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Detecting B-Type Natriuretic Peptide to Better Diagnose
Congestive Heart Failure “Where there is stress, there is BNP.”
Greenfield High School SMART Team: Tammy Tian, Jordan Tian, Panfua Thao, Robin Sandner, My Nguyen, Guetzie Maya, Elizabeth Konieczny, Amber Inman,
Chi Huynh, Marlene Hagen, Hope Gueller, Nick Evers, Brayden Campagna, Tania Alvarez, Jodi Allison
Teachers: Julie Fangmann and Martin Volk
Mentor: Shama Mirza, Ph.D., Medical College of Wisconsin
Abstract
There are about 400,000 new cases of congestive heart failure (CHF) every year
in the United States. CHF is a disease that interferes with the heart’s ability to
pump blood efficiently throughout the body. Major symptoms of CHF are fatigue,
shortness of breath, nausea, sleeplessness, and swelling of the heart, lungs, and
legs. One indicator of CHF is B-type Natriuretic Peptide (BNP), a hormone
released due to stress on heart ventricles. A biologically active BNP molecule
consisting of 32 amino acids (BNP-32) results from proteolytic cleavage of the
precursor protein (originally 134 amino acids long). While CHF patients have a
high concentration of BNP, high levels of BNP are not always due to CHF. BNP32 indirectly regulates sodium and water levels to reduce swelling. Natriuretic
peptides, like BNP, do this by causing vasodilation and decreasing levels of certain
chemicals that cause swelling. One of the receptors of BNP is Natriuretic Peptide
Receptor-C (NPR-C), a clearance receptor found in the heart and other organs.
When BNP binds to NPR-C, BNP is removed from the bloodstream and broken
down, and swelling in that area reduces. Since CHF patients have a large amount
of BNP, the receptors are unable to break down all of it and the swelling remains.
Continual stress and swelling can be fatal. A way to measure the level of BNP in
vivo could diagnose CHF before it becomes serious. Scientists are currently
working on this through quantification of BNP using mass spectrometry (MS)based technology.
Congestive Heart Failure
Congestive heart Failure (CHF) is a condition where the heart insufficiently pumps
oxygen-rich blood. Each year, there are 400,000 new cases in the United States.
Some Causes of CHF:
•High Blood Pressure ( hypertension)
•Long term alcohol abuse
•Disorders of the heart valves
Symptoms of CHF:
•Swelling of heart, lungs and legs
•Fatigue
•Shortness of breath
•Wheezing
•Chest Pain
•Pneumonia
•Nausea
•Sleeplessness
.
The Role of BNP in the Heart
2. Different types of natriuretic peptide
hormones (including BNP) are released
due to the stress and swelling in the heart.
1. Stress and swelling of the heart
(potentially due to CHF).
BNP
NPR-C
4. Natriuretic Peptide Receptor-C
(NPR-C) is a clearance receptor
that removes circulating
natriuretic peptides (such as BNP).
6. In a CHF heart, BNP levels
continue to elevate as the heart
produces more than NPR-C can
remove. This cycle continues until
the stress on the heart is relieved
or the heart ultimately fails.
5. In a healthy heart, BNP levels
reduce. Swelling and stress on the
heart also return to normal levels.
Future Research Using Mass Spectrometry to Better Diagnose CHF
Mass Spectrometer
Inlet
Ion Source
Sample
introduction
Generates gas
phase ions
e.g. MALDI
Mass Analyser(s)
Separates ions by m/z and fragments ions
Detector
Computer
Counts number
of ions for each
m/z
e.g. electron
multiplier
•The best current bed-side CHF diagnosis equipment is
only 81% accurate. Better methods of detecting BNP
levels could help diagnose CHF patients.
Instrument
control and data
acquisition
Vacuum Chamber
*
CHF’s Connection to BNP
O
•CHF patients have a high amount of stress on their
hearts. This stress triggers the release of B-Type
Natriuretic Peptide (BNP) into the bloodstream.
*
O
Light isotope
* Heavy isotope
*with heavy isotopes
•BNP is a protein naturally found in the human
body, but CHF patients have a higher concentration
of BNP.
•A high concentration of BNP is only an indicator
of CHF, but does not cause the disease.
3. These hormones signal
other molecules to regulate
salt and water levels in
order to relieve swelling.
•A mass spectrometer (MS) is an instrument that can
identify and quantify molecules, such as BNP. The
quantity of the desired molecule can be identified by
adding the same molecule of known concentration, but
with a heavy isotope .
Multiple Reaction Monitoring
BNP (B-Type Natriuretic Peptide)
MRM of
pdb file: 1YK1
Sources:
http://www.medicinenet.com/congestive_heart_failure/article.htm; Images and data from the Mirza lab; pdb file: 1YK1
from He, X.L., Dukkipati, A., and Garcia, K.C.’s Structural determinants of natriuretic peptide receptor specificity and
degeneracy. Reference: Hawkridge et al.PNAS 102 (2005) 17442
Ion
source
Analyzer Q1
Analyzer Q2
(collision cell)
Analyzer Q3
Data Signal
•One of the MS-based approaches, multiple reaction
monitoring, combines several mass spectrometry tests to
get a result with the greatest sensitivity and selectivity for
measuring BNP. Scientists hope these methods will lead
to a better method for early CHF diagnosis.
SMART Teams are supported by the National Institutes of Health (NIH)- National Center for Research Resources-Science Education Partnership Award (NCRR-SEPA), and an NIH CTSA Award to the Medical College of Wisconsin.