Pulmonary Vascular Thrombosis in COVID-19: Clinical and Morphological Parallels

Aim. We aimed to study the histological and thrombotic changes in lung vessels in patients who died with COVID-19, to access the correlation between anticoagulation therapy (ACT) and thrombotic events (TE), treatment results, clinical and laboratory patients' characteristics.Material and Methods. We retrospectively analyzed treatment results of patients hospitalized with COVID-19 and lung vessel samples of the deceased patients. Dynamic changes and highest levels of D-dimer and fibrinogen were studied in its correlation with the disease severity according to SOFA score, computer tomographic (CT) results, lung, renal and hepatic dysfunction. The association between different doses of ACT and treatment results, laboratory indicators and thrombotic events was accessed. The histological lung vessels examination was performed using Martius Scarlet Blue (MSB)staining.Results. 313 patients were included in the study (61 patients died). The median age of hospitalized patients was 60 years (IQR 51-66 years). The frequency of the intravitallyconfirmed TE was 4,8%. The strong statistical association was revealed between D-dimer level and 3-4 points SOFA score, patients' mortality, oxygen support requirement, CT3-CT4 pneumonia, glomerular filtration rate and TE. There was no mortality in patients with D-dimer normal references, but in cases with three times elevation reached 13%, 48,5% - in cases with 3-6 times elevation and 64,6% - in cases with more than 6 times elevation. The strong statistical association was registered between fibrinogen and SOFA score, CT 3-4 pneumonia, patients' mortality. D-dimer and fibrinogen levels demonstrated weak correlation. There was no statistical correlation between prophylactic, intermediate and therapeutic ACT and D-dimer and fibrinogen levels, CT results, patients' mortality. MSBstaining was used in 36 deceased patients tissue samples. 1394 lung vessels were analyzed. Lung vessels thrombi persisted in samples of all 36 patients (100%). Vessels with the diameter 3,5-30 mm were thrombosed in 7%, with the diameter 0,034-0,84 mm - in 48%, with the diameter 0,85-3,4 mm - in 45%. The frequency of thrombi persisted 06 hours, 6-12 hours, 12-18hours, 18-24 hours and more than 24 hours was12%, 14%, 62%, 5% and 7% respectively.Conclusion. Thrombi of different ages from fresh to organized were observed in one third of lung vessels in all deceased patients. Lung vessels thrombosis plays an important role in pathogenesis and thanatogenesis of COVID-19. The D-dimer level correlates with lung, renal dysfunction, patients' mortality and doesn't show any correlation with ACT and can be accepted as a criterion of lung vessel thrombotic progression

4D Imaging and Diffraction Dynamics of Single-Particle Phase Transition in Heterogeneous Ensembles

In this Letter, we introduce conical-scanning dark-field imaging in four-dimensional (4D) ultrafast electron microscopy to visualize single-particle dynamics of a polycrystalline ensemble undergoing phase transitions. Specifically, the ultrafast metal–insulator phase transition of vanadium dioxide is induced using laser excitation and followed by taking electron-pulsed, time-resolved images and diffraction patterns. The single-particle selectivity is achieved by identifying the origin of all constituent Bragg spots on Debye–Scherrer rings from the ensemble. Orientation mapping and dynamic scattering simulation of the electron diffraction patterns in the monoclinic and tetragonal phase during the transition confirm the observed behavior of Bragg spots change with time. We found that the threshold temperature for phase recovery increases with increasing particle sizes and we quantified the observation through a theoretical model developed for single-particle phase transitions. The reported methodology of conical scanning, orientation mapping in 4D imaging promises to be powerful for heterogeneous ensemble, as it enables imaging and diffraction at a given time with a full archive of structural information for each particle, for example, size, morphology, and orientation while minimizing radiation damage to the specimen

The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability

The ATLAS TRT electronics

The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system

Treatment and Secondary Prevention of Venous Thromboembolism in Real Clinical Practice Based on Health Care Professional Survey

Aim. To assess the duration of the anticoagulant treatment of venous thromboembolism (VTE) in various categories of patients in real clinical practice through survey of practitioners, as well as correspondence of the duration with current clinical guidelines.Material and methods. Data obtained from electronic survey of practicing surgeons as part of a commercial brand assessment (Brand Adoption Monitor) was studied. Survey was carried out by the "Validata” analytical agency at the request and with the financial support of Bayer. Inpatient and outpatient vascular surgeons, as well as general outpatient surgeons were invited to complete the electronic questionnaire. The number of interviewed specialists was 100: 50 inpatient vascular surgeons and 50 outpatient specialists, among whom the share of vascular surgeons (phlebologists, angi-ologists) was about 20%. The study was completed in 20 cities of Russia with a population of at least 200,000 people from all federal districts except the North Caucasus and the Republic of Crimea. The selection criteria for participants were: work experience in the specialty ≥3 years, work experience at the current organization >6 months, ≥5 patients with VTE during in the last month.Results. In total, 104 doctors were surveyed during the period from December 11, 2019 to January 20, 2020, of which 50 were inpatient vascular surgeons and 54 were from outpatient setting. According to the survey of vascular surgeons in hospitals, 75% (6 [5;10]) of patients were hospitalized with a primary episode of VTE and 25% (2 [1;4]) with a recurrent thrombotic event. In an outpatient surgeon, 27.5% (3 [2;5]) of patients were treated in an outpatient setting without hospitalization, 34.7% (3 [2;5]) came to an appointment immediately after discharge from the hospital and 38.8% (2 [1;4]) were a repeat visit regarding a previous VTE. Most often, surgeons observed episodes of clinically unprovoked VTE in 27.3% of cases, thrombotic events provoked by major transient risk factors were 12.2%, event provoked by small transient risk factors were 13.3% and events provoked by small persistent risk factors were 12.6%, while cancer-associated thrombosis represented 13.5%. Most surgeons chose to prescribe anticoagulant therapy beyond 3 months. About half of the specialists prescribed therapy for a year or longer for cancer-associated thrombosis and recurrent VTE. When treating the first episode of clinically unprovoked VTE, about half of the respondents chose anticoagulation for a period of 3 to 6 months. About 60% of specialists prescribed anticoagulant therapy for a period of 3 to 6 months to patients with minor transient or persistent risk factors and patients with VTE provoked by major transient risk factor (trauma or surgery).Conclusion. Correspondence of the duration of anticoagulant therapy in real clinical practice with the international clinical guidelines varies within 450% range and, on average, does not exceed 30%. This discrepancy was both in situations when the duration of therapy was lower than recommended, but also in situations when treatment extension would not have been recommended