Generation of neutrophil extracellular traps in patients with acute liver failure is associated with poor outcome.

BACKGROUND AND AIMS: Acute liver failure (ALF) is characterized by significant changes in the hemostatic system and by systemic inflammation. The formation of neutrophil extracellular traps (NETs), in which an activated neutrophil expels its DNA, histones, and granular enzymes, such as myeloperoxidase (MPO), has been associated with immune-mediated and thrombotic diseases. We hypothesized that formation of NETs in patients with ALF contributes to progression of disease. APPROACH AND RESULTS: A total of 676 patients with ALF (international normalized ratio [INR], ≥1.5) or severe acute liver injury (ALI; INR, ≥2.0) were recruited from the U.S. ALF Study Group Registry between 2011 and 2018, of whom 308 patients (45.6%) had acetaminophen-induced ALF. Up to 21 days after admission, 483 patients (71.5%) survived without liver transplantation (LT). Levels of cell-free DNA (cfDNA) and the specific NET marker MPO-DNA complexes were measured in plasma samples obtained on admission and compared to levels in healthy controls. In addition, liver tissue obtained at transplantation of 20 ALF patients was stained for NETs. Levels of cfDNA were 7.1-fold, and MPO-DNA complexes 2.5-fold, higher in patients with ALF compared to healthy controls. cfDNA levels were not associated with 21-day transplant-free survival, but were higher in those patients with more-severe disease on admission, as reflected by various laboratory and clinical parameters. MPO-DNA levels were 30% higher in patients with ALF who died or required urgent LT. Liver tissue of ALF patients stained positive for NETs in 12 of 18 evaluable patients. CONCLUSIONS: Here, we provide evidence for NET formation in patients with ALF. Elevated plasma levels of MPO-DNA complexes in patients with ALF were associated with poor outcome, which suggests that NET formation contributes to disease progression.

Device-Induced Hemostatic Disorders in Mechanically Assisted Circulation.

Mechanically assisted circulation (MAC) sustains the blood circulation in the body of a patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) or on ventricular assistance with a ventricular assist device (VAD) or on extracorporeal membrane oxygenation (ECMO) with a pump-oxygenator system. While MAC provides short-term (days to weeks) support and long-term (months to years) for the heart and/or lungs, the blood is inevitably exposed to non-physiological shear stress (NPSS) due to mechanical pumping action and in contact with artificial surfaces. NPSS is well known to cause blood damage and functional alterations of blood cells. In this review, we discussed shear-induced platelet adhesion, platelet aggregation, platelet receptor shedding, and platelet apoptosis, shear-induced acquired von Willebrand syndrome (AVWS), shear-induced hemolysis and microparticle formation during MAC. These alterations are associated with perioperative bleeding and thrombotic events, morbidity and mortality, and quality of life in MCS patients. Understanding the mechanism of shear-induce hemostatic disorders will help us develop low-shear-stress devices and select more effective treatments for better clinical outcomes.

Paediatric reference intervals for common coagulation assays in Chinese children as performed on the STA-R coagulation analyzer.

INTRODUCTION: In order to correctly manage the paediatric patients affected with haemostatic disorders, age-appropriate reference intervals should be used. The purpose of this study was to establish age-specific reference intervals for prothrombin time (PT), thrombin time (TT), activated partial thromboplastin time (aPTT) and fibrinogen (Fg). METHODS: In this study, a total of 34 234 apparently healthy children and adolescents aged 0-15 years were chosen as reference individuals. PT, TT, aPTT and Fg were performed on the STA-R coagulation analyzer. Outliers were eliminated using the Dixon D/R ratio rule. Partitioning by age was achieved using Harris and Boyd's standard normal deviate test. The lower (2.5th percentiles) and upper (97.5 percentiles) reference intervals were established using the nonparametric method. RESULTS: Compared with the adult group, the median time of PT was significantly different in the groups consisting of children aged 0-15 days, 15 days-1 month, 1-6 months and 11-15 years. The median time of APTT and TT was significantly prolonged in all paediatric age groups than in the adult group (P < .05). Compared with the adult group, the median values of Fg were significantly different in the groups consisting of children aged 0-15 days and 2-15 years. Our results showed that all coagulation assays required partitioning by age. CONCLUSION: Our results suggest that results of coagulation assays are highly dependent on age, and that age-specific reference intervals must be used to ensure proper evaluation of paediatric coagulation assays.

Primary Hemostatic Disorders and Late Major Bleeding After Transcatheter Aortic Valve Replacement.

BACKGROUND: Periprocedural and late (>30 days) bleedings represent major complications after transcatheter aortic valve replacement and have been identified as potential areas for improved patient care. OBJECTIVES: The authors sought to evaluate the impact of ongoing primary hemostasis disorders on late major/life-threatening bleeding complications (MLBCs). METHODS: Bleedings were assessed according to the VARC-2 (Valve Academic Research Consortium-2) criteria. Closure time of adenosine diphosphate (CT-ADP), a surrogate marker of high molecular weight von Willebrand multimers proteolysis was assessed 24 h after the procedure. Ongoing primary hemostasis disorder was defined by a CT-ADP >180 s. RESULTS: Among 372 patients who survived at 30 days, MLBCs occurred in 42 patients (11.3%) at a median follow-up of 383 days (interquartile range: 188 to 574 days). MLBCs were mainly of gastrointestinal origin (42.8%) and were associated with increased overall mortality (hazard ratio [HR]: 5.66; 95% confidence interval [CI]: 3.10 to 10.31; p < 0.001) and cardiac mortality (HR: 11.62; 95% CI: 4.59 to 29.37; p < 0.001). A 2.5-fold elevation of MLBCs could be evidenced in patients with a CT-ADP > 180 s (27.4% vs. 11.5%; p < 0.001). Multivariate regression analysis identified paravalvular leak (PVL) (HR: 6.31; 95% CI: 3.43 to 11.60; p < 0.0001) and CT-ADP > 180 s (HR: 3.08; 95% CI: 1.62 to 5.81; p = 0.0005) as predictor of MLBCs. CONCLUSIONS: MLBCs after transcatheter aortic valve replacement are frequent and associated with an increased morbidity and mortality. PVL and CT-ADP >180 s were identified as strong predictors for MLBCs. These findings strongly suggest that persistent HMW defects contribute to enhanced bleeding risk in patients with residual PVL.

Perioperative standards for the treatment of coagulation disorders and usage of blood products in patients undergoing liver transplantation used in the Clinic for Transplant Surgery in Wroclaw.

BACKGROUND: Coagulation system disorders in liver transplantation (ltx) patients are considered a serious issue. Liver cirrhosis leads to decreased synthesis of clotting factors and decreased elimination of waste products, including coagulation proteins. Platelet sequestration and dysfunction in an enlarged spleen additionally worsen these conditions. The resulting state, the most common pathology of the coagulation system, involves the reduction of clotting potential and hyperfibrinolysis. OBJECTIVES: Tackling the problem of impaired hemostasis is a dynamic process. Throughout the whole procedure, consisting of the preanhepatic, the anhepatic and the neohepatic phases, consecutive pathomechanisms disrupt the very balance that anesthesia aims to preserve. MATERIAL AND METHODS: Rotational thromboelastometry (ROTEM), having been introduced in the Clinic of Anesthesiology and Intensive Therapy, Wroclaw Medical University, Poland, enables the efficient and early diagnosis of clotting disorders. An additional major problem which occurs during ltx, namely blood loss, could be solved using a cell separator. RESULTS: In this study, we present the standards introduced to the Transplantology Department of the Vascular Surgery Clinic, Wroclaw Medical University, Poland, that describe blood treatment during ltx procedures. CONCLUSIONS: We conclude that thromboelastometric examination and the use of a cell separator have significantly increased the safety of ltx procedures at our clinic. The introduction of thromboelastometry (TEM) and the implementation of the cell separator recovery method have enabled us to perform the dangerous and complicated surgical procedure of ltx in a much more stable and much safer manner than in the past.

Establishing reference intervals in the coagulation laboratory.

INTRODUCTION: Obtaining a reference interval (RI) is a challenge for any laboratory and becomes more complicated in the coagulation laboratory due to testing on samples with limited stability on reagents that are poorly standardized. Reference intervals are required to be able to evaluate results in relation to a patients' hemostatic disorder. This becomes one of the most important tasks conducted in the coagulation laboratory. However, many laboratories lack the time, finances and in many cases the expertise to conduct this study. METHODS: Many RI are obtained from package inserts, or from publications written by experts in lieu of laboratories conducting their own studies. An overview of validating reference intervals and options for verifying or transference of reference intervals is discussed. RESULTS: Based on the confidence interval and the acceptability of risk laboratories are willing to accept, coagulation laboratories have options to conduct robust studies for their RI. Data mining or global reference studies may help to provide data for age specific ranges. CONCLUSIONS: Pre-analytical variables and selection of healthy subjects have the largest impact on coagulation testing outcomes and need to be well controlled during the establishment of reference intervals. Laboratories have options in lieu of conducting a full validation on how to verify RI based on smaller RI studies or transference of RI after determining compatibility of the original RI study.

Hemostatic Disorders Associated with Hepatobiliary Disease.

The liver plays a crucial role in all aspects of coagulation because most factors that regulate procoagulation, anticoagulation, and fibrinolysis are produced, cleared, and/or activated in the liver. Establishing the coagulation status of an individual patient with hepatobiliary disease can therefore be challenging. Although, classically, patients with hepatobiliary disease were thought of as potentially hypocoagulable, hypercoagulability also occurs. The article summarizes the breadth of coagulation abnormalities that have been reported in dogs and cats with hepatobiliary disease and provides strategies to respond to bleeding and thrombotic risk.

Neonatal Hemostatic Disorders: Issues and Challenges.

Neonates form a unique cohort with distinct features associated with the hemostatic system compared with older children and adults. The development of the human hemostatic system begins around 10 weeks in utero and continues to evolve during childhood. This dynamic period termed developmental hemostasis should be taken into consideration when diagnosing a neonate with disorders of bleeding or thrombosis.

Hemostatic Disorders in Hormonally Active Pituitary Tumors.

Endocrinopathies encompass heterogeneous diseases that can lead to hemostasis disorders at various stages over their clinical course. Normal hemostasis requires an equilibrium between the processes of coagulation and fibrinolysis, which depend on multiple activators and inhibitors. To date, the influence of various hormonal disorders on the hemostatic system has been assessed many times. The aim of this review was to analyze hemostasis abnormalities that occur in patients with hormonally active pituitary tumors: corticotropinoma, somatotropinoma, prolactinoma, gonadotropinoma and thyrotropinoma. Authors discuss studies that examined coagulation and hemostasis parameters among patients with these tumors, as well as analyze antithrombotic prophylaxis approach for endogenous hypercortisolemia subjects in particular.

Hemostatic abnormalities in Noonan syndrome.

BACKGROUND: A bleeding diathesis is a common feature of Noonan syndrome, and various coagulation abnormalities have been reported. Platelet function has never been carefully investigated. METHODS: The degree of bleeding diathesis in a cohort of patients with Noonan syndrome was evaluated by a validated bleeding score and investigated with coagulation and platelet function tests. If ratios of prothrombin time and/or activated partial thromboplastin time were prolonged, the activity of clotting factors was measured. Individuals with no history of bleeding formed the control group. RESULTS: The study population included 39 patients and 28 controls. Bleeding score was ≥2 (ie, suggestive of a moderate bleeding diathesis) in 15 patients (38.5%) and ≥4 (ie, suggestive of a severe bleeding diathesis) in 7 (17.9%). Abnormal coagulation and/or platelet function tests were found in 14 patients with bleeding score ≥2 (93.3%) but also in 21 (87.5%) of those with bleeding score <2. The prothrombin time and activated partial thromboplastin time were prolonged in 18 patients (46%) and partial deficiency of factor VII, alone or in combination with the deficiency of other vitamin K-dependent factors, was the most frequent coagulation abnormality. Moreover, platelet aggregation and secretion were reduced in 29 of 35 patients (82.9%, P < .01 for all aggregating agents). CONCLUSIONS: Nearly 40% of patients with the Noonan syndrome had a bleeding diathesis and >90% of them had platelet function and/or coagulation abnormalities. Results of these tests should be taken into account in the management of bleeding or invasive procedures in these patients.

Disorders of hemostasis in overt and subclinical hypercortisolism.

Glucocorticoids are a group of hormones of a particular impact on hemostasis. Epidemiological studies show an approximately severalfold greater incidence of thromboembolic events in hypercortisolemic patients compared to those without hormonal disorders. The prothrombotic action of this steroid class is caused by both the direct impact of hypercortisolism on the activation of coagulation and the inhibition of fibrinolysis, as well as, the pathology of hemostasis due to metabolic disorders, which occur in this endocrinopathy. The aim of this study was to discuss the hemostasis abnormalities that occur in patients with overt and subclinical hypercortisolism with a particular emphasis on plasmatic coagulation, endogenous anticoagulation system, homocysteine and proinflammatory cytokines.

Haemostatic effects of levothyroxine and selenomethionine in euthyroid patients with Hashimoto's thyroiditis.

The aim of this prospective study was to investigate for the first time whether levothyroxine and selenomethionine, administered alone or in combination, affect coagulation and fibrinolysis in Hashimoto's thyroiditis patients with normal thyroid function tests. A group of 155 ambulatory women with recently diagnosed and previously untreated Hashimoto's thyroiditis, of whom 149 completed the study, were randomly assigned in a double-blind fashion to six months of treatment with levothyroxine, selenomethionine, levothyroxine plus selenomethionine, or placebo. The control group included 39 matched healthy women. The prothrombin time ratio, the activated partial thromboplastin time, and plasma levels/activities of fibrinogen, factor VII, von Willebrand factor, factor X and plasminogen activator inhibitor-1 (PAI-1) were assessed at baseline and after three and six months of treatment. Compared with the healthy subjects, Hashimoto's thyroiditis patients exhibited higher plasma levels/activities of all of the parameters studied, as well as were characterised by the abnormal prothrombin time ratio and activated partial thromboplastin time. All these haemostatic disturbances were reduced or normalised by levothyroxine + selenomethionine treatment, while the effect of levothyroxine or selenomethionine was limited to fibrinogen and PAI-1, respectively. Our results demonstrate that euthyroid women with Hashimoto's thyroiditis are characterised by abnormal coagulation and fibrinolysis. Levothyroxine and selenomethionine, especially if administered together, produce a beneficial effect on haemostasis in euthyroid patients with this disorder.

[The thromboelastometric criteria of hemostasis disorders correction during liver transplantation].

UNLABELLED: The purpose of the study. Optimum correction of hemostasis remains one of the unsolved problems in anesthesia maintenance during liver transplantation. Modern methods of coagulation monitoring (thromboelastography, thromboelastometry) allows to differ the increased bleeding reason. The clear criteria for the appointment of the blood components according to these methods have not developed so far. The aim of this study was to determine the criteria of hemostasis disorders correction during liver transplantation. MATERIALS AND METHODS: The study included all patients undergoing a liver transplantation in our clinic from January 2009 to December 2010. In certain intervals of time an intake of blood samples for the hemostasis study including koagulogramm, determination of the clotting factors and natural anticoagulants activity was performed. RESULTS: There is no significant correlation between the results of the standard coagulation tests and thromboelastometry Based on the international hemostasis correction recommendations, with the help of ROC-analysis the search for thromboelastometry data, which would have pointed to the need for this therapy was made. Concerning coagulation factors deficiency (INR>2, APTT> 1.5) CT-EXTEM>80 has a sensitivity of 17% and a specificity of 97%, and CT-INTEM>240 has sensitivity of 51% and specificity of 96%. Use of A10-FIBTEM for fibrinogen deficiency diagnosis, A10-FIBTEM <9 has sensitivity of 95% and specificity of 63%. A simultaneous increase of CT-EXTEM >80 and CT-INTEM more than 300 has a sensitivity of 96% and a specificity 81% in relation to diagnose thrombocytopenia (platelet count less than 50,000 per mcl). CONCLUSION: Correction of coagulation factors deficiency indicated when CT-EXTEM>80 and CT-INTEM> 240, hypofibrinogenemia when A10-FIBTEM <9, thrombocytopenia when of CT-EXTEM >80 and CT-INTEM increase simultaneously more than 300.

Haemostatic abnormalities in cats with naturally occurring liver diseases.

Alterations in the haemostatic system were characterized in cats with different naturally occurring liver diseases. The study looked at 44 healthy cats and 45 cats with different liver diseases confirmed histologically or cytologically (neoplasia, n=9; inflammation, n=12; hepatic lipidosis, n=13; other degenerative liver diseases, n=11). The following parameters were evaluated: platelet count; prothrombin time; activated partial thromboplastin time; thrombin time; factor (F) II, FV, FVII, FX, and FXIII activities; fibrinogen concentration; activities of antithrombin, protein C, plasminogen, and α(2)-plasmin inhibitor, and D-dimer concentration. In cats with liver diseases, 44/45 (98%) had one or more abnormalities of the coagulation parameters measured. In cats with inflammatory liver diseases, increased D-dimer concentrations and decreased FXIII activity were the most consistent abnormalities and were found in 83% and 75% of cats, respectively. The most common abnormality in cats with neoplastic liver disease was FXIII deficiency (78%). The most consistent abnormalities in cats with hepatic lipidosis were increased FV activity and D-dimer concentration with 54% of cats having values above the reference range for both parameters. Cats with miscellaneous degenerative liver disease most frequently showed FXIII deficiency (64%). The results of this study show that alterations of single haemostatic components are a frequent finding in cats with liver disease. Activation of haemostasis with subsequent consumptive coagulopathy (rather than decreased synthesis) seems to be responsible for these alterations. Increased blood levels of different haemostatic components in cats with inflammatory lesions may be related to an acute phase reaction.

Patients with liver cirrhosis suffer from primary haemostatic defects? Fact or fiction?

Patients with cirrhosis can have abnormalities in laboratory tests reflecting changes in primary haemostasis, including bleeding time, platelet function tests, markers of platelet activation, and platelet count. Such changes have been considered particularly relevant in the bleeding complications that occur in cirrhosis. However, several studies have shown that routine diagnostic tests, such as platelet count, bleeding time, PFA-100, thromboelastography are not clinically useful to stratify bleeding risk in patients with cirrhosis. Moreover, treatments used to increase platelet count or to modulate platelet function could potentially do harm. Consequently the optimal management of bleeding complications is still a matter of discussion. Moreover, in the last two decades there has been an increased recognition that not only bleeding but also thrombosis complicates the clinical course of cirrhosis. Thus, we performed a literature search looking at publications studying both qualitative and quantitative aspects of platelet function to verify which primary haemostasis defects occur in cirrhosis. In addition, we evaluated the contribution of qualitative and quantitative aspects of platelet function to the clinical outcome in cirrhosis and their therapeutic management according to the data available in the literature. From the detailed analysis of the literature, it appears clear that primary haemostasis may not be defective in cirrhosis, and a low platelet count should not necessarily be considered as an automatic index of an increased risk of bleeding. Conversely, caution should be observed in patients with severe thrombocytopenia where its correction is advised if bleeding occurs and before invasive diagnostic and therapeutic procedures.

Monitoring unfractionated heparin therapy in dogs by measuring thrombin generation.

BACKGROUND: The calibrated automated thrombogram (CAT), an assay that permits measurement of thrombin generation in plasma, may be useful in studying hemostatic disorders and anticoagulant therapy in animals. OBJECTIVES: The aims of the study were to measure thrombin generation in healthy Beagle dogs and to evaluate the potential use of the CAT assay for monitoring therapy with unfractionated heparin (UFH). METHODS: Individual platelet-poor plasma samples and a plasma pool from 20 healthy adult Beagles were prepared. Serial UFH plasma dilutions were used to establish an in vitro heparin-sensitivity curve. The pharmacodynamic effects of heparin in vivo were evaluated in Beagles using the CAT assay to measure thrombin generation with tissue factor at a concentration of 5 pM for initiation. RESULTS: In healthy Beagles, the range of endogenous thrombin potential (ETP) was 238.7-414.0 nM/min (mean ± SD, 340.4 ± 63.1 nM/min). ETP intra-assay and interassay variations were 7.1% and 12.9%, respectively. In vitro, a UFH concentration ≥0.4 U/mL resulted in total inhibition of thrombin generation. In vivo, the maximal effect of UFH on ETP was observed at 170 ± 36 minutes (range, 120-210 minutes) and resulted in a decrease in ETP of 38.5 ± 7.8% (range, 26.5-50.3%). In 210-420 minutes, ETP returned to baseline in 5 dogs. CONCLUSION: Our study demonstrates that thrombin generation can be measured in canine plasma and may be useful in assessing the degree of anticoagulation provided by UFH.

Hemostatic disorders in type 1 diabetes mellitus.

This review summarizes current knowledge of the adverse effects of type 1 diabetes mellitus on coagulation and fibrinolysis. Although further larger studies are needed to provide more definitive information, patients with type 1 diabetes exhibit a proinflammatory/procoagulant condition deriving from increased platelet adhesiveness, activation of the coagulation system, and decreased plasma fibrinolytic potential. This review also focuses on recent data from large prospective studies suggesting a strong association between procoagulant imbalance and development of chronic vascular complications in people with type 1 diabetes. It is likely that a greater appreciation of the intimate interactions between endothelial integrity, coagulation and fibrinolytic factors, and platelets in type 1 diabetes will provide a greater understanding of the risk of developing cardiovascular disease and microvascular complications such as nephropathy and retinopathy in this patient population.

[Hemostatic disorders caused by chronic use of valproic acid in neurosurgical patients. Thromboelastographic monitoring].

The paper gives the results of analyzing the hemostatic system in 26 patients with various neurosurgical diseases on the basis of routine laboratory biochemical tests and thromboelastographic indicators. In all the patients, the pattern of the disease contained an epilepsy syndrome that required mono- or combination therapy with valproic acid. Laboratory indicators of clinical hypocoagulation were found to develop during the use of valproic acid, and its monotherapy in particular. Hemorrhagic complications were also analyzed in not only the immediate, but also late postoperative period (for as long as 6 months after surgery). Two cases of severe late complications, such as formation of chronic subdural hematomas requiring surgical intervention, were diagnosed in the valproate monotherapy group. A tactic using a thromboelastographic technique is proposed to prepare these patients for further neurosurgical intervention.

[The choice of surgical tactics in patients with unstable hemostasis and gastroduodenal ulcer bleeding].

Treatment results of 476 patients with acute gastroduodenal ulcer bleeding were analyzed. Men comprised 75% (n=357), women - 25% (n=119). All patients were divided in two groups. Treatment principles of patients of the first group (36.8%; n=175) were based on active conservative treatment. Surgery was performed in 70.3%, postoperative lethality comprised 12.2%, overall mortality was 9.7%. Second group consisted of 301 patients (63.2%). Individual based active surgical treatment was performed, including clinical and endoscopic evaluation of local hemostasis, prognostic criteria of bleeding recurrence, differential approach in time, extent and method of the applied surgery. Operative treatment was used in 81.1% of patients of the second group, postoperative lethality comprised 9.8%, overall mortality was 8.0%. Emergency operations were performed in 43.6% (n=160) of all patients, early elective surgery in 56.4% (n=207). Postoperative lethality comprised 10.6%, overall mortality rate was 8.6%. Therefore, individual based active surgical treatment proved to be preferable. Gastric resection showed to be more advisable then organ-preserving operations, considering emergency ulcer surgery.

Prostate-specific antigen, prostate cancer, and disorders of hemostasis.

Prostate cancer is the most prevalent malignancy in men and the third leading cause of cancer deaths worldwide. Disorders of hemostasis are commonplace in patients with prostate cancer and include disseminated intravascular coagulation, venous thromboembolism, acute coronary syndrome, and postsurgical bleeding. These hemostatic disorders contribute to the mortality and morbidity of prostate cancer. The leading mechanisms proposed to underlie prostate cancer-related coagulopathies are thought to be a hyperexpression of tissue factor, cancer procoagulant, and platelet-activating factor, which is then accompanied by release of large amounts of both prothrombotic and profibrinolytic substances into the bloodstream. Given the generally accepted notion that prostate-specific antigen (PSA) represents an important biomarker in prostate cancer diagnostics, large population screenings were initiated for early detection of cancer. However, recent clinical and economic drawbacks have been recently raised, including evidence that screening exposes patients to a significant risk of both overdiagnosis and overtreatment. Nevertheless, several lines of evidence suggest that PSA may have tumor-suppressing activities. Despite being a member of the vast kallikrein family, which actively interplays with the coagulation cascade, the role of PSA in the pathogenesis of hemostatic disorders observed in prostate cancer patients remains circumstantial and speculative. However, observations that the levels of this cancer marker tend to correlate positively with those of several markers of thrombin generation, and with postsurgical bleeding as well as with coronary atherosclerosis and negative outcomes of myocardial infarction, raise a new and intriguing scenario regarding the pathophysiological role of this serine protease.