Showing papers on "Serum albumin published in 1998"

Hydrophobicity of Bovine Serum Albumin and Ovalbumin Determined Using Uncharged (PRODAN) and Anionic (ANS-) Fluorescent Probes

Abstract: The influence of ionic interactions on quantitation of protein surface hydrophobicity was assessed by comparing the protein binding of an uncharged fluorescent probe, 6-propionyl-2-(N,N-dimethylamino)naphthalene (PRODAN), with that of an anionic probe, 1-(anilino)naphthalene-8-sulfonate (ANS-). Binding constants for the protein−probe complexes involving bovine serum albumin (BSA) and ovalbumin (OVA) in phosphate buffer (pH 7.0, I = 0.01 M) at 30 °C were fluorometrically determined to be KP-BSA = (1.00 ± 0.01) × 106 M-1 and KP-OVA = (4.2 ± 0.1) × 103 M-1, respectively, for PRODAN, compared to KA-BSA = (6.21 ± 0.04) × 106 M-1 and KA-OVA = (1.97 ± 0.09) × 103 M-1, respectively, for ANS-. A procedure was established using PRODAN to determine protein surface hydrophobicity (S0) values from the initial slope of relative fluorescence intensity versus protein concentration plots, and the results were compared to S0 values measured using ANS-. Increasing ionic strength up to 1.0 M decreased the S0 values of BSA me...

Serum albumin: touchstone or totem?

Abstract: A decrease in serum albumin concentrations is an almost inevitable finding in disease states, and is primarily mediated in the acute phase by alterations in vascular permeability and redistribution. This change is not disease specific but marked changes that persist are generally associated with a poorer prognosis. Critical appraisal of long-standing practices and the availability of alternative colloid solutions have led to a reduction in albumin replacement therapy, and a widespread tolerance of lower albumin concentrations in patients. The factors determining serum albumin concentrations, their measurement and the implications of hypoalbuminaemia are reviewed. The clinical value of serum albumin measurement is discussed.

3-Nitrotyrosine in the proteins of human plasma determined by an ELISA method.

Abstract: The modification of tyrosine residues in proteins to 3-nitrotyrosine by peroxynitrite or other potential nitrating agents has been detected in biological systems that are subject to oxidative stress. A convenient semi-quantitative method has been developed to assay nitrated proteins in biological fluids and homogenates using a competitive ELISA developed in our laboratory. This assay selectivity detected 3-nitro-l-tyrosine residues in a variety of peroxynitrite-treated proteins (BSA, human serum albumin (HSA), alpha1-antiprotease inhibitor, pepsinogen and fibrinogen) and also in a nitrated peptide, but had a low affinity for free 3-nitro-L-tyrosine and 3-chloro-L-tyrosine. The IC50 values for the inhibition of antibody binding by different nitrated proteins were in the range 5-100 nM, suggesting that the antibody discriminated between nitrotyrosine residues in different environments. The presence of nitrotyrosine in plasma proteins was detected by Western blot analysis and quantified by the ELISA. A concentration of 0. 12+/-0.01 microM nitro-BSA equivalents was measured in the proteins of normal plasma which was increased in peroxynitrite-treated plasma and was elevated in inflammatory conditions. HSA and low-density lipoprotein (LDL) isolated from plasma contained 0.085+/-0.04 and 0. 03+/-0.006 nmol nitro-BSA equivalents/mg protein, respectively. Comparison of the level of nitration in peroxynitrite-treated HSA and LDL in the presence and absence of plasma indicates that nitration and presumably oxidation is inhibited by plasma antioxidants. The presence of nitrotyrosine in LDL is consistent with previous reports implicating peroxynitrite in the oxidative modification of lipoproteins and the presence of a low concentration of oxidized LDL in the blood.

Biological basis of hypoalbuminemia in ESRD.

Abstract: Hypoalbuminemia is associated with mortality in patients with end-stage renal disease (ESRD) maintained either on peritoneal dialysis (PD) or hemodialysis (HD). Serum albumin concentration is determined by its rate of synthesis, by the catabolic rate constant (the fraction of the vascular pool catabolized per unit time), by external losses, and by redistribution from the vascular to the extravascular space. Hypoalbuminemia in dialysis patients is primarily a consequence of reduced albumin synthesis rate in both HD and PD patients, and in the case of PD patents, of transperitoneal albumin losses as well. Continuous ambulatory peritoneal dialysis patients are able to increase albumin synthesis to replace losses. Thus, ESRD does not directly suppress albumin synthesis. The rate of albumin synthesis is inversely proportional to the serum concentration of one potential acute phase protein (alpha2 macroglobulin), and albumin concentration is inversely proportional to that of either C-reactive protein or serum amyloid A in both HD and PD patients. The cause of decreased albumin synthesis is primarily a response to inflammation (the acute phase response), although it is possible that inadequate nutrition may also contribute. The cause of the inflammatory response is not immediately evident. There is no evidence that shifts of albumin to the extravascular space or that dilution of the plasma by volume expansion plays any role in causing hypoalbuminemia in ESRD patients.

Serum proteins as drug carriers of anticancer agents: a review.

Abstract: Targeted delivery of anticancer drugs is one of the most actively pursued goals in anticancer chemotherapy. Serum proteins such as transferrin, albumin, and low-density lipoprotein (LDL) offer promise for the selective delivery of antineoplastic agents due to their accumulation in tumor tissue. Uptake of these proteins in solid tumors is mediated by a number of factors, including an increased metabolic activity of tumors, an enhanced vascular permeability of tumor blood vessels for circulating macromolecules, and a lack of a functional lymphatic drainage system in tumor tissue. At the tumor site, transferrin, low-density lipoprotein, and albumin are taken up by the tumor cell through receptor-mediated and fluid phase endocytosis, respectively. Serum protein conjugates can be designed to release the bound antitumor drug after cellular uptake of the drug conjugate. This review covers the diagnostic evidence for tumor accumulation of serum proteins and the design, development, and biological evaluation of drug conjugates with transferrin, albumin, and low-density lipoprotein.

Association between tumor necrosis factor in serum and cachexia in patients with prostate cancer

Abstract: The present study was undertaken to evaluate the relationship between serum tumor necrosis factor (TNF) and cachexia in patients with prostate cancer TNF levels were determined in 110 serum samples from prostate cancer patients by an enzyme immunoassay Serum TNF activity was positive in 76% of the patients with relapsed disease, whereas only 11% of the untreated patients and 0% of the patients in remission as a result of endocrine therapy were positive The serum total protein and albumin levels, hemoglobin levels, and body mass index of the patients with elevated serum TNF levels were significantly lower (P < 005) than the corresponding values in patients with undetectable serum TNF levels The serum TNF levels of patients with serum albumin levels of <35 g/dl, serum total protein levels of <70 g/dl, hemoglobin levels of <110 g/dl, and a body mass index of <21 kg/m2 were significantly higher (P < 005) than the values in their respective counterparts There was a significant correlation between the detectability of serum TNF and performance status (P < 005) Patients with elevated serum TNF levels had a significantly higher mortality rate (P < 005) than those with undetectable serum TNF levels These findings suggest that TNF may be one of the factors contributing to the complex syndrome of cachexia in patients with prostate cancer

Correction of metabolic acidosis increases serum albumin concentrations and decreases kinetically evaluated protein intake in haemodialysis patients: a prospective study.

Abstract: BACKGROUND Metabolic acidosis in haemodialysis (HD) patients increases whole body protein degradation while the correction of acidosis reduces it. However, the effects of the correction of acidosis on nutrition have not been clearly demonstrated. STUDY DESIGN In this study we have evaluated the effects of 3 months of correction of metabolic acidosis by oral sodium bicarbonate supplementation on protein catabolic rate (PCRn) and serum albumin concentrations in 12 uraemic patients on maintenance HD for at least 6 months (median 49 months; range 6-243 months). Pre-dialysis serum bicarbonate, arterial pH, serum albumin, total serum proteins, serum creatinine, plasma sodium, haemoglobin, PCRn, Kt/V, and TACurea, were evaluated before and after correction. RESULTS Serum bicarbonate levels and arterial pH increased respectively from 19.3 +/- 0.6 mmol/l to 24.4 +/- 1.2 mmol/l (P < 0.0001) and 7.34 +/- 0.03 to 7.40 +/- 0.02 (P < 0.0001). Serum albumin increased from 34.9 +/- 2.1 g/l to 37.9 +/- 2.9 g/l (P < 0.01), while PCRn decreased from 1.11 +/- 0.17 g/kg/day to 1.03 +/- 0.17 g/kg/day (P < 0.001). No changes in Kt/V, total serum proteins, serum creatinine, plasma sodium, haemoglobin, body weight, pre dialysis systolic and diastolic blood pressure, and intradialytic weight loss were observed. CONCLUSIONS Our data demonstrate that correction of metabolic acidosis improves serum albumin concentrations in HD patients. The correction of acidosis induces a decrease in PCRn values, as evaluated by kinetic criteria, suggesting that in the presence of moderate to severe acidosis this parameter does not reflect the real dietary protein intake of the patients probably as a result of increased catabolism of endogenous proteins. The correction of metabolic acidosis should be considered of paramount importance in HD patients.

Chiral Inversion and Hydrolysis of Thalidomide: Mechanisms and Catalysis by Bases and Serum Albumin, and Chiral Stability of Teratogenic Metabolites

Abstract: The chiral inversion and hydrolysis of thalidomide and the catalysis by bases and human serum albumin were investigated by using a stereoselective HPLC assay. Chiral inversion was catalyzed by albumin, hydroxyl ions, phosphate, and amino acids. Basic amino acids (Arg and Lys) had a superior potency in catalyzing chiral inversion compared to acid and neutral ones. The chiral inversion of thalidomide is thus subject to specific and general base catalysis, and it is suggested that the ability of HSA to catalyze the reaction is due to the basic groups of the amino acids Arg and Lys and not to a single catalytic site on the macromolecule. The hydrolysis of thalidomide was also base-catalyzed. However, albumin had no effect on hydrolysis, and there was no difference between the catalytic potencies of acidic, neutral, and basic amino acids. This may be explained by different reaction mechanisms of the chiral inversion and hydrolysis of thalidomide. Chiral inversion is deduced to occur by electrophilic substituti...

Serum albumin: a prognostic indicator in patients with colorectal cancer.

Abstract: Various prognostic factors for survival have been identified in patients with colorectal cancer. However, although it has been suggested that the pre-treatment serum albumin concentration is a prognostic indicator in certain malignant diseases (melanoma, prostate cancer, leukaemia), its value in patients with colorectal cancer remains unclear. This study investigated the prognostic value of serum albumin in this patient group. A total of 431 patients presenting to the Professorial Surgical Unit between 1972 and 1985 were analysed in this study. Using the Cox proportional hazard model, age, tumour stage (Dukes' stage) and tumour differentiation were shown to be independent prognostic factors for survival in patients with localized colorectal cancer. In addition, the pre-treatment serum albumin concentration was found to be an independent prognostic indicator. This is the first such documentation for patients with 'curable' colorectal cancer.

Predictive Value of Functional Status for Mortality in Patients on Maintenance Hemodialysis

Abstract: In patients receiving maintenance hemodialysis, laboratory indices (such as serum albumin concentration) are predominantly utilized to assess well-being, while measures of functional status are rarely applied. However, the serum albumin concentration declines with advancing age, and the mean age of patients starting maintenance hemodialysis is now over 63 years. Using a 14-level modified Karnofsky activity scale, we measured baseline functional status in 522 randomly selected hemodialysis patients and prospectively monitored them for 3 years to determine the predictive value of our modified Karnofsky score for mortality. At onset of study, serum albumin and creatinine concentrations as well as hematocrit were measured and the comorbid conditions documented. At baseline, the 522 subjects (270 women and 252 men) included 327 blacks (63%), 154 whites (29%), 31 Hispanics (6%), and 10 Asians (2%) of mean age 59 ± (SD) 15 years. The mean duration of end-stage renal disease was 4 ± 3.6 years, and the mean serum albumin concentration was 3.7 ± 0.4 g/dl. 166 (32%) of the patients died during the observation period. Cox regression analysis revealed inverse relations between mortality and both our modified Karnofsky score (p = 0.0001) and serum albumin concentration (p = 0.001). The predictive value of a low modified Karnofsky score for mortality persisted after analysis of subjects stratified according to serum albumin concentration (not predict survival in the Cox model when other independent variables were included. We conclude that in patients with end-stage renal disease sustained on maintenance hemodialysis, a poor functional status (measured on a modified Karnofsky activity scale) is associated with early mortality. Periodic measurement of modified Karnofsky score is a simple, low-cost, and reliable means of identifying patients on dialysis at risk for early death.

Additive effects of bovine serum albumin, dithiothreitol, and glycerol on PCR.

Abstract: The effects of bovine serum albumin, dithiothreitol, and glycerol on PCR were studied. PCR under standard conditions failed the amplification of an enterohemorrhagic E. coli DNA fragment when the boiled bacterial cell lysate was used as the template. The addition of either one of bovine serum albumin, dithiothreitol, or glycerol in the reaction mixture allowed the specific fragment amplification; and the optimum concentrations were as follows: bovine serum albumin, 1 mg/ml; dithiothreitol, 10 mM; and glycerol, 5%. In addition, when all of the three agents were included at the above concentrations, the PCR yield was further increased. The effect of the three-agent mixture was not the template specific. Furthermore, the mixture enabled long PCR over 20 kb when Taq DNA polymerase with 3'-5' exonuclease activity was used for the amplification. Our simple PCR method allows robust PCR independent of template purity or amplification length.

Tissue protein synthesis rates in critically ill patients

Abstract: ObjectivesThe aims of this study were to simultaneously determine the in vivo rates of protein synthesis in skeletal muscle, peripheral blood lymphocytes, and serum albumin in critically ill patients; to establish whether a relationship between the responses of these tissues could be observed; and t

Bovine serum albumin reverses inhibition of RT-PCR by melanin.

Abstract: Melanin contained in pigment cells in a variety of tissues co-purifies with nucleic acids in standard RNA (or DNA) extraction procedures. The presence of melanin in RNA (or DNA) templates can inhibit reverse transcription polymerase chain reactions (RT-PCR) and/or PCR (5). In the past, to circumvent this problem, melanin has been separated from DNA by either columnchromatography (5) or acid-precipitation (3). In this study, a facile approach is described to overcome melanin inhibition of RT-PCR. Specifically, the addition of >15 μg of bovine serum albumin (BSA) per 25 μL RT-PCR mixture is shown to reverse melanin inhibition (Figures 2, A and B). BSA has been used previously to prevent inhibition of PCR amplifications by hemin, iron chloride, tannic acids, fulvic acids, extracts from feces, freshwater or marine water (4). In this study, we describe the doseresponse effect of melanin on RT-PCR inhibition and the effect of BSA in overcoming melanin inhibition. The addition of 2 μg of synthetic melanin (Catalog No. M-8631; Sigma Chemical, St. Louis, MO, USA) to a 25-μL RT-PCR can completely inhibit RTPCR of aldolase mRNA (Figure 1A). A similar degree of inhibition was observed when melanin-containing RNA preparations were prepared from either normal melanocyte cell strains (Figure 2A) or melanoma cell lines (data not shown). While RT-PCR of 0.5 μg total RNA will normally yield a product after 16 cycles of PCR following RT (2), when 2 μg of melanin were present, no RT-PCR product was obtained after 45 cycles of PCR. The addition of >15 μg BSA to the reaction mixture alleviated melanin inhibition and allowed detection of a PCR product by PCR cycle 16. The addition of 20–23 μg BSA per assay appeared to be optimum (Figure 1B) in overcoming melanin inhibition. Fatty acid-free BSA (Catalog No. A7511; Sigma Chemical), >97% pure alcohol-precipitated BSA (Catalog No. A-4378; Sigma Chemical) and Fraction V 98%–99%-pure BSA (Catalog No. A-7906; Sigma Chemical) were found to be equally effective in reversing melanin-mediated RT-PCR inhibition (data not shown). It was reported previously that melanin inhibits PCR (5). We found that melanin slightly inhibits the RT step as well. This determination was made as follows: (i) two RT reactions were carried out: a control and an RT containing 2 μg of synthetic melanin, and (ii) PCR was carried out on 1/100 dilution of the RT-generated cDNAs. Note that 1/100 dilution was used as a means to eliminate the effects of melanin at the PCR step. A small reduction in PCR product was noted after 2 μg of synthetic melanin were added at the RT step. This amount of melanin present at the PCR step would have been completely inhibitory. Thus, melanin appears to have only a small effect on reverse transcription. In summary, the simple addition of >15 μg BSA per 25 μL RT-PCR mixture effectively overcomes inhibition of RT-PCR by melanin. Addition of up to 23 μg BSA per RT-PCR appeared to have no deleterious effects on RT-PCR product yield. This modified procedure should allow more effective RT-PCR analysis in melanin-containing cells or tissues (e.g., skin, hair or eyes).

Extracellular fluid volume determined by bioelectric impedance and serum albumin in CAPD patients.

Abstract: Aim. To investigate the relationship between serum albumin and extracellular fluid volume, as measured by multifrequency bioelectrical impedance, in stable patients treated by CAPD. Method. Fifty-nine stable CAPD patients were assessed. Serum albumin (bromocresol green) and CRP, age, dialysate to plasma (D/P) creatinine ratio, normalized protein catabolic rate (nPCR), daily urine and peritoneal protein losses, and extracellular fluid volume (Vecf) were measured in each patient. Vecf was calculated as a percentage of actual body weight (Vecf% ABW ), of lean body mass derived from anthropometry (Vecf% LBM ) and of total body water ( Vecf% Vtbw). Comparisons between those with a normal serum albumin (≥37 g/l) and those with a low serum ajbumin (<37 g/l) were made by Mann-Whitney U test. Correlations with serum albumin were sought by Pearson's test. Results. The D/P creatinine ratio, daily peritoneal and urine protein losses, and extracellular fluid volume (Vecf% LBM and Vecf% Vtbw) were all significantly greater in patients with serum albumin <37 g/1 as compared to those ≥37 g/l; P< 0.05. Age, CRP, and nPCR were not different. Serum albumin was negatively correlated with Vecf% LBM, r = - 0.25; P= 0.05, Vecf% Vtbw, r= -0.39; P=0.002, and daily urinary albumin loss, r= -0.25, P=0.06. Conclusion. Hypoalbuminaemia is partly dependent on subclinical overhydration in CAPD patients. Serum albumin is negatively correlated with increased extracellular fluid volume and the proportion of Vecf to Vtbw is increased in hypoalbuminaemic patients. Multifrequency bioelectrical impedance is able to identify these abnormalities.

Receptor-mediated endocytosis of albumin by kidney proximal tubule cells is regulated by phosphatidylinositide 3-kinase.

Abstract: Receptor-mediated endocytosis of albumin is an important function of the kidney proximal tubule epithelium. We have measured endocytosis of [125I]-albumin in opossum kidney cells and examined the regulation of this process by phosphatidylinositide 3-kinase (PI 3-kinase). Albumin endocytosis was inhibited by both wortmannin (IC50 6.9 nM) and LY294002 (IC50 6.5 microM) at concentrations that suggested the involvement of PI 3-kinase in its regulation. Recycling rates were unaffected. We transfected OK cells with either a wild-type p85 subunit of PI 3-kinase, or a dominant negative form of the p85 subunit (Deltap85) using the LacSwitch expression system. Transfects were screened by immunoblotting with anti-PI 3-kinase antibodies. Under basal conditions, transfects demonstrated no expression of p85 or Deltap85, but expression was briskly induced by treatment of the cells with IPTG (EC50 13.7 microM). Inhibition of PI 3-kinase activity by Deltap85 was confirmed by in vitro kinase assay of anti-phosphotyrosine immunoprecipitates from transfected cells stimulated with insulin. Expression of Deltap85 resulted in marked inhibition of albumin endocytosis, predominantly as a result of reduction of the Vmax of the transport process. Expression of p85 had no significant effect on albumin uptake. The results demonstrate that PI 3-kinase regulates an early step in the receptor-mediated endocytosis of albumin by kidney proximal tubular cells.

Serum albumin and colloid osmotic pressure in survivors and nonsurvivors of prolonged critical illness

Abstract: We retrospectively compared the changes in serum albumin concentration and colloid osmotic pressure between survivors and nonsurvivors of prolonged (> or = 7 days) critical illness over a 2-year period from 1 July 1995. All patients had serum albumin measured daily, and colloid osmotic pressure measured 5 days a week, throughout their ICU admission. They received crystalloid and colloid infusions as well as parenteral or enteral feeding. Infusions of albumin were not used to treat hypoalbuminaemia. One hundred and forty-five patients were included, 66 nonsurvivors and 79 survivors. Nonsurvivors were significantly older than survivors [mean (95% CI): 58 (3.8) and 49 (4.1) years, respectively] and had a greater risk of death [mean (95% CI): 0.44 (0.06) and 0.28 (0.05); p < 0.05]. There was no significant difference in gender, APACHE II score [mean (95% CI): 22 (2.7) (nonsurvivors); 18 (2.3) (survivors)] or length of stay [median (interquartile range): 14 (9-27) days (nonsurvivors); 15 (9-26) days (survivors)]. There was no difference between the two groups in the absolute minimum serum albumin concentrations reached, the time to reach that minimum or the minimum in the first 7 days. However, nonsurvivors had a significantly lower mean serum albumin concentration: [mean (95% CI): 15.7 (5.1) g.l-1 compared with 18.3 (4.6) g.l-1 in survivors; p < 0.05]. They also had a lower recovery mean (the weighted mean after the minimum value): [mean (95% CI): 13.3 (5.1) g.l-1 (nonsurvivors) and 18.6 (5.3) g.l-1 (survivors); p < 0.01]. Analysis of colloid osmotic pressure results showed no difference between the groups in mean, minimum or recovery mean. Regression analysis of mean colloid osmotic pressure and albumin revealed that albumin only contributed 17% of the colloid osmotic pressure in these patients. The similar decrease in albumin in nonsurvivors and survivors may reflect the acute inflammatory response and/or haemodilution. However, survivors showed an ability to increase serum albumin concentrations, possibly owing to resumption of synthesis. The colloid osmotic pressure varied little between or within either group of patients, possibly because of the use of artificial colloids. There was no relationship between death and colloid osmotic pressure.

Absence of albumin in the plasma of the common carp Cyprinus carpio: binding of fatty acids to high density lipoprotein

Abstract: It was investigated whether an albumin-like protein, active in the transport of free fatty acids, is present in the blood of the common carp, Cyprinus carpio. In contrast with the brown trout Salmo trutta, no free fatty acid-binding protein could be found with a molecular mass and isoelectric point similar to human serum albumin. On the other hand, free fatty acids bound in this fish species to the apolipoproteins of high density lipoprotein (HDL), namely apolipoprotein A-I and apolipoprotein A-II. In addition to the binding of free fatty acids, carp HDL was also capable of interacting with the lipophilic human serum albumin binding dye, Cibracon Blue. The results obtained with plasma of carp, trout and man suggest that HDL acts as an alternative carrier for the transport of free fatty acids in the blood when albumin concentrations are low or absent.