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At least 253 records · Page 14Linked to original sources
PubMed1988

Immunoturbidimetry of urinary albumin: prevention of adsorption of albumin; influence of other urinary constituents.

I describe a simple, rapid immunoturbidimetric assay for low concentrations of albumin in urine (2 to 260 mg/L). However, in this assay, the human serum albumin (HSA) in the standards binds nonspecifically to the polystyrene or glass tubes. This nonspecific binding cannot be prevented by adding bovine serum albumin (BSA) to standards, because the anti-HSA antibody cross reacts with BSA. Adding Triton X-100 (1 mL/L) to standards effectively prevents this nonspecific binding of HSA from standards to both polystyrene and glass tubes. High concentrations of compounds found in urine from normal and diabetic subjects do not interfere with this assay if pH extremes can be avoided. The between-day CV is 4.8% at means = 18.8 mg/L and 2.0% at means = 183.1 mg/L. Measurements by this immunoturbidimetric method (y) correlate well with those obtained by a radioimmunoassay (x): y = 1.078x - 0.141 mg/L (n = 98; r = 0.984) and with those obtained by a radial immunodiffusion method (x'): y = 1.026x' - 0.117 mg/L (n = 98; r = 0.983). Urinary excretion of albumin by 25 healthy, nondiabetic subjects was less than 8 micrograms/min.

Adsorption↗
PubMedDate not supplied

[The effect of the medium on the functional and structural properties of serum albumins. III. Relation between the N-F1-, F1-F2- and F2-E transitions of human serum albumin and temperature and ionic strength].

Using fluorescence parameters of tryptophanyl and bound ANS, the acid-induced structural transitions of defatted monomeric human serum albumin were measured as pH-dependences from 6 to 2.5 in the wide range of temperature (10 to 45 degrees C) and ionic strength (from 0.001 to 0.2 M NaCl or 0.067 M Na2SO4). Temperature rise and decrease in ionic strength value result in the splitting of the N-F-transition onto two stages, N-F1 and F1-F2. The N-F1-transition is accompanied by the blue shift of tryptophanyl and ANS fluorescence spectra and increase in the ANS emission yield. The F1-F2-stage is manifested in an additional blue spectral shift and a sharp drop of the ANS emission yield, which is shown to be due to the lowering of albumin affinity for the dye. In the acidic-extension stage (F2-E), the spectra undergo a red shift which means that the nanosecond dipole relaxation of protein groups and bound water becomes faster. In the F2 from, the albumin affinity for ANS is significantly lowered; the association constant of the primary binding site is lower by an order of quantity and two secondary sites are practically disappeared. The complex effect of temperature, ionic strength and pH changes on the properties of ANS-binding sites is considered as a model of possible control influences of these factors upon the albumin transport of amphiphilic anions in organism.

Binding Sites↗
PubMed1982

Quantitation of estrogen effect on Xenopus laevis albumin mRNA levels by hybridization to cloned albumin cDNA.

The isolation and characterization of a Xenopus laevis albumin cDNA clone, pUN18, is described. This clone was identified as a X. laevis albumin cDNA clone by hybridization-mRNA selection-translation and by other techniques. The clone was used in hybridizations to determine the effect of estrogen on albumin synthesis in livers of male X. laevis. We find that albumin mRNA levels remain relatively constant during the massive induction of vitellogenin mRNA synthesis and vitellogenin secretion which follow administration of estrogen to male X. laevis.

Albumins↗
PubMed1997

Microalbuminuria and borderline-increased albumin excretion determined with a centrifugal analyzer and the Albumin Blue 580 fluorescence assay.

We report a new automated fluorescence assay for determination of albumin in urine. The dye Albumin Blue 580 specifically binds to albumin with exhibition of strong red fluorescence. The albumin concentration is calculated from emission intensity at 616 nm (excitation at 590 nm) and a calibration curve. Two Cobas Fara programs cover working ranges of 2-200 and 1-50 mg/L with detection limits of 1.4 and 0.4 mg/L, respectively. Within-run CVs (n = 10) ranged from 1.7% (189 mg/L) to 8.9% (7.2 mg/L) for 2-200 mg/L and from 2.9% (43.3 mg/L) to 5.7% (2.3 mg/L) for the 1-50 mg/L range. A test of urine samples (n = 100) submitted to routine analysis gave results that agreed well with those by the Behring nephelometric assay: AB 580 = 0.922 (+/-0.010) BNA + 4.16 (+/-0.78). No interference was detected from other urine components, including several proteins and 46 drugs. The high specificity and sensitivity make the method ideal for determination of microalbuminuria. In addition, the method is fast, inexpensive, and well-suited for clinical laboratory application and thus may be used instead of immunoassays.

Albumins↗
PubMed1976

Antibody as an immunological probe for studying the refolding of bovine serum albumin. I. The catalysis of reoxidation of reduced bovine serum albumin by glutathione and a disulfide interchange enzyme.

We have used an immunochemical approach to study the refolding of bovine serum albumin. Using antibody as a probe for return of native structure, we have been able to demonstrate the regeneration of native structure at several sites on the surface of the molecule. Using this technique, we have shown that the rate of refolding of reduced bovine serum albumin catalyzed by either glutathione or rat liver disulfide interchange enzyme is greater than the rate of air reoxidation of albumin. The half-regeneration times for albumin, however, are substantially greater than those obtained with smaller proteins that have fewer disulfide bonds. We have also demonstrated that the reoxidized monomers isolated at the end of the refolding process are immunologically identical to native monomers. In addition, the tryptophan fluorescence emission maxima were the same as that of the native monomers.

Antibodies↗
PubMed1981

Structural or functional heterogeneity of normal human serum albumin, allo albumin, bisalbumin.

The present paper reports a comparative isoelectric focusing study of electrophoretically normal and abnormal albumins. All the albumins were purified by two different techniques (cellulose acetate electrophoresis and preparative slab isoelectric focusing), and submitted to analytical isoelectric focusing before and after incubation with either metabolites or drugs. Isoelectric focusing patterns show general heterogeneity, both in normal and in any of the observed alloalbumins. The heterogeneity is increased in bisalbumins (drug or metabolite induced), showing the same electrophoretic pattern as alloalbumins. The differences are related to the amount of the ligands. The results agree with the hypothesis that the heterogeneity depends on the structure and the carrier function of albumin.

Albumins↗
PubMed1967

Cellular localization of anti-DNP-PLL and anticonveyor albumin antibodies in genetic nonresponder guinea pigs immunized with DNP-PLL albumin complexes.

Genetic nonresponder guinea pigs incapable of an immune response to DNP-PLL alone were immunized with DNP-PLL complexed to ovalbumin or bovine serum albumin. Under these circumstances the animals produce both anti-DNP-PLL antibodies and antibodies directed against the conveyor albumin. Thus immune response to DNP-PLL complexed to conveyor albumin molecules can serve as a simple model of hapten-carrier relationships. To explore these relationships the question whether these two types of antibody are synthesized by the same or by different plasma cells was investigated by a combination of a double immunofluorescent technique and radioautographic localization of radioactive antigen. It was shown that the anti-DNP-PLL antibodies and the antibodies against the carrier albumin molecule were produced in separate cells. No cell-producing antibodies with both specificities were detected out of 526 cells studied.

Animals↗
PubMed1991

[A latex immunologic method of analysis of low-molecular proteins and albumin in urine. II. Beta 2-microglobulin, retinol-binding protein and albumin levels in the urine of general Polish population and workers exposed to cadmium].

The aim of the work was to collect data about beta 2-microglobulin (beta 2M), retinol-binding protein (RBP) and albumin (Alb) levels in subjects not exposed to nephrotoxic agents in Poland. The data are necessary to interpret determination results in persons occupationally exposed to these chemicals. Concentrations of beta 2-microglobulin, retinol-binding protein and albumin in urine were determined using latex-immunological method. Examination of levels of low molecular proteins and albumin was made on population from agricultural regions of Poland (the Suwałki region) and on textile plant workers from Lódź not exposed to nephrotoxic agents. It was found that upper normal level of low molecular proteins in urine was 300 micrograms/l and of albumin 60 mg/l. The data obtained indicate that sex and age play an important role in beta 2-M and RBP excretion. In the workers of an alkaline accumulator plant who were occupationally exposed to cadmium, a statistically increased excretion of low molecular proteins in urine was observed compared to the controls from Lódź. In 20% of the subjects beta 2-M and RBP concentration in urine were higher than the accepted upper normal levels. Collected data make one aware of necessity to study the above determinations which lead to an early detection of renal function disorders.

Age Factors↗
PubMed1988

Albumin excretion rate, albumin concentration, and albumin/creatinine ratio compared for screening diabetics for slight albuminuria.

Slight albuminuria, an overnight albumin excretion rate (AER) greater than 30 micrograms/min in an "Albustix"-negative sample, predicts development of diabetic nephropathy. This study compares the AERs for 261 timed overnight urine collections with the albumin concentrations and albumin/creatinine ratios for the same specimens (equivalent to first morning specimens). Thirty-one specimens (11.9%) had AERs greater than 30 micrograms/min. Use of an albumin/creatinine ratio greater than 3.0 mg/mmol to predict an AER greater than 30 micrograms/min gave a sensitivity of 96.8%, a specificity of 93.9%, and a predictive value of 68.2%, with a correlation coefficient of 0.921. Use of an albumin concentration greater than 17 mg/L gave a sensitivity of 96.8%, a specificity of 90.9%, a predictive value of 58.8%, and a slightly poorer correlation (r = 0.904). Evidently either method is acceptable as an initial screening procedure, but determination of albumin concentration alone would be preferable because of lesser cost.

Albuminuria↗
PubMed1987

Albumin to creatinine ratio: an unreliable index of 24 h albumin excretion in healthy adults.

The urine albumin to creatinine ratio was studied on four timed collections during a 24 h period in a group of 30 healthy volunteers. The results show large within and between subject variation not explained by exercise, and the absence of a predictable diurnal pattern. It was not possible to predict the 24 h excretion of albumin from the albumin to creatinine ratio of a separately collected random urine sample. The large variations of the ratio observed in healthy subjects stress the need for 24 h urine collections rather than random samples when assessing albumin excretion.

Adult↗
PubMed1995

Molecular characteristics of methylglyoxal-modified bovine and human serum albumins. Comparison with glucose-derived advanced glycation endproduct-modified serum albumins.

The amino acid modification, gel filtration chromatographic, and electrophoretic characteristics of bovine and human serum albumins irreversibly modified by methylglyoxal (MG-SA) and by glucose-derived advanced glycation endproducts (AGE-SA) were investigated. Methylglyoxal selectively modified arginine residues at low concentration (1 mM); at high methylglyoxal concentration (100 mM), the extent of arginine modification increased and lysine residues were also modified. Both arginine and lysine residues were modified in AGE-SA. Analytical gel filtration HPLC of serum albumin derivatives suggested that the proportion of dimers and oligomers increased with modification in both low and highly modified MG-SA and AGE-SA derivatives relative to unmodified serum albumins. In SDS-PAGE analysis, dimers and oligomers of low-modified MG-SA were dissociated into monomers, but not in highly modified MG-SA. MG-SA had increased anodic electrophoretic mobility under nondenaturing conditions at pH 8.6, indicating an increased net negative charge, which increased with extent of modification; highly modified MG-SA and AGE-SA had similar high electrophoretic mobilities. MG-SA derivatives were fluorescent: the fluorescence was characteristic of the arginine-derived imidazolone N delta-(5-methyl-4-imidazolon-2-yl)ornithine, but other fluorophores were also present. AGE-SA had similar fluorescence, attributed, in part, to glucose-derived imidazolones. AGE formed from glucose-modified proteins and AGE-like compounds formed from methylglyoxal-modified proteins may both be signals for recognition and degradation of senescent macromolecules.

Animals↗
PubMed2005

Interaction of pyrene-end-capped poly(ethylene oxide) with bovine serum albumin and human serum albumin in aqueous buffer medium: a fluorometric study.

The photophysical behavior of a hydrophobically tailored water-soluble polymer, pyrene-end-capped poly(ethylene oxide) (PYPY), has been studied in aqueous buffered bovine serum albumin (BSA) and human serum albumin (HSA) media. In buffered aqueous solution the polymer shows dual emission corresponding to the monomer and the excimer of pyrene moiety. The relative intensity of the monomer to the excimer emission shows interesting variation with the addition of BSA and HSA and is indicative of significant interaction of these albumin proteins with the polymer. The binding interaction has been shown to have a prominent role on the steady state fluorescence anisotropy of the two emission bands. Attempt has been made to determine the micropolarities of the protein microenvironments from a comparison of the variation of the monomer to excimer relative fluorescence intensities of the probe in water-dioxane mixtures with varying composition.

Buffers↗
PubMed2001

The subsequent effect of interaction between Co(2+) and human serum albumin or bovine serum albumin.

A notable hysteretic effect has been observed in the interaction of Co(II) with human serum albumin (HSA) or bovine serum albumin (BSA) using UV-Visible spectrometry at physiological pH (7.43), which shows that the binding between Co(II) and HSA or BSA may induce a slow transition of HSA or BSA from the conformation of weaker affinity for Co(II) to one of stronger affinity (A-B transition). The rate constants and activation parameters of this transition were measured and are discussed. It is inferred that such a conformation transition may occur due to the binding of the first Co(II) ion with the peptide segment of N-terminal residues 1-3, which results in a 'hinged movement' of the relatively hydrophobic 'valley' in the IA subdomain. This process leads to a slow conformational transition in the albumins, makes the other binding sites of Co(II) exposed, and shows a positive cooperativity effect. The LMCT (ligand-to-metal charge transition) bands of the Co(II)-HSA and Co(II)-BSA systems also show a kind of hypochromic effect featuring a dipole-dipole interaction mechanism. This phenomenon is rarely reported.

Animals↗
PubMed1998

Checking the integrity of albumin after pasteurisation: a fluorescent assay for quantitating monomeric albumin using anthroyloxy-fatty acids analogs.

This study presents a new assay based on the binding of anthroyloxy-stearates to albumin and the change in the fluorescence intensity when these fluorescent probes are bound to the protein. This assay permits the quantification of the albumin monomers present in a mixture of monomers and polymers, and allows to check the integrity of albumin after pasteurisation.

Animals↗
PubMed1988

'Albumin-receptor' uptake kinetics do not require an intact lobular architecture and are not specific for albumin.

When freshly isolated well-stirred single cell suspensions of rat hepatocytes were incubated with 5-600 microM [3H]oleate or [35S]sulfobromophthalein (BSP) in the presence of 150 microM bovine serum albumin (BSA), uptake of both ligands increased as a linear function of the total ligand concentration in the medium. By contrast, when the same ligand concentrations were incubated as 1:1 complexes with BSA, apparent saturation of ligand uptake was observed. Analogous results were obtained in incubations employing beta-lactoglobulin instead of BSA. In none of these studies did ligand uptake velocity correlate in simple fashion with the concentration of unbound ligand in the incubation medium. These studies establish that the basis for the kinetic observations termed the 'albumin receptor phenomenon' does not require an intact hepatic lobular architecture or space of Disse, and is not specific for albumin.

Animals↗
PubMed1997

Red edge excitation shift emission spectroscopic investigation of serum albumins and serum albumin-bilirubin complexes.

The microenvironments around the intrinsic and extrinsic fluorophores in bovine and human serum albumins as well as their complexes with bilirubin have been visualized by red edge excitation shift (REES) emission spectroscopic investigation. The two albumins and their bilirubin complexes in aqueous buffered solutions (pH 7.5) do not exhibit any appreciable shift in their emission maxima, upon gradual change in excitation wavelength towards the red edge of their respective absorption band. The addition of Triton X-100 triggers REES emission in both the fluorophores. The observations suggest that the microenvironment around the flurophores are not so rigid, and even the extrinsic flurophore bilirubin having two carboxylic acid groups acts as a hydrophobic non-polar molecule when bound to albumins. The ligand binding domains (receptor sites) are large enough and incorporation of Triton X-100 makes the fluorophore environments rigid and subtle polarity may also be induced. Whereas small polar molecules like CHCl3, ANS and L-trp fail to induce REES emission in either of the fluorophores.

Animals↗
PubMed2004

Crystal structure and biological implications of a bacterial albumin binding module in complex with human serum albumin.

Many bactericide species express surface proteins that interact with human serum albumin (HSA). Protein PAB from the anaerobic bacterium Finegoldia magna (formerly Peptostreptococcus magnus) represents one of these proteins. Protein PAB contains a domain of 53 amino acid residues known as the GA module. GA homologs are also found in protein G of group C and G streptococci. Here we report the crystal structure of HSA in complex with the GA module of protein PAB. The model of the complex was refined to a resolution of 2.7 A and reveals a novel binding epitope located in domain II of the albumin molecule. The GA module is composed of a left-handed three-helix bundle, and residues from the second helix and the loops surrounding it were found to be involved in HSA binding. Furthermore, the presence of HSA-bound fatty acids seems to influence HSA-GA complex formation. F. magna has a much more restricted host specificity compared with C and G streptococci, which is also reflected in the binding of different animal albumins by proteins PAB and G. The structure of the HSA-GA complex offers a molecular explanation to this unusually clear example of bacterial adaptation.

Albumins↗