Biomedical subjects

T Koster

Publications and source records attributed to T Koster.

27 records · Page 2Linked to original sources

PubMed1994

John Hageman's factor and deep-vein thrombosis: Leiden thrombophilia Study.

Because the relationship between factor XII deficiency and venous thrombosis is unclear and study results seem contradictory, we undertook a population-based case-control study. Among 350 unselected patients younger than 70 years, with a first, objectively confirmed, episode of deep-vein thrombosis and without underlying malignant disease we detected a 6% frequency (21/350 patients) of factor XII deficiency (activity level < 57%). Among 350 healthy control subjects, matched for age and sex, the frequency was 5% (18 subjects). Thus there is no increase in prevalence of factor XII deficiency among thrombosis patients and no increase in thrombosis risk for subjects with low factor XII levels (matched odds ratio 1.2 (95% CI 0.6-2.4)). In addition, there was no relation between strata of factor XII levels and thrombosis risk. In conclusion, we do not consider factor XII to be a determinant of deep-vein thrombosis.

Adolescent↗

PubMed1994

Factor VII and fibrinogen levels as risk factors for venous thrombosis. A case-control study of plasma levels and DNA polymorphisms--the Leiden Thrombophilia Study (LETS).

The plasma levels of coagulation factor VII and fibrinogen are well known risk factors for arterial thrombosis. We tested the hypothesis that this association also exists for venous thrombosis. Additionally, MspI and HaeIII polymorphisms in the factor VII and fibrinogen genes have recently been reported to be associated with the concentration of both proteins in the plasma. However, no conclusion could be drawn with respect to an increase or decrease in thrombosis risk. We undertook a population-based case-control study, in which 199 patients with a population-based case-control study, in which 199 patients with a first, objectively confirmed episode of deep vein thrombosis, aged less than 70, and without a known malignant disorder were compared to 199 age- and sex-matched healthy controls, to evaluate the clinical importance of these reported findings. For fibrinogen we found a positive level-related association between the plasma fibrinogen level and thrombotic risk. Subjects with a plasma fibrinogen greater than 5 g/l had an almost 4-fold increase of thrombosis risk. The frequencies of the different HaeIII genotypes were out of balance only for the thrombosis patients, with a deficit of the H1H2 genotype. Possession of an H1H2 genotype was associated with a 40% reduction in thrombosis risk. For factor VII, neither the plasma level nor the MspI genotypes were related to deep vein thrombosis, although possession of a M2 allele was clearly associated with significantly lower factor VII levels. The frequencies of the MspI-genotypes were the same for patients and control subjects and exhibited Hardy-Weinberg equilibrium. (ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Lover's arm.

Explore the source record for details and available documents.

Adult↗

PubMed1992

A randomized and blinded comparison of three bleeding time techniques: the Ivy method, and the Simplate II method in two directions.

We compared the Ivy bleeding time method and two alternatives of the Simplate II method (incisions in horizontal and vertical direction) with each other, with regard to the sensitivity, the specificity, the costs and the burden for the patient. In the aspirin study an aspirin-induced bleeding defect was used. Seventy-two healthy volunteers were randomized to receive either 500 mg acetylsalicylic acid (ASA) or a placebo. Double blinding was maintained throughout the study. In the anticoagulation study 62 patients participated, who received oral anticoagulants (OAC) for various reasons. All participants received two bleeding time methods. The burden for the participants of each method was screened by a small standard questionnaire. The differences in sensitivity and specificity between the three methods proved minimal. The Ivy method was more often preferred by the participants than the Simplate methods. Since a choice on the basis of sensitivity and specificity appears not possible, we prefer the Ivy method because of lower costs and less burden.

Adult↗

PubMed1992

Helicobacter pylori, musings from the epidemiologic armchair.

The literature on Helicobacter pylori has become enormous, but the epidemiology of the infection remains an enigma. Guided by epidemiologic principles we have tried to interpret the available data on the epidemiologic aspects of H. pylori. We conclude that conflicting results on familial clustering and seroprevalence curves might have logical explanations. However, the exact way this organism spreads among humans remains to be solved.

Antibodies, Bacterial↗

PubMed1991

More objective diagnoses of venous thromboembolism?

The clinical diagnosis of deep venous thrombosis is non-specific, i.e. suffers from a large number of false-positive diagnoses. Therefore, the use of objective tests is emphasized. We have investigated retrospectively the increase, if any, in the use of objective tests over a three year period in the Leiden area (1986-1989). We found that the percentage of patients on whom objective tests were used was more than doubled, from 21% to 55%; this increase was accompanied by a 29% decrease in the incidence of venous thromboembolic disease. These opposing trends are to be expected if more objective tests are used.

Anticoagulants↗

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↗

PubMed1989

Bleeding time, blood groups and von Willebrand factor.

The bleeding time in healthy volunteers was determined according to both the Ivy and the Simplate II techniques. A significantly longer bleeding time in people with blood group O than in people with non-O blood groups was demonstrated with both techniques. This difference could not be attributed to a difference in sex ratio, platelet count or haematocrit. The mean level of von Willebrand factor in blood group O is lower than in non-O blood groups, but we found no association between the level of von Willebrand factor and the bleeding time, despite the very broad range of von Willebrand factor levels in the subjects examined.

ABO Blood-Group System↗

PubMedDate not supplied

Venous thrombosis due to poor anticoagulant response to activated protein C: Leiden Thrombophilia Study.

We undertook a population-based case-control study to test the clinical importance of a hereditary abnormality in the coagulation system, characterised by poor anticoagulant response to activated protein C (APC), which is associated with familial thrombophilia. The abnormality was detected in 64 (21%) of 301 unselected consecutive patients younger than 70 years, with a first, objectively confirmed episode of deep-vein thrombosis and without underlying malignant disease. Among 301 healthy control subjects matched for age and sex, the frequency was 5% (14 subjects). Thus, there is a seven-fold increase in risk of deep-vein thrombosis in subjects with a poor response to APC (matched odds ratio 6.6 [95% CI 3.6-12.0]). In addition, there was a clear inverse relation between the degree of response to APC and thrombosis risk. In the families of the patients an autosomal dominant mode of transmission of the abnormality was confirmed. 9 of 10 thrombosis patients with a poor response to APC had 1 parent with a similar poor response, whereas 9 of 10 patients with normal tests had parents with equally normal tests. The abnormality was found in both parents of 1 patient with an extremely poor response to APC; this patient is probably homozygous for the abnormality. We conclude that the poor response to APC is the most important hereditary cause of venous thrombosis. Its high prevalence in a series of unselected patients will make testing of all thrombosis patients for this abnormality worth while.

Adolescent↗