C-reactive protein (CRP), a molecule produced by the liver in response to inflammation, normally accounts for less than 1/60,000 of a person’s total serum protein, or about 1 milligram per liter (mg/L) of serum.
Recent evidence suggests that a CRP level between 1 and 3 mg/L indicates a moderate risk of cardiovascular disease while a level greater than 3 mg/L predicts a high risk. A clinical diagnostic procedure known as the high-sensitivity CRP (hsCRP) test has been used to detect higher-than-normal levels of the protein and warn a patient about elevated risk for cardiovascular disease.
However, there is no certified reference material—in this case, a sample of human serum with accurately determined amounts of the CRP for various risk levels—against which the accuracy of methods for measuring CRP can be evaluated. The problem: normal, low-risk of cardiovascular disease CRP levels are so low that even mass spectrometry (a very sensitive technique for separating and identifying molecules based on mass) cannot easily quantify them.
In a recent paper in Analytical Chemistry,* NIST researchers Eric Kilpatrick and David Bunk describe the first steps toward development of a certified reference material that can be used to assess the accuracy of routine clinical laboratory tests for CRP. The researchers accomplished this by isolating the minute amounts (less than 1 mg/L) of CRP circulating at normal levels in serum prior to measurement. Using a protein isolation technique called affinity purification, Kilpatrick and Bunk added polystyrene beads coated with anti-CRP antibodies to normal human serum. The antibodies bind tightly to any circulating CRP, allowing it to be easily removed from solution. The researchers then cleave the purified protein they isolated into its component parts, known as peptides, using enzyme digestion. The peptides are more readily measured by the mass spectrometer, resulting in a very precise determination of the total CRP.
To see if their purification method yields CRP that can serve as a reference material, Kilpatrick and Bunk will next mix purified CRP with genetically engineered CRP containing a heavy isotope of nitrogen (15N) and then run the combined pool through affinity purification, enzyme digestion and mass spectrometry. The peptides with the heavy 15N atoms will be easily detected and precisely quantified by the mass spectrometer. If the measurements for the 15N-tagged peptides compare favorably to those made for the purified serum CRP, then that will validate the use of the affinity purification method for quantifying extremely low levels of the protein. In turn, this validation will clear the way for purified serum CRP derived by the NIST method to be eventually used as a quality control and calibration tool by manufacturers for the hsCRP test.
Michael E. Newman | Newswise Science News
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research