| 1. |
- Chen, Daxin, et al.
(författare)
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Regulated inhibition of coagulation by porcine endothelial cells expressing P-selectin-tagged hirudin and tissue factor pathway inhibitor fusion proteins
- 1999
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Ingår i: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337. ; 68:6, s. 832-839
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Tidskriftsartikel (refereegranskat)abstract
- Background. Thrombotic vascular occlusion resulting in infarction occurs during hyperacute rejection of allografts transplanted into sensitized patients and remains a major problem in experimental xenotransplantation. A similar process is also found in disorders of diverse etiology including atherosclerosis, vasculitis, and disseminated intravascular coagulation. Methods. We have previously constructed two membrane-tethered anticoagulant fusion proteins based on human tissue factor pathway inhibitor and the leech anticoagulant hirudin and demonstrated their functional efficacy in vitro. These constructs have now been modified by the addition of a P-selectin sequence to the cytoplasmic tail to localize them in Weibel-palade bodies. They have been transfected into Weibel-palade body-positive endothelial cells isolated from the inferior vena cava of normal pigs. Results. In resting endothelial cells, fusion protein expression colocalized with P-selectin and was confined to Weibel-palade bodies. These cells had a procoagulant phenotype in recalcified human plasma. However, after activation with phorbol ester the anticoagulant proteins were rapidly relocated to the cell surface where they specifically inhibited the clotting of human plasma. Conclusions. Novel anticoagulant molecules may prove useful therapeutic agents for gene therapy in thrombotic disease and postangioplasty or for transgenic expression in animals whose organs may be used for clinical xenotransplantation. Expression in vascular endothelial cells may be regulated by inclusion of P-selectin cytoplasmic sequence, to restrict cell surface expression to activated endothelium.
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| 2. |
- Frey, Sharon, et al.
(författare)
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Interference of antibody production to hepatitis B surface antigen in a combination hepatitis A/hepatitis B vaccine
- 1999
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 180:6, s. 2018-2022
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Tidskriftsartikel (refereegranskat)abstract
- A randomized trial comparing 3 manufacturing consistency lots of a combination hepatitis A/hepatitis B vaccine to each other and to hepatitis A vaccine and hepatitis B vaccine given separately and concurrently was done to evaluate safety, tolerability, and immunogenicity. Healthy volunteers >/=11 years of age were divided into 4 groups. Each of 3 groups received a separate consistency lot of the combination vaccine, and 1 group received separate but concurrent injections of hepatitis A and hepatitis B vaccines. Injections were given at weeks 0 and 24. The combination vaccine was generally well tolerated. The hepatitis A portion of the combination vaccine produced clinically acceptable high seropositivity rates 4 and 52 weeks after the first injection. The hepatitis B portion of the vaccine did not produce clinically acceptable seropositivity rates 4 weeks after the second injection. Lack of antibody production may be attributed, at least in part, to immunologic interference.
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| 3. |
- Riesbeck, Kristian, et al.
(författare)
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Expression of hirudin fusion proteins in mammalian cells : A strategy for prevention of intravascular thrombosis
- 1998
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Ingår i: Circulation. - 0009-7322. ; 98:24, s. 2744-2752
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Tidskriftsartikel (refereegranskat)abstract
- Background - Intravascular thrombosis occurs in disorders of diverse pathogeneses, including allograft and xenograft rejection. In this in vitro study, we describe an approach for tethering the specific thrombin inhibitor hirudin to plasma membranes as part of a genetic strategy for regulating intravascular coagulation. Methods and Results - An HLA class I leader sequence was fused with hirudin linked to domains 3 and 4 of human CD4 and intracytoplasmic sequence from either CD4 or human P-selectin. The constructs were transfected into mouse fibroblasts, Chinese hamster ovary (CHO)-K1 cells, immortalized porcine endothelial cells (IPECs), and a pituitary secretory cell line (D16/16). Thrombin binding to the hirudin fusion proteins expressed on fibroblasts and CHO-K1 cells could be blocked by an anti- hirudin monoclonal antibody and by pretreatment of thrombin with either the synthetic tripeptide thrombin inhibitor PPACK or native hirudin. Hirudin expression significantly modified the procoagulant phenotype of IPECs in human plasma, leading to prolongation of clotting times. Hirudin-CD4-P- selectin fusion proteins accumulated in adrenocorticotropic hormone- containing granules in D16/16 cells, with no cell surface expression except on activation with phorbol ester, when hirudin relocated to the outer membrane. Conclusions - Hirudin fusion proteins were expressed on mammalian cells, where they reduced local thrombin levels and inhibited fibrin formation. Regulated expression was achieved on activated cells by use of the cytoplasmic sequence from P-selectin. In vivo, these fusion proteins may prove useful transgenic or gene therapy agents for preventing intravascular thrombosis.
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