Category Archives: Medical physics

Fluorescent eel protein could indicate human liver malfunction

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Science News: A fluorescent protein found in a Japanese eel glows green in the presence of bilirubin, a pigment that can indicate jaundice or liver problems in humans. The discovery was made by Atsushi Miyawaki and his coworkers of the RIKEN research institute in Japan while they were studying the species Anguilla japonica to find out why the eels glow green. What they found was that a protein called UnaG, located in the eels’ muscle fibers, glows when it comes in contact with bilirubin. Although the researchers are not entirely sure why UnaG does that, they have used a lab-made version of the protein to develop a simple blood test to check for elevated levels of the protein in humans.

NASA to fund startups focused on space travel health problems

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Ars Technica: NASA has announced a new program, SMARTCAP-Accel, that will provide funding to startups that are working on projects related to the medical dangers of space travel. The areas of focus include radiation exposure, inadequate nutrition, bone fracture, and heart health. NASA is also interested in routine monitoring techniques. To qualify for funding, the projects must be able to function without a doctor or full medical lab and must be completely solar powered. In addition to being useful in space, such technologies could also benefit people in remote and underserved areas on Earth. The program will award between $10 000 and $200 000, but all awardees must find a second source to match NASA’s funding. If the companies produce technology that NASA wants to use, the agency will purchase it separately.

Medical isotopes produced without nuclear reactor

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Vancouver Sun: When the Canadian government shut down the Chalk River reactor in Ontario, it eliminated the source of 40% of the world’s technetium-99. The isotope is used in 90% of all nuclear medical imaging, including tracking blood flow and identifying tumors. Now, researchers at the British Columbia Cancer Agency have shown that they can make significant amounts of 99Tc using a particle accelerator known as a cyclotron. The accelerator, which collides atoms, has been known for more than 40 years to produce small amounts of various isotopes. Scientists on the $15 million program have been working to scale up the production rate since 2009. Most hospitals have secured supplies of necessary isotopes in the years since the Chalk River shutdown, but the new development may provide cheaper alternatives. However, because of the short half-life of 99Tc, a cyclotron can only supply nearby hospitals, so such facilities would likely only be established in larger urban areas.

First flexible conductive material attached to soft contact lenses

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MIT Technology Review: Electronic systems for monitoring glaucoma patients or for displaying images have been attached to hard contact lenses over the past several years. Now, Jang-Ung Park of the Ulsan National Institute of Science and Technology in South Korea and his colleagues have mounted an LED on an off-the-shelf soft contact. They were able to create an adhesive, transparent, highly conductive, yet flexible circuit by creating a mesh of layers of graphene and silver nanowire. This allowed them to overcome the normally low conductivity of organic conductors and graphene. The material was added to the contact by depositing it as a liquid while the surface of the contact was spun to evenly distribute the material. The material maintains 94% transparency, and the contact remains flexible. Then the researchers mounted a single LED to the contact as a proof of concept. The technique could be used for on-contact displays, they say, but may be more useful for medical monitoring systems.

Atomic bomb tests provide evidence of adult brain neuron growth

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Science: In 1998 researchers showed, contrary to expectations, that some neurons in adult human brains did divide to produce new cells. The test was never duplicated because one of the substances used was found to be toxic. A new study, led by Kirsty Spalding of the Karolinska Institute in Stockholm, Sweden, has provided the first support for the original study, using an unusual source. The testing of nuclear weapons in the 1950s and 60s doubled the levels of radioactive carbon-14 in the atmosphere. Because the levels stopped increasing after the 1963 Limited Test Ban Treaty, 14C has steadily decayed to 12C. The ratio of those isotopes in cells can serve as a time stamp for the cells’ ages. Spalding and her colleagues spent 10 years developing techniques to isolate specific neural tissues and to then extract and identify the very small amounts of carbon isotopes present. They found that more than one third of the hippocampal neurons were regularly replaced during adulthood, with roughly 1400 new neurons added daily. Whether that growth is actually significant in how the brain functions is far from clear, but the question of whether neuron growth occurs at all appears to be settled.

Pilot’s brain waves remotely control the flight of a model helicopter

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BBC: Electroencephalography (EEG) measures electrical activity on the scalp generated by the firing of neurons in the brain. Although most of the signals are largely indecipherable, those related to motion are recognizable. Such signals have been used for basic control of motorized wheelchairs, and implanted sensors have allowed for even finer control systems. Bin He of the University of Minnesota and his colleagues have now used an EEG cap connected to a computer that allows the wearer to control the flight of a remote-control helicopter. The pilots “trained” the computer to recognize each pilot’s brain patterns corresponding to left, right, up, and down. They then used the system to guide the helicopter through an obstacle course. Some of the pilots achieved obstacle avoidance rates of 90% with just those simple commands. The noninvasive ability to harness the power of thought to control complex motion is a significant step forward in brain-controlled mechanical action.

Using magnetic fields to detect brain damage

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MIT Technology Review: A new and cheap helmet-shaped device can detect the accumulation of fluids that accompanies certain forms of brain damage. Designed by Cesar Gonzalez of Mexico’s National Polytechnic Institute and his colleagues, the helmet works by inducing a magnetic field in a patient’s brain with a set of coils. Another set of coils measures changes in the magnetic field’s phase that depend on the amount of fluid present. Although the helmet can’t locate where fluid levels are anomalously high, it’s cheap enough and compact enough to identify patients for follow-up tests. A pilot study succeeded in identifying cases of brain edema and hematoma.

Particle physicist leads drive to study radiation exposure from Fukushima Daiichi

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Science: Soon after the disaster at the Fukushima Daiichi Nuclear Power Plant, Ryugo Hayano of the University of Tokyo began to use his Twitter account to share information from one of the radiation monitors at the plant. He also became aware of the public’s concerns over radionuclide levels in food and the government’s apparent failure to share information regarding the issue. Beginning in January 2012, he began testing school lunches for radiocaesium, the most common radionuclide near Fukushima. However, he found no evidence of dangerous levels of radioactivity in the food. He also assisted in full-body scans of local residents and helped determine that the local hospital’s scanner was not shielded from environmental radiation. Shielded full-body scanners found no evidence of radiocaesium in any of the 10 000 children scanned. And the four adults who had significant levels had eaten food that had bypassed the mandatory testing in markets. The government has welcomed Hayano’s findings, but he is still critical of their haphazard testing and information sharing.

Sensor uses carbon nanotubes to test saliva for glucose

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MIT Technology Review: A new way to test people’s glucose levels should make that process less painful for people with type 2 diabetes. Current tests rely on blood samples drawn from finger pricks. Now Mitchell Lerner of the University of Pennsylvania in Philadelphia and colleagues have developed a carbon nanotube–based transistor that can detect glucose levels in a variety of body fluids, including saliva. The nanotubes are coated with molecules of pyrene-1-boronic acid, which makes then highly sensitive for glucose detection. When exposed to glucose, the nanotube transistor’s current-voltage curve changes, and that change can be measured to indicate the glucose concentration. Although the technology has been around for a while, what the research team did was find a way to make the tubes quickly and cheaply. The system is less useful for type 1 patients, who have to give themselves daily injections of insulin. Because it takes at least 30 minutes for the glucose to show up in saliva, the device cannot quickly give an accurate reading of the blood glucose levels.

Bacteria used to deliver radiation treatment to pancreatic tumors

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Science: Pancreatic cancer is exceptionally lethal—only 4% of patients survive past 5 years—partly because of its aggressive metastasizing. Now a novel way to halt its spread has been proposed. Listeria monocytogenes is a bacterium that has previously been shown to directly attack tumor cells when it is modified to carry the tumor cells’ DNA. Claudia Gravekamp of the Albert Einstein College of Medicine in New York and her colleagues combined the modified Listeria with a radioactive compound and used it to treat mice with human pancreatic cancer tumors. The radioactive bacteria treatment reduced the number of metastatic cancer cells by up to 90%, while nonirradiated bacteria eliminated 50% of the metastasized cells. In addition, the radioactive bacteria shrank the primary tumor by 64% versus just 20% for the nonradioactive treatment. And there was very little damage to healthy tissue. Although a 90% elimination of metastasized cells is impressive, the remaining 10% are more than enough to be lethal. The researchers believe that use of a radiation source with a longer half-life could be 100% effective. Certain issues need to be addressed, however, before the treatment can be used on humans, including the risk of inducing sickness by using Listeria, which is itself a dangerous bacteria even in an attenuated form, and the potential buildup of radiation in the kidneys after the bacteria die.