Detection of endogenous tissue factor levels in plasma using the calibrated automated thrombogram assay

Background

The calibrated automated thrombogram (CAT) assay measures thrombin generation in plasma.

Objective

Use the CAT assay to detect endogenous tissue factor (TF) in recalcified platelet-rich plasma (PRP) and platelet-free plasma (PFP).

Methods

Blood from healthy volunteers was collected into citrate and incubated at 37 °C with or without lipopolysaccharide (LPS) for 5 hours. PRP and PFP were prepared and clotting was initiated by recalcification. Thrombin generation was measured using the CAT assay.

Results

The lag time (LT) was significantly shortened in PRP prepared from LPS-treated blood compared with untreated blood (10 ± 3 min versus 20 ± 6 min), and this change was reversed by the addition of inactivated human factor VIIa. LPS stimulation did not change the peak thrombin. Similar results were observed in PFP (21 ± 4 min versus 35 ± 5 min). LPS stimulation also significantly reduced the LT of PRP and PFP derived from blood containing citrate and a factor XIIa inhibitor. Finally, a low concentration of exogenous TF shortened the LT of PFP prepared from unstimulated, citrated blood without affecting the peak thrombin.

Conclusion

Changes in LT in the CAT assay can be used to monitor levels of endogenous TF in citrated plasma.     

In vitro comparison of dabigatran, unfractionated heparin, and low-molecular-weight heparin in preventing thrombus formation on mechanical heart valves

Introduction

Lifelong oral anticoagulation (OAC) therapy is required for the prevention of thromboembolic events after implantation of an artificial heart valve. Thromboembolism and anticoagulant-related bleedings account for ≈ 75% of all complications experienced by heart valve recipients (2-9% of patients per year). The present study investigated the efficacy of dabigatran, a new direct thrombin inhibitor for oral use, as compared to unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) in preventing thrombus formation on mechanical heart valves in vitro.

Material and Methods

Blood (230 ml) from healthy young male volunteers was anticoagulated either by dabigatran (1 μmol/l), UFH (150 IU), or LMWH (100 IU). Mechanical heart valve prostheses were placed in an in vitro thrombosis tester and exposed to the anticoagulated blood samples under continuous circulation at a rate of 75 beats per minute.

Results

In whole blood with no anticoagulant, the apparatus completely clotted in 15-20 minutes. When blood was treated with dabigatran, the mean thrombus weight was 164 ± 55 mg, in the UFH group 159 ± 69 mg, and in the LMWH group 182 ± 82 mg (p-value: 0.704). Electron microscopy showed no significant difference in thrombus formation in any group.

Conclusisons

Dabigatran was as effective as UFH and LMWH in preventing thrombus formation on mechanical heart valves in our in vitro investigation. Thus, we hypothesize that dabigatran etexilate might potentially be a useful and competitive orally administered alternative to UFH and LMWH for recipients of alloplastic heart valve prostheses.     

Thrombogenic potential of whole blood is higher in patients with acute coronary syndrome than in patients with stable coronary diseases

Introduction

Although thrombogenic potential of blood may play an important role for the onset of acute coronary syndrome (ACS), there is no established way to evaluate it by single parameter. We compared the thrombogenic potential of whole blood between patients with ACS and those with stable coronary diseases using single comprehensive parameter.

Materials and Methods

Consecutive patients with ACS (n = 146) and those with stable coronary heart diseases (control, n = 92) were prospectively examined. Thrombogenic potential of whole blood was evaluated by blood vulnerability index measured by Micro-Channel Array Flow Analyzer (MC-FAN).

Results

Blood vulnerability index was higher in ACS than in control patients (5099 ± 2278 vs. 2071 ± 389, p < 0.0001), higher in acute MI than in unstable angina patients (5693 ± 2146 vs. 3524 ± 1841, p < 0.0001), and higher in ACS patients with initial TIMI 0/1 flow grade than in those with TIMI 2/3 flow grade (6061 ± 1936 vs. 2560 ± 1301, p < 0.0001). Furthermore, blood vulnerability index decreased from acute to chronic stage in acute MI patients. Multivariate logistic regression analysis revealed that high blood vulnerability index, high LDL cholesterol, high CRP, no use of aspirin, and no use of β-blocker were the independent contributors for the onset of ACS.

Conclusion

High thrombogenic potential of whole blood evaluated by blood vulnerability index was significantly associated with ACS and was reduced from acute to chronic stage in acute MI.

Condensed Abstract

Thrombogenic potential of whole blood was evaluated by blood vulnerability index measured comprehensively by Micro-Channel Array Flow Analyzer (MC-FAN) in consecutive patients with ACS (n = 146) or stable coronary diseases (control, n = 92) prospectively. Blood vulnerability index was significantly higher in ACS patients, especially in acute MI and poor initial TIMI flow grade patients, compared with control patients; and blood vulnerability index was reduced from acute to chronic stage in acute MI patients.     

Platelet activation in patients with peripheral vascular disease: reproducibility and comparability of platelet markers

Background

Many markers of platelet activation have been described but their reproducibility and comparability in patient populations are poorly defined.

Objectives

We sought to compare markers of platelet and monocyte activation with platelet-monocyte aggregates, a proposed gold standard of in vivo platelet activation, and assess their reproducibility in patients with peripheral arterial disease: a population with substantial platelet activation, inflammation and risk of thrombotic events.

Patients/Methods

Thirty patients with peripheral vascular disease attended on two occasions to permit within-day and between-day comparisons. In vivo platelet and monocyte activation were determined by flow-cytometric quantification of platelet-monocyte aggregation, platelet surface expression of P-selectin and CD40L, platelet-derived microparticles, and monocyte surface expression of CD40 and CD11b. Plasma concentrations of platelet-derived microparticles, soluble P-selectin and CD40L were measured by enzyme-linked immunosorbant assays.

Results

Platelet-monocyte aggregation (36.7 ± 7.86%), and platelet surface expression of P-selectin (5.8 ± 1.65%) and CD40L (3.3 ± 1.45%) demonstrated comparable within-day (mean difference ± co-efficient of reproducibility; 0.9 ± 15.4%, 0.21 ± 1.65% and 0.2 ± 2.8% respectively) and between-day reproducibility (2.0 ± 12.4%, 0.10 ± 2.25% and 0.9 ± 6.4% respectively). Platelet-monocyte aggregates correlated well with other platelet (r = 0.30-0.50, P < 0.02) and monocyte (r = 0.27-0.47, P < 0.03) activation markers. Flow cytometric and assay quantified platelet-derived microparticles showed poorer reproducibility (co-efficient of reproducibility > 40).

Conclusions

In patients with peripheral arterial disease, measurements of platelet-monocyte aggregates have good reproducibility and consistently reflect other markers of platelet and monocyte activation.     

Impaired spontaneous thrombolytic activity measured by global thrombosis test in males with metabolic syndrome

Introduction

In patients with metabolic syndrome (MetS), activity of the fibrinolytic system is generally surmised to be decreased through increased plasminogen activator inhibitor-1 (PAI-1) generation. However, there have been no detailed reports describing whether the clot lysis activity is more dominant than increased clot formation activity for production of the thrombotic state in MetS.

Methods

The global thrombosis test (GTT) is a novel method designed to test both clot formation and clot lysis activities under physiological conditions by using non-anticoagulated blood samples in vitro. We used the GTT to examine the thrombotic or thrombolytic states in males with MetS.

Results

Lysis time, which reflects spontaneous clot lysis activity, was significantly longer in MetS subjects (median, 1494 s; range, 865-3596 s; n = 30) than in control subjects (median 1246 s; range, 667-2239 s; n = 53). There was no significant difference between the two groups in occlusion time, which reflects platelet function. The mean level of PAI-1 was significantly higher in MetS subjects than in controls (mean ± SE, 8.7 ± 1.1 and 5.0 ± 0.5 ng/mL, respectively). PAI-1 level and lysis time were significantly correlated (r = 0.400, P < 0.01).

Conclusion

These results suggest that male patients with MetS are more likely than controls to experience a thrombotic state through decreased fibrinolytic activity due to increased PAI-1 generation, and that the GTT is useful for evaluating fibrinolytic activity in vitro.     

Quality of life in patients with idiopathic subclavian vein thrombosis

Introduction

Idiopathic subclavian vein thrombosis (SVT) is a rare disease but these otherwise healthy patients often suffer from prolonged clinical manifestations. The aim of this retrospective study was to assess the range and severity of thrombosis-related disability of the upper extremity in patients after an episode of documented idiopathic SVT in the long-term follow-up.

Materials and Methods

The quality of life (QoL) of 37 patients with documented idiopathic SVT was assessed by two standardized questionnaires (DASH and SF 36). The DASH and SF-36 questionnaire each use a 100 point scale. 0 stands for uncompromised functioning, 100 for maximum limitation in the DASH, while in the SF-36 0 marks the lowest rating of QoL and 100 indicates the best imaginable quality of life.

Results

Mean follow-up time was 120 ± 80.1 months (range: 14 to 286 months). The mean DASH score was 10.7 ± 12 and the mean scores for the SF-36 dimensions Physical Component Summary (PCS) and Mental Component System (MCS) were 52 ± 9.3 and 46.3 ± 9.5, respectively.

Conclusions

Patients suffering from idiopathic SVT report good overall QoL judged by the mean DASH and satisfactory QoL by the SF-36 score in the long-term follow-up. These patients deal well with their physical limitations.     

Effect of pramipexole on cutaneous-silent-period parameters in patients with restless legs syndrome

Objective

The aim of this study was to investigate cutaneous-silent-period (CSP) parameters in patients with restless legs syndrome (RLS) and examine the effects of treatment on CSP which, to our knowledge, have not been investigated till date.

Methods

A total of 25 patients with RLS and 25 healthy volunteers were studied. CSP latency and duration in the upper and lower extremities were examined in the two groups. In RLS patients, the variables were examined before and after pramipexole treatment.

Results

Lower-extremity CSP latency was longer (106.22 ± 11.69 ms vs. 91.67 ± 8.53 ms; p < 0.001) and CSP duration was shorter (35.50 ± 10.91 ms vs. 49.47 ± 6.43 ms; p < 0.001) in patients, compared with controls. In the patient group, CSP durations in the upper (40.88 ± 7.95 ms vs. 46.84 ± 10.22 ms; p = 0.006) and lower extremities (35.50 ± 10.91 ms vs. 44.91 ± 6.43 ms; p = 0.005) were prolonged after treatment, compared with pre-treatment values.

Conclusions

Small-fibre neuropathy may exist in RLS. In addition, we suggest that pramipexole may regulate cortical and spinal inhibitory mechanisms.

Significance

The use of CSP may aid in the diagnosis of RLS and may be used as a measure of treatment effectiveness.     

The ‘carry-over’ effects of patient self-testing: Positive effects on usual care management by an anticoagulation management service

Introduction

Patient self-testing (PST) of the international normalised ratio (INR) has a positive effect on anticoagulation control. This study investigated whether the benefits of PST (other than increased frequency of testing, e.g. patient education, empowerment, compliance etc.) could be ‘carried-over’ into usual care management after a period of home-testing has ceased.

Material and methods

Patients that completed a six month period of PST (as part of a randomised controlled trial) but returned to clinic management when the trial ended were included in the study. The primary outcome variable was the difference in anticoagulation control (measured using the time in therapeutic range) between the two periods. A group of patients who were managed solely by the anticoagulation clinic served as the control.

Results

There was no significant difference in median time in therapeutic range (TTR) between the 52 patients during clinic management post-PST and the six month period of PST (75% vs 75.3%; p = 0.061). Patients tested more frequently while home-testing compared with the subsequent six month period of clinic management (once every 5.6 ± 0.7 days compared with once every 23.2 ± 7.4 days; p = 0.000). Patients with previous experience of PST performed significantly better than the control group of patients (n = 107) that were managed solely by the anticoagulation clinic (75% vs 59.7%; p = 0.009) despite less frequent monitoring of the INR (every 23.2 ± 7.4 days vs. 17.4 ± 6.7 days; p = 0.000).

Conclusions

The improvements in anticoagulation control observed during a period of PST can be sustained when patients cease home-testing and revert back to usual care management.     

Venlafaxine or a second SSRI: Switching after treatment failure with an SSRI among depressed inpatients: a retrospective analysis

Background

Approximately 50% of patients with major depressive disorder (MDD) do not respond after adequate first-line treatment with a selective serotonin reuptake inhibitor (SSRI). Special interest is paid to whether specialist level inpatient psychiatric care results differ from community studies.

Aim

To compare switching alternatives after treatment failure with an SSRI; switching to venlafaxine (Dexcel Pharma Israel) versus switching to another SSRI in depressed inpatients.

Method

A retrospective register study of inpatients was undertaken in a psychiatric tertiary care university center serving an urban catchment area in Israel with a population of more than 900,000.

Results

A total of 401 MDD inpatients were assigned to antidepressant treatment. Of these, 232 records (47 venlafaxine, 185 SSRI) were included in the analysis. Patients assigned to venlafaxine treatment were older (mean age 64.3 ± 15 years versus 53.6 ± 17; p < 0.01) and had more comorbid physical disorders (80% versus 57%; p < 0.001).In the primary analysis, there was no statistical difference between groups in reduction in CGI-S total scores. The secondary end point of achieving a CGI-S score of 2 or less (1 = normal, not at all ill or 2 = borderline mentally ill) was statistically significantly better for the venlafaxine treated inpatients (P = 0.02). AEs were reported less than 10% of patients in both groups.

Conclusion

Patients who remain severely depressed following treatment with an SSRI may gain benefit from the dual-action drug venlafaxine, rather than switching to another SSRI. These findings need to be further supported by prospective studies.     

Verbal learning contributes to cognitive insight in schizophrenia independently of affective and psychotic symptoms

Objective

Patients with schizophrenia exhibit distorted beliefs and experiences, and their own evaluation of this is labeled cognitive insight. We examined the relationship between cognitive insight and neurocognition, as well as the contribution of neurocognition in explaining cognitive insight.

Method

Clinically characterized patients with schizophrenia (n = 102) were assessed with a measure of cognitive insight, Beck Cognitive Insight Scale (BCIS) and a neuropsychological test battery. The contribution of neurocognition to the explained variance in BCIS components self-reflectiveness (i.e. objectivity and reflectiveness) and self-certainty (i.e. overconfidence in own beliefs) was examined controlling for current affective and psychotic symptoms.

Results

A significant negative correlation was found between self-certainty and verbal learning, whereas no associations were found between self-reflectiveness and any of the neuropsychological tests. Verbal learning was added significantly to the explained variance in self-certainty after controlling for potential confounders.

Conclusion

High self-certainty was associated with poor verbal learning. This suggests that overconfidence in own beliefs is associated with cognitive dysfunction in schizophrenia.     

Characterisation and reproducibility of a human ex vivo model of thrombosis

Background

The Badimon chamber is a clinical ex vivo model of thrombosis that mimics flow conditions within the coronary circulation of man. The aims of this study were to characterise thrombus formation in the chamber and evaluate its reproducibility.

Methods

Using blood from 24 healthy human volunteers, thrombus formation was assessed at low and high shear rates with porcine aortic tunica media as the thrombogenic substrate. Thrombus area was measured histomorphometrically. Reproducibility was assessed by paired measurements made both within and between days. Platelet activation was assessed before and at selected points within the extracorporeal circuit using flow cytometry, and fibrin content and distribution within the thrombus were assessed by immunohistochemistry.

Results

Total thrombus area was highly reproducible within and between days in the low shear ([mean thrombus area, mean difference ± SEM] 8,018 μm², 58 ± 204 μm² and 8,177 μm², -154 ± 168 μm² respectively) and high shear chambers (11,802 μm², -52 ± 175 μm² and 11,877 μm², 220 ± 181 μm² respectively). Total thrombus area was greater in the high compared to the low shear chamber (11,970 ± 285 μm²versus 7,892 ± 298 μm²; P < 0.0001). Transit through the extracorporeal circuit did not result in platelet activation which was only detected after blood passed across the perfusion chambers (P = 0.02 for platelet-monocyte aggregate formation and P = 0.05 for P-selectin expression). Thrombus in the low shear chamber contained a greater proportion of fibrin (25.0 ± 6.0% versus 8.3 ± 1.6%, P < 0.001).

Conclusions

The Badimon chamber provides a highly reproducible technique for the assessment of ex vivo platelet-rich thrombus formation in man.     

Purification, biochemical properties and antithrombotic effect of a novel Streptomyces enzyme on carrageenan-induced mice tail thrombosis model

Introduction

The prevalence of cardiovascular diseases, one of the major causes of worldwide mortality, is being increasingly reported. Safer, more effective, and less expensive thrombolytic drugs can possibly overcome the underlying problems associate with current thrombolytic drugs.

Methods

A thrombolytic enzyme was purified and characterized from a Streptomyces strain. Carrageenan induced tail-thrombosis mice model was used to evaluate in vivo antithrombotic effect of the enzyme.

Results

First 15 N-terminal amino acids of the purified enzyme were IAGGQAIYAGGGRRS, which are significantly different from the reported fibrinolytic enzymes. The enzyme exhibited 14.3 ± 2.3-fold stronger thrombolytic activity than that of plasmin. In carrageenan induced tail-thrombosis model, the enzyme caused reduction in frequency of thrombus. Tail-thrombus of the enzyme treated group was significantly shorter than the physiological saline treated group and the thrombus decrement was correlated with the enzyme dose.

Conclusions

The enzyme purified from the Streptomyces strain can be a potential candidate for the treatment of thrombosis.     

Bivalirudin is inferior to heparin in preservation of intraoperative autologous blood

Introduction

Bivalirudin is used as an alternative to heparin in cardiac surgery, and may be superior to heparin with regard to platelet function. Bivalirudin however, is prone to cleavage by thrombin resulting in coagulation in areas of stasis.

Material and Methods

We compared the preservation of platelet function and the quality of anticoagulation in autologous blood of 26 cardiac surgical patients collected intraoperatively and anticoagulated ex vivo with either bivalirudin or heparin, with supplementation of bivalirudin over time and prevention of stasis.

Results

We found in both preservatives a reduction in ADP-induced platelet aggregation response over a period of 105 minutes (median, IQR: 73-141) as measured by Multiplate®. Supplementation of additional bivalirudin (23 ± 1.1 μg/ml/hr) and prevention of stasis was not able to prevent thrombin generation. We found a 5-fold increase in levels of prothrombin fragment 1 + 2 in bivalirudin preserved autologous blood as compared to heparin preserved blood (F₁₊₂ levels median 8.9 nM [quartile percentiles 4.2-12.4] vs 1.3 nM [0.6-2.1], P = 0.001 Mann-Whitney, n = 10).

Conclusions

Our study suggests that preservation of platelet function in autologous blood anticoagulated with bivalirudin is not a suitable alternative to heparin.     

Pioglitazone inhibits platelet function and potentiates the effects of aspirin: a prospective observation study

Background

Thiazolidinediones (TZDs) are agonists of PPARγ and exert beneficial metabolic effects in patients with diabetes. They may also affect platelet function.

Objectives

To characterize potential platelet inhibitory effect of pioglitazone alone and in the presence of aspirin.

Methods

20 normal and 20 diabetic subjects were enrolled in a prospective study. On day 1, a blood sample was obtained at baseline and a second one after ingestion of 30 mg of pioglitazone. PRP was prepared and platelet aggregation and release were evaluated using ADP, collagen and arachidonic acid as agonists. Subjects returned at 6-9 days later after ingesting a single 81 mg dose of aspirin and a third blood sample was obtained. The subjects then again ingested 30 mg of pioglitazone and a fourth and final blood sample was obtained. Platelet aggregation and release were measured. PRP was incubated with thrombin to activate platelets, and the serum was separated and assayed for thromboxane B2, TGFβ and CD40L

Results

Pioglitazone alone did not affect aggregation with arachidonic acid. However, following ingestion of both aspirin and pioglitazone aggregation was significantly decreased compared to aspirin alone (P < 0.0001). Pioglitazone also potentiated aspirin-induced inhibition of ATP release using either arachidonic acid or collagen. Following pioglitazone alone, TXB₂ release was 32,719 ± 3,585 pg/ml which was significantly reduced compared to baseline (42,075 ± 4,479, P = 0.0004). Pioglitazone also potentiated the inhibition of TXB₂ release by aspirin.

Conclusion

Pioglitazone inhibits platelet function and potentiates the inhibitory effects of aspirin.     

Endothelial, platelet, and tissue factor-bearing microparticles in cancer patients with and without venous thromboembolism

Background

Cancer is a prothrombotic state, with an increased prevalence of venous thromboembolism (VTE). Microparticles (MPs) are sub-micron-sized vesicles derived from activated or apoptotic cells that may play a role in VTE, although evidence of this association is still limited.

Objectives

To evaluate the hypothesis that elevated numbers of endothelial (EMPs), platelets (PMPs), and Tissue Factor-bearing MPs (TF⁺MPs) in plasma may contribute to cancer-associated thrombosis.

Patients/Methods

EMPs, PMPs and TF⁺MPs plasma levels were measured in 90 consecutive patients (cases) referred to our Department (30 with a first episode of unprovoked VTE; 30 with active cancer; 30 with a diagnosis of acute VTE associated with active cancer), and in a group of 90 healthy subjects (controls). MPs analyses were performed by flow-cytometry (Cytomics FC500).

Results

Cases showed statistically significant higher (mean ± SD) circulating EMPs and PMPs plasma levels (920 ± 341 and 1221 ± 413 MP/μL, respectively) than controls (299 ± 102 and 495 ± 241 MP/μL; p < 0.005). Moreover cancer patients (with and without VTE) showed higher (mean ± SD) TF⁺MPs (927 ± 415 MPs/μL) than controls (204 ± 112 MPs/μL; p < 0.001). The subgroup of cancer patients plus VTE showed statistically significant higher TF⁺MPs plasma levels (1019 ± 656 MPs/μL) than cancer patients without VTE (755 ± 391 MPs/μL, p = 0.002). Multivariate analysis failed to show a significant association between elevated TF⁺MPs and VTE in cancer patients.

Conclusions

Our results suggest that MPs might be an important intermediate in the cascade of cellular injury and vascular dysfunctions underlying the process of thrombosis, particularly in cancer. Further clinical investigations are needed to confirm the precise role of MPs in predicting hypercoagulable state in patients with cancer.     

Extracorporeal cardiopulmonary support may be an efficient rescue of patients after massive pulmonary embolism. An experimental porcine study

Introduction

Treatment of massive pulmonary embolism leading to cardiac arrest is controversial but restitution of circulation within a shorter time is crucial. Cardiopulmonary support and therapeutic hypothermia is an option for cardiac arrest and could be used to treat massive PE. However, hypothermia may influence the effect of the ongoing intrinsic fibrinolysis.

Objectives

To establish a porcine model of massive pulmonary embolism, to show that cardiopulmonary support can rescue pigs with massive pulmonary embolism and to examine the effect of hypothermia on fibrinolysis.

Methods

Pigs ~ 80 kg were anesthetised and prepared for cardiopulmonary support. Repetitive injections of preformed blood thrombi into the right atrium were done until cardiac arrest. Cardiopulmonary support was established and eighteen pigs were randomised into 3 groups: Normothermia (38-39 °C); hypothermia (33-34 °C); or medication with recombinant tissue plasminogen activator. After three hours the pigs were weaned from cardiopulmonary support, and after 15 minutes with spontaneous circulation assassinated and autopsied. Remaining thrombi in the lungs were weighed.

Results

The development of fatal pulmonary embolism was highly reproducible. All 18 pigs could be weaned from cardiopulmonary support and survived more than 15 minutes. The amount of remaining thromboemboli was substantial in all groups and not significantly different between groups. Normothermic group 20.0 ± 2.2 g, Hypothermic group 17.0 ± 3.7 g, and rt-PA group 14.3 ± 3.2 g.

Conclusions

Cardiopulmonary support could rescue pigs with massive pulmonary embolism. Hypothermia did not reduce the emboli but may for other reasons be beneficial. The optimal additional treatment is still unknown but treatment modalities can be tested in this model.     

Sunshine-exposure variation of human striatal dopamine D2/D3 receptor availability in healthy volunteers

Background

In addition to the serotonergic system, the central dopaminergic system has been reported to be correlated with seasonality. The aim of this study was to explore the difference in striatal dopamine D₂/D₃ receptor availability between healthy volunteers who had a high-sunshine exposure and those who had a low exposure.

Methods

Sixty-eight participants were enrolled, and those in the upper and lower quartiles in terms of sunshine exposure were categorized into high- (n = 17) and low-sunshine-exposure (n = 18) subgroups. Single photon emission computed tomography with [¹²³I] iodo-benzamide was used to measure striatal dopamine D₂/D₃ receptor availability.

Results

Striatal dopamine D₂/D₃ receptor availability was significantly greater in the subjects with high-sunshine exposure than in those with low-sunshine exposure (F = 7.97, p = 0.01) after controlling for age, sex, and smoking status.

Limitations

Different subjects were examined at different time points in our study. In addition, the sex and tobacco use distributions differed between groups.

Conclusion

The central dopaminergic system may play a role in the neurobiological characteristics of sunshine-exposure variation.     

Whole blood flow cytometry measurements of in vivo platelet activation in critically-Ill patients are influenced by variability in blood sampling techniques

Introduction

Flow cytometry is often used to measure in vivo platelet activation in critically-ill patients. Variability in blood sampling techniques, which may confound these measurements, remains poorly characterized.

Materials and Methods

Platelet activation was measured by flow cytometry performed on arterial and venous blood from 116 critically-ill patients. We determined how variability in vascular sampling site, processing times, and platelet counts influenced levels of platelet-monocyte aggregates (PMA), PAC-1 binding (for glycoprotein (GP) IIbIIIa), and P-selectin (P-SEL) expression.

Results

Levels of PMA, but not PAC-1 binding or P-SEL expression, were significantly affected by variability in vascular sampling site. Average PMA levels were approximately 60% higher in whole blood drawn from an arterial vessel compared to venous blood (16.2 ± 1.8% vs. 10.7 ± 1.2%, p < 0.05). Levels of PMA in both arterial and venous blood increased significantly during ex vivo processing delays (1.7% increase for every 10 minute delay, p < 0.05). In contrast, PAC-1 binding and P-SEL expression were unaffected by processing delays. Levels of PMA, but not PAC-1 binding or P-SEL expression, were correlated with platelet count quartiles (9.4 ± 1.6% for the lowest quartile versus 15.4 ± 1.6% for the highest quartile, p < 0.05).

Conclusions

In critically-ill patients, variability in vascular sampling site, processing times, and platelet counts influence levels of PMA, but not PAC-1 binding or P-SEL expression. These data demonstrate the need for rigorous adherence to blood sampling protocols, particularly when levels of PMA, which are most sensitive to variations in blood collection, are measured for detection of in vivo platelet activation.     

The plasma levels of activated thrombin activatable fibrinolysis inhibitor and thrombomodulin in Behçet Disease and their association with thrombosis

Objective

To investigate the plasma levels of activated thrombin activatable fibrinolysis inhibitor (aTAFI) and thrombomodulin (TM) in Behçet disease (BD) and their relationship with thrombosis.

Methods

Plasma aTAFI and TM levels were measured by ELISA in 89 patients with BD (18 having venous thrombosis) and in 86 healthy controls.

Results

Compared with healthy controls, the BD group had significantly lower levels of aTAFI (13.49 ± 8.88 µg/ml vs. 26.76 ± 11.57 µg/ml, p < 0.0001) and significantly higher levels of TM (3.26 ± 1.85 ng/ml vs. 2.6 ± 0.69 ng/ml, p = 0.0003). Neither aTAFI, nor TM levels differed significantly between BD patients with and without thrombosis (p > 0.05). Despite a tendency to positive correlation (r = 0.37, p = 0.0004) between plasma levels of aTAFI and TM in healthy controls, there was a tendency for negative correlation (r = -0.51, p < 0.0001) between these two parameters in BD patients.

Conclusion

The plasma aTAFI and TM levels do not seem to be related with the presence of thrombosis observed in BD. Increased plasma TM levels in BD may simply reflect endothelial cell activation and dysfunction.     

Pain due to osteoarthritis may impair the early outcome of deep brain stimulation in Parkinson's disease

Objective

To analyse postoperative pain due to osteoarthritis in patients with Parkinson's disease submitted to bilateral subthalamic nucleus stimulation.

Methods

Fifty-three parkinsonian patients (mean age, 59.9 ± 8.3 years; mean disease duration, 11.5 ± 4.2 years) referred for subthalamic nucleus stimulation were enrolled. Patients were prospectively asked to refer and describe any pain due to osteoarthritis they experienced at any time during the preoperative period and within the 6 postoperative months. Pre-existing pain due to osteoarthritis, therapeutic changes, parkinsonian motor disability and weight gain were assessed as explanatory factors for occurrence pain due to osteoarthritis after surgery.

Results

After surgery, thirty patients (57%) complained of pain due to osteoarthritis whereas all demonstrated great functional improvement. Twenty (67%) among the 30 experienced similar pain sensation before surgery. Symptoms occurred rapidly, between 4 and 26 postoperative weeks. Multiple stepwise regression analysis showed that pre-existing pain due to osteoarthritis, 6-month postoperative UPDRS III motor score and axial sub-score improvements in the off-drug/on-stimulation condition were accurate independent predictors of pain due to osteoarthritis after surgery (F(8, 41) = 2.20, p < 0.047).

Conclusion

Our results highlight the high prevalence of pain due to osteoarthritis arising shortly after subthalamic implantation. An accurate pain and osteo-articular assessment should be performed preoperatively in parkinsonian candidates for subthalamic nucleus stimulation in order to limit occurrence of complications in the early postoperative period.