20 research outputs found

    Double percolation effects and fractal behavior in magnetic/superconducting hybrids

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    Perpendicular magnetic anisotropy ferromagnetic/ superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network.Comment: 15 pages, 5 figure

    Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions

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    Magnetic lateral multilayers have been fabricated on weak perpendicular magnetic anisotropy amorphous Nd-Co films in order to perform a systematic study on the conditions for controlled nucleation of topological defects within their magnetic stripe domain pattern. A lateral thickness modulation of period ww is defined on the nanostructured samples that, in turn, induces a lateral modulation of both magnetic stripe domain periods λ\lambda and average in-plane magnetization component MinplaneM_{inplane}. Depending on lateral multilayer period and in-plane applied field, thin and thick regions switch independently during in-plane magnetization reversal and domain walls are created within the in-plane magnetization configuration coupled to variable angle grain boundaries and disclinations within the magnetic stripe domain patterns. This process is mainly driven by the competition between rotatable anisotropy (that couples the magnetic stripe pattern to in-plane magnetization) and in-plane shape anisotropy induced by the periodic thickness modulation. However, as the structural period ww becomes comparable to magnetic stripe period λ\lambda, the nucleation of topological defects at the interfaces between thin and thick regions is hindered by a size effect and stripe domains in the different thickness regions become strongly coupled.Comment: 10 pages, 7 figures, submitted to Physical Review

    Optimal doses of rifampicin in the standard drug regimen to shorten tuberculosis treatment duration and reduce relapse by eradicating persistent bacteria.

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    Objectives: Although high-dose rifampicin holds promise for improving tuberculosis disease control by eradication of persistent bacteria, the optimal dose of rifampicin that kills persistent bacteria and shortens the treatment duration is unknown. Methods: The Cornell mouse model was used to test the efficacy of rifampicin at elevated doses combined with isoniazid and pyrazinamide to kill actively growing and persistent bacilli and to measure relapse rate. Persistent bacteria were evaluated using Mycobacterium tuberculosis culture supernatant containing resuscitation-promoting factors. Pharmacokinetic parameters and dose-dependent activity for cultivable and persistent bacilli were determined. Results: Increasing doses of rifampicin in combination with isoniazid and pyrazinamide resulted in dose-dependent faster bacterial clearance. Evaluated both on solid media and in culture filtrate containing resuscitation-promoting factors, a regimen containing a standard dose of rifampicin at 10 mg/kg over 14 weeks failed to achieve organ sterility. In contrast, higher doses of rifampicin achieved organ sterility in a much shorter time of 8-11 weeks. Disease relapse, which occurred in 86% of mice treated with the standard regimen for 14 weeks, was completely prevented by rifampicin doses of ≥ 30 mg/kg. Conclusions: In the treatment of murine tuberculosis, a rifampicin dose of 30 mg/kg was sufficient to eradicate persistent M. tuberculosis, allowing shorter treatment duration without disease relapse

    Investigation of elimination rate, persistent subpopulation removal and relapse rates of Mycobacterium tuberculosis by combinations of first-line drugs in a modified Cornell mouse model.

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    Currently, the most effective tuberculosis control method resides in case-finding and 6 months chemotherapy. There is a need to improve our understanding about drug interactions, combination activities and the ability to remove persistent bacteria in the current regimens, particularly in relation to relapse. We aimed to investigate the therapeutic effects of three main components, rifampicin (RMP), isoniazid (INH), and pyrazinamide (PZA), in current drug regimens using a modified version of the Cornell mouse model. We evaluated the post-treatment levels of persistent Mycobacterium tuberculosis in the organs of mice using culture filtrate derived from M. tuberculosis strain H37Rv. When RMP was combined with INH, PZA or INH-PZA, significant additive activities were observed compared to each of the single drug treatments. However, the combination of INH and PZA showed a less significant additive effect than either of the drugs used on their own. Apparent culture negativity of mouse organs was achieved at 14 weeks of treatment with RMP-INH, RMP-PZA and RMP-INH-PZA but not with INH-PZA, when conventional tests, namely culture on solid agar and in liquid broth indicated that the organs were bacteria negative. The relapse rates for RMP-containing regimens were not significantly different to a 100% relapse rate at the numbers of mice examined in this study. In parallel, we examined the organs for the presence of culture filtrate-dependent persistent bacilli after 14 weeks of treatment. Culture filtrate treatment of the organs revealed persistent M. tuberculosis Modelling of mycobacterial elimination rates and evaluation of culture-filtrate dependent organisms showed promise as surrogate methods for efficient factorial evaluation of drug combinations in tuberculosis in mouse models and should be further evaluated against relapse. The presence of culture filtrate-dependent persistent M. tuberculosis is the likely cause of disease relapse in this modified Cornell mouse model

    Double percolation effects and fractal behavior in magnetic/superconducting hybrids

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    Perpendicular magnetic anisotropy ferromagnetic/superconducting (FM/SC) bilayers with a labyrinth domain structure are used to study nucleation of superconductivity on a fractal network, tunable through magnetic history. As clusters of reversed domains appear in the FM layer, the SC film shows a percolative behavior that depends on two independent processes: the arrangement of initial reversed domains and the fractal geometry of expanding clusters. For a full labyrinth structure, the behavior of the upper critical field is typical of confined superconductivity on a fractal network

    Clinico-pathological characteristics and outcomes of patients with early-onset colorectal cancer

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    [Background]: The rising incidence of colorectal cancer (CRC) among young patients is alarming. We aim to characterize the clinico-pathological features and outcomes of patients with early-onset CRC (EOCRC). [Methods]: We included all of the patients with pathologically confirmed diagnosis of CRC at Hospital Universitario La Paz from October 2016 to September 2020. EOCRC age cut-off was 50 years. All statistical analyses were carried out using SPSS v.25. [Results]: A total of 1152 patients were diagnosed with CRC, fifty-nine (5,1%) of them were After a median follow-up of 24 months, 279 patients have died. Median overall survival (OS) was not reached in either group (p = 0,06). Three-year OS was 80% (95%CI: 73-87) and 67 (95%CI: 65-69) in the younger and older group, respectively. In patients with localized disease that underwent surgery or other antineoplastic treatment ( n = 856), 159 events for disease-free survival (DFS) were observed. Median DFS was [Conclusions]: Patients with EOCRC are diagnosed at a more advanced stage and display distinct biological features (more prevalence of dMMR and WT tumors among others). Studies focusing on screening in this population and deeper molecular profiling are needed

    Clinico-pathological characteristics and outcomes of patients with early-onset colorectal cancer

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    [Background]: The rising incidence of colorectal cancer (CRC) among young patients is alarming. We aim to characterize the clinico-pathological features and outcomes of patients with early-onset CRC (EOCRC).[Methods]: We included all of the patients with pathologically confirmed diagnosis of CRC at Hospital Universitario La Paz from October 2016 to September 2020. EOCRC age cut-off was 50 years. All statistical analyses were carried out using SPSS v.25. [Results]: A total of 1152 patients were diagnosed with CRC, fifty-nine (5,1%) of them were After a median follow-up of 24 months, 279 patients have died. Median overall survival (OS) was not reached in either group (p ¼ 0,06). Three-year OS was 80% (95% CI: 73-87) and 67 (95%CI: 65-69) in the younger and older group, respectively. In patients with localized disease that underwent surgery or other antineoplastic treatment ( n ¼ 856), 159 events for disease-free survival (DFS) were observed. Median DFS was not reached in either group (p ¼0,144). Three-year DFS was 86% (95%CI: 79-93) and 73% (95%CI: 71-75, respectively). In patients with metastatic disease (n ¼ 332; synchronous or metachronic), median OS was not reach in the EOCRC group vs 18,1 (95%CI: 13,8-22,4), p ¼ 0,05). In those patients with metastatic EOCRC with mutational status assessed (n ¼23), no difference in OS according to RAS was observed (p ¼ 0,55).[Conclusions]: Patients with EOCRC are diagnosed at a more advanced stage and display distinct biological features (more prevalence of dMMR and WT tumors among others). Studies focusing on screening in this population and deeper molecular profiling are needed.Peer reviewe

    Interaction Testing and Polygenic Risk Scoring to Estimate the Association of Common Genetic Variants with Treatment Resistance in Schizophrenia

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    Importance: About 20% to 30% of people with schizophrenia have psychotic symptoms that do not respond adequately to first-line antipsychotic treatment. This clinical presentation, chronic and highly disabling, is known as treatment-resistant schizophrenia (TRS). The causes of treatment resistance and their relationships with causes underlying schizophrenia are largely unknown. Adequately powered genetic studies of TRS are scarce because of the difficulty in collecting data from well-characterized TRS cohorts. Objective: To examine the genetic architecture of TRS through the reassessment of genetic data from schizophrenia studies and its validation in carefully ascertained clinical samples. Design, Setting, and Participants: Two case-control genome-wide association studies (GWASs) of schizophrenia were performed in which the case samples were defined as individuals with TRS (n = 10501) and individuals with non-TRS (n = 20325). The differences in effect sizes for allelic associations were then determined between both studies, the reasoning being such differences reflect treatment resistance instead of schizophrenia. Genotype data were retrieved from the CLOZUK and Psychiatric Genomics Consortium (PGC) schizophrenia studies. The output was validated using polygenic risk score (PRS) profiling of 2 independent schizophrenia cohorts with TRS and non-TRS: a prevalence sample with 817 individuals (Cardiff Cognition in Schizophrenia [CardiffCOGS]) and an incidence sample with 563 individuals (Genetics Workstream of the Schizophrenia Treatment Resistance and Therapeutic Advances [STRATA-G]). Main Outcomes and Measures: GWAS of treatment resistance in schizophrenia. The results of the GWAS were compared with complex polygenic traits through a genetic correlation approach and were used for PRS analysis on the independent validation cohorts using the same TRS definition. Results: The study included a total of 85490 participants (48635 [56.9%] male) in its GWAS stage and 1380 participants (859 [62.2%] male) in its PRS validation stage. Treatment resistance in schizophrenia emerged as a polygenic trait with detectable heritability (1% to 4%), and several traits related to intelligence and cognition were found to be genetically correlated with it (genetic correlation, 0.41-0.69). PRS analysis in the CardiffCOGS prevalence sample showed a positive association between TRS and a history of taking clozapine (r2 = 2.03%; P =.001), which was replicated in the STRATA-G incidence sample (r2 = 1.09%; P =.04). Conclusions and Relevance: In this GWAS, common genetic variants were differentially associated with TRS, and these associations may have been obscured through the amalgamation of large GWAS samples in previous studies of broadly defined schizophrenia. Findings of this study suggest the validity of meta-analytic approaches for studies on patient outcomes, including treatment resistance
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