Development and evaluation of an immuno-MALDI iMALDI assay for angiotensin I and the diagnosis of secondary hypertensionReport as inadecuate




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Clinical Proteomics

, 10:20

First Online: 20 December 2013Received: 20 September 2013Accepted: 13 November 2013

Abstract

Plasma renin activity PRA is an essential analytical tool for screening and diagnosis of secondary forms of hypertension. Typically, PRA is measured by competitive radioimmunoassay, but there are significant drawbacks to this technique including non-specificity, long analysis times, narrow calibration range, and the requirement for radionucleotides. In this paper, we report a method for plasma renin activity determination by immuno-MALDI mass spectrometry detection. This method overcomes the issues of non-specificity and long analytical times present with RIA, and does not require the use of radionucleotides. As an initial methodological evaluation, plasma renin activity results obtained by radioimmunoassay, LC-ESI-MS-MS, and immuno-MALDI on 64 samples from an outpatient primary aldosteronism screening program have been compared. A strong correlation was found between immuno-MALDI and radioimmunoassay R = 0.9412, 62-64 within the 95% CI of the Bland-Altman plot, and iMALDI and LC-ESI-MS-MS R = 0.9471, 62-64 within the 95% CI of the Bland-Altman plot. Technical replicates showed a 4.8% CV, while inter- and intra-day replicates showed CVs of 17.3% and 17.2% respectively. We have developed an assay capable of measuring PRA without the use of radionucleotides. This immuno-MALDI approach affords the specificity of MS while avoiding the long analytical run times and technical problems associated with HPLC. With the use of robotic sample preparation to optimize precision, this assay should be adaptable to clinical environments.

KeywordsHypertension Angiotensin-I Plasma renin activity PRA iMALDI Immuno-MALDI AbbreviationsRAASRenin-angiotensin-aldosterone system

PAPrimary aldosteronism

Ang-IAngiotensin-I

ACEAngiotensin-converting-enzyme

Ang-IIAngiotensin-II

PRAPlasma renin activity

PRCPlasma renin concentration

iMALDIImmuno-MALDI

SPESolid-phase extraction

SPHSt. Paul’s Hospital

RTRoom temperature

UVicUniversity of Victoria

FAFormic acid

SISStable-isotope labelled internal standard

pAbPolyclonal antibody

CHCAα-Cyano-4-hydroxycinnamic acid

RRRelative response

R2Coefficient of determination.

Electronic supplementary materialThe online version of this article doi:10.1186-1559-0275-10-20 contains supplementary material, which is available to authorized users.

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Author: Alexander G Camenzind - Jessica Grace van der Gugten - Robert Popp - Daniel T Holmes - Christoph H Borchers

Source: https://link.springer.com/







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