Phenotypic and Functional Transformation in Smooth Muscle Cells Derived from a Superficial Thrombophlebitis-affected Vein Wall.

BACKGROUND: Superficial thrombophlebitis (ST) is a frequent pathology, but its exact incidence remains to be determined. This study tested the hypothesis whether relationships exist among smooth muscle cells (SMCs) derived from ST, varicose great saphenous veins (VGSVs), and normal great saphenous veins (GSVs). METHODS: Forty-one samples of ST, VGSVs, and GSVs were collected. SMCs were isolated and cultured. Proliferation, migration, adhesion, and senescence in SMCs from the three vein walls were compared by various methods. Bax, Bcl-2, caspase-3, matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 messenger RNA (mRNA) and protein expressions were detected by fluorescence quantitative PCR and Western blot. RESULTS: An obvious decrease in cytoskeletal filaments was observed in thrombophlebitic vascular smooth muscle cells (TVSMCs). The quantity of proliferation, migration, adhesion, and senescence in TVSMCs was significantly higher than in varicose vascular smooth muscle cells and normal vascular smooth muscle cells (NVSMCs) (all P < 0.05). Bax and caspase-3 mRNA and protein expression were decreased, while Bcl-2 mRNA and protein expression were increased in the TVSMCs compared with the varicose vascular smooth muscle cells and the NVSMCs (all P < 0.05). MMP-2, MMP-9, TIMP-1, and TIMP-2 mRNA and protein expression were significantly increased in the TVSMCs compared with the VVGSVs and the NVSMCs (all P < 0.05). CONCLUSION: SMCs derived from ST are more dedifferentiated and demonstrate increased cell proliferation, migration, adhesion, and senescence, as well as obviously decreased cytoskeletal filaments. These results suggest that the phenotypic and functional differences could be related to the presence of atrophic and hypertrophic vein segments during the disease course among SMCs derived from ST, VGSVs, and GSVs.

Effect of miR-223 on thrombophlebitis rats through regulating Toll-like receptor signaling pathway.

OBJECTIVE: To explore the effect of the micro ribonucleic acid (miR)-223 on the thrombophlebitis rats by regulating the Toll-like receptor (TLR) signaling pathway. MATERIALS AND METHODS: The rat model of thrombophlebitis was established, and miR-223 was silenced or overexpressed through lentiviral transfection. The rats were divided into miR-223 inhibitors group (Inhibitors group), miR-223 mimics group (Mimics group), and normal group (Control group). The transfection efficiency of miR-223 in venous tissues was detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR), the hemorheological indexes plasma viscosity (PV) and hematocrit (HCT) were observed, and the content of the serum inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-ß (TNF-ß) were detected via enzyme-linked immunosorbent assay (ELISA). Moreover, the fibrinolytic indexes plasminogen activator inhibitor (PAI) and the tissue-type plasminogen activator (t-PA) were detected, the morphological changes in the venous tissues were observed via hematoxylin-eosin (HE) staining, and the gene and protein expressions of the TLR signaling pathway were detected via RT-PCR and Western blotting. RESULTS: The expression of miR-223 was significantly increased in the Mimics group (p<0.05) and significantly decreased in the Inhibitors group (p<0.05). The high-shear and low-shear whole blood viscosity and HCT in the Inhibitors group were significantly higher than those in the Mimics group (p<0.05). The levels of serum IL-6, IL-1ß, and TNF-ß in the Inhibitors group were remarkably higher than those in the Mimics group (p<0.05). The Inhibitors group had a remarkably lower level of t-PA (p<0.05) and a remarkably higher level of PAI than the Mimics group (p<0.05). Besides, the inferior vena cava wall shed and disappeared due to complete necrosis in the Inhibitors group. In the Mimics group, the vascular lumen was slightly expanded, and the vascular wall had intact contour. It was found in the gene detection that the mRNA levels of TLR2, myeloid differential protein-88 (MyD88) and c-Jun N-terminal kinase (JNK) were evidently increased in the Inhibitors group, and the significant increases in the protein levels of TLR2 and MyD88 were also observed in the protein detection. CONCLUSIONS: The overexpression of miR-223 can inhibit the TLR signaling pathway, thereby promoting the recovery of thrombophlebitis rats.

Assessment of apoptotic cells in the wall of thrombophlebitic saphenous vein.

INTRODUCTION: Programmed cell death plays a critical role in various physiological processes. In the present study, we investigated its possible pathogenic role in primary varicose veins. We studied histological changes in surgical specimens from thrombophlebitic saphenous veins. In thrombophlebitic saphenous, varicose, and healthy veins, we also determined the number of apoptotic cells, and investigated apoptosis in the role of the pathogenesis of varicose veins. METHODS: Forty-four specimens of thrombophlebitic saphenous veins and simple varicose veins were collected. Thirteen samples of normal great saphenous veins were also collected (control group). Apoptosis of venous walls was determined by terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) and immunofluorescence methods. The corpuscular number per high-power field was counted under light microscopy. RESULTS: A significantly higher apoptotic ratio of the intima and media were observed in control veins as compared with thrombophlebitic saphenous veins and simple varicose veins (p < 0.01). A significant difference was not observed between thrombophlebitic saphenous veins and simple varicose veins (p > 0.05). A significant difference was not seen between the intima and media of the three groups (p > 0.05). CONCLUSION: In the walls of thrombophlebitic saphenous veins and varicose veins, the apoptotic indices were clearly decreased. The results suggest that the process of programmed cell death was inhibited in walls of thrombophlebitic saphenous veins and varicose veins.

Assessment of vasa vasorum in the walls of thrombophlebitic saphenous vein.

AIM: The purpose of this study was to investigate the proliferation of vasa vasorum (VV) in the walls of thrombophlebitic saphenous vein (TSV), and to evaluate the influence of high venous pressure and lack of oxygen on the VV. METHODS: The specimens of the great saphenous vein were collected: 11 primary varicose vein (PVV), 11 TSV and, as a control, eight normal great saphenous vein. Masson staining and immunohistochemistry for CD34 were used to observe the status of VV, and the number of VV were counted under light microscopy. RESULTS: VV of the thrombophlebitic saphenous vein group (TSVG) were clustered together in adventitia, increased linearly in media, and scattered appearance in intima, were increased partially in intima of thrombus rupturing. In TSVG, the number of VV observed in adventitia, media and intima was 16.738±7.685, 4.845±2.537, 2.448±3.030, respectively. In the primary varicose vein group (PVVG), the corresponding values were 14.280±4.440, 2.965±1.125, 0.500±0.548. And the number was 8.911±2.629, 0.150±0.424, 0±0 in the control group (CG). Significantly higher numbers of VV were observed in the TSVG as compared to the PVVG or CG (P<0.05). No significant difference was observed between intima and media (P>0.05). CONCLUSION: Thrombi in varicose veins can induce proliferation of VV, which may be involved in high venous pressure and hypoxia.

Activated protein C resistance and its correlation with thrombophlebitis in Behçet's disease.

Patients with Behçet's disease (BD) have been recognized to be at an increased risk of thrombosis and thrombotic complications have been reported in 12%-40% of patients. The precise pathogenetic mechanisms underlying the thrombotic tendency of BD are not known. In recent researches, it is reported that procoagulant mutations might play a role in thrombotic process in BD patients. We aimed to evaluate the frequency of activated protein C resistance (APCR) in our BD patients and to investigate the association between thrombophlebitis and APCR. The study included 116 patients with BD who fulfilled the International Study Group criteria and 70 healthy individuals as a control group. APCR levels were measured by the clotting method. APCR levels were 129.63 ± 39.70 and 152.26 ± 22.62 in BD patients and control group, respectively (P<0.01). APCR was found in 47.4% and 8.6% of BD patients and control group, respectively (P<0.01). There was no statistically significant difference regarding APCR levels between patients with thrombophlebitis and without thrombophlebitis (46.4% vs. 48.3%). We found the frequency of APCR to be increased in BD patients with or without thrombophlebitis. The lack of association between thrombophlebitis and APCR in our series of BD patients suggests that some factors like endothelial abnormalities other than thrombophilia play a major role in the pathogenesis of thrombosis in BD.

Influence of thrombophlebitis on TGF-ß1 and its signaling pathway in the vein wall.

Extensive extracellular matrix remodeling of the vein wall is involved in varicose veins pathogenesis. This process is controlled by numerous factors, including peptide growth factors. The aim of the study was to evaluate influence of thrombophlebitis on TGF-ß1 and its signaling pathway in the vein wall. TGF-ß1 mRNAlevels, growth factor content and its expression were evaluated by RT-PCR, ELISA, and western blot methods, respectively, in the walls of normal veins, varicose veins and varicose veins complicated by thrombophlebitis. Western blot analysis was used to assess TGF-ß receptor type II (TGF-ß RII) and p-Smad2/3 protein expression in the investigated material. Unchanged mRNA levels of TGF-ß1, decreased TGF-ß1 content, as well as decreased expression of latent and active forms of TGF-ß1 were found in varicose veins. Increased expression of TGF-ß RII and p-Smad2/3 were found in varicose veins. Thrombophlebitis led to increased protein expression of the TGF-ß1 active form and p-Smad2/3 in the vein wall compared to varicose veins. TGF-ß1 may play a role in the disease pathogenesis because of increased expression and activation of its receptor in the wall of varicose veins. Thrombophlebitis accelerates activation of TGF-ß1 and activity of its receptor in the varicose vein wall.

Hyperglycemia accelerates arterial thrombus formation and attenuates the antithrombotic response to endotoxin in mice.

Recent human studies reveal that hyperglycemia induces procoagulant and antifibrinolytic effects in blood that may contribute to a greater risk of arterial thrombosis, but the direct relationship between high blood glucose levels and thrombosis has not yet been investigated. We performed a number of experiments to clarify whether hyperglycemia was causally related to arterial thrombosis and whether the combined stimulus of hyperglycemia and inflammation would enhance the thrombotic effect. In a model of ferric-chloride-induced carotid artery thrombosis, hyperglycemia did not influence the time to occlusion in mice pretreated with streptozotocin, but the rate of thrombus formation was accelerated. This effect was associated with increased thrombin generation and could not be explained by changes in vessel-wall tissue factor activity. The prothrombotic effect of hyperglycemia was assessed in a separate experiment, showing that collagen/thrombin-induced platelet procoagulant activity was increased in hyperglycemic mice. The effect of inflammation was studied by injecting a low dose of endotoxin that caused a systemic inflammatory state after 24 h (increased plasma levels of tumor necrosis factor alpha, interleukin-6 and monocyte chemotactic protein 1 in diabetic and nondiabetic mice) associated with a mild delay in thrombus formation. This reduced rate of thrombus formation was attenuated by hyperglycemia. Together, these data establish a discrete but clear contribution of hyperglycemia in experimental arterial thrombosis.

[Changes in cell adhesion molecules under the influence of surgical treatment in patients with acute thrombophlebitis of the subcutaneous veins in the lower extremities]. / Zminy volekul adheziï klityn pid vplyvom khirurhichnoho likuvannia khvorykh na hostryi tromboflebit pidshkirnykh nyzhnikh kintsivok.

The content of soluble molecules of intercellular adhesion-1 (sICAM-1) in 60 patients with an acute thrombophlebitis (TP) of the lower extremities subcutaneous veins was studied preoperatively and 7 days after the operation using method of a solid phase immunoenzymatic analysis (IEA). The sICAM-1 level before treatment in men was increased at average by 75.8% (P < 0.001), in women--by 81.5% (P < 0.001) in comparison with control group, after treatment it was lowered somewhat. The gender differences of patients for the average sICAM-1 concentration was not noted. In ascending TP sICAM-1 higher level preoperatively and its normalization on 7th day postoperatively were observed in patients, admitted to in surgical unit and operated 3-5 days after the beginning of disease. In patients, to whom conservative treatment was performed initially (anti-inflammatory and thrombolytic therapy), but its efficacy was minimal, the content of cell adhesion molecules preoperatively and before the treatment did not differ. Positive dynamic of index was revealed after the intervention. The results of investigation trust the important role of cell adhesion in pathogenesis of an acute TP of the lower extremities subcutaneous veins and perspective of application of the sICAM-1 method determination in dynamic of the patients treatment to estimate the surgical efficacy intervention.

Selectin-mucin interactions as a probable molecular explanation for the association of Trousseau syndrome with mucinous adenocarcinomas.

Trousseau described spontaneous, recurrent superficial migratory thrombophlebitis associated with occult cancers, and this was later correlated with disseminated microangiopathy (platelet-rich clots in small blood vessels). Trousseau syndrome often occurs with mucinous adenocarcinomas, which secrete abnormally glycosylated mucins and mucin fragments into the bloodstream. Since carcinoma mucins can have binding sites for selectins, we hypothesized that selectin-mucin interactions might trigger this syndrome. When highly purified, tissue-factor free carcinoma mucin preparations were intravenously injected into mice, platelet-rich microthrombi were rapidly generated. This pathology was markedly diminished in P- or L-selectin-deficient mice. Heparin (an antithrombin-potentiating agent that can also block P- and L-selectin recognition of ligands) ameliorated this platelet aggregation, but had no additional effect in P- or L-selectin-deficient mice. Inhibition of endogenous thrombin by recombinant hirudin also did not block platelet aggregation. Mucins generated platelet aggregation in vitro in hirudinized whole blood, but not in platelet-rich leukocyte-free plasma nor in whole blood from L-selectin-deficient mice. Thus, Trousseau syndrome is likely triggered by interactions of circulating carcinoma mucins with leukocyte L-selectin and platelet P-selectin without requiring accompanying thrombin generation. These data may also explain why heparin ameliorates Trousseau syndrome, while vitamin K antagonists that merely depress thrombin production do not.

Generation of reactive oxygen metabolites by the varicose vein wall.

OBJECTIVES: to evaluate the content of lipid peroxidation products (expressed by the concentration of thiobarbituric acid-reactive substances; TBARS), the content of myeloperoxidase (MPO), and the localisation of xanthine oxidase (XO) in varicose veins (vv), varicose veins with superficial thrombophlebitis and unchanged saphenous veins. METHODS: varicose saphenous veins, varicose veins with superficial thrombophlebitis and normal saphenous veins obtained during varicose vein surgery on 36 patients as well as healthy saphenous veins from cadaver organ donors (control). Homogenates were prepared in which TBARS concentration and MPO content were determined. Immunohistochemical staining to detect XO was also performed. RESULTS: the highest concentration of TBARS occurred in vv with superficial thrombophlebitis, the lowest in donor vein. The highest content of MPO was observed in vv and slightly lower - in varicose veins with thrombophlebitis. A positive reaction for XO was seen in vv wall endothelium. Specimens of vv with thrombophlebitis revealed strong, intense staining in endothelium as well as in vasa vasorum. CONCLUSIONS: varicose veins, especially those complicated with superficial thrombophlebitis revealed increased free radical generation. Its sources might be neutrophils, and in vv complicated with superficial thrombophlebitis-xanthine oxidase.

Dendritic cells in venous pathologies.

Dendritic cells are potent antigen-presenting cells responsible for the activation of T-lymphocytes in various immune responses. Their role in the initiation of immune reactions in allergies, autoimmune diseases, tumors, transplantation, and, more recently, in atherosclerosis has been well established, but their involvement in venous pathologies has not been previously investigated. The aim of this study was to determine whether dendritic cells are present in veins affected by varicosity and thrombophlebitis. Three groups of veins obtained at operation were studied: (1) varicose veins of the great saphenous vein from patients who were undergoing vein stripping for primary varicosity; (2) segments of the great saphenous vein from patients with varicosity complicated by thrombophlebitis; and (3) great saphenous veins without varicosity or thrombophlebitis from patients who were undergoing femoropopliteal bypass grafting. The specimens were fixed in 10% neutral buffered formalin and embedded in paraffin, and the sections were stained with antibodies to S-100 (to identify dendritic cells), CD3 (T-lymphocytes), CD68 (macrophages), von Willebrand factor (endothelial cells), alpha-smooth muscle actin (smooth muscle cells), and CD15 (mast cells) by use of avidin-biotin complex (ABC) immunoperoxidase technique. Immunohistochemical examination showed that no S-100-positive dendritic cells were present in normal saphenous veins. In contrast, S-100-positive cells with dendritic cell morphology were detected in the intima and media of veins with varicosity and thrombophlebitis, where they represented a minor cell population. S-100-positive dendritic cells were located between smooth muscle cells as well as around areas of neovascularization where they colocalized with T-lymphocytes. The present work suggests that dendritic cells might be involved in pathological processes in veins affected by varicosity and thrombophlebitis. The authors speculate that dendritic cells may be involved in the inflammatory mechanisms in these veins through their interaction with T-lymphocytes.

Superficial vein thrombosis of lower limbs: influence of factor V Leiden, factor II G20210A and overweight.

Superficial vein thrombosis (SVT) has been reported in patients with thrombophilia. In the present unmatched case-control study, the two most common thrombophilic abnormalities (factor V Leiden and factor II G20210A) were searched for in 112 consecutive patients with SVT of lower limbs and in 180 healthy donors. FV Leiden was present in 16/112 (14.3%) SVT patients and 11/180 (6.1%) controls (odds ratio 2.51, 95% CI 1.04-6.24) and FII G20210A in 4/112 (3.6%) patients and 2/180 (1.1%) controls (OR 3.28, 95% CI 0.46-36.84). In addition, body mass index (BMI) > or =28 kg/m2 was also associated with SVT (OR 2.81, 95% CI 1.60-5.00). After adjustment for BMI > or =28 kg/m2, the association between FV Leiden and SVT remained strong though no longer statistically significant. Among patients with SVT, the presence of FV Leiden was independently associated with the absence of varicose veins (OR 4.62, 95% CI 1.25-18.0) and with a BMI > or =28 kg/m2 (OR 3.74, 95% CI 1.05-15.1). In conclusion, both FV Leiden and overweight seem to predispose to SVT, a finding that should be confirmed in larger studies.

Aging and venous thromboembolism influence the pharmacodynamics of the anti-factor Xa and anti-thrombin activities of a low molecular weight heparin (nadroparin).

Venous thromboembolism may be efficiently treated by one single daily administration of a high dose of low molecular weight heparin (LMWH). The present study investigates if the physiological deterioration of renal function associated with normal aging or the presence of an acute venous thromboembolism influences the pharmacodynamic pattern of the anti-factor Xa and anti-thrombin activities. Three groups of 12 subjects were investigated. The first 2 groups were composed of healthy volunteers differing by age (25 +/- 4 and 65 +/- 3 yrs) and creatinine clearance (114 +/- 15 and 62 +/- 6 ml x min(-1)). The third group was composed of patients hospitalized for deep vein thrombosis, having a mean age of 65 +/- 11 yrs and creatinine clearance of 76 +/- 8 ml x min(-1). Nadroparin was administered subcutaneously once daily at the dose of 180 anti-factor Xa IU.kg(-1) for 6 to 10 days. Serial sampling on day 1 and on the last day of administration (day n) allowed the pharmacodynamic parameters of the anti-factor Xa and anti-thrombin activities to be compared at the beginning and at the end of the treatment. The main findings were the following: (1) After repeated administration, a significant accumulation of the anti-factor Xa activity was observed in the healthy elderly and in the patients but not in the healthy young subjects (accumulation factor: 1.3). There was no evidence of accumulation of anti-thrombin activity; (2) There were significant correlations between the clearance of creatinine and the clearance of the anti-factor Xa activity but not with that of the anti-thrombin activity; (3) In the patients, the clearance of the anti-factor Xa and of the anti-thrombin activities were 1.4 and 2 times higher respectively than those calculated in the healthy elderly; (4) The mean ratio of the of anti-factor Xa and anti-thrombin clearances was close to 2 in the healthy subjects but equal to 5.4 in the patients. These results suggest that the mechanisms involved in the clearance of polysaccharide chains which support the anti-thrombin activity are different from those of the anti-factor Xa activity and that the enhanced binding properties of plasma proteins to unfractionated heparin reported in patients presenting an acute venous thromboembolism also exists for LMWH, predominantly for the anti-thrombin activity.

Antithrombotic effects of YM-60828 in three thrombosis models in guinea pigs.

The antithrombotic effects of a novel factor Xa inhibitor, YM-60828 ([N-[4-[(1-acetimidoyl-4-piperidyl)oxy]phenyl]-N-[(7-amidino-2-nap hthyl)methyl]sulfamoyl]acetic acid dihydrochloride), in three thrombosis models in guinea pigs were studied in comparison with its effect on bleeding time. The antithrombotic effects of YM-60828 were most pronounced in the venous thrombosis and the arterio-venous shunt models but YM-60828 showed 10-fold weaker effects in the carotid thrombosis model. However, YM-60828 prolonged bleeding time at a much higher dose than that required in all thrombosis models. In conclusion, YM-60828 exerted its antithrombotic effects without prolonging bleeding time in all thrombosis models and may be of clinical value not only in venous thrombosis but also in arterial thrombosis.

Increased plasma granulocyte elastase levels in Behçet's disease.

OBJECTIVE: To assess the role of granulocyte elastase in the development of thromboembolic vasculopathy in patients with Behçet's disease. METHODS: Plasma granulocyte elastase-alpha1-proteinase inhibitor (E-PI) complex levels were measured by ELISA in 11 healthy subjects and 19 patients with Behçet's disease (BD). Eight of 19 patients showed deep vein thrombosis on (99m)technetium-macro-agglutinate albumin venography. Hemostatic variables were measured at the same time. RESULTS: The mean plasma E-PI complex level was significantly higher in the 8 patients with than in the 11 patients without deep vein thrombosis (242 +/- 73 vs 165 +/- 97 ng/ml; p = 0.033). The mean plasma E-PI complex level in the 11 patients without deep vein thrombosis was significantly higher than in controls (165 +/- 97 vs 96 +/- 40 ng/ml; p = 0.038). Plasma E-PI complex levels correlated with the serum plasmin-alpha2-plasmin inhibitor complex levels (r = 0.621, p = 0.0084). CONCLUSION: Plasma E-PI complex levels appear to be a useful marker of thromboembolic vasculopathy in BD.

Acute myeloid leukemia accompanied by multiple thrombophlebitis.

A 66-year-old woman suffering from fever and thrombophlebitis was referred to our hospital. A peripheral blood examination revealed hyperleukocytosis with 96% blast cells and thrombocytopenia. The patient was diagnosed as having acute myeloid leukemia (AML) accompanied by disseminated intravascular coagulation (DIC). A marked decrease in protein C (PC) antigen and activity were observed. In this case, PC levels were lower than those observed in AML with DIC. Induction therapy for leukemia and treatment of DIC were started on the first day of hospitalization. The patient achieved complete remission, with PC antigen and activity levels normalized.

Tissue factor in health and disease.

Over the last years numerous studies have focussed on the in vivo expression of tissue factor (TF) in health and disease. The selective perivascular distribution of TF and the lethal effects of TF knockouts have added strong support to the widely accepted view that TF plays a pivotal role in the initiation of blood coagulation during physiological hemostasis. Inappropriate in vivo expression of TF, particularly by cells that do not express this protein under normal conditions (mainly monocyte-macrophages and endothelial cells), has been documented and is likely responsible for fibrin deposition in a variety of pathological conditions, among which sepsis-associated disseminated intravascular coagulation (DIC) and thromboembolic disease. In malignancy, in vivo expression of TF by tumor cells and/or by host cells has been implicated not only in intratumoral and systemic activation of blood coagulation but also in tumor growth and dissemination.

Resistance to activated protein C: a major cause of inherited thrombophilia.

Blood coagulation proteins play a major role in the development of pathological venous and arterial thrombosis. Inherited disorders of thrombosis are due to deficiencies of the anticoagulant proteins antithrombin, protein C, and protein S in 10% to 15% of individuals that present with venous thrombosis. A recently described cause of venous thrombosis is characterized by a poor response to activated protein C. In 90% of cases the activated protein C resistance is attributable to a mutation in the factor V gene (factor V Leiden). Activated protein C resistance is found in up to 7% of the Caucasian population but essentially unseen in other races. Activated protein C resistance is associated with a 5 to 10X increased risk of venous thrombosis in individuals that are heterozygous for the defect and a 50 to 100X increased risk in those individuals that are homozygous for factor V Leiden. Activated protein C resistance can be detected in the laboratory by modifications of the activated partial thromboplastin time assay. This assay is easy to perform and can be automated for a variety of instruments. Confirmation of the mutation of the factor V gene is accomplished through polymerase chain reactions that require DNA extraction from the patient's blood sample. Global assays that reflect the functionality of the protein C pathway have recently been introduced to the marketplace.

Endothelial fibrinolytic reactivity and the risk of deep venous thrombosis after spinal cord injury.

Deep vein thrombosis (DVT) is a frequent event in patients with spinal cord injury, even with prophylactic anticoagulant therapy. Lower limb paralysis is a known major risk factor for venous thrombosis, supposedly due to the venostasis in relation with total immobility. The main goal of this study was to evaluate the endothelial response to anoxia to determine whether recovery of fibrinolytic potential occurs in patients subjected to forced bedrest because of a spinal cord injury and whether this recovery is related to the incidence and/or evolution of DVT. We evaluated vascular endothelium reactivity in the lower limbs no longer submitted to the hydrostatic pressure of the erected position in 15 patients with paraplegia or tetraplegia and in 10 normal volunteers after venous occlusion produced by the application of 10 cm Hg pressure to the lower limb for 15 min comparatively to the upper limb used as reference. Among the 15 patients, 10 whose spinal cord injury had occurred 1 to 6 months earlier were still receiving prophylactic anticoagulant therapy, whereas the five other patients were not receiving prophylactic anticoagulants because the injury dated back 6 months or more. After venostasis, tissue plasminogen activator (tPA) increased significantly in both patients and controls in the upper limb (tPA levels twofold and threefold respectively in controls and patients) but showed no significant changes in the lower limb; prolonged immobility did not allow recovery in the lower limbs of a level of fibrinolytic responsiveness identical to that in the upper limbs. The plasminogen activator inhibitor (PAI1) remained unchanged after anoxia, although wide interindividual variations were seen. Natural coagulation inhibitors and circulating blood stigmates of hypercoagulability were measured. None of the patients had abnormally low levels of coagulation inhibitors (ie, antithrombin III, protein C and protein S levels were normal). Seventy-five per cent of patients (prophylactically anticoagulated or not) had very high levels of fibrin degradation products (D. Dimer levels sevenfold to eightfold those of the controls), but all patients had normal levels of thrombin-antithrombin complexes and prothrombin fragments 1 + 2. The permanence of the thrombotic process characterized by an increase in D. Dimer levels without recovery of fibrinolytic potential suggests a proposal for the patients an indefinite antithrombotic treatment at curative doses.

Pharmacokinetic optimisation of the treatment of deep vein thrombosis.

The current treatment for deep vein thrombosis is a 5- to 10-day course of heparin followed by 3 to 6 months of oral anticoagulants. Both heparin and oral anticoagulants present a high inter- and intra-individual variability and require individualisation and monitoring of their dosage. The pharmacokinetic properties of heparin have been difficult to assess through the radiolabelling procedures typically used for many other drugs. This is partially a result of the heterogeneous nature of heparin. Thus, the pharmacokinetics of heparin are expressed in terms of its pharmacodynamic activity. Improved coagulation test methodology coupled with the incorporation of patient factors such as bodyweight, height, baseline coagulation status, pretreatment heparin sensitivity and heparin concentrations, can be used to improve the accuracy of heparin dosage determination. Computer-based systems are now available to assist clinicians in quantitating dosage requirements, estimating bleeding risks, and storing patient dose-response relationships for future therapy monitoring. Low molecular weight heparin products might improve our ability to control anticoagulant therapy because drug concentration, as well as the effect on the clotting system, will be more predictable in patients receiving these products. In addition, low molecular weight heparins produce a more consistent, predictable anticoagulant response, and clinicians have a new pharmacological tool which may readily lend itself to patient-controlled, home-based anticoagulant pharmacotherapy. Where pharmacokinetics and pharmacodynamics could contribute to the optimisation of warfarin treatment is in the initiation of treatment, the estimation of the dosage required, the methods for drug monitoring, the assessment of unusual responses and the avoidance of drug interactions. Traditional pharmaco kinetic methods have limited applicability to the optimisation of warfarin therapy because there is no direct relationship between drug concentration and therapeutic effect. However, a variety of simple or sophisticated computer-assisted methods have been developed to help clinicians in individualising and monitoring warfarin treatment. New therapeutic approaches, such as direct thrombin inhibitors and thrombolytic agents, could overcome some limitations of the standard heparin plus oral anticoagulation therapy.