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The 5d^{1} ordered double perovskites present an exotic playground for studying novel multipolar physics due to large spin-orbit coupling. We present Re L_{3} edge resonant inelastic x-ray scattering (RIXS) results that reveal the presence of the dynamic Jahn-Teller effect in the A_{2}MgReO_{6} (A=Ca, Sr, Ba) family of 5d^{1} double perovskites. The spin-orbit excitations in these materials show a strongly asymmetric line shape and exhibit substantial temperature dependence, indicating that they are dressed with lattice vibrations. Our experimental results are explained quantitatively through a RIXS calculation based on a spin-orbit-lattice entangled electronic ground state with the dynamic Jahn-Teller effect taken into consideration. We find that the spin-orbit-lattice entangled state is robust against magnetic and structural phase transitions as well as against significant static Jahn-Teller distortions. Our results illustrate the importance of including vibronic coupling for a complete description of the ground state physics of 5d^{1} double perovskites.
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OBJECTIVES: Endoscopic ultrasound-guided tissue acquisition (EUS-TA) has been the most common method used for the preoperative cytopathological diagnosis of solid tumors of the pancreas. There are only a few reported cases about the role of endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) in the pre-operative diagnosis of solid pseudopapillary neoplasms (SPN). This study aimed to evaluate the diagnostic yield of EUS-TA,including endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) andEUS-FNB, in patients with SPN. METHODS: We performed a retrospective analysis of patients with EUS-TA for SPN diagnosis in 2 referral centers. The primary outcome was the diagnostic yield of EUS-TA compared to the surgical specimen. RESULTS: Seventy-four patients with SPN of the pancreas were identified. Eighteen had a EUS-TA (10 EUS-FNB and 8 EUS-FNA). The median age of the patients was 31 years (IQR 21-38), and all patients were women. The most common presenting symptom was abdominal pain. Most of the tumors were in the head of the pancreas (9/18; 50%). The median tumor size by EUS was 4.5 cm (min-max 2-15 cm). The most common appearance on EUS was a solid lesion (n = 8/18, 44.4%). A definitive presurgical cytopathological diagnosis was obtained in 16/18 patients (88.8%) with EUS-TA. The sensitivity and positive predictive value of the EUS-TA were 94% each. One patient in the EUS-FNB group developed mild acute pancreatitis. CONCLUSION: The diagnostic yield of the EUS-TA in SPN is high. In most cases, the diagnosis was obtained with the first procedure. No differences in the diagnostic yield or AEs between EUS-FNA vs. EUS-FNB needles were seen.
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Neoplasias Pancreáticas , Pancreatite , Humanos , Feminino , Adulto Jovem , Adulto , Masculino , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/patologia , Estudos Retrospectivos , Doença Aguda , Pâncreas/diagnóstico por imagem , Pâncreas/patologiaRESUMO
For patients with inborn errors of immunity (IEI) and other inborn diseases, mixed donor chimerism is a well-accepted outcome of hematopoietic stem cell transplantation (HSCT). Cytoreductive chemotherapy for a secondary malignancy is a potential challenge for the stability of the graft function after HSCT. We report on a boy with X-SCID who developed Ewing sarcoma ten years after HSCT which was successfully treated with cytoreductive chemotherapy, surgery and local radiation. Surprisingly, this treatment had a positive impact on mixed chimerism with an increase of donor-cell proportions from 40% for neutrophils and 75% for non-T-mononuclear cells (MNCs) to >90% for both. T-cell counts remained stable with 100% of donor origin. This is -to our knowledge- the first report on the impact of cytoreductive chemotherapy on post-HSCT mixed chimerism and provides an important first impression for future patients.
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Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Neoplasias , Masculino , Humanos , Quimerismo , Transplante Homólogo , Doadores de Tecidos , Condicionamento Pré-TransplanteRESUMO
INTRODUCTION: Barrett's esophagus (BE) is the main precursor of esophageal adenocarcinoma (EAC). This study aimed to identify the risk factors associated with BE progression to dysplasia or EAC in a Latin population. METHODS: The study is a retrospective analysis of a single-center cohort of patients with BE, evaluated from 2002 to 2012. RESULTS: We identified 420 patients with BE; 281 (66.9%) of them were men with a mean age of 57.2 ± 15.3 years. Among all BE patients evaluated, 81 (19.3%) had progression to some degree of dysplasia/EAC. The mean follow-up was 5.6 years. Multivariate analysis showed that age (OR = 1.03), cigarette smoking (OR = 3.05), long-segment BE (OR = 4.81), and a visible lesion on BE (OR = 6.94) were associated with progression to dysplasia/EAC. CONCLUSION: In Latin patients with BE, age, cigarette smoking, long-segment BE, and the presence of lesions were associated with the presence of dysplasia/EAC.
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Extracting reliable information on certain physical properties of materials, such as thermal transport, can be computationally very demanding. Aiming to overcome such difficulties in the particular case of lattice thermal conductivity (LTC) of 2D nanomaterials, we propose a simple, fast, and accurate semi-empirical approach for LTC calculation. The approach is based on parameterized thermochemical equations and Arrhenius-like fitting procedures, thus avoiding molecular dynamics or ab initio protocols, which frequently require computationally expensive simulations. As a proof of concept, we obtain the LTC of some prototypical physical systems, such as graphene (and other 2D carbon allotropes), hexagonal boron nitride (hBN), silicene, germanene, binary, and ternary BNC lattices and two examples of the fullerene network family. Our obtained values are in good agreement with other theoretical and experimental estimations, nonetheless, being derived in a rather straightforward way, at a fraction of the usual computational cost.
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AIM: To assess the effects of subchronic administration with NaHS, an exogenous H2S donor, on TBI-induced hypertension and vascular impairments. MAIN METHODS: Animals underweministration does not prevent the body weight loss but slightly imnt a lateral fluid percussion injury, and the hemodynamic variables were measured in vivo by plethysmograph method. The vascular function in vitro, the ROS levels by the DCFH-DA method and the expression of H2S-synthesizing enzymes and eNOS by Western blot were measured in isolated thoracic aortas at day 7 post-TBI. The effect of L-NAME on NaHS-induced effects in vascular function was evaluated. Brain water content was determined 7 days after trauma induction. Body weight was recorded throughout the experimental protocol, whereas the sensorimotor function was evaluated using the neuroscore test at days -1 (basal), 2, and 7 after the TBI induction. KEY FINDINGS: TBI animals showed: 1) an increase in hemodynamic variables and ROS levels in aortas; 2) vascular dysfunction; 3) sensorimotor dysfunction; and 4) a decrease in body weight, the expression of H2S-synthesizing enzymes, and eNOS phosphorylation. Interestingly, NaHS subchronic administration (3.1 mg/kg; i.p.; every 24 h for six days) prevented the development of hypertension, vascular dysfunction, and oxidative stress. L-NAME abolished NaHS-induced effects. Furthermore, NaHS treatment restored H2S-synthesizing enzymes and eNOS phosphorylation with no effect on body weight, sensorimotor impairments, or brain water content. SIGNIFICANCE: Taken together, these results demonstrate that H2S prevents TBI-induced hypertension by restoring vascular function and modulating ROS levels, H2S-synthesizing enzymes expression, and eNOS phosphorylation.
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Lesões Encefálicas Traumáticas , Sulfeto de Hidrogênio , Hipertensão , Animais , Ratos , Sulfeto de Hidrogênio/farmacologia , Espécies Reativas de Oxigênio/metabolismo , NG-Nitroarginina Metil Éster/efeitos adversos , Hipertensão/metabolismo , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/tratamento farmacológico , Peso Corporal , ÁguaRESUMO
Two of the molecular families closely associated with mediating communication between the brain and immune system are cytokines and the kynurenine metabolites of tryptophan. Both groups regulate neuron and glial activity in the central nervous system (CNS) and leukocyte function in the immune system, although neither group alone completely explains neuroimmune function, disease occurrence or severity. This essay suggests that the two families perform complementary functions generating an integrated network. The kynurenine pathway determines overall neuronal excitability and plasticity by modulating glutamate receptors and GPR35 activity across the CNS, and regulates general features of immune cell status, surveillance and tolerance which often involves the Aryl Hydrocarbon Receptor (AHR). Equally, cytokines and chemokines define and regulate specific populations of neurons, glia or immune system leukocytes, generating more specific responses within restricted CNS regions or leukocyte populations. In addition, as there is a much larger variety of these compounds, their homing properties enable the superimposition of dynamic variations of cell activity upon local, spatially limited, cell populations. This would in principle allow the targeting of potential treatments to restricted regions of the CNS. The proposed synergistic interface of 'tonic' kynurenine pathway affecting baseline activity and the superimposed 'phasic' cytokine system would constitute an integrated network explaining some features of neuroimmune communication. The concept would broaden the scope for the development of new treatments for disorders involving both the CNS and immune systems, with safer and more effective agents targeted to specific CNS regions.
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Many invasive micro-organisms produce 'quorum sensor' molecules which regulate colony expansion and may modulate host immune responses. We have examined the ability of Pseudomonas Quorum Sensor (PQS) to influence cytokine expression under conditions of inflammatory stress. The administration of PQS in vivo to mice with collagen-induced arthritis (CIA) increased the severity of disease. Blood and inflamed paws from treated mice had fewer regulatory T cells (Tregs) but normal numbers of Th17 cells. However, PQS (1µM) treatment of antigen-stimulated lymph node cells from collagen-immunised mice in vitro inhibited the differentiation of CD4+IFNγ+ cells, with less effect on CD4+IL-17+ cells and no change in CD4+FoxP3+Tregs. PQS also inhibited T cell activation by anti-CD3/anti-CD28 antibodies. PQS reduced murine macrophage polarisation and inhibited expression of IL1B and IL6 genes in murine macrophages and human THP-1 cells. In human monocyte-derived macrophages, IDO1 gene, protein and enzyme activity were all inhibited by exposure to PQS. TNF gene expression was inhibited in THP-1 cells but not murine macrophages, while LPS-induced TNF protein release was increased by high PQS concentrations. PQS is known to have iron scavenging activity and its suppression of cytokine release was abrogated by iron supplementation. Unexpectedly, PQS decreased the expression of indoleamine-2, 3-dioxygenase genes (IDO1 and IDO2), IDO1 protein expression and enzyme activity in mouse and human macrophages. This is consistent with evidence that IDO1 inhibition or deletion exacerbates arthritis, while kynurenine reduces its severity. It is suggested that the inhibition of IDO1 and cytokine expression may contribute to the quorum sensor and invasive actions of PQS.
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Cinurenina , Pseudomonas , Humanos , Camundongos , Animais , Cinurenina/metabolismo , Pseudomonas aeruginosa , Ferro/metabolismo , Citocinas/metabolismoRESUMO
The systemic cardiovascular effects of major trauma, especially neurotrauma, contribute to death and permanent disability in trauma patients and treatments are needed to improve outcomes. In some trauma patients, dysfunction of the autonomic nervous system produces a state of adrenergic overstimulation, causing either a sustained elevation in catecholamines (sympathetic storm) or oscillating bursts of paroxysmal sympathetic hyperactivity. Trauma can also activate innate immune responses that release cytokines and damage-associated molecular patterns into the circulation. This combination of altered autonomic nervous system function and widespread systemic inflammation produces secondary cardiovascular injury, including hypertension, damage to cardiac tissue, vascular endothelial dysfunction, coagulopathy and multiorgan failure. The gasotransmitters nitric oxide (NO) and hydrogen sulfide (H2S) are small gaseous molecules with potent effects on vascular tone regulation. Exogenous NO (inhaled) has potential therapeutic benefit in cardio-cerebrovascular diseases, but limited data suggests potential efficacy in traumatic brain injury (TBI). H2S is a modulator of NO signaling and autonomic nervous system function that has also been used as a drug for cardio-cerebrovascular diseases. The inhaled gases NO and H2S are potential treatments to restore cardio-cerebrovascular function in the post-trauma period.
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Doenças Cardiovasculares , Sistema Cardiovascular , Gasotransmissores , Sulfeto de Hidrogênio , Humanos , Sulfeto de Hidrogênio/uso terapêutico , Sulfeto de Hidrogênio/farmacologia , Óxido Nítrico , Gasotransmissores/uso terapêuticoRESUMO
Lactic acid bacteria are distributed in nature, isolating themselves from diverse ecosystems and presenting a wide metabolic biodiversity. In Corrientes (Argentina), artisanal cheeses and their specific environment are an important source of autochthonous lactic acid bacteria. The objective of this work was to establish associations between the phenotypic characteristics of strains of Lactococcus lactis subsp. lactis native from Corrientes with climatological data of the Province and the characteristics of the soil and the landscapes. Physiological and biochemical characterization data of Lactococcus lactis subsp. lactis isolated from the dairy environment and from different localities of Corrientes will be used. The strains were space-located through Google Earth, flood and drought events were evaluated using Standardized Precipitation Evapotranspiration Index, and soil composition data (A and Bt horizons) in the study areas were obtained from the experimental station National Institute of Agricultural Technology - Corrientes. A statistical analysis was applied to these results (Infostat Software, Di Rienzo et al. 2008). The resulting consists in three conglomerates, differentiating strains from soils coming from "flooded landscapes" and those from "sandy hills landscape". The analysis by main components highlighted the preference of strains from flooded landscapes by a saline-alkaline environment, affecting during periods of drought, and strains from sandy hills landscape by a low medium in salts and acid soil, directly during period of high humidity resulting from previous floods.
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Lactococcus lactis , Biodiversidade , Ecossistema , Microbiologia de Alimentos , Lactococcus lactis/metabolismo , SoloRESUMO
The alternative (noncanonical) nuclear factor-κB (NF-κB) signaling pathway predominantly regulates the function of the p52/RelB heterodimer. Germline Nfkb2 deficiency in mice leads to loss of p100/p52 protein and offers protection against a variety of gastrointestinal conditions, including azoxymethane/dextran sulfate sodium (DSS)-induced colitis-associated cancer and lipopolysaccharide (LPS)-induced small intestinal epithelial apoptosis. However, the common underlying protective mechanisms have not yet been fully elucidated. We applied high-throughput RNA-Seq and proteomic analyses to characterize the transcriptional and protein signatures of the small intestinal mucosa of naïve adult Nfkb2-/- mice. Those data were validated by immunohistochemistry and quantitative ELISA using both small intestinal tissue lysates and serum. We identified a B-lymphocyte defect as a major transcriptional signature in the small intestinal mucosa and immunoglobulin A as the most downregulated protein by proteomic analysis in Nfkb2-/- mice. Small intestinal immunoglobulins were dramatically dysregulated, with undetectable levels of immunoglobulin A and greatly increased amounts of immunoglobulin M being detected. The numbers of IgA-producing, cluster of differentiation (CD)138-positive plasma cells were also reduced in the lamina propria of the small intestinal villi of Nfkb2-/- mice. This phenotype was even more striking in the small intestinal mucosa of RelB-/- mice, although these mice were equally sensitive to LPS-induced intestinal apoptosis as their RelB+/+ wild-type counterparts. NF-κB2/p52 deficiency confers resistance to LPS-induced small intestinal apoptosis and also appears to regulate the plasma cell population and immunoglobulin levels within the gut.NEW & NOTEWORTHY Novel transcriptomic analysis of murine proximal intestinal mucosa revealed an unexpected B cell signature in Nfkb2-/- mice. In-depth analysis revealed a defect in the CD38+ B cell population and a gut-specific dysregulation of immunoglobulin levels.
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Subunidade p52 de NF-kappa B , Plasmócitos , Animais , Imunoglobulina A/metabolismo , Imunoglobulinas/metabolismo , Mucosa Intestinal/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , NF-kappa B/metabolismo , Subunidade p52 de NF-kappa B/genética , Subunidade p52 de NF-kappa B/metabolismo , Plasmócitos/metabolismo , ProteômicaRESUMO
The transition from strong (fluidlike) to nearly marginal (Floquet-type) regimes of ion-temperature-gradient (ITG) driven turbulence is studied in the stellarator Wendelstein 7-X by means of numerical simulations. Close to marginality, extended (along magnetic field lines) linearly unstable modes are dominant, even in the presence of kinetic electrons, and provide a drive that results in finite turbulent transport. A total suppression of turbulence above the linear stability threshold of the ITG modes, commonly present in tokamaks and known as the "Dimits shift," is not observed. We show that this is mostly due to the peculiar radial structure of marginal turbulence, which is more localized than in the fluid case and therefore less likely to be stabilized by shearing flows.
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Autoimmune murine disease models are vital tools for identifying novel targets and finding better treatments for human diseases. Complete Freund's adjuvant is commonly used to induce disease in autoimmune models, and the quality of the adjuvant/autoantigen emulsion is of critical importance in determining reproducibility. We have established an emulsification method using a standard homogenizer and specially designed receptacle. Emulsions are easy to prepare, form stable and uniform water-in-oil particles, are faster to make than the traditional syringe method, use less material and are designed to fill syringes with ease. In the present study, we have validated the emulsions for induction of experimental autoimmune encephalitis, collagen II induced arthritis, antigen induced arthritis, and delayed type hypersensitivity models. These models were induced consistently and reproducibly and, in some cases, the new method outperformed the traditional method. The method described herein is simple, cost-effective and will reduce variability, thereby requiring fewer animals for in vivo research involving animal models of autoimmune disease and in vaccine development.
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Artrite Experimental , Doenças Autoimunes , Animais , Autoantígenos , Emulsões , Camundongos , Padrões de Referência , Reprodutibilidade dos TestesRESUMO
Many coastal ecosystems, such as coral reefs and seagrass meadows, currently experience overgrowth by fleshy algae due to the interplay of local and global stressors. This is usually accompanied by strong decreases in habitat complexity and biodiversity. Recently, persistent, mat-forming fleshy red algae, previously described for the Black Sea and several Atlantic locations, have also been observed in the Mediterranean. These several centimetre high mats may displace seagrass meadows and invertebrate communities, potentially causing a substantial loss of associated biodiversity. We show that the sessile invertebrate biodiversity in these red algae mats is high and exceeds that of neighbouring seagrass meadows. Comparative biodiversity indices were similar to or higher than those recently described for calcifying green algae habitats and biodiversity hotspots like coral reefs or mangrove forests. Our findings suggest that fleshy red algae mats can act as alternative habitats and temporary sessile invertebrate biodiversity reservoirs in times of environmental change.
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Ecossistema , Rodófitas , Animais , Biodiversidade , Recifes de Corais , InvertebradosRESUMO
Several serine proteases have been linked to autoimmune disorders and tumour initiation although the mechanisms are not fully understood. Activation of the kynurenine pathway enzyme indoleamine-2,3-dioxygenase (IDO1) modulates cellular activity in the brain, tolerogenesis in the immune system and is a major checkpoint in cancer development. We now report that IDO1 mRNA and IDO1 protein expression (generating kynurenine) are induced in human monocyte-derived macrophages by several chymotryptic serine proteases with direct links to tumorigenesis, including Prostate Specific Antigen (PSA), CD26 (Dipeptidyl-peptidase-4, CD26/DPP-4), High Temperature Requirement protein-A (HtrA), and the bacterial virulence factor subtilisin. These proteases also induce expression of the pro-inflammatory cytokine genes IL1B and IL6. Other serine proteases tested: bacterial glu-C endopeptidase and mammalian Pro-protein Convertase Subtilase-Kexin-3 (PCSK3, furin), urokinase plasminogen activator (uPA), cathepsin G or neutrophil elastase, did not induce IDO1, indicating that the reported effects are not a general property of all serine proteases. The results represent a novel mechanism of activating immunosuppressive IDO1 and inducing kynurenine generation which, together with the production of inflammatory cytokines, would contribute to tumour initiation and progression, providing a new target for drug development. In addition, the proteasomal S20 serine protease inhibitor carfilzomib, used in the treatment of myeloma, prevented the induction of IDO1 and cytokine gene expression, potentially contributing to its clinical anti-cancer activity.
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Cinurenina , Neoplasias , Animais , Citocinas , Dipeptidil Peptidase 4/genética , Humanos , Terapia de Imunossupressão , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Cinurenina/metabolismo , Masculino , Mamíferos/metabolismo , Antígeno Prostático Específico , Serina Proteases , Proteína Estafilocócica A , SubtilisinaRESUMO
Splice variants of CD74 differentially modulate the activity of cathepsin L (CTSL). As CD74 and CTSL participate in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA), we determined whether splice variants of CD74 could be biomarkers of disease activity. Gene expression was measured in mice with collagen-induced arthritis using quantitative PCR (qPCR). In vitro studies using murine macrophage/DC-lineage cells determined the relative influence of macrophage phenotype on isoform expression and the potential to produce CTSL in response to TNF. CD74 splice variants were measured in human RA synovium and RA patients' monocytes. In arthritic mice, the expression of the p41 CD74 isoform was significantly higher in severely affected paws compared with unaffected paws or the paws of naïve mice; the p41 isoform significantly correlated with the expression of TNF in arthritic paws. Compared with M2-like macrophages, M1-like macrophages expressed increased levels of CD74 and had higher expression, secretion and activity of CTSL. RA patients that responded to TNF blockade had significantly higher expression levels of CD74 in circulating monocytes after treatment, compared with non-responders. The expression of the human CD74 isoform a was significantly higher in RA synovia, compared with osteoarthritis synovia, and was associated with CSTL enzymatic activity. This study is the first to demonstrate differential expression of the CD74 p41 isoform in an auto-immune disorder and in response to therapy. The differential expression of CD74 splice variants indicates an association, and potentially a mechanistic role, in the pathogenesis of RA.
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Artrite Experimental , Artrite Reumatoide , Animais , Antígenos de Diferenciação de Linfócitos B/genética , Antígenos de Histocompatibilidade Classe II/genética , Humanos , Camundongos , Isoformas de Proteínas/genéticaRESUMO
BACKGROUND: During the COVID-19 pandemic, several questions have arisen about which endoscopic procedures (EPs) must be performed and which ones can be postponed. The aim of this study was to conduct a nationwide survey regarding the appropriate timing of EPs during the COVID-19 pandemic. METHODS: This prospective study was performed through a nationwide electronic survey. The survey consisted of 15 questions divided into three sections. The first evaluated the agreement for EPs classified as "time sensitive" and "not time sensitive". Two other sections assessed "high-priority" and "low-priority" scenarios. Agreement was considered when > 75% of respondents answered a question in the same direction. RESULTS: The response rate was 27.2% (214/784). Among the respondents, agreement for the need to perform EP in < 72 h was only reached for variceal bleeding (93.4%). Dysphagia with alarm symptoms was the scenario in which the highest percentage of physicians (95.9%) agreed that an EP needed to be performed within a month. Less than 30% of endoscopists would perform an EP within the first 72 h for patients with mild cholangitis, non-variceal upper gastrointestinal bleeding without hemodynamic instability, or severe anaemia without overt bleeding. In time-sensitive clinical scenarios suggestive of benign disease, none of the scenarios reached agreement in any sense. Among the time-sensitive clinical scenarios suggestive of malignancy, > 90% of the surveyed respondents considered that EP could not be postponed for > 8 weeks. CONCLUSIONS: There was no consensus among endoscopists about the timing of EPs in patients with pathologies considered time sensitive or in those with high-priority pathologies. Agreement was only reached in five (17%) of the evaluated clinical scenarios.
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COVID-19 , Varizes Esofágicas e Gástricas , Hemorragia Gastrointestinal/epidemiologia , Hemorragia Gastrointestinal/etiologia , Humanos , Pandemias , Estudos Prospectivos , SARS-CoV-2RESUMO
New, linear, segmented poly(peptide-urethane-urea) (PPUU) block copolymers are synthesized and their surface compositions are characterized with angle dependent X-ray photoelectron spectroscopy (ADXPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These new PPUU block copolymers contain three types of segments. The soft segment (SS) is poly(caprolactone diol) (PCL). The hard segment is lysine diisocyanate with a hydrazine chain extender. The oligopeptide segment (OPS) contains three types of amino acids (proline, hydroxyproline, and glycine). Incorporation of the OPS into the polyurethane backbone is done to provide a synthetic polymer material with controllable biodegradation properties. As biodegradation processes normally are initiated at the interface between the biomaterial and the living tissue, it is important to characterize the surface composition of biomaterials. ADXPS and ToF-SIMS results show that the surfaces of all four polymers are enriched with the PCL SS, the most hydrophobic component of the three polymer segments.
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Espectrometria de Massa de Íon Secundário , Ureia , Materiais Biocompatíveis/química , Peptídeos , Espectroscopia Fotoeletrônica , Polímeros/química , Poliuretanos/química , Propriedades de SuperfícieRESUMO
Unmet needs for small diameter, non-biologic vascular grafts and the less-than-ideal performance of medium diameter grafts suggest opportunities for major improvements. Biomaterials that are mechanically matched to native blood vessels, reduce the foreign body capsule (FBC) and demonstrate improved integration and healing are expected to improve graft performance. In this study, we developed biostable, crosslinked polyurethane formulations and used them to fabricate scaffolds with precision-engineered 40 µm pores. We matched the scaffold mechanical properties with those of native blood vessels by optimizing the polyurethane compositions. We hypothesized that such scaffolds promote healing and mitigate the FBC. To test our hypothesis, polyurethanes with 40 µm pores, 100 µm pores, and non-porous slabs were implanted subcutaneously in mice for 3 weeks, and then were examined histologically. Our results show that 40 µm porous scaffolds elicit the highest level of angiogenesis, cellularization, and the least severe foreign body capsule (based on a refined assessment method). This study presents the first biomaterial with tuned mechanical properties and a precision engineered porous structure optimized for healing, thus can be ideal for pro-healing vascular grafts and in situ vascular engineering. In addition, these scaffolds may have wide applications in tissue engineering, drug delivery, and implantable device.