There is emerging evidence for enhanced blood coagulation in coronavirus 2019 (COVID-19) patients, with thromboembolic complications contributing to morbidity and mortality. The mechanisms underlying ...this prothrombotic state remain enigmatic. Further data to guide anticoagulation strategies are urgently required.
We used viscoelastic rotational thromboelastometry (ROTEM) in a single-center cohort of 40 critically ill COVID-19 patients.
Clear signs of a hypercoagulable state due to severe hypofibrinolysis were found. Maximum lysis, especially following stimulation of the extrinsic coagulation system, was inversely associated with an enhanced risk of thromboembolic complications. Combining values for maximum lysis with D-dimer concentrations revealed high sensitivity and specificity of thromboembolic risk prediction.
The study identifies a reduction in fibrinolysis as an important mechanism in COVID-19-associated coagulopathy. The combination of ROTEM and D-dimer concentrations may prove valuable in identifying patients requiring higher intensity anticoagulation.
In this article we study the motion of charged particles in the spacetime of a charged rotating scalarized black hole, namely the rotating dyonic black hole in Kaluza-Klein theory found by Rasheed. ...We derive the equations of motion in the extremal case and present their analytical solutions in terns of elliptic and hyperelliptic functions. Furthermore, we analyze the particle motion with the help of parametric diagrams and effective potentials.
Abstract
With an urgent need for bedside imaging of coronavirus disease 2019 (COVID-19), this study’s main goal was to assess inter- and intraobserver agreement in lung ultrasound (LUS) of COVID-19 ...patients. In this single-center study we prospectively acquired and evaluated 100 recorded ten-second cine-loops in confirmed COVID-19 intensive care unit (ICU) patients. All loops were rated by ten observers with different subspeciality backgrounds for four times by each observer (400 loops overall) in a random sequence using a web-based rating tool. We analyzed inter- and intraobserver variability for specific pathologies and a semiquantitative LUS score. Interobserver agreement for both, identification of specific pathologies and assignment of LUS scores was fair to moderate (e.g., LUS score 1 Fleiss’ κ = 0.27; subpleural consolidations Fleiss’ κ = 0.59). Intraobserver agreement was mostly moderate to substantial with generally higher agreement for more distinct findings (e.g., lowest LUS score 0 vs. highest LUS score 3 (median Fleiss’ κ = 0.71 vs. 0.79) or air bronchograms (median Fleiss’ κ = 0.72)). Intraobserver consistency was relatively low for intermediate LUS scores (e.g. LUS Score 1 median Fleiss’ κ = 0.52). We therefore conclude that more distinct LUS findings (e.g.,
air bronchograms
,
subpleural consolidations
) may be more suitable for disease monitoring, especially with more than one investigator and that training material used for LUS in point-of-care ultrasound (POCUS) should pay refined attention to areas such as
B-line
quantification and differentiation of intermediate LUS scores.
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) induces lung injury of varying severity, potentially causing severe acute respiratory ...distress syndrome (ARDS). Pulmonary injury patterns in COVID-19 patients differ from those in patients with other causes of ARDS. We aimed to explore the frequency and pathogenesis of cavitary lung lesions in critically ill patients with COVID-19. Retrospective study in 39 critically ill adult patients hospitalized with severe acute respiratory syndrome coronavirus 2 including lung injury of varying severity in a tertiary care referral center during March and May 2020, Berlin/Germany. We observed lung cavitations in an unusually large proportion of 22/39 (56%) COVID-19 patients treated on intensive care units (ICU), including 3/5 patients without mechanical ventilation. Median interquartile range (IQR) time between onset of symptoms and ICU admission was 11.5 (6.25–17.75) days. In 15 patients, lung cavitations were already present on the first CT scan, performed after ICU admission; in seven patients they developed during a subsequent median (IQR) observation period of 48 (35–58) days. In seven patients we found at least one cavitation with a diameter > 2 cm (maximum 10 cm). Patients who developed cavitations were older and had a higher body mass index. Autopsy findings in three patients revealed that the cavitations reflected lung infarcts undergoing liquefaction, secondary to thrombotic pulmonary artery branch occlusions. Lung cavitations appear to be a frequent complication of severely ill COVID-19 patients, probably related to the prothrombotic state associated with COVID-19.
COVID 19 is associated with a hypercoagulable state and frequent thromboembolic complications. For how long this acquired abnormality lasts potentially requiring preventive measures, such as ...anticoagulation remains to be delineated. We used viscoelastic rotational thrombelastometry (ROTEM) in a single center cohort of 13 critical ill patients and performed follow up examinations three months after discharge from ICU. We found clear signs of a hypercoagulable state due to severe hypofibrinolysis and a high rate of thromboembolic complications during the phase of acute illness. Three month follow up revealed normalization of the initial coagulation abnormality and no evidence of venous thrombosis in all thirteen patients. In our cohort the coagulation profile was completely normalized three months after COVID-19. Based on these findings, discontinuation of anticoagulation can be discussed in patients with complete venous reperfusion.
A kinetic reaction model for thermal decomposition of urea is presented. Systematic thermogravimetric analyses of urea and its most important by-products, such as biuret and cyanuric acid, are ...performed to gain the main reactions and their rates. Gaseous products are analyzed and the concentrations of solid products are determined. The reaction scheme, as well as the kinetic parameterization, is validated at different heating rates. The proposed kinetic reaction model matches all performed thermogravimetric analyses and it is also able to reproduce changes in the measurement conditions, such as differences in crucibles geometry or variations of the initial sample mass.
•A kinetic reaction model for thermal decomposition of urea is proposed.•Thermogravimetric analyses of urea, biuret and cyanuric acid are predicted.•Species concentrations during thermal decomposition of urea are captured.•Variations in heating rate and initial sample mass can be reproduced.•The influence of the surface area and the crucible geometry is captured.
Reactive extrusion with pyromellitic dianhydride (PMDA) and tetraglycidyl diamino diphenyl methane (TGDDM) was conducted to create long-chain branched poly(ethylene terephthalate) (LCB-PET). The ...mechanical and molecular properties were analyzed by linear and non-linear viscoelastic rheology in the melt state and by size-exclusion chromatography measurements with triple detection. The two tetra-functional chain extenders lead to strong viscosity increases, increasing strain hardening effects, and increasing LCB with increasing chain extender concentration. Molecular stress function model predictions show good agreement with the elongational data measured and allowed a quantification of the strain hardening. Analysis of SEC triple detection data shows a strong increase of the average molar mass, polydispersity, radius of gyration, and hydrodynamic radius with increasing chain extender concentration. Branching was confirmed by a decreasing Mark-Houwink exponent, and the analysis of the contraction of the molecule revealed either star-like, comb-like, random tree-like or hyperbranched structures depending on concentration and type of chain extender.
A 64-year-old female patient presented with severe dyspnea shortly after apparent recovery from COVID-19 disease. Chest computed tomography revealed central pulmonary embolism and ultrasonography ...showed a deep vein thrombosis of her right leg. The patient was tachycardiac with evidence of right ventricular strain on echocardiography. An interdisciplinary decision for interventional therapy was made.
Angiographic aspiration thrombectomy resulted in a significant reduction of thrombus material and improved flow in the pulmonary arteries and immediate marked clinical improvement and subsequent normalization of functional echocardiographic parameters.
This case adds to the emerging evidence for severe thromboembolic complications following COVID-19 and suggests aspiration thrombectomy can be considered in pulmonary embolism of intermediate risk.
Time-resolved rheometry was employed to study thermal and thermo-oxidative degradation of poly(ethylene terephthalate) (PET). Degradation results in a vertical downward shift of the complex viscosity ...in air atmosphere. We conclude that reduction of moduli and viscosity is governed by oligomers emerging from chain scission and acting as plasticizer. Additionally, cross-linking leading to a yield stress is observed at long times. In nitrogen atmosphere, polycondensation increases the molar mass and viscosity and extends the shear thinning regime. With longer degradation times, thermal degradation prevails and leads to a vertical downward shift. The reaction kinetics of three PETs with different molar mass was analyzed by a time constant
τ
assuming first-order kinetics. The low molecular weight PET exhibits the largest time constant in air atmosphere, and hence the lowest degradation rate, while high molecular weight PET exhibits a small
τ
and rapid degradation. The enhancement rate in nitrogen is vice versa.
2,3,7,8-Tetrachloro-dibenzo-
p-dioxin (TCDD) is an ubiquitously distributed xenobiotic. It has been postulated that the effects of TCDD on T-lymphocytes are mediated by modulation of the thymic ...microenvironment. There is growing evidence of a modified interplay between thymocytes and thymic epithelium related to changes in extracellular matrix (ECM) proteins.
Eighteen male marmosets (
Callithrix jacchus) were treated with single subcutaneous TCDD doses (1, 10, 100
ng/kg body weight) or vehicle and sacrificed 2 or 4 weeks thereafter. Thymus samples were stained with fluorescein isothiocyanate-conjugated antibodies for ECM proteins and examined immunohistochemically by semi-quantitative image analysis. Thymus samples of animals treated with 1 and 10
ng/kg were additionally analysed by Western blotting for ECM proteins, transforming growth factor-β
1 (TGF-β
1) and integrin chain content (CD49a, CD49e, CD49f and CD29).
Monkeys showed no overt signs of toxicity after TCDD treatment. Immunohistochemistry revealed an increase of ECM proteins at 100
ng/kg after 2 and 4 weeks. Western blotting confirmed immunohistochemistry showing a dose-dependent increase of several ECM proteins in animals treated with the lower TCDD doses of 1 and 10
ng/kg. Additionally, dose-dependent increases were observed in integrin chain and TGF-β
1 contents.
We demonstrated changes of thymic ECM in marmosets following low single TCDD doses. Combined with altered integrin expression and enhanced TGF-β
1 stimulation our findings suggest a modified interplay between thymic epithelium and thymocytes. The extracellular matrix may play a more central role in mediating adverse effects of TCDD in organs than yet acknowledged.
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