Haemoperfusion Health Dictionary

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Haemoperfusion: From 1 Different Sources

n. the passage of blood through a sorbent column with the aim of removing toxic substances. The commonest sorbent in use is charcoal, microencapsulated with cellulose nitrate. Haemoperfusion might be considered for the treatment of poisoning with carbamazepine, theophylline, barbiturates, and Amanita mushrooms.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Prostaglandins

Those natural substances, so-called because they were ?rst discovered in the SEMEN and thought to arise in the PROSTATE GLAND, are a group of fatty-acid substances with a wide range of activity. The richest known source is semen, but they are also present in many other parts of the body. Their precise mode of action is not yet clear, but they are potent stimulators of muscle contraction and they are also potent VASODILATORS. They cause contraction of the UTERUS and have been used to induce labour (see PREGNANCY AND LABOUR); they are also being used as a means of inducing therapeutic abortions (see ABORTION).

Prostaglandins play an important part in the production of PAIN, and it is now known that ASPIRIN relieves pain by virtue of the fact that it prevents, or antagonises, the formation of certain prostaglandins. In addition, they play some, although as yet incompletely de?ned, part in producing in?ammatory changes. (See INFLAMMATION; NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).)

Thus prostaglandins have potent biological effects, but their instability and rapid metabolism make them short-acting. They are produced but not stored by most living cells and act locally. The two most important prostaglandins are prostacycline and thromboxane: prostacycline is a vasodilator and an inhibitor of platelet aggregation; thromboxanes have the opposite effects and cause vasoconstriction and platelet aggregation. The NSAIDs act by blocking an ENZYME called cyclo-oxygenase which converts arachidonic acid to the precursors of the various prostaglandins. Despite their potent pharmacological properties, the role of prostaglandins in current therapeutics is limited and controversial. They have been used most successfully as an inhibitor of platelet aggregation in extra-corporeal haemoperfusion systems. The problems with the prostacyclines is that they have to be given intravenously as they are inactive by mouth, and continuous infusion is required because the drug is rapidly eliminated with a half-life of minutes. Side-effects tend to be severe because the drug is usually given at the highest dose the patient can tolerate. The hope for the future lies in the exploitation of the compound to generate, synthetically, stable orally active prostacycline analogues which will inhibit platelet aggregation and hence thrombotic events, and yet have minimal effects on the heart and blood vessels.... prostaglandins


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