Category: Medical Research & Technology

Categories : Medical Research & TechnologyTags :

Study Reveals Global Differences in Sleep Patterns

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Using data from a consumer sleep tracker, a new study has shown that not only do people in Asia go to sleep later and have shorter sleep, they also have lower sleep quality than those in other parts of the world. The study, published in Sleep Medicine, also showed that South Africans, Australians and New Zealanders went to bed and rose earlier than the other parts of the world included in the research, but also got the most sleep.

This finding surfaced after a team of researchers from the Centre for Sleep and Cognition at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine) in partnership with Oura Health Oy (Finland), analysed 50 million nights of anonymised sleep data, contributed by over 220 000 users of the “Oura Ring”, a consumer sleep tracker, from across 35 countries. Most of the users were working adults, aged between 30 and 55 years. To provide a comprehensive analysis of sleep measures for each user, the team gathered sleep data from multiple nights across a whole year – on average, each user contributed 242 nights of data. Weekday and weekend sleep were analysed separately to assess the impact of the working week on sleep patterns.

The results showed that people in Asia have shorter sleep, and display higher variability in both sleep timing and duration on weekdays. They also fall asleep later than those living in Europe, Oceania and North America. Previous studies have shown that shorter sleep duration is usually associated with higher sleep efficiency as people try to make the most of their sleep opportunity; however, in this study, despite sleeping less, people in Asia also had lower sleep efficiency. This may be because factors that result in short sleep (eg, work-related anxiety) also lead to lower quality sleep.

People often sleep for longer at the weekends than during the week, a phenomenon known as weekend sleep extension. While there was a clear association between shorter weekday sleep and longer weekend sleep extension, suggesting that people caught up on sleep at the weekend, even after accounting for this, people in Asia had the shortest weekend sleep extension.

While there are many socio-cultural factors that affect sleep patterns, the team hypothesises that because it plays such a fundamental role in our lives, work (and the broader work culture) is one of the most influential factors affecting how we sleep. Previous evidence from time use studies have demonstrated a strong association between long work hours and short sleep. Additionally, there is evidence that preoccupation with work demands and the inability to stop thinking about work contribute to sleep disturbances.

Dr Adrian Willoughby, Senior Research Fellow at NUS Medicine’s Centre for Sleep and Cognition, said, “In Europe, weekends are generally considered time for relaxation, and engaging in social activities with friends and family. In Asia, however, people may use the weekends to catch up on work, do the things they didn’t have time for during the week or attend to more family responsibilities. We think that longer working hours and the difference in work culture in Asia means that people don’t catch up on sleep as much at the weekends, but try to catch up whenever they have the opportunity over the course of the week.”

Prof Michael Chee, Director of the Centre for Sleep and Cognition at NUS Medicine said, “Sleep is a significant issue to address, especially for people living in Asia, who seem to sleep less than other global regions. Access to such a large dataset has allowed us to have unique insights into global sleep patterns. This research enables us to work towards our goal of giving customised sleep advice that considers individual sleep needs, environment factors and larger socio-cultural pressures that affect sleep. We want people to practise sleep routines that fit different contexts, but also promote health, well-being and performance.”

Source: National University of Singapore, Yong Loo Lin School of Medicine

Categories : Medical Research & Technology OphthalmologyTags :

A Smart Contact Lens Battery Powered by Tears

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Singapore scientists have developed a flexible battery as thin as a human cornea, which can store electricity when immersed in a saline solution such as tears. The scientists described their research in Nano Energy, and believe that this technology could one day power smart contact lenses.

Smart contact lenses are high-tech contact lenses capable of displaying visible information on the cornea and can be used to access augmented reality as well as monitoring health and their normal function of correcting vision. But they need power, and existing rechargeable batteries rely on wires or induction coils that contain metal and are unsuitable for use in the human eye, as they are uncomfortable and present risks to the user.

The battery, developed by Nanyang Technological University, is made of biocompatible materials and does not contain wires or toxic heavy metals, such as those in lithium-ion batteries or wireless charging systems. It has a glucose-based coating that reacts with the sodium and chloride ions in the saline solution surrounding it, while the water the battery contains serves as the ‘wire’ or ‘circuitry’ for electricity to be generated.

The battery could also be powered by human tears as they contain sodium and potassium ions, at a lower concentration. Testing the current battery with a simulated tear solution, the researchers showed that the battery’s life would be extended an additional hour for every twelve-hour wearing cycle it is used. The battery can also be charged conventionally by an external power supply.

Associate Professor Lee Seok Woo, from NTU’s School of Electrical and Electronic Engineering (EEE), who led the study, said: “This research began with a simple question: could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.

“However, previous techniques for lens batteries were not perfect as one side of the battery electrode was charged and the other was not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction. Besides the charging mechanism, it relies on just glucose and water to generate electricity, both of which are safe to humans and would be less harmful to the environment when disposed, compared to conventional batteries.”

The research team has filed for a patent through NTUitive, NTU’s innovation and enterprise company. They are also working towards commercialising their invention.

Cry me a current

The team demonstrated their invention using a simulated human eye. The battery, which is about 0.5 millimetres-thin generates electrical power by reacting with the basal tears – the constant tears that create a thin film over our eyeballs – for the devices embedded within the lenses to function.

The flexible and flat battery discharges electricity through a process called reduction when its glucose oxidase coating reacts with the sodium and chloride ions in the tears, generating power and current within the contact lenses.

The team demonstrated that the battery could produce a current of 45 microamperes and a maximum power of 201 microwatts, which would be sufficient to power a smart contact lens.

Laboratory tests showed that the battery could be charged and discharged up to 200 times. Typical lithium-ion batteries have a lifespan of 300 to 500 charging cycles.

The team recommends that the battery should be placed for at least eight hours in a suitable solution that contains a high quantity of glucose, sodium and potassium ions, to be charged while the user is asleep.

Source: Nanyang Technology University

Categories : Medical Research & Technology Metabolic DisordersTags :

‘We Will Rock You’: The Special Cells that Secrete Insulin to Music

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Freddie Mercury performing with Queen in 1977. Source: Wikimedia Commons

Music has often been touted as a soothing treatment to aid healing. Now, researchers at ETH Zurich in Basel have come up with another medical approach. They have developed a novel method to get music to make specially designed cells secrete insulin. They found that this works especially well with the bass rhythm “We Will Rock You,” a global hit by British rock band, Queen.

Diabetics depend on an external supply of insulin via injection or pump. Researchers led by Martin Fussenegger from the Department of Biosystems Science and Engineering at ETH Zurich in Basel want to make the lives of these people easier and are looking for solutions to produce and administer insulin directly in the body. Any alternatives must be able to release insulin in controlled quantities on command.

One such solution the scientists are pursuing is enclosing insulin-producing designer cells in capsules that can be implanted in the body. To be able to control from the outside when and how much insulin the cells release into the blood, researchers have studied and applied different triggers in recent years: light, temperature and electric fields.

Equipping cells to receive sound waves

To make the insulin-producing cells receptive to sound waves, the researchers used a protein from the bacterium E. coli. Such proteins respond to mechanical stimuli and are common in animals and bacteria. The protein is located in the membrane of the bacterium and regulates the influx of calcium ions into the cell interior. The researchers incorporated the blueprint of this bacterial ion channel into human insulin-producing cells, letting these cells create the ion channel themselves and embed it in their membrane.

As the scientists have been able to show, the channel in these cells opens in response to sound, allowing positively charged calcium ions to flow into the cell. This leads to a charge reversal in the cell membrane, which in turn causes the tiny insulin-filled vesicles inside the cell to fuse with the cell membrane and release the insulin to the outside.

Turn up the bass

In cell cultures, the researchers first determined which frequencies and volume levels activated the ion channels most strongly. They found that volume levels around 60 decibels (dB) and bass frequencies of 50 hertz were the most effective in triggering the ion channels. To trigger maximum insulin release, the sound or the music had to continue for a minimum of three seconds and pause for a maximum of five seconds. If the intervals were too far apart, substantially less insulin was released.

Finally, the researchers looked into which music genres caused the strongest insulin response at a volume of 85dB. Rock music with booming bass like the song “We Will Rock You,” from Queen, came out on top, followed by the soundtrack to the action movie The Avengers. The insulin response to classical music and guitar music was rather weak by comparison.

“We Will Rock You” triggered roughly 70% of the insulin response within five minutes, and all of it within 15 minutes. This is comparable to the natural glucose-induced insulin response of healthy individuals, Fussenegger says.

Sound source must be directly above the implant

To test the system as a whole, the researchers implanted the insulin-producing cells into mice and placed the animals so that their bellies were directly on the loudspeaker. This was the only way the researchers could observe an insulin response. If, however, the animals were able to move freely in a “mouse disco,” the music failed to trigger insulin release.

“Our designer cells release insulin only when the sound source with the right sound is played directly on the skin above the implant,” Fussenegger explains. The release of the hormone was not triggered by ambient noise such as aircraft noise, lawnmowers, fire brigade sirens or conversations.

Ambient noise won’t do

As far as he can tell from tests on cell cultures and mice, Fussenegger sees little risk that the implanted cells in humans would release insulin constantly and at the slightest noise.

Another safety buffer is that insulin depots need four hours to fully replenish after they have been depleted. So even if the cells were exposed to sound at hourly intervals, they would not be able to release a full load of insulin each time and thereby cause life-threatening hypoglycaemia. “It could, however, cover the typical needs of a diabetes patient who eats three meals a day,” Fussenegger says. He explains that insulin remains in the vesicles for a long time, even if a person doesn’t eat for more than four hours. “There’s no depletion or unintentional discharge taking place.”

As a proof of concept only, clinical application is a long way off, but it shows that genetic networks can be controlled by mechanical stimuli such as sound waves. Whether this principle will ever be put to practical use depends on whether a pharmaceutical company is interested in doing so. It could, after all, be applied broadly: the system works not only with insulin, but with any protein that lends itself to therapeutic use.

Source: ETH Zurich

Categories : Medical Research & TechnologyTags :

Clinical Researchers Beware – ChatGPT is not a Reliable Aid

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Clinicians are all too familiar with the ‘Google patient’ who finds every scary, worst-case or outright false diagnosis online on whatever is ailing them. During COVID, misinformation spread like wildfire, eroding the public’s trust in vaccines and the healthcare profession. But now, AI models like ChatGPT can be whispering misleading information to the clinical researchers trying to produce real research.

Researchers from CHU Sainte-Justine and the Montreal Children’s Hospital recently posed 20 medical questions to ChatGPT. The chatbot provided answers of limited quality, including factual errors and fabricated references, show the results of the study published in Mayo Clinic Proceedings: Digital Health.

“These results are alarming, given that trust is a pillar of scientific communication. ChatGPT users should pay particular attention to the references provided before integrating them into medical manuscripts,” says Dr Jocelyn Gravel, lead author of the study and emergency physician at CHU Sainte-Justine.

Questionable quality, fabricated references

The researchers drew their questions from existing studies and asked ChatGPT to support its answers with references. They then asked the authors of the articles from which the questions were taken to rate the software’s answers on a scale from 0 to 100%.

Out of 20 authors, 17 agreed to review the answers of ChatGPT. They judged them to be of questionable quality (median score of 60%). They also found major (five) and minor (seven) factual errors. For example, the software suggested administering an anti-inflammatory drug by injection, when it should be swallowed. ChatGPT also overestimated the global burden of mortality associated with Shigella infections by a factor of ten.

Of the references provided, 69% were fabricated, yet looked real. Most of the false citations (95%) used the names of authors who had already published articles on a related subject, or came from recognised organisations such as the Food and Drug Administration. The references all bore a title related to the subject of the question and used the names of known journals or websites. Even some of the real references contained errors (eight out of 18).

ChatGPT explains

When asked about the accuracy of the references provided, ChatGPT gave varying answers. In one case, it claimed, “References are available in Pubmed,” and provided a web link. This link referred to other publications unrelated to the question. At another point, the software replied, “I strive to provide the most accurate and up-to-date information available to me, but errors or inaccuracies can occur.”

Despite even the most ‘truthful’ of these responses, ChatGPT poses hidden risks to academic, the researcher say.

“The importance of proper referencing in science is undeniable. The quality and breadth of the references provided in authentic studies demonstrate that the researchers have performed a complete literature review and are knowledgeable about the topic. This process enables the integration of findings in the context of previous work, a fundamental aspect of medical research advancement. Failing to provide references is one thing but creating fake references would be considered fraudulent for researchers,” says Dr Esli Osmanlliu, emergency physician at the Montreal Children’s Hospital and scientist with the Child Health and Human Development Program at the Research Institute of the McGill University Health Centre.

“Researchers using ChatGPT may be misled by false information because clear, seemingly coherent and stylistically appealing references can conceal poor content quality,” adds Dr Osmanlliu.

This is the first study to assess the quality and accuracy of references provided by ChatGPT, the researchers point out.

Source: McGill University Health Centre

Categories : Environmental Effects Medical Research & Technology UncategorizedTags :

Measuring Heart Rate from Facial Colour Changes

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Scientists have for a long time tried to develop contactless heart rate monitoring, such as using cameras to measure subtle colour changes in the face from blood flow, but have been hampered by noise artefacts. Now, Japanese researchers have developed a way to pick up a clean signal by taking advantage of the pulse’s characteristic rhythm.

In the past decade or so, researchers tried to develop contactless heart rate (HR) measuring which avoids the discomfort and dermatitis risk of physical contact. An example is cameras that focus on the blood volume pulse (BVP), that causes slight temporal changes in facial skin colour captured in videos and which can be used for HR estimation. However, due to the small magnitude of these colour changes, the accuracy of HR estimation is adversely affected by facial movements, ambient lighting variations, and noise.

To address these challenges, a team of researchers from Japan have now developed a novel method that leverages the temporal characteristics of the blood pulse. Importantly, it builds on the ability of the pulse to exhibit quasi-periodic behaviour, which distinguishes it from noise artefacts. The study was led by Dr Yoshihiro Maeda, Junior Associate Professor, from the Department of Electrical Engineering at the Tokyo University of Science and is published in the journal IEEE Access.

The proposed method uses dynamic mode decomposition (DMD), a technique that analyses spatio-temporal structures in multi-dimensional time-series signals. It also employs adaptive selection of the optimal spatio-temporal structure based on medical knowledge of HR frequencies. “Our method, unlike previous applications of DMD, effectively models and extracts the BVP signal by incorporating physics-informed DMD in a time-delay coordinate system, taking into account the nonlinearity and quasi-periodicity of the BVP dynamics,” explains PhD student Kosuke Kurihara.

The proposed method relies solely on tracking time-series data from videos of a person’s face, eliminating the need for any attached detectors on the person’s body. In this method, the video time-series of the face, monitoring continuous changes, are converted into RGB time-series signals, which helps in extracting information of blood volume changes occurring beneath the skin. After effectively dealing with noise or misinformation that might creep into the data, the observed RGB signals are then converted to pulse wave information data.

Using the DMD method in a time-delayed coordinate system with conservative dynamics modeling, pulse waves containing major and accurate information can be extracted to estimate HR.

To demonstrate the efficacy of this method, the researchers used 67 facial videos from three publicly available datasets. The results of this method were then compared with other non-contact HR estimation methods. Interestingly, the proposed method adaptively selects the dynamic mode that contains the most pulse wave components, based on the knowledge of the typical range of pulse wave components. As a result, the method showed a 36.5% improvement in estimation accuracy compared to conventional methods, especially in scenes with ambient light fluctuations.

“This achievement is expected to play a significant role as a fundamental technology for vital monitoring systems in the medical and fitness fields. The breakthrough contactless method holds great potential for non-contact heart rate estimation in various applications, such as remote health monitoring and physiological assessments,” concludes Dr Maeda. Further research will be needed to explore techniques that incorporate multispectral information, which can contribute to reducing noise and improving the accuracy of the method.

Source: Tokyo University of Science

Categories : General Interest Medical Research & Technology UncategorizedTags :

US Officials Discover Illegal Biological Laboratory inside Warehouse

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Authorities in the US have shut down what seems to be an illegal biological lab in California. Hidden inside a warehouse, the lab held nearly 1000 lab mice, around 800 unidentified chemicals, refrigerators and freezers, thousands of vials of biohazardous materials such as blood, incubators, and at least 20 infectious agents, including SARS-CoV-2, HIV, and a herpes virus. The lab’s owners claim they were developing COVID testing kits.

NBC News affiliate KSEE of Fresno reported that the authorities first cottoned on to the lab when a local official noticed an illegal hosepipe connection, prompting a warrant to search the building, which was only supposed to be used for storage.

Officials first inspected the warehouse in Reedley City, Fresno County on March 3, court documents reveal. It was only on March 16 when local health officials conducted their own inspection – and they were shocked to discover the true nature of the warehouse’s contents and operations.

Reedley City Manager Nicole Zieba told KSEE, “This is an unusual situation. I’ve been in government for 25 years. I’ve never seen anything like this.”

“Certain rooms of the warehouse were found to contain several vessels of liquid and various apparatus,” court documents read. “Fresno County Public Health staff also observed blood, tissue and other bodily fluid samples and serums; and thousands of vials of unlabeled fluids and suspected biological material.”

Chemicals and equipment were also haphazardly stored with furniture. They also discovered nearly a thousand mice; more than 175 were already dead and 773 were euthanised.

The tenant was found Prestige BioTech, which was not licensed for business in California. The company president was identified as Xiuquin Yao, whom officials questioned via email. Prestige BioTech had moved assets from a now-defunct medical technology company which had owed it money.

Prestige Biotech is accused of not having the proper permits and disposal plans for the equipment and substances, and would not explain the laboratory activity at the warehouse.

“I’ve never seen this in my 26-year career with the County of Fresno,” said Assistant Director of the Fresno County Department of Public Health Joe Prado.

“Through their statements that they were doing some testing on laboratory mice that would help them support, developing the COVID test kits that they had on-site,” Prado said.

Zieba also commented that this was only part of the investigation. “Some of our federal partners still have active investigations going. I can only speak to the building side of it,” Zieba said.

Further attempts to contact Yao for comment have been unsuccessful.

Categories : Genetics Medical Research & TechnologyTags :

New CRISPR Discovery Targets Infected Cells

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CRISPR-Cas9 is a customisable tool that lets scientists cut and insert small pieces of DNA at precise areas along a DNA strand. This lets scientists study our genes in a specific, targeted way. Credit: Ernesto del Aguila III, National Human Genome Research Institute, NIH

German and US scientists have discovered a CRISPR system in cells that shuts them down entirely to protect against viral replication, instead of merely chopping out foreign DNA that it comes across. It does this by shredding any DNA or RNA it comes across, causing the cell to become senescent and not become a virus factory. The newly identified CRISPR system is described in two papers published in Nature.

“With this new system, known as Cas12a2, we’re seeing a structure and function unlike anything that’s been observed in CRISPR systems to date,” says Jackson, assistant professor in Utah State’s Department of Chemistry and Biochemistry.

CRISPR, (Clustered Regularly Interspaced Short Palindromic Repeats) has taken science by storm with its gene-editing potential. Study of CRISPR DNA sequences and CRISPR-associated (Cas) proteins, which are actually bacterial immune systems, is still a young field.

Identified as a distinct immune system within the last five years, the Class 2, type V Cas12a2 is somewhat similar to the better-known ‘molecular scissors’ of CRISPR-Cas9, which binds to target DNA and cuts it, effectively shutting off a targeted gene. But CRISPR-Cas12a2 binds a different target than Cas9, and that binding has a very different effect.

Using cryo-electron microscopy, the team captured the CRISPR-Cas12a2 in a naturally occurring defensive strategy called abortive infection, a natural resistance strategy used by bacteria and archaea to limit the spread of viruses and other pathogens by preventing replication in the cell.

The team observed Cas12a2 in the act of cutting double-stranded DNA, bending it 90° to expose the backbone of the helix to cut it, a phenomenon that a phenomenon that elicits audible gasps from fellow scientists,” Jackson says.

Since the difference between a healthy cell and a malignant cell or infected cell is genetic, if Cas12a2 could be harnessed, “the potential therapeutic applications are significant.”

“If Cas12a2 could be harnessed to identify, target and destroy cells at the genetic level, the potential therapeutic applications are significant,” he says.

Source: Utah State University

Categories : Medical Research & Technology Metabolic DisordersTags :

This Open-source Autoinjector Could Be Made for a Tenth of the Price of Commercial Ones

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Research team led by Joshua Pearce has developed a new 3-D printed, completely open-source autoinjector for a tenth of the cost of a commercially purchased product. (Photo by Anjutha Selvaraj)

A new study published in PLOS One describes the development of a spring-driven autoinjector for the delivery of insulin and other medications. This device, made from a combination of 3D-printed and commercially available parts, could cost less than $7 to make while a store-bought version is closer to $70.

Sir Frederick Banting was an inspiration for a new open source self-administering drug delivery device. Long before open source was an option or even a concept, the now-celebrated former University of Western Ontario lecturer refused to patent insulin because he wanted it to be inexpensive and widely available for the betterment of all.

A century after Banting won the Nobel Prize for his discovery, Western researchers led by engineering and Ivey Business School professor Joshua Pearce has developed a new 3D printed, completely open-source autoinjector – a device designed to deliver a single dose of medicine – for a tenth of the cost of a commercially purchased product.

“I think of this device, like so much of what we’re doing here at Western, very much as following the golden rule: do unto others as you would have them do unto you,” said Pearce. “It makes the world slightly better to have an open-source version of an autoinjector, especially for people who don’t have access or the financial means to purchase a proprietary one.”

Autoinjectors are used all over the world by health care practitioners, patients and parents (for children under 12) to inject insulin into people with diabetes. Other chronic conditions such as psoriasis, multiple sclerosis and rheumatoid arthritis can also be treated using an autoinjector. The device is also essential during emergency conditions for migraine, anaphylaxis and status epilepticus patients, as well.

Pearce, along with research assistant Anjutha Selvaraj and post-doctoral associate Apoorv Kulkarni, have created the new open-source autoinjector to make the device – considered more reliable and easier to operate than a simple syringe for self-administering medications into the body – an equitable alternative to the more expensive options.

Studies show self-administration of medications by patients improves compliance and comfort and empowers patients as they are actively involved in their personal care. It also allows patients to avoid time-consuming and costly visits to the hospital, which is a bonus for overburdened health care systems.

And, as with all open-source hardware, there is money to be made as the digitally replicable device enables low-cost distributed manufacturing. All materials, designs and assembly instructions are also detailed in the new study, and the effectiveness of the autoinjector is tested against the current standard (ISO 11608-1:2022) for needle-based injection systems. It is released with an open source hardware license. Companies wishing to commercialise the device will still need to meet their own local regulatory requirements.

“Does this design make it possible for other people to commercialise it anywhere in the world? Yes, it does,” said Pearce. “But more importantly, it means we can really target isolated communities, whether they’re in northern Canada, Africa or anywhere in else in the world, and improve health care access for everyone.”

Source: University of Western Ontario

Categories : Lab Tests and Imaging Medical Research & TechnologyTags :

Gravity-powered Biomedical Devices Pull Droplets Through a Maze

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Source: Unsplash CC0

Biomedical engineers at Duke University have developed an entirely new approach to building point-of-care diagnostic devices that only use gravity to transport, mix and otherwise manipulate the liquid droplets involved. The demonstration, in the journal Device, requires only commercially available materials and very little power to read results, making it a potentially attractive option for applications in low-resource settings.

“The elegance in this approach is all in its simplicity – you can use whatever tools you happen to have to make it work,” said Hamed Vahabi, a former postdoctoral researcher at Duke. “You could theoretically even just use a handsaw and cut the channels needed for the test into a piece of wood.”

The study was conducted in the laboratory of Ashutosh Chilkoti, the Alan L. Kaganov Distinguished Professor of Biomedical Engineering at Duke.

There is no shortage of need for simple, easy-to-use, point-of-care devices. Many demonstrations and commercial devices seek to make diagnoses or measure important biomarkers using only a few drops of liquid with as little power and expertise required as possible. Their goal is to improve health care for the billions of people living in low-resource settings far from traditional hospitals and trained clinicians.

All of these tests have the same basic requirements; they must move, mix and measure small droplets containing biological samples and the active ingredients that make measuring specific biomarkers possible. More expensive examples use tiny electrical pumps to drive these reactions. Others use the physics of liquids within microchannels (microfluidics) that create a sort of suction effect.

This is the first demonstration that only uses gravity. Each approach offers uniquely useful abilities as well as drawbacks.

“Most microfluidic devices need more than just capillary forces to operate,” Chilkoti said. “This approach is much simpler and also allows very complex fluid paths to be deigned and operated, which is not easy or cheap to do with microfluidics.”

The new gravity-driven approach relies on a set of nine commercially available surface coatings that can tweak the wettability and slipperiness at any given point on the device. That is, they can adjust how much droplets flatten down into pancakes or remain spherical while making it easier or harder for them to slide down an incline.

Used together in clever combinations, these surface coatings can create all the microfluidic elements needed in a point-of-care test. For example, if a given location is extremely slippery and a droplet is placed at an intersection where one side pulls liquid flat and the other pushes it into a ball, it will act like a pump and accelerate the droplet toward the former.

“We came up with many different elements to control the motion, interaction, timing and sequence of multiple droplets in the device,” Vahabi said. “All of these phenomena are well-known in the field, but nobody thought of using them to control the motion of droplets in a systematic way before.”

By combining these elements, the researchers created a prototype test to measure the levels of lactate dehydrogenase (LDH) in a sample of human serum. They carved channels within the test platform to create specific pathways for droplets to travel, each coated with a substance that stops the droplets from sticking along their journey. They also primed specific locations with dried reagents needed for the test, which are soaked up by droplets of simple buffer solution as they travel through.

The whole maze-like test is then capped with a lid containing a couple of holes where the sample and buffer solution are dripped in. Once loaded, the test is placed inside a box-like device with a handle that turns the test 90° to allow gravity to do its work. This device is also equipped with a simple LED and light detector that can quickly and easily detect the amount of blue, red, or green in the test results. This means that the researchers can tag three different biomarkers with different colours for various tests to measure.

In the case of this prototype LDH test, the biomarker is tagged with a blue molecule. A simple microcontroller measures how deep of a blue hue the test results become and how quickly it changes colour, which indicates the amount and concentration of LDH in the sample, to generate results.

“We could eventually also use a smart phone down the line to measure results, but that’s not something we explored in this specific paper,” said Jason Liu, a PhD candidate in the Chilkoti lab.

The demonstration provides a new approach for consideration when engineering inexpensive, low-power, point-of-care diagnostic devices. While the group plans to continue developing their idea, they also hope others will take notice and work on similar tests.

“While a well-designed microfluidic system can be fully automated and easy-to-use by passive means, the timing of discrete steps is usually programmed into the design of the device itself, making modifications to protocol more difficult,” added David Kinnamon, a PhD candidate in the Chilkoti group. “In this work, the user retains more control of the timing of steps while only modestly sacrificing ease-of-operation. Again, this is an advantage for more complex protocols.”

Source: Duke University

Categories : Medical Research & TechnologyTags :

A Natural Repair Process for Damaged Auditory Hair Cells

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Auditory researchers have discovered how hair cells can repair themselves after being damaged, an important insight could benefit efforts to develop new and better ways to treat and prevent hearing loss. Their findings are published in the free online journal eLife.

Found in the inner ear, hair cells derive their name from the hair-like structures that cover them and serve as mechanical antennas for sound detection. The prevailing belief is that when auditory hair cells are killed, they are gone for good. But this new research from University of Virginia School of Medicine shows that these delicate cells have the ability to repair themselves from damage caused by loud noises or other forms of stress.

“For many years, auditory research has placed considerable emphasis on the regeneration of sensory hair cells. Although these efforts continue, it is equally important to enhance our comprehension of the intrinsic mechanisms that govern the repair and maintenance of these cells. By gaining a deeper understanding of these inherent repair processes, we can uncover strategies to fortify them effectively. One such approach in the future might involve the utilisation of drugs that stimulate repair programs,” said researcher Jung-Bum Shin, PhD, of UVA’s Department of Neuroscience. “In essence, when replacement of hair cells proves challenging, the focus shifts towards repairing them instead. This dual strategy of regeneration and repair holds strong potential in advancing treatments for hearing loss and associated conditions.”

Repairing the damaged cells

In order to sense sound, hair cells are naturally fragile, but they also must withstand the continuous mechanical stress inherent in their jobs.

Prolonged exposure to loud noise harms hair cells in a variety of ways, and one of those is by damaging the cores of the “hairs” themselves. These hair-like structures are known as stereocilia, and Shin’s new research shows a process they use to repair themselves.

The hair cells do this by deploying a protein called XIRP2, which has the ability to sense damage to the cores, which are made of a substance called actin. Shin and his team found that XIRP2 first senses damage, then migrates to the damage site and repairs the cores by filling in new actin.

“We are especially excited to have identified a novel mechanism by which XIRP2 can sense damage-associated distortions of the actin backbone,” Shin said. “This is of relevance not only for hair cell research, but the broader cell biology discipline.”

The pioneering work has netted a grant to fund additional research into how the cores are repaired. By understanding this, scientists will be better positioned to develop new ways to battle hearing loss – even the kind that comes from aging, the researchers say.

“Age-related hearing loss affects at least a third of all older adults,” Shin said. “Understanding and harnessing internal mechanisms by which hair cells counteract wear and tear will be crucial in identifying ways to prevent age-related hearing loss. Furthermore, this knowledge holds potential implications for associated conditions such as Alzheimer’s disease and other dementia conditions.”

Source: University of Virginia Health System