New test could make ulcer-causing bacteria emit green light in the stomach
January 16, 2014
Research carried out by a team of scientists at the University of Southern Denmark literally sheds new light on how a non-invasive technique for the early diagnosis of stomach ulcers could be performed in the future. The findings of the researchers point to a fast, hassle-free method that does not require sample tissues, unlike current testing methods.
The experiments were carried out to detect the presence of a bacteria called Helicobacter Pylori. It's found in virtually every other person, and is a risk factor associated with gastric cancer, the second most deadly cancer across the globe. The researchers employed a new version of a method called "fluorescent in situ hybridization" (FISH) that uses DNA or RNA samples ("probes") to detect the presence of a DNA target. FISH has already been used to detect microorganisms in samples, but not within the human body.
The new variant of FISH, which they call FIVH (fluorescence in vivohybridization of microorganisms), combined with recent advances in imaging systems, makes it possible to carry out in-depth analysis of the mucosa of internal organs such as the stomach and the colon. The presence of the bacteria would be signaled as it fluoresced green, the light from which the doctor would detect using a micro camera.
The researchers worked to overcome some of the challenges related to this type of approach, particularly in relation to the environmental conditions of the organs for the probes. In the case of the stomach, they would have to survive at the human stomach’s temperature of 37°C (98.6°F) and its acidic environment. Professor Jesper Wengel developed special synthetic molecules called Locked Nucleid Acid, which are known to be well-suited for the FIVH method. In this case, they offered the stability and requirements to function well in the stomach.
The process was tested by making the bacteria glow in artificial tissue that mimics the lining of the human stomach. In a real-life context, the synthetic molecules would be sent to the stomach, where they would react with the bacteria and make it glow. This is where the cameras play their part in the process, allowing doctors to see the fluorescence signal inside the human body. The researchers envisage the use of a confocal laser endomicroscope connected to a computer, a technology that has already been used successfully for in vivo diagnosis of gastric cancer and has also enabled identification of H. pylori in other settings.
The scientists believe this type of micro camera could produce real time, high-resolution images of the bacterium during endoscopy. The method could also allow doctors to test the bacteria’s resistance to Clarithromycin, used to treat bacterial infection, by redesigning the probes they send to the stomach. With this information, health professionals would be better equipped to choose the best therapy for the patient.
The team at the University of South Denmark say there still are problems to be solved before the method can be perfected, mainly related to the chemical compounds of the probes and exposure time to the bacteria. The performance of the confocal endomicroscopy to pick up the fluorescent signals in the stomach also needs to be further assessed. They add that their study has laid the foundation for other projects aimed at developing methods for in vivo detection of other microorganisms using FIVH.
An article describing the results of the research appeared in the journal PLOS ONE.
Source: University of Southern Denmark
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