Plasma biology

Pharmacokinetics. Heparin is poorly absorbed from the gastrointestinal tract and is given i.v. or S.C. once in the blood its effect is immediate. Heparin binds to several plasma proteins and to sites on endothelial cells it is also taken up by cells of the reticuloendothelial system and some is cleared by the kidney. Due to these factors, elimination of heparin from the plasma appears to involve a combination of zero-order and first-order processes, the effect of which is that the plasma biological effect alters disproportionately with dose, being 60 min after 75 units per kg and 150 min after 400 units per kg. 

S. B. Lotito and C. G. Fraga. Ascorbate protects (+)-catechin from oxidation both in a pure chemical system and human plasma. Biological Research 33 (2(KX)) 151-157. 

Lepage, L., F. Schiele, R. Gueguen, and G. Siest. 1985. Total cholinesterase in plasma Biological variations and reference ranges. Clinical Chemistry 31 546-550. 

The next level of complexity is the analysis of compounds in complex matrices such as blood plasma, biological tissues, or environmental samples. Here the class of compounds of interest needs to be recovered from the matrix using, for instance, solvent or solid phase extraction. The resulting extracts are usually still complex mixtures that are best separated chromatographically prior to introduction into the mass spectrometer. The polarity of the analytes will determine whether GC or LC is the appropriate technique. The versatility of QqQ instruments is particularly suited... 

Pietrzak WS, Eppley BL (2005) Platelet rich plasma biology and new technology. J Craniofac Surg 16 1043-1054... 

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