Arachidonic acid adults

The essential fatty acids in humans are linoleic acid (C-18 2 N-6) and a-linolenic acid (C18 3 N-3). Arachidonic acid (C20 4 N-6) is also essential but can be synthesized from linoleic acid. Administration of 2% to 4% of total daily calories as linoleic acid should be adequate to prevent essential fatty acid deficiency in adults (e.g., infusion of 500 mL of 20% intravenous lipid emulsion once weekly).7 Biochemical evidence of essential fatty acid deficiency can develop in about 2 to 4 weeks in adult patients receiving lipid-free PN, and clinical manifestations generally appear after an additional... 

Aspirin is maximally effective as an antithrombotic agent at the comparatively low dose of 81 to 325 mg per day. (The antipyretic dose of aspirin in adults is 325 to 650 mg every 4 h.) Higher doses of aspirin are actually contraindicated in patients prone to thromboembolism. At higher doses, aspirin also reduces synthesis of prostacyclin, another arachidonic acid metabolite. Prostacyclin normally inhibits platelet aggregation. The prophylactic administration of low-dose aspirin has been shown to increase survival following myocardial infarction, decrease incidence of stroke, and assist in maintenance of patency of coronary bypass grafts. 

It is well established that dietary (n-6) and (n-3) LCP modulate Thl and Th2 immune cell responses generation in the adult (Calder and Grimble, 2002). Docosahexaenoic acid (DHA) and arachidonic acid (AA) constitute a relatively small fraction of the total fatty acids in human breast milk, but have recently been suggested to participate in immime development... 

Diethylcarbamazine citrate (Hetrazan) is active against several microfilaria and adult filarial worms. It interferes with the metabolism of arachidonic acid and blocks the production of prostaglandins, resulting in capillary vasoconstriction and impairment of the passage of the microfilaria. Diethylcarbamazine also increases the adherence of microfilariae to the vascular wall, platelets, and granulocytes. 

In susceptibie individuais, NSAIDs may precipitate acute bronchospasm. It affects 10-20% of adults with asthma but is rare in asthmatic children. The mechanism is related to cyclooxygenase inhibition, with shunting of arachidonic acid metabolism from the prostaglandin pathway to the biosynthesis of ieukotrienes with increased mucosal permeability and bronchospasm. Susceptible patients should avoid NSAIDs since the bronchospasm may be severe and has been fatal. Paracetamol in doses up to 1000 mg daiiy wiii be toierated by most patients. True type I allergic reactions to NSAIDs, with specific IgE, are rare but anaphyloactoid reactions have occasionally been described in patients with a history of aiiergy or bronchiai asthma. 

Strosznajder J, Chalimoniuk M, Samochocki M. Activation of serotonergic 5-HT1A receptor reduces Ca2+- and glutamatergic receptor-evoked arachidonic acid and NO/cGMP release in adult hippocampus. Neurochem Int 1996 28 439-444. 

Of adult asthmatics 2-20% have aspirin hypersensitivity (9). The mechanism is related to a deficiency in bronch-odilator prostaglandins prostaglandin inhibition may make arachidonic acid produce more leukotrienes with bronchoconstrictor activity. Oral challenge in asthmatic patients is an effective but potentially dangerous method for establishing the presence of aspirin hypersensitivity (63). 

FAs liberated from food during absorption are metabolized more easily if they are short or medium chain, i.e., C10 or below. The sn-2 monoacylglycerols can be absorbed directly. Therefore, essential or desired FAs are most efficiently utilized from the sn-2 position in acylglycerols. In accordance with this, TAGs with short-chain FAs (SCFAs) or MCFAs at the sn-1 and sn-3 positions and PEFAs at the sn-2 position are rapidly hydrolyzed with pancreatic lipase (sn-1,3-specific lipase) and absorbed efficiently into mucosal cells. SCFAs or MCFAs are used as a source of rapid energy for infants and patients with fat malabsorption-related diseases. LCFAs, especially DHA and arachidonic acid, are important in both the growth and development of an infant, while n-3 PEFAs have been associated with reduced risk of cardiovascular disease in adults (Christensen et al., 1995 Jensen et al., 1995). 

Salem N Jr, Pawlosky R, Wegher B, Hibbeln J. In vivo conversion of linoleic acid to arachidonic acid in human adults. Prostaglandins Leukotrienes Essential Fatty Acids 1999 60(5-6) 407 10. 

During the fetal development bovine, rabbit and sheep lung were shown to have a poor capacity for thromboxane synthesis compared with the adult lung. The fetal lung was instead quite active in converting arachidonic acid into PGEj [271,272,275]. 

A9 12 15 18 (24 4) and A6 9 12 15 18 (24 5). Such a concept of "reservoirs" of potential arachidonic acid might partially explain the difficulty of depleting the adult animal of essential fatty acids. 

Table 1. Changes in C-arachidonic acid incorporation in lipids of the adult brain by electroshock or ischemia...

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