1,097 research outputs found

    Evidence for B cell exhaustion in chronic graft-versus-host disease

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    Chronic graft-versus-host disease (cGvHD) remains a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). A number of studies support a role for B cells in the pathogenesis of cGvHD. In this study, we report the presence of an expanded population of CD19+CD21− B cells with features of exhaustion in the peripheral blood of patients with cGvHD. CD21− B cells were significantly increased in patients with active cGvHD compared to patients without cGvHD and healthy controls (median 12.2 versus 2.12 versus 3%, respectively; p < 0.01). Compared with naïve (CD27−CD21+) and classical memory (CD27+CD21+) B cells, CD19+CD21− B cells in cGvHD were CD10 negative, CD27 negative and CD20hi, and exhibited features of exhaustion, including increased expression of multiple inhibitory receptors such as FCRL4, CD22, CD85J, and altered expression of chemokine and adhesion molecules such as CD11c, CXCR3, CCR7, and CD62L. Moreover, CD21− B cells in cGvHD patients were functionally exhausted and displayed poor proliferative response and calcium mobilization in response to B-cell receptor triggering and CD40 ligation. Finally, the frequencies of circulating CD21− B cells correlated with cGvHD severity in patients after HSCT. Our study further characterizes B cells in chronic cGVHD and supports the use of CD21−CD27−CD10− B cell frequencies as a biomarker of disease severity

    Aromatase inhibitors and antiepileptic drugs: a computational systems biology analysis

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    <p>Abstract</p> <p>Background</p> <p>The present study compares antiepileptic drugs and aromatase (CYP19) inhibitors for chemical and structural similarity. Human aromatase is well known as an important pharmacological target in anti-breast cancer therapy, but recent research demonstrates its role in epileptic seizures, as well. The current antiepileptic treatment methods cause severe side effects that endanger patient health and often preclude continued use. As a result, less toxic and more tolerable antiepileptic drugs (AEDs) are needed, especially since every individual responds differently to given treatment options.</p> <p>Methods</p> <p>Through a pharmacophore search, this study shows that a model previously designed to search for new classes of aromatase inhibitors is able to identify antiepileptic drugs from the set of drugs approved by the Food and Drug Administration. Chemical and structural similarity analyses were performed using five potent AIs, and these studies returned a set of AEDs that the model identifies as hits.</p> <p>Results</p> <p>The pharmacophore model returned 73% (19 out of 26) of the drugs used specifically to treat epilepsy and approximately 82% (51 out of 62) of the compounds with anticonvulsant properties. Therefore, this study supports the possibility of identifying AEDs with a pharmacophore model that had originally been designed to identify new classes of aromatase inhibitors. Potential candidates for anticonvulsant therapy identified in this manner are also reported. Additionally, the chemical and structural similarity between antiepileptic compounds and aromatase inhibitors is proved using similarity analyses.</p> <p>Conclusions</p> <p>This study demonstrates that a pharmacophore search using a model based on aromatase inhibition and the enzyme's structural features can be used to screen for new candidates for antiepileptic therapy. In fact, potent aromatase inhibitors and current antiepileptic compounds display significant - over 70% - chemical and structural similarity, and the similarity analyses performed propose a number of antiepileptic compounds with high potential for aromatase inhibition.</p

    Forward ray tracing for image projection prediction and surface reconstruction in the evaluation of corneal topography systems

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    A forward ray tracing (FRT) model is presented to determine the exact image projection in a general corneal topography system. Consequently, the skew ray error in Placido-based topography is demonstrated. A quantitative analysis comparing FRT-based algorithms and Placido-based algorithms in reconstructing the front surface of the cornea shows that arc step algorithms are more sensitive to noise (imprecise). Furthermore, they are less accurate in determining corneal aberrations particularly the quadrafoil aberration. On the other hand, FRT-based algorithms are more accurate and more precise showing that point to point corneal topography is superior compared to its Placido-based counterpart

    Experimental Study of Choking Flow of Water at Supercritical Conditions

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    Les prochaines générations de réacteurs nucléaires vont opérer avec un fluide de refroidissement dont la pression sera près de 25 MPa et dont la température de sortie sera de 500°C à 625°C, selon le type de réacteur. En conséquence, l’enthalpie du flux de sortie de ces futurs réacteurs à eau supercritique, SCWR, «Supercritical Water-Cooled Reactors» sera beaucoup plus élevée que celle des réacteurs actuels. Cela permettra à l’efficacité des centrales nucléaires de passer d’environ 30-33% aujourd’hui jusqu’à 48%. Cependant, le comportement thermo-hydraulique de l’eau supercritique n’est pas encore bien compris sous de telles conditions d’écoulement, notamment en ce qui concerne par exemple les chutes de pression, la convection forcée, la détérioration du transfert de chaleur et le flux massique critique. Jusqu’à maintenant, seul un nombre très limité de recherches ont été effectuées utilisant des fluides en conditions supercritiques. De plus, ces recherches n’ont pas été effectuées dans des conditions représentatives des SCWR. Aussi, les données existantes au sujet du flux massique critique ont été recueillies lors d’expériences dont la pression de décharge était celle de l’atmosphère ambiante, et dans la plupart des cas en utilisant des fluides autres que l’eau. Il est à noter que la compréhension de l’écoulement critique des fluides supercritiques est essentielle pour effectuer les analyses de sûreté des futurs réacteurs nucléaires et pour concevoir leurs principaux composants mécaniques, par exemple, les valves de contrôle et les vannes de sûreté. Ainsi donc, une installation d’eau supercritique a été construite à l’École Polytechnique de Montréal pour effectuer des recherches sur le débit critique. Ce montage expérimental consiste en deux boucles fonctionnant en parallèle, servant à déterminer les conditions d’écoulement qui déclenchent le débit critique de l’eau supercritique. Cette installation est également en mesure d’effectuer des expériences de transfert de chaleur et de perte de pression utilisant de l’eau en conditions supercritiques. Dans cette thèse, seront présentés les résultats obtenus grâce à cette installation avec l’utilisation d’une section d’essais munie d’un orifice de 1 mm de diamètre interne et de 3,17 mm de longueur, et dont les rebords sont acérés. Ainsi, 545 points de données de flux massique critique ont été obtenus en conditions supercritiques, pour des pressions d’écoulement allant de 22,1 MPa à 32,1MPa, et à des températures d’écoulement allant de 50°C à 502°C, et ce pour des pressions de décharges 0,1 MPa à 3,6 MPa.----------Abstract Future nuclear reactors will operate at a coolant pressure close to 25 MPa and at outlet temperatures ranging from 500oC to 625°C. As a result, the outlet flow enthalpy in future Supercritical Water-Cooled Reactors (SCWR) will be much higher than those of actual ones which can increase overall nuclear plant efficiencies up to 48%. However, under such flow conditions, the thermal-hydraulic behavior of supercritical water is not fully known, e.g., pressure drop, forced convection and heat transfer deterioration, critical and blowdown flow rate, etc. Up to now, only a very limited number of studies have been performed under supercritical conditions. Moreover, these studies are conducted at conditions that are not representative of future SCWRs. In addition, existing choked flow data have been collected from experiments at atmospheric discharge pressure conditions and in most cases by using working fluids different than water which constrain researchers to analyze the data correctly. In particular, the knowledge of critical (choked) discharge of supercritical fluids is mandatory to perform nuclear reactor safety analyses and to design key mechanical components (e.g., control and safety relief valves, etc.). Hence, an experimental supercritical water facility has been built at École Polytechnique de Montréal which allows researchers to perform choking flow experiments under supercritical conditions. The facility can also be used to carry out heat transfer and pressure drop experiments under supercritical conditions. In this thesis, we present the results obtained at this facility using a test section that contains a 1 mm inside diameter, 3.17 mm long orifice plate with sharp edges. Thus, 545 choking flow of water data points are obtained under supercritical conditions for flow pressures ranging from 22.1 MPa to 32.1 MPa, flow temperatures ranging from 50°C to 502°C and for discharge pressures from 0.1 MPa to 3.6 MPa. Obtained data are compared with the data given in the literature including those collected with fluids other than water. It is also important to mention that present models used to predict supercritical choking flows have been developed for fluids under subcritical conditions. Even though none of these models were developed to handle the expansion of supercritical fluids, we tested some of the models (Homogenous Equilibrium Model, Modified-Homogeneous Equilibrium Model and Bernoulli equation) under supercritical conditions and compared their predictions with our data and those of other researchers, available in the literature. In addition, a simple polytropic model is proposed to estimate the critical flow rate of water

    Bacillus Cereus Catheter Related Bloodstream Infection in a Patient with Acute Lymphoblastic Leukemia

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    Bacillus cereus infection is rarely associated with actual infection and for this reason single positive blood culture is usually regarded as contamination . However it may cause a number of infections, such catheter-related bloodstream infections. Significant catheter-related bloodstream infections (CRBSI) caused by Bacillus spp. are mainly due to B. cereus and have been predominantly reported in immunocompromised hosts. Catheter removal is generally advised for management of infection. In this report, catheter-related bacteremia caused by B. cereus in a patient with acute lymphoblast c leukemia (ALL) in Istanbul Medical Faculty was presented

    Benchmarking Differential Privacy and Federated Learning for BERT Models

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    Natural Language Processing (NLP) techniques can be applied to help with the diagnosis of medical conditions such as depression, using a collection of a person's utterances. Depression is a serious medical illness that can have adverse effects on how one feels, thinks, and acts, which can lead to emotional and physical problems. Due to the sensitive nature of such data, privacy measures need to be taken for handling and training models with such data. In this work, we study the effects that the application of Differential Privacy (DP) has, in both a centralized and a Federated Learning (FL) setup, on training contextualized language models (BERT, ALBERT, RoBERTa and DistilBERT). We offer insights on how to privately train NLP models and what architectures and setups provide more desirable privacy utility trade-offs. We envisage this work to be used in future healthcare and mental health studies to keep medical history private. Therefore, we provide an open-source implementation of this work.Comment: 4 pages, 3 tables, 1 figur
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