Flow cytometry for comprehensive assessment of platelet functional activity in response to ADP stimulation

OBJECTIVES

Flow cytometry with adenosine diphosphate (ADP) allows to characterize molecular changes of platelet function caused by this physiologically important activation, but the methodology has not been thoroughly investigated, standardized and characterized yet. We analyzed the influence of several major variables and chose optimal conditions for platelet function assessment.

METHODS

For activation, 2.5 μM CaCl2 , 5 μM ADP and antibodies were added to diluted blood and incubated for 15 min. We analyzed kinetics of antibody binding and effects of their addition sequence, agonist concentration, blood dilution, exogenous calcium addition and platelet fixation.

RESULTS

We tested our protocol on 11 healthy children, 22 healthy adult volunteers, 9 patients after a month on dual antiplatelet therapy after percutaneous coronary intervention (PCI), 7 adult patients and 14 children with immune thrombocytopenia (ITP). We found that our protocol is highly sensitive to ADP stimulation with low percentage of aggregates formation. The assay is also sensitive to platelet function inhibition in post-PCI patients. Finally, platelet preactivation with ITP plasma was stronger and caused increase in activation response to ADP stimulation compared to preactivation with low dose of ADP.

CONCLUSIONS

Our assay is sensitive to antiplatelet therapy and platelet preactivation in ITP patients under physiological conditions with minimal percentage of aggregates formation.

[Clinical and diagnostic value of including PCR blood test in the traditional algorithm for identifying causative agents of infective endocarditis: a cohort study of 124 patients]

BACKGROUND

If infective endocarditis (IE) is suspected, the determination of the etiology is of fundamental importance for the verification of the disease and the appointment of effective therapy. Microbiological diagnostic features are important, but they often need to be supplemented by culture-independent studies of pathological agents.

AIM

To investigate of the diagnostic advantage and value of quantitative analysis of molecular biological methods (polymerase chain reaction - PCR, sequencing) in addition to microbiological examination of whole venous blood in IE.

MATERIALS AND METHODS

We examined 124 patients with suspected or significant IE (DUKE 2015) hospitalized in the Vinogradov City Clinical Hospital (2015-2021). All patients underwent parallel microbiological (cultural) and molecular biological (PCR or PCR followed by sequencing) examination of venous whole blood samples.

RESULTS

The introduction of an early parallel PCR study into the algorithm for the etiological diagnosis of IE made it possible to obtain an additional advantage in 43/124 (34.7%) patients, which made it possible to exclude unreliable results in the determination of CoNS skin commensals and pathogens atypical for IE or contamination and identify the true pathogens, and also for the first time to isolate the etiopathogenetic pathogen with a negative microbiological study. It was shown that in IE associated with CoNS, the association with the disease was confirmed by PCR in 21.4% (3/14) and refuted in 71.4% (10/14). The coincidence of the results of microbiological and PCR studies of blood samples was obtained only in 35/95 (36.8%). Positive results of PCR analysis of blood of biological material with negative results of culture were obtained in 22/51 (43.1%), of which 2/22 (9.0%) were able to confirm the presence of Bartonella spp DNA. The presented complex algorithm made it possible to significantly increase the possibility of intravital identification of the pathogen in the blood from 58.9 to 76.6%. IE with unknown etiology was present in 29/124 (23.4%) patients. A parallel PCR study allowed timely correction of antibiotic therapy in 43/124 (34.7%) patients.

CONCLUSION

Expansion of indications for the use of PCR studies, primarily whole venous blood samples, is justified, not only in IE with negative results of microbiological examination, but also as a control method for the reliability of the results of traditional (cultural) diagnostic methods.

Systems Biology Approach for Personalized Hemostasis Correction

The correction of blood coagulation impairments of a bleeding or thrombotic nature employs standard protocols where the type of drug, its dose and the administration regime are stated. However, for a group of patients, such an approach may be ineffective, and personalized therapy adjustment is needed. Laboratory hemostasis tests are used to control the efficacy of therapy, which is expensive and time-consuming. Computer simulations may become an inexpensive and fast alternative to real blood tests. In this work, we propose a procedure to numerically define the individual hemostasis profile of a patient and estimate the anticoagulant efficacy of low-molecular-weight heparin (LMWH) based on the computer simulation of global hemostasis assays. We enrolled a group of 12 patients receiving LMWH therapy and performed routine coagulation assays (activated partial thromboplastin time and prothrombin time) and global hemostasis assays (thrombodynamics and thrombodynamics-4d) and measured anti-Xa activity, fibrinogen, prothrombin and antithrombin levels, creatinine clearance, lipid profiles and clinical blood counts. Blood samples were acquired 3, 6 and 12 h after LMWH administration. We developed a personalized pharmacokinetic model of LMWH and coupled it with the mechanism-driven blood coagulation model, which described the spatial dynamics of fibrin and thrombin propagation. We found that LMWH clearance was significantly lower in the group with high total cholesterol levels. We generated an individual patient's hemostasis profile based on the results of routine coagulation assays. We propose a method to simulate the results of global hemostasis assays in the case of an individual response to LMWH therapy, which can potentially help with hemostasis corrections based on the output of global tests.

Hypercoagulation detected by routine and global laboratory hemostasis assays in patients with infective endocarditis

Background

Coagulation system is heavily involved into the process of infective endocarditis (IE) vegetation formation and can facilitate further embolization. In this study we aimed to assess the coagulation and platelet state in IE implementing a wide range of standard and global laboratory assays. We also aim to determine whether prothrombotic genetic polymorphisms play any role in embolization and mortality in IE patients.

Methods

37 patients with IE were enrolled into the study. Coagulation was assessed using standard coagulation assays (activated partial thromboplastin time (APTT), prothrombin, fibrinogen, D-dimer concentrations) and integral assays (thromboelastography (TEG) and thrombodynamics (TD)). Platelet functional activity was estimated by flow cytometry. Single nuclear polymorphisms of coagulation system genes were studied.

Results

Fibrinogen concentration and fibrinogen-dependent parameters of TEG and TD were increased in patients indicating systemic inflammation. In majority of patients clot growth rate in thrombodynamics was significantly shifted towards hypercoagulation in consistency with D-dimers elevation. However, in some patients prothrombin, thromboelastography and thrombodynamics were shifted towards hypocoagulation. Resting platelets were characterized by glycoprotein IIb-IIIa activation and degranulation. In patients with fatal IE, we observed a significant decrease in fibrinogen and thrombodynamics. In patients with embolism, we observed a significant decrease in the TEG R parameter. No association of embolism or mortality with genetic polymorphisms was found in our cohort.

Conclusions

Our findings suggest that coagulation in patients with infective endocarditis is characterized by general hypercoagulability and platelet pre-activation. Some patients, however, have hypocoagulant coagulation profile, which presumably can indicate progressing of hypercoagulation into consumption coagulopathy.

[Focus ultrasound for cardiology practice. Russian consensus document]

This document is a consensus document of Russian Specialists in Heart Failure, Russian Society of Cardiology, Russian Association of Specialists in Ultrasound Diagnostics in Medicine and Russian Society for the Prevention of Noncommunicable Diseases. In the document a definition of focus ultrasound is stated and discussed when it can be used in cardiology practice in Russian Federation.

Predictors of mortality in patients with intermediate risk pulmonary embolism

Introduction

Information about treatment and outcome of patients with pulmonary embolism (PE) intermediate risk remains limited. Little is known about the benefits of reperfusion therapy in patients with intermediate risk PE and evidence of right ventricular dysfunction.

Objective

To evaluate clinical outcomes and predictors of mortality in patients admitted to ICU with pulmonary embolism and intermediate risk.

Methods

In a prospective single-center study 103 normotensive patients with an established diagnosis of pulmonary embolism confirmed by pulmonary CT were included. All patients met intermediate risk criteria according to the European Society of Cardiology guidelines (ESC 2019) for pulmonary embolism using severity index [PESI] with signs of right ventricular dysfunction and elevated cardiac biomarkers.

The average age of patients was 67.6 years (95% CI, 65.1–70.5), 42 (41%) of them were men. Thrombolysis with standard dose of alteplase was performed in 54 (52%) patients. CT scan and echocardiography were done for all patients.

Results

Outcome data were collected for all patients through the 30-day and 180-day follow-up. During 30 days follow up 14 patients died (13,6%, 95% CI, 6,9–20%). The all-cause mortality rate after 180 days was 22,2% (95% CI, 13,5–31%) - 22 patient. In the thrombolysis group only 2 patients died after 180-day follow-up, mortality rate was 4,4% (95% CI, 1,7–10,6%), the mortality rate in patients not treated by thrombolysis was 40% (95% CI, 25,3–54,7%). Thrombolysis was associated with a significant decrease in mortality [OR 0.07 (95% CI, 0.01–0.31)]. In the thrombolysis group 2 patients (4.1%; 95% CI, 1.1–10%) had a non-fatal major bleeding event. The presence of chronic heart failure [OR 6 (95% CI, 1.8–20.2)] and previous stroke [OR 4.3 (95% CI, 0.9–21.1)] were higher among non-survivors when compared to survivors (p≤0.05). TAPSE less than 16 mm was found to be negatively associated with survival [OR 5.5 (95% CI, 0.9–40.3)], p=0.02.

Conclusion

In our study thrombolysis in patients with pulmonary embolism and intermediate-risk was associated with improved prognosis. Predictors of mortality were the presence of CHF, previous stroke and TAPSE of less than 16 mm.

Funding Acknowledgement

Type of funding sources: None. Kaplan-Meier mortality curves. p<0.05

Value of polymerase chain reaction in etiological diagnostic of infectiove endocarditis

Introduction

Identification of a causative agent in patients with infective endocarditis (IE) is crucial for diagnostic and prescribing etiotropic therapy which defines positive outcome of a disease. High rate of a culture negative IE and inaccurate results of traditional microbiological methods raise a concern. So the methods of etiological diagnostics in IE are in need of development, particularly introduction of polymerase chain reaction (PCR) method might be helpful.

Aim

Modernisation of the algorithm of IE etiological diagnostic by introducing PCR

Materials and methods

The study included 85 cases of IE [first episode of IE (n=79), recurrence/relapse (n=6)] verified by DUKE criteria 2009, 2015, hospitalized in Moscow primary hospital from 2012 to 2017. All patient had venous blood investigated both with microbiological method and with broadrange and specific PCR. Following microorganisms' DNA were assessed by PCR: Staphylococcus spp. (MRCoNS, S. aureus and others), Streptococcus spp. (S. agalactiae, S. pyogenes and others), Enterococcus spp. (E. faecium, E. faecalis and others), Enterobacteriaceae, Klebsiella spp. (K. pneumoniae and others), E. coli, Proteus spp., A. baumanii, P. aeruginosa, Fungi (C. albicans, C. glabrata, Aspergillus spp. and others).

Results

Median age was 55.48 years (95% confidence interval (CI) 51.16–59.8), males 67.9%. History of cardiovascular diseases was in 54 (68.35%), diabetes mellitus in 18 (22.78%), hepatitis B and/or C in 31 (39.2%), intravenous drug dependency in 27 (34.18%), chronic kidney disease in 38 (48.1%), median Charlson comorbidity index was 5.44 (95% CI 4.52–6.37). Left-side IE was in 50 (63.29%), right-side IE – in 23 (29.12%), left-right-side IE in 6 (7.59%). Secondary IE was in 53 patients (62.3%). Embolic events were diagnosed in 27 cases (34.18%), in-hospital mortality – in 22 (27.8%).

Microbiological method identified etiological agent in 55 of 85 cases (61.2%), featuring Staphylococcus aureus (n=23), Staphylococcus CoNS (n=6), Escherichia coli (n=1), Acinetobacter spp. (n=2), Streptococcus spp. (n=2), Enterococcus spp. (n=8), Klebsiella pneumoniae (n=2), Gemella haemolysans (n=2), several causative agents (n=6). Additional PCR testing identified etiology in 14 of 33 (42.2%) featuring Staphylococcus spp. (n=6), Enterococcus spp. (n=3), Streptococcus spp. (n=1), Aspergillus sp. (n=1) Pasteurella multocida (n=1), Enterococcus spp. + Staphylococcus spp. (n=1), Staphylococcus spp.+ A. baumanii + E. coli (n=1).

PCR method identified 6 fals-positive results of microbilogical investigation [S. epidermidis (n=2), G. haemolysans, Acinetobacter spp., E. faecalis, K. pneumoniae], that are most probably due to preanalytical sample contamination

Conclusions

Introduction of PCR into the algorithm of IE etiological diagnostic increased validity of laboratory findings on 23.5%. True culture negative IE was present in 19 of 85 patients. Rate of mortality and complications in IE remains high.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Peoples' Friendship University of Russia (RUDN), Moscow, Russia

[Infective Endocarditis with Unknown Etiology: Possibilities of Conquering and Role of Microbiologistics]

Current infectious endocarditis (IE) is characterized by changes in its etiological and epidemiological profiles associated with increased incidence of IE of undetermined etiology. This requires a search for ways to enhance the effectivity of diagnosis. Microbiologistics along with high-tech methods becomes decisively important for identifying the pathogen by studying cultures of blood and tissues from the affected heart valve. This determines timely diagnosis and treatment to be introduced to medical practice as a component of personalized medicine. The article focuses on the validity and features of microbiological (cultural), immunochemical, and molecular biological [MALDI-TOF MS (matrix-activated laser desorption/ionization with time-of-flight mass spectrometry), polymerase chain reaction, sequencing] studies.

Infective Endocarditis in Moscow General Hospital: Clinical Characteristics and Outcomes (Single-Center 7 Years’ Experience)

AIM

to investigate clinical properties of course and outcomes of infective endocarditis (IE) depending on source of infection, to find predictors of mortality in a Moscow general hospital.

MATERIALS AND METHODS

We included in this study 176 patients with definite and possible infective endocarditis (the Duke criteria), admitted in our hospital in 2010-2017. Patients were divided in three groups according to source of infection. All patients underwent standard clinical and laboratory assessment, echocardiography, blood culture test combined with blood PCR with sequencing. Inhospital and 1-year outcome were evaluated.

RESULTS

Among 176 patients with IE 65.3 % were men (median age 57 [35-72] years), most patients (n=149, 84.7 %) had native valve IE. Etiological factor was identified in 127 (72.2 %) cases. Gram-positive infective agents prevailed (54 %). Surgery in active phase of the disease was performed in 30 (17 %) patients. Among patients with healthcare-associated IE (n=76, 43.9 %) prevailed those older than 60 years, with high Charlson comorbidity index, with culture-negative IE, and complicated clinical course (mainly progressing heart failure). Patients with intravenous drug use associated IE (n=50, 28.4 %) had low Charlson index, association with hepatitis C viral infection, involvement of tricuspid valve with big vegetations, high frequency of embolic complications, and low inhospital mortality. Group of patients with community acquired IE (n=50, 28.4 %) more often had uncommon causative microorganisms, and had better long-term outcome. In-hospital mortality was 30.1 % (n=53) mostly due to sepsis with multi-organ failure, and heart failure. Risk factors of inhospital death were history of cardiovascular diseases, old age, kidney damage, methicillin-resistant Staphylococcus aureus (MRSA) infection, uncontrolled infection, and embolic events. Risk factors of 1-year mortality were history of stroke, and heart failure as IE complication. Independent predictors of in-hospital death were MRSA infection (odds ratio [OR] 50.32, 95 % confidence interval [CI] 1.66-213.92; p=0.002), persistent infection (OR 18.6, 95 %CI 5.37-64.40; p=0.001), duration of fever >7 days after initiation of antibacterial therapy (OR 13.41, 95 %CI 3.51-51.24; p=0.001); and of death during first year - history of cerebral infarction (OR 4.39, 95 %CI 1.32-14.70; p=0.016)), and heart failure as IE complication (OR 8.1, 95 %CI 1.97-67.09; p=0.016). Among patients subjected to surgery there were no fatal outcomes during 1 year after hospital discharge, while among conservatively treated patients were 21 (14.4 %) deaths (p<0.009).

CONCLUSION

Main clinical features of IE course in patients urgently admitted to a general hospital was dominance of healthcare-associated  IE among patients, who were older than 60 years with severe comorbidities. These patients had more complications and worse outcome. Modeling of prognosis identified uncontrolled infection as key factor of unfavorable outcome. Surgery significantly reduced long-term mortality.

[Infective endocarditis: Importance of molecular biological techniques in etiological diagnosis]

AIM

To investigate the specific features of conventional bacteriological methods and current molecular biological techniques for the etiological diagnosis of infective endocarditis (IE).

SUBJECTS AND METHODS

Examinations were made in 53 patients treated at City Clinical Hospital Sixty-Four, Moscow Healthcare Department, in 2012-2015 who underwent simultaneous bacteriological and molecular biological (polymerase chain reaction (PCR) or PCR with further sequencing) examinations of blood or resected cardiac valve tissues.

RESULTS

The investigation included 53 patients (31 men; median age, 62 years) with IE (Duke 2009); its primary form was observed in 32 (60.4%) patients. Blood bacteriological tests and PCR assays were positive in 28 (52.8%) and 34 (64.2%) patients, respectively. There were concordant results in 21 of the 28 positive blood culture cases and discordant results in 7 (25%); at the same time 3 cases showed a compete discordance in the detected causative agents (the growth of Enterococcus spp. was revealed by bacteriological examination and that of Staphylococcus spp., Streptococcus spp., and Escherichia coli by DNA PCR) and a pathogen could not be identified by DNA PCR in 4 patients who had positive blood bacteriological results. The positive PCR results for cocci and fungi were obtained in 10 of the 25 (47.2%) examinees with culture-negative IE. Rare causative agents were not revealed. The tissues obtained from 8 resected damaged heart valves displayed a wider spectrum of pathogens than did blood samples, which was associated with the formation of bacterial films.

CONCLUSION

The etiological agent of IE was revealed in venous blood by bacteriological examination in 52.8% of the examinees, by PCR in 64.2%, and by either in 71.7%. There were concordant and discordant results in 67.9 and 32.1% of the patients, respectively; among whom 18.9% were found to have pathogen DNA revealed by PCR in culture-negative IE.