A simple method for the preparation of human serum albumin

Novel mefenamic acid PVC membrane sensor based on a new Cd Schiff's base complex containing a phenanthroline unit

In this study, a PVC membrane electrode modified with a Cd Schiff base complex was constructed as a novel, sensitive and selective structured carrier for checking trace amounts of mefenamic acid in real samples.

Hepatocyte spheroids as a competent in vitro system for drug biotransformation studies: nevirapine as a bioactivation case study

The development of metabolically competent in vitro models is of utmost importance for predicting adverse drug reactions, thereby preventing attrition-related economical and clinical burdens. Using the antiretroviral drug nevirapine (NVP) as a model, this work aimed to validate rat hepatocyte 3D spheroid cultures as competent in vitro systems to assess drug metabolism and bioactivation. Hepatocyte spheroids were cultured for 12 days in a stirred tank system (3D cultures) and exposed to equimolar dosages of NVP and its two major Phase I metabolites, 12-OH-NVP and 2-OH-NVP. Phase I NVP metabolites were detected in the 3D cultures during the whole culture time in the same relative proportions reported in in vivo studies. Moreover, the modulation of SULT1A1 activity by NVP and 2-OH-NVP was observed for the first time, pointing their synergistic effect as a key factor in the formation of the toxic metabolite (12-sulfoxy-NVP). Covalent adducts formed by reactive NVP metabolites with N-acetyl-L-cysteine and bovine serum albumin were also detected by high-resolution mass spectrometry, providing new evidence on the relative role of the reactive NVP metabolites, 12-sulfoxy-NVP, and NVP quinone methide, in toxicity versus excretion pathways. In conclusion, these results demonstrate the validity of the 3D culture system to evaluate drug bioactivation, enabling the identification of potential biomarkers of bioactivation/toxicity, and providing new evidence to the mechanisms underlying NVP-induced toxic events. This model, integrated with the analytical strategies described herein, is of anticipated usefulness to the pharmaceutical industry, as an upstream methodology for flagging drug safety alerts in early stages of drug development.

A novel albumin-based tissue scaffold for autogenic tissue engineering applications

Tissue scaffolds provide a framework for living tissue regeneration. However, traditional tissue scaffolds are exogenous, composed of metals, ceramics, polymers, and animal tissues, and have a defined biocompatibility and application. This study presents a new method for obtaining a tissue scaffold from blood albumin, the major protein in mammalian blood. Human, bovine, and porcine albumin was polymerised into albumin polymers by microbial transglutaminase and was then cast by freeze-drying-based moulding to form albumin tissue scaffolds. Scanning electron microscopy and material testing analyses revealed that the albumin tissue scaffold possesses an extremely porous structure, moderate mechanical strength, and resilience. Using a culture of human mesenchymal stem cells (MSCs) as a model, we showed that MSCs can be seeded and grown in the albumin tissue scaffold. Furthermore, the albumin tissue scaffold can support the long-term osteogenic differentiation of MSCs. These results show that the albumin tissue scaffold exhibits favourable material properties and good compatibility with cells. We propose that this novel tissue scaffold can satisfy essential needs in tissue engineering as a general-purpose substrate. The use of this scaffold could lead to the development of new methods of artificial fabrication of autogenic tissue substitutes.

Effective removal of albumin from serum

The protein constituents of serum can range from grams to picograms per liter, making it technically difficult to achieve in-depth proteomic analysis. Removal of highly abundant proteins, such as albumin, coupled to powerful protein separation methods is required for increased sample load, thus facilitating detection and identification of low-abundant proteins. We report here a chemical-based extraction method for the effective and specific removal of albumin from serum.

Exposure to topical bovine thrombin during surgery elicits a response against the xenogeneic carbohydrate galactose alpha1-3galactose

Exposure of humans to topical bovine thrombin has been associated with development of antibodies against bovine and human coagulation factors and blood coagulation abnormalities. However, the nature of this humoral response is unknown. In this study, numerous glycoproteins in the topical bovine thrombin were found to contain the Gal(alpha1)-3Gal epitope, which is known to be highly immunogenic. More importantly, Gal(alpha1)-3Gal is recognized by natural antibodies that are found in all normal individuals and are known to effectively mediate complement activation and subsequent destruction of xenogeneic tissues. Thus, primary exposure of normal individuals to topical bovine thrombin is expected to result in an immediate immune reaction against that reagent. Further, following exposure to topical bovine thrombin, the levels of anti-Gal(alpha1)-3Gal IgG rose to levels tenfold greater than the average level of natural anti-Gal(alpha1)-3Gal IgG in naive individuals. Thus, Gal(alpha1)-3Gal in topical bovine thrombin accounts for, at least in part, the highly immunogenic nature of this reagent.

Sequential purification of human apolipoprotein B-100, albumin, and fibrinogen by immunoaffinity chromatography for measurement of protein synthesis

A determinant of the accuracy of protein synthesis measurement using stable isotope is the purity of the protein under study. An Immunoaffinity chromatographic technique to sequentially purify human plasma albumin, fibrinogen, and apolipoprotein B-100 (ApoB-100) was developed to measure isotopic enrichment in these proteins. The technique, utilizing immobilized mouse monoclonal antibodies specific to human plasma ApoB-100, albumin, and fibrinogen onto an affinity matrix, allowed purification of very low density lipoprotein (VLDL) ApoB-100, albumin, and fibrinogen from 1- to 2-ml plasma samples. Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining demonstrated consistent purity of the three purified proteins. The identity and the purity of the proteins separated by this technique were also confirmed by amino acid sequence analysis. This technique was applied to sequentially purify and measure the isotopic enrichment in those proteins by mass spectrometry from human plasma samples collected after orally ingesting L[1-13C]-leucine. Reproducibility of the enrichment measurements is within 5% of the coefficient of variation. Measurements [13C]leucine in these proteins purified from plasma samples collected during a 10-h primed continuous intravenous infusion of L-[1-13C]leucine confirmed that this technique provides an efficient way to purify plasma VLDL ApoB-100, albumin, and fibrinogen for measuring their synthetic rates in human metabolism studies.

Effect of fetal and adult bovine albumins on human lymphocyte proliferation in vitro

Fetal and adult bovine albumins were isolated and compared with the commercially obtained fraction V of Cohn, in terms of their ability to support cell proliferation, when added as a supplement to serum-free lymphocyte cultures activated with phytohemagglutinin. It was found that fetal albumin is the least efficient of the three proteins in permitting lymphoproliferation. A difference between the kinetics of proliferation of lymphocyte cultures supplemented with albumin and with serum was also observed.

Pilot-plant scale preparation of human serum albumin

Pilot-plant scale experiments using production scale fractionation equipment have been carried out to prepare human serum albumin according to a two-step simple method reported previously. Results have indicated that scale-up is feasible and the resultant albumin is of at least the same quality but with better yield when compared to that obtained by the conventional ethanol fractionation method. Filtration to replace centrifugation in one of the steps for liquid-solid separation was also attempted. It proved to be superior to centrifugation in terms of time and labor savings, but a small percentage of albumin was not recoverable. However, because of the simplicity and higher yield of this fractionation method the final albumin yield is still higher than that obtained by the conventional ethanol method even if the filtration step is introduced. Diafiltration and ultrafiltration are used for solvent removal and concentration, instead of lyophilization and reconstitution to prepare the final albumin solutions.

A comparative study of some physico-chemical properties of human serum albumin samples from different sources--II. The characteristics of the N-B transition and the binding behaviour with regard to warfarin and diazepam

A comparative study of the N-B transition and the drug binding properties of human serum albumin samples from various sources has been carried out with the help of circular dichroism and equilibrium dialysis. It was found that when warfarin was used as a marker the midpoint pH and the cooperative nature of the N-B transition that occurs in the albumin around physiological pH varied with the albumin sample. The midpoint pH was found to be related to the cooperative nature of the albumin samples. A similar relationship has been found for allosteric proteins. However, when diazepam was used as a marker molecule for the N-B transition, variations in the midpoint pH and cooperative nature of the N-B transition disappeared. This is attributed to the strong allosteric effect of diazepam on binding. The affinity of warfarin for albumin depends strongly on the sample, but this is not the case with diazepam. The cooperative binding properties found for the albumin samples are compared with those found for the albumin in serum. After a discussion it is concluded that the cooperative binding properties of a particular albumin sample should be taken into account when that sample is used in binding studies.

A comparative study of some physico-chemical properties of human serum albumin samples from different sources--I. Some physico-chemical properties of isoionic human serum albumin solutions

Human serum albumin samples from different sources were investigated. The fatty acid content of the albumin before and after deionization on a mixed bed ion-exchange column varied from sample to sample. When an albumin sample from one source was deionized under standard conditions the amount of fatty acid bound by the albumin was reduced to a reproducible amount. In samples from different sources, however, the amount bound varied considerably. Also the isoionic pH of the albumin varied from sample to sample. This variation could be attributed to the difference in the fatty acid content and the different number of titratable histidines and acid amino-acid residues in the albumin from different sources. It can be concluded from the specific conductance of these isoionic solutions that ions other than H-, OH and protein are effectively removed by a mixed bed ion-exchange column. The specific conductance of the albumin samples is directly related to the isoionic pH. Therefore, the isoionic pH and the specific conductance of the albumins reflect the heterogeneity of the albumin samples with respect to their primary structure and fatty acid content.

A simplified method for the preparation of immune-serum globulin

This report describes the recovery of highly purified immune-serum globulin (ISG) from the 42% ethanol precipitate fraction (42% P) generated during the first step of albumin purification. The method consists of three purification steps: (1) reprecipitation of the 42% P at 20% ethanol, pH 7.2; (2) solubilization of ISG at 17% ethanol, pH 5.2, and (3) isoelectric precipitation of ISG at 25% ethanol, pH 7.2. ISG prepared by this method was homogeneous when subjected to immunoelectrophoresis and polyacrylamide gel electrophoresis, and gave a yield equivalent to 4.7 g/l plasma, corresponding to a final recovery of over 48%.