Cerebrospinal fluid (CSF) of the central nervous system disseminates numerous cells, proteins, microparticles, and DNA as potential biomarkers of many diseases and therapy efficacy.
For example, circulating tumor cells are a sign for metastatic cancer, bacteria can reveal an infectious meningitis or encephalitis, erythrocytes indicate a trauma, and tau-protein is a biomarker for Alzheimer’s disease.
However, current methods for detecting biomarker in CSF are far from ideal. A main drawback is that the tests are performed in vitro, and their sensitivity is limited by the sample volume. Rare circulating biomarkers such as tumor cell at the stage of latent metastasis remain undetectable. Furthermore, cytology is a quite subjective method depending on the experience of the laboratory technicians. Yet, other current methods show even higher false-negative results than cytology.
The problem could be solved by examining a larger volume. Ekaterina I. Galanzha and a team from the University of Arkansas for Medical Sciences thought to examine the whole CSF volume. To pursue this objective, they developed a method using in vivo photoacoustic flow cytometry (PAFC) for ultrasensitive detection of cells and nanoparticles in CSF. During PAFC, non-radiative relaxation of absorbed laser energy into heat leads to thermoelastic generation of sound.
PAFC is not sensitive to light scattering or autofluorescence and provides higher sensitivity and resolution in deeper tissue than other optical modalities. When CSF is irradiated through skin, photoacoustic waves from individual cells can be detected with an ultrasound transducer attached to the tissue over ventricles or spinal cord. The method is noninvasive for normal tissues as it operates with laser energy at levels that are safe for humans.
To extend diagnostic significance, PAFC was integrated with photothermal scanning cytometry/microscopy ex vivo using label-free mode as well as molecular targeting with low-toxicity bioconjugated nanoparticles. In photothermal thermal-lens schematic, laser induced temperature-dependent variation of the refractive index around absorbing zones is optically detected.
Contrast can be enhanced by labeling cells or molecules of interest with specifically binding nanoparticles such as gold nanorods. In the experiments, two types of nanorods were used with different absorption maxima for two color labeling.
In the CSF of tumor-bearing mice, the researchers molecularly detected in vivo circulating tumor cells before the development of breast cancer brain metastasis with 20-times higher sensitivity than with current assays. For the first time, they demonstrated assessing three pathways – blood, lymphatic, and CSF – of circulating tumor cells dissemination, tracking nanoparticles in CSF and their imaging ex vivo. The scientists were able to count leukocytes, erythrocytes, melanoma cells, and bacteria in label-free CSF samples.In addition, they could image intracellular cytochromes, hemoglobin, melanin, and carotenoids, respectively, by labeling with specific binding gold nanorods.
Taking into account the safety of PAFC, the researchers expect its translation for use in humans to improve disease diagnosis beyond conventional detection limits. (Text contributed by K. Maedefessel-Herrmann)Nedosekin, D.A., et al; J. Biophotonics 6(6-7), 523-533 (2013); DOI 10.1002/jbio.201200242
http://onlinelibrary.wiley.com/doi/10.1002/jbio.201200242/abstractWiley-VCH Verlag GmbH & Co. KGaA
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy