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At least 703 records · Page 39Linked to original sources
PubMed1999

The effect of fish oil on hypertension, plasma lipids and hemostasis in hypertensive, obese, dyslipidemic patients with and without diabetes mellitus.

We have recently reported that dietary fish oil supplementation (n-3) polyunsaturated fatty acid (PUFA) led to a reduction in blood pressure (BP) and serum triglycerides (TG), in addition to the normalization of the hypercoagulable state in subjects with obesity, hypertension and dyslipidemia without diabetes mellitus (OHD-DM). The aim of the present study was to explore the mechanism of this amelioration by comparing the previous results to those obtained from 19 subjects who, in addition to the conditions described above, also suffer from diabetes mellitus (OHD+DM) and proteinuria. In both the non-diabetic and diabetic groups, a similar reduction was observed in BP (from 158.7/80.8 to 146/72.9 mmHg, and from 157.6/83.2 to 141.9/75.6 mmHg, respectively, P<0.001) and TG levels (from 159.2 to 108.0 mg/dl and from 208.7 to 153.1 mg/dl, respectively, P<0.001). However, a favorable reduction in hemostasis parameters (platelet aggregation on extracellular matrix and (alpha2-antiplasmin) was only seen among the nondiabetic patients (from 12.1+/-4.9 to 4.2+/-3.2%, P<0.001). This difference may stem from a less efficient exchange between n-3 and n-6 PUFA in serum phospholipid of the OHD+DM patients. Overall, this 13-day fasting/refeeding method developed by us has proven to cause the rapid exchange of arachidonic acid for eicosapentaenoic acid. It appears to be an effective regimen for the reduction of cardiovascular risk factors (BP, TG and hemostatic variables) in OHD-DM patients and to a lesser extent in OHD+DM patients.

Aged↗
PubMed1995

Influence of HPA-1a and HLA antibodies on primary hemostasis.

The influence of platelet specific and HLA antibodies was investigated on primary hemostasis by the in vitro bleeding test (IVBT) (Thrombostat 4000). Seven of 12 plasmas with HPA-1a (P1A1) antibodies and two with antibodies against glycoprotein Ib/IX significantly inhibited the IVBT of normal, cross-match-positive donor blood. This correlated with a significant increase of GMP-140 (CD 62) on the platelets, determined by flow cytometry. These results agree with the literature showing both activation and inhibition of platelet function by platelet specific antibodies. On the other hand, HLA antibodies showed a similar platelet activation (shortening of occlusion time and decrease in blood volume in the IVBT, increase of CD 62 expression) as plasma samples of polytransfused thrombocytopenic patients without HLA antibodies. It can be concluded that neither an activating nor an inhibitory effect of HLA antibodies on platelet function is significant in vivo. The IVBT seems not to be suited for compatibility testing.

Antibodies↗
PubMed1995

Primary hemostasis during women's life cycle measured by Thrombostat 4000.

The Thrombostat 4000 was used to investigate primary hemostasis in women during different stages of their life cycle. Nonpregnant females were studied during their proliferative and luteal phases; pregnant women were investigated during their 28-35th weeks of gestation and some women between the ages of 70-84. Data were compared to those obtained from male volunteers injected with 40 mg estrogen. No significant differences between proliferative and luteal phases were found, but BT2 was prolonged in the elderly women. In the pregnant women extremely short BT2 values were measured. Shortening of BT2 was also seen in the males injected with estrogen.

Adult↗
PubMed2001

Endoscopic factors predisposing to rebleeding following endoscopic hemostasis in bleeding peptic ulcers.

BACKGROUND AND STUDY AIMS: Various clinical and endoscopic factors have been proposed and used as predictors of endoscopic treatment failure in bleeding peptic ulcers. Recently, several endoscopic factors have been considered to be more significant than various clinical factors, except for shock. Detailed knowledge of which endoscopic factors can be classified as predictors of rebleeding following endoscopic hemostasis is needed. This study describes newly defined endoscopic variables and evaluates their usefulness as predictors of endoscopic treatment failure. PATIENTS AND METHODS: Between January 1996 and April 1999, diagnostic and therapeutic endoscopies were carried out in 143 patients with active bleeding peptic ulcers. Nine clinical and eight endoscopic variables were studied. Endoscopic factors were classified by three types of stigmata bleeding, 14 locations, two ulcer sizes, three ulcer bases, three visible vessel colors, two ulcer depths, two margin shapes, and three endoscopic treatment methods (injection, hemoclipping, and combination). RESULTS: 36 patients experienced rebleeding (25.2 %), 11 patients needed operations (7.7 %) and five deaths occurred (3.5 %). In univariate analysis, rebleeding was significantly related to: i) presence of spurting activity (odds ratio [OR] = 4.91, P = 0.006), ii) ulcer size larger than 2 cm (OR = 2.78, P = 0.017); and iii) location in stomach (OR = 2.81, P = 0.026). Clinical variables including age, shock, and initial hemoglobin levels were not significantly related to rebleeding. In multiple logistic regression using selected significant variables, presence of spurting activity remained a significant independent predictor of rebleeding (adjusted OR = 6.48, P = 0.003). CONCLUSION: Our data support the hypothesis that endoscopic factors are more important than clinical ones when predicting rebleeding of peptic ulcers. Based on statistical analysis of risk factors, the ulcers most likely to rebleed after endoscopic therapy are those which are located in the stomach, are greater than 2 cm in diameter and exhibit oozing or spurting of blood.

Adolescent↗
PubMed2003

Developmental hemostasis: pro- and anticoagulant systems during childhood.

An understanding of developmental hemostasis is pivotal for optimal prevention, diagnosis, and treatment of hemostatic problems during childhood. The development of microassays in the early 1980s enabled researchers to delineate age-dependent features of the coagulation system and to establish reference ranges for healthy children of all age groups, from premature infants to adolescents. Based on the results from these studies, the hemostatic system in the young can be described as evolving, and yet functional, since healthy fetuses, infants, and children do not suffer hemorrhagic nor thromboembolic complications spontaneously or in the presence of minor challenges. Plasma concentrations of most pro- and anticoagulant proteins are decreased throughout childhood but provide an effective hemostatic balance on a lower level compared with adults. The current article describes the development of pro- and anticoagulant systems throughout childhood.

Age Factors↗
PubMed2005

Diet and aging: bearing on thrombosis and hemostasis.

Diet is one of the environmental factors that influences thrombosis and hemostasis. Macronutrients, micronutrients, and other bioactive food components alter the predisposition to thrombosis. The type and amount of dietary fat has been shown to alter thromboxane A2 production and platelet aggregation, bleeding time, factor VII, fibrinogen, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1). Both epidemiological studies and clinical trials indicate that the very long chain n-3 fatty acids lower thrombotic tendency and risk of heart disease. Other polyunsaturated fats and monounsaturated fat appear to have antithrombotic properties, but further studies are indicated. Hypercaloric diets and those with high glycemic loads are associated with elevations of PAI-1. Moderate consumption of alcohol is associated with decreased platelet aggregation. Low intakes of folate, vitamin B12, and vitamin B6 predispose to hyperhomocysteinemia, and the benefits of supplementation in decreasing vascular disease are under investigation. In a limited number of clinical and laboratory studies, vitamin E has been shown to decrease platelet aggregation and the concentration of PAI-1. Flavonoids and isoflavones appear to inhibit platelet aggregation at pharmacologic concentrations only. Nutritional status frequently declines with aging and may exacerbate the already increased risk for thrombosis. Diet presents an interesting area for research into thrombophilia, but additional work is indicated before specific recommendations are made.

Aging↗
PubMed2005

Visceral fat as a determinant of fibrinolysis and hemostasis.

An increased amount of deep abdominal visceral fat has generally been accepted as an important cardiovascular risk factor, and disturbances in hemostasis and fibrinolysis have been suggested to play a role. Fibrinogen and von Willebrand factor, representatives of the hemostatic system, and plasminogen activator inhibitor 1 (PAI-1), as the most important inhibitor of the fibrinolytic system, have been associated with visceral obesity, with the most convincing evidence found for the involvement of PAI-1. The association with fibrinogen and von Willebrand factor has been suggested to be merely a reflection of the association with inflammation and endothelial dysfunction. The fact that PAI-1 is secreted by adipose tissue has attracted much attention. The increase of PAI-1 in visceral obesity could be because visceral adipose tissue produces more PAI-1 compared with subcutaneous abdominal adipose tissue. The contribution of other cell types such as hepatocytes or endothelial cells is probably more important, with stimulation of PAI-1 production by different components of the metabolic syndrome. PAI-1 secretion by adipose tissue has been suggested to have a more local effect, playing a role in tissue remodeling during the development of obesity.

Adipose Tissue↗
PubMed1990

Endoscopic hemostasis of esophageal and gastric variceal bleeding with Histoacryl.

Endoscopic injection of the tissue adhesive n-butyl-2-cyano-acrylate (Histoacryl) has been tried for esophageal or fundic variceal bleeding in 23 patients. Definitive hemostasis was achieved in 22 with a single injection of Histoacryl. Throughout the entire hospitalization period, which was completed with at least two weekly sessions of conventional sclerotherapy, only one recurrent bleeding was recorded. Four patients died of hepatic decompensation. It is suggested that Cyanoacrylate could overcome some of the shortcomings of conventional sclerotherapy such as early recurrent hemorrhage and bleeding from fundic varices.

Adolescent↗
PubMed1984

Possible mechanism of hemostasis effected by electrocoagulation.

Forty acute gastric ulcers were created in 10 rabbits. The bleeding was controlled by monopolar electrocoagulation in 20 ulcers, the remaining ulcers were left untreated as controls. Spontaneous intravascular thrombosis was precluded by heparinization. A histological assessment in the acute stage revealed significant morphological alterations in electrocoagulated ulcers, with fibrin deposition, decreased tissue stainability and swelling of the vessel walls, indicating heat-induced damage including cells of the vessel walls. An intravascular occlusive fibrin thrombosis demonstrated in all coagulated ulcers is suggested to be the probable mechanism of hemostasis.

Animals↗
PubMed1999

High dose supplementation of RRR-alpha-tocopherol decreases cellular hemostasis but accelerates plasmatic coagulation in type 2 diabetes mellitus.

BACKGROUND: Diabetes mellitus is associated with increased generation of free oxygen radicals and depleted scavenging potential (oxidative stress), leading to increased LDL oxidation and platelet hyperreactivity, the major components of atherothrombotic vascular lesions. A main goal of antioxidant therapy is to protect the LDL particle from atherogenic oxidation and to reduce the activated cellular hemostasis. METHODS: We evaluated the influence of a high dose supplementation with 800 IU of the natural antioxidant RRR-alpha-tocopherol (vitamin E) per day for six months on serum levels, vitamin E load of LDL particles (HPLC), lag phase of LDL oxidation (Esterbauer's assay), platelet adhesion molecules, leukocyte-platelet coaggregation (flow cytometry, D-III protocol) and coagulation (INR/PTT) in a group of 36 patients with type 2 diabetes (f/m 22/14; age 58+/-8.0; HbA1 at baseline 10.25+/-1.7). RESULTS: Average vitamin E levels increased 2.65-fold accompanied by a 1.83-fold increase of LDL-associated vitamin E and a 12.3 min prolongation of the lag-phase of LDL oxidation (p<0.001 for all parameters at six months). Platelet expression of PECAM-1 (CD31) (-30.2% positive cells, p<0.001; antigen density -25%, p<0.001), ICAM-2 (CD102) (-2.9% positive cells, p<0.01; antigen density -10.6%, p<0.001) and fibrinogen (-1.6% positive cells, p<0.001; antigen density - 16.1 %, p<0.001) decreased. Concomitantly, platelet-leukocyte-coaggregation increased by 44% (p<0.001), correlating to an INR reduction of 10.4% (1.06+/-0.09 to 0.95+/-0.09, p<0.001, r = - 0.34). The PTT remained constant. CONCLUSION: The antioxidant protection from the increased vitamin E was accompanied by a decreased expression of constitutive and function-dependent platelet adhesion molecules. However, increases in platelet-leukocyte coaggregates and a shortened INR time suggest extrinsic coagulation activation, possibly by induction of a leukocyte tissue factor dependent mechanism. High dose supplements of alpha-tocopherol may override the available redox balance in well controlled type 2 diabetes. However, intrinsic effects of alpha-tocopherol must be discussed.

Aged↗
PubMed2006

Modular chemical mechanism predicts spatiotemporal dynamics of initiation in the complex network of hemostasis.

This article demonstrates that a simple chemical model system, built by using a modular approach, may be used to predict the spatiotemporal dynamics of initiation of blood clotting in the complex network of hemostasis. Microfluidics was used to create in vitro environments that expose both the complex network and the model system to surfaces patterned with patches presenting clotting stimuli. Both systems displayed a threshold response, with clotting initiating only on isolated patches larger than a threshold size. The magnitude of the threshold patch size for both systems was described by the Damköhler number, measuring competition of reaction and diffusion. Reaction produces activators at the patch, and diffusion removes activators from the patch. The chemical model made additional predictions that were validated experimentally with human blood plasma. These experiments show that blood can be exposed to significant amounts of clot-inducing stimuli, such as tissue factor, without initiating clotting. Overall, these results demonstrate that such chemical model systems, implemented with microfluidics, may be used to predict spatiotemporal dynamics of complex biochemical networks.

Blood Coagulation↗
PubMed1998

A mouse model of severe von Willebrand disease: defects in hemostasis and thrombosis.

von Willebrand factor (vWf) deficiency causes severe von Willebrand disease in humans. We generated a mouse model for this disease by using gene targeting. vWf-deficient mice appeared normal at birth; they were viable and fertile. Neither vWf nor vWf propolypeptide (von Willebrand antigen II) were detectable in plasma, platelets, or endothelial cells of the homozygous mutant mice. The mutant mice exhibited defects in hemostasis with a highly prolonged bleeding time and spontaneous bleeding events in approximately 10% of neonates. As in the human disease, the factor VIII level in these mice was reduced strongly as a result of the lack of protection provided by vWf. Defective thrombosis in mutant mice was also evident in an in vivo model of vascular injury. In this model, the exteriorized mesentery was superfused with ferric chloride and the accumulation of fluorescently labeled platelets was observed by intravital microscopy. We conclude that these mice very closely mimic severe human von Willebrand disease and will be very useful for investigating the role of vWf in normal physiology and in disease models.

Animals↗
PubMed1995

The interaction of fibulin-1 with fibrinogen. A potential role in hemostasis and thrombosis.

The fibulins are an emerging family of extracellular matrix and blood proteins presently having two members designated fibulin-1 and -2. Fibulin-1 is the predominant fibulin in blood, present at a concentration of 30-40 micrograms/ml (approximately 1000-fold higher than fibulin-2). During the course of isolating fibulin-1 from plasma by immunoaffinity chromatography, a 340-kDa polypeptide was consistently found to co-purify. This protein was identified as fibrinogen (Fg) based on its electrophoretic behavior and reactivity with Fg monoclonal antibodies. Radioiodinated fibulin-1 was shown to bind to Fg transferred onto nitrocellulose filters after SDS-polyacrylamide gel electrophoresis. In enzyme-linked immunosorbent assay, fibulin-1 bound to Fg (and fibrin) adsorbed onto microtiter well plastic, and conversely, Fg bound to fibulin-1-coated wells. The binding of Fg to fibulin-1 was also observed in surface plasmon resonance assays, and a dissociation constant (Kd) of 2.9 +/- 1.6 microM was derived. In addition, fluorescence anisotropy experiments demonstrated that the interaction was also able to occur in fluid phase, which suggests that complexes of fibulin-1 and Fg could exist in the blood. To localize the portion of Fg that is responsible for interacting with fibulin-1, proteolytic fragments of Fg were evaluated for their ability to promote fibulin-1 binding. Fragments containing the carboxyl-terminal region of the Bbeta chain (residues 216-468) were able to bind to fibulin-1. In addition, it was found that fibulin-1 was able to incorporate into fibrin clots formed in vitro and was immunologically detected within newly formed fibrin-containing thrombi associated with human atherectomy specimens. The interaction between fibulin-1 and Fg highlights potential new roles for fibulin-1 in hemostasis as well as thrombosis.

Binding Sites↗
PubMed2002

Inhibition of hemostasis by a high affinity biogenic amine-binding protein from the saliva of a blood-feeding insect.

The saliva of the blood-feeding insect Rhodnius prolixus contains numerous pharmacologically active substances. Included among these are a number of lipocalin proteins that bind various ligands important in hemostasis and inflammation. One such protein is a biogenic amine-binding protein (ABP) that binds serotonin, epinephrine, and norepinephrine. Based on amino acid alignments, it is most similar to the nitrophorin group of lipocalins found in the same insect species. Physiologically, this protein appears to act as both a vasodilator and platelet aggregation inhibitor. This protein inhibits smooth muscle contraction of the rat uterus in response to serotonin and of the rabbit aorta in response to norepinephrine. Platelet aggregation induced by a combination of low concentrations of ADP and either serotonin or epinephrine is inhibited because of the binding of serotonin and epinephrine. Potentiation of aggregation induced by low concentrations of collagen along with serotonin or epinephrine is also inhibited. Dissociation constants for biogenic amines were measured using isothermal titration calorimetry and the Hummel-Dreyer method of equilibrium gel filtration. In this manner, K(d) values of 102, 24, and 345 nm were found for serotonin, norepinephrine, and epinephrine, respectively. Molecular modeling of ABP suggests that ligand binding is mediated by interaction with the side chains of aromatic amino acids and charged residues that line the binding pocket.

Amino Acid Sequence↗
PubMed2004

The role of intrinsic fibrinolytic system activation in pathogenesis of hemostasis disturbances in hemodialyzed patients with chronic renal failure.

In the hemodialysis patient, hemostasis changes may occur. The contribution of fibrinolysis in pathogenesis of these disorders is unclear. The aim of the study was to estimate intrinsic fibrinolysis pathway in patients treated with hemodialysis (HD) because of chronic renal failure caused by chronic glomerulonephritis. The study was performed with 43 patients; the control group consisted of 51 healthy volunteers chosen by sex and age. The following parameters were determined: concentration of the urokinase plasminogen activator antigen (uPA:Ag), plasmin--antiplasmin complexes (PAP), fibrin and fibrinogen degradation products (FDP), activity of prekallikrein (PK) and C1-inhibitor (C1-INH) and also euglobulin clot lysis time (ELT). The above parameters were assessed in the patients before and after HD and were compared with the control group. In the HD patients, in comparison with the control group, prolonged statistically ELT [153 (125;215) vs. 105 (75;142) min.; p<0.001], with increase of PAP (508.6 +/- 274.7 vs. 184.7 +/- 69.4 microg/L; p<0.001) and FDP concentrations [5 (5;15) vs. 2.5 (0;0.3) microg/mL; p<0.05] before the procedure were determined. It suggests increased plasmin production and fibrin digestion despite determination of decreased general fibrinolytic activity. The C1-INH activity before HD was also significantly increased as compared with the control group [157 (136;171) vs. 107 (100;124)%; p<0.001], and its significant decreased after the HD is 157.7 +/- 23.9 vs. 122.3 +/- 20.3%; p<0.001, as it seems to be a nondirect proof of intrinsic pathway contribution in fibrinolysis activation in the HD patients. The remaining examined parameters did not change significantly after the dialysis procedure.

Adult↗
PubMed2002

Zinc finger protein, Hzf, is required for megakaryocyte development and hemostasis.

Using an expression gene trapping strategy, we recently identified a novel gene, hematopoietic zinc finger (Hzf), which encodes a protein containing three C(2)H(2)-type zinc fingers that is predominantly expressed in megakaryocytes. Here, we have examined the in vivo function of Hzf by gene targeting and demonstrated that Hzf is essential for megakaryopoiesis and hemostasis in vivo. Hzf-deficient mice exhibited a pronounced tendency to rebleed and had reduced alpha-granule substances in both megakaryocytes and platelets. These mice also had large, faintly stained platelets, whereas the numbers of both megakaryocytes and platelets were normal. These results indicate that Hzf plays important roles in regulating the synthesis of alpha-granule substances and/or their packing into alpha-granules during the process of megakaryopoiesis.

Animals↗
PubMed2006

Associations of vitamin C status, fruit and vegetable intakes, and markers of inflammation and hemostasis.

BACKGROUND: It has been suggested that a high dietary intake and high circulating concentrations of vitamin C may protect against ischemic heart disease. OBJECTIVES: The objective was to examine the associations between dietary and plasma vitamin C concentrations, fruit and vegetable intakes, and markers of inflammation and hemostasis associated with cardiovascular disease in older men free of cardiovascular disease. DESIGN: This cross-sectional study examined 3258 men aged 60-79 y with no physician diagnosis of myocardial infarction, stroke, or diabetes and who were drawn from general practices in 24 British towns. Fruit and vegetable intakes and dietary vitamin C were assessed by using a food-frequency questionnaire. RESULTS: Plasma vitamin C, fruit intake, and dietary vitamin C intake were significantly and inversely associated with mean concentrations of C-reactive protein, an acute phase reactant, and tissue plasminogen activator (t-PA) antigen, a marker of endothelial dysfunction, even after adjustment for confounders. Vegetable intake was correlated significantly (inversely) only with t-PA. For plasma vitamin C (highest versus lowest quartile), the adjusted odds of elevated C-reactive protein and t-PA (highest tertile versus lowest tertile) were 0.56 (95% CI: 0.44, 0.71) and 0.79 (0.62, 1.00); for fruit intake, the corresponding odds ratios were 0.76 (0.60, 0.95) and 0.76 (0.61, 0.95). Plasma (but not dietary) vitamin C also showed inverse associations with both fibrinogen concentrations and blood viscosity. No associations were seen with von Willebrand factor or factor VIII. CONCLUSION: The findings suggest that vitamin C has antiinflammatory effects and is associated with lower endothelial dysfunction in men with no history of cardiovascular disease or diabetes.

Acute-Phase Proteins↗