Showing papers on "Serum albumin published in 1990"

Production of correctly processed human serum albumin in transgenic plants.

Abstract: We have used a modified CaMV 35S promoter to direct the expression of chimaeric genes encoding human serum albumin (HSA) in transgenic potato and tobacco plants. To secrete the protein, either the human prepro-sequence or the signal sequence from the extracellular tobacco protein PR-S was used. We demonstrate secretion of HSA with both types of signal sequences in transgenic leaf tissue and in suspension cultures. HSA produced in transgenic potato plants was purified to chromatographic homogeneity. N-terminal amino acid sequence analysis revealed that the processing of the precursor protein was dependent on the type of signal sequence. Expression of the human preproHSA gene lead to partial processing of the precursor and secretion of proHSA. Fusion of HSA to the plant PR-S presequence resulted in cleavage of the presequence at its natural site and secretion of correctly processed HSA that is indistinguishable from the authentic human protein.

Structure and ligand binding properties of human serum albumin

Abstract: UNLABELLED 1 INTRODUCTION Serum albumin possesses a unique capability to bind, covalently or reversibly, a great number of various endogenous and exogenous compounds Several different transport proteins exist in blood plasma but albumin only is able to bind a wide diversity of ligands reversibly with high affinity The subject of the present thesis is these binding properties In 1981 the author proposed in a review a model for binding of ligands to serum albumin In the model, binding of ligands to at least 6 distinct regions was considered The purpose of the experimental work described here was to test the validity of the model This was done by performing a large number of competition experiments From these new data a revised model for ligand binding is presented 2 STRUCTURE AND CONFORMATIONAL CHANGES OF SERUM ALBUMIN Human serum albumin consists of 585 amino acids forming a single polypeptide of known sequence A number of well characterized genetic variants have been reported The physico-chemical characteristics of the protein are well-established By contrast, the complete secondary and tertiary structures are not known; information about major structural features only has been obtained The albumin molecule seems to have an overall ellipsoidal shape (about 140 x 40 A) and to be composed of domains On the basis of the amino acid sequence, Brown (1977a) proposed a 3-domain model for the protein Each domain is believed to consist of 6 helices forming a hydrophobic channel with basic and hydrophobic amino acid residues placed at the ends Experimental data, however, indicate that the domains cannot be identical Long-chain fatty acid ions are proposed to bind with high affinity within the channels The ability to fluctuate between isomeric forms in aqueous solution could assist in adapting the albumin molecule to bind ligands with a diverse nature with high affinity This possibility is discussed on the basis of several physico-chemical techniques including hydrogen-deuterium exchanges Also the importance of the N-B transition for ligand binding is considered 3 PRELIMINARY BINDING MODEL OF SERUM ALBUMIN Single binding of ligands to serum albumin is usually described as high-affinity binding to one or two sites and weaker binding to a larger number of sites In this chapter, the original binding model for high-affinity binding is elaborated Region 1 seems to be specific for binding of one, or possibly two, ions of long-chain fatty acids Region 2 is somewhat less specific and includes binding of octanoate, tryptophan, chlorazepate, thyroxine, p-iodobenzoate and possibly also chloride Region 3 accommodates bilirubin, Phenol Red, Bromophenol Blue and iopanoate Region 4 is a special site for strong binding of metal ions such as Cu++ and Ni++ Evidence is presented for placing the primary haemin site in a separate region (no 5) The existence of additional binding regions, well-suited for high-affinity binding of drugs, is discussed

Release of human serum albumin from poly(lactide-co-glycolide) microspheres.

Abstract: Human serum albumin (HSA) was encapsulated in a 50:50 copolymer of DL-lactide/glycolide in the form of microspheres. These microspheres were used as a model formulation to study the feasibility of controlling the release of large proteins over a 20- to 30-day period. We show that HSA can be successfully incorporated into microspheres and released intact from these microspheres into various buffer systems at 37°C. A continuous release of the protein could be achieved in physiological buffers at 37°C over a 20- to 30-day period from microspheres with high protein loadings (11.6%). These results demonstrate the potential of poly(DL-lactide-co-glycolide) microspheres for continuous delivery of large proteins.

Synthesis and chromatographic properties of an HPLC chiral stationary phase based upon human serum albumin

Abstract: A new HPLC stationary phase was synthesized by thein situ covalent immobilization of human serum albumin (HSA). The protein was immobilized on a commerically available diol column which had been activated with 1,1-carbonyldiimidazole. Initial chromatographic studies show that this phase can be used for chiral separations of enantiomeric solutes and that these separations may reflectin vitro binding to the HSA. The effects of mobile phase composition and temperature on the stereochemical resolutions are reported.

Purification and characterisation of an extracellular serine proteinase from Aspergillus fumigatus and its detection in tissue

Abstract: Surmmary A serine proteinase (Alp) from the culture supernate of a clinical isolate of Aspergillus fumigatus was purified to virtual homogeneity at a yield of 41%. The procedure involved affinity chromatography on agarose-e-amino-caproyl-D-trypto-phan methyl ester. Alp had an estimated mol. wt of 32 Kda and the pI was determined at pH 7.9. The enzyme was fully inhibited by phenylmethyl sulphonyl fluoride, chymostatin and α-1-proteinase inhibitor, and it was largely inhibited by α-1-anti-chymotrypsin. Partial inhibition was observed with tosyl-phenylalanine chloromethyl ketone, but tosyl-lysine chloromethyl ketone was ineffective. Thus, Alp may be identical with the major chymotryptic activity of A. fumigatus, which has already been described. The N-terminal sequence of 25 amino acids revealed an 88% homology of Alp with the subtilisin-related proteinase of A. oryzae. Alp acted on casein over a broad range from pH 5.5 to 11.5 and also acts to a lesser extent on haemoglobin and serum albumin. The enzyme degraded elastin and a synthetic elastase substrate; hence, it may be identical with the previously described elastinolytic activity of the fungus. At pH 7.3 and a concentration of 1 μg/ml, Alp was not toxic for Vero cells, but it efficiently detached such cells from a plastic surface. Specific antibodies against Alp were detected by enzyme immunoassay in the sera of patients and Alp-antigen was demonstrated by immunofluorescence in mycotic human lung. In addition, a second proteinase (Exalp) with extremely alkaline activity, and an aspartic proteinase of A. fumigatus are described.

Multihormonal regulation of the progesterone receptor in MCF-7 human breast cancer cells: interrelationships among insulin/insulin-like growth factor-I, serum, and estrogen.

Abstract: Estrogen (E) is well known to be an important stimulator of progesterone receptor (PR) synthesis in target cells. We have observed that E stimulation of PR in MCF-7 human breast cancer cells (as monitored by progestin binding or Western blotting with anti-PR antibodies) increases as a function of serum concentration in the cell culture medium; PR stimulation by E is greatest in high serum medium (5% or 10% charcoal dextran-treated calf serum) and is not observed when cells are in medium containing serum concentrations below 1%, although estrogen receptor levels are well maintained. This suggests that some serum factor(s) may be essential for E to be able to stimulate PR. To better understand such factors, we have grown cells in serum-free medium and in serum-free medium supplemented with insulin (6.25 micrograms/ml) [corrected], transferrin (6.25 micrograms/ml), selenium (6.25 ng/ml), albumin (1.25 mg/ml) [corrected], and linoleic acid (5.35 micrograms/ml; ITS+). Unexpectedly, we found that addition of ITS+ (without E) increases PR levels in these cells, especially in the absence of serum and under low serum conditions where E stimulation of PR is poor. Analyses of the individual components in ITS+ reveal that insulin is the major active component. Dose-response studies indicate that high superphysiological (greater than 1 microgram/ml) concentrations of insulin are required. In contrast, low physiological levels of insulin-like growth factor-I (IGF-I; 10 or 40 ng/ml) are active, suggesting mediation by the IGF type I receptor system. At all serum concentrations (0-10%), the effects of ITS+ and E in increasing PR are synergistic. The fact that anti-E are able to suppress the insulin/IGF-I stimulation as well as the E stimulation of PR suggests that the anti-E can actively interfere with the action of the growth factor as well as the action of E. These results indicate that regulation of PR is multifactor and raise the possibility that PR may be regulated in vivo by both E and growth factors such as IGF-I that are known to be increased in these breast cancer cells by E.

Brain edema and cerebrovascular permeability during cerebral ischemia in rats.

Abstract: Focal cerebral ischemia was produced by occluding the left middle cerebral artery in 769 rats. Permeability of the blood-brain barrier to small or large molecules was evaluated qualitatively using Evans blue or sodium fluorescein and quantitatively using the transfer indexes of iodine-125-labeled bovine serum albumin or [14C]sucrose. Water content was determined using wet and dry weights and sodium and potassium contents using flame photometry. Cortical tissue in the middle cerebral artery territory was sampled less than or equal to 14 days after occlusion. A significant increase in the albumin transfer index was first found 12 hours after occlusion, and the index remained approximately the same until water content peaked 3 days after occlusion. In contrast, the sucrose transfer index increased gradually, significantly correlated with increases in the water and sodium contents. Tissue staining by sodium fluorescein was more extensive than that by Evans blue. As edema fluid decreased gradually 4-10 days after occlusion, the albumin and sucrose transfer indexes increased markedly. These findings indicate that disruption of the blood-brain barrier to small molecules is accompanied by accumulation of edema fluid during the later stages of ischemia. Opening of the barrier to serum protein is probably related to the resolution of edema.

Induction of albumin gene transcription in hepatocytes by extracellular matrix proteins.

Abstract: Transcriptional activity of the albumin gene was induced in primary cultures of hepatocytes by adding dilute concentrations of basement membrane-like proteins derived from the EHS mouse sarcoma tumor to established type I collagen cultures. By immunofluorescence microscopy with antialbumin antibody, the population of cells responded uniformly to dilute EHS. Of the three major components of EHS, purified laminin was as effective as unfractionated EHS at inducing an increase in albumin mRNA levels and albumin secretion; type IV collagen and heparan sulfate proteoglycan were ineffective.

Binding of progesterone to nerve cell membranes of rat brain using progesterone conjugated to 125I-bovine serum albumin as a ligand.

Abstract: Radioiodinated bovine serum albumin conjugated to progesterone was used as a probe to examine binding parameters of steroids to membrane preparations from rat brain tissue. The binding of 11 alpha-hydroxyprogesterone-11-hemisuccinate-125I-bovine serum albumin conjugate reached saturation after 30 min of incubation at 5 degrees C. Several bovine serum albumin-conjugated steroids were then tested for competition displacement studies. Among these steroid conjugates, the bovine serum albumin conjugate at position 3 of progesterone had the highest affinity, with an estimated inhibition constant of 28.5 +/- 2.1 nM (n = 3), whereas bovine serum albumin itself and the 17 beta-estradiol 6-(O-carboxy-methyl)oxime-bovine serum albumin conjugate showed no specific displacement. In addition, the binding sites were localized in an axolemma-enriched fraction of rat brainstem. Specific binding was obtained in tissues from cerebral cortex, brainstem, cerebellum, corpus striatum, and hypothalamus, but little or no binding occurred in uterus, ovary, liver, and spleen. The present data indicate that progesterone-125I-bovine serum albumin conjugate can be used as a ligand to study progesterone-membrane receptor interactions.

Serum Albumin and Globulin

Abstract: Hundreds of proteins are dissolved in the plasma. By measuring the concentration of these proteins, the clinician can obtain information regarding disease states in different organ systems. The measurement of protein is done on serum, which is the fluid that remains after plasma has clotted, thus removing fibrinogen and most of the clotting factors. Total protein content provides some information regarding a patient's general status; more clinically useful data are obtained from fractionating the total protein. The normal serum protein level is 6 to 8 g/dl. Albumin makes up 3.5 to 5.0 g/dl, and the remainder is the total globulins. These values may vary according to the individual laboratory.

Effect of dietary protein deprivation on insulin-like growth factor (IGF)-I and -II, IGF binding protein-2, and serum albumin gene expression in rat.

Abstract: Circulating levels of insulin-like growth factor I (IGF-I) and serum albumin are decreased under conditions of chronic dietary protein limitation. To investigate the biochemical mechanism(s) involved in the regulation of IGF-I and serum albumin synthesis by dietary protein, we studied the effects of protein limitation on IGF-I and serum albumin gene expression in young growing rats maintained on isocaloric diets containing 20%, 12%, 8%, or 4% protein. Animals maintained on the 12%, 8%, or 4% protein diets exhibited slight, moderate, or severe growth deficiency, respectively, and a decreased abundance of hepatic IGF-I messenger RNA (mRNA). The decrease in IGF-I mRNA was most pronounced for the largest [7.7 kilobase (kb)] species, which was decreased by 87% in animals maintained on the 4% protein diet compared with animals on the 20% protein diet. The 0.9 kb species of IGF-I mRNA exhibited a smaller (46%) reduction in abundance in animals maintained on the 4% protein diet. The differential regulation of the 7.7 kb IGF-I mRNA species compared with the shorter IGF-I mRNA species suggests that a sequence or sequences within the long 3'-untranslated region of this mRNA species may play a role in regulating its abundance under conditions of protein limitation. Serum albumin mRNA was also decreased (by 62%) in the animals maintained on the 4% protein diet. The level of serum albumin gene transcription was not decreased in animals on the low protein diets, suggesting that nutrition regulates albumin mRNA at a posttranscriptional step. There was considerable animal-to-animal variability in the level of IGF-I gene transcription within each dietary group. The mean level of IGF-I gene transcription was decreased by 46% in the animals on the 4% protein diet compared with animals on the 20% protein diet, although this decrease was not statistically significant because of the animal-to-animal variability in IGF-I gene transcription within the dietary groups. Additional studies of brain RNA from animals on the four diets indicated that brain IGF-II mRNA was decreased by 57% in animals on the 4% protein diet. It has been demonstrated recently that expression of the gene for IGF binding protein-2 (IGFBP-2) is strongly induced in the liver of fasting animals. To investigate the possible regulation of the IGFBP-2 gene in the protein-limited animals, the abundance of liver and brain IGFBP-2 mRNA was analyzed in animals on the four diets.(ABSTRACT TRUNCATED AT 400 WORDS)

Tumor necrosis factor-alpha inhibits albumin gene expression in a murine model of cachexia.

Abstract: The mechanisms responsible for decreased serum albumin levels in patients with cachexia-associated infection, inflammation, and cancer are unknown. Since tumor necrosis factor-alpha (TNF alpha) is elevated in cachexia-associated diseases, and chronic administration of TNF alpha induces cachexia in animal models, we assessed the regulation of albumin gene expression by TNF alpha in vivo. In this animal model of cachexia, Chinese hamster ovary cells transfected with the functional gene for human TNF alpha were inoculated into nude mice (TNF alpha mice). TNF alpha mice became cachectic and manifested decreased serum albumin levels, albumin synthesis, and albumin mRNA levels. However, even before the TNF alpha mice lost weight, their albumin mRNA steady-state levels were decreased approximately 90%, and in situ hybridization revealed a low level of albumin gene expression throughout the hepatic lobule. The mRNA levels of several other genes were unchanged. Hepatic nuclei from TNF alpha mice before the onset of weight loss were markedly less active in transcribing the albumin gene than hepatic nuclei from control mice. Therefore, TNF alpha selectively inhibits the genetic expression of albumin in this model before weight loss.

The secretion of human serum albumin from the yeast Saccharomyces cerevisiae using five different leader sequences.

Abstract: We demonstrate the secretion of human serum albumin into the culture supernatant from the yeast Saccharomyces cerevisiae. Studies with five KEX2 processed leader sequences, namely the S. cerevisiae α factor, the natural human serum albumin, the Kluyveromyces lactis killer, a natural human serum albumin/α factor fusion, and a Kluyveromyces lactis killer/α factor fusion leader, are described. We show that the leader sequence used to direct secretion influences the quantity and quality of the secreted product. In designing secretion systems for heterologous proteins, one aims to maximise both the yield and fidelity of the product. Our results indicate that the choice of leader sequence and its relationship to the structural protein under study are crucial to the success of this process.

Quantitative analysis of antibody localization in human metastatic colon cancer: a phase I study of monoclonal antibody A33.

Abstract: A33 is a mouse immunoglobulin G2a (IgG2a) monoclonal antibody (mAb) that detects a heat-stable, protease- and neuraminidase-resistant epitope. The antigen is homogeneously expressed by virtually all colon cancers and in the colon mucosa but not other epithelial tissues. The biodistribution and imaging characteristics of iodine-131 (131I)-mAbA33 were studied in colorectal carcinoma patients with hepatic metastases. Antibody labeled with 2 to 5 mCi of 131I was administered intravenously (IV) 7 to 8 days before surgery at five dose levels, ranging from 0.2 mg to 50 mg, with three or more patients entered at each dose level. In addition, three patients received 2 mg 131I-mAbTA99 (an isotype-matched control mAb) together with 125I-mAbA33. Evaluation included whole-body imaging with a gamma camera, technetium-99 (99mTc)-human serum albumin blood pool scans, liver/spleen scans, abdominal computed tomographic (CT) scans, hepatic arteriograms, antibody pharmacokinetics, and assessment of antibody distribution in biopsied malignant and normal tissues. Selective mAbA33 localization to tumor tissue was demonstrated in 19 of 20 patients, and external imaging correlated with surgical inspection, pathologic examination, and tissue radioactivity. One week after antibody administration, tumor:liver ratios ranged from 6.9:1 to 100:1 and tumor:serum ratios from 4.1:1 to 25.2:1. 99mTc-albumin blood pool studies showed that liver metastases were hypovascular, emphasizing the selective localization of mAbA33 despite poor tumor-blood flow. Control mAbTA99 studies showed mAbA33 localization was antigen-specific; tumor:liver ratios were 2.3- to 45-fold higher for specific antibody. In metastatic lesions, radioisotope was localized primarily in the viable periphery; however, even the necrotic tumor core concentrated specific antibody. External imaging showed isotope visualization in some patients' large bowel; whether this represents specific antibody uptake or gastric iodine secretion is unclear.

Separation of sublethal and lethal effects of the bactericidal/permeability increasing protein on Escherichia coli.

Abstract: Binding of the bactericidal/permeability increasing protein (BPI) of granulocytes to Escherichia coli promptly produces several discrete outer envelope alterations and growth arrest without major impairment of bacterial structure or biosynthetic capabilities, raising the question whether these early effects of BPI are sufficient to cause bacterial death. In this study, the bactericidal action of BPI was examined more closely. We have found that bovine or human serum albumin blocks bacterial killing without preventing BPI binding or an increase in outer membrane permeability. Moreover, addition of serum albumin after BPI results in growth resumption without displacement of bound BPI and without (early) repair of the envelope alterations. These effects are opposite to those produced by Mg2+ (80 mM), which displaces greater than 85% of bound BPI and rapidly initiates outer envelope repair without restoration of bacterial growth. The extent of rescue by serum albumin depends on the time and pH of preincubation of BPI with E. coli: e.g., for E. coli J5 treated with human BPI, t1/2 = 79 min at pH 7.4 and 10 min at pH 6.0. The serum albumin effects on BPI action are the same in wild-type E. coli and in a mutant strain lacking an activatable phospholipase, indicating that serum albumin does not act by sequestering membrane-damaging products of bacterial phospholipid hydrolysis. The progression from reversible to irreversible growth arrest, revealed by the subsequent addition of serum albumin at different times, is paralleled by a decrease in amino acid uptake and an increase in the permeability of the cytoplasmic membrane to o-nitrophenyl-beta-D-galactoside. These findings demonstrate at least two stages in the action of BPI: (a) an early, reversible, sublethal stage in which BPI has effects on the outer envelope and causes growth arrest, and (b) time- and pH-dependent progression to a lethal stage, apparently involving cytoplasmic membrane damage, possibly caused by penetration of a small subpopulation of BPI.

Albumin supplementation in the critically ill. A prospective, randomized trial.

Abstract: • Albumin replacement to correct hypoalbuminemia in critically ill patients has been controversial. This study was a prospective, randomized trial of 25% albumin administration in 40 hypoalbuminemic (serum albumin, 25 g/L [2.5 g/dL]), critically ill patients. The treatment group (18 patients) received 25% albumin supplementation to achieve and maintain serum albumin levels of 25 g/L (2.5 g/dL) or greater, while the nontreatment group (22 patients) received no concentrated albumin. There was no clinical benefit from albumin therapy when assessing mortality (39% vs 27%, treatment vs control) or major complication rate (89% vs 77% of patients). There were also no significant differences in length of hospital stay, intensive care unit stay, ventilator dependence, or tolerance of enteral feeding, despite significant elevations of albumin in the treatment group. The costly use of exogenous albumin as treatment for hypoalbuminemia in this patient population does not appear to be justified. ( Arch Surg . 1990;125:739-742)

Regenerable fiber-optic-based immunosensor.

Abstract: An immunosensor is described that is based on fluorescently labeled F(ab') anti-human serum albumin antibody fragments covalently immobilized to the distal end of a fiber-optic probe. When human serum albumin is present, it is bound to the sensor and shields the fluorescent label from the solvent water, and a significant increase in the label fluorescence results. The sensor can be regenerated by simply immersing the sensing tip in chaotropic media. Under these conditions the antigen-antibody complex is selectively disrupted without adversely affecting the sensor. In the present configuration, the same sensor can be recycled over 50 times before the immunosurface inactivates significantly. With proper storage the sensor can last for up to 4 months.

Aflatoxin-albumin adducts in human sera from different regions of the world.

Abstract: An immunoassay now permits the determination of human exposure to aflatoxin at an individual level and consequently allows a better assessment of the role of aflatoxin, and its interaction with hepatitis B virus infection, in the aetiology of liver cancer. Measurements of aflatoxin bound to serum albumin in children and adults from various African countries show that between 12 and 100% contain aflatoxin-albumin adducts, with levels up to 350 pg AFB1-lysine equivalent/mg albumin. In Thailand, lower levels and prevalence of this adduct were observed, while no positive sera were detected from France or Poland. Data are presented showing that exposure to this carcinogen can occur throughout life and the relevance of these observations to the understanding of the multifactorial aetiology of liver cancer in these countries is discussed.

The effects of serum and human albumin on calcium hydroxyapatite crystal growth

Abstract: The effects of potential serum inhibitors upon the growth of calcium hydroxyapatite (HAP) crystals were studied in vivo using a pH-stat system Whole serum caused a marked decrease in crystal growth in a dose-dependent manner At a protein concentration of 13 micrograms/ml, whole serum reduced the initial rate of crystal growth from 84 mumol of KOH/h to 48 mumol of KOH/h Serum components were separated by ultrafiltration (10,000 Da cut-off) The high-molecular-mass fraction containing serum proteins gave an initial rate of crystal growth of 48 mumol of KOH/h compared with 64 mumol of KOH/h given by the low-molecular-mass components Thus, two-thirds of the inhibitory activity was associated with proteins and other serum macromolecules, whilst the remainder of the activity was associated with the low-molecular-mass components Albumin-depleted serum showed an initial rate of crystal growth of 59 mumol of KOH/h, whilst albumin purified by affinity chromatography gave an initial rate of crystal growth of 56 mumol of KOH/h at the same protein concentration Albumin, therefore, not only accounts for half of the protein concentration in serum, but also contributes half of the inhibitory activity of the high-molecular-mass fraction Heat denaturation of albumin dramatically enhanced the inhibition of HAP seeded growth with the initial rate of crystal growth falling to 27 mumol of KOH/h after treatment compared with 62 mumol of KOH/h before denaturation Isoelectric focusing indicated that the tertiary and secondary structure, and hence the distribution of surface charge of albumin, are altered by heat denaturation Gels showed a mixture of species with isoelectric points ranging from 60 to 50 compared with the native protein value of 47 These data suggest that adsorption of serum proteins to the growing HAP crystals is one mechanism of growth inhibition It is also clear that the most abundant serum protein, albumin, is an important mediator of this process

Serum albumin as a modulator on growth of the human breast cancer cell line, MCF-7.

Abstract: The growth of the estrogen responsive human breast cancer cell line, MCF-7, is inhibited by high serum concentrations, and this growth inhibition can be abolished by estradiol (E2). To investigate this inhibitory phenomenon further, we decided to purify the inhibitory factor from newborn calf serum (NCS). After the use of various fractionation methods, we found that inhibitory activity in NCS was exclusively expressed by albumin containing fractions. The inhibitory potential of several commercial bovine serum albumin (BSA) preparations and one human serum albumin preparation were analysed. They all exerted inhibitory activity comparable to that of NCS, and BSA inhibited MCF-7 cell proliferation in a concentration-dependent manner similar to that of NCS. Albumin itself or a contaminating factor in the albumin preparations seemed to be responsible for the growth inhibition. It could be excluded that the growth inhibitor TGF-beta, known to be present in serum, was the factor which inhibited MCF-7 cell proliferation. We separated contaminating proteins from albumin by gel filtration of a BSA preparation, revealing that neither low mol.wt nor high mol.wt proteins in the preparation exerted any significant growth inhibitory activity. NCS and BSA affected the secretion of specific proteins from MCF-7 cells similarly, when grown with or without E2. In conclusion, we assume that albumin is the factor in serum exerting a growth inhibition which can be reversed by E2. Our results indicate that albumin may affect cell proliferation by modulating the activities of autocrine growth regulatory factors.

The blood/gas solubilities of sevoflurane, isoflurane, halothane, and serum constituent concentrations in neonates and adults

Abstract: To determine the effect of prematurity on the solubility of volatile anesthetics in blood, the authors measured the blood/gas partition coefficients of sevoflurane, isoflurane, and halothane and the serum concentrations of albumin, globulin, cholesterol, and triglycerides in umbilical venous blood f

The effect of age on serum concentrations of albumin and alpha 1-acid glycoprotein

Abstract: 1. Human serum albumin (HSA) concentrations and alpha 1-acid glycoprotein (AAG) concentrations were measured in 68 subjects, 35 males and 33 females, aged 20-90 years without evidence of acute or chronic inflammatory disease or malignancy. Subjects were drug free for at least 1 month. HSA and AAG concentrations were measured using rate nephelometry. 2. Age had no effect on alpha 1-acid glycoprotein concentration, whereas plasma albumin levels decreased as a function of age in both sexes. We observed no differences between males and females in the plasma concentrations of HSA and AAG. 3. These data show that in healthy subjects the HSA concentration decreases with increasing age, whereas age, uncomplicated by disease does not influence AAG concentration.

Proteinuria, not altered albumin metabolism, affects hyperlipidemia in the nephrotic rat.

Abstract: It has been established previously that nephrotic hyperlipidemia is characterized by both an increase in lipid synthesis and a defect in removal of lipoproteins. The relationship between these defects and altered albumin metabolism is uncertain. One hypothesis is that hepatic lipogenesis increases in parallel with albumin synthesis. To test this hypothesis, albumin synthesis was increased in nephrotic rats fed an 8.5% protein diet (LPN) by increasing dietary protein to 40% (HPN). Proteinuria was modulated in half of the rats fed 40% protein by enalapril (HPE). Albumin synthesis was the same in both HPN and HPE, but proteinuria was reduced in HPE compared to HPN, and so were serum cholesterol and triglycerides (TG). To examine the effect of serum albumin on lipid clearance in the absence of proteinuria, plasma clearance of chylomicrons (CM) and VLDL was measured in Nagase analbuminemic rats (NAR) and found to be no different than in normal SD rats. When proteinuria was induced in NAR and in SD rats, a severe and identical defect in both CM and VLDL clearance was acquired in both groups and blood lipid levels were increased to a similar degree in both groups. Neither hyperlipidemia nor defective removal of lipoproteins from the circulation are linked to albumin synthesis or serum albumin concentration but result, at least in part, from proteinuria. Postheparin lipoprotein lipase (LPL) activity was reduced slightly in nephrotic animals compared to nonnephrotic controls, but the most striking finding was a highly significant decrease in postheraprin LPL activity in normal NAR compared to SD rats (P less than 0.001), suggesting that reduced LPL activity is not responsible for reduced clearance of CM and VLDL in nephrotic rats.

Evaluation of cationized rat albumin as a potential blood-brain barrier drug transport vector.

Abstract: The present investigations evaluated the effects in rats of repetitive administration of cationized rat albumin over an 8-week period with the future aim of using this modified protein as a vector to transport drugs across the brain capillary endothelial wall, i.e., the blood-brain barrier. Rat albumin was cationized at pH = 7.8 with hexamethylenediamine, and the isoelectric point of the protein was raised from 5.5 to approximately 8. The cationized protein was monomeric based on mobility during sodium dodecylsulfate polyacrylamide gel electrophoresis. After radiolabeling, the cationized rat serum albumin (RSA) was taken up by isolated rat or bovine brain microvessels, whereas radio-labeled native RSA was not taken up by the capillaries in vitro. The brain volume of distribution of the 3H-cationized RSA increased linearly over a 5-hr period after an intravenous injection of the isotope and reached a value of 46 +/- 3 microliter/g (mean +/- S.E.) by 5 hr, whereas the brain volume of distribution of the 125I-native RSA was constant during the 5-hr time period (9.3 +/- 0.7 microliter/g, which is equal to the brain blood volume). The cationized and native RSAs were administered daily (Monday through Friday) at a dose of 1 mg/kg subcutaneously to groups of rats for 4- and 8-week periods. This dosage regimen resulted in no discernible toxicity, based on the findings of normal weight gain, normal tissue histology and normal serum chemistry. Therefore, cationized rat albumin may be used in future studies that use the repetitive administration of cationized rat albumin chimeric peptides for the evaluation of the transport of these substances through the blood-brain barrier in vivo.

Measurement of albumin synthesis in humans: a new approach employing stable isotopes

Abstract: A new method for measuring albumin synthesis in humans with stable isotopes is presented. This can readily be applied in most clinical conditions, even when albumin losses are occurring or when repeated assessment is required. After rapid intravenous injection of a large dose of [13C]leucine (57 mg/kg body wt, 19.4 atoms%), plasma samples were taken at intervals up to 90 min. The enrichment of free leucine in plasma measured by gas chromatography-mass spectrometry rose to a peak at 10 min and then fell slowly, whereas that in liver biopsies (from surgical patients) ranged from 101.5 to 80.5% of the plasma value between 10 and 90 min after injection. The fractional synthesis rate (FSR) was calculated by dividing the increase in enrichment of leucine in albumin, measured by gas isotope ratio mass spectrometry, by the area under the plasma free leucine enrichment vs. time curve after allowing for the period between synthesis of the protein and its secretion into the plasma. The FSR in healthy postabsorptive males was 7.2 +/- 1.3%/day, and the absolute synthesis rate was 157 +/- 39 mg.kg body wt-1.day-1. These rates are comparable to those obtained by other methods.