All posts by Toni Baker

Unusual alliances enable movement

Augusta, Ga. – Some unusual alliances are necessary for you to wiggle your fingers, researchers report.

Dr. Lin Mei, Director of the Institute of Molecular Medicine and Genetics at Georgia Health Sciences University

Understanding those relationships should enable better treatment of neuromuscular diseases, such as myasthenia gravis, which prevent muscles from taking orders from your brain, said Dr. Lin Mei, Director of the Institute of Molecular Medicine and Genetics at Georgia Health Sciences University.

During development, neurons in the spinal cord reach out to muscle fibers to form a direct line of communication called the neuromuscular junction. Once complete, motor neurons send chemical messengers, called acetylcholine, via that junction so you can text, walk or breathe.

As a first step in laying down the junction, motor neurons release the protein agrin, which reaches out to LRP4, a protein on the muscle cell surface. This activates MuSK, an enzyme that supports the clustering of receptors on the muscle cell surface that will enable communication between the brain and muscle. The precise alignment between the neuron and muscle cell that occurs during development ensures there is no confusion about what the brain is telling the muscle to do.

A missing piece was how agrin and LRP4 get together.

A study published in the journal Genes & Development shows that in the space between the neuron and its muscle cell, agrin and LRP4 first form two diverse work teams: each team has one agrin and one LRP4. The two teams then merge to form a four-molecule complex essential to MuSK activation and to the clustering of receptors that will receive the chemical messenger acetylcholine on the muscle cell.

It was expected that the two agrins would get together first then prompt the LRP4s to merge. “This is very novel,” said Mei, and an important finding in efforts to intervene in diseases that attack the neuromuscular junction.

Mei and Dr. Rongsheng Jin, neuroscientist and structural biologist in the Del E. Webb Neuroscience, Aging and Stem Cell Research Center at Sanford-Burnham Medical Research Institute in La Jolla, Calif., are co-corresponding authors of the study.

Myasthenia gravis, which paralyzes previously healthy individuals, targets these protein workers. The condition, which can run in families, likely results from a process called mimicry in which the immune system starts making antibodies to the workers, which it confuses with a previous viral or bacterial infection. The majority of patients have antibodies to acetylcholine receptors and a smaller percentage have antibodies to MuSK. Most recently, GHSU researchers also helped identify LRP4 as an antibody target.

The scientists already are looking at the impact of the antibodies on the LRP4 complex. Understanding its unique structure is essential to designing drugs that could one day block such attacks. “Prior to this we had no idea how they interacted,” Mei said.

In addition to providing new information on muscle diseases, this study might also have a far-reaching ripple effect in the field of neuroscience.

“This is just the beginning,” says Jin. “Now that we know more about how signals are transferred during the formation of neuromuscular junctions, we can start looking at how a similar system might work in brain synapses and how it malfunctions in neurodegenerative conditions like Alzheimer’s and Parkinson’s diseases. If we can figure out how to trigger the formation of new brain synapses, maintain old synapses, or simply slow their disappearance, we’d be much better equipped to prevent or treat these diseases.”

To reveal the novel mechanism, researchers used a technique known as X-ray crystallography, which produces 3-D “pictures” of protein at the atomic level using powerful X-ray beams.

Jin is the recipient of the Alfred P. Sloan Research Fellowship and the Human Frontier Science Program Young Investigator research grant. Mei is a Georgia Research Alliance Eminent Scholar in Neuroscience. Collaborators include Dr. Kay Perry in the Department of Chemistry and Chemical Biology at Cornell University’s and the U.S. Department of Energy’s Argonne National Laboratory.

###

About Georgia Health Sciences University

Georgia Health Sciences University is the state’s public academic health center. The enterprise includes the Medical College of Georgia and the Colleges of Allied Health Sciences, Dental Medicine, Graduate Studies and Nursing as well as Georgia Health Sciences Medical Center and Georgia Health Sciences Children’s Medical Center. GHSU is a unit of the University System of Georgia and an equal opportunity institution. For more information, visit http://www.georgiahealth.edu.

 About Sanford-Burnham Medical Research Institute

Sanford-Burnham Medical Research Institute is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. The Institute consistently ranks among the top five organizations worldwide for its scientific impact in the fields of biology and biochemistry (defined by citations per publication) and currently ranks third in the nation in NIH funding among all laboratory-based research institutes. Sanford-Burnham is a highly innovative organization, currently ranking second nationally among all organizations in capital efficiency of generating patents, defined by the number of patents issued per grant dollars awarded, according to government statistics.

Sanford-Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Sanford-Burnham is a U.S.-based, non-profit public benefit corporation, with operations in San Diego (La Jolla), Santa Barbara, and Orlando (Lake Nona). For more information, please visit our website (www.sanfordburnham.org) or blog (http://beaker.sanfordburnham.org). You can also receive updates by following us on Facebook and Twitter.

Animal research model using zebrafish may help speed drug discovery

Tiny zebrafish just may give scientists one solution to information overload in the search for new drug therapies.

High-throughput screening uses robotics and computers to rapidly screen drugs, genes or proteins, to identify, for example, compounds that are best at destroying cancer or restoring insulin-producing cells. The technology has both revolutionized and stymied research, said Dr. Jeffrey Mumm, biologist in the Medical College of Georgia at Georgia Health Sciences University.

While the decade-old technology can screen 100,000 compounds in a day, there is no efficient next step for whittling to a manageable number the resulting, say, 2,500 compounds that on first blush appear to have potential. Consequently, drug discovery has actually stalled, creating a scientific “indigestion,” Mumm said. Drug failure rates and discovery costs, on the other hand, have escalated.

“The next best thing to do is probably take all the compounds and put them into an animal model that mimics the disease you are trying to cure but nobody has that kind of budget or would know where to start with that number of candidates,” Mumm said.

One solution is pairing zebrafish with reporter-based assays that make certain parts glow, according to Mumm’s research published in the journal PLoS ONE. He calls it Automated Reporter Quantification.

“It’s a way to cut to the chase rather than having to make educated guess about which of the 2,500 compounds are really of interest,” said Mumm. Zebrafish, which start out as single cell organisms that are fully functioning by day four, already are an invaluable research model for a wide variety of diseases, such as Mumm’s efforts to regenerate cells in the face of degenerative diseases of the eyes or pancreas.

To produce a model of type 1 diabetes, for example, he uses a single drug to destroy insulin-producing cells; 24 hours later, he knows those cells are gone because the glow is gone in the transparent zebrafish.

Now, he can leave the fish in the well plates, which look like plastic ice trays with cubes about the size of pencil tops and come in multiples of 96. The individual wells enable him to quickly reassess the impact of the thousands of compounds identified by high-throughput screening in a living specimen. Simply put: Does the glow come back?

The next step becomes logical and doable: study the 20 or so compounds that continued to show promise in a mouse model. These steps to the fish then mouse, called biological validation, have been a real bottleneck in science post high-throughput screening, Mumm said. “This is going to give you much more thorough information about how compounds affect the overall physiology of a living being,” Mumm said.

He noted that reporter-based assays number in the thousands so what they can help find is essentially limited only by the imagination.

He’s used one to monitor a major signaling pathway that consistently shows up in cancer.

“We hooked the pathway up to a reporter that told us whether it was on or off, then tested whether we could modulate it over time and, sure enough, it was very easy to do,” Mumm said. “Name the cancer and basically you have WNT activated so there is a huge effort in cancer therapeutics to try and essentially shut it down.”

Mumm’s Automated Reporter Quantification system, which uses microplate readers developed by the life sciences supply company Tecan, placed second in the inaugural Tecan Detection Award.

Mumm also is a faculty member in GHSU’s College of Graduate Studies.

Adolescents’ fructose consumption may put them at cardiovascular risk

Evidence of cardiovascular disease and diabetes risk is present in the blood of adolescents who consume a lot of fructose, a scenario that worsens in the face of excess belly fat, researchers report.

An analysis of 559 adolescents age 14-18 correlated high-fructose diets with higher blood pressure, fasting glucose, insulin resistance and inflammatory factors that contribute to heart and vascular disease.

Heavy consumers of the mega-sweetener also tend to have lower levels of cardiovascular protectors such as such as HDL cholesterol and adiponectin, according to researchers at the Medical College of Georgia at Georgia Health Sciences University.

These dangerous trends are exacerbated by fat around their midsection, called visceral adiposity, another known risk factor for cardiovascular disease and diabetes. The association did not hold up for adolescents with more generalized, subcutaneous fat.

“It is so very important to provide a healthy balance of high-quality food to our children and to really pay close attention to the fructose and sucrose they are consuming at their home or anyone else’s,” said Dr. Vanessa Bundy, an MCG pediatric resident. Drs. Bundy and Norman Pollock, bone biologist at MCG’s Georgia Prevention Institute, are co-first authors on the study published in The Journal of Nutrition.

“The nutrition that caregivers provide their children will either contribute to their overall health and development or potentially contribute to cardiovascular disease at an early age,” Bundy said. The best way caregivers can support healthy nutrition is to be good role models, she said. A healthy diet with plenty of physical activity – not dieting – is the best prescription for growing children.

“Adolescents consume the most fructose so it’s really important to not only measure the levels of fructose but to look at what it might be doing to their bodies currently and, hopefully, to look at cardiovascular disease outcomes as they grow,” Pollock said.

While animal studies have had similar findings, evidence in children is needed to support dramatic steps to curb consumption, such as asking schools to remove soda and other vending machines or, at least, to limit access, Pollock said. The researchers noted that more study is needed to flesh out the relationship between high fructose consumption and cardiovascular risk and whether these early associations forebode adult disease.

Fructose, or fruit sugar, is found in fruits and veggies but also in high fructose corn syrup, the sweetener used liberally in processed foods and beverages. Researchers suspect growing bodies crave the cheap, strong sweetener and companies often target young consumers in ads.

“Fructose itself is metabolized differently than other sugars and has some byproducts that are believed to be bad for us,” Bundy said. “The overall amount of fructose that is in high fructose corn syrup is not much different than the amount in table sugar but it’s believed there’s something in the syrup processing that plays a role in the bad byproducts of metabolism.”

The study took a “snapshot” of the adolescents’ lives, looking at overall fructose consumption, general diet history and body fat.

“A unique aspect of our study design is that we took into account the fructose released from sucrose during digestion along with the fructose found in foods and beverages,” Pollock said. “Because sucrose is broken down into fructose and glucose before it arrives at the liver for metabolism, it is important to consider the additional fructose from sucrose when determining the overall health effect of fructose.”

Stimulation of brain hormone action may improve pneumonia survival

(from left) Dr. Supriya Sridhar, Dr. Rudolf Lucas and Aluya Oseghale

Augusta, Ga. – An international research team may have found a way to block a second wave of death that can result from pneumonia treatment.

Antibiotics are effective at killing pneumococcus – the cause of about 50 percent of pneumonias – but as it dies the bacterium releases potentially lethal toxins.

Adding an agonist that mimics the action of growth hormone-releasing hormone – which ultimately enables growth – may stop that second wave, according to research published in the Proceedings of the National Academy of Sciences.

“You have to take antibiotics, if you don’t, the bugs will grow and you most likely will die anyway,” said Dr. Rudolf Lucas, vascular biologist at the Medical College of Georgia at Georgia Health Sciences University.

Problems start when a bacterium that causes pneumonia, in this case pneumococcus, is inhaled. Symptoms include mucus buildup, cough, fever, chills and shortness of breath. Antibiotics are the front line treatment to kill the infection.

An unfortunate result of bacterium death is release of pneumolysin, a toxin that can trigger formation of holes in the walls of the millions of tiny air sacs and blood vessels in the lungs. The result is that fluid, blood and other products find their way into air sacs that were intended for oxygen exchange.

Schally, a Nobel Prize recipient for his discovery of hypothalamic hormones and Head of The Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center in Miami, developed the agonist that may one day make the difference for these patients.

“It’s like making a hole in a bucket,” said Lucas. He and Dr. Andrew V. Schally, Distinguished Leonard M. Miller Professor of Pathology & Professor of Hematology/Oncology at the University of Miami Miller School of Medicine, are co-corresponding authors on the study.

Pneumolysin naturally binds to cholesterol, a component of all cell membranes including cells lining the air sacs, or alveoli. Once attached to the membrane, the toxin produces complexes that make holes in the membranes of the air sacs before escaping to do similar damage to nearby capillaries. While the close proximity of capillaries normally enables air sacs to replenish blood with oxygen and to remove carbon dioxide, the now open exchange enables fluid and cells from the capillaries to penetrate air sacs as well as the space in between them. To make matters worse, the toxin also blocks a protective sodium uptake system in the lungs that can help remove fluids. Within a few days, the patient is back in jeopardy. “These patients are being treated with an antibiotic and aggressive intensive care support and they (can) still die,” Lucas said.

Schally, a Nobel Prize recipient for his discovery of hypothalamic hormones and Head of The Endocrine, Polypeptide and Cancer Institute, Veterans Affairs Medical Center in Miami, developed the agonist that may one day make the difference for these patients. The agonist was previously shown to help protect heart muscle in the aftermath of a heart attack.

Surprisingly, GHSU scientists detected receptors for growth hormone releasing hormone in cells lining the air sacs. Typically, growth hormone-releasing hormone is produced by the hypothalamus then goes to the pituitary which makes and releases growth hormone. “We were asking ourselves, what is it doing there?” Lucas said.

They got a clue when they applied the agonist to the growth hormone-releasing hormone in an animal model of pneumonia as well as human lung cells in culture: leaking was significantly reduced and beneficial sodium uptake was restored. Conversely, when they applied a hormone antagonist – to block its action – lung cells became leaky even without toxin exposure, further indicating the hormone’s apparent role in protecting the lining of the air sacs and capillaries.

“This is an acute problem; dangerous lung fluid accumulation occurs within days in patients,” said Lucas who anticipates the agonist, or a compound with a similar function, could someday be given to patients in those first few critical days to avoid the second onslaught.

As a result of the findings, extensive collaborative studies are being planned on the use of growth hormone-releasing hormone agonists to prevent edema in patients with bacterial pneumonia. Next steps include pursing a National Institutes of Health grant with Dr. Michael A. Matthay, Senior Associate, Cardiovascular Research Institute, University of California, San Francisco, to support more studies that include an isolated human lung model and a preclinical model of laboratory animals who follow the same course as patients: they are infected with the bacterium then given an antibiotic. In the model for the PNAS study, scientists gave the resulting toxin directly.

Dr. Trinad Chakraborty, Dean of the Faculty of Medicine at the University of Giessen in Germany, developed the purified toxin used for the study. Study co-authors Dr. Richard White, GHSU pharmacologist, showed restoration of sodium uptake, and Dr. Supriya Sridhar, GHSU research associate, performed the cell permeability experiments. University of Miami co-authors included Dr. Norman L. Block, Professor of Pathology, Urology, Oncology and Biomedical Engineering, as well as Dr. Ferenc G. Rick, Assistant Research Professor of Pathology.

###

Georgia Bio honors biotech company that enables stroke care

Augusta, Ga. – It was a “common sense” decision to start the company in a large, mostly rural state in the middle of the stroke belt.

“We wanted to give better stroke care,” said Dr. David Hess, stroke specialist and Chairman of the Department of Neurology at the Medical College of Georgia at Georgia Health Sciences University. It was the year 2000 and Hess and his colleagues were frustrated that nearly five years after the first stroke medication was approved by the Food and Drug Administration, patients were arriving at Georgia Health Sciences Medical Center too late to get the clot-busting drug that could reduce their stroke damage.

“We had customers before we had a company,” said Hess, a founder and Chairman of the Board of REACH Health, Inc., the six-year-old company that packaged the need for rapid stroke care with the emerging capabilities of the Internet to provide that care remotely.

The company received a 2012 Georgia Bio Community Award Jan. 26 for its significant contributions to Georgia’s life sciences industry. Georgia Bio is a private, non-profit representing universities, medical centers, companies and others involved in developing products that improve the health and well-being of people, animals and the environment.

The first iteration of the system was assembled at MCG: a security camera on an intravenous pole that rolled alongside a computer on a cart. In late 2011, REACH rolled out its fourth iteration: a professionally assembled, sleek system that enables immediate access to a wider range of care, such as critical or cardiac care.

“Anywhere we have time-critical situations or a severe shortage of specialists, the REACH system can perform,” said Richard E. Otto, the company’s Chief Executive Officer. REACH has offices in Alpharetta, Ga., a center for health care information technology, as well as the Georgia Medical Center Authority in Augusta, a statewide authority to advance the life sciences. The system, which works on a hub and spoke model, operates in more than 100 hospitals in a growing number of states that include Alaska, New York, Ohio, South Carolina and Louisiana.

“Today it’s a uniform platform with multiple applications,” Hess said. “That is what our customers want.”

Part of REACH’s success is what Hess calls its “secret sauce,” which enables an interactive consultation between the stroke specialist and referring physician. “They put in data, we put in data, so in the end we produce a consult they can follow with guidelines, for example, on how to give tPA,” Hess said, referencing the only FDA-approved stroke drug. Quick administration is necessary to maximize the drug’s effectiveness and, even after all these years, less than 5 percent of patients get it. That disconnect is the primary reason development of a remote care system was common sense, Hess said. “It’s an immediate, collaborative consultation in the cloud.”

“It’s never going to take the place of a physician and a patient sitting across from each other but that is not always possible,” Otto added. In fact, with fewer than four stroke specialists for every 100,000 people, it’s highly unlikely for stroke care.

“Efficiencies in medicine are driving decisions in medicine,” Otto said. No doubt the REACH system increases the efficiency of stroke specialists by making distance from the patient irrelevant, he said. That’s particularly cogent in an aging population with too few doctors.

REACH targets academic health centers, which tend to attract stroke specialists, as the logical starting point for developing the hub-and-spoke model that makes the system an efficient, effective tool on both ends of the patient consultation, Hess said. Georgia Health Sciences Medical Center, the original hub, now connects with 17 smaller hospitals across Georgia.

The latest REACH system is being tested at St. Joseph’s/Candler in Savannah, the hub for eight hospitals in surrounding communities. The health system is still looking at the spectrum of specialties it will roll out with the system’s expanded capabilities. St. Joseph’s/Candler Stroke NET-work became operational in May 2009.

“St. Joseph’s/Candler is committed to finding technology to help patients get treated quickly and recover faster,” said Paul P. Hinchey, President & CEO of St. Joseph’s/Candler. “We’ve had such a good experience with REACH that upgrading to the 4.0 platform was an easy decision. It will allow patients in our region fast and easy access to our expert specialists.”

GHSU researchers showed in a study published in 2003 in Stroke: Journal of the American Heart Association that stroke patients in rural communities could be assessed and treated via the wireless Internet program just as well as they could be in person.

 

High fructose consumption by adolescents may put them at cardiovascular risk

AUGUSTA, Ga. – Evidence of cardiovascular disease and diabetes risk is present in the blood of adolescents who consume a lot of fructose, a scenario that worsens in the face of excess belly fat, researchers report.

An analysis of 559 adolescents age 14-18 correlated high-fructose diets with higher blood pressure, fasting glucose, insulin resistance and inflammatory factors that contribute to heart and vascular disease.

Heavy consumers of the mega-sweetener also tend to have lower levels of cardiovascular protectors such as such as HDL cholesterol and adiponectin, according to researchers at the Medical College of Georgia at Georgia Health Sciences University.

These dangerous trends are exacerbated by fat around their midsection, called visceral adiposity, another known risk factor for cardiovascular disease and diabetes. The association did not hold up for adolescents with more generalized, subcutaneous fat.

“It is so very important to provide a healthy balance of high-quality food to our children and to really pay close attention to the fructose and sucrose they are consuming at their home or anyone else’s,” said Dr. Vanessa Bundy, an MCG pediatric resident. Drs. Bundy and Norman Pollock, bone biologist at MCG’s Georgia Prevention Institute are co-first authors on the study published in The Journal of Nutrition.

“The nutrition that caregivers provide their children will either contribute to their overall health and development or potentially contribute to cardiovascular disease at an early age,” Bundy said. The best way caregivers can support healthy nutrition is to be good role models, she said. A healthy diet with plenty of physical activity – not dieting – is the best prescription for growing children.

“Adolescents consume the most fructose so it’s really important to not only measure the levels of fructose but to look at what it might be doing to their bodies currently and, hopefully, to look at cardiovascular disease outcomes as they grow,” Pollock said.

While animal studies have had similar findings, evidence in children is needed to support dramatic steps to curb consumption, such as asking schools to remove soda and other vending machines or, at least, to limit access, Pollock said. The researchers noted that more study is needed to flesh out the relationship between high fructose consumption and cardiovascular risk and whether these early associations forebode adult disease.

Fructose, or fruit sugar, is found in fruits and veggies but also in high fructose corn syrup, the sweetener used liberally in processed foods and beverages. Researchers suspect growing bodies crave the cheap, strong sweetener and companies often target young consumers in ads.

“Fructose itself is metabolized differently than other sugars and has some byproducts that are believed to be bad for us,” Bundy said. “The overall amount of fructose that is in high fructose corn syrup is not much different than the amount in table sugar but it’s believed there’s something in the syrup processing that plays a role in the bad byproducts of metabolism.”

The study took a “snapshot” of the adolescents’ lives, looking at overall fructose consumption, general diet history and body fat.

“A unique aspect of our study design is that we took into account the fructose released from sucrose during digestion along with the fructose found in foods and beverages,” Pollock said. “Because sucrose is broken down into fructose and glucose before it arrives at the liver for metabolism, it is important to consider the additional fructose from sucrose when determining the overall health effect of fructose.”

 

###

Emergency medicine physicians develop device to stop lethal bleeding in soldiers

Two emergency medicine physicians with wartime experience have developed a weapon against one rapidly lethal war injury.

Insurgents commonly aim just below a soldier’s body armor, where the trunk and legs join, to injure the body’s largest blood vessels, causing soldiers to bleed to death within minutes.

“There is no way to put a tourniquet around it, so soldiers are getting shot in this area and dying within several minutes,” said Dr. Richard Schwartz, Chairman of the Department of Emergency Medicine in the Medical College of Georgia at Georgia Health Sciences University. Police officers wearing chest protection as well as automobile accident victims can sustain similar injuries.

Efforts to externally compress the injury have been largely ineffective; the inch-round aorta runs parallel to the spine, so it can’t be approached from the back, and is several inches inside the abdomen even in a fit soldier.

Schwartz and Dr. John Croushorn, Chairman of the Department of Emergency Medicine at Trinity Medical Center in Birmingham, Ala., hope their inflatable wedge-shaped bladder will make a lifesaving difference.

It’s called an abdominal aortic tourniquet and it’s placed around the body at the navel level, tightened then, much like a blood pressure cuff, inflated into the abdomen until it occludes the aorta and stops the bleeding. The goal is to restore the golden hour so soldiers survive long enough to get definitive care for their injury.

“By effectively cross-clamping the aorta with the abdominal aortic tourniquet, you are essentially turning the faucet off,” Croushorn said.  “You are stopping the loss of blood from the broken and damaged blood vessels. You are buying the patient an additional hour of survival time based on blood loss.”

It was known that the knee pressed into the mid-abdomen could slow bleeding and block blood flow to the legs. The idea for the device came from studies conducted at GHSU in 2006 that quantified pressure needed to occlude the abdominal aorta. Schwartz and Croushorn started talking about turning that concept into a lifesaving device at an American College of Emergency Physicians meeting.

They first put the device on pigs, inflated it to the point there was no blood flow from the aorta to the femoral arteries and left it that way for an hour. There saw no potentially deadly increase in potassium levels in the blood and the pigs’ leg and gut tissue remained healthy. Next they used it on healthy humans for a shorter duration to ensure that the aorta could be completed occluded.

Croushorn and Schwartz have premarket clearance for the abdominal aortic tourniquet from the Food and Drug Administration and have identified a manufacturer. They already have orders for the device from the U.S. military and will teach courses on how to use it to the military and law enforcement. Device development was funded by the U.S. Department of Defense.

The physicians still want to explore their device’s potential for also helping CPR recipients. The chest compression that is the hallmark of CPR actually pushes blood all the way out to the extremities when the focus is keeping vital organs alive.

“With this device, you could, in theory, double the blood flow to the kidneys, heart and brain,” Schwartz said. They also believe it will help concentrate drugs given during CPR where they are needed. “Now when a medic pushes a cardiac drug during cardiac arrest, the drug is circulated through the toes before it reaches steady state concentrations in the heart,” Croushorn said.

Schwartz was a member of the 5th Special Forces Group (Airborne) during Operation Desert Shield and Desert Storm. He works with the Federal and Georgia Bureaus of Investigation and helped develop courses that bridge the gap between military and civilian groups that may work together during major disasters. Croushorn served as Command Surgeon, Task Force 185 Aviation in the U.S. Army in Iraq in 2004. He also works with the FBI.

Zebrafish may help speed drug discovery

Dr. Jeffrey Mumm, biologist in the School of Medicine at Georgia Health Sciences University

AUGUSTA, Ga. – Tiny zebrafish just may give scientists one solution to information overload in the search for new drugs therapies.

High throughput screening uses robotics and computers to rapidly screen drugs, genes or proteins, to identify, for example, compounds that are best at destroying cancer or restoring insulin-producing cells. The technology has both revolutionized and stymied research, said Dr. Jeffrey Mumm, biologist in the Medical College of Georgia at Georgia Health Sciences University.

While the decade-old technology can screen 100,000 compounds in a day, there is no efficient next step for whittling to a manageable number the resulting say, 2,500 compounds that on first blush appear to have potential. Consequently, drug discovery has actually stalled, creating a scientific “indigestion,” Mumm said. Drug failure rates and discovery costs, on the other hand, have escalated.

“The next best thing to do is probably take all the compounds and put them into an animal model that mimics the disease you are trying to cure but nobody has that kind of budget or would know where to start with that number of candidates,” Mumm said.

One solution is pairing zebrafish with reporter-based assays that make certain parts glow, according to Mumm’s research published in the journal PLoS ONE. He calls it Automated Reporter Quantification.

“It’s a way to cut to the chase rather than having to make educated guess about which of the 2,500 compounds are really of interest,” said Mumm. Zebrafish, which start out as single cell organisms that are fully functioning by day four, already are an invaluable research model for a wide variety of diseases, such as Mumm’s efforts to regenerate cells in the face of degenerative diseases of the eyes or pancreas.

To produce a model of type 1 diabetes, for example, he uses a single drug to destroy insulin-producing cells; 24 hours later, he knows those cells are gone because the glow is gone in the transparent zebrafish.

Now, he can leave the fish in the well plates, which look like plastic ice trays with cubes about the size of pencil tops and come in multiples of 96. The individual wells enable him to quickly reassess the impact of the thousands of compounds identified by high-throughput screening in a living specimen. Simply put: Does the glow come back? The next step becomes logical and doable: study the 20 or so compounds that continued to show promise in a mouse model. These steps to the fish then mouse, called biological validation, have been a real bottleneck in science post high-throughput screening, Mumm said. “This is going to give you much more thorough information about how compounds affect the overall physiology of a living being,” Mumm said.

He noted that reporter-based assays number in the thousands so what they can help find is essentially limited only by the imagination.                                                                                                                                                                                                                                                                                      He’s used one to monitor a major signaling pathway that consistently shows up in cancer. “We hooked the pathway up to a reporter that told us whether it was on or off, then tested whether we could modulate it over time and, sure enough, it was very easy to do,” Mumm said. “Name the cancer and basically you have WNT activated so there is a huge effort in cancer therapeutics to try and essentially shut it down.”

Mumm’s Automated Reporter Quantification system, which uses microplate readers developed by the life sciences supply company Tecan, placed second in the inaugural Tecan Detection Award.

Mumm also is a faculty member in GHSU’s College of Graduate Studies.

###

Emergency medicine physicians develop device to stop lethal bleeding in soldiers

AUGUSTA, Ga. – Two emergency medicine physicians with wartime experience have developed a weapon against one rapidly lethal war injury.

Insurgents commonly aim just below a soldier’s body armor, where the trunk and legs join, to injure the body’s largest blood vessels, causing soldiers to bleed to death within minutes.

“There is no way to put a tourniquet around it, so soldiers are getting shot in this area and dying within several minutes,” said Dr. Richard Schwartz, Chairman of the Department of Emergency Medicine in the Medical College of Georgia at Georgia Health Sciences University. Police officers wearing chest protection as well as automobile accident victims can sustain similar injuries.
Efforts to externally compress the injury have been largely ineffective; the inch-round aorta runs parallel to the spine, so it can’t be approached from the back, and is several inches inside the abdomen even in a fit soldier.

Schwartz and Dr. John Croushorn, Chairman of the Department of Emergency Medicine at Trinity Medical Center in Birmingham, Ala., hope their inflatable wedge-shaped bladder will make a lifesaving difference.

Abdominal Aortic Tourniquet

 

It’s called an abdominal aortic tourniquet and it’s placed around the body at the navel level, tightened then, much like a blood pressure cuff, inflated into the abdomen until it occludes the aorta and stops the bleeding. The goal is to restore the golden hour so soldiers survive long enough to get definitive care for their injury.

“By effectively cross-clamping the aorta with the abdominal aortic tourniquet, you are essentially turning the faucet off,” Croushorn said.  “You are stopping the loss of blood from the broken and damaged blood vessels. You are buying the patient an additional hour of survival time based on blood loss.”

It was known that the knee pressed into the mid-abdomen could slow bleeding and block blood flow to the legs. The idea for the device came from studies conducted at GHSU in 2006 that quantified pressure needed to occlude the abdominal aorta. Schwartz and Croushorn started talking about turning that concept into a lifesaving device at an American College of Emergency Physicians meeting.

They first put the device on pigs, inflated it to the point there was no blood flow from the aorta to the femoral arteries and left it that way for an hour. There saw no potentially deadly increase in potassium levels in the blood and the pigs’ leg and gut tissue remained healthy. Next they used it on healthy humans for a shorter duration to ensure that the aorta could be completed occluded.

Croushorn and Schwartz have premarket clearance for the abdominal aortic tourniquet from the Food and Drug Administration and have identified a manufacturer. They already have orders for the device from the U.S. military and will teach courses on how to use it to the military and law enforcement. Device development was funded by the U.S. Department of Defense.

The physicians still want to explore their device’s potential for also helping CPR recipients. The chest compression that is the hallmark of CPR actually pushes blood all the way out to the extremities when the focus is keeping vital organs alive.

“With this device, you could, in theory, double the blood flow to the kidneys, heart and brain,” Schwartz said. They also believe it will help concentrate drugs given during CPR where they are needed. “Now when a medic pushes a cardiac drug during cardiac arrest, the drug is circulated through the toes before it reaches steady state concentrations in the heart,” Croushorn said.

Schwartz was a member of the 5th Special Forces Group (Airborne) during Operation Desert Shield and Desert Storm. He works with the Federal and Georgia Bureaus of Investigation and helped develop courses that bridge the gap between military and civilian groups that may work together during major disasters.  Croushorn served as Command Surgeon, Task Force 185 Aviation in the U.S. Army in Iraq in 2004. He also works with the FBI.

Related Link: GHS Physician’s Invention Receives Popular Science Award

Smaller sibling protein calls the shots in cell division

AUGUSTA, Ga. – Scientists have found at least one instance when the smaller sibling gets to call the shots and cancer patients may one day benefit.

The protein Chk1 has long been known to be a checkpoint in cell development: it keeps normal cells and damaged cells from dividing until their DNA has been fully replicated or repaired. Now scientists at Georgia Health Sciences University and the California Institute of Technology have discovered a shorter form they’ve dubbed Chk1-S (“S” stands for short) that essentially neutralizes its longer sibling so cell division can proceed.

That shorter form is in higher levels in cancer cells as well as fetal tissue, both of which require accelerated cell division. But the scientists also have shown that very high levels of Chk1-S actually reduce tumor growth and prompt premature cell division and death in other cells.

“Chk1 is needed for division of all cells, even cancer cells, so if you inhibit it completely by over-expressing Chk1-S, those cells also will not grow,” said Dr. Navjotsingh Pabla, a postdoctoral fellow at Caltech. Chk1-S expression is nearly zero in normal, non-dividing cells.

These findings, published in Proceedings of the National Academy of Sciences, point toward the short form’s potential to help diagnose and/or treat cancer, they said. Chk1 inhibitors, which promote abnormal cell division – and likely cell death – to occur before DNA replication/repair is complete, already are being tested on patients.

“Chk1-S is only expressed at a time when DNA is replicated or repaired so it binds to its sibling protein, Chk1, antagonizing it so now the cell can divide,” said Dr. Zheng Dong, cell biologist at GHSU and the Charlie Norwood Veterans Affairs Medical Center in Augusta. “The question that has been hanging on for many years is: How is Chk1 regulated?”

They found that significantly increasing levels of Chk1-S induces cell division regardless of whether DNA replication or repair is complete. Incomplete DNA replication or repair can result in spontaneous cell suicide but also can result in chromosomal or genetic defects leading to cancer cell production. Additionally, cancer cells purposefully mutate to resist treatment. Pabla speculates that expression of the shorter version may be awry in cancer cells. “We are very interested in pursuing that.”

“It’s exciting to have found an important regulator of such an important protein that we think may contribute to cancer as well as its treatment,” Dong said.

Chk1 and Chk1-S are made by the same gene they are just spliced differently. One way Chk1 gets turned on is by phosphorylation, or adding phosphate, which can activate or deactivate a protein. The level of phosphorylation of Chk1 is particularly dramatic when DNA repair is needed. Chk1, in turn, works to temporarily halt the cell cycle by phosphorylating another protein. Interestingly, Chk1-S cannot bind to its sibling when Chk1 is phosphorylated. It’s known that mental retardation can result from mutation of ATR, a DNA damage-sensing protein that phosphorylates Chk1.

While the biggest burst of cell division occurs during development, it continues lifelong in areas such as the blood, skin and gastrointestinal tract where cell turnover is high. “Lots of tissues need to regenerate,” said Dong.

Dong is a Regents Professor at GHSU and a faculty member in the university’s Medical College of Georgia and College of Graduate Studies. He is a Research Career Scientist and Director of Research Development at the Charlie Norwood VA Medical Center. Pabla worked at GHSU with Dong on the study.

###