Tag Archives: MRI

Being smart about using artificial intelligence in the field of medicine

Since my August 20, 2018 post featured an opinion piece about the possibly imminent replacement of radiologists with artificial intelligence systems and the latest research about employing them for diagnosing eye diseases, it seems like a good time to examine some of the mythology embedded in the discussion about AI and medicine.

Imperfections in medical AI systems

An August 15, 2018 article for Slate.com by W. Nicholson Price II (who teaches at the University of Michigan School of Law; in addition to his law degree he has a PhD in Biological Sciences from Columbia University) begins with the peppy, optimistic view before veering into more critical territory (Note: Links have been removed),

For millions of people suffering from diabetes, new technology enabled by artificial intelligence promises to make management much easier. Medtronic’s Guardian Connect system promises to alert users 10 to 60 minutes before they hit high or low blood sugar level thresholds, thanks to IBM Watson, “the same supercomputer technology that can predict global weather patterns.” Startup Beta Bionics goes even further: In May, it received Food and Drug Administration approval to start clinical trials on what it calls a “bionic pancreas system” powered by artificial intelligence, capable of “automatically and autonomously managing blood sugar levels 24/7.”

An artificial pancreas powered by artificial intelligence represents a huge step forward for the treatment of diabetes—but getting it right will be hard. Artificial intelligence (also known in various iterations as deep learning and machine learning) promises to automatically learn from patterns in medical data to help us do everything from managing diabetes to finding tumors in an MRI to predicting how long patients will live. But the artificial intelligence techniques involved are typically opaque. We often don’t know how the algorithm makes the eventual decision. And they may change and learn from new data—indeed, that’s a big part of the promise. But when the technology is complicated, opaque, changing, and absolutely vital to the health of a patient, how do we make sure it works as promised?

Price describes how a ‘closed loop’ artificial pancreas with AI would automate insulin levels for diabetic patients, flaws in the automated system, and how companies like to maintain a competitive advantage (Note: Links have been removed),

[…] a “closed loop” artificial pancreas, where software handles the whole issue, receiving and interpreting signals from the monitor, deciding when and how much insulin is needed, and directing the insulin pump to provide the right amount. The first closed-loop system was approved in late 2016. The system should take as much of the issue off the mind of the patient as possible (though, of course, that has limits). Running a close-loop artificial pancreas is challenging. The way people respond to changing levels of carbohydrates is complicated, as is their response to insulin; it’s hard to model accurately. Making it even more complicated, each individual’s body reacts a little differently.

Here’s where artificial intelligence comes into play. Rather than trying explicitly to figure out the exact model for how bodies react to insulin and to carbohydrates, machine learning methods, given a lot of data, can find patterns and make predictions. And existing continuous glucose monitors (and insulin pumps) are excellent at generating a lot of data. The idea is to train artificial intelligence algorithms on vast amounts of data from diabetic patients, and to use the resulting trained algorithms to run a closed-loop artificial pancreas. Even more exciting, because the system will keep measuring blood glucose, it can learn from the new data and each patient’s artificial pancreas can customize itself over time as it acquires new data from that patient’s particular reactions.

Here’s the tough question: How will we know how well the system works? Diabetes software doesn’t exactly have the best track record when it comes to accuracy. A 2015 study found that among smartphone apps for calculating insulin doses, two-thirds of the apps risked giving incorrect results, often substantially so. … And companies like to keep their algorithms proprietary for a competitive advantage, which makes it hard to know how they work and what flaws might have gone unnoticed in the development process.

There’s more,

These issues aren’t unique to diabetes care—other A.I. algorithms will also be complicated, opaque, and maybe kept secret by their developers. The potential for problems multiplies when an algorithm is learning from data from an entire hospital, or hospital system, or the collected data from an entire state or nation, not just a single patient. …

The [US Food and Drug Administraiont] FDA is working on this problem. The head of the agency has expressed his enthusiasm for bringing A.I. safely into medical practice, and the agency has a new Digital Health Innovation Action Plan to try to tackle some of these issues. But they’re not easy, and one thing making it harder is a general desire to keep the algorithmic sauce secret. The example of IBM Watson for Oncology has given the field a bit of a recent black eye—it turns out that the company knew the algorithm gave poor recommendations for cancer treatment but kept that secret for more than a year. …

While Price focuses on problems with algorithms and with developers and their business interests, he also hints at some of the body’s complexities.

Can AI systems be like people?

Susan Baxter, a medical writer with over 20 years experience, a PhD in health economics, and author of countless magazine articles and several books, offers a more person-centered approach to the discussion in her July 6, 2018 posting on susanbaxter.com,

The fascination with AI continues to irk, given that every second thing I read seems to be extolling the magic of AI and medicine and how It Will Change Everything. Which it will not, trust me. The essential issue of illness remains perennial and revolves around an individual for whom no amount of technology will solve anything without human contact. …

But in this world, or so we are told by AI proponents, radiologists will soon be obsolete. [my August 20, 2018 post] The adaptational learning capacities of AI mean that reading a scan or x-ray will soon be more ably done by machines than humans. The presupposition here is that we, the original programmers of this artificial intelligence, understand the vagaries of real life (and real disease) so wonderfully that we can deconstruct these much as we do the game of chess (where, let’s face it, Big Blue ate our lunch) and that analyzing a two-dimensional image of a three-dimensional body, already problematic, can be reduced to a series of algorithms.

Attempting to extrapolate what some “shadow” on a scan might mean in a flesh and blood human isn’t really quite the same as bishop to knight seven. Never mind the false positive/negatives that are considered an acceptable risk or the very real human misery they create.

Moravec called it

It’s called Moravec’s paradox, the inability of humans to realize just how complex basic physical tasks are – and the corresponding inability of AI to mimic it. As you walk across the room, carrying a glass of water, talking to your spouse/friend/cat/child; place the glass on the counter and open the dishwasher door with your foot as you open a jar of pickles at the same time, take a moment to consider just how many concurrent tasks you are doing and just how enormous the computational power these ostensibly simple moves would require.

Researchers in Singapore taught industrial robots to assemble an Ikea chair. Essentially, screw in the legs. A person could probably do this in a minute. Maybe two. The preprogrammed robots took nearly half an hour. And I suspect programming those robots took considerably longer than that.

Ironically, even Elon Musk, who has had major production problems with the Tesla cars rolling out of his high tech factory, has conceded (in a tweet) that “Humans are underrated.”

I wouldn’t necessarily go that far given the political shenanigans of Trump & Co. but in the grand scheme of things I tend to agree. …

Is AI going the way of gene therapy?

Susan draws a parallel between the AI and medicine discussion with the discussion about genetics and medicine (Note: Links have been removed),

On a somewhat similar note – given the extent to which genetics discourse has that same linear, mechanistic  tone [as AI and medicine] – it turns out all this fine talk of using genetics to determine health risk and whatnot is based on nothing more than clever marketing, since a lot of companies are making a lot of money off our belief in DNA. Truth is half the time we don’t even know what a gene is never mind what it actually does;  geneticists still can’t agree on how many genes there are in a human genome, as this article in Nature points out.

Along the same lines, I was most amused to read about something called the Super Seniors Study, research following a group of individuals in their 80’s, 90’s and 100’s who seem to be doing really well. Launched in 2002 and headed by Angela Brooks Wilson, a geneticist at the BC [British Columbia] Cancer Agency and SFU [Simon Fraser University] Chair of biomedical physiology and kinesiology, this longitudinal work is examining possible factors involved in healthy ageing.

Turns out genes had nothing to do with it, the title of the Globe and Mail article notwithstanding. (“Could the DNA of these super seniors hold the secret to healthy aging?” The answer, a resounding “no”, well hidden at the very [end], the part most people wouldn’t even get to.) All of these individuals who were racing about exercising and working part time and living the kind of life that makes one tired just reading about it all had the same “multiple (genetic) factors linked to a high probability of disease”. You know, the gene markers they tell us are “linked” to cancer, heart disease, etc., etc. But these super seniors had all those markers but none of the diseases, demonstrating (pretty strongly) that the so-called genetic links to disease are a load of bunkum. Which (she said modestly) I have been saying for more years than I care to remember. You’re welcome.

The fundamental error in this type of linear thinking is in allowing our metaphors (genes are the “blueprint” of life) and propensity towards social ideas of determinism to overtake common sense. Biological and physiological systems are not static; they respond to and change to life in its entirety, whether it’s diet and nutrition to toxic or traumatic insults. Immunity alters, endocrinology changes, – even how we think and feel affects the efficiency and effectiveness of physiology. Which explains why as we age we become increasingly dissimilar.

If you have the time, I encourage to read Susan’s comments in their entirety.

Scientific certainties

Following on with genetics, gene therapy dreams, and the complexity of biology, the June 19, 2018 Nature article by Cassandra Willyard (mentioned in Susan’s posting) highlights an aspect of scientific research not often mentioned in public,

One of the earliest attempts to estimate the number of genes in the human genome involved tipsy geneticists, a bar in Cold Spring Harbor, New York, and pure guesswork.

That was in 2000, when a draft human genome sequence was still in the works; geneticists were running a sweepstake on how many genes humans have, and wagers ranged from tens of thousands to hundreds of thousands. Almost two decades later, scientists armed with real data still can’t agree on the number — a knowledge gap that they say hampers efforts to spot disease-related mutations.

In 2000, with the genomics community abuzz over the question of how many human genes would be found, Ewan Birney launched the GeneSweep contest. Birney, now co-director of the European Bioinformatics Institute (EBI) in Hinxton, UK, took the first bets at a bar during an annual genetics meeting, and the contest eventually attracted more than 1,000 entries and a US$3,000 jackpot. Bets on the number of genes ranged from more than 312,000 to just under 26,000, with an average of around 40,000. These days, the span of estimates has shrunk — with most now between 19,000 and 22,000 — but there is still disagreement (See ‘Gene Tally’).

… the inconsistencies in the number of genes from database to database are problematic for researchers, Pruitt says. “People want one answer,” she [Kim Pruitt, a genome researcher at the US National Center for Biotechnology Information {NCB}] in Bethesda, Maryland] adds, “but biology is complex.”

I wanted to note that scientists do make guesses and not just with genetics. For example, Gina Mallet’s 2005 book ‘Last Chance to Eat: The Fate of Taste in a Fast Food World’ recounts the story of how good and bad levels of cholesterol were established—the experts made some guesses based on their experience. That said, Willyard’s article details the continuing effort to nail down the number of genes almost 20 years after the human genome project was completed and delves into the problems the scientists have uncovered.

Final comments

In addition to opaque processes with developers/entrepreneurs wanting to maintain their secrets for competitive advantages and in addition to our own poor understanding of the human body (how many genes are there anyway?), there are same major gaps (reflected in AI) in our understanding of various diseases. Angela Lashbrook’s August 16, 2018 article for The Atlantic highlights some issues with skin cancer and shade of your skin (Note: Links have been removed),

… While fair-skinned people are at the highest risk for contracting skin cancer, the mortality rate for African Americans is considerably higher: Their five-year survival rate is 73 percent, compared with 90 percent for white Americans, according to the American Academy of Dermatology.

As the rates of melanoma for all Americans continue a 30-year climb, dermatologists have begun exploring new technologies to try to reverse this deadly trend—including artificial intelligence. There’s been a growing hope in the field that using machine-learning algorithms to diagnose skin cancers and other skin issues could make for more efficient doctor visits and increased, reliable diagnoses. The earliest results are promising—but also potentially dangerous for darker-skinned patients.

… Avery Smith, … a software engineer in Baltimore, Maryland, co-authored a paper in JAMA [Journal of the American Medical Association] Dermatology that warns of the potential racial disparities that could come from relying on machine learning for skin-cancer screenings. Smith’s co-author, Adewole Adamson of the University of Texas at Austin, has conducted multiple studies on demographic imbalances in dermatology. “African Americans have the highest mortality rate [for skin cancer], and doctors aren’t trained on that particular skin type,” Smith told me over the phone. “When I came across the machine-learning software, one of the first things I thought was how it will perform on black people.”

Recently, a study that tested machine-learning software in dermatology, conducted by a group of researchers primarily out of Germany, found that “deep-learning convolutional neural networks,” or CNN, detected potentially cancerous skin lesions better than the 58 dermatologists included in the study group. The data used for the study come from the International Skin Imaging Collaboration, or ISIC, an open-source repository of skin images to be used by machine-learning algorithms. Given the rise in melanoma cases in the United States, a machine-learning algorithm that assists dermatologists in diagnosing skin cancer earlier could conceivably save thousands of lives each year.

… Chief among the prohibitive issues, according to Smith and Adamson, is that the data the CNN relies on come from primarily fair-skinned populations in the United States, Australia, and Europe. If the algorithm is basing most of its knowledge on how skin lesions appear on fair skin, then theoretically, lesions on patients of color are less likely to be diagnosed. “If you don’t teach the algorithm with a diverse set of images, then that algorithm won’t work out in the public that is diverse,” says Adamson. “So there’s risk, then, for people with skin of color to fall through the cracks.”

As Adamson and Smith’s paper points out, racial disparities in artificial intelligence and machine learning are not a new issue. Algorithms have mistaken images of black people for gorillas, misunderstood Asians to be blinking when they weren’t, and “judged” only white people to be attractive. An even more dangerous issue, according to the paper, is that decades of clinical research have focused primarily on people with light skin, leaving out marginalized communities whose symptoms may present differently.

The reasons for this exclusion are complex. According to Andrew Alexis, a dermatologist at Mount Sinai, in New York City, and the director of the Skin of Color Center, compounding factors include a lack of medical professionals from marginalized communities, inadequate information about those communities, and socioeconomic barriers to participating in research. “In the absence of a diverse study population that reflects that of the U.S. population, potential safety or efficacy considerations could be missed,” he says.

Adamson agrees, elaborating that with inadequate data, machine learning could misdiagnose people of color with nonexistent skin cancers—or miss them entirely. But he understands why the field of dermatology would surge ahead without demographically complete data. “Part of the problem is that people are in such a rush. This happens with any new tech, whether it’s a new drug or test. Folks see how it can be useful and they go full steam ahead without thinking of potential clinical consequences. …

Improving machine-learning algorithms is far from the only method to ensure that people with darker skin tones are protected against the sun and receive diagnoses earlier, when many cancers are more survivable. According to the Skin Cancer Foundation, 63 percent of African Americans don’t wear sunscreen; both they and many dermatologists are more likely to delay diagnosis and treatment because of the belief that dark skin is adequate protection from the sun’s harmful rays. And due to racial disparities in access to health care in America, African Americans are less likely to get treatment in time.

Happy endings

I’ll add one thing to Price’s article, Susan’s posting, and Lashbrook’s article about the issues with AI , certainty, gene therapy, and medicine—the desire for a happy ending prefaced with an easy solution. If the easy solution isn’t possible accommodations will be made but that happy ending is a must. All disease will disappear and there will be peace on earth. (Nod to Susan Baxter and her many discussions with me about disease processes and happy endings.)

The solutions, for the most part, are seen as technological despite the mountain of evidence suggesting that technology reflects our own imperfect understanding of health and disease therefore providing what is at best an imperfect solution.

Also, we tend to underestimate just how complex humans are not only in terms of disease and health but also with regard to our skills, understanding, and, perhaps not often enough, our ability to respond appropriately in the moment.

There is much to celebrate in what has been accomplished: no more black death, no more smallpox, hip replacements, pacemakers, organ transplants, and much more. Yes, we should try to improve our medicine. But, maybe alongside the celebration we can welcome AI and other technologies with a lot less hype and a lot more skepticism.

Getting chipped

A January 23, 2018 article by John Converse Townsend for Fast Company highlights the author’s experience of ‘getting chipped’ in Wisconsin (US),

I have an RFID, or radio frequency ID, microchip implanted in my hand. Now with a wave, I can unlock doors, fire off texts, login to my computer, and even make credit card payments.

There are others like me: The majority of employees at the Wisconsin tech company Three Square Market (or 32M) have RFID implants, too. Last summer, with the help of Andy “Gonzo” Whitehead, a local body piercer with 17 years of experience, the company hosted a “chipping party” for employees who’d volunteered to test the technology in the workplace.

“We first presented the concept of being chipped to the employees, thinking we might get a few people interested,” CEO [Chief Executive Officer] Todd Westby, who has implants in both hands, told me. “Literally out of the box, we had 40 people out of close to 90 that were here that said, within 10 minutes, ‘I would like to be chipped.’”

Westby’s left hand can get him into the office, make phone calls, and stores his living will and drivers license information, while the chip in his right hand is using for testing new applications. (The CEO’s entire family is chipped, too.) Other employees said they have bitcoin wallets and photos stored on their devices.

The legendary Gonzo Whitehead was waiting for me when I arrived at Three Square Market HQ, located in quiet River Falls, 40 minutes east of Minneapolis. The minutes leading up to the big moment were a bit nervy, after seeing the size of the needle (it’s huge), but the experience was easier than I could have imagined. The RFID chip is the size of a grain of basmati rice, but the pain wasn’t so bad–comparable to a bee sting, and maybe less so. I experienced a bit of bruising afterward (no bleeding), and today the last remaining mark of trauma is a tiny, fading scar between my thumb and index finger. Unless you were looking for it, the chip resting under my skin is invisible.

Truth is, the applications for RFID implants are pretty cool. But right now, they’re also limited. Without a near-field communication (NFC) writer/reader, which powers on a “passive” RFID chip to write and read information to the device’s memory, an implant isn’t of much use. But that’s mostly a hardware issue. As NFC technology becomes available, which is increasingly everywhere thanks to Samsung Pay and Apple Pay and new contactless “tap-and-go” credit cards, the possibilities become limitless. [emphasis mine]

Health and privacy?

Townsend does cover a few possible downsides to the ‘limitless possibilities’ offered by RFID’s combined with NFC technology,

From a health perspective, the RFID implants are biologically safe–not so different from birth control implants [emphasis mine]. [US Food and Drug Administration] FDA-sanctioned for use in humans since 2004, the chips neither trigger metal detectors nor disrupt [magnetic resonance imaging] MRIs, and their glass casings hold up to pressure testing, whether that’s being dropped from a rooftop or being run over by a pickup truck.

The privacy side of things is a bit more complicated, but the undeniable reality is that privacy isn’t as prized as we’d like to think [emphasis mine]. It’s already a regular concession to convenience.

“Your information’s for sale every day,” McMullen [Patrick McMullen, president, Three Square Market] says. “Thirty-four billion avenues exist for your information to travel down every single day, whether you’re checking Facebook, checking out at the supermarket, driving your car . . . your information’s everywhere.

Townsend may not be fully up-to-date on the subject of birth control implants. I think ‘safeish’ might be a better description in light of this news of almost two years ago (from a March 1, 2016 news item on CBS [Columbia Broadcasting Service] News [online]), Note: Links have been removed,

[US] Federal health regulators plan to warn consumers more strongly about Essure, a contraceptive implant that has drawn thousands of complaints from women reporting chronic pain, bleeding and other health problems.

The Food and Drug Administration announced Monday it would add a boxed warning — its most serious type — to alert doctors and patients to problems reported with the nickel-titanium implant.

But the FDA stopped short of removing the device from the market, a step favored by many women who have petitioned the agency in the last year. Instead, the agency is requiring manufacturer Bayer to conduct studies of the device to further assess its risks in different groups of women.

The FDA is requiring Bayer to conduct a study of 2,000 patients comparing problems like unplanned pregnancy and pelvic pain between patients getting Essure and those receiving traditional “tube tying” surgery. Agency officials said they have reviewed more than 600 reports of women becoming pregnant after receiving Essure. Women are supposed to get a test after three months to make sure Essure is working appropriately, but the agency noted some women do not follow-up for the test.

FDA officials acknowledged the proposed study would take years to complete, but said Bayer would be expected to submit interim results by mid-2017.

According to a Sept. 25, 2017 article by Kerri O’Brien for WRIC.com, Bayer had suspended sales of their device in all countries except the US,

Bayer, the manufacturer of Essure, has announced it’s halting sales of Essure in all countries outside of the U.S. In a statement, Bayer told 8News it’s due to a lack of interest in the product outside of the U.S.

“Bayer made a commercial decision this Spring to discontinue the distribution of Essure® outside of the U.S. where there is not as much patient interest in permanent birth control,” the statement read.

The move also comes after the European Union suspended sales of the device. The suspension was prompted by the National Standards Authority of Ireland declining to renew Essure’s CE marketing. “CE,” according to the European Commission website signifies products sold in the EEA that has been assessed to meet “high safety, health, and environmental protection requirements.”

These excerpts are about the Essure birth control implant. Perhaps others are safer? That noted, it does seem that Townsend was a bit dismissive of safety concerns.

As for privacy, he does investigate further to discover this,

As technology evolves and becomes more sophisticated, the methods to break it also evolve and get more sophisticated, says D.C.-based privacy expert Michelle De Mooy. Even so, McMullen believes that our personal information is safer in our hand than in our wallets. He  says the smartphone you touch 2,500 times a day does 100 times more reporting of data than does an RFID implant, plus the chip can save you from pickpockets and avoid credit card skimmers altogether.

Well, the first sentence suggests some caution. As for De Mooy, there’s this from her profile page on the Center for Democracy and Technology website (Note: A link has been removed),

Michelle De Mooy is Director of the Privacy & Data Project at the Center for Democracy & Technology. She advocates for data privacy rights and protections in legislation and regulation, works closely with industry and other stakeholders to investigate good data practices and controls, as well as identifying and researching emerging technology that impacts personal privacy. She leads CDT’s health privacy work, chairing the Health Privacy Working Group and focusing on the intersection between individual privacy, health information and technology. Michelle’s current research is focused on ethical and privacy-aware internal research and development in wearables, the application of data analytics to health information found on non-traditional platforms, like social media, and the growing market for genetic data. She has testified before Congress on health policy, spoken about native advertising at the Federal Trade Commission, and written about employee wellness programs for US News & World Report’s “Policy Dose” blog. Michelle is a frequent media contributor, appearing in the New York Times, the Guardian, the Wall Street Journal, Vice, and the Los Angeles Times, as well as on The Today Show, Voice of America, and Government Matters TV programs.

Ethics anyone?

Townsend does raise some ethical issues (Note: A link has been removed),

… Word from CEO Todd Westby is that parents in Wisconsin have been asking whether (and when) they can have their children implanted with GPS-enabled devices (which, incidentally, is the subject of the “Arkangel” episode in the new season of Black Mirror [US television programme]). But that, of course, raises ethical questions: What if a kid refused to be chipped? What if they never knew?

Final comments on implanted RFID chips and bodyhacking

It doesn’t seem that implantable chips have changed much since I first wrote about them in a May 27, 2010 posting titled: Researcher infects self with virus.  In that instance, Dr Mark Gasson, a researcher at the University of Reading. introduced a virus into a computer chip implanted in his body.

Of course since 2010, there are additional implantable items such as computer chips and more making their way into our bodies and it doesn’t seem to be much public discussion (other than in popular culture) about the implications.

Presumably, there are policy makers tracking these developments. I have to wonder if the technology gurus will continue to tout these technologies as already here or having made such inroads that we (the public) are presented with a fait accompli with the policy makers following behind.

Quantum device provides capabilities of Dr. Who’s sonic screwdriver and Star Trek’s tricorder

I think these Australian scientists are bigger fans of Dr. Who than Star Trek if I read this March 8, 2017 news item on Nanowerk rightly (Note: A link has been removed),

Physicists have designed a handheld device inspired by the sonic screwdriver in Doctor Who and the tricorder in Star Trek that will use the power of MRI and mass spectrometry to perform a chemical analysis of objects (Nano Letters, “Nanomechanical Sensing Using Spins in Diamond”).

The sonic screwdriver is a tool used in Doctor Who to scan and identify matter, among other functions, while the multi-purpose tricorder in Star Trek can provide a detailed analysis of living things.

This video confirms the scientists’ Dr. Who fanhood,

A March 8, 2017 Australian National University (ANU) news release, which originated the news item, provides more technical detail about the research,

Lead researcher Dr Marcus Doherty from ANU said the team had proven the concept of a diamond-based quantum device to perform similar functions to these science fiction tools and would now develop a prototype.

“Laboratories and hospitals will have the power to do full chemical analyses to solve complex problems with our device that they can afford and move around easily,” said Dr Doherty from the ANU Research School of Physics and Engineering (RSPE).

“This device is going to enable many people to use powerful instruments like molecular MRI machines and mass spectrometers much more readily.”

Dr Doherty said medical researchers could use the device to weigh and identify complex molecules such as proteins, which drive diseases, such as cancer, and cures for those diseases.

“Every great advance for microscopy has driven scientific revolution,” he said.

“Our invention will help to solve many complex problems in a wide range of areas, including medical, environmental and biosecurity research.”

Molecular MRI is a form of the common medical imaging technology that is capable of identifying the chemical composition of individual molecules, while mass spectrometers measure the masses within a sample.

Co-researcher Michael Barson said the device would use tiny defects in a diamond to measure the mass and chemical composition of molecules with advanced quantum techniques borrowed from atomic clocks and gravitational wave detectors.

“For the mass spectrometry, when a molecule attaches to the diamond device, its mass changes, which changes the frequency, and we measure the change in frequency using the defects in the diamond,” said Mr Barson, a PhD student from RSPE.

“For the MRI, we are looking at how the magnetic fields in the molecule will influence the defects as well.”

Here’s a link to and a citation for the paper,

Nanomechanical Sensing Using Spins in Diamond by Michael S. J. Barson, Phani Peddibhota, Preeti Ovartchaiyapong, Kumaravelu Ganesan, Richard L. Taylor, Matthew Gebert, Zoe Mielens, Berndt Koslowski, David A. Simpson, Liam P. McGuinness, Jeffrey McCallum, Steven Prawer, Shinobu Onoda, Takeshi Ohshima, Ania C. Bleszynski Jayich, Fedor Jelezko, Neil B. Manson, and Marcus W. Doherty. Nano Lett., 2017, 17 (3), pp 1496–1503 DOI: 10.1021/acs.nanolett.6b04544 Publication Date (Web): February 1, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Nuclear magnetic resonance microscope breaks records

Dutch researchers have found a way to apply the principles underlying magnetic resonance imaging (MRI) to a microscope designed *for* examining matter and life at the nanoscale. From a July 15, 2016 news item on phys.org,

A new nuclear magnetic resonance (NMR) microscope gives researchers an improved instrument to study fundamental physical processes. It also offers new possibilities for medical science—for example, to better study proteins in Alzheimer’s patients’ brains. …

A Leiden Institute of Physics press release, which originated the news item, expands on the theme,

If you get a knee injury, physicians use an MRI machine to look right through the skin and see what exactly is the problem. For this trick, doctors make use of the fact that our body’s atomic nuclei are electrically charged and spin around their axis. Just like small electromagnets they induce their own magnetic field. By placing the knee in a uniform magnetic field, the nuclei line up with their axis pointing in the same direction. The MRI machine then sends a specific type of radio waves through the knee, causing some axes to flip. After turning off this signal, those nuclei flip back after some time, under excitation of a small radio wave. Those waves give away the atoms’ location, and provide physicians with an accurate image of the knee.

NMR

MRI is the medical application of Nuclear Magnetic Resonance (NMR), which is based on the same principle and was invented by physicists to conduct fundamental research on materials. One of the things they study with NMR is the so-called relaxation time. This is the time scale at which the nuclei flip back and it gives a lot of information about a material’s properties.

Microscope

To study materials on the smallest of scales as well, physicists go one step further and develop NMR microscopes, with which they study the mechanics behind physical processes at the level of a group of atoms. Now Leiden PhD students Jelmer Wagenaar and Arthur de Haan have built an NMR microscope, together with principal investigator Tjerk Oosterkamp, that operates at a record temperature of 42 milliKelvin—close to absolute zero. In their article in Physical Review Applied they prove it works by measuring the relaxation time of copper. They achieved a thousand times higher sensitivity than existing NMR microscopes—also a world record.

Alzheimer

With their microscope, they give physicists an instrument to conduct fundamental research on many physical phenomena, like systems displaying strange behavior in extreme cold. And like NMR eventually led to MRI machines in hospitals, NMR microscopes have great potential too. Wagenaar: ‘One example is that you might be able to use our technique to study Alzheimer patients’ brains at the molecular level, in order to find out how iron is locked up in proteins.’

Here’s a link to and a citation for the paper,

Probing the Nuclear Spin-Lattice Relaxation Time at the Nanoscale by J. J. T. Wagenaar, A. M. J. den Haan, J. M. de Voogd, L. Bossoni, T. A. de Jong, M. de Wit, K. M. Bastiaans, D. J. Thoen, A. Endo, T. M. Klapwijk, J. Zaanen, and T. H. Oosterkamp. Phys. Rev. Applied 6, 014007 DOI:http://dx.doi.org/10.1103/PhysRevApplied.6.014007 Published 15 July 2016

This paper is open access.

*’fro’ changed to ‘for’ on Aug. 3, 2016.

Measuring a singular spin of a biological molecule

I gather there are some Swiss scientists excited about obtaining experimental proof for room temperature detection of a  biological molecule’s spin. From a May 11, 2015 news item on Nanowerk (Note: A link has been removed),

Physicists of the University of Basel and the Swiss Nanoscience Institute were able to show for the first time that the nuclear spins of single molecules can be detected with the help of magnetic particles at room temperature.

In Nature Nanotechnology (“High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature”), the researchers describe a novel experimental setup with which the tiny magnetic fields of the nuclear spins of single biomolecules – undetectable so far – could be registered for the first time. The proposed concept would improve medical diagnostics as well as analyses of biological and chemical samples in a decisive step forward.

A May 11, 2015 University of Basel press release, which originated the news item, explains why the researchers are excited about a ‘room temperature’ approach to measuring a nuclear spin,

The measurement of nuclear spins is routine by now in medical diagnostics (MRI). However, the currently existing devices need billions of atoms for the analysis and thus are not useful for many small-scale applications. Over many decades, scientists worldwide have thus engaged in an intense search for alternative methods, which would improve the sensitivity of the measurement techniques.

With the help of various types of sensors (SQUID- and Hall-sensors) and with magnetic resonance force microscopes, it has become possible to detect spins of single electrons and achieve structural resolution at the nanoscale. However, the detection of single nuclear spins of complex biological samples – the holy grail in the field – has not been possible so far.

Diamond crystals with tiny defects

The researchers from Basel now investigate the application of sensors made out of diamonds that host tiny defects in their crystal structure. In the crystal lattice of the diamond a Carbon atom is replaced by a Nitrogen atom, with a vacant site next to it. These so-called Nitrogen-Vacancy (NV) centers generate spins, which are ideally suited for detection of magnetic fields. At room temperature, researchers have shown experimentally in many labs before that with such NV centers resolution of single molecules is possible. However, this requires atomistically close distances between sensor and sample, which is not possible for biological material.

A tiny ferromagnetic particle, placed between sample and NV center, can solve this problem. Indeed, if the nuclear spin of the sample is driven at a specific resonance frequency, the resonance of the ferromagnetic particle changes. With the help of an NV center that is in close proximity of the magnetic particle, the scientists can then detect this modified resonance.

Measuring technology breakthrough?

The theoretical analysis and experimental techniques of the researchers in the teams of Prof. Daniel Loss and Prof. Patrick Maletinsky have shown that the use of such ferromagnetic particles can lead to a ten-thousand-fold amplification of the magnetic field of nuclear spins. „I am confident that our concept will soon be implemented in real systems and will lead to a breakthrough in metrology“ [science of measurement], comments Daniel Loss the recent publication, where the first author Dr. Luka Trifunovic, postdoc in the Loss team, made essential contributions and which was performed in collaboration with colleagues from the JARA Institute for Quantum Information (Aachen, Deutschland) and the Harvard University (Cambridge, USA).

Here’s a link to and a citation for the paper,

High-efficiency resonant amplification of weak magnetic fields for single spin magnetometry at room temperature by  Luka Trifunovic, Fabio L. Pedrocchi, Silas Hoffman, Patrick Maletinsky, Amir Yacoby, & Daniel Loss. Nature Nanotechnology (2015) doi:10.1038/nnano.2015.74 Published online 11 May 2015

This paper is behind a paywall.

Université de Montréal (Canada) and nanobots breech blood-brain barrier to deliver drugs to the brain

In the spirit of full disclosure, the March 25, 2014 news item on ScienceDaily describing the research about breeching the blood-brain barrier uses the term nanorobotic agents rather than nanobots, a term which makes my headline a lot catchier although less accurate. Getting back to the research,

Magnetic nanoparticles can open the blood-brain barrier and deliver molecules directly to the brain, say researchers from the University of Montreal, Polytechnique Montréal, and CHU Sainte-Justine. This barrier runs inside almost all vessels in the brain and protects it from elements circulating in the blood that may be toxic to the brain. The research is important as currently 98% of therapeutic molecules are also unable to cross the blood-brain barrier.

“The barrier is temporary [sic] opened at a desired location for approximately 2 hours by a small elevation of the temperature generated by the nanoparticles when exposed to a radio-frequency field,” explained first author and co-inventor Seyed Nasrollah Tabatabaei. “Our tests revealed that this technique is not associated with any inflammation of the brain. This new result could lead to a breakthrough in the way nanoparticles are used in the treatment and diagnosis of brain diseases,” explained the co-investigator, Hélène Girouard. “At the present time, surgery is the only way to treat patients with brain disorders. Moreover, while surgeons are able to operate to remove certain kinds of tumors, some disorders are located in the brain stem, amongst nerves, making surgery impossible,” added collaborator and senior author Anne-Sophie Carret.

A March 25, 2015 University of Montreal news release (also on EurekAlert), which originated the news item, notes that the technique was tested or rats or mice (murine model) and explains how the technology breeches the blood-brain barrier,

Although the technology was developed using murine models and has not yet been tested in humans, the researchers are confident that future research will enable its use in people. “Building on earlier findings and drawing on the global effort of an interdisciplinary team of researchers, this technology proposes a modern version of the vision described almost 40 years ago in the movie Fantastic Voyage, where a miniature submarine navigated in the vascular network to reach a specific region of the brain,” said principal investigator Sylvain Martel. In earlier research, Martel and his team had managed to manipulate the movement of nanoparticles through the body using the magnetic forces generated by magnetic resonance imaging (MRI) machines.

To open the blood-brain barrier, the magnetic nanoparticles are sent to the surface of the blood-brain barrier at a desired location in the brain. Although it was not the technique used in this study, the placement could be achieved by using the MRI technology described above. Then, the researchers generated a radio-frequency field. The nanoparticles reacted to the radio-frequency field by dissipating heat thereby creating a mechanical stress on the barrier. This allows a temporary and localized opening of the barrier for diffusion of therapeutics into the brain.

The technique is unique in many ways. “The result is quite significant since we showed in previous experiments that the same nanoparticles can also be used to navigate therapeutic agents in the vascular network using a clinical MRI scanner,” Martel remarked. “Linking the navigation capability with these new results would allow therapeutics to be delivered directly to a specific site of the brain, potentially improving significantly the efficacy of the treatment while avoiding systemic circulation of toxic agents that affect healthy tissues and organs,” Carret added. “While other techniques have been developed for delivering drugs to the blood-brain barrier, they either open it too wide, exposing the brain to great risks, or they are not precise enough, leading to scattering of the drugs and possible unwanted side effect,” Martel said.

Although there are many hurdles to overcome before the technology can be used to treat humans, the research team is optimistic. “Although our current results are only proof of concept, we are on the way to achieving our goal of developing a local drug delivery mechanism that will be able to treat oncologic, psychiatric, neurological and neurodegenerative disorders, amongst others,” Carret concluded.

Here’s a link to and a citation for the paper,

Remote control of the permeability of the blood–brain barrier by magnetic heating of nanoparticles: A proof of concept for brain drug delivery by Seyed Nasrollah Tabatabaei, Hélène Girouard, Anne-Sophie Carret, and Sylvain Martel.Journal of Controlled Release, Volume 206, 28 May 2015, Pages 49–57,  DOI: 10.1016/j.jconrel.2015.02.027  Available online 25 February 2015

This paper is behind a paywall.

For anyone unfamiliar with French, University of Montreal is Université de Montréal.

Green tea to improve MRIs (magnetic resonance images)?

Sadly, this new technique does not require the ingestion of green tea prior to an MRI session. A March 18, 2015 American Chemical Society press release on EurekAlert provides detals,

Green tea’s popularity has grown quickly in recent years. Its fans can drink it, enjoy its flavor in their ice cream and slather it on their skin with lotions infused with it. Now, the tea could have a new, unexpected role — to improve the image quality of MRIs. Scientists report in the journal ACS Applied Materials & Interfaces that they successfully used compounds from green tea to help image cancer tumors in mice.

Sanjay Mathur and colleagues note that recent research has revealed the potential usefulness of nanoparticles — iron oxide in particular — to make biomedical imaging better. But the nanoparticles have their disadvantages. They tend to cluster together easily and need help getting to their destinations in the body. To address these issues, researchers have recently tried attaching natural nutrients to the nanoparticles. Mathur’s team wanted to see if compounds from green tea, which research suggests has anticancer and anti-inflammatory properties, could play this role.

Using a simple, one-step process, the researchers coated iron-oxide nanoparticles with green-tea compounds called catechins and administered them to mice with cancer. MRIs demonstrated that the novel imaging agents gathered in tumor cells and showed a strong contrast from surrounding non-tumor cells. The researchers conclude that the catechin-coated nanoparticles are promising candidates for use in MRIs and related applications.

Here’s a link to and a citation for the paper,

Enhanced In Vitro and In Vivo Cellular Imaging with Green Tea Coated Water-Soluble Iron Oxide Nanocrystals by Lisong Xiao, Marianne Mertens, Laura Wortmann, Silke Kremer, Martin Valldor, Twan Lammers, Fabian Kiessling, and Sanjay Mathur. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/am508404t Publication Date (Web): March 2, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Water cages made of buckyballs could affect nuclear magnetic resonance and magnetic resonance imaging (MRI)

I wasn’t expecting to find this May 20, 2014 news item on Nanowerk to be* quite so fascinating, especially as It gets off to a slow start (a link has been removed),

In a new paper in The Journal of Chemical Physics (“Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance”), produced by AIP Publishing, a research team in the United Kingdom and the United States describes how water molecules “caged” in fullerene spheres (“buckyballs”) are providing a deeper insight into spin isomers — varieties of a molecule that differ in their nuclear spin. The results of this work may one day help enhance the analytical and diagnostic power of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).

A May 20, 2014 American Institute of Physics (AIP) news release on EurekAlert, which originated the news item, provides some information about water molecules prior to describing the research in more detail,

Water molecules can exist as one of two isomers depending on how the spins of their two hydrogen atoms are oriented: ortho, where the spins are parallel and have a spin number of 1, and para, where the spins are antiparallel and have a spin number of 0. Scientists believe that any given molecule can transform from ortho- into para- spin states and vice versa, a process known as nuclear spin conversion.

“Currently, mechanisms for this conversion are not completely understood, nor how long it takes the molecules to transform from one spin isomer to the other,” said Salvatore Mamone, a post-doctoral physicist at the University of Southampton and lead author on the JCP paper. “To study this, we had to figure out how to reduce the strong intermolecular interactions that are responsible for aggregation and lower the rotational mobility of the water molecules.”

Next, there’s a brief summarized version of the research (from the news release),

The answer was to use chemical reactions to open a hole in fullerene (C60, also known as a buckyball) spheres, inject water molecules and then close the “cages” to form a complex referred to as H2O@C60. “At the end of this synthetic preparation nicknamed ‘molecular surgery,’ we find that 70 to 90 percent of the cages are filled, giving us a significant quantity of water molecules to examine,” Mamone said. “Because the [water] molecules are kept separated by the cages, there is a large rotational freedom that makes observation of the ortho and para isomers possible.”

This is followed by more technical details,

In their experiment, the researchers quickly cooled the individual H2O@C60 samples from 50 Kelvin (minus 223 degrees Celsius) to 5 K (minus 268 degrees Celsius) and then monitored their NMR signal every few minutes over several days.

“As the observed NMR signal is proportional to the amount of ortho-water in the sample [para-water with its spin number of 0 is “NMR silent”], we can track the percentages of ortho and para isomers at any time and any temperature,” Mamone explained. “At 50 K, we find that 75 percent of the water molecules are ortho, while at 5 K, they become almost 100 percent para. Therefore, we know that after the quick temperature jump, equilibrium is restored by conversion from ortho to para—and we see that conversion in real time.”

A surprising outcome of the experiment was that the researchers observed a second-order rate law in the kinetics of the spin conversion which proves that pairs of molecules have to interact for conversion to occur. “Previous studies have speculated that other nuclear spins can cause conversion but we found this not to be the case for H2O@C60,” Mamone said.

Next up, the research team plans to study the roles of isomer concentrations and temperature in the conversion process, the conversion of para-water to ortho (“back conversion”), how to detect single ortho- and para-water molecules on surfaces, and spin isomers in other fullerene-caged molecules.

Bravo to the news release writer for a very nice explanation of the science!

Here’s a link to and a citation for the paper,

Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance by Salvatore Mamone, Maria Concistré, Elisa Carignani, Benno Meier, Andrea Krachmalnicoff, Ole G. Johannessen, Xuegong Lei, Yongjun Li, Mark Denning, Marina Carravetta, Kelvin Goh, Anthony J. Horsewill, Richard J. Whitby and Malcolm H. Levitt.  J. Chem. Phys. 140, 194306 (2014) DOI: 10.1063/1.4873343

This is an open access paper.

* ‘to be’ added on July 16, 2014.

Nanodiamonds as imaging devices

Two different teams have recently published studies in Science magazine (Feb. 1, 2013 issue) about their work with nanodiamonds, flaws, and imaging in what seems to be a case of synchronicity as there are no obvious connections between the teams.

Sabrina Richards writes in her Jan. 31, 2013 article for The Scientist about the possibility of taking snapshots of molecules at some time in the future (Note: Links have been removed),

A miniscule diamond flaw—just two atoms different—could someday enable researchers to image single molecules without resorting to time-consuming and technically exacting X-ray crystallography. The new approach, published today (January 31 [sic]) in Science, relies on a single electron to detect perturbation in molecular magnetic fields, which can provide clues about the structures of proteins and other molecules.

The work was inspired by magnetic resonance imaging (MRI), which uses electromagnetic coils to detect the magnetic fields emitted by hydrogen atom protons.  But traditional MRI requires many trillions of protons to get a clear image—of a brain, for example—preventing scientists from visualizing anything much smaller than millimeters-wide structures. To detect just a few protons, such as those of a single molecule, scientists would need an atomic-scale sensor.

To construct such a sensor, physicists Daniel Rugar at IBM Research and David Awschalom at the University of California, Santa Barbara, turned to diamonds. A perfect diamond, made entirely of carbon atoms covalently bonded to each other, has no free electrons and therefore no magnetic properties, explained Hammel. But a special kind of defect, known as a nitrogen-vacancy (NV) center, confers unique magnetic properties.

Jyllian Kemsley’s Jan. 31, 2013 article for C&EN (Chemical and Engineering News) discusses the work from both teams and describes the technique they used,

To downscale NMR [aka MRI], both groups used a detector made of diamond with a site defect called a single nitrogen-vacancy (NV) center, in which a nitrogen atom and a lattice hole replace two adjacent carbon atoms. Prior work had determined that NV centers are sensitive to the internal magnetic fields of the diamond. The new research demonstrates that the fluorescence of such centers can be used to detect magnetic fields emanating from just outside the diamond. Both groups were able to use NV centers to detect nuclear polarization of hydrogens in poly(methyl methacrylate) with a sample volume lower limit of about (5 nm)3. Further development is necessary to extract structural information.

Still, nothing much has happened with this technique as Richards notes in her article,

So far, the study is “just a proof of principle,” noted Awschalom. The researchers haven’t actually imaged any molecules yet, but simply detected their presence. Still, Awschalom said, “we’ve shown it’s not a completely ridiculous idea to detect external nuclear magnetic fields with one electron.” …

Here’s a citation and a link to the article,

Nanoscale Nuclear Magnetic Resonance with a Nitrogen-Vacancy Spin Sensor by H. J. Mamin, M. Kim, M. H. Sherwood, C. T. Rettner, K. Ohno, D. D. Awschalom, D. Rugar. Science 1 February 2013: Vol. 339 no. 6119 pp. 557-560 DOI: 10.1126/science.1231540

The other research is described in a Feb. 14, 2013 news item on Azonano,

Magnetic resonance imaging (MRI) reveals details of living tissues, diseased organs and tumors inside the body without x-rays or surgery. What if the same technology could peer down to the level of atoms? Doctors could make visual diagnoses of a person’s molecules – examining damage on a strand of DNA, watching molecules misfold, or identifying a cancer cell by the proteins on its surface.

It is remarkably  similar work as Kemsley notes not helped by the fact that the one line description for both articles in Science magazine’s Table of Contents is identical.  (One line description: The optical response of the spin of a near-surface atomic defect in diamond can be used to sense proton magnetic fields.) The City College of New York City Feb. 13, 2013 news release, which originated the Azonano news item about the other team, offers more details,

 … Dr. Carlos Meriles, associate professor of physics at The City College of New York, and an international team of researchers at the University of Stuttgart and elsewhere have opened the door for nanoscale MRI. They used tiny defects in diamonds to sense the magnetic resonance of molecules. They reported their results in the February 1 [2013] issue of Science.

“It is bringing MRI to a level comparable to an atomic force microscope,” said Professor Meriles, referring to the device that traces the contours of atoms or tugs on a molecule to measure its strength. A nanoscale MRI could display how a molecule moves without touching it.

“Standard MRI typically gets to a resolution of 100 microns,” about the width of a human hair, said Professor Meriles. “With extraordinary effort,” he said, “it can get down to about 10 microns” – the width of a couple of blood cells. Nanoscale MRI would have a resolution 1,000 to 10,000 times better.

To try to pick up magnetic resonance on such a small scale, the team took advantage of the spin of protons in an atom, a property usually used to investigate quantum computing. In particular, they used minute imperfections in diamonds.

Diamonds are crystals made up almost entirely of carbon atoms. When a nitrogen atom lodges next to a spot where a carbon atom is missing, however, it creates a defect known as a nitrogen-vacancy (NV) center.

“These imperfections turn out to have a spin – like a little compass – and have some remarkable properties,” noted Professor Meriles. In the last few years, researchers realized that these NV centers could serve as very sensitive sensors. They can pick up the magnetic resonance of nearby atoms in a cell, for example. But unlike the atoms in a cell, the NVs shine when a light is directed at them, signaling what their spin is. If you illuminate it with green light it flashes red back.

“It is a form of what is called optically detected magnetic resonance,” he said. Like a hiker flashing Morse code on a hillside, the sensor “sends back flashes to say it is alive and well.”

“The NV can also be thought of as an atomic magnet. You can manipulate the spin of that atomic magnet just like you do with MRI by applying a radio frequency or radio pulses,” Professor Meriles explained. The NV responds. Shine a green light at it when the spin is pointing up and it will respond with brighter red light. A down spin gives a dimmer red light.

In the lab, graduate student Tobias Staudacher — the first author in this work — used NVs that had been created just below the diamond’s surface by bombarding it with nitrogen atoms. The team detected magnetic resonance within a film of organic material applied to the surface, just as one might examine a thin film of cells or tissue.

“Ultimately,” said Professor Meriles, “One will use a nitrogen-vacancy mounted on the tip of an atomic force microscope – or an array of NVs distributed on the diamond surface – to allow a scanning view of a cell, for example, to probe nuclear spins with a resolution down to a nanometer or perhaps better.”

Here’s a citation and a link to this team’s study,

Nuclear Magnetic Resonance Spectroscopy on a (5-Nanometer)3 Sample Volume by T. Staudacher, F. Shi, S. Pezzagna, J. Meijer, J. Du, C. A. Meriles, F. Reinhard1, J. Wrachtrup. Science 1 February 2013: Vol. 339 no. 6119 pp. 561-563 DOI: 10.1126/science.1231675

Both articles are behind paywalls.

Bacteria, pyramids, cancer, and Sylvain Martel

Canada’s national newspaper (as they like to bill themselves), the Globe and Mail featured Québec researcher’s (Sylvain Martel) work in a Dec. 13, 2011 article by Bertrand Marotte. From the news article,

Professor Sylvain Martel is already a world leader in the field of nano-robotics, but now he’s working to make a medical dream reality: To deliver toxic drug treatments directly to cancerous cells without damaging the body’s healthy tissue.

I have profiled Martel’s work before in an April 6 2010 posting about bacterial nanobots (amongst other subjects) and in a March 16, 2011 posting about his work with remote-controlled microcarriers.

It seems that his next project will combine the work on bacteria and microcarriers (from the Globe and Mail article),

Bolstered by his recent success in guiding micro-carriers loaded with cancer-fighting medications into a rabbit’s liver, he and his team of up to 20 researchers from several disciplines are working to transfer the method to the treatment of colorectal cancer in humans within four years.

This time around he is not using micro-carriers to deliver the drug to the tumour, but rather bacteria.

Here’s a video of the bacteria which illustrates Martel’s earlier success with ‘training’ them to build a pyramid.

The latest breakthrough reported in March 2011 (from my posting) implemented an MRI (magnetic resonance imaging) machine,

Known for being the world’s first researcher to have guided a magnetic sphere through a living artery, Professor Martel is announcing a spectacular new breakthrough in the field of nanomedicine. Using a magnetic resonance imaging (MRI) system, his team successfully guided microcarriers loaded with a dose of anti-cancer drug through the bloodstream of a living rabbit, right up to a targeted area in the liver, where the drug was successfully administered. This is a medical first that will help improve chemoembolization, a current treatment for liver cancer.

Here’s what Martel is trying to accomplish now (from the Globe and Mail article),

The MRI machine’s magnetic field is manipulated by [a] sophisticated software program that helps guide the magnetically sensitive bacteria to the tumour mass.

Attached to the bacteria is a capsule containing the cancer-fighting drug. The bacteria are tricked into swimming to an artificially created “magnetic north” at the centre of the tumour, where they will die off after 30 to 40 minutes. The micro-mules, however, have left their precious cargo: the capsule, whose envelope breaks and releases the drug.

I’m not entirely sure why the drug won’t destroy health tissue after it’s finished with the tumour but that detail is not offered in Marotte’s story which, in the last few paragraphs, switches focus from medical breakthroughs to the importance of venture capital funding for Canadian biotech research.

I wish Martel and his team great success.