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Biomedical subjects

R M Bertina

Publications and source records attributed to R M Bertina.

At least 19 recordsLinked to original sources
PubMed2006

Microparticle-associated tissue factor activity: a link between cancer and thrombosis?

BACKGROUND: Cancer, in particular mucinous adenocarcinoma, is associated with venous thromboembolism (VTE). Tissue factor (TF), initiator of coagulation, plays a central role in the paradigm that clotting and tumor growth form a vicious circle, in which hypercoagulability facilitates the aggressive biology of cancer and vice versa. Expression of TF in tumors is associated with poor differentiation and poor prognosis. PATIENT/METHODS: We investigated the association between clinically manifest VTE and procoagulant properties of circulating microparticles (MP) isolated from blood of unselected pancreatic and breast adenocarcinoma patients' consecutive subjects, who presented with ultrasound or CT-scan confirmed VTE, and healthy subjects. RESULTS: Patients with disseminated breast and pancreatic cancer had significantly increased levels of MP-associated TF activity compared with healthy controls, subjects with idiopathic acute VTE and non-metastatic cancer patients. Patients with both high MP-associated TF-activity and MP-associated epithelial mucin (MUC1) had a lower survival rate at 3-9 months follow-up than those with low TF-activity and no MUC1 expression: the likelihood of survival was 0.42 (95% CI: 0.19- 0.94) for an individual with these two predictor variables present, after adjustment for other factors (age cohort, type of cancer, VTE) in the Cox proportional hazards model. CONCLUSIONS: Our results suggest an important role for MP-associated TF and MUC1 in the pathogenesis of thrombosis in disseminated mucinous adenocarcinoma patients. Future studies should reveal the mechanism underlying the observed associations.

Adenocarcinoma, Mucinous↗
PubMed2006

Matrix metalloproteinase-9 gene -1562C/T polymorphism mitigates preeclampsia.

Although the aetiology of preeclampsia is unknown, there is substantial evidence that it finds its roots in abnormal placentation. Prerequisites for successful placentation include trophoblast invasion, degradation and remodelling of the uterine decidual extracellular matrix, and apoptosis without thrombosis. We tested this hypothesis by analysing the effect of functional polymorphisms in the genes coding for MMP9, MMP3 and annexin A5 on the risk of preeclampsia using a case-control design. In 163 women with preeclampsia and 163 controls we studied the association with polymorphisms in the MMP9 (-1562 C/T), MMP3 (-1612 5A/6A) and annexin A5 (-1 C/T) genes using logistic regression analysis. A lower prevalence of the rare T allele of the MMP9 (-1562 C/T) polymorphism in women with preeclampsia was found (odds ratio 0.48, 95% confidence interval 0.25-0.90). The distribution of the MMP3 (-1612 5A/6A) and annexin A5 (-1 C/T) gene polymorphisms were similar in cases and controls. Our results suggest that the MMP9-1562T allele is associated with a reduced risk of preeclampsia and therefore may protect against maladaptation of the spiral arteries and decreased decidual degradation. The elevated MMP9 concentrations reported to be associated with the -1562T allele might be essential for the development of an adequate maternal-fetal interface early in pregnancy by facilitating trophoblast apoptosis and degradation.

Adult↗
PubMed2006

von Willebrand factor and its propeptide: the influence of secretion and clearance on protein levels and the risk of venous thrombosis.

BACKGROUND AND OBJECTIVES: Elevated levels of factor (F)VIII are associated with an increased risk of thrombosis. FVIII levels are determined mainly by von Willebrand factor (VWF). We have investigated the contribution of secretion and clearance rates to the elevated VWF antigen (VWF:Ag) and to the risk of thrombosis. VWF is secreted in equimolar amounts with its propeptide, which has a shorter half-life. VWF propeptide can be used as a measure of VWF secretion and allows estimation of the VWF half-life. METHODS AND RESULTS: We have measured VWF propeptide, VWF:Ag, FVIII:Ag and FVIII activity (FVIII:C) in the Leiden Thrombophilia Study. In controls, high VWF propeptide was associated with high VWF:Ag, FVIII:Ag and FVIII:C. In contrast to mature VWF:Ag, VWF propeptide was not influenced by blood groups. Using an ELISA-based assay we have shown that VWF propeptide lacks ABO antigens. Levels were higher in men and increased with age. A long VWF half-life was also associated with high VWF:Ag, FVIII:Ag and FVIII:C. The VWF half-life was influenced by blood group (10 h in O vs. 12 h in non-O individuals), but not by sex, and only slightly by age. VWF propeptide was higher in thrombosis patients than in controls. The VWF half-life was similar in patients and controls (11.4 and 11.1 h, respectively). CONCLUSIONS: Both secretion and clearance rates are important determinants of VWF and FVIII levels. However, mainly high VWF and FVIII levels caused by increased secretion seem to be associated with thrombosis. ABO blood group influences the clearance rates of VWF rather than VWF secretion rates.

ABO Blood-Group System↗
PubMed2006

Plasma fibrinogen gamma' chain content in the thrombotic microangiopathy syndrome.

BACKGROUND: Human fibrinogen gamma chain variants, termed gamma' chains, contain a unique 20-residue sequence after gamma chain residue 407 that ends at gamma'427, and is designated gamma'(427L). Full-length (FL) gamma'(427L) chains are constituents of a fibrin-dependent thrombin inhibitory system known as antithrombin I, whereas a gamma' chain processed in vivo, termed gamma'(423P), lacks the C-terminal tetrapeptide EDDL, and does not bind thrombin. Together, the gamma'(423P) and gamma'(427L) chains comprise the total plasma fibrinogen gamma' chain content. OBJECTIVES: Lowered plasma gamma' chain content (i.e. gamma' chain-containing fibrinogen/total fibrinogen ratio) has been shown to correlate with susceptibility to venous thrombosis, thus prompting this study on the total and FL gamma' chain content in 45 subjects with thrombotic microangiopathy (TMA), a disorder characterized by microvascular thrombosis. METHODS: We measured by enzyme-linked immunosorbent assay the total gamma' chain-containing fibrinogen/total fibrinogen (Total gamma'-fgn/Total fgn) ratio and the FL gamma' chain-containing fibrinogen/total fibrinogen (FL gamma'-fgn/Total fgn) ratio in these plasmas and in healthy subjects (n = 87). RESULTS: In healthy subjects, the mean Total gamma'-fgn/Total fgn ratio was 0.127, whereas the FL gamma'-fgn/Total fgn ratio was somewhat lower at 0.099 (P < 0.0001), a difference reflecting the presence of gamma'(423P) chains. In TMA plasmas, both the Total gamma'-fgn and FL gamma'-fgn/Total fgn ratios (0.099 and 0.084, respectively) were lower than those of their healthy subject counterparts (P < 0.0001). CONCLUSIONS: These findings in TMA suggest that reductions in the gamma' chain content indicate reduced antithrombin I activity that may contribute to microvascular thrombosis in TMA.

ADAM Proteins↗
PubMed2006

Homozygous C2362F von Willebrand factor induces intracellular retention of mutant von Willebrand factor resulting in autosomal recessive severe von Willebrand disease.

The missense mutation of cysteine 2362 to a phenylalanine in von Willebrand factor (VWF) has been detected in several Italian families with autosomal recessive, severe von Willebrand disease. We investigated how this amino acid change in VWF may lead to a predominantly quantitative defect. This mutation was studied in vitro by transient expression of the full-length mutant VWF-C2362F protein and in vivo by analysis of plasma VWF after infusion of 1-deamino-8-d-arginine vasopressin (DDAVP) in a patient homozygous for this mutation. Single transfections of pSVHVWF-C2362F and co-transfections of mutant and wild-type constructs resulted in 8% and 50% VWF antigen, respectively, in conditioned medium. These reduced levels are in accordance with observations in homozygous and heterozygous carriers of the mutation. In addition, VWF-C2362F was retained intracellularly. Similar results were obtained for C2362F and C2362A. After infusion of DDAVP in a homozygous patient, a twofold decrease in half-life of plasma VWF-C2362F was observed. This was not explained by increased susceptibility of recombinant VWF-C2362F to ADAMTS13. It was concluded that VWF-C2362F causes reduced VWF plasma levels due to impaired secretion and intracellular retention. Furthermore, it is the loss of cysteine 2362 rather than the introduction of the bulky amino acid side chain that causes these effects.

ADAM Proteins↗
PubMed2005

A new functional assay of thrombin activatable fibrinolysis inhibitor.

New thrombin activatable fibrinolysis inhibitor (TAFI) assays are necessary for studying the role of this fibrinolysis inhibitor in cardiovascular disease. The identification of a functional single nucleotide polymorphism (SNP) (1040C/T) leading to a TAFI-variant with increased stability but lower antigen levels has made the determination of functional activity even more essential. Therefore, we developed a new assay for the functional activity of TAFI in citrated plasma samples. This assay is based on the retardation of plasma clot lysis by TAFIa. TAFI activation was induced simultaneously with fibrin formation and lysis was mediated by rt-PA. The variability of other plasma components was minimized by a 20-fold dilution of the samples in TAFI-depleted plasma. Lysis times (-/+ potato carboxypeptidase inhibitor) and the TAFI-related retardation of clot lysis, the functional parameter of the assay, were determined in a group of 92 healthy volunteers, as well as TAFI antigen levels (electroimmunoassay) and two TAFI SNPs (-438A/G and 1040C/T). TAFI-related retardation was 19.8 +/- 5.6 min (mean +/- SD) and was correlated with the antigen level. The specific antifibrinolytic activity of TAFI was associated with the -438A/G and 1040C/T genotypes. Individuals with the 325Ile-variant had on average a 34% higher TAFI-specific antifibrinolytic activity than individuals with the 325Thr-isoform. The TAFI-related retardation in the two groups of individuals did not differ, as a lower level compensated for the higher specific antifibrinolytic activity of the 325Ile-isoform. This assay provides valuable information about the performance of different TAFI isoforms and constitutes a new method for studying the role of TAFI in cardiovascular disease.

Adult↗
PubMed2005

Determinants of the APTT- and ETP-based APC sensitivity tests.

BACKGROUND: A reduced sensitivity for activated protein C (APC) is associated with an increased risk of venous thrombosis even in the absence of the factor (F)V Leiden mutation. This risk has been demonstrated with two APC sensitivity tests, which quantify the effects of APC on the activated partial thromboplastin time (APTT) and the endogenous thrombin potential (ETP), respectively. OBJECTIVES: We examined determinants of both APC sensitivity tests in the control group of the Leiden Thrombophilia Study (LETS). METHODS: Multiple linear regression analysis was performed with normalized APC-SR(APTT) or APC-SR(ETP) as dependent variable and putative determinants [levels of FII, FV, FVII, FVIII, FIX, FX, FXI, FXII, FXIII A subunit, FXIII B subunit, protein S total, protein S free, protein C, tissue factor pathway inhibitor (TFPI) total, TFPI free, antithrombin and fibrinogen] as independent variables. RESULTS AND CONCLUSIONS: The major determinant of the APTT-based test was FVIII level, followed by FII level. The ETP-based test was influenced most by free protein S and free TFPI levels. In both tests FXa formation plays a major role, as the effect of FVIII and TFPI on the tests seems to be executed via FXa. The ETP-based test was also strongly influenced by oral contraceptive use, even when we adjusted for all the clotting factors listed above. This means that the effect of oral contraceptives on the ETP-based test is not fully explained by the changes of coagulation factor levels investigated in this study, and that the molecular basis of acquired APC resistance during use of oral contraceptives remains to be established.

Adolescent↗
PubMed2005

Cysteine-mutations in von Willebrand factor associated with increased clearance.

BACKGROUND: von Willebrand disease (VWD) is a bleeding disorder caused by the decrease of functional von Willebrand factor (VWF). Low levels of VWF can result from decreased synthesis, impaired secretion, increased clearance or combinations thereof. Several mutations lead to impaired synthesis or secretion of VWF, however, little is known about the survival of VWF in the circulation. OBJECTIVES: To evaluate the effect of several VWF mutations on VWF clearance. PATIENTS/METHODS: The effect of three cysteine-mutations (C1130F, C1149R or C2671Y) on the in vivo survival of VWF was studied in patients carrying these mutations and in a VWF-deficient mice model. RESULTS: In patients carrying these mutations, we observed increased propeptide/mature VWF ratios and rapid disappearance of VWF from the circulation after desmopressin treatment. Detailed analysis of in vivo clearance of recombinant VWF in a VWF-deficient mice model revealed a fourfold increased clearance rate of the mutants. The mutations C1130F, C1149R and C2671Y are each associated with reduced survival of VWF in the circulation. Detailed analysis of the recombinant mutant VWF demonstrated that increased clearance was not due to increased proteolysis by ADAMTS-13. We did not identify functional or structural characteristics that the mutant proteins have in common and could be associated with the phenomenon of increased clearance. CONCLUSIONS: Cysteine-mutations in VWF may result in reduced in vivo survival. The observation that various mutations are associated with increased in vivo clearance may have major implications for the therapeutic strategies that rely on the rise of endogenous VWF after desmopressin administration.

ADAMTS13 Protein↗
PubMed2004

Interleukin 10-2849AA genotype protects against pre-eclampsia.

Recently, it has been described that human fertility is associated with the interleukin 10 (IL10) -2849 AA genotype. Pre-eclampsia is the most common pregnancy-specific complication. In the pathogenesis of pre-eclampsia, IL10 may affect maternal intravascular inflammation as well as endothelial dysfunction. Therefore, we tested the hypothesis that pre-eclampsia is associated with genetic variation in the IL10 promoter region in a case-control study for pre-eclampsia. Women homozygous for the IL10 -2849A allele have a threefold reduced risk for pre-eclampsia compared to controls (odds ratio 0.29; 95% CI 0.10-0.83). No differences in genotype frequency were found for polymorphisms in the IL10 promoter region at positions -1082, -819 and -592. This suggests that there is a genetically determined mechanism which protects the mother against pre-eclampsia, as reflected in the lower frequency of the IL10 -2849AA genotype in pre-eclamptic women.

Case-Control Studies↗
PubMed2004

Characterization of an immunologic polymorphism (D79H) in the heavy chain of factor V.

BACKGROUND: During the study of a family with hereditary factor (F)V deficiency (FV Amersfoort, 1102 A > T in exon 7) we identified an individual with 5% FV heavy chain antigen (FV(HC)) and 50% FV light chain antigen (FV(LC)). Further testing revealed that apart from the FV Amersfoort allele a second variant FV allele was segregating in this family, which encodes for a FV molecule with a reduced affinity for mAb V-23 used in the FV heavy chain ELISA (ELISA(HC)). OBJECTIVE: Identification and characterization of the molecular basis responsible for the reduced affinity of the variant FV for mAb V-23. METHODS: Family members of the proband were screened for mutations in the exons coding for the heavy chain of FV, after which the recombinant variant FV could be generated and characterized. Next, the cases and controls of the Leiden Thrombophilia Study (LETS) were genotyped for carriership of the variant FV. RESULTS: In the variant FV allele a polymorphism in exon 3 (409G > C) was identified, which predicts the replacement of aspartic acid 79 by histidin (D79H). Introduction of this mutation in recombinant FV confirmed that it reduces the affinity for binding to mAb V-23. The substitution has no effect on FV(a) stability and Xa-cofactor activity. In Caucasians the frequency of the FV-79H allele is approximately 5%. Analysis of the LETS revealed that the FV-79H allele is not associated with FV levels (FV(LC)), activated protein C sensitivity (using an activated partial thromboplastin time-based test) or risk of venous thrombosis (OR 1.07, CI 95: 0.7-1.7). CONCLUSION: The D79H substitution in FV should be considered as a neutral polymorphism. The monoclonal antibody V-23, which has a strongly reduced affinity for FV-79H, is not suitable for application in diagnostic tests.

Activated Protein C Resistance↗
PubMed2004

Haplotypes of the EPCR gene, plasma sEPCR levels and the risk of deep venous thrombosis.

BACKGROUND: Binding of protein C (PC) to the endothelial cell PC receptor (EPCR) stimulates PC activation by increasing the affinity of PC for the thrombin-thrombomodulin complex. A soluble form of this receptor (sEPCR) circulates in plasma and inhibits both PC activation and APC anticoagulant activity. OBJECTIVES: The aim of this study was to investigate whether variations in the EPCR gene or plasma sEPCR levels are risk factors for deep venous thrombosis (DVT). PATIENTS/METHODS: In a large case-control study, the Leiden Thrombophilia Study (LETS), sEPCR levels were measured by ELISA. All subjects were genotyped for three haplotype-tagging SNPs, enabling us to detect all four common haplotypes of the EPCR gene. RESULTS: The distribution of sEPCR levels in the control population was trimodal and was genetically controlled by haplotype 3 (H3). This haplotype explained 86.5% of the variation in sEPCR levels. Carriers of two H3 alleles had higher sEPCR levels (439 ng mL(-1)) than carriers of one H3 allele (258 ng mL(-1)), which had higher levels than non-H3 carriers (94 ng mL(-1)). Haplotype 4 was associated with a slightly increased risk (OR = 1.4, 95%CI:1.0-2.2). The risk of subjects with sEPCR levels in the top quartile (>/= 137 ng mL(-1)) was increased compared to that of subjects in the first quartile (< 81 ng mL(-1)), but since there was no dose-response effect, it is most likely that low sEPCR levels reduce the risk of DVT. CONCLUSIONS: Our data do not suggest a strong association between EPCR haplotypes and thrombosis risk, but low sEPCR levels appear to reduce the risk of DVT.

Adolescent↗