Discovery identifies new treatment target for age-releated macular degeneration, Alzheimer’s

0 comments

Posted on 11th March 2016 by Pacific ClearVision Institute in General |Retina

For the first time, researchers at LSU Health New Orleans have shown that a protein critical to the body’s ability to remove waste products from the brain and retina is diminished in age-related macular degeneration (AMD), after first making the discovery in an Alzheimer’s disease (AD) brain. The research team, led by Walter Lukiw, PhD, Professor of Neurology, Neuroscience and Ophthalmology at LSU Health New Orleans Neuroscience Center, also discovered a key reason, identifying a new treatment target. The paper, microRNA-34a-mediated down-regulation of the microglial-enriched triggering receptor and phagocytosis-sensor TREM2 in age-related macular degeneration, was published March 7, 2016, online in the journal, PLOS ONE.

During their normal day-to-day operation, the brain and retina produce relatively large quantities of waste products, which have to be cleared away so that they do not clog up the delicate parts of the thinking and visual system. Part of the waste disposal system consists of a very special waste-sensing transmembrane protein located in highly specialized cells called microglial cells found in the brain and retina. This waste-sensing protein in microglial cells is known to scientists as the “triggering receptor expressed in microglia,” or TREM2 protein.

In this work, the researchers examined human AD-affected brain and AMD-affected retina, the retina of aging 5xFAD transgenic animals and microglial and other brain and retinal cells in culture.

“We have discovered that in age-related degenerative diseases of the brain, such as Alzheimer’s disease, and the retina, such as age-related macular degeneration, there is a lowered and insufficient amount of TREM2 protein, and this may be in part responsible for the inability of the brain and retina to clear away their end-stage waste products,” notes Dr. Lukiw, who is also the Bollinger Professor of Alzheimer’s Disease at LSU Health New Orleans.

These waste products consist chiefly of amyloid — misfolded proteins, small various remnants of the innate immune system, small, very sticky toxic proteins and prominently, a 42-amino acid amyloid protein called Aß42 peptide. Because they cannot be properly removed, the waste products accumulate in the brain and retina and contribute to the progressive appearance of insoluble lesions called senile plaques in the brain and drusen in the retina. These lesions ultimately contribute to episodes of age-related inflammatory degeneration.

“We have also discovered that an excessive amount of a small piece of ribonucleic acid (RNA) called microRNA-34a, or miRNA-34a, is in part responsible for insufficient TREM2 protein,” adds Dr. Lukiw. “These scientific findings further indicate that getting rid of the excessive miRNA-34a to restore normal TREM2 abundance may provide a highly effective therapeutic strategy for the treatment of both degenerative diseases of the brain, such as Alzheimer’s disease, and progressive diseases of the retina, such as age-related macular degeneration.”

Eye cells may use math to detect motion

0 comments

Posted on 11th March 2016 by Pacific ClearVision Institute in General |Retina

Our eyes constantly send bits of information about the world around us to our brains where the information is assembled into objects we recognize. Along the way, a series of neurons in the eye uses electrical and chemical signals to relay the information. In a study of mice, National Institutes of Health (NIH) scientists showed how one type of neuron may do this to distinguish moving objects. The study suggests that the NMDA receptor, a protein normally associated with learning and memory, may help neurons in the eye and the brain relay that information.

“The eye is a window onto the outside world and the inner workings of the brain,” said Jeffrey S. Diamond, Ph.D., senior scientist at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), and the senior author of the study published in Neuron. “Our results show how neurons in the eye and the brain may use NMDA receptors to help them detect motion in a complex visual world.”

Vision begins when light enters the eye and hits the retina, which lines the back of the eyeball. Neurons in the retina convert light into nerve signals which are then sent to the brain. Using retinas isolated from mice, Dr. Alon Poleg-Polsky, Ph.D. a postdoctoral fellow in Dr. Diamond’s lab, studied neurons called directionally selective retinal ganglion cells (DSGCs), which are known to fire and send signals to the brain in response to objects moving in specific directions across the eye.

Electrical recordings showed that some of these cells fired when a bar of light passed across the retina from left to right, whereas others responded to light crossing in the opposite direction. Previous studies suggested these unique responses are controlled by incoming signals sent from neighboring cells at chemical communication points called synapses. In this study, Dr. Poleg-Polsky discovered that the activity of NMDA receptors at one set of synapses may regulate whether DSGCs sent direction-sensitive information to the brain.

NMDA receptors are proteins that generate electrical signals in response to the neurochemicals glutamate and glycine. When activated, they allow electrically charged ions to flow in and out of cells like water through an unlocked canal. In the early 1980s, studies in France and at the NIH showed that magnesium blocks the flow until the neuron is strongly activated and its electrical state rises above a certain voltage. This regulation is thought to be critical for certain types of learning and memory, and in amplifying signals in neurons.

Further experiments by Dr. Poleg-Polsky examined how magnesium’s control of NMDA receptors may regulate the firing of DSGCs. To mimic realistic conditions, Dr. Poleg-Polsky passed bars of light across retinas while exposing them to various background lights. The results suggested that the variable magnesium block that ensured the cells consistently sent information to the brain in response to the passing bars of light despite the distracting incoming stream of signals generated by the background lights. The NMDA receptors did this by amplifying the cells’ responses to the bars in a process called multiplicative scaling.

“Cells in the eye can multiply,” said Dr. Poleg-Polsky. “The process may help these cells determine whether a tiger is sauntering by, or fast approaching as it’s looking for dinner.”

Neurons in the eye and brain receive a constant stream of information. The results of this study support a growing body of evidence suggesting that NMDA receptors play in critical role in how neurons relay information.

“Our results suggest that NMDA receptors help neurons distinguish relevant information from irrelevant background noise,” said Dr. Diamond. “In the future we plan to examine whether this process contributes to other aspects of vision.”

March is Workplace Eye Wellness Month

0 comments

Posted on 11th March 2016 by Pacific ClearVision Institute in General |Retina

March is Workplace Eye Wellness Month. Along with many other eye care providers across the nation, as well as the American Academy of Ophthalmology, PCVI in Eugene is promoting good eye health in the work place.

Safety Eyewear: A Critical Component

One of the most obvious and effective ways to reduce workplace eye injuries is to wear proper safety glasses. It is estimated that 90% of workplace eye injuries could be avoided if safety eyewear is used effectively.

Safety eyewear varies depending upon the type of work being done. The general rule is that anyone passing through a work site use safety eyewear to avoid injuries caused by flying objects, tools, particles and other hazards. The Occupational Safety and Health Administration (OSHA) requires employers to ensure workers have suitable eye protection.

Avoid Infection Risks

Certain fields of work carry the risk of eye infection. Workers in health care, laboratory, janitorial or animal handling environments need to consider special eye protection to reduce the risk of exposure to both minor and major illnesses via the eye.

Office and Computer Users Are Not Immune

Do you work on a computer, laptop, or other digital device? With more and more workers using technology and gadgets as part of their daily work routine, the risk for eye strain and its effects also continues to rise. Increasing use of digital devices may expose workers to eye strain from long, uninterrupted focus on video screens.

Workers can even suffer from computer vision syndrome. Computer vision syndrome is a group of eye and vision-related problems that result from prolonged computer use. Computer vision syndrome symptoms can range from physical fatigue to eye twitching. If you think you are suffering from symptoms of computer vision syndrome, it is important to see your eye doctor. An eye doctor can recommend the best personalized treatment for you.

However, if you work on electronic devices all day, there are things that you can do to prevent computer vision syndrome. Here are some tips that you can use:

See An Eye Doctor: The first step to preventing computer vision syndrome is seeing your eye doctor for an eye exam. It is a great way to keep tabs on your eye health. Tell your eye doctor if you are a heavy user of electronic devices during your daily routine.

Get to Know the 20/20/20 Rule: If you work on a computer at your desk, take a 20 second break every 20 minutes and shift your vision to something else 20 feet away.

Make Sure to Blink: When you work at a computer or on other electronic devices, you are less likely to blink. However, you need to blink because it keeps your eyes moist and prevents dry eye. So remember to blink when you are working at your computer.

Take Mini Breaks: Most people only take two 15 minute breaks throughout the work day, but if you take shorter more frequent breaks from working on your computer, it will be a lot easier on your eyes. Make sure to get up, stretch, and move around during your breaks so that your eyes get a chance to rest.

Computer Eyewear Is An Option: Your eye doctor may be able to prescribe computer eyewear that can help alleviate eye strain if you are heavy electronics user.