Physiologic protein concentrations

The complexity of the FT-IR spectra collected in the Attenuated Total Reflectance (ATR) mode which can include contributions from (a) the adsorbed protein layer or (b) the soluble proteins in the liquid layer adjacent to the ATR surface but within the "depth of penetration" of the evanescent field of the IR beam (this so-called "bulk" effect is especially significant when near-physiological protein concentrations are studied) ... 

From this equation it can be seen that for a given receptor density systems can spontaneously produce physiological response and that this response is facilitated by high G-protein concentration, high-affinity receptor/ G-protein coupling (low value of KG), and/or a natural tendency for the receptor to spontaneously form the active state. This latter property is described by the magnitude of L, a thermodynamic constant unique for every receptor. 

Uptake of LCFAs across the lipid-bilayer of most mammalian cells occurs through both a passive diffusion of LCFAs and a protein-mediated LCFA uptake mechanism. At physiological LCFA concentrations (7.5 nM) the protein-mediated, saturable, substrate-specific, and hormonally regulated mechanism of fatty acids accounts for the majority (>90%) of fatty acid uptake by tissues with high LCFA metabolism and storage such as skeletal muscle, adipose tissue, liver,... 

The first four materials (IRMM/IFCC-452, 453, 454, 455) are expected to be released during 2000. Projects on the certification of reference materials for cardiac marker (myoglobin) and total protein concentration in serum are under discussion. Even so the number of available CRMs for clinical chemistry and occupational toxicology is still limited. This has to do with the complexity of physiological compounds (e.g. proteins), the instabihty (e.g. enzymes), or the volatility (e.g. solvents). 

One of the important developments in dairy technology in recent years has been the fractionation of milk into its principal constituents, e.g. lactose, milk fat fractions and milk protein products (caseins, caseinates, whey protein concentrates, whey protein isolates, mainly for use as functional proteins but more recently as nutraceuticals , i.e. proteins for specific physiological and/or nutritional functions, e.g. lactotransferrin, immunoglobulins). 

The mechanism of AD pathogenesis still remains unclear. However, one mechanism, amyloid (3 (A(3) accumulation, may be due to the disturbance in metal homeostasis in AD brains [Strausak et al., 2001]. A(3 peptides are the major constituents of the amyloid core of senile plaques, which are derived from the amyloid precursor protein (APP) and are secreted into extracelluar spaces. Both APP and A(3 contain a copper-binding domain [Hesse et al., 1994 Atwood et al., 1998]. High concentrations of copper, zinc, and iron have been found within the amyloid deposits in AD brains [Lovell et al., 1998], A(3 peptides can be rapidly precipitated by copper under mildly acidic conditions and by zinc at low physiological (submicromolar) concentrations [Bush et al., 1994], An age-dependent binding between A(3 peptides with excess brain metals (copper, iron, and zinc) induces A(3 peptides to precipitate into metal-enriched plaques [Bush, 2002],... 

Disaccharides can have similar utility to monosaccharides in DNA delivery polymers. Trehalose, a disaccharide composed of two glucose units linked via an a-(l—>1) glycosidic bond, has been shown to have cryo- and lyo-protective properties, attributed to an unusually large hydration volume [152]. As a function of these properties, trehalose has been shown to prevent aggregation and fusion of proteins and lipids [153]. Logically, incorporation of these features into a polymer backbone could afford similar characteristics to a DNA delivery system and may prevent aggregation of polyplexes in physiological serum concentrations and ionic... 

It is possible to predict what happens to Vd when fu or fur changes as a result of physiological or disease processes in the body that change plasma and/or tissue protein concentrations. For example, Vd can increase with increased unbound toxicant in plasma or with a decrease in unbound toxicant tissue concentrations. The preceding equation explains why because of both plasma and tissue binding, some Vd values rarely correspond to a real volume such as plasma volume, extracellular space, or total body water. Finally interspecies differences in Vd values can be due to differences in body composition of body fat and protein, organ size, and blood flow as alluded to earlier in this section. The reader should also be aware that in addition to Vd, there are volumes of distribution that can be obtained from pharmacokinetic analysis of a given data set. These include the volume of distribution at steady state (Vd]SS), volume of the central compartment (Vc), and the volume of distribution that is operative over the elimination phase (Vd ea). The reader is advised to consult other relevant texts for a more detailed description of these parameters and when it is appropriate to use these parameters. 

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