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J Astermark

Publications and source records attributed to J Astermark.

At least 37 records · Page 2Linked to original sources
PubMed2001

Complexes between activated protein C and protein C inhibitor measured with a new method: comparison of performance with other markers of hypercoagulability in the diagnosis of deep vein thrombosis.

A first clinical evaluation has been made of the performance of a newly devised immunofluorometric assay for measuring plasma concentrations of activated protein C (APC) in complex with protein C inhibitor (PCI). The method was compared with testing for other markers of hypercoagulability in a case-control study comprising 123 patients with clinical suspicion of deep vein thrombosis (DVT). The diagnosis was confirmed by ascending phlebography, and the thrombotic burden estimated with a newly developed scoring system. Receiver operating characteristics (ROC) curves calculated to demonstrate the discriminatory capacity of the methods, showed the area under the curves (AUCs) to be similar for the APC-PCI and D-dimer methods. However, in contrast to the D-dimer method, the APC-PCI method measures a well-defined analyte, a prerequisite for reliable comparisons of future clinical studies. The APC-PCI method appears to be particularly useful as a marker for detection of recently developed proximal thrombi.

Activated Protein C Resistance↗
PubMed2000

Correlation between different intensities of anti-vitamin K treatment and coagulation parameters.

In order to study the effect of different intensities of anti-vitamin K treatment on coagulation parameters, 23 patients with venous thromboembolism were given, after the initial treatment period, warfarin at doses giving an International Normalised Ratio of 1.3-2.0 for 4 weeks, and of 1.1-1.3 for another 4 weeks. Blood samples were taken at the end of each of these periods and 4 weeks after the end of warfarin treatment. The vitamin K-dependent coagulation factors VII, IX, and X, as well as the inhibitor protein C and its cofactor protein S, all showed a highly significant correlation with treatment intensity. This was to some extent also true for the coagulation activation markers, prothrombin fragment 1+2 and thrombin-antithrombin complex. Ratios of pro- and anticoagulant factors in some instances showed a decrease at therapeutical (International Normalised Ratio) levels, and also sometimes with reduced warfarin treatment intensity. Taken together, our results encourage further research addressing issues of varying treatment intensity with warfarin and alternative methods for monitoring of anti-vitamin K treatment.

Adult↗
PubMed2000

The Malmö model for immune tolerance induction: impact of previous treatment on outcome.

Ten patients, who had been treated according to the Malmö model for immune tolerance induction (ITI), were analysed regarding treatment with clotting factors and chemotherapy during the time period between inhibitor detection and ITI. Of the patients who were successfully rendered tolerant (n=6) all but one had received treatment with FVIII, either alone (n=1), or combined with cyclophosphamide (n=4). Of the patients who did not become tolerant, three of four had received treatment with FVIII during the inhibitor period but only one with FVIII and chemotherapy. The total amount of treatment received was in general much lower in the group that did not become tolerant. In individual cases, it appeared very clear that the inhibitor level and anamnestic response was substantially reduced prior to the ITI using the Malmö treatment model. We conclude that treatment of acute bleeds during the inhibitor period may be of importance for ITI and that the different response rates published for different immune tolerance regimens most likely do not reflect the true response rate for the respective regimen.

Adult↗
PubMed2000

Immune tolerance induction and the treatment of hemophilia. Malmö protocol update.

The Malmö protocol for immune tolerance induction includes high doses of Factor VIII/IX, intravenous IgG and cyclophosphamide. If the inhibitor titer exceeds 10 Bethesda units at start, extracorporeal adsorption of IgG is performed using protein A. The protocol sometimes has to be repeated. A successful response may occur within a few weeks. In hemophilia A the success rate so far is 10/17 patients (15 high-responders, 2 low-responders) or 59%, whereas in hemophilia B 6/9 patients (8 high-responders, 1 low-responder), or 67%, have become tolerant. In one hemophilia B patient, a relapse occurred after 6 months. During a second treatment episode he developed an acute myocardial infarction, probably caused by replacement with prothrombin complex concentrate. We conclude that the Malmö protocol is efficient for induction of immune tolerance but the patients must be selected particularly with regard to inhibitor duration and time of last booster.

Adolescent↗
PubMed1999

Primary prophylaxis in severe haemophilia should be started at an early age but can be individualized.

The frequency of joint bleeds and orthopaedic joint scores were evaluated in 121 patients with severe haemophilia who had started prophylactic treatment with clotting factor concentrates at least once weekly before the age of 10. 75 of the patients started before the age of 3, 31 at the age of 3-5 and 15 at the age of 6-9. Each subgroup was evaluated separately. In addition, a regimen of one infusion weekly was compared with that of two (haemophilia B) or three (haemophilia A) infusions weekly in each patient. A significant decrease in the overall number of joint bleeds per year was found after shortening the infusion interval (P<0.005), but the individual bleeding pattern varied. In survival analysis of the first pathologic joint score event, those who started prophylaxis before the age of 3 had a better outcome overall than those starting at later ages (P=0.001). However, in subgroup analysis, no significant difference was seen in the annual number of joint bleeds and the development of arthropathy between those starting with, or shifting to, the more intensive regimen before the age of 3 and those that were put on this regimen at the age of 3-5. Age at start of prophylaxis was found to be an independent predictor for the development of arthropathy (P=0.0002), whereas dose and infusion interval at start were not. Our data emphasize the importance of starting replacement therapy during the first years of life. However, it seems that when beginning the regimen it can be individualized and adjusted according to the bleeding pattern. In this way, the need for a venous access system may be assessed on an individual basis.

Age Factors↗
PubMed1999

Malmö International Brother Study (MIBS): an international survey of brother pairs with haemophilia.

Malmö International Brother Study (MIBS) was initiated in 1996 in order to set up an international registry of twins and non-twin brothers with haemophilia and to search for genetic and compound factors predisposing for inhibitor development. As of July, 1997, 178 brother pairs are registered (143 haemophilia A and 35 haemophilia B patients). Sixteen of these pairs are twins. In 48 of the brother pairs (27%) there is a history of inhibitors, in 25 of them involving only one of the brothers. Immune tolerance induction has been attempted in 13 brother pairs (27%) and in four pairs the inhibitor has been eradicated. Additional demographic data need to be collected and, if possible plasma, IgG and DNA samples will be taken from inhibitor patients to serve as a tool for basic inhibitor experiments.

Antibodies↗
PubMed1999

The proportion of carboxylated to total or intact osteocalcin in serum discriminates warfarin-treated patients from control subjects.

We assessed the serum concentration of gamma-carboxylated osteocalcin (OC), total OC, and full-length OC in a clinical setting of 37 patients on continuous warfarin treatment (international normalized ratio 2.0-3.8). A comparison was done with the results from 30 untreated age-matched controls. Four monoclonal antibodies, previously generated and characterized as to their ability to recognize different human OC forms and fragments, were used in three two-site immunofluorometric assays. The warfarin-treated patients had significantly lower levels of carboxylated OC 4.9 +/- 3.8 (+/- 1 SD) ng/ml compared with the controls 13.1 +/- 9.7 (p < 0.0001). There was no difference in the levels of total OC or full-length OC between the two groups of patients. A strong correlation was found between the serum concentration of carboxylated OC and total OC, both for the warfarin-treated patients (r = 0.98) and for the controls (r = 0.99). There was a distinct cut-off level at 0.80, in the quotient carboxylated OC/total OC, at which all warfarin-treated patients fell below and all controls above this level. Hence, the concentration or ratio of serum gamma-carboxylated OC in clinical settings such as warfarin-treated patients could be measured using two-site immunoassays.

Aged↗
PubMed1998

Calcium binding to the first EGF-like module of human factor IX in a recombinant fragment containing residues 1-85. Mutations V46E and Q50E each manifest a negligible increase in calcium affinity.

The first EGF-like module of human coagulation factor IX contains a single functionally important calcium ion binding site. We have now shown the dissociation constant for this site to be approximately 160 microM in a recombinant protein fragment consisting of residues 1-85 in human fIX. This represents a approximately 10-fold increase in affinity as compared with the isolated EGF module (residues 46-85). The Gla module (here with Glu instead of Gla) thus increases the affinity of the EGF module calcium ion binding site. Each of two mutations, V46E and Q50E, made to investigate whether the extra negative charge would increase the affinity of the calcium binding site manifested a negligible increase in affinity.

Amino Acid Sequence↗
PubMed1998

[Hemophiliacs with HIV. Slower progression of the infection among younger patients and at higher dosages of factor concentrates].

HIV disease progression and the effect of replacement therapy with clotting factor concentrates (CFCs) were studied in 100 Swedish haemophiliacs, mean age at seroconversion 29 years (range, 4-72). On average 16 years after seroconversion, 67 per cent of the patients had CD4+ cell counts of < 200 x 10(6)/l, 50 per cent had developed AIDS, and 58 per cent had died. HIV disease progression was significantly slower in those aged less than 28 (median age) at seroconversion (P = 0.004). Moreover, mortality was inversely correlated to total annual CFC consumption after adjustment for age and HIV-related therapy, i.e., Pneumocystis carinii prophylaxis and antiretroviral drugs (P = 0.014), but unrelated to the purity of the CFCs used. After adjustment for age, annual CFC consumption and HIV-therapy, prophylactic replacement therapy was not associated with significantly better survival than on-demand treatment. It is concluded that in HIV-positive haemophiliacs replacement therapy may have a beneficial effect on the immune system, and that CFC purity and the regimen (prophylaxis vs on-demand) would seem to be factors of minor importance.

AIDS-Related Opportunistic Infections↗
PubMed1998

Major surgery seems not to influence HIV disease progression in haemophilia patients.

The influence of major surgery on HIV disease progression and decline in CD4+ cell count was evaluated in 23 seropositive haemophilia patients. 24 HIV-infected patients served as non-operated controls. In addition, 32 age-matched seronegative subjects were included. The follow-up time was up to 5 years. During the course of the study, eight of the operated (35%) and 11 of the non-operated (48%) subjects developed HIV-related symptoms (P=0.267). The relative risk for developing HIV-related symptoms after surgery was 0.60 (95% CI 0.25; 1.48). A significant decline in CD4+ cell counts was observed in both the surgery (4.0 x 10(6)/l/month, 95% CI 2.0; 6.0 x 10(6), P=0.001) and the non-surgery (4.0 x 10(6)/l/month, 95% CI 2.0; 6.0 x 10(6), P=0.004) seropositive subgroup, but no difference between the two subgroups was seen (P=0.793). HIV (6.0 x 10(6)/l/month, 95% CI 2.1; 9.9 x 10(6), P=0.0005) but not surgery (-1.0 x 10(6)/l/ month, 95% CI -3.0; 0.96 x 10(6), P=0.647) was an independent predictor for the decline in CD34+ cell count. No interaction effect was observed between HIV infection and surgery (P=0.361). The annual amount of factor concentrate used for regular replacement therapy did not influence the decline in CD4+ cell count (P=0.492). We conclude that major surgery may be considered in symptom-free HIV-seropositive haemophilia patients, with CD4+ cell counts > or = 0.20 x 10(9)/l under similar premises as for seronegative subjects.

Adolescent↗
PubMed1998

The Malmö-Klaipeda WFH twinning programme: a comparative description of the haemophilia cohorts.

In 1994, the Malmö-Klaipeda twinning programme was approved by the World Federation of Hemophilia. One of the first steps in the collaboration has been to set up a registry of the haemophilia patients in the Klaipeda area. In order to collect important clinical data the patients have been examined jointly by experts on haemophilia from the two centres. Seventeen out of 25 patients with severe haemophilia known at the Klaipeda centre were examined and compared to a matched cohort of patients from the Malmö centre. The main differences between the cohorts were that home treatment was not available to the Klaipeda patients, they received less treatment in general, had higher joint scores and more frequent bleeds. The pattern of transmission of blood-borne virus was very similar, with a high prevalence of hepatitis C antibodies. We conclude that the twinning programme between Malmö and Klaipeda has resulted in several achievements, including training of staff and a necessary inventory of the patients. This should not only form a suitable platform for the future development of haemophilia care in Lithuania, but could also serve as an example for liaisons between other haemophilia centres.

Adolescent↗
PubMed1998

Low recurrence rate after deep calf-vein thrombosis with 6 weeks of oral anticoagulation.

OBJECTIVES: To evaluate the recurrence rate after deep calf-vein thrombosis treated with 6 weeks of oral anticoagulation. DESIGN AND SUBJECTS: A 2 year follow-up of 126 consecutive patients admitted to the Department of Internal Medicine with venographically verified deep calf-vein thrombosis. RESULTS: One hundred and twenty-six patients were treated with warfarin for 6 weeks, 18 of them having had a previous episode of venous thrombosis (DVT). Eleven patients (8.7%) suffered a recurrent thromboembolic episode within 2 years, four of which were within the first 3 months. Eight of those without a history of DVT had a recurrence (7.4%). Three of these were activated protein C (APC)-resistant, one was protein C-deficient and one had malignant melanoma. Eight patients (6.3%) reported minor haemorrhagic complications, but no major bleeding was seen. CONCLUSION: Our data support the use of a 6 week regimen of secondary oral prophylaxis after a first episode of deep calf-vein thrombosis in patients without a permanent risk factor. Whether individuals with inherited thrombophilia require prolonged treatment remains to be evaluated.

Administration, Oral↗
PubMed1997

No effect of a new second-generation B-domain-deleted recombinant product on lymphocyte transformation in vitro: a study of plasma-derived and recombinant products.

Immunomodulatory effects of various factor VIII and factor IX clotting factor concentrates (CFCs) and of albumin were evaluated by a sensitive assay measuring the incorporation of 3H-thymidine in phytohaemagglutinin-stimulated lymphocytes in the presence of monodansylthiacadaverine. In contrast to previous findings by others, we found lymphocyte transformation to be inhibited by all plasma-derived factor VIII concentrates at concentrations of 0.02, 0.2 and 2.0 IU/ml, including those purified by monoclonal antibodies (P < 0.05). Kryobulin TIM3 had the most pronounced effect. In addition, three plasma-derived human albumin preparations exerted a similar inhibitory effect as the factor VIII concentrates, whereas the corresponding plasma-derived factor IX concentrates only manifested minor immunomodulatory effects. Of the recombinant preparations, only Recombinate exerted an inhibitory effect at 0.02 and 0.2 IU/ml, whereas both Kogenate and Recombinate decreased 3H-thymidine incorporation at 2.0 IU/ml (P = 0.01). No immunomodulatory effect at all was observed with r-VIII SQ, a new B-domain-deleted recombinant factor VIII preparation free from added albumin. The significance of this finding regarding immunological side-effects including inhibitor development remains to be evaluated, but this second-generation recombinant product opens up new and interesting perspectives yet to be explored.

Cadaverine↗
PubMed1994

Baculovirus-mediated expression of the epidermal growth factor-like modules of human factor IX fused to the factor XIIIa transamidation site in fibronectin. Evidence for a direct interaction between the NH2-terminal epidermal growth factor-like module of factor IXa beta and factor X.

Factor IX is a vitamin K-dependent procoagulant zymogen of a serine protease. In the presence of Ca2+ the active form of factor IX (factor IXa beta) forms a complex with factor VIIIa on suitable phospholipid surfaces such as aggregated platelets. This macromolecular complex rapidly activates factor X. We have previously provided data that suggest an interaction between the NH2-terminal epidermal growth factor (EGF)-like module of factor IXa beta and the substrate factor X. In an alternative approach to study this protein-protein interaction, we have expressed three recombinant baculovirus constructs encoding the EGF-like modules of human factor IX and a truncated form of fibronectin in a system based on the infection of insect cells (Spodoptera frugiperda 21). This strategy allows a simple one-step purification of the recombinant proteins on a gelatin-Sepharose column, followed by removal of the gelatin-binding part derived from fibronectin by proteolytic cleavage. The fusion proteins were isolated at yields of 20-50 micrograms/ml culture medium. The recombinant EGF-like modules contained 0.2-0.4 mol of erythro-beta-hydroxyaspartic acid/mol of protein, i.e. similar to the amount found in factor IX from human plasma, and appeared to be glycosylated at Ser-53. The NH2-terminal EGF-like module, which contained a transamidation acceptor site derived from fibronectin, was cross-linked by factor XIIIa in solution to intact and Gla-domainless factor X. There was no evidence of cross-linking to activated factor X or to factor X fragments containing only the gamma-carboxyglutamic acid module and the two EGF-like modules. The cross-linking results suggest a specific interaction between the NH2-terminal EGF-like module of factor IXa beta and the heavy chain of unactivated factor X. This interaction, albeit weak as judged by competition experiments, may be important for the targeting of factor X to the factor IXa beta-factor VIIIa complex on biological membranes and for the subsequent dissociation of factor Xa from the complex after activation.

Amino Acid Sequence↗
PubMed1994

The gamma-carboxyglutamic acid and epidermal growth factor-like modules of factor IXa beta. Effects on the serine protease module and factor X activation.

Blood coagulation factors IX and X are two serine proteases with a similar modular structure. The non-catalytic part of each protein consists of a gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. We have now found that the NH2-terminal EGF-like module of both factors IX and X inhibits factor Xa formation in a Gla-independent manner, both in the presence and absence of phospholipid and the cofactor, factor VIIIa. In contrast, the COOH-terminal EGF-like module has no such effect. Our data indicate that the NH2-terminal EGF-like module of factor IXa beta interacts either with the corresponding module or with the serine protease module in the substrate, factor X, without affecting the hydrolysis of low molecular weight substrates. Using antibodies as structural probes, we found that Ca2+ binding to the Gla module of factor IXa beta induces a conformational transition in the serine protease module. No evidence was found for a direct interaction between the Gla module and factor VIIIa. We therefore propose that the Gla module in factor IXa beta is indirectly involved in the cofactor interaction, in that Ca2+ binding to sites in this module induces a conformation in the serine protease module that is commensurate with factor VIIIa interaction. In addition, the immunochemical approach revealed a Gla-independent Ca2+ binding site in the serine protease module (apparent Kd of approximately 120 microM) that also might influence its conformation. Antibodies against the EGF-like modules of factor IX were used to probe Ca2+ binding to these modules in intact and in Gla-domainless factor IXa beta. The data indicate a Ca2+ binding site with an apparent Kd of approximately 50 microM in the NH2-terminal EGF-like module of both factor IX species.

1-Carboxyglutamic Acid↗
PubMed1992

Effects of gamma-carboxyglutamic acid and epidermal growth factor-like modules of factor IX on factor X activation. Studies using proteolytic fragments of bovine factor IX.

Factor IX is a vitamin K-dependent zymogen of a serine protease. The NH2-terminal half of the molecule consists of a Ca(2+)-binding gamma-carboxyglutamic acid (Gla)-containing module and two modules homologous to the epidermal growth factor (EGF) precursor. To elucidate the role of these non-catalytic modules of factor IXa beta in factor X activation, we have isolated and characterized fragments of bovine factor IX, containing one or both of the EGF-like modules as well as these modules linked to the Gla module. The fragments were used as inhibitors of factor IXa beta-mediated factor X activation in a plasma clotting system and in systems with purified components of the Xase complex. Fragments consisting of either the two EGF-like modules of factor IX linked together or the NH2-terminal EGF-like module alone were found to inhibit factor Xa generation both in the presence and absence of the cofactor, factor VIIIa. Moreover, a fragment consisting of the corresponding modules of factor X had a similar effect. We therefore propose that factor IXa beta and factor X interact directly through their EGF-like modules on or in the vicinity of a phospholipid surface. We have also found that the isolated Gla module of factor IX inhibits the formation of factor Xa both in the presence and absence of phospholipid but not in the absence of factor VIIIa. Our results are compatible with a model of the Xase complex, in which both the serine protease part and the Gla module of factor IXa beta interact with factor VIIIa.

1-Carboxyglutamic Acid↗