ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Microheterogeneity of antithrombin III (AT-III) was investigated by crossed immunoelectrofocusing (CIEF) on eleven molecular variants. A normal pattern was found in five variants while two different abnormal CIEF patterns were found in the other four and two variants, respectively. Point mutations causing a major pIchange (exceeding 4.0) of the amino acid substituted lead to alterations in the overall microheterogeneity. The variants thus substituted share a first type of abnormal CIEF pattern with alterations throughout the pH range, regardless of the location of the mutation (reactive site and adjacent regions or heparin binding region). Minor amino acid pIchanges in these regions do not alter the AT-III overall microheterogeneity, whatever the resulting functional defect. However, if the mutation is placed in the region around positions 404 or 429, then even minor changes of the amino acid pIseem able to alter the overall charge, leading to a second type of abnormal CIEF pattern with the main alteration at pH 4.8–4.6. Neuraminidase treatment leads to disappearance of microheterogeneity except for the variants with the Arg393 to Cys substitution. Addition of thrombin induces CIEF modifications specifically related to the functional defect. A normal formation of thrombin–antithrombin complexes induces a shift towards the more acid pH range, whereas in the variants substituted at the reactive site the CIEF pattern is substantially unaffected by thrombin; variants substituted at positions 382–384 show a maximal thrombin-induced increase of the isoforms at pI4.8–4.6. Therefore mutant antithrombins with different functional abnormalities but sharing a common CIEF pattern were well distinguished. Thus CIEF can be a useful tool to investigate congenital AT-III pathological variants as well as different functional roles of physiological isoantithrombins.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Young adults with cyanotic congenital heart disease have a high incidence of respiratory and haemostatic problems. Activated neutrophils release vasoactive and chemotactic factors which result in endothelial injury, lung parenchymal damage and the activation of platelets and coagulation pathways. To investigate the contribution of neutrophil activation to morbidity in young adults with cyanotic congenital heart disease, plasma neutrophil elastase levels were measured in 25 cyanotic patients and the results compared to patients with acyanotic heart disease and normal controls. Neutrophil elastase levels were significantly elevated in the group with cyanotic congenital heart disease (P< 0.001). Platelet activation was significantly increased in the patients with cyanotic heart disease (P< 0.001). Platelet aggregation was impaired only in those with haematocrits greater than 0.50 (P< 0.02). Whole blood coagulation, as determined by thrombelastography, was within normal limits. The reason for neutrophil activation in patients with cyanotic congenital heart disease is unclear, but activated neutrophils may contribute to the respiratory and haemostatic problems common to these patients.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Thrombotic events have been reported in acute lymphoblastic leukaemia patients, especially during or after l-asparaginase administration. A so-called L-asparaginase associated coagulopathy has been well recognized, being characterized by a hypercoagulable state (decrease of antithrombin III, plasminogen, protein C, protein S and increase of prothrombm fragment F1+2, thrombin—antithrombin complexes and fibrinopeptide A). The aim of this study was to determine whether the supplementation of antithrombin III (AT-III) concentrates could improve the L-asparaginase associated coagulopathy, thereby blocking the activation of the haemostatic system. In 25 adult patients with acute lymphoblastic leukaemia (M19, F 6, mean age 34 years) antithrombin III (AT-III) concentrates were administered at daily doses of 50 U/kg for 10 consecutive days from the beginning of l-asparaginase therapy (6000 U/m2/day s.c. for 7 days), given according to the GIMEMA ALL 0288 trial. A marked increase of antithrombin III was recorded on days IV-VIII-XI (P<0.001). No changes in protein C, protein S, plasminogen, α2-antiplasmin, factor VII and platelet count were observed and there was no increase in markers of hypercoagulability. There was no evidence of disseminated intravascular coagulation. In conclusion, AT-III concentrate supplementation during l-asparaginase therapy, by the achievement of high levels of antithrombin III, is associated with a lack of activation of the haemostatic system and appears to overcome the complex coagulopathy associated with L-asparaginase.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The frequency of five factor VIII gene intragenic and linked DNA polymorphisms and five factor IX gene intragenic polymorphisms was studied in Thai females. The polymorphisms in the FVIII gene were detected by restriction enzymesBelI,XbaI,BglI and at linked lociDX13 (DXS15) and Stl4 (DXS52) byBqlII andTaqI, respectively, and in the FIX gene byMseI,DdeI,XmnI,TaqI andHhaI. With the exception of theBglI restriction fragment length polymorphism (RFLP), which is absent in Thais, factor VIII polymorphism frequencies were similar in Thais and Caucasians. Combined use ofXbaI andTaqI/St14 resulted in a heterozygosity rate of greater than 90% in Thai females. For FIX, the recently describedMseI RFLP in the 5‘ flanking region was the most informative polymorphism in Thais, 43% of females being heterozygous. The other four polymorphisms added little to the overall heterozygosity rate. The appropriate polymorphisms were used to track defective factor VIII and IX genes through 22 Thai pedigrees with haemophilia to enable carrier status to be assigned to female family members. The information obtained during this study will form the basis for carrier detection and prenatal diagnosis of haemophilia A and B by DNA polymorphism analysis in Thailand.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The influence of 38 IgG fractions with either cardiolipin antibodies only (CLa) or both CLa and lupus anticoagulant activity (LA) on the response to activated protein C (APC) and on the snake venom activation of protein C were investigated. Five of eight IgG fractions with LA activity showed a tendency to reduce the effect of APC in the aPTT method and to simulate the APC-resistance phenomenon. This effect was not observed in IgG fractions without LA activity. The addition of IgG fractions did not decrease enzymatic activation of protein C in normal plasma. No correlation was found between sample protein C activity and CLa level or the extent of clotting time prolongation. These observations suggested that acquired resistance to APC in the presence of some types of phospholipid antibodies may be a cause of thrombophilia in such patients.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Levels of tissue plasminogen activator antigen (t-PA:ag), tissue plasminogen activator inhibitor 1 antigen (PAI-1:ag) and tissue plasminogen activator inhibitor activity (PAI activity), and α-2-antiplasmin (AAP) were measured in plasma from 19 patients with severe trauma on admission and on days 1,2,3 and 7 after the incident. In all patients the Injury Severity Score (ISS) and the number of blood transfusions were recorded. The development of post-traumatic pulmonary dysfunction was observed in four patients. Levels of t-PA:ag, PAI-1:ag and PAI activity were increased, and levels of AAP were low immediately after trauma. Levels of t-PA:ag normalized during the first week, whereas PAI-1:ag levels decreased gradually from day 1 to day 3. Thereafter a secondary increase was observed. A similar trend was observed in levels of PAI activity. Levels of APP increased significantly during the first week. t-PA:ag, PAI-1:ag or PAI activity levels were not correlated with the ISS on any day, but levels of AAP showed a weak correlation with the ISS on day 7. Post-traumatic levels of t-PA:ag and PAI-1:ag were higher in patients who had 6 or more units of blood transfusions for resuscitation. The fibrinolytic markers were not significantly different in patients who had pulmonary dysfunction compared with patients without.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

A poor anticoagulant response to activated protein C (APC) in an activated partial thromboplastin time (aPTT) assay (APC resistance) was recently reported to be a cause of familial thrombophilia. The response to APC was measured in 30 patients suffering from juvenile or recurrent stroke, in 40 patients suffering from venous thromboembolism and in 50 healthy subjects. The prevalence of APC resistance was found to be significantly higher among patients with stroke (20%,P< 0.003) and venous thrombosis (17.5%,P< 0.02) compared with the prevalence of APC resistance among normal controls (2%). In one case of venous thrombosis, the proposita's family (A) could be investigated and in five out of nine investigated members (56%) a poor or borderline response to APC was detected. The family (B) of another APC-resistant patient revealed six subjects with poor coagulation response to APC out of eight family members studied (75%). Measuring protein S activity with an automated calcium-thromboplastin-based protein S activity assay, a significant correlation (P< 0.0001) between the results of this functional protein S assay and APC resistance (represented by the ratio (Rs value) of clotting time with and without addition of activated protein C) was observed. Nine out of 14 patients (64%) with poor APC response showed protein S activities below the normal range. Assessment of protein S activity with a second protein S clotting assay using factor Va as substrate confirmed only 47% of the decreased levels of the thromboplastin-based protein S clotting assay. It is concluded that unless more data concerning the new APC cofactor become available, protein S clotting assays should be considered to be influenced by the new APC-resistance phenomenon and may not therefore be specific for protein S.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Heterozygous factor XI deficiency occurs very frequently among Ashkenazi Jews. To investigate the potential influence of a co-inherited factor XI deficiency state on the clinical phenotype of mild/moderate haemophilia A, 28 unrelated haemophiliacs of Jewish origin were screened for the two most common factor XI gene mutations. Gene lesions were identified in two out of 14 patients of Ashkenazi origin. In the one family analysed further, co-inheritance of both factor XI and factor VIII deficiencies was associated with a bleeding tendency that was more severe than that associated with either deficiency alone.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

It has previously been shown that thrombin effects on endothelial cells can be mediated via G-proteins, which couple the thrombin receptor to several key physiological responses. As G-proteins are known targets of bacterial toxins, specific toxins were used to further characterize G-protein involvement in thrombin activation of bovine pulmonary arterial endothelial cells (6PAEC) and human umbilical vein endothelial cells (HUVEC). Homogenates were exposed to several bacterial toxins in the presence of32P-N AD and ADP ribosylation of proteins determined by autoradiography of SDS-PAGE gels. Major substrates were a 40 kDa protein for pertussis toxin, 39, 45 and 52 kDa proteins (G5) for cholera toxin, a 21 kDa protein for botulinum toxin C, and a 43 kDa protein (actin) for botulinum toxin C2α. The increase in either HUVEC or BPAEC PGI2release induced by thrombin was not altered by pretreatment with any toxin. However, 1 h treatment of BPAEC monolayers with 1 μg/ml pertussis toxin resulted in dramatic barrier dysfunction, which was synergistic with the albumin permeability induced by 1 μM thrombin. In contrast, pretreatment with 1 μg/ml cholera toxin completely prevented the thrombin-induced barrier dysfunction. Moreover, contraction and gap formation due to thrombin challenge, observed by phase contrast microscopy, was greatly augmented by pertussis toxin and prevented by cholera toxin. Whereas 5 μg/ml botulinum toxin C did not affect either basal or thrombin-induced barrier dysfunction, botulinum toxin C2aincreased basal BPAEC permeability over four-fold. Thus, bacterial toxins have specific and divergent effects on thrombin-induced endothelial cell responses. Botulinum toxin C2aappears to interact directly with actin to produce barrier dysfunction. In contrast, cholera toxin promotes barrier function via its known effects on Gs, stimulating adenylate cyclase and increasing cAMP. Because cholera toxin and pertussis toxin (via inhibition of Gi) both increase cAMP, yet have opposing effects on barrier function, the present results suggest that pertussis toxin produces barrier dysfunction via ADP ribosylation of a novel G-protein other than Gior via a novel action of Gi.

ISSN:0957-5235    

出版商:OVID    

年代:1994

数据来源: OVID