122 research outputs found
Optical properties of Ce–Ti-containing silicate glasses
Silicate glasses doped with ceria and titania have been studied. Such co-doping determines the specific coloration of the glasses with adjustable absorption in the visible spectral region. Based on measurements of optical transmittance and photoluminescence and studies of electron paramagnetic resonance, it was established
that the features of their optical properties are due to the formation of chromophore centers incorporating cerium and titanium ions
Proximity-driven source of highly spin-polarized ac current on the basis of superconductor/weak ferromagnet/superconductor voltage-biased Josephson junction
We theoretically investigate an opportunity to implement a source of highly
spin-polarized ac current on the basis of superconductor/weak
ferromagnet/superconductor (SFS) voltage-biased junction in the regime of
essential proximity effect and calculate the current flowing through the probe
electrode tunnel coupled to the ferromagnetic interlayer region. It is shown
that while the polarization of the dc current component is generally small in
case of weak exchange field of the ferromagnet, there is an ac component of the
current in the system. This ac current is highly spin-polarized and entirely
originated from the non-equilibrium proximity effect in the interlayer. The
frequency of the current is controlled by the voltage applied to SFS junction.
We discuss a possibility to obtain a source of coherent ac currents with a
certain phase shift between them by tunnel coupling two probe electrodes at
different locations of the interlayer region.Comment: 8 pages, 5 figure
Therapeutic complement targeting in ANCA-associated vasculitides and thrombotic microangiopathy
Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are a group of systemic autoimmune disorders characterized by necrotizing inflammation of medium-to-small vessels, a relative paucity of immune deposits, and an association with detectable circulating ANCAs. AAVs include granulomatosis with polyangiitis (renamed from Wegener's granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome). Until recently, AAVs have not been viewed as complement-mediated disorders. However, recent findings predominantly from animal studies demonstrated a crucial role of the complement system in the pathogenesis of AAVs. Complement activation or defects in its regulation have been described in an increasing number of acquired or genetically driven forms of thrombotic microangiopathy. Coinciding with this expanding spectrum of complement-mediated diseases, the question arises as to which AAV patients might benefit from a complement-targeted therapy. Therapies directed against the complement system point to the necessity of a genetic workup of genes of complement components and regulators in patients with AAV. Genetic testing together with pluripotent stem cells and bioinformatics tools may broaden our approach to the treatment of patients with aggressive forms of AAV
Bound states at the interface between antiferromagnets and superconductors
We present a detailed theoretical investigation of interfaces and junctions
involving itinerant antiferromagnets. By solving the Bogoliubov-de Gennes
equations with a tight-binding model on a square lattice, we study both the
self-consistent order parameter fields proximate to interfaces between
antiferromagnets (AF) and s-wave (sSC) or d-wave (dSC) superconductors, the
dispersion of quasiparticle subgap states at interfaces and interlayers, and
the local density of states (LDOS) as a function of distance from the
interface. In addition, we present the quasiclassical approach to interfaces
and junctions involving itinerant antiferromagnets developed in an earlier
paper. Analytical results are in excellent agreement with what we obtain
numerically. Strong effects of pair breaking in the presence of low-energy
interface Andreev states are found in particular for AF/sSC interfaces when
interface potentials are not too high. Potential barriers induce additional
extrema in the dispersive quasiparticle spectra with corresponding peaks in the
LDOS. Discrete quasiparticle dispersive levels in AF - normal metal (N) - AF
systems are found to strongly depend on the misorientation angle of the
magnetizations in the two antiferromagnets.Comment: 21 pp, 21 postscript figures, submitted to Phys. Rev.
Josephson Current in S-FIF-S Junctions: Nonmonotonic Dependence on Misorientation Angle
Spectra and spin structures of Andreev interface states in S-FIF-S junctions
are investigated with emphasis on finite transparency and misorientation angle
between in-plane magnetizations of ferromagnetic layers in a three-layer
interface. It is demonstrated that the Josephson current in S-FIF-S quantum
point contacts can exhibit a nonmonotonic dependence on the misorientation
angle. The characteristic behavior takes place, if the pi-state is the
equilibrium state of the junction in the particular case of parallel
magnetizations.Comment: 5 pages, 4 figure
Point mutations in the Rpb9-homologous domain of Rpc11 that impair transcription termination by RNA polymerase III
RNA polymerase III recognizes and pauses at its terminator, an oligo(dT) tract in non-template DNA, terminates 3′ oligo(rU) synthesis within this sequence, and releases the RNA. The pol III subunit Rpc11p (C11) mediates RNA 3′–5′ cleavage in the catalytic center of pol III during pausing. The amino and carboxyl regions of C11 are homologous to domains of the pol II subunit Rpb9p, and the pol II elongation and RNA cleavage factor, TFIIS, respectively. We isolated C11 mutants from Schizosaccharomyces pombe that cause pol III to readthrough terminators in vivo. Mutant RNA confirmed the presence of terminator readthrough transcripts. A predominant mutation site, F32, resides in the C11 Rpb9-like domain. Another mutagenic approach confirmed the F32 mutation and also isolated I34 and Y30 mutants. Modeling Y30, F32 and I34 of C11 in available cryoEM pol III structures predicts a hydrophobic patch that may interface with C53/37. Another termination mutant, Rpc2-T455I, appears to reside internally, near the RNA–DNA hybrid. We show that the Rpb9 and TFIIS homologous mutants of C11 reflect distinct activities, that differentially affect terminator recognition and RNA 3′ cleavage. We propose that these C11 domains integrate action at the upper jaw and center of pol III during termination
The importance of the cellular stress response in the pathogenesis and treatment of type 2 diabetes
Organisms have evolved to survive rigorous environments and are not prepared to thrive in a world of caloric excess and sedentary behavior. A realization that physical exercise (or lack of it) plays a pivotal role in both the pathogenesis and therapy of type 2 diabetes mellitus (t2DM) has led to the provocative concept of therapeutic exercise mimetics. A decade ago, we attempted to simulate the beneficial effects of exercise by treating t2DM patients with 3 weeks of daily hyperthermia, induced by hot tub immersion. The short-term intervention had remarkable success, with a 1 % drop in HbA1, a trend toward weight loss, and improvement in diabetic neuropathic symptoms. An explanation for the beneficial effects of exercise and hyperthermia centers upon their ability to induce the cellular stress response (the heat shock response) and restore cellular homeostasis. Impaired stress response precedes major metabolic defects associated with t2DM and may be a near seminal event in the pathogenesis of the disease, tipping the balance from health into disease. Heat shock protein inducers share metabolic pathways associated with exercise with activation of AMPK, PGC1-a, and sirtuins. Diabetic therapies that induce the stress response, whether via heat, bioactive compounds, or genetic manipulation, improve or prevent all of the morbidities and comorbidities associated with the disease. The agents reduce insulin resistance, inflammatory cytokines, visceral adiposity, and body weight while increasing mitochondrial activity, normalizing membrane structure and lipid composition, and preserving organ function. Therapies restoring the stress response can re-tip the balance from disease into health and address the multifaceted defects associated with the disease
Immunoglobulin, glucocorticoid, or combination therapy for multisystem inflammatory syndrome in children: a propensity-weighted cohort study
Background: Multisystem inflammatory syndrome in children (MIS-C), a hyperinflammatory condition associated with SARS-CoV-2 infection, has emerged as a serious illness in children worldwide. Immunoglobulin or glucocorticoids, or both, are currently recommended treatments. Methods: The Best Available Treatment Study evaluated immunomodulatory treatments for MIS-C in an international observational cohort. Analysis of the first 614 patients was previously reported. In this propensity-weighted cohort study, clinical and outcome data from children with suspected or proven MIS-C were collected onto a web-based Research Electronic Data Capture database. After excluding neonates and incomplete or duplicate records, inverse probability weighting was used to compare primary treatments with intravenous immunoglobulin, intravenous immunoglobulin plus glucocorticoids, or glucocorticoids alone, using intravenous immunoglobulin as the reference treatment. Primary outcomes were a composite of inotropic or ventilator support from the second day after treatment initiation, or death, and time to improvement on an ordinal clinical severity scale. Secondary outcomes included treatment escalation, clinical deterioration, fever, and coronary artery aneurysm occurrence and resolution. This study is registered with the ISRCTN registry, ISRCTN69546370. Findings: We enrolled 2101 children (aged 0 months to 19 years) with clinically diagnosed MIS-C from 39 countries between June 14, 2020, and April 25, 2022, and, following exclusions, 2009 patients were included for analysis (median age 8·0 years [IQR 4·2–11·4], 1191 [59·3%] male and 818 [40·7%] female, and 825 [41·1%] White). 680 (33·8%) patients received primary treatment with intravenous immunoglobulin, 698 (34·7%) with intravenous immunoglobulin plus glucocorticoids, 487 (24·2%) with glucocorticoids alone; 59 (2·9%) patients received other combinations, including biologicals, and 85 (4·2%) patients received no immunomodulators. There were no significant differences between treatments for primary outcomes for the 1586 patients with complete baseline and outcome data that were considered for primary analysis. Adjusted odds ratios for ventilation, inotropic support, or death were 1·09 (95% CI 0·75–1·58; corrected p value=1·00) for intravenous immunoglobulin plus glucocorticoids and 0·93 (0·58–1·47; corrected p value=1·00) for glucocorticoids alone, versus intravenous immunoglobulin alone. Adjusted average hazard ratios for time to improvement were 1·04 (95% CI 0·91–1·20; corrected p value=1·00) for intravenous immunoglobulin plus glucocorticoids, and 0·84 (0·70–1·00; corrected p value=0·22) for glucocorticoids alone, versus intravenous immunoglobulin alone. Treatment escalation was less frequent for intravenous immunoglobulin plus glucocorticoids (OR 0·15 [95% CI 0·11–0·20]; p<0·0001) and glucocorticoids alone (0·68 [0·50–0·93]; p=0·014) versus intravenous immunoglobulin alone. Persistent fever (from day 2 onward) was less common with intravenous immunoglobulin plus glucocorticoids compared with either intravenous immunoglobulin alone (OR 0·50 [95% CI 0·38–0·67]; p<0·0001) or glucocorticoids alone (0·63 [0·45–0·88]; p=0·0058). Coronary artery aneurysm occurrence and resolution did not differ significantly between treatment groups. Interpretation: Recovery rates, including occurrence and resolution of coronary artery aneurysms, were similar for primary treatment with intravenous immunoglobulin when compared to glucocorticoids or intravenous immunoglobulin plus glucocorticoids. Initial treatment with glucocorticoids appears to be a safe alternative to immunoglobulin or combined therapy, and might be advantageous in view of the cost and limited availability of intravenous immunoglobulin in many countries. Funding: Imperial College London, the European Union's Horizon 2020, Wellcome Trust, the Medical Research Foundation, UK National Institute for Health and Care Research, and National Institutes of Health
Charting Evolution’s Trajectory: Using Molluscan Eye Diversity to Understand Parallel and Convergent Evolution
For over 100 years, molluscan eyes have been used as an example of convergent evolution and, more recently, as a textbook example of stepwise evolution of a complex lens eye via natural selection. Yet, little is known about the underlying mechanisms that create the eye and generate different morphologies. Assessing molluscan eye diversity and understanding how this diversity came about will be important to developing meaningful interpretations of evolutionary processes. This paper provides an introduction to the myriad of eye types found in molluscs, focusing on some of the more unusual structures. We discuss how molluscan eyes can be applied to the study of evolution by examining patterns of convergent and parallel evolution and provide several examples, including the putative convergence of the camera-type eyes of cephalopods and vertebrates
Эффективность и безопасность применения цепэгинтерферона альфа-2b в составе двойной схемы (цепэгинтерферон альфа 2b и рибавирин) противовирусной терапии у пациентов с хроническим гепатитом С, генотипами 2 и 3. Опыт реальной клинической практики
The objective: to analyze the experience of use of cepeginterferonalfa-2b and ribavirin in patients with chronic hepatitis C genotypes 2 and 3 in clinical practice, to evaluate the efficacy, safety and tolerability of this treatment regimen.Materials and methods. From 2013 to 2016 a total of 73 patients with chronic hepatitis C (CHC) received antiviral therapy with cepeginterferon alfa 2b (cePEG-IFN alfa-2b) and ribavirin in the Center for Gastroenterology and Hepatology of FSBE «Vishnevsky Third Military Clinical Hospital» of Russian Ministry of Defence. Treatment efficacy was assessed by the rate of sustained virologic response (SVR) on 24 week after completion of antiviral therapy. All cases of deterioration of the patient’s condition and laboratory abnormalities were registered throughout the treatment period and follow up. Severity of adverse events was assessed in accordance with the classification of CTCAE (Common Terminology Criteria for Adverse Events).Results. 73 CHC patients genotype 2/3 received cePEGIFN alfa-2b 1.5 μg/kg/week and ribavirin 800-1400 mg/day based on body weight for 24 weeks. SVR 24 was registered in 94,7% (n=54) of patients with HCV genotype 3 and in 93,7% (n =15) patients with genotype 2. During the first 12 weeks of therapy the normalization of serum transaminase activities was registered. All adverse events were typical for interferon/ribavirin treatment regimen.Conclusion. According to our data the use of double treatment regimen (CePEG-IFN alfa-2b and ribavirin) is reasonable in patients who don’t have negative predictive factors of response to IFN-based therapy. The SVR rate in this group of patients was 94.5%.Цель: проанализировать опыт применения цепэгинтерферона альфа-2b в составе двойной схемы (цепэгинтерферон альфа-2b и рибавирин) противовирусной терапии у пациентов с хроническим гепатитом С, генотипами 2 и 3 в клинической практике; оценить эффективность, безопасность и переносимость лечения.Материалы и методы. С февраля 2013 г. по март 2016 г. в Центре гастроэнтерологии и гепатологии 3-го Центрального военного клинического госпиталя им. А.А. Вишневского 73 пациента с хроническим гепатитом С (ХГС) получали противовирусную терапию (ПВТ) с применением двойной схемы, включающей цепэгинтерферон альфа-2b (цеПЭГ-ИФН альфа-2b) и рибавирин. Эффективность лечения оценивалась по частоте достижения вирусологического ответа через 24 недели после окончания терапии – устойчивый вирусологический ответ (УВО24). В процессе лечения фиксировались все случаи нарушения самочувствия пациентов и отклонений от нормы в лабораторных тестах крови. Выраженность нежелательных явлений оценивалась в соответствии с классификацией СТСАЕ (Common Terminology Criteria for Adverse Events).Результаты. 73 пациента с ХГС, генотипом 2 и 3, получали цеПЭГ-ИФН альфа-2b 1,5 мкг/кг/нед. и рибавирин 800–1400 мг/сут в зависимости от массы тела в течение 24 недель. УВО 24 был зафиксирован у 94,7% (n=54) пациентов с 3 генотипом HCV и у 93,7% (n=15) пациентов с 2 генотипом. В течение первых 12 недель терапии у большинства пациентов отмечена нормализация активности сывороточных трансаминаз. Все наблюдавшиеся нежелательные явления были характерны для интерферона и рибавирина.Заключение. В работе представлен опыт применения комбинации цеПЭГ-ИФН альфа-2b и рибавирина у пациентов с 2 и 3 генотипом HCV. Согласно полученным нами данным, при применении цеПЭГ-ИФН альфа-2b и рибавирина у пациентов, не имеющих предикторов неблагоприятного исхода терапии, частота УВО составила 94,5%
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