Health
A new study appearing this week in the Journal of Neuroscience details for the first time how “mini-strokes” cause prolonged periods of brain damage and result in cognitive impairment.
These strokes, which are often imperceptible, are common in older adults and are believed to contribute to dementia.
“Our research indicates that neurons are being lost as a result of delayed processes following a mini-strokes that may differ fundamentally from those of acute ischemic events,” said Maiken Nedergaard, M.D., D.M.Sc., the lead author of the study and professor of Neurosurgery at the University of Rochester Medical Center (URMC). “This observation suggests that the therapeutic window to protect cells after these tiny strokes may extend to days and weeks after the initial injury.”
The prevalence of mini-strokes, or microinfarcts, has only been recently appreciated because common imaging techniques, such as MRI, are typically not sensitive enough to detect these microscopic injuries.
Similar to severe ischemic strokes, mini-strokes are caused when blood flow is blocked to a small area of the brain, usually by particle that travelled there from another part of the body.
But unlike acute ischemic strokes – which bring about immediate symptoms such as numbness, blurry vision, and slurred speech – mini-strokes usually pass without notice. However, it is increasingly appreciated that these smaller strokes have a lasting impact on neurological function.
Microinfarcts are far more common than previously understood; it is believed that about 50 percent of individuals over the age of 60 have experienced at least one mini-stroke.
Studies have also correlated the presence of mini-strokes with the symptoms of dementia. An estimated 55 percent of individuals with mild dementia and upwards of 70 percent of individuals with more severe symptoms show evidence of past mini-strokes. This association has led researchers to believe that these mini-strokes may be key contributors to age-related cognitive decline and dementia.
Nedergaard and her colleagues were the first to develop an animal model in which the complex progression and, ultimately, the cognitive impact of mini-strokes could be observed. Her team found that, in most instances, these strokes result in a prolonged period of damage to the brain.
A small fraction of these microinfarcts unfold in a manner similar to acute strokes; cell death is immediate and the brain quickly seals off the site of the stroke and begins to “digest” the damaged tissue. However, the researchers also identified a second and far more common form of mini-stroke – which they labeled incomplete lesions – where the cell death can drag on for several weeks.
“In most microinfarcts the injury is incomplete,” said Nedergaard. “There is no scar tissue to separate the stroke site from the rest of the brain and the cells that would normally support the neurons may not function properly. As a result, the neurons at the site continue to slowly die like a smoldering fire. This suggests that, unlike acute ischemic strokes where the cell death occurs in the first 24 hours, there is a longer period in which we can medically intervene and stop the neuronal death that results from mini-strokes.”
The researchers then attempted to determine the cognitive impact of microinfarcts. Mice who were victims of mini-strokes underwent a series of experiments during which they had to recall objects or respond to certain audio cues.
The researchers observed that the mice with mini-strokes were far more likely to fail these tasks – suggesting neurological impairment – compared to healthy mice.
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Are you allergic to peanuts and worried there might be some in that cookie? Now you can find out using a rather unlikely source: your cell phone.
A team of researchers from the UCLA Henry Samueli School of Engineering and Applied Science has developed a lightweight device called the iTube, which attaches to a common cell phone to detect allergens in food samples.
The iTube attachment uses the cell phone’s built-in camera, along with an accompanying smart-phone application that runs a test with the same high level of sensitivity a laboratory would.
Food allergies are an emerging public concern, affecting as many as 8 percent of young children and 2 percent of adults. Allergic reactions can be severe and even life-threatening.
And while consumer-protection laws regulate the labeling of ingredients in pre-packaged foods, cross-contaminations can still occur during processing, manufacturing and transportation.
Although several products that detect allergens in foods are currently available, they are complex and require bulky equipment, making them ill-suited for use in public settings, according to the UCLA researchers.
The iTube was developed to address these issues, said Aydogan Ozcan, leader of the research team and a UCLA associate professor of electrical engineering and bioengineering. Weighing less than two ounces, the attachment analyzes a test tube–based allergen-concentration test known as a colorimetric assay.
To test for allergens, food samples are initially ground up and mixed in a test tube with hot water and an extraction solvent; this mixture is allowed to set for several minutes.
Then, following a step-by-step procedure, the prepared sample is mixed with a series of other reactive testing liquids. The entire preparation takes roughly 20 minutes.
When the sample is ready, it is measured optically for allergen concentration through the iTube platform, using the cell phone’s camera and a smart application running on the phone.
The kit digitally converts raw images from the cell-phone camera into concentration measurements detected in the food samples. And beyond just a “yes” or “no” answer as to whether allergens are present, the test can also quantify how much of an allergen is in a sample, in parts per million.
The iTube platform can test for a variety of allergens, including peanuts, almonds, eggs, gluten and hazelnuts, Ozcan said.
The UCLA team successfully tested the iTube using commercially available cookies, analyzing the samples to determine if they had any harmful amount of peanuts, a potential allergen. Their research was recently published online in the peer-reviewed journal Lab on a Chip and will be featured in a forthcoming print issue of the journal.
Other authors of the research included graduate student and lead author Ahmet F. Coskun and undergraduate students Justin Wong, Delaram Khodadadi, Richie Nagi and Andrew Tey, all of whom are members of the Ozcan BioPhotonics Laboratory at UCLA. Ozcan is also a member of the California NanoSystems Institute at UCLA.
“We envision that this cell phone–based allergen testing platform could be very valuable, especially for parents, as well as for schools, restaurants and other public settings,” Ozcan said. “Once successfully deployed in these settings, the big amount of data – as a function of both location and time – that this platform will continuously generate would indeed be priceless for consumers, food manufacturers, policymakers and researchers, among others.”
Allergen-testing results of various food products, tagged with a time and location stamp, can be uploaded directly from cell phones to iTube servers to create a personalized testing archive, which could provide additional resources for allergic individuals around the world.
A statistical allergy database, coupled with geographic information, could be useful for future food-related policies – for example in restaurants, food production and for consumer protection, the researchers said.
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