ISSN:0953-7104    

DOI:10.3109/09537109309013232

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Platelet-derived growth factor (PDGF) is a pleotropic mitogen involved in several normal processes and pathological settings which include embryonal development, wound healing, atherosclerosis and neoplasia. We have reviewed the literature on the structure, function and regulation of PDGF and its receptors, and the roles played by PDGF in these settings.

ISSN:0953-7104    

DOI:10.3109/09537109309013233

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

It has recently been demonstrated that both initiators and inhibitors (viz iloprost) of aggregation stimulate the uptake of [45Ca2+] by human platelets. Since it was postulated that this calcium uptake reflects changes associated with signal transduction, we investigated the role of cAMP-dependent protein kinases and protein kinase C (PKC) in mediating [45Ca2+] uptake by washed human platelets. Phorbol myristate acetate (PMA; a PKC activator), sodium fluoride (NaF; a putative G protein activator), ADP and collagen stimulated the uptake of [45Ca2+] by platelets in dose-dependent manners. The inert phorbol ester, phorbol 4-α-didecanoate had no effect on [45Ca2+] uptake. PMA-stimulated and NaF-stimulated [45Ca2+] uptake was inhibited in concentration-dependent manners by the PKC inhibitor, staurosporine. Staurosporine also inhibited [45Ca2+] uptake when stimulated with collagen, ADP and to a lesser extent by adrenaline. Staurosporine, however, had no effect on [45Ca2+] uptake when stimulated with calcium ionophore A23187, dibutyryl cAMP or iloprost. The more specific inhibitor of PKC, chelerythrine, inhibited [45Ca2+] uptake when stimulated by PMA, collagen and adrenaline but not A23187 or dibutyryl cAMP. H8 (a PKA inhibitor) inhibited iloprost- and dibutyryl cAMP-stimulated (but not A23187-stimulated) [45Ca2+] uptake. These data indicate that [45Ca2+] uptake is: (1) mediated by PKC when stimulated by proaggregatory agonists and, (2) that cAMP-dependent protein kinase mediated signal transduction involves a calcium uptake component. Thus, these data demonstrate that the [45Ca2+] uptake elicited by both stimulators and inhibitors of aggregation reflect events associated with signal transduction, possibly at the plasma membrane and not necessarily changes in intracellular calcium (i.e. calcium influx into the cytosol).

ISSN:0953-7104    

DOI:10.3109/09537109309013234

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

In the Caucasian population, platelet incompatibility within the HPA-1 (PlA1/A2) and HPA-5 (Bra/b) alloantigen systems are the two most likely causes of post-transfusion purpura (PTP) and neonatal alloimmune thrombocytopenia. However, the way in which HLA (class-II) antigens participate in alloantibody formation is unclear. The patient (M-J.G.) is a middle aged woman with two children who developed a severe PTP (<2000 platelets/µ1) 8 days after receiving red cell concentrates during coronary bypass surgery. During treatment with intravenous gamma-globulin and corticosteroids, her platelet count peaked, fell again, and returned to normal over a period of several months. Western blotting and/or the monoclonal antibody specific-immobilization of platelet antigens (MAIPA) assay performed with serum prepared at the height of her initial thrombocytopenia revealed antibodies to both the PlA1and the Braalloantigens. This rare combination prompted us to study the expression of specific HLA class II antigens in the patient. HLA-DR and DQ typing was performed from genomic DNA by the recently developed polymerase chain reaction-restriction fragment length polymorphism procedure (PCR-RFLP). The patient was found to express the DRB1*1302/1303 and DRB3*0101/0301 alleles (serological specificities: HLA-DR6 and DR52a/c respectively). She also expressed the DQA1*0102/0501, DQB1*0601 and DQB1*0301 alleles. Thus, this case provides further evidence linking an immune response to PlA1and Braantigens with HLA-DR52a/c and DR6.

ISSN:0953-7104    

DOI:10.3109/09537109309013235

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

This study explores a kinetic approach to distinguish Ca2+-dependent and independent forms of PKC activity in a cell-free system of human platelets. Incorporation of32P from [γ-32P] ATP into total proteins, in the presence or in the absence of histone IIIS, at various combinations of added lipids (diolein and phosphatidyl serine) and Ca2+, fail to distinguish PKC from other kinases. Phosphorylation of the 40 kDa protein, a major and specific platelet PKC substrate resolved by SDS-PAGE, is completely dependent on the added lipids, allowing the determination of PKC and its two sub-forms: dependent and independent Ca2+. The activities of these forms and their ratio are characteristics for an individual, while the inter-individual difference is much greater, with an overall average ratio of 2:1 (n = 9). The forms differ in sensitivity to staurosporine with IC50= 14.6 and 4.3 nM for the Ca2+-dependent and independent forms, respectively. Furthermore, cAMP at 1µM inhibits selectively the Ca2+-dependent form by 45%. Okadaic acid, a potent inhibitor of protein phosphatase 1 and 2A, enhances at 1µM the activity of the Ca2+-dependent form. It is concluded that the two PKC forms that are determined in the crude cell free system of human platelets by measuring the endogenous phosphorylation have distinct properties.

ISSN:0953-7104    

DOI:10.3109/09537109309013236

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Platelet aggregation in response to ADP (10µM) and collagen (4µg/ml) in fresh and stored platelet concentrates (PC) and the enhancement of aggregation of the stored platelets after resuspension in fresh plasma and plasma-free medium were measured. The ability of platelets in autologous plasma to respond to the two agonists decreased significantly on days 2 and 5 of storage to 18 and 4% (p<0.001) respectively of that seen in platelet-rich plasma on day 0 (100%). A 2-fold or greater improvement (p<0.01) in the aggregation response was achieved when the autologous plasma in stored PC was replaced by fresh allogeneic plasma just before testing. The effect was even greater (three-fold or more, p<0.001) when the autologous plasma was first replaced by plasma-free medium followed by suitable dilution for the test in fresh allogeneic plasma. These observations indicate another way to rejuvenate stored platelets and enhance their residual capacity to aggregate ex vivo. They could provide a basis for a suitable test for use within a quality assurance programme for stored PC.

ISSN:0953-7104    

DOI:10.3109/09537109309013237

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

ISSN:0953-7104    

DOI:10.3109/09537109309013238

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

ISSN:0953-7104    

DOI:10.3109/09537109309013239

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor