Endogenous anions

Organic anion transporters play important roles in the elimination of a variety of endogenous anionic substances, xenobiotics, and their metabolites from the body... 

At pH 7.4, in buffered media containing the common endogenous anions, incremental addition of HC03 to a solution containing these Eu complexes is signalled... 

Influence of Endogenous Anions such as Ascorbate or Citrate... 

The PBRis distinct from the central BZ receptor although both can be present in the same tissues in differing ratios. PBRs are predominately localized on the outer mitochondrial membrane and are thus intracellular BZ recognition sites. The PBR is composed of three subunits an 18,000 mol wt subunit that binds isoquinoline carboxamide derivatives a 30,000 mol wt subunit that binds BZs and a 32,000 mol wt voltage-dependent anion channel subunit. The porphyrins may be endogenous ligands for the PBR. PBRs are involved in the control of cell proliferation and differentiation and steroidogenesis. 

Cellular defense mechanisms against toxins (A multistep mechanism for elimination of toxic metabolites and xenobiotics. It involves various transport, oxidation, and conjugation steps.) are usually divided into several steps as it is visualized on Fig. 3. Organic anion transporting proteins (OATPs) are responsible for the cellular uptake of endogenous compounds and... 

In phase 1, the pollutant is converted into a more water-soluble metabolites, by oxidation, hydrolysis, hydration, or reduction. Usually, phase 1 metabolism introduces one or more hydroxyl groups. In phase 2, a water-soluble endogenous species (usually an anion) is attached to the metabolite— very commonly through a hydroxyl group introduced during phase 1. Although this scheme describes the course of most biotransformations of lipophilic xenobiotics, there can be departures from it. 

Conjugate In biochemical toxicology, a structure (often an anion) formed by the combination of a xenobiotic (usually a phase I metabolite) with an endogenous component (e.g., glucuronate sulfate or glutathione). 

It is important to realize that the serum HCO, concentration may be affected by the presence of unmeasured endogenous acids (lactic acidosis or ketoacidosis). Bicarbonate will attempt to buffer these acids, resulting in a 1 mEq loss of serum HCO, for each 1 mEq of acid titrated. Because the cation side of the equation is not affected by this transaction, the loss of serum HC03 results in an increase in the calculated anion gap. Identification of an increased anion gap is very important for identifying the etiology of the acid-base disorder. The concept of the increased anion gap will be applied later in the case studies section. 

The anion gap is the concentration of plasma anions not routinely measured by laboratory screening. It is useful in the evaluation of acid-base disorders. The anion gap is greater with increased plasma concentrations of endogenous species (e.g., phosphate, sulfate, lactate, and ketoacids) or exogenous species (e.g., salicylate, penicillin, ethylene glycol, ethanol, and methanol). The formulas for calculating the anion gap are as follows ... 

A significant amount of the 02 metabolized by the human organism is converted to the highly reactive superoxide radical anion 02. Endogenous overproduction of 02 may cause considerable... 

Various constituents in plant foods can impede Ca absorption. Plant-based diets can be high in oxalate and phytate, which are recognized as inhibitors of Ca absorption. In fact, Ca absorption is considered to be inversely proportional to oxalic acid content of the food (Weaver et al, 1999). Phytic acid poses Ca absorption problems for those species imable to endogenously synthesize phytase (e.g., humans, birds, and pigs). The Ca in CCM is chelated with the citrate and malate anions, which may make CCM less reactive than other sources of Ca toward food components known to interact with Ca " cations. For example, Lihono et al (1997a) reported data suggesting that the Ca in CCM may be less likely to complex with phytates than other Ca salts. Qn this basis, CCM may be more appropriate for the fortification of soy or other phytic acid-containing products. 

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