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Human albumin solution for resuscitation and volume expansion in critically ill patients. The Albumin Reviewers.

BACKGROUND: Human albumin solutions are used in a range of medical and surgical problems. Licensed indications are the emergency treatment of shock and other conditions where restoration of blood volume is urgent, burns, and hypoproteinaemia. Human albumin solutions are more expensive than other colloids and crystalloids. OBJECTIVES: To quantify the effect on mortality of human albumin and plasma protein fraction (PPF) administration in the management of critically ill patients. SEARCH STRATEGY: We searched the Cochrane Injuries Group trials register, Cochrane Controlled Trials Register, Medline, Embase and BIDS Index to Scientific and Technical Proceedings. Reference lists of trials and review articles were checked, and authors of identified trials were contacted. The search was last updated in November 1999. SELECTION CRITERIA: Randomised controlled trials comparing albumin/PPF with no albumin/PPF, or with a crystalloid solution, in critically ill patients with hypovolaemia, burns or hypoalbuminaemia. DATA COLLECTION AND ANALYSIS: We collected data on the participants, albumin solution used, mortality at the end of follow up, and quality of allocation concealment. Analysis was stratified according to patient type. We assessed publication bias using the regression test for funnel plot asymmetry. MAIN RESULTS: We found 30 trials meeting the inclusion criteria and reporting death as an outcome. There were 156 deaths among 1419 trial participants. For each patient category the risk of death in the albumin treated group was higher than in the comparison group. For hypovolaemia the relative risk of death following albumin administration was 1.46 (95% confidence interval 0.97 to 2.22), for burns the relative risk was 2.40 (1.11 to 5.19), and for hypoalbuminaemia the relative risk was 1.69 (1.07 to 2.67). The pooled relative risk of death with albumin administration was 1.68 (1.26 to 2.23). Overall, the risk of death in patients receiving albumin was 14% compared to 8% in the control groups, an increase in the risk of death of 6% (3% to 9%). These data suggest that for every 17 critically ill patients treated with albumin there is one additional death. REVIEWER'S CONCLUSIONS: There is no evidence that albumin administration reduces the risk of death in critically ill patients with hypovolaemia, burns or hypoalbuminaemia, and a strong suggestion that it may increase the risk of death. These data suggest that the use of human albumin in critically ill patients should be urgently reviewed and that it should not be used outside the context of a rigorously conducted randomised controlled trial.

Blood Proteins↗

Lung uptake to technetium-99m microaggregated human albumin in the rat after treatment with microaggregated human albumin or macroaggregated human albumin.

Marked accumulation in lung and liver of intravenously--injected 99mTc-microaggregated human serum albumin (liver imaging agent) was observed in rats pretreated with the subcutaneous injection of microaggregated or macroaggregated human serum albumin, whereas accumulation of 99mTc-microaggregated human serum albumin was observed only in the liver of rats pretreated with plain human serum albumin or in non-treated control rats. The activity of the intravenously-administered 99mTc-sulfur colloid was concentrated in the liver and spleen only and not in the lung, of rats previously treated with human serum albumin, microaggregated human serum albumin, or macroaggregated human serum albumin. These observations suggest that the specific accumulation of microaggregated human serum albumin in the lung of rats pretreated with aggregated albumin is due to rapid in vivo clumping of injected particles, possibly due to antigen-antibody reaction.

Animals↗

Affinity chromatography and affinity partition of human serum pre-albumin using immobilized Remazol Yellow GGL. Evidence that albumin increases binding of pre-albumin to the dye.

Pre-albumin was isolated from human serum or plasma by ammonium sulphate fractionation and by chromatography on dye-substituted Sephadex G-100 to a high degree of purity. The interaction of the pre-albumin with the dye Remazol Yellow GGL was studied in more detail by means of affinity partitioning in an aqueous two-phase system composed of dextran and poly(ethylene glycol). In the presence of dye-substituted poly(ethylene glycol) the partition coefficient of pre-albumin increases, indicating an interaction with the dye. Human serum albumin was found to enhance this interaction considerably. A similar effect was also shown by bovine albumin but not by egg albumin.

Ammonium Sulfate↗

Uptake of oleate from albumin solutions by rat liver. Failure to detect catalysis of the dissociation of oleate from albumin by an albumin receptor.

The hepatic removal of albumin-bound substances from plasma requires that they dissociate from albumin. Using indirect methods, we and others have proposed that dissociation may be catalyzed by interaction of albumin with the liver cell surface. This study looked for direct evidence of catalysis by comparing the rate of dissociation of oleate from albumin in vitro with the rate observed within the sinusoids of perfused rat liver. No evidence for catalysis was found. The rate of hepatic oleate removal from dilute albumin solutions did not exceed but instead closely paralleled the rate predicted from the in vitro dissociation rate constant (0.14s-1). These results suggest that under some conditions the liver can remove unbound material from the sinusoids faster than it can be replenished by dissociation from albumin, resulting in dissociation-limited removal. However, dissociation of oleate does not appear to be catalyzed by the liver.

Albumins↗

Albumin Cooperstown: a serum albumin variant with the same (313 Lys----Asn) mutation found in albumins in Italy and New Zealand.

Albumin Cooperstown is an electrophoretically fast genetic variant (alloalbumin) inherited in a family in New York State. To determine the structural change, we separated the alloalbumin from normal albumin A by "high-performance" liquid chromatography, reduced and carboxymethylated it, and cleaved it with CNBr. Isoelectric focusing showed that the substitution was in fragment CB4 (residues 299 to 329). The variant CNBr fragment from the albumin of two siblings was purified by liquid chromatography. Automated sequence analysis established the substitution of lysine-313 by asparagine (313 Lys----Asn), which corresponds to mutation of a single nucleotide base. The same substitution has recently been reported in albumin variants in Italy and New Zealand. This provides the first evidence for independent mutations at a single site within the structure of the mature albumin molecule. Because of the significance of albumin for study of protein evolution, clinical chemists are asked to be on the alert for cases of bisalbuminemia.

Amino Acid Sequence↗

Influence of albumin concentration, albumin species, pH and temperature on the stereoselectively different binding of (S)-(+)- and (R)-(-)-1-methyl-5-phenyl-5-propyl-barbiturate to serum albumin.

Using normal conditions (phosphate buffer pH 7.4, room temperature) and 1% human serum albumin (HSA), (R)-(-)-1-methyl-5-phenyl-5-propyl-barbiturate = (R)-(-)-1) as compared to (S)-(+)-1 was preferentially bound to albumin: the difference in the enantioselective binding was large (factor of 2) with low substrate concentrations and much smaller (factor of 1.3) with high substrate concentrations (range 5-620 micrograms/ml); with (S)-(+)-1 the decrease of the percent binding values observed with increasing concentrations was only moderately marked. The stereoselective binding difference ((R)-(-)- being greater than (S)-(+)-1) was always present independent of the albumin concentration (range 0.5-10%), the pH value (range 5-10) and the temperature (range 5-50 degrees C). Using 20 micrograms/ml as substrate concentration the stereospecific binding difference was large in solutions with low HSA concentration, in acidic and neutral pH range, and in experiments with low temperature. In contrast to HSA, bovine as well as rabbit serum albumin bound (S)-(+)-1 to a higher percentage than (R)-(-)-1; using rat serum albumin an enantioselective binding difference was not obtained. Taking into account for each of three mammalian albumins the respective number of binding classes and sites in each class, the affinity constant and total binding constant, it becomes evident that they bind (S)-(+)- and (R)-(-)-1 quantitatively differently in a species-specific manner.

Animals↗

Is albumin synthesis regulated by the colloid osmotic pressure? Effect of albumin and dextran on albumin and total protein synthesis in isolated rat hepatocytes.

In order to study the influence of the colloid osmotic pressure on albumin and total liver protein synthesis, rat hepatocytes were isolated by collagenase perfusion and incubated in Krebs-Ringer-buffer for 4 h. The colloid osmotic pressure produced by different bovine serum albumin (BSA) or dextran 60 concentrations varied from 3 to 80 mm Hg. A physiological colloid osmotic pressure of 20 mm Hg was obtained with 5.7 g BSA or 3.7 g dextran 60 per 100 ml of buffer. Albumin synthesis was measured by Laurell rocket immunoelectrophoresis. Total liver protein and total secretory protein synthesis were determined by the measurement of 1-14C-leucine incorporation. Albumin synthesis was not primarily regulated by the colloid osmotic pressure as was demonstrated by a lack of inhibition after addition of BSA. There was no significant influence of the oncotic pressure on the incorporation of 14C-leucine into total liver proteins. The incorporation into total secretory proteins was inhibited by an increasing colloid osmotic pressure, mediated either by BSA or dextran, suggesting an inhibition of the secretion of plasma proteins other than albumin.

Animals↗

Elevation of serum albumin by intrahepatic transplantation of albumin-producing cells does not correct quantitative abnormalities of non-albumin proteins in analbuminemic rats.

Nagase analbuminemic rats (NAR) show quantitative abnormalities of non-albumin serum proteins which could represent a compensatory response to the analbuminemia, although total serum protein levels are normal. When hyperplastic hepatic nodule (HPN) cells of F344 rats, which produce albumin, were infused into the portal vein of congenic analbuminemic rats (F344-alb) followed by treatment with the Solt and Farber dietary regimen, the transplanted cells grew within the livers, occasionally developing into hepatocellular carcinomas (HCC). In the recipient F344-alb, while serum albumin was considerably elevated, the total serum protein was also increased. Moreover, the abnormal pattern of serum proteins in NAR was unchanged by the elevation of albumin. These results indicate that the unique pattern of serum proteins in NAR is constitutive and cannot be corrected by a continuous increase in albumin levels.

Animals↗

The effect of albumin conformation on the binding of warfarin to human serum albumin. The dependence of the binding of warfarin to human serum albumin on the hydrogen, calcium, and chloride ion concentrations as studied by circular dichroism, fluorescence, and equilibrium dialysis.

The pH dependence of the binding of warfarin to human serum albumin has been studies by circular dichroism, fluorescence, and equilibrium dialysis. The pH dependences of the induced ellipticity and the fluorescent intensity of the warfarin . albumin complexes at low drug to protein ratios parallel the neutral to base transition, occurring in the protein over the pH range 6 to 9. Dialysis data show albumin to have a single high affinity site for warfarin over this pH range. This affinity is higher for the basic than for the neutral conformation. Calcium ions increase the high affinity constant of warfarin for albumin over the same pH region, by affecting the neutral to base transition. On the other hand, chloride ions reduce the induced ellipticity and the fluorescent intensity of the complexes at all pH investigated, the mechanism being primarily that of displacement of the drug from albumin.

Binding Sites↗

Permeability and mechanism of albumin, cationized albumin, and glycosylated albumin transcellular transport across monolayers of cultured bovine brain capillary endothelial cells.

We have measured the permeability and binding characteristics of bovine serum albumin (BSA), cationized BSA (cBSA), and glycosylated BSA (gBSA) to primary cultures of bovine brain capillary endothelial cells (BBCEC). These endothelial cells serve as an in vitro model to study the binding, uptake, and transcellular transport of small and large molecule flux across the blood-brain barrier. The rate of [3H]BSA flux across the cultured BBCEC monolayers grown onto polycarbonate membranes (5-microns pore size) was linear with increasing BSA concentration and the flux could be inhibited by temperature reduction to 0-4 degrees C. The maximal binding of [3H]BSA was 0.04 fmol/mg total cell protein and could not be inhibited by nonradiolabeled BSA. The binding of cBSA and gBSA was rapid and could be inhibited by nonradiolabeled cBSA or gBSA, respectively. The maximal amount bound was 1.8 fmol/mg total cell protein for cBSA and 17.4 fmol/mg total cell protein for gBSA. The dissociation constants (Kd's) were 27 +/- 13 and 3.7 +/- 1.1 nM for cBSA and gBSA, respectively. The flux rates of cBSA and gBSA across the endothelial cell monolayers were linear with respect to concentration and they were approximately seven times greater than those observed for BSA. Each of the proteins appeared on the antiluminal side of the endothelial cell monolayers primarily (90%) as intact protein as determined by trichloroacetic acid (TCA) precipitations and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). The results for BSA are similar to those observed for lucifer yellow, a fluid-phase endocytic marker.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗

Role of albumin arginyl sites in albumin-induced reduction of endothelial hydraulic conductivity.

We determined the effect of albumin on endothelial hydraulic conductivity (Lp) and the contributions of the positively charged arginyl and lysinyl residues of albumin in mediating the effect. Studies were made using monolayers of cultured sheep pulmonary artery endothelial cells grown to confluence on polycarbonate filters. Water flux was measured as transendothelial hydrostatic pressure was varied from 5 to 20 cm H2O. Lp was calculated from the slope of the relationship of water flux versus pressure. The Lp of endothelial monolayers perfused with albumin-free Hanks Balanced Salt Solution (HBSS) was compared to perfusion with HBSS containing either native albumin, or albumin in which the arginyl residues were modified by a condensation reaction with 1,2-cyclohexanedione (CHD-albumin), or albumin in which the lysinyl residues were modified by a substitution reaction with succinic anhydride (SC-albumin). Baseline Lp at 2.5 mg/ml native albumin was 1.6 +/- 0.1 X 10(-6) cm/s/cm H2O compared to the filter Lp after removing cells of 3.0 +/- 0.3 X 10(-4) cm/s/cm H2O. Endothelial Lp increased by 60% when albumin concentration was decreased from 2.5 mg/ml to 0.5 mg/ml (P less than 0.05), but did not change with an increase in concentration to 10 mg/ml. Albumin-free buffer and CHD-albumin increased endothelial Lp by 2.2 +/- 0.3-fold and 1.9 +/- 0.3-fold, respectively (P less than 0.05). All endothelial Lp values were restored to baseline when the native albumin concentration was returned to 2.5 mg/ml. Excess l-arginine (2 X 10(-3) M) inhibited the effect of native albumin and increased endothelial Lp 1.5 +/- 0.02-fold (P less than 0.05), but excess l-lysine (4 X 10(-3) in the presence of native albumin had no effect on Lp. None of the perfusates altered the filter Lp value. Neutral dextran (70 kD), in contrast to native albumin, had no effect on endothelial Lp. These results indicate that albumin reduces the hydraulic conductivity of endothelial monolayers in a concentration-dependent fashion and that the arginyl residues of albumin are required for the response. The effect of albumin may be mediated by a charge interaction of albumin with the endothelium.

Albumins↗

The kinetics in vivo of the synthesis of albumin-like protein and albumin in rats.

The incorporation of radioactivity into total protein, albumin-like protein and albumin in liver and into total protein and albumin in blood plasma, was studied for a time period of 2 h after intraportal injection of L-[1-14C]leucine. 1. In the liver, radioactivity began to increase in albumin-like protein before 2.5 min and in albumin at about 10 min after injection. In the plasma, radioactive albumin appeared at about 15 min. No albumin-like protein could be detected in the plasma. 2. Maximum radioactivity was reached first in albumin-like protein, then in hepatic albumin and finally in albumin in the blood-stream. The maximum specific radioactivity of albumin-like protein was 15 times higher than that of extravascular hepatic albumin which, in turn, was 6 times higher than that of plasma albumin. 3. The increase of radioactivity in albumin in the blood corresponded almost quantitatively to the decrease of radioactivity in albumin-like protein. 4. It is concluded that the albumin-like protein is the precursor of albumin in vivo. It is converted into albumin 5-6 min before the appearance of newly synthesized albumin in the blood-stream.

Animals↗

Inflammation and reduced albumin synthesis associated with stable decline in serum albumin in hemodialysis patients.

BACKGROUND: The concentration of albumin in serum is maintained by its rates of synthesis, catabolism, and distribution between vascular and extravascular compartments. Albumin synthesis is suppressed when there is inflammation or inadequate protein intake. This study was conducted to establish whether a decline in serum albumin of >0.3 g/dL was accompanied by a change in albumin synthesis and if so whether these changes were associated with increased levels of acute phase proteins and/or with a decrease in equilibrated normalized protein catabolic rate (enPCR). METHODS: Seventy-nine patients in the National Institutes of Health (NIH)-sponsored HEMO Study had baseline measurements of albumin synthesis (measured kinetically as the disappearance of [125]I human serum albumin), the serum concentrations of albumin, transferrin, C-reactive protein (CRP), alpha1 acid glycoprotein (alpha1AG), ceruloplasmin, interleukin-6 (IL-6), plus monthly measurements of enPCR. The plasma levels of all proteins and enPCR were measured regularly over 2 years or until serum albumin decreased by >0.3 g/dL on two sequential measurements. Albumin synthesis was measured a second time when serum albumin declined by >0.3 g/dL or after 2 years. RESULTS: Fifty-nine patients [21 with a significant decrease in serum albumin (decliners) and 38 with stable values of serum albumin] had albumin synthesis measured twice. A decline in albumin concentration and synthesis was associated with an increase in alpha1AG when data from all patients were analyzed as a group. In decliners, albumin synthesis decreased significantly but was unchanged in stable. Likewise, in decliners, IL-6, CRP, alpha1AG, and ceruloplasmin increased significantly but were unchanged in stable. enPCR was unchanged in both groups and was not associated with either changes in albumin level or synthesis in the whole group. CONCLUSION: A decrease in serum albumin of >0.3 g/dL that persists for a period of 6 weeks is associated a decrease in albumin synthesis. This response is associated with evidence of activation of the acute phase response (inflammation) but not with changes in enPCR. In well-dialyzed patients, inflammation is the principal cause of a decrease in serum albumin while protein intake plays an insignificant role.

Acute-Phase Reaction↗

Intra-venous albumin for preventing severe ovarian hyperstimulation syndrome.

BACKGROUND: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic condition that occurs after the administration of human menopausal gonadotrophin (hMG) with or without gonadotrophin releasing hormone (GnRH) agonists. OHSS is a threat to every woman undergoing ovulation induction and is potentially lethal in its severest form. Severe OHSS is characterised by growth of multiple large follicles with massive extravascular protein rich fluid shift. This may lead to hypovolaemia, haemoconcentration, oliguria, and electrolyte disturbance. Human albumin solutions are now used in the management of shock and other conditions in which restoration of blood volume is urgent, the acute management of burns, and clinical situations associated with hypoproteinaemia. Recently, a number of clinical trials with conflicting results have been reported in which albumin has been tested as a possible way for preventing the severe form of OHSS. OBJECTIVES: To review the effectiveness of human albumin administration in prevention of severe ovarian hyperstimulation syndrome. SEARCH STRATEGY: The Menstrual Disorders and Subfertility Group literature search strategy was used to identify randomised trials that had compared the use of human albumin with placebo or no treatment in the prevention of severe ovarian hyperstimulation syndrome. A diverse search strategy was employed, including handsearching of core journals from 1966 to the present, searching bibliographies of relevant trials, MEDLINE, EMBASE, PsychLIT and CINAHL databases, the MDSG specialised register, abstracts from North American and European meetings and contact with authors of relevant papers. SELECTION CRITERIA: Trials were included if they compared the effect of human albumin with placebo or no treatment on relevant outcomes. Only randomised controlled studies were included in this review. DATA COLLECTION AND ANALYSIS: Trials under consideration were evaluated for methodological quality and appropriateness for inclusion without consideration of their results. Relevant data were extracted independently by two reviewers using the standardized data extraction sheet. Validity was assessed in terms of method of randomization, completeness of follow-up, presence or absence of crossover and co-intervention. DATA SYNTHESIS: 2x2 tables were generated for all relevant outcomes. Odds ratios were calculated using the Peto modified Mantel-Haenszel technique. MAIN RESULTS: Meta-analysis of the three included trials demonstrated significant reduction in severe ovarian hyperstimulation syndrome on administration of human albumin (common odds ratio 0.1, 95% confidence interval 0.03 to 0.39). There was no evidence of an increase in the pregnancy rate (common odds ratio 1.69, 95% confidence interval 0.7 to 4.07). REVIEWER'S CONCLUSIONS: This review shows a clear benefit from administration of intra-venous albumin at the time of oocyte retrieval in prevention of severe OHSS in high-risk cases. However, the results of this review can not be regarded as conclusive as they are based on only three small trials. Further trials are urgently needed.

Female↗

Problems in serum albumin measurement and clinical significance of albumin microheterogeneity in cirrhotics.

OBJECTIVES: To clarify problems with the determination of serum albumin levels, the definition of hypoalbuminemia, and the implications of microheterogeneity of albumin, serum albumin was measured by using dye-binding methods and the authentic method (immunoassay) in patients with liver cirrhosis and healthy subjects. METHODS: We enrolled 103 patients with liver cirrhosis and 36 healthy subjects. Serum albumin levels were analyzed by immunoassay and the bromcresol green and bromcresol purple methods. Oxidized albumin and glycoalbumin were determined by high-performance liquid chromatography. RESULTS: In cirrhotic patients, serum albumin levels measured by the bromcresol green method was about 0.2 g/dL higher than that by immunoassay. Serum albumin levels measured by the bromcresol purple method also was higher in cirrhotic patients than those measured by immunoassay and varied widely. In addition, extensive variation was found across serum albumin levels determined by the bromcresol green method at individual institutions (five university hospitals) and those determined by immunoassay at a contract laboratory. The percentages of oxidized albumin and glycoalbumin within total serum albumin increased with progression of liver disease. Further, an increase in oxidized albumin led to an increase in the albumin level as measured by the bromcresol purple method. CONCLUSION: These results show that adequate assessment of the pathophysiology and prognosis of patients with liver cirrhosis and the efficacy of treatment is not possible with dye-binding methods for determination of serum albumin. Further, the conventional definition of hypoalbuminemia as a serum albumin level of 3.5 g/dL or lower should be reconsidered, and the clinical implications of qualitative changes in albumin should be investigated in consideration of the microheterogeneity of albumin, such as oxidized albumin and glycoalbumin.

Aged↗

Immunohistochemical localization of albumin and in situ hybridization of albumin mRNA.

Hepatocytes actively involved in albumin synthesis were identified by immunohistochemical method. In sections of perioidate-lysine-2 per cent (w/v) paraformaldehyde fixed normal rat liver, albumin was detected in all hepatocytes. At the ultrastructural level, albumin was localized in the rough endoplasmic reticulum and in Golgi complexes located near the nucleus in only a small subpopulation of hepatocytes, while all other hepatocytes contained albumin only in Golgi complexes located near the bile canaliculi. Stimulation of albumin synthesis by puromycin aminonucleoside-induced nephrosis resulted in an altered intracellular distribution of albumin at the light microscopic level. When examined at the ultrastructural level, albumin was localized in the rough endoplasmic reticulum as well as in Golgi complexes located near the nucleus in nearly all these hepatocytes. Hepatocytes with the potential to synthesize albumin were identified by in situ hybridization of albumin mRNA. In sections of 0.1 per cent (v/v) glutaraldehyde perfusion fixed normal rat liver, albumin mRNA was detected in the cytoplasm of only a few hepatocytes scattered throughout the lobule. Following stimulation of albumin synthesis by the induction of nephrosis, albumin mRNA was detected in the cytoplasm of the hepatocytes. The source of albumin in those hepatocytes which lacked albumin mRNA was identified in analbuminemic rats injected with rat albumin. At 6 h post injection, the light microscopic distribution of albumin in the liver of these animals was virtually indistinguishable from that in normal rat liver. At the ultrastructural level, injected albumin was localized in lysosomes and in Golgi complexes located near the bile canaliculi.

Animals↗