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Biomedical subjects

E Briet

Publications and source records attributed to E Briet.

15 recordsLinked to original sources
PubMed1996

Hyperhomocysteinemia as a risk factor for deep-vein thrombosis.

BACKGROUND: Previous studies have suggested that hyperhomocysteinemia may be a risk factor for venous thrombosis. To assess the risk of venous thrombosis associated with hyperhomocysteinemia, we studied plasma homocysteine levels in patients with a first episode of deep-vein thrombosis and in normal control subjects. METHODS: We measured plasma homocysteine levels in 269 patients with a first, objectively diagnosed episode of deep-vein thrombosis and in 269 healthy controls matched to the patients according to age and sex. Hyperhomocysteinemia was defined as a plasma homocysteine level above the 95th percentile in the control group (18.5 micromol per liter). RESULTS: Of the 269 patients, 28 (10 percent) had plasma homocysteine levels above the 95th percentile for the controls, as compared with 13 of the controls (matched odds ratio, 2.5; 95 percent confidence interval, 1.2 to 5.2). The association between elevated homocysteine levels and venous thrombosis was stronger among women than among men and increased with age. The exclusion of subjects with other established risk factors for thrombosis (e.g., a deficiency of protein C, protein S, or antithrombin; resistance to activated protein C; pregnancy or recent childbirth; or oral-contraceptive use) did not materially affect the risk estimates. CONCLUSIONS: High plasma homocysteine levels are a risk factor for deep-vein thrombosis in the general population.

Adolescent↗
PubMed1993

Haemophilia: strategies for carrier detection and prenatal diagnosis.

In 1977 WHO published in the Bulletin a Memorandum on Methods for the Detection of Haemophilia Carriers. This was produced following a WHO/WFH (World Federation of Haemophilia) Meeting of Investigators in Geneva in November 1976, and has served as a valuable reference article on the genetics of haemophilia. The analyses discussed were based on phenotypic assessment, which, at that time, was the only procedure available. The molecular biology revolution in genetics during the 1980s made enormous contributions to our understanding of the molecular basis of the haemophilias and now permits precise carrier detection and prenatal diagnosis. WHO and WFH held a joint meeting on this subject in February 1992 in Geneva. This article is the result of these discussions.

Base Sequence↗
PubMed1991

Systemic effects of collagen-impregnated aortoiliac Dacron vascular prostheses on platelet activation and fibrin formation.

To minimize intraoperative blood loss a watertight knitted Dacron aortoiliac prosthesis has been developed by impregnation with bovine collagen. A potential disadvantage is that collagen may be associated with an increase in thrombus formation. We conducted a prospective randomized trial to study the systemic effects of collagen-impregnated prostheses and of aortoiliac operation as such on the coagulation mechanism during the first 10 days after operation. Forty-one patients randomly received either a collagen-impregnated (n = 20) or a nonimpregnated prosthesis (n = 21). Twelve patients who underwent cholecystectomies served as controls. Three markers of the coagulation mechanism were monitored: beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation products. We found no significant differences in median beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation product levels between patients in the collagen-impregnated prosthesis group and patients in the nonimpregnated prosthesis group. This indicates that collagen does not stimulate the coagulation cascade any more than conventional Dacron protheses do. In a comparison of patients who underwent aortoiliac reconstruction and patients who underwent cholecystectomies, the results indicated a significant increased platelet activation and fibrin metabolism in aortoiliac reconstruction group compared with the control group. Finally, we observed a significantly higher preoperative fibrin metabolism in patients with vascular disease than in control subjects. This difference is attributable to the high preoperative fibrin/fibrinogen degradation product values in patients with aortic aneurysms.

Adult↗
PubMed1990

An infrequent DNA polymorphism associated with severe von Willebrand's disease.

Genomic DNA of six unrelated Dutch patients with severe von Willebrand's disease (vWD) was submitted to restriction fragment length polymorphism analysis. We observed a strong association between a 36 kb allele detected by a partial complementary DNA probe (pvWF 1100) and the restriction enzyme XbaI with severe von Willebrand's disease. This 36 kb allele is rare (allele frequency of 7%) both in the general population and in patients with autosomal dominant types of von Willebrand's disease. Three of our six patients were found to be homozygous for this allele while two others were heterozygous. The association of this rare XbaI allele with severe vWD enables carrier detection and prenatal diagnosis in these families. The high frequency (67%) of the 36 kb allele observed in this patient group raises the possibility that a subgroup of patients with severe vWD has a genetic defect with a common origin.

Alleles↗
PubMed1990

An evaluation of 75 terminations of pregnancy based on abnormal laboratory findings at first trimester CVS.

Seventy-five selective terminations, based on abnormal laboratory findings at first-trimester CVS, were performed in 1581 consecutive pregnancies. In all cases a (semi-) direct method of cytogenetic analysis was used. The 75 abortions were analysed in number of ways. Confirmatory studies showed that three cases had to be considered as false-positive findings, and in one other case the results were inconclusive. Based on literature data, it was estimated that 41 of the 75 pregnancies would have resulted in seriously handicapped children, surviving beyond the age of 1 year, if no termination of pregnancy had taken place. Negative side-effects of the procedure include: spontaneous abortion of chromosomally normal fetuses due to the CVS procedure itself and the need for a number of secondary amniocenteses (5.1%). The advantage of DNA diagnosis in X-linked diseases is illustrated by comparing the CVS results with a previously published amniocentesis study.

Abortion, Eugenic↗
PubMed1989

A randomized and blinded comparison of the sensitivity and the reproducibility of the Ivy and Simplate II bleeding time techniques.

The authors compared the sensitivity and the reproducibility of the bleeding time techniques according to Ivy and Simplate II. The sensitivity was studied in two groups: one group of 64 healthy volunteers and another group of 40 patients with various disorders of hemostasis, including 28 patients with Von Willebrand's disease. Ivy and Simplate II bleeding times were performed on each subject. The reproducibility was studied in 48 patients with mildly or moderately prolonged bleeding times that resulted from various disorders who had a duplicate Ivy or a duplicate Simplate II bleeding time. All subjects were randomized over the technologists and they were blinded for each other's results. By a receiver operating characteristic analysis, the Ivy method appeared to offer greater overall detection efficacy than the Simplate II method. For the Ivy method, the standard deviation of the ratios of the duplicate bleeding times was 0.37 and for the Simplate II method it was 0.33. The authors conclude that the Simplate II method is not superior in sensitivity or reproducibility to the Ivy method, which is cheaper, takes less time, and does not leave scars.

Adult↗
PubMed1986

Hemostasis and periventricular-intraventricular hemorrhage of the newborn.

In a prospective study we analyzed the role of coagulopathy in the development of periventricular-intraventricular hemorrhage (PIVH) in 49 consecutively admitted preterm infants of less than 34 weeks' gestation by serial ultrasound examinations and coagulation assays. In 20 patients (41%) PIVH was detected. On the day of birth, patients with PIVH had significantly lower levels of factor V than did the patients without PIVH, but all other clotting factors gave similar results, and on the third and fifth days all results were similar, including those for factor V. Even the small subgroup of infants who subsequently developed grade IV hemorrhage did not have a more severe coagulopathy than the other infants, although they had significantly lower levels of platelets and of factor VII at birth. We conclude that coagulopathy does not play an important role in the etiology of PIVH. Standard doses of 10 mL/kg of fresh-frozen plasma, administered to increase the low levels of clotting factors, did not prevent extension of the hemorrhage.

Blood Coagulation Disorders↗
PubMed1985

Characterization of the clotting activities of structurally different forms of activated factor IX. Enzymatic properties of normal human factor IXa alpha, factor IXa beta, and activated factor IX Chapel Hill.

Two structurally different forms of activated human Factor IX (Factor IXa alpha and IXa beta) have been previously reported to have essentially identical clotting activity in vitro. Although it has been shown that activated Factor IX Chapel Hill, an abnormal Factor IX isolated from the plasma of a patient with mild hemophilia B, and normal Factor IXa alpha are structurally very similar, the clotting activity of activated Factor IX Chapel Hill is much lower (approximately fivefold) than that of normal Factor IXa beta. In the present study we have prepared activated Factor IX by incubating human Factor IX with calcium and Russell's viper venom covalently bound to agarose. Fractionation of the activated Factor IX by high-performance liquid chromatography demonstrated the presence of both Factors IXa alpha and IXa beta. On the basis of active site concentration, determined by titration with antithrombin III, the clotting activities of activated Factor IX Chapel Hill and IXa alpha were similar, but both activities were less than 20% of the clotting activity of Factor IXa beta. Activated Factor IX activity was also measured in the absence of calcium, phospholipid, and Factor VIII, by determination of the rate of Factor X activation in the presence of polylysine. In the presence of polylysine, the rates of Factor X activation by activated Factor IX Chapel Hill, Factor IXa alpha, and Factor IXa beta were essentially identical. We conclude that the clotting activity of activated Factor IX Chapel Hill is reduced when compared with that of Factor IXa beta but essentially normal when compared with that of Factor IXa alpha.

Blood Coagulation↗
PubMed1982

Cleavage and activation of human prothrombin by Echis carinatus venom.

The cleavage of human prothrombin by partially purified Echis carinatus venom (ECV) was investigated in the present report. Incubation of prothrombin with ECV resulted in the rapid cleavage of prothrombin to alpha-thrombin, with the release of fragment-1 and fragment-2. When dansyl arginine-N-(3-ethyl-1,5-pentanediyl) amide (DAPA), a very effective inhibitor of thrombin, was included in the ECV-prothrombin solution, meizothrombin was rapidly formed. Only small amounts of meizothrombin-1 could be detected. Prolonged incubation (23 h) in the presence of DAPA, however, resulted in nearly quantitative conversion of meizothrombin to meizothrombin-1 and fragment-1. Kinetic studies strongly suggested that the conversion of meizothrombin to meizothrombin-1 was due to ECV and not meizothrombin autolysis. In addition, EDTA, which inhibits ECV, blocked the cleavage of meizothrombin. Amino terminal sequence analysis indicated that ECV cleaves human prothrombin at two sites; Gly158-Ser159 and Arg322-Ile323. The former site differs from the site of autolytic cleavage of meizothrombin which occurs at Arg155-Ser156. In contrast to reports in the literature, the results of the present study indicate that the release of fragment-1 does not precede activation of human prothrombin by ECV.

Amino Acid Sequence↗
PubMed1982

Factor IX levels during pregnancy in a women with hemophilia B.

The levels of factors VIII, II, and VII rise during pregnancy in normal women. In addition, increases in factor VIII levels have been observed in pregnant carriers of hemophilia A and in women affected with von Willebrand's disease. The influence of pregnancy on factor IX levels is less clear. Consequently, we determined serial factor IX coagulant activities (IX:C) and factor IX antigen levels (IX:Ag) during the pregnancy of an affected carrier of hemophilia B who had baseline values of 13% both IX:C and IX:Ag levels. Neither level rose during pregnancy and the patient was treated with plasmapheresis and plasma infusions during the delivery and the postpartum period. Excessive bleeding did not occur.

Adult↗