December 23, 2012

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US Teen Invents Advanced Cancer Test Using Google

August 31, 2012 By 1 Comment

Originally posted on bbc.co.uk, August 20, 2012

Fifteen-year-old high school student Jack Andraka likes to kayak and watch the US television show Glee.

And when time permits, he also likes to do advanced research in one of the most respected cancer laboratories in the world.

Jack Andraka has created a pancreatic cancer test that is 168 times faster and considerably cheaper than the gold standard in the field. He has applied for a patent for his test and is now carrying out further research at Johns Hopkins University in the US city of Baltimore.

And he did it by using Google.

The Maryland native, who won $75,000 at the Intel International Science and Engineering Fair in May for his creation, cites search engines and free online science papers as the tools that allowed him to create the test.

The BBC’s Matt Danzico sat down with the teenager, who said the idea came to him when he was “chilling out in biology class”.

Source: https://www.bbc.co.uk/news/magazine-19291258

Filed Under: Biotechnology, Cancer, Chemistry, Health, Media, Positive, Science, Technology

New Wind Turbine Makes Drinking Water

August 30, 2012 By Leave a Comment

Originally posted by Neal Colgrass on Newser.com, August 26, 2012

Eole Water

A French inventor may have an answer for the millions of people who scramble to find fresh drinking water each day: a wind turbine that literally pulls H2O from the air. Marc Parent, head of Eoie Water, designed the turbine while living in the Caribbean and enduring water shortages. His solution is called the WMS1000, which gathers moisture from the air and turns it into drinking water, ABC News reports. On average, each unit creates over 62 liters per hour when the temperature is 75 Fahrenheit with 45% humidity, according to the company website.

“Let me highlight this word: CREATE,” says Eole Water executive Thibault Janin. “All existing solutions (wells, desalination, lakes/rivers pumping, etc) only treat an existing source of water.” He adds that the world’s water scarcity will affect more than the 150 million possible WMS1000 customers; household water needs are also growing, so Eole Water is seeking other solutions—especially affordable ones. Once testing is complete, each WMS1000 should cost $600,000 and last for 20 years.

Source: https://www.newser.com/story/152849/new-wind-turbine-makes-drinking-water.html

Filed Under: Environment, Featured, Health, Positive, Self-Sustainability, Water

Metatronic Chip Replaces Electricity With Light, Swaps Resistors With Silicon Nitride Nanorods

August 28, 2012 By 1 Comment

Originally posted by Sebastian Anthony on ExtremeTech.com, February 24, 2012

www.element14.com

www.element14.com

Optical engineers at the University of Pennsylvania have created the first computer circuit where logic is performed with light instead of electricity. Dubbed “metatronics,” this light-based logic could enable smaller, faster, and more energy efficient computer chips.

The team, led by Nader Engheta, demonstrated that it’s possible to make resistors, inductors, and capacitors that act on light. By creating a chip that has a comb-like array of nanorods — tiny pillars of silicon nitride (pictured below) — the flow of light can be controlled in such a way that the “voltage” and “current” of the optical signal can be altered. By changing the height and width of the nanorods, and by altering their arrangement, different effects can be achieved. For example, if light has to pass by a short rod and then a tall rod, it might create a resistor-like effect — but a square of four short rods might act as an optical capacitor. The metatronic name comes from the fact that these nanorods are a metamaterial; a material that has properties that can’t be found in nature.

Because Engheta and co are working with light instead of electricity, their metatronic chip has some very odd properties. For example, light’s polarization — whether the light wave undulates left/right or up/down — affects how it moves through the nanorods. When the light is aligned with the nanorods (pictured above), the circuit fires in parallel; but when light is perpendicular, the circuit is serial. In effect, one set of nanorods can act as two different circuits, which Engheta calls “stereo-circuitry.”

www.extremetech.com

Furthermore, if you rotate the circuit itself through 45 degrees, the light wave would hit the nanorods obliquely, creating a circuit that is neither series or parallel — a setup that doesn’t occur in regular electronics. Eventually — and be careful, this might make your brain explode — you could even build 3D arrays of nanorods, where a single arrangement could act as dozens of different circuits.

To put this into perspective, imagine a low-power, ultra-high-speed CPU that turns into a GPU when you change the input signal — that’s the kind of functionality that metatronic circuits might one day enable. In the short term, though, work needs to be done on optical interconnects– and, as yet, the closest we’ve come to creating an optical transistor is MIT’s optical diode. In the short term it is much more likely that optoelectronic chips — chips that mix electronic logic with optical interconnects, and which can be built using standard semiconductor processes — will be used commercially.

Sources:

https://www.extremetech.com/extreme/119759-metatronic-chip-replaces-electricity-with-light-swaps-resistors-with-nanorods

University of Pennsylvania

Filed Under: Physics, Positive, Science, Technology

New nanoparticles shrink tumors in mice

August 22, 2012 By Leave a Comment

Nanoparticles that shut off cancer genes could also allow researchers to screen potential drug targets more rapidly

MIT researchers have developed RNA-delivering nanoparticles that

Short strands of RNA can be used to selectively turn off cancer genes (credit: MIT)

allow for rapid screening of new drug targets in mice.

By sequencing cancer-cell genomes, scientists have discovered vast numbers of genes that are mutated, deleted or copied in cancer cells. This treasure trove is a boon for researchers seeking new drug targets, but it is nearly impossible to test them all in a timely fashion.

In their first mouse study, done with researchers at Dana-Farber Cancer Institute and the Broad Institute, they showed that nanoparticles that target a protein known as ID4 can shrink ovarian tumors.

The nanoparticle system could relieve a significant bottleneck in cancer-drug development, says Sangeeta Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science and a member of the David H. Koch Institute for Integrative Cancer Research at MIT.

“What we did was try to set forth a pipeline where you start with all of the targets that are pouring out of genomics, and you sequentially filter them through a mouse model to figure out which ones are important. By doing that, you can prioritize the ones you want to target clinically using RNA interference, or develop drugs against,” says Bhatia, one of the paper’s senior authors.

William Hahn, an associate professor of medicine at Harvard Medical School and the paper’s other senior author, is the leader of Project Achilles, a collaborative effort to identify promising new targets for cancer drugs from the flood of data coming from the National Cancer Institute’s cancer-genome-sequencing project.

Among those potential targets are many considered to be “undruggable,” meaning that the proteins don’t have any pockets where a traditional drug could bind to them. The new nanoparticles, which deliver short strands of RNA that can shut off a particular gene, may help scientists go after those undruggable proteins.

“If we could figure out how to make this work [in humans], it would open up a whole new class of targets that hadn’t been available,” says Hahn, who is also director of the Center for Cancer Genome Discovery at Dana-Farber and a senior associate member of the Broad Institute.

An abundance of targets

Through Project Achilles, Hahn and his colleagues have been testing the functions of many of the genes disrupted in ovarian cancer cells. By revealing genes critical to cancer-cell survival, this approach has narrowed the list of potential targets to several dozen.

Typically, the next step in identifying a good drug target would be to genetically engineer a strain of mice that are missing (or overexpressing) the gene in question, to see how they respond when tumors develop. However, this normally takes two to four years. A much faster way to study these genes would be simply to turn them off after a tumor appears.

RNA interference (RNAi) offers a promising way to do that. During this naturally occurring phenomenon, short strands of RNA bind to the messenger RNA (mRNA) that delivers protein-building instructions from the cell’s nucleus to the rest of the cell. Once bound, the mRNA molecules are destroyed and their corresponding proteins never get made.

Scientists have been pursuing RNAi as a cancer treatment since its discovery in the late 1990s, but have had trouble finding a way to safely and effectively target tumors with this therapy. Of particular difficulty was finding a way to get RNA to penetrate tumors.

Bhatia’s lab, which has been working on RNAi delivery for several years, joined forces with Hahn’s group to identify and test new drug targets. Their goal was to create a “mix and dose” technique that would allow researchers to mix up RNA-delivery particles that target a particular gene, inject them into mice and see what happens.

Shrinking tumors

In their first effort, the researchers decided to focus on the ID4 protein because it is overexpressed in about a third of high-grade ovarian tumors (the most aggressive kind), but not in other cancer types. The gene, which codes for a transcription factor, appears to be involved in embryonic development: It gets shut down early in life, then somehow reactivates in ovarian tumors.

To target ID4, Bhatia and her students designed a new type of RNA-delivering nanoparticle. Their particles can both target and penetrate tumors, something that had never before been achieved with RNA interference.

On their surface, the particles are tagged with a short protein fragment that allows them to enter tumor cells. Those fragments are also drawn to a protein found on tumor cells, known as p32. This fragment and many similar ones were discovered by Erkki Ruoslahti, a professor at the Sanford-Burnham Medical Research Institute at the University of California at Santa Barbara, who is also an author of the new paper.

Within the nanoparticles, strands of RNA are mixed with a protein that further helps them along their journey: When the particles enter a cell, they are encapsulated in membranes known as endosomes. The protein-RNA mixture can cross the endosomal membrane, allowing the particles to get into the cell’s main compartment and start breaking down mRNA.

In a study of mice with ovarian tumors, the researchers found that treatment with the RNAi nanoparticles eliminated most of the tumors.

Gordon Mills, chair of the systems biology department at the University of Texas’ MD Anderson Cancer Center, says the work is an important step toward generating new targets for drugs to treat ovarian cancer, which is the fifth-leading cause of cancer deaths among women in the United States.

“This approach has the potential to [validate] targets that are deemed ‘undruggable’ using current technologies and to provide sufficient throughput to screen candidates arising from high-throughput sequencing, shRNA and siRNA screens and other screens for novel potential targets,” says Mills, who was not part of the research team.

The researchers are now using the particles to test other potential targets for ovarian cancer as well as other types of cancer, including pancreatic cancer. They are also looking into the possibility of developing the ID4-targeting particles as a treatment for ovarian cancer.

The research was funded by the Howard Hughes Medical Institute, the National Cancer Institute, the National Institutes of Health, the Mary Kay Foundation, the Sandy Rollman Ovarian Cancer Foundation, the Canadian Institutes of Health Research and the H.L. Snyder Medical Foundation.

Filed Under: Biotechnology, Cancer, Drugs, Genetics, Health, Nanoparticles, Positive, Vaccines and Medicine

200 page book converted into DNA by researchers

August 22, 2012 By 1 Comment

Originally posted by Jed E. Robinson on RoundNews.com on August 17, 2012

Scientists from Harvard University wanted to prove that DNA, the genetic template substance, can be a viable storage solution. They took a 200+ page book that totalled close to 53000 words.

The book also had 11 images and a short javascript code added to its contents.

The scope of Harvard’s research was to see if DNA molecules ca be used to store a large amount of data. DNA can last for thousands of years as opposed to the average harddrive lifespan which is close to 5 years of active use. If DNA is trapped in amber then it can last for million of years.

In order to convert the digital version of the book to DNA the following process was followed:

- Researchers first took the binary code of the book.

- The resulting binary string was analysed bit by bit. A nucleobase was assigned for every bit value.

- The 5.27 million base long DNA strand was synthesized by analysing 96 bases at a time

- The synthesized DNA now contains the entire book. Its weight is one million time less than the weight of a grain of salt.

After the book was converted to DNA, Harvard scientists went ahead and tried to read the content in order to determine how reliable is DNA as a storing medium. Only 10 bits out of the total of 5.27 million were erronated. Current technology offers an easy way to read DNA. There are many commercially available solutions on the market.

DNA is our basis of life. Using it for storing data in the close future is not that far fetched.

Source: https://www.roundnews.com/science/beyond-science/449-200-page-book-converted-into-dna-by-researchers.html

Filed Under: Genetics, Media, Positive, Science, Technology

Major advance in generating electricity from wastewater

August 21, 2012 By 2 Comments

Improved microbial fuel cell (credit: Oregon State University)

Engineers at Oregon State University have made a breakthrough in the performance of microbial fuel cells that can produce electricity directly from wastewater, opening the door to a future in which waste treatment plants not only will power themselves, but will sell excess electricity.

The new technology developed at OSU uses new concepts — reduced anode-cathode spacing, evolved microbes and new separator materials — and can produce more than two kilowatts per cubic meter of liquid reactor volume — 10 to 50 more times the electrical per unit volume than most other approaches using microbial fuel cells, and 100 times more electricity than some.

This technology cleans sewage by a very different approach than the aerobic bacteria used in the past. Bacteria oxidize the organic matter and, in the process, produce electrons that run from the anode to the cathode within the fuel cell, creating an electrical current.

Almost any type of organic waste material can be used to produce electricity — not only wastewater, but also grass straw, animal waste, and byproducts from such operations as the wine, beer or dairy industries.

The researchers say this could eventually change the way that wastewater is treated all over the world, replacing the widely used “activated sludge” process that has been in use for almost a century. The new approach would produce significant amounts of electricity while effectively cleaning the wastewater, they suggest.

“If this technology works on a commercial scale the way we believe it will, the treatment of wastewater could be a huge energy producer, not a huge energy cost,” said Hong Liu, an associate professor in the OSU Department of Biological and Ecological Engineering. “This could have an impact around the world, save a great deal of money, provide better water treatment and promote energy sustainability.”

Experts estimate that about 3 percent of the electrical energy consumed in the United States and other developed countries is used to treat wastewater, and a majority of that electricity is produced by fossil fuels.

The system also works better than an alternative approach to creating electricity from wastewater that is based on anaerobic digestion that produces methane. It treats the wastewater more effectively, and doesn’t have any of the environmental drawbacks of that technology, such as production of unwanted hydrogen sulfide or possible release of methane, a potent greenhouse gas, the researchers believe.

The OSU system has now been proven at a substantial scale in the laboratory, Liu said, and the next step would be a pilot study. A good candidate, she said, might initially be a food processing plant, which is a contained system that produces a steady supply of certain types of wastewater that would provide significant amounts of electricity.

Once advances are made to reduce high initial costs, researchers estimate that the capital construction costs of this new technology should be comparable to that of the activated sludge systems now in widespread use today — and even less expensive when future sales of excess electricity are factored in.

The approach may also have special value in developing nations, where access to electricity is limited and sewage treatment at remote sites is difficult or impossible as a result.

The ability of microbes to produce electricity has been known for decades, but only recently have technological advances made their production of electricity high enough to be of commercial use. OSU researchers reported several years ago on the promise of this technology, but at that time the systems in use produced far less electrical power. Continued research should also find even more optimal use of necessary microbes, reduced material costs and improved function of the technology at commercial scales, OSU scientists said.

Filed Under: Chemistry, Environment, Featured, Green Energy, Pollution, Positive, Self-Sustainability

New storage nanoparticle could make hydrogen a practical fuel

August 20, 2012 By Leave a Comment

University of New South Wales researchers have demonstrated that hydrogen can be released and reabsorbed from sodium borohydride, a promising storage material, overcoming a major hurdle to i

A diagram of the nanoparticle, with sodium borohydride encased in nickel, and a TEM image of the particles (credit: University of New South Wales)

ts use as an alternative fuel source.

Considered a major a fuel of the future, hydrogen could be used to power buildings, portable electronics and vehicles — but this application hinges on practical storage technology.

The researchers synthesized nanoparticles of sodium borohydride and encased these inside nickel shells.

Their unique “core-shell” nanostructure demonstrated remarkable hydrogen storage properties, including the release of energy at much lower temperatures than previously observed.

“No one has ever tried to synthesize these particles at the nanoscale because they thought it was too difficult, and couldn’t be done. We’re the first to do so, and demonstrate that energy in the form of hydrogen can be stored with sodium borohydride at practical temperatures and pressures,” says Dr Kondo-Francois Aguey-Zinsou from the School of Chemical Engineering at UNSW.

Lightweight compounds known as borohydrides (including lithium and sodium compounds) are known to be effective storage materials, but it was believed that once the energy was released it could not be reabsorbed — a critical limitation. This perceived “irreversibility” means there has been little focus on sodium borohydride.

“By controlling the size and architecture of these structures we can tune their properties and make them reversible — this means they can release and reabsorb hydrogen,” says Aguey-Zinsou. “We now have a way to tap into all these borohydride materials, which are particularly exciting for application on vehicles because of their high hydrogen storage capacity.”

In its bulk form, sodium borohydride requires temperatures above 550 degrees Celsius just to release hydrogen. However, with the core-shell nanostructure, the researchers saw initial energy release happening at just 50 °C, and significant release at 350 °C.

“The new materials that could be generated by this exciting strategy could provide practical solutions to meet many of the energy targets set by the U.S. Department of Energy,” says Aguey-Zinsou.

Filed Under: Featured, Green Energy, Nanorobots, Pollution, Positive, Science

Transforming cancer treatment

July 16, 2012 By 2 Comments

A Harvard researcher studying the evolution of drug resistance in cancer says that, in a few decades, “many, many cancers could be manageable

Predicted probability distribution of times from when treatment starts until resistance mutations become observable in circulating DNA (credit: Luis A. Diaz Jr/Nature)

“Many people are dying needlessly of cancer, and this research may offer a new strategy in that battle,” saidMartin Nowak, a professor of mathematics and of biology and director of the Program for Evolutionary Dynamics.

“One hundred years ago, many people died of bacterial infections. Now, we have treatment for such infections — those people don’t have to die. I believe we are approaching a similar point with cancer.”

Nowak is one of several co-authors of a paper, published in Nature on June 28, that details how resistance to targeted drug therapy emerges in colorectal cancers and describes a multidrug approach to treatment that could make many cancers manageable, if not curable.

The key, Nowak’s research suggests, is to change the way clinicians battle the disease.

Physicians and researchers in recent years have increasingly turned to “targeted therapies” — drugs that combat cancer by interrupting its ability to grow and spread — rather than traditional chemotherapy, but such treatment is far from perfect. Most targeted therapies are effective for only a few months before the cancer evolves resistance to the drugs.

The culprit in the colon cancer treatment examined in the Nature paper is the KRAS gene, which is responsible for producing a protein to regulate cell division. When activated, the gene helps cancer cells develop resistance to targeted-therapy drugs, effectively making the treatment useless.

To better understand what role the KRAS gene plays in drug resistance, a team of researchers led by Bert Vogelstein, the Clayton Professor of Oncology and Pathology at the Johns Hopkins Kimmel Cancer Center, launched a study that began by testing patients to determine if the KRAS gene was activated in their tumors. Patients without an activated KRAS gene underwent a normal round of targeted therapy treatment, and the initial results — as expected — were successful. Tests performed after the treatment broke down, however, showed a surprising result: The KRAS gene had been activated.

As part of the research, Vogelstein’s team analyzed a handful of mutations that can lead to the activation of the KRAS gene. To help interpret those results, they turned to Nowak’s team, including mathematicians Benjamin Allen, a postdoctoral fellow in mathematical biology, and Ivana Bozic, a postdoctoral fellow in mathematics.

Analyzing the clinical results, Allen and Bozic were able to mathematically describe the exponential growth of the cancer and determine whether the mutation that led to drug resistance was pre-existing, or whether it occurred after treatment began. Their model was able to predict, with surprising accuracy, the window of time from when the drug is first administered to when resistance arises and the drug begins to fail.

“By looking at their results mathematically, we were able to determine conclusively that the resistance was already there, so the therapy was doomed from the start,” Allen said. “That had been an unresolved question before this study. Clinicians were finding that these kinds of therapies typically don’t work for longer than six months, and our finding provides an explanation for why that failure occurs.”

Put simply, Nowak said, the findings suggest that, of the billions of cancer cells that exist in a patient, only a tiny percentage — about one in a million — are resistant to drugs used in targeted therapy. When treatment starts, the nonresistant cells are wiped out. The few resistant cells, however, quickly repopulate the cancer, causing the treatment to fail.

“Whether you have resistance prior to the start of treatment was one of the large, outstanding questions associated with this type of treatment,” Bozic said. “Our study offers a quantitative understanding of how resistance evolves, and shows that, because resistance is there at the start, the single-drug therapy won’t work.”

The answer, Nowak said, is simple: Rather than the one drug used in targeted therapy, treatments must involve at least two drugs.

Nowak isn’t new to such strategies. In 1995 he participated in a study, also published in Nature, that focused on the rapid evolution of drug resistance in HIV. The result of that study, he said, was the development of the drug “cocktail” many HIV-positive patients use to help manage the disease.

Such a plan, however, isn’t without challenges.

The treatment must be tailored to the patient, and must be based on the genetic makeup of the patient’s cancer. Perhaps even more importantly, Nowak said, the two drugs used simultaneously must not overlap: If a single mutation allows the cancer to become resistant to both drugs, the treatment will fail just as the single-drug therapy does.

Nowak estimated that hundreds of drugs might be needed to address all the possible treatment variations. The challenge in the near term, he said, is to develop those drugs.

“This will be the main avenue for research into cancer treatment, I think, for the next decade and beyond,” Nowak said. “As more and more drugs are developed for targeted therapy, I think we will see a revolution in the treatment of cancer.”

Sources:

https://www.kurzweilai.net/transforming-cancer-treatment

The molecular evolution of acquired resistance to targeted EGFR blockade in colorectal cancers, Nature, 2012, DOI: 10.1038/nature11219

Filed Under: Cancer, Drugs, Genetics, Positive, Science, Vaccines and Medicine

Photoreceptor transplant restores vision in mice

July 15, 2012 By 2 Comments

Scientists from the UCL Institute of Ophthalmology have shown for the first time that transplanting light-sensitive photoreceptors into the eyes of visually impaired mice can restore their vision.

Transplanted photoreceptor cells (green) can integrate and make functional connections in the adult mouse retina (credit: UCL/Robin Ali)

The research suggests that transplanting photoreceptors — light-sensitive nerve cells that line the back of the eye — could form the basis of a new treatment to restore sight in people with degenerative eye diseases.

Scientists injected cells from young healthy mice directly into the retinas of adult mice that lacked functional rod-photoreceptors. Loss of photoreceptors is the cause of blindness in many human eye diseases including age-related macular degeneration, retinitis pigmentosa, and diabetes-related blindness.

There are two types of photoreceptor in the eye: rods and cones. The cells transplanted were immature (or progenitor) rod-photoreceptor cells. Rod cells are especially important for seeing in the dark as they are extremely sensitive to even low levels of light.

Almost-normal rod vision achieved

After four to six weeks, the transplanted cells appeared to be functioning almost as well as normal rod-photoreceptor cells and had formed the connections needed to transmit visual information to the brain.

The researchers also tested the vision of the treated mice in a dimly lit maze. Those mice with newly transplanted rod cells were able to use a visual cue to quickly find a hidden platform in the maze whereas untreated mice were able to find the hidden platform only by chance after extensive exploration of the maze.

Professor Robin Ali at UCL Institute of Ophthalmology, who led the research, said: “We’ve shown for the first time that transplanted photoreceptor cells can integrate successfully with the existing retinal circuitry and truly improve vision. We’re hopeful that we will soon be able to replicate this success with photoreceptors derived from embryonic stem cells and eventually to develop human trials.

“Although there are many more steps before this approach will be available to patients, it could lead to treatments for thousands of people who have lost their sight through degenerative eye disorders. The findings also pave the way for techniques to repair the central nervous system as they demonstrate the brain’s amazing ability to connect with newly transplanted neurons.”

Cone vision next

Dr Rachael Pearson from UCL Institute of Ophthalmology and principal author, said: “We are now finding ways to improve the efficiency of cone photoreceptor transplantation and to increase the effectiveness of transplantation in very degenerate retina. We will probably need to do both in order to develop effective treatments for patients.”

The researchers demonstrated previously, in another study published in Nature, that it is possible to transplant photoreceptor cells into an adult mouse retina, provided the cells from the donor mouse are at a specific stage of development — when the retina is almost, but not fully, formed. In this study they optimized the rod transplantation procedure to increase the number of cells integrated into the recipient mice and so were able to restore vision.

Ref.: R. A. Pearson, et al., Restoration of vision after transplantation of photoreceptors, Nature, 2012, DOI:10.1038/nature10997

Related links: https://exposingthetruth.info/new-type-of-retinal-prosthesis-could-restore-sight-to-blind/

Filed Under: Biotechnology, Health, Neuroscience, Positive, Science

New type of retinal prosthesis could restore sight to blind

July 15, 2012 By Leave a Comment

Using tiny solar-panel-like cells surgically placed underneath the retina, scientists at the Stanford University School of Medicine have devised a system that may someday restore sight to people who have lost vision

A photovoltaic retinal prosthesis — a flexible sheet of silicon pixels that convert light into electrical signals that can be picked up by neurons in the eye. A scanning-electron micrograph shows the implant in a pig’s eye. (Credit: Nature Photonics/Stanford)

because of certain types of degenerative eye diseases.

This device — a new type of retinal prosthesis — involves a specially designed pair of goggles, which are equipped with a miniature camera and a pocket PC designed to process the visual data stream. The resulting images would be displayed on a liquid crystal microdisplay embedded in the goggles, similar to what’s used in video goggles for gaming, corresponding to approximately 30 degrees of visual field .

Unlike the regular video goggles, though, the images would be beamed from the LCD using laser pulses of near-infrared light to a photovoltaic array on a silicon chip — one-third as thin as a strand of hair — implanted beneath the retina. It would have 25 micron (millionths of a meter, about 1/1000th of an inch) pixels, each containing a ~10 micron stimulating electrode.

Electric currents from the photodiodes on the chip would then trigger signals in the retina, which then flow to the brain, enabling a patient to regain vision.

The retinal chip is approximately 3 mm in diameter, corresponding to 10 degrees of visual field. The 30 degree visual field is accessible by eye scanning.

A portable computer processes video images captured by a head-mounted camera. Video goggles then project these images onto the retina using pulsed infrared (880–915 nm) illumination. Electric currents from the photodiodes on the chip then trigger signals in the retina that then flow to the brain, enabling a patient to regain vision. (Credit: K. Mathieson et al./Keith Mathieson et al./Nature Photonics)

Scientists tested the photovoltaic stimulation using the prosthetic device’s diode arrays in rat retinas in vitro and how they elicited electric responses, which are widely accepted indicators of visual activity, from retinal cells . The scientists are now testing the system in live rats, taking both physiological and behavioral measurements, and are hoping to find a sponsor to support tests in humans.

There are several other retinal prostheses being developed, and at least two of them are in clinical trials. A device made by the Los Angeles-based company Second Sight was approved in April for use in Europe, and another prosthesis-maker, a German company called Retina Implant AG, announced earlier this month results from its clinical testing in Europe.

Unlike these other devices — which require coils, cables or antennas inside the eye to deliver power and information to the retinal implant — the Stanford device uses near-infrared light to transmit images, thereby avoiding any need for wires and cables, and making the device thin and easily implantable.

“The current implants are very bulky, and the surgery to place the intraocular wiring for receiving, processing and power is difficult,” said Daniel Palanker, PhD, associate professor of ophthalmology. The device developed by his team, he noted, has virtually all of the hardware incorporated externally into the goggles. “The surgeon needs only to create a small pocket beneath the retina and then slip the photovoltaic cells inside it.” What’s more, one can tile these photovoltaic cells in larger numbers inside the eye to provide a wider field of view than the other systems can offer, he added.

The current design allows for 178 pixels per square millimeter. By comparison, the first retinal prosthesis to go to market, made by Second Sight of Sylmar, California, has 60 pixels in total and requires bulkier hardware.

However, thousands of pixels are likely to be required for functional restoration of sight, such as reading and face recognition, Palanker said on his Stanford page.

Conceptual diagram of the photovoltaic pixels with pillar electrodes (1) penetrating into the inner nuclear layer. The return electrodes (2) are located in the plane of the photodiodes. (Credit: Daniel Palanker)

Stanford University holds patents on two technologies used in the system, and Palanker and colleagues would receive royalties from the licensing of these patents.

Clinical trials are expected in a few years.

A prosthesis for retinal degenerative diseases

The proposed prosthesis is intended to help people suffering from retinal degenerative diseases, such as age-related macular degeneration and retinitis pigmentosa. The former is the foremost cause of vision loss in North America, and the latter causes an estimated 1.5 million people worldwide to lose sight, according to the nonprofit group Foundation Fighting Blindness.

In these diseases, the retina’s photoreceptor cells slowly degenerate, ultimately leading to blindness. But the inner retinal neurons that normally transmit signals from the photoreceptors to the brain are largely unscathed. Retinal prostheses are based on the idea that there are other ways to stimulate those neurons.

The Stanford device uses near-infrared light, which has longer wavelength than normal visible light. It’s necessary to use such an approach because people blinded by retinal degenerative diseases still have photoreceptor cells, which continue to be sensitive to visible light. “To make this work, we have to deliver a lot more light than normal vision would require,” said Palanker. “And if we used visible light, it would be painfully bright.” Near-infrared light isn’t visible to the naked eye, though it is “visible” to the diodes that are implanted as part of this prosthetic system, he said.

For this study, Palanker and his team fabricated a chip about the size of a pencil point that contains hundreds of these light-sensitive diodes. To test how these chips responded, the researchers used retinas from both normal rats and blind rats that serve as models of retinal degenerative disease. The scientists placed an array of photodiodes beneath the retinas and placed a multi-electrode array above the layer of ganglion cells to gauge their activity. The scientists then sent pulses of light, both visible and near-infrared, to produce electric current in the photodiodes and measured the response in the outer layer of the retinas.

In the normal rats, the ganglions were stimulated, as expected, by the normal visible light, but they also presented a similar response to the near-infrared light: That’s confirmation that the diodes were triggering neural activity.

In the degenerative rat retinas, the normal light elicited little response, but the near-infrared light prompted strong spikes in activity roughly similar to what occurred in the normal rat retinas. “They didn’t respond to normal light, but they did to infrared,” said Palanker. “This way the sight is restored with our system.” He noted that the degenerated rat retinas required greater amounts of near-infrared light to achieve the same level of activity as the normal rat retinas.

While there was concern that exposure to such doses of near-infrared light could cause the tissue to heat up, the study found that the irradiation was still one-hundredth of the established ocular safety limit.

Since completing the study, Palanker and his colleagues have implanted the photodiodes in rats’ eyes and been observing and measuring their effect for the last six months. He said preliminary data indicates that the visual signals are reaching the brain in normal and in blind rats, though the study is still under way.

While this and other devices could help people to regain some sight, the current technologies do not allow people to see color, and the resulting vision is far from normal, Palanker said.

Ref.: Keith Mathieson et al., Photovoltaic retinal prosthesis with high pixel density, Nature Photonics, 2012, DOI:10.1038/nphoton.2012.104

Related: https://exposingthetruth.info/photoreceptor-transplant-restores-vision-in-mice/

Filed Under: Health, Neuroscience, Positive, Science
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