Binding Capacity Of Human Albumin Research Articles

Reduced Fatty Acid Binding Capacity of Human Albumin Used in Volume Resuscitation May Potentially Increase Hemolysis in Hypovolemic Shock

The choice of resuscitation fluid for hypovolemic trauma patients in the absence of fresh whole blood remains controversial. Albumin solutions have shown promise in animal studies but meta‐analysis suggests they have had little to no benefit in human trials. This contradiction is currently unresolved. Unbound (cytotoxic) free fatty acids (FFAs) are generated in the intestine during ischemia and enter the mesenteric lymph, from where they likely enter the circulation, resulting in organ damage, hemolysis, coagulopathy and further ischemia. We hypothesize that resuscitation fluids with higher available binding capacities for FFAs may help prevent these events in shock. The objectives of this in‐vitro study were to determine: 1) if commercial sources of pharmaceutical‐grade human albumin contain FFAs, 2) if these FFAs result in a decreased available fatty acid binding capacity, and 3) if binding capacity will affect the level of hemolysis that occurs in whole blood when exogenous FFA is introduced in levels similar to those in shock. To achieve these objectives, we first measured FFA concentrations in human albumin via a kit. We then developed a new assay for measuring fatty acid binding capacity using exogenous oleic acid (OA), glass fiber filtration, and the FFA kit to measure binding capacity in both the human albumin and FFA‐free bovine albumin. Lastly, we mixed fresh human whole blood 4:1 with PBS, human albumin, FFA‐free bovine serum albumin (BSA), or BSA that was first saturated to its binding capacity with OA and measured the amount of hemoglobin released into the plasma after 30 minute incubation with 0 to 5 mM OA. We found that pharmaceutical‐grade 5% human albumin contained 4.6±0.3 mM FFA (N=5 lots), ~7x the physiologic concentration, leaving an available binding capacity of 4.8±0.6 mM out of a total binding capacity of 9.4±0.8 mM. This represented a significant loss of binding capacity (p<0.0001) compared to the total. FFA‐free BSA (N=5 replicates) had significantly greater available binding capacity of 7.0±1.4 mM (p=0.02) compared to the pharmaceutical‐grade human albumin. In 4:1 mixtures of blood to PBS or albumin, hemolysis was reduced after addition of all concentrations of exogenous OA with 25% FFA‐free compared to 25% pre‐saturated BSA (p<0.04). Likewise, 0.5 and 5 mM exogenous OA caused less hemolysis when blood was pre‐mixed with 5% FFA‐free BSA than with 5% human albumin (p<0.01). These preliminary findings suggest that the failure of albumin in human trials to live up to the promise of animal studies may be due to steps in the manufacturing process that reduce the FFA binding capacity of human albumin.Support or Funding InformationSupported by US Army Medical Research & Materiel Command.

Reduction in the cobalt binding capacity of human albumin with myocardial ischemia

Reduction in the cobalt binding capacity of human albumin with myocardial ischemia

A method for transmission and scanning electron microscopy of undecalcified human bone marrow biopsy specimens using cryofracture.

The purpose of this study was to determine whether changes in long-chain free fatty acid concentration would alter the transport and utilization of another organic ligand that was bound to human plasma albumin. Ehrlich ascites cells were incubated in medium containing human albumin, and the uptake of 2-(49-hydroxyphenylazo)benzoic acid was measured relative to the free fatty acid concentration of the medium. As the molar ratio of free fatty acid to albumin was raised from 1 to 4, hydroxyphenylazobenzoic acid uptake by the cells increased. In contrast, cells "loaded" with large quantities of fatty acid took up no more hydroxyphenylazobenzoic acid from an albumin-free medium than did cells loaded with only small amounts of fatty acid. Equilibrium dialysis binding measurements indicated that the binding capacity of human albumin for hydroxyphenylazobenzoic acid decreased as the molar ratio of free fatty acid to albumin was raised. Therefore, it is likely that the free fatty acid-induced increase in hydroxyphenylazobenzoic acid uptake by the Ehrlich cells was due to displacement of this compound from strong to weaker albumin binding sites rather than to a direct effect of fatty acids on the cells. These results suggest that variations in the molar ratio of free fatty acid to albumin may influence the transport and utilization of other albumin-bound metabolites or drugs.

The binding capacity of human albumin for bilirubin and its significance in the significance in the pathogenesis of kernicterus.

The binding capacity of human albumin for bilirubin was studied by spectrophotometry and Sephadex G-25 gel filtration. It was found that one molecule of albumin could bind tightly only one molecule of bilirubin. While in contrast to earlier investigations, this corresponds well with clinical experience of development of kernicterus in newborns. Differences in the absorbance pattern at pH 7.4 and 8.3 are explained by a second molecule of bilirubin being able to form a dimer on the molecule already bound. This second molecule of bilirubin dissociates freely and is partly retained on a Sephadex column.

The protective effect of albumin on bilirubin toxicity on human fibroblasts.

The binding capacity of human albumin for bilirubin was studied using fibroblasts in tissue culture. Bilirubin alone in the growth media regularly killed the cells at concentrations above 35–52 μmol/1. The presence of albumin in the medium could prevent the toxic effects of bilirubin. It was shown that one molecule of albumin would completely detoxify only one molecule of bilirubin.

The determination of maximum bilirubin binding capacity of human albumin and serum by a calcium carbonate adsorption technique

It was demonstrated in this study that calcium carbonate selectively adsorbs unbound bilirubin from bilirubin-albumin solutions. A batch adsorption assay has been devised and used for studying bilirubin binding by albumin and serum preparations. Serum gave variable but consistently higher bilirubin/albumin molecular binding ratios than did purified albumin when tested in dilute solutions. In more concentrated solutions serum binding capacity decreased dramatically. Results obtained in studies testing serum and plasma protein fractions for their effect of bilirubin binding by albumin, suggested that an interaction of albumin with a high density lipoprotein influenced binding capacity.

Bestimmung der bindungskapazität des albumins für Evans-Blue (T 1824) mit der freien präparativen elektrophorese nach barrollier

Resume The binding capacity of human albumin for the azo dye T 1824 was investigated by free preparative electrophoresis according to Barrollier. One mol. of albumin can bind 11–12 mois. of Evans Blue at most. Globulins do not bind this dye. Paper and cellulose acetate strips can only be used as carrier for substances that are not adsorbed onto the cellulose fibres. They are not suitable as electrophoretic carriers for Evans Blue. The advantages of free preparative continuous electrophoresis lie in the fact that large quantities of substances can be separated and that the disturbances due to adsorption onto the carrier are avoided. Evans Blue can be used for labelling albumin in vivo and in vitro .