Showing papers on "Serum albumin published in 1980"

Increased Glycosylation of Serum Albumin in Diabetes Mellitus

Abstract: The level of glycosylated albumin has been determined in the serum of normal and diabetic subjects after purification of the albumin to apparent homogeneity. The sugar was released from the albumin preparations as 5-hydroxymethylfurfural (HMF) after 24 h of hydrolysis in 2 N acetic acid at 92°C, and it was assayed by the thiobarbituric acid reaction. The mean value for glycosylated albumin, expressed as picomoles of HMF per nanomole of albumin, obtained from 10 normal control and 65 diabetic subjects, was 64 and 124, respectively. The level of glycosylated albumin correlates with the mean blood glucose concentration (N = 55, r = 0.715), but not with the fasting blood sugar concentrations. Moreover, a linear relationship was observed between the amounts of glycosylated hemoglobin (HbAla−c) and glycosyl-albumin (n = 74, r = 0.88). In an insulin-treated diabetic patient, there was a different temporal relationship between blood glucose concentrations and glycosylated hemoglobin and albumin levels. While HbAla−c was lowered by only 15% after 20 days, glycosylated albumin had dropped by more than 50% during the same time. Our results indicate that glycosylated albumin might provide a valuable tool to assess the average blood sugar levels between shorter intervals, since the turnover of serum albumin is considerably faster than that of HbAla−c.

Binding of bilirubin to albumin.

Abstract: (1980). Binding of Bilirubin to Albumin. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 11, No. 4, pp. 307-399.

Coordinate regulation of two estrogen-dependent genes in avian liver.

Abstract: Livers of egg-laying species contain abundant mRNAs encoded by both estrogen-responsive and constitutively expressed genes. We have recently constructed cDNA clones from three members of the abundant mRNA class of hen liver. One of these mRNA species was identified as serum albumin mRNA, and another as vitellogenin mRNA. In this study we have identified the third member of the group as apo VLDLII mRNA. Hybridization analyses using cloned cDNA probes indicate that expression of the apo VLDLII gene in rooster liver, like that of the vitellogenin gene, is completely dependent upon the administration of estrogen. The apo VLDLII and vitellogenin genes appear to be the only genes capable of high rates of expression in the liver that exhibit such an exceptional response to the hormone. Administration of estrogen resulted in the appearance of both mRNA species within 30 min, followed by a rapid accumulation to several thousand copies per cell. Removal of the hormone caused a marked destabilization of both vitellogenin mRNA and apo VLDLII mRNA. In contrast, the absolute levels of serum albumin mRNA were unaffected by the hormone. Comparative studies on the structure and organization of these three genes may reveal elements involved in determining their rates of expression in the presence and absence of estrogen.

Studies on the mechanism of capacitation: albumin-mediated changes in plasma membrane lipids during in vitro incubation of rat sperm cells.

Abstract: Plasma membrane isolated from rat sperm cells after incubation in vitro had a significantly lower cholesterol/phospholipid mole ratio when the medium contained serum albumin. Transfer of albumin-bound phospholipids to the membrane can largely account for this effect. The result is broadly consistent with a previously proposed model for albumin-induced destabilization of sperm membrane (capacitation) and its reversal by seminal plasma membrane vesicles. Albumin also decreased sialic acid and, more specifically, ganglioside levels, presumably by promoting release of sperm neuraminidase. Cholesteryl ester comprised up to 0.5 mol/mol of cholesterol in these plasma membrane preparations.

Albumin synthesis in young and elderly subjects using a new stable isotope methodology: Response to level of protein intake

Abstract: Albumin synthesis was evaluated in 5 young adult males (19–25 yr) and 6 elderly males (64–78 yr) by a procedure involving oral administration of 15 N-glycine every 3 hr over a 60-hr period From about 40 hr onwards, urinary urea achieved a plateau of 15 N-enrichment, which was estimated from the average of the last five (low protein) or seven (adequate protein) consecutive three-hourly urinary samples of the 60-hr period This enrichment plateau was used as an index of the 15 N-enrichment of the guanidine N of hepatic free arginine The 15 N-enrichment of the guanidine N of arginine in serum albumin was determined and albumin synthesis was estimated by comparing this value with the estimated enrichment of precursor hepatic arginine Using this methodology, serum albumin concentration, synthesis, rate and plasma volume were measured when the young and elderly subjects had received an adequate protein intake (15 g · kg −1 for 7 days) or a low protein intake (04 g · kg −1 for 14 days) Serum albumin concentration was lower in the elderly at both levels of protein intake; protein intake did not affect this parameter in either age-group Plasma volume (per kg body weight) did not differ between young and old, but increased in both groups when they were given the low-protein diet, so that the total intravascular albumin mass increased in both age groups significantly in the case of the young, and was probably due to net transfer of albumin from the extravascular pool The fractional synthesis rate of the whole body albumin pool with adequate intake of protein was 40%/day in the young and 34%/day in the elderly This fractional rate was reduced significantly by giving the low-protein diet to the young subjects, but was not reduced in the elderly Absolute synthesis rates, calculated per kg body weight and per kg body cell mass, led to a similar conclusion Whole body protein synthesis was also estimated from urinary 15 N-urea enrichment using the Picou and Taylor-Roberts model Albumin synthesis as a percentage of whole body protein synthesis (5%–6%) was reduced in the young adults by giving the low-protein diet, but was unchanged in the elderly In conclusion, the rate of albumin synthesis in the young, but not in the elderly, is sensitive to changes in protein intake It is suggested that albumin synthesis in the elderly is controlled at a lower set point, which prevents its response to higher protein intakes

Kinetics and mechanism of the interaction between human serum albumin and monomeric haemin.

Abstract: The interaction of human serum albumin with monomeric haemin has been investigated by detailed kinetic analysis in dimethyl sulphoxide/water (3:5, v/v). The results obtained under conditions of albumin saturation of haemin and under pseudo-single turnover conditions indicate that methaemalbumin is formed in a two-stage, single-intermediate process. The initial association between the haemin and human serum albumin is a chemically controlled process (k1 = 1.7 X 10(5) mol-1 . s-1 . dm3 at 24 degrees C); the variation of K1 with pH exhibited a well defined pK of 5.9. The overall equilibrium constant, calculated by using microscopic rate constants, is 1.1 (+/- 0.5) X 10(8) mol-1 at 24 degrees C. The data and conclusions are consistent with a general binding mechanism for albumin in which intermediate formation is followed by an entropy-controlled internalization of the ligand.

Studies on the mechanism of binding of serum albumins to immobilized cibacron blue F3G A

Abstract: The interaction of Cibacron Blue F3G A-Sepharose 4B with several serum albumins was studied. Although all albumins used were fond to bind to this adsorbent, human serum albumin was bound to a far greater extent than were the others. From the results of competition experiments and n.m.r. studies of Cibacron Blue and/or bilirubin binding to human serum albumin it is proposed that the mechanism of the interaction between human serum albumin and cibacron Blue is consistent wit Cibacron Blue binding to bilirubin-binding sites. In contrast with these findings with human serum albumin, there is little or no interaction of Cibacron Blue and the bilirubin-binding sites of albumins from rabbit, horse, bovine or sheep sera, although some interaction occurs between Cibacron Blue and the fatty acid-binding sites of these proteins. Structural analogues of Cibacron Blue have been used to investigate the binding of albumins to these ligands.

Serum protein binding of drugs during and after pregnancy in humans.

Abstract: The serum protein binding of three weakly acidic drugs (salicylic acid, sulfisoxazole, and Phenytoin), one weak base (diazepam), and one steroid (dexamethasone) was determined in pregnant women at seven time periods during pregnancy and at two time periods post partum, as well as in a group of nonpregnant women of childbearing age. The serum free fraction values (ratio of concentrations, free to total drug) of all drugs rose during pregnancy, primarily after 15 wk of gestation, and remained elevated for at least 1 to 5 days post partum. Pregnancy had the greatest effect on protein binding of sulfisoxazole, diazepam, and salicylic acid. The magnitude of this effect is such that quantitatively significant changes in the pharmacokinetic and pharmacodynamic characteristics of certain drugs may be expected to occur during pregnancy (in addition to possible changes caused by other pregnancy-related effects such as altered activity of drug-metabolizing enzyme systems). All drugs but dexamethasone exhibited significant negative correlations between free fraction values and serum albumin concentrations during pregnancy. The serum protein binding of salicylic acid, but not the other drugs tested, was more extensive in nonpregnant women who were not taking oral contraceptives than in those who were. Clinical Pharmacology and Therapeutics (1980) 28, 253–261; doi:10.1038/clpt.1980.158

Serum Albumin and Body Weight as Predictors of Postoperative Course in Colorectal Cancer

Abstract: . The influence of preoperative serum albumin and percent ideal body weight on postoperative outcome was examined in 83 patients operated upon for colorectal cancer. Compared to patients with normal preoperative body weight and serum albumin, the following were noted: 1) those with low serum albumins had increased rates of complications (p < 0.02) and deaths (p < 0.02); 2) complications were increased in obese patients (p < 0.02); and 3) those with two nutritional abnormalities had increased rate of complications (p < 0.05) and deaths (p < 0.01). The group at highest risk, those with both low body weight and decreased serum albumin, had a complication rate of over 70% and a mortality rate of 42%.

Immunological Quantification by High-Affinity Antibodies of O6-Ethyldeoxyguanosine in DNA Exposed to N-Ethyl-N-nitrosourea

Abstract: Three immunological methods [radioimmunoassay (RIA), enzyme-linked immunosorbent assay, and radioimmunosorbent technique] were established for quantification of the potentially mutagenic O6-ethyldeoxyguanosine (O6-EtdGuo) in DNA treated with the carcinogen ethylnitrosourea in vivo or in vitro. To obtain high-affinity antibodies for specific detection of low levels of O6-EtdGuo in small amounts of DNA (cells), different schemes were applied for immunization of rabbits with the hapten O6-ethylguanosine coupled to various carrier proteins (rat serum albumin, bovine serum albumin, keyhold limpet hemocyanin). Low-dose immunization with the hapten-keyhold limpet hemocyanin conjugate resulted in antibodies with an affinity constant of 1 to 2 X 10(10) liters/mol and very low levels of cross-reactivity with normal as well as other alkylated DNA components. The RIA (the most sensitive of the three assays) detects 0.05 pmol of O6-EtdGuo at 50% inhibition of tracer (O6-ethyl[8,5'-3H]-3'-deoxyguanosine)-antibody binding. This permits quantification by RIA of O6-EtdGuo at an O6-EtdGuo:2'-deoxyguanosine molar ratio of approximately 3 X 10(-7) in a hydrolysate of 100 micrograms of ethylated DNA. By chromatographic separation of O6-EtdGuo prior to the RIA, this value can be lowered to less than 5 X 10(-8).

Proteins in cerebrospinal fluid and plasma of fetal sheep during development.

Abstract: 1. The concentration of total protein in c.s.f. and plasma has been measured in fetal sheep of different gestational ages and in the adult. In c.s.f. it was highest (approximately 840 mg/100 ml.) in the youngest fetuses (35 days) and declined steeply by 60 days (260 mg/100 ml.). It decreased less markedly in the last half of gestation to reach about 50 mg/100 ml. at 125 days which is twice the adult value. Protein concentration in plasma was lowest in the youngest fetuses and did not rise much until the second half of gestation during which time it doubled. There was a further rather larger increase between the late fetal (125 days) stage and the adult.2. Albumin, fetuin, alpha-fetoprotein (AFP), transferrin and lipoprotein were identified in c.s.f. and plasma.3. The concentrations of albumin, AFP and fetuin in c.s.f. and plasma at different gestational ages were measured using immunodiffusion and radioimmuno-assays.4. Albumin was the major protein in plasma at all ages studied (35-128 days gestation and adult). Its concentration increased throughout gestation whereas that of fetuin was similar at all fetal ages and that of AFP declined markedly during the second half of gestation. In the adult, fetuin was only about 0.1% of the total protein in plasma and AFP was not detectable.5. In 35-40 day fetuses albumin, AFP and fetuin accounted for 90% of the total protein concentration in plasma and for about 70-80% of the total protein concentration of c.s.f. As gestation progressed the concentration of all three proteins in c.s.f. declined. But the concentration of AFP and fetuin fell more rapidly and to a greater extent than that of albumin; neither AFP nor fetuin could be detected in adult c.s.f.6. The c.s.f.: Plasma ratio was above 50% for AFP and above 60% for fetuin at 35 days compared with about 25% for albumin at the same fetal age. The c.s.f.: plasma ratios for all three proteins declined with increasing fetal age and were not significantly different from each other by about mid gestation.

Serum Albumin and Nutritional Status

Abstract: Serum albumin concentration is frequently used to define nutritional status. To validate this relationship, 161 body composition studies were performed on 102 patients simultaneously with protein electrophoresis. The body cell mass represented by the exchangeable potassium to total body water ratio correlated significantly (p < 0.001) with the serum albumin concentration (r = 0.59) and significantly (p < 0.001) to total protein (r = 0.59). However, in both cases the 95% confidence limits about the regression were wide. In 24 of 54 patients (44%) with a normal nutritional state, as defined by body composition, the serum albumin was abnormal. In 12 of 107 (11.2%) patients with malnutrition, the serum albumin was normal. Patients with more than one study were divided into 3 groups depending on the changes in their nutritional state as defined by their body composition. Serum albumin did not consistently reflect the significant body compositional changes observed. The data indicate that serum albumin is a valid measure of nutritional state for epidemiological surveys. However, due to the low sensitivity and specificity it is a poor parameter for evaluating the individual patient's nutritional state.

Anaphylactic release of intestinal goblet cell mucus.

Abstract: The effect of intestinal anaphylaxis on goblet cell mucus release was tested in rats immunized with small doses of egg albumin and alum and challenged intraduodenally with antigen The alteration in vascular and mucosal permeability which accompanies intestinal anaphylaxis was reflected by increased retention of 125I-labelled rat serum albumin in gut wall segments and increased amounts of protein-bound radioactivity in the intestinal secretion from the segments Intestinal goblet cell mucus was labelled in vivo with 35S Infusion of antigen, into the duodenum of actively immunized rats led to the appearance of 35S-labelled high molecular weight glycoprotein, presumably of goblet cell origin, in the intestinal secretions Goblet cell mucus release was dependent on the dose of antigen infused, was antigen-specific and was inhibited by pretreatment of rats with cyproheptidine Enhanced release of goblet cell mucus was observed in normal rats prepared by intravenous injection of rat antiserum rich in IgE anti-egg albumin antibodies and challenged by intraduodenal infusion of antigen Prior heating of the antiserum inhibited passive transfer of the reaction; this finding is consistent with the heat lability of IgE antibodies The latter class of antibodies are presumed to be responsible for intestinal anaphylaxis and its associated mucus release in the model system examined

Demonstration of specific binding sites for human serum albumin in group C and G streptococci.

Abstract: A total of 297 bacterial strains belonging to 27 species was tested for quantitative uptake of radiolabeled human serum albumin. Specific binding sites with high affinity for human serum albumin were found exclusively in group C and G streptococci. The albumin binding was found to be a time-dependent, saturable, and displaceable process which obeyed simple kinetic equations. Scatchard analysis revealed that human serum albumin bound to a homogeneous population of receptors with an affinity in the order ot 10(7) liters/mol and that the average bacterial cell carried more than 80,000 binding sites. The albumin receptor is a heat-stable component susceptible to proteolytic digestion. It has a surface localization separate from the receptors for immunolgobulin G, fibrinogen, aggregated beta 2-microglobulin, and haptoglobin. In individual strains, albumin reactivity was also detected independently of these other types of interactions with human proteins.

Blood-cerebrospinal fluid transfer of plasma proteins during fetal development in the sheep.

Abstract: 1. The penetration of human and sheep plasma proteins from blood into c.s.f. of sheep fetuses (57-86 days gestation) has been studied. The proteins were injected intravenously via cotyledonary vessels. After different time periods the c.s.f. concentrations of marker proteins were estimated by radioactive counting of iodinated human or sheep proteins or by immunoassay of human proteins. 2. Several proteins of similar molecular size penetrated into c.s.f. to a different extent in 60 day fetuses. The steady-state c.s.f.: plasma ratios were about 15% for human AFP, 10% for human transferrin and sheep albumin, 7% for human α1-antitrypsin, and 5% for human albumin. In older fetuses the penetration of protein from blood into c.s.f. was much reduced and no evidence for differential penetration of different proteins was found. 3. The penetration of human AFP, transferrin and sheep albumin from blood into c.s.f. was greater than can be accounted for by passive diffusion. 4. The results of this paper are discussed in relation to those of the preceding paper on the identification and quantification of proteins in fetal c.s.f. and plasma. The hypothesis is put forward that the choroid plexus of the immature (60 days and less) sheep fetus contains a mechanism for the transcellular transfer of plasma proteins which may be selective in nature and of importance for some aspects of brain development.

Anion channel blockers inhibit lysosomal enzyme secretion from human neutrophils without affecting generation of superoxide anion

Abstract: The role of permeant anions in lysosomal enzyme secretion from human neutrophils was investigated by means of anion-channel-blocking agents: 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), and pyridoxal phosphate. Lysosomal enzyme release from cytochalasin B-treated human neutrophils stimulated by immune complexes (bovine serum albumin and IgG anti-bovine serum albumin) was inhibited by DIDS, SITS, and pyridoxal phosphate at concentrations that inhibited sulfate fluxes. Enzyme secretion triggered by calcium ionophore A23187 was also inhibited by DIDS and SITS; these agents acted on secretory events subsequent to Ca2+ influx. Neither the species of permeant anion(s) nor the role of anion fluxes in degranulation was identified, although influxes of chloride, hydroxide, or phosphate ions were not critical. In contrast to degranulation, generation of superoxide anions (O2.-) stimulated by immune complex or A23187 was not inhibited by these agents. Ultrastructural cytochemical studies demonstrated that, although lysosomal contents were not discharged from stimulated cells, vacuole formation and lysosome-lysosome fusion were unaffected by SITS or DIDS. Data suggest that anion channel blockers specifically inhibit fusion of lysosomes with the plasma membrane or its invaginations.

Synthesis of rat liver microsomal cytochrome b5 by free ribosomes.

Abstract: Free and membrane-bound polyribosomes were separated from liver homogenates and characterized by electron microscopy. Using the wheat germ cell-free translation system, total translation products of poly A+RNA extracted from free polyribosomes (poly A+RNAf) showed some correlation to total liver cytosol proteins. In contrast, translation products of poly A+RNA from membrane-bound polyribosomes (poly A+RNAmb) showed some similarity to rat serum. Antibody to purified rat serum albumin immunoprecipitated from only the translation products of poly A+RNAmb a single polypeptide of mol wt 68,000. i.e., 3,000 greater than secreted serum albumin. In contrast, antibody to detergent-extracted cytochrome b5 immunoprecipitated from only the translation products of poly A+RNAf a single polypeptide of mol wt 17,500, identical to that of microsomal cytochrome b5. A consideration of the known properties of cytochrome b5 is consistent with an exclusive site of synthesis on free ribosomes.

Quantitation of aflatoxin B1 and aflatoxin B1 antibody by an enzyme-linked immunosorbent microassay.

Abstract: A specific microtest plate enzyme immunoassay has been developed for the rapid quantitation of aflatoxin B1 at levels as low as 25 pg per assay Multiple-site injection of rabbits with an aflatoxin B1 carboxymethyloxime-bovine serum albumin conjugate was used for the production of hyperimmune sera Dilutions of the purified antibody were air dried onto microplates previously treated with bovine serum albumin and glutaraldehyde and then incubated with an aflatoxin B1 carboxymethyloxime-horseradish peroxidase conjugate The amount of enzyme bound to antibody was determined by monitoring the change in absorbance at 414 nm after the addition of a substrate solution consisting of hydrogen peroxide and 2,2'-azino-di-3-ethyl-benzthiazoline-6-sulfonate Antibody titers determined in this manner closely correlated with those determined by radioimmunoassay Competition assays as performed by incubation of different aflatoxin analogs with the peroxidase conjugate showed that aflatoxins B1 and B2 and aflatoxicol caused the most inhibition of conjugate binding to antibody Aflatoxins G1 and G2 inhibited the conjugate binding to a lesser degree, whereas aflatoxins M1 and B2a had no effect of the assay

Influx of Thyroid Hormones into Rat Liver In Vivo: DIFFERENTIAL AVAILABILITY OF THYROXINE AND TRIIODOTHYRONINE BOUND BY PLASMA PROTEINS

Abstract: The transport of [(125)I]thyroxine (T(4)) and [(125)I]triiodothyronine (T(3)) into liver was investigated with a tissue sampling-portal vein injection technique in the anesthetized rat. The method allows the investigation of the effects of plasma proteins in human serum on the unidirectional influx of T(4) or T(3) into liver cells. The percent extraction of unidirectional clearance of T(3) and T(4) was 77+/-2% and 43+/-2%, respectively, after portal injection of a bolus of Ringer's solution. Cell membrane transport of T(4) or T(3) was nonsaturable because 50-muM concentrations of unlabeled hormone had no effect on transport. The addition of bovine albumin in concentrations of 1, 5, or 10 g/100 ml bound >98% of T(4) or T(3) in vitro, but had no significant effect on T(3) or T(4) transport in vivo. Conversely, 10% rabbit antisera specific for T(3) or T(4), completely abolished the intracellular distribution of thyroid hormone into liver. In the presence of rat serum, which contains albumin and thyroid hormone binding pre-albumin (TBPA), 18 and 81% of total plasma T(4) and T(3), respectively, were available for transport in vivo. The fraction of hormone available for transport in the presence of normal human serum, which contains albumin, TBPA, and thyroid hormone binding globulin (TBG) was 11% for T(4) and 72% for T(3). The fraction of hormone transported into liver after injection of serum obtained from pregnant or birth control pilltreated volunteers was 4% for T(4) (but this was not significantly different from zero) and 54% for T(3). THESE DATA SUGGEST: (a) The mechanism by which T(4) and T(3) traverse the liver cell membrane is probably free diffusion. (b) Albumin-bound T(4) or T(3) is freely cleared by liver, approximately 50% of TBG-bound T(3) is transported, but little, if any, of TBPA-bound T(4) or TBG-bound T(4) is cleared by liver cells. (c) Although the albumin-bound fraction of T(4) greatly exceeds the free (dialyzable) moiety, the two fractions are both inversely related to the existing TBA or TBG level; therefore, in vitro measurements of free T(4) would be expected to accurately reflect what is available for transport in vivo. Conversely, TBG-bound T(3) is readily transported in vivo; therefore, it is proposed that in vitro measurements of free T(3) do not reliably predict the fraction of T(3) available for transport into liver in vivo.

Bacterial antigen detection in body fluids: methods for rapid antigen concentration and reduction of nonspecific reactions.

Abstract: We sought procedures which would allow a rapid concentration in high yield of bacterial antigens from tissue fluids of patients and which could be applied also to protein-rich fluids like serum. Ethanol precipitation at a subzero temperature with albumin added as an antigen coprecipitant made it possible to achieve a more than 20-fold concentration of antigen in 15 min and a 200-fold concentration in 45 min. Heat-stable antigens could be concentrated from protein-rich fluids (like serum) after the sample had been deproteinized by boiling. Such heating (100 degrees C, 3 min) also liberated bacterial polysaccharides from antibody complexes and elminated the nonspecific interference of serum in enzyme-linked immunosorbent assay.

Zinc absorption in Crohn's disease.

Abstract: Zinc deficiency is a potential complication of Crohn's disease and we have searched for evidence of this and assessed the possibility that malabsorption of zinc might be a cause. Serum zinc concentrations in 33 patients suffering from Crohn's disease were significantly lower than in 58 normal control subjects (9 . 18 +/- 2 . 3 mumol compared with 13 . 6 +/- 1 . 73 mumol, P < 0 . 0005). Serum zinc correlated well with serum albumin concentrations and the low serum zinc may simply reflect the low serum albumin. Thus its value as an indicator of zinc deficiency is poor. We studied zinc absorption in seven patients with Crohn's disease and compared it with the results obtained previously in five normal subjects using a new technique involving a short-lived isotope of zinc (69mZn). Plasma appearance curves, constructed after an oral dose of isotope, and disappearance curves, after an intravenous dose, were used in a deconvolution computer programme to calculate zinc absorption. Compared with normal subjects, zinc absorption was considerably impaired in patients with Crohn's disease (range 9--45%, compared with 38--75%). This abnormality is a potential cause of zinc deficiency in patients with Crohn's disease.