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Biomedical subjects

W Muntean

Publications and source records attributed to W Muntean.

At least 73 records · Page 4Linked to original sources
PubMed1993

Tissue plasminogen activator (alteplase) treatment for femoral artery thrombosis after cardiac catheterisation in infants and children.

OBJECTIVE: To determine the efficacy of fibrinolytic therapy with tissue plasminogen activator (alteplase) in infants and children with arterial thrombosis after cardiac catheterisation. DESIGN: Use of alteplase (Actilyse) in a protocol with prospective data collection. Alteplase was administered to infants and children with arterial thrombosis after cardiac catheterisation. A dose of 0.5 mg/kg/h was given continuously via a peripheral vein for the first hour followed by 0.25 mg/kg/h till clot lysis occurred or treatment had to be stopped because of bleeding complications. SETTING: University hospital, intensive care unit. PATIENTS: 17 consecutive infants and children with femoral artery thrombosis after cardiac catheterisation between 1 April 1988 and 31 October 1991. MAIN OUTCOME MEASURE: Reopening of the vessel. RESULTS: Complete clot lysis was achieved in 16 of 17 patients within 4-11 hours after the start of treatment. In one patient only partial lysis occurred. After complete lysis rethrombosis developed in one patient 15 hours after the end of treatment. Bleeding complications were seen in nine patients. These were restricted to the arterial puncture site, except for one who showed mild epistaxis. Three patients had to be treated with packed erythrocytes. CONCLUSIONS: Alteplase was an effective treatment of arterial thrombosis after cardiac catheterisation in infants and children. Further studies are needed to determine whether lower doses will reduce the frequently observed bleeding complications.

Cardiac Catheterization↗
PubMed1991

[Hepatitis C antibodies in children and adolescents with congenital blood coagulation disorders].

Antibodies to hepatitis C (anti-HCV) were determined in 24 children and adolescents with congenital disorders of haemostasis. 13 out of 24 patients (54%) were positive for anti-HCV. Comparison of the prevalence of positive anti-HCV and the quantity of non-virus inactivated factor VIII concentrates administered before 1985 showed positive anti-HCV in 100% of patients receiving more than 300 U factor VIII/kg b.w./month, in 88% of patients receiving 100 to 300 U factor VIII/kg b.w./month, and in 60% of patients receiving less than 100 U/kg b.w./month. 13 out of all 16 patients (81%) treated with non-virus-inactivated concentrates before 1985 were positive for anti-HCV. In contrast, all patients treated with virus inactivated concentrates were negative for anti-HCV. Elevated aminotransferases were frequently found in 8 out of 13 patients (62%) positive for anti-HCV, but only in 3 out of 11 patients (27%) negative for anti-HCV. The risk of developing chronic hepatitis was about 2.5-fold higher in patients positive for hepatitis C-antibodies than in patients negative for hepatitis C-antibodies.

Adolescent↗
PubMed1989

Factor VIII influences binding of factor IX and factor X to intact human platelets.

To investigate the influence of factor VIII on the binding of factors IX and X to the surface of intact human platelets, washed collagen-stimulated platelets were incubated with factor IX and factor X in the presence or absence of factor VIII. Platelets were then lysed and IX:Ag and X:Ag were determined in the platelet lysate. Platelet bound IX:Ag was higher after incubation of platelets with factor IX in the presence of native or activated factor VIII than after incubation of platelets with factor IX alone. Thrombin degraded factor VIII did not support binding of factor IX to stimulated platelets. Preactivation of factor IX enhanced binding to platelets; influence by factor VIII on binding to platelets was greater with native factor IX than with preactivated factor IX. Presence of native or activated factor VIII also increased binding of factor X to platelets. In contrast to factor IX, preactivation of factor X did not influence binding to platelets, but in the presence of factor VIII preactivation of factor X increased binding of factor X to platelets. Our data suggest that mediation of binding of factors IX and X to the surface of platelets is one of the mechanisms by that factor VIII exerts its cofactor function in the activation of factor X.

Blood Platelets↗
PubMed1988

Testing for human immunodeficiency virus (HIV-1) antigens in haemophiliacs positive for HIV antibody.

Sera collected from 28 haemophiliacs during the 2 years from 1985 to 1987 were examined for the presence of human immunodeficiency virus (HIV-1) antigen by two different methods using commercially available test kits. Of 28 patients, 18 had been positive for HIV antibody since at least 1985 and their HIV infection by blood products went back 3-6 years. Of these 18 antibody-positive patients, 8 were positive for HIV antigen according to one or both antigen tests on one or more occasions. The longest period of antigen expression was 21 months in two patients, one being in perfect health, the other showing AIDS-related complex (ARC) for the last 9 months. The detection of antigen expression was highly variable between the two tests used. Both positive and negative antigen-test results must therefore be used with great caution in clinical practice.

Adolescent↗
PubMed1988

Anticoagulation for continuous arteriovenous hemofiltration in children.

Continuous arteriovenous hemofiltration requires continuous anticoagulation to prevent early hemofilter clotting. We used heparin given continuously in the arterial line of the extracorporeal circuit as anticoagulant in children with initially normal coagulation status, and heparin and/or prostacyclin in high-risk bleeding patients with preexisting coagulopathy. Heparin infusion enabled a mean running time of 22.2 +/- 9.6 h, with the 0.1-m2 hemofilter and of 26.6 +/- 4.7 h with the 0.25-m2 hemofilter. The mean filter running time with combined heparin/prostacyclin infusion was 31 +/- 8.8 h. Prostacyclin as the sole antithrombotic agent provided good filter function only in 1 patient with preexisting coagulopathy. No adverse effects such as bleeding thrombosis, or hypotension were observed.

Anticoagulants↗
PubMed1988

Low total protein S antigen but high protein S activity due to decreased C4b-binding protein in neonates.

Protein S, a vitamin K-dependent cofactor for activated protein C, exists in normal adult plasma in a free anticoagulantly active form and in an inactive form complexed to C4b-binding protein. Immunologic and functional levels of protein S and C4b-binding protein in plasma were determined for 20 newborn infants and compared with adult normal pooled plasma. Total protein S antigen levels averaged 23%, similar to other vitamin K-dependent plasma proteins. However, the protein S anticoagulant activity was 74% of that of adult normal plasma. This apparent discrepancy of activity to antigen was shown to be due to low or undetectable levels of C4b-binding protein, which results in the presence of most if not all of protein S in its free and active form. The relatively high level of anticoagulantly active protein S in infants may enhance the potential of the protein C pathway, thereby minimizing risks of venous thrombosis in this group.

Antigens↗
PubMed1987

Factor VIII coagulant moiety binds to platelets by binding to phospholipids of the platelet membrane.

Washed human platelets were incubated with commercial factor VIII concentrate, or with purified factor VIII coagulant moiety. Platelets were then washed again and lysed by sonication. VIII:Ag and vWf:Ag were measured in the platelet lysate prior to and after incubation of the lysate with phospholipase C (PL-C). Platelet bound VIII:Ag was significantly higher after incubation of washed platelets with factor VIII concentrate than after incubation with buffer. Platelet bound VIII:Ag was further increased when platelets had been incubated with concentrate in the presence of thrombin and collagen. In contrast, only a slight increase in platelet bound vWf:Ag was observed after incubation of platelets with concentrate. When washed platelets had been incubated with factor VIII coagulant moiety, also significantly more platelet bound VIII:Ag was observed than after incubation with buffer. Measurable VIII:Ag, but not vWf:Ag, increased significantly after incubation of the platelet lysate with PL-C. When intact washed platelets had been treated with PL-C prior to the incubation with concentrate, binding of VIII:Ag to platelets was nearly completely abolished. Our data suggest that the factor VIII coagulant moiety binds to phospholipids of the platelet membrane and thereby contributes to the assembly of the factor X activating complex on the platelet surface.

Blood Platelets↗
PubMed1987

[HTLV-III antibodies and immunologic changes in hemophilic children. Prevalence of HTLV-III antibodies in hemophilic children and their relatives living in the same household].

19 (51%) of 37 hemophiliac children and adolescents regularly treated with factor VIII and IX concentrates were positive for HTLV III antibodies. The prevalence of HTLV III antibodies was higher in patients with severe hemophilia (64%) requiring frequent administration of concentrates than in patients with mild hemophilia (17%). No patient showed signs of AIDS or AIDS related complex. Immunologic alterations (inverse ratio of helper- and suppressor lymphocytes, elevated immunoglobulins, and elevated total serum proteins) were more often observed in patients requiring frequent administration of concentrates than in patients requiring relatively infrequent administration of concentrates. Since in patients frequently treated with concentrates the prevalence of HTLV III antibodies was also higher, it was not possible to draw any conclusions whether the observed immunologic alterations are due to the HTLV III infection alone or are also induced by the frequent administration of coagulation factor concentrates. No HTLV III positive person was detected in 45 relatives of 18 HTLV III positive hemophiliac children living together in 16 households and actively participating in the care of those children. In contrast, 6 (11%) of 55 relatives living in 21 households with 23 hepatitis-B-positive hemophiliac children were positive for hepatitis B. Our results support the general impression, that the risk to contract hepatitis B seems to be greater than to contract HTLV III from seropositive patients, and should help to facilitate the social integration of HTLV III positive hemophiliac children.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Suppression of factor VIII inhibitor in children with hemophilia A].

In 1977 Brackmann for the first time reported an induction of tolerance in hemophiliacs with inhibitors using a protocol requiring administration of very high daily doses of factor VIII and activated prothrombin complex concentrates. Since the costs of such a protocol are enormous, we report our experiences in 3 hemophiliac children with inhibitors against factor VIII treated with much lower doses of factor VIII concentrate only for induction of tolerance. Two "high responder" and one "low responder" initially for only a short period received factor VIII concentrate in doses comparable to the Brackmann protocol. After that period patients were treated with 25--30 units factor VIII concentrate/kg/day, doses that are comparable to conventional prophylactic treatment. In one high responder the inhibitor disappeared completely after 22 months, in the other high responder the inhibitor titer decreased from 133 BU to 4.4 BU. In the low responder also a significant decrease of the inhibitor titer was observed. At this time bleedings in all three patients can be controlled by conventional doses of factor VIII concentrate.

Adolescent↗