Breakthrough in creating invisibility cloaks, stealth technology

Controlling and bending light around an object so it appears invisible to the naked eye is the theory behind fictional invisibility cloaks.It may seem easy in Hollywood movies, but is hard to create in real life because no material in nature has the properties necessary to bend light in such a way. Scientists have managed to create artificial nanostructures that can do the job, called metamaterials. But the challenge has been making enough of the material to turn science fiction into a practical reality.The work of Debashis Chanda at the University of Central Florida, however, may have just cracked that barrier. The cover story in the March edition of the journal Advanced Optical Materials, explains how Chanda and fellow optical and nanotech experts were able to develop a larger swath of multilayer 3-D metamaterial operating in the visible spectral range. They accomplished this feat by using nanotransfer printing, which can potentially be engineered to modify surrounding refractive index needed for controlling propagation of light.”Such large-area fabrication of metamaterials following a simple printing technique will enable realization of novel devices based on engineered optical responses at the nanoscale,” said Chanda, an assistant professor at UCF.The nanotransfer printing technique creates metal/dielectric composite films, which are stacked together in a 3-D architecture with nanoscale patterns for operation in the visible spectral range. Control of electromagnetic resonances over the 3-D space by structural manipulation allows precise control over propagation of light. Following this technique, larger pieces of this special material can be created, which were previously limited to micron-scale size.By improving the technique, the team hopes to be able to create larger pieces of the material with engineered optical properties, which would make it practical to produce for real-life device applications. For example, the team could develop large-area metamaterial absorbers, which would enable fighter jets to remain invisible from detection systems.Story Source:The above story is based on materials provided by University of Central Florida. Note: Materials may be edited for content and length.

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Gulf war illness not in veterans’ heads but in their mitochondria

Researchers at the UC San Diego School of Medicine have demonstrated for the first time that veterans of the 1990-91 Persian Gulf War who suffer from “Gulf War illness” have impaired function of mitochondria — the energy powerhouses of cells.The findings, published in the March 27, 2014 issue of PLOS ONE, could help lead to new treatments benefitting affected individuals — and to new ways of protecting servicepersons (and civilians) from similar problems in the future, said principal investigator Beatrice A. Golomb MD, PhD, professor of medicine.Golomb, with associate Hayley Koslik and Gavin Hamilton, PhD, a research scientist and magnetic resonance physicist, used the imaging technology to compare Gulf War veterans with diagnosed Gulf War illness to healthy controls. Cases were matched by age, sex and ethnicity.The technique used — 31-phosphorus magnetic resonance spectroscopy or 31P-MRS — reveals amounts of phosphorus-containing compounds in cells. Such compounds are important for cell energy production, in particular phosphocreatine or PCr, which declines in muscle cells during exercise. PCr recovery takes longer when mitochondrial function is impaired, and delayed recovery is recognized as a robust marker of mitochondrial dysfunction.Affected Gulf War veterans displayed significantly delayed PCr recovery after an exercise challenge. In fact, said Golomb, there was almost no overlap in the recovery times of Gulf War illness veterans compared to controls: All but one control participant had a recovery time-constant clustered under 31 seconds. In contrast, all but one Gulf Illness veteran had a recovery time-constant exceeding 35 seconds, with times ranging as high as 70 seconds.There were 14 participants in the study: seven Gulf War illness cases and seven matching controls. Golomb notes that the use of 1:1 matching markedly improves statistical “power,” allowing a smaller sample size. The separation between the two groups was “visibly striking, and the large average difference was statistically significant,” she said.Golomb noted that impaired mitochondrial function accounts for numerous features of Gulf War illness, including symptoms that have been viewed as perplexing or paradoxical.”The classic presentation for mitochondrial illness involves multiple symptoms spanning many domains, similar to what we see in Gulf War illness. These classically include fatigue, cognitive and other brain-related challenges, muscle problems and exercise intolerance, with neurological and gastrointestinal problems also common.”There are other similarities between patients with mitochondrial dysfunction and those suffering from Gulf War illness: Additional symptoms appear in smaller subsets of patients; varying patterns of symptoms and severity among individuals; different latency periods across symptoms, or times when symptoms first appear; routine blood tests that appear normal.”Some have sought to ascribe Gulf War illness to stress,” said Golomb, “but stress has proven not to be an independent predictor of the condition. …

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Detecting tumor markers easily

Blood is just teeming with proteins. It’s not easy there to identify specialized tumor markers indicating the presence of cancer. A new method now enables diagnostics to be carried out in a single step. Scientists will present the analysis equipment at analytica, the international trade fair in Munich April 1-4.Benign growth, or cancer?Tumor markers in the blood help determine whether the patient is afflicted with a malign tumor and whether it is excreting markers more vigorously — involving highly specific proteins. An increased concentration in the blood provides one indication of the disease for physicians. However, it has been quite expensive in time and effort to detect the markers thus far. This is because all kinds of molecules and proteins are teeming in the blood. To be able to detect a single specific one, doctors must first separate and purify the blood in several steps, and then isolate the marker they are searching for from the rest of the molecules.This will go faster in future. Researchers in the Project Group for Automation in Medicine and Biotechnology PAMB of the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Mannheim, Germany, have developed a one-step analysis. “Our goal is to detect biological molecules in blood, or in other kinds of samples from the patient such as urine, that indicate diseases,” explains Caroline Siegert, a scientist at IPA, “and do so without having to laboriously process the blood, but in one single step instead.”Lower noise, higher signalThe difficulty in detecting specific molecules in the blood or urine lies in the enormous number of substances that are mixed in the liquid. …

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Proteins that control energy use necessary to form stem cells

Two proteins that control how cells break down glucose play a key role in forming human stem cells, University of Washington researchers have found. The finding has implications for future work in both regenerative medicine and cancer therapy.A report on this research appears online March 20 in the CELL journal Stem Cell. The paper’s lead authors are Julie Mathieu, a postdoctoral fellow at the UW, and Wenyu Zhou, a former graduate student at UW and now a postdoctoral scholar at Stanford University. Hannele Ruohola-Baker, UW professor of biochemistry, is the paper’s senior author.The researchers changed mature human cells to an earlier stem cell-like state by inserting genes for four proteins. This technique is called reprogramming.These reprogrammed cells have the extraordinary ability to develop into any type of cell in the human body, a capacity called pluripotency. It is hoped that pluripotent stem cells, created from a person’s mature cells, will one day be used to form new tissues and organs to repair and replace those damaged by injury and disease.During reprogramming, the cells change gears. They shut down the metabolic pathway for generating energy from glucose. This pathway requires the presence of oxygen in mitochondria, the cell’s powerhouses. The cells then shift over to the glycolytic pathway that generates less energy but does not require the presence of oxygen.This shift may take place because, in nature, embryonic and tissue stem cells often must survive in low-oxygen conditions.This transition to a glycolytic state is of particular interest to cancer researchers as well. In many ways, cancer cells resemble stem cells. …

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Watching the heartbeat of molecules

Oct. 17, 2013 — A team of scientists around Prof. Theodor W. Hänsch and Dr. Nathalie Picqué at the Laser Spectroscopy Division of the Max Planck Institute of Quantum Optics (Garching), in a collaboration with the Ludwig-Maximilians-Universität Munich and the Institut des Sciences Moléculaires d’Orsay (France) now report on a new method of rapidly identifying different molecular species under a microscope. Their technique of coherent Raman spectro-imaging with two laser frequency combs takes a big step towards the holy grail of real-time label-free biomolecular imaging, as published recently in Nature.How does a drug influence a living cell? In which way can signal molecules change the cell metabolism? Such questions are difficult to answer, since cells are highly complex “chemical factories” which constantly manufacture and break down a large number of different molecular species. Biologists have learnt to attach fluorescent dye labels to certain proteins so that they can distinguish them under a microscope. However, such labels can alter the cell functions. …

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Promising new angle for drugs to prevent stroke and heart attack

Aug. 30, 2013 — Platelets, which allow blood to clot, are at the heart of numerous cardiovascular problems, including heart attacks and stroke. New research has uncovered a key platelet protein that could offer a new angle for developing drugs to prevent thrombosis, or dangerous blood clots, in patients who are at high risk such as those with atherosclerosis or a history of heart problems.”I think we’re at the start of an exciting journey of drug discovery for a new class of antithrombotic therapies,” said lead study author Stephen Holly, PhD, assistant professor of biochemistry and biophysics at the University of North Carolina School of Medicine. This work was performed in collaboration with senior authors Leslie Parise, PhD, at UNC and Benjamin Cravatt, PhD, at The Scripps Research Institute.The study was published online August 29 ahead of print in the journal Chemistry & Biology and funded by grants from the American Heart Association and the National Institutes of Health.In the human circulatory system, platelets are something of a double-edged sword. Without their clotting abilities, even a minor injury could result in potentially fatal bleeding. But during a heart attack or stroke, platelets form a clot that can potentially block blood flow through our veins and arteries, a dangerous condition called thrombosis, which can deprive tissues of oxygen and lead to death.Several antithrombotic drugs are available, but some have been found to cause bleeding — a side effect that is particularly troublesome when these drugs are used to prevent thrombosis in people undergoing heart surgery. “There’s still room for improvement, in terms of making an ideal drug that can block platelet function without initiating bleeding,” said Dr. Holly.Dr. Holly and his colleagues uncovered several potential drug targets using a screening technique that has never before been applied to the cardiovascular system. The technique, called activity-based protein profiling, has been used in cancer research and allows researchers to track the actual activities of proteins operating within a cell. …

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New technique to help brain cancer patients

Aug. 23, 2013 — A new scanning technique developed by Danish and US researchers reveals how susceptible patients with aggressive brain cancer are to the drugs they receive. The research behind the ground-breaking technique has just been published in Nature Medicine.Each year sees 260 new cases of the most aggressive type of brain cancer in Denmark. Some patients survive only a few months, while others survive for 18 months. Only very few, 3.5%, are alive five years after their diagnosis. A new scanning technique can now reveal how the brain tumour responds to the drug administered:”We have developed an MRI technique which reveals how a patient will respond to the treatment that inhibits the growth of new blood vessels to the tumour. The technique allows us to only select the patients who will actually benefit from the treatment and to quickly initiate or intensify other treatments for non-responding patients,” says Kim Mouridsen, Associate Professor at Aarhus University and head of the research group Neuroimaging Methods at MINDLab, Aarhus University.He has developed the new technique together with researchers from Harvard Medical School.Brain architecture providing important knowledgeAggressive brain cancer is usually treated with drugs that inhibit the growth of new blood vessels, as the most aggressive brain tumours are constantly trying to produce new blood vessels to get oxygen. The treatment alleviates the symptoms, but it also increases the efficacy of radiation therapy because it improves oxygenation.According to Kim Mouridsen, the new technique — Vessel Architectural Imaging — is an important step towards better treatment:”Getting more knowledge about what the blood vessels in the tumour look like will also give us a better understanding of the mechanisms which are decisive for the efficacy of the treatment. And understanding these mechanisms is precisely what we need to be able to develop and improve the treatment of brain tumours in general.”

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Gold ‘nanoprobes’ hold the key to treating killer diseases

Aug. 7, 2013 — Researchers at the University of Southampton, in collaboration with colleagues at the University of Cambridge, have developed a technique to help treat fatal diseases more effectively. Dr Sumeet Mahajan and his group at the Institute for Life Sciences at Southampton are using gold nanoprobes to identify different types of cells, so that they can use the right ones in stem cell therapies.Stem cell therapy is in its infancy, but has the potential to change the way we treat cancer and other life-threatening diseases, by replacing damaged or diseased cells with healthy ones. One of the key limitations of stem cell therapy is identifying the right cells to use for different therapies. This fundamental problem with the treatment is being tackled by this new research.Dr Mahajan, Senior Chemistry Lecturer in Life Science Interface, says: “Stem cells could hold the key to tackling many diseases. They develop into all the various kinds of cells needed in the body — blood, nerves and organs — but it is almost impossible to tell them apart during their initial development without complex techniques, even with the most advanced microscopes. Up to now, scientists have used intrusive fluorescent markers to tag molecules and track each cell, a process which can render them useless for therapeutic purposes anyway. By using a technique discovered at Southampton in the 1970s, known as Surface Enhanced Raman Spectroscopy (SERS), we have been able to look at adult stem cells on a molecular scale to distinguish one from another, meaning we can still use the cells for therapeutic purposes.”The team who discovered SERS in the 1970s found that by roughening a metal surface upon which they had placed molecules to be examined, they could increase the signal by which they could detect these molecules, by a million times. This allowed them to detect molecules in far smaller quantities than ever before. SERS has been used in many different capacities around the world and across industries, but this new research marks the first time it has been used in the field of cell therapeutics. …

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Genes that drive brain cancer revealed

Aug. 5, 2013 — A team of researchers at the Herbert Irving Comprehensive Cancer Center at Columbia University Medical Center has identified 18 new genes responsible for driving glioblastoma multiforme, the most common — and most aggressive — form of brain cancer in adults.The study was published August 5, 2013, in Nature Genetics.”Cancers rely on driver genes to remain cancers, and driver genes are the best targets for therapy,” said Antonio Iavarone, MD, professor of pathology and neurology at Columbia University Medical Center and a principal author of the study.”Once you know the driver in a particular tumor and you hit it, the cancer collapses. We think our study has identified the vast majority of drivers in glioblastoma, and therefore a list of the most important targets for glioblastoma drug development and the basis for personalized treatment of brain cancer.”Personalized treatment could be a reality soon for about 15 percent of glioblastoma patients, said Anna Lasorella, MD, associate professor of pediatrics and of pathology & cell biology at CUMC.”This study — together with our study from last year, Research May Lead to New Treatment for Type of Brain Cancer — shows that about 15 percent of glioblastomas are driven by genes that could be targeted with currently available FDA-approved drugs,” she said. “There is no reason why these patients couldn’t receive these drugs now in clinical trials.”New Bioinformatics Technique Distinguishes Driver Genes from Other MutationsIn any single tumor, hundreds of genes may be mutated, but distinguishing the mutations that drive cancer from mutations that have no effect has been a longstanding problem for researchers.The Columbia team used a combination of high throughput DNA sequencing and a new method of statistical analysis to generate a short list of driver candidates. The massive study of nearly 140 brain tumors sequenced the DNA and RNA of every gene in the tumors to identify all the mutations in each tumor. A statistical algorithm designed by co-author Raul Rabadan, PhD, assistant professor of biomedical informatics and systems biology, was then used to identify the mutations most likely to be driver mutations. The algorithm differs from other techniques to distinguish drivers from other mutations in that it considers not only how often the gene is mutated in different tumors, but also the manner in which it is mutated.”If one copy of the gene in a tumor is mutated at a single point and the second copy is mutated in a different way, there’s a higher probability that the gene is a driver,” Dr. Iavarone said.The analysis identified 15 driver genes that had been previously identified in other studies — confirming the accuracy of the technique — and 18 new driver genes that had never been implicated in glioblastoma.Significantly, some of the most important candidates among the 18 new genes, such as LZTR1 and delta catenin, were confirmed to be driver genes in laboratory studies involving cancer stem cells taken from human tumors and examined in culture, as well as after they had been implanted into mice.A New Model for Personalized Cancer TreatmentBecause patients’ tumors are powered by different driver genes, the researchers say that a complicated analysis will be needed for personalized glioblastoma treatment to become a reality. First, all the genes in a patient’s tumor must be sequenced and analyzed to identify its driver gene.”In some tumors it’s obvious what the driver is; but in others, it’s harder to figure out,” said Dr.Iavarone.Once the candidate driver is identified, it must be confirmed in laboratory tests with cancer stem cells isolated from the patient’s tumor.About 15 percent of glioblastoma driver genes can be targeted with currently available drugs, suggesting that personalized treatment for some patients may be possible in the near future. Personalized therapy for glioblastoma patients could be achieved by isolating the most aggressive cells from the patient’s tumor and identifying the driver gene responsible for the tumor’s growth (different tumors will be driven by different genes). …

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Chemical reaction could streamline manufacture of pharmaceuticals and other compounds

July 22, 2013 — Researchers at The University of Texas at Austin have discovered a new chemical reaction that has the potential to lower the cost and streamline the manufacture of compounds ranging from agricultural chemicals to pharmaceutical drugs.The reaction resolves a long-standing challenge in organic chemistry in creating phenolic compounds from aromatic hydrocarbons quickly and cheaply.Phenolic compounds, or phenols, are broadly used as disinfectants, fungicides and drugs to treat many ailments such as Parkinson’s disease. Creating a phenol seems deceptively simple. All it requires is replacing a hydrogen molecule on an aromatic hydrocarbon with an oxygen molecule.”This is a chemical transformation that is underdeveloped and at the same time pivotal in the production of many chemicals important to life as we know it,” said Dionicio Siegel, an assistant professor of chemistry in the College of Natural Sciences at The University of Texas at Austin.The secret that Siegel and his colleagues discovered is a substance called phthaloyl peroxide. This chemical was studied in the late 1950s and early 1960s, but it has been largely ignored during the intervening years.The scientists were conducting basic studies on phthaloyl peroxide, building on previous research, and decided to use it to tackle the age-old problem of transforming aromatic hydrocarbons into phenols.The advantage to using phthaloyl peroxide is that the reaction does not require the use of acids or catalysts to work, and it can add oxygen to a wide variety of starting materials.”There are no special conditions,” said Siegel. “You just combine the reagents, mix them and go. It’s very simple and straight forward.”The paper describing this discovery was published last week in Nature.The new process can be applied to other problems in organic chemistry. One particular area of interest is creating metabolites to drugs. Metabolites are the products left after the body finishes breaking down, or metabolizing, a substance. When testing drugs, scientists need to take into account not just how the drug itself reacts in the body, but also how the metabolites react.”We’ve had a long-standing interest in accessing metabolites of drugs or compounds that are used in biological systems,” said Siegel. “Just as it’s important that the drug doesn’t have deleterious side effects, it’s equally important that the metabolite doesn’t have an effect. …

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Good vibrations: Mediating mood through brain ultrasound

July 18, 2013 — Ultrasound vibrations applied to the brain may affect mood, UA researchers have discovered. The finding potentially could lead to new treatments for psychological and psychiatric disorders.University of Arizona researchers have found in a recent study that ultrasound waves applied to specific areas of the brain appear able to alter patients’ moods. The discovery has led the scientists to conduct further investigations with the hope that this technique could one day be used to treat conditions such as depression and anxiety.Dr. Stuart Hameroff, professor emeritus of the UA’s departments of anesthesiology and psychology and director of the UA’s Center for Consciousness Studies, is lead author on the first clinical study of brain ultrasound, which was published in the journal Brain Stimulation.Hameroff became interested in applying ultrasound to the human brain when he read about a study by colleague Jamie Tyler at the Virginia Polytechnic Institute, who found physiological and behavioral effects in animals of ultrasound applied to the scalp, with the waves passing through the skull.Hameroff knew that ultrasound vibrates in megahertz frequencies at about 10 million vibrations per second, and that microtubules, protein structures inside brain neurons linked to mood and consciousness, also resonate in megahertz frequencies. Hameroff proposed testing ultrasound treatment for mood on human brains.”I said to my anesthesiology colleagues, ‘we should try this on chronic pain patient volunteers.'” His colleagues respectfully suggested he try it on himself, first. Hameroff acquiesced.After 15 seconds with an ultrasound transducer, a standard ultrasound imaging device, placed against his head, Hameroff felt no effect.”I put it down and said, ‘well, that’s not going to work,'” he said. “And then about a minute later I started to feel like I’d had a martini.”His mood was elevated for the next hour or two, Hameroff said. Aware that his experience could be a placebo effect, an imagined effect derived from his expectation to feel a change, Hameroff set out to properly test the treatment with a clinical trial.With research committee and hospital approval, and patient informed consent, Hameroff and his colleagues applied transcranial ultrasound to 31 chronic pain patients at The University of Arizona Medical Center-South Campus, in a double blind study in which neither doctor nor subject knew if the ultrasound machine had been switched on or off.Patients reported improvements in mood for up to 40 minutes following treatment with brain ultrasound, compared with no difference in mood when the machine was switched off. The researchers confirmed the patients’ subjective reports of increases in positive mood with a Visual Analog Mood Scale, or VAMS, a standardized objective mood scale often used in psychological studies.”Encouraging!” Hameroff remarked. “We’re referring to transcranial ultrasound as ‘TUS,'” he added. …

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Splitting donated livers shown to be safe, allowing doctors to save two lives from single organ, study suggests

July 17, 2013 — Split liver transplantation carries no increased risk of failure in either recipient, allowing surgeons to safely save two lives from a single donated organ (graft), according to new research from Boston Children’s Hospital published online in the Journal of the American College of Surgeons.Due to their regenerative nature, livers donated by a deceased adult or adolescent can be surgically split into two unequally sized portions; the smaller segment is allocated to a young child awaiting transplant and the larger portion to an adult.”Infants waiting for a donor liver have the highest wait list mortality of all liver transplant candidates, and dozens of children die each year waiting for size-appropriate organs to become available,” says Heung Bae Kim, MD,director of Boston Children’s Hospital’s Pediatric Transplant Center and lead author on the study.”If we can increase the number of split livers to just 200 a year, which would still affect less than four percent of the total number of livers transplanted each year, it would save virtually every small child waiting for a new liver.”Based on his recent findings, (which includes research on how well children function with split livers)Kim is advocating for changes in how donor livers are allocated — automatically placing infants and small children at the top of the liver wait list, thereby giving pediatric transplant surgeons the option to split the first graft to become available. Once the liver has been split, the smaller portion is transplanted into a child and the larger portion is transplanted into the next appropriate adult on the list.Analyzing United Network for Organ Sharing (UNOS) records, Boston Children’s researchers looked at data compiled over a fifteen year period (1995-2010), studying the graft survival rates of 62,190 first-time adult deceased-donor liver transplant recipients, 889 of whom received partial grafts from a split liver transplant. The research shows that from 2002 forward the vast majority of adults who received a split graft experienced a risk of graft failure comparable to those who received a whole graft.”After an extensive review of the data, it’s clear that in the current era, with the exception of a small, very sick population of patients, adults who receive a split graft can expect to fare as well as those who received a whole organ,” says Ryan Cauley, MD, MPH, first author on the paper. “Because risks once associated with this technique are now negligible, if a center has a patient waiting for a liver and it has access to a split graft, there’s no reason not to accept it.”In addition to saving young patients, Kim’s proposed amendments to the allocation process could take place without sweeping change, affecting only an extremely small portion of available grafts. “There are around 500 to 600 pediatric liver transplants done each year in the United States, with split liver transplant only accounting for 120 of the total number,” Kim says. “By splitting just 80 more livers a year, it would make grafts available to virtually every small child on the wait list. Given the current national debate on maximizing access to organs for children, it’s my hope that implementing changes that would benefit children without harming adults would be considered favorably.”

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Injectable ‘smart sponge’ holds promise for controlled drug delivery

July 17, 2013 — Researchers have developed a drug delivery technique for diabetes treatment in which a sponge-like material surrounds an insulin core. The sponge expands and contracts in response to blood sugar levels to release insulin as needed. The technique could also be used for targeted drug delivery to cancer cells.”We wanted to mimic the function of health beta-cells, which produce insulin and control its release in a healthy body,” says Dr. Zhen Gu, lead author of a paper describing the work and an assistant professor in the joint biomedical engineering program at North Carolina State University and the University of North Carolina at Chapel Hill. “But what we’ve found also holds promise for smart drug delivery targeting cancer or other diseases.” The research team includes Daniel Anderson, the senior author and an associate professor of chemical engineering and member of the Koch Institute for Integrative Cancer Research at MIT, and researchers from the Department of Anesthesiology at Boston Children’s Hospital.The researchers created a spherical, sponge-like matrix out of chitosan, a material found in shrimp and crab shells. Scattered throughout this matrix are smaller nanocapsules made of a porous polymer that contain glucose oxidase or catalase enzymes. The sponge-like matrix surrounds a reservoir that contains insulin. The entire matrix sphere is approximately 250 micrometers in diameter and can be injected into a patient.When a diabetic patient’s blood sugar rises, the glucose triggers a reaction that causes the nanocapsules’ enzymes to release hydrogen ions. Those ions bind to the molecular strands of the chitosan sponge, giving them a positive charge. The positively charged chitosan strands then push away from each other, creating larger gaps in the sponge’s pores that allow the insulin to escape into the bloodstream. …

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Nanoparticles with protein ‘passports’ evade immune system, deliver more medication to tumors

July 16, 2013 — Scientists have found a way to sneak nanoparticles carrying tumor-fighting drugs past cells of the immune system, which would normally engulf the particles, preventing them from reaching their target. The technique takes advantage of the fact that all cells in the human body display a protein on their membranes that functions as a specific ‘passport’ in instructing immune cells not to attack them. By attaching a small piece of this protein to nanoparticles, scientists were able to fool immune cells in mice into recognizing the particles as ‘self’ rather than foreign, thereby increasing the amount of medication delivered to tumors.Cancer NanotechnologyCurrent approaches to chemotherapy leave patients with severe side effects because anti-cancer drugs meant to destroy tumors inadvertently kill healthy cells in the body. But scientists have recently developed nanoparticles that can ferry toxic medications directly to tumors while sparing healthy tissue. Because of their small size, nanoparticles escape from leaky blood vessels that are characteristic of tumors and accumulate in the cancerous tissue. Tumor cells take up the particles which release their toxic contents once inside. This localized delivery system allows doctors to give patients higher doses of medications than would normally be tolerated.Previous attempts have been made to ward off attack by the immune system by coating nanoparticles densely with polyethylene glycol (PEG) “brushes” that physically block the adhesion of proteins that normally deposit onto foreign bodies to attract macrophages. While these brushes delay the onset of the immune response, they don’t prevent it.The inspiration for Discher’s breakthrough work dates back thirteen years when a group of researchers showed with genetically engineered mice that a protein called CD47 — which is found in the cell membranes of nearly all mammals — interacts with a receptor on macrophages called SIRPa, and, in doing so, signals that the cell is native and shouldn’t be destroyed. The findings hinged on deleting mouse CD47 and raised many questions, including how such mice survive and whether there was relevance to humans.Discher, who was engineering nanoparticles that self-assemble into various shapes at the time of the discovery, realized that the CD47-SIRPa mechanism for self-recognition could, in principle, be exploited to help nanoparticles sneak past the immune system. But it was also clear that human versions of purified proteins needed to be studied for any translation to humans.In 2008, Discher’s lab demonstrated that human CD47 acts similarly to mouse CD47 as a “marker of self” via signaling through the SIRPa receptor. …

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Levitation: Droplets surfing on sound waves

July 16, 2013 — ETH researchers are able to make objects such as particles and liquid droplets fly in mid-air by letting them ride on acoustic waves. For the first time, they have been able to also control the movement of objects, merge droplets, letting them react chemically or biologically and even rotate a toothpick in the air.A toothpick floating in mid-air without any support — this may sound like it involves hidden threads, magnets or other sleight-of-hand tricks from magicians. But the actual trick used by Daniele Foresti, former doctoral student now a postdoctoral researcher at the Laboratory of Thermodynamics in Emerging Technologies, is based on acoustic waves. Despite the appearance of “magic,” he and his colleagues realized and controlled the planar movement of floating objects in air, regardless of their properties, involving no sorcery but science. This is not simply an amusing trick: moving objects such as particles or droplets of a liquid freely in mid-air makes it possible to investigate processes while avoiding any disruptive contact with a surface. For instance, some chemical reactions and biological processes are compromised by surfaces, and certain substances disintegrate on contact with a surface.Riding a stationary waveUntil now, scientists have been able to generate such a “contact-free” levitational state only with the help of magnets, electrical fields or in liquids with the help of buoyancy. These methods, however, limit the selection of materials that can be handled. “It is extremely difficult to levitate and precisely move a drop of liquid with a magnet. The fluid has to possess magnetic properties. In liquids, where buoyancy force supports levitation, you can only use immiscible liquids such as a drop of oil in water,” explains Dimos Poulikakos, Professor of Thermodynamics and head of the research project.With acoustic waves, in contrast, it is possible to levitate various objects regardless of their properties. …

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Injecting iron supplement lets scientists track transplanted stem cells

July 12, 2013 — A new, noninvasive technique for tracking stem cells after transplantation — developed by a cross-disciplinary team of radiologists, chemists, statisticians and materials scientists at the Stanford University School of Medicine — could help surgeons determine whether a procedure to repair injured or worn-out knees is successful.The technique, described in a study to be published online July 12 in Radiology, relies on an imaging agent already approved by the U.S. Food and Drug Administration for an entirely different purpose: anemia treatment. Although this study used rodents, the approach is likely to be adapted for use in humans this fall as part of a clinical trial in which mesenchymal stem cells will be delivered to the site of patients’ knee injuries. Mesenchymal stem cells are capable of differentiating into bone and cartilage, as well as muscle, fat and tendon, but not into the other cell types that populate the body.Every year, arthritis accounts for 44 million outpatient visits and 700,000 knee-replacement procedures. But the early repair of cartilage defects in young patients may prevent further deterioration of the joint and the need for knee replacement later in life, said the study’s senior author, Heike Daldrup-Link, MD, PhD, an associate professor of radiology and clinician who splits her time between research and treating pediatric patients.Mesenchymal stem cells have been used with some success in cartilage-repair procedures. “These cells can be easily derived from bone marrow of patients who are going to undergo the knee-repair procedure,” said Daldrup-Link, a member of the Molecular Imaging Program at Stanford. “And they can differentiate into the real-life tissues that compose our joints. But here, too, things can go wrong. The newly transferred cells might fail to engraft, or die. They might migrate away. …

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On the trail of bacteria: Infrared light allows characterization of pathogens

July 12, 2013 — Scientists at the University of Veterinary Medicine, Vienna (Vetmeduni Vienna) are hot on the trail of the bacterium Staphylococcus aureus. The researchers have developed a technique for the rapid and reliable distinction between strains that can cause chronic infections and those that cannot. Using infrared light and artificial intelligence, the scientists present a sophisticated method for the prediction of disease progression.Their results are now published in the Journal of Clinical Microbiology.The bacterium Staphylococcus aureus (S. aureus) is commonly found in nature and frequently colonizes the skin and the upper respiratory tract of humans. A healthy immune system can fight the microorganism but once the immune system is weakened the pathogen can spread and lead to life-threatening diseases of the lungs, the heart and other organs. Moreover, S. aureus produces toxins in foods and can cause serious food poisoning. Its effects are not confined to humans: in cattle, S. aureus frequently causes inflammation of the udders, so the bacterium is also of great interest in veterinary medicine.Bacterial microevolution and chronic infectionsS. aureus comes in many different forms, which helps it evade the immune system. …

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Hubble finds a true blue planet: Giant Jupiter-sized planet located 63 light-years away

July 11, 2013 — Astronomers using NASA’s Hubble Space Telescope have deduced the actual visible-light color of a planet orbiting another star 63 light-years away.If seen directly it would look like a “deep blue dot,” reminiscent of Earth’s color as seen from space. But that’s where all comparison ends. The planet’s daytime atmosphere is nearly 2,000 degrees Fahrenheit, and it possibly rains glass — sideways — in howling 4,500-mile-per-hour winds.The cobalt blue color doesn’t come from the reflection of a tropical ocean, but rather from a hazy blow-torched atmosphere and perhaps from high clouds laced with silicate particles. The condensation temperature of silicates could form very small drops of glass that would scatter blue light more than red light.The turbulent alien world, cataloged HD 189733b, is one of the nearest exoplanets to Earth that can be seen crossing the face of its star. It has been intensively studied by Hubble and other observatories, and its atmosphere is dramatically changeable and exotic.The observations yield new insights into the chemical composition and cloud structure of a bizarre “hot Jupiter” class planet, which orbits precariously close to its parent star.Clouds often play key roles in planetary atmospheres, and detecting the presence and importance of clouds in hot Jupiters is crucial, say researchers. “We obviously don’t know much on the physics and climatology of silicate clouds, so we are exploring a new domain of atmospheric physics,” said team member Frederic Pont of the University of Exeter, South West England, the United Kingdom.The team used Hubble’s Space Telescope Imaging Spectrograph to measure changes in the color of light from the planet before, during, and after the passage of the planet behind the parent star. This technique is possible because the planet’s orbit is tilted edge-on as viewed from Earth; therefore, it routinely passes in front of and then behind the star.Hubble measured a small drop in light — about one part in 10,000 — when the planet went behind the star, and a slight change in the color of the light, too. “We saw the light becoming less bright in the blue, but not in the green or the red. This means that the object that disappeared is blue because light was missing in the blue, but not in the red when it was hidden,” said Pont.The team’s study will be published online July 11 and will appear in the August 1 issue of the Astrophysical Journal Letters.Earlier observations have reported evidence for the scattering of blue light on the planet. But this most recent Hubble observation gives confirming evidence, said the researchers.The planet HD 189733b was discovered in 2005. …

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Cloud brightening to cool seas can protect coral reefs: Targeted cooling could offer a 50-year ‘breathing space’ for coral protection

July 10, 2013 — The seeding of marine clouds to cool sea surface temperatures could protect threatened coral reefs from being bleached by warming oceans. Research, published in Atmospheric Science Letters, proposes that a targeted version of the geo-engineering technique could give coral a fifty year ‘breathing space’ to recover from acidification and warming.”Coral bleaching over the last few decades has been caused by rising sea temperatures and ocean acidification,” said Dr Alan Gadian, from Leeds University. “Our research focuses on how Marine Cloud Brightening (MCB) could quickly lower sea temperatures in targeted areas.”There is a strong association between warmer-than-normal sea conditions and cases of coral bleaching. Bleaching is most likely to occur when a 1˚C temperature rise over a prolonged period, typically a 12-week period.To brighten clouds unmanned vehicles are used to spray tiny seawater droplets, which rise into the cloud, thereby increasing their reflectivity and duration. In this way, more sunlight is bounced back into space, resulting in a cooling sea surface temperature.While MCB was originally envisaged to be a global counter measure against warming, in principle the technique could be more targeted. In 2012 Dr. Gadian wrote how the use of MCB in the Atlantic could tame hurricanes.The new modeling study focuses the impact of seeding marine stratocumulus clouds over the Caribbean, French Polynesia, and the Great Barrier Reef. The study shows how the projected increases in coral bleaching, caused by rising CO2 levels, were eliminated while sea surface temperature cooled to pre-warming levels.Mild and severe coral bleaching events were projected over a 20-year period for the three target regions. Without MCB the amount of coral bleaching was seen to be severe; however, simultaneous deployment of MCB eliminated the risk of extra bleaching.”We estimate that MCB would have an annual cost of $400 million, however political, social and ethical costs make a true figure difficult to estimate, said Gadian. “Whatever the final figure, it will be less expensive than the damage the destruction of coral would wreck on neighboring countries, the local food chain and global biodiversity.”Public and political skepticism of geo-engineering projects remains a hurdle to their development; however, as the least disruptive form of Solar Radiation Management, the authors believe small-scale use of MCB for conservation would be unlikely to generate public opposition.The authors propose field-testing of MCB on a scale of 100 square metres, which could demonstrate its use, without producing significant climate effects. …

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Variation between hot extrasolar planet atmospheres revealed

July 5, 2013 — First results from the analysis of eight ‘hot Jupiter’ exoplanets suggest that winds and clouds play an important role in the atmospheric make up of these exotic planets.Catherine Huitson from Physics and Astronomy at the University of Exeter will present the results at the National Astronomy Meeting in St Andrews on Friday 5 July 2013.Hot Jupiters are giant exoplanets, similar in size to Jupiter, that orbit so close to their stars that their atmospheres can reach temperatures of 1000-3000 degrees Celsius. Astronomers can detect which gases are present in their atmospheres by analysing the spectrum of starlight filtered through the planet’s atmosphere when the planet passes in front of the star. Last year, a team led by the University of Exeter was awarded nearly 200 hours on the NASA/ESA Hubble Space Telescope to examine eight planets using this technique — the largest survey of its type to date.Catherine Huitson said: “These hot Jupiter planets are expected to have a vastly different composition from planets in our own Solar System like Jupiter, where temperatures at the cloud tops are around -150 degrees Celsius. The first planet we measured is one of the hottest to be observed, with a temperature of over 2000 degrees. The early results of the survey are now in, and they present a diverse range of puzzling properties.”The first, very hot planet observed showed an unexpected absence of titanium oxide. Current 3D models of hot Jupiter atmospheres suggest that grains of this heavy molecule should be circulated by fast winds, allowing gaseous titanium oxide to reach the observable upper atmosphere. The non-detection of the gas suggests that either the winds are not as strong as expected or the molecule is forming much larger grains that are too heavy be lifted.Huitson explained, “Titanium oxide is a solid on Earth, but we expect it to be present in the atmosphere of the hottest hot Jupiters because of the extreme temperatures. This molecule is important because it could trap atmospheric heat high up forming a stratosphere — the same role ozone plays on Earth. However, our results show that this molecule is not present in the upper atmosphere, meaning that we need to revise our understanding of how wind processes distribute materials.”The team also made a confirmed detection of water vapour in the atmosphere of two planets. Importantly, the water was found in the quantities predicted by theory, contrasting with previously observed planets.”While our models tell us that water (as steam) should be present in hot Jupiter atmospheres, until now the molecule has only been seen in limited quantities and in fewer planets than expected,” said Huitson.”Seeing steam in two exoplanets is a great confirmation of current theory. …

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