with gram-negative strains mainly, E. coli, due to its thin peptidoglycan layer and electrostatic interactions between the bacterial cell wall and CuNPs surfaces. Hence, CuNPs can be potent therapeutic agents in several biomedical applications, which are yet to be explored in the near future

    A Centralized Cluster-Based Hierarchical Approach for Green Communication in a Smart Healthcare System

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    The emergence of the Internet of Things (IoT) has revolutionized our digital and virtual worlds of connected devices. IoT is a key enabler for a wide range of applications in today's world. For example, in smart healthcare systems, the sensor-embedded devices monitor various vital signs of the patients. These devices operate on small batteries, and their energy need to be utilized efficiently. The need for green IoT to preserve the energy of these devices has never been more critical than today. The existing smart healthcare approaches adopt a heuristic approach for energy conservation by minimizing the duty-cycling of the underlying devices. However, they face numerous challenges in terms of excessive overhead, idle listening, overhearing, and collision. To circumvent these challenges, we have proposed a cluster-based hierarchical approach for monitoring the patients in an energy-efficient manner, i.e., green communication. The proposed approach organizes the monitoring devices into clusters of equal sizes. Within each cluster, a cluster head is designated to gather data from its member devices and broadcast to a centralized base station. Our proposed approach models the energy consumption of each device in various states, i.e., idle, sleep, awake, and active, and also performs the transitions between these states. We adopted an analytical approach for modeling the role of each device and its energy consumption in various states. Extensive simulations were conducted to validate our analytical approach by comparing it against the existing schemes. The experimental results of our approach enhance the network lifetime with a reduced energy consumption during various states. Moreover, it delivers a better quality of data for decision making on the patient's vital signs

    Under pressure: Response urgency modulates striatal and insula activity during decision-making under risk

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    When deciding whether to bet in situations that involve potential monetary loss or gain (mixed gambles), a subjective sense of pressure can influence the evaluation of the expected utility associated with each choice option. Here, we explored how gambling decisions, their psychophysiological and neural counterparts are modulated by an induced sense of urgency to respond. Urgency influenced decision times and evoked heart rate responses, interacting with the expected value of each gamble. Using functional MRI, we observed that this interaction was associated with changes in the activity of the striatum, a critical region for both reward and choice selection, and within the insula, a region implicated as the substrate of affective feelings arising from interoceptive signals which influence motivational behavior. Our findings bridge current psychophysiological and neurobiological models of value representation and action-programming, identifying the striatum and insular cortex as the key substrates of decision-making under risk and urgency

    Effect of anthropogenic sulphate aerosol in China on the drought in the western-to-central US

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    In recent decades, droughts have occurred in the western-to-central United States (US), significantly affecting food production, water supplies, ecosystem health, and the propagation of vector-borne diseases. Previous studies have suggested natural sea surface temperature (SST) forcing in the Pacific as the main driver of precipitation deficits in the US. Here, we show that the aerosol forcing in China, which has been known to alter the regional hydrological cycle in East Asia, may also contribute to reducing the precipitation in the western-to-central US through atmospheric teleconnections across the Pacific. Our model experiments show some indications that both the SST forcing and the increase in regional sulphate forcing in China play a similar role in modulating the western-to-central US precipitation, especially its long-term variation. This result indicates that regional air quality regulations in China have important implications for hydrological cycles in East Asia, as well as in the USopen1

    Total Hadronic Cross Section Data and the Froissart-Martin Bound

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    The energy dependence of the total hadronic cross section at high energies is investigated with focus on the recent experimental result by the TOTEM Collaboration at 7 TeV and the Froissart-Martin bound. On the basis of a class of analytical parametrization with the exponent γ\gamma in the leading logarithm contribution as a free parameter, different variants of fits to pppp and pˉp\bar{p}p total cross section data above 5 GeV are developed. Two ensembles are considered, the first comprising data up to 1.8 TeV, the second also including the data collected at 7 TeV. We shown that in all fit variants applied to the first ensemble the exponent is statistically consistent with γ\gamma = 2. Applied to the second ensemble, however, the same variants yield γ\gamma's above 2, a result already obtained in two other analysis, by U. Amaldi \textit{et al}. and by the UA4/2 Collaboration. As recently discussed by Ya. I. Azimov, this faster-than-squared-logarithm rise does not necessarily violate unitarity. Our results suggest that the energy dependence of the hadronic total cross section at high energies still constitute an open problem.Comment: 20 pages, 10 figures, introduction extended and general references added to match editorial style, to appear in the Brazilian Journal of Physic

    Singlet-doublet Higgs mixing and its implications on the Higgs mass in the PQ-NMSSM

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    We examine the implications of singlet-doublet Higgs mixing on the properties of a Standard Model (SM)-like Higgs boson within the Peccei-Quinn invariant extension of the NMSSM (PQ-NMSSM). The SM singlet added to the Higgs sector connects the PQ and visible sectors through a PQ-invariant non-renormalizable K\"ahler potential term, making the model free from the tadpole and domain-wall problems. For the case that the lightest Higgs boson is dominated by the singlet scalar, the Higgs mixing increases the mass of a SM-like Higgs boson while reducing its signal rate at collider experiments compared to the SM case. The Higgs mixing is important also in the region of parameter space where the NMSSM contribution to the Higgs mass is small, but its size is limited by the experimental constraints on the singlet-like Higgs boson and on the lightest neutralino constituted mainly by the singlino whose Majorana mass term is forbidden by the PQ symmetry. Nonetheless the Higgs mixing can increase the SM-like Higgs boson mass by a few GeV or more even when the Higgs signal rate is close to the SM prediction, and thus may be crucial for achieving a 125 GeV Higgs mass, as hinted by the recent ATLAS and CMS data. Such an effect can reduce the role of stop mixing.Comment: 26 pages, 3 figures; published in JHE
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