Showing papers in "Seminars in Thrombosis and Hemostasis in 1994"

Antiphospholipid and thrombosis syndromes.

Abstract: ACAs and the lupus anticoagulant are strongly associated with thrombosis and appear to be the most common of the acquired blood protein defects causing thrombosis. Although the precise mechanism or mechanisms whereby antiphospholipid antibodies alter hemostasis to induce a hypercoagulable state remain unclear, several theories, as previously discussed, have been advanced. The most common thrombotic events associated with ACAs are DVT and PE (type I syndrome), coronary or peripheral artery thrombosis (type II syndrome), cerebrovascular or retinal vessel thrombosis (type III syndrome), and occasionally patients present with mixtures (type IV syndrome). The relative frequency of ACAs in association with arterial and venous thrombosis strongly suggests that these should be looked for in any patient with unexplained thrombosis; all three idiotypes (IgG, IgA, and IgM) should be assessed. Also, the type of syndrome (I through IV) should be defined, if possible, because this may dictate both type and duration of both immediate and long-term anticoagulant therapy. Unlike those with ACAs, patients with primary lupus anticoagulant thrombosis syndrome usually have venous thrombosis. Since the aPTT is unreliable in patients with lupus anticoagulant and is not usually prolonged in patients with ACAs, definitive tests (ELISA for ACA and the dRVVT for lupus anticoagulant) should be immediately ordered when suspecting antiphospholipid syndrome or in patients with otherwise unexplained thrombotic or thromboembolic events.

Syndromes of hypercoagulability and thrombosis: a review.

Abstract: This review has stressed the common hereditary and acquired blood protein defects associated with thrombosis. The most common of the hereditary defects appear to be antithrombin, protein C, and protein S deficiency and the most common acquired defects are anticardiolipin antibodies and the lupus anticoagulant. Therefore these are the defects that should first be looked for in an individual with unexplained thrombosis. If these more common defects are not found, then the rarer defects, including heparin cofactor II, plasminogen or tissue plasminogen activator deficiency, dysfibrinogenemia, or elevated PAI-1 should next be sought. The importance of finding these defects has significant implications for therapy of the individual patient and for institution of family studies to identify, inform, and possibly treat others at risk. It is expected that as knowledge of hemostasis expands, more hereditary and acquired defects, such as elevated lipoprotein(a) or defects of extrinsic (tissue factor) pathway inhibitor may be associated with enhanced risks of thrombosis.

Platelet-activating factor-induced endothelial cell expression of adhesion molecules and modulation of surface glycocalyx, evaluated by electron spectroscopy chemical analysis.

Abstract: PAF synthesized by or added to the endothelial cell monolayer has as first target the endothelium itself, inducing the expression of GMP-140 on the cell surface and qualitative alterations in the composition of glycocalyx. As seen by ESCA, sulfated chemical groups were significantly reduced after PAF stimulation. This reduction depended on selective loss of sulfated proteoglycans that were released into the supernatant. The alteration of glycocalyx may favor functional exposure of GMP-140 and of PAF on the surface of endothelial cells and may reduce charge repulsive forces between cells. PAF associated with endothelial cell surface has as second target PMNs and stimulates in cooperation with GMP-140, the functional activation of PMN CD11-CD18 adhesion molecules.

Effects of heparin and its desulfated derivatives on leukocyte-endothelial adhesion.

Abstract: The effect of heparin and partially desulfated heparin derivatives on thrombin and PAF-induced adhesion of PMNs to the endothelium was studied either by a fluorescence image analysis or by 111In-labeled PMNs. The results observed with these two techniques consistently indicated that heparin and O-des-heparin inhibited PMN adhesion in a dose-dependent manner. Moreover, N-des-Hep and N-O-des-Hep, even if less effective, also inhibited the adhesion of PMNs when used at high concentrations. The effect of heparin and heparin derivatives was not directed to endothelial cells but rather to PMNs, as shown by the absence of inhibitory effects, when heparins were preincubated with endothelium.

Gas-liquid chromatography-mass spectrometry analysis of anticoagulant active curdlan sulfates.

Abstract: 1. To evaluate the sulfation pattern of anticoagulant active curdlan sulfates, a methylation method, based on the synthesis of alkylated alditol acetates, followed by GLC-MS examination, was developed. 2. By the specific cleavage of the sulfate esters, using solvolysis and the substitution of these liberated OH groups with ethyl iodide, a third kind of substitution was introduced in the alkylated alditol acetates, specifically replacing the former sulfate esters. 3. The primary OH group in position 6 had more than the 10-fold accessibility to sulfation, in comparison to the secondary OH groups in positions 2 and 4. 4. Products with a low DS were fairly homogenously substituted, having unsubstituted or selectively C6-sulfated glucose units. Increasing DS was associated with a loss of homogeneity as well as selectivity of the C6 sulfation. 5. Sulfation of C6-protected curdlan resulted in products with a higher content of sulfate groups in positions 2 and 4, and consequently a uniform charge distribution around the glucose monomer. 6. Besides the dependence on the DS and the MW, also the sulfation pattern influenced the anticoagulant activity. The higher the portion of the secondary linked sulfate esters, the higher the anticoagulant activity. The C6-protected curdlan sulfates had activities normally corresponding to higher DS and MW.

Human pharmacokinetics of glycosaminoglycans using deuterium-labeled and unlabeled substances: evidence for oral absorption.

Abstract: In the present study, the pharmacokinetics of extractive GAGs used as therapeutic agents have been studied after intravenous and oral administration on volunteers. The use of native or deuterium-labeled compounds, followed by HPLC/MS detection, allowed the quantitation of exogenous heparin and DS as major disaccharide fragments, obtained either by enzymatic or chemical depolymerization. In particular the high level of labeling reached in DS allowed its differentiation from structurally related endogenous species. The estimated plasmatic bioavailability was about 18% for DS. Notwithstanding the impossibility of evaluating the same parameters for heparin species, due to the interferences of endogenous GAGs, the results obtained provided clear evidence of oral availability of heparin and DS through detection and quantitation of structures specifically related to these GAGs. Due to the selectivity of the lyases used, the enzymatic degradation specifically allowed the detection of both DS and heparin species still retaining the original sulfation pattern. Additionally, the chemical degradation could detect the main metabolites of the drugs, consisting of partially to totally desulfated GAGs showing a more or less marked reduction in their molecular weight.

Antiphospholipid Antibodies in Coronary Artery Disease: A Review

Abstract: APAs present a clinical problem that is now recognized to be a significant causative factor of both fatal and nonfatal myocardial infarction as well as other coronary syndromes. Similar to the thrombotic complications of APAs in the cerebrovascular system, the result can be life-threatening or fatal. Correct diagnosis requires a high index of suspicion, especially in patients with known prior thrombotic events and in those who present with myocardial ischemia or infarction without underlying risk factors and at a young age. In these patients an aggressive laboratory evaluation must be performed, including testing for APAs. The treatment of the coronary syndrome must progress along currently accepted approaches, including the aggressive and early use of thrombolytic therapy followed by anticoagulation with heparin, porcine heparin, or possibly low molecular weight heparin. Intermediate and long-term therapy with some form of heparin or high-intensity warfarin anticoagulation is essential to have any chance of preventing coronary reocclusion and recurrent myocardial infarction as well as other thrombotic events. Although the precise incidence of APAs in the general and coronary artery disease population is not known and although in the individual patient early disease may be difficult to detect, an enhanced awareness of the possibility of the association of APAs with coronary artery disease may allow earlier diagnosis and may save lives. Studies of larger numbers of patients over extended time periods with various pharmacological approaches to anticoagulation are needed to define more clearly optimal management.

Extravascular Proteolysis and the Nervous System: Serine Protease/Serpin Balance

Abstract: Widely recognized as components of the blood coagulation cascade, serine proteases and their natural inhibitors, specific serpins known as the protease nexins, also regulate the maintenance of normal function in the nervous system. Increasingly, evidence has accumulated as to regulation of their synthesis and functional roles within both the CNS and peripheral nervous system. Our review focuses on the localization and activity of TH and PN I in the nervous system, as well as on the impact of the protease/inhibitor balance for the pathogenesis of neurodegenerative disorders such as AD.

Clinical syndromes associated with lupus anticoagulants.

Abstract: Recent evidence suggests that lupus anticoagulants are immunologically distinct from the anticardiolipin antibodies. Nevertheless, the associated clinical complications exhibited by the two groups of antibodies are similar. They have been shown to have a strong association with a history of arterial and venous thrombosis, thrombocytopenia and neurological disease in patients with SLE or lupus-like disorders. The association between antiphospholipid antibodies and recurrent fetal loss is suggested by the currently available data but is not firmly established. Patients with lupus and antiphospholipid antibodies and an established history of recurrent fetal wastage are at high risk for experiencing subsequent fetal loss, but it is not yet known whether the same is true for patients without a history of fetal loss. The association of thrombosis, neurological disease, thrombocytopenia, and fetal loss in patients with non-SLE disorders has not been as extensively studied. Only recently have investigators such as Ginsberg and colleagues begun to show in prospective studies that there may, in fact, be a statistically significant risk of thrombotic events in otherwise healthy individuals with antiphospholipid antibodies. Many of the diverse minor manifestations reported in individual patients, case series, or cross-sectional studies such as livedo reticularis, leg ulcers, and hemolytic anemia may, alternatively, be due to coincidence or chance. Efforts to elucidate the mechanisms of thrombosis in patients with antiphospholipid antibodies is an area of active research. Most efforts have been based on the effects of these antibodies on endothelial cell and platelet function as well as on the fibrinolytic system. In addition, it has recently been shown that binding of antiphospholipid antibodies to phospholipids requires the serum "co-factor" beta 2-glycoprotein I. In patients with SLE selected for the presence of the lupus anticoagulant, thrombosis, or fetal loss, Viard and associates found that 17 of 47 (36%) patients had anti-beta 2-glycoprotein I antibodies. They were able to show, in their small retrospective study, that there was an association between the presence of these antibodies and anticardiolipin activity, lupus anticoagulant activity, and thrombotic events, but not with spontaneous abortion. Of patients with SLE and thrombosis (9 of 47) eight of nine were positive for anti-beta 2-glycoprotein I antibodies, seven of nine were positive for anticardiolipin antibodies, and eight of nine were positive for the lupus anticoagulant. The known inhibitory effect of beta 2-glycoprotein I on platelet aggregation, on platelet prothrombinase activity, and on the intrinsic pathway of coagulation supports the hypothesis that implicates beta 2-glycoprotein I in the pathogenesis of unwanted thrombotic events.(ABSTRACT TRUNCATED AT 400 WORDS)

Cutaneous expressions of antiphospholipid syndromes

Abstract: The cutaneous clinical signs of antiphospholipid syndromes are expressed as stagnation of blood flow as livedo reticularis, purplish erythematous macules of acral areas, or end result of thrombosis as ulcers and necrosis (Fig. 6) (Table 1). Corresponding histological signs are reflected as thrombosis of dermal blood vessels (Fig. 7).

Hemostatic system activation in patients with lupus anticoagulant and essential thrombocythemia.

Abstract: Hemostatic system activation was estimated in the plasmas of 39 patients with LAC and 19 patients with ET by measuring concentrations of TAT complex and prothrombin F1+2. The concentrations of FVII, recognized previously as a risk factor for arterial thrombosis, were also measured. None of the patients had active thrombosis during this study. The mean TAT and F1+2 levels in LAC and ET plasmas were higher than the respective values in the plasmas of healthy control subjects. Compared with their respective controls, TAT levels were significantly higher in the LAC group (P < 0.05) and F1+2 was significantly higher in the ET group (P < 0.005). The mean FVIIt and FVIIz was significantly higher (P < 0.05 and P < 0.01, respectively) in LAC than control plasmas. Furthermore, the differences between FVIIt and FVIIz were significantly greater in LAC than control plasmas, indicating increased in vivo proteolysis of FVII in LAC. Although the mean concentrations of these two FVII parameters in ET plasma were not significantly different from those of normal plasmas, the FVII levels were higher in 30% of ET plasmas than the upper limit of controls. Our results are consistent with hypercoagulation in LAC and ET patients, and this may be a contributory factor for the increased rates of thrombosis associated with the two conditions.

Current trends in antithrombotic drug and device development.

Abstract: Many significant developments in the diagnosis and clinical management of thrombotic disorders have occurred recently [1– 24, 26]. Basic medical sciences have contributed remarkably in both the areas of therapeutics and diagnosis of arterial and venous thrombosis. Many newer approaches for the diagnosis and treatment of thrombotic disorders have been introduced [10, 14, 16]. This has only been possible due to the understanding of the molecular mechanisms involved in the development of thrombotic processes.

Comparison of three heparin bovine serum albumin binding methods for production of antiheparin antibodies.

Abstract: IgG antiheparin antibody secreting hybrid cells have not been successfully raised so far Therefore, we compared three different conjugating procedures for preparation of LMMH-protein conjugates Albumin was chosen as carrier protein Only the conjugate prepared by reductive amination induced antiheparin antibody production in mice Conjugates prepared by the carbodiimide method and Mannich reaction did not induce heparin immunogenicity and did not induce antibody production in mice Antiheparin antibody production in mice and by hybrid cells was detected by assaying serum and culture supernatant LMMH-tyramine, labeled with 125I, was bound by the antibodies and immunoprecipitated by goat anti-mouse IgG antibodies The tracer was competitively inhibited by nonlabeled heparin for binding to the heparin antibodies Hybridoma cells producing the specific antiheparin antibody were cloned and subcloned up to monoclonality Six hybrids were selected and designated H118, H121, H31, H317, H318, H424 In conclusion, six monoclonal antiheparin antibodies were raised using a LMMH-albumin conjugate prepared by reductive amination

High-performance size exclusion chromatography and polyacrylamide gel electrophoresis for characterization of unfractionated and low molecular mass glycosaminoglycans.

Abstract: The microheterogeneity of glycosaminoglycans was analyzed using HPSEC and PAGE. GAG preparations were analyzed five times to determine the standard deviation of the average molecular mass and the polydispersity P of each GAG with HPSEC. In addition, the Kav coefficient, the area under the absorbance time curve, and the peak purity were determined as mean and standard deviation. PAGE was performed five times using the same preparations and the average molecular mass and polydispersity were calculated. The results of PAGE and HPSEC were compared and the molecular mass distribution of the two methods was shown. The advantage of PAGE is the higher sensitivity and the resolution of oligosaccharides. The advantage of HPSEC is the better standardization, higher reproducibility, and speed.

Therapeutic Use of Low Molecular Weight Heparins: Knowledge to Date and Their Application to Therapy

Abstract: Indeed, the accumulating evidence indicates that certain LMW heparins administered subcutaneously may replace classic intravenous heparin therapy. Certain of these subcutaneously administered LMW heparins do not require monitoring. The simplified care offered by LMW heparin therapy offers the possibility of transferring care from in to out of hospital in uncomplicated patients with deep vein thrombosis. The advantages to the patient of avoiding in-hospital care and its associated hazards are obvious. Outpatient LMW heparin therapy will likely prove to be highly cost effective. It is uncertain at present whether the findings associated with an individual LMW heparin preparation can be extrapolated to a different LMW heparins. For this reason, the findings of clinical trials apply only to the particular LMW heparin evaluated and cannot be generalized to the LMW heparins at large.

Thrombin-induced alterations in endothelial cell cytoarchitectural and functional properties.

Abstract: alpha-Thrombin interacts with confluent bovine pulmonary artery endothelial cells to produce two types of actin microfilament rearrangements: (1) The loss of cortical actin correlates with interruption of barrier integrity, evident from increased permeability to 125I-albumin; and (2) an increase in actin stress fibers results in greater adherence of the cells to their extracellular substrate. Use of phallatoxin compounds that stabilize actin filaments and prevent their depolymerization prevents both the cytoarchitectural and functional changes resulting from thrombin challenge.

Derivatives of bis-aldonic acid amides and their anticoagulant and antithrombotic properties

Abstract: Aprosulate sodium was the first representative of a new class of synthetic polyanions showing antithrombotic efficacy in different animal models In several clinical trails (Phase I) in human volunteers aprosulate demonstrated anticoagulant properties, too Searching for other active substances of similar structure, a series of bis-aldonic acid amides were synthesized These compounds exhibited interesting antithrombotic and anticoagulant activities The pharmacodynamic activities of the compounds LW 10121, LW 10125, LW 10114, 10244, and LW 10168 are summarized in this article These substances prolonged the APTT to 150% of the blank values at concentrations of 15 to 135 micrograms/mL The thrombin time and anti-Xa test were only slightly influenced by concentrations up to 100 micrograms/mL All compounds were investigated in a jugular vein hemostasis model in rats to examine their antithrombotic potential They all had an antithrombotic activity lower than aprosulate, except compound LW 10121, which seemed to be a little more active The subcutaneous injection of 10 mg/kg LW 10121 resulted in a longer duration of action than aprosulate and heparin On the basis of the chemical structure and the profile of action, it is assumed that the new compounds may possess the same mode of action as aprosulate, but the mechanism of action may be different from heparin and low molecular weight heparins