75 research outputs found
Sequential Palladium-Catalyzed Allylic Alkylation/retro-Dieckmann Fragmentation Strategy for the Synthesis of α-Substituted Acrylonitriles.
A straightforward synthesis of α-substituted acrylonitriles is described using 4-cyano-3-oxotetrahydro-thiophene (c-THT) as an acrylonitrile surrogate. This unprecedented two-step sequence featuring a palladium-catalyzed allylic alkylation (Pd-AA) and a retro-Dieckmann fragmentation provides a general entry into diversely substituted 1,4-dienes
Ultrahigh frequency oscillations and multimode dynamics in vertical cavity surface emitting lasers
Includes bibliographical references (page 187).We report the observation of ultrahigh frequency oscillations of up to 240 GHz in optically gain switched vertical cavity surface emitting lasers. These oscillations are shown to be produced by multimode emission through mode competition (10-30 GHz) or mode beating (above 100 GHz). Although these oscillations are not related to the intrinsic modulation bandwidth, some of them could be mistaken for relaxation oscillations, calling for careful interpretation of the results of this type of experiments. The highest frequencies observed for single mode relaxation oscillations were about 9 GHz in agreement with values of modulation bandwidth reported in the literature
Transverse mode dynamics in vertical cavity surface emitting lasers excited by fast electrical pulses
Includes bibliographical references (page 592).We report measurements of the transient multimode dynamics of vertical cavity surface emittin glasers excited by short (100-200 ps rise times, 1 ns duration) electrical pulses. Fast changes on the spatial distribution of the output power and strong mode competition are observed. Numerical simulations show that the observed dynamics are due to the partial overlap of the different transverse modes through spatial hole burning
Identification of autoantigens and their potential post-translational modification in EGPA and severe eosinophilic asthma.
BACKGROUND: The chronic airway inflammation in severe eosinophilic asthma (SEA) suggests potential autoimmune aetiology with unidentified autoantibodies analogous to myeloperoxidase (MPO) in ANCA-positive EGPA (eosinophilic granulomatosis with polyangiitis). Previous research has shown that oxidative post-translational modification (oxPTM) of proteins is an important mechanism by which autoantibody responses may escape immune tolerance. Autoantibodies to oxPTM autoantigens in SEA have not previously been studied. METHODS: Patients with EGPA and SEA were recruited as well as healthy control participants. Autoantigen agnostic approach: Participant serum was incubated with slides of unstimulated and PMA-stimulated neutrophils and eosinophils, and autoantibodies to granulocytes were identified by immunofluorescence with anti-human IgG FITC antibody. Target autoantigen approach: Candidate proteins were identified from previous literature and FANTOM5 gene set analysis for eosinophil expressed proteins. Serum IgG autoantibodies to these proteins, in native and oxPTM form, were detected by indirect ELISA. RESULTS: Immunofluorescence studies showed that serum from patients with known ANCA stained for IgG against neutrophils as expected. In addition, serum from 9 of 17 tested SEA patients stained for IgG to PMA-stimulated neutrophils undergoing NETosis. Immunofluorescent staining of eosinophil slides was evident with serum from all participants (healthy and with eosinophilic disease) with diffuse cytoplasmic staining except for one SEA individual in whom subtle nuclear staining was evident. FANTOM5 gene set analysis identified TREM1 (triggering receptor expressed on myeloid cells 1) and IL-1 receptor 2 (IL1R2) as eosinophil-specific targets to test for autoantibody responses in addition to MPO, eosinophil peroxidase (EPX), and Collagen-V identified from previous literature. Indirect ELISAs found high concentrations of serum autoantibodies to Collagen-V, MPO, and TREM1 in a higher proportion of SEA patients than healthy controls. High concentrations of serum autoantibodies to EPX were evident in serum from both healthy and SEA participants. The proportion of patients with positive autoantibody ELISAs was not increased when examining oxPTM compared to native proteins. DISCUSSION: Although none of the target proteins studied showed high sensitivity for SEA, the high proportion of patients positive for at least one serum autoantibody shows the potential of more research on autoantibody serology to improve diagnostic testing for severe asthma. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifier, NCT04671446
A thiol redox sensor in soluble epoxide hydrolase enables oxidative activation by intra-protein disulfide bond formation
Soluble epoxide hydrolase (sEH), an enzyme that broadly regulates the cardiovascular system, hydrolyses epoxyeicosatrienoic acids (EETs) to their corresponding dihydroxyeicosatrienoic acids (DHETs). We previously showed that endogenous lipid electrophiles adduct within the catalytic domain, inhibiting sEH to lower blood pressure in angiotensin II-induced hypertensive mice. As angiotensin II increases vascular H2O2, we explored sEH redox regulation by this oxidant and how this integrates with inhibition by lipid electrophiles to regulate vasotone. Kinetics analyses revealed that H2O2 not only increased the specific activity of sEH but increased its affinity for substrate and increased its catalytic efficiency. This oxidative activation was mediated by formation of an intra-disulfide bond between C262 and C264, as determined by mass spectrometry and substantiated by biotin-phenylarsinate and thioredoxin-trapping mutant assays. C262S/264S sEH mutants were resistant to peroxide-induced activation, corroborating the disulfide-activation mechanism. The physiological impact of sEH redox state was determined in isolated arteries and the effect of the pro-oxidant vasopressor angiotensin II on arterial sEH redox state and vasodilatory EETs indexed in mice. Angiotensin II induced the activating intra-disulfide in sEH, causing a decrease in plasma EET/DHET ratios that is consistent with the pressor response to this hormone. Although sEH C262–C264 disulfide formation enhances hydrolysis of vasodilatory EETs, this modification also sensitized sEH to inhibition by lipid electrophiles. This explains why angiotensin II decreases EETs and increases blood pressure, but when lipid electrophiles are also present, that EETs are increased and blood pressure lowered
Lesion load may predict long-term cognitive dysfunction in multiple sclerosis patients.
Magnetic Resonance Imaging (MRI) techniques provided evidences into the understanding of cognitive impairment (CIm) in Multiple Sclerosis (MS).To investigate the role of white matter (WM) and gray matter (GM) in predicting long-term CIm in a cohort of MS patients.303 out of 597 patients participating in a previous multicenter clinical-MRI study were enrolled (49.4% were lost at follow-up). The following MRI parameters, expressed as fraction (f) of intracranial volume, were evaluated: cerebrospinal fluid (CSF-f), WM-f, GM-f and abnormal WM (AWM-f), a measure of lesion load. Nine years later, cognitive status was assessed in 241 patients using the Symbol Digit Modalities Test (SDMT), the Semantically Related Word List Test (SRWL), the Modified Card Sorting Test (MCST), and the Paced Auditory Serial Addition Test (PASAT). In particular, being SRWL a memory test, both immediate recall and delayed recall were evaluated. MCST scoring was calculated based on the number of categories, number of perseverative and non-perseverative errors.AWM-f was predictive of an impaired performance 9 years ahead in SDMT (OR 1.49, CI 1.12–1.97 p = 0.006), PASAT (OR 1.43, CI 1.14–1.80 p = 0.002), SRWL-immediate recall (OR 1.72 CI 1.35–2.20 p<0.001), SRWL-delayed recall (OR 1.61 CI 1.28–2.03 p<0.001), MCST-category (OR 1.52, CI 1.2–1.9 p<0.001), MCST-perseverative error(OR 1.51 CI 1.2–1.9 p = 0.001), MCST-non perseverative error (OR 1.26 CI 1.02–1.55 p = 0.032).In our large MS cohort, focal WM damage appeared to be the most relevant predictor of the long-term cognitive outcome
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS) databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history, and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among national and international groups
The Italian multiple sclerosis register
The past decade has seen extraordinary increase in worldwide availability of and access to several large multiple sclerosis (MS)
databases and registries. MS registries represent powerful tools to provide meaningful information on the burden, natural history,
and long-term safety and effectiveness of treatments. Moreover, patients, physicians, industry, and policy makers have an active
interest in real-world observational studies based on register data, as they have the potential to answer the questions that are most
relevant to daily treatment decision-making. In 2014, the Italian MS Foundation, in collaboration with the Italian MS clinical
centers, promoted and funded the creation of the Italian MS Register, a project in continuity with the existing Italian MS Database
Network set up from 2001. Main objective of the Italian MS Register is to create an organized multicenter structure to collect data
of all MS patients for better defining the disease epidemiology, improving quality of care, and promoting research projects in
high-priority areas. The aim of this article is to present the current framework and network of the Italian MS register, including the
methodology used to improve the quality of data collection and to facilitate the exchange of data and the collaboration among
national and international groups
Data monitoring roadmap. The experience of the Italian Multiple Sclerosis and Related Disorders Register
Introduction Over the years, disease registers have been increasingly considered a source of reliable and valuable population studies. However, the validity and reliability of data from registers may be limited by missing data, selection bias or data quality not adequately evaluated or checked.This study reports the analysis of the consistency and completeness of the data in the Italian Multiple Sclerosis and Related Disorders Register.MethodsThe Register collects, through a standardized Web-based Application, unique patients.Data are exported bimonthly and evaluated to assess the updating and completeness, and to check the quality and consistency. Eight clinical indicators are evaluated.ResultsThe Register counts 77,628 patients registered by 126 centres. The number of centres has increased over time, as their capacity to collect patients.The percentages of updated patients (with at least one visit in the last 24 months) have increased from 33% (enrolment period 2000-2015) to 60% (enrolment period 2016-2022). In the cohort of patients registered after 2016, there were >= 75% updated patients in 30% of the small centres (33), in 9% of the medium centres (11), and in all the large centres (2).Clinical indicators show significant improvement for the active patients, expanded disability status scale every 6 months or once every 12 months, visits every 6 months, first visit within 1 year and MRI every 12 months.ConclusionsData from disease registers provide guidance for evidence-based health policies and research, so methods and strategies ensuring their quality and reliability are crucial and have several potential applications
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