176 research outputs found
On the non-abelian superalgebra spanned by the conserved quantities of N=1 supersymmetric Korteweg-de Vries equation
We obtain an infinite sequence of bosonic non-local conserved quantities for
the N=1 supersymmetric Korteweg-de Vries equation. It is generated from a
bosonic non-local conserved quantity of Super Gardner equation. In distinction
to the already known one with odd parity and dimension 1/2, it has even parity
and dimension 1. It fits exactly in the supersymmetric cohomology in the space
of conserved quantities that we also introduce here. Using results from this
cohomology we obtain the Poisson bracket of several non-local conserved
quantities, including the already known odd ones and the new even ones. The
algebra closes in terms of polynomials of local and non-local conserved
quantities. We prove that the bosonic non-local conserved quantities cannot be
expressed as functions of the already known local and non-local conserved
quantities of Super KdV equation.Comment: To be published in: Physics Letters A. 16 page
Evolution of Blood-Brain Barrier Permeability in Subacute Ischemic Stroke and Associations With Serum Biomarkers and Functional Outcome
Background and Purpose: In the setting of acute ischemic stroke, increased blood-brain barrier permeability (BBBP) as a sign of injury is believed to be associated with increased risk of poor outcome. Pre-clinical studies show that selected serum biomarkers including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha), matrix metallopeptidases (MMP), and vascular endothelial growth factors (VEGFs) may play a role in BBBP post-stroke. In the subacute phase of stroke, increased BBBP may also be caused by regenerative mechanisms such as vascular remodeling and therefore may improve functional recovery. Our aim was to investigate the evolution of BBBP in ischemic stroke using contrast-enhanced (CE) magnetic resonance imaging (MRI) and to analyze potential associations with blood-derived biomarkers as well as functional recovery in subacute ischemic stroke patients.
Methods: This is an exploratory analysis of subacute ischemic stroke patients enrolled in the BAPTISe study nested within the randomized controlled PHYS-STROKE trial (interventions: 4 weeks of aerobic fitness training vs. relaxation). Patients with at least one CE-MRI before (v1) or after (v2) the intervention were eligible for this analysis. The prevalence of increased BBBP was visually assessed on T1-weighted MR-images based on extent of contrast-agent enhancement within the ischemic lesion. The intensity of increased BBBP was assessed semi-quantitatively by normalizing the mean voxel intensity within the region of interest (ROI) to the contralateral hemisphere ("normalized CE-ROI"). Selected serum biomarkers (high-sensitive CRP, IL-6, TNF-alpha, MMP-9, and VEGF) at v1 (before intervention) were analyzed as continuous and dichotomized variables defined by laboratory cut-off levels. Functional outcome was assessed at 6 months after stroke using the modified Rankin Scale (mRS).
Results: Ninety-three patients with a median baseline NIHSS of 9 [IQR 6-12] were included into the analysis. The median time to v1 MRI was 30 days [IQR 18-37], and the median lesion volume on v1 MRI was 4 ml [IQR 1.2-23.4]. Seventy patients (80%) had increased BBBP visible on v1 MRI. After the trial intervention, increased BBBP was still detectable in 52 patients (74%) on v2 MRI. The median time to v2 MRI was 56 days [IQR 46-67]. The presence of increased BBBP on v1 MRI was associated with larger lesion volumes and more severe strokes. Aerobic fitness training did not influence the increase of BBBP evaluated at v2. In linear mixed models, the time from stroke onset to MRI was inversely associated with normalized CE-ROI (coefficient -0.002, Standard Error 0.007, p < 0.01). Selected serum biomarkers were not associated with the presence or evolution of increased BBBP. Multivariable regression analysis did not identify the occurrence or evolution of increased BBBP as an independent predictor of favorable functional outcome post-stroke.
Conclusion: In patients with moderate-to-severe subacute stroke, three out of four patients demonstrated increased BBB permeability, which decreased over time. The presence of increased BBBP was associated with larger lesion volumes and more severe strokes. We could not detect an association between selected serum biomarkers of inflammation and an increased BBBP in this cohort. No clear association with favorable functional outcome was observed
A gain-of-function TBX20 mutation causes congenital atrial septal defects, patent foramen ovale and cardiac valve defects
BACKGROUND: Ostium secundum atrial septal defects (ASDII) account for approximately 10% of all congenital heart defects (CHD) and mutations in cardiac transcription factors, including TBX20, were identified as an underlying cause for ASDII. However, very little is known about disease penetrance in families and functional consequences of inherited TBX20 mutations. METHODS: The coding region of TBX20 was directly sequenced in 170 ASDII patients. Functional consequences of one novel mutation were investigated by surface plasmon resonance, CD spectropolarymetry, fluorescence spectrophotometry, luciferase assay and chromatin immunoprecipitation. RESULTS: We found a novel mutation in a highly conserved residue in the T-box DNA-binding domain (I121M) segregating with CHD in a three generation kindred. Four mutation carriers revealed cardiac phenotypes in terms of cribriform ASDII, large patent foramen ovale or cardiac valve defects. Interestingly, tertiary hydrophobic interactions within the mutant TBX20 T-box were significantly altered leading to a more dynamic structure of the protein. Moreover, Tbx20-I121M resulted in a significantly enhanced transcriptional activity, which was further increased in the presence of co-transcription factors GATA4/5 and NKX2-5. Occupancy of DNA binding sites on target genes was also increased. CONCLUSIONS: We suggest that TBX20-I121M adopts a more fluid tertiary structure leading to enhanced interactions with cofactors and more stable transcriptional complexes on target DNA sequences. Our data, combined with that of others, suggest that human ASDII may be related to loss- as well as gain-of-function TBX20 mutations
Sentinel-1 instruments status and product performance update for 2023
The Copernicus program, and particularly Sentinel-1, are among the largest Earth Observation SAR data providers, serving an ever-increasing number of services, users, and applications. A key aspect of the program is the constant provision of quality data, which requires long term engagement to carefully monitor, preserve, and even improve the system performances. These tasks are mainly carried out within the SAR Mission Performance Cluster (SAR-MPC), an international consortium of SAR experts in charge of the continuous monitoring of the Sentinel-1 instruments status and of the L1 and L2 products quality. This paper provides an update on the monitoring and the actions implemented by the SAR-MPC during 2022 and 2023. The analysis regards the monitoring of the instrument status, the evaluation of the instrument radiometric and geometric accuracy, and the updates of the S-1 Instrument Processing Facility
Universal applicator for digitally-controlled pressing force and impact velocity insertion of microneedles into skin
Microneedle technologies have been developed for dermal drug and vaccine delivery, including hollow-, solid-, coated-, and dissolving microneedles. Microneedles have been made in many different geometries and of many different materials, all of which may influence their skin-penetrating ability. To ensure reproducible and effective drug and vaccine delivery via microneedles, the optimal insertion parameters should be known. Therefore, a digitally-controlled microneedle applicator was developed to insert microneedles into the skin via impact insertion (velocity) or via pressing force insertion. Six microneedle arrays with different geometries and/or materials were applied onto ex vivo human skin with varying velocities or pressing forces. Penetration efficiency and delivered antigen dose into the skin after application of microneedles were determined. In general, microneedles pierced the skin more efficiently when applied by impact application as compared to application via pressing force. However, the angle of application of the applicator on the skin can affect the velocity of the impact, influencing the penetration efficiency of microneedles. Regarding the antigen delivery into the skin, the delivered dose was increasing by increasing the velocity or pressure, and thus, increasing the penetration efficiency. These data demonstrate that an applicator is an important tool to determine optimal application conditions with ex vivo human skin
Practical Applications as a Source of Credibility: A Comparison of Three Fields of Dutch Academic Chemistry
In many Western science systems, funding structures increasingly stimulate academic research to contribute to practical applications, but at the same time the rise of bibliometric performance assessments have strengthened the pressure on academics to conduct excellent basic research that can be published in scholarly literature. We analyze the interplay between these two developments in a set of three case studies of fields of chemistry in the Netherlands. First, we describe how the conditions under which academic chemists work have changed since 1975. Second, we investigate whether practical applications have become a source of credibility for individual researchers. Indeed, this turns out to be the case in catalysis, where connecting with industrial applications helps in many steps of the credibility cycle. Practical applications yield much less credibility in environmental chemistry, where application-oriented research agendas help to acquire funding, but not to publish prestigious papers or to earn peer recognition. In biochemistry practical applications hardly help in gaining credibility, as this field is still strongly oriented at fundamental questions. The differences between the fields can be explained by the presence or absence of powerful upstream end-users, who can afford to invest in academic research with promising long term benefits
Critical Role of IRF-5 in the Development of T helper 1 responses to Leishmania donovani infection
The transcription factor Interferon Regulatory Factor 5 (IRF-5) has been shown to be involved in the induction of proinflammatory cytokines in response to viral infections and TLR activation and to play an essential role in the innate inflammatory response. In this study, we used the experimental model of visceral leishmaniasis to investigate the role of IRF-5 in the generation of Th1 responses and in the formation of Th1-type liver granulomas in Leishmania donovani infected mice. We show that TLR7-mediated activation of IRF-5 is essential for the development of Th1 responses to L. donovani in the spleen during chronic infection. We also demonstrate that IRF-5 deficiency leads to the incapacity to control L. donovani infection in the liver and to the formation of smaller granulomas. Granulomas in Irf5-/- mice are characterized by an increased IL-4 and IL-10 response and concomitant low iNOS expression. Collectively, these results identify IRF-5 as a critical molecular switch for the development of Th1 immune responses following L. donovani infections and reveal an indirect role of IRF-5 in the regulation of iNOS expression
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