Navigation Links
Imaging probe allows noninvasive detection of dangerous heart-valve infection

A novel imaging probe developed by Massachusetts General Hospital (MGH) investigators may make it possible to diagnose accurately a dangerous infection of the heart valves. In their Nature Medicine report, which is receiving advance online publication, the team from the MGH Center for Systems Biology describes how the presence of Staphylococcus aureus-associated endocarditis in a mouse model was revealed by PET imaging with a radiolabeled version of a protein involved in a process that usually conceals infecting bacteria from the immune system.

"Our probe was able to sense whether S. aureus was present in abnormal growths that hinder the normal function of heart valves," says Matthias Nahrendorf, MD, PhD, of the MGH Center for Systems Biology, a co-lead author of the study. "It has been very difficult to identify the bacteria involved in endocarditis, but a precise diagnosis is important to steering well-adjusted antibiotic therapy."

An infection of the tissue lining the heart valves, endocarditis is characterized by growths called vegetations made up of clotting components such as platelets and fibrin along with infecting microorganisms. Endocarditis caused by S. aureus is the most dangerous, with a mortality rate of from 25 to almost 50 percent, but diagnosis can be difficult since symptoms such as fever and heart murmur are vague and blood tests may not detect the involved bacteria. Without appropriate antibiotic therapy, S. aureus endocarditis can progress rapidly, damaging or destroying heart valves.

S. aureus bacteria initiate the growth of vegetations by secreting staphylocoagulase, an enzyme that sets off the clotting cascade. This process involves a protein called prothrombin, which is part of a pathway leading to the deposition of fibrin, a primary component of blood clots. The clotting process enlarges the vegetation, anchors it to the heart valve and serves to conceal the bacteria from immune cells in the bloodstream.

To develop an imaging-based approach to diagnosing S. aureus endocarditis, the MGH team first investigated the molecular mechanism by which staphylocoagulase sets off the clotting cascade, finding that one staphylocoagulase molecule interacts with at least four molecules of fibrin or its predecessor molecule fibrinogen in a complex that binds to a growing vegetation. Since prothrombin is an essential intermediary in the staphylocoagulase/fibrin interaction, the researchers investigated whether labeled versions of prothrombin could accurately detect S. aureus endocarditis in mice.

After initial experiments confirmed that an optical imaging technology called FMT-CT could detect a fluorescence-labeled version of prothombin deposited into S. aureus-induced vegetations, the researchers showed that a radiolabeled version of prothombin enabled the detection of S. aureus vegetations with combined PET-CT imaging, an approach that could be used in human patients after additional development and FDA approval.

"An approach like this could help clinicians detect the presence of endocarditis, determine its severity and whether it is caused by S. aureus, and track the effectiveness of antibiotics or other treatments," says Nahrendorf, also a co-corresponding author of the Nature Medicine article and an assistant professor of Radiology at Harvard Medical School. "We are working to improve the PET reporter probe with streamlined chemistry and a more mainstream PET isotope to make it a better candidate for eventual testing in patients."


Contact: Sue McGreevey
Massachusetts General Hospital

Related medicine news :

1. New high-speed 3-D imaging system holds potential for improved cancer screening
2. New CMU brain imaging research reveals why autistic individuals confuse pronouns
3. New imaging technique captures brain activity in patients with chronic low back pain
4. High-resolution imaging technology reveals cellular details of coronary arteries
5. IASLC: Adjunctive use of 3-D imaging system increases utility of CT lung cancer screening
6. Self-referral: A significant factor in imaging growth
7. Women May Be Getting Unneeded Heart Imaging Tests
8. Brain imaging study of preschoolers with ADHD detects brain differences linked to symptoms
9. Imaging utilization affected by patient age and facility imaging capacity, study suggests
10. Halving the radiation dose in cardiac perfusion imaging is now feasible
11. Digital imaging software to create a Google Earth view of the bladder
Post Your Comments:
(Date:11/27/2015)... ... November 27, 2015 , ... According to an article published ... Toronto and the University of British Columbia suggested that laws requiring bicyclists to wear ... explains that part of the reason for the controversial conclusion is that, while helmets ...
(Date:11/27/2015)... , ... November 27, 2015 , ... ... the toilets were," said an inventor from Hillside, N.J. "Many people catch diseases ... cover so that individuals will always be protected from germs." , He developed ...
(Date:11/27/2015)... , ... November 27, 2015 , ... ... of progress through sharing, the 2016 Building Better Radiology Marketing Programs ... will begin on Sunday, March 6, 2016, at Caesars Palace in Las Vegas ...
(Date:11/27/2015)... ... November 27, 2015 , ... CBD College is proud to ... Programs (CAAHEP) awarded accreditation to its Diagnostic Medical Sonography program. CBD College is honored ... one of twelve colleges and universities in the state of California make the cut. ...
(Date:11/26/2015)... , ... November 26, 2015 , ... ... abuse located in central Michigan, have come together on Thanksgiving Day to share ... video, available for viewing on the Serenity Point YouTube channel, patients displayed what ...
Breaking Medicine News(10 mins):
(Date:11/27/2015)... YORK , November 27, 2015 ... system is set to go online. The potential to ... processes is vast and far from fully exploited as ... to patient health records, either via mobile tablet or ... ) --> ) --> ...
(Date:11/27/2015)... ) ... "2016 Global Tumor Marker Testing Market: Supplier ... Segment Forecasts, Innovative Technologies, Instrumentation Review, Competitive ... offering. --> ) has ... Global Tumor Marker Testing Market: Supplier Shares ...
(Date:11/26/2015)... Netherlands , November 26, 2015 ... A new combination approach blends immunotherapy with Bremachlorin-photodynamic ... A new combination approach blends immunotherapy with Bremachlorin-photodynamic therapy ... A new combination approach blends immunotherapy with Bremachlorin-photodynamic therapy ... Netherlands has found that immunotherapy can be ...
Breaking Medicine Technology: