SERUM ALBUMIN RESEARCH

Albumin: Not Just a Plasma Expander

noreply@blogger.com (Diagnostic Research) — Sun, 13 Nov 2011 17:05:00 +0000

Abstract:
HUMAN SERUM ALBUMIN is important for health and normal metabolic function. It comprises over half of the extracellular protein in blood and is the main regulator of plasma oncotic pressure. Traditionally, its main use has been as a volume expansion agent. Albumin undertakes a wide variety of transport functions and is essential for carrying metabolic products to the liver for metabolism and excretion. Due to its redox-active properties, it also acts as a first line of defence against pro-oxidant and free radical injury. In subjects with liver disease its concentration is reduced, an effect that is further compounded by studies that demonstrate that the remaining protein is functionally impaired. This lack of metabolic function most likely contributes to exacerbation of the disease processes. Administration of albumin to both patients with liver disease, and for a wide variety of other indications, shows beneficial effects that go far beyond simple fluid resuscitation.

Davies NA, Garcia R, Proven A, Jalan R

Gerbes AL (ed): Ascites, Hyponatremia and Hepatorenal Syndrome: Progress in Treatment. Front Gastrointest Res. Basel, Karger, 2011, vol 28, pp 40–51 (DOI: 10.1159/000319177

Prognostic significance of preoperative serum albumin level in patients with gastric cancer.]

noreply@blogger.com (Diagnostic Research) — Sun, 03 Apr 2011 22:20:00 +0000

Liu N, Liang H, Zhang RP, Pan Y, Ke B, Zhao JZ, Liu XY, Han T.

Department of Gastrointestinal Cancer, Tianjin Cancer Hospital, Key Laboratory of Cancer Prevention and Treatment of Tianjin City, Tianjin Medical University, Tianjin 300060, China.

Abstract
OBJECTIVE: To evaluate the prognostic significance of preoperative serum albumin in patients with gastric cancer undergoing radical resection.

METHODS: A total of 146 patients with gastric cancer underwent radical resection from January 2001 to December 2003. Clinicopathological data were analyzed retrospectively. Patients were divided into two groups, including patients with a normal preoperative serum albumin level(>35 g/L, n=115) and patients with hypoalbuminemia (≤35 g/L, n=31).

RESULTS: Patients with a low albumin level were associated with a higher postoperative recurrence rate(90.3% vs. 43.5%, P<0.01). The overall 5-year survival rate in patients with a normal serum albumin level was significantly higher than that in patients with a low serum level(57.4% vs. 9.7%, P<0.01). On multivariate analysis, preoperative serum albumin level was an independent factor associated with survival(P<0.01). When stratified by nodal metastasis, normal serum albumin level was still associated with higher survival rate(P<0.05). Prognostic significance was found in patients with lower stomach cancer(P<0.01), but not in patients with cancer in the upper and middle stomach(P>0.05).

CONCLUSION: Hypoalbuminemia is associated with worse survival in patients with cancer in the lower stomach and adjuvant therapy should be considered.

Recombinant human serum albumin.

noreply@blogger.com (Diagnostic Research) — Wed, 15 Sep 2010 20:32:00 +0000

Abstract
Human serum albumin (HSA) is responsible for 80% of the colloid osmotic pressure of plasma (25-33 mmHg). Its main clinical use is in maintaining colloid oncotic pressure and increasing circulating plasma volume with the typical dosage in excess of 10 g per dose.

HSA is isolated by fractionating human plasma, which entails possible contamination by viruses or prions. Recombinant HSA (rHSA) has been successfully produced using a methylotrophic yeast, Pichia pastoris. Due to the fact that the clinical usage of HSA infusion often exceeds 10 g, rHSA preparation requires a high level of purity. rHSA purified by means of Streamline technology is identical to plasma-derived HSA (pdHSA) with no detectable mannan component from P. pastoris.

The structural and functional properties of rHSA are similar to those of pdHSA. Preclinical and clinical trials have confirmed the safety and efficacy of using this rHSA preparation in different disease conditions, such as hemorrhagic shock, cirrhosis with ascites, and other critical clinical conditions related to plasma volume and oncotic pressure. In addition to its use as a plasma expander, rHSA has great potential as a biomaterial for other medical and pharmaceutically related applications

Chuang VT, Otagiri M.

School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.

Selection of an analytical method for evaluating bovine serum albumin concentrations in pharmaceutical polymeric formulations

noreply@blogger.com (Diagnostic Research) — Thu, 28 Jan 2010 19:34:00 +0000

Abstract
Bovine serum albumin (BSA) is a commonly used model protein in the development of pharmaceutical formulations. In order to assay its release from various dosage forms, either the bicinchoninic acid (BCA) assay or a more specific size-exclusion high performance liquid chromatography (SE-HPLC) method are commonly employed. However, these can give erroneous results in the presence of some commonly used pharmaceutical excipients. We therefore investigated the ability of these methods to accurately determine BSA concentrations in pharmaceutical formulations that also contained various polymers and compared them with a new reverse-phase (RP)-HPLC technique.

We found that the RP-HPLC technique was the most suitable method. It gave a linear response in the range of 0.5–100 μg/ml with a correlation co-efficient of 0.9999, a limit of detection of 0.11 μg/ml and quantification of 0.33 μg/ml. The performed ‘t’-test for the estimated and theoretical concentrations indicated no significant difference between them providing the accuracy. Low % relative standard deviation values (0.8–1.39%) indicate the precision of the method. Furthermore, the method was used to quantify in vitro BSA release from polymeric freeze-dried formulations.

Manish Umrethiaa, Vicky L. Kett, a, , Gavin P. Andrewsa, R. Karl Malcolma and A. David Woolfsona

a School of Pharmacy, Medical Biology Centre, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK

The redox state of human serum albumin in eye diseases with and without complications

noreply@blogger.com (Diagnostic Research) — Thu, 28 Jan 2010 19:33:00 +0000

ABSTRACT
Purpose: To investigate the redox state of human serum albumin concerning cysteine-34 as a possible systemic redox marker in patients with different eye diseases with and without complications and with consideration of possible effects of age.

Methods: Cataract (CAT), glaucoma, age-related macular degeneration (AMD), diabetes mellitus (DM), diabetic retinopathy and hypertension were the pathologies investigated. Albumin redox state concerning cysteine-34 was measured by high-performance liquid chromatography with fluorescence detection. The separation gives three fractions: the fully reduced form containing a thiol group, the disulphide form and a higher oxidized form. Statistical analysis was done by Student's t-test, analysis of variance and stepwise regression analysis.

Results: Albumin as a systemic marker for oxidative stress was shifted to a more oxidized state by DM. An even stronger shift to the oxidized form was observed in patients with proliferative diabetic retinopathy. Notably, these effects were independent from age. In contrast, CAT and AMD had no influence on serum albumin redox state.

Conclusion: Serum albumin is not shifted to more oxidized forms by localized oxidative stress, but it is in systemic diseases like DM.

Karl Oettl 1 , Gilbert Reibnegger 1 and Otto Schmut 2
1 Institute of Physiological Chemistry, Center for Physiological Medicine, Medical University of Graz, Graz, Austria
2 University Eye Hospital, Medical University of Graz, Graz, Austria

Spectroscopic and thermodynamic determination of three distinct binding sites for Co(II) ions in human serum albumin

noreply@blogger.com (Diagnostic Research) — Tue, 24 Nov 2009 18:38:00 +0000

Journal of Inorganic Biochemistry
Volume 103, Issue 7, July 2009, Pages 1005-1013

Abstract
Human serum albumin (HSA) is the most abundant protein of blood serum, involved in the transport of metal ions, including Co(II). Using circular dichroism spectroscopic titrations we characterized three distinct Co(II) binding sites in HSA. Applying Cu(II), Ni(II) and Cd(II) ions as competitors we determined that these sites are identical with three binding sites known for other metal ions. We ordered these sites according to their binding affinities as cadmium site B (CdB) > multi-metal binding site (MBS) > N-terminal binding site (NTS).

Using isothermal titration calorimetry (ITC) we confirmed the presence of these three binding sites and determined their conditional binding constants at pH 7.4 as 9 ± 5, 1.1 ± 0.5, and 0.9 ± 0.3 × 104 M−1, respectively. The impact of these results on the albumin cobalt binding (ACB) clinical assay for myocardial ischemia is discussed.

Magdalena Sokołowskaa, Małgorzata Wszelaka-Rylikb, Jarosław Poznańskib, c and Wojciech Balc, d, ,
aDepartment of Hygiene, Wroclaw Medical University, Mikulicza-Radeckiego 7, 50-368 Wroclaw, Poland
bInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
cInstitute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
dCentral Institute for Labour Protection – National Research Institute, Czerniakowska 16, 00-701 Warsaw, Poland

Oxidative Modification of Albumin in Predialysis, Hemodialysis, and Peritoneal Dialysis Patients

noreply@blogger.com (Diagnostic Research) — Thu, 20 Aug 2009 19:12:00 +0000

Mitrogianni Z, Barbouti A, Galaris D, Siamopoulos KC.
Department of Nephrology, Medical School, University of Ioannina, Ioannina, Greece.

Background/Aims: Oxidative damage has been reported to be involved in the pathophysiology of chronic kidney disease (CKD) as well as in the pathogenesis of cardiovascular complications of CKD patients. The aim of the present investigation was to evaluate the levels of plasma carbonyl formation, a sensitive marker of enhanced oxidative stress in predialysis, hemodialysis (HD) and peritoneal dialysis (PD) patients. Methods: Plasma samples from 20 apparently healthy control individuals and 127 CKD (stages 2, 3, 4, HD and PD) patients were evaluated by Western blot analysis for the estimation of the levels of protein carbonyl formation.

Results: Albumin represented the main plasma carbonylated protein. Increasing carbonylation of albumin was detected along with the severity of CKD, reaching significance at stages 3 and 4 (p < 0.01, compared to healthy controls). The carbonylation of albumin was even higher in the plasma of HD patients (p < 0.001), while in PD patients it was not statistically significant compared to controls (p = 0.224).

Conclusions: The data presented in this work indicate that oxidative stress in CKD patients gradually increased during the development of the disease. This stress is probably intensified during HD, but not in PD subjects.

Serum Albumin may not correlate with weight status

noreply@blogger.com (Diagnostic Research) — Wed, 08 Jul 2009 01:09:00 +0000

Anorexia nervosa is a difficult disease to treat effectively. Inpatient treatment in facilities with specialized expertise heightens the chance for success. Patients with the most severe degrees of anorexia nervosa are especially in need of hospitalization. Authorization from insurers can be a barrier to admitting these patients to reputable treatment facilities.

Therefore, familiarity with accurate markers of disease severity is important to understand in order to effectively advocate for these patients. Albumin , a commonly used marker for nutritional status is surprisingly normal even in patients with severe anorexia nervosa. Understanding that albumin levels do not correlate with the severity of anorexia nervosa is an important lesson to understand in the process of facilitating the most effective care settings for patients with severe anorexia nervosa
University of Colorado Health Sciences Center and Internal Medicine, Denver Health, Denver, Colorado, USA

Three new Cardiovascular Risk Markers -Do They Improve Risk Prediction and Influence Treatment

noreply@blogger.com (Diagnostic Research) — Mon, 22 Jun 2009 15:56:00 +0000

Urine Albumin/Creatinine Ratio, High Sensitivity C-Reactive Protein and N-Terminal Pro Brain Natriuretic Peptide -Three new Cardiovascular Risk Markers -Do They Improve Risk Prediction and Influence Treatment

In order to prioritize limited health resources in a time of increasing demands optimal cardiovascular risk stratification is essential. We tested the additive prognostic value of 3 relatively new, but established cardiovascular risk markers: N-terminal pro brain natriuretic peptide (Nt-proBNP), related to hemodynamic cardiovascular risk factors, high sensitivity C-reactive protein (hsCRP), related to metabolic cardiovascular risk factors and urine albumin/creatinine ratio (UACR), related to hemodynamic as well as metabolic risk factors. In healthy subjects with a 10-year risk of cardiovascular death lower than 5% based on HeartScore and therefore not eligible for primary prevention, the actual 10-year risk of cardiovascular death exceeded 5% in a small subgroup of subjects with UACR higher than the 95-percentile of approximately 1.6 mg/mmol. Combined use of high UACR or high hsCRP identified a larger subgroup of 16% with high cardiovascular risk in which primary prevention may be advised despite low-moderate cardiovascular risk based on HeartScore. Furthermore, combined use of high UACR or high Nt-proBNP in subjects with known cardiovascular disease or diabetes identified a large subgroup of 48% with extremely high cardiovascular risk who should be referred for specialist care to optimize treatment.

Olsen MH, Sehestedt T, Lyngbæk S, Hansen TW, Rasmussen S, Wachtell K, Torp-Pedersen C, Hildebrandt PR, Ibsen H.
Research Center for Prevention and Health, Gentofte University Hospital, Holbaek Hospital, Denmark

Interaction of perfluorooctanoic acid with human serum albumin.

noreply@blogger.com (Diagnostic Research) — Wed, 20 May 2009 00:40:00 +0000

ABSTRACT: BACKGROUND: Recently, perfluorooctanoic acid (PFOA) has become a significant issue in many aspects of environmental ecology, toxicology, pathology and life sciences because it may have serious effects on the endocrine, immune and nervous systems and can lead to embryonic deformities and other diseases. Human serum albumin (HSA) is the major protein component of blood plasma and is called a multifunctional plasma carrier protein because of its ability to bind an unusually broad spectrum of ligands.

RESULTS: The interaction of PFOA with Human serum Albumin was investigated in the normal physiological condition by equilibrium dialysis, fluorospectrometry, isothermal titration calorimetry (ITC) and circular dichroism (CD). The non-covalent interaction is resulted from hydrogen bond, van der Waals force e and hydrophobic stack. PFOA binding to Human Serum Albumin accorded with two-step binding model with the saturation binding numbers of PFOA, only 1 in the hydrophobic intracavity of Human Serum Albumin and 12 on the exposed outer surface. The interaction of PFOA with Human Serum Albumin is spontaneous and results in change of HSA conformation. The possible binding sites were speculated.

CONCLUSION: The present work suggested a characterization method for the intermolecular weak interaction. It is potentially useful for elucidating the toxigenicity of perfluorochemicals when combined w: BMC Struct Biol. 2009 May 14;9(1):31.ith biomolecular function effect, transmembrane transport, toxicological testing and the other experiments.

Protein glycation inhibitory activity of wheat bran feruloyl oligosaccharides

noreply@blogger.com (Diagnostic Research) — Fri, 08 Aug 2008 15:35:00 +0000

Protein glycation is believed to play an important role in the development of long-term disorders associated with diabetes. Water-soluble feruloyl oligosaccharides (FOs) from wheat bran, the ferulic acid esters of oligosaccharides, have been reported as natural antioxidants. The present work assesses the chelating activity of FOs and their inhibition of protein glycation in a bovine serum albumin (BSA)/glucose system, using fluorescence spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). FOs exhibited an effective ferrous ion chelating activity, and quenched the fluorescence intensity of glycated bovine serum albumin (BSA) in a dose-dependent manner with 64.0% of inhibition at 1.0 mg/ml. Further, the formation of advanced glycation end products in the tested system was significantly decreased by FOs, as shown by SDS–PAGE. These data indicate that FOs might be beneficial as glycation inhibitors under specified conditions.

ARTICLE

Human Serum Albumin Adsorption Study on 62-MHz Miniaturized Quartz Gravimetric Sensors

noreply@blogger.com (Diagnostic Research) — Wed, 23 Jul 2008 17:52:00 +0000

We have designed and fabricated 25-μm-thick quartz resonators operating at a fundamental resonance frequency of ~62 MHz. The results show a substantial increase in the mass sensitivity compared to single monolithic commercial resonators operating at lower frequencies in the ~5−10-MHz range. The overall performance of the micromachined resonators is demonstrated for the example of human serum albumin protein adsorption from aqueous buffer solutions onto gold electrodes functionalized with self-assembled monolayers. The results show a saturation adsorption frequency change of 6.8 kHz as opposed to 40 Hz for a commercial ~5-MHz sensor under identical loading conditions. From the analysis of the adsorption isotherm, the equilibrium adsorption constant of the adsorption of the protein layer was found to be K = 8.03 × 10^6 M^−1, which is in agreement with the values reported in the literature. The high sensitivity of the miniaturized QCM devices can be a significant advantage in both vapor and solution adsorption analyses.

The "albumin effect" and drug glucuronidation: bovine serum albumin and fatty acid-free human serum albumin enhance the glucuronidation of UDP-gluc...

noreply@blogger.com (Diagnostic Research) — Fri, 18 Jul 2008 14:40:00 +0000

Bovine serum albumin (BSA) and fatty acid-free human serum albumin (HSAFAF) reduce the K(m) values for UGT2B7 substrates by sequestering inhibitory long-chain fatty acids released by incubations of human liver microsomes (HLM) and HEK293 cells expressing this enzyme. However, the scope of the "albumin effect" is unknown. In this investigation we characterized the effects of albumin on the kinetics of 4-methylumbelliferone (4MU) glucuronidation by UDP-glucuronosyltransferase (UGT) 1A1, 1A6, and 1A9, and propofol (PRO) glucuronidation by UGT1A9 and HLM. Bovine serum albumin (BSA) and HSAFAF, but not human serum albumin, reduced the K(m) values for 4MU and PRO glucuronidation by UGT1A9. For example, HSAFAF (2%) reduced the K(m) values for 4MU and PRO glucuronidation from 13.4 to 2.9 and 41 to 7.2 microM, respectively. Similarly, HSAFAF (2%) reduced the K(m) for PRO glucuronidation by HLM from 127 to 10.6 muM. Arachidonic, linoleic, and oleic acids and a mixture of these decreased the rates of 4MU and PRO glucuronidation by UGT1A9. K(m) values for these reactions were increased 3- to 6-fold by the fatty acid mixture. Inhibition was reversed by the addition of BSA (2%). Extrapolation of kinetic constants for PRO glucuronidation by HLM in the presence of HSAFAF predicted in vivo hepatic clearance within 15%. Fatty acids had no effect on 4MU glucuronidation by UGT1A1 and UGT1A6 but, paradoxically, all forms of albumin altered the kinetic model for 4MU glucuronidation by UGT1A6 (from Michaelis-Menten to two-site). Only BSA caused a similar effect on 4MU glucuronidation by UGT1A1. It is concluded that BSA and HSAFAF reduce the K(m) values of only those enzymes inhibited by long-chain unsaturated fatty acids.

Engineering of a femtomolar affinity binding protein to human serum albumin

noreply@blogger.com (Diagnostic Research) — Fri, 18 Jul 2008 14:33:00 +0000

We describe the development of a novel serum albumin binding protein showing an extremely high affinity (KD) for Human Serum Albumin in the femtomolar range. Using a naturally occurring 46-residue three-helix bundle albumin binding domain (ABD) of nanomolar affinity for HSA as template, 15 residues were targeted for a combinatorial protein engineering strategy to identify variants showing improved HSA affinities. Sequencing of 55 unique phage display-selected clones showed a strong bias for wild-type residues at nine positions, whereas various changes were observed at other positions, including charge shifts. Additionally, a few non-designed substitutions appeared. On the basis of the sequences of 12 variants showing high overall binding affinities and slow dissociation rate kinetics, a set of seven ‘second generation’ variants were constructed. One variant denoted ABD035 displaying wild-type-like secondary structure content and excellent thermal denaturation/renaturation properties showed an apparent affinity for HSA in the range of 50–500 fM, corresponding to several orders of magnitude improvement compared with the wild-type domain. The ABD035 variant also showed an improved affinity toward serum albumin from a number of other species, and a capture experiment involving human serum indicated that the selectivity for Serum Albumin had not been compromised from the affinity engineering.

A study of the binding of C.I. Direct Yellow 9 to human serum albumin using optical spectroscopy and molecular modeling

noreply@blogger.com (Diagnostic Research) — Thu, 17 Jul 2008 15:03:00 +0000

The mechanism of interaction between C.I. Direct Yellow 9 and human serum albumin was studied using spectroscopic methods including fluorescence spectra, UV–vis, Fourier transform infrared (FT-IR) and circular dichroism (CD). The quenching mechanism was investigated in terms of the association constants, number of binding sites and basic thermodynamic parameters. The distance between the human serum albumin donor and the acceptor dye was 3.64 nm as derived from fluorescence resonance energy transfer. Alteration of the secondary protein structure in the presence of the dye was confirmed by UV, FT-IR and CD spectroscopy. Molecular modeling revealed that a dye–protein complex was stabilized by hydrophobic forces and hydrogen bonding, via amino acid residues.

ARTICLE

Antioxidant and antimicrobial activities of tea infusions

noreply@blogger.com (Diagnostic Research) — Tue, 15 Jul 2008 21:39:00 +0000

Tea polyphenols, especially the catechins, are potent antimicrobial and antioxidant agents, with positive effects on human health. White tea is one of the less studied teas but the flavour is more accepted than that of green tea in Europe. The concentrations of various catechins in 13 different kinds of infusion were determined by capillary electrophoresis. The total polyphenol content (Folin–Ciocalteu method), the trolox equivalent antioxidant capacity (TEAC value determined with the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation) and the inhibitory effects of infusions on the growth of some microorganisms were determined. Five different infusions (black, white, green and red teas and rooibos infusion) were added to a model food system, comprising a sunflower oil-in-water emulsion containing 0% or 0.2% bovine serum albumin (BSA), and the oxidative stability was studied during storage at 37 °C. Oxidation of the oil was monitored by determination of the peroxide value.

The highest radical-scavenging activity observed was for the green and white teas. Emulsions containing these extracts from these teas were much more stable during storage when bovine serum albumin (BSA) was present than when it was not present, even though BSA itself did not provide an antioxidant effect (at 0.2% concentration). Rooibos infusion did not show the same synergy with BSA. Green tea and white tea showed similar inhibitions of several microorganisms and the magnitude of this was comparable to that of the commercial infusion 2 (C.I.2), “té de la belleza”. This tea also had an antioxidant activity comparable to green tea.

ARTICLE

Probing the binding of morin to human serum albumin by optical spectroscopy

noreply@blogger.com (Diagnostic Research) — Tue, 15 Jul 2008 20:01:00 +0000

Morin [2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-benzopyran-4-one], a member of flavonols, is an important bioactive compound by interacting with nucleic acids, enzymes and protein. Its binding to human serum albumin was investigated by fluorescence quenching, fluorescence anisotropy, and UV–vis absorbance under the simulative physiological condition. Fluorescence quenching data show that the interaction of morin with human serum albumin forms a non-fluorescent complex with the binding constants of 1.394 × 105, 1.489 × 105, 1.609 × 105 and 1.717 × 105 M−1 at 292, 298, 303 and 310 K, respectively. The thermodynamics parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated to be 8.97 kJ mol−1 and 129.15 J mol−1 K−1 via van’t Hoff equation. From the spectroscopic results and thermodynamics parameters, it is observed that van der Waals and hydrogen bonds are predominant intermolecular forces when forming the complex. The distance r = 4.25 nm between donor (Trp214) and accepter (morin) was estimated based on the Förster theory of non-radiative energy transfer. The red shift of UV–vis absorbance shows that morin is bound to several amino acids on the hydrophobic pocket of HSA. Moreover, the competitive probes, such as warfarin and ibuprofen (site I and II probes, respectively), reveal that the binding location of morin to HSA in the site I of the hydrophobic pocket, which corresponds to the results of UV–vis absorbance, while morin also binds other lower affinity binding sites on human serum albumin from the fluorescence anisotropy spectroscopy.

ARTICLE

Human Serum Albumin Adsorption Study on 62-MHz Miniaturized Quartz Gravimetric Sensors

noreply@blogger.com (Diagnostic Research) — Tue, 15 Jul 2008 19:56:00 +0000

We have designed and fabricated 25-μm-thick quartz resonators operating at a fundamental resonance frequency of ~62 MHz. The results show a substantial increase in the mass sensitivity compared to single monolithic commercial resonators operating at lower frequencies in the ~5−10-MHz range. The overall performance of the micromachined resonators is demonstrated for the example of human serum albumin protein adsorption froHSAm aqueous buffer solutions onto gold electrodes functionalized with self-assembled monolayers. The results show a saturation adsorption frequency change of 6.8 kHz as opposed to 40 Hz for a commercial ~5-MHz sensor under identical loading conditions. From the analysis of the adsorption isotherm, the equilibrium adsorption constant of the adsorption of the protein layer was found to be K = 8.03 × 10^6 M^−1, which is in agreement with the values reported in the literature. The high sensitivity of the miniaturized QCM devices can be a significant advantage in both vapor and solution adsorption analyses.

Binding interaction of indomethacin with human serum albumin

noreply@blogger.com (Diagnostic Research) — Wed, 02 Jul 2008 20:53:00 +0000

The interaction between indomethacin and human serum albumin (HSA) was investigated by fluorescence quenching technique and UV–vis absorption spectroscopy. The results of fluorescence titration revealed that indomethacin, strongly quench the intrinsic fluorescence of HSA by static quenching and nonradiative energy transfer. The binding site number n and the apparent binding constant KA, were calculated using linear and nonlinear fit to the experimental data. The distance r between donor (HSA) and acceptor (indomethacin) was obtained according to fluorescence resonance energy transfer (FRET). The study suggests that the donor and the acceptor are bound at different locations but within the quenching distance.

ARTICLE

Reactivity of sulfenic acid in human serum albumin.

noreply@blogger.com (Diagnostic Research) — Wed, 02 Jul 2008 20:51:00 +0000

Sulfenic acid is formed upon oxidation of thiols and is a central intermediate in the redox modulation of an increasing number of proteins. Methods for quantifying or even detecting sulfenic acid are scarce. Herein, the reagent 7-chloro-4-nitrobenz-2-oxa-1,3-diazole was determined not to be suitable as a chromophoric probe for sulfenic acid in human serum albumin (HSA-SOH) because of lack of specificity. Thionitrobenzoate (TNB) reacted with HSA exposed to hydrogen peroxide, but not control or thiol-blocked HSA. The reaction was biphasic. The first phase was approximately 20-fold faster than the second phase and first order in HSA-SOH and TNB (105 +/- 11 M-1 s-1, 25 degrees C, pH 7.4), allowing quantitative data on HSA-SOH formation and reactivity to be obtained. Exposure of reduced human serum albumin (0.5 mM) to hydrogen peroxide (4 mM, 37 degrees C, 4 min) yielded 0.18 +/- 0.02 mol of HSA-SOH per mol of HSA. HSA-SH reacted with hydrogen peroxide at 2.7 +/- 0.7 M-1 s-1 (37 degrees C, pH 7.4), while HSA-SOH reacted at 0.4 +/- 0.2 M-1 s-1, yielding sulfinic acid (HSA-SO2H), as detected by mass spectrometry. The rate constants of HSA-SOH with targets of analytical interest such as dimedone and sodium arsenite were determined. HSA-SOH did not react appreciably with the plasma reductants ascorbate or urate, nor with free basic amino acids. In contrast, HSA-SOH reacted rapidly with the plasma thiols cysteine, glutathione, homocysteine, and cysteinylglycine at 21.6 +/- 0.2, 2.9 +/- 0.5, 9.3 +/- 0.9, and 55 +/- 3 M-1 s-1 (25 degrees C, pH 7.4), respectively, supporting a role for HSA-SOH in the formation of mixed disulfides.

Serum Albumin Level as a Predictor of Outcome in Traumatic Brain Injury

noreply@blogger.com (Diagnostic Research) — Fri, 23 May 2008 21:00:00 +0000

Abstract:
Background: Serum albumin level is correlated with outcome in various clinical situations. Albumin has multiple physiologic properties that could be beneficial in brain injury. The Lund therapy for elevated intracranial pressure uses albumin as part of its protocol and demonstrates favorable outcome. We sought to find out if albumin is associated with outcome after traumatic brain injury to justify conducting a randomized trial.

Methods:
A retrospective study of traumatic brain injury patients was conducted. Characteristics known to influence outcome were included in a multiple logistic regression model to analyze predictors of poor outcome at 6 months.

Results:
Data were available for 138 patients. The majority of patients (65%) had a severe injury (Glasgow Coma Scale score <9). Seventy percent of patients had a favorable outcome. Albumin levels decrease considerably from normal values in the first few days after injury irrespective of outcome. albumin remained <25 g/L for a longer period of time in patient with an unfavorable outcome (6 days vs. 3 days, p = 0.012). Multiple logistic regression analysis identified albumin levels, age, Glasgow Coma Scale score at admission, and Injury Severity Score as predictors of poor outcome.

Conclusion:
Serum albumin level seems to be an independent predictor of poor outcome. The model also identified classic predictors of poor outcome that tends to strengthen its adequacy. Because albumin level is the only modifiable factor influencing outcome, it seems justified to carry out a randomized trial of the use of albumin in the treatment of brain injury.

Journal of Trauma-Injury Infection & Critical Care. 64(4):872-875, April 2008.
Bernard, Francis MD, FRCPC; Al-Tamimi, Yahia Z. MD; Chatfield, Doris BSc; Lynch, Andrew G.; Matta, Basil F. FRCA; Menon, David K. MD, PhD, FRCP, FMedSci

Serum albumin and mortality in very low birth weight infants

noreply@blogger.com (Diagnostic Research) — Tue, 29 Jan 2008 20:33:00 +0000

Serum albumin is a predictor of outcome in adults but its role in paediatric patients is unclear. Earliest albumin was not associated with mortality or morbidity in very low birth weight (VLBW) infants. However the lowest serum albumin had a statistically significant inverse correlation with mortality and potentially plays a prognostic role in VLBW neonates .

Arch Dis Child Fetal Neonatal Ed. 2008 Jan 24. Morris I, McCallion N, El-Khuffash A, Molloy EJ. National Maternity Hospital, Dublin, Republic of Ireland.

Hypoalbuminemia

noreply@blogger.com (Diagnostic Research) — Thu, 20 Dec 2007 19:29:00 +0000

What is hypoalbuminemia?

Hypoalbuminemia is a deficit of albumin in the blood, more often seen in elderly patients. Albumin is a protein that is found in the blood. Hypoalbuminemia is a medical condition where levels of albumin in blood serum are abnormally low. It is a specific form of hypoproteinemia.

Albumin is a major protein in the human body, making up about 60% of total human plasma protein by mass. Many hormones, drugs, and other molecules are mostly bound to albumin in the bloodstream and must be released before becoming biologically active.

Albumin is synthesized in the liver , and low serum albumin may be indicative of liver failure or diseases such as cirrhosis or chronic hepatitis. Hypoalbuminemia can also present as part of the nephrotic syndrome, in which protein is lost in the urine due to kidney damage. Low albumin levels can be an indicator of chronic malnutrition.

Hypoalbuminemia may cause generalized edema (swelling) via a decrease in oncotic pressure.

The serum albumin level is part of a standard panel of liver function tests . Levels below 3.5 grams per deciliter are generally considered low.

There are many causes of low serum albumin levels . These causes may include:

Poor nutritional state - you haven't been eating enough protein, or you may be losing protein, usually during a period of illness

Increased excretion (or loss) of albumin from your body from:
Renal ( kidney ) dysfunction - your kidneys may not work well due to any number of conditions. They may be leaking albumin in the urine , causing hypoalbuminemia
You may have some form of liver disease, such as hepatitis , or cancer in your liver, which may have spread from elsewhere in your body that causes you to lose albumin, thus resulting in hypoalbuminemia.

Certain heart conditions - such as congestive heart failure , or pericarditis - may cause you to have low albumin levels in your blood.

Problems with your stomach - including inflammatory bowel disease, or lymphoma , can cause hypoalbuminemia

Other forms of cancer or conditions- such as sarcoma or amyloidosis - can cause hypoalbuminemia

Side effects from medications can cause hypoalbuminemia
Infections - such as tuberculosis - can cause hypoalbuminemia

What are some symptoms and side effects of hypoalbuminemia to look for?

You may not have any symptoms, unless your blood albumin levels are significantly lowered. In this case, you may not be eating very well. You may have swelling that is all over your body, or swelling in one part of your body (such as your legs)
You may have muscle weakness , fatigue, or cramps
You may have a poor appetite, and may not be eating well. Even people who take in a lot of protein in their diet may still have low albumin levels in their blood.
If you have liver problems that may have caused your hypoalbuminemia, you may notice that your abdomen is swollen with fluid (called, ascites ).

Genetic Engineering of the Heme Pocket in Human Serum Albumin: Modulation of O2 Binding of Iron Protoporphyrin IX by Variation of Distal Amino Acids

noreply@blogger.com (Diagnostic Research) — Tue, 27 Nov 2007 14:39:00 +0000

Complexing an iron protoporphyrin IX into a genetically engineered heme pocket of recombinant human serum albumin (rHSA) generates an artificial hemoprotein, which can bind O2 in much the same way as hemoglobin (Hb). We previously demonstrated a pair of mutations that are required to enable the prosthetic heme group to bind O2 reversibly: (i) Ile-142 His, which is axially coordinated to the central Fe2+ ion of the heme, and (ii) Tyr-161 Phe or Leu, which makes the sixth coordinate position available for ligand interactions [I142H/Y161F (HF) or I142H/Y161L (HL)]. Here we describe additional new mutations designed to manipulate the architecture of the heme pocket in rHSA-heme complexes by specifically altering distal amino acids. We show that introduction of a third mutation on the distal side of the heme (at position Leu-185, Leu-182, or Arg-186) can modulate the O2 binding equilibrium. The coordination structures and ligand (O2 and CO) binding properties of nine rHSA(triple mutant)-heme complexes have been physicochemically and kinetically characterized. Several substitutions were severely detrimental to O2 binding: for example, Gln-185, His-185, and His-182 all generated a weak six-coordinate heme, while the rHSA(HF/R186H)-heme complex possessed a typical bis-histidyl hemochrome that was immediately autoxidized by O2. In marked contrast, HSA(HL/L185N)-heme showed very high O2 binding affinity (P1/2O2 1 Torr, 22 C), which is 18-fold greater than that of the original double mutant rHSA(HL)-heme and very close to the affinities exhibited by myoglobin and the high-affinity form of Hb. Introduction of Asn at position 185 enhances O2 binding primarily by reducing the O2 dissociation rate constant. Replacement of polar Arg-186 with Leu or Phe increased the hydrophobicity of the distal environment, yielded a complex with reduced O2 binding affinity (P1/2O2 9-10 Torr, 22 C), which nevertheless is almost the same as that of human red blood cells and therefore better tuned to a role in O2 transport.

Human serum albumin levels and cardiovascular risk factors in elderly Japanese-American men: the Honolulu Heart Program.

noreply@blogger.com (Diagnostic Research) — Wed, 24 Oct 2007 22:02:00 +0000

The objective of this study is to investigate the relationship between low levels of human serum albumin (HSA) and the incidence of coronary heart disease (CHD) in a cohort of elderly Japanese-American men. Using data from the Honolulu Heart Program's fourth examination (1991-1993), Human Serum Albumin levels of 998 Japanese American men aged 71-93 years was compared with plasma levels of fibrinogen, total cholesterol, HDL cholesterol , LDL cholesterol , triglycerides , diastolic BP, BMI, and fasting blood glucose . Human Serum Albumin was significantly negatively associated with age and fibrinogen, and significantly positively associated with total cholesterol, HDL cholesterol , LDL cholesterol , triglycerides , diastolic BP, BMI and fasting blood glucose. After adjusting for age, tertiles of Human Serum Albumin were significantly positively associated with total cholesterol, HDL cholesterol and triglycerides, and significantly negatively associated with fibrinogen.

Using multivariate stepwise regression, significant correlations were seen between human serum albumin Albumin and fibrinogen, cholesterol, age, "High Density Lipoprotein" cholesterol and triglycerides, and a borderline correlation was seen with systolic blood pressure. However, the model R-square for all variables was only 0.10. In conclusion, human serum albumin Human Serum Albumin levels are significantly associated with several traditional cardiovascular risk factors, particularly serum lipid levels.
PMID: 17621861 [PubMed - indexed for MEDLINE]