Establishment Of CEDIA For B-type Natriurtic Peptide (BNP) And Primary Clinical Use

Heart failure (CHF) is one of the most important health problems of our population. We not only have difficulty diagnosing CHF, we also have difficulty assessing the results of treatment. Heart failure has historically been defined as a syndrome, and often diagnosed based on patient's clinical signs and symptoms. Unfortunately, the signs and symptoms of CHF are nonspecific. Radiographic (X-ray), electrocardiography, and hemodynamic evaluations are also not accurate enough to make the appropriate diagnosis, sometimes they yield conflicting results in patients with CHF. Although echocardiography is considered the gold standard for detecting left ventricular(LV) dysfunction, it is expensive, not easily accessible and may not always reflect an acute condition. As such, no single finding is pathognomonic, heart failure is often misdiagnosed, particularly in primary care. Several studies reported that nearly 40% suspected CHF patients could not get a rapid and accurate diagnosis, and up to 12% patients were misdiagnosed. So finding a biomarker (or a simple blood test) that would aid in the diagnosis and managements of patients with CHF is a popular study area of cardiology and lab medicine.Brain natriuretic peptide, firstly discovered by Sudoh T, now named as B type natriuretic peptide(BNP), was regarded as a good biomarker for the diagnosis , severity, treatment , and prognosis of CHF. BNP is a cardiac neurohormone that is secreted by the left ventricle in response to an increase in wall stress. BNP is synthetized as pre-proBNP form, secondary cleaved in proBNP, itself equimolarly cleaved in BNP and NT-proBNP. The active BNP is a 32-aapolypeptide containing a 17-aa ring structure (through SH between the 7aa and 23aa ) .It helps regulate blood pressure and fluid balance by counterbalancing the rennin-angiontensin system.The biological action of BNP is mediated by the NPR-A receptor. This peptide is eliminated from the systemic circulation by a neutral endopeptidase and by a clearance receptor (NPR-C).BNP has emerged as a neurohormone with multiple roles in heart failure management. From the available data, measurement of plasma BNP concentrations has several potential uses: BNP as a test for heart failure diagnosis and prognosis; Using BNP to predict outcome in HF; BNPin assessing right ventricular dysfunction; Monitoring response to heart failure therapy; Predicting intracardiac pressures; and etc.Although the measurement of plasma BNP concentrations has several potential uses, this test has not been widely used in clinical ,especially in China. The main reason is the limitation of BNP detecting test. Several assays for BNP such as radioimmunoassay (R1A), immunoradiometric assay (IRMA), Enzyme linked immunoassay (ELISA), and fluorescence immunoassay, have been reported. RIA and IRMA assays for BNP use radiolabelled ligand in a competitive binding assay format. Such ligands are often unstable and have to be utilized before radioactive decay renders them unusable. Moreover, radiation protection and disposal need to be considered and add to the cost. Also those tests require a 2-days testing time. The 'Triage' BNP test from Biosite Diagnostics is the first one which received Federal Drug Administration approval. It is a rapid bedside (point of care, 15 min) test based on fluorescence immunoassay, but requires $25 per test and a special device. To establish new BNP method which is easy to run and low cost is still a hot study point now. There is no methodology study report in China.Cloned enzyme donar immunoassay (CEDIA), which invented by Henderson DR., represent a state of the art technique utilizing two genetically engineered, enzymatically inactive fragments of P-galactosidase as the basis for a homogeneous immunoassay. The smaller, amino-terminal polypeptide, designated the enzyme donor (ED), can recombine spontaneously with the large residual fragment, called the enzyme acceptor (EA), to form active 8-galactosidase,in a process called complementation. ED have been designed in such a way that a ligand, such as a hormone...