The most common form of strokes are caused by a sudden reduction in blood flow to the brain (ischemia) that leads to an inadequate supply of oxygen and nutrients. These so-called ischemic strokes are one of the leading causes of death and disability in industrialized nations.
If they are not immediately remedied by medical intervention, areas of the brain may die off. In the journal Angewandte Chemie, Korean researchers have now proposed a new approach for supplemental treatment: Ceria nanoparticles could trap the reactive oxygen compounds that result from ischemia and cause cells to die.
When blood flow to areas of the brain is restricted, reactive oxygen compounds like superoxide radical anions (O2• –), hydrogen peroxide (H2O2), and hydroxyl radicals (HO• –) form and accumulate. These species cause oxidative damage and are responsible for tissue damage and cell death during a stroke. Nerve connections and neurovascular units are destroyed and the function of the brain in these areas stops. Despite various treatments that primarily combat the causes of reduced blood flow, such as thrombosis, there has been no way to protect nerves from oxidative damage after an acute ischemic stroke. Seung-Hoon Lee, Taeghwan Hyeon, and their team at Seoul National University hope that nanoparticles made of ceria may represent a new approach for treatment.
Cells contain enzymes that can break down reactive oxygen species: superoxide dismutases, which convert superoxide anions to hydrogen peroxide; and catalase, which splits hydrogen peroxide. Ceria nanoparticles can do both. How does this work? The cerium in ceria crystals is present in the form of Ce4+. However, if the particle size is reduced to a few nanometers in diameter, some spots on the surface are missing oxygen atoms. These places have Ce3+ instead, which can easily be reduced back to Ce4+ and can reversibly bind oxygen.
The researchers treated cell cultures with a substance that increases the concentrations of reactive oxygen species, which leads to increased cell death. Treatment with cerium oxide nanoparticles drastically improved the cell survival rate. In animal trials, the researchers induced ischemic strokes in rats. Intravenously administered ceria nanoparticles considerably reduced the stroke volume and nerve damage. An optimized, carefully balanced dose is necessary, however.
Interestingly, the concentrations of ceria nanoparticles in the healthy areas of the brain were very low, while those in the ischemic areas were drastically elevated. The researchers speculate that the ceria nanoparticles can barely pass through the intact blood-brain barrier. However, the barrier is damaged in the ischemic areas, allowing the diseased areas of the brain to be reached and oxidative damage to be stopped.
Author: Taeghwan Hyeon, Seoul National University (Korea), http://nanomat.snu.ac.kr/index.php?mid=DirectorTitle: Ceria Nanoparticles that Protect against Ischemic Stroke
Taeghwan Hyeon | Angewandte Chemie
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences