摘要:

Maximum blood concentrations (Cmax) of thrombin and tranexamic acid were evaluated in the bloodstream after local application of a radioactively labelled cryoprecipitate based fibrin (CBF) sealant to a partial liver resection in rabbits. The Cmax of3H-tranexamic acid reached a peak of 0.015 mg/ml of plasma after 1 h and then slowly cleared within 10 h, never reaching pharmacologically active systemic levels, and demonstrating a slow release from the clot and a fast clearance for the drug. The Cmax of125I-α-thrombin never exceeded 56 milliunits of thrombin equivalent per ml, lower than endogenous thrombin generated in abdominal surgery. Furthermore, the low ratio of trichloroacetic acid precipitable counts versus total counts indicates that the majority of thrombin proteins are in a continuous process of degradation into very small peptides, which are known to be biologically inactive. The bioavailability of tranexamic acid, when embedded in a fibrin sealant, is much longer than when intravenously administered. Conversely, the circulating thrombin resulting from the sealant is low-molecular-weight degradation products with probably no significant biological activity.

ISSN:0957-5235    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Tissue factor is heterogeneously distributed within and among cells in cultures of U87-MG, a glioblastoma-derived line. The heterogeneity among cells may reflect the presence of distinct populations within the U87-MG cultures. This hypothesis has been confirmed by cloning of five distinct sublines from the parent population. These subpopulations have remained distinct through 4 months of growth in culture and one cycle of cryogenic preservation and thawing. The cultures differ in growth rates, amounts of tissue factor activity expressed, tissue factor antigen measured by flow cytometry, and patterns of tissue factor distribution studied by immunofluorescence microscopy. Characterization of these sublines allowed us to recognize that the tissue factor distribution on polarized cells (e.g. spindle-shaped) differed from that on cells with less polar morphologies. Finely speckled tissue factor staining tended to be localized to polarized aspects of the cell body where actin stress fibers are commonly present, whereas larger distinct foci of tissue factor were present in regions of membrane spreading. These results show that tissue factor is distributed differently in distinct regions of plasma membrane differentiation. Furthermore, the isolation of distinct stable subpopulations by dilutional cloning of U87-MG cultures serves as a reminder that cell culture heterogeneity can complicate experiments using molecular genetic manipulation of cultured cells which require clonal isolation of genetically altered lines.

ISSN:0957-5235    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We have developed a rapid method which allows us simultaneously to determine two genetic variations that are associated with an increased risk of venous thrombosis: the 20210 G→A mutation present in the 3′-UT region of the prothrombin gene and the 1691 G→A mutation giving rise to factor V Leiden. Our strategy involves the coamplification of exon 10 of the factor V gene and of the region 3′ from the prothrombin gene using modified oligonucleotides, permitting the introduction of a single Hind III cleavage site in fragments bearing one of the mutations. As a result of its time- and cost-saving features, this combined method should be considered for screening large numbers of patients.

ISSN:0957-5235    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0957-5235    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0957-5235    

出版商:OVID    

年代:1998

数据来源: OVID