Gain of function in the immune system caused by a ryanodine receptor 1 mutation

Mutations in RYR1, the gene encoding ryanodine receptor 1, are linked to a variety of neuromuscular disorders including malignant hyperthermia (MH), a pharmacogenetic hypermetabolic disease caused by dysregulation of Ca(2+) in skeletal muscle. RYR1 encodes a Ca(2+) channel that is predominantly expressed in skeletal muscle sarcoplasmic reticulum, where it is involved in releasing the Ca(2+) necessary for muscle contraction. Other tissues, however, including cells of the immune system, have been shown to express ryanodine receptor 1; in dendritic cells its activation leads to increased surface expression of major histocompatibility complex II molecules and provides synergistic signals leading to cell maturation. In the present study, we investigated the impact of an MH mutation on the immune system by studying the RYR1Y522S knock-in mouse. Our results show that there are subtle but significant differences both in resting 'non-challenged' mice as well as in mice treated with antigenic stimuli, in particular the knock-in mice: (i) have dendritic cells that are more efficient at stimulating T cell proliferation, (ii) have higher levels of natural IgG1 and IgE antibodies, and (iii) are faster and more efficient at mounting a specific immune response in the early phases of immunization. We suggest that some gain-of-function MH-linked RYR1 mutations might offer selective immune advantages to their carriers. Furthermore, our results raise the intriguing possibility that pharmacological activation of RyR1 might be exploited for the development of new classes of vaccines and adjuvants.

Variability between laboratories performing coagulation tests with identical platforms: a nationwide evaluation study

Background

While the assessment of analytical precision within medical laboratories has received much attention in scientific enquiry, the degree of as well as the sources causing variation between them remains incompletely understood. In this study, we quantified the variance components when performing coagulation tests with identical analytical platforms in different laboratories and computed intraclass correlations coefficients (ICC) for each coagulation test.

Methods

Data from eight laboratories measuring fibrinogen twice in twenty healthy subjects with one out of 3 different platforms and single measurements of prothrombin time (PT), and coagulation factors II, V, VII, VIII, IX, X, XI and XIII were analysed. By platform, the variance components of (i) the subjects, (ii) the laboratory and the technician and (iii) the total variance were obtained for fibrinogen as well as (i) and (iii) for the remaining factors using ANOVA.

Results

The variability for fibrinogen measurements within a laboratory ranged from 0.02 to 0.04, the variability between laboratories ranged from 0.006 to 0.097. The ICC for fibrinogen ranged from 0.37 to 0.66 and from 0.19 to 0.80 for PT between the platforms. For the remaining factors the ICC’s ranged from 0.04 (FII) to 0.93 (FVIII).

Conclusions

Variance components that could be attributed to technicians or laboratory procedures were substantial, led to disappointingly low intraclass correlation coefficients for several factors and were pronounced for some of the platforms. Our findings call for sustained efforts to raise the level of standardization of structures and procedures involved in the quantification of coagulation factors.

A genome-wide association study of resistance to HIV infection in highly exposed uninfected individuals with hemophilia A

Human genetic variation contributes to differences in susceptibility to HIV-1 infection. To search for novel host resistance factors, we performed a genome-wide association study (GWAS) in hemophilia patients highly exposed to potentially contaminated factor VIII infusions. Individuals with hemophilia A and a documented history of factor VIII infusions before the introduction of viral inactivation procedures (1979-1984) were recruited from 36 hemophilia treatment centers (HTCs), and their genome-wide genetic variants were compared with those from matched HIV-infected individuals. Homozygous carriers of known CCR5 resistance mutations were excluded. Single nucleotide polymorphisms (SNPs) and inferred copy number variants (CNVs) were tested using logistic regression. In addition, we performed a pathway enrichment analysis, a heritability analysis, and a search for epistatic interactions with CCR5 Δ32 heterozygosity. A total of 560 HIV-uninfected cases were recruited: 36 (6.4%) were homozygous for CCR5 Δ32 or m303. After quality control and SNP imputation, we tested 1 081 435 SNPs and 3686 CNVs for association with HIV-1 serostatus in 431 cases and 765 HIV-infected controls. No SNP or CNV reached genome-wide significance. The additional analyses did not reveal any strong genetic effect. Highly exposed, yet uninfected hemophiliacs form an ideal study group to investigate host resistance factors. Using a genome-wide approach, we did not detect any significant associations between SNPs and HIV-1 susceptibility, indicating that common genetic variants of major effect are unlikely to explain the observed resistance phenotype in this population.

[Screening for thrombophilia 2011: who are the candidates?]

Heritable thrombophilia as a concept in hemostasis has been continuously discovered parallel to the knowledge on physiology of bleeding disorders. Since the 1980s it has become increasingly popular to search for thrombophilia in patients with thromboembolism and their relatives. Although initially no direct evidence existed for any advantage for the patients, successive clinical studies have helped to understand the risk of thrombosis and to stratify the patients in relation to the thrombophilic defect. In the meantime national and international guidelines have been published, suggesting which candidates should be examined and what tests should be performed. In the present paper we summarise and explain the rationale of these guidelines from the european point of view.

Impact of loss of high-molecular-weight von Willebrand factor multimers on blood loss after aortic valve replacement

BACKGROUND

Severe aortic stenosis is associated with loss of the largest von Willebrand factor (vWF) multimers, which could affect primary haemostasis. We hypothesized that the altered multimer structure with the loss of the largest multimers increases postoperative bleeding in patients undergoing aortic valve replacement.

METHODS

We prospectively included 60 subjects with severe aortic stenosis. Before and after aortic valve replacement, vWF antigen, activity, and multimer structure were determined and platelet function was measured by impedance aggregometry. Blood loss from mediastinal drainage and the use of blood and haemostatic products were evaluated perioperatively.

RESULTS

Before operation, the altered multimer structure was present in 48 subjects (80%). Baseline characteristics and laboratory data were similar in all subjects. The median blood loss after 6 h was 250 (105-400) and 145 (85-240) ml in the groups with the altered and normal multimer structures, respectively (P=0.182). After 24 h, the cumulative loss was 495 (270-650) and 375 (310-600) ml in the groups with the altered and normal multimer structures, respectively (P=0.713). Multivariable analysis revealed no significant influence of multimer structure and platelet function on bleeding volumes after 6 and 24 h. After 24 h, there was no obvious difference in vWF antigen, activity, and multimer structure in subjects with and without the altered multimer structure before operation or in subjects with and without perioperative plasma transfusion.

CONCLUSIONS

The altered vWF multimer structure before operation was not associated with increased bleeding after aortic valve replacement. Our findings might be explained by perioperative release of vWF and rapid recovery of the largest vWF multimers.

Late effects on haemostasis after haematopoietic stem cell transplantation

Allogeneic and autologous hematopoietic stem cell transplantations are important therapeutic options for patients with hematologic disorders. Hemostatic complications are frequent after hematopoietic stem cell transplantation with a considerable morbidity and mortality. The incidence of bleedings and thrombosis is highest in the first few weeks after transplantation, but may also occur later. However, beyond the first year of transplantation only limited data are available. In long-term survivors the risk for premature atherosclerosis increases over time after allogeneic hematopoietic stem cell transplantation and it is higher than in the age-adjusted general population and in recipients of autologous transplantation.

Rivaroxaban: Quantification by anti-FXa assay and influence on coagulation tests: a study in 9 Swiss laboratories

INTRODUCTION

Rivaroxaban (RXA) is licensed for prophylaxis of venous thromboembolism after major orthopaedic surgery of the lower limbs. Currently, no test to quantify RXA in plasma has been validated in an inter-laboratory setting. Our study had three aims: to assess i) the feasibility of RXA quantification with a commercial anti-FXa assay, ii) its accuracy and precision in an inter-laboratory setting, and iii) the influence of 10mg of RXA on routine coagulation tests.

METHODS

The same chromogenic anti-FXa assay (Hyphen BioMed) was used in all participating laboratories. RXA calibrators and sets of blinded probes (aim ii.) were prepared in vitro by spiking normal plasma. The precise RXA content was assessed by high-pressure liquid chromatography-tandem mass spectrometry. For ex-vivo studies (aim iii), plasma samples from 20 healthy volunteers taken before and 2 - 3hours after ingestion of 10mg of RXA were analyzed by participating laboratories.

RESULTS

RXA can be assayed chromogenically. Among the participating laboratories, the mean accuracy and the mean coefficient of variation for precision of RXA quantification were 7.0% and 8.8%, respectively. Mean RXA concentration was 114±43μg/L .RXA significantly altered prothrombin time, activated partial thromboplastin time, factor analysis for intrinsic and extrinsic factors. Determinations of thrombin time, fibrinogen, FXIII and D-Dimer levels were not affected.

CONCLUSIONS

RXA plasma levels can be quantified accurately and precisely by a chromogenic anti-FXa assay on different coagulometers in different laboratories. Ingestion of 10mg RXA results in significant alterations of both PT- and aPTT-based coagulation assays.

Effects of drug interactions on biotransformation and antiplatelet effect of clopidogrel in vitro

BACKGROUND AND PURPOSE

The conversion of clopidogrel to its active metabolite, R-130964, is a two-step cytochrome P450 (CYP)-dependent process. The current investigations were performed to characterize in vitro the effects of different CYP inhibitors on the biotransformation and on the antiplatelet effect of clopidogrel.

EXPERIMENTAL APPROACH

Clopidogrel biotransformation was studied using human liver microsomes (HLM) or specific CYPs and platelet aggregation using human platelets activated with ADP.

KEY RESULTS

Experiments using HLM or specific CYPs (3A4, 2C19) revealed that at clopidogrel concentrations >10 microM, CYP3A4 was primarily responsible for clopidogrel biotransformation. At a clopidogrel concentration of 40 microM, ketoconazole showed the strongest inhibitory effect on clopidogrel biotransformation and clopidogrel-associated inhibition of platelet aggregation with IC(50) values of 0.03 +/- 0.07 microM and 0.55 +/- 0.06 microM respectively. Clarithromycin, another CYP3A4 inhibitor, impaired clopidogrel biotransformation and antiplatelet activity almost as effectively as ketoconazole. The CYP3A4 substrates atorvastatin and simvastatin both inhibited clopidogrel biotransformation and antiplatelet activity, less potently than ketoconazole. In contrast, pravastatin showed no inhibitory effect. As clopidogrel itself inhibited CYP2C19 at concentrations >10 microM, the CYP2C19 inhibitor lansozprazole affected clopidogrel biotransformation only at clopidogrel concentrations < or =10 microM. The carboxylate metabolite of clopidogrel was not a CYP substrate and did not affect platelet aggregation.

CONCLUSIONS AND IMPLICATIONS

At clopidogrel concentrations >10 microM, CYP3A4 is mainly responsible for clopidogrel biotransformation, whereas CYP2C19 contributes only at clopidogrel concentrations < or =10 microM. CYP2C19 inhibition by clopidogrel at concentrations >10 microM may explain the conflicting results between in vitro and in vivo investigations regarding drug interactions with clopidogrel.

Drug use problems with self-injected low-molecular-weight heparins in primary care

PURPOSE

Outpatient subcutaneous therapies are becoming increasingly common. A literature search failed to find produced any studies on application problems pertaining to the self-injection of low-molecular-weight heparins (LMWH) in a heterogeneous outpatient population under daily-life conditions. We therefore designed a study with the aim of recording drug use problems, patient satisfaction, compliance, problems arising from the injection site (abdomen vs. thigh), and residual drug volumes in pre-filled syringes used in self-injection therapy.

METHODS

Patients were recruited in community pharmacies by 95 trained Master's students in pharmacy. Data were collected during recruitment and by means of structured questionnaire-based telephone interviews that were carried out at the beginning and the end of the LMWH treatment.

RESULTS

The median age of the 213 patients enrolled in the study was 54 years [interquartile range (IQR) 39-70 years]; of these, 15.5% had their injections administered by a third person. The rate of self-reported non-compliance was 17.1%. At least one relevant problem was recorded in 85.0% of the cases. At the end of the treatment, 38.9% of the patients stated self-administration of the injections required some effort. The preferred injection site was the thigh (68.5%). An overall mean residual drug volume ≥ 10.0% was detected for 3.9% of the patients. If residual drug was present, a median of 11.2% (IQR 8.6-17.6%) of the total drug volume had not been injected. Patients injecting into the thigh showed a higher risk of leaving residual medication (odds ratio 2.16, 95% confidence interval 1.04-4.51).

CONCLUSIONS

Most patients had drug use problems, whereas no clear factors were associated with non-compliance, the injection site (apart from residual drug), and discomfort or effort required (apart from prior injection use).

Late altered organ function in very long-term survivors after allogeneic hematopoietic stem cell transplantation: a paired comparison with their HLA-identical sibling donor

BACKGROUND

Hematopoietic stem cell transplantation has become an established procedure worldwide. Severe early and late complications are well described. Little is known about more subtle changes in general health status of very long-term survivors. The study objective was to assess health status of very long-term survivors in comparison with their respective human leukocyte antigen-identical sibling donors.

DESIGN AND METHODS

Case matched comparison in a cross-sectional cohort was performed in a tertiary university hospital and referral center for hematopoietic stem cell transplantation. Forty-four pairs of recipients and their respective donors with a very long-term (17.5 years median; 11-26 years range) follow up after allogeneic hematopoietic stem cell transplantation were included. A comparative clinical evaluation and examination of routine clinical chemistry tests was carried out.

RESULTS

Recipients more frequently had a lower Karnofsky score (P = 0.05), hypertension (P = 0.015) and dyslipidemia (P = 0.002) but were less likely to be smokers (P = 0.016). Recipients showed systematically lower glomerular filtration rates (P < 0.0001), higher liver function tests (P = 0.0004 for Aspartat-Amino-Transferase) and reduced thyroid function (P = 0.002) despite normal or near normal values, and independent of presence or absence of chronic graft-versus-host disease. Indicators of inflammation were more frequent in recipients (9 of 44) with ongoing chronic graft-versus-host disease as measured by higher C-reactive protein (P = 0.001) and higher von Willebrand factor (P = 0.002). Conclusions Clinically very long-term survivors after an allogeneic hematopoietic stem cell transplantation present more frequently with cardiovascular risk factors and with subtle signs of altered organ function compared to their sibling donors. Even minimal ongoing chronic graft-versus-host disease remains associated with elevated laboratory indicators of inflammation. The clinical significance of these findings needs to be defined.

Leukocyte count and risk of thrombosis in patients undergoing haematopoietic stem cell transplantation or intensive chemotherapy

Elevated white blood cell count has recently been established as an independent risk factor for thromboembolic events in patients with myeloproliferative syndromes. Thrombotic events occur frequently in patients with haematological malignancies undergoing intensive cytoreductive treatment. We evaluated retrospectively the association of leukocyte counts and thrombosis in three cohorts of 100 patients each undergoing autologous or allogeneic haematopoietic stem cell transplantation or chemotherapy, respectively. A total of 26 thromboembolic events were recorded, 10 in recipients of allogeneic transplants, five in autografted patients, and 11 in the chemotherapy group. Fifteen events were central venous catheter related. Non-catheter related thrombotic events were pulmonary embolism (N=5), hepatic veno-occlusive disease (N=2), deep-vein thrombosis (N=1), stroke (N=1), ovarian vein thrombosis (N=1), and left ventricular thrombosis (N=1). Hazard rates showed two peaks, a first during cytoreduction in all groups, and a second after engraftment in transplanted patients. Time-dependent multivariable Cox analysis confirmed an association of leukocytosis with development of thrombosis (hazard ratio for leukocyte count > 11G/l: 9.73, 95% confidence interval 1.98-47.9, p=0.005). The risk associated with leukocytosis was independent from C-reactive protein level. Thrombocyte count and type of treatment (allogeneic vs. autologous transplantation vs. chemotherapy) had no significant influence on thrombosis development. In three cohorts of patients undergoing intensive cytoreductive treatment for haematological malignancy, leukocyte count was strongly associated with development of thrombotic complications.

Effect of beta-blockers, Ca2+ antagonists, and benzodiazepines on bleeding incidence in patients with chemotherapy induced thrombocytopenia

Beta-1-adrenoreceptor antagonists, Ca(2+) antagonists, and benzodiazepines negatively affect platelet aggregation in vitro. Few data exists on whether platelet function in vivo is relevantly influenced by exposure to any these substances. We analysed in three cohorts of 100 patients each treated with allogeneic hematopoietic stem cell transplantation (HSCT), autologous HSCT, and intensive chemotherapy, respectively, whether treatment with these drugs was associated with an increased risk of bleeding. Cumulative incidences of bleeding in the three cohorts were 47 +/- 5% after allogeneic transplants, 30 +/- 5% after autologous transplant, and 46 +/- 5% after chemotherapy (p = 0.008). Exposure to beta-blockers (hazard ratio [HR] 0.71, p = 0.32), Ca(2+) antagonists (HR 0.90, p = 0.73), and benzodiazepines (HR 1.18, p = 0.29) did not significantly increase the risk of bleeding in any cohort. Instead, bleeding risk was determined by platelet count, presence of inflammation, azotemia, presence of graft-versus-host disease and treatment with low-molecular weight heparin. After correcting for these factors, no differences in bleeding risk were seen between the three cohorts. In conclusion, therapy with Beta-1-adrenoreceptor antagonists, Ca(2+) antagonists, and benzodiazepines did not appear to significantly increase the risk for hemorrhagic complications in patients with iatrogenic severe thrombocytopenia.

Hypersensitivity reactions to anticoagulant drugs

Drugs with anticoagulant activity, including heparins, hirudins, coumarins, and platelet aggregation inhibitors belong to the most widely used drugs. Hypersensitivity reactions from these agents are rare. However, due to their widespread use, they may have a considerable impact on patient safety and treatment. Accurate diagnosis of potentially life-threatening adverse events and identification of alternatives is mandatory. We review hypersensitivity reactions caused by the different groups of anticoagulant agents and discuss the pathophysiological mechanisms, diagnostic possibilities and management options. According to patients histories the most common hypersensitivity reaction is intolerance to acetylsalicylic acid (ASA). Also localized erythematous plaques, occurring to subcutaneous application of heparins are rather common. Other hypersensitivity reactions are rare but may be life-threatening, e.g. skin necrosis due to heparin-induced thrombocytopenia. Rarely anaphylactoid reactions have been observed to ASA, heparin, and hirudin. Skin and provocation tests with immediate and late readings are the most reliable diagnostic tools for heparin- or hirudin-induced urticaria/anaphylaxis or heparin-induced delayed plaques. Provocation tests may be used to identify safe alternatives. In cases of necrosis from heparins or coumarins, all in vivo tests are contraindicated. Most in vitro tests are not universally available, and with the exception of platelet aggregation tests, they have a low sensitivity. In some anticoagulant-associated hypersensitivity reactions detailed allergologic investigation may help to identify safe treatment alternatives. Typically, several tests are needed, and therefore the test procedures are time consuming.

A large Swiss family with Bernard-Soulier syndrome - Correlation phenotype and genotype

Bernard-Soulier syndrome (BSS) is a rare, autosomal recessive inherited bleeding disorder associated with thrombocytopenia, thrombocytopathy and giant platelets. BSS is caused by genetic alterations of the glycoprotein (GP) Ib/V/IX complex. We report on a large Swiss family of whom four family members suffer from BSS. Here, a homozygous missense mutation in position 1829 (A(R)G) of the GPIX gene constituting a N45S substitution is the cause for the bleeding symptoms. A total of 38 family members within two generations were analyzed regarding the N45S mutation by DNA sequencing and restriction fragment length polymorphism. The laboratory parameters which are characteristically for BSS such as platelet count, platelet volume and the expression of CD42a (GPIX), CD42b (GPIbalpha) and CD41 (GPIIb) were measured for all 38 individuals. The four homozygous patients showed bleeding symptoms, thrombocytopenia and giant platelets. In these patients, the expression of CD42a (GPIX), CD42b (GPIbalpha) was diminished. Interestingly, the intensity of the bleeding symptoms of the 4 homozygous family members seemed to vary although they carry the same mutation. The 24 heterozygous carriers did not differ significantly from their 10 wildtype family members regarding bleeding symptoms and laboratory analysis.

Premature cardiovascular disease after allogeneic hematopoietic stem-cell transplantation

We assessed incidence and risk factors of cardiovascular events in 265 patients undergoing allogeneic hematopoietic stem-cell transplantation (HSCT) between 1980 and 2000 and who survived at least 2 years. Results were compared with a cohort of 145 patients treated during the same period with autologous HSCT. The median age of patients with allogeneic HSCT at last follow-up was 39 years, and median follow-up was 9 years. Eighteen (6.8%) patients after allogeneic and 3 (2.1%) patients after autologous HSCT experienced an arterial event. The cumulative incidence of first arterial event after allogeneic HSCT was 22.1% (95% CI, 12.0-40.9) at 25 years. The cumulative incidence 15 years after allogeneic HSCT was 7.5% as compared with 2.3% after autologous HSCT. Adjusting for age, risk of an arterial event was significantly higher after allogeneic HSCT (RR 6.92; P =.009). In multivariate analysis, allogeneic HSCT (RR: 14.5; P =.003), and at least 2 of 4 cardiovascular risk factors (hypertension, dyslipidemia, diabetes, obesity) (RR: 12.4; P =.02) were associated with a higher incidence of arterial events after HSCT. Thus, long-term survivors after allogeneic HSCT are at high risk for premature arterial vascular disease. HSCT might favor the emergence of established risk factors, such as hypertension, diabetes, and dyslipidemia.

Failure of recombinant factor VIIa in a patient with severe polymicrobial sepsis and postoperative uncontrolled intraabdominal bleeding

Background

This report discusses a case of unsuccessful treatment with recombinant factor VIIa (rFVIIa) in off-label use. The need for international guidelines concerning the off-label use of rFVIIa is outlined as well as the need for methods to control the efficacy of rFVIIa objectively.

Case presentation

54 year old male with severe polymicrobial sepsis due to a perforated diverticulitis of the sigmoid colon and consecutive overt disseminated intravascular coagulation. He suffered severe intraabdominal bleeding after abdominal surgery despite conventional haemostatic support. Repeated applications of factor VIIa temporarily improved coagulation essays but did not stop clinical bleeding. The patient died in multiorgan failure due to septic and haemorrhagic shock.

Conclusion

Off-label use of rFVIIa could result in more side effects than could be expected from literature because of a publication bias. However for most off-label applications large prospective, randomised and controlled trials to confirm the positive findings are missing. For the future, not only guidelines concerning the off-label use of rFVIIa are urgently needed but also guidelines for monitoring the efficacy of rFVIIa.

Hypersensitivity reactions to anticoagulant drugs: diagnosis and management options

Anticoagulants, including heparins, coumarins, hirudins, and some of the previously used plasma volume expanders, belong to the most widely used drugs. Hypersensitivity reactions from these agents are uncommon. However, they may have a considerable impact on patient safety and treatment decisions. Therefore, early diagnosis of potentially life-threatening adverse events and identification of alternatives is clinically important. This review contains an update on current knowledge about hypersensitivity reactions caused by the different anticoagulants. In addition, it discusses pathophysiologic mechanisms, diagnostic possibilities, and management options. The most common hypersensitivity reactions are erythematous plaques, occurring with a delay after subcutaneous application of heparins. Seldom they turn into maculopapular exanthema. Other hypersensitivity reactions are rare but may be life-threatening, e.g. skin necrosis because of heparin-induced thrombocytopenia. Skin and provocation tests with immediate and late readings are the most reliable diagnostic tools for heparin- or hirudin-induced urticaria/anaphylaxis or heparin-induced delayed plaques. If necrosis from heparins or coumarins is suspected, skin tests are contraindicated. In anaphylactic reactions caused by dextrans or hydroxyethyl starch skin tests are useless. Most in vitro tests have a low sensitivity and are not generally available. Therefore, in some anticoagulant-associated hypersensitivity reactions detailed allergologic investigation may help to identify safe treatment alternatives. However, several tests may be needed, and the procedures are usually time-consuming.

Transplant-associated microangiopathy (TAM) in recipients of allogeneic hematopoietic stem cell transplants

We studied occurrence, risk factors and outcome of patients with transplant-associated microangiopathy (TAM) after allogeneic stem cell transplantation (HSCT). A total of 221 consecutive patients were transplanted between 1995 and 2002. TAM is defined as evidence of hemolysis and schistocytes in the first 100 days. Outcomes analyzed included TAM and overall survival. Of 221 patients, 68 had TAM. The cumulative incidence was 31 (25-38)% at 100 days. Patients with TAM had higher LDH, higher bilirubin, higher creatinine and more often neurologic symptoms. TAM was not associated with stem cell source, cyclosporine levels and was not more frequent in recent years. In multivariate analysis, risk factors for TAM included donor type, age, gender, ABO-incompatibility and acute graft-versus-host disease (aGvHD). In patients with TAM, 1-year survival was lower than in patients without TAM (27 +/- 18% for TAM with high schistocyte counts; 53 +/- 15% for TAM with low schistocyte counts; vs 78 +/- 7% in patients without TAM; P<0.0001). TAM was independently associated with mortality adjusting for donor type, age and aGvHD occurrence and severity. TAM is frequent after HSCT and is associated with mortality even after adjustment for aGvHD grade. Risk factors of TAM are similar to aGvHD. TAM may represent endothelial damage driven by donor-host interactions.

[Anticoagulants and antiplatelet agents in pregnancy]

Anticoagulants and antiplatelet agents are currently used during pregnancy as treatment or prophylaxis for thromboembolic disease. Main adverse events of these agents are bleeding episodes, which put the pregnancy at risk. Unfractionated and low molecular weight heparins are first-line treatment or prophylaxis for thromboembolism. If an antiplatelet agent is needed, aspirin alone or in combination with heparins can be safely administered. Coumarine derivatives are still contraindicated during pregnancy because of teratogenicity and/or bleeding. No adequate data are yet available on the safety profile of the new antiplatelet agents or the direct thrombin inhibitors. Special considerations are discussed on the risks of regional anesthesia, as well as on nursing during anticoagulation.

[New antiplatelet agents (platelet receptor blockers): has aspirin come out of place?]

Nach der Einführung des Aspirins in die kardiovaskuläre Medizin Ende der 40er Jahre konnten sich erst in den 90er Jahren neue Substanzen als äquivalente oder bessere Antiaggregantien etablieren. Es sind dies das orale Clopidogrel (Plavix®), welches die ADP-induzierte Plättchenaggregation hemmt und die intravenösen GPIIb/IIIa-Hemmer (ReoPro®, Aggrastat®, Integrilin®), welche den Fibrinogenrezeptor auf den Plättchen blockieren. Aspirin behält weiterhin seinen festen Platz in der primären und sekundären Prävention der kardiovaskulären Krankheiten. Clopidogrel kann Patienten mit Aspirin-Unverträglichkeit oder bei rezidivierenden kardiovaskulären Ereignissen unter Aspirin verabreicht werden. Für eine allgemeine Empfehlung zur Umstellung von Aspirin auf Clopidogrel bei allen Indikationen fehlt noch die komplette Evidenz. Die Kombination Aspirin plus Clopidogrel verspricht noch besseren Schutz vor kardiovaskulären Komplikationen in ausgewählten Indikationen. Die GPIIb/IIIa-Hemmer haben sich als intravenöse Therapie in der Behandlung von Patienten mit Katheterinterventionen der Koronararterien gut etabliert. Die Hoffnung, dass die oralen GPIIb/IIIa-Hemmer den gleichen Erfolg haben könnten, hat sich definitiv in mehreren Studien nicht bestätigt. Die Entwicklung der neuen Antiaggregantien signalisiert eine Optimierung der Therapie der Patienten mit atherosklerotischer Krankheit.

Combining altered levels of effector transcripts in circulating T cells with a marker of endothelial injury is specific for active graft-versus-host disease

Cytotoxic T lymphocytes (CTLs) are important effector cells of graft-versus-host disease (GVHD) and vascular endothelial cells are target cells of allospecific CTL. A combined assessment of T-cell activation and endothelial injury should result in a specific and sensitive test for GVHD. We examined circulating T lymphocytes for effector molecules involved in CTL-mediated endothelial injury. We analyzed CD4 and CD8 T lymphocytes of 24 long-term survivors of allogeneic stem cell transplantation with or without GVHD, and nine healthy, age-matched controls for signs of CTL activation and endothelial injury. IFN-gamma transcript levels in CD8 T cells were significantly elevated in SCT recipients with GVHD compared to patients without GVHD (767 CD3epsilon units/T cell (376-2050) vs 211 CD3epsilon units/T cell (159-274), P=0.01). Fas ligand transcript levels in CD4 T cells were significantly elevated in SCT recipients without GVHD compared to patients with GVHD (20 CD3epsilon units/T cell (0-78) vs 0 CD3epsilon units/T cell (0-0), P=0.01). Von Willebrand factor plasma levels were high in patients with GVHD, but normal in patients without GVHD (209 (186-254) vs 120 (100-141), P=0.0005). This assessment of T-cell activation and endothelial injury results in a sensitive and specific test to identify patients with active chronic GVHD.

Antiphospholipid syndrome and endocrine damage: why bilateral adrenal thrombosis?

We describe a rare case of bilateral hemorrhagic infarction of the adrenal glands diagnosed in the context of positive antiphospholipid antibodies (aPL). The patient presented atypical clinical symptoms of adrenal insufficiency. Laboratory investigation showed complete adrenal failure and increased aPL, both manifestations persisted 1 yr after the initial event. MR imaging at baseline was compatible with bilateral hemorrhagic infarction and showed almost complete loss of viable adrenal tissue 1 yr later. Although no direct causal effect can be proved, the sequence of events and the exclusion of other common causes of bilateral adrenal hemorrhage (e.g. tuberculosis, severe coagulation disorder) support an association between aPL and adrenal hemorrhagic infarction. A unique link between particular anatomical characteristics of the adrenal fascicular zone and a novel, previously described, explanation model of aPL-thrombosis is hypothesized. It is based on the properties of late endosomes, which are important organelles participating in cholesterol trafficking and protein sorting within cells and express epitopes recognized by aPL. It would be interesting to investigate adrenal tissue for presence of late endosomes and their aPL relevant epitopes for proof of this tempting hypothesis. Focal accumulation of aPL and isolated, simultaneous, bilateral adrenal infarctions could thus be explained.

[New antiaggregants and their importance for the practitioner]

Since the introduction of Aspirin in the 1950s many substances have been introduced with an antiplatelet effect. Only few have been proved to be superior to aspirin in some clinical settings. Ticlopidin and its biochemical analog clopidogrel block the ADP-induced platelet aggregation. Clopidogrel having a better profile in terms of adverse events has been established over ticlopidin. It can be used for secondary prevention in patients with stroke, myocardial infarction or peripheral arterial disease instead of aspirin, certainly in cases with aspirin intolerance or with relapsing cardiovascular event under treatment with aspirin. For a general substitution of aspirin through clopidogrel hard evidence is still lacking. The combination aspirin + clopidogrel has been proved superior to aspirin in the treatment of patients with unstable angina or myocardial infarction without ST-segment elevation. For an extension of this indication to other clinical entities further evidence is needed. GPIIb/IIIa blockers are a well established treatment modality in patients undergoing coronary catheter interventions. Oral GPIIb/IIIa blockers, probably because of their pharmacokinetic profile, have proved to be insufficient in protecting from cardiovascular events compared to aspirin. Practical aspects concerning use of the newer antiplatelet agents during pregnancy, preoperatively and in spinal anesthesia are discussed.

[Management of patients with Type 2B von Willebrand's disease during delivery and puerperium]

Von Willebrand's disease (VWD) is the most common congenital haemorrhagic diathesis inherited as an autosomal dominant trait, with a prevalence estimated to be 1 - 2 %. In subtype 2B an abnormally structured von-Willebrand factor (VWF) leads to an increased binding of VWF molecules to normal platelets, which regularly results in thrombocytopenia in pregnancy. Only few systematic observations in patients with type 2B VWD in the perinatal period have been reported in the literature. Six spontaneous deliveries in two sisters with type 2B VWD are reported. The first patient did not show any bleeding complications in five vaginal deliveries without any factor replacement therapy. The second patient showed a massive haemorrhage on the third postpartum day after administration of factor VIII-VWF concentrate replacement therapy (Haemate(R) HS), only on the day of delivery. No neonatal complications were reported. The clinical management of pregnancy, delivery and puerperium in patients with type 2B VWD requires close collaboration of experienced obstetricians, haematologists, anaesthesiologists and paediatricians. During labour and delivery, but especially in puerperium, there is a significantly increased risk for haemorrhage. Vaginal delivery is generally safe, but the incidence of postpartum haemorrhage is 30 %. These bleedings may be extremely severe. The danger of postpartum bleeding complications cannot be predicted with certainty, neither by past history of bleeding episodes or haematological laboratory tests of VWF activity levels. Hence, in all patients factor VIII-VWF concentrate replacement therapy should be initiated already in the first stage of labour. Post partum replacement therapy along with effective uterotonic therapy should be continued at least for seven days. With this treatment bleeding problems may be largely prevented. The decision to perform epidural block in labour and delivery must be assessed depending on individual risk factors.

Endothelial injury mediated by cytotoxic T lymphocytes and loss of microvessels in chronic graft versus host disease

BACKGROUND

Vascular endothelial cells form the interface between recipient tissues and circulating alloreactive donor T cells after allogeneic stem cell transplantation. Vascular injury has been seen in patients with acute graft versus host disease (GVHD) in the skin. We aimed to see whether vascular injury mediated by cytotoxic T lymphocytes and microvessel loss arises in patients with chronic GVHD.

METHODS

We investigated eight patients with acute GVHD and ten with chronic GVHD for signs of endothelial injury and microvessel loss by measurement of von Willebrand factor (vWF) in plasma and blood vessel density in biopsy samples taken from lesional skin. Controls consisted of nine patients without GVHD who survived for longer than 100 days and nine healthy people. Inflammation and endothelial injury were assessed in selected samples by immunostaining for CD8 T cells, activated cytotoxic T lymphocytes, and vascular endothelial cells.

FINDINGS

We identified more extensive loss of microvessels in the skin of patients with GVHD (median 66 capillaries/mm(2); IQR 16-98) than of healthy controls (205 capillaries/mm(2); 157-226; p=0.005). Patients with GVHD had higher concentrations of vWF (238%; 168-288) than did those without GVHD (102%; 88-118; p=0.0005). Perivascular CD8 T cell infiltrates in skin correlated with vWF plasma concentrations in patients with GVHD (p=0.01), and activated cytotoxic T lymphocytes and endothelial injury were present in these same samples.

INTERPRETATION

Host endothelial cells are a target of alloreactive donor cytotoxic T lymphocytes. Substantial blood vessel loss may lead to impaired blood perfusion and tissue fibrosis, the hallmark lesion of chronic GVHD.

Antiretroviral therapy reduces markers of endothelial and coagulation activation in patients infected with human immunodeficiency virus type 1

We investigated the effect of antiretroviral therapy on vascular activation in 41 human immunodeficiency (HIV)--infected patients receiving a regimen that included either at least 1 protease inhibitor (PI; n = 21) or a nonnucleoside reverse-transcriptase inhibitor (NNRTI; n = 20). A control group of 21 healthy subjects was included for comparison. Levels of endothelial markers (soluble vascular cell adhesion molecule [sVCAM]--1, soluble intercellular adhesion molecule--1, and von Willebrand factor) were higher in HIV-infected persons before treatment than in control subjects and decreased significantly after 5--13 months of treatment. Levels of sVCAM-1 and von Willebrand factor correlated significantly with initial virus load. d-dimer concentrations also decreased significantly after initiation of treatment. PI- and NNRTI-containing regimens had similar effects. Therapy did not reduce levels of the soluble platelet (sP) activation markers sP-selectin and CD40 ligand. The inhibition of markers of vascular activation may counterbalance sequelae of therapy-induced dyslipidemia and potentially prevent development of atherosclerosis in HIV-infected patients.

Influence of the genetic background on platelet function, microparticle and thrombin generation in the common laboratory mouse

Genetic background has been shown to affect phenotype in transgenic mice with hemostatic defects. We present comparative data on various platelet function tests, as well as on microparticle and thrombin generation capacity in three mouse strains most commonly used in transgenic applications. Normal, inbred 129Sv (n = 24), C57BL/6 (n = 14) and BALB/c (n = 22) mice were used. BALB/c mice showed statistically significantly longer tail-bleeding times (158 +/- 42 s, P<0.02) than 129Sv (113 +/- 37) and C57BL/6 (122 +/- 29) and paradoxically increased velocity of platelet aggregation (P<0.01) with ADP, collagen, ionophore and thrombin. ATP-release did not differ between strains, it was weakest with ADP and strongest with thrombin. 129Sv platelets were less responsive to thrombin. Generation of platelet microparticles did not differ between strains either and could efficiently be inhibited by EDTA but not by aspirin or alprostadil. Two anti-GPIIIa monoclonal antibodies did not inhibit microparticles either, although they could block aggregation. Thrombin generation was equivalent in C57BL/6 and BALB/c, but slower in 129Sv. Interestingly, the reaction in all strains was immediate and different from the human model in that no lag-phase was seen after triggering. In summary these mouse strains show similar patterns of ex vivo platelet aggregation, bleeding times as well as microparticle and thrombin generation. Subtle differences were found, which should be taken into consideration when interpreting data from wild-type or transgenic models.

Haemostatic profile in hypothyroidism as potential risk factor for vascular or thrombotic disease

The influence of thyroid failure on haemostasis is controversial, both hypocoagulable and hypercoagulable states have been reported. Since both subclinical and overt hypothyroidism have been associated with atherosclerosis, a hypercoagulable state in addition might represent a risk factor for thromboembolic disease. We investigated various haemostatic variables in 42 women with subclinical hypothyroidism and compared them to 66 euthyroid controls. Prothrombin time, activated partial thromboplastin time, fibrinogen, factor VII activity (FVII:C), factor VII antigen (FVII:Ag), factor VIII activity, von Willebrand factor (vWF), antithrombin III, heparin cofactor II, protein C, protein S, plasminogen, antiplasmin, plasminogen activator inhibitor and tissue plasminogen activator, as well as common lipid variables, were measured. Factor VII:C (P < 0.02) and the ratio FVII:C/FVII:Ag (P < 0.01) were significantly increased in subclinical hypothyroid patients compared to the control group. Both parameters remained higher in hypothyroid patients after exclusion of 18 women on oestrogen replacement therapy. No differences were found between the groups with respect to vWF or the other haemostatic and lipid variables tested. Patients with subclinical hypothyroidism had significantly higher levels of FVII:C. The greater increase in FVII:C compared to that of FVII:Ag, as shown by the increase in their ratio, might reflect the presence of activated FVIIa. This might mean a hypercoagulable state, which could contribute to the increased prevalence of coronary heart disease reported in such patients. A hypercoagulable state might be another argument in favour of thyroxine replacement treatment in subclinical hypothyroidism, especially in patients with additional risk factors for vascular disease.

Structure and function of murine alphaIIbbeta3 (GPIIb/IIIa): studies using monoclonal antibodies and beta3-null mice,

The alphaIIbeta3 receptor (GPIIb/IIIa) is the only platelet-specific integrin receptor and the most abundant adhesion/aggregation receptor on the surface of human platelets. Since mice are increasingly being used as models of human disease, we analyzed the structure and function of murine platelet alphaIIbeta3, utilizing both beta3 integrin-deficient mice, who have a phenotype that resembles Glanzmann thrombasthenia, and our hamster monoclonal antibody (mAb) 1B5 to murine alphaIIbbeta3. By immunoblot analysis, flow cytometry, and mAb binding studies, mouse platelets express abundant amounts of alphaIIbbeta3 (60-80,000 copies/platelet). Like their human counterparts, murine alphaIIb and beta3 exhibit different electrophoretic motilities under nonreducing (aIIb 135k Da; beta3 92k Da) and reducing (aIIb 120k Da; beta3 108k Da) conditions, and the alphaIIbbeta3 complex is dissociated by EDTA at pH 8 and 37 degrees C. Murine beta3 is less susceptible to proteolysis by plasmin than is human beta3. In addition to defective platelet aggregation, mouse platelets lacking alphaIIbbeta3 and alphaVbeta3 are unable to adhere to fibrinogen and prothrombin, but retain the ability to adhere to fibronectin and collagen. Following platelet activation, beta3-null platelets express slightly less P-selectin than do wild-type mouse platelets. Moreover, beta3-null platelets have altered tyrosine phosphorylation patterns following thrombin- and collagen-induced aggregation. These results suggest fundamental similarities between human and mouse platelet activation and aggregation, but delineate subtle differences that need to be considered when comparing studies from mice and humans.

Platelets and cytokines in concert with endothelial activation in patients with peripheral arterial occlusive disease

We tested the hypothesis whether circulating oncostatin-M (OSM), a cytokine that in vitro promotes fibrinogen biosynthesis and smooth muscle cell proliferation, or soluble CD40 ligand (CD40L; CD154), a leukocyte and platelet surface marker that stimulates endothelial cells, were associated: (a) with fibrinogen and other soluble cell adhesion molecules, such as P-selectin, vascular cell adhesion molecule-1 (VCAM-1), intercellular cell adhesion molecule-1 and platelet-endothelial cell adhesion molecule-1; or (b) with restenosis and platelet activation in 71 patients with peripheral arterial occlusive disease undergoing peripheral angioplasty (PTA). Platelet membrane activation markers (CD62P, CD63, activated GPIIb/IIIa) were immunologically measured at 0, 1, 24 and 48 h, and 3 and 6 months after PTA. Soluble cell adhesion molecules, endothelial markers and various hemostatic variables were measured before PTA. Of the patients, 42.3% developed restenosis within 6 months, defined as a >50% reduction of the lumen at the site of balloon dilatation. Soluble CD40L was not higher in the restenosis group. Interestingly, patients with high CD40L showed significantly higher soluble VCAM-1 (P < 0.01) and thrombomodulin (P < 0.01), as well as trends for higher soluble P- and E-selectin. Platelet activation was found uniformly increased mostly at 1 and 24 h, as well as at 3 and 6 months. OSM was measurable in 53.5% (6.9 +/- 9.4 pg/ml) of the patients and undetectable in the others. No differences in the rate of restenosis was found in these two groups, which did not differ with respect to fibrinogen (3.14 +/- 1.00 versus 3.21 +/- 0.70 g/l), or the other parameters. In conclusion, soluble CD40L is associated with higher endothelial biological markers that might implicate its involvement in endothelial activation. Platelet activation, probably intermittent, might play a significant role through the expression of CD40L as a source of activation signals to the endothelial cells. Free circulating OSM does not seem to correlate directly with fibrinogen or with other acute phase reaction proteins, the synthesis of which it could influence in vitro. This might well not mean, however, that OSM lacks this activity in vivo.

Circulating cell adhesion molecules and endothelial markers before and after transluminal angioplasty in peripheral arterial occlusive disease

In the present study, the levels of soluble adhesion molecules P- and E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1) and of other markers of endothelial activation or injury, such as thrombomodulin, von Willebrand factor (vWF), as well as homocysteine, were prospectively investigated in 71 patients (21 women, 50 men, age 68+/-13) with predominantly femoropopliteal peripheral arterial occlusive disease (PAOD, stage II-IV, Fontaine) before and after percutaneous transluminal angioplasty (PTA). Thirty patients (42.3%) developed restenosis within 6 months, defined as a > 50% reduction of the lumen diameter at the site of PTA. At entry in the study, 46% and 58% of all patients had higher than normal levels of soluble P-selectin and VCAM-1, respectively. Thrombomodulin (P < 0.01) measured at entry, was significantly higher in patients who developed late restenosis, with trends for higher values for P-selectin, VCAM-1 and vWF. The relative risks for developing restenosis were 2.41 (CI95%: 1.23-4.75) and 1.54 (CI95%: 0.98-2.72) for thrombomodulin and P-selectin, respectively. Soluble P-selectin and the severity of PAOD (Fontaine stage III/IV) were found to be statistically indicative factors for late restenosis in a logistic regression risk factor analysis with an overall predictive value of 72%. At 6 months, those who developed restenosis had also higher soluble P-selectin (P < 0.01), VCAM-1 (P < 0.05) and a trend for higher thrombomodulin. Homocysteine was elevated in 52% of the patients at entry but neither was it associated with higher restenosis rates nor did it correlate with the levels of thrombomodulin or the other adhesion molecules. These findings indicate that patients with PAOD have to a significant proportion, elevated levels of circulating soluble adhesion molecules and markers of endothelial activation occurring in concert with an ongoing atherosclerotic process.

Beta3-integrin-deficient mice are a model for Glanzmann thrombasthenia showing placental defects and reduced survival

beta3 integrins have been implicated in a wide variety of functions, including platelet aggregation and thrombosis (alphaIIbbeta3) and implantation, placentation, angiogenesis, bone remodeling, and tumor progression (alphavbeta3). The human bleeding disorder Glanzmann thrombasthenia (GT) can result from defects in the genes for either the alphaIIb or the beta3 subunit. In order to develop a mouse model of this disease and to further studies of hemostasis, thrombosis, and other suggested roles of beta3 integrins, we have generated a strain of beta3-null mice. The mice are viable and fertile, and show all the cardinal features of GT (defects in platelet aggregation and clot retraction, prolonged bleeding times, and cutaneous and gastrointestinal bleeding). Implantation appears to be unaffected, but placental defects do occur and lead to fetal mortality. Postnatal hemorrhage leads to anemia and reduced survival. These mice will allow analyses of the other suggested functions of beta3 integrins and we report that postnatal neovascularization of the retina appears to be beta3-integrin-independent, contrary to expectations from inhibition experiments.

Two consecutive pregnancies and deliveries in a patient with von Willebrand's disease type 3

Pregnancy and delivery are critical events in women with von Willebrand's disease type 3. Prophylactic treatment for delivery and early postpartum period is recommended. Vaginal delivery is considered safe. However, experience is based on rare case reports. We report the management of two pregnancies and successful deliveries in a woman with von Willebrand's disease type 3.

The effect of nimesulide versus placebo on hemostasis in healthy volunteers

OBJECTIVE

The primary objective was to evaluate the effect of 7 days treatment with nimesulide on bleeding time. Blood coagulation, von Willebrand factor and platelet aggregation ex vivo were investigated as a secondary objective.

METHOD

A randomised, double-blind, placebo-controlled, parallel group, single centre study performed on 20 healthy male volunteers who received either placebo or nimesulide 100 mg twice daily for 7 days. Bleeding time, platelet count and platelet aggregation, thromboplastin time (prothrombin time), activated partial thromboplastin time, fibrinogen, Factor VIII:C, vWF:Ag, vWF:RCof and platelet-rich plasma aggregation following stimulation with adenosine 5'-diphosphate, collagen, arachidonic acid, ristocetin, thrombin and thrombin receptor-activating peptide were measured at baseline (day 0), and then 3 h after the first (day 1) and last (day 7) treatment.

RESULTS

The bleeding times for all subjects remained within the normal range throughout the study period, with no significant differences between the two treatment groups. There were no significant changes from baseline in platelet aggregation studies or in any of the other haemostasis tests, with no significant differences between the two groups. No clinically significant adverse events were reported or observed.

CONCLUSIONS

Daily administration of 200 mg nimesulide for 7 days neither prolongs bleeding time nor modifies any of the other haemostasis variables measured. The lack of interactions with important haemostatic mechanisms suggests that nimesulide may also be used in patients with bleeding problems. This expectation has still to be confirmed by clinical experience.

Role of hemostatic risk factors for restenosis in peripheral arterial occlusive disease after transluminal angioplasty

In a prospective study, the role of various hemostatic factors known to be associated with thrombotic risk was investigated in 71 patients with peripheral arterial occlusive disease (PAOD, stages II through IV, Fontaine; aged 68 +/- 13 years). Laboratory investigations were done before; 1, 24, and 48 hours after; and 3 and 6 months after percutaneous transluminal angioplasty (PTA). Thirty of 71 (42.3%) patients developed restenosis (> 50% reduction of the lumen diameter) at the site of PTA within 6 months, verified by color-coded duplex sonography. Significantly increased levels of thrombin-antithrombin III complexes (P < .01), prothrombin fragments 1 + 2 (P < .01), and D-dimers (P < .01) were found 1 hour, as well as 24 to 48 hours, after PTA. Fibrinogen (P < .01) and von Willebrand factor (P < .01) were significantly higher 48 hours after PTA. Restenotic patients as a whole had higher plasma fibrinogen (3.46 +/- 1.12 versus 2.95 +/- 0.62 g/L, P < .01) and C-reactive protein (25.4 +/- 46.7 versus 7.9 +/- 6.9 mg/L, P < .05) at baseline, as well as higher fibrinogen (P < .05) and prothrombin fragments 1 + 2 (P < .01) during months 3 to 6 after PTA. There was a nonsignificant tendency for higher values of von Willebrand factor (206 +/- 98% versus 184 +/- 100%, P = .2) at baseline in patients with restenosis, whereas tissue plasminogen activator, plasminogen activator inhibitor, coagulation screening tests, blood cell counts, and serum lipids showed no significant difference between the two groups. The relative risk for developing restenosis within 6 months while having high fibrinogen (> 2.8 g/L) or C-reactive protein at baseline was 2.80 (95% CI: 1.30-6.02, P < .01) and 1.96 (95% CI: 1.07-3.58, P < .05), respectively. Patients with critical limb ischemia (stage III/IV, Fontaine) had significantly higher fibrinogen and von Willebrand factor at repeated points of time, as well as significantly higher C-reactive protein and lower creatinine clearance at entry. In the logistic regression risk factor analysis, baseline plasma fibrinogen, C-reactive protein concentration, and the severity of the arterial disease were significantly predictive of restenosis. Our results indicate that high procoagulant factors and persistent thrombin generation of the hemostatic system might promote restenosis, particularly in patients with extended atherosclerosis. This finding suggests that new treatment strategies should be taken under consideration for patients with PAOD and PTA.