5,132 research outputs found

    The use of β-cell transcription factors in engineering artificial β cells from non-pancreatic tissue

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    Type 1 diabetes results from the autoimmune destruction of the insulin-producing pancreatic beta (β) cells. Patients with type 1 diabetes control their blood glucose levels using several daily injections of exogenous insulin; however, this does not eliminate the long-term complications of hyperglycaemia. Currently, the only clinically viable treatments for type 1 diabetes are whole pancreas and islet transplantation. As a result, there is an urgent need to develop alternative therapies. Recently, cell and gene therapy have shown promise as a potential cure for type 1 diabetes through the genetic engineering of 'artificial' β cells to regulate blood glucose levels without adverse side effects and the need for immunosuppression. This review compares putative target cells and the use of pancreatic transcription factors for gene modification, with the ultimate goal of engineering a glucose-responsive 'artificial' β cell that mimics the function of pancreatic β cells, while avoiding autoimmune destruction

    Diabetes reversal via gene transfer: building on successes in animal models

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    Type 1 diabetes (T1D) is caused by the autoimmune destruction of the insulin-producing pancreatic β-cells. People with T1D manage their hyperglycemia using daily insulin injections; however, this does not prevent the development of long-term diabetic complications such as retinopathy, nephropathy, neuropathy, and various macrovascular disorders. Currently, the only "cure" for T1D is pancreas transplantation or islet-cell transplantation; however, this is hampered by the limited number of donors and the requirement for life-long immunosuppression. As a result, the need for alternative therapies is vital. One of the strategies employed to correct T1D is the use of gene transfer to generate the production of an “artificial” β-cell that is capable of secreting insulin in response to fluctuating glucose concentrations that normally occurs in people without T1D. The treatment of many diseases using cell and gene therapy is generating significant attention in the T1D research community; however, for a cell therapy to enter clinical trials, success and safety must first be shown in an appropriate animal model. Animal models have been used in diabetes research for over a century, have improved our understanding of the pathophysiology of diabetes, and have led to the discovery of useful drugs for the treatment of the disease. Currently, the nonobese diabetic mouse is the animal model of choice for the study of T1D as it most closely reflects disease development in humans. The aim of this review is to evaluate the success of cell and gene therapy to reverse T1D in animal models for future clinical application

    Nonmethane hydrocarbon measurements in the North Atlantic Flight Corridor during the Subsonic Assessment Ozone and Nitrogen Oxide Experiment

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    Mixing ratios of nonmethane hydrocarbons (NMHCs) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX). NMHC enhancements were not detected within the general organized tracking system of the NAFC, nor during two tail chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute at all or contributes negligibly to NMHCs in the NAFC. Copyright 2000 by the American Geophysical Union

    Mindfulness-based stress reduction in Parkinson’s disease: a systematic review

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    Background: Mindfulness based stress reduction (MBSR) is increasingly being used to improve outcomes such as stress and depression in a range of long-term conditions (LTCs). While systematic reviews on MBSR have taken place for a number of conditions there remains limited information on its impact on individuals with Parkinson’s disease (PD). Methods: Medline, Central, Embase, Amed, CINAHAL were searched in March 2016. These databases were searched using a combination of MeSH subject headings where available and keywords in the title and abstracts. We also searched the reference lists of related reviews. Study quality was assessed based on questions from the Cochrane Collaboration risk of bias tool. Results: Two interventions and three papers with a total of 66 participants were included. The interventions were undertaken in Belgium (n = 27) and the USA (n = 39). One study reported significantly increased grey matter density (GMD) in the brains of the MBSR group compared to the usual care group. Significant improvements were reported in one study for a number of outcomes including PD outcomes, depression, mindfulness, and quality of life indicators. Only one intervention was of reasonable quality and both interventions failed to control for potential confounders in the analysis. Adverse events and reasons for drop-outs were not reported. There was also no reporting on the costs/benefits of the intervention or how they affected health service utilisation. Conclusion: This systematic review found limited and inconclusive evidence of the effectiveness of MBSR for PD patients. Both of the included interventions claimed positive effects for PD patients but significant outcomes were often contradicted by other results. Further trials with larger sample sizes, control groups and longer follow-ups are needed before the evidence for MBSR in PD can be conclusively judged

    Exponential Random Graph Modeling for Complex Brain Networks

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    Exponential random graph models (ERGMs), also known as p* models, have been utilized extensively in the social science literature to study complex networks and how their global structure depends on underlying structural components. However, the literature on their use in biological networks (especially brain networks) has remained sparse. Descriptive models based on a specific feature of the graph (clustering coefficient, degree distribution, etc.) have dominated connectivity research in neuroscience. Corresponding generative models have been developed to reproduce one of these features. However, the complexity inherent in whole-brain network data necessitates the development and use of tools that allow the systematic exploration of several features simultaneously and how they interact to form the global network architecture. ERGMs provide a statistically principled approach to the assessment of how a set of interacting local brain network features gives rise to the global structure. We illustrate the utility of ERGMs for modeling, analyzing, and simulating complex whole-brain networks with network data from normal subjects. We also provide a foundation for the selection of important local features through the implementation and assessment of three selection approaches: a traditional p-value based backward selection approach, an information criterion approach (AIC), and a graphical goodness of fit (GOF) approach. The graphical GOF approach serves as the best method given the scientific interest in being able to capture and reproduce the structure of fitted brain networks

    Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager

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    We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer ( CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two subgroups: protons and water group ions. We present the relative amounts of these two groups and the first estimates of their fluid parameters: ion density, flow velocity and temperature. We also compare this data with electron plasma measurements. Within the plasmasphere and inside of Enceladus' orbit, water group ions are about a factor of similar to 10 greater than protons in number with number densities exceeding 40 cm(-3). Within this inner region the spacecraft acquires a negative potential so that the electron density is underestimated. The electron and proton temperatures, which could not be measured in this region by Voyager, are T similar to 2 eVat L similar to 3. Also, within this inner region the protons, because of a negative spacecraft potential, appear to be super-corotating. By enforcing the condition that protons and water group ions are co-moving we may be able to acquire an independent estimate of the spacecraft potential relative to that estimated when comparing ion-electron measurements. Using our estimates of plasma properties, we estimate the importance of the rotating plasma on the stress balance equation for the inner magnetosphere and corresponding portion of the ring current

    Insulin trafficking in a glucose responsive engineered human liver cell line is regulated by the interaction of ATP-sensitive potassium channels and voltage- gated calcium channels

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    Type I diabetes is caused by the autoimmune destruction of pancreatic beta (â) cells [1]. Current treatment requires multiple daily injections of insulin to control blood glucose levels. Tight glucose control lowers, but does not eliminate, the onset of diabetic complications, which greatly reduce the quality and longevity of life for patients. Transplantation of pancreatic tissue as a treatment is restricted by the scarcity of donors and the requirement for lifelong immunosuppression to preserve the graft, which carries adverse side-effects. This is of particular concern as Type 1 diabetes predominantly affects children. Lack of glucose control could be overcome by genetically engineering "an artificial â-cell" that is capable of synthesising, storing and secreting insulin in response to metabolic signals. The donor cell type must be readily accessible and capable of being engineered to synthesise, process, store and secrete insulin under physiological conditions

    Sea-level constraints on the amplitude and source distribution of Meltwater Pulse 1A.

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    During the last deglaciation, sea levels rose as ice sheets retreated. This climate transition was punctuated by periods of more intense melting; the largest and most rapid of these—Meltwater Pulse 1A—occurred about 14,500 years ago, with rates of sea-level rise reaching approximately 4 m per century1, 2, 3. Such rates of rise suggest ice-sheet instability, but the meltwater sources are poorly constrained, thus limiting our understanding of the causes and impacts of the event4, 5, 6, 7. In particular, geophysical modelling studies constrained by tropical sea-level records1, 8, 9 suggest an Antarctic contribution of more than seven metres, whereas most reconstructions10 from Antarctica indicate no substantial change in ice-sheet volume around the time of Meltwater Pulse 1A. Here we use a glacial isostatic adjustment model to reinterpret tropical sea-level reconstructions from Barbados2, the Sunda Shelf3 and Tahiti1. According to our results, global mean sea-level rise during Meltwater Pulse 1A was between 8.6 and 14.6 m (95% probability). As for the melt partitioning, we find an allowable contribution from Antarctica of either 4.1 to 10.0 m or 0 to 6.9 m (95% probability), using two recent estimates11, 12 of the contribution from the North American ice sheets. We conclude that with current geologic constraints, the method applied here is unable to support or refute the possibility of a significant Antarctic contribution to Meltwater Pulse 1A

    Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager

    Get PDF
    We present an analysis of Saturn's inner plasmasphere as observed by the Cassini Plasma Spectrometer ( CAPS) experiment during Cassini's initial entry into Saturn's magnetosphere when the spacecraft was inserted into orbit around Saturn. The ion fluxes are divided into two subgroups: protons and water group ions. We present the relative amounts of these two groups and the first estimates of their fluid parameters: ion density, flow velocity and temperature. We also compare this data with electron plasma measurements. Within the plasmasphere and inside of Enceladus' orbit, water group ions are about a factor of similar to 10 greater than protons in number with number densities exceeding 40 cm(-3). Within this inner region the spacecraft acquires a negative potential so that the electron density is underestimated. The electron and proton temperatures, which could not be measured in this region by Voyager, are T similar to 2 eVat L similar to 3. Also, within this inner region the protons, because of a negative spacecraft potential, appear to be super-corotating. By enforcing the condition that protons and water group ions are co-moving we may be able to acquire an independent estimate of the spacecraft potential relative to that estimated when comparing ion-electron measurements. Using our estimates of plasma properties, we estimate the importance of the rotating plasma on the stress balance equation for the inner magnetosphere and corresponding portion of the ring current
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