Disorders of fibrinolysis

The Role of Fibrinolytic System in Health and Disease

The fibrinolytic system is composed of the protease plasmin, its precursor plasminogen and their respective activators, tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), counteracted by their inhibitors, plasminogen activator inhibitor type 1 (PAI-1), plasminogen activator inhibitor type 2 (PAI-2), protein C inhibitor (PCI), thrombin activable fibrinolysis inhibitor (TAFI), protease nexin 1 (PN-1) and neuroserpin. The action of plasmin is counteracted by α2-antiplasmin, α2-macroglobulin, TAFI, and other serine protease inhibitors (antithrombin and α2-antitrypsin) and PN-1 (protease nexin 1). These components are essential regulators of many physiologic processes. They are also involved in the pathogenesis of many disorders. Recent advancements in our understanding of these processes enable the opportunity of drug development in treating many of these disorders.

Pathophysiology and Nonsurgical Treatment of Chronic Subdural Hematoma: From Past to Present to Future

BACKGROUND

Chronic subdural hematoma (CSDH) is one of the more frequent pathologic entities in daily neurosurgical practice. Historically, CSDH was considered progressive recurrent bleeding with a traumatic cause. However, recent evidence has suggested a complex intertwined pathway of inflammation, angiogenesis, local coagulopathy, recurrent microbleeds, and exudates. The aim of the present review is to collect existing data on pathophysiology of CSDH to direct further research questions aiming to optimize treatment for the individual patient.

METHODS

We performed a thorough literature search in PubMed, Ovid, EMBASE, CINAHL, and Google scholar, focusing on any aspect of the pathophysiology and nonsurgical treatment of CSDH.

RESULTS

After a (minor) traumatic event, the dural border cell layer tears, which leads to the extravasation of cerebrospinal fluid and blood in the subdural space. A cascade of inflammation, impaired coagulation, fibrinolysis, and angiogenesis is set in motion. The most commonly used treatment is surgical drainage. However, because of the pathophysiologic mechanisms, the mortality and high morbidity associated with surgical drainage, drug therapy (dexamethasone, atorvastatin, tranexamic acid, or angiotensin-converting enzyme inhibitors) might be a beneficial alternative in many patients with CSDH.

CONCLUSIONS

Based on pathophysiologic mechanisms, animal experiments, and small patient studies, medical treatment may play a role in the treatment of CSDH. There is a lack of level I evidence in the nonsurgical treatment of CSDH. Therefore, randomized controlled trials, currently lacking, are needed to assess which treatment is most effective in each individual patient.

Lethal ricin intoxication in two adult dogs: toxicologic and histopathologic findings

Two adult dogs with the same owner were intoxicated by ingestion of fertilizer composed of residual plant material of the castor bean plant (Ricinus communis L.). Both dogs died within 2 and 3 days, respectively, after the first signs of vomiting and abundant hemorrhagic diarrhea. Toxicologic and histopathologic examinations were performed on different organs. Histopathologic examination of the kidneys revealed tubular degeneration and necrosis and membranous glomerulonephritis. Additionally, myocardial degeneration with localized inflammation, lymphoid necrosis, and depletion in the spleen and mesenteric lymph nodes and hemorrhagic ulcerative gastroenteritis were found. The 2 cases could be used to elucidate the lethal dose of ricin and the histopathologic lesions in dogs.

Significance of fibrin formation and dissolution in the pathogenesis and treatment of cancer

Despite increased concentration of plasminogen activators in malignant tumors, fibrinolytic potential in blood of cancer patients and tumor tissue is low. At the same time histochemical and microscopic examination revealed the presence of fibrin-like material coating tumor cells. It is postulated in the present paper that the increased concentrations of -SH groups and arginine-rich peptides, and the activation of tissue transglutaminases in the tumor tissue are responsible for the resistance of the fibrin coat to enzymatic degradation. The fibrin coat, in turn, causes neoplastic cells not to be recognized by the immunological system and thus makes them immune to the attack by the natural killer cells. Administration of naturally occurring, but diminished in cancer, derivatives of alpha ketoaldehydes resistant to glyoxalases, reverses the effect of -SH and arginine-rich peptides, and reactivates fibrinolysis. Consequently, removal of the fibrin coat from tumor cells makes them vulnerable to the attack of killer cells and their subsequent elimination.

Immunohistochemical localization of tissue-type plasminogen activator in the lining wall of chronic subdural hematoma

Capsules of chronic subdural hematoma were immunohistochemically stained with monoclonal antibody against tissue-type plasminogen activator. Endothelial cells of sinusoids and capillaries in the outer membrane showed strong immunostaining. Endothelial cells of veins and arteries in the dura mater showed moderate and weak staining. No cells other than the endothelial cells were stained. In the inner membrane, tissue-type plasminogen activator immunoreactivity was not seen. The mean concentration of tissue-type plasminogen activator in the hematoma content was higher than that in the plasma. The more the sinusoids in the outer membrane were developed, the higher the concentration of tissue-type plasminogen activator contained in the hematoma fluid. In chronic subdural hematoma, overproduction and oversecretion of tissue-type plasminogen activator from the sinusoidal and capillary endothelial cells in the outer membrane cause increased fibrinolysis, which in turn impairs hemostasis, and hemorrhage from the capillaries recurs, resulting in enlargement of the chronic subdural hematoma.

Effects of exercise on plasma fibrinolytic activity in patients with ischaemic heart disease

In order to investigate the response of plasma fibrinolytic activity to exercise in patients with ischaemic heart disease, we studied 109 patients with chronic stable angina pectoris. All patients were exercised on the treadmill according to the Bruce protocol. They were subsequently divided into 2 groups according to the results of exercise testing. The first group comprised 47 patients with negative exercise tests and the second group 62 patients with positive exercise tests. The plasma fibrinolytic activity was determined in all patients by the method of euglobulin lysis time before exercise, at peak exercise and 2 hours later. The results were compared with those of a control group which consisted of 30 normal healthy volunteers. In the control group there was a significant increase of plasma fibrinolytic activity (P less than 0.001) at peak exercise, which almost returned to the resting levels at 2 hours. In all patients with angina, resting and peak exercise fibrinolytic activity level was significantly lower than that of the control group (P less than 0.01 and less than 0.001, respectively), although at peak exercise it also increased significantly (P less than 0.001) compared to resting levels and it remained elevated at 2 hours after exercise (P less than 0.001). In patients with negative exercise test, plasma fibrinolytic activity at rest was almost identical to that of the control group, it increased with exercise (P less than 0.001) but to values below those of the control group (P less than 0.01) and although there was a tendency to return to resting levels it remained elevated (P less than 0.01) at 2 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

The fibrinolytic system in man

The existence of a system in the human body capable of inducing the dissolution of endogenous pathologically formed thrombi was appreciated in ancient times. Considered in detail in this article are the data that have elucidated the physiologic regulation of which plasmin formation is dependent on, the plasma concentration of plasminogen, availability of activators of plasminogen in the plasma and surrounding tissue environment, the concentration of naturally present inhibitors, and the existence of fibrin in the circulation. Important in this rapidly progressive scientific discipline is consideration of the factors which control the synthesis of the components of this proteolytic enzyme system. Recently abundant information has indicated that this plasminogen-plasmin proteolytic enzyme system can be utilized therapeutically. Knowledge of the mechanisms of this system has permitted identification of agents that can be exogenously administered to releave thrombotic obstruction to blood flow in the venous (pulmonary emboli, deep vein thrombosis) and arterial (peripheral and central vessels) circulatory systems. Particularly important is the demonstration that thrombolytic agents can directly attack and alleviate the immediate cause of acute myocardial infarction. As a result of the innovations in the present decade, it is evident that the plasminogen system can be advantageously employed to reverse the pathologic effects of all thrombotic diseases.

A study of disseminated intravascular coagulopathy in hepatic coma complicating acute viral hepatitis

Thirty cases of viral hepatitis with and without coma and 15 normal healthy age and sex matched controls were studied for disseminated intravascular coagulopathy (DIC). Cases of viral hepatitis with coma showed strong evidence of DIC in the form of increased plasma FDP (240 +/- 190.64 dilution), diminished fibrinogen half life (48.1 +/- 15.3 hours) and increased fractional catabolic rate (46.13 +/- 14.7% per day) with normal Euglobulin clot lysis time and reduced fibrinogen (147.33 +/- 43.5%) and platelet count (1.27 +/- 0.324 lakhs/cm.). The possible role of heparin in the reversal of coagulation abnormalities have been discussed.

Comparative effect of clofibrate, garlic and onion on alimentary hyperlipemia

The effect of clofibrate on the same subjects in similar test conditions were used as a control to verify the alleged beneficial effects from garlic and onion on alimentary hyperlipemia in normals and in cases with ischemic heart disease. The results showed that clofibrate checked the fat-induced (a) rises of serum triglyceride and plasma fibrinogen, and (b) falls of coagulation time (CT) and blood fibrinolytic activity (BFA). Only garlic had a clofibrate-like effect on CT but both garlic and onion checked the postprandial fall of BFA. Clofibrate, however, increased BFA even above the fasting level. Serum cholesterol and beta-lipoprotein were not appreciably affected by fat with or without any drug. Thus, surprisingly, the so-called beneficial effects of garlic and onion were not seen in subjects who had shown significant changes after clofibrate.

Current clotting concepts in urology

A modern outline of the physiology of coagulation, a simple approach to the use of laboratory investigation for patients with possible clotting disorders in unexplained hematuria and several illustrative cases are presented. The diagnosis and management of localized fibrinolysis in the genitourinary tract and intravascular coagulation as possible causes of post-prostatectomy hemorrhage are discussed. A minimum of a platelet count, fibrinogen assay and, if possible, measurement of fibrinogen-related antigens should be obtained before administration of epsilon aminocaproic acid.

Intracellular distribution of neutral proteinases and inhibitors in pig leucocytes. Isolation of two inhibitors of neutral proteinases

Granule and post-granular-supernatant fractions were obtained from pig leucocyte cells by differential centrifugation in 0.34 M sucrose. Granule extract possesses proteinase activity at acid and at neutral pH. Three groups of neutral and a group of acid proteinases were isolated from granule extracts by chromatography on DEAE-cellulose. In the first group are present elastase-like and plasminogen-activator proteinases, that are inhibited by diisopropylphosphorofluoridate, alpha1-antitrypsin, intracellular leucocyte inhibitor and partly with p-aminomethylbenzoic acid and Trasylol. The second group of neutral proteinases is unstable under the conditions of isolation used the third group of neutral proteinases comprises collagenases that are inhibited by ethylenediamine tetraacetic acid disodium salt, alpha1-antitrypsin and leucocyte inhibitor. The acid proteinases are inhibited only with pepstatin, up to 90%. In the post-granular supernatant was found the acid proteinase activity towards hemoglobin and casein, and non-stable neutral proteolytic activity towards bovine serum albumin and serum gamma globulin. In the post-granular supernatant also the inhibitors of neutral proteinases were found. By gel filtration on Sephadex G-100 and ion-exchange chromatography on CM-cellulose two inhibitors of neutral proteinases were isolated. The majority of the inhibitor capacity (about 80%) of post-granular supernatant was eluted together with ovalbumin (Mr 43000) and the remainder with cytochrome c (12300). These inhibitors inhibit the granule neutral proteinases, acting on all substrates used, but do not inhibit granule acid proteinase. Inhibition effects of post-granular-supernatant inhibitors on trypsin and chymotrypsin were obtained only when bovine serum albumin was used as substrate. Inhibitors of post-granular supernatant are stable at pH 6-8, but unstable in the pH rnage 2-5 and are thermolabile.

Hematologic problems in urology. Basic mechanisms and clinical approach

Baxic clotting mechanisms are reviewed. The clinical and laboratory aspects of disseminated intravascular coagulation and fibrinolysis are discussed, and an approach is suggested to those problems encountered by the urologist.