Development Of Arterial Thrombosis Research Articles

Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratio as novel prognostic biomarkers in BCR-ABL negative myeloproliferative neoplasms.

Higher neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been associated with increased risk of thrombosis, cardiovascular mortality, but their role in myeloproliferative neoplasms (MPN) remains unclear. We analyzed NLR and PLR as prognostic markers for thrombosis and overall survival (OS) in the study that included 461 consecutive MPN patients who were diagnosed from 2018 to 2022 at University center. Twenty age-matched patients without hematological disorder were used as controls. NLR and PLR were significantly increased in whole MPN group compared to controls. NLR was highest in PV > PMF > ET (p < 0.001) while PLR was highest in ET > PMF > PV (p < 0.001). Thrombosis occurrence during follow-up correlated with NLR, NLR ≥ 4.5, presence of ≥ 2 CV factors and previous thrombosis. Arterial thrombosis was associated with previous thrombosis, NLR and NLR ≥ 4.5. Similarly in venous thrombosis previous thrombosis was risk factor, together with NLR, NLR ≥ 4.5, PLR, but also secondary malignancy and female gender. In multivariate Cox model, most important factors for thrombosis development during follow-up were previous thrombosis, NLR ≥ 4.5 and PLR ≥ 500; for arterial thrombosis, NLR ≥ 4.5 and previous thrombosis; for venous thrombosis PLR ≥ 500 and previous thrombosis. Patients with pre-PMF had significantly higher NLR than ET patients. In multivariate Cox regression model, most important factors associated with survival were NLR ≥ 4.5 and PLR ≥ 500. This study highlights strong prognostic correlation of NLR ≥ 4.5 and PLR ≥ 500 with development of thrombosis and OS in MPN. Besides previous thrombosis, most important factor associated with development of arterial thrombosis is NLR ≥ 4.5 and for venous PLR ≥ 500. Our results revealed that NLR ≥ 4.5 could be used as additional marker to distinguish ET from prePMF.

Deficiency of Natural Anticoagulants Involves in the Occurrence of Arterial Thrombosis

Background The role of natural anticoagulant deficiency in the development of arterial thrombosis (AT) is controversial. Objective Our objectives were to assess the deficiency of natural anticoagulants, including protein S (PS), protein C (PC), antithrombin III (AT III) and their involvement in the occurrence of AT. Design Retrospective cross-sectional study. Methods This study was conducted in 585 patients who were examined with PS, PC, and AT III tests. The activity of PC, PS (men, women), and ATIII under 70%, 75%, 60%, and 80% was recognized as a deficiency, respectively. Peripheral blood cell and coagulation tests were performed before starting treatment. Patients with previous AT, venous thromboembolism (VTE) or anticoagulant therapy were excluded. Results Patients without thrombosis were 222 (38%), patients with newly diagnosed VTE were 281 (48%), and patients with newly diagnosed AT were 82 (14%). The most common AT sites were in the lungs, brain, and lower extremities (31.2%, 20.8%, and 20.8%, respectively). Compared to the nonthrombosis group, the AT group had a lower PS activity (%) (82.77 ± 24.09 vs 91.31 ± 27.27), a higher fibrinogen (g/L) (4.25 ± 1.68 vs 3.74 ± 1.51), a higher D-dimer (mg/L FEU) (6.16 vs 1.95), and a higher neutrophil count (G/L) (8.57 vs 6.50) with P &lt; .05. Compared to the VTE group, the AT group had higher hemoglobin (g/L) (135.95 ± 23.75 vs 129.02 ± 25.22) and a higher neutrophil count (G/L) (8.57 vs 7.28) ( P &lt; .05). In the AT group, the frequencies of PC, PS, and AT III deficiency were 23.1%, 28%, and 17.1%, respectively. The AT group had a higher frequency of PS deficiency than the nonthrombosis group (28% vs 17.1%, P = .035). Patients with PS deficiency had a higher risk of AT compared to those without PS deficiency (OR = 1.888, 95% CI [1.041-3.422], P = .036). Conclusion PS deficiency may be considered a factor in increasing the risk of AT.

Results of thrombectomy in lower-extremity ischemia in patients with COVID-19 and respiratory failure of different severity

Aim. To analyze the results of thrombectomy in lower-extremity ischemia in patients with coronavirus disease 2019 (COVID-19) and respiratory failure of different severity.Material and methods. This retrospective, cohort, comparative study for the period from May 1, 2020 to March 1, 2022 included 305 patients with acute lower-extremity ischemia and COVID-19. Depending on the type of oxygen support, three groups of patients were formed: group 1 (n=168) — nasal oxygen insufflation; group 2 (n=92) — non-invasive ventilation (NIV); group 3 (n=45) — artificial ventilation (AV). Thrombectomy was carried out according to the standard technique using Fogarty catheters (3F-6F — depending on the vessel size). After the diagnosis was established before and after the start of surgical treatment, all patients received the following therapy: Unfractionated IV heparin infusion at an initial rate of 1000 U/r, adjusted to maintain the activated partial thromboplastin time at 2-3 times the normal value; 2. Oral acetylsalicylic acid 125 mg; 3. Analgesics.Results. Myocardial infarction and ischemic stroke were not detected in the total sample. The highest number of deaths (group 1: 5,3%, n=9; group 2: 72,8%, n=67; group 3: 100%, n=45; p&lt;0,0001), retrombosis (group 1 : 18,4%, n=31; group 2: 69,5%, n=64; group 3: 91,1%, n=41; p&lt;0,0001) and limb amputations (group 1: 9,5%, n=16; group 2: 56,5%, n=52; group 3: 91,1%, n=41; p&lt;0,0001) was recorded in group 3 patients.Conclusion. In patients receiving mechanical ventilation, COVID-19 have more aggressive course, which is expressed in an increase in laboratory para- meters (C-reactive protein, ferritin, interleukin-6, D-dimer), the severity of pneumonia and location of thrombosis in the tibial arteries. Among patients with COVID-19 receiving mechanical ventilation, the greatest number of rethromboses (91,1%), limb amputations (91,1%), and deaths (100%) are noted, which suggests the expediency of abandoning open thrombectomy in favor of anticoagulant/antiplatelet therapy in this cohort of patients. The development of arterial thrombosis in patients with COVID-19 receiving mechanical ventilation is an indicator of a high risk of death. Open thrombectomy in combination with anticoagulant/antiplatelet therapy is most effective in patients on nasal oxygen insufflation or NIV.

Results of treatment of acute arterial thrombosis in patients with severe course of coronavirus infection COVID-19

Acute arterial thrombosis against the background of the novel coronavirus infection COVID-19 is an unfavorable complication. The survival prognosis in this category of patients is much worse than in the rest of the patient population. The aim of the work is to compare the immediate results of various methods of treating acute arterial insufficiency in patients with the novel coronavirus infection COVID-19, complicated by the development of acute arterial thrombosis of various localizations. 42 clinical cases of treatment of acute arterial pathology in patients with confirmed COVID-19 infection were analyzed. The severity of the underlying disease was not considered as a criterion for exclusion from the study. Surgical treatment by open intra-arterial thrombectomy under local anesthesia was used in 9 patients. Endovascular balloon angioplasty of arteries followed by selective catheter-guided thrombolysis with alteplase was performed in 17 patients. Sixteen patients received systemic transvenous thrombolysis with the recombinant human tissue plasminogen activator alteplase at a dose of 100 mg. The development of arterial thrombosis against the background of the coronavirus infection is accompanied by a high risk of death in the absence of timely and active specialized care. In the study group, 18 patients (43 %) with acute arterial thrombosis associated with COVID-19 deceased; of these, eight patients underwent open thrombectomy, eight patients had systemic transvenous thrombolysis with alteplase, and two patients underwent endovascular balloon angioplasty with selective catheter-guided thrombolysis with alteplase. A favorable outcome of the disease was noted in 24 patients (57 %); of these, fifteen patients underwent endovascular balloon angioplasty with selective catheter-guided thrombolysis with alteplase, and 8 patients had systemic thrombolysis with alteplase. Optimal treatment results were achieved in the group of patients using minimally invasive endovascular treatment methods in combination with tissue plasminogen activator. In the group of non-transportable patients with grade 3 respiratory failure and high perioperative risks, positive results were achieved exclusively through the use of systemic transvenous thrombolysis. These data allow us to consider justified the use of options for systemic thrombolysis and selective catheter thrombolysis in combination with endovascular reconstruction as an alternative to «open» surgical methods for thevtreatment of acute arterial insufficiency against the background of COVID-19.

Targeting Myeloid-Cell Specific Integrin α9β1 Inhibits Arterial Thrombosis in Mice

Background: Coordinated interactions between neutrophils, platelets and endothelial cells contribute towards the development of arterial thrombosis. Neutrophils along with platelets are the first immune cells that are recruited at the site of endothelial activation/injury or infection. Recent studies have suggested that neutrophils modulate thrombosis via several mechanisms, including NETosis (formation of neutrophil extracellular traps). The integrin α9 is highly expressed on neutrophils while platelets do not express it. The integrin α9 up-regulated upon neutrophil activation and is implicated in stable adhesion and transmigration. The mechanisms underlying the role of integrin α9 towards the progression of arterial thrombosis has not been explored yet. Objective: To elucidate the mechanistic insights into the role of myeloid-cell specific integrin α9 in neutrophil adhesion and arterial thrombosis. Methods: We generated novel myeloid-specific α9-/- mice (α9fl/fl LysMcre+l-) by crossing α9fl/fl with LysMcr+/+mice. Littermates α9fl/flLysMcre-l-mice were used as controls. Standardized in vitro assays were used to evaluate the role of integrin α9 in neutrophil mediated platelet aggregation, NETosis and Cathepsin-G release. Susceptibility to arterial thrombosis and hemostasis was evaluated in vivo (FeCl3-induced carotid and laser-injury induced mesenteric artery thrombosis models) by utilizing intravital microscopy and tail bleeding assay respectively. Results: α9fl/flLysMCre+/-mice developed smaller thrombi (~40% occlusion), when compared with α9fl/flmice (~80% occlusion, 10 minutes post-FeCl3 induced injury). The mean time to complete occlusion was significantly prolonged in α9fl/flLysMCre+/-mice (P&amp;lt;0.05 vs α9fl/fl mice). Consistent with this, α9fl/flLysMCre+/-mice displayed significantly decreased platelet mean fluorescence intensity (MFI) and reduced rate of thrombus growth in laser injury-induced thrombosis model (P&amp;lt;0.05 vs. α9fl/fl mice). Together, these results suggest that myeloid cell-specific integrin α9 contributes to the experimental thrombosis at arterial shear rates. Monocytes depletion experiments demonstrated a minimal role for monocyte in progression of arterial thrombosis. In vitro mechanistic studies demonstrated a reduction in neutrophil-mediated platelet aggregation and cathepsin-G secretion in myeloid cell-specific integrin α9-/- mice, when compared with litter-mates control wild-type mice. Notably, the percentage of cells releasing NETs was markedly reduced in myeloid cell-specific integrin α9-/- mice that was concomitant with reduced MPO levels in carotid thrombus of α9fl/flLysMCre+/-mice. Together, these results suggest most likely integrin α9 expressed on neutrophils, but not monocytes, promotes arterial thrombosis. Comparable tail bleeding time between α9fl/flLysMcreand littermate α9fl/fl mice suggested that myeloid-cell specific deficiency of integrin α9 does not alter hemostasis. Conclusion: These findings reveal a novel role for integrin α9 in modulation of arterial thrombosis. While the clinical implications of these findings remains to be explored, we suggest that targeting integrin α9 may reduce post reperfusion thrombo-inflammatory injury, following acute myocardial infarction or stroke. Disclosures No relevant conflicts of interest to declare.

Arterial Thrombosis Is Accompanied by Elevated Mitogen-Activated Protein Kinase (MAPK) and Cyclooxygenase-2 (COX-2) Expression via Toll-Like Receptor 4 (TLR-4) Activation by S100A8/A9.

BackgroundThe aim of this study was to determine the involvement of S100A8/A9 in the development of arterial thrombosis.Material/MethodsA total of 303 patients were enrolled in this study, with 110 having acute coronary syndrome (ACS) and 110 having coronary heart disease (CHD), and 83 subjects served as healthy blood donors. The concentrations of Toll-like receptor 4 (TLR-4), cyclooxygenase-2 (COX-2), and S100A8/A9 protein were determined in the sera of the participants and in peripheral blood mononuclear cells (PBMCs) derived from a rat carotid artery thrombosis model and in human aortic endothelial cells (HAECs). The mitogen-activated protein kinase (MAPK) inhibitor SB203580 and the TLR-4 blocker CLI-095 were used to investigate the role of the TLR-4-MAPK-COX2 signaling axis in thrombosis.ResultsThe levels of COX-2, TLR-4, and S100A8/A9 in the sera of patients with ACS and CHD were significantly higher than in healthy controls (P<0.05). S100A8/A9 expression was significantly correlated with TLR-4 and COX-2 in the ACS group and with TLR-4 in the CHD group. In the rat carotid thrombosis model, the expressions of TLR-4, COX-2, and p-p38 MAPK significantly increased until 14 days after thrombosis induction, whereas S100A8/A9 expression increased until day 7, but then decreased. Administration of SB203580 to rats reduced COX-2 expression in PBMCs after thrombosis induction, and incubation of HAECs with CLI-095 reduced their p-p38 MAPK and COX-2 response to S100A8/A9 stimulation.ConclusionsS100A8/A9 is upregulated after blood vessel injury and is enhanced in combination with TLR-4 COX-2 induction via p38 MAPK activation.

Association between antiphospholipid antibodies and arterial thrombosis in patients with rheumatoid arthritis.

Antiphospholipid antibodies (aPL) are present in a proportion of patients with rheumatoid arthritis but their clinical significance remains unclear. We investigated the association between aPL and thrombotic events in rheumatoid arthritis patients. In this cross-sectional study, aPL profiles were evaluated in 376 rheumatoid arthritis patients in accordance with the standard guidelines. Clinical and radiographic data were retrospectively collected. aPL were identified in 39 patients (10.4%). Lupus anticoagulant was the most common subtype (n = 25, 6.6%); anti-cardiolipin antibodies and anti-β2 glycoprotein I antibodies were detected in six and 12 patients (1.6% and 3.2%), respectively. Compared to the aPL-negative group, aPL-positive patients included more male patients (41.0% vs. 15.4%, P < 0.001) and more smokers (41.0% vs. 16.0%, P = 0.001). There was no difference between the two groups in age, disease duration and body mass index, or the frequency of diabetes, hypertension or dyslipidaemia. Of note, arterial thromboses were more common in the aPL-positive than the aPL-negative group (12.8% vs. 2.1%, P = 0.004), whereas the frequency of venous thrombosis did not differ between the two groups (0.0% vs. 0.9%, P = 1.000). On multivariate regression analysis, aPL, age, hypertension, dyslipidaemia and baseline C-reactive protein level were independently associated with arterial thrombotic events (all P values < 0.05). aPL was found in a subset of rheumatoid arthritis patients, who were more often smokers, and aPL was independently associated with development of arterial thrombosis. This result suggests that aPL may contribute to an increased risk of arterial thrombosis in rheumatoid arthritis patients.

Microparticles as new markers of cardiovascular risk in diabetes and beyond.

The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called "plaque" MPs. Otherwise, circulating MPs represent a TF reservoir, named "blood-borne" TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. "Blood-borne" TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients.

A mouse model to study thrombotic complications of thalassemia

Patients with β-thalassemia major and mainly intermedia have an increased risk for developing venous and arterial thrombosis which may be related to circulating pathological red blood cells (RBC) and continuous platelet activation. In the present study we used a modified thalassemic mice model in conjunction with a "real-time" carotid thrombus formation procedure to investigate thrombotic complications of thalassemia. Heterozygous Th3/+ mice, which lack one copy of their β-major and β-minor globin genes, exhibit anomalies in RBC size and shape, chronic anemia and splenomegaly which recapitulate the phenotype of human β-thalassemia intermedia. Flow cytometry measurements showed higher reactive oxygen species generation, indicating oxidative stress, in platelets and RBC of the thalassemic mice compared with wild type mice concomitant with an increase in reduced glutathione content which may represent a compensatory response to oxidative stress, and exposed phosphatidylserine which indicates platelet activation. To elucidate the effect of thalassemia on the development of arterial thrombosis, we studied photochemical-induced real-time thrombus formation in the carotid artery of these mice. The results indicated a significantly shorter "time to occlusion" in the thalassemic mice compared to wild type mice, which was prolonged following in vivo aspirin treatment. We suggest that this mouse model may contribute to our understanding of platelet activation and the hypercoagulable state in thalassemia and lay foundations to screening of anti-platelet drugs as well as anti-oxidants as possible therapeutics for prevention of thrombosis in thalassemia patients.

Síndrome coronario agudo con y sin elevación del segmento ST: ¿cómo darles igualdad de oportunidades?

La activación y la agregación plaquetarias son clave en la progresión de la trombosis rterial y el principal objetivo terapéutico del manejo del síndrome coronario agudo. Actualmente, además de inhibir la formación de tromboxano A 2 con ácido acetilsalicílico, se recomienda inhibir otra vía complementaria de la agregación plaquetaria para asegurar la eficacia del tratamiento y prevenir la trombosis coronaria. Los profármacos tienopiridínicos, como clopidogrel y prasugrel, y el derivado pirimidínico ticagrelor son las alternativas más extendidas. En esta revisión se discuten las indicaciones de estos fármacos antiagregantes y su evidencia científica en relación con el síndrome coronario agudo con y sin elevación del segmento ST. Platelet activation and aggregation play key roles in the development of arterial thrombosis. Accordingly, they provide the principle therapeutic targets in patients with acute coronary syndrome. At present, in addition to using aspirin to inhibit the formation of thromboxane A 2 , it is also recommended that another complementary platelet aggregation pathway should be inhibited to ensure that treatment is effective and to prevent coronary thrombosis. Thienopyridine prodrugs, such as clopidogrel and prasugrel, and the pyrimidine derivative ticagrelor are the most widely used agents. This review includes a discussion of indications for these antiplatelet drugs and summarizes the scientific evidence for their use in patients with acute coronary syndrome, with or without ST-segment elevation.

Differentiating haemostasis from thrombosis for therapeutic benefit

The central role of platelets in the formation of the primary haemostatic plug as well as in the development of arterial thrombosis is well defined. In general, the molecular events underpinning these processes are broadly similar. Whilst it has long been known that disturbances in blood flow, changes in platelet reactivity and enhanced coagulation reactions facilitate pathological thrombus formation, the precise details underlying these events remain incompletely understood. Intravital microscopy studies have highlighted the dynamic and heterogeneous nature of thrombus development and demonstrated that there are considerable spatiotemporal differences in the activation states of platelets within a forming thrombus. In this review we will consider the factors regulating the activation state of platelets in a developing thrombus and discuss how specific prothrombotic factors may influence this process, leading to excessive thrombus propagation. We will also discuss some potentially novel therapeutic approaches that may reduce excess thrombus development whilst minimising bleeding risk.

1122 The Effect of Heparin Infusion on Development of ThrombosİS Secondary to Cardiac Catheterization

Background and AimCardiac catheterization is an important diagnostic tool. In this study, the frequency and the factors affecting the development of thrombosis were prospectively evaluated in neonates who were subjected...

Diagnosis and treatment of platelet hyperactivity in relation to thrombosis in dogs and cats

To review the mechanisms of platelet activation and options for diagnosing and treating platelet hyperactivity in relation to thrombosis in dogs and cats. Prospective, retrospective, and review articles, as well as textbook chapters in both human and veterinary medicine. Articles were primarily, but not exclusively, retrieved via Medline. In people, platelets are known to play a key role in the development of arterial thrombosis in numerous disease states and antiplatelet drugs are the cornerstone in the treatment of acute events and for prevention in patients at risk. For many years, aspirin was used as the sole antiplatelet drug in people, but the introduction of adenosine diphosphate receptor antagonists and integrin α(IIb) β(3) inhibitors has significantly improved outcome in selective groups of patients. The understanding of platelet activation in disease states has increased dramatically over the past decade. Simultaneously, a host of new methods for evaluating platelet function have been developed, which enable primarily researchers, but also clinicians to monitor the activity of platelets. Many of these methods have been validated for research purposes, but few have found their way to the clinics. Not a single correctly randomized clinical trial has been carried out with any antiplatelet drug for any indication in dogs or cats, and consequently, treatment is empiric and largely based on expert opinion or data from experimental studies. The pathogenesis of thromboembolic disease is complex and multifactorial and the role of hyperactive platelets in this etiology remains to be clarified in most of the diseases associated with thrombosis in dogs and cats. Until efficacy data from well-designed studies are available, antithrombotic therapy should consist of close monitoring, good supportive care, and judicious empirical use of antiplatelet agents.

A role for adhesion and degranulation‐promoting adapter protein in collagen‐induced platelet activation mediated via integrin α2β1

Collagen-induced platelet activation is a key step in the development of arterial thrombosis via its interaction with the receptors glycoprotein (GP)VI and integrin α(2) β(1) . Adhesion and degranulation-promoting adapter protein (ADAP) regulates α(IIb) β(3) in platelets and α(L) β(2) in T cells, and is phosphorylated in GPVI-deficient platelets activated by collagen. To determine whether ADAP plays a role in collagen-induced platelet activation and in the regulation and function of α(2) β(1). Using ADAP(-/-) mice and synthetic collagen peptides, we investigated the role of ADAP in platelet aggregation, adhesion, spreading, thromboxane synthesis, and tyrosine phosphorylation. Platelet aggregation and phosphorylation of phospholipase Cγ2 induced by collagen were attenuated in ADAP(-/-) platelets. However, aggregation and signaling induced by collagen-related peptide (CRP), a GPVI-selective agonist, were largely unaffected. Platelet adhesion to CRP was also unaffected by ADAP deficiency. Adhesion to the α(2) β(1) -selective ligand GFOGER and to a peptide (III-04), which supports adhesion that is dependent on both GPVI and α(2) β(1), was reduced in ADAP(-/-) platelets. An impedance-based label-free detection technique, which measures adhesion and spreading of platelets, indicated that, in the absence of ADAP, spreading on GFOGER was also reduced. This was confirmed with non-fluorescent differential-interference contrast microscopy, which revealed reduced filpodia formation in ADAP(-/-) platelets adherent to GFOGER. This indicates that ADAP plays a role in mediating platelet activation via the collagen-binding integrin α(2) β(1). In addition, we found that ADAP(-/-) mice, which are mildly thrombocytopenic, have enlarged spleens as compared with wild-type animals. This may reflect increased removal of platelets from the circulation.

Limb amputation among patients with surgically treated popliteal arterial injury: analysis of 15years of experience in an urban trauma center in Cali, Colombia.

Popliteal arterial injuries carry a high risk of amputation. The currently available literature from both civilian and military experiences is characterized by a wide variation of recommendations for surgical management. We questioned how these recommendations have been applied in our practice. Therefore, we aimed to identify predictors of amputation after popliteal arterial injury. We conducted an observational study of 175 patients with popliteal arterial injuries who underwent surgical treatment from 1992 to 2006 at a level I trauma center in Cali, Colombia. Information on demographic characteristics, clinical information, and surgical management was collected from clinical records. The outcome measure was amputation within 30days following the first surgical intervention. The amputation rate was 17.1%. A multivariable logistic regression model indicates that blunt mechanism (odds ratio [OR] 4.79, 95% confidence interval [CI] 1.49-15.42), signs of ischemia (OR 5.29, 95% CI 1.48-18.91), ligation of the popliteal vein of the compromised limb during surgical exploration (OR 3.83, 95% CI 1.20-12.18), and the development of arterial thrombosis (OR 56.51, 95% CI 12.36-258) were found to be independent predictors of amputation. Fractures, popliteal venous injuries, prolonged time between injury and surgery, fasciotomies, and graft arterial repair were not statistically significant predictors of amputation. Emphasis on the early assessment and prompt identification of signs of ischemia after popliteal arterial injury continue to be the most important factor for reducing the risk of amputation, especially in blunt trauma. Vascular trauma teams must emphasize the need for the specialized management of popliteal veins. Clinical research is needed in order to identify means of decreasing arterial thrombosis after popliteal repair.

Epistatic Interactions in Genetic Regulation of t-PA and PAI-1 Levels in a Ghanaian Population

The proteins, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1), act in concert to balance thrombus formation and degradation, thereby modulating the development of arterial thrombosis and excessive bleeding. PAI-1 is upregulated by the renin-angiotensin system (RAS), specifically by angiotensin II, the product of angiotensin converting enzyme (ACE) cleavage of angiotensin I, which is produced by the cleavage of angiotensinogen (AGT) by renin (REN). ACE indirectly stimulates the release of t-PA which, in turn, activates the corresponding fibrinolytic system. Single polymorphisms in these pathways have been shown to significantly impact plasma levels of t-PA and PAI-1 differently in Ghanaian males and females. Here we explore the involvement of epistatic interactions between the same polymorphisms in central genes of the RAS and fibrinolytic systems on plasma t-PA and PAI-1 levels within the same population (n = 992). Statistical modeling of pairwise interactions was done using two-way ANOVA between polymorphisms in the ETNK2, RENIN, ACE, PAI-1, t-PA, and AGT genes. The most significant interactions that associated with t-PA levels were between the ETNK2 A6135G and the REN T9435C polymorphisms in females (p = 0.006) and the REN T9435C and the TPA I/D polymorphisms (p = 0.005) in males. The most significant interactions for PAI-1 levels were with REN T9435C and the TPA I/D polymorphisms (p = 0.001) in females, and the association of REN G6567T with the TPA I/D polymorphisms (p = 0.032) in males. Our results provide evidence for multiple genetic effects that may not be detected using single SNP analysis. Because t-PA and PAI-1 have been implicated in cardiovascular disease these results support the idea that the genetic architecture of cardiovascular disease is complex. Therefore, it is necessary to consider the relationship between interacting polymorphisms of pathway specific genes that predict t-PA and PAI-1 levels.

Clinical Summaries

Clinical Summaries

Platelet Dense-Granule Secretion Plays a Critical Role in Thrombosis and Subsequent Vascular Remodeling in Atherosclerotic Mice

Platelet aggregation plays a critical role in myocardial infarction and stroke; however, the role of platelet secretion in atherosclerotic vascular disease is poorly understood. Therefore, we examined the hypothesis that platelet dense-granule secretion modulates thrombosis, inflammation, and atherosclerotic vascular remodeling after injury. Functional deletion of the Hermansky-Pudlak syndrome 3 gene (HPS3(-/-)) markedly reduces platelet dense-granule secretion. HPS3(-/-) mice have normal platelet counts, platelet morphology, and alpha-granule number, as well as maximal secretion of the alpha-granule marker P-selectin; however, their capacity to form platelet-leukocyte aggregates is significantly reduced (P<0.05). To examine the role of platelet dense-granule secretion in these processes, atherosclerosis-prone mice with combined genetic deficiency of apolipoprotein E and HPS3 (ApoE(-/-), HPS3(-/-)) were compared with congenic, atherosclerosis-prone mice with normal platelet secretion (ApoE(-/-), HPS3(+/+)). After 16 to 18 weeks on a high-fat diet, both groups of mice had similar fasting cholesterol levels and body weight. Carotid arteries of ApoE(-/-), HPS3(+/+) mice thrombosed rapidly after FeCl(3) injury, but ApoE(-/-), HPS3(-/-) mice were completely resistant to thrombotic arterial occlusion (P<0.01). Three weeks after injury, neointimal hyperplasia (from alpha-smooth muscle actin-positive cells) was significantly less (P<0.001) in arteries from ApoE(-/-), HPS3(-/-) mice. In ApoE(-/-), HPS3(-/-) mice, there were also pronounced reductions in arterial inflammation, as indicated by a 74% decrease in CD45-positive leukocytes (P<0.01) and a 73% decrease in Mac-3-positive macrophages (P<0.05). In atherosclerotic mice, reduced platelet dense-granule secretion is associated with marked protection against the development of arterial thrombosis, inflammation, and neointimal hyperplasia after vascular injury.

Antiplatelet agents

The introduction of aspirin as an anti-thrombotic agent some 50 years ago has changed the therapeutic approach in cardiovascular medicine. Since platelets play a key role in the development of arterial thrombosis, antiplatelet drugs serve as a cornerstone in the prevention and the treatment of these conditions. After many years of a "monopoly" of aspirin, ADP receptor P2Y12 inhibitors were introduced with a significant improvement in clinical outcome. Nowadays dual antiplatelet therapy is the common practice for both acute events and secondary prevention in selected groups of patients. Another revolution was the development of potent inhibitors of the platelet integrin GPIIbIIIa, which significantly improved the outcome of percutaneous interventions (PCI), in cardiology. The improved efficacy of multiple-drug therapy is associated with an increased risk of bleeding, which raises the issue of the dosing of these drugs. Recently, numerous studies have reported a variable laboratory response to aspirin and clopidogrel, which correlates with clinical outcome. Several mechanisms have been proposed to cause this variable response, including genetic variability, disease burden and others. A major obstacle in this field is the lack of a standardized method for testing these responses, and thus some studies cannot be compared to others. Ongoing studies are currently investigating the potential translation of these observations into clinical practice. Such studies may lead to a change in the paradigm of antiplatelet therapy, where individual dose adjustment may improve efficacy and safety. Finally, a variety of new drugs are currently in different stages of development, including new P2Y12 receptor inhibitors, thromboxane receptor blockers, direct thrombin inhibitors and other signaling pathway inhibitors including oral GPIIbIIIa inhibitors. Thus, antiplatelet therapy is currently under intensive development toward multiple-drug therapy and personal-dose adjustment, which may improve clinical outcome.

The genetics of antiplatelet drug resistance

Platelets have a central role in the development of arterial thrombosis and subsequent cardiovascular events. An appreciation of this complex process has made antiplatelet therapy the cornerstone of cardiovascular disease management. However, numerous patients will experience a recurrent atherothrombotic vascular event despite adequate antiplatelet therapy. Individual differences in the rate of platelet activation and reactivity markedly influence normal hemostasis and the pathological outcome of thrombosis. Such an individual variability is largely determined by environmental and genetic factors. These are known to either hamper platelets' response to agonists, and thereby mimic the pharmacological modulation of platelet function or mask therapy effect and sensitize platelets. In this article, we reviewed the antiplatelet mechanisms of aspirin and clopidogrel and the possible role of different polymorphisms, which may affect the efficacy of antiplatelet therapy. Heterogeneity in the way patients respond to aspirin and clopidogrel may in part reflect variation in cyclooxygenase (COX)-1, COX-2, glycoprotein (GP) Ib alpha, GP Ia/IIa, GP IIb/IIIa, UGT1A6*2, P2Y(1), P2Y(12), CYP2C9, CYP3A4 and CYP3A5 genotypes.