Effect of Pyridoxal 5'-Phosphate (PALP) on Human Platelet Aggregation, Dense Granule Release and Thromboxane B2 Generation - Role of Schiff Base Formation

1982 ◽  
Vol 48 (02) ◽  
pp. 136-141 ◽  
Author(s):  
S Krishnamurthi ◽  
J Westwick ◽  
V V Kakkar
Keyword(s):  
Schiff Base ◽  
Direct Interaction ◽  
Dense Granule ◽  
Platelet Membrane ◽  
Thromboxane B2 ◽  
Platelet Surface ◽  
Schiff Base Formation ◽  
Induced Aggregation ◽  
Base Formation

SummaryPyridoxal 5’-phosphate (PALP) inhibited ADP, thrombin, adrenaline, PAF and AA induced aggregation and 14C-5HT release. Thromboxane B2 (TxB2) generation induced by all the above agents except AA was also inhibited indicating that PALP may be inhibiting AA release via phospholipase A2 activation rather than AA metabolism. PALP inhibited ristocetin induced aggegation in PRP and agglutination in formaldehyde-treated washed platelets (FWP). Inhibition of ADP, adrenaline, PAF and AA-induced aggregation and 14C-5HT release by PALP was found in resuspended platelets pretreated with PALP and sodium borohydride suggesting that inhibition was mediated by Schiff base formation with platelet surface amino groups.Irreversible fixation of PALP to the platelet membrane by borohydride reduction also inhibited thrombin induced 14C-5HT release and TxB2 generation but not thrombin induced primary aggregation or ristocetin induced agglutination in FWP. This suggests that PALP may interact with specific glycoproteins on the platelet membrane involved in ADP, adrenaline and PAF induced primary aggregation and that PALP could be inhibiting ristocetin induced agglutination by direct interaction with ristocetin or FVIII RCoF.

Schiff Base Formation upon Complexation of Tris(acetylacetonato)iron with N[(CH2CH2NH2)(CH2CH2OH)(CH2CH2CH2OH)]

2004 ◽  
Vol 630 (13-14) ◽  
pp. 2558-2561 ◽  
Author(s):  
F. Ekkehardt Hahn ◽  
Christoph Jocher ◽  
Thomas L�gger ◽  
Tania Pape
Keyword(s):  
Schiff Base ◽  
Schiff Base Formation ◽  
Base Formation

scholarly journals Thermal Healing, Reshaping and Ecofriendly Recycling of Epoxy Resin Crosslinked with Schiff Base of Vanillin and Hexane-1,6-Diamine

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 293 ◽  
Author(s):  
Van-Dung Mai ◽  
Se-Ra Shin ◽  
Dai-Soo Lee ◽  
Ilho Kang
Keyword(s):  
Schiff Base ◽  
Epoxy Resin ◽  
Elevated Temperatures ◽  
Relaxation Times ◽  
Diglycidyl Ether ◽  
Original Material ◽  
Crosslinked Polymer ◽  
Schiff Base Formation ◽  
Hydrolysis Of ◽  
Base Formation

A bio-derived dihydroxylimine hardener, Van2HMDA, for the curing of epoxy resin was prepared from vanillin (Van) and hexamethylene-1,6-diamine (HMDA) by Schiff base formation. The epoxy resin of diglycidyl ether of bisphenol A was cured with Van2HMDA in the presence of the catalyst, 2-ethyl-4-methylimidazole (EMI). The crosslinked epoxy resin showed thermal-healing properties at elevated temperatures. Moreover, the crosslinked epoxy resin can be reshaped by heating via imine metathesis of the hardener units. The imine metathesis of Van2HMDA was confirmed experimentally. Stress-relaxation properties of the epoxy resin crosslinked with Van2HMDA were investigated, and the activation energy obtained from Arrhenius plots of the relaxation times was 44 kJ/mol. The imine bonds in the epoxy polymer matrix did not undergo hydrolysis after immersing in water at room temperature for one week. However, in the presence of acid, the crosslinked polymer was easily decomposed due to the hydrolysis of imine bonds. The hydrolysis of imine bonds was used for the ecofriendly recycling of crosslinked polymer. It is inferred that thermal-healing, reshaping, and reprocessing properties can be implemented in the various crosslinked epoxy resins with the bio-derived dihydroxylimine hardener, albeit the recycled epoxy resin is of inevitably lower quality than the original material.

ANALYSIS OF THE FUNCTIONAL ROLE OF PLATELET MEMBRANE GLYCOPROTEINS WITH MONOCLONAL ANTIBODIES

1987 ◽  
Author(s):  
H Nagata ◽  
S Nomura ◽  
K Oda ◽  
T Kokawa ◽  
K Yasunaga
Keyword(s):  
Monoclonal Antibodies ◽  
Lymphoblastic Leukemia ◽  
Atp Release ◽  
Platelet Membrane ◽  
Calcium Flux ◽  
Antibody Concentration ◽  
Membrane Glycoproteins ◽  
Induce Platelet Aggregation ◽  
Platelet Surface ◽  
Induced Aggregation

Eight monoclonal antibodies were obtained which recognized platelet surface antigens of these, 5 (NNKYl-32, NNKY2-5, NNKY2-6, NNKY2-11, NNKY2-18 ) recognized GP IIb-IIIa complex, 2 (NNKY5-4, NNKY5-5 ) recognized GP lb and 1 (NNKYl-19) recognized CD 9 antigen. They were used to research the platelet membrane antigens.Monoclonal antibodies that recognize CD 9 antigen, which exists on the surface of platelets, acute lymphoblastic leukemia cells, eosinophils and other tissue, are known to act as an aggregating agent to platelets and NNKYl-19 was fond to induce platelet aggregation accompanied by ATP release. NNKY5-4 had no effect on platelet functions. NNKY5-5 inhibited aggregation induced by ristocetin but had no effect on aggregation induced by ADP, collagen, thrombin, and NNKYl-19. NNKYl-32, 2-5, 2-6, 2-11, and 2-18 inhibited aggregation induced by ADP, collagen, thrombin, and NNKYl-19, although slight release of ATP was recognized when NNKYl-19-induced aggregation was completely inhibited by NNKYl-32. Mutual inhibition of binding to platelet membranes between the 3 groups of monoclonal antibodies was not recognizedNNKYl-19-induced aggregation was associated with a lag time that was plo-longed in inverse proportion to antibody concentration. Aspirin had almost no effect on NNKYl-19-induced aggregation. A TXA2 receptor antagonist, a calci-um-channel blocking drug and EDTA inhibited NNKYl-19-induced aggregation. These results indicate that GP I b, GP IIb-IIIa complex and the cyclooxygenase pathway are not involved in NNKYl-19-induced platelet activation, that the target of NNKYl-19 on the platelet membrane is same as that of TXA2, and that the mechanism of activation by NNKYl-19 is related to calcium flux.

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