Platelet-activating factors

A platelet-activating factor, l-0-alkyl-2-(R)acetyl-sn-glyceryl-3-phosphocholine, is released in the presence of shock and ischemia. The platelet-activating factor antagonist can protect the heart and brain against ischemic injury. 

A combination of acetylsalicylic acid and dipyridimole has been found to be effective in preventing myocardial reinfarction and occlusion of aortocoronary grafts. 

The synthesis of the platelet-activating factor (PAF l-alkyl-2-acetyl-sn-glycero-3-phosphocholine) by the action of phospholipase Aj on phosphatidylcho- 

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Young s modulus for [CERAMICS - PffiCHANICAL PROPERTIES AND BEHAVIOR] (Vol 5) Platelet-activating factor QAE) antagonists... 

The synthetic utihty of the above transformations stems from the fact that many monoesters obtained as a result of hydrolysis may be converted to pharmaceutically important intermediates. For example, the optically active glycerol derivative (27) is a key intermediate in the production of P-blockers. Akyl derivative (25) may be converted into (5)-paraconic acid [4694-66-0] ((5)-5-oxo-3-tetrahydrofurancarboxyhc acid) that is a starting material for the synthesis of (3R)-A-factor. The unsaturated chiral cycHc monoacetate (31) is an optically active synthon for prostaglandins, and the monoester (29) is used for the synthesis of platelet activating factor (PAF) antagonists. 

Platelet Activating Factor A Potent Glyceroether Mediator... 

Platelet activating factor (PAF) was first identified by its ability (at low levels) to cause platelet aggregation and dilation of blood vessels, but it is now known to be a potent mediator in inflammation, allergic responses, and shock. PAF effects are observed at tissue concentrations as low as 10 M. PAF causes a dramatic inflammation of air passages and induces asthma-like symptoms in laboratory animals. Toxic-shock syndrome occurs when fragments of destroyed bacteria act as toxins and induce the synthesis of PAF. This results in a drop in blood pressure and a reduced... 

FIGURE 25.24 Platelet activating factor, formed from Talkyl-2-lysophosphatidylcholine by acetylation at C-2, is degraded by the action of acetylhydrolase. 

Various 1.4-benzodiazepines with a five-membered heteroaromatic ring fused to the 1,2-bond, such as 17, where A represents a heteroaromatic ring, have been prepared by such methods and tested for activity on the central nervous system, as cholecystokinin antagonists and as antagonists of platelet activating factors.245... 

Platelet-activating Factor Platelet Aggregation Inhibitors Platelet-derived Growth Factor Receptor Platelet Inhibitors Platelets... 

These cells respond to a number of different chemoattractants which have specific and distinct receptors on the membrane surface (for recent reviews see Refs. 3 and 4). Such chemoattractants include N-formylpeptides, which are bacterial peptides, and mediators of inflammation such as leukotriene B4, C5a, and platelet activating factor. 

Basophils Release Platelet-Activating Factor Instead of Histamine to Induce IgG-Mediated Systemic Anaphylaxis... 

Lie WJ, Homburg CH, Kuijpers TW, Knol EF, Mul FR Roos D, Tool AT Regulation and kinetics of platelet-activating factor and leukotriene C4 synthesis by activated human basophils. Clin Exp Allergy 2003 33 1125-1134. 

Vadas P, Gold M, Perelman B, Liss GM, Lack G, Blyth T Simons FE, Simons JK, Cass D, Yeung J Platelet-activating factor, PAF acetylhydrolase, and severe anaphylaxis. N Engl J Med 2008 358 28-35. 

Goncharova S, Coyle A, Vadas P, Waserman S, Jor-dana M Concurrent blockade of platelet-activating factor and histamine prevents life-threatening pea-nut-induced anaphylactic reactions. J Allergy Clin Immunol 2009 124 307-314. 27... 

Figure 24-1. Overview of acylglycerol biosynthesis. (PAF, platelet-activating factor.)...

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