Archive for November 2016

Saliva tests may help identify marijuana-impaired drivers

November 22, 2016
Photo by ashton

Photo by ashton

As of the recent election, seven states and the District of Columbia have now legalized marijuana for recreational use and 19 other states have legalized medical marijuana. And this legalization has raised concerns about driving under the influence of marijuana.

A number of research groups are now focusing on ways to identify drivers impaired by marijuana. As recently reported by KQED, the Center of Medicinal Cannabis Research at the University of California, San Diego, are working to “gather data about dosages, time and what it takes to impair driving ability — and then create a viable roadside sobriety test for cannabis.” And a group of Stanford engineers have created a test called a ‘potalyzer.’

The Stanford effort was led by Shan Wang, PhD, a Stanford professor of materials science and engineering and of electrical engineering. He and his colleagues developed a mobile device that detects the amount of tetrahydrocannabinol (THC) molecules in saliva. (THC is the main psychoactive agent in marijuana.)

The test would allow police officers to collect a saliva sample from the driver’s mouth with a cotton swab, analyze it with the new device, and then read the results on a smartphone or laptop in as little as three minutes.

The technology combines magnetic nanotechnology with a competitive immunoassay. During the test, saliva is mixed with antibodies that bind to both THC molecules and magnetic nanoparticles. The mixture is placed on a disposable test chip, inserted into the handheld device and the THC-antibody-nanoparticles are detected by magnetic biosensors. The biosensor signal is then displayed on a Bluetooth-enabled device.

Wang’s group focused on developing a THC saliva test because it is less invasive and may correlate better with impairment than THC urine or blood tests. Also key is the need for a very sensitive test. A Stanford news release explains:

“Wang’s device can detect concentrations of THC in the range of 0 to 50 nanograms per milliliter of saliva. While there’s no consensus on how much THC in a driver’s system is too much, previous studies have suggested a cutoff between 2 and 25 ng/ml, well within the capability of Wang’s device.”

There is still a lot to do before police can deploy this ‘potalyzer’ device, including making it more user-friendly, getting it approved by regulators and investigating whether there is a better biomarker to detect marijuana impairment than THC. In addition, the test may not work well for THC edibles, the researchers wrote in a recent paper published in Analytical Chemistry.

On the upside, the Stanford technology could also be used to test for morphine, heroin, cocaine or other drugs — and for multiple drugs at the same time.

More research is needed, but there is now a new funding source in California: Proposition 64 allots millions of dollars per year to research marijuana and develop ways to identify impaired drivers.

This is an expanded version of my Scope blog story, courtesy of Stanford School of Medicine.

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Dr. B’s brain collection helps local students learn anatomy

November 21, 2016
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Photo courtesy of Donna Bouley

Most of the time, veterinary pathologist Donna Bouley, DVM, PhD, provides pathology support for Stanford researchers and clinicians who work with animals.

But she also has an unusual hobby: Bouley, known to all as Dr. B, collects animal brains. Since 1997, she and others have taken “Dr. B’s Brain Collection” to local schools for a variety of science programs. Fascinated by this idea, I contacted her to learn more.

What inspired you to create your brain collection? What does it include?

“When I first started as faculty at Stanford, there were some preserved brains in the necropsy [animal autopsy] lab. I decided to start collecting more brains from animals that came to necropsy, when we didn’t need their brains to make our diagnosis. The word somehow got out that such a resource existed on campus. Now, I actually have two collections that are almost identical, because multiple labs were interested in borrowing the collection at the same time.

In each collection, I try to have at least one of the following brains: sheep, pig, dog, macaque, squirrel monkey, rabbit, owl, rat, mouse, cyclid (fish), and Xenopus laevis (an African Clawed frog). The brains are preserved and sealed in ‘seal-a-meal’ style bags or jars.

If any new species come through necropsy, I try to get brains from those animals. I also have to replace damaged ones each year, since the enthusiasm of middle schoolers can often result in the rough handling of my bagged brains. My necropsy tech keeps a close watch over the condition of the collections and replaces brains as needed or when available.”

How do you use the collection at Stanford?

“I teach a freshman seminar called Comparative Anatomy and Physiology of Mammals that tends to have several pre-vet and pre-med students each year. I use these brains to demonstrate various features that are similar or different between them, such as overall size, location of the cerebellum or the extent of brain surface folds and ridges. For instance, in lower mammals such as rodents — that survive mainly on instinct rather than cognitive processing — the brain has a very smooth surface. In mammals such as a pig, dog, or macaque that are higher functioning and quite intelligent, the brain surface is highly folded or convoluted. And dolphins and elephants have even more convolutions in their brains than humans!

I also have colleagues that teach Comparative Neuroanatomy at the graduate level and they borrow the brains.

I can only speak about my own college student reactions to exposure to this field and tell you in general they are amazed and in awe. They never look at animals the same after taking my class.”

How do others use the brain collection?

“Graduate students from Stanford psychology or neurobiology labs generally take a brain collection to nearby middle schools, where they work with students during a science class. They most likely also bring some human brains that they compare to the animal brains. Having unique visual teaching tools — real brains, not models or pictures — helps the middle schoolers gain insight into the complexity of the nervous system. Learning about anatomy from a truly comparative aspect is incredibly valuable, because it demonstrates the similarities as well as the unique differences between humans and other mammals.

I’m sure that ‘Dr. B’s Brains’ provide a very lasting impression on students.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Many adults should now take statins, task force recommends

November 15, 2016
Illustration by Rf Vectorscom

Illustration by Rf Vectorscom

The U.S. Preventative Services Task Force now recommends that many adults take a low to moderate dose of statin to reduce their risk of a heart attack or stroke, even if they don’t have a history of cardiovascular disease.

Statins are drugs that reduce the production of cholesterol by the liver — lowering bad cholesterol and triglycerides and raising good cholesterol. The task force comprehensively reviewed the literature on clinical trials and observational studies involving statin use. It concluded that the benefits of using statins outweighed the harms in some patients with increased risk of cardiovascular disease.

Douglas Owen, MD, a Stanford professor of medicine and director of the Center for Health Policy, was a member of the task force when the guidelines were developed. He summarizes the new recommendations in a recent news story:

“The task force recommends that clinicians offer statins to adults who are 40 to 75 years old and have at least one existing cardiovascular disease risk, such as diabetes, hypertension, high cholesterol or smoking. They also must have a calculated risk of 10 percent or more that they will experience a heart attack or stroke in the next decade. The task force recommends that clinicians use the American College of Cardiology/American Heart Association risk calculator to estimate cardiovascular risk because it provides gender- and race-specific estimates of heart disease and stroke.”

The task force hope these new recommendations will help clinicians better identify cardiovascular risk, so their patients can take steps to reduce their risk, such as eating a healthy diet, exercising and potentially taking a statin.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Brain scans detect lies better than polygraph tests, new study shows

November 11, 2016

Forget fact checkers or polygraph tests. A functional magnetic resonance imaging (fMRI) brain scan might be the best way to tell if someone is lying.

According to a study from the University of Pennsylvania, our brains are more likely to give us away when we’re lying than sweaty palms, rapid breathing or spikes in blood pressure, the factors tracked by polygraph tests.

The researchers directly compared the ability of two techniques — fMRI and polygraph tests — to detect concealed information. They had 28 participants secretly write down a number between 3 and 8 on a slip of paper. Each participant then had both lie-detection tests, in random order, a few hours apart. During both sessions, they always answered “no” when asked if they had picked a certain number, which meant that one out of the six answers was a lie.

Three fMRI experts and three professional polygraph examiners then independently analyzed the results. The fMRI experts were 24 percent more likely to detect the lie than the polygraph experts, as recently reported in the Journal of Clinical Psychiatry.

Although the study wasn’t designed to evaluate the combined use of both techniques, the polygraph and fMRI results agreed correctly on the concealed number for 17 participants. So they plan to investigate in the future whether these techniques are complementary.

The study includes only a small number of participants, but the research team is encouraged by the results. “While the jury remains out on whether fMRI will ever become a forensic tool, these data certainly justify further investigation of its potential,” said Daniel Langleben, MD, first author and a professor in psychiatry, in a recent news release.

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Talk about death — before a health crises, says Stanford’s Philip Pizzo

November 10, 2016
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Photo by Oldiefan

Most of us have no desire to think, or talk, about death. However, if we never talk about it, we leave our health providers and families guessing about how and where we want to die.

That’s why it’s important to communicate end-of-life preferences early, Philip Pizzo, MD, founder and director of the Stanford Distinguished Careers Institute, argues in a recent perspective in the Proceedings of the National Academy of Sciences.

It’s a topic he’s quite familiar with: Pizzo co-authored the Institute of Medicine’s report “Dying in America,” which addressed how to improve the quality of care for patients with advanced illnesses, without exacerbating the high costs of health care. In the perspective, he summarizes the IOM report’s key recommendations and provides an update.

Pizzo discussed the piece in an email:

“Unless we are facing an illness or event that makes the prospect of death imminent, most of us do not even think about the inevitability of our mortality. These conversations get slotted to times when death is more imminent and when our crisis-oriented decisions may not reflect our true preferences. That is why the IOM report recommended that conversations about death take place with our health care providers and families throughout life. Our thoughts and preferences about dying will vary at different stages of life and wellbeing.”

In the perspective, Pizzo describes the progress that has been made since the report was published. For instance, the Centers for Medicare & Medicaid Services in January 2016 began paying doctors to have end-of-life conversations with patients — a move Pizzo lauds as a major step.

Another important achievement, according to Pizzo, is the national stakeholder conferences that are now bringing constituencies together to implement the report’s recommendations.

He added:

“We witnessed before the IOM Committee began its work how rapidly public opinion can be swayed by political rhetoric. Thankfully since then, the public’s willingness to engage in conversations about death and dying have become better realized and books, like Atul Gawande’s Being Mortal or Paul Kalaniti’s When Breath Becomes Air, have helped to foster more enlightened conversations about dying.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

Alzheimer’s researchers call on citizen scientists to play an online game

November 7, 2016
Image by geralt

Image by geralt

Many people, like me, have helplessly watched a loved one suffer and die from dementia. Now there is something you can do to help accelerate Alzheimer’s research — play a game.

The game, called Stall Catchers, is part of the EyesOnALZ project that uses citizen scientists to analyze Alzheimer’s research data. The game was developed by the Human Computation Institute, in collaboration with scientists from Cornell University, MIT and the University of California, Berkeley. The research team is trying to understand the association between reduced blood flow in the brain and Alzheimer’s disease.

The game features movies of real blood vessels in live mouse brains. Players must search for clogged vessels where blood flow is blocked, or stalled. Each movie is seen by many citizen scientists and then checked by a research scientist in order to quickly and accurately identify the stalls.

Past research has shown that Alzheimer’s is associated with the accumulation of beta amyloid proteins that clump together into sticky, neurotoxic aggregates called amyloid plaques. These proteins are normally cleared by the blood stream, but the formation of amyloid plaques slows down this clearance process.

Recent animal studies, performed by the Schaffer-Nishimura Lab at Cornell, suggest that improving blood flow in the brain may help reduce the devastating effects of amyloid accumulation. The researchers discovered that up to two percent of capillaries in the brains of Alzhiemer’s-affected mice were clogged — 10 times more than usual — and this caused up to a 30 percent decrease in overall blood flow in the brain.

“Advanced optical techniques have allowed us to peer into the brain of mice affected by Alzheimer’s disease,” said Chris Schaffer, PhD, the principal investigator in the Schaffer-Nishimura Lab, in a recent news release. “For the first time, we were able to identify the mechanism that is responsible for the significant blood flow reduction in Alzheimer’s, and were even able to reverse some of the cognitive symptoms typical to the disease.”

Now the main challenge for the Cornell researchers is the time-consuming process of manually analyzing all the brain movies to identify the stalled vessels. They need to study up to a thousand vessels for each animal. That’s why they collaborated with the experienced citizen teams at UC Berkeley and MIT to create the Stall Catchers game to get help from the public.

“Today, we have a handful of lab experts putting their eyes on the research data,” said Pietro Michelucci, PhD, the EyesOnALZ principal investigator, in a news story. “If we can enlist thousands of people to do that same analysis by playing an online game, then we have created a huge force multiplier in our fight against this dreadful disease.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

 


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