Science News - November 19, 2011

McDevitt of Rice University in Houston has developed a device, called a biotometer, that analyzes saliva samples, as well as other body fluids, on board emergency vehicles. Like programmers developing apps for an iPhone, McDevitt’s team has individual test cards customized for specific health conditions. Each card can look for multiple biomarkers associated with that condition.

The battery-operated analyzer weighs in at just under five kilograms, making it light enough to transport from place to place. Working like an ATM machine, the device reads information on the disposable test cards inserted into it. Each card contains a series of wells packed with tiny detection beads that act as microsponges to collect the biomarkers of interest.

McDevitt and his colleagues are already using the device to analyze spit samples to find out whether patients with chest pain are suffering a heart attack. A drop of saliva obtained from a gum swab goes onto the appropriate test card and is placed in the analyzer. If the saliva sample contains troponin T, a protein characteristic of a heart attack (it is released into the blood when heart cells die), the detection beads will emit a fluorescent color. The analyzer spots that color glow in the beads and indicates that the patient is indeed experiencing a heart attack.

McDevitt says he hopes saliva-based tests can detect heart attacks faster and more accurately than traditional methods. Of the millions of patients who visit emergency rooms with chest pain each year, only about half of those suffering a heart attack are immediately diagnosed using the electrocardiogram. The others must undergo additional testing, which can take anywhere from 90 minutes to several hours to process.

With the biotometer, clinicians could make a diagnosis within minutes instead of hours, McDevitt says.

The device is now being tested in a clinical trial in Houston, directed by Baylor College of Medicine cardiologists, to see how spit samples work in conjunction with the EKG to diagnose cardiac arrest patients. A second study

Digging in

That frothy fluid in your mouth holds all kinds of clues to the body’s happenings.

Drug use Saliva can reveal drug use, whether for therapy or recreation.

Hormones commercial test kits gauge estrogen, testosterone and cortisol levels from saliva.

HIV The u.S. Food and Drug administration has approved a test that looks in oral fluid for antibodies known to be present in people with hiv infections.

Age a recent study suggests that genetic clues in spit can pinpoint age to within five years.

Cancer messenger rNa signatures for breast and pancreatic cancer have turned up in saliva.

Heart disease The protein troponin T in spit may pinpoint people having heart attacks.

is in progress on emergency vehicles in San Antonio.

Within spitting distance

Currently being manufactured by Force Diagnostics, a biotechnology firm in Chicago, McDevitt’s device will be made available for real-world applications within the next few months. The first units will be deployed for blood-based testing, targeting HIV infection in Africa. A 12-minute field test will replace a two-hour lab version, McDevitt says.

Initial applications for spit-based tests using the biotometer and other devices may appear within two to three years. Oral disease and gum disease tests will probably come online first. Widespread screening for conditions such as pancreatic cancer, breast cancer or heart attack may occur within five years.

These developments and other findings from various labs are laying the groundwork for a dramatic change in disease treatment, McDevitt says, allowing clinicians to move from reactive to preventive medicine.

As part of the heart attack trial, for example, his group is collecting information on protein changes associated with the risk of future heart attacks. Current diagnostic methods can’t easily detect the earliest stages of cardiac disease, he says, so the findings open up the possibility of using the biomarkers in saliva, or other body fluids, to detect health risks months or years before they become full-blown problems.

“I think we actually have a way to do
it,” McDevitt says. “We’re seeing this in
our trials right now.”
His optimism is supported by a study
published in the Oct. 25 Journal of
the American College of Cardiology. It
showed that adjusting therapy to con-
trol levels of the protein NT-proBNP in
the blood of heart patients could lower
the rates of arrhythmias, stroke and
heart attack. NT-proBNP is a known
marker of cardiac distress, and is already
detectable in spit. Because spit tests are
cheaper and easier to administer than
blood tests, clinicians might someday
use them to monitor such patients.