34 research outputs found

    Non-linear microwave impedance of short and long Josephson Junctions

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    The non-linear dependence on applied acac field (bωb_{\omega}) or current (iω% i_{\omega}) of the microwave (ac) impedance Rω+iXωR_{\omega}+iX_{\omega} of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current anti-symmetric) and field anti-symmetric (current symmetric) excitation configurations.The resistance shows step-like features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors, and new effects are suggested. When a % dc field (bdcb_{dc}) or current (idci_{dc}) is applied, interesting phase locking effects are observed in the ac impedance ZωZ_{\omega}. In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a cos(ϕ)\cos (\phi) potential in the overdamped limit and subjected to an ac drive.Comment: 7 pages, 11 figure

    Effect of Treatment, during Primary Infection, on Establishment and Clearance of Cellular Reservoirs of HIV-1

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    Patients in whom virologic suppression is achieved with highly active antiretroviral therapy (HAART) retain long-lived cellular reservoirs of human immunodeficiency virus type 1 (HIV-1); this retention is an obstacle to sustained control of infection. To assess the impact that initiating treatment during primary HIV-1 infection has on this cell population, we analyzed the decay kinetics of HIV-1 DNA and of infectivity associated with cells activated ex vivo in 27 patients who initiated therapy before or <6 months after seroconversion and in whom viremia was suppressed to <50 copies/mL. The clearance rates of cellular reservoirs could not be distinguished by these techniques (median half-life, 20 weeks) during the first year of HAART. The clearance of HIV-1 DNA slowed significantly during the subsequent 3 years of treatment (median half-life, 70 weeks), consistent with heterogeneous cellular reservoirs being present. Total cell-associated infectivity (CAI) after 1 year of treatment was undetectable (<0.07 infectious units/million cells [IUPM]) in most patients initiating treatment during primary infection either before (9/9) or <6 months after (6/8) seroconversion. In contrast, all 17 control patients who initiated HAART during chronic infection retained detectable CAI after 3-6 years of treatment (median reservoir size, 1.1 IUPM; P<.0005). These results suggest that treatment <6 months after seroconversion may facilitate long-term control of cellular reservoirs that maintain HIV-1 infection during treatmen

    Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

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    Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

    Targeted gene sanger sequencing should remain the first-tier genetic test for children suspected to have the five common X-linked inborn errors of immunity

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    DATA AVAILABILITY STATEMENT : The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author.To address inborn errors of immunity (IEI) which were underdiagnosed in resource-limited regions, our centre developed and offered free genetic testing for the most common IEI by Sanger sequencing (SS) since 2001. With the establishment of The Asian Primary Immunodeficiency (APID) Network in 2009, the awareness and definitive diagnosis of IEI were further improved with collaboration among centres caring for IEI patients from East and Southeast Asia. We also started to use whole exome sequencing (WES) for undiagnosed cases and further extended our collaboration with centres from South Asia and Africa. With the increased use of Next Generation Sequencing (NGS), we have shifted our diagnostic practice from SS to WES. However, SS was still one of the key diagnostic tools for IEI for the past two decades. Our centre has performed 2,024 IEI SS genetic tests, with in-house protocol designed specifically for 84 genes, in 1,376 patients with 744 identified to have disease-causing mutations (54.1%). The high diagnostic rate after just one round of targeted gene SS for each of the 5 common IEI (X-linked agammaglobulinemia (XLA) 77.4%, Wiskott–Aldrich syndrome (WAS) 69.2%, X-linked chronic granulomatous disease (XCGD) 59.5%, X-linked severe combined immunodeficiency (XSCID) 51.1%, and X-linked hyper-IgM syndrome (HIGM1) 58.1%) demonstrated targeted gene SS should remain the first-tier genetic test for the 5 common X-linked IEI.The Hong Kong Society for Relief of Disabled Children and Jeffrey Modell Foundation.http://www.frontiersin.org/Immunologyam2023Paediatrics and Child Healt

    Identification of paclitaxel resistance through a new statistical approach based on a random forest of perfect trees classifcation

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    International audienceBackground: Predictors of paclitaxel sensitivity in breast cancer published ten years ago, are still pending. The authors showed that paclitaxel pathological complete response (pCR) was in one hand, encountered in aggressive breast tumor with immune response and in another hand, paclitaxel resistance in less aggressive tumor. We have developed a new analysis paradigm, mixing neurons into nodes of trees classification and news class of statistical information based on free-error trees classification. We proposed to reanalyze the Bauer et al’s dataset using this novel approach. Methods: GES22513 dataset including 14 duplicated observations and 54675 anonymized probes was analyzed. A random forest of one million trees whose nodes were composed of neurons including 15 probes, was developped. We selected probes for which a free-error classification was obtained and ranked them according to the inverse of the probability of being a confounding factor and to the inverse of the probability of interacting with another probe. We compared the sets of probes which were necessary to obtain an error-free classification between those associated with a decrease and those associated with an increase of the probability of pCR. Results: Our 15 best ranked predictors were free-error classification for all observations. This includes gene expression of TLCD2, BRCC3, CHI3L2 and PROX1. Their over-expressions were associated with an increase in the probability of pCR, and gene expression of APH1B, ARFGEF1, ARID2, BPGM, CAMK2N1, CCNY, PARM1, PHKA1, PSMD9, SUDS3 (two probes) whose over-expressions are associated with a decrease in the probability of pCR. Ten out of these probes were concordant with Bauer et al’s conclusion. Four probes ( BPGM, PHKA1, CCNY and ARFGEF1) are in contradiction with it. The limited biological information were available for TLCD2. The statistical analysis also showed that TLCD2, BBRCC3, CHI3L2 and PROX1 were altogether positively modulated by eight genes/probes ( CKS1B, ADIG, NCR3, RIN3, NIPAL1, 234422_at, DCLRE1C, SLC17A4). At the opposite, the modulation of genes associated with a decrease in the probability of pCR, was rather heterogeneous and involves many more genes. Conclusions: This preliminary work shows that our statistical approach allows a perfect classification of tumors with and without pCR. Also, it proves that the selected probes/genes are respectively associated with aggressiveness/basal and less aggressiveness/luminal phenotypes. These results need to be validated on an independent cohort

    Random forest of perfect trees: concept, performance, applications and perspectives

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    International audienceAbstract Motivation The principle of Breiman's random forest (RF) is to build and assemble complementary classification trees in a way that maximizes their variability. We propose a new type of random forest that disobeys Breiman’s principles and involves building trees with no classification errors in very large quantities. We used a new type of decision tree that uses a neuron at each node as well as an in-innovative half Christmas tree structure. With these new RFs, we developed a score, based on a family of ten new statistical information criteria, called Nguyen information criteria (NICs), to evaluate the predictive qualities of features in three dimensions. Results The first NIC allowed the Akaike information criterion to be minimized more quickly than data obtained with the Gini index when the features were introduced in a logistic regression model. The selected features based on the NICScore showed a slight advantage compared to the support vector machines—recursive feature elimination (SVM-RFE) method. We demonstrate that the inclusion of artificial neurons in tree nodes allows a large number of classifiers in the same node to be taken into account simultaneously and results in perfect trees without classification errors. Availability and implementation The methods used to build the perfect trees in this article were implemented in the ‘ROP’ R package, archived at https://cran.r-project.org/web/packages/ROP/index.html. Supplementary information Supplementary data are available at Bioinformatics online

    Interactions between cancer-associated fibroblasts and tumor cells promote MCL-1 dependency in estrogen receptor-positive breast cancers

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    International audienceSelective inhibition of BCL-2 is expected to enhance therapeutic vulnerability in luminal estrogen receptor-positive breast cancers. We show here that the BCL-2 dependency of luminal tumor cells is nevertheless mitigated by breast cancer-associated fibroblasts (bCAFs) in a manner that defines MCL-1 as another critical therapeutic target. bCAFs favor MCL-1 expression and apoptotic resistance in luminal cancer cells in a IL-6 dependent manner while their own, robust, survival also relies on MCL-1. Studies based on ex vivo cultures of human luminal breast cancer tissues further argue that the contribution of stroma-derived signals to MCL-1 expression shapes BCL-2 dependency. Thus, MCL-1 inhibitors are beneficial for targeted apoptosis of breast tumor ecosystems, even in a subtype where MCL-1 dependency is not intrinsically driven by oncogenic pathways
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