Current status of thrombolysis for peripheral arterial occlusive disease

Fibrinolytic and ACE Inhibitory Activity of Nattokinase Extracted from Bacillus subtilis VITMS 2: A Strain Isolated from Fermented Milk of Vigna unguiculata

The current research work aims at optimization, production, purification and evaluation of fibrinolytic extracellular protease from Bacillus subtilis VITMS2 isolated from fermented milk of Vigna unguiculata. The optimal production was achieved at 4.0% inoculum, pH7.0, 30 °C with (1% w/v) sucrose, (2% w/v) soya bean meal and (2% w/v) malt extract and 10 mM of CaCl_2, MgSO_4, Na₂HPO₄ and K₂HPO₄. The clear cell-free supernatant was purified using conventional ammonium sulphate salt fractionation (75%), ultrafiltration, ion-exchange (DEAE Sepharose FF) and gel filtration (Sephadex G-50). The molecular mass was determined to be 29 kDa using SDS-PAGE analysis. The purified enzyme showed strong fibrinolytic activity with a specific activity of 2418.85 U/mg and has a yield of 12.01%. The enzyme was highly stable up to 60 °C and a pH range of 10.0 until 72 h of incubation. The purified enzyme showed 97.4% in vitro thrombolytic activity. The K_m and V_max values of the enzyme was determined to be 0.0114 mM and 147.8 µmol min^-1 using the chromogenic substrate S-7388. IC₅₀ of ace inhibition was assessed to be 0.06 mg/mL suggesting anti-hypertensive property of the fibrinolytic enzyme. The above-obtained ace-inhibition results was supported by in silico molecular docking studies which revealed better binding affinity of nattokinase with a HADDOCK score of - 22.0 ± 8.5 confirms affinity towards angiotensin converting enzyme.

The effects of hydrogen sulfide on platelet-leukocyte aggregation and microvascular thrombolysis

The volatile transmitter hydrogen sulfide (H₂S) is known for its various functions in vascular biology. This study evaluates the effect of the H₂S-donor GYY4137 (GYY) on thrombus stability and microvascular thrombolysis. Human whole blood served for all in vitro studies and was analyzed in a resting state, after stimulation with thrombin-receptor activating peptide (TRAP) and after incubation with 10 or 30 mM GYY or its vehicle DMSO following TRAP-activation, respectively. As a marker for thrombus stability, platelet-leukocyte aggregation was assessed using flow cytometry after staining of human whole blood against CD62P and CD45, respectively. Furthermore, morphology and quantity of platelet-leukocyte aggregation were studied by means of scanning electron microscopy (scanning EM). Therefore, platelets were stained for CD62P followed by immuno gold labeling. In vivo, the dorsal skinfold chamber preparation was performed for light/dye induction of thrombi in arterioles and venules using intravital fluorescence microscopy. Thrombolysis was assessed 10 and 22 h after thrombus induction and treatment with the vehicle, GYY, or recombinant tissue plasminogen activator (rtPA). Flow cytometry revealed an increase of CD62P/CD45 positive aggregates after TRAP stimulation of human whole blood, which was significantly reduced by preincubation with 30 mM GYY. Scanning EM additionally showed a reduced platelet-leukocyte aggregation and a decreased leukocyte count within the aggregates after preincubation with GYY compared to TRAP stimulation alone. Further on, morphological signs of platelet activation were found markedly reduced upon treatment with GYY. In mice, both GYY and rtPA significantly accelerated arteriolar and venular thrombolysis compared to the vehicle control. In conclusion, GYY impairs thrombus stability by reducing platelet-leukocyte aggregation and thereby facilitates endogenous thrombolysis.

Peripheral Arterial Embolism: Prevalence, Outcome, and the Role of Echocardiography in Management

The aims of this study were to review the prevalence and outcome of all surgically treated upper and lower limb emboli presenting to one vascular unit in the last 3 years and to compare transthoracic with transesophageal echocardiography for defining the source of the embolus. All patients who underwent surgical embolectomy for acute limb ischemia from January 2001 to June 2004 were reviewed. Transthoracic and transesophageal echocardiography were carried out on a subset of consecutive unselected patients. Forty-two patients, with a mean age of 80 years, underwent surgical embolectomy from January 2001 to June 2004 (M/F 1:1.8): 27 for lower limb ischemia and 15 for upper limb ischemia. Two thirds of these patients were found to be in atrial fibrillation at presentation (n=28), of whom less than a third were receiving anticoagulants or antiplatelet agents (n=8). The mean hospital stay was 15 days with 36 patients (86%) being fully anticoagulated before discharge from hospital. The 30-day mortality rate was 11% (n=3/27) with 5 patients requiring fasciotomies (12%) and 3 patients requiring an amputation of the lower limb (11%). Postoperatively, 34 patients (81%) had transthoracic echocardiography (TTE), which demonstrated a source or potential source for thrombus in 19 (56%). Fifteen patients (36%) had transesophageal echocardiography (TEE), which changed the subsequent management in 3 patients. All patients in whom TEE altered clinical management would have required this investigation if standard clinical guidelines were followed. TEE did not identify any additional patients with cardiac embolic sources that were not detected by TTE. Arterial limb emboli are still prevalent, but limb salvage and mortality rates appear to be improving. Despite clear guidelines on anticoagulation for patients in atrial fibrillation, many are not receiving appropriate treatment. Transthoracic echocardiography is a good screening tool for detecting a potential cardiac source for peripheral embolism, with transesophageal echocardiography being reserved for specific indications.

Urokinase Thrombolysis in Acute-on-Chronic Vascular Occlusion of Lower Limb

Between January 2000 and June 2003, 70 patients (63 men and 7 women) with acute-on-chronic lower limb vascular occlusion underwent thrombolysis with 1 million units of urokinase. Forty-eight patients had unilateral and 22 had bilateral involvement; 9 had gangrenous changes. The mean age was 47 ± 9 years, 73% were smokers, and 13% had diabetes. The definition of a good response was either return of distal pulses or a warm limb and relief of pain at rest. Fifty-three (76%) patients (including 5 with gangrenous changes) had symptomatic improvement with thrombolysis (group 1), and 17 (24%) did not respond (group 2). All 70 patients (including 7 who later required amputation) underwent surgical intervention with a polytetrafluoroethylene interposition graft or arterioplasty. A good response to surgical treatment was found in significantly more patients (49/53, 92%) in group 1 compared to group 2 (7/17, 41%). Claudication distance after 6 months of follow-up improved in a significantly higher percentage of patients in group 1 (85%) than group 2 (38%). Preoperative thrombolysis improved the outcome and predicted the result of arterial surgery.

Purification and characterization of mutant miniPlasmin for thrombolytic therapy

BACKGROUND

Previous animal studies by us and others have indicated that catheter-administered plasmin or its des-kringle derivatives may be more appropriate alternatives to plasminogen activators for treating thrombolytic diseases, since it has a very short serum half-life and therefore does not result in hemorrhaging. We have previously produced recombinant miniPlasmin (mPlasmin) that was proven suitable for treating peripheral arterial occlusion in animal models. However, our previous results showed that non-specific cleavage at position K698 of mPlasmin during activation hindered the further development of this promising therapeutic candidate. In order to minimize or eliminate the non-specific cleavage problem, we performed saturation mutagenesis at the K698 position to develop a mutant form of mPlasmin for thrombolytic therapy.

METHODS

We changed K698 to 16 other amino acids, with preferred E. coli codons. Each of these mutants were expressed in E. coli as inclusion bodies and then refolded, purified, and subsequently characterized by detailed kinetic assays/experiments/studies which identified highly active mutants devoid of non-specific cleavage.

RESULTS

Activation studies indicated that at those conditions in which the wild type enzyme is cut at the non-specific position K698, the active mutants can be activated without being cleaved at this position.

CONCLUSIONS

From the above results, we selected two mutants, K698Q and K698N, as our lead candidates for further thrombolytic drug developments. The selected mutants are potentially better therapeutic candidates for thrombolytic therapy.

ADAMTS13 exerts a thrombolytic effect in microcirculation

Recombinant tissue plasminogen activator (r-tPA) is the drug of choice for thrombolysis, but it is associated with a significant risk of bleeding and is not always successful. By cleaving von Willebrand factor (VWF), the metalloprotease ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type I repeats-13) down-regulates thrombus formation in injured vessels. We investigated whether recombinant ADAMTS13 (r-ADAMTS13) induces thrombolysis in vivo in mice. Thrombosis was produced by ferric chloride-induced (FeCl(3)) injury in the venules of a dorsal skinfold chamber. Phosphate-buffered saline (PBS, vehicle), r-tPA or r-ADAMTS13, supplemented with hirudin (to stop on-going thrombin generation), was directly applied onto the occluded vessel, and thrombus dissolution was evaluated by intravital microscopy. The incidence of blood flow restoration significantly increased 30 minutes (min) after r-ADAMTS13 vs. PBS treatment (60% vs. 0%, p<0.05) and 60 min after r-tPA treatment (75% vs. 17%, p<0.05). Both r-tPA and r-ADAMTS13 significantly reduced thrombus size 60 min after their superfusion (53.2% and 62.3% of the initial thrombus size, p<0.05 and p<0.01, respectively). Bleeding occurred in all r-tPA-treated chambers, while it was absent in mice treated with r-ADAMTS13 or PBS. We observed that, similar to r-tPA, r-ADAMTS13 can dissolve occlusive thrombi induced by FeCl(3) injury in venules. In contrast to r-tPA, the in vivo thrombolytic effect of ADAMTS13 was not associated with any signs of haemorrhage. ADAMTS13 could represent a new therapeutic option for thrombolysis.

The mouse dorsal skinfold chamber as a model for the study of thrombolysis by intravital microscopy

Although intravital microscopy models of thrombosis in mice have contributed to dissect the mechanisms of thrombus formation and stability, they have not been well adapted to study long-term evolution of occlusive thrombi. Here, we assessed the suitability of the dorsal skinfold chamber (DSC) for the study of thrombolysis and testing of thrombolytic agents by intravital microscopy. We show that induction of FeCl3-induced occlusive thrombosis is achievable in microvessels of DSCs, and that thrombi formed in DSCs can be visualised by intravital microscopy using brightfield transmitted light, or fluorescent staining of thrombus components such as fibrinogen, platelets, leukocytes, and von Willebrand factor. Direct application of control saline or recombinant tissue-plasminogen activator (rtPA) to FeCl3-produced thrombi in DSCs did not affect thrombus size or induce recanalisation. However, in the presence of hirudin, rtPA treatment caused a rapid dose-dependent lysis of occlusive thrombi, resulting in recanalisation within 1 hour after treatment. Skin haemorrhage originating from vessels located inside and outside the FeCl3-injured area was also observed in DSCs of rtPA-treated mice. We further show that rtPA-induced thrombolysis was enhanced in plasminogen activator inhibitor-1-deficient (PAI-1-/-) mice, and dropped considerably as the time between occlusion and treatment application increased. Together, our results show that by allowing visualization and measurement of thrombus lysis and potential bleeding complications of thrombolytic treatments, the DSC provides a model for studying endogenous fibrinolysis and for first-line screening of thrombolytic agents. Furthermore, using this system, we found that thrombin and clot aging impair the thrombolytic action of rtPA towards FeCl3-produced thrombi.

Purification and characterization of a novel anticoagulant and fibrinolytic enzyme produced by endophytic bacterium Paenibacillus polymyxa EJS-3

INTRODUCTION

Endophytes may become a new source of thrombolytic agents for thrombosis treatment.

MATERIALS AND METHODS

A novel fibrinolytic enzyme from Paenibacillus polymyxa EJS-3 (PPFE-I) was purified with ammonium sulfate precipitation, hydrophobic chromatography, ion exchange and gel filtration chromatography. The characterization of the enzyme was investigated by means of fibrinolysis plate, hydrolysis of fibrinogen and anticoagulant effect in vitro.

RESULTS

The fibrinolytic enzyme is purified to homogeneity with a purification of 14.5 fold and a recovery of 3.3%. The enzyme was shown to have a molecular mass of 63.3kDa by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The optimum temperature and pH value were 37°C and 7.5, respectively. Results from the fibrinolysis pattern showed that the enzyme rapidly hydrolyzed the Aα-chain of fibrinogen, followed by the Bβ-chains. It also hydrolyzed the γ-chains, but more slowly. It was activated by metal ions such as Zn(2+), Mg(2+), and Fe(2+), but inhibited by Ca(2+) and Cu(2+). Furthermore, PPFE-I activity was inhibited strongly by PMSF, and it was found to exhibit a higher specificity for the synthetic substrate N-succinyl-Ala-Ala-Pro-Phe-pNA for chymotrypsin, indicating that the enzyme is a chymotrypsin-like serine protease. Additionly, PPFE-I showed a significant anticoagulant effect in vitro.

CONCLUSION

The fibrinolytic enzyme PPFE-I from endophytic bacterium Paenibacillu polymyxa EJS-3 exhibits a profound fibrinolytic activity.

Treatment for peripheral arterial obstructive disease: An appraisal of the economic outcome of complications

OBJECTIVE

This study determined the average estimated total costs after treatment for peripheral arterial occlusive disease (PAOD) and evaluated the effect of postoperative complications and their consequences for the total costs.

METHODS

Cost data on all admissions involving treatment for PAOD from January 2007 until July 2007 were collected. A prospective analysis was made using the patient-related risk factor and comorbidity (Society for Vascular Surgery/International Society of Cardiovascular Surgeons) classification, primary and secondary treatment, and prospectively registered complications. At admission, patients without complications were placed in group A, and those with complications were in group B. Prospectively registered complications were divided into patient management (I), surgical technique (II), patient's disease (III), and outside surgical department (IV). The consequences of these were divided into minor complication, no long-term consequence (1A), additional medication or transfusion (1B), surgical reoperation (2A), prolonged hospital stay (2B), irreversible physical damage (3), and death (4). The main outcome measures were total costs of patients and costs per patient (PP), with or without the presence of complications, cost of complications and costs per complication (PC), and the costs of their consequences calculated in euros (euro).

RESULTS

Ninety patients (mean age, 71.4 years; 59% men) were included. Group B patients had a significantly higher American Society of Anesthesiologists (4) and Fontaine (3) classification and more secondary procedures. Total costs were euro 1,716,852: group A, euro 512,811 (PP euro 12,820); and group B, euro 1,204,042 (PP euro 24,081). The costs of the 115 complications were euro 568,500 (PC euro 4943). Split by the cause of the complication, costs were I, euro 95,924 (PC euro 2998); II, euro 163,137 (PC euro 8157); III, euro 289,578 (PC euro 5171); and IV, euro 19,861 (PC euro 2837). The increase of costs in group B was mainly caused by additional medication or transfusion (1B) euro 348,293 (61.3%), a surgical reoperation (2A) euro 118,054 (20.8%), or prolonged hospital stay (2B) euro 60,451 (10.6%). Patients who died caused 23% of the total costs.

CONCLUSION

Complications cause an increase of the average estimated total costs in the treatment for peripheral arterial occlusive disease and are responsible for 33% of these total costs. The most expensive complications were errors in surgical technique and patient's disease, resulting in surgical reoperation or additional medication, or both, or transfusion, the two most expensive consequences.

[Clinical and therapeutic characteristics of limb emboli]

INTRODUCTION

To treat an extremity embolus seems to be a simple and safe procedure. However, it is not exempt from potentially serious complications. We review our experience of treating acute peripheral arterial occlusion due to emboli.

PATIENTS AND METHOD

We retrospectively analyzed the data of 127 embolectomies performed during the last five years, in 120 extremities in 116 patients. The mean age of the patients was 80 years and 66% were female. All cases were presented as acute threatened limb ischemia grades IIA or IIB, and the mean evolution time was 27 hours. The patency, limb salvage and morbidity-mortality rates in the postoperative period and the salvage and survival rates in the follow-up were analyzed.

RESULTS

Of the embolectomies, 55% were femoral and 30% brachial. Although 90% of the cases improved, only 75% of them recovered distal pulses. In the postoperative period the patency, limb salvage, morbidity and mortality rates were 90%, 96%, 13% and 6.4%, respectively. The mean follow-up was 24 months. Up until this time, the patency and survival rates are 91% and 61%, respectively. The only factor related with an increase in the amputation rate was a clinical presentation, such as a threatened immediate ischemia. The factors related with an increase in survival rate were appropriate cardiological treatment and control, and long-term anticoagulation treatment.

CONCLUSIONS

Suffering an embolus of the extremities and its treatment causes considerable morbidity-mortality and limb amputation rates. The extremity salvage is associated with the clinical presentation at the time of the treatment. Long-term anticoagulation treatment and appropriate cardiological control increase the survival of these patients.

Prevalence of and risk factors for peripheral arterial disease in the patients with hypertension among Han Chinese

OBJECTIVES

Peripheral arterial disease (PAD) is associated with morbidity and mortality of coronary heart disease and stroke. Hypertension is an independent risk factor for peripheral arterial disease. However, the prevalence and risk factors of PAD in hypertensive patients have not been studied in China.

METHODS

In order to investigate the prevalence of PAD and its risk factors in China, a cross-sectional study was carried out. A total of 4716 patients with hypertension and 833 age-gender matched people without hypertension were recruited; age 40 to 75 years, from seven rural communities. PAD was defined as an ankle-brachial index (ABI) <or= 0.9 in either leg; hypertension was defined as systolic blood pressure >or=140 mm Hg, diastolic blood pressure >or=90 mm Hg, or history of antihypertensive drug use.

RESULTS

The prevalence of PAD is 8.7% (n = 408) in patients with hypertension (n = 4716), higher than in people without hypertension (5.0%, n = 833, P = .004). Hypertensive patients with PAD were older, (61 +/- 8.6 vs 58 +/- 8.6, P < .01), had more conventional cardiovascular risk factors including systolic blood pressure (170 +/- 22.6 vs 167 +/- 22.7, P < .01), pulse pressure (72 +/- 19.7 vs 68 +/- 18.9, P < .01), blood glucose (5.8 +/- 2.2 vs 5.6 +/- 1.7, P < .05), total cholesterol (5.7 +/- 1.3 vs 5.5 +/- 1.1, P < .05), and serum uric acid (355 +/- 98.0 vs 293 +/- 86.2, P < .05) than the hypertensive patients without PAD. After adjusting for gender, age, and other cardiovascular risk factors by using multiple logistical regression analysis, PAD was still associated with current smoking (odds ratio [OR] = 1.65, 95% confidence interval [CI] 1.18-2.29), history of stroke (OR = 1.50, 95% CI 1.12-2.00), serum uric acid (OR = 1.21, 95% CI 1.10-1.59), and total cholesterol (OR = 1.12, 95% CI 1.10-1.59).

CONCLUSION

This study reports, for the first time, the prevalence of PAD in Chinese patients with hypertension, which is quite different from that in westerners, and that PAD is independently associated with conventional cardiovascular risk factors.

GP IIb/IIIa Blockade During Peripheral Artery Interventions

The activation of the platelet GP IIb/IIIa receptor is the final and common pathway in platelet aggregation. By blocking this receptor, platelet aggregation can be inhibited independently of the stimulus prompted the targeting of this receptor. Several years ago, three drugs have been approved for coronary artery indications. Since that time, there is increasing evidence that GP IIb/IIIa receptor blockade might have also an important role in peripheral arterial intervention. This article summarizes the action and differences of GP Ilb/IIIa receptor inhibitors and its possible indication in peripheral arteries.

[Arterial thrombolysis in the lower extremity in vascular surgical practice]

The acute arterial thrombosis of the lower limb is dangerous not only for the limb, but it can cause life-threatening situation as well. That is why it is important to use different therapeutical modalities as the catheter guided intraarterial thrombolysis, which can reduce the surgical risks. All the drugs used for lysis now days are plasminogen activators. Due to the results of different studies the most appropriate drugs for optimal thrombolysis are the urokinase, the tissue-plasminogen activators and their recombinant forms. There are two major studies dealing with the effect of the different fibrinolytic drugs in comparison of the results of randomly operated patients. Both of these studies (STILE, TOPAS) determined a nearly same efficacy of both methods, operative or thrombolytic (approximately 70% amputation-free survival). Significant difference was observed in relation of occlusion of a native artery or a graft: better results could be obtained with surgery in case of arterial occlusion and conversely, it was in favor for thrombolysis if a graft was occluded. It must be noted that the thrombolysis has to be followed with endovascular or open surgical procedures in most of the cases. On the basis of our experiences and the data of literature we suggest after individual decision thrombolysis in case of graft occlusion, and surgery in case of arterial occlusion as first choice.

Purification and characterization of anticoagulant protein from the Tabanus,Tabanus bivittatus

Tabanus anticoagulant protein (TAP) was isolated from the whole body of the tabanus, Tabanus bivittatus, using three purification steps (ammonium sulfate fractionation, gel filtration on Bio-Gel P-60, and ion exchange chromatography on DEAE Sephadex gel). The purified TAP, with a molecular weight of 65 kDa, was assessed to be homogeneous by SDS-polyacrylamide gel electrophoresis, and an isoelectric point of 7.9 was determined by isoelectric focusing. The internal amino acid sequence of the purified protein was composed of Ser-Leu-Asn-Asn-Gln-Phe-Ala-Ser-Phe-Ile-Asp-Lys-Val-Arg. The protein was activated by Cu2+ and Zn2+, and the optimal conditions were found to be at pH 3-6 and 40-70 degrees C. Standard coagulation screen assays were used to determine thrombin time and activated partial thromboplastin time. Chromogenic substrate assays were performed for thrombin and factor Xa activity. TAP considerably prolonged human plasma clotting time, especially activated partial thromboplastin time in a dose-dependent manner; it showed potent and specific antithrombin activity in the chromogenic substrate assay. Specific anti-factor Xa activity in TAP was not detected. Overall, this result suggested that TAP has significant anticoagulant activity on blood coagulation system.

Purification and characterization of a serine protease (CPM-2) with fibrinolytic activity from the dung beetles

Catharsius protease-2 (CPM-2) was isolated from the body of dung beetles, Catharsius molossus, using a three step purification process (ammonium sulfate fractionation, gel filtration on Bio-Gel P-60, and affinity chromatography on DEAE Affi-Gel blue). The purified CPM-2, having a molecular weight of 24 kDa, was assessed homogeneously by SDS-polyacrylamide gel electrophoresis. The N-terminal amino acid sequence of CPM-2 was composed of X Val Gln Asp Phe Val Glu Glu Ile Leu. CPM-2 was inactivated by Cu2+ and Zn2+ and strongly inhibited by typical serine proteinase inhibitors such as TLCK, soybean trypsin inhibitor, aprotinin, benzamidine, and alpha1-antitrypsin. However, EDTA, EGTA, cysteine, beta-mercaptoethanol, E64, and elastatinal had little effect on enzyme activity. In addition, antiplasmin and antithrombin III were not sensitive to CPM-2. Based on the results of a fibrinolytic activity test, CPM-2 readily cleaved Aalpha- and Bbeta-chains of fibrinogen and fibrin, and gamma-chain of fibrinogen more slowly. The nonspecific action of the enzyme resulted in extensive hydrolysis, releasing a variety of fibrinopeptides of fibrinogen and fibrin. Polyclonal antibodies of CPM-2 were reactive to the native form of antigen. The ELISA was applied to detect quantities, in nanograms, of the antigen in CPM-2 protein.

Thrombolysis and mechanical thrombectomy for arterial disease

Thrombolytic therapy has been around for close to 30 years now,but its exact role in the treatment of acute and chronic arterial occlusive disease continues to be debated. Studies have produced varying and contradictory results. We are still not sure if thrombolysis has any true advantages over surgical thromboembolectomy,or which lytic agent is the best. Nonetheless, the technique still plays an important role in the treatment of arterial occlusions.

National Audit of Thrombolysis for Acute Leg Ischemia (NATALI): clinical factors associated with early outcome

OBJECTIVE

The National Audit of Thrombolysis for Acute Leg Ischemia (NATALI) database is a consecutive series of patients who underwent intra-arterial thrombolysis to treat acute leg ischemia in one of 11 centers in the United Kingdom. The purpose of the study was to analyze the factors associated with outcome after 30 days.

METHODS

The data were collected over 10 years on standard pro formas, and registration was completed at the end of 1999. Since then, data from each unit have been verified and missing data included when available. Univariate and multivariate analyses were performed, with the outcomes of amputation-free survival (AFS), amputation with survival, and death.

RESULTS

A total of 1133 thrombolytic events were included. Outcome results at 30 days for the entire group were AFS, 852 (75.2%); amputation, 141 (12.4%); and death, 140 (12.4%). Results for the entire group improved from the first half of the database, when AFS ranged from 65% to 75%, to almost 80% for the last few years of the study, although this was not statistically significant. Preintervention factors associated with lower AFS at multivariate analysis included diabetes (P =.002), increasing age (P <.001), short-duration ischemia (P =.027), Fontaine grade (P =.001), and ischemia with neurosensory deficit (P =.004). AFS was improved in patients receiving warfarin sodium at the time of the arterial occlusion (P =.04). Mortality was higher in women (P =.006) and in older patients (P <.001), and in patients with native vessel occlusion (P <.001), emboli (P =.02), or a history of ischemic heart disease (P <.001). Amputation risk was greatest in younger men (P <.001) and in patients with more severe ischemia (P =.02), graft occlusion (P <.001), or native vessel thrombotic occlusion (P =.02).

CONCLUSION

Experienced surgeons and radiologists can achieve an AFS of about 80% in selected patients with acute leg ischemia. Information from the NATALI database can be used in selection of an appropriate intervention in the individual patient.

A Model Incorporating Some of the Mechanical and Biochemical Factors Underlying Clot Formation and Dissolution in Flowing Blood

Multiple interacting mechanisms control the formation and dissolution of clots to maintain blood in a state of delicate balance. In addition to a myriad of biochemical reactions, rheological factors also play a crucial role in modulating the response of blood to external stimuli. To date, a comprehensive model for clot formation and dissolution, that takes into account the biochemical, medical and rheological factors, has not been put into place, the existing models emphasizing either one or the other of the factors. In this paper, after discussing the various biochemical, physiologic and rheological factors at some length, we develop a model for clot formation and dissolution that incorporates many of the relevant crucial factors that have a bearing on the problem. The model, though just a first step towards understanding a complex phenomenon, goes further than previous models in integrating the biochemical, physiologic and rheological factors that come into play.

Purification and characterization of a serine protease with fibrinolytic activity from the dung beetles, Catharsius molossus

Catharsius protease-1 (CPM-1) was isolated from the whole body of the dung beetles, Catharsius molossus, using three purification steps (ammonium sulfate fractionation, gel filtration on Bio-Gel P-60, and affinity chromatography on DEAE Affi-Gel Blue gel). The purified CPM-1 that has a molecular weight of 27 kDa was assessed homogeneous by SDS-polyacrylamide gel electrophoresis and an isoelectric point of 4.4 was determined by isoelectric focusing. N-terminal amino acid sequence of the protease was composed of Ile-Val-Gly-Gly-Gln-Ala-Val-Glu-Ile-Gly-Asp-Tyr-Pro-Ala-Gln. The enzyme was inactivated by Cu(2+) and Zn(2+) and strongly inhibited by typical serine proteinase inhibitors such as TLCK, soybean trypsin inhibitor, aprotinin, benzamidine and alpha-antitrypsin. However, EDTA, EGTA, cysteine, beta-mercaptoethanol, E64, chymostatin, elastatinal and TPCK did not/less affect activity. Also, antiplasmin and antithrombin III were not sensitive to CPM-1. On the basis of amidolytic activity test, CPM-1 preferably hydrolysed chromogenic protease substrates containing Arg or Lys residues of the P1 position at pH 7.0 and 37 degrees C. CPM-1 preferentially cleaved the oxidized B-chain of insulin between Arg(22) and Gly(23). CPM-1 readily digested Aalpha- and gamma-chains and more slowly Bbeta-chain of fibrinogen. The nonspecific action of the enzyme resulted in extensive hydrolysis, releasing a variety of fibrinopeptides of fibrinogen and fibrin. D-dimer concentration increased on incubation of cross-linked fibrin with CPM-1, indicating that the enzyme has a significant fibrinolytic activity.