State-of-the-Art Review: Molecular Markers in Thrombosis and Hemostasis

Molecular markers for exploring the different stages of hemostasis activation are now available. These markers allow investigation of endothelial functions, blood cell activation, stimulation of coagulation pathways, involvement of the fibrinolytic system, and profiling of the coagulolytic-equilibrium that regulates hemostasis. Additionally, these markers find useful applications for monitoring therapies, following-up clinical states associated with high thrombotic risk, and validating new drugs and analyzing their mode of action. Furthermore, these markers may allow for recognition of the evolution of early disease in the clinically silent phase. Large scale epidemiological and longitudinal studies are required for establishing this latter approach. Up to now, only D. Dimer is used in routine clinical application for exclusion diagnosis of deep-veinous-thrombosis and pulmonary embolism. Other markers must prove their sensitivity for the early asymptomatic period and demonstrate their applicability throughout disease evolution. According to pathology and application, different markers may provide complementary information. Some markers, e.g., D. Dimer, soluble thrombomodulin, and modified AT-III (ATM), are used on standard citrated plasma samples. Modem and flexible technologies are now available for point-of-care testing (when required), quick and sensitive measurements in emergency conditions, and full automation when necessary. Lastly, factors that trigger hemostatic activation can now be evaluated and provide information on etiology. In this latter respect, autoimmunity may be important in thrombotic disease induction. Key Words: Hemostatic activation—Molecular markers— Thrombosis—Predictivity—Monitoring antithrombotic therapies.

Coagulation and Fibrinolysis in Amyloid and Non-amyloid Hemodialysis Patients: Assessment of Local Hemostatic Kinetics Within Arteriovenous Fistulas

This study was designed to determine whether systemic amyloidosis is an additional risk factor for he mostatic abnormalities in hemodialysis patients and to evaluate local alterations of the hemostatic process within the patent-functional native arteriovenous fistula (AVF). Concentrations of in vivo molecular hemostatic markers, including prothrombin fragment1 +2 (PF 1.2), thrombin antithrombin III complex (TAT) and plasmin-α 2 antiplasmin complex (PAP) were determined in plasma samples taken simultaneously from AVFs and contralat eral upper extremity large veins of hemodialysis patients associated with and without systemic amyloidosis. Seven amyloid (2 women, 5 men, aged 34 ± 6 years), and 13 non-amyloid patients (4 women, 9 men, aged 36 ± 7 years) on maintenance hemodialysis and 20 healthy vol unteers (8 women, 12 men, aged 36 ± 9 years) were in cluded in the study. Peripheral vein PF 1.2 and TAT lev els showed no difference between amyloid and non- amyloid patient groups, but both were significantly higher than control group. PF 1.2 and TAT levels were also found to be elevated in fistulas when compared with that of peripheral vein in both amyloid and non-amyloid pa tient groups. Determination of PAP in peripheral veins of each group revealed significantly higher levels in amyloid hemodialysis patients than in non-amyloid patients and controls. PAP levels were significantly higher in fistulas of amyloid patients than in non-amyloid patients. In con clusion, this study confirms enhanced coagulation and fibrinolysis in hemodialysis patients and excessive fibri nolysis in amyloid patients with remarkable contribu tion of AVF on enhanced coagulation and fibrinolysis.

Platelet aggregation and activation in thalassemia major patients in Indonesia

Thromboembolic events and hypercoagulable state have been reported in patients with thalassemia. As platelets play an important role in the pathogenesis of thrombosis, the authors aimed to find the pattern of changes in platelet count, function and activation, and evidence of coagulation activation in patients with thalassemia major in Indonesia. A total of 31 patients with splenectomized and 35 patients with nonsplenectomized thalassemia major were enrolled in this study. Platelet count, platelet aggregation, beta-thromboglobulin, and D-dimer levels were measured. All measured parameters were significantly higher in splenectomized than in nonsplenectomized patients. beta-thromboglobulin level was increased, but D-dimer level was within normal range. The authors concluded that there was an increase in platelet activation in patients with beta-thalassemia major. Platelet activation was higher in splenectomized than in nonsplenectomized patients.

Hemostatic markers and platelet aggregation factors as predictive markers for type of stroke and neurological disability following cerebral infarction

We investigated the plasma levels of D-dimer, fibrinogen, beta-thromboglobulin (BTG) and platelet factor-4 (PF-4), indices of the occurrence of platelet activation in vivo, to find out their role in pathophysiology of ischemic stroke and whether or not such a role has any effect on the disability and the prognosis of stroke patients. A total of 76 patients with AIS aged from 26 to 85 (32 men, 44 women) and 30 cases as controls with similar age (18 men, 12 women) were included in the study. The plasma levels of D-dimer, BTG and PF-4 were measured by ELISA method using a special commercial kit. The cases were allocated into two groups as non-embolic (NEI) and cardioembolic stroke (CEI). The D-dimer levels in 76% of 42 patients in NEI group (p<0.05) and 85.2% of 34 patients in CEI group (p<0.05) were outside the confidence interval (CI) defined for the control group. The levels of BTG were elevated in 81% of 42 cases with NEI (p<0.05) and in 76% of 34 cases with CEI, with reference to CI of control group. The levels of PF-4 were significantly increased in 86% of cases with NEI (p<0.05) and in 88% of cases with CEI than controls (p<0.05). It was observed that the cases with high Rankin scores had higher levels of D-dimer (p<0.005), BTG (p<0.01) and PF-4 (p<0.01) than those with lower scores. There was a correlation between hemostatic markers, platelet activation and functional disability. D-dimer levels were an important marker that determined to degree of the activation of hemostatic system, especially in CEI subtype. The platelet aggregation had an important role in pathophysiology of ischemic stroke and this condition is significant in NEI subgroup and subjects with large infarcts and high disability scores.

Comparison of incidence/risk of venous thromboembolism (VTE) among selected clinical and hereditary risk markers: a community-based cohort study

Background

Little information is available from community-based long-term VTE cohort studies to compare the absolute thrombosis risk of established clinical and genetic risk factors.

Materials and methods

The occurrence of venous thromboembolism (VTE) was observed during a 10-year observation period in the BAvarian ThromboEmbolic Risk (BATER) study, a cohort study of 4337 women (age 18–55 years). We collected data on demographics, reproductive life, lifestyle, conditions/diseases, and particularly potential risk factors for VTE with a self-administered questionnaire. The objective was to present incidence rates of VTE and to show relative risk estimated associated with different clinical and genetic risk factors.

Results

34 new, by diagnostic means confirmed VTE events occurred during the observation time of 32,656 women-years (WY). The overall incidence of VTE was 10.4 per 10⁴ WY. The incidence rates varied markedly among different risk cohorts. The highest incidence was observed in women with previous history of VTE, followed by family history of VTE. None of the measured "genetically-related risk markers" (antithrombin, protein C, FVL, prothrombin mutation, or MTHFR) showed a significant VTE risk.

Conclusion

Most of the discussed VTE risk factors showed no significant association with the occurrence of new VTEs due to smallness of numbers. Only first-degree family history of VTE and own history of a previous VTE event depicted a significant association with future VTE. Clinical information seems to be more important to determine future VTE risk than genetically related laboratory tests.

Effects of extracorporeal circulation on thrombinantithrombin III and prothrombin fragment 1+2 levels

Cardiopulmonary bypass may alter the factors responsible for normal hemostasis by exposing blood to nonendothelial surfaces, for example, extracorporeal circuits. To evaluate the probable effect of extracorporeal circulation on hemostasis, we measured thrombin-antithrombin III complex (TAT) and prothrombin fragment 1+2 (PF 1.2) plasma levels, which are the biologic markers of in vivo coagulation, in 20 patients who underwent coronary artery bypass grafting (CABG). Postoperative PF 1.2 levels were higher in comparison to the preoperative concentrations of the parameter. Preoperative and postoperative TAT concentrations showed no statistically significant difference. The increment in the PF 1.2 levels in CABG patients might suggest ongoing subclinical hemostatic activation associated with CABG. Further investigations are needed to clarify the exact relationship between increased PF 1.2 levels and thrombotic complications observed in CABG patients. Hemostatis in CABG is still an enigma and remains to be eluciated.

Changes of the hemostatic network in critically ill patients--is there a difference between sepsis, trauma, and neurosurgery patients?

OBJECTIVE

To study the time course of coagulation data in intensive care patients.

DESIGN

Prospective, descriptive study.

SETTING

Clinical investigation on a surgical and neurosurgical intensive care unit of a university hospital.

PATIENTS

Fifteen patients with severe trauma (injury severity score, 15 to 25), 15 sepsis patients secondary to major surgery, and 15 neurosurgery patients (cancer surgery) were studied.

INTERVENTIONS

Standardized intensive care therapy.

MEASUREMENTS AND MAIN RESULTS

Standard coagulation data and molecular markers of coagulation activation and fibrinolytic activity (soluble thrombomodulin, protein C, free protein S, thrombin/antithrombin III complex, plasmin-alpha 2-antiplasmin complex, tissue plasminogen activator, platelet factor 4, beta-thromboglobulin were measured from arterial blood samples on the day of admission to the intensive care unit (trauma/neurosurgery patients) or on the day of diagnosis of sepsis (baseline value) and serially during the next 5 days. Antithrombin III, fibrinogen, and platelet counts were highest in neurosurgery patients but without significant differences between sepsis and trauma patients. Thrombin/antithrombin III complex increased in the sepsis patients (from 22.6+/-4.2 microg/L to 39.9+/-6.8 microg/L), but decreased in trauma (from 40.2+/-5.1 microg/L to 17.6+/-4.0 microg/L) and neurosurgery patients (from 28.2+/-4.2 microg/L to 16.2+/-3.8 microg/L). Tissue plasminogen activator increased in the sepsis patients (from 14.4+/-3.9 microg/L to 20.7+/-3.8 microg/mL) and remained almost unchanged in the other two groups. Soluble thrombomodulin plasma concentration increased significantly in the sepsis group (max, 131.8+/-22.5 ng/mL), while it remained elevated in the trauma (max, 75.5+/-5.9 ng/mL) and was almost normal in the neurosurgery patients. Protein C and free protein S remained decreased only in the sepsis group.

CONCLUSIONS

Alterations of the hemostatic network were seen in all three groups of critically ill patients. Hemostasis normalized in the neurosurgery patients and posttraumatic hypercoagulability recovered within the study period. By contrast, monitoring of molecular markers of the coagulation process demonstrated abnormal hemostasis in the sepsis patients during the entire study period indicating ongoing coagulation disorders and abnormalities in fibrinolysis in these patients.

Clinical significance of hemostatic markers and thrombomodulin in systemic lupus erythematosus: evidence for a prothrombotic state

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder with overwhelming thrombotic states. The precise pathogenetic mechanisms underlying the prethrombotic state in SLE is not fully understood, but interactions between the antiphospholipid antibodies and antigen targets on the coagulation components have been incriminated to play fundamental roles. To evaluate this issue, 34 women with antiphospholipid antibody negative SLE were investigated for molecular markers of blood coagulation and fibrinolytic activity: prothrombin fragment1+2 (PF1+2), thrombin-antithrombin complex (TAT), plasmin-alpha2-antiplasmin inhibitor complex (PAP), and tissue factor pathway inhibitor (TFPI). We also analysed plasma soluble thrombomodulin (sTM) levels. SLE disease activity was determined using the SLE Disease Activity Index (SLEDAI). Concentrations of TAT, PAP, PF1+2 and sTM were significantly elevated (P<0.0001, P=0.0002, P<0.0001, and P<0.0001, respectively), while TFPI antigen levels were found to be reduced (P<0.0001) in patients with SLE compared to the control group. In patients with active SLE, anti-ds DNA levels were correlated positively with plasma TAT (P<0.05), PF1+2 (P<0.05), and sTM (P<0.01) concentrations and negatively with plasma TFPI levels (P<0.05). SLEDAI scores were correlated positively with plasma TAT (P<0.01), PF1+2 (<0.01), and sTM (P<0.01) levels. This study illustrates that both a prethrombotic state and a compensatory fibrinolytic process secondary to subclinical intravascular coagulation might coexist in SLE with elevated sTM levels, indicating impaired endothelial functions.

Course of molecular hemostatic markers during and after different surgical procedures

STUDY OBJECTIVE

To establish the most vulnerable time of thrombi formation with regard to the plasmatic (noncellular) part of the coagulatory and fibrinolytic systems.

DESIGN

Nonrandomized observational study.

SETTING

A surgical and an orthopedic unit and the central laboratory of a university hospital.

PATIENTS

61 consenting ASA physical status I and II inpatients undergoing four different types of surgery: total hip replacement (THR): 16 patients; hemicolectomy: 15 patients; endoscopic cholecystectomy: 15 patients; subtotal thyroid resection: 15 patients.

INTERVENTIONS

The time course of 11 procoagulatory and fibrinolytic parameters was examined during the different types of surgery. Blood samples were drawn on the day before surgery, directly before the induction of general anesthesia, 1 to 2 hours postoperatively, and on the mornings of postoperative days 1, 2, 3, 4, and 5.

MEASUREMENTS AND MAIN RESULTS

The coagulation samples were centrifuged within 1 hour of collection at 2,300 g for 15 minutes at 4 degrees C. Hemoglobin, hematocrit, platelets, fibrinogen, prothrombin time, activated partial thromboplastin time, thrombin time, antithrombin III, and protein C were determined immediately on laboratory arrival of the samples. The samples were aliquoted at -70 degrees C. They were thawed within 2 weeks and prepared for the following assays: thrombin-antithrombin III complexes (TAT-complexes), D-dimers, and plasminogen activator inhibitor type 1. Maximum activation of coagulation is not reached until 2 hours postoperatively and slowly decreases until normal values are reached around the fifth postoperative day. Parameters displaying the greatest changes are TAT-complexes and D-dimers. The type of surgery with the most pronounced changes was total hip replacement, followed by hemicolectomy, cholecystectomy, and subtotal thyroid resection.

CONCLUSION

The total hip replacement and hemicolectomy groups show similar and strong activation of the procoagulatory and fibrinolytic systems. Much less pronounced are the changes during endoscopic cholecystectomy and subtotal thyroid resection. Maximum activation occurs 1 to 2 hours postoperatively.

Evaluation of two new integrated adapters for blood drawing in closed blood bag systems: influence on different molecular coagulation markers

We compared a conventional blood donation bag system (A) with two newly developed ones (B, C) with integrated Y-shaped adapters. The new systems facilitate the withdrawal of blood samples in a closed system under aseptic conditions. The purpose of the study was to determine whether disturbances during blood donation in the different tubings influence the quality of the donated plasma due to activation processes of the coagulation system. In all bag samples from 34 probands for each system, we found higher levels of the global tests (aPTT, TT) compared to intraindividual controls. This was due to a greater amount of anticoagulant in the bag samples. An increase of procoagulant activity was demonstrated for bags A and C. Concerning the fibrinolytic system, values were reduced in all three systems compared to controls. In summary, the quality of the plasma in the three different bag devices was comparable to controls concerning factor activities measured as global tests. The activation of the coagulation system was only slightly higher in the new system B and C than in the conventional one (A). Therefore, the new closed systems are suitable for blood donation and reveal a high coagulation quality of the plasma.

The molecular markers of hemostatic activation on coronary artery disease

Endothelial cells, circulating platelets, and proteins of the coagulation and fibrinolytic systems are known to contribute to the hemostatic processes. Various molecular markers of hemostatic alteration are found in increased amounts in the circulation during the activation of this process. In this study, we investigated serum lipoprotein (a) and plasma platelet factor 4, beta-thromboglobulin, thrombin-anthithrombin complex, fibrinopeptid A, D-dimer, tissue plasminogen activator, tissue plasminogen activator inhibitor, and fibronectin levels in patients with coronary artery disease. The levels of all these markers were found to be significantly higher as compared to the control group. Our findings suggest that patients with coronary artery disease have greater blood coagulability than controls, and the use of molecular markers has become greatly important in clinical practice.

Hematology for primary care physicians

Many hematologic disorders present minimal physical signs and symptoms in the early state. For example, chronic myelogenous leukemia may not manifest splenomegaly or any obvious physical signs, yet the laboratory report may demonstrate leukocytosis, eosinophilia, basophilia, and thrombocytosis. Although the anemic condition of a patient with a hemoglobin level of 7 gm/dl may be readily apparent to the clinician, a hemoglobin level of 10.5 gm/dl may be difficult to discern during a brief visit that is focused on another organ system. The same laboratory report, however, may contain valuable clues about unsuspected anemia related to mean corpuscular volume or morphology. Information from supporting chemistry studies often may be helpful in interpretation of the diagnosis. An elevated uric acid level, for example, may indicate hyperkinetic cytogenesis related to myeloproliferative or lymphoproliferative neoplastic disorders. This monograph is designed to be useful to busy physicians who want to use basic hematologic studies in a cost-effective manner. Hematology is viewed in a problem-oriented way; the laboratory report is used as the problem generator.

Platelet factor 3 in plasma fractions: its relation to microparticle size and thromboses

Platelet factor 3 (PF3) was assayed by Russell's viper venom (RVV) in three plasma fractions, platelet-rich plasma (PRP), platelet poor plasma (PPP), and 0.1 microns particle-filtered plasma (PFP), in 42 healthy controls, 34 patients with recent cerebrovascular accidents (CVA) and 28 with recent ischemic events from coronary artery disease (CAD). Platelet microparticles (PMP) were assayed in PPP by flow cytometry. Relative to controls, the RVV clotting times were shortened in all three plasma fractions in both patient groups, p < 0.001. PMP were also elevated in both patient groups, p < 0.001. Linear regression analysis showed that the RVV times of PPP are inversely correlated with PMP, p < 0.005, in patient groups but not in controls. There was no correlation of RVV time with PT, APTT or FIB. After converting RVV times to units of PF3 activity, it could be shown that only about 1/4 of the total PF3 activity was contributed by platelets. The major contribution to the PF3 activity in controls was from microparticles < 0.1 microns but in patients was due mainly to microparticles > 0.1 microns. The RVV time was superior to routine coagulation tests in discriminating thrombotic patients from healthy controls.