Enolase is a <em>dimer</em>ic metal-activated metalloenzyme which uses two magnesium ions per subunit: the strongly bound conformational ion and the catalytic ion that binds to the enzyme-substrate complex inducing catalysis. The crystal structure of the human neuronal enolase-Mg<em>2</em>F<em>2</em>P(i) complex (enolase fluoride/phosphate inhibitory complex, EFPIC) determined at 1.36 A resolution shows that the combination of anions effectively mimics an intermediate state in catalysis. The phosphate ion binds in the same site as the phosphate group of the substrate/product, <em>2</em>-phospho-<em>D</em>-glycerate/phosphoenolpyruvate, and induces binding of the catalytic Mg<em>2</em>+ ion. One fluoride ion bridges the structural and catalytic magnesium ions while the other interacts with the structural magnesium ion and the ammonio groups of Lys 34<em>2</em> and Lys 393. These fluoride ion positions correspond closely to the positions of the oxygen atoms of the substrate's carboxylate moiety. To relate structural changes resulting from fluoride, phosphate, and magnesium ions binding to those that are induced by phosphate and magnesium ions alone, we also determined the structure of the human neuronal enolase-Mg<em>2</em>P(i) complex (enolase phosphate inhibitory complex, EPIC) at 1.9<em>2</em> A resolution. It shows the closed conformation in one subunit and a mixture of open and semiclosed conformations in the other. The EPFIC <em>dimer</em> is essentially symmetric while the EPIC <em>dimer</em> is asymmetric. Isothermal titration calorimetry data confirmed binding of four fluoride ions per <em>dimer</em> and yielded Kb values of 7.5 x 10(5) +/- 1.3 x 10(5), 1.<em>2</em> x 10(5) +/- 0.<em>2</em> x 10(5), 8.6 x 10(4) +/- 1.6 x 10(4), and 1.6 x 10(4) +/- 0.7 x 10(4) M(-1). The different binding constants indicate negative cooperativity between the subunits; the asymmetry of EPIC supports such an interpretation.

BACKGROUND

Pulmonary embolism (PE) is a potentially fatal disorder with highly varying mortality rates. To provide information that is more precise for prospective intervention studies, we analysed the data of our patients with PE, defining clinically relevant subgroups with respect to their individual mortality rates.

METHODS

We studied 283 consecutive patients with confirmed PE diagnosis, with respect to demographic data, risk factors for thromboembolic disease and clinical signs. In addition, diagnostic and therapeutic interventions such as blood gas analysis (BGA), lactate and D-dimer determination, electrocardiography (ECG), echocardiography, spiral computer tomography (Spiral CT), ventilation/perfusion lung scintigraphy (V/Q-Scan), thrombolytic therapy, mechanical ventilation, and cardiopulmonary resuscitation (CPR), were accounted for. Study endpoint was mortality rates on day three.

RESULTS

Overall, mortality rate was 15% (42 of 283). Mortality rates differed considerably; 95% of patients with cardiac arrest on arrival (21 of 22), 85% of patients with cardiac arrest--not in hospital (28 of 33), 80% of patients receiving mechanical ventilation (40 of 50), 77% of patients needing cardiopulmonary resuscitation within the first 24 hours (37 of 48), 37% of patients with syncope (18 of 49), 30% of patients receiving thrombolytic treatment (25 of 87), 26% of patients on whom lactate measurement was performed (36 of 139), 18% of patients on whom blood gas analysis was done (35 of 197), 17% of patients on whom echocardiography was performed (34 of 195), 8% of patients with twelve complete lead ECG recordings (21 of 262) and D-Dimer determination (12 of 148), 2% of patients tested on Spiral CT (5 of 226) and 1% where a V/Q-Scan was performed (1 of 74).

CONCLUSIONS

Patients with PE who received mechanical ventilation, cardiopulmonary resuscitation, and thrombolytic treatment had very high mortality rates of 80, 77 and 30% respectively. However, patients stable enough for diagnostic procedures as Spiral CTs and V/Q-Scans had mortality rates of 1 to 2%. These facts are to be considered when planning pulmonary embolism intervention trials in which reduction of mortality is a defined endpoint.

COVI<em>D</em>-19 is also manifested with hypercoagulability, pulmonary intravascular coagulation, microangiopathy, and venous thromboembolism (VTE) or arterial thrombosis. Predisposing risk factors to severe COVI<em>D</em>-19 are male sex, underlying cardiovascular disease, or cardiovascular risk factors including noncontrolled diabetes mellitus or arterial hypertension, obesity, and advanced age. The VAS-European Independent Foundation in Angiology/Vascular Medicine draws attention to patients with vascular disease (V<em>D</em>) and presents an integral strategy for the management of patients with V<em>D</em> or cardiovascular risk factors (V<em>D</em>-CVR) and COVI<em>D</em>-19. VAS recommends (1) a COVI<em>D</em>-19-oriented primary health care network for patients with V<em>D</em>-CVR for identification of patients with V<em>D</em>-CVR in the community and patients' education for disease symptoms, use of eHealth technology, adherence to the antithrombotic and vascular regulating treatments, and (<em>2</em>) close medical follow-up for efficacious control of V<em>D</em> progression and prompt application of physical and social distancing measures in case of new epidemic waves. For patients with V<em>D</em>-CVR who receive home treatment for COVI<em>D</em>-19, VAS recommends assessment for (1) disease worsening risk and prioritized hospitalization of those at high risk and (<em>2</em>) VTE risk assessment and thromboprophylaxis with rivaroxaban, betrixaban, or low-molecular-weight heparin (LMWH) for those at high risk. For hospitalized patients with V<em>D</em>-CVR and COVI<em>D</em>-19, VAS recommends (1) routine thromboprophylaxis with weight-adjusted intermediate doses of LMWH (unless contraindication); (<em>2</em>) LMWH as the drug of choice over unfractionated heparin or direct oral anticoagulants for the treatment of VTE or hypercoagulability; (3) careful evaluation of the risk for disease worsening and prompt application of targeted antiviral or convalescence treatments; (4) monitoring of <em>D</em>-<em>dimer</em> for optimization of the antithrombotic treatment; and (5) evaluation of the risk of VTE before hospital discharge using the IMPROVE-<em>D</em>-<em>dimer</em> score and prolonged post-discharge thromboprophylaxis with rivaroxaban, betrixaban, or LMWH.

Clotting abnormalities are well-recognized complications that occur with high frequency in patients suffering from underlying malignant diseases. New and highly sensitive molecular markers of hemostasis, thrombin-antithrombin III complex (TAT III), <em>D</em>-<em>dimer</em> fragments (<em>D</em><em>D</em>), and plasmin-alpha <em>2</em>-antiplasmin complex (PIC) were measured in 58 consecutive lung cancer patients. Significant elevation in the blood concentrations of <em>D</em><em>D</em>, PIC, and TAT was found in lung cancer patients, with either extensive or limited disease compared with values obtained in a healthy control group and in another group of patients with chronic obstructive pulmonary disease. Patients with distant metastasis exhibited significantly higher levels of these parameters as compared to those without metastasis. These data indicated that there was a subclinical activation of blood coagulation and fibrinolysis in lung cancer from the early clinical stages of the disease. In addition, there appeared to be different levels of clotting activation according to histologic type of tumor and response to chemotherapy.

BACKGROUND

The link between long-haul air travel and venous thromboembolism is the subject of continuing debate. It remains unclear whether the reduced cabin pressure and oxygen tension in the airplane cabin create an increased risk compared with seated immobility at ground level.

OBJECTIVE

To determine whether hypobaric hypoxia, which may be encountered during air travel, activates hemostasis.

METHODS

A single-blind, crossover study, performed in a hypobaric chamber, to assess the effect of an 8-hour seated exposure to hypobaric hypoxia on hemostasis in 73 healthy volunteers, which was conducted in the United Kingdom from September <em>2</em>003 to November <em>2</em>005. Participants were screened for factor V Leiden G1691A and prothrombin G<em>2</em>0<em>2</em>10A mutation and were excluded if they tested positive. Blood was drawn before and after exposure to assess activation of hemostasis.

METHODS

Individuals were exposed alternately >> or =1 week apart) to hypobaric hypoxia, similar to the conditions of reduced cabin pressure during commercial air travel (equivalent to atmospheric pressure at an altitude of <em>2</em>438 m), and normobaric normoxia (control condition; equivalent to atmospheric conditions at ground level, circa 70 m above sea level).

METHODS

Comparative changes in markers of coagulation activation, fibrinolysis, platelet activation, and endothelial cell activation.

RESULTS

Changes were observed in some hemostatic markers during the normobaric exposure, attributed to prolonged sitting and circadian variation. However, there were no significant differences between the changes in the hypobaric and the normobaric exposures. For example, the median difference in change between the hypobaric and normobaric exposure was 0 ng/mL for thrombin-antithrombin complex (95% CI, -0.30 to 0.30 ng/mL); -0.0<em>2</em> [corrected] nmol/L for prothrombin fragment 1 + <em>2</em> (95% CI, -0.03 to 0.01 nmol/L); 1.38 ng/mL for <em>D</em>-<em>dimer</em> (95% CI, -3.63 to 9.7<em>2</em> ng/mL); and -<em>2</em>.00% for endogenous thrombin potential (95% CI, -4.00% to 1.00%).

CONCLUSIONS

Our findings do not support the hypothesis that hypobaric hypoxia, of the degree that might be encountered during long-haul air travel, is associated with prothrombotic alterations in the hemostatic system in healthy individuals at low risk of venous thromboembolism.

We hypothesized that the 'residual' thromboembolic risk in therapeutically anticoagulated patients undergoing cardioversion could potentially be related to abnormal haemorheology and platelet activation. To test this hypothesis, we firstly investigated the role of haemorheology and platelet activation in patients with paroxysmal and persistent atrial fibrillation (AF), who were compared with healthy controls and patients with permanent AF. Second, we compared these indices in patients with persistent AF, before and after successful cardioversion. We measured indices of haemorheology (haematocrit, plasma viscosity, and fibrinogen), fibrin <em>D</em>-<em>dimer</em> (an index of thrombogenesis and fibrin turnover) and platelet activation (as assessed by platelet aggregation and plasma levels of beta-thromboglobulin, and soluble P-selectin) in <em>2</em>9 patients with paroxysmal AF, 87 patients with permanent AF and <em>2</em>9 healthy controls in sinus rhythm. The effects of cardioversion were studied in <em>2</em>0 patients with persistent AF, who maintained sinus rhythm at <em>2</em> months follow-up. Plasma levels of beta-thromboglobulin (P = 0.03) and fibrin <em>D</em>-<em>dimer</em> (P = 0.001) were higher in patients with AF, when compared with controls; the highest levels were seen in those with permanent AF (Tukey's test, < 0.05). Plasma viscosity was significantly higher in the patients with paroxysmal AF compared with healthy controls (P = 0.0<em>2</em>). Plasma soluble P-selectin levels and platelet aggregation responses to all four platelet agonists (adenosine diphosphate, collagen, epinephrine and thrombin) in patients with paroxysmal AF and permanent AF were similar to controls. Plasma fibrinogen, viscosity and other markers of platelet activation (including platelet aggregation) were not significantly different in patients with paroxysmal AF, during episodes of AF and sinus rhythm (P = not significant), although mean haematocrit was significantly higher during the episodes of AF compared with episodes of sinus rhythm (P = 0.03). Among the patients with persistent AF who remained in sinus rhythm at <em>2</em> months following successful cardioversion, there was a significant decrease in the plasma levels of soluble P-selectin at <em>2</em> weeks and <em>2</em> months, when compared with baseline (pre-cardioversion) levels (P < 0.001). Haemorheology and platelet aggregation response to agonists did not change significantly, except for a transient increase in platelet aggregation response to collagen at <em>2</em> weeks (P = 0.045). In conclusion. abnormal haemostatic and platelet activation in patients with permanent AF are not consistently observed in patients with paroxysmal and persistent AF. Abnormal haemorheology appears to play an important role in patients with paroxysmal AF, especially during the paroxysms of AF. Cardioversion of persistent AF to sinus rhythm appears to decrease the platelet activation, but whether this translates into a beneficial reduction in thromboembolic risk requires further study.

BACKGROUND

Bullous pemphigoid (BP) is a blistering skin disease caused by autoantibodies to hemidesmosomal proteins, with eosinophils participating in blister formation. Eosinophils are a source of tissue factor (TF), an initiator of blood coagulation.

OBJECTIVE

To evaluate the local and systemic activation of coagulation in BP.

METHODS

We stu<em>d</em>ie<em>d</em> <em>2</em>0 patients with active BP (eight re-evaluate<em>d</em> <em>d</em>uring remission) an<em>d</em> 40 controls. The coagulation markers prothrombin fragment F1+<em>2</em> an<em>d</em> <em>d</em>-<em>dimer</em> were measure<em>d</em> in the plasma of all subjects an<em>d</em> in both plasma an<em>d</em> blister flui<em>d</em> of patients with BP. TF was evaluate<em>d</em> immunohistochemically in skin specimens from the <em>2</em>0 patients an<em>d</em> in <em>2</em>0 normal samples.

RESULTS

F1+<em>2</em> an<em>d</em> <em>d</em>-<em>dimer</em> levels were higher in plasma of patients with BP (649 +/- 96 pmol L(-1) an<em>d</em> 18.5<em>2</em> +/- 3.44 nmol L(-1), respectively) than in plasma of controls (157 +/- 7 pmol L(-1) an<em>d</em> 1.4<em>2</em> +/- 0.06 nmol L(-1); P = 0.0001), an<em>d</em> were very high in blister flui<em>d</em> (40 449 +/- 3491 pmol L(-1) an<em>d</em> 153<em>2</em>.3<em>2</em> +/- <em>2</em>6<em>2</em>.81 nmol L(-1); P = 0.0001). Plasma an<em>d</em> blister flui<em>d</em> F1+<em>2</em> an<em>d</em> <em>d</em>-<em>dimer</em> levels parallele<em>d</em> bloo<em>d</em> an<em>d</em> tissue eosinophilia an<em>d</em> <em>d</em>isease severity. In the eight patients re-evaluate<em>d</em> <em>d</em>uring remission, there was a marke<em>d</em> re<em>d</em>uction in F1+<em>2</em> (from 11<em>2</em>7 +/- 144 to <em>2</em>87 +/- 5<em>2</em> pmol L(-1); P = 0.005) an<em>d</em> <em>d</em>-<em>dimer</em> (from <em>2</em>4.03 +/- 4.08 to 4.69 +/- 1.51 nmol L(-1); P = 0.0<em>2</em>9). Immunohistochemistry reveale<em>d</em> strong TF reactivity in BP skin (P = 0.0001), an<em>d</em> colocalization stu<em>d</em>ies confirme<em>d</em> eosinophils as a source of TF.

CONCLUSIONS

The coagulation cascade is activated in BP and correlates with the severity of the disease and with eosinophilia, indicating that eosinophils play a role in coagulation activation via TF. The hypercoagulability may contribute to inflammation, tissue damage, blister formation and possibly thrombotic risk in BP.

Portal thrombosis may complicate the clinical course of cirrhosis, but the pathophysiologic mechanism is unclear. Aim of the study was to evaluate the behavior of clotting system and endotoxemia in portal vein and in peripheral circulation of 11 cirrhotic patients undergoing transjugular port-systemic shunt (TIPS). Portal blood showed higher values of F1 + <em>2</em> [Median (range): <em>2</em>.5 (1.1-5.3) vs. 1.1 (0.6-<em>2</em>.1) nM, p < 0.01], <em>D</em>-<em>dimer</em> [765 (184-1713) vs. 19<em>2</em> (64-813) ng/ml, p < 0.01] and endotoxemia [31 (16-47.<em>2</em>) vs. 13.7 (7.5-<em>2</em>3.5) pg/ml, p < 0.01] than peripheral circulation. In the portal vein, all but one sample had F1 + <em>2</em>>> 1.<em>2</em> nM (upper limit of control values), all but one had <em>D</em>-<em>dimer</em>>> <em>2</em>16 mg/dl (mean + <em>2</em> S<em>D</em> of controls) and 100% had values of endotoxemia>> 9.6 pg/ml (upper limit of control values). Fibrinogen was lower in the portal circulation compared to peripheral circulation but the difference was not significant [85 (58-195) vs. 134 (75-<em>2</em>44) mg/dl, p>> 0.05]. Endotoxemia was directly correlated with F1 + <em>2</em> (Rho = 0.9<em>2</em> p < 0.006) and <em>D</em>-<em>dimer</em> (Rho = 0.93, p < 0.005). This study shows that an ongoing prothrombotic state is present in the portal circulation of cirrhotic patients and may play a pivotal role in the thrombotic episodes occurring in this clinical setting.

Tang et al. recently reported that (Journal of Thrombosis and Haemostasis), in COVI<em>D</em>-19 infections caused by the novel coronavirus (SARS-CoV-<em>2</em>), heparin anticoagulant therapy lowers the mortality rate in patients who present with markedly elevated concentrations of <em>D</em>-<em>dimer</em> 1). In other words, abnormal coagulation may influence the prognosis of COVI<em>D</em>-19. This is extremely interesting. The article did not describe to what extent heparin improves the abnormal coagulation and further studies by this group are anticipated. The authors reported in that article 1) and a previous article <em>2</em>) that the abnormal coagulation seen in non-survivors of COVI<em>D</em>-19 clearly differs from the abnormal coagulation typically seen in other severe infectious diseases.

Severe acute respiratory syndrome coronavirus <em>2</em> (SARS-Cov-<em>2</em>), also known as coronavirus disease <em>2</em>019 (COVI<em>D</em>-19)-induced infection, is strongly associated with various coagulopathies that may result in either bleeding and thrombocytopenia or hypercoagulation and thrombosis. Thrombotic and bleeding or thrombotic pathologies are significant accompaniments to acute respiratory syndrome and lung complications in COVI<em>D</em>-19. Thrombotic events and bleeding often occur in subjects with weak constitutions, multiple risk factors and comorbidities. Of particular interest are the various circulating inflammatory coagulation biomarkers involved directly in clotting, with specific focus on fibrin(ogen), <em>D</em>-<em>dimer</em>, P-selectin and von Willebrand Factor (VWF). Central to the activity of these biomarkers are their receptors and signalling pathways on endothelial cells, platelets and erythrocytes. In this review, we discuss vascular implications of COVI<em>D</em>-19 and relate this to circulating biomarker, endothelial, erythrocyte and platelet dysfunction. <em>D</em>uring the progression of the disease, these markers may either be within healthy levels, upregulated or eventually depleted. Most significant is that patients need to be treated early in the disease progression, when high levels of VWF, P-selectin and fibrinogen are present, with normal or slightly increased levels of <em>D</em>-<em>dimer</em> (however, <em>D</em>-<em>dimer</em> levels will rapidly increase as the disease progresses). Progression to VWF and fibrinogen depletion with high <em>D</em>-<em>dimer</em> levels and even higher P-selectin levels, followed by the cytokine storm, will be indicative of a poor prognosis. We conclude by looking at point-of-care devices and methodologies in COVI<em>D</em>-19 management and suggest that a personalized medicine approach should be considered in the treatment of patients.

Keywords: COVID-19; bleeding; fibrin(ogen); thrombosis.

The presence of SARS-CoV-<em>2</em> was officially documented in Europe at the end of February <em>2</em>0<em>2</em>0. <em>D</em>espite many observations, the real impact of COVI<em>D</em>-19 in the European Union (EU), its underlying factors and their contribution to mortality and morbidity outcomes were never systematically investigated. The aim of the present work is to provide an overview and a meta-analysis of main predictors and of country differences of severe acute respiratory syndrome coronavirus <em>2</em> (SARS-CoV-<em>2</em>) infection-associated mortality rate (MR) in hospitalized patients. Out of 3714 retrieved articles, 87 studies were considered, including 35,486 patients (mean age 60.9 ± 8.<em>2</em> years) and 5867 deaths. After adjustment for confounders, diabetes mellitus was the best predictors of MR in an age- and sex-dependent manner, followed by chronic pulmonary obstructive diseases and malignancies. In both the US and Europe, MR was higher than that reported in Asia (<em>2</em>5[<em>2</em>0;<em>2</em>9] % and <em>2</em>0[17;<em>2</em>3] % vs. 13[10;17]%; both p < 0.0<em>2</em>). Among clinical parameters, dyspnea, fatigue and myalgia, along with respiratory rate, emerged as the best predictors of MR. Finally, reduced lymphocyte and platelet count, along with increased <em>D</em>-<em>dimer</em> levels, all significantly contributed to increased mortality. The optimization of glucose profile along with an adequate thrombotic complications preventive strategy must become routine practice in diseased SARS-CoV-<em>2</em> infected patients.

<strong class="sub-title"> Keywords: </strong> COVI<em>D</em>-19; <em>D</em>iabetes mellitus; SARS-CoV-<em>2</em>; hospitalization; male; mortality; testosterone.

<strong class="sub-title"> Background: </strong> Coronavirus disease <em>2</em>019 (COVI<em>D</em>-19) has been widely spread and caused tens of thousands of deaths, especially in patients with severe COVI<em>D</em>-19. This analysis aimed to explore risk factors for mortality of severe COVI<em>D</em>-19, and establish a scoring system to predict in-hospital deaths.

Methods: Patients with COVID-19 were retrospectively analyzed and clinical characteristics were compared. LASSO regression as well as multivariable analysis were used to screen variables and establish prediction model.

<strong class="sub-title"> Findings: </strong> A total of <em>2</em>5<em>2</em>9 patients with COVI<em>D</em>-19 was retrospectively analyzed, and 45<em>2</em> eligible severe COVI<em>D</em>-19 were used for finally analysis. In training cohort, the median age was 66•0 years while it was 73•0 years in non-survivors. Patients aged 60-75 years accounted for the largest proportion of infected populations and mortality toll. Anti-SARS-CoV-<em>2</em> antibodies were monitored up to 54 days, and IgG levels reached the highest during <em>2</em>0-30 days. No differences were observed of antibody levels between severe and non-severe patients. About 60.<em>2</em>% of severe patients had complications. Among acute myocardial injury (AMI), acute kidney injury (AKI) and acute liver injury (ALI), the heart was the earliest injured organ, whereas the time from AKI to death was the shortest. Age, diabetes, coronary heart disease (CH<em>D</em>), percentage of lymphocytes (LYM%), procalcitonin (PCT), serum urea, C reactive protein and <em>D</em>-<em>dimer</em> (<em>D</em><em>D</em>), were identified associated with mortality by LASSO binary logistic regression. Then multivariable analysis was performed to conclude that old age, CH<em>D</em>, LYM%, PCT and <em>D</em><em>D</em> remained independent risk factors for mortality. Based on the above variables, a scoring system of COVI<em>D</em>-19 (CSS) was established to divide patients into low-risk and high-risk groups. This model displayed good discrimination (AUC=0·919) and calibration (<i>P</i>=0·<em>2</em>64). Complications in low-risk and high-risk groups were significantly different (<i>P<</i>0·05). Use of corticosteroids in low-risk groups increased hospital stays by 4·5 days (<i>P</i>=0·036) and durations of disease by 7·5 days (<i>P</i>=0·01<em>2</em>) compared with no corticosteroids.

Interpretation: Old age, CHD, LYM%, PCT and DD were independently related to mortality. CSS was useful for predicting in-hospital mortality and complications, and it could help clinicians to identify high-risk patients with poor prognosis.

<strong class="sub-title"> Funding: </strong> This work was supported by the Key Project for Anti-<em>2</em>019 novel Coronavirus Pneumonia from the Ministry of Science and Technology, China (grant number <em>2</em>0<em>2</em>0YFC0845500).

Keywords: Antibody; COVID-19; Critical ill; Mortality; Scoring system.

Although a significant minority of patients with cyanotic congenital heart disease (CCH<em>D</em>) are thrombocytopenic, the pathogenesis and prevalence have not been established. This study was designed to address these <em>2</em> issues. We included 105 patients with CCH<em>D</em> (60 men and 45 women; aged <em>2</em>1 to 54 years). Systemic arterial oxygen saturations were 69% to 78%. Hematocrits were 6<em>2</em>% to 74% with normal iron indexes. In <em>2</em>6 of 105 patients (<em>2</em>5%), platelet counts were <100x10(9)/L. The diagnosis was Eisenmenger syndrome in all <em>2</em>6 patients with thrombocytopenia. Platelet production was determined by flow cytometric reticulated platelet counts. Megakaryocyte mass was determined indirectly by thrombopoietin levels. <em>D</em>isseminated intravascular coagulation was based on prothrombin time, activated partial thromboplastin time, and <em>D</em>-<em>dimers</em>. Platelet activation was determined by levels of platelet factor 4 and beta thromboglobulin. Reference ranges were derived from <em>2</em>0 normal acyanotic controls. A reduction in absolute reticulated platelet counts implied decreased platelet production (p<0.001). Normal thrombopoietin levels implied normal megakaryocyte mass. Normal prothrombin time, activated partial thromboplastin time, and <em>D</em>-<em>dimers</em> excluded disseminated intravascular coagulation. Normal platelet factor 4 and beta thromboglobulin indicated absent or minimal platelet activation. Twenty-five percent of the patients with CCH<em>D</em> were thrombocytopenic because platelet production was decreased despite normal megakaryocyte mass. We hypothesized that right-to-left shunts deliver whole megakaryocytes into the system arterial circulation, bypassing the lungs where megakaryocytic cytoplasm is fragmented into platelets, thus reducing platelet production. In conclusion, platelet counts in CCH<em>D</em> appear to represent a continuum beginning with low normal counts and ending with thrombocytopenia.

OBJECTIVE

Plasma d-dimer levels, measured using a research laboratory assay, independently predict progressing ischemic stroke. We wished to confirm these findings using commercially available assays and to provide data to allow the design of intervention studies.

METHODS

We studied 219 consecutive acute ischemic stroke admissions of whom 54 (25%) met criteria for progressing stroke.

RESULTS

There were strong correlations between d-dimer results as measured by the Biopool AB, MDA and VIDAS assays; correlation coefficients r=0.91 to 0.94; all P<0.001. In binary logistic regression analyses, d-dimer, as measured by the 3 different assays, was an independent predictor of progressing stroke (odds ratios, 1.87 to 2.45; all P<0.001). This confirms the results of our original analysis (Biopool AB) using 2 commercial d-dimer assays, demonstrating the potential usefulness of d-dimer in providing early prognostic information after ischemic stroke in different clinical settings. We also provide information on the performance of the 3 assays in predicting progressing stroke at a variety of cutoff values.

CONCLUSIONS

Ischemic stroke patients at high risk of early progression can be identified using commercial d-dimer measurements. This could allow selection of high-risk patients for inclusion in randomized trials of early antithrombotic treatments.

The lipopeptide lichenysin (cyclo-[L-Gln1->><em>D</em>-Leu<em>2</em>->>L-Leu3->>L-Val4->> L-Asp5->><em>D</em>-Leu6->>L-Ile7-beta-OH fatty acid]) produced by Bacillus licheniformis structurally resembles surfactin from Bacillus subtilis. The main difference is the presence of a glutaminyl residue in position 1 of the peptide sequence in place of glutamic acid in surfactin. This local variation causes significant changes in the properties of the molecule compared to surfactin. Lichenysin has a higher surfactant power, the critical micellar concentration (c.m.c.) being strongly reduced from <em>2</em><em>2</em>0 to <em>2</em><em>2</em> microM and a much higher hemolytic activity because 100% hemolysis was observed with only 15 microM instead of <em>2</em>00 microM. Lichenysin is also a better chelating agent because its association constants with Ca<em>2</em>+ and Mg<em>2</em>+ are increased by a factor of 4 and 16, respectively. This effect is assigned to an increase in the accessibility of the carboxyl group to cations owing to a change in the side chain topology induced by the Glu/Gln exchange. Additionally, the propensity of the lipopeptide for extensive hydrophobic interactions, as illustrated by its low c.m.c., contributes to further stabilization of the cation and an increase in the partitioning of lichenysin into the erythrocyte membrane. Our data support the formation of a lichensyin-Ca<em>2</em>+ complex in a molar ratio of <em>2</em>:1 instead of 1:1 with surfactin, suggesting an intermolecular salt bridge between two lichenysin molecules. Therefore, when Ca<em>2</em>+ ions are present in the solution, micellization occurs via a <em>dimer</em> assembly, with a possible long-range effect on the spatial arrangement of the micelles or other supramolecular structures. Finally, among all the surfactin peptidic variants so far known, lichenysin is the one for which the three tested activities are the most substantially improved.

Herein we developed a new "smart" Gd-based MR contrast agent (i.e., 1) which is susceptive to furin, a protease overexpressed in tumor. Under the action of furin, 1 condenses to form <em>dimers</em> (1-<em>D</em>s) and the latter self-assemble into gadolinium nanparticles (Gd-NPs). Relaxivity of 1-<em>D</em> is more than <em>2</em> folds of those of 1 and magnevist at 1.5 T, and 1.4 folds of that of 1 at 3 T. Intracellular condensation of 1 in furin-overexpressed M<em>D</em>A-MB-468 cells was proven with direct two-photon laser microscopy (TPLM) fluorescence imaging of the cells incubated with the europium analog of 1 (i.e., <em>2</em>). Intracellular Gd-NPs of 1 were uncovered and characterized for the first time. MRI of M<em>D</em>A-MB-468 tumors showed that 1 has enhanced MR contrast within the tumors than that of its scrambled control 1-Scr.

Cutaneous manifestations in patients with COVI<em>D</em>-19 infection are being increasingly reported. Several patterns have been described since the initial report by Recalcati,¹ including erythematous maculo-papular,¹ urticarial,^1,<em>2</em> chickenpox-like,^1,3 purpuric peri-flexural,⁴ transient livedo reticularis,⁵ and acro-ischemic or chilblain-like lesions.^6,7 Herein we report the observation a new pattern with erythema multiforme-like lesions in 4 hospitalized patients with COVI<em>D</em>-19 infection. All of them were women, and the mean age was 66.75 years (range 58 - 77). The mean time period between the onset of COVI<em>D</em>-19 symptoms to the appearance of cutaneous lesions was 19.5 days (range 16 - <em>2</em>4). One patient developed the skin rash during hospitalization. The remaining 3 patients had been previously discharged after clinical, analytical and radiologic improvement, and negativization of COVI<em>D</em>-19 PCR test. These 3 patients returned to the Emergency department consulting for skin rashes 6, 7 and 4 days after discharge, respectively. Laboratory tests at the time of skin lesions showed worsening of one or more parameters, compared to those at the time of discharge (CRP, <em>D</em>-<em>dimer</em> and lymphocyte count). However, none of the patients presented recurrence of clinical symptoms of COVI<em>D</em>-19. Microbiological studies were performed in <em>2</em> patients, excluding other infectious diseases (Table 1). In all patients, skin lesions begun as erythematous papules in upper trunk, that progressively turned to erythemato-violaceous patches with a dusky center, and a pseudo-vesicle in the middle. Typical target lesions were observed in two patients. Lesions were markedly coalescing in the back, and then spread to the face and limbs within 1 week, without involvement of palms and soles (Figure 1). Three patient had their oral cavity examined, showing palatal macules and petechiae. Histological examination was similar in all patients, revealing a normal basket-weave stratum corneum, and mild to moderate spongiosis in epidermis. The dermis showed dilated vessels filled with neutrophils, extravasation of red blood cells, and lymphocytic perivascular and interstitial infiltrate. Basal vacuolar changes with interface dermatitis was observed in 1 patient, and lymphocytic exocytosis in another (Figure <em>2</em>). All patients were treated with systemic corticosteroids with progressive resolution of the skin lesions within <em>2</em>-3 weeks. We are facing challenging times in <em>D</em>ermatology. New information and cutaneous manifestations possibly related to COVI<em>D</em>-19 are emerging every day. Further studies are needed to evaluate whether these lesions are associated with the virus, the drug intake or any other conditions. Erythema multiforme (EM) is linked to infectious agents in 90% of the cases, while drug-associated EM is reported in less than 10% of cases. Herpes simplex virus (HSV) and Mycoplasma pneumoniae are the main agents, but other viruses have been reported, such as Adenovirus, Coxsackie, Parvovirus B19.⁸ We suggest that this EM-like or target-like exanthem might be another pattern of exanthem associated with COVI<em>D</em>-19 infection. Recent articles also report targetoid lesions in exanthems of patients with COVI<em>D</em>-19 infection.^9,10 In addition, the presence of pseudo-vesicles and enanthem are two clues that suggest an infectious cause rather than a drug reaction. However, we cannot positively exclude the involvement of the various drugs administered to the patients. This is a first observation that will require further investigations.

We described features of hospitalized Covid-19 patients and identified predictors of clinical deterioration. We included patients consecutively admitted at Humanitas Research Hospital (Rozzano, Milan, Italy); retrospectively extracted demographic; clinical; laboratory and imaging findings at admission; used survival methods to identify factors associated with clinical deterioration (defined as intensive care unit (ICU) transfer or death), and developed a prognostic index. Overall; we analyzed 239 patients (29.3% females) with a mean age of 63.9 (standard deviation [SD]; 14.0) years. Clinical deterioration occurred in 70 patients (29.3%), including 41 (17.2%) ICU transfers and 36 (15.1%) deaths. The most common symptoms and signs at admission were cough (77.8%) and elevated respiratory rate (34.1%), while 66.5% of patients had at least one coexisting medical condition. Imaging frequently revealed ground-glass opacity (68.9%) and consolidation (23.8%). Age; increased respiratory rate; abnormal blood gas parameters and imaging findings; coexisting coronary heart disease; leukocytosis; lymphocytopenia; and several laboratory parameters (elevated procalcitonin; interleukin-6; serum ferritin; C-reactive protein; aspartate aminotransferase; lactate dehydrogenase; creatinine; fibrinogen; troponin-I; and D-dimer) were significant predictors of clinical deterioration. We suggested a prognostic index to assist risk-stratification (C-statistic; 0.845; 95% CI; 0.802‒0.887). These results could aid early identification and management of patients at risk, who should therefore receive additional monitoring and aggressive supportive care.

Keywords: 2019 novel coronavirus; 2019-nCoV; COVID-19; SARS-CoV-2; severe acute respiratory syndrome coronavirus 2.

Coronavirus disease <em>2</em>019 (COVI<em>D</em>-19) represents a new pandemic caused by severe acute respiratory syndrome virus coronavirus <em>2</em> (SARS-CoV-<em>2</em>). A previous pooled analysis clearly identified elevated <em>D</em>-<em>dimer</em> levels as being associated with severity of COVI<em>D</em>-19. Since then, several other studies have provided clearer support for this initial evidence. However, potentially under-recognized by those reporting on <em>D</em>-<em>dimer</em> is the considerable variation in reporting units for <em>D</em>-<em>dimer</em>, and thus also the potential for misreporting of <em>D</em>-<em>dimer</em> data based on poor or incomplete reporting. A PubMed search was used to identify recent papers reporting on <em>D</em>-<em>dimers</em> in COVI<em>D</em>-19-based studies. We report that: (1) most publications did not identify either the manufacturer or <em>D</em>-<em>dimer</em> product used; (<em>2</em>) most did not identify whether <em>D</em>-<em>dimer</em> values were reported as <em>D</em>-<em>dimer</em> units (<em>D</em><em>D</em>U) or fibrinogen equivalent units (FEU) (~<em>2</em> × differences); (3) nearly half did not identify normal cut-off values; (4) some did not report numerical findings or units for <em>D</em>-<em>dimer</em>; (5) where reported, most identified units as either mg/L or μg/mL; (6) we identified at least four errors in reporting from <em>2</em>1 papers. It may not be possible to truly standardize <em>D</em>-<em>dimer</em> assays, but it should be feasible to harmonize <em>D</em>-<em>dimer</em> assays to a single unit of measurement.

Keywords: COVID-19; D-dimer; thrombosis; units.

Rare cases of macrophage activation syndrome (MAS) occurring during the acute phase of Kawasaki disease (K<em>D</em>) have been reported. We sought to characterize, review treatment, and outcomes of K<em>D</em> patients with clinical features of MAS. Medical histories of patients treated for K<em>D</em> and MAS between January <em>2</em>001 and March <em>2</em>008 were reviewed. Of 638 K<em>D</em> patients seen, 1<em>2</em> (1.9%) had additional clinical findings usually associated with MAS; 7 of them were males older than 5 years (6.1%; odds ratio: 6.8, P=0.00<em>2</em>). Clinically, 9 patients had at least 4 of 5 K<em>D</em> clinical signs, and all patients had prolonged fever beyond initial intravenous immunoglobulin treatment. Hepatosplenomegaly, cytopenia in two or more cell lines, hypertriglyceridemia and/or hypofibrinogenemia, and increased <em>D</em>-<em>dimers</em> were seen in 11 patients. Hyperferritinemia and elevated hepatic enzymes were seen in all patients. Four patients had biopsy-proven evidence of hemophagocytosis. All but <em>2</em> patients met at least 5 of 8 criteria necessary for MAS diagnosis. Treatment beyond the standard K<em>D</em> protocol (aspirin + intravenous immunoglobulin) was necessary in all but 1 patient. All patients eventually recovered with no long-term sequelae. A high index of suspicion for clinical features associated with MAS is warranted for K<em>D</em> patients to provide appropriate and timely treatment.

OBJECTIVE

To assess the influence of tourniquet inflation-deflation as well as desmopressin and tranexamic acid (TA) administration on prothrombin fragment 1.2, fibrinogen, plasmin antiplasmin complex, and D-dimer concentrations during total knee replacement.

METHODS

Randomized, placebo-controlled study.

METHODS

Large referral hospital.

METHODS

30 ASA physical status I, II, and III patients undergoing total knee replacement.

METHODS

Patients were randomized to one of three treatment groups. Patients received either tranexamic acid, desmopressin, or an equal volume of saline, intravenously.

RESULTS

Cubital blood was drawn immediately before induction of anesthesia, 1 hour after tourniquet application, and 2 and 15 minutes after tourniquet deflation. Fibrinogen and D-dimer levels were measured using the Clauss Method and latex agglutination, respectively. Plasmin antiplasmin complex and prothrombin fragment 1.2 levels were measured by enzyme-linked immunosorbent assay (ELISA). All assays were performed in duplicate, and intra-assay variability was documented. No statistically significant difference in fibrinogen, D-dimer, plasmin antiplasmin complex, or prothrombin fragment 1.2 levels was demonstrated among the groups. Similarly, within each group there were no statistically significant differences in the variables studied. However, despite the lack of statistical significance, when compared with their levels during tourniquet application, an increase in D-dimer and plasmin antiplasmin complex levels was observed in all three groups at 2 and 15 minutes after tourniquet release. In contrast, no increase in prothrombin fragment 1.2 generation was noted. Significantly more allogeneic blood was transfused in the Control and Desmopressin Groups when compared with the tranexamic acid group (p< 0.02).

CONCLUSIONS

No evidence of tourniquet-induced fibrinolysis or thrombin generation was demonstrated in the systemic circulation. Desmopressin and tranexamic acid had no significant effect on the variables measured.

Cross-linking of antibodies constitutes a widespread initiation signal for their respective effector functions. Cross-linking IgE-class antibodies provide the triggering signal to mast cells for their degranulation process. To obtain a quantitative insight into these cross-linking processes, the interactions between a <em>D</em>NP-specific monoclonal antibody of the IgE class and a series of divalent <em>D</em>NP haptens with spacers of different length and flexibility have been studied by fluorescence titration experiments. These were analyzed by employing the theoretical model developed by <em>D</em>embo and Goldstein [<em>D</em>embo, M., & Goldstein, B. (1978) J. Immunol. 1<em>2</em>1, 345-353] in a fitting procedure. Equilibrium constants that describe the aggregation and ring-closure processes caused by divalent hapten binding have been used as free parameters. The intrinsic binding constants were determined by fluorescence titrations with corresponding monovalent haptens. The main results are the following: (1) The divalent haptens with a short and flexible spacer [i.e., N alpha, N epsilon-di-(<em>D</em>NP)-L-lysine,meso-bis[(<em>D</em>NP-beta-Ala)amino]succinate, and bis[(<em>D</em>NP-tri-<em>D</em>-Ala)amino]heptane, having a maximal <em>D</em>NP-<em>D</em>NP distance of gamma = 14, <em>2</em>1, and 45 A, respectively] effect aggregation of the antibodies mainly into closed <em>dimers</em>. (<em>2</em>) The divalent hapten family with long and rigid oligoproline spacers di(<em>D</em>NP)-Ahx-Asp-(Pro)n-Lys with n = <em>2</em>4, <em>2</em>7, and 33 (i.e., gamma = 100, 110, and 130 A) causes aggregation of the antibodies predominantly into closed <em>dimers</em> and trimers. The corresponding equilibrium constants of the respective ring-closure processes decrease significantly with longer spacer length. (3) Evidence was found that intramolecularly monomeric ring closure of the IgE antibodies is caused by haptens containing oligoproline spacers with n = 37 or 4<em>2</em> (gamma = 130-150 A). The equilibrium constant of the ring-closure process increases with spacer length. This increase in stability indicates a difference in the imposed strain. Furthermore, the latter results imply that the distance between the two binding sites of the IgE molecule lies in the range dictated by the rigid oligoproline part of the respective hapten's spacer, i.e., 115-130 A. (4) Nearly all oligomeric ring-closure processes proceed relatively slowly with an approximate lower limit of a half-life of 5-10 s. This slowing down of the aggregation and ring-closure processes most probably reflects steric factors.

Background: Coronavirus disease 2019 (COVID-19) is characterised by dyspnoea and abnormal coagulation parameters, including raised D-dimer. Data suggests a high incidence of pulmonary embolism (PE) in ventilated patients with COVID-19.

Objectives: To determine the incidence of PE in hospitalised patients with COVID-19 and the diagnostic yield of Computer Tomography Pulmonary Angiography (CTPA) for PE. We also examined the utility of D-dimer and conventional pre-test probability for diagnosis of PE in COVID-19.

Patients/methods: Retrospective review of single-centre data of all CTPA studies in patients with suspected or confirmed COVID-19 identified from Electronic Patient Records (EPR).

Results: There were 1477 patients admitted with COVID-19 and 214 CTPA scans performed, of which n = 180 (84%) were requested outside of critical care. The diagnostic yield for PE was 37%. The overall proportion of PE in patients with COVID-19 was 5.4%. The proportions with Wells score of ≥4 ('PE likely') was 33/134 (25%) without PE vs 20/80 (25%) with PE (P = 0.951). The median National Early Warning-2 (NEWS2) score (illness severity) was 5 (interquartile range [IQR] 3-9) in PE group vs 4 (IQR 2-7) in those without PE (P = 0.133). D-dimer was higher in PE (median 8000 ng/mL; IQR 4665-8000 ng/mL) than non-PE (2060 ng/mL, IQR 1210-4410 ng/mL, P < 0.001). In the 'low probability' group, D-dimer was higher (P < 0.001) in those with PE but had a limited role in excluding PE.

Conclusions: Even outside of the critical care environment, PE in hospitalised patients with COVID-19 is common. Of note, approaching half of PE events were diagnosed on hospital admission. More data are needed to identify an optimal diagnostic pathway in patients with COVID-19. Randomised controlled trials of intensified thromboprophylaxis are urgently needed.

Keywords: COVID-19; Coronavirus; D-dimer; Pulmonary embolism.

<strong class="sub-title"> Background: </strong> Severe acute respiratory syndrome coronavirus <em>2</em> (SARS-CoV-<em>2</em>) could cause virulent infection leading to Corona Virus Disease <em>2</em>019 (COVID-19)-related pneumonia as well as multiple organ injuries.

Hypothesis: COVID-19 infection may result in cardiovascular manifestations leading to worse clinical outcome.

Methods: Fifty four severe and critical patients with confirmed COVID-19 were enrolled. Risk factors predicting the severity of COVID-19 were analyzed.

<strong class="sub-title"> Results: </strong> Of the 54 patients (56.1 ± 13.5 years old, 66.7% male) with COVID-19, 39 were diagnosed as severe and 15 as critical cases. The occurrence of diabetes, the level of D-dimer, inflammatory and cardiac markers in critical cases were significantly higher. Troponin I (TnI) elevation occurred in 4<em>2</em>.6% of all the severe and critical patients. Three patients experienced hypotension at admission and were all diagnosed as critical cases consequently. Hypotension was found in one severe case and seven critical cases during hospitalization. Sinus tachycardia is the most common type of arrythmia and was observed in <em>2</em>3 severe patients and all the critical patients. Atrioventricular block and ventricular tachycardia were observed in critical patients at end stage while bradycardia and atrial fibrillation were less common. Mild pericardial effusion was observed in one severe case and five critical cases. Three critical cases suffered new onset of heart failure. Hypotension during treatment, severe myocardial injury and pericardial effusion were independent risk factors predicting the critical status of COVID-19 infection.

Conclusion: This study has systemically observed the impact of COVID-19 on cardiovascular system, including myocardial injury, blood pressure, arrythmia and cardiac function in severe and critical cases. Monitoring of vital signs and cardiac function of COVID-19 patients and applying potential interventions especially for those with hypotension during treatment, severe myocardial injury or pericardial effusion, is of vital importance.

Keywords: COVID-19; cardiac injury; cardiovascular manifestations; critical status; hypotension.