Neuroscience

Articles and news from the latest research reports.

Posts tagged disease

13 notes

Recent findings by an international collaboration including IRCM researchers hold new implications for the pathogenesis of myotonic dystrophy.
An important breakthrough could help in the fight against myotonic dystrophy. The discovery, recently published in the prestigious scientific journal Cell, results from an international collaboration between researchers at the IRCM, the Massachusetts Institute of Technology (MIT), the University of Southern California and Illumina. Their findings could lead to a better understanding of the causes of this disease.
Myotonic dystrophy (DM), also known as Steinert’s disease, is the most common form of muscular dystrophies seen in adults. This disorder is characterized by muscle weakness and myotonia (difficulty in relaxing muscles following contraction). It is a multi-system disease, typically involving a wide range of tissues and muscle.
“We studied a specific family of proteins called muscleblind-like proteins (Mbnl), which were first discovered in the fruit fly Drosophila melanogaster,” says Dr. Éric Lécuyer, Director of the RNA Biology research unit at the IRCM. “These RNA-binding proteins are known to play important functions in muscle and eye development, as well as in the pathogenesis of DM in humans.”
Because of the extreme heterogeneity of clinical symptoms, DM has been described as one of the most variable and complicated disorders known in medicine. The systems affected, the severity of symptoms, and the age of onset of those symptoms greatly vary between individuals, even within the same family.
“In patients with DM, levels of Mbnl proteins are depleted to different extents in various tissues,” explains Dr. Neal A.L. Cody, postdoctoral fellow in Dr. Lécuyer’s laboratory. “These alterations in levels and functions of Mbnl proteins are thought to play an important role in causing the disease.”
“The global transcriptome analyses conducted in this study yielded several insights into Mbnl function and established genomic resources for future functional, modeling, and clinical studies,” add Drs. Christopher B. Burge and Eric T. Wang from MIT, the researchers who headed the study. “This knowledge will be invaluable in reconstructing the order of events that occur during DM pathogenesis, and could lead to the development of diagnostic tools for monitoring disease progression and response to therapy.”
According to Muscular Dystrophy Canada, myotonic dystrophy is the most common form of muscle disease, affecting approximately one person in 8,000 worldwide. However, in Quebec’s region of Charlevoix / Saguenay-Lac-Saint-Jean, the prevalence is exceptionally high, with one person in 500 affected by the disease. There is no cure for myotonic dystrophy at the present time. Treatment is symptomatic, meaning that problems associated with myotonic dystrophy are treated individually.

Recent findings by an international collaboration including IRCM researchers hold new implications for the pathogenesis of myotonic dystrophy.

An important breakthrough could help in the fight against myotonic dystrophy. The discovery, recently published in the prestigious scientific journal Cell, results from an international collaboration between researchers at the IRCM, the Massachusetts Institute of Technology (MIT), the University of Southern California and Illumina. Their findings could lead to a better understanding of the causes of this disease.

Myotonic dystrophy (DM), also known as Steinert’s disease, is the most common form of muscular dystrophies seen in adults. This disorder is characterized by muscle weakness and myotonia (difficulty in relaxing muscles following contraction). It is a multi-system disease, typically involving a wide range of tissues and muscle.

“We studied a specific family of proteins called muscleblind-like proteins (Mbnl), which were first discovered in the fruit fly Drosophila melanogaster,” says Dr. Éric Lécuyer, Director of the RNA Biology research unit at the IRCM. “These RNA-binding proteins are known to play important functions in muscle and eye development, as well as in the pathogenesis of DM in humans.”

Because of the extreme heterogeneity of clinical symptoms, DM has been described as one of the most variable and complicated disorders known in medicine. The systems affected, the severity of symptoms, and the age of onset of those symptoms greatly vary between individuals, even within the same family.

“In patients with DM, levels of Mbnl proteins are depleted to different extents in various tissues,” explains Dr. Neal A.L. Cody, postdoctoral fellow in Dr. Lécuyer’s laboratory. “These alterations in levels and functions of Mbnl proteins are thought to play an important role in causing the disease.”

“The global transcriptome analyses conducted in this study yielded several insights into Mbnl function and established genomic resources for future functional, modeling, and clinical studies,” add Drs. Christopher B. Burge and Eric T. Wang from MIT, the researchers who headed the study. “This knowledge will be invaluable in reconstructing the order of events that occur during DM pathogenesis, and could lead to the development of diagnostic tools for monitoring disease progression and response to therapy.”

According to Muscular Dystrophy Canada, myotonic dystrophy is the most common form of muscle disease, affecting approximately one person in 8,000 worldwide. However, in Quebec’s region of Charlevoix / Saguenay-Lac-Saint-Jean, the prevalence is exceptionally high, with one person in 500 affected by the disease. There is no cure for myotonic dystrophy at the present time. Treatment is symptomatic, meaning that problems associated with myotonic dystrophy are treated individually.

Filed under myotonic dystrophy DM steinert’s disease protein neuroscience brain disease science

20 notes

'Genomic CSI' Helps Contain a Killer

22 August 2012 

In June of last year, a 43-year old woman was admitted to the Clinical Center of the National Institutes of Health in Bethesda, Maryland, for a lung disease. Doctors knew she was carrying a highly resistant form of a deadly bacterium known as Klebsiella pneumoniae—although it didn’t make her sick—and they placed her in isolation. When the woman was discharged, no one else appeared to have become infected. A few weeks later, however, another patient was found to be carrying the bacterium, and over the next 3 months, 12 more intensive care patients contracted it. Six died as a direct result of the infection.

Doctors could not make sense of the outbreak with the usual methods: A survey of bed locations showed that the first patient had had no direct contact with any of the others and, in theory, Klebsiella might have been introduced into the hospital multiple times. So physicians turned to the bacterium’s genome for answers. The approach, known as genomic epidemiology, helped them track the path of the microbe, contain the disease, and save lives, according to a new study.

Tracking a killer. Full-genome sequencing revealed the movements of Klebsiella (shown) within one hospital. Credit: Image courtesy of Adrian Zelazny

Genomic epidemiology makes use of the fact that when bacteria divide, they accumulate mutations. As a result, the bacterial genome differs slightly—often by just one or two letters of genetic code, or base pairs—from one patient to the next. By fully sequencing the genomes of patients’ bacteria and finding these minute differences, researchers can track microbial movements with unprecedented precision. The technique has already been used to reconstruct the spread of methicillin-resistant Staphylococcus aureus (MRSA) around the world and to pinpoint the origin of a cholera outbreak in Haiti.

It also helped the doctors at the hospital in Bethesda. Comparing the genomes from all patients showed that the female patient admitted in June had indeed initiated the outbreak; the researchers showed that the bacteria had been transmitted from her to other patients three times independently. Apparently, transmission occurred in ways the researchers didn’t understand, says Tara Palmore, an infectious disease physician at the hospital. “When we realized there was more than met the eye, we started testing everyone in the hospital,” she says. That helped identify four more infected patients outside the intensive care unit, the scientists report online today in Science Translational Medicine. They were quickly isolated, which Palmore believes prevented further spread.

Just how the microbes were transmitted is still unclear. Palmore assumes that the bacteria mainly traveled on the hands of doctors. But the clinic had stationed a person outside the isolation rooms to make sure everyone who entered followed a hygiene regimen 24/7. That suggests that bacteria might have established colonies on surfaces or medical equipment and spread that way as well. “The conventional wisdom is that Klebsiellas do not really survive in the environment, but we found them in six sink drains and a ventilator,” Palmore says.

"This small study demonstrates the potential power of whole genome sequencing for outbreak investigation and surveillance," says Sharon Peacock, a microbiologist at the University of Cambridge in the United Kingdom who was not involved in the work. And infectious disease specialist Dag Harmsen of the University Clinic of Münster in Germany says it is "further proof that the time is ripe for using genomic sequencing of pathogens in a hospital setting." The paper also highlights the dangers of resistant Gram-negative bacteria like Klebsiella p., he adds. In many patients, the bacteria were not susceptible to any available antibiotic; not even to colistin, an old compound used only when all else fails. “This is even more dramatic than MRSA, because you have nothing left to treat the patients with,” Harmsen says. Since the outbreak, every patient at the hospital is checked for such dangerous pathogens; one more resistant Klebsiella case—although a different strain—has been found so far.

Genomic epidemiology could make it easier for hospitals to deal with similar outbreaks, Palmore says. “A lot of academic centers have the ability to do this now,” she says. The cost is becoming less of an issue; during last year’s outbreak, scientists still paid about $2000 per genome sequenced; now that would be closer to $500. But Peacock cautions that it still takes bioinformatics specialists several weeks to interpret the data. “This technology will not be applicable to routine clinical practice until automated interpretation tools become available.”

(Source: news.sciencemag.org)

Filed under bacteria disease genomic epidemiology genomics microbes neuroscience science Klebsiella pneumoniae

19 notes

Watson turns medic: Supercomputer to diagnose disease

22 August 2012 by Jim Giles

More than a year after it won the quiz show Jeopardy!, IBM’s supercomputer is learning how to help doctors diagnose patients

IT IS more than a year since Watson, IBM’s famous supercomputer, opened a new frontier for artificial intelligence by beating human champions of the quiz show Jeopardy!. Now Watson is learning to use its language skills to help doctors diagnose patients.

Progress is most advanced in cancer care, where IBM is working with several US hospitals to build a virtual physicians’ assistant. “It’s a machine that can read everything and forget nothing,” says Larry Norton, a doctor at the Memorial Sloan-Kettering Cancer Center in New York, who is collaborating with IBM.

When playing Jeopardy!, Watson analysed each question in a bid to guess what it was about. Then it looked for possible answers in its database, made up of sources such as encyclopaedias, scoring each according to the evidence associated with it and answering with the highest rated answer. The system takes a similar approach when dealing with medical questions, although in this case it draws on information from medical journals and clinical guidelines.

To test the system, Watson was first tasked with answering questions taken from Doctor’s Dilemma, a competition for trainee doctors that takes place at the annual meeting of the American College of Physicians. Watson was given 188 questions that it had not seen before and achieved around 50 per cent accuracy - not bad for an early test, but hardly ideal (Artificial Intelligence, doi.org/h6m).

To improve, Watson is now absorbing records - tens of thousands at Sloan-Kettering alone - of treatments and outcomes associated with individual patients. Given data on a new patient, Watson looks for information on those with similar symptoms, as well as the treatments that have been the most successful. The idea is it will give doctors a range of possible diagnoses and treatment options, each with an associated level of confidence. The result will be a system that its creators say can suggest nuanced treatment plans that take into account factors like drug interactions and a patient’s medical history.

William Audeh, a doctor at Cedars-Sinai Medical Center in Los Angeles, who is working with IBM, says the last few months have involved “filling Watson’s brain” with medical data. Watson is answering basic questions based on the treatment guidelines that are published by medical societies and is showing “very positive” results, he adds.

The technology is particularly useful in oncology because doctors struggle to keep up with the explosion of genomic and molecular data generated about each cancer type. This means it can take years for findings to translate into medical practice. By contrast, Watson can absorb new results and relay them to doctors quickly, together with an estimate of their potential usefulness. “Watson really has great potential,” says Audeh. “Cancer needs it most because it’s becoming so complicated so quickly.”

The IBM system could also approve treatment requests more quickly. At WellPoint, one of the largest insurers in the US, nurses use guidelines and patient history to determine if a request is in line with company policy. Nurses are now training Watson by feeding it test requests and observing the answers. Progress is good and the system could be deployed next year, says WellPoint’s Cindy Wakefield. “Now it can take up to a couple of days,” she says. “We hope Watson can return the accurate recommendation in a matter of minutes.”

Source: NewScientist

Filed under Watson diagnosis disease neuroscience science supercomputer technology AI

38 notes

Acute Stress Alters Control of Gene Activity: Researchers Examine DNA Methylation

ScienceDaily (Aug. 15, 2012) — Acute stress alters the methylation of the DNA and thus the activity of certain genes. This is reported by researchers at the Ruhr-Universität Bochum together with colleagues from Basel, Trier and London for the first time in the journal Translational Psychiatry. “The results provide evidence how stress could be related to a higher risk of mental or physical illness,” says Prof. Dr. Gunther Meinlschmidt from the Clinic of Psychosomatic Medicine and Psychotherapy at the LWL University Hospital of the RUB. The team looked at gene segments which are relevant to biological stress regulation.

In stressful social situations, the methylation patterns (bright spheres) of the DNA change. (Credit: Illustration: Christoph Unternährer and Christian Horisberger)

Epigenetics — the “second code” — regulates gene activity

Our genetic material, the DNA, provides the construction manual for the proteins that our bodies need. Which proteins a cell produces depends on the cell type and the environment. So-termed epigenetic information determines which genes are read, acting quasi as a biological switch. An example of such a switch is provided by methyl (CH3) groups that attach to specific sections of the DNA and can remain there for a long time — even when the cell divides. Previous studies have shown that stressful experiences and psychological trauma in early life are associated with long-term altered DNA methylation. Whether the DNA methylation also changes after acute psychosocial stress, was, however, previously unknown.

Two genes tested

To clarify this issue, the research group examined two genes in particular: the gene for the oxytocin receptor, i.e. the docking site for the neurotransmitter oxytocin, which has become known as the “trust hormone” or “anti-stress hormone”; and the gene for the nerve growth factor Brain-Derived Neurotrophic Factor (BDNF), which is mainly responsible for the development and cross-linking of brain cells. The researchers tested 76 people who had to participate in a fictitious job interview and solve arithmetic problems under observation — a proven means for inducing acute stress in an experiment. For the analysis of the DNA methylation, they took blood samples from the subjects before the test as well as ten and ninety minutes afterwards.

DNA methylation changes under acute psychosocial stress

Stress had no effect on the methylation of the BDNF gene. In a section of the oxytocin receptor gene, however, methylation already increased within the first ten minutes of the stressful situation. This suggests that the cells formed less oxytocin receptors. Ninety minutes after the stress test, the methylation dropped below the original level before the test. This suggests that the receptor production was excessively stimulated.

Possible link between stress and disease

Stress increases the risk of physical or mental illness. The stress-related costs in Germany alone amount to many billions of Euros every year. In recent years, there have been indications that epigenetic processes are involved in the development of various chronic diseases such as cancer or depression. “Epigenetic changes may well be an important link between stress and chronic diseases” says Prof. Meinlschmidt, Head of the Research Department of Psychobiology, Psychosomatics and Psychotherapy at the LWL University Hospital. “We hope to identify more complex epigenetic stress patterns in future and thus to be able to determine the associated risk of disease. This could provide information on new approaches to treatment and prevention.” The work originated within the framework of an interdisciplinary research consortium with the University of Trier, the University of Basel and King’s College London. The German Research Foundation and the Swiss National Science Foundation supported the study.

Source: Science Daily

Filed under brain neuroscience psychology science stress disease DNA methylation DNA

18 notes


Having an operation?Don’t be surprised if the surgeon performs it from the room next door.Indeed, he could even operate from halfway across the world — because these doctors are increasingly using robots to treat disease and injury.‘These are incredibly exciting times,’ says Brian Davies, emeritus professor of medical robotics at Imperial College London and inventor of the surgical robot, which in April 1991 became the first in the world to remove tissue from a living human.‘Robots can work much more accurately than human hands, which is fantastic now that we are seeking minimally invasive surgery through a tiny incision where precision is key,’ says Professor Davies.Of course, the surgeon still performs the operation, but uses the robot to see inside the body, or operates it using a joystick or console so it’s like a spare arm — but without the human hand’s natural shake.‘Medical robots are not like the sci-fi images of autonomous humanoids; they are sophisticated computer-assisted instruments that remain always under the surgeon’s control,’ says Dr Patrick Finlay, founder of medical robotics firm MediMaton.

Read more: The rise of Robodoc: They can operate on everything from your heart to creaky knees - but would you put your life into the hands of a robot surgeon?

Having an operation?

Don’t be surprised if the surgeon performs it from the room next door.

Indeed, he could even operate from halfway across the world — because these doctors are increasingly using robots to treat disease and injury.

‘These are incredibly exciting times,’ says Brian Davies, emeritus professor of medical robotics at Imperial College London and inventor of the surgical robot, which in April 1991 became the first in the world to remove tissue from a living human.

‘Robots can work much more accurately than human hands, which is fantastic now that we are seeking minimally invasive surgery through a tiny incision where precision is key,’ says Professor Davies.

Of course, the surgeon still performs the operation, but uses the robot to see inside the body, or operates it using a joystick or console so it’s like a spare arm — but without the human hand’s natural shake.

‘Medical robots are not like the sci-fi images of autonomous humanoids; they are sophisticated computer-assisted instruments that remain always under the surgeon’s control,’ says Dr Patrick Finlay, founder of medical robotics firm MediMaton.

Read more: The rise of Robodoc: They can operate on everything from your heart to creaky knees - but would you put your life into the hands of a robot surgeon?

Filed under brain health medical robots neuroscience robotics science surgery disease injury

13 notes

Molecular Link Between Circadian Clock Disturbances and Inflammatory Diseases Discovered

ScienceDaily (Aug. 1, 2012) — Scientists have known for some time that throwing off the body’s circadian rhythm can negatively affect body chemistry. In fact, workers whose sleep-wake cycles are disrupted by night shifts are more susceptible to chronic inflammatory diseases such as diabetes, obesity and cancer.

Researchers at the Salk Institute for Biological Studies have now found a possible molecular link between circadian rhythm disturbances and an increased inflammatory response. In a study published July 9 in Proceedings of the National Academy of Sciences, the Salk team found that the absence of a key circadian clock component called cryptochrome (CRY) leads to the activation of a signaling system that elevates levels of inflammatory molecules in the body.

"There is compelling evidence that low-grade, constant inflammation could be the underlying cause of chronic diseases such as diabetes, obesity and cancer," says senior author Inder Verma, a professor in Salk’s Laboratory of Genetics and the Irwin and Joan Jacobs Chair in Exemplary Life Science. "Our results strongly indicate that an arrhythmic clock system, induced by the absence of CRY proteins, alone is sufficient to increase the stress level of cells, leading to the constant expression of inflammatory proteins and causing low-grade, chronic inflammation."

Cryptochrome serves as a break to slow the circadian clock’s activity, signaling our biological systems to wind down each evening. In the morning, CRY stops inhibiting the clock’s activity, helping our physiology ramp up for the coming day.

To gain insight into the role of circadian clock components on immune function, the Salk scientists measured the expression of inflammatory mediators in the hypothalamus (the area of the brain responsible for sleep-wake cycle regulation) of mice with deleted CRY genes. Through a variety of tests, these knockout mice showed a significant increase in the expression of certain inflammatory proteins known as cytokines, including interleukin-6 and tumor necrosis factor-α, compared to mice with CRY genes.

"Our findings demonstrate that a lack of cryptochrome activates these proinflammatory molecules, indicating a potential role for cryptochrome in the regulation of inflammatory cytokine expression," says Satchidananda Panda, an associate professor in Salk’s Regulatory Biology Laboratory and one of the senior authors of the study.

In addition, the researchers found that a lack of CRY activated the NF-kB pathway, a molecular signaling conduit that controls many genes involved in inflammation. NF-kB is a protein complex in a cell’s cytoplasm, “just happily doing nothing,” says Verma. In response to stimuli, it is transferred to the cell’s nucleus, where it binds to inflammation genes and turns them on. The regulation of these genes is tightly controlled, but NF-kB does not completely shut off their expression. This lingering expression causes inflammation.

"Every time this pathway is turned on, there is a residual amount of inflammation left in the body," says Rajesh Narasimamurthy, a research associate in Verma’s laboratory and the paper’s first author. "That adds up over time, contributing to inflammation-related diseases like obesity and diabetes."

Previous research has shown that suppressing the activity of the NF-kB pathway might be a suitable therapy for some diseases. For example, NF-kB is activated automatically in cancer cells of multiple myeloma, which affects infection-fighting plasma cells in the bone marrow and allows the cells to proliferate. Drugs that inhibit this activity might be able to degrade NF-kB to the point that it may kill off the disease.

The researchers say the goal now is to find out how to suppress NF-kB activation in the short term to treat diseases like diabetes. They caution that any long-term suppression of the pathway could lead to chronic infection. “We would like to find molecules that modify this activity and focus on those small-molecule inhibitors to treat disease,” Verma adds.

Source: Science Daily

Filed under CRY NF-kB circadian rhythms cryptochrome diabetes disease inflammatory diseases neuroscience obesity science protein

6 notes

Research team finds possible clue to progression of multiple sclerosis

July 31, 2012

Wayne State University School of Medicine researchers, working with colleagues in Canada, have found that one or more substances produced by a type of immune cell in people with multiple sclerosis (MS) may play a role in the disease’s progression. The finding could lead to new targeted therapies for MS treatment.

B cells, said Robert Lisak, M.D., professor of neurology at Wayne State and lead author of the study, are a subset of lymphocytes (a type of circulating white blood cell) that mature to become plasma cells and produce immunoglobulins, proteins that serve as antibodies. The B cells appear to have other functions, including helping to regulate other lymphocytes, particularly T cells, and helping maintain normal immune function when healthy.

In patients with MS, the B cells appear to attack the brain and spinal cord, possibly because there are substances produced in the nervous system and the meninges — the covering of the brain and spinal cord — that attract them. Once within the meninges or central nervous system, Lisak said, the activated B cells secrete one or more substances that do not seem to be immunoglobulins but that damage oligodendrocytes, the cells that produce a protective substance called myelin.

The B cells appear to be more active in patients with MS, which may explain why they produce these toxic substances and, in part, why they are attracted to the meninges and the nervous system.

The brain, for the most part, can be divided into gray and white areas. Neurons are located in the gray area, and the white parts are where neurons send their axons — similar to electrical cables carrying messages — to communicate with other neurons and bring messages from the brain to the muscles. The white parts of the brain are white because oligodendrocytes make myelin, a cholesterol-rich membrane that coats the axons. The myelin’s function is to insulate the axons, akin to the plastic coating on an electrical cable. In addition, the myelin speeds communication along axons and makes that communication more reliable. When the myelin coating is attacked and degraded, impulses — messages from the brain to other parts of the body — can “leak” and be derailed from their target. Oligodendrocytes also seem to engage in other activities important to nerve cells and their axons. 

The researchers took B cells from the blood of seven patients with relapsing-remitting MS and from four healthy patients. They grew the cells in a medium, and after removing the cells from the culture collected material produced by the cells. After adding the material produced by the B cells, including the cells that produce myelin, to the brain cells of animal models, the scientists found significantly more oligodendrocytes from the MS group died when compared to material produced by the B cells from the healthy control group. The team also found differences in other brain cells that interact with oligodendrocytes in the brain.

"We think this is a very significant finding, particularly for the damage to the cerebral cortex seen in patients with MS, because those areas seem to be damaged by material spreading into the brain from the meninges, which are rich in B cells adjacent to the areas of brain damage," Lisak said.

The team is now applying for grants from several sources to conduct further studies to identify the toxic factor or factors produced by B cells responsible for killing oligodendrocytes. Identification of the substance could lead to new therapeutic methods that could switch off the oligodendrocyte-killing capabilities of B cells, which, in turn, would help protect myelin from attacks.

Provided by Wayne State University

Source: medicalxpress.com

Filed under science neuroscience psychology MS disease treatment brain neuron

14 notes

Possible new approach to fighting chronic inflammatory diseases

30 July 2012

Researchers from The University of Queensland’s Institute for Molecular Bioscience have discovered a potential new approach to treating chronic inflammatory diseases such as arthritis. 

Professor David Fairlie and his colleagues have developed an experimental treatment that has proven effective at reducing symptoms and stopping the progression of the disease in models of arthritis. 

“Human enzymes called proteases stimulate the secretion of immune cells that, when the correct amount is released, play important roles in digestion, fighting infections and healing wounds,” Professor Fairlie said. 

“But in chronic inflammatory diseases such as arthritis, these enzymes continuously stimulate the release of immune cells, which cause inflammation when present at high levels. This leads to ongoing tissue damage.” 

Professor Fairlie and his team have developed experimental compounds that block this stimulation and successfully reduce chronic inflammatory arthritis in experimental models. 

If the treatment could be transferred to humans, it has the potential to reduce both the health and economic impacts of chronic inflammatory diseases. 

Almost four million Australians suffer from chronic joint pain and disability caused by various forms of arthritis, including osteoarthritis, rheumatoid arthritis and gout. 

Related healthcare and loss of employment cost Australia over $20 billion per year, an amount that is expected to increase dramatically as our population ages. 

These promising new findings are published in the current hard-copy edition of The Federation of American Societies For Experimental Biology Journal, the world’s most cited scientific journal in biology. 

Journal subscribers can access the paper at this address: http://bit.ly/Pg8lgk

Source: The University of Queensland

Filed under science neuroscience chronic inflammatory diseases arthritis disease enzymes inflammation treatment biology

30 notes

Chemical Makes Blind Mice See; Compound Holds Promise for Treating Humans

ScienceDaily (July 25, 2012) — A team of University of California, Berkeley, scientists in collaboration with researchers at the University of Munich and University of Washington, in Seattle, has discovered a chemical that temporarily restores some vision to blind mice, and is working on an improved compound that may someday allow people with degenerative blindness to see again.

Mice with a genetic disease that causes blindness regained some sight after injection with a chemical “photoswitch.” The eye of the untreated mouse on the left shows no response to light, while the pupil of the mouse on the right, which was injected with the chemical, contracts in light. (Credit: Image courtesy of University of California - Berkeley)

The approach could eventually help those with retinitis pigmentosa, a genetic disease that is the most common inherited form of blindness, as well as age-related macular degeneration, the most common cause of acquired blindness in the developed world. In both diseases, the light sensitive cells in the retina — the rods and cones — die, leaving the eye without functional photoreceptors.

The chemical, called AAQ, acts by making the remaining, normally “blind” cells in the retina sensitive to light, said lead researcher Richard Kramer, UC Berkeley professor of molecular and cell biology. AAQ is a photoswitch that binds to protein ion channels on the surface of retinal cells. When switched on by light, AAQ alters the flow of ions through the channels and activates these neurons much the way rods and cones are activated by light.

"This is similar to the way local anesthetics work: they embed themselves in ion channels and stick around for a long time, so that you stay numb for a long time," Kramer said. "Our molecule is different in that it’s light sensitive, so you can turn it on and off and turn on or off neural activity."

Because the chemical eventually wears off, it may offer a safer alternative to other experimental approaches for restoring sight, such as gene or stem cell therapies, which permanently change the retina. It is also less invasive than implanting light-sensitive electronic chips in the eye.

"The advantage of this approach is that it is a simple chemical, which means that you can change the dosage, you can use it in combination with other therapies, or you can discontinue the therapy if you don’t like the results. As improved chemicals become available, you could offer them to patients. You can’t do that when you surgically implant a chip or after you genetically modify somebody," Kramer said.

"This is a major advance in the field of vision restoration," said co-author Dr. Russell Van Gelder, an ophthalmologist and chair of the Department of Ophthalmology at the University of Washington, Seattle.

Kramer, Van Gelder, chemist Dirk Trauner and their colleagues at UC Berkeley, the University of Washington, Seattle, and the University of Munich will publish their findings on July 26, in the journal Neuron.

The blind mice in the experiment had genetic mutations that made their rods and cones die within months of birth and inactivated other photopigments in the eye. After injecting very small amounts of AAQ into the eyes of the blind mice, Kramer and his colleagues confirmed that they had restored light sensitivity because the mice’s pupils contracted in bright light, and the mice showed light avoidance, a typical rodent behavior impossible without the animals being able to see some light. Kramer is hoping to conduct more sophisticated vision tests in rodents injected with the next generation of the compound.

"The photoswitch approach offers real hope to patients with retinal degeneration," Van Gelder said. "We still need to show that these compounds are safe and will work in people the way they work in mice, but these results demonstrate that this class of compound restores light sensitivity to retinas blind from genetic disease."

From optogenetics to implanted chips

The current technologies being evaluated for restoring sight to people whose rods and cones have died include injection of stem cells to regenerate the rods and cones; “optogenetics,” that is, gene therapy to insert a photoreceptor gene into blind neurons to make them sensitive to light; and installation of electronic prosthetic devices, such as a small light-sensitive retinal chip with electrodes that stimulate blind neurons. Several dozen people already have retinal implants and have had rudimentary, low vision restored, Kramer said.

Eight years ago, Kramer, Trauner, a former UC Berkeley chemist now at the University of Munich, and their colleagues developed an optogenetic technique to chemically alter potassium ion channels in blind neurons so that a photoswitch could latch on. Potassium channels normally open to turn a cell off, but with the attached photoswitch, they were opened when hit by ultraviolet light and closed when hit by green light, thereby activating and deactivating the neurons.

Subsequently, Trauner synthesized AAQ (acrylamide-azobenzene-quaternary ammonium), a photoswitch that attaches to potassium channels without the need to genetically modify the channel. Tests of this compound are reported in the current Neuron paper.

New versions of AAQ now being tested are better, Kramer said. They activate neurons for days rather than hours using blue-green light of moderate intensity, and these photoswitches naturally deactivate in darkness, so that a second color of light is not needed to switch them off.

"This is what we are really excited about," he said.

Source: Science Daily

Filed under blindness brain chemicals disease genetics neuroscience psychology science vision AAQ

29 notes

New drug could treat Alzheimer’s, multiple sclerosis and brain injury

July 24, 2012

A new class of drug developed at Northwestern University Feinberg School of Medicine shows early promise of being a one-size-fits-all therapy for Alzheimer’s disease, Parkinson’s disease, multiple sclerosis and traumatic brain injury by reducing inflammation in the brain.

Northwestern has recently been issued patents to cover this new drug class and has licensed the commercial development to a biotech company that has recently completed the first human Phase 1 clinical trial for the drug.

The drugs in this class target a particular type of brain inflammation, which is a common denominator in these neurological diseases and in traumatic brain injury and stroke. This brain inflammation, also called neuroinflammation, is increasingly believed to play a major role in the progressive damage characteristic of these chronic diseases and brain injuries.

By addressing brain inflammation, the new class of drugs — represented by MW151 and MW189 — offers an entirely different therapeutic approach to Alzheimer’s than current ones being tested to prevent the development of beta amyloid plaques in the brain. The plaques are an indicator of the disease but not a proven cause.

A new preclinical study published today in the Journal of Neuroscience, reports that when one of the new Northwestern drugs is given to a mouse genetically engineered to develop Alzheimer’s, it prevents the development of the full-blown disease. The study, from Northwestern’s Feinberg School and the University of Kentucky, identifies the optimal therapeutic time window for administering the drug, which is taken orally and easily crosses the blood-brain barrier.

"This could become part of a collection of drugs you could use to prevent the development of Alzheimer’s," said D. Martin Watterson, a professor of molecular pharmacology and biological chemistry at the Feinberg School, whose lab developed the drug. He is a coauthor of the study.

In previous animal studies, the same drug reduced the neurological damage caused by closed-head traumatic brain injury and inhibited the development of a multiple sclerosis-like disease. In these diseases as well as in Alzheimer’s, the studies show the therapy time window is critical.

Read more …

Filed under MS alzheimer alzheimer's disease brain brain injury drug medication neuroscience parkinson parkinson's disease psychology science disease neuroinflammation

free counters