Archive for the ‘Technology’ category

Low-cost “magic box” could decontaminate water in rural communities

April 4, 2017

Photo by Shawn

More than a billion people drink water that is contaminated and can spread deadly diseases such as cholera, dysentery, hepatitis A, typhoid, polio and diarrhea.

Most contaminated water could be purified by adding hydrogen peroxide, which safely kills many of the disease-causing organisms and oxidizes organic pollutants to make them less harmful. Hydrogen peroxide disinfects water in a similar way as standard water chlorination, but it leaves no harmful residual chemicals. Unfortunately, it’s difficult to make or obtain hydrogen peroxide in rural settings with limited energy sources.

Now, researchers from Stanford University and SLAC National Accelerator Laboratory have developed a portable device that produces hydrogen peroxide from oxygen gas and water — and it can be powered by a battery or conventional solar panels. You can hold the small device in one hand.

“The idea is to develop an electrochemical cell that generates hydrogen peroxide from oxygen and water on site, and then use that hydrogen peroxide in ground water to oxidize organic contaminants that are harmful for humans to ingest,” said Christopher Hahn, PhD, a SLAC associate staff scientist, in a recent news release.

First, the researchers designed and synthesized a catalyst that selectively speeds up the chemical reaction of converting oxygen gas into hydrogen peroxide. For this application, standard platinum-mercury or gold-plated catalysts were too expensive, so they investigated cheaper carbon-based materials.

Next, they used their carbon-based material to build a low-cost, simple and robust device that generates and stores hydrogen peroxide at the concentration needed for water purification, which is one-tenth the concentration of the hydrogen peroxide you buy at the drug store for cleaning a cut. Although this device uses materials not available in rural communities, it could be cheaply manufactured and shipped there.

Their results were recently reported in Reaction Chemistry and Engineering. However, more work needs to be done before a higher-capacity device will be available for use.

“Currently it’s just a prototype, but I personally think it will shine in the area of decentralized water purification for the developing world,” said Bill Chen, first author and a chemistry graduate student at Stanford. “It’s like a magic box. I hope it can become a reality.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine. For more details, please read my SLAC news release.

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.

Can social media shed light on cardiovascular disease? Possibly, Stanford journal editors write

October 6, 2016
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Illustration by Clker-Free-Vector-Images

Clearly social media is part of our every day lives, recording our personal communications in a way previously unimaginable.

Researchers are now analyzing this wealth of social media data to better understand what people think and say about their health. Recently, researchers at the University of Pennsylvania sifted through 10 billion English-language tweets to identify and study more than 550,000 US-based tweets related to cardiovascular disease, as reported in JAMA Cardiology.

The research team found that people who tweeted about five cardiovascular conditions — high blood pressure, heart attack, diabetes, heart failure and cardiac arrest — were more likely to be older and female compared to the general population of Twitter users. They also tweeted within minutes or hours in response to events, such as celebrity deaths or to mark World Diabetes Day. 

This study was discussed in the issue’s Editor’s Note by Stanford journal editors Mintu Turakhia, MD, an assistant professor of medicine, and Robert Harrington, MD, a professor and the chair of the Department of Medicine. In the editorial, they acknowledged that the Penn Twitter study was atypical research to include in JAMA Cardiology but noted that digital health is now a major priority for the journal. They explained:

“We accepted [the paper] because it highlights the potential for using these emerging data sources such as Twitter for cardiovascular research, in this case to evaluate public communication about cardiovascular medicine in a manner not previously possible on such a scale.”

Turakhia, the journal’s associate editor of digital health, elaborated in an email: “Twitter and other social media data allow us to examine daily interactions in a connected life in ways not possible before,” he said. “Previously, in order to gain insight on the public’s perception or interest in cardiovascular disease, we were limited to examine historical news and media archives or direct surveys.”

Although the editors believe that Twitter is a new and important research tool, they raised a few questions about future studies. They wrote in the editorial, “The use of Twitter and other social media platforms for cardiovascular research is in an early, proof-of-concept stage. Many important questions remain: Is there signal in the noise? Are these data or results… from the ‘Twitterverse’ generalizable to a broader population?” They also emphasized the need to establish analysis standards and overcome any ethical issues in linking the data with medical or clinical information. Turakhia added:

“Twitter users do not represent the broader population, but that’s not really its purpose. Twitter allows us to examine a highly connected subset of society and learn how cardiovascular disease might manifest in their connected world.”

Ultimately, researchers hope to use this new information to improve their patients’ health, but the research is in its infancy, he said, adding:

“We haven’t yet figured out how Twitter or social media can be definitely used to improve health and health care. The obvious avenues would be through social and community engagement. Although sharing of personal information is at the cornerstone of the success of social media, I’m not sure that society is ready to be as open with posting health information, as they are with selfies or pictures of kids. However social media could be used to gamify health care behavior by providing incentives, and that won’t need disclosure.”

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

To battle mosquito-borne disease, SLAC x-ray laser provides new view of insecticides

October 4, 2016
Illustration, of LCLS x-ray pulses blasting BinAB nanocrystals composed of protein BinA (yellow) and BinB (blue), courtesy of SLAC National Accelerator Laboratory.

Illustration of LCLS x-ray pulses blasting BinAB nanocrystals composed of protein BinA (yellow) and BinB (blue), courtesy of SLAC National Accelerator Laboratory.

Mosquitoes continue to spread devastating diseases such as malaria, West Nile virus, dengue fever and Zika virus throughout the world. Sadly, there are no medications or vaccines for many of these deadly diseases, so it’s critical to prevent mosquito bites.

A cost effective way to eliminate these disease-bearing insects is the use of specialized insecticides that target against the larval stage of a mosquito. These larvicides, like BinAB, kill some mosquito species, but they are currently ineffective against Aedes mosquitoes that transmit Zika and dengue fever. Now, an international team of researchers is working to develop a new toxin that will kill a broader range of mosquito species, including Aedes.

The existing larvicide BinAB is composed of two proteins, BinA and BinB, which pair together to form nanocrystals inside Lysinibacillus sphaericus soil bacteria. When these bacteria are distributed on the surface of stagnant water locations where mosquitoes breed, the mosquito larvae eat the bacteria — dissolving the nanocrystals that bind to their gut, activating the deadly BinAB toxin and killing the larvae.

The proteins are toxic to the mosquitoes, but harmless to humans and other animals. Unfortunately, previous research has shown that BinAB is also harmless to an Aedes mosquito, because the protein never binds to the insect’s gut so the toxin isn’t activated.

“Part of the appeal is that the larvicide’s safe because it’s so specific, but that’s also part of its limitation,” said Michael Sawaya, PhD, a scientist at the UCLA-DOE Molecular Biology Institute, in a recent news release.

Now, the researchers are adapting the BinAB toxin to attack mosquito species that are insecticide resistant. In order to do this, they needed to understand the 3-D structure of the BinAB proteins and how they work. This was a challenge, because the nanocrystals were so tiny and their structural details were a mystery.

The research team increased the size of the nanocrystals using genetic engineering, and then blasted them with an intense beam of bright, fast pulses of light using the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory. This allowed the team to collect detailed structural data from the tiny crystals and create 3-D maps of the electron density of the BinAB protein, as reported in a recent paper in Nature.

The LCLS experiments helped the researchers fully understand how the BinAB protein forms and functions. They are now engineering a modified version of the protein that will kill a broader range of mosquito species.

“The most immediate need is to now expand the spectrum of action of the BinAB toxin to counter the progression of Zika, in particular,” said Jacques-Philippe Colletier, PhD, a scientist at the Institut de Biologie Structurale in France, in the news release. “BinAB is already effective against Culex [carrier of West Nile encephalitis] and Anopheles [carrier of malaria] tos. With the results of the study, we now feel more confident that we can design the protein to target Aedes mosquitoes.”

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

Water purification: tiny solar device may have global impact

August 18, 2016
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Photograph, of researcher Chong Liu holding their nanostructured device, by Jin Xie.

Millions of people in developing countries lack access to safe drinking water, a primary cause of disease. Now, researchers from Stanford University and SLAC National Accelerator Laboratory have developed a tiny gadget that may help address this huge global health issue.

Their device — the size of half a postage stamp — uses solar energy to more efficiently purify water.

Solar energy is already commonly used to disinfect drinking water, particularly in areas with limited fuel to boil water. However, solar disinfection mostly relies on killing pathogens in the water with ultraviolet light, which represents only 4 percent of the sun’s total energy. This slow and inefficient purification process takes six to 48 hours.

The Stanford research team devised a new material that can significantly speed up this process by harvesting the whole spectrum of visible light, which corresponds to over 50 percent of solar energy. As reported this week in Nature Nanotechnology, they were able to disinfect nearly all of the bacteria in a small water sample in just 20 minutes.

“Our device looks like a little rectangle of black glass. We just dropped it into the water and put everything under the sun, and the sun did all the work,” said Chong Liu, PhD, lead author and postdoctoral researcher in materials science and engineering at Stanford, in a recent news release, which describes the device:

Under an electron microscope the surface of the device looks like a fingerprint, with many closely spaced lines. Those lines are very thin films — the researchers call them “nanoflakes” — of molybdenum disulfide that stacked on edge, like the walls of a labyrinth, atop a rectangle of glass.

By making their molybdenum disulfide walls in just the right thickness, the scientists got them to absorb the full range of visible sunlight. And by topping each tiny wall with a thin layer of copper, which also acts as a catalyst, they were able to use that sunlight to trigger exactly the reactions they wanted — reactions that produce “reactive oxygen species” like hydrogen peroxide, a commonly used disinfectant, which kill bacteria in the surrounding water.

Although promising, the researchers’ method doesn’t remove chemical pollutants and it has only been tested on three strains of bacteria mixed with less than an ounce of water in the lab. The next step will be to test the device in a real-world stew of contaminants.

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

A look at how social media helps connect patients with rare diseases

May 18, 2016
Photo by Jason Howie

Photo by Jason Howie

If you suffer from a very rare disease, getting the proper diagnosis can be an arduous journey. But a bigger challenge may be the feeling of isolation, since there may not be any support groups where you can connect to someone who is going through the same thing.

That was the situation the Bigelow family found themselves, and they turned to social media for the solution.

Bo Bigelow knew that his six-year-old daughter Tess had a genetic mutation called USP7. She also had global developmental delays in basic functions such as walking and talking, causing her to function at the level of an 18-month year old. Was USP7 the cause of her developmental delays?

Bigelow spread the word about his daughter’s genetic condition to find out, posting on Facebook, Twitter and a personal website with the plea to “help us find others like Tess.” A friend of the family also posted on Reddit, where it was read within 24 hours by a researcher at Baylor College of Medicine who was studying USP7. His research group had already identified seven children similarly affected by the same genetic mutation, and they were about to publish an article about it in Molecular Cell.

Tess may become part of future clinical trials at Baylor, but the researchers also connected the Bigelows to the other seven families. “These days there are ribbons and awareness-weeks for so many diseases,” Bigelow said in a recent KQED Science story, “but when yours is ultra-rare, you feel completed isolated. You feel like you’re never going to hear another person say, ‘Us too!’ And being connected to other families changes all that.”

The KQED piece goes on to explain:

“Patients or parents like Tess’ who are seeking answers to seemingly unsolvable medical mysteries have new tools to reach out, not only on social media, but in crowdsourcing websites like CrowdMed, a subscription service for people seeking answers to medical conundrums. At CrowdMed, people who have symptoms but have yet to find a diagnosis seek opinions from the site’s “medical detectives,” only some of whom are medical professionals.”

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

Tattoo ink may mimic cancer on PET-CT images

October 23, 2015
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Photograph by Paulo Guereta

The hit new crime thriller Blindspot is about a mysterious woman, Jane Doe, who is covered in extensive full-body tattoos. If Jane Doe were a real woman who ever needed medical imaging, she might need to be concerned.

In a case report published recently in the journal Obstetrics & Gynecology, researchers found that extensive tattoos can mimic metastases on images from positron emission tomography (PET) fused with computed tomography (CT). PET-CT imaging is commonly used to detect cancer, determine whether the cancer has spread and guide treatment decisions. A false-positive finding can result in unnecessary or incorrect treatment.

Ramez N. Eskander, MD, assistant professor of obstetrics and gynecology at UC Irvine, and his colleagues describe the case study of a 32-year-old woman with cervical cancer and extensive tattoos. The pre-operative PET-CT scan using fluorine-18-deoxyglucose confirmed that there was a large cervical cancer mass, but the scan also identified two ileac lymph nodes as suspicious for metastatic disease. However, final pathology showed extensive deposition of tattoo ink and no malignant cells in those ileac lymph nodes.

It is believed that carbon particles in the tattoo pigment migrate to the nearby lymph nodes through macrophages, using mechanisms similar to those seen in malignant melanoma. The researchers explain in their case report:

Our literature search yielded case reports describing the migration of tattoo ink to regional lymph nodes in patients with breast cancer, melanoma, testicular seminoma, and vulvar squamous cell carcinoma, making it difficult to differentiate grossly between the pigment and the metastatic disease, resulting in unnecessary treatment.

The authors warn other physicians to be aware of the possible effects of tattoo ink on PET-CT findings when formulating treatment plans, particularly for patients with extensive tattoos.

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


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