Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels increase in patients with heart failure with the progression of clinical symptoms and with the deterioration of hemodynamics; consequently, assay methods for these peptides may be useful in the follow-up of cardiac patients. Non-competitive immunoradiometric assay (IRMA) methods for ANP or BNP do not generally require preliminary extraction and/or purification of the plasma sample, and so may be more suitable than competitive immunoradiometric assay (RIA) methods for the routine assay of plasma peptide concentrations. We evaluated the analytical characteristics and clinical usefulness of two IRMAs for plasma ANP and BNP, to verify whether these methods may be considered suitable for the follow-up of patients with heart failure. Both methods are based on the solid-phase sandwich IRMA system, which uses two monoclonal antibodies prepared against two sterically remote epitopes of peptide molecule; the first antibody was coated on the beads solid-phase and the second was radiolabeled with 125I. Blood samples were collected from a brachial vein in ice-chilled disposable polypropylene tubes containing aprotinin and EDTA after the patient had rested for at least 20 min in the recumbent position. Plasma samples were immediately separated by centrifugation and stored at -20 C until assay. The IRMA methods showed a better sensitivity and a wider working range sensitivity (about 2 ng/l) than those of RIA methods. Moreover, the normal range found with these methods (ANP = 16.1 +/- 8.6 ng/l, 5.2 +/- 2.8 pmol/l, BNP = 8.6 +/- 8.2 ng/l, 2.5 +/- 2.4 pmol/l) was similar to that generally reported using the most accurate methods, such as the other IRMAs or RIAs, using a preliminary extraction and purification of plasma samples with chromatographic procedures. Our results obtained in patients with different degrees of heart failure indicate that plasma ANP and BNP increase with the progression of clinical symptoms (NYHA class) (ANOVA p < 0.0001). Indeed, circulating levels of ANP (R = -0.701, no. = 86) and BNP (R = -0.745, no. = 55) were significantly (p < 0.0001) and negatively correlated with the left ventricular ejection fraction values. Furthermore, a close curvilinear regression (R = 0.960, no. = 215) was found between ANP and BNP values, because plasma BNP progressively increases more than plasma ANP in patients with different stages of heart failure. In conclusion, IRMA methods are preferable for the measurement of plasma ANP and BNP for experimental studies and routine assay because they are more practicable, sensitive and accurate than RIA procedures. Finally, BNP assay appears to be better than ANP for discriminating between normal subjects and patients with different degrees of heart failure.

Circulating levels of cardiac natriuretic peptides (ANP and BNP) measured by highly sensitive and specific immunoradiometric assays in normal subjects and in patients with different degrees of heart failure

Creatine Kinase Isoenzymes

Backgound:

C-type natriuretic peptide (CNP), secreted by the endothelium and the heart, is structurally related to atrial and brain natriuretic peptides, but its clinical significance in chronic heart failure (CHF) is controversial.



Aim:

To investigate the role of CNP in CHF, plasma CNP levels were determined in a prospective series of 133 patients with CHF (age 64±1 years, left ventricular ejection fraction (EF), 31.5±0.7%, mean±S.E.M.) and in 21 age-matched healthy subjects.



Methods and results:

CNP was measured by a radioimmunoassay (sensitivity: 0.41±0.009 pg/tube) after a preliminary solid-phase extraction. Plasma level of CNP in healthy subjects was 2.7±0.2 pg/ml and significantly increased in CHF, as a function of clinical severity: 4.9±0.7 pg/ml in NYHA class I; 7.0±0.4 pg/ml in class II (p<0.001 vs. controls); 9.6±0.7 pg/ml in class III (p<0.001 vs. controls and class I and II), and 11.8±2.0 pg/ml in class IV (p<0.001 vs. controls, class I and II; Fisher's test after ANOVA). A significant relation was also found between CNP plasma levels and EF (R=0.40, p<0.001).



Conclusion:

Plasma CNP elevation is related to clinical and functional disease severity. These findings suggest a pathophysiological role for this peptide that, for its vasorelaxing activity, could influence the endothelial vasomotor response in CHF.

https://onlinelibrary.wiley.com/doi/pdf/10.1016/j.ejheart.2004.12.009

C‐type natriuretic peptide plasma levels increase in patients with chronic heart failure as a function of clinical severity

Expression of C-type natriuretic peptide and its receptor NPR-B in cardiomyocytes.

Lactate dehydrogenase isoenzymes.

Main features of computer algorhythms for RIA data reduction; comparison of some different approaches for the interpolation of the dose-response curve.

Radioimmunoassay of circulating human myoglobin

Radioimmunoassay of acute myocardial infarction markers (myoglobin, creatine kinase MB and lactate dehydrogenase H4).

Antisera to H4-lactate dehydrogenase (LDH) were elicited in rabbits, against both human (h) and porcine (p) isoenzymes. 
125I-labelled H4-LDH was prepared by electrolytic iodination. A simple and fast procedure (1-h incubation for clinical assays) was set up by using polyethylene glycol for the bound-free separation. The results obtained in the antiserum characterization indicated that the heterologous homotetramer, M4 was completely discriminated in the porcine system while a weak cross-reaction with human antisera resulted. In both cases, for the hybrid forms, a crossreactivity level related to the stoichiometric contents of the H-subunit in the tetramers was observed. The H4-LDH from other species was found to be much more effectively disinguished in the porcine than in the human system. The assay for human LDH was further validated in terms of analytical suitability and clinical response. For healthy subjects the mean concentration was 0.46±0.19μg/ml (mean±SD). Patients with acute myocardial infarction had levels ranging from 1.2 to 5.9μg/ml.

Radioimmunoassay of lactate dehydrogenase, H forms

Are TSH immunoassays fully adequate in discrinate among low hormone values

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

R. Malvano

Author Tools

Chat about Author