Classification function, definition

The lipoproteins present in plasma may be operationally defined according to their density, as low or very low density lipoproteins and high density lipoproteins, but other, more functional definitions may be more appropriate in connection with in vivo metabolism. Examples are the hpoprotein classes chylomicrons and chylomicron remnants. Alaupovic has suggested a classification based on the apolipoprotein composition [1]. As apolipoproteins often determine the metabolic fate of lipoprotein particles this is a logical approach. Lipoprotein particles with specific apolipoprotein compositions exist in all density fractions of human plasma, as well as plasma from a variety of animal species. 

Haslam E (1998) Practical polyphenolics from structure to molecular recognition and physiological function. Cambridge University Press, Cambridge, UK Khanbabaee K, Van Ree T (2001) Tannins classification and definition. Nat Prod Rep 18 641-649... 

Serotoninergic System. Figure 1 Graphical representation of the current classification of 5-hydroxytryptamine (5-HT) receptors. Receptor subtypes represented by shaded boxes and lowercase designate receptors that have not been demonstrated to definitively function in native systems. Abbreviations 3-5r cyclic adenosine monophosphate (cAMP) phospholipase C (PLC) negative (-ve) positive (+ve)... 

A consensus-derived definition and classification system for ARF has been proposed and is being validated (Fig. 75-1). Components of the system include both GFR and UOP plus two clinical outcomes. Definitions of risk of dysfunction, injury to and /ail ure of the kidney, loss of function, and end-stage kidney disease are included in the RIFLE acronym. 

Lipids are substances that are considered to be essential for cell functioning all cells contain lipids, hence lipids must be primary metabolites However, the spectrum of lipids produced by various species can differ very markedly indeed the lipid spectrum of a species can help identify that species.= Furthermore, the study of mutants with altered lipid compositions has shown that some individual lipids can be lost from plants without any apparent loss of short-term fitness. This suggests that some individual lipids are more like NPs and can be lost without a short-term loss of fitness. But clearly, cells need lipid-rich membranes hence, some lipids are essential for life. So, lipids as a group would have to be classified by KosseTs definition of primary metabolites but some individual lipids wouid be classified as secondary (equivalent to NPs). The way to resolve this contradiction is to abandon KosseTs classification, as will be argued in more detail later, but first another instructive example. 

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