Fibrinolytic activity in patients undergoing hepatic transplantation

Bleeding complications during liver transplantation have been attributed to accelerated fibrinolysis. In order to determine its cause, 11 adults (mean age: 38.9 +/- 13.2 yr) undergoing liver transplantation were studied. There were three groups of patients: cirrhosis (n = 4), fulminating hepatitis (n = 4) and one group including a primary biliary cirrhosis, a hepatic metastasis and a hepatoma. The following factors were studied in the immediate preoperative period, at different surgical times throughout the procedure and 2-3 h after the end of the abdominal sutures: platelet count, prothrombin concentration, fibrinogen, activated kephalin time, factors II, V, VII + X and VIIIc, antithrombin III, protein C, D-dimers, fibrinogen and fibrin degradation products (PDF), plasma plasminogen, tissue plasminogen activator (tPA) and the fast tPA inhibitor (PAi). Preoperatively, only the two patients with hepatic cancer had a normal haemostatic profile. Throughout the procedure, all patients had only moderate changes in platelets, coagulation factors and their inhibitors, and plasminogen, because platelet concentrates and fresh frozen plasma were transfused. Levels of tPA rose, becoming very high during the anhepatic period and just after graft reperfusion. An abrupt fall occurred at the end of surgery. There were important individual differences in tPA activity. PAi activity was low during the preanhepatic and anhepatic stages, rising rapidly after revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Haemostasis in patients with Beh?et's disease.

AIM: to determine whether Beh?et's disease affects haemostatic function. SETTING: University Hospital, Turkey. PATIENTS: one hundred and twenty-seven consecutive patients with Beh?et's disease, 34 of whom with a history of vascular involvement. METHODS: prothrombin fragment 1+2 tissue plasminogen activator, protein S and C, antithrombin, fibrinogen, von Willebrand factor, thrombomodulin and prothrombin time (PT) were measured in patient plasma. RESULTS: soluble thrombomodulin was significantly lower and von Willebrand factor (vWF) and tissue plasminogen activator (tPA) significantly higher in Beh?et's patients. Patients with vascular involvement showed the highest levels of vWF and tPA. There was no activation of coagulation, not even in patients with an active disease at the time of sampling. CONCLUSION: there were indirect signs of endothelial activity or damage, particularly in patients with vascular involvement. Coagulation was not activated.     

Fibrinolytic activity in traumatic hemothorax fluids]

Twenty-nine patients, 15 to 85-year-old (mean: 50 years) who presented with a pleural effusion after trauma were studied. The blood content of pleural fluid was confirmed by thoracocentesis. None of the patients had been taking anticoagulant drugs during the fortnight preceding the trauma. Thoracocentesis was always carried out less than 90 min after the trauma. The following parameters were measured in the haemothorax liquid samples: clotting fibrinogen fraction (Fg C), fibrin degradation D-dimers, functional plasminogen, alpha 2-antiplasmin, alpha 2-macroglobulin, plasminogen tissue activator (tPA Ag), type 1 tPA plasma inhibitor (PAI), and haematocrit. Haemothorax liquid haematocrit values ranged from 13 to 35% (25 +/- 7%, with a mean peripheral venous haematocrit of 34 +/- 6%). Only three patients had some Fg C (0.05-0.13 g.l-1). The D-dimer level was very high (0.23 +/- 0.22 g.l-1). The other factors involved in fibrinolysis were also present. Moreover, there was a statistically significant inverse correlation between D-dimer and alpha 2-macroglobulin levels (r = -0.64, p less than 0.0025). These data suggest two possible mechanisms to explain the fibrinogen levels: coagulation is activated, followed by an important fibrinolytic reaction elicited by the large amounts of plasminogen and tPA present in the haemothorax liquid.     

Perioperative activation of hemostasis in vascular surgery patients

BACKGROUND: Perioperative activation of hemostasis could play an important role in the occurrence of postoperative cardiac events. The authors conducted a prospective study to assess platelet function, coagulation, and fibrinolysis status during and after infrarenal aortic surgery. METHODS: Seventeen patients were studied. Excluded were patients with preoperative coagulopathies or liver disease, or cardiac or renal insufficiency; patients receiving anticoagulant treatment, antiplatelet agents, nonsteroidal antiinflammatory agents, fresh frozen plasma, or platelet concentrates; and patients undergoing reoperation and septic patients. Blood samples were drawn before induction (T1), 1 h after incision (T2), 1 h after extubation (T3), 24 h postoperatively (T4), 48 h postoperatively (T5), and at day 7 (T6). The following tests were performed: platelet count, platelet aggregation, platelet flow cytometry for CD62 and CD63, usual coagulation tests, thrombin--antithrombin complexes, plasminogen activator inhibitor 1. RESULTS: A significant increase of adenosine diphosphate--induced platelet aggregation was observed postoperatively at T4 and T5. This was not associated with a change of flow cytometry profile. No increase of thrombin--antithrombin complex levels was observed. A higher fibrinogen rate was detected at T5 and T6. Greater amounts of plasminogen activator inhibitor 1 were detected at T3 and T4. Thus, thrombin generation was limited and fibrinolysis was impaired postoperatively. Platelets were not activated in the postoperative period, as shown by flow cytometry, but were prone to be activated, as shown by aggregation studies. CONCLUSION: The association of more easily activated platelets with a higher fibrinogen rate and a temporary shut down of fibrinolysis during the early postoperative period may indicate an increased thrombotic risk in patients undergoing major vascular surgery.     

Enhanced expression of plasminogen activator inhibitor 1 in patients with nephrotic syndrome

Hypercoagulability is present in patients with nephrotic syndrome. However, alterations in coagulation and fibrinolysis reflected in the glomeruli and urine are not fully understood. We examined plasma and urine concentrations of tissue-type plasminogen activator (tPA) and type 1 plasminogen activator inhibitor (PAI-1) in 33 patients with nephrotic syndrome (nephrotic group). We compared these concentrations with the concentrations in 30 nonnephrotic patients with chronic glomerulonephritis (nonnephrotic group) and with the concentrations in 30 healthy volunteers (control group). We also examined fibrin/fibrinogen degradation products in serum and urine and plasma D-dimers. The expression of tPA and PAI-1 was examined in isolated glomeruli using RT-PCR methods. Deposition of fibrinogen/fibrin-related antigen was observed by direct immunofluorescence. The incidence of fibrinogen/fibrin-related antigen deposition in the nephrotic group was significantly higher than that in the nonnephrotic group. The concentrations of fibrin/fibrinogen degradation products in serum and urine and of plasma D-dimers were significantly elevated in the nephrotic group as compared with the nonnephrotic and control groups. The plasma concentrations of tPA in the nephrotic group were significantly higher than those in the control group. The urinary excretion of tPA in the nephrotic group was also significantly higher than in the nonnephrotic and control groups. The urinary excretion of PAI-1 in the nephrotic group was higher than that in the control group. The ratio of PAI-1 mRNA to tPA mRNA in glomeruli was increased in the nephrotic group as compared with the nonnephrotic group. These results indicate that the fibrinolytic activity is increased in patients with nephrotic syndrome despite urinary losses of tPA. However, a relatively enhanced expression of PAI-1 may be involved in the intraglomerular fibrinogen/fibrin-related antigen deposition seen in nephrotic syndrome.     

Hemostatic abnormalities in total artificial heart patients as detected by specific blood markers.

We retrospectively evaluated the hemostatic system of 13 patients during implantation (2 to 35 days) of the Jarvik 7-70 total artificial heart (TAH). Although all patients were clinically manageable while on the TAH, 5 had excessive generalized bleeding. After the heart transplant procedure, 2 patients had neurological events and 1 patient, thrombosis of the leg. While the patients were supported by the TAH, the routine coagulation assays (prothrombin time, activated partial thromboplastin time, fibrinogen, factor assays, and platelet count) showed slight abnormalities but no correlation to hemorrhagic or thrombotic events. In contrast, plasma and cellular activation markers, which are highly sensitive and specific for hypercoagulability, fibrinolysis, or platelet activation, revealed activation in all patients. Most striking was the marked activation of the fibrinolytic system (p less than 0.05 to 0.001). Correlations of individual patient data compared with the average TAH group response could be made between excessive enhancement of fibrinolysis (increased D-dimer and tissue plasminogen activator and decreased plasminogen activator inhibitor) and bleeding. A hypercoagulable state (increased fibrinogen and thrombin-antithrombin complex and decreased antithrombin III and protein C), decreased fibrinolysis (decreased tissue plasminogen activator and D-dimer), activated platelets (increased thromboxane B2), or combinations of these were associated with thrombosis. The hemostatic activation returned to normal 1 day after removal of the TAH. These data suggest that the patient with a TAH requires more sophisticated laboratory monitoring and individualized treatment for excessive fibrinolysis, hypercoagulable state, or platelet activation to avoid thrombotic and hemorrhagic complications.     

Activation of platelets, coagulation and fibrinolysis in patients on long-term haemodialysis: influence of cuprophan and polyacrylonitrile membranes

This study was designed to evaluate platelet activation, enhancement of coagulation and fibrinolysis in patients with chronic renal failure on long-term haemodialysis. Beta thromboglobulin (BTG), platelet factor 4 (PF4), fibrinopeptide A, tissue plasminogen activator (t-PA) activity and antigen, tissue plasminogen activator inhibitor (PAI), fibrin, and fibrinogen degradation products were studied during dialysis. The influence of two types of membrane on these parameters was also evaluated. The patients comprised 24 individuals on long-term haemodialysis on either cuprophan membrane (CUP) (12 patients) or polyacrylonitrile membrane (AN 69) (12 patients). Blood samples were collected before, at 15 min, and at the end of dialysis. The results demonstrated that platelet activation was permanent and increased during haemodialysis. However, no difference could be demonstrated between patients treated on CUP and patients treated on AN 69. Coagulation was also enhanced permanently but did not show modification during haemodialysis. Fibrinolysis was activated at the end of haemodialysis in half the patients, but again no difference could be demonstrated between patients treated on AN 69 and CUP membranes. It was concluded that the process of haemodialysis itself enhanced platelet activation, coagulation, and fibrinolysis but that both membranes were of equal effect.     

Perioperative Activation of Hemostasis in Vascular Surgery Patients

Background: Perioperative activation of hemostasis could play an important role in the occurrence of postoperative cardiac events. The authors conducted a prospective study to assess platelet function, coagulation, and fibrinolysis status during and after infrarenal aortic surgery.

Methods: Seventeen patients were studied. Excluded were patients with preoperative coagulopathies or liver disease, or cardiac or renal insufficiency; patients receiving anticoagulant treatment, antiplatelet agents, nonsteroidal antiinflammatory agents, fresh frozen plasma, or platelet concentrates; and patients undergoing reoperation and septic patients. Blood samples were drawn before induction (T1), 1 h after incision (T2), 1 h after extubation (T3), 24 h postoperatively (T4), 48 h postoperatively (T5), and at day 7 (T6). The following tests were performed: platelet count, platelet aggregation, platelet flow cytometry for CD62 and CD63, usual coagulation tests, thrombin-antithrombin complexes, plasminogen activator inhibitor 1.

Results: A significant increase of adenosine diphosphate-induced platelet aggregation was observed postoperatively at T4 and T5. This was not associated with a change of flow cytometry profile. No increase of thrombin-antithrombin complex levels was observed. A higher fibrinogen rate was detected at T5 and T6. Greater amounts of plasminogen activator inhibitor 1 were detected at T3 and T4. Thus, thrombin generation was limited and fibrinolysis was impaired postoperatively. Platelets were not activated in the postoperative period, as shown by flow cytometry, but were prone to be activated, as shown by aggregation studies.     

不同二氧化碳气腹时间胆囊切除术患者凝血纤溶功能和血管内膜损伤的比较

目的 比较不同二氧化碳气腹时间胆囊切除术患者的凝血纤溶功能和血管内膜损伤程度.方法 择期拟行腹腔镜胆囊切除术患者64例,年龄23～60岁,体重45～82 kg,ASA分级Ⅰ或Ⅱ级,根据气腹持续时间不同分为3组:气腹时间≤30 min组(Ⅰ组,n=21)、30 min＜气腹时间＜60 min组(Ⅱ组,n=23)和气腹时间≥60 min组(Ⅲ组,n=20).气腹压力维持12～14 mm Hg,分别于术前(T0)、术毕(T1)、术后1、2,3 d(T2～4)时抽取静脉血样,测定凝血酶原时间、激活部分凝血活酶时间、血浆凝血酶原片段1+2(F1+2)、纤维蛋白原(Fib)、组织纤溶酶原激活物和纤溶酶原激活物抑制物-1(PAI-1)的浓度和抗凝血酶-Ⅲ(AT-Ⅲ)、血管性血友病因子(vWF)的活性.结果 与Ⅰ组比较,Ⅲ组T2时vWF活性和PAI-1浓度升高,T3时Fjb、F1+2、PAI-1浓度和vWF活性升高,AT-Ⅲ活性降低,T4时Fib 和F1+2浓度升高(P＜0.05);与Ⅱ组比较,Ⅲ组上述指标差异无统计学意义(P＞0.05).结论 气腹时间短时胆囊切除术后患者凝血纤溶功能变化小,血管内膜损伤不明显;随气腹时间延长,凝血功能增强,纤溶功能受抑制,血管内膜损伤加重.

Abstract：

Objective To compare the changes in blood coagulation, fibrinolysis and endothelial damage in patients undergoing laparoscopic cholecystectomy with different durations of carbon dioxide pneumoperitoneum. Methods Sixty-four ASA Ⅰ orⅡpatients, aged 23-60 yr, weighing 45-82 kg, scheduled for elective laparoscopic cholecystectomy, were randomly divided into 3 groups according to the duration of pneumoperitoneum: duration of pneumoperitoneum ≤30 min group (group Ⅰ, n=21), 30 min ＜ duration of pneumoperitoneum ＜ 60 min (group Ⅱ, n=23) and duration of pneumoperitoneum≥ 60 min (group Ⅲ , n=20).The intra-abdominal pressure was maintained at 12-14 mm Hg. Venous blood samples were taken before surgery (baseline, T0 ),at the end of surgery(T1), and at 1, 2 and 3 d after surgery (T2-4) for determination of prothrombin time, activated partial thromboplastin time, concentrations of prothrombin fragment 1+2(F1+2), fibrinogen (Fib), tissue plasminogen activator and plasminogen activator inhibitor type-1 (PAI-1), and activities of antithrombin Ⅲ(AT-Ⅲ)and von Willebrand factor(vWF).Results Compared with groupⅠ , the vWF activity and PAI-1 concentration at T2 , concentrations of Fib, F1+2, PAI-1 and activity of vWF at T3 and concentrations of Fib and F1+2 at T4 were significantly increased, while the AT-IE activity at T3 was significantly decreased in group Ⅲ(P＜0.05) .Conclusion When the duration of pneumoperitoneum is short, no obvious changes in the blood coagulation, fibrinolysis and endothelial damage are observed postoperatively in patients undergoing laparoscopic cholecystectomy, and along with the prolongation of the duration of pneumoperitoneum, increased blood coagulation, reduced fibrinolysisand aggravated endothelial damage are observed postoperatively.     

The effect of burn wound size on hemostasis: a correlation of the hemostatic changes to the clinical state.

The effect of burn wound size on the activation of fibrinolysis, coagulation, and contact factors was analyzed in 60 thermal injury patients. Blood samples from 47 male patients and 13 female patients, (average age 37 years; range 1.5-70 years) were collected within the first 36 hours and at 5-7 days following injury. The patient population was categorized by percentage of burn (second degree and/or third degree): less than 20%, n = 22; 20%-40%, n = 18; greater than 40%, n = 20. The average percentage of burn was 32% (range, 4%-95%). The mechanism of injury was by flame (25), explosion and flame (19), scald (12), electric (3), or chemicals (1). An associated inhalation injury was present in 12 patients. The overall mortality rate was 13% (8). Sepsis or serious infection occurred in 23% (14) of the patients. On admission, 83% of the patients had normal prothrombin times (PT) and activated partial thromboplastin times (APTT). However, specific hemostatic variables showed marked changes. Admission hemostatic markers that correlated with the severity of injury were: tissue-plasminogen activator (tPA), plasminogen activator inhibitor (PAI), D-dimer (D-di), plasminogen (Plg), proteins C and S (PrC and PrS), antithrombin III (ATIII), thrombin-antithrombin complex (TAT), kallikrein (Kal:c), kinin (Kin), C1 esterase inhibitor (C1Inh), and factor VII clotting and antigen (FVII:c, FVII:ag). These data suggest that during the early course following burn injury, thrombogenicity is increased (TAT increases) because of a decrease in ATIII, PrC, and PrS; and fibrinolysis activation (D-di increases) occurs via an increase in tPA with a p value increase in PAI.(ABSTRACT TRUNCATED AT 250 WORDS)     

Haemostasis in Patients with Behçet''s Disease

Aim to determine whether Behçet's disease affects haemostatic function.Setting University Hospital, Turkey. Patients one hundred and twenty-seven consecutive patients with Behçet's disease, 34 of whom with a history of vascular involvement. Methods prothrombin fragment 1+2 tissue plasminogen activator, protein S and C, antithrombin, fibrinogen, von Willebrand factor, thrombomodulin and prothrombin time (PT) were measured in patient plasma. Results soluble thrombomodulin was significantly lower and von Willebrand factor (vWF) and tissue plasminogen activator (tPA) significantly higher in Behçet's patients. Patients with vascular involvement showed the highest levels of vWF and tPA. There was no activation of coagulation, not even in patients with an active disease at the time of sampling. Conclusion there were indirect signs of endothelial activity or damage, particularly in patients with vascular involvement. Coagulation was not activated.     

Activation of coagulation and fibrinolysis in open and laparoscopic cholecystectomy

Background: Activation of coagulation and fibrinolysis occurs as a stress response to surgery and may predispose the patient to thromboembolic complications. Other components of the surgical stress response (cytokine release, neurohumoral response, etc.) have been shown to differ between laparoscopic and open cholecystectomy, and the aim of this study was to investigate the effects of laparoscopic and open surgery on the coagulation and fibrinolytic pathways. Methods: Fourteen patients undergoing laparoscopic cholecystectomy and 12 patients undergoing open cholecystectomy had blood taken in the perioperative period for fibrinopeptide A (FPA) prothrombin fragment F1.2, antithrombin 3, tissue plasminogen activator (tPA) and its fast-acting inhibitor plasminogen activator inhibitor-1 (PAI-1 antigen and activity), and the euglobulin clot lysis time (ECLT). Results: The only significant differences between the two groups occurred 6 h after surgery when the ECLT was longer (p < 0.005; Mann Whitney), and PAI-1 antigen and activity were higher (p < 0.01 and p < 0.001, respectively; Mann Whitney) after open cholecystectomy than laparoscopic cholecystectomy. Conclusions: Other changes in fibrinolysis and coagulation were similar for open and laparoscopic cholecystectomy. With respect to hemostasis, laparoscopic cholecystectomy does not increase the risk of thromboembolic complications compared to the conventional procedure.     

Elevated resistin is related to inflammation and residual renal function in haemodialysed patients

AIM: Resistin is an adipocytokine that recently generated much interest. Because of the fact that inflammation, endothelial cell damage or injury is invariably associated with such clinical conditions as thrombosis, atherosclerosis and their major clinical consequences, that is, cardiovascular disease and resistin play a role in linking inflammation and cardiovascular disease, the aim of the study was to assess resistin in correlation with markers of inflammation, endothelial cell injury and residual renal function in haemodialysed (HD) patients. METHODS: We assessed resistin, markers of coagulation: thrombin-antithrombin complexes (TAT), prothrombin fragments 1+2; fibrinolysis: tPA, plasminogen activator inhibitor type 1, plasmin-antiplasmin complexes (PAP); endothelial function/injury: von Willebrand factor (vWF), thrombomodulin, intracellular adhesion molecule (ICAM); inflammation: high sensitivity C-reactive protein (hsCRP), tumour necrosis factor alpha and interleukin-6 (IL-6). RESULTS: Healthy volunteers and HD patients did not differ significantly regarding age, leucocyte count, serum iron, aspartate and alanine aminotransferases activities, calcium, cholesterol, tPA concentration. Triglycerides, CRP (assessed by high sensitivity method), phosphate, urea, creatinine, IL-6, tumour necrosis factor alpha, vWF, prothrombin fragments 1+2, TAT, PAP, thrombomodulin, ICAM, plasminogen activator inhibitor type 1 and resistin, were elevated in HD patients when compared with the control group. Serum albumin, total protein, haemoglobin and haematocrit were significantly lower in HD patients when compared with the control group. In HD patients with hsCRP 0e; 6 mg/L, resistin, IL-6, vWF and F1+2 were significantly higher, whereas tPA was significantly lower than in patients with hsCRP<6 mg/L. Moreover, HD patients with residual renal function have significantly lower resistin when compared with patients without it. Resistin was significantly higher in diabetics. In HD patients, resistin correlated significantly, in univariate analysis, with calcium, phosphate, PTH, TIBC, vWF residual renal function, urea, hsCRP, IL-6 and tended to correlate with tPA and ferritin. In the healthy volunteers, resistin was related to IL-6 and hsCRP. In multiple regression analysis, resistin was independently related to hsCRP, IL-6, residual renal function in HD patients. CONCLUSION: Elevated resistin related to markers of inflammation may represent a novel link between inflammation and adipocytokines in HD patients. Impaired renal function and inflammation are responsible for elevated resistin in HD patients.     

Effect of shear stress on the expression of coagulation and fibrinolytic factors in both smooth muscle and endothelial cells in a co-culture model

Blood vessels are subjected to forces due to the flow. Endothelial cells (EC) are recipients, cross-talk with smooth muscle cells (SMC), and regulate physiology. It was hypothesized that both EC and SMC respond to shear stress, which alters the expression of factors in coagulation and fibrinolysis. METHODS: A co-culture of human saphenous vein EC (HSVEC) and human saphenous vein SMC (HSVSMC) was exposed to shear, following which the cells were separated. Gene expression of tissue factor, thrombomodulin (TM), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) were analyzed with real-time RT-PCR. Protein expression was studied with ELISA. In HSVEC, the expression of PAI-1 (x2.1), tPA (x1.8), uPA (x1.6), tissue factor (x2.5) and TM (x1.9) was upregulated after 4 h of shear compared to controls. After 24 h of shear, expression was still upregulated in tPA (x2.3) and TM (x1.6). In HSVSMC, change in expression of PAI-1 (x2.1) was present after 4 h and in uPA (x2.1), and TM (x0.4) after 24 h. Both HSVEC and HSVSMC responded to shear, which led to altered expression of coagulation and fibrinolytic factors. This indicates that SMC, and interactions between EC and SMC, are more important in the regulation of vascular wall hemostasis than earlier studies have reported.     

A preliminary study on the effects of exercising to maximum walking distance on platelet and endothelial function in patients with intermittent claudication.

BACKGROUND: Platelet and endothelial activation has been shown to be increased in patients with intermittent claudication (IC). Recent studies have suggested that exercise may induce further platelet activation. The aims of this study were to investigate the effect of exercising to maximum walking distance on platelet and endothelial function in patients with intermittent claudication who were receiving statin and aspirin therapy compared with age matched healthy controls. METHODS: Platelet aggregation through COX-mediated and thrombin receptor activator peptide (TRAP)-stimulated GPIIb/IIIa pathways was measured by the Ultegra point of care system in 20 patients with IC on aspirin and 20 healthy volunteers before, immediately and 1h after exercising to treadmill maximal walking distance (MWD). Soluble P-selectin, vWF and sICAM were measured using an enzyme linked immuno-sorbent assay technique. RESULTS: Baseline platelet aggregation was significantly reduced in patients with IC compared to volunteers (p<0.05). In patients, exercising to MWD significantly reduced platelet aggregation (COX, median -5% [range -24 to 13%]; p = 0.02; GPIIIa/IIb, median -13% [range -72 to 33%]; p = 0.02) immediately post-exercise which returned to baseline values at 1 h. There was no change in the healthy volunteers following the same median duration of exercise. Baseline sP-selectin levels were higher in the patients with IC compared to the healthy volunteers [Median values (interquartile range), 42.72 (33.28-54.24) versus 29.16 (24.40-34.10), p = 0.0003] but there were no differences in vWF levels. Both sP-selectin and vWF levels increased significantly in the control and patient group following exercise (p<0.005). sICAM were higher at baseline in the patients with IC but were unchanged following exercise [Median values (interquartile range),560.9 (405.5-739.4) versus 467.0 (325.7-643.4), p<0.05]. CONCLUSION: This study is the first to show that platelet aggregation is reduced immediately following treadmill exercise to maximum walking distance in patients with IC despite a rise in sP-selectin and vWF, suggesting endothelial activation. The inhibition of platelet aggregation after exercise in subjects on antiplatelet and statin therapy suggests that exercise is unlikely to exacerbate platelet thrombus formation in patients with IC.     

Effects of L-Carnitine supplement on plasma coagulation and anticoagulation factors in hemodialysis patients

Background: Hypercoagulability is an important risk factor for thrombosis and its complications in hemodialysis patients. This study was designed to investigate the effects of l-carnitine supplement on plasma coagulation and anticoagulation factors in hemodialysis patients. Methods: Thirty-six hemodialysis patients were randomly assigned to either a carnitine or a placebo group. Patients in the carnitine group received 1000 mg/day oral l-carnitine for 12 weeks, whereas patients in the placebo group received a corresponding placebo. At baseline and the end of week 12, 5 mL blood was collected after a 12- to 14-hour fast and plasma fibrinogen concentration, activity of plasma protein C, coagulation factors V, VII, IX, and serum concentrations of tissue plasminogen activator (tPA), plasminogen activator inhibitor type-1 (PAI-1), free carnitine, and C-reactive protein (CRP) were measured. Results: In the carnitine group, mean serum free carnitine concentration increased significantly to 150% of baseline (p < 0.001), whereas plasma fibrinogen and serum CRP had 98 mg/dL (p < 0.01) and 41% (p < 0.01) significant decreases, respectively, at the end of week 12 compared with baseline. The reductions were significant compared with the placebo group (p < 0.05). No significant differences were observed between the two groups with regard to mean changes of the activity of plasma protein C, coagulation factors V, VII, IX, and serum PAI-1 to tPA ratio. Conclusion: l-Carnitine supplement reduces serum CRP, a marker of systemic inflammation, and plasma fibrinogen, an inflammation-related coagulation factor, in hemodialysis patients. Therefore, l-carnitine may play an effective role in preventing cardiovascular diseases in these patients.     

Intragraft coagulation events and delayed graft function in clinical renal transplantation

BACKGROUND: Cold preservation, reperfusion damage, immunosuppressive drugs, and uremia-induced acquired thrombophilias increase the risk of thrombotic complications in renal transplantation. Intragraft fibrin deposition may be associated with delayed graft function. METHODS: We studied coagulation and fibrinolysis in 45 patients of a larger trial in renal transplantation: perioperative antithymocyte globulin (group A, n=15), perioperative basiliximab (group B, n=16), and conventional triple therapy (group C, n=14). Blood samples for prothrombin fragment F1+2, plasminogen activator inhibitor (PAI)-1, d-dimer, tPA antigen, tPA activity, and platelet counts were obtained simultaneously at 1 and 5 min after reperfusion from iliac artery and graft vein for calculation of transrenal changes. Because antithymocyte globulin activates coagulation and fibrinolysis, group A was analyzed separately. Groups B and C were pooled (group BC). RESULTS: In group BC, transrenal D-dimer release occurred at 1 min, tPA-antigen release at 1 and 5 min, and transrenal PAI-1 uptake at 5 min postreperfusion. tPA activity increased marginally only at 1 min. High graft tPA-antigen release at 5 min and D-dimer release at 1 min were associated with delayed graft function. In group A, transrenal tPA-antigen release occurred at 1 and 5 min and D-dimer release at 1 min. There were no transrenal F1+2 changes in either group. CONCLUSION: Although graft PAI-1 uptake inhibits tPA activity, graft releases D-dimer at early reperfusion without concomitant F1+2 release. Data suggest thrombin and fibrin formation already before cold preservation during donor care and organ retrieval. This fibrin deposition increases risk of delayed graft function.     

Activation of coagulation and fibrinolytic systems in patients with CLI is not normalized after surgical revascularisation.

OBJECTIVE: To study the activation of coagulation and fibrinolysis before, during and after surgical revascularisation in patients with critical limb ischemia (CLI). DESIGN: Prospective clinical study. MATERIALS AND METHODS: Forty patients with CLI underwent femoro-popliteal or femoro-distal reconstruction and were compared to a control-group. Measurements of prothrombin-fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) assessed activation of coagulation. Fibrinolysis was determined by tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and fibrin degradation product (D-dimer). The inflammatory mediators: Interleukin 2 receptor (IL-2-rec), Interleukin 6 (IL-6), Interleukin 10 (IL-10) and Monocyte chemoattractant protein 1 (MCP-1) was also analysed. RESULTS: Patients (in 35 of the 40 reconstruction was possible) were operated upon using either vein (n=23) or ePTFE (n=12) grafts. Patients with CLI had a preoperative prothrombotic state as indicated by high TAT-levels and also ongoing fibrinolysis with high levels of t-PA and D-dimer. After reperfusion an ongoing prothrombotic state for the first week was demonstrated. A significant as well as defective fibrinolysis was also seen with increased levels of tPA and D-dimer unopposed by PAI-1 after one week and also after 30 days. Increased levels of inflammatory mediators IL-6, IL-10 and MCP-1 was observed after reperfusion and normalised after 30 days. CONCLUSION: This study demonstrates significant disturbances of both the coagulation and fibrinolytic systems before, during and after revascularisation for CLI. This was accompanied by release of inflammatory mediators. A prothrombotic state and increased fibrinolysis were evident also 30 days after successful revascularisation.     

Progressive intermittent claudication is associated with impaired fibrinolysis

Purpose: Acute complications of atherosclerosis such as stroke and myocardial infarction are caused by thrombosis and may be associated with impaired fibrinolytic activity. The current study was performed to determine whether peripheral arterial disease (PAD) and its progression are also associated with impaired fibrinolysis, by measurement of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1). Methods: The study group consisted of 80 men with a mean age of 69 years. This included 18 patients with mild intermittent claudication (MC, pain-free walking distance ≥200 meters) and 51 patients with severe claudication (SC, walking distance <200 meters). Eleven age- and sex-matched patients without PAD served as controls. All patients had measurements of serum tPA antigen using an enzyme-linked immunoadsorbent assay. Serum levels of tPA and PAI-1 activity were assayed with an amidolytic method. Mean ± SEM levels of the enzyme levels in patients with progressively more severe PAD were compared with normal controls. Results: Serum PAI-1 activity levels were significantly elevated in both PAD groups compared with normal controls (p < 0.02). There were no significant differences in the PAI-1 activity levels in groups with worsening degrees of PAD. There was a significant decrease in tPA activity levels in patients with SC (p = 0.01) relative to those with MC and the normal subjects. There was also a significant increase in tPA antigen level in the patients with SC compared with those with MC and the control subjects, as well as a significant inverse correlation between tPA antigen levels and pain-free walking time in patients with claudication (p = 0.001). Conclusions: All patients with PAD in this study had significant reductions in endogenous fibrinolytic activity. Patients with SC had more impaired fibrinolytic activity than those with MC and the control subjects, suggesting that the progression to more severe levels of PAD may be associated with worsening endogenous fibrinolysis. (J Vasc Surg 1998;27:645-50.)     

Peritoneal fibrinolytic activity in peritonitis

BACKGROUND: Peritonitis may cause a reduction in abdominal fibrinolytic activity. The reduced local fibrinolysis seems to be an important process in the subsequent development of adhesion formation. The aim of the study was to evaluate peritoneal fibrinolytic capacity in inflamed and normal peritoneum. METHODS: Peritoneal biopsy specimens were taken at the beginning of operation from 15 patients with peritonitis and 10 patients who underwent elective operation. Levels of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor (PAI) type 1 (PAI-1) and type 2 (PAI-2), and tPA/PAI complex in tissue extracts were determinated by commercially available enzyme-linked immunosorbent assay kits. RESULTS: tPA was significantly reduced in peritonitis compared with normal peritoneum (P <0.001), whereas it was found that the levels of PAI-1, PAI-2, uPA, and tPA/PAI complex in peritonitis were significantly higher than those in normal controls. CONCLUSIONS: Plasminogen activator activity was significantly reduced in peritoneal biopsy samples from patients with peritonitis compared with those from patients without peritonitis.