Caption: Mouse brain tissue as viewed by traditional microscopy (left) and expansion microscopy (right), which makes it possible to visualize individual synapses (example in white box). In both views, green indicates neurons; blue, pre-synaptic proteins; and red, post-synaptic proteins. Credit: Ed Boyden, Fei Chen, Paul Tillberg, MIT
Light microscopy has been a mainstay of neuroscience and many areas of biology for more than a century. But the resolution limit of light, based on immutable physical principles, has kept the fine details of many structures out of view. Scientists can’t change the laws of physics—but NIH-supported researchers recently devised a highly creative way to see images that were previously out of reach, by expanding the contents of tissue sections up to five times their normal size, while maintaining the anatomic arrangements. The new approach takes advantage of a compound used in—get this—disposable diapers!
By harnessing the super-absorbent properties of sodium polyacrylate, a polymer commonly used in diapers, a team from the Massachusetts Institute of Technology (MIT) developed a new technique that makes it possible for conventional microscopes to produce super high-resolution images of brain cells. The name of the new technique? Expansion microscopy.
In recent years, scientific evidence has begun to accumulate that indicates taking aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) on a daily basis may lower the risk of developing colorectal cancer. Now, a new study provides more precise information on who might benefit from this particular prevention strategy, as well as who might not.
Published in the journal JAMA, the latest work shows that, for the majority of people studied, regular use of aspirin or NSAIDs was associated with about a one-third lower risk of developing colorectal cancer. But the international research team, partly funded by NIH, also found that not all regular users of aspirin/NSAIDs reaped such benefits—about 9 percent experienced no reduction in colorectal cancer risk and 4 percent actually appeared to have an increased risk . Was this just coincidence, or might there be a biological explanation?
“The Thinker” by Auguste Rodin (photo by Brian Hillegas)
Humans’ most unique traits, such as speaking and abstract thinking, are rooted in the outer layer of our brains called the cerebral cortex. This convoluted sheet of grey matter is found in all mammals, but it is much larger and far more complex in Homo sapiens than in any other species. The cortex comprises nearly 80 percent of our brain mass, with some 16 billion neurons packed into more than 50 distinct, meticulously organized regions.
In an effort to explore the evolution of the human cortex, many researchers have looked to changes in the portion of the genome that codes for proteins. But a new paper, published in the journal Science , shows that protein-coding DNA provides only part of the answer. The new findings reveal that an even more critical component may be changes in the DNA sequences that regulate the activity of these genes.
Bill Bement describes himself as a guy who “passionately, obsessively, and almost feverishly” loves to study cells. His excitement comes through in our final installment of the American Society for Cell Biology’s Celldance 2014. Bement, an NIH grantee at the University of Wisconsin, Madison, shares his scanning confocal microscope with us for this fascinating glimpse into the rapid response of cells to repair holes, tears, and other structural damage in their protective outer membranes.
For most people, this damage response runs on biochemical autopilot, sealing any membrane break within seconds to keep the cell viable and healthy. But some people inherit gene mutations that make sealing and patching difficult, particularly in cells that operate under repetitive mechanical stress. For example, some forms of muscular dystrophy stem specifically from an inherited inability to repair breaks in the cell membrane of skeletal muscle cells. In one type of disease that affects both skeletal and cardiac muscle, a gene mutation alters the shape of a protein called dysferlin, which normally binds annexin proteins that, as noted in the video, play a vital role in patching holes. In the presence of a glitch in dysferlin, the rapid chain of biochemical events needed to enable such repair breaks down.
There’s still an enormous amount to learn about cell membrane repair, so it will be interesting to see what Bement’s microscope and camera will show us next.
Caption: Schematic of how the clot retriever used in the reported trials is opened inside a blood vessel to surround a clot that is blocking blood flow. Once caught by the stent, the entire apparatus with the clot is removed from the body out a small puncture in the femoral artery at the groin. Credit: Covidien
Despite the recent progress we’ve made in preventing stroke by such steps as controlling weight, lowering blood pressure, and stopping smoking, nearly 700,000 Americans suffer clot-induced, or ischemic, strokes every year . So, I’m very pleased to report that, thanks to years of rigorous research and technological development, we’ve turned a major corner in the emergency treatment of this leading cause of death and disability.
The most severe strokes—those that can cause lifelong loss of independent function—are often due to blood clots that suddenly enter and block one of the main arteries supplying blood flow to the brain. No less than four large, randomized clinical trials recently reported results showing, for the first time, that using catheters to remove large clots from cerebral arteries can restore blood flow and halt further damage to the brains of patients with acute strokes. In fact, the stent-based retrievers and other mechanical approaches used to remove stroke-causing clots proved so effective, that three of the four trials were stopped early, allowing the results to be made swiftly available to medical professionals and the public.