399 research outputs found

    Dissociative adsorption of NO upon AI(111): Orientation dependent charge transfer and chemisorption reaction dynamics.

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    In order to clarify the underlying mechanism of the initial oxidation of aluminum, the reaction between a heteronuclear diatomic molecule, nitric oxide, and the Al(111) surface was studied. It was shown that the reaction of NO with aluminum is a two-step process including a change of the orientation of the molecule with respect to the surface

    Local Electronic Structure of a Single Magnetic Impurity in a Superconductor

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    The electronic structure near a single classical magnetic impurity in a superconductor is determined using a fully self-consistent Koster-Slater algorithm. Localized excited states are found within the energy gap which are half electron and half hole. Within a jellium model we find the new result that the spatial structure of the positive-frequency (electron-like) spectral weight (or local density of states), can differ strongly from that of the negative frequency (hole-like) spectral weight. The effect of the impurity on the continuum states above the energy gap is calculated with good spectral resolution for the first time. This is also the first three-dimensional self-consistent calculation for a strong magnetic impurity potential.Comment: 13 pages, RevTex, change in heuristic picture, no change in numerical result

    Local Electronic Structure of Defects in Superconductors

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    The electronic structure near defects (such as impurities) in superconductors is explored using a new, fully self-consistent technique. This technique exploits the short-range nature of the impurity potential and the induced change in the superconducting order parameter to calculate features in the electronic structure down to the atomic scale with unprecedented spectral resolution. Magnetic and non-magnetic static impurity potentials are considered, as well as local alterations in the pairing interaction. Extensions to strong-coupling superconductors and superconductors with anisotropic order parameters are formulated.Comment: RevTex source, 20 pages including 22 figures in text with eps

    Advances in ab-initio theory of Multiferroics. Materials and mechanisms: modelling and understanding

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    Within the broad class of multiferroics (compounds showing a coexistence of magnetism and ferroelectricity), we focus on the subclass of "improper electronic ferroelectrics", i.e. correlated materials where electronic degrees of freedom (such as spin, charge or orbital) drive ferroelectricity. In particular, in spin-induced ferroelectrics, there is not only a {\em coexistence} of the two intriguing magnetic and dipolar orders; rather, there is such an intimate link that one drives the other, suggesting a giant magnetoelectric coupling. Via first-principles approaches based on density functional theory, we review the microscopic mechanisms at the basis of multiferroicity in several compounds, ranging from transition metal oxides to organic multiferroics (MFs) to organic-inorganic hybrids (i.e. metal-organic frameworks, MOFs)Comment: 22 pages, 9 figure

    Optimal flux spaces of genome-scale stoichiometric models are determined by a few subnetworks

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    The metabolism of organisms can be studied with comprehensive stoichiometric models of their metabolic networks. Flux balance analysis (FBA) calculates optimal metabolic performance of stoichiometric models. However, detailed biological interpretation of FBA is limited because, in general, a huge number of flux patterns give rise to the same optimal performance. The complete description of the resulting optimal solution spaces was thus far a computationally intractable problem. Here we present CoPE-FBA: Comprehensive Polyhedra Enumeration Flux Balance Analysis, a computational method that solves this problem. CoPE-FBA indicates that the thousands to millions of optimal flux patterns result from a combinatorial explosion of flux patterns in just a few metabolic sub-networks. The entire optimal solution space can now be compactly described in terms of the topology of these sub-networks. CoPE-FBA simplifies the biological interpretation of stoichiometric models of metabolism, and provides a profound understanding of metabolic flexibility in optimal states

    A systematic review and meta-analysis on the effect of neoadjuvant chemotherapy on complications following immediate breast reconstruction

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    Background The impact of neoadjuvant chemotherapy (NACT) on surgical outcomes following immediate breast reconstruction (IBR) remains unclear. While it is generally considered safe practice to perform an IBR post NACT, reported complication rates in published data are highly variable with the majority of studies including fewer than 50 patients in the NACT and IBR arm. To evaluate this further, we conducted a systematic review and meta-analysis on the effect of NACT on autologous and implant based immediate breast reconstructions. We aimed to assess for differences in the post-operative course following IBR between patients who received NACT with those who did not. Methods PubMed, EMBASE, and Cochrane Library were searched from 1995 to Sept 2, 2020 to identify articles that assessed the impact of NACT on IBR. All included studies assessed outcomes following IBR. Only studies comparing reconstructed patients receiving NACT to a control group of women who did not receive NACT were included. Unadjusted relative risk of outcomes between patients who received or did not receive NACT were synthesized using a fixed-effect meta-analysis. The evidence was assessed using the Newcastle Ottawa Scale scores and GRADE. Primary effect measures were risk ratios (RRs) with 95% confidence intervals. Results A total 17 studies comprising 3249 patients were included in the meta-analyses. Overall, NACT did not increase the risk of complications after immediate breast reconstructions (risk ratio [RR]: 0.91, 95% CI 0.74 to 1.11, p = 0.34). There was a moderate, but not significant, increase in flap loss following NACT compared with controls (RR: 1.23, 95% CI 0.70 to 2.18, p = 0.47; I2 = 0%). Most notably, there was a statistically significant increase in implant/expander loss after NACT (RR: 1.54, 95% CI 1.04 to 2.29, p = 0.03; I2 = 34%). NACT was not shown to significantly increase the incidence of hematomas, seromas or wound complications, or result in a significant delay to commencing adjuvant therapy (RR: 1.59, 95% CI 0.66 to 3.87, p = 0.30). Conclusion Immediate breast reconstruction after NACT is a safe procedure with an acceptable post-operative complication profile. It may result in a slight increase in implant loss rates, but it does not delay commencing adjuvant therapy

    Structural Disorder Provides Increased Adaptability for Vesicle Trafficking Pathways

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    Vesicle trafficking systems play essential roles in the communication between the organelles of eukaryotic cells and also between cells and their environment. Endocytosis and the late secretory route are mediated by clathrin-coated vesicles, while the COat Protein I and II (COPI and COPII) routes stand for the bidirectional traffic between the ER and the Golgi apparatus. Despite similar fundamental organizations, the molecular machinery, functions, and evolutionary characteristics of the three systems are very different. In this work, we compiled the basic functional protein groups of the three main routes for human and yeast and analyzed them from the structural disorder perspective. We found similar overall disorder content in yeast and human proteins, confirming the well-conserved nature of these systems. Most functional groups contain highly disordered proteins, supporting the general importance of structural disorder in these routes, although some of them seem to heavily rely on disorder, while others do not. Interestingly, the clathrin system is significantly more disordered (,23%) than the other two, COPI (,9%) and COPII (,8%). We show that this structural phenomenon enhances the inherent plasticity and increased evolutionary adaptability of the clathrin system, which distinguishes it from the other two routes. Since multi-functionality (moonlighting) is indicative of both plasticity and adaptability, we studied its prevalence in vesicle trafficking proteins and correlated it with structural disorder. Clathrin adaptors have the highest capability for moonlighting while also comprising the most highly disordered members. The ability to acquire tissue specific functions was also used to approach adaptability: clathrin route genes have the most tissue specific exons encoding for protein segments enriched in structural disorder and interaction sites. Overall, our results confirm the general importance of structural disorder in vesicle trafficking and suggest major roles for this structural property in shaping the differences of evolutionary adaptability in the three routes

    CAR expression in invasive breast carcinoma and its effect on adenovirus transduction efficiency

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    BackgroundBreast cancer is the second leading cause of death in women, with invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) as the two most common forms of invasive breast cancer. While estrogen receptor positive (ER+) IDC and ILC are treated similarly, the multifocality of ILC presents challenges in detection and treatment, worsening long-term clinical outcomes in patients. With increasing documentation of chemoresistance in ILC, additional treatment options are needed. Oncolytic adenoviral therapy may be a promising option, but cancer cells must express the coxsackievirus & adenovirus receptor (CAR) for adenoviral therapy to be effective. The present study aims to evaluate the extent to which CAR expression is observed in ILC in comparison to IDC, and how the levels of CAR expression correlate with adenovirus transduction efficiency. The effect of liposome encapsulation on transduction efficiency is also assessed.MethodsTo characterize CAR expression in invasive breast carcinoma, 36 formalin-fixed paraffin-embedded (FFPE) human breast tumor samples were assayed by CAR immunohistochemistry (IHC). Localization of CAR in comparison to other junctional proteins was performed using a multiplex immunofluorescence panel consisting of CAR, p120-catenin, and E-cadherin. ILC and IDC primary tumors and cell lines were transduced with E1- and E3-deleted adenovirus type 5 inserted with a GFP transgene (Ad-GFP) and DOTAP liposome encapsulated Ad-GFP (DfAd-GFP) at various multiplicities of infection (MOIs). Transduction efficiency was measured using a fluorescence plate reader. CAR expression in the human primary breast carcinomas and cell lines was also evaluated by IHC.ResultsWe observed membranous CAR, p120-catenin and E-cadherin expression in IDC. In ILC, we observed cytoplasmic expression of CAR and p120-catenin, with absent E-cadherin. Adenovirus effectively transduced high-CAR IDC cell lines, at MOIs as low as 12.5. Ad-GFP showed similar transduction as DfAd-GFP in high-CAR IDC cell lines. Conversely, Ad-GFP transduction of ILC cell lines was observed only at MOIs of 50 and 100. Furthermore, Ad-GFP did not transduce CAR-negative IDC cell lines even at MOIs greater than 100. Liposome encapsulation (DfAd-GFP) improved transduction efficiency 4-fold in ILC and 17-fold in CAR-negative IDC cell lines.ConclusionThe present study demonstrates that oncolytic adenoviral therapy is less effective in ILC than IDC due to differences in spatial CAR expression. Liposome-enhanced delivery may be beneficial for patients with ILC and tumors with low or negative CAR expression to improve adenoviral therapeutic effectiveness

    Phase 2b program with sonlicromanol in patients with mitochondrial disease due to m.3243A>G mutation

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    \ua9 The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain. Mitochondrial disease incorporates a group of rare conditions with no approved treatment to date, except for Leber hereditary optic neuropathy. Therapeutic options to alleviate the symptoms of mitochondrial disease are urgently needed. Sonlicromanol is a promising candidate, as it positively alters the key metabolic and inflammatory pathways associated with mitochondrial disease. Sonlicromanol is a reductive and oxidative distress modulator, selectively inhibiting microsomal prostaglandin E1 synthase activity. This phase 2b program, aimed at evaluating sonlicromanol in adults with m.3243A>G mutation and primary mitochondrial disease, consisted of a randomized controlled (RCT) study (dose-selection) followed by a 52-week open-label extension study (EXT, long-term tolerability, safety and efficacy of sonlicromanol). Patients were randomized (1:1:1) to receive 100 or 50 mg sonlicromanol or placebo twice daily (bid) for 28 days with a ≥2-week wash-out period between treatments. Patients who completed the RCT study entered the EXT study, wherein they received 100 mg sonlicromanol bid. Overall, 27 patients were randomized (24 RCT patients completed all periods). Fifteen patients entered the EXT, and 12 patients were included in the EXT analysis set. All patients reported good tolerability and favourable safety, with pharmacokinetic results comparable to the earlier phase 2a study. The RCT primary end point [change from placebo in the attentional domain of the cognition score (visual identification; Cogstate IDN)] did not reach statistical significance. Using a categorization of the subject\u27s period baseline a treatment effect over placebo was observed if their baseline was more affected (P = 0.0338). Using this approach, there were signals of improvements over placebo in at least one dose in the Beck Depression Inventory (BDI, P = 0.0143), Cognitive Failure Questionnaire (P = 0.0113) and the depression subscale of the Hospital Anxiety and Depression Scale (P = 0.0256). Statistically and/or clinically meaningful improvements were observed in the patient- and clinician-reported outcome measures at the end of the EXT study [Test of Attentional Performance (TAP) with alarm, P = 0.0102; TAP without alarm, P = 0.0047; BDI somatic, P = 0.0261; BDI total, P = 0.0563; SF12 physical component score, P = 0.0008]. Seven of nine domains of RAND-Short Form-36-like SF-36 pain improved (P = 0.0105). Other promising results were observed in the Neuro-Quality of Life Short Form-Fatigue Scale (P = 0.0036), mini-Balance Evaluation Systems test (P = 0.0009), McGill Pain Questionnaire (P = 0.0105), EuroQol EQ-5D-5L-Visual Analog Scale (P = 0.0213) and EQ-5D-5L-Index (P = 0.0173). Most patients showed improvement in the Five Times Sit-To-Stand Test. Sonlicromanol was well-tolerated and demonstrated a favourable benefit/risk ratio for up to 1 year. Sonlicromanol was efficacious in patients when affected at baseline, as seen across a variety of clinically relevant domains. Long-term treatment showed more pronounced changes from baseline

    Evidence for a Massive Post-Starburst Galaxy at z ~ 6.5

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    We present results from a search for high-redshift J--band ``dropout'' galaxies in the portion of the GOODS southern field that is covered by extremely deep imaging from the Hubble Ultradeep Field (HUDF).Using observations at optical, near-infrared and mid-infrared wavelengths from the Hubble and Spitzer Space Telescopes and the ESO-VLT, we search for very massive galaxies at high redshifts and find one particularly remarkable candidate. Its spectral energy distribution is consistent with a galaxy at z ~ 6.5 and a stellar mass of 6x10e11 M(sun) (for a Salpeter IMF). We interpret a prominent photometric break between the near-infrared and Spitzer bandpasses as the 3646A Balmer discontinuity. The best-fitting models have low reddening and ages of several hundred Myr, placing the formation of the bulk of the stars at z > 9. Alternative models of dusty galaxies at z ~ 2.5 are possible but provide significantly poorer fits. The object is detected with Spitzer at 24 micron. This emission originats from an obscured active nucleus or star formation. We present optical and near-infrared spectroscopy which has, thus far, failed to detect any spectral features. This helps limit the solution in which the galaxy is a starburst or active galaxy at z ~ 2.5. If the high-redshift interpretation is correct, this object would be an example of a galaxy that formed by a process strongly resembling traditional models of monolithic collapse, in a way which a very large mass of stars formed within a remarkably short period of time, at very high redshift.Comment: Accepted for publication in Ap.J. 31 pages, 6 diagram
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