546 research outputs found

    Peripheral stimulation affects subthreshold Triple Stimulation Technique.

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    Compared to conventional transcranial magnetic stimulation (TMS), the triple stimulation technique (TST) strongly decrease the effects of desynchronization of descending discharges and accompanying phase cancellation that follow TMS and offers a more sensitive method to quantify motor evoked potentials (MEPs). Using the TST, we explored as to whether sub-threshold TMS evokes peripheral motor neuron discharges (MNs). We compared the number of MEPs elicited by TMS and by TST in fifteen healthy participants. We used the subthreshold intensity of 80 % resting motor threshold. To control the TST assessment of the corticospinal tract, we included a peripheral stimulation control condition, which consisted of peripheral stimulation alone, in a subgroup of five volunteers. Compared to TMS, TST at sub-threshold intensities did not detect significantly more responses unequivocally attributable to the cortical stimulation. In contrast, the peripheral supra-maximal stimuli produced confounding effects in the TST condition that were, in part, indistinguishable from cortical responses. At subthreshold TMS intensities, the TST does not detect more discharges of spinal MNs than conventional TMS and, in addition, it is confounded by effects from peripheral stimulation. The TST can be useful in assessing the integrity of the MN pool and of the corticospinal tract. However, if used at near threshold intensity, the confounding effects of peripheral stimulation need to be considered; for instance, in paired-pulse stimulation paradigms assessing the cortical physiology

    Resiliency of the western Chesapeake Bay to total suspended solid concentrations following storms and accounting for land-cover

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    The effect of storms on water quality in the Chesapeake Bay has been studied in a patchwork fashion at various sites for short periods of time. In this paper, we use a relationship between MODIS-Terra red light reflectance and total suspended solid (TSS) concentrations in order to develop a fourteen-year time period of TSS estimates during which effects of storms and land cover can be studied over a large portion of the Bay. Exponential fits were most appropriate, resulting in viable reflectance-TSS relationships for the five major Western Shore rivers and the Mainstem of the Bay. Other tributaries were less well-disposed for such relationships due to lack of a large range of TSS concentrations, shallow river beds, or low number of data points. Treating the entire Chesapeake as a single entity and modeling a single reflectance-TSS relationship for the entire estuary produced poorer models with less significance compared to treating each channel separately. Over 2800 rain events were studied in the Lower Western Shore between 2000 and 2014. We found some evidence that higher rainfall amounts correspond to a lower distribution of TSS concentrations 1 day following the event in forested watersheds. At rainfall events of <50 mm, maximum TSS within one day of the storm was highly variable, suggesting that rainfall amounts alone cannot explain variation in TSS levels. Finally, we found value in the use of prediction intervals around TSS estimates, a statistical procedure uncommonly used heretofore with satellite-based estimates but which can help to determine if results are significant or not

    Bogota-VAC – A Newly Modified Temporary Abdominal Closure Technique

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    Background: We present Bogota-VAC, a newly modified temporary abdominal closure (TAC) technique for open abdomen condition after abdominal compartment syndrome (ACS). Methods: A thin isolation bag (Bogota bag) and a vacuum assisted closure (VAC) system were combined. A matching bag was tension-free fixed on the abdominal fascia by fascia suture. A ring shaped black polyurethane foam of the VAC system was placed into the gap between Bogota bag, abdominal fascia and the wound edge. A constant negative topic pressure of 50–75 mmHg was used in the VAC system. Results: Intra-abdominal pressure (IAP: 22 ± 2 mmHg)of four patients with ACS after severe traumatic brain injury and one patient with isolated ACS after blunt abdominal trauma decreased significantly (p = 0.01)after decompressive laparotomy and treatment with Bogota-VAC (IAP: 10 ± 2 mmHg) and remained low, measured via urinary bladder pressure. Intracranial pressure (ICP) in the four traumatic brain injury patients decreased from 42 ± 13 mmHg to 15 ± 3 mmHg after abdominal decompression. Cerebral perfusion pressure (57 ± 14 mmHg) increased to 74 ± 2 mmHg. Conclusion: The advantage of the presented Bogota-VAC is leak tightness, wound conditioning (soft tissue/fascia), skin protection and facilitation of nursing in combinationwith highest volume reserve capacity (VRC), thus preventing recurrent increased intra-abdominal and intracranial pressure in the initial phase after decompression of ACS compared to other TAC techniques

    How war, drought, and dam management impact water supply in the Tigris and Euphrates Rivers

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    The fast-paced conflicts in the Middle East can disrupt management and supply of water, particularly on dams and barrages along the Tigris and Euphrates rivers that have experienced threats or changes in sovereignty. Water supply is also under pressure from upstream water management, drought, and structural decline. In this research, we used a satellite-based algorithm, the normalized difference water index (NDWI), to monitor changes in the extent of surface reservoirs (1985-present). We compared the timeline of reservoir fluctuations with the timeline of events related to conflicts, droughts, and dam management. Our results show that the most sudden changes in water supply occurred during events related to conflict, but conflict was not often a cause of the greatest absolute changes to reservoir area. Though not as precise as on-the-ground information, satellite data can give insights to water supply when conflict has disrupted the flow of information or restricted on-the-ground data collection

    Measurements of thorium and uranium daughters in radioenvironmental samples using γγ-coincidence spectrometry

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    We present the performance of a γγ-coincidence spectrometer for measuring the activities of thorium and uranium daughters in environmental samples. The spectrometer consists of two NaI(Tl) detectors facing each other inside a low-background passive shield. We present coincidence gating schemes for achieving the best signal-to-noise ratios, coincidence detection efficiencies, background levels, and minimum detectable activities. The spectrometer is simulated using Geant4 to correct sample efficiencies for self-absorption effects. The device is used to measure thorium and uranium daughter activities in Brazil nuts, potting mix, and magazine paper. Our results for Brazil nuts agree with some, but not all, previous measurements. Thorium or uranium daughter activities have previously not been reported for commercial potting mix. For magazine paper, our measured activities are lower than most previously determined values

    The use of visual methods to explore how children construct and assign meaning to the ''self'' within two urban communities in the Western Cape, South Africa

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    This study aimed to explore how children construct and assign meaning to the ''self'' within two urban communities of Cape Town in South Africa. Using a child participation methodological framework data were collected using Photovoice and community maps with 54 participants between the ages of 9 and 12. Feelings of safety, social connectedness, and children's spaces were found to be central to the ways in which the participants constructed and assigned meaning to the ''self.'' The study provides implications for intervention programmes aimed at improving children's well-being to be inclusive of activities aimed at improving children's self-concept, including the construction of safe spaces for children to play, learn, and form meaningful relationships

    Multicolour correlative imaging using phosphor probes

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    Correlative light and electron microscopy exploits the advantages of optical methods, such as multicolour probes and their use in hydrated live biological samples, to locate functional units, which are then correlated with structural details that can be revealed by the superior resolution of electron microscopes. One difficulty is locating the area imaged by the electron beam in the much larger optical field of view. Multifunctional probes that can be imaged in both modalities and thus register the two images are required. Phosphor materials give cathodoluminescence (CL) optical emissions under electron excitation. Lanthanum phosphate containing thulium or terbium or europium emits narrow bands in the blue, green and red regions of the CL spectrum; they may be synthesised with very uniform-sized crystals in the 10- to 50-nm range. Such crystals can be imaged by CL in the electron microscope, at resolutions limited by the particle size, and with colour discrimination to identify different probes. These materials also give emissions in the optical microscope, by multiphoton excitation. They have been deposited on the surface of glioblastoma cells and imaged by CL. Gadolinium oxysulphide doped with terbium emits green photons by either ultraviolet or electron excitation. Sixty-nanometre crystals of this phosphor have been imaged in the atmospheric scanning electron microscope (JEOL ClairScope). This probe and microscope combination allow correlative imaging in hydrated samples. Phosphor probes should prove to be very useful in correlative light and electron microscopy, as fiducial markers to assist in image registration, and in high/super resolution imaging studies

    Inhibition of 12/15-Lipoxygenase Protects Against β-Cell Oxidative Stress and Glycemic Deterioration in Mouse Models of Type 1 Diabetes

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    Islet β-cell dysfunction and aggressive macrophage activity are early features in the pathogenesis of type 1 diabetes (T1D). 12/15-Lipoxygenase (12/15-LOX) is induced in β-cells and macrophages during T1D and produces proinflammatory lipids and lipid peroxides that exacerbate β-cell dysfunction and macrophage activity. Inhibition of 12/15-LOX provides a potential therapeutic approach to prevent glycemic deterioration in T1D. Two inhibitors recently identified by our groups through screening efforts, ML127 and ML351, have been shown to selectively target 12/15-LOX with high potency. Only ML351 exhibited no apparent toxicity across a range of concentrations in mouse islets, and molecular modeling has suggested reduced promiscuity of ML351 compared with ML127. In mouse islets, incubation with ML351 improved glucose-stimulated insulin secretion in the presence of proinflammatory cytokines and triggered gene expression pathways responsive to oxidative stress and cell death. Consistent with a role for 12/15-LOX in promoting oxidative stress, its chemical inhibition reduced production of reactive oxygen species in both mouse and human islets in vitro. In a streptozotocin-induced model of T1D in mice, ML351 prevented the development of diabetes, with coincident enhancement of nuclear Nrf2 in islet cells, reduced β-cell oxidative stress, and preservation of β-cell mass. In the nonobese diabetic mouse model of T1D, administration of ML351 during the prediabetic phase prevented dysglycemia, reduced β-cell oxidative stress, and increased the proportion of anti-inflammatory macrophages in insulitis. The data provide the first evidence to date that small molecules that target 12/15-LOX can prevent progression of β-cell dysfunction and glycemic deterioration in models of T1D

    Diabetes causes marked inhibition of mitochondrial metabolism in pancreatic β-cells

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    Diabetes is a global health problem caused primarily by the inability of pancreatic β-cells to secrete adequate levels of insulin. The molecular mechanisms underlying the progressive failure of β-cells to respond to glucose in type-2 diabetes remain unresolved. Using a combination of transcriptomics and proteomics, we find significant dysregulation of major metabolic pathways in islets of diabetic βV59M mice, a non-obese, eulipidaemic diabetes model. Multiple genes/proteins involved in glycolysis/gluconeogenesis are upregulated, whereas those involved in oxidative phosphorylation are downregulated. In isolated islets, glucose-induced increases in NADH and ATP are impaired and both oxidative and glycolytic glucose metabolism are reduced. INS-1 β-cells cultured chronically at high glucose show similar changes in protein expression and reduced glucose-stimulated oxygen consumption: targeted metabolomics reveals impaired metabolism. These data indicate hyperglycaemia induces metabolic changes in β-cells that markedly reduce mitochondrial metabolism and ATP synthesis. We propose this underlies the progressive failure of β-cells in diabetes.Peer reviewe
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