Showing papers on "Albumin published in 2003"
TL;DR: In this paper, a low molecular weight (LMW) serum proteome was extracted from serum and analyzed using microcapillary reversed-phase liquid chromatography coupled with electrospray ionization tandem mass spectrometry.
830 citations
TL;DR: These results affirm the hypothesis that the major histocompatibility complex–related Fc receptor protects albumin from degradation just as it does IgG, prolonging the half-lives of both.
Abstract: The inverse relationship between serum albumin concentration and its half-life suggested to early workers that albumin would be protected from a catabolic fate by a receptor-mediated mechanism much like that proposed for IgG. We show here that albumin binds FcRn in a pH dependent fashion, that the lifespan of albumin is shortened in FcRn-deficient mice, and that the plasma albumin concentration of FcRn-deficient mice is less than half that of wild-type mice. These results affirm the hypothesis that the major histocompatibility complex-related Fc receptor protects albumin from degradation just as it does IgG, prolonging the half-lives of both.
576 citations
TL;DR: Perfluorooctane sulfonic acid in serum is in general bound to albumins, and it is unlikely that PFOS would cause displacement of hormones from serum proteins in wildlife.
Abstract: Perfluorooctane sulfonic acid (PFOS) accumulates in the liver and blood of exposed organisms. The potential for these surfactant molecules to interfere with hormone/protein interactions in blood is of concern given the importance of these interactions. The PFOS binding to serum proteins was investigated by assessing its ability to displace a variety of steroid hormones from specific binding proteins in the serum of birds and fishes. Perfluorooctane sulfonic acid had only a weak ability to displace estrogen or testosterone from carp serum steroid binding proteins. Displacement of cortisone in avian sera occurred at relatively low PFOS concentrations. Corticosterone displacement potency increased with chain length, and sulfonic acids were more potent than carboxylic acids. The PFOS concentrations estimated to cause these effects were 320 μM or greater, equivalent to serum concentrations greater than 160 mg/L. Using mass spectrometry and direct in vitro binding assays, PFOS was demonstrated to bind strongly to bovine serum albumin (BSA) in a 1:1 stoichiometric ratio. It appears that PFOS in serum is in general bound to albumins. Concentrations of PFOS required to saturate albumin would be in excess of 50 to 100 mg/L. Based on current environmental concentrations, it is unlikely that PFOS would cause displacement of hormones from serum proteins in wildlife.
558 citations
TL;DR: The immunoaffinity‐based protein subtraction chromatography (IASC) described here removes multiple proteins present in plasma and serum in high concentrations effectively and reproducibly and facilitates automated chromatographic processing of plasma samples in high throughput, desirable in proteomic disease marker discovery projects.
Abstract: In order to discover novel protein markers indicative of disease processes or drug effects, the proteomics technology platform most commonly used consists of high resolution protein separation by two-dimensional electrophoresis (2-DE), mass spectrometric identification of proteins from stained gel spots and a bioinformatic data analysis process supported by statistics. This approach has been more successful in profiling proteins and their disease- or treatment-related quantitative changes in tissue homogenates than in plasma samples. Plasma protein display and quantitation suffer from several disadvantages: very high abundance of a few proteins; high heterogeneity of many proteins resulting in long charge trains; crowding of 2-DE separated protein spots in the molecular mass range between 45-80 kD and in the isoelectric point range between 4.5 and 6. Therefore, proteomic technologies are needed that address these problems and particularly allow accurate quantitation of a larger number of less abundant proteins in plasma and other body fluids. The immunoaffinity-based protein subtraction chromatography (IASC) described here removes multiple proteins present in plasma and serum in high concentrations effectively and reproducibly. Applying IASC as an upfront plasma sample preparation process for 2-DE, the protein spot pattern observed in gels changes dramatically and at least 350 additional lower abundance proteins are visualized. Affinity-purified polyclonal antibodies (pAbs) are the immunoaffinity reagents used to specifically remove the abundant proteins such as albumin, immunoglobulin G, immunoglobulin A, transferrin, haptoglobin, alpha-1-antitrypsin, hemopexin, transthyretin, alpha-2-HS glycoprotein, alpha-1-acid glycoprotein, alpha-2-macroglobulin and fibrinogen from human plasma samples. To render the immunoaffinity subtraction procedure recyclable, the pAbs are immobilized and cross-linked on chromatographic matrices. Antibody-coupled matrices specific for one protein each can be pooled to form mixed-bed IASC columns. We show that up to ten affinity-bound plasma proteins with similar solubility characteristics are eluted from a mixed-bed column in one step. This facilitates automated chromatographic processing of plasma samples in high throughput, which is desirable in proteomic disease marker discovery projects.
356 citations
TL;DR: It is concluded that glycation induces refolding of initially globular albumin into amyloid fibrils comprising cross-β structure, which would explain how glycated ligands and amyloids ligands can bind to the same multiligand “cross- β structure” receptors and to tPA.
269 citations
TL;DR: In conclusion, albumin is a strong stimulus for tubular IL-8 expression, which occurs via NF-kappaB-dependent pathways through PKC activation and ROS generation.
Abstract: Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the stimuli for leukocyte recruitment are not fully understood. IL-8 is a potent chemokine produced by proximal tubular epithelial cells (PTECs). Whether nephrotic proteins stimulate tubular IL-8 expression remains unknown. Acute exposure of human PTECs to albumin induced IL-8 gene and protein expression time- and dose-dependently. Apical albumin predominantly stimulated basolateral IL-8 secretion. Electrophoretic mobility shift assay demonstrated nuclear translocation of NF-κB, and the p65/p50 subunits were activated. NF-κB activation and IL-8 secretion were attenuated by the NF-κB inhibitors pyrrolidine dithiocarbamate and cell-permeable peptide. Albumin upregulated intracellular reactive oxygen species (ROS) generation, while exogenous H2O2 stimulated NF-κB translocation and IL-8 secretion. Albumin-induced ROS generation, NF-κB activation, and IL-8 secretion were endocytosis- and PKC-dependent as these downstream events were abrogated by the PI3K inhibitors LY294002 and wortmannin, and the PKC inhibitors GF109203X and staurosporin, respectively. In vivo, IL-8 mRNA expression was localized by in situ hybridization to the proximal tubules in nephrotic kidney tissues. The intensity of IL-8 immunostaining was higher in nephrotic than non-nephrotic subjects. In conclusion, albumin is a strong stimulus for tubular IL-8 expression, which occurs via NF-κB–dependent pathways through PKC activation and ROS generation.
267 citations
TL;DR: In this article, the pharmacokinetics of albumin and methotrexate were examined in a mouse model of rheumatoid arthritis and the efficacy of MTX and MTX-HSA in arthritic mice were studied.
Abstract: We reported recently that albumin is a suitable drug carrier for targeted delivery of methotrexate (MTX) to tumors. Due to pathophysiological conditions in neoplastic tissue, high amounts of albumin accumulate in tumors and are metabolized by malignant cells. MTX, covalently coupled to human serum albumin (MTX-HSA) for cancer treatment, is currently being evaluated in phase II clinical trials. Because synovium of patients with rheumatoid arthritis (RA) shares various features observed also in tumors, albumin-based drug targeting of inflamed joints might be an attractive therapeutic approach. Therefore, the pharmacokinetics of albumin and MTX in a mouse model of arthritis was examined. Additionally, uptake of albumin by synovial fibroblasts of RA patients and the efficacy of MTX and MTX-HSA in arthritic mice were studied. The results show that when compared with MTX, significantly higher amounts of albumin accumulate in inflamed paws, and significantly lower amounts of albumin are found in the liver and the kidneys. The protein is metabolized by human synovial fibroblasts in vitro and in vivo. MTX-HSA was significantly more effective in suppression of the onset of arthritis in mice than was MTX. In conclusion, albumin appears to be a suitable drug carrier in RA, most likely due to effects on synovial fibroblasts, which might increase therapeutic efficacy and reduce side effects of MTX.
226 citations
TL;DR: In conclusion, albumin is more effective than saline in the prevention of PICD and is a valid alternative to albumin when less than 6 L of ascitic fluid is evacuated.
224 citations
TL;DR: Using monoclonal antibodies against human serum albumin (HSA) to develop an immunoaffinity resin that is effective in the removal of both full-length HSA and many of the HSA fragments present in serum shows markedly better performance than dye-based resins in terms of both the efficiency and specificity of albumin removal.
222 citations
TL;DR: Analysis of x-ray crystal structures of human albumin suggests that fatty acid binding to site 2 triggers a spring-lock mechanism, which disengages the upper and lower halves of the metal site, which provides a possible mechanism whereby fatty acids could influence the transport and delivery of zinc in blood.
Abstract: Albumin is the major transport protein in blood for Zn(2+), a metal ion required for physiological processes and recruited by various drugs and toxins. However, the Zn(2+)-binding site(s) on albumin is ill-defined. We have analyzed the 18 x-ray crystal structures of human albumin in the PDB and identified a potential five-coordinate Zn site at the interface of domains I and II consisting of N ligands from His-67 and His-247 and O ligands from Asn-99, Asp-249, and H(2)O, which are the same amino acid ligands as those in the zinc enzymes calcineurin, endonucleotidase, and purple acid phosphatase. The site is preformed in unliganded apo-albumin and highly conserved in mammalian albumins. We have used (111)Cd NMR as a probe for Zn(2+) binding to recombinant human albumin. We show that His-67 --> Ala (His67Ala) mutation strongly perturbs Cd(2+) binding, whereas the mutations Cys34Ala, or His39Leu and Tyr84Phe (residues which may H-bond to Cys-34) have no effect. Weak Cl(-) binding to the fifth coordination site of Cd(2+) was demonstrated. Cd(2+) binding was dramatically affected by high fatty acid loading of albumin. Analysis of the x-ray structures suggests that fatty acid binding to site 2 triggers a spring-lock mechanism, which disengages the upper (His-67Asn-99) and lower (His-247Asp-249) halves of the metal site. These findings provide a possible mechanism whereby fatty acids (and perhaps other small molecules) could influence the transport and delivery of zinc in blood.
194 citations
TL;DR: The present findings indicate that the effect of glycation can be partly explained by blockage of the positive charges of lysine at positions 199, 439 and 525.
TL;DR: As the binding affinity of plasma albumin for bilirubin decreases strikingly as albumin concentration increases, previously reported Bf values were underestimated.
Abstract: Revised concepts of bilirubin encephalopathy have been revealed by studies of bilirubin toxicity in cultured CNS cells and in congenitally jaundiced Gunn rats. Bilirubin neurotoxicity is related to the unbound (free) fraction of unconjugated bilirubin (Bf), of which the dominant species at physiological pH is the protonated diacid, which can passively diffuse across cell membranes. As the binding affinity of plasma albumin for bilirubin decreases strikingly as albumin concentration increases, previously reported Bf values were underestimated. Newer diagnostic tests can detect reversible neurotoxicity before permanent damage occurs from precipitation of bilirubin (kernicterus). Early toxicity can occur at Bf only modestly above aqueous saturation and affects astrocytes and neurons, causing mitochondrial damage, resulting in impaired energy metabolism and apoptosis, plus cell-membrane perturbation, which causes enzyme leakage and hampers transport of neurotransmitters. The concentrations of unbound bilirubin in the cerebro-spinal fluid and CNS cells are probably limited mainly by active export of bilirubin back into plasma, mediated by ABC transporters present in the brain capillary endothelium and choroid plexus epithelium. Intracellular bilirubin levels may be diminished also by oxidation, conjugation and binding to cytosolic proteins. These new concepts may explain the varied susceptibility of neonates to develop encephalopathy at any given plasma bilirubin level and the selective distribution of CNS lesions in bilirubin encephalopathy. They also can suggest better strategies for predicting, preventing and treating this syndrome.
TL;DR: Data point to a rapid and highly coordinated regulation of mitochondrial protein expression that occurs during the heart adaptation to diabetes, as shown in rats treated with streptozotocin.
TL;DR: In this article, the ability of fatty acids to interact with peroxisome proliferator-activated receptors (PPAR) in primary cultures of human proximal tubule cells was examined.
Abstract: In nephrotic syndrome, large quantities of albumin enter the kidney tubule. This albumin carries with it a heavy load of fatty acids to which the proximal tubule cells are exposed at high concentration. It is postulated that exposure to fatty acids in this way is injurious to proximal tubule cells. This study has examined the ability of fatty acids to interact with peroxisome proliferator-activated receptors (PPAR) in primary cultures of human proximal tubule cells. Luciferase reporter assays in transiently transfected human proximal tubule cells were used to show that albumin bound fatty acids and other agonists activate PPARgamma in a dose-dependent manner. One of the consequences of this activation is apoptosis of the cells as determined by changes in cell morphology, evidence of PARP cleavage, and appearance of DNA laddering. Overexpression of PPARgamma in these cells also results in enhanced apoptosis. Both fatty acid-induced PPAR activation and apoptosis in these cells can be blocked by PPAR response element decoy oligonucleotides. Activation of PPARgamma by the specific agonist PGJ(2) is associated with inhibition of cell proliferation, whereas activation by albumin bound fatty acids is accompanied by increased proliferation. However, the net balance of apoptosis/proliferation favors deletion of cells. These results implicate albumin-bound fatty acids as important mediators of tubular injury in nephrosis and provide fresh impetus for pursuit of lipid-lowering strategies in proteinuric renal disease.
TL;DR: It is demonstrated that SCCA1 can be detected by LC-MS in patient serum following depletion of albumin and gamma-globulins thus opening the possibility of screening patient sera for other, so far unknown, tumor markers.
01 Jan 2003
TL;DR: The casein and non-casein fractions are heterogeneous; casein includes four principal primary proteins (gene products), αs1-, αs2-, β- andκ-caseins, and several minor proteins, while the noncasein fraction includes β-lactoglobulin, α-Lactalbumin, blood serum albumin, immunoglobulins as mentioned in this paper.
Abstract: Bovine milk contains ~13% solids, which include fat, lactose, protein, and organic and inorganic salts. Normal milk contains ~3.5 g total protein per 100 ml which falls into two main categories based on solubility at pH 4.6 at >~8°C. Under these conditions ~80% of the total nitrogen precipitates and this fraction is referred to as casein, while ~20% remains soluble in the serum or whey, ~15% being whey proteins with the remainder being non- protein nitrogenous components. As discussed in Chapter 1, both the casein and non-casein fractions are heterogeneous; casein includes four principal primary proteins (gene products), αs1-, αs2-, β- andκ-caseins, and several minor proteins, while the non-casein fraction includes β-lactoglobulin, α-lactalbumin, blood serum albumin, immunoglobulins. casein-derived proteose peptones, several minor proteins, including lactotransferrin, and several enzymes. The characteristics of the caseins and whey proteins differ very significantly (Table 26.1).
TL;DR: The results suggest that BCAAs, especially leucine, promote the production of albumin in rat primary hepatocytes through an mTOR signal transduction system.
TL;DR: It is concluded that serum CRP is a poor marker of acute inflammation in the rat in comparison with serum Hp and plasma Fbgn, while serum HP is shown to be the most sensitive and useful marker of acutely inflammation.
Abstract: C-reactive protein (CRP), haptoglobin (Hp) and fibrinogen (Fbgn) are acute phase reactants (APRs), the blood levels of which increase during acute inflammation. However, although the levels of these APRs are used to monitor inflammation in man, their usefulness and sensitivity as markers of inflammation in rodents are less clear. We therefore wished to evaluate, in a comparative fashion, a prototype immunoassay for serum CRP, a commercial assay for serum Hp, and an automated assay for Fbgn, using a model of acute inflammation in the rat. Additionally, pro-inflammatory cytokines and serum protein fractions were also measured. The model of inflammation used was the intraperitoneal injection of Freund's complete adjuvant (FCA). In a concluding experiment, findings with Hp in the FCA rat model were validated in a toxicologically relevant study involving the induction of acute hepatic inflammation using the model hepatotoxicant carbon tetrachloride (CCl4). Female Wistar Han rats were treated with a single injection of FCA in a dose–response study (1.25–10.0 ml/kg, sampling at 36 h) and two time-course studies (over 40 h and 21 days). In a final experiment, rats were dosed with CCl4 at 0.8 ml/kg and sampled over a 17-day period. In FCA and CCl4 experiments, serum/plasma was prepared and tissues taken at autopsy for histological assessment (CCl4 study only). In the dose–response study, serum CRP, Hp and plasma Fbgn were increased at all FCA dose levels at 36 h post-dosing. Serum α2 and β1 globulin fractions were also increased, while albumin levels were decreased. In the 40-h time-course study, CRP levels peaked at 25–40 h post-dosing, to approximately 120% of control (as 100%). Hp levels increased to a maximum at 25 and 40 h post-dosing with values greater than 400% of control, and α2 and β1 globulin fractions peaked at 30 and 40 h post-dosing to 221 and 187% of control, respectively. Increased serum interleukin-6 (IL-6) and interleukin-1β (IL-1β) levels peaked at 20 h (11-fold) and 25 h (19-fold), respectively. In a 21-day time-course study, no increased CRP levels were measured despite elevated levels of Hp, which peaked at 36 h (approximately 7-fold above control), and remained elevated up to 21 days. IL-6 and IL-1β levels peaked at 12 h (19-fold) and 24 h (28-fold), respectively. Liver histopathology of animals treated with CCl4 showed centrilobular hepatocellular degeneration and necrosis (most significant at 36 h) with an inflammatory response (most significant at 48 h). Resolution of the lesion was complete by 4 days post-dosing. Serum alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase levels peaked at 36 h post-dosing. Hp levels increased maximally at 48 h (426% of control). We conclude that serum CRP is a poor marker of acute inflammation in the rat in comparison with serum Hp and plasma Fbgn. Between Hp and Fbgn, serum Hp is shown to be the most sensitive and useful marker of acute inflammation.
TL;DR: High performance liquid chromatography was used to provide a more accurate measurement of albuminuria compared with radioimmunoassay (RIA) on 97 fresh urine samples from patients with diabetes, showing that to determine microalbuminuria accurately, there is a need to assess urinary total intact albumin, rather than simply immunoreactive albumin.
TL;DR: Inclusion of recombinant albumin and hyaluronan in culture media facilitates the development of physiological defined culture conditions and has implications for both research and commercial applications where defined reproducible conditions are desirable.
Abstract: Recombinant albumin can be used to supplement culture medium for the maturation and fertilization of bovine oocytes and subsequent embryo development to the blastocyst stage. Recombinant albumin was able to support blastocyst development at rates equivalent to that of bovine serum albumin (BSA) supplemented media. Supplementation of media containing recombinant albumin and citrate stimulated blastocyst expansion. Culture with recombinant albumin and citrate significantly increased the ability of the resultant blastocysts to re-expand and hatch following cryopreservation. The further addition of the glycosaminoglycan hyaluronan to the culture medium containing either BSA or recombinant albumin also increased the ability of blastocysts to survive cryopreservation. Inclusion of recombinant albumin and hyaluronan in culture media facilitates the development of physiological defined culture conditions. For bovine embryos this has implications for both research and commercial applications where defined reproducible conditions are desirable.
TL;DR: The binding stoichiometry of allopurinol–mercaptopurine–serum albumin complex was studied and the character of the binding between studied quencher and human and bovine serum albumin was estimated.
TL;DR: The Gradiflow, a preparative electrophoresis system, has been used to deplete human plasma of the highly abundant protein albumin under native and denatured conditions and the identification of the protein that lies beneath albumin to be C4B‐binding protein α chain was confirmed.
Abstract: Analysis of complex protein samples by two-dimensional electrophoresis (2-DE) is often more difficult in the presence of a few predominant proteins. In plasma, proteins such as albumin mask proteins of lower abundance, as well as significantly limiting the amount of protein that can be loaded onto the immobilized pH gradient strip. In this paper the Gradiflow, a preparative electrophoresis system, has been used to deplete human plasma of the highly abundant protein albumin under native and denatured conditions. A three step protocol incorporating a charge separation to collect proteins with an isoelectric point greater than albumin and two size separations to isolate proteins larger and smaller than albumin, was used. When the albumin depleted fractions were analysed on pH 3–10 2-DE gels, proteins that were masked by albumin were revealed and proteins not seen in the unfractionated plasma sample were visualised. Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry analysis confirmed the identification of the protein that lies beneath albumin to be C4B-binding protein α chain. The liquid fractions from the Gradiflow separations were also analysed by liquid chromatography-tandem mass spectrometry to confirm the proteins were separated according to their size and charge mobility in an electric field.
TL;DR: The results suggest that the long term exposure of various pesticides on sprayers of grape garden affect liver, heme biosynthesis and decrease serum cholinesterase.
Abstract: A total of 85 healthy male pesticide sprayers in grape garden exposed to different class of pesticides for 3 to 10 years were compared with 75 controls matched for age with respect to serum cholinesterase, serum total protein, albumin, AST, ALT, hematological parameters such as Hb, Hct, RBC and serum lipid peroxidation. Serum lipid peroxidation was estimated in the form of thiobarbituric acid reactive substances (TBARS) produced. Significant decrease was observed in serum cholinesterase, serum total proteins, albumin and hematological parameters viz. Hb, Hct and RBC. Significant increase in lipid peroxidation, AST, ALT, was observed in exposed group when compared with control. These results suggest that the long term exposure of various pesticides on sprayers of grape garden affect liver, heme biosynthesis and decrease serum cholinesterase.
TL;DR: In this article, the authors analyzed albumin and creatinine levels as outcome variables and their association with C-reactive protein (CRP), equilibrated normalized protein catabolic rate (enPCR), and serum bicarbonate level as independent variables from laboratory data obtained from patients in the Hemodialysis Study.
TL;DR: The present results suggest that binding to plasma proteins causes a drastic decrease of NAMI-A bioavailability and a subsequent reduction of its biological activity, implying that association to Plasma proteins essentially represents a mechanism of drug inactivation.
Abstract: NAMI-A is an innovative ruthenium(III) complex with a very encouraging preclinical profile of metastasis inhibition, which is undergoing initial phases of clinical trials. To assess the pharmacological relevance of the drug fraction associated to plasma proteins, adducts of NAMI-A with either serum albumin or serum transferrin were prepared and their biological effects tested in vitro and in vivo. Specifically, adducts of NAMI-A with either serum albumin or serum transferrin, prepared and characterized at a ruthenium-to-protein molar ratio of 4:1, were evaluated in vitro on the KB human tumor cell line and in vivo on the MCa mammary carcinoma tumor. The effects of NAMI-A/protein adducts on cell viability and on cell cycle progression were found to be far smaller than those produced by free NAMI-A. GFAAS measurements point out that the amount of ruthenium that gets into cells is drastically reduced when NAMI-A is presented in its protein-bound form. In vivo use of NAMI-A adducts with albumin and transferrin resulted markedly less effective on lung metastasis reduction, than free NAMI-A. Overall, the present results suggest that binding to plasma proteins causes a drastic decrease of NAMI-A bioavailability and a subsequent reduction of its biological activity, implying that association to plasma proteins essentially represents a mechanism of drug inactivation.
TL;DR: In conclusion, angiotensin II blockade restored albumin reabsorption via amelioration of megalin expression in the proximal tubules of early stage diabetic rats.
Abstract: The kidney plays an important role in protein metabolism. The albumin reabsorption in the proximal tubule is disturbed in the early stage of diabetic nephropathy. We evaluated the effects of angiotensin converting enzyme inhibitor (ACEI) and angiotensin II type 1 receptor blocker (ARB) on albumin reabsorption and expression of megalin, an endocytosis receptor for albumin, in proximal tubules of streptozotocin (STZ)-induced diabetic-rats. Diabetic rats at the second week after STZ injection were treated with quinapril (3mg/kg/day) or candesartan (0.05mg/kg/day) for 2 weeks. The tubular reabsorption of fluorescein isothiocyanate (FITC)-labeled albumin was evaluated by immunogold electron microscopy, and megalin expression was investigated by immunohistochemistry and Western blotting. Reabsorption of FITC-labeled albumin and megalin expression were prominently inhibited in the proximal convoluted tubules of diabetic rats compared to the controls. Both quinapril and candesartan restored albumin reabsorption in the proximal tubule due to normalization of megalin expression. Urinary albumin excretion was significantly reduced by both ACEI and ARB treatment. Angiotensin II infusion decreased megalin expression and albumin reabsorption in the proximal tubule. In conclusion, angiotensin II blockade restored albumin reabsorption via amelioration of megalin expression in the proximal tubules of early stage diabetic rats. (Hypertens Res 2003; 26: 413-419)
TL;DR: Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) was used in this study to characterize human serum albumin (HSA) adsorption on two different polyearbonate surfaces: a native membrane and a hydrophilic treated one.
Abstract: The adsorption of proteins at biomaterial surfaces depends on the properties of the substrate and can cause changes in protein conformation. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) was used in this study to characterize human serum albumin (HSA) adsorption on two different polyearbonate surfaces: a native membrane and a hydrophilic treated one. The amount adsorbed as a function of HSA concentration in solution was compared for the two substrates. The treated membrane was found to have a lower affinity for albumin than the native one. Principal component analysis was used to reveal changes in albumin conformation as a function of albumin concentration in solution and to compare the conformations adopted on the two substrates. The albumin conformation was different on the two substrates, and in every case, the protein lost its native structure. A correlation was found between the amount adsorbed on the hydrophilic surface and the albumin conformation on this surface.
TL;DR: A three-way interaction among fibrinogen, Ig, and albumin that synergistically induces RBC aggregation in plasma is suggested to help predict clinically important phenomena related to R BC aggregation, such as thrombotic complications of Ig infusion.
Abstract: Therapeutic administration of immunoglobulins (Ig) has the potential to precipitate thrombotic events. This phenomenon may be explained by red blood cell (RBC) aggregation, which can be potentiated...
TL;DR: The results show that well known protein coupling techniques can be used for the preparation of protein layers with well controlled thickness and the layers possess low contact activation of blood plasma and induce different release of TNF-α and IL-10 in monocyte cultures.
TL;DR: Results, indicating a flow of quercetin from albumin to haemoglobin, and vice versa, are consistent with the possibility that human RBC play a pivotal role in the distribution and bioavailability of circulating flavonoids.
Abstract: Quercetin is rapidly and avidly taken up by human red blood cells (RBC) via a passive diffusion mechanism, driven by flavonoid binding to haemoglobin and resulting in an almost quantitative accumulation of the flavonoid. Heamoglobin-free resealed ghosts accumulated quercetin exclusively in the membrane fraction. Cell-associated quercetin was biological active and could be quantitatively utilised to support the reduction of extracellular oxidants mediated by a transplasma-membrane oxido-reductase. Additional experimental evidence revealed that quercetin uptake declined in the presence of albumin and that, under these conditions, the amount of cell-associated quercetin is enhanced by increasing the RBC number. Quercetin release from flavonoid-preloaded RBC was observed only in the presence of albumin (or in human plasma) and this response was progressively inhibited upon incubation in solutions containing albumin previously exposed to increasing concentrations of quercetin and cleared of the unbound fraction of the flavonoid. Furthermore, exposure to quercetin pre-saturated albumin promoted accumulation of the flavonoid in fresh RBC and this response was a direct function of the extent of albumin saturation. These results, indicating a flow of quercetin from albumin to haemoglobin, and vice versa, are therefore consistent with the possibility that human RBC play a pivotal role in the distribution and bioavailability of circulating flavonoids.