Interrelationships between the fibrinolytic system and lipoproteins in the pathogenesis of coronary atherosclerosis

General health of patients with diabetic macular edema-The LIPSIA study

PURPOSE

Cardiovascular risk factors such as hypertension or dyslipidemia can influence the incidence and progression of diabetic retinopathy (DR) and diabetic macular edema (DME). The aim of this study is to describe the comorbidities in patients with DME.

METHODS

Prospective, monocentric observational study. Patients presenting for the treatment of DME received laboratory and clinical examinations including 24-hour blood pressure measurement.

RESULTS

Seventy-five consecutive patients were included in the study. The mean age was 61.0 ± 14.5 years, and 83% had type 2 diabetes. The mean body mass index (BMI) was 32.8 ± 6.0 kg/m2. Overweight (BMI ≥ 25 kg/m2) was present in 92% of all patients. HbA1c values were > 7.0% in 57%. Although 87% of the patients already received antihypertensive therapy, the blood pressure (BP) of 82% was still above the recommended target values of systolic < 140 mmHg and diastolic < 80 mmHg. An insufficient nocturnal fall of the systolic BP (< 10%, non-dipping or reverse dipping) was observed in 62%. In 83% of the patients the glomerular filtration rate was ≤ 90 ml/min/1.73m2. Despite 65% of the cohort already receiving lipid-lowering therapy, LDL cholesterol was above the target value of 1.4 mmol/l in 93%. All patients had at least one cardiovascular risk factor in addition to diabetes (overweight, hypertension, insufficient nocturnal BP fall, dyslipidemia, or renal dysfunction) and 86% had ≥ 3 risk factors.

CONCLUSION

DME patients are characterized by highly prevalent cardiovascular risk factors that are poorly controlled. These comorbidities reduce the prognosis and negatively influence existing DR and DME. The data reveal an important opportunity for improving patient care by interaction of the ophthalmologist with the general practitioner and internal specialists for the detection and treatment of these conditions.

Lipoprotein (a), hypertension, and cardiovascular outcomes: a prospective study of patients with stable coronary artery disease

Although emerging data suggest that circulating lipoprotein (a) [Lp (a)] could predict cardiovascular events (CVEs) in patients with cardiovascular disease, no study is currently available regarding the prognostic linkage of Lp (a) and hypertension in patients with coronary artery disease (CAD). This study sought to evaluate the association of Lp (a), hypertension and cardiovascular outcomes in patients with stable CAD. A total of 8668 patients with stable CAD were consecutively enrolled. Baseline Lp (a) concentrations were measured. All subjects were categorized according to Lp (a) levels of <10 (low), 10-30 (medium) and ≥30 mg/dL (high) and were further stratified by hypertension status. They were regularly followed-up for the occurrence of cardiovascular death, nonfatal myocardial infarction, and stroke. Over an average of 54.81 ± 18.60 months of follow-up, 584 (6.7%) CVEs occurred. Kaplan-Meier and multivariate Cox regression analyses showed that elevated Lp (a) levels had a significant association with CVEs in hypertensive patients, regardless of the control status of blood pressure, but not in normotensive subjects. Moreover, when analyzed by subgroups according to both Lp (a) category and hypertension status, the risk of CVEs was only significantly elevated in the high Lp (a) plus hypertension group compared with the reference group with low Lp (a) levels and normotension (hazard ratio: 1.80, 95% confidence interval: 1.11-2.91). Elevated Lp (a) was associated with an increased risk of CVEs in stable CAD patients with hypertension. Moreover, the coexistence of high Lp (a) concentrations and hypertension greatly worsened the clinical prognosis in patients with CAD, which may suggest a prognostic correlation between Lp (a) and hypertension.

[Association between IGF system and PAPP-A in coronary atherosclerosis]

Atherosclerosis is a condition that involves multiple pathophysiological mechanisms and whose knowledge has not been fully elucidated. Often, scientific advances on the atherogenic pathophysiology generate that molecules not previously considered in the scene of this disease, were attributed actions on the onset or progression of it. A representative example is the study of a new mechanism involved in the atherogenic process, consisting of the association between the insulin-like growth factor (IGF) system and pregnancy-associated plasma protein-A (PAPP-A). Insulin-like growth factor system is a family of peptides that include 3 peptide hormones, 4 transmembrane receptors and 6 binding proteins. Insulin-like growth factor-1 (IGF-1) is the main ligand of the IGF system involved in coronary atherosclerosis. IGF-1 exerts its effects via activation of the IGF-1R receptor on vascular smooth muscle cells or macrophages. In vascular smooth muscle cells promotes migration and prevents apoptosis which increases plaque stability while in macrophages reduces reverse cholesterol transport leading to the formation of foam cells. Regulation of IGF-1 endothelial bioavailability is carried out by IGFBP proteases, mainly by PAPP-A. In this review, we address the mechanisms between IGF system and PAPP-A in atherosclerosis with emphasis on molecular effects on vascular smooth muscle cells and macrophages.

Impaired fibrinolysis is associated with the severity of aortic stenosis in humans

BACKGROUND

A role of fibrinolysis in the pathogenesis of aortic valve stenosis (AS) is unknown, although fibrinolytic proteins have been detected in aortic stenotic valves.

OBJECTIVE

To investigate whether impaired fibrinolysis could be associated with AS.

METHODS AND RESULTS

We studied 74 patients with AS (43 male, 31 female, aged 62.7 ± 10.7 years) without documented atherosclerotic valvular disease scheduled for isolated valve replacement and 68 controls. The plasma fibrin clot lysis time (CLT) in the presence of tissue factor (TF) and tissue plasminogen activator (tPA), along with plasma plasminogen activator inhibitor-1 (PAI-1) were determined. Valvular expression of fibrin and PAI-1 together with macrophages and mast cells (MC) was evaluated by immunostaining. Patients with AS compared with controls were characterized by a prolonged CLT (median, 110 [54-153] vs. 92.5 [58-115] min, P = 0.0007) and increased plasma PAI-1 (78.6 [35.5-149] vs. 38.5 [18-61] ng mL(-1) , P < 0.0001). CLT was correlated with maximal (r = 0.43, P = 0.0002) and mean (r = 0.38, P = 0.001) transvalvular pressure gradients, and aortic valve area (r = -0.59, P < 0.0001). In AS patients, the CLT was positively correlated with the valve leaflet thickness (r = 0.67, P = 0.003), the degree of valve calcification (r = 0.65, P < 0.00001), valvular fibrin (r = 0.54, P = 0.007) and PAI-1 expression (r = 0.48, P = 0.007). Double-immunostaining revealed colocalization of valvular PAI-1 with MC (87 ± 17% cells) and macrophages (48 ± 11% cells) within stenotic valves.

CONCLUSIONS

Hypofibrinolysis might be a marker of severe AS and be implicated in AS progression.

Thermodynamic and structural destabilization of apoE3 by hereditary mutations associated with the development of lipoprotein glomerulopathy

Lipoprotein glomerulopathy (LPG) is a dominant inherited kidney disorder characterized by lipoprotein thrombi in glomerular capillaries. Single-amino-acid mutations in apoE have been associated with the development of the disease, although the mechanism is unknown. In an effort to gain mechanistic insight linking the presence of such mutations and the development of LPG, we evaluated the effects of three of the most common apoE3 variants associated with this disease, namely R145P(Sendai), R147P(Chicago), and R158P(Osaka or Kurashiki), on the structural and conformational integrity of the protein. All three variants were found to have significantly reduced helical content, to expose a larger portion of hydrophobic surface to the solvent, and to be significantly thermodynamically destabilized, often lacking functionally relevant unfolding intermediates. Furthermore, all variants were aggregation prone and had enhanced sensitivity to protease digestion. Finally, although the variants were able to form discoidal lipoprotein particles, discrete subpopulations of poorly formed or aberrant particles were evident. Furthermore, these lipoprotein particles were thermodynamically destabilized and aggregation prone. Overall, our data suggest that these mutations induce a generalized unfolding of the N-terminal domain of apoE3 toward a molten-globule-like structure. ApoE3 N-terminal domain unfolding due to mutation may constitute a common mechanism underlying the protein's association with the pathogenesis of LPG.

Plasminogen and fibrinogen plasma levels in coronary artery disease

Objective

The formation of thrombi at the site of atherosclerotic lesions plays a central role in atherothrombosis. Impaired fibrinolysis may exacerbate pre-existing coronary artery disease and potentiate its evolution. While the fibrinogen plasma level has been strongly associated with the severity of coronary artery disease, its relevance in the evaluation of plasminogen in coronary artery disease patients remains unclear. This study evaluated fibrinogen and plasminogen levels in subjects with coronary artery disease as diagnosed by angiography.

Methods

This is a cross-sectional study. Blood samples obtained from 17 subjects with angiographically normal coronary arteries (controls), 12 with mild/moderate atheromatosis and 28 with severe atheromatosis were evaluated. Plasma plasminogen and fibrinogen levels were measured by chromogenic and coagulometric methods, respectively.

Results

Fibrinogen levels were significantly higher in the severe atheromatosis group compared to the other groups(p-value < 0.0001). A significant positive correlation was observed between the severity of coronary artery diseaseand increasing fibrinogen levels (r = 0.50; p-value < 0.0001) and between fibrinogen and plasminogen levels (r =0.46; p-value < 0.0001). There were no significant differences in the plasminogen levels between groups.

Conclusion

Plasma fibrinogen, but not plasminogen levels were higher in patients with coronary artery disease compared to angiographically normal subjects. The plasma fibrinogen levels also appear to be associated with the severity of the disease. The results of this study provide no evidence of a significant correlation between plasma plasminogen levels and the progress of coronary stenosis in the study population.

Circulating levels of vascular endothelial markers in obstructive sleep apnoea syndrome. Effects of nasal continuous positive airway pressure

INTRODUCTION

Obstructive sleep apnoea syndrome (OSAS) is an important risk factor in cardiovascular disorders. Although the exact mechanism remains to be elucidated, the endothelial dysfunction process seems to be implicated.

MATERIAL AND METHODS

In order to test this hypothesis, blood circulating levels of endothelial markers were measured at baseline and 1 year after treatment with continuous positive airway pressure (CPAP). We studied 37 males using polysomnography: 20 subjects with OSAS and a 17-subject control group. An OSAS-validated sleep questionnaire covering the most important cardiovascular risk factors was applied to all subjects. Furthermore, patients received a complete general physical examination and biochemistry test with lipid profile. The specific markers measured were intercellular cell adhesion molecule-1 (ICAM-1), E-selectin, endothelin-1, von Willebrand factor (vWF) and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

Obstructive sleep apnoea syndrome patients presented higher circulating levels of ICAM-1, endothelin-1 and PAI-1 than the control group. On the other hand, no differences were found in E-selectin and vWF. After 1 year of CPAP treatment, there was a significant decrease in circulating levels of ICAM-1 and PAI-1. On the other hand, no differences were found in endothelin-1, E-selectin and vWF.

CONCLUSIONS

Obstructive sleep apnoea syndrome is associated with elevated levels of ICAM-1 and PAI-1 and these levels normalize after treatment with CPAP.

Supplementation of cheonggukjang and red ginseng cheonggukjang can improve plasma lipid profile and fasting blood glucose concentration in subjects with impaired fasting glucose

This study was conducted to investigate the plasma lipid profile and blood glucose-lowering effects of cheonggukjang (CH) and red ginseng CH (RGCH) in 45 subjects (men:women = 27:18; mean age, 44.9 ± 3.1 years) with impaired fasting glucose (IFG). Subjects were randomly divided into three groups: control (starch, 2 g/day), CH (20 g/day), and RGCH (20 g/day). Each volunteer received his or her daily doses for 8 weeks. The supplementation with CH and RGCH significantly decreased the plasma total cholesterol about 30.0 mg/mL and 37.7 mg/mL, respectively, compared to the initial value. The plasma low-density lipoprotein-cholesterol concentration was also significantly reduced by 29.66% and 23.42% in the CH and RGCH groups, respectively, compared to the initial value. The concentration of plasma non-high-density lipoprotein-cholesterol (107.9 mg/mL) was significantly lowered in the RGCH group compared to the initial value (139.1 mg/mL). The level of erythrocyte thiobarbituric acid-reactive substances was significantly lowered in the CH (6.5 nmol/mL) and RGCH (6.6 nmol/mL) groups compared to the initial value (7.9 nmol/mL and 8.0 nmol/mL, respectively). The ratio of apolipoprotein B and apolipoprotein A-1 concentrations (2.5) was significantly reduced in the CH group compared to the initial value (3.0). The concentration of fasting blood glucose (FBG) was significantly lower in the CH- and RGCH-supplemented groups compared to the initial value. These results suggest that CH and RGCH can lower the FBG concentration and improve the plasma lipid profile in subjects with IFG.

Association between serum lipoprotein (a) level and progression of non-proliferative diabetic retinopathy in Type 2 diabetes

PURPOSE

To investigate independent risk factors related to the progression of non-proliferative diabetic retinopathy (NPDR) for Japanese Type 2 diabetic patients.

METHODS

One hundred and six patients with NPDR were followed up for 2 years. Diabetic retinopathy (DR) was determined by colour fundus photography. Multivariate logistic regression analysis was performed to assess variables independently associated with the progression of NPDR. Serum concentrations of novel risk factors for atherosclerotic vascular disease, including lipoprotein (a) [Lp(a)] and fibrinogen, were measured.

RESULTS

Thirty-three patients (31%) had progressed by two scale steps or more in 2 years. The progression of NPDR was significantly associated with HbA(1c) [odds ratio (OR) 2.12; 95% confidence interval (CI) 1.14-4.87], systolic blood pressure (OR 1.72; 95% CI 1.14-2.91), Lp(a) (OR 2.70; 95% CI 1.09-5.12) and fibrinogen (OR 1.68; 95% CI 1.03-3.08). Multivariate logistic regression analysis showed that HbA(1c) (OR 1.74; 95% CI 1.12-3.21) and Lp(a) level (OR 1.90; 95% CI 1.06-4.33) were significant and independent predictors of the progression of NPDR.

CONCLUSION

These data suggest that serum Lp(a) level is an independent risk factor for the progression of NPDR in Type 2 diabetes patients. We recommend that further prospective validation of our findings be undertaken to confirm these observations.

Salvianolic acid B attenuates plasminogen activator inhibitor type 1 production in TNF-alpha treated human umbilical vein endothelial cells

Plasminogen activator inhibitor type 1 (PAI-1), which plays a role in the development of atherosclerosis, is produced by endothelial cells following stimulation with various inflammatory cytokines such as tumor necrosis factor (TNF-alpha). In the present study, we investigated the effects of a potent water-soluble antioxidant, salvianolic acid B (SalB; derived from the Chinese herb, Salvia miltiorrhiza), on the expression of PAI-1 in TNF-alpha-treated human umbilical vein endothelial cells (HUVECs). We found that SalB inhibited TNF-alpha-induced PAI-1 mRNA production and protein secretion in HUVECs. Treatment with SalB (0.05 and 0.15 microM) notably attenuated TNF-alpha induced expression of PAI-1 to 90.5% and 74.6%, respectively, after 12 h, and to 75.1% and 64.2%, respectively, after 18 h. We also observed a dose-dependent decrease in PAI-1 protein production in the presence of SalB. We then used pathway inhibitors to investigate which step of the TNF-alpha induced signaling pathway was targeted by SalB. We found that the c-Jun N-terminal kinase (JNK) inhibitor, SP600125, increased the inhibitory effects of SalB on TNF-alpha-induced PAI-1 secretion, whereas the nuclear factor-kappaB (NF-kappaB) inhibitor, emodin, and the extracellular signal-regulated kinase (ERK) inhibitor, PD98059, did not. A gel shift assay further showed that SalB inhibited the TNF-alpha-activated NF-kappaB and AP-1 DNA binding activities in a dose-dependent manner. Collectively, these results indicate that the NF-kappaB and ERK-AP-1 pathways are possible targets of SalB in the regulation of TNF-alpha-stimulated PAI-1 production in HUVECs.

Thrombophilia-hypofibrinolysis and atherothrombotic cardiovascular disease < or = age 45 years

Thrombophilia-hypofibrinolysis may play an important role in rare premature (< or = age 45 years) arterial occlusive events in atherothrombotic cardiovascular (ATCVD) disease, particularly in normolipidemic patients. Whether thrombophilia-hypofibrinolysis contributed to ATCVD < or = age 45 years was assessed in 78 men and 40 women with 230 ATCVD events (myocardial infarction (MI) [n = 60], coronary artery bypass graft [CABG, n = 33], angioplasty [n = 52], chronic angina [n = 41], ischemic stroke [n = 11], transient ischemic attack [TIA, n = 24], claudication [n = 9]). Cases were compared with healthy normal adult controls (44 men and 76 women). In men, the Factor V Leiden mutation was present in 6/63 (10%) cases versus 0/44 (0%) controls (P = 0.042), Factor VIII was high (>150%) in 16/60 (27%) cases versus 1/42 (2%) controls (P = 0.001), Factor XI was high (>150%) in 9/57 (16%) cases versus 0/42 (0%) controls (P = 0.009), and plasminogen activator inhibitor activity (PAI-Fx) was high (>21.1 U/mL) in 15/63 (24%) cases versus 3/43 (7%) controls (P = 0.023). In women, protein C was low (<73%) in 4/26 (15%) cases versus 0/74 (0%) controls (P = 0.004), and free protein S was low (<66%) in 5/27 (19%) cases versus 2/74 (3%) controls (P = 0.014). In women, Factor XI was high (>150%) in 3/27 (11%) cases versus 1/74 (1%) controls (P = 0.057), and the lupus anticoagulant was present in 9/32 (28%) cases versus 2/51 (4%) controls (P = 0.002). In patients with ATCVD < or = age 45 years, thrombophilias (Factor V Leiden, Factor VIII, Factor XI, protein C and S deficiency, lupus anticoagulant) and hypofibrinolysis (PAI-Fx, Lp[a]) may promote arterial thrombosis, which is synergistic with atherosclerotic endothelial injury.

Elevated tissue plasminogen activator in patients with screening-detected abdominal aortic aneurysm

OBJECTIVE

A population-based case-control study with historical and current data was conducted in a population with a high prevalence of disease to explore the hypothesis that the fibrinolytic system may be involved in the early pathogenesis of abdominal aortic aneurysm (AAA).

METHODS

Forty-two patients found to have AAA at population-based screening were compared with 100 controls matched for age and sex. Mass concentration of tissue plasminogen activator (tPA mass) and tissue plasminogen activator/plasminogen activator inhibitor-1 complex (tPA/PAI-1 complex mass) were analyzed in blood samples obtained at the screening (current), and in blood samples obtained from a study conducted 12 years previously on the same population (historical).

RESULTS

Current tPA mass levels were significantly higher in AAA patients compared with controls (13.6 vs 11.4 microg/L, P=.016). A similar trend was observed in historical tPA mass levels (9.8 vs 8.2 microg/L, P=.062). Current and historical mass concentrations of tPA/PAI complex in AAA patients were similar to those in controls. Current tPA mass levels retained the associations with AAA in a logistic regression model after adjustment for history of atherosclerosis (odds ratio [OR], 1.1 per microg/L, P=.039) and current smoking (OR 1.1 per microg/L, P=.039). When family history of AAA was added in a logistic regression model, the OR for current tPA mass was 1.1 per microg/L (P=.056) and 1.1 per microg/L (P=.070) when treated hypertension was added.

CONCLUSION

The finding of elevated tPA mass, in contrast to tPA/PAI-1 complex, in plasma among patients with screening-detected AAA supports the hypothesis that the fibrinolytic system may be important in the early pathogenesis of AAA.

The risk of dialysis access thrombosis is related to the transforming growth factor-beta1 production haplotype and is modified by polymorphisms in the plasminogen activator inhibitor-type 1 gene

Transforming growth factor-beta1 (TGF-beta1) and plasminogen activator inhibitor-type 1 (PAI-1) might play a role in the development of fibrosis and stenosis of hemodialysis vascular accesses. We studied polymorphisms in the TGFbeta1 (869T>C; 915G>C), and PAI-1 (4G/5G) genes in 416 hemodialysis patients (107 access thrombosis cases, 309 controls), to determine if they are related to vascular access thrombosis. Three TGF-beta1 production haplotypes (low, intermediate, and high) were defined according to the combination of polymorphisms found. The adjusted odds ratio (OR) and 95% confidence interval (CI) for access thrombosis in low TGF-beta1 producers was 7.31 (2.15-24.88; P = .001). The interaction between low TGF-beta1 production haplotype and the 4G/4G PAI-1 genotype was strongly associated with access thrombosis (adjusted OR 19.3; 95% CI 2.82-132.40; P = .003). Mean access thrombosis-free survival times in years (95% CI) were 14.65 (12.05-17.25), 11.96 (8.67-15.25), and 4.94 (3.06-6.83) in high, intermediate, and low TGF-beta1 producers, respectively (P = .044). Analysis of the synergy index and the case-only cross-product supported the presence of an interaction. We concluded that low TGF-beta1 production haplotype is a risk factor for hemodialysis access thrombosis and that in the presence of the 4G/4G PAI-1 genotype there is an additional increase in risk.

Probing the importance of hydrogen bonds in the active site of the subtilisin nattokinase by site-directed mutagenesis and molecular dynamics simulation

Hydrogen bonds occurring in the catalytic triad (Asp32, His64 and Ser221) and the oxyanion hole (Asn155) are very important to the catalysis of peptide bond hydrolysis by serine proteases. For the subtilisin NK (nattokinase), a bacterial serine protease, construction and analysis of a three-dimensional structural model suggested that several hydrogen bonds formed by four residues function to stabilize the transition state of the hydrolysis reaction. These four residues are Ser33, Asp60, Ser62 and Thr220. In order to remove the effect of these hydrogen bonds, four mutants (Ser33-->Ala33, Asp60-->Ala60, Ser62-->Ala62, and Thr220-->Ala220) were constructed by site-directed mutagenesis. The results of enzyme kinetics indicated that removal of these hydrogen bonds increases the free-energy of the transition state (DeltaDeltaG(T)). We concluded that these hydrogen bonds are more important for catalysis than for binding the substrate, because removal of these bonds mainly affects the kcat but not the K(m) values. A substrate, SUB1 (succinyl-Ala-Ala-Pro-Phe-p-nitroanilide), was used during enzyme kinetics experiments. In the present study we have also shown the results of FEP (free-energy perturbation) calculations with regard to the binding and catalysis reactions for these mutant subtilisins. The calculated difference in FEP also suggested that these four residues are more important for catalysis than binding of the substrate, and the simulated values compared well with the experimental values from enzyme kinetics. The results of MD (molecular dynamics) simulations further demonstrated that removal of these hydrogen bonds partially releases Asp32, His64 and Asn155 so that the stability of the transition state decreases. Another substrate, SUB2 (H-D-Val-Leu-Lys-p-nitroanilide), was used for FEP calculations and MD simulations.

Fibrinolysis and cardiovascular risk factors: association with fibrinogen, lipids, and monocyte count

BACKGROUND

Numerous risk factors for cardiovascular disease (CVD) have been determined by clinical epidemiological observations. The missing link could be related to endothelial dysfunction and the resulting hypofibrinolysis.

METHODS

In this cross-sectional study, we evaluated 160 subjects (134 in primary prevention) characterized by their clinical cardiovascular risk factors (CVRF), i.e., age, gender, diabetes, hypertension, smoking habit, and history of coronary event or stroke, and by their blood parameters, i.e., C-reactive protein (CRP), fibrinogen, leukocyte count (WBC), monocyte count (MC), total cholesterol, HDL cholesterol (HDL-c), LDL cholesterol (LDL-c), and triglycerides. We assessed their fibrinolytic capacity with a new method, Euglobulin Clot Lysis Time (ECLT). The effects of these clinical and biological parameters were evaluated in multivariate analysis (backward stepwise regression).

RESULTS

ECLT was correlated with the Framingham risk score and was significantly influenced by the number of clinical CVRF. MC was confirmed to be an important predictive factor influencing ECLT. In subjects without clinical CVRF (n=46), 67% of the variability of ECLT was explained by a combination of MC, LDL-c, and fibrinogen.

CONCLUSION

ECLT is related to the number of epidemiologically defined clinical CVRF and to MC. Because it integrates many risk factors, we suggest that fibrinolytic function could be a biological test useful for physicians in the cardiovascular risk assessment of their patients.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

High-density lipoprotein particles may regulate hemostasis in human pregnancy

We explored the association of apolipoprotein A-I (the major protein constituent of high-density lipoprotein (HDL)) and fibrin fragment D-dimer (a marker of cross-linked fibrin turnover) in pregnant women. A significant inverse correlation between the levels of apolipoprotein A-I and fibrin fragment D-dimer was observed in both pre-eclamptic and normal pregnant women (rs = -0.459, n = 37 and rs = -0.290, n = 55, respectively), suggesting a major regulating role of HDL in hemostasis during pregnancy.

Stimulated release of tissue plasminogen activator from artery wall sympathetic nerves: implications for stress-associated wall damage

Recurrent stress is clinically associated with early onset hypertension and coronary artery disease. A mechanism linking emotion to pathogenic remodeling of the artery wall has not been identified. Stress stimulates acute regulated release of tissue plasminogen activator (t-PA) into the circulation, which is presently attributed to the vascular endothelium. Sympathetic neurons also synthesize t-PA and axonally transport it to the arterial smooth muscle. Unlike release by the endothelium, a stress-stimulated sympathetic discharge would potentially accelerate degradation of the wall matrix by plasmin. To assess whether sympathetic axons are the principal source of acute stress-induced arterial release of t-PA, we compared the output from small densely innervated and large sparsely innervated isolated artery segments before and after sympathetic stimulation, and after ablations. Following phenylephrine infusion densely-innervated microvessels in uveal eyecups were released over 60-fold greater amounts of active t-PA per milligram than the sparsely innervated aorta; and ten-fold more than carotid artery segments. Mesenteric artery release was 4.8-fold greater than release by the carotid artery. In vivo, uveal release of t-PA increased more than three-fold within one minute following superior cervical sympathetic ganglion electrical stimulation, and after phenylephrine, or nicotine infusions of the anterior chamber. Circulating levels of t-PA fell 70% following chemical sympathectomy. We propose that sympathetic nerves are the primary source of stress-induced release of t-PA into and from the densely innervated resistance arteries and arterioles, where dysregulated plasmin-induced proteolysis could damage the wall matrix.