Haemostatic variables associated with diabetes and its complications.

To study the possible role of an "increased thrombotic tendency" in the vascular complications of diabetes several tests of haemostatic function were carried out on 91 men and 63 women with diabetes aged 35-54 years and the results compared with findings in 686 men and 393 women of the same age in the Northwick Park Heart Study. Mean values for factors VII and X, fibrinogen, and platelet adhesiveness were higher in the diabetics, but mean fibrinolytic activity and whole blood platelet counts were lower. Antithrombin III values were also higher in the diabetics, which may have constituted a protective response to other changes favouring the onset of vascular disease. Diabetics with retinopathy had higher factor VII and antithrombin III values, and those with proteinuria had higher values for factor VII, fibrinogen, and platelet adhesiveness than those without these complications. These findings suggest a potentially important association between a thrombogenic tendency and vascular disease in diabetes. Nevertheless, prospective data are needed to clarify whether the haemostatic abnormalities precede the onset of clinically manifest vascular complications or are a consequence of them.     

Body Mass Index and the Prevalence of Hypertension and Dyslipidemia

Objective: To describe and evaluate relationships between body mass index (BMI) and blood pressure, cholesterol, high‐density lipoprotein‐cholesterol (HDL‐C), and hypertension and dyslipidemia. Research Methods and Procedures: A national survey of adults in the United States that included measurement of height, weight, blood pressure, and lipids (National Health and Nutrition Examination Survey III 1988–1994). Crude age‐adjusted, age‐specific means and proportions, and multivariate odds ratios that quantify the association between hypertension or dyslipidemia and BMI, controlling for race/ethnicity, education, and smoking habits are presented. Results: More than one‐half of the adult population is overweight (BMI of 25 to 29.9) or obese (BMI of ≥30). The prevalence of high blood pressure and mean levels of systolic and diastolic blood pressure increased as BMI increased at ages younger than 60 years. The prevalence of high blood cholesterol and mean levels of cholesterol were higher at BMI levels over 25 rather than below 25 but did not increase consistently with increasing BMI above 25. Rates of low HDL‐C increased and mean levels of HDL‐C decreased as levels of BMI increased. The associations of BMI with high blood pressure and abnormal lipids were statistically significant after controlling for age, race or ethnicity, education, and smoking; odds ratios were highest at ages 20 to 39 but most trends were apparent at older ages. Within BMI categories, hypertension was more prevalent and HDL‐C levels were higher in black than white or Mexican American men and women. Discussion: These data quantify the strong associations of BMI with hypertension and abnormal lipids. They are consistent with the national emphasis on prevention and control of overweight and obesity and indicate that blood pressure and cholesterol measurement and control are especially important for overweight and obese people.     

The roles of platelet function, thromboxane, blood lipids and nitric oxide in hypertension of children and adolescents

The roles of platelet function, plasma lipids and nitric oxide (NO) were studied in adolescent patients with essential hypertension (JEHT group), with chronic renal failure (CRF) associated with hypertension (CRFH group), and CRF patients with normal blood pressure (CRF group), as compared with normal controls (cont. group). Platelet aggregation and the thromboxane B(2)(TxB(2)) level were significantly higher in the JEHT and CRFH groups as compared with the cont. group, whereas they were significantly lower in the CRF group. On the other hand, the platelet cAMP level was significantly lower in the JEHT and CRFH groups than in the cont. group. The plasma NO level was significantly higher only in the JEHT as compared with the cont. group (120 +/- 39 and 89 +/- 21 microM, respectively). The plasma total cholesterol, triglyceride and LDL cholesterol concentrations were normal in the JEHT group, but high in the CRF and CRFH group, the HDL cholesterol level was lower in the CRF and CRFH groups as compared with the cont. and JEHT groups. There was a positive correlation between the platelet aggregation and the TxB(2)level and between the BP and the platelet aggregation. In conclusion, hyperlipidaemia is commonly present in uraemia with haemodialysis, but is not specific for hypertension in children, while an increased platelet function is frequently associated with hypertension. The increased NO level might play a compensatory role in JEHT.     

Effects of atorvastatin and aspirin combined therapy on inflammatory responses in patients undergoing coronary artery bypass grafting

This study was conducted to compare the effects of atorvastatin plus aspirin combined therapy on inflammatory responses, endothelial cell function, and blood coagulation system in patients undergoing coronary artery bypass grafting (CABG) to aspirin monotherapy. The patients were randomized into atorvastatin plus aspirin combined therapy group and aspirin monotherapy group. Reduced total cholesterol in the combined therapy group was found in a short term of medication for 14 days. On postoperative day (POD)-14, inhibitory effects of the combined therapy on whole blood aggregation as well as platelet activation assessed by flow cytometry were stronger than those of the monotherapy. Furthermore, cytokine, cytokine receptors, c-reactive protein and α1-acid glycoprotein in the combined therapy group were down-regulated on POD-14. At the same time, circulating levels of thromboxane A₂, vascular endothelial growth factor and thrombin–antithrombin III complex as well as P-selectin, L-selectin and intercellular adhesion molecule-1 were down-regulated, while E-selectin and transforming growth factor-β1 was up-regulated. Atorvastatin plus aspirin combined therapy may improve inflammatory responses, accelerated platelet function, vascular endothelial cell function, blood coagulation system at the early stage such as 14th day after CABG. In conclusion, atorvastatin and aspirin combined therapy may bring beneficial effects to the patient after CABG.     

Beta-endorphin administered into the lateral ventricle of the brain causes pulmonary platelet trapping in rabbits

Human beta-endorphin was injected into the cerebrospinal fluid in rabbits by means of a needle inserted into the lateral ventricle of the brain. Control rabbits received an equal amount of saline. beta-Endorphin induced a significant pulmonary platelet trapping compared to control. beta-Endorphin had no effect on arterial blood pressure, heart rate, platelet aggregability ex vivo or fibrinolytic activity (fibrinolytic plates). The plasma activity of antithrombin III, kallikrein-like activity and kallikrein inhibitor determined by means of chromogenic substrates was not influenced by beta-endorphin.     

Anticoagulant activities of heparin oligosaccharides and their neutralization by platelet factor 4.

Oligosaccharides of well-defined molecular size were prepared from heparin by nitrous acid depolymerization, affinity chromatography on immobilized antithrombin III (see footnote on Nomenclature) and gel chromatography on Sephadex G-50. High affinity (for antithrombin III) octa-, deca-, dodeca-, tetradeca-, hexadeca- and octadeca-saccharides were prepared, as well as oligosaccharides of larger size than octadecasaccharide. The inhibition of Factor Xa by antithrombin III was greatly accelerated by all of these oligosaccharides, the specific anti-Factor Xa activity being invariably greater than 1300 units/mumol. The anti-Factor Xa activity of the decasaccharide was not significantly decreased in the presence of platelet factor 4, even at high platelet factor 4/oligosaccharide ratios. Measurable but incomplete neutralization of the anti-Factor Xa activities of the tetradeca- and hexadeca-saccharides was observed, and complete neutralization of octadeca- and larger oligo-saccharides was achieved with excess platelet factor 4. The octa-, deca-, dodeca-, tetradeca- and hexadeca-saccharides had negligible effect on the inhibition of thrombin by antithrombin III, whereas specific anti-thrombin activity was expressed by the octadeca-saccharide and by the larger oligosaccharides. An octadecasaccharide is therefore the smallest heparin fragment (prepared by nitrous acid depolymerization) that can accelerate thrombin inhibition by antithrombin III. The anti-thrombin activities of the octadecasaccharide and larger oligosaccharides were more readily neutralized by platelet factor 4 than were their anti-Factor Xa activities. These findings are compatible with two alternative mechanisms for the action of platelet factor 4, both involving the binding of the protein molecule adjacent to the antithrombin III-binding site. Such binding results in either steric interference with the formation of antithrombin III-proteinase complexes or in displacement of the antithrombin III molecule from the heparin chain.     

Replacement therapy of acquired antithrombin III deficiency in experimental nephrotic syndrome

The influence of antithrombin III on hemostasis and renal function was studied in experiments on rats with nephrotic syndrome. The development of nephrotic syndrome was accompanied by the activation of blood coagulation and appearance of acquired antithrombin III deficiency due to its loss with the urine. The replacement therapy by bovine antithrombin III at a dose of 25 U/kg a day for 10 days decreased the signs of excessive thrombinogenesis in experimental animals and increased the amount of thrombin-antithrombin III complexes in the blood flow. The activation of coagulation in rats with nephrotic syndrome predominantly induced the disturbances of the excretory renal function which could be efficiently corrected by antithrombin III.     

Changes in thromboxane A2 generation and plasma lipid pattern in pseudomenopause induced by gonadotropin releasing hormone (GnRH) analogue buserelin

An increased risk of cardiovascular disease has been found in postmenopausal women in comparison to premenopausal women. The aim of this study was to investigate platelet function, blood clotting and plasma lipid levels in 12 women with a condition of hypoestrogenism, similar to the postmenopausal status induced by treatment with the GnRH analogue buserelin for uterine leiomyoma. Platelet aggregation in whole blood and platelet-rich plasma (PRP), serum thromboxane (TX) B2 production, fibrinopeptide A (FPA) plasma levels and plasma lipid pattern were measured before and after 13 weeks of buserelin treatment. No changes of platelet aggregability were found either in whole blood or PRP. Serum TXB2 generation increased significantly after 13 weeks of therapy (p less than 0.001). No signs of increased thrombin generation were found, as indicated by unchanged FPA plasma levels. Total cholesterol plasma levels were found increased after 13 weeks, LDL cholesterol levels showed a tendency to increase although not significantly. HDL cholesterol and triglyceride concentrations were unaffected. The changes of arachidonic acid metabolism and lipid pattern suggest that buserelin treatment may induce a condition of increased thrombotic risk even if the lack of enhanced thrombin generation and increased platelet aggregability indicates that no blood clotting activation occurs.     

Antithrombin III activity in long-developing hypercoagulation in animals

Old rats aged 12-18 months and rats kept on an atherogenic diet for 3.5 months demonstrate high blood antithrombin III content at the initial period of the development of anticoagulation function suppression and of hypercoagulation. During long-developing hypercoagulation, the high content of antithrombin III might be regarded as compensatory reaction interfering with formation in the blood of thrombin microamounts. With hypercoagulation becoming more pronounced and with a further increase of blood thrombin concentration the content of antithrombin III progressively descends, which is accompanied by steady development of anticoagulation function suppression.     

Blood coagulation and immunological changes associated with frostbite at high altitude

In 15 cases of frostbite among soldiers stationed between 3690 and 5540 m altitude in the Himalayas investigations of blood coagulation and immunoglobulins were carried out within 24 hours, after 4 weeks and one year. In frostbite evidences of intravascular coagulation were the presence of increased amounts of FDPs in serum, reduction of plasma fibrinogen, fall in platelet counts and haematocrit, increased platelet adhesiveness, and prolonged euglobulin lysis time. Marked lowering of antithrombin III and protease inhibitors -1 antitrypsin and 2 macroglobulin indicate their increased consumption in the pathological process. Increased immunolglobulins with relative decrease of albumin and the appearance of cryoglobulins in the form of IgG, IgA and IgM complexes, also seem to promote platelet aggregation and release reaction. Anticoagulant therapy combined with antiplatelet adhesive drugs, if instituted in the early stages of frostbite might be successful in preventing damage resulting from intravascular coagulation.     

Low-density lipoprotein derived from atherosclerotic patients enhances macrophage cholesterol accumulation and in vitro platelet aggregation

The aims of our study were to assess the differences between plasma lipoproteins separated from five angiographically normal subjects and five patients with proven CHD. The patients with CHD had significantly higher levels of LDL-cholesterol and apo-B, and reduced levels of HDL-cholesterol and apo-Al. The biological characteristics of LDL and HDL from both groups of patients demonstrated that the LDL from the CHD patients enhanced platelet aggregation and increased cholesterol content and cholesterol esterification in MPM compared to the normal patients. HDL had no significant effect on MPM; however, there was an increased platelet aggregation with HDL derived from the CHD patients, while the HDL from the normal group decreased platelet aggregation. The data suggest that lipoproteins isolated from CHD patients are more atherogenic than lipoproteins from normal patients.     

Changes in blood lipids and blood pressure during adolescence.

A total of 625 adolescents from three general practices participated in a cross-sectional study of cardiovascular disease risk factors. The girls had higher serum total and high density lipoprotein (HDL) cholesterol concentrations than the boys, while the boys had higher serum triglyceride concentrations. Smoking (equally prevalent in both sexes) was associated with lower HDL cholesterol concentrations, particularly in boys, while in girls use of oral contraceptives was associated with higher total cholesterol and lower HDL cholesterol concentrations showed striking associations with age, height, and sexual maturation in boys, but not in girls. Triglyceride concentrations were associated with age in boys. Systolic blood pressure and serum urate concentrations were higher in boys and rose steeply with age, but no age association was seen for urate concentrations or systolic blood pressure in girls or for diastolic pressures in either sex. Girls, however, had higher diastolic pressures. There was a strong association between urate concentration and the other cardiovascular disease risk factors, especially HDL cholesterol. Adolescence is associated with considerable changes in cardiovascular disease risk factors, and there are striking sex differences in these changes.     

Adrenergic mechanisms in control of plasma lipid concentrations.

The mechanisms of the changes in plasma lipids concentrations observed after beta-blockade were examined in 53 patients with hypertension receiving treatment with atenolol, metoprolol, propranolol, and oxprenolol in a randomised cross-over trial. Significant increases in mean plasma total and very-low-density lipoprotein (VLDL) triglyceride and reductions in high-density lipoprotein (HDL) cholesterol and free fatty acids concentrations wer observed with all four drugs, the increase in plasma triglyceride concentration being greatest after propranolol and oxprenolol. No significant changes were observed in total of LDL cholesterol concentrations, but HDL:LDL ratios and HDL cholesterol as a proportion of total cholesterol fell significantly. Thus plasma lipid concentrations should be monitored after three to six months of long-term treatment. Changes in triglyceride, HDL cholesterol and free fatty acid concentrations were associated with a highly significant reduction in clearance of soya oil (Intralipid) in 25 patients studied but were unrelated to changes in blood pressure. The fall in HDL cholesterol and rise in free fatty acid concentrations were significantly less in those with initially reduced HDL cholesterol or raised free fatty acid concentrations respectively. It is proposed that unopposed alpha stimulation inhibits lipoprotein lipase with a subsequent rise in plasma triglyceride and fall in HDL cholesterol concentration. Analysis of the relation between pretreatment concentrations and subsequent changes suggests that excessive alpha stimulation may impair production of HDL cholesterol in those with low HDL cholesterol concentrations before treatment. Subtle catecholamine-mediated changes in plasma lipid concentrations might provide a mechanism for the relation between stress and the development of cardiovascular events.     

High density lipoprotein modulates platelet function.

BACKGROUND: Platelet activation by atherogenic lipoproteins can be antagonized by high density lipoprotein (HDL), probably via interaction with the ATP-binding cassette transporter A1 (ABCA1). METHODS: ABCA1 expression and its association with cholesterol rich membrane domains was analyzed by mRNA and Western blot analysis. HDL effects on platelet receptor clustering were analyzed by flow cytometric analysis of fluorescence resonance energy transfer between fluorochrome-labeled antibodies. RESULTS: ABCA1 expression increased upon megakaryocytic differentiation of human stem cells and ABCA1 protein partially associated to LubroIWX-resistant membrane domains. Plasma HDL-cholesterol in healthy donors negatively correlated to the platelet membrane cholesterol content. Receptor cluster analysis revealed a decrease in the association of Gplb and FcgammaRII upon incubation of platelets with HDL3. CONCLUSION: Our results suggest that HDL modulates platelet reactivity by altering lipid raft associated receptor clustering.     

Insulin sensitivity and regular alcohol consumption: large,prospective, cross sectional population study (Bruneck study)

OBJECTIVES: To assess the relation between regular alcohol consumption and insulin sensitivity, and to estimate the importance of insulin in the association of alcohol with multiple vascular risk factors and cardiovascular disease. DESIGN: Prospective and cross sectional study of a large randomly selected population sample. SETTING: Part of the Bruneck study 1990-5 (Bolzano province, Italy). SUBJECTS: 820 health, non-diabetic women and men aged 40-79 years. MAIN OUTCOME MEASURE: Concentrations of fasting and post-glucose insulin, cholesterol, apolipoproteins, triglycerides, Lp(a) lipoprotein glucose, fibrinogen, and antithrombin III; blood pressure; insulin resistance estimated by the homeostasis model assessment. RESULTS: Fasting insulin concentrations in those who did not drink alcohol and subjects reporting low (1-50 g/day), moderate (51-99 g/day), and heavy (> or = 100 g/day) alcohol intake were 12.4, 10.0, 8.7, and 7.1 mU/l (P < 0.001). Likewise, post-glucose insulin concentrations and estimates for insulin resistance assessed by the homeostasis model assessment decreased significantly with increasing amounts of regular alcohol consumption. These trends were independent of sex, body mass index, physical activity, cigarette smoking, medication, and diet (P < 0.001). Regular alcohol intake predicted multiple changes in vascular risk factors over a five year period including increased concentrations of high density lipoprotein cholesterol and apolipoprotein A I; higher blood pressure; and decreased concentration of antithrombin III. These associations were in part attributable to the decrease in insulin concentrations observed among alcohol consumers. CONCLUSIONS: Low to moderate amounts of alcohol, when taken on a regular basis, improve insulin sensitivity. Insulin is a potential intermediate component in the association between alcohol consumption and vascular risk factors (metabolic syndrome).     

Multivariate analysis for the understanding of typical diabetic hemostasis criteria. 3. Determination of a typical retinopathy parameter-constellation]

Features of metabolism and haemostasis which are different in diabetics of both types in comparison with normal subjects were covered by the statistical method of multivariance analysis depending on the severity of diabetic retinopathy. In 29 diabetics without retinopathy, 46 patients with stage I or II, and 36 patients with stage III the following parameters could be found as optimal criteria for characterizing the extent of vascular changes: blood sugar concentration, concentration of sialic acid and HDL cholesterol in the serum, serum protein, sialic acid per protein volume, total cholesterol in the serum and capillary fragility and number of large spreading forms of platelets features of hemostasis. Thus, diabetic retinopathy is characterized by a wide spectrum of different features containing the parameters of hemostasis. Thrombocytic vascular interactions are characterized by platelet spreading and capillary fragility which are significant for the development of diabetic retinopathy.     

Platelet Defect of Infectious Mononucleosis

Platelet function has been studied in 16 patients with uncomplicated infectious mononucleosis. Some abnormality of platelet aggregation and/or release of platelet factor III or platelet factor IV was found in all patients. Six patients with platelet defects were retested after three to four months and were found to have normal platelet function and appreciably higher platelet counts. Abnormal platelet function may reflect a platelet defect which predisposes to premature platelet destruction. Recent viral illness should be excluded before attributing abnormal platelet function to other factors or to a congenital disorder.     

Antithrombin III stimulates prostacyclin production by cultured aortic endothelial cells

Prostacyclin (PGI2) is a potent vasodilator and an inhibitor of platelet aggregation. We found that antithrombin III (AT III), an anticoagulant present in circulating blood, stimulated PGI2 production by cultured bovine aortic endothelial cells in a dose- and time-dependent manner. The stimulation of PGI2 production by AT III was observed at physiological concentrations and was inhibited by the addition of anti-AT III antiserum and heparin. These results suggest that AT III may stimulate PGI2 production by binding to heparin-like molecules on the endothelial cell membrane.     

Monitoring complex formation in the blood-coagulation cascade using aptamer-coated SAW sensors

Specific binding of the anticoagulants heparin and antithrombin III to the blood clotting cascade factor human thrombin was recorded as a function of time with a Love-wave biosensor array consisting of five sensor elements. Two of the sensor elements were used as references. Three sensor elements were coated with RNA or DNA aptamers for specific binding of human thrombin. The affinity between the aptamers and thrombin, measured using the biosensor, was within the same range as the value of K(D) measured by filter binding experiments. Consecutive binding of the thrombin inhibitors heparin, antithrombin III or the heparin-antithrombin III complex to the immobilized thrombin molecules, and binding of a ternary complex of heparin, anithrombin III, and thrombin to aptamers was evaluated. The experiments showed attenuation of binding to thrombin due to heparin-antithrombin III complex formation. Binding of heparin activated the formation of the inhibitory complex of antithrombin III with thrombin about 2.7-fold. Binding of the DNA aptamer to exosite II appeared to inhibit heparin binding to exosite I.     

Haemostasis and oral contraceptives

Selected hemostasis parameters were assayed in 131 women ingesting different kinds of oral contraceptives and 36 control women. No differences were noted in the plasma levels of fibrinogen, antithrombin III, prekallikrein, alpha 2 antiplasmin, fibrinopeptide A, platelet factor 4 and beta-thromboglobulin. Protein C and plasminogen levels were significantly higher in pill users (p less than 0.001, p less than 0.01) and fibronectin levels were lower (p less than 0.05). Canonical correlation, performed between clinical parameters and hemostasis data, revealed a negative correlation between antithrombin III levels and family history for thromboembolic diseases. A positive correlation was noted between fibrinogen and fibronectin levels in obese OC users. The data suggest that women taking OCs are not in a state of "hypercoagulability."