Plasminogen Activator Inhibitor-1 Activity Levels Research Articles

Fibrinolysis Assessment with Tpa-ROTEM in Patients with Bleeding Disorders of Unknown Cause (BDUC)

Background: In 40-70% of patients referred to the hematologist for evaluation of bleeding symptoms, no cause for their increased bleeding tendency can be found using currently available hemostasis laboratory tests. This group is classified as patients with bleeding disorder of unknown cause (BDUC). The lack of clear guidelines concerning diagnosis, management and genetic counseling in BDUC-patients poses a challenge for patients, family members and treating physicians. Several hemostasis assays have been investigated in BDUC-patients, but little is known about the role of the fibrinolytic pathway in this patient group. This can be explained by the lack of standardized fibrinolysis tests and the limited availability of these tests in laboratories. To further unravel potential bleeding mechanisms in BDUC, in the present study we assessed fibrinolysis in BDUC patients by using a global whole blood tPA ROTEM assay and determining of individual fibrinolysis proteins. Aim: To investigate the capacity of the tPA-ROTEM assay to detect fibrinolytic abnormalities in BDUC-patients and to correlate these findings with fibrinolytic protein activity levels in plasma. Methods: Data from patients referred to the hematologist for bleeding evaluation and included in the Prediction of Evaluation in Adult Hematologic Patients with Bleeding Tendencies (ProBe-AHP) study (METC:14-4-036) were used. BDUC-patients were identified based on (1) a clinically relevant increased bleeding tendency and (2) no abnormalities in extended hemostasis laboratory testing. tPA-ROTEM assay was done according to the in 2016 validated and published method on the ROTEM device. Fibrinolysis protein plasma levels, including plasminogen, plasminogen activator inhibitor 1 (PAI-1) antigen and activity, tissue plasminogen activator (tPA) antigen, alpha2-antiplasmin and thrombin activatable fibrinolysis inhibitor (TAFI), were measured using ELISA assays. Pre-specified definitions of hyper- and hypofibrinolysis as measured by tPA-ROTEM were applied to identify hyper- and hypofibrinolytic profiles. Results: tPA-ROTEM identified a hyperfibrinolytic profile in 15/73 (20%) of BDUC-patients, a hypofibrinolytic profile in 16/73 (22%) of BDUC-patients and a normal profile in 42 BDUC-patients (58%). Plasminogen activity inhibitor 1 (PAI-1) activity and antigen levels and α2-antiplasmin levels were lower in BDUC-patients with a hyperfibrinolytic profile compared to BDUC-patients with a hypofibrinolytic profile. No statistically significant correlations between tPA-ROTEM parameters and fibrinolysis protein plasma levels were identified using multivariate regression analysis. Conclusion: tPA-ROTEM identified a hyperfibrinolytic profile in 20% of BDUC-patients. In this group, the lower PAI-1 activity and antigen levels and lower α2-antiplasmin levels are in concordance with the expected changes in case of hyperfibrinolysis. These findings indicate that these fibrinolysis protein plasma levels are within the lower functional range of their distribution, shifting the balance towards increased clot lysis leading to an increased bleeding tendency. These findings might deliver evidence to the use of antifibrinolytic therapies in BDUC-patients in case of bleeding or interventions. Informed consent and approval from the medical-ethical committee from Maastricht (METC azM/UM) were obtained.

Obesity paradox in acute myocardial infarction: Is plasminogen activator inhibitor 1 the culprit?

The obesity paradox continues to puzzle scientists. The unexpected observation of a higher incidence but more favorable outcomes in obese patients has been described in several cardiovascular and non-cardiovascular conditions. A number of possible causes of the paradox have been proposed. Plasminogen activator inhibitor 1 (PAI-1) has not yet been evaluated in this context. Our study group investigated the prognostic value of PAI-1 dynamics in the early stages of acute ST elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention. A higher rise in PAI-1 activity within 24 h of STEMI was associated with worse long-term outcomes. Within the study population, which involved 87 consecutive patients, we observed a certain pattern of PAI-1 dynamics that may be protective in obese patients. In these patients, initial PAI-1 activity levels were elevated, a fact in line with the higher incidence of acute coronary syndromes in the obese population. However, the increase in PAI-1 activity during first 24 h of STEMI was not as pronounced in obese patients. It is our hypothesis that this correlation may prove protective in this population. If confirmed in larger studies, this observation may provide a piece of the puzzle towards elucidating the origins of the obesity paradox, as well as further promote the development of PAI-1 inhibitors as a viable therapeutic option for STEMI patients.

Application of Machine Learning to Assess Interindividual Variability in Rapid-Acting Insulin Responses After Subcutaneous Injection in People With Type 1 Diabetes

ObjectivesCirculating insulin concentrations mediate vascular-inflammatory and prothrombotic factors. However, it is unknown whether interindividual differences in circulating insulin levels are associated with different inflammatory and prothrombotic profiles in type 1 diabetes (T1D). We applied an unsupervised machine-learning approach to determine whether interindividual differences in rapid-acting insulin levels associate with parameters of vascular health in patients with T1D. MethodsWe re-analyzed baseline pretreatment meal-tolerance test data from 2 randomized controlled trials in which 32 patients consumed a mixed-macronutrient meal and self-administered a single dose of rapid-acting insulin individualized by carbohydrate counting. Postprandial serum insulin, tumour necrosis factor (TNF)-alpha, plasma fibrinogen, human tissue factor (HTF) activity and plasminogen activator inhibitor-1 (PAI-1) were measured. Two-step clustering categorized individuals based on shared clinical characteristics. For analyses, insulin pharmacokinetic summary statistics were normalized, allowing standardized intraindividual comparisons. ResultsDespite standardization of insulin dose, individuals exhibited marked interpersonal variability in peak insulin concentrations (48.63%), time to peak (64.95%) and insulin incremental area under the curve (60.34%). Two clusters were computed: cluster 1 (n=14), representing increased serum insulin concentrations; and cluster 2 (n=18), representing reduced serum insulin concentrations (cluster 1: 389.50±177.10 pmol/L/IU h−1; cluster 2: 164.29±41.91 pmol/L/IU h−1; p<0.001). Cluster 2 was characterized by increased levels of fibrinogen, PAI-1, TNF-alpha and HTF activity; higher glycated hemoglobin; increased body mass index; lower estimated glucose disposal rate (increased insulin resistance); older age; and longer diabetes duration (p<0.05 for all analyses). ConclusionsReduced serum insulin concentrations are associated with insulin resistance and a prothrombotic milieu in individuals with T1D, and therefore may be a marker of adverse vascular outcome.

Plasminogen Activator Inhibitor-1 in poorly controlled vs well controlled Type-2 Diabetes Mellitus patients: A case-control study in a district hospital in Ghana.

Hypofibrinolysis resulting from the up-regulation of plasminogen activator inhibitor-1 (PAI-1) usually occurs in patients with type 2 diabetes mellitus (T2DM), rendering them hypercoagulable. This study assessed the plasma antigen and activity levels of the PAI-1 enzyme in T2DM patients in a district hospital in Ghana. This was a hospital-based case-control study conducted from December 2018 to May 2019 at Nkenkaasu District Hospital. Sixty subjects with T2DM (30 T2DM subjects with good glycemic control and 30 with poor glycemic control), and 30 apparently healthy blood donors were recruited into the study. Blood specimens were collected for complete blood count, lipid profile, PAI-1 Ag and PAI-1 activity levels. A pre-tested questionnaire was used to obtain demographic and clinical information. The data was analyzed using SPSS version 22.0. Elevated PAI-1 Ag and activity levels were observed in the T2DM subjects compared to the healthy controls, with the levels and activity significantly higher (PAI-1 Ag; p< 0.001, PAI-1 activity level; p = 0.004) in the T2DM subjects with poor glycemic control in comparison to those with good glycemic control. A significant positive correlation was observed between HbA1c and PAI-1 enzymes. PAI-1 Ag levels significantly increased along with increased total cholesterol (Β = 0.262, p = 0.033), triglyceride (Β = -0.273, p = 0.034) and HbA1c (Β = 0.419, p = 0.001). Similarly, PAI-1 activity level was associated with total cholesterol (Β = 0.325, p = 0.009), triglyceride (Β = -0.262, p = 0.042), HbA1c (Β = 0.389, p = 0.003) and VLDL-c (Β = -0.227, p = 0.029). PAI-1 antigen/activity is enhanced in poorly controlled Ghanaian T2DM subjects. The hypercoagulable state of the affected individuals put them at higher risk of developing cardiovascular diseases. Good glycemic control to regulate plasma PAI-1 levels is essential during T2DM lifelong management. Markers of fibrinolysis should be assessed in these individuals and appropriate anticoagulants given to prevent thrombosis and adverse cardiovascular diseases.

PAI-1 5G/5G genotype is an independent risk of intracranial hemorrhage in post-lysis stroke patients.

ObjectiveThrombolysis by recombinant tissue plasminogen activator (rt‐PA) is the main pharmacological therapy in acute ischemic stroke (IS); however, it is only effective in a subset of patients. Here we aimed to investigate the role of plasminogen activator inhibitor‐1 (PAI‐1), an effective inhibitor of t‐PA, and its major polymorphism (PAI‐1 4G/5G) in therapy outcome.MethodsStudy population included 131 consecutive IS patients who all underwent thrombolysis. Blood samples were taken on admission, 1 and 24 h after rt‐PA infusion. PAI‐1 activity and antigen levels were measured from all blood samples and the PAI‐1 4G/5G polymorphism was determined. Clinical data including NIHSS were registered on admission and day 1. ASPECTS was assessed using CT images taken before and 24 h after thrombolysis. Intracranial hemorrhage (ICH) was classified according to ECASS II. Long‐term outcome was defined 90 days post‐event by the modified Rankin Scale (mRS).ResultsPAI‐1 activity levels dropped transiently after thrombolysis, while PAI‐1 antigen levels remained unchanged. PAI‐1 4G/5G polymorphism had no effect on PAI‐1 levels and did not influence stroke severity. PAI‐1 activity/antigen levels as measured on admission were significantly elevated in patients with worse 24 h ASPECTS (<7). Logistic regression analysis including age, sex, NIHSS on admission, BMI, history of arterial hypertension, and hyperlipidemia conferred a significant, independent risk for developing ICH in the presence of 5G/5G genotype (OR:4.75, 95%CI:1.18–19.06). PAI‐1 levels and PAI‐1 4G/5G polymorphism had no influence on long‐term outcomes.InterpretationPAI‐1 5G/5G genotype is associated with a significant risk for developing ICH in post‐lysis stroke patients.

Association between plasminogen activator inhibitor-1 and cardiovascular events: a systematic review and meta-analysis

BackgroundSmall studies have implicated plasminogen activator inhibitor-1 (PAI-1) as a predictor of cardiovascular events; however, these findings have been inconsistent.We sought out to examine the potential role of PAI-1 as a marker for major adverse cardiovascular events (MACE).MethodsWe systematically reviewed all indexed studies examining the association between PAI-1 and MACE (defined as death, myocardial infarction, or cerebrovascular accident) or restenosis. EMBASE, Web of Science, Medline, and the Cochrane Library were searched through October 2016 to identify relevant studies, supplemented by letters to authors and review of citations. Studies reporting the results of PAI-1 antigen and/or activity levels in association with MACE in human subjects were included.ResultsOf 5961 articles screened, we identified 38 articles published between 1991 to 2016 that reported PAI-1 levels in 11,557 patients. In studies that examined PAI-1 antigen and activity levels, 15.1% and 29.6% of patients experienced MACE, respectively. Patients with MACE had higher PAI-1 antigen levels with a mean difference of 6.11 ng/mL (95% CI, 3.27-8.96). This finding was similar among patients with and without known coronary artery disease. Comparatively, studies that stratified by PAI-1 activity levels were not associated with MACE. In contrast, studies of coronary restenosis suggest PAI-1 antigen and activity levels are negatively associated with MACE.ConclusionsElevated plasma PAI-1 antigen levels are associated with MACE. Definitive studies are needed to ascertain if PAI-1 acts simply as a marker of risk or if it is indeed a bona fide therapeutic target.

Fibrinolysis shutdown is associated with a fivefold increase in mortality in trauma patients lacking hypersensitivity to tissue plasminogen activator.

Fibrinolysis shutdown (SD) is an independent risk factor for increased mortality in trauma. High levels of plasminogen activator inhibitor-1 (PAI-1) directly binding tissue plasminogen activator (t-PA) is a proposed mechanism for SD; however, patients with low PAI-1 levels present to the hospital with a rapid TEG (r-TEG) LY30 suggestive SD. We therefore hypothesized that two distinct phenotypes of SD exist, one, which is driven by t-PA inhibition, whereas another is due to an inadequate t-PA release in response to injury. Trauma activations from our Level I center between 2014 and 2016 with blood collected within an hour of injury were analyzed with r-TEG and a modified TEG assay to quantify fibrinolysis sensitivity using exogenous t-PA (t-TEG). Using the existing r-TEG thresholds for SD (<0.9%), physiologic (LY30 0.9-2.9%), and hyperfibrinolysis (LY30 > 2.9%) patients were stratified into phenotypes. A t-TEG LY30 greater than 95th percentile of healthy volunteers (n = 140) was classified as t-PA hypersensitive and used to subdivide phenotypes. A nested cohort had t-PA and PAI-1 activity levels measured in addition to proteomic analysis of additional fibrinolytic regulators. This study included 398 patients (median New Injury Severity Score, 18), t-PA-Sen was present in 27% of patients. Shutdown had the highest mortality rate (20%) followed by hyperfibinolysis (16%) and physiologic (9% p = 0.020). In the non-t-PA hypersensitive cohort, SD had a fivefold increase in mortality (15%) compared with non-SD patients (3%; p = 0.003) which remained significant after adjusting for Injury Severity Score and age (p = 0.033). Overall t-PA activity (p = 0.002), PAI-1 (p < 0.001), and t-PA/PAI-1 complex levels (p = 0.006) differed between the six phenotypes, and 54% of fibrinolytic regulator proteins analyzed (n = 19) were significantly different. In conclusion, acute fibrinolysis SD is not caused by a single etiology, and is clearly associated with PAI-1 activity. The differential phenotypes require an ongoing investigation to identify the optimal resuscitation strategy for these patients. Prognostic, level III.

Differential effect of the ultra-low dose and standard estrogen plus dydrogesterone therapy on thrombin generation and fibrinolysis in postmenopausal women.

The objective of this study was to estimate the effects of different doses of oral hormone therapy (HT) on thrombin generation and fibrinolytic activity in postmenopausal women after 12 months of treatment. Thrombin generation, fibrinolysis activators and inhibitors were determined before and after 12 months of treatment. Participants (180) were assigned (1:1:1) as follows: (1) standard HT group, 17β-estradiol (1 mg/day) with dydrogesterone (5 mg/day); (2) ultra-low dose HT group, 17β-estradiol (0.5 mg/day) with dydrogesterone (2.5 mg/day); (3) control group, no treatment. The standard HT led to a higher concentration of prothrombin 1 + 2 fragment (by 5.8%) with lower antithrombin activity (by 6.1%). Compared with baseline, we observed a reduction in mean antithrombin activity in the standard HT group and increases in mean levels of prothrombin 1 + 2 fragment in two HT groups. We found decreases after treatment in both standard and ultra-low dose HT groups in plasminogen activator inhibitor-1 (PAI-1) activity (-32.4% and -19.6%, respectively) and PAI-1 antigen (-9.9% and -7.8%, respectively). Intergroup analysis revealed reduction in both mean PAI-1 activities and PAI-1 antigen levels in the two treatment groups when compared with the control. Contrary to the standard estrogen plus dydrogesterone treatment, ultra-low dose HT revealed positive effects on hemostasis by intensifying fibrinolysis through a decrease in both PAI-1 activity and antigen levels, and with no impact on thrombin generation.

Re: "Plasminogen Activator Inhibitor-1 and Pericardial Fat in Individuals with Type 2 Diabetes Mellitus" by Bayomi et al. (Metab Syndr Relat Disord 2017;15:269-275).

Plasminogen activator inhibitor-1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily, which inactivates tissue plasminogen activator (tPA); therefore, increased level of PAI-1 antigen counteracts the anticoagulant effect of tPA and facilitates the fibrin clot formation. Plasma PAI-1 antigen and activity levels are associated with increased body mass index and with features of the insulin resistance syndrome like obesity and diabetes. Visceral adipose tissue produces more PAI-1 than subcutaneous adipose tissue: This increased production of PAI-1 from the visceral adipose tissue is one important link between visceral obesity and cardiovascular disease. Besides visceral adipose tissue, there is mounting evidence that epicardial adipose tissue may be an important source of PAI-1, especially in patients with type 2 diabetes.

Myocardial Production of Plasminogen Activator Inhibitor-1 is Associated with Coronary Endothelial and Ventricular Dysfunction after Acute Myocardial Infarction.

Although plasminogen activator inhibitor-1 (PAI-1) is abundantly expressed in infarcted myocardium, the pathogenic role of myocardial PAI-1 remains unknown. This study examined whether PAI-1 in the infarcted lesion contributes to coronary endothelial dysfunction and left ventricular (LV) dysfunction in patients with acute myocardial infarction (AMI). Plasma levels of PAI-1 activity and tissue-plasminogen activator (tPA) antigen were measured 2 weeks and 6 months after MI by ELISA in plasma obtained from the aortic root (AO) and anterior interventricular vein (AIV) in 28 patients with a first AMI due to occlusion of the left anterior descending coronary artery (LAD). Coronary blood flow responses in LAD to intracoronary infusion of acetylcholine (ACh) and left ventriculography were measured at the same time points: 2 weeks and 6 months after MI. The trans-myocardial gradient of PAI-1 from AO to AIV, reflecting production/release of PAI-1 in the infarcted lesion, was inversely correlated with the coronary blood flow response to ACh 6 months after MI (r=-0.43, p=0.02) and with the percentage change in LV regional motion in the LAD territory from 2 weeks to 6 months after MI (r=-0.38, p=0.04). The trans-myocardial gradient of tPA level showed no significant correlations. PAI-1 produced in the infarcted myocardium and released into the coronary circulation is associated with endothelial dysfunction in resistance vessels of the infarct-related coronary arteries and with progressive dysfunction of the infarcted region of the left ventricle in AMI survivors.

Abstract 12338: Production of Plasminogen Activator Inhibitor-1 in Infarcted Lesion was Associated With Coronary Endothelial Vasomotor Dysfunction and Progressive Dysfunction of Left Ventricle in Patients With Acute Myocardial Infarction

Experimental studies showed that plasminogen activator inhibitor-1 (PAI-1) is abundantly expressed in the infarcted myocardium and that the increased PAI-1 expression causes an impairment of fibrinolysis in the coronary vascular beds and left ventricular (LV) adverse remodeling after acute myocardial infarction (AMI). However, little is known in humans. Thus, this study examined whether PAI-1 produced in the infarcted lesion may contribute to coronary endothelial dysfunction and LV dysfunction in patients with AMI. Methods: Plasma levels of PAI-1 activity and tissue-plasminogen activator (tPA) protein were measured by ELISA in plasma obtained from aortic root (AO), anterior interventricular vein (AIV), and peripheral vein (PV) in 41 patients with a first AMI due to occlusion of a proximal segment of the LAD at 6 months (M) after MI. Coronary blood flow responses in the LAD to intracoronary infusion of acetylcholine (ACh, 50 μg/min) were measured by an intracoronary flow wire technique 6M after MI. Left ventriculography was repeated twice, 2 weeks (2W) and 6M after MI. Results: The trans-myocardial gradient of PAI-1 from AO to AIV (0.14 ± 0.15 ng/mL), reflecting a production/release of PAI-1 from the infarcted lesion, had an inverse correlation with coronary blood flow response to ACh (r = -0.43 , p = 0.02). The trans-myocardial gradient of PAI-1 had an inverse correlation with the % changes in LV regional motion in the LAD territory from 2W to 6M after MI (r = -0.37, p = 0.02). PAI-1 level in the PV and the trans-myocardial gradient of tPA had no significant correlation with the coronary blood flow response to ACh and the LV regional motion. The trans-myocardial gradient in PAI-1 level was lower in patients taking than not taking angiotensin II receptor blocker (ARB) (n = 22, -0.15 ± 0.19 ng/mL vs. n = 19, 0.48 ± 0.21 ng/mL, respectively, p = 0.03). Conclusions: PAI-1 produced in the infarcted myocardium and released into the coronary circulation was associated with endothelial dysfunction in resistance vessels of the infarct-related coronary arteries and progressive dysfunction of the infarcted region of LV in AMI survivors. ARB might inhibit PAI-1 production in the infarcted myocardium in the chronic phase of MI, which may represent an additional benefit of ARB therapy.

Evaluation of Lp-PLA2 mass, vitronectin and PAI-1 activity levels in patients with preeclampsia.

The aim of the current study is to determine, correlate and compare the plasma lipoprotein-associated phospholipase A2 (Lp-PLA2), vitronectin (Vn), Plasminogen activator inhibitor-1 (PAI-1) activity and tissue plasminogen activator (t-PA) levels in early-onset preeclampsia, late-onset preeclampsia and in control pregnant women. A total of 79 individuals, 30 early-onsets, and 22 late-onset preeclamptic and 27 control pregnant women were included into the scope of this study. Enzyme-linked immunosorbent assay procedure was used to determine the serum Lp-PLA2 and plasma Vn, t-PA antigen and PAI-1 activity levels. Serum C-reactive protein (CRP) levels were measured immunoturbidimetrically in routine clinical chemistry analyser. In patients with preeclampsia, Lp-PLA2, PAI-1, t-PA, CRP and blood pressures levels were increased (p = 0.000) and correlated with each other. Vn levels were decreased (p = 0.016) but not correlated with other parameters in preeclamptic patients. We are of the opinion that increased Lp-PLA2 levels may partially contribute to endothelial dysfunction by the progression of inflammation. In addition, increased complex formation with Vn is likely to bring about the increase of PAI-1 activity in patients with preeclampsia. Moreover, increased t-PA and decreased Vn levels may also be the consequences of compensatory mechanisms against disease progression.

Abstract T P75: Temporal Profiles of Plasminogen Activator Inhibitor-1 Concentration and Activity Changes in Circulation after Focal Stroke and Tissue Type Plasminogen Activator Administration in Rats

Aims: Plasminogen activator inhibitor-1 (PAI-1) is the main and potent endogenous tissue-type plasminogen activator (tPA) inhibitor, but an important question on whether PAI-1 in blood stream responds and interferes with the exogenously administered tPA remains unexplored. We for the first time investigated temporal profiles of PAI-1 concentration and activity in circulation after stroke and tPA administration in rats. Methods: Permanent MCAO focal stroke of rats were treated with saline or 10mg/kg tPA at 3 hours after stroke (n=10 per group). Plasma (platelet free) PAI-1 antigen and activity levels were measured by ELISA at before stroke, 3, 4.5 (1.5 hours after saline or tPA treatments) and 24 hours after stroke. Since vascular endothelial cells and platelets are two major cellular sources for PAI-1 in circulation, we measured releases of PAI-1 from cultured endothelial cells and isolated platelets after direct tPA (4 μg/ml) exposures for 60 min in vitro by ELISA (n=4 per group). Results: At 3 hours after stroke, both plasma PAI-1 antigen and activity were significantly increased (3.09±0.67, and 3.42±0.57 fold of before stroke baseline, respectively, all data are expressed as mean±SE). At 4.5 hours after stroke, intravenous tPA administration significantly further elevated PAI-1 antigen levels (5.26±1.24), while as expected that tPA neutralized most elevated PAI-1 activity (0.33±0.05). At 24 hours after stroke, PAI-1 antigen levels returned to the before baseline level, however, there was a significantly higher PAI-1 activity (2.51±0.53) in tPA treated rats. In vitro tPA exposures significantly increased PAI-1 releases into culture medium in cultured endothelial cells (1.65±0.08) and platelets (2.02±0.17). Conclution: Our experimental results suggest that tPA administration may further elevate stroke-increased blood PAI-1 concentration, but also increase PAI-1 activity at late 24 hours after stroke. The increased PAI-1 releases after tPA exposures in vitro suggest tPA may directly stimulate PAI-1 secretions from vascular walls and circulation platelets, which partially contributes to the PAI-1 elevation observed in focal stroke rats. The underlying regulation mechanisms and pathological consequence need further investigation.

Circadian Variability of Fibrinolytic Markers and Endothelial Function in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is strongly associated with cardiovascular disease, including stroke and acute coronary syndromes. Plasminogen activator inhibitor-1 (PAI-1), the principal inhibitor of tissue-type plasminogen activator (t-PA), has a pronounced circadian rhythm and is elevated in both OSA and cardiovascular disease and may be an important link between the two conditions. Endothelial dysfunction is one of the underlying pathophysiological mechanisms of cardiovascular disease, and may be altered in OSA. Our primary aim was to compare circadian variability of PAI-1 and t-PA in patients with OSA and normal controls by determining the amplitude (peak level) and mesor (rhythm adjusted mean) of PAI-1 and t-PA in serial blood samples over a 24-h period. The secondary aim was to measure markers of endothelial function (brachial and radial artery flow) in patients with OSA compared with normal controls. Cross-sectional cohort study. Subjects age 18 y or older, with a body mass index of 25-45 kg/m(2), with or without evidence of untreated OSA. Plasma samples were collected every 2 h, in OSA patients and matched controls, over a 24-h period. PAI-1 and t-PA antigen and activity were measured. The presence or absence of OSA (apnea-hypopnea index of 5 or greater) was confirmed by overnight polysomnography. Endothelial function was measured via brachial artery flow mediated vasodilatation and computerized arterial pulse waveform analysis. The rhythm-adjusted mean levels of PAI-1 antigen levels in the OSA group (21.8 ng/mL, 95% confidence level [CI], 18 to 25.7) were significantly higher as compared to the non-OSA group (16 ng/mL, 95% CI, 12.2 to 19.8; P = 0.03). The rhythm-adjusted mean levels of PAI-1 activity levels in the OSA group (23.9 IU/mL, 95% CI, 21.4 to 26.5) were also significantly higher than in the non-OSA group (17.2 IU/ mL, 95% CI, 14.6 to 19.9; P < 0.001).There were strong correlations between amplitude of PAI-1 activity and severity of OSA as measured by AHI (P = 0.02), and minimum oxygen levels during sleep (P = 0.04). Endothelial function parameters did not differ significantly between the two groups. The presence of obstructive sleep apnea adversely affects circadian fibrinolytic balance with higher mean plasminogen activator inhibitor-1 activity and antigen, and significantly lower mean tissue-type plasminogen activator activity compared with controls. This perturbation may be an important mechanism for increased cardiovascular events in patients with obstructive sleep apnea. Intermittent hypoxia and changes in circadian clock gene activity in obstructive sleep apnea may be responsible for these findings and warrant further study. Favorable changes in fibrinolytic balance may underlie the reduction in cardiovascular events observed with the treatment of obstructive sleep apnea.

Impact of atrial fibrillation on inflammatory and fibrinolytic variables in the elderly

Purpose. Atrial fibrillation (AF) is associated with inflammation and a prothrombotic state; however, it is still unclear whether this is independent of ageing and comorbidity. The objective of this study was to investigate the impact of AF on circulating levels of inflammatory and fibrinolytic markers in a 75-year-old general population. Methods. All 75-year-old citizens in Asker and Baerum counties in Norway were invited to participate in a prevalence study of AF. Blood samples were collected from 63 subjects with AF and a gender-matched control group of 126 subjects in sinus rhythm. C-reactive protein (CRP), tumour necrosis factor α (TNFα), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), P-selectin, CD40 ligand, tissue plasminogen activator antigen (tPA ag), plasminogen activator inhibitor-1 (PAI-1), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase inhibitor 1 (TIMP-1) activity were analyzed using commercially available assays. Results. Subjects with AF had higher levels of IL-6 (median 3.07 pg/mL (interquartile range 2.11, 4.36) vs. 2.26 (1.70, 3.26); p = 0.002) and PAI-1 activity (12.9 U/mL (6.6, 17.1) vs. 9.0 (4.6, 14.0); p = 0.005). No difference was found for the other markers. The presence of AF was still significantly associated with higher levels of IL-6 and PAI-1 activity after adjusting for confounders (p = 0.028 and p = 0.007, respectively). Conclusion. AF was independently associated with higher levels of IL-6 and PAI-1 activity. Thus, there is evidence of a proinflammatory state and reduced fibrinolysis also in this stable, out-of-hospital group of 75-year-old AF patients.

Acute CO Poisoning is Associated with Impaired Fibrinolysis and Increased Thrombin Generation

Carbon monoxide (CO) poisoning is a leading cause of unintentional poisoning deaths in many countries. In ex vivo studies, CO released from carbon monoxide-releasing molecules has been shown to attenuate fibrinolysis via increased alpha-2-antiplasmin activity. Hypofibrinolysis is associated with coronary ischaemia, which is also commonly observed in CO poisoning. We examined fibrin clot properties in acutely poisoned CO patients. Ex vivo plasma fibrin clot permeability, turbidimetry and efficiency of fibrinolysis were investigated in 48 patients and controls matched for age and sex. CO-poisoned patients had 11.6% longer clot lysis time than the controls (p < 0.0001). No intergroup differences in clot permeability or turbidimetric variables were observed. Plasma tissue-type plasminogen antigen (tPA), plasminogen activator inhibitor-1 (PAI-1) antigen and activity and F1.2 prothrombin fragments were higher in the patients than in the controls (all p < 0.0001). Plasma tPA activity was lower in the CO-poisoned group. Multiple linear regression showed that a thrombin generation marker, F1.2, is the strongest predictor of clot lysis time, followed by PAI-1 activity and carboxyhaemoglobin levels. In conclusion, this report is the first to demonstrate that acute CO poisoning in human beings is linked to increased thrombin generation and impaired fibrinolysis, which might contribute to ischaemic complications.

Elevated levels of PAI‐1 activity and t‐PA antigen are associated with newly diagnosed abnormal glucose regulation in patients with ST‐elevation myocardial infarction

Both Type 2 diabetes and cardiovascular disease have been associated with enhanced coagulation and suppressed fibrinolysis. To investigate a possible relationship between selected hemostatic variables and abnormal glucose regulation (AGR) in patients with acute ST-elevation myocardial infarction (STEMI) without known diabetes and to study changes in selected hemostatic variables from baseline to follow-up in STEMI patients with or without AGR. Plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator (t-PA) antigen, prothrombin fragment 1+2 (F(1+2)) and von Willebrand factor (vWF) were measured in fasting blood samples from 199 STEMI patients 16.5 h (median time) after admission and 3 months later. All patients were classified into normal glucose regulation (NGR) or AGR based on an oral glucose tolerance test at follow-up, according to the WHO criteria. High PAI-1 activity (≥ 75th percentile) measured in-hospital was associated with AGR (n = 49) with an adjusted odds ratio of 2.2 (95% confidence interval, 1.1, 4.4). In addition, high levels of t-PA antigen (≥ 75th percentile) were associated with AGR (adjusted odds ratio, 3.5; 95% confidence inteval, 1.5, 8.2), but only in men. Changes in the levels of F(1+2) were significantly more pronounced in patients with AGR compared with NGR (adjusted P = 0.04). Elevated levels of PAI-1 activity and t-PA antigen measured in-hospital in STEMI patients were associated with AGR classified at 3-month follow-up. Additionally, changes in the levels of F(1+2) were more pronounced in patients with AGR compared with NGR. The data suggest an enhanced prothrombotic state after an acute STEMI in patients with AGR without known diabetes.

Enhanced functional stability of plasminogen activator inhibitor-1 in patients with livedoid vasculopathy

Livedoid vasculopathy (LV) is a chronic, recurrent, painful cutaneous disease with distinctive clinical features and an uncertain etiology. The skin lesions are recognizable by focal purpura, depigmentation and shallow ulcers. Thrombophilic conditions occur frequently in patients with LV. While no definitive treatment exists for LV, smoking cessation, antiplatelet therapy, immunosuppressive treatment, and anabolic steroids are often included in the therapeutic ladder. Recently, a possible link between LV and impaired fibrinolysis was established as cutaneous LV lesions responded to tissue plasminogen activator (t-PA) infusion suggesting that inhibition of the fibrinolysis through plasminogen activator inhibitor-1 (PAI-1) activity may determine the disease course in patients with LV. In this study, we investigated PAI-1 antigen (Ag) and activity levels in 20 patients with biopsy proven LV (mean age 26 ± 11, M/F = 7/13, median disease duration 3.5 years). All patients received antiplatelet treatment with aspirin and/or dipyrimadole and 14 patients received anabolic steroids or immunosuppressive treatment. Fasting PAI-1 Ag and activity levels were measured at 9 AM in all patients. Both Ag (34 (26) ng/ml) (median (interquartile range)) and specific activity (17 (23) IU/fmole) levels of PAI-1 were moderately elevated in LV patients compared to the controls, however, PAI-1 kinetic studies demonstrated markedly enhanced stability of PAI-1 activity in plasma from patients with LV. Specific activity at 16 h was significantly higher than expected specific activity levels (7 (11) vs. 0.07 (0.09) IU/fmole, P < 0.01). While the exact mechanism of increased stability of PAI-1 activity is not known, it may be due to post-translational modifications or increased binding affinity for a stabilizing cofactor. In conclusion, enhanced stability of PAI-1 may contribute to the pathophysiology of LV, and systemic or local treatment with PAI-1 inhibitors may offer a potential treatment alternative in patients with LV.

Determinants of blood levels of some thrombogenic biomarkers in healthy Arab adolescent subjects

Acute coronary syndromes present clinically as a consequence of plaque rupture and thrombosis possibly related to altered homeostasis of thrombogenic factors. It is speculated that this vulnerability in adults should be predictable from blood levels of thrombogenic biomarkers in children and adolescents. This study aims to examine the determinants and blood levels of lipoprotein(a) [Lp(a)], fibrinogen (FBG) and plasminogen activator inhibitor-1 (PAI-1) in healthy adolescents stratified according to age group, gender and body mass. A total of 774 (316 males 458 females) healthy adolescent Arab subjects aged 10-19 years and attending secondary schools in Kuwait were interviewed by a validated questionnaire for variables relating to socio-demographic variables, diet and physical activity. They also had anthropometry, BP measurement and determination of fasting blood levels of Lp(a), low density lipoprotein (LDL)-cholesterol, apolipoprotein (apo) B, PAI-1 activity and FBG. The median (interquartile range, IQR) plasma levels of PAI-1 activity, FBG, Lp(a) and apoB were respectively 1.59 (0.58-3.78) U/mL, 296 (190-417) mg/dL, 10.0 (4.8-21.0) mg/dL and 0.72 (0.60-0.85) g/L. Boys had significantly higher PAI-1, FBG and apoB concentrations than the girls, although Lp(a) levels were greater in the latter. The overweight and obese subjects tended to have higher levels of LDL, apoB, FBG and PAI-1 but not Lp(a). Furthermore, the younger adolescent males and females (age <14 years) consistently had higher FBG levels than the older ones (age >14 years). Lp(a) and PAI-1 levels did not appear significantly influenced by this age stratification. Bivariate and multivariate analyses with adjustment for putative body mass index (BMI) confounders indicated that the independent determinants of these biomarkers were (i) Lp(a): apoB, gender; (ii) PAI-1: BMI, apoB, diet; (iii) FBG: BMI, gender, age, family income; and (iv) apoB: BMI, gender and PAI-1. The blood levels of the prothrombotic biomarkers ;ibLp(a), PAI-1, and FBG;ic in healthy Kuwaiti adolescent subjects are variably influenced by age, gender, body mass and socio-demographic factors.

Abstract 4943: Enhanced Stability of Plasminogen Activator Inhibitor-1 in Patients With Livedoid Vasculopathy

Livedoid vasculopathy (LV) is a chronic, recurrent, painful cutaneous disease with distinctive clinical features and an uncertain etiology. The skin lesions are recognizable by focal purpura, depigmentation and shallow ulcers. Thrombophilic conditions occur frequently in patients with LV. While no definitive treatment exists for LV, smoking cessation, antiplatelet therapy, immunosuppressive treatment, anabolic steroids are often included in the therapeutic ladder. Recently, a possible link between LV and impaired fibrinolysis was suggested and cutaneous LV lesions responded to tissue plasminogen activator (t-PA) infusion. Hence, inhibition of the fibrinolysis through plasminogen activator inhibitor-1 (PAI-1) activity may determine the disease course in patients with LV. In this study, we investigated PAI-1 Ag and activity levels in 8 patients with biopsy proven LV (mean age 33±18, M/F = 1, median disease duration 5 years). All patients received antiplatelet treatment with aspirin and/or dipyrimadole and 6 patients received anabolic steroids or immunosuppressive treatment. Fasting PAI-1 antigen and activity levels were measured at 9 AM in all patients. Both PAI-1 Ag levels were 44±11 (ng/ml) and PAI activity levels were 16±9 (U/ng/ml) were moderately elevated compared to age-matched controls. However, PAI-1 kinetic studies demonstrated, markedly enhanced stability of PAI-1 activities in plasma from patients with LV. Specific activity at 16 hours were significantly higher than expected activity levels (0.1±0.1 versus 0.001±0.001 u/ng/ml, p=0.028). In conclusion, enhanced stability of PAI-1 may contribute to the pathophysiology of LV, mediated via either binding with stablizing co-factors or by post-translational modification in the PAI-1 protein. Systemic or local treatment with PAI-1 inhibitors may offer potential treatment alternative in patients with LV.