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Biomedical subjects

G Pfliegler

Publications and source records attributed to G Pfliegler.

At least 19 recordsLinked to original sources
PubMed2003

Anti-factor V auto-antibody in the plasma and platelets of a patient with repeated gastrointestinal bleeding.

Development of autoantibody against coagulation factor V (FV) is a rare clinical condition with hemorrhagic complications of varying severity. The aim of this study was to establish the pathomechanism of an acquired FV deficiency and characterize the FV inhibitor responsible for the clinical symptoms. A 78-year-old female was admitted to hospital with severe gastrointestinal bleeding. General clotting tests and determination of clotting factors were performed by standard methods. FV antigen and FV containing immune complexes were measured by ELISA. The FV molecule was investigated by Western blotting and by sequencing the f5 gene. The binding of patient's IgG to FV and activated FV (FVa) was demonstrated in an ELISA system and its effect on the procoagulant activity of FVa was tested in clotting tests and in a chromogenic prothrombinase assay. Localization of the epitope for the antibody was performed by blocking ELISA. FV activity was severely suppressed both in plasma and platelets. FV antigen levels were normal by ELISA using polyclonal anti-FV antibody or monoclonal antibody against the connecting region of FV, but depressed when HV1 monoclonal antibody against the C2 domain in the FV light-chain was used as capture antibody. The FV molecule was found intact. An IgG reacting with both FV and FVa was present in the patient's plasma and its binding to FV was inhibited by HV1 antibody. FV-containing immune complexes were detected in the patient's plasma and platelet lysate. The patient's IgG inhibited the procoagulant function of FVa. An anti-FV IgG was present in the patient's plasma and platelets. The autoantibody reacted with an epitope in the C2 domain of FV light chain and neutralized the procoagulant function of FVa.

Aged↗
PubMed2001

The subendothelium of the HMEC-1 cell line supports thrombus formation in the absence of von Willebrand factor and collagen types I, III and VI.

The macromolecular composition of the extracellular matrix (ECM) produced by the human microvascular endothelial cell line (HMEC-1) was determined by ELISA and its thrombogenicity was studied in blood perfusion assays. Results were compared with those obtained with the ECM produced by human umbilical vein endothelial cells (HUVEC). The HMEC-1's ECM contains collagen type IV, fibronectin, laminin and thrombospondin, but no detectable levels of collagen types I, III and VI, or von Willebrand factor (vWF), whereas all these components were found in the ECM synthesized by HUVEC. HMEC-1's ECM was perfused with low-molecular-weight heparin-anticoagulated blood at two wall shear rates (650/s and 2,600/s), representative of moderate and high arterial wall shear rates, in parallel plate flow chambers for 5 min. This resulted in the formation of large platelet aggregates, compared to essentially a monolayer of adherent platelets on HUVEC's ECM. Interestingly, large thrombi were formed at 2,600/s when HMEC-1's ECM was perfused with the blood of a patient with severe type III von Willebrand disease lacking both plasma and platelet vWF, indicating that vWF was not absolutely required for thrombus formation on this matrix. Thrombin generated on the HMEC-1's ECM contributed importantly to the large platelet thrombi formed, shown by performing blood perfusion experiments in the presence of thrombin inhibitors. Our results indicate that 1) platelet adhesion and aggregate formation on a subendothelium may occur at a high shear rate (2600/s) without the participation of collagen types I, III and VI, and vWF; and 2) the HMEC-1 cell line may prove useful for in vitro studies of the thrombogenic properties of microvascular subendothelium which in most cases does not contain fibrillar collagens and vWF.

Cell Line↗
PubMed2000

Val34Leu polymorphism of plasma factor XIII: biochemistry and epidemiology in familial thrombophilia.

Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) is located in the activation peptide (AP) just 3 amino acids away from the thrombin cleavage site. This mutation has been associated with a protective effect against occlusive arterial diseases and venous thrombosis; however, its biochemical consequences have not been explored. In the current study it was demonstrated that the intracellular stability and the plasma concentration of FXIII of different Val34Leu genotypes are identical, which suggests that there is no difference in the rate of synthesis and externalization of wild-type and mutant FXIII-A. In contrast, the release of AP by thrombin from the Leu34 allele proceeded significantly faster than from its wild-type Val34 counterpart. By molecular modeling larger interaction energy was calculated between the Leu34 variant and the respective domains of thrombin than between the Val34 variant and thrombin. In agreement with these findings, the activation of mutant plasma FXIII by thrombin was faster and required less thrombin than that of the wild-type variant. Full thrombin activation of purified plasma FXIII of different genotypes, however, resulted in identical specific transglutaminase activities. Similarly, the mean specific FXIII activity in the plasma was the same in the groups with wild-type, heterozygous, and homozygous variants. Faster activation of the Leu34 allele hardly could be associated with its presumed protective effect against venous thrombosis. No such protective effect was observed in a large group of patients with familial thrombophilia.

Adult↗
PubMed1998

[Thrombophilia, anticoagulant therapy and pregnancy].

Thromboembolic complications during pregnancy are the most common causes of maternal death. Here we report on thromboembolic prophylaxis of 60 pregnancies of 32 pregnant women with familial thrombophilia. Long-term Fraxiparine (Sanofi-Chinoin) as thromboprophylaxis was applied in 26 cases throughout pregnancy. UFH (Heparin-Ca inj.) was used in 11 cases, and there were 23 pregnancies without thromboembolic prophylaxis in our patient's case histories. Artificial abortions were not included in this paper. The ratio of successful pregnancies were: with Fraxiparine: 24/26 (92.3%), with UFH (Heparin-Ca): 8/11 (72.7%), without prophylaxis: 4/23 (17.4%). In the patient group treated with Fraxiparine there were no foetopathy, thrombocytopenia or bleeding complication. LMWH is recommended for pregnant women with familial thrombophilia. According to literature data and our own experiences the doses of LMWH in patients with familial thrombophilia, and -antiphospholipid syndrome, and -artificial heart value are suggested.

Adult↗
PubMed1998

[Empty follicle syndrome as cause of unsuccessful in vitro fertilization].

The authors report a case, where ultrasound guided transvaginal follicle aspiration was carried out for oocyte retrieval during the source of in vitro fertilization. Despite the favourable situation described by ultrasound and prognosed by serum hormone levels aspiration of oocytes proved unsuccessful even after lavage of follicules. The authors give an overview of the literature of "empty" follicle syndrome, its possible aetiology and methods of treatment.

Female↗
PubMed1997

[Coumarin combined with low-dose acetylsalicylic acid in the prevention of thromboembolic complications in patients with mitral and aortic valve prostheses].

Authors studied the effect of coumarin, and its combination with low-dose (125 mg/day) acetylsalicylic acid in the prevention of thromboembolic complication during a 10-year period (average 4.7 years) in a randomized trial of 296 patients aged 18-60 year with tilting disc type prosthetic heart valve (159 mitral and 137 aortic) in sinus rhythm. In the group treated with coumarin (152 patients, 743.4 patient-years) 4 cases (2 of them fatal) of valve thrombosis, 12 cases of peripheral embolism and 9 cases (3 intracranial, 3 among them fatal) of major bleeding were observed; in the group treated with coumarin plus acetylsalicylic acid (144 patients, 638.7 patient-years) 2 cases (1 of them fatal) of valve thrombosis, 4 cases of peripheral embolism and 14 cases (3 of them fatal) of major bleeding were observed. In the case of valve thromboses the difference between the two groups was non-significant but still clinically remarkable; peripheral embolism occurred in significantly higher number (p < 0.05). There was no statistically significant difference of bleeding complications between the two groups. The results suggest that the combination of coumarin plus low-dose acetylsalicylic acid is more effective in the prevention of thromboembolic complications in patients with mitral and aortic prosthetic heart valve than coumarin alone; the danger of bleeding complications seems to be acceptable with adequate control.

Adolescent↗
PubMed1996

[Low-molecular-weight heparin in the prevention of thromboembolism in pregnant thrombophilic patients].

Prophylaxis of thromboembolism with low molecular weight heparin (LMWH) may offer some advantages over unfractionated heparin during pregnancy. Controlled studies with LMWH for thromboprophylaxis in pregnancy are failing, although according to some recent studies LMWH did not cross the placental barrier. LMWH as thromboprophylactic agent was used in three young pregnant women with familial thrombophilia (two with PC one with AT-III deficiency). According to the bodyweight of patients the applied doses of LMWH were 5,000-10,000 ICU once daily. Laboratory control (determination of anti-FXa activity in plasma samples) was made monthly. The three pregnancies were uneventful, thromboembolic or haemorrhagic complications did not develop. Newborns were healthy, with no coincide of disturbances of haemostasis. The LMWH-demand is certainly increased at the late period of pregnancy. LMWH as thromboprophylaxis is recommended for pregnants with familial thrombophilia. The necessary dose of Fraxiparine may be 70 ICU/kg/day in the first and 100 ICU/kg/day in the second half of pregnancy.

Adult↗
PubMed1995

Targeting platelets containing electro-encapsulated iloprost to balloon injured aorta in rats.

Drugs can be electro-encapsulated within platelets and targeted to damaged blood vessels by exploiting the platelet's natural haemostatic properties to adhere to collagen and other vessel wall constituents revealed by injury. A rat aorta balloon angioplasty model has been used to study the effect on platelet deposition of giving iloprost loaded platelets i.v. during the balloon injury. After labelling the circulating platelets with 111-Indium before balloon injury, time course studies showed maximum platelet deposition on the injured aorta occurred at about 1 h post-injury and the deposition remained stable over the next 2-3 h. When iloprost-loaded platelets were given i.v. during injury and the circulating platelet pool labelled with 111-Indium 30 min later, platelet deposition, measured at 2 h postinjury, was substantially and significantly reduced compared with control platelet treatment. Some anti-proliferative effects of iloprost-loaded platelets given i.v. during injury have also been observed. Whereas the incorporation of [3H]-thymidine into aorta intima-media DNA at 3 days post injury was 62-fold higher in balloon injured rats than in control sham operated rats, thymidine incorporation into intima/media of rats which had received iloprost loaded platelets during injury was reduced as compared with rats subjected only to the injury procedure. The reduction was only of near significance, however, but at 14 days after injury the total DNA content of the aorta intima/media of rats given iloprost loaded platelets during injury was significantly reduced. Although iloprost loaded platelets can clearly inhibit excessive platelet deposition, other encapsulated agents may have greater anti-proliferative effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1994

Inhibition of platelet recruitment to arterial lesions by predeposition of platelets containing encapsulated iloprost.

Drugs can be encapsulated within blood platelets by reversible electroporation and can be haemostatically targeted to vessel wall injury sites. Initial studies with iloprost-loaded pig platelets and pig aorta tunica media in perfusion circuits are presented. After autologous reconstitution into blood, no significant difference was observed in the deposition of 111Indium labelled sham-loaded and untreated platelets onto the tunica media during perfusion under low and high shear conditions. In paired experiments (n = 10 pairs), the deposition of iloprost-loaded platelets was significantly lower (mean 61%) after 5 min perfusion than the deposition from blood containing sham-loaded (control) platelets. A similar significant reduction (mean 54%) was seen after 10 min perfusion. Pre-perfusion of iloprost-loaded platelets for 10 min under low shear conditions (212/s), followed by 5 min perfusion of 111Indium labelled normal platelets, significantly reduced the secondary platelet deposition (p < 0.01) when compared with the deposition seen when control untreated platelets were preperfused. Significant differences (p < 0.001) in secondary deposition were also observed when primary and secondary platelet perfusions were made under high shear (1690/s). Histology of the tunica media segments post perfusion, supported the inhibitory effect of predeposited iloprost-loaded platelets on secondary platelet recruitment. By exploiting their natural haemostatic propensity, drug-loaded platelets can be targeted to vessel wall injury sites. Appropriate drugs could be packaged that may passivate the carrier platelets at the lesion inhibiting thrombus formation or they may act as a depot for sustained drug release.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Endothelium releases more von Willebrand factor and tissue-type plasminogen activator upon venous occlusion in patients with liver cirrhosis than in normals.

Venous occlusion was used in 8 patients with liver cirrhosis and in 10 normals to investigate the pathomechanism of long-term elevation of plasma von Willebrand factor antigen (vWFAg) in liver cirrhosis. The following parameters were determined at baseline, and immediately, 60 min and 24 h after 10 min venous occlusion: vWFAg, ristocetin cofactor (RiCoF), in vitro platelet retention (Adeplat T), and tissue-type plasminogen activator (t-PA). Every baseline value in the liver cirrhosis group was significantly higher than in the controls. In both groups the 10-min values were significantly higher than their corresponding baseline results. Hence, comparing the two groups, in liver cirrhosis a significantly higher release of vWFAg and t-PA could be observed. These findings suggest on the one hand that the increased release contributes substantially to the sustained elevation of plasma vWF level in liver cirrhosis. On the other hand, the results indicate that not only the vascular surface of the diseased liver but most probably the total endothelium plays an important role in this phenomenon.

Adult↗
PubMed1992

Effect of platelet encapsulated Iloprost on platelet aggregation and adhesion to collagen and injured blood vessels in vitro.

A novel approach to site-directed delivery of drugs in vivo using blood platelets as carrier vehicles is being investigated. In this context some initial studies are reported on the effect of platelet encapsulated anti-platelet drugs on platelet aggregation and adhesion to fibrillar collagen and injured arteries in vitro. The stable prostacyclin analogue Iloprost has been encapsulated within human and pig platelets by high voltage electroporation (Hughes and Crawford 1989 and 1990). After resealing the platelets, the packaged drug has a negligible effect upon platelet adhesion to a surface of fibrillar collagen or to damaged aorta (stripped to the tunica media to simulate deep injury). The rate of platelet recruitment to the collagen shows no dose dependency with respect to intracellular Iloprost concentrations. After high Iloprost loading, as few as 2% drug loaded platelets in a mixture with control (sham encapsulated) platelets, inhibit agonist-induced platelet aggregation > 50%. The prior deposition of a "lawn" of Iloprost-loaded platelets onto fibrillar collagen or damaged aorta has a substantial inhibitory effect (50-70%) upon the secondary recruitment of normal platelets compared with recruitment to a "lawn" of normal platelets. This inhibition of secondary recruitment occurs even in the presence of a platelet activator. If reduction of platelet recruitment to a vessel wall lesion results in a decrease in the local concentration of platelet granule-derived smooth muscle cell chemotactic and proliferative factors, this site-directed drug delivery may well have application for the prevention of restenosis following balloon angioplasty procedures.

Animals↗
PubMed1991

[Successful treatment of severe hemorrhage by using thrombocyte suspension with cryoprecipitate in type III Willebrand disease].

A 24-year-old woman with severe haemorrhagic complication due to type III von Willebrand's disease is reported, as the first such case in Hungary. Analysis of seven family members affected by the type III mutant gene was compatible with an autosomal recessive mode of inheritance. Severe, iatrogenic epistaxis of the patient was not improved by cryoprecipitate and DDAVP. Platelet suspension together with cryoprecipitate immediately stopped bleeding. Simultaneous application of cellulare (platelet suspension) and plasmatic (cryoprecipitate) Willebrand protein is suggested for patients with severe (type III) von Willebrand's disease.

Adult↗
PubMed1991

[Successful cyclosporin therapy of acquired hemophilia caused by factor VIII (VIII:C) inhibiting antibody].

A 47-year-old woman is reported who had a life-threatening, subarachnoideal bleeding due to the spontaneous development of factor VIII:C inhibitor. Cyclosporin combined with prednisone allowed a full recovery and the elimination of antibody even when other therapeutic facilities failed to be effective. Actual problems of treatment of factor VIII inhibitors are briefly surveyed.

Antibodies↗
PubMed1991

Treatment of the severe bleeding episode in type III von Willebrand's disease by simultaneous administration of cryoprecipitate and platelet concentrate.

A severe, life-threatening bleeding episode in a 24-year-old woman suffering from type III von Willebrand's disease was treated by large doses of cryoprecipitate with unsatisfactory results. Bleeding ceased and the bleeding time normalized only after concomitant administration of platelet concentrates. In the treatment of von Willebrand's disease patients possessing platelets with absent or insufficient von Willebrand factor activity the administration of plasma concentrates together with platelets appears to be justified.

Adult↗