Franco Carmassi

Microalbuminuria and endothelial dysfunction in essential hypertension

Microalbuminuria (urinary albumin excretion between 20 and 200 micrograms/min) and endothelial dysfunction coexist in patients with essential hypertension. To evaluate whether the two phenomena are related and the determinants of that association, we recruited 10 untreated males with essential hypertension and microalbuminuria without diabetes to be compared with an equal number of matched patients with essential hypertension excreting albumin in normal amounts and 10 normal controls. The status of endothelial function was inferred from circulating von Willebrand Factor antigen (vWF), a glycoprotein secreted in greater amounts when the vascular endothelium is damaged. vWF concentrations were higher in hypertensive patients with microalbuminuria than in hypertensive patients without and controls. Individual vWF and urine albumin-excretion values were correlated (r = 0.55, p < 0.002). Blood pressure correlated with both urinary albumin excretion and vWF. Left ventricular mass index and minimal forearm vascular resistances were comparable in patients with hypertension and higher than in controls; total and low-density lipoprotein cholesterol, triglycerides, lipoprotein-a, Factor VII, and plasminogen activator inhibitor-1 did not differ. Fibrinogen was higher and creatinine clearance lower in microalbuminurics. Albuminuria in essential hypertension may reflect systemic dysfunction of the vascular endothelium, a structure intimately involved in permeability, haemostasis, fibrinolysis, and blood pressure control. This abnormality may have important physiopathological implications and expose these patients to increased cardiovascular risk.

Soluble Vascular Cell Adhesion Molecule-1 as a Biohumoral Correlate of Atherosclerosis

Vascular cell adhesion molecule-1 (VCAM-1) is a protein expressed on the surface of activated endothelial cells and expressed in early atherosclerosis. Because part of the protein is shed in the circulation and can be detected in peripheral plasma [soluble (s) VCAM-1], we hypothesized that sVCAM-1 may be a circulating marker of the presence and severity of atherosclerosis in humans. We selected 11 patients with essential hypertension plus peripheral vascular disease (PVD) and matched them for age, gender, body mass index, and smoking habits with 11 patients with uncomplicated essential hypertension (UH) and 11 healthy controls. We evaluated plasma concentrations of sVCAM-1 along with those of the soluble form of two other endothelial leukocyte adhesion molecules [sE-selectin and s-intercellular adhesion molecule-1 (sICAM-1)] and other markers of endothelial dysfunction/ damage [s-thrombomodulin, plasminogen activator inhibitor type I, and von Willebrand factor (vWF)]. We also measured insulin, glucose, fibrinogen, total and HDL cholesterol, and the urinary albumin excretion (UAE), which may also be related to atherosclerosis. Results of these assays were related to the echographic assessment of the maximum intima-media thickness (IMTmax) at the carotid bifurcation, as an index of atherosclerosis in the carotids. PVD patients had a clearly elevated IMTmax [2.7 (1.1-3.1) mm, median (range)] compared with both UH patients [1.2 (0.8-2.4) mm] and controls [1 (0.6-2) mm]. sVCAM-1 was clearly higher in PVD patients [990 (273-1808) ng/mL, median (range)] versus 340 (236-975) ng/mL in UH and 386 (204-835) ng/mL in controls, and it separated clinical categories better than sICAM-1, vWF, glucose, insulin, UAE, triglycerides, or total, LDL or HDL cholesterol, sVCAM-1 was also the best biohumoral correlate of IMTmax (R = .59; P < .001) in univariate analysis. Because many of the biohumoral variables assessed were mutually intercorrelated, they were entered in a multivariate analysis to assess their contribution in explaining IMTmax variability. sVCAM-1 remained the only independent predictor of IMTmax and totally abolished the contribution of other variables to IMTmax variability. Thus, sVCAM-1 is a good biohumoral correlate of overt atherosclerosis, independent of underlying hypertension, and may be an in vivo marker of endothelial activation. Its potential value as a surrogate for global risk assessment and its behavior in intervention studies remain to be determined.

COAGULATION AND FIBRINOLYTIC SYSTEM IMPAIRMENT IN INSULIN DEPENDENT DIABETES MELLITUS

Selected coagulation and fibrinolytic parameters were assessed in 40 insulin dependent diabetes mellitus patients with varying degrees of metabolic control; 30 healthy subjects matched for age and sex formed the control group. Activated Partial Thromboplastin Time, Prothrombin Time, Fibrinogen, Factor VII, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, Plasminogen Activator Inhibitor-1, tissue-Plasminogen Activator were functionally evaluated. Antigenic levels of tissue-Plasminogen Activator, Thrombin-Antithrombin complexes and fibrinolytic specific product B beta 15-42 were also determined. Compared to the control group diabetic patients displayed significantly higher levels of Fibrinogen (p < 0.01), Factor VII (p < 0.01), Thrombin-Antithrombin complexes (p < 0.01) and Plasminogen Activator Inhibitor-1 activity (p < 0.01). Regardless of the normal level of the tissue-Plasminogen Activator-related antigen, diabetic patients had tissue-Plasminogen Activator activity lower than the control group (p < 0.05). Coagulation Factor VII and Thrombin-Antithrombin complexes were increased only in the patients with poor metabolic control (p < 0.01). Activated Partial Thromboplastin Time, Prothrombin Time, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, B beta 15-42 fibrin peptide were found to be in the normal range. Fibrinogen correlated positively with fasting blood glucose (p < 0.05) and Thrombin-Antithrombin complexes with glycosylated haemoglobin (p < 0.05), whereas Factor VII was positively correlated with glycemia (p < 0.01) and glycosylated haemoglobin (p < 0.05). Higher levels of Fibrinogen were found in patients affected by nephropathy (p < 0.005) or neuropathy (p < 0.05). These results demonstrate an impairment of the haemostatic balance in diabetic patients, that is a possible hypercoagulable state, which represents an important factor in the pathogenesis of atherosclerotic complications.

Local insulin infusion stimulates expression of plasminogen activator inhibitor-1 and tissue-type plasminogen activator in normal subjects

PURPOSE Plasma levels of plasminogen activator inhibitor-1 are increased in obesity, hypertension, and diabetes. Their correlation with insulin levels supports the hypothesis that hypofibrinolysis may affect the development of atherosclerotic complications in patients with insulin resistance. To investigate the effect of insulin on fibrinolysis, we evaluated levels of plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) antigens during insulin infusion in the forearm vascular beds of 8 healthy subjects. MATERIALS AND METHODS Insulin was infused in the brachial artery of each subject to raise local venous concentrations to approximately 100 microU/mL. Blood samples were obtained from the brachial artery and vein at baseline, after 30, 60, 90, and 120 minutes of infusion, and 30 minutes after the end of the infusion. RESULTS Following intra-arterial infusion of insulin, forearm blood flow (mean +/- SD) increased progressively from 2.7 +/- 0.6 to 4.0 +/- 0.6 mL/dL/min (P <0.01) and did not return to baseline after the end of the infusion. Plasminogen activator inhibitor-1 balance increased (345 +/- 160 versus 8 +/- 152 fmol/dL/min, P <0.02) at 60 minutes, reaching baseline levels after the end of the infusion. After 90 minutes, tPA balance increased (40 +/- 26 versus 7 +/- 29 fmol/dL/min, P <0.01) with a profile similar to forearm blood flow. CONCLUSIONS Local hyperinsulinemia induces regional vasodilation and expression of PAI-1 and tPA antigens. An alteration of this physiological process could be involved in the development of hypofibrinolysis and atherosclerosis in states of insulin resistance.

Fibrinopeptide a plasma levels during low-estrogen oral contraceptive treatment

In a group of healthy women taking oral contraceptives containing 30 micrograms ethinylestradiol combined with two different progestogens (desogestrel and gestoden), Fibrinopeptide A (FPA) plasma levels were evaluated both before and after 3, 6 and 9 months of therapy. FPA levels, which represent an index of thrombin action in vivo, were also determined in untreated subjects during the follicular and the luteal phases of the menstrual cycle. While no modifications of FPA levels were found during the menstrual cycle, a significant increase of this peptide was observed during oral contraceptive treatment. These data suggest that low-dose oral contraceptives, by enhancing the rate of conversion of fibrinogen to fibrin by thrombin, increase the risk of venous thrombosis. Since some mechanisms which compete with the thrombin activity are also increased by oral contraceptives, the significance of this change in the induction of thrombosis cannot be completely clarified.

Modulation of hemostatic balance with antithrombin III replacement therapy in a case of liver cirrhosis associated with recurrent venous thrombosis

Patients with liver failure can present both thrombotic and hemorragic complications because of the deficiency in coagulation factors and inhibitors (protein C and S, antithrombin III) and impairment of fibrinolytic balance. Here we report the case of a 63-year-old man with liver cirrhosis, recurrent thrombosis, and features of low-grade consumption coagulopathy, showing severe antithrombin III deficiency (about 30% of normal values). Treatment with antithrombin III (2000 U/day) and low doses of heparin (5000 U b.i.d.) was successful in modulating the coagulation system toward an antithrombotic effect. After discharge from hospital the ambulatory treatment with antithrombin III concentrates (2000 U twice a week) allowed the attainment of antithrombin III activity of about 60% and prevented the patient from recurrence of venous thrombosis.

A 12-month clinical investigation with a 24-day regimen containing 15 μg ethinylestradiol plus 60 μg gestodene with respect to hemostasis and cycle control

Abstract The effects of a 24-day regimen containing 15 μg ethinyl estradiol (EE) plus 60 μg gestodene on cycle control and on hemostasis, were evaluated in 58 healthy women (age 19–47 years). All women received the pill for 12 months. Withdrawal bleeding at every cycle during the tablet-free interval was experienced by 84.5% of the women. The overall incidence of irregular bleedings was 19.3%. Hemostasis was evaluated in 20 women. No changes in plasma fibrinogen concentrations, nor in prothrombin fragment F1+2 were observed. A slight increase in thrombin-antithrombin III complexes was observed after 6 and 12 months of oral contraceptive use. Antithrombin III activity significantly increased after one-year of pill intake. The concentrations of tissue plasminogen activator and plasminogen activator inhibitor, both antigen and activity, did not change. These results show that very low doses of EE, such as 15 μg, do not impair hemostasis in healthy females. However, the reduction for the EE dose is responsible of some of the effects on cycle control.

Antithrombotic and antifibrinolytic effects of antithrombin III replacement in liver cirrhosis

In liver failure, chronic disseminated intravascular coagulation (DIC) may occur as shown by increases in markers of activation of the coagulation cascade (prothrombin fragment F1+2, thrombin-antithrombin [TAT] complexes) and fibrinolysis (plasmin-antiplasmin [PAP] complexes, D-dimer), although the contribution of impaired hepatic clearance to the increases in these products cannot be ruled out. DIC rarely becomes life-threatening in liver cirrhosis, but chronic activation and consumption of clotting factors can contribute to haemorrhagic and thrombotic complications. Antithrombin III (AT-III) inhibits thrombin, other activated coagulation factors, and plasmin, and previous studies suggest the usefulness of AT-III replacement in selected patients with AT-III deficiency and DIC. We studied the effect of AT-III replacement therapy on coagulation and fibrinolysis in cirrhotic patients. Ten cirrhotic patients (Child B-C stages) with low plasma AT-III (<600 U/L) were treated for 7 days with AT-III doses calculated to raise plasma values above 800 U/L (range 2000–4000 U per day). AT-III concentrates (Immuno, Vienna) were administered intravenously between 0800 h and 1000 h. Blood samples were obtained before AT-III injection. The antigenic levels of PAP complexes, F1+2 fragment, and TAT complexes were assayed by ELISA methods. All patients showed high basal concentrations of TAT, F1+2 fragment, and PAP complexes. During therapy, a progressive decrease of TAT complexes, F1+2 fragment, and PAP complexes was observed (figure). Plasma values of TAT complexes and F1+2 fragment were strongly correlated (p<0·001). In liver cirrhosis, hyperfibrinolysis, reduced synthesis of coagulation factors and inhibitors, and their consumption, restrain the adaptability of the haemostatic balance. Thus, depending on the triggering stimulus, the patient can develop thrombosis and/or haemorrhage. Whereas clotting proteins are present in excess and deficiencies must be severe to produce haemorrhagic effects, a moderate reduction of AT-III can severely impair the antithrombotic potential of plasma. Since second-order kinetics regulate the reaction of AT-III with thrombin and factor Xa, the rate of clotting enzyme inhibition is likely to depend on AT-III concentration. Moderate AT-III deficiency, characterised by a large molar excess of AT-III over the clotting factors, can cause thrombophilia through a kinetic rather than a capacity defect in the interaction between clotting factors and inhibitor. The finding of increased levels of F1+2 fragment and TAT complexes and their decrease after AT-III replacement demonstrates the presence of increased thrombin generation in cirrhotic patients, and also that ATIII replacement is able to inhibit prothrombin activation by quenching the coagulation cascade. In liver cirrhosis, hyperfibrinolysis, either primary or secondary to DIC, could play an important role in bleeding complications. In our patients, the decrease of PAP complexes after AT-III replacement suggests that hyperfibrinolysis in liver cirrhosis can be reduced by improving the antithrombotic potential of plasma. A trial is now needed to evaluate efficacy and indications for AT-III replacement therapy in cirrhotic patients.

Oral contraceptives and venous thromboembolic disease: the effect of the oestrogen dose

Low-dose oral contraceptives when tested for vascular or thrombotic effects not only show no risk of venous thromboembolic disease, but this method could possibly reduce the chance of thromboembolic disease as compared with pills which have a higher estrogen dose. It has also been found that pills containing lower doses of estrogen have no effect on the coagulatory system. Concerns raised about the connection between oral contraceptive use and the risk of cardiovascular disease called for testing in the late 1960s. Epidemiological studies confirmed the risk of oral contraceptive use and cardiovascular disease especially venous thromboembolism. A further association was identified between the amount of estrogens contained in oral contraceptives and the risk of disease. Estrogens affect the hemostatic system; decreases in antithrombin III activity in addition to platelet adhesiveness and blood viscosity have been observed in oral contraceptive users. Although both a decreased influence on the hemostatic system and the risk of thromboembolic disease have been found in pills with lower doses of estrogen, further research on the effect of the clotting system by low-dose oral contraceptives is needed.

Acetylcholine-mediated vasodilatation and tissue-type plasminogen activator release in normal and hypertensive men.

Muscarinic agents release tissue plasminogen activator (t-PA) in the forearm circulation of normal subjects, but no information exists about their effect in those hypertensive patients in whom the response to endothelial-mediated vasodilators is blunted. Acetylcholine, an endothelium-dependent vasodilator and a muscarinic agonist that releases t-PA from in-vitro systems, and sodium nitroprusside, an endothelium-indepen dent vasodilator, were infused into the brachial artery at rates calculated to cause a similar degree of vasodilatation. The study was performed in five elderly, smoking hyper tensive patients in whom the clustering of detrimental factors for endothelial function permitted prediction of defective endothelial-mediated vasorelaxation, and five young, normotensive, nonsmoking male volunteers. Forearm blood flow was assessed by venous plethysmography; t-PA and plasminogen activator inhibitor 1 (PAI-1) antigen values were expressed as flow-dependent (net release, the product of venoarterial concentration gradient and forearm blood flow) or independent (absolute and fractional concentration gradients) indices. In patients, acetylcholine did not change flow and net release and concentration gradients of t-PA, suggesting that vasodilatation as such, possibly by increasing fluid shear stress, may induce t-PA release in human forearm. In normal subjects, acetylcholine and sodium nitroprusside increased t-PA antigen net release at the highest infusion rate, an effect attributable to forearm hyperperfusion, since absolute and fractional gradients did not change significantly. PAI-1 antigen did not change during either infusion in both controls and patients, indicating the absence of an endothelial pool to be mobilized acutely.