Category Archives: Guest Post

Mice and the Mycobiome: How Animal Models Will Help Us Understand the Microbial World In Our Gut

Rebecca Drummond, PhD, is a post-doctoral scientist working at the National Institutes of Health, USA. Dr Drummond’s research aims to understand why some people get fungal infections and others do not. To do this she must understand how the immune system prevents fungal infections and the risk factors that make an infection more likely. In this blog, Rebecca explains how mice can help us to understand how bacteria and fungi can affect the immune system and development of gut-related disorders, like irritable bowel disease (IBD).

Our intestines are home to billions of microbes, which help digest food and maintain a healthy immune system. These microbes, known as the ‘microbiome’, are a mixture of bacteria, fungi and viruses, and individual species can have a huge impact on the health of our gut. The bacteria in our microbiome has been studied for decades, using samples from human volunteers and mice. While human research has allowed us to make connections between microbiome patterns and disease, it’s the work with mice that actually help us understand the fine details of how bacteria in our gut may cause or prevent disease. In contrast to research on gut bacteria, research into the fungal population (the ‘mycobiome’) within our intestines has lagged behind. This is because this branch of life is often underappreciated and misunderstood, but this is now beginning to change and recent studies indicate that the mycobiome can profoundly impact the health of our gut.

Since fungi are common inhabitants of our intestines, one of the major interests in the field is how these intestinal fungi affect the health of our gut and what harm they might do if they ‘escape’. Fungal infections are one of the hardest to diagnose and treat, killing more than 2 million people every year and are also responsible for exacerbating other diseases like asthma and inflammatory bowel disease (IBD). Yet, fungi receive a surprisingly small amount of attention in the news and research community.

Microscopy image of fungi in a mouse intestine. Yeast cells interact with the cells of the intestine (epithelium) and mucus. Image courtesy of Dr Simon Vautier, NIH.

It’s therefore important to understand how our immune system handles fungi and prevents an infection. It’s well accepted that some species of bacteria in our gut can promote healthy intestines (probiotics or ‘good bacteria’ – you’ve probably seen these sold in yoghurt at the supermarket), while other bacteria can cause stomach ulcers. It’s therefore reasonable to assume that different fungal species might have similar benefits or health risks, and some recent research has shown that this is the case. For example, inflammatory bowel disease (IBD) is a condition where the immune system attacks the intestine for reasons that we don’t yet fully understand, and it’s long been known that proteins in our blood (antibodies) that stick to a fungus called Saccharomyces cerevisiae (anti-S. cerevisiae antibodies: ASCA) correlate with the incidence of IBD. So, if you have IBD, it’s likely that you have more ASCA in your blood. Moreover, mutations in genes that are needed to activate immune responses against fungi have been repeatedly linked to IBD and an overgrowth of fungi in the gut. Studies using samples from IBD patients have shown that a disturbance (‘dysbiosis’) of the mycobiome is a common occurrence in IBD; patients with IBD have increased amounts of a fungus called Candida albicans, and the ratio between different fungal species is not normal in IBD patients compared to people who have never experienced IBD.

It’s therefore important to understand how our immune system handles fungi and prevents an infection. It’s well accepted that some species of bacteria in our gut can promote healthy intestines (probiotics or ‘good bacteria’ – you’ve probably seen these sold in yoghurt at the supermarket), while other bacteria can cause stomach ulcers. It’s therefore reasonable to assume that different fungal species might have similar benefits or health risks, and some recent research has shown that this is the case. For example, inflammatory bowel disease (IBD) is a condition where the immune system attacks the intestine for reasons that we don’t yet fully understand, and it’s long been known that proteins in our blood (antibodies) that stick to a fungus called Saccharomyces cerevisiae (anti-S. cerevisiae antibodies: ASCA) correlate with the incidence of IBD. So, if you have IBD, it’s likely that you have more ASCA in your blood. Moreover, mutations in genes that are needed to activate immune responses against fungi have been repeatedly linked to IBD and an overgrowth of fungi in the gut. Studies using samples from IBD patients have shown that a disturbance (‘dysbiosis’) of the mycobiome is a common occurrence in IBD; patients with IBD have increased amounts of a fungus called Candida albicans, and the ratio between different fungal species is not normal in IBD patients compared to people who have never experienced IBD.

Candida albicans is found as a yeast in our gut. Image from Wikipedia

In human studies like this, we can only ever make assumptions from this type of data, but it is difficult, if not impossible, to determine causality. It’s not clear whether the mycobiome dysbiosis in IBD patients is a cause of the IBD, or a consequence. To help understand these sorts of correlations and make sense of them, we can use mice as a model system. Mice are commonly used for immunology research because the immune system is similar between different species of mammals; mice have the same types of immune cells that carry out similar functions as their human counterparts. We know this because mutations in genes that are important for preventing IBD or fungal disease cause similar diseases in mice as they do in humans. Mice also provide us with a way of obtaining samples of intestine tissue, since it would be difficult to find human volunteers for such research which would also suffer from the lack of laboratory controls. The complexity of the gut also means that we can’t use petri-dishes, because we simply can’t model the thousands of interactions happening in the gut in a petri-dish.

We can also breed mice so that they have no bacteria or fungi in their intestines. These are known as ‘germ-free’ mice and are particularly useful for studies that want to analyze how an individual species of bacteria or fungi affects the intestinal immune system and our metabolism; something that isn’t possible to do in humans. To give an example, if you take germ-free mice and feed them the yeast S. cerevisiae (the one that ASCA binds to and indicates IBD), you can make the symptoms of IBD worse. Researchers showed that this was because S. cerevisiae caused a build-up of uric acid as it grew in the intestine. Uric acid activates our immune cells so they become over-excited and start to attack the intestine, basically causing symptoms of IBD. These types of experiments can help us understand the possible mechanisms resulting in IBD and the roles our microbiota might play in the development of this disease.

Germ-Free Animal Facility. Animals are bred and kept within isolator units to keep them sterile from outside bacteria, fungi and other microbes found in the environment. Photograph courtesy of Yasmine Belkaid, NIAID, NIH.

In addition to looking at individual species, we can also use mice to understand relationships between bacteria and fungi living together side-by-side in the gut. Changing the amount of fungi in the gut, by introducing a new species in the diet or depleting lots of fungi at once with antifungal drugs, subsequently changes the amounts of different bacteria in the gut. The same is true when you do the opposite experiment – antibiotic treatment (which kills off the bacteria, not the fungi) causes fungi in the intestine to grow like crazy, a phenomenon known as a fungal bloom. These blooms are thought to be one of the ways a patient could contract a dangerous blood-poisoning fungal infection called systemic candidiasis, which if treated, still only has a 50/50 chance for survival.

So, if fungi can exacerbate IBD and be a potential source for blood-poisoning, should we be treating patients with antifungal drugs to prevent this? For IBD at least, mouse models suggest that this strategy won’t work. Mice treated with antifungal drugs weren’t helped at all – they actually developed worse IBD after treatment than mice that were left untreated. This was because the antifungal drug treatment doesn’t completely get rid of all the different species of fungi in the gut. Instead, you get rid of some species, and the remaining fungi (which are resistant to the drugs) start to grow and takeover. This is what we call a dysbiosis of the mycobiome, and we’ve seen it before – in patients with IBD.

The number of papers discussing the mycobiome has seen a 10-fold increase since 2013, indicating that awareness of fungi and fungal infections is on the rise. More research is needed to understand our relationship with fungi and this critically depends on using animal models, without which we wouldn’t have learned how the fungi and bacteria in our guts exacerbate diseases like IBD. By better understanding this, we can begin to decide what to do about it and develop treatments for the future.

Rebecca Drummond

Jane Goodall and White Coat Waste are wrong about nicotine addiction research

This open letter is from scientists and leaders in the addiction research community.  If you’d like to join the signatories listed below, please do in comments at the bottom of this article. Please also share with others with an interest in research on addiction.

Smoking – and nicotine addiction – are sometimes easy targets for criticism by many people. For others, addiction is a mental health issue of deep concern, affecting one in seven Americans during their lifetime, often resulting in immeasurable suffering and even death.  There are many reasons that addiction can be an easy target and perennial candidate for ridicule. One is that some believe addiction is “simply a matter of weak willpower,” evidence of a “moral failing,” or some other character flaw. In this, we see parallels to medieval beliefs that schizophrenia, bipolar disorder, and depression were due to witchcraft, demonic possession, wandering uteruses, and weak moral character.

Addiction is a brain disorder

Through decades of scientific study of the brain, behavior, genetics, and physiology, we now know that addiction is a complex disorder affected by neural function, genes, and the environment. We also know – at a specific level – about the brain chemistry and circuits that increase the risk for and play a role in addiction—including smoking. Unfortunately, there is still a lot we do not know, including questions such as: Why are some individuals vulnerable to addiction and others not? Why does relapse after any kind of treatment occur at such phenomenally high rates? Why do drug abusers persist in seeking and taking substances that so clearly will lead to incarceration, poverty, even death?

It is these gaps in knowledge – along with empathy for those suffering because of addiction—that lead the nation’s health research agencies to actively support addiction research. Yet, there are others who seek to end this lifesaving research. For example, a months-long campaign by the anti-animal research advocacy group White Coat Waste Project targeting nicotine addiction research recently got a boost from Jane Goodall, the celebrity primatologist known for research on chimpanzee behavior. This marks yet another high profile pairing of Goodall and groups fundamentally opposed to all nonhuman animal research. Here, Goodall wrote to the head of the US Food and Drug Administration (FDA) about research on nicotine addiction in monkeys conducted at the FDA’s National Center for Toxicological Research (NCTR).

Addiction costs the US billions each year

What Goodall claims is that the research is a misuse of taxpayer’s money because of her belief that ‘the results of smoking are well-known in humans’, and that the same research can be done in humans. Both statements are shocking, no less so because they come from a prominent scientist whose very profession is based on reporting facts.

Even a cursory glance at the state of tobacco use in the US gives some clues as to why statements like this are irresponsible: According to the National Institute on Drug Abuse (NIDA), tobacco use kills approximately 440,000 Americans each year. Given the White Coat Waste Project’s interest in saving the taxpayer’s money, the estimated economic impact of tobacco use, including everything from healthcare costs to cigarette-related fires, is almost $200 billion per year (see NIDA Research Report Series online, 2012). So, clearly nicotine addiction remains a significant public health problem and it is quite evident that we do not understand this disorder well enough to eradicate it—current treatments basically have just slowed it down. There is much work to do.

Outright wrong: the FDA nicotine research Goodall targets is not taxpayer funded

There is another blatant inaccuracy in Goodall’s letter to the FDA, namely, the very idea that this is a fraudulent waste of taxpayer’s money. In fact, the funding source for NCTR nicotine research is the Center for Tobacco Products (CTP), which was established to oversee implementation of the Family Smoking Prevention and Tobacco Control Act of 2009.

What is important here is that CTP funding comes from “tobacco user fees” charged to manufacturers of tobacco products. In other words, no taxpayer’s money is funding this research. How can the public trust any claim by Goodall and White Coat Waste if even this basic fact was ignored?

Why research with humans cannot answer the full range of questions

What is lost in the simple formulation that Goodall uses is the fact that research with humans cannot answer fundamentally important questions that are basic to progress in understanding, preventing, and treating addiction. Species other than humans take drugs. The fact that monkeys and rodents “self-administer” drugs in a manner similar to humans provides scientists with an extremely valuable model of drug addiction. The discovery of the “reward center” in the brain, the role of the chemical dopamine, even the basic principles of many behavioral therapies for addiction—all of these basic findings come from studies with monkeys and/or rodents self-administering drugs. In fact, the discovery that nicotine is the primary ingredient of tobacco products that contributes to their addictive properties, as well as the designation of nicotine as a drug of abuse, relied on self-administration studies. And yet, we are just at the beginning of understanding addiction as a brain disorder (rather than a simple moral failure or a series of bad decisions).

Instead of using monkeys in nicotine addiction research, Goodall suggests that ‘smoking habits’ can be studied ‘directly’ in humans. These two scenarios are entirely different—you don’t study ‘smoking habits’ in monkeys (who generally don’t go to the local gas station for some smokes). Smoking habits are an incredibly important part of nicotine addiction, but studying nicotine self-administration has entirely different goals. For example, the NCTR researchers are interested in brain changes following nicotine taking in adults and adolescents. What the monkey experiments allow them to do is isolate just nicotine (burning tobacco creates approximately 7000 chemicals)

and study its effects in a highly controlled environment. This approach allows the researchers to draw much firmer conclusions about effects on brain function than could ever be obtained in people smoking cigarettes. To treat nicotine addiction, we have to know precisely what nicotine does to the brain, and we need to do this in a systematic, carefully controlled manner.  We also need to know, however, what all the other chemicals are doing in order to understand the “real life” situation.  Studying nicotine alone provides a platform for going about doing those types of studies, eventually recreating the real life experiences of the tobacco abuser.

Absolutism is different from consideration of animal welfare

Research in laboratories with animals is conducted humanely, ethically, and under careful oversight guided by federal and state laws, regulations, guidelines, and by institutional policy.  Importantly, it is unclear what evidence Goodall and White Coat Waste have for any serious violations of regulations at the FDA facility. It may be the case that Jane Goodall and White Coat Waste are opposed to animal research that is conducted in order to benefit human health. That is a different argument, however, than saying that addiction research is unnecessary, that human studies are all that is needed, or that the animals are abused. We in the scientific community wholeheartedly support ethical, humanely-conducted research on addiction to nicotine and other drugs of abuse, which is in the public’s interest. At the same time, we condemn this irresponsible and factually-challenged assault on research at the NCTR.

Conclusion

We, the undersigned, support the careful, considered and regulated use of primates in addiction research. While respecting Dr. Jane Goodall as an eminent primatologist—known for her knowledge of chimpanzee behavior in the wild—we do not believe she has the necessary expertise to intervene into the scientific questions of addiction research and neuroscience. Addiction is a major public health issue worldwide, and requires and deserves close scientific scrutiny, some of which will require the use of animals.

James K. Rowlett, Ph.D., Professor and Vice Chair for Research, Department of Psychiatry & Human Behavior, University of Mississippi Medical Center

Jack E. Henningfield, Ph.D., Vice President, Research, Health Policy, and Abuse Liability, Pinney Associates, Inc. and Professor, Department of Psychiatry, Johns Hopkins University School of Medicine

Marina Picciotto, Ph.D., Charles B.G. Murphy Professor of Psychiatry and Professor in the Child Study Center, of Neuroscience and of Pharmacology, Deputy Chair for Basic Science Research, Dept. of Psychiatry, Deputy Director, Kavli Institute for Neuroscience, Yale University

Travis Thompson, Ph.D., L.P., Professor, University of Minnesota; Past President of American Psychological Association Division of Psychopharmacology and Substance Abuse; Past Member, College on Problems of Drug Dependence Executive Committee

Charles P. France, Ph.D., Robert A. Welch Distinguished University Chair in Chemistry, Professor of Pharmacology and Psychiatry, University of Texas Health Science Center- San Antonio

Michael A. Nader, Ph.D., Professor of Physiology, Pharmacology, and Radiology and Director, Center for the Neurobiology of Addiction Treatment; Co-Director, Center for Research on Substance Use and Addiction, Wake Forest School of Medicine

Thomas Eissenberg, Ph.D., Professor of Psychology (Health Program) and
Director, Center for the Study of Tobacco Products, Virginia Commonwealth University

Nancy A. Ator, Ph.D., Professor of Behavioral Biology, Johns Hopkins School of Medicine

Roger D. Spealman, Ph.D., Professor of Psychobiology, Department of Psychiatry, Harvard Medical School

Kathleen A. Grant, Ph.D., Chief and Senior Scientist, Division of Neuroscience, Professor, Dept. Behavioral Neuroscience, Oregon National Primate Research Center

Alan J. Budney, Ph.D., President, College on Problems of Drug Dependence, Past President, Division of Psychopharmacology and Substance Abuse (28) and the Division on Addictions (50) – American Psychological Association, Professor, Geisel School of Medicine at Dartmouth

Peter W. Kalivas, Ph.D., Professor and Chair, Department of Neuroscience, Medical University of South Carolina

Marilyn E. Carroll, Ph.D., Professor of Psychiatry and Neuroscience, Department of Psychiatry, University of Minnesota

Craig A. Stockmeier, Ph.D., Professor, Dept Psychiatry & Human Behavior, University of Mississippi Medical Center

Janet Neisewander, Ph.D., Professor, School of Life Sciences, Arizona State University

Mary E Cain, PhD, Professor of Psychological Sciences, Past President for Behavioral Neuroscience and Comparative Psychology, Kansas State University

Wei-Dong Yao, PhD, Professor, SUNY Upstate Medical University

Lance R. McMahon, PhD, Chair and Professor of Pharmacodynamics, College of Pharmacy, University of Florida

Michael N. Lehman, Ph.D., Professor and Chair, Department of Neurobiology and Anatomical Sciences, Chairman of the Board, UMMC Neuro Institute, University of Mississippi Medical Center

Donna M. Platt, Ph.D., Associate Professor, Department of Psychiatry & Human Behavior, University of Mississippi Medical Center

Michael A. Taffe, Ph.D., Associate Professor, The Scripps Research Institute

Linda J. Porrino, PhD, Professor and Chair, Wake Forest School of Medicine

Kevin B. Freeman, Ph.D., Associate Professor, Department of Psychiatry & Human Behavior, University of Mississippi Medical Center

Mei-Chuan Ko, Ph.D., Professor, Wake Forest School of Medicine

Sally L. Huskinson, Ph.D., Instructor, Department of Psychiatry & Human Behavior, University of Mississippi Medical Center

Mark Smith, PhD, Professor, Department of Psychology and Program in Neuroscience, Davidson College

Daniel C. Williams, Ph.D., Associate Professor, Director, Division of Psychology, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center

Eric J. Vallender, PhD, Associate Professor, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center

Matthew Banks, PharmD, PhD, Assistant Professor of Pharmacology and Toxicology, Virginia Commonwealth University

Paul May, Ph.D., Department of Neurobiology & Anatomical Sciences, University of Mississippi Medical Center

Juan Carlos Marvizon, Ph.D., Adjunct Professor, UCLA, VA Greater Los Angeles Healthcare System

Catherine M. Davis, PhD, Assistant Professor, Division of Behavioral Biology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine

Klaus A. Miczek, Ph.D., Moses Hunt Professor of Psychology, Psychiatry, Pharmacology, & Neuroscience, Tufts University, Department of Psychology

Wendy J. Lynch, Ph.D., Associate Professor of Psychiatry and Neurobehavioral Sciences, University of Virginia

Michael T. Bardo, Professor of Psychology, Director, Center for Drug Abuse Research Translation (CDART), University of Kentucky

Xiu Liu, MD, PhD, Professor, Department of Pathology, Associate Director, Graduate Program in Pathology, University of Mississippi Medical Center

Katherine Serafine, PhD, Assistant Professor of Behavioral Neuroscience University of Texas at El Paso, Department of Psychology

Robert L. Balster, PhD,  Butler Professor of Pharmacology and Toxicology, Research Professor of Psychology and Psychiatry, former CoDirector of the Center for the Study of Tobacco Products, Virginia Commonwealth University, Richmond, VA

David Jentsch, Ph.D., Professor of Psychology, Binghamton University

William W. Stoops, Ph.D., Professor, University of Kentucky College of Medicine

Jack Bergman, Ph.D., McLean Hospital / Harvard Medical School

Barry Setlow, PhD, Professor, Department of Psychiatry, University of Florida College of Medicine

Doris J. Doudet, PhD, Professor, Dept. Medicine/Neurology, University of British Columbia

Leonard L. Howell, PhD, Professor of Psychiatry and Behavioral Sciences, Emory University

S. Stevens Negus, PhD, Dept. of Pharmacology and Toxicology, Virginia Commonwealth University

Carrie K. Jones, Ph.D., Director, In Vivo and Translational Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University

 

 

 

 

 

 

Found in Translation: Using a Personal Tragedy to Drive Innovative Research

Kathryn Henley is a doctoral candidate at the University of Alabama at Birmingham. She studies pain in animals, currently pigs, trying to understand the different and often subtle signs that animals may be in pain. In this post, she explains why her research is important – both to the development of good animal welfare and the development of better pain management in humans.

Ten years ago, my dad fell off a ladder while he was cleaning the gutters on our house. Although he only fell five feet, the position in which he fell broke vertebrae in his neck. He was taken via MedFlight to a specialty hospital, where a neurosurgeon diagnosed him with a C4/5 complete spinal cord injury. In simple terms, he was paralyzed from the chest down and could not move or feel anything below that level.

One unfortunate side effect of spinal cord injury is that while the ability to feel internal stimuli (e.g., needing to go to the bathroom) and external stimuli (e.g., someone touching your hand) is lost, the majority of people with spinal cord injury live with the feeling of pain. This pain is usually severe and can significantly affect their physical capabilities, mental and emotional health, and social activities.  For example, my dad’s pain made it extremely difficult for him to participate in rehabilitation. I would often bring him to physical therapy where he would sit with cold packs on his shoulders instead of performing exercises to help him regain function. The medications available to treat pain after an injury to the central nervous system are few. Most of the medications my dad tried failed to provide adequate relief, and the few that did were highly addictive or left him feeling “out of it.” He usually chose not to take his medication and to live with the pain rather than dealing with the side effects.

I find the lack of effective therapeutics for pain extremely frustrating. If the number of preclinical studies of pain is increasing, why haven’t they translated into pain relief for people like my dad? In general, pain is extremely hard to measure. There is no biomarker for pain and we can’t ask the animals how they are feeling or have them fill out a survey. However, we can make observations about their behavior. One way pain is assessed in animals is measuring withdrawal reflexes. This is the same reflex that humans experience when we touch a hot stove and immediately pull back our hand. However, this is a spinal reflex that occurs so quickly, it happens before the feeling of pain reaches your sensory cortex. This is problematic for the study of pain after spinal cord injury because axons in the spinal cord that carry pain signals to the cortex may be damaged. In other words, the injury may prevent pain information from reaching the brain even though the withdrawal reflexes remain intact. Therefore, we can’t assume that there is pain sensation below the level of a spinal cord injury even if there is a withdrawal reflex. Additionally, the most devastating part of living with pain is the physical, emotional, and mental effects of feeling the pain, not withdrawal responses. My research focuses on behaviors in animals that tell us when there is a “feeling” of pain that reaches the sensory cortex and then results in a behavioral reaction.

The first behavior I examine is the “pain face,” also known as a grimace. When humans are in pain, we grimace by narrowing our eyes, wrinkling our nose, and raising our upper lip. Animals also grimace by changing certain parts of their faces, including their eyes, ears, cheeks, and nose or snout. An assessment called the grimace scale was first developed in mice by Dr. Jeffrey Mogil at McGill University in Canada. The grimace scale has since been translated to rats, rabbits, cats, pigs, sheep, and horses. Researchers have found that mice with lesions to their insular cortex don’t grimace. Because the insular cortex is involved in the emotional component of pain in humans, this may indicate that grimacing reflects the emotional effect of pain.

Example of the Rat Grimace Scale. There are four action units in the rat’s face that change with pain: the eyes, ears, whiskers, and nose/cheek. Image source: K. Henley, unpublished.

I also use vocalizations to measure pain. Some animals vocalize to communicate when they are in pain because this ultimately benefits them and promotes the survival of their species. However, other animals like mice and rats may not vocalize when they feel pain because this would attract predators. Right now, I am characterizing the vocal repertoire of pigs. This means I record all the sounds that pigs make and classify them based on how they sound and look on a spectrogram. Sound analysis software enables me to analyze different components of their calls in detail, so I can determine even slight differences in duration and frequency. Knowing all their calls will allow me to better assess differences when using their vocalizations as an outcome measure. So far, I have characterized 16 different call types. Did you know that pigs bark?!

One important consideration when assessing pain is the confounding effect of other mental and emotional states, such as stress or anxiety. Animals may behave differently because of stress, regardless of whether they are in pain or not. As such, we take extreme care to ensure our animals feel safe and comfortable in their environment. We allow the animals to acclimate to their new space for three days after their arrival, without any interaction with study staff. On the following days, we slowly habituate them to our presence by offering treats and other positive reinforcement. We do not begin any study-related procedures until each animal can be calmly approached and touched by the investigators. Many prey animals will hide signs of pain from predators; therefore, it is vital that our animals do not feel threatened at any time. In fact, the pigs enjoy our presence very much (as it typically accompanies food) and I enjoy spending time getting to know each individual animal. They are also acclimated to any rooms, equipment, or procedures they will experience in the study to reduce any effects from stress or anxiety.

I love my research because it serves a dual purpose: to help both animals AND people like my dad live pain-free. The more I learn about animals and their behavior, the more information there is to guide animal welfare policies in both biomedical research and the production (farm) industry. This means that scientists, veterinarians, laboratory animal technicians, and farm personnel will have access to better tools to assess whether an animal is pain and if a pain medication is working. In addition, more accurate assessments of pain will lead to more valid results from preclinical studies. This means that people like my dad will have better options to help manage their pain and be able to achieve a better quality of life.

Kathryn Henley

Veteran speaks up for the importance of allowing canine research to continue at the VA Medical Center

On July 26, 2017, the House of Representatives passed an amendment (proposed by Rep. Brat) to a spending bill that would ban all medical research at the Department of Veterans Affairs that could cause pain to dogs. The spending bill itself has not yet passed, however if such a bill was to be passed with the amendment, and also approved by the Senate, it would do huge damage to important medical research conducted by the VA.

The following article by Sherman Gillums Jr was originally published in The Hill on August 8, 2017 under the title “Devaluing human life is no way to thank wounded veterans for their service“. It is reproduced here with permissions from both The Hill and the original author. Sherman Gillums Jr. is a retired U.S. Marine officer who suffered a spinal cord injury in 2002 while serving on active duty. His career with Paralyzed Veterans of America started in 2004 after he completed rehabilitation at the San Diego VA Spinal Cord Injury & Disease Center. He is an alum of University of San Diego and Harvard Business School.


For a veteran facing a lifetime of paralysis after suffering a spinal cord injury, hope is often the last thing to die. Yet, the recently introduced House bill, H.R. 3197, threatens to crush what little hope to which I, and the approximately 60,000 veterans living with spinal cord injury, cling. The act proposes to reduce investment in medical research, and the reason is as simple as it is controversial: animal research.

Introduced by Rep. Dave Brat (R-Va.), the Act follows reports of experimentation on dogs at the McGuire VA Medical Center in the congressman’s home state. Purportedly disturbing reports revealed that animals were being given amphetamines and suffering heart attacks, among other research-based details that aren’t easily digestible by those outside of the scientific community. The mainstream gut reaction that followed these revelations was easy to predict. When contemplated in a vacuum, the thought of animals experiencing induced pain would bother any reasonable person. However, I do not enjoy the luxury of contemplating these thoughts in a vacuum.

My thoughts immediately shift to the 23-year old soldier I met on a spinal cord injury unit in San Diego. He had a freshly severed spinal cord, fixators that held the bones in his legs together, and chronic pain that often kept him awake all night, despite medication. He also had a two-year old daughter, Marianna, who knew nothing about an explosive device, or how the one that hit her father would change her life forever. Then the two thoughts clashed and bred possibilities— hope —that sprang from what research might offer to him and his daughter. A hope that may now be dying for him, me and those 60,000 other veterans who could benefit from that research.

dog, animal testing, animal experiment

“VA’s canine research that spurred the development of the cardiac pacemaker and artificial pancreas the Food and Drug Administration approved just last year, which serves to benefit both veterans and those who have never worn the uniform” [This image was not part of the original article]

When House members voted on July 26, 2017 to ban all VA medical research that causes pain to animals, specifically targeting VA’s canine research program, it was the first step toward a complete devaluation of the lives of catastrophically injured veterans. Brat declared, “From what I read, the type of work that [VA researchers] were doing was on the level of torture.”

I understand how reading a report like that would spur intense emotion and abstract horror. But if the congressman had put down the report and accompanied me to a VA hospital, he would have discovered that the price of military service is not abstract. He would have seen firsthand what it’s like to care for a paralyzed veteran with a failing heart on a VA spinal cord injury unit; or another on the polytrauma unit who needs a new pancreas, among other missing body parts that need to be replaced. After that reality check, I’d have asked the congressman, to consider these facts: It was VA’s canine research that spurred the development of the cardiac pacemaker and artificial pancreas the Food and Drug Administration approved just last year, which serves to benefit both veterans and those who have never worn the uniform. Non-VA canine research has also led to the discovery of insulin, new tests and treatments for various types of cancer and has played an important role in ushering in advancements in heart surgery procedures. While that reality may be inconvenient, it’s like freedom and democracy; it all comes at a price. I’d rather that price involve as little human suffering as possible. It’s apparent, however, not everyone agrees.

I would like to leave the legislative debate to the congressman and his colleagues, but it’s the ideology behind this bill that troubles me.  Those participating in the debate over the VA’s animal research program appear to fall into two camps: those who believe we should do everything we can to improve the lives of seriously injured veterans, and those who refuse to stare the ugly consequences of war in the face. It is not that simple though. The U.S. military faces the ugliness for its citizens, which includes our public servants.  Now that those citizens are faced with the aftermath, some are having second thoughts.

The VA has a responsibility to consistently find new and better ways of treat America’s heroes. Animal research helps the department do that. The program has helped save and improve countless lives, and it will continue to do so—unless ideology, and in some cases extremism on the issue of animal rights, succeed in forcing the public’s attention away from VA waiting rooms, inpatient wards, and rehabilitation gyms across the country. This is where the price of wars across several eras can be seen almost daily, as well as where medicine and science find their ripest opportunities.

Medical and scientific experts in America, as well as across the globe, agree animal research is essential. That’s because only animal research will provide the answers needed to develop revolutionary new treatments. Whether we like it or not, canine research is especially vital to potential medical breakthroughs because of unique traits shared by humans and dogs. In fact, CNN recently highlighted in a February 2017 story how canine research is leading to better results than traditional cancer research efforts.

Despite the hyperbole used by legislators to invoke disturbing images, VA is conducting research that is vital to seriously disabled veterans.  That is what cannot be forgotten or eclipsed by words hyperlinked to extreme ideologies. Canine studies address a host of medical problems afflicting them, and it advances treatments that heal them, or at the very least, mitigate their suffering and give them a better quality of life. I’ve seen it for myself, as Paralyzed Veterans of America has collaborative partnerships with Yale University and New Haven VA Medical Center to further the treatment advances that make veterans’ sacrifices endurable.

The research conducted at these facilities includes exploring cures and treatments for fatal lung infections affecting those with spinal cord injuries, dysfunction in brain circuits that control breathing, and whether service dogs reliably reduce the symptoms of post-traumatic stress disorder. Orthopedics research conducted with animals is especially important to many VA patients, as it has been essential to the design and testing of new prosthetic devices for veterans who have lost limbs.

Much of the animal research VA is doing aims to benefit a small group of veterans with specialized needs — those who’ve sustained serious injuries in the line of duty. As a veteran who represents tens of thousands within this group, veterans who stand to benefit from VA’s animal research efforts, I am compelled to challenge those who are fighting to shut this vital program down. I ask them, instead, to take a step back and look at things from our perspective.  We are veterans who live with severe disability, many still in the prime of our lives. Our lives after service will never be the same as our lives before service, but advances in research will help us experience lives with less pain—and more hope.

It is my sincere hope there will come a time when we don’t need animals for research. Unfortunately, that time has not arrived, and because of the incredible complexity of human anatomy and our still-limited understanding of how it works, animal research will be needed for the foreseeable future. To those who remain unconvinced, I’ll close with two questions: What wouldn’t you do to find a cure for spinal cord injury, cancer, chronic lung infection, orthopedic deterioration, or other serious afflictions associated with military service? Then, what would you do if it was your son or daughter who served and returned home profoundly broken by battle, illness or disease?

For many veterans and their families, these questions are not philosophical. Because for them, hope is indeed the last thing to die. It is now up to Congress to decide whether that hope will be put completely out of its misery.

Sherman Gillums Jr

Guest Post: Predictability and Utility of Animal Models

This is a guest post on the utility of animal models in drug development, misconceptions about animal models, and alternative methods of drug development, by Dale M. Cooper, DVM, MS, Diplomate, American College of Laboratory Animal Medicine. Dr. Cooper has over 20 years of veterinary experience in private practice, and as a laboratory animal veterinarian in academic and pharmaceutical research.  He is committed to the welfare of research animals.

Part I  Predictability of Animal Models for Effects of Drugs in Humans

Mark Twain popularized an aphorism that “there are three kinds of lies: lies, damn lies, and statistics.”  While all of these strategies have been employed by animal activist groups to discredit animal based research, the misuse of statistics has the most significant impact, as the most believable lies have a kernel of truth to them. Such is the case with the intense efforts by animal activist groups to discredit the use of dogs and other animal models in biomedical research. The various statistics that are cited are that only 0.0002% of studies using animals result in an approved drug, over 90% of drugs shown to be safe or effective in animals fail to make it through human clinical trials, that animal models have a poor predictive value for the effects of drugs in humans, and that the a flip of a coin gives as good of a chance of predicting success in drug development as an animal model. Like all good lies, these statements have a kernel of truth, but are extremely misleading and demonstrate a significant lack of understanding of science and a general lack of critical thinking skills.

Graphs like this are misused to suggest that animal studies result in failures in human trials.

Experts in drug development understand the limitations of animal models, but they also understand their applications. There have been several publications that have retrospectively evaluated the value of animal models in predicting human safety across a variety of therapeutic areas and the overall percentage of human toxicities predicted by animal models is around 70% with variability between different species and body systems.  Predictability for some therapeutic areas are over 90%. When different models are used in combination, the predictability increases. It is also an established fact that only about 1 in 10,000 drugs tested make it to the market and that there is over a 90% attrition rate of drugs in human clinical trials.  How does this happen if animal models are predictive?

Studies that have evaluated the ability of animal models to predict clinical results in humans show very similar results, but the interpretation of the results is varied.  Authors who are acknowledged animal activists claim the results show poor correlation between results in animals and outcomes in humans (e.g ‘no better than a flip of a coin’). However, most scientists (and the FDA and NIH) assert that animal models predict outcomes in humans with good reliability. What is the disconnect? This is where statistics come in. The different papers argue over the use of a calculation for predictive value versus likelihood ratio. The results come out slightly different.  Predictive value calculations show better results for animal models than do likelihood ratio calculations, so animal activists tend to cite the likelihood ratios while overlooking the predictive ratios (see table below). I am not a statistician and therefore won’t weigh in on this point and will use the term ‘predictive value’ to refer to both terms.

What I feel is a far more relevant discussion is how we interpret positive versus negative predictive values.  In general, the positive predictive values of animal models are higher than the negative predictive values. What this means is that the presence of an effect in an animal model is a good indicator that the same effect will be seen in humans (positive predictive value).  However, if an effect is not seen in the animal that does not mean there won’t be an effect in humans (negative predictive value). Activists have focused on the negative predictive value, taking the position that because animal models don’t predict all effects in humans, they are not reliable and therefore, the use of animals in research is not scientifically justified. Is this a valid conclusion?  Let’s apply it to another risk assessment situation and see if this makes sense. Say I want to cross a road but don’t want to get hit by a car. My Mom taught me to look both ways and if I see a car coming I don’t cross the road. There is a positive predictive value to look before I cross. However, if I don’t see a car, that doesn’t always mean one isn’t coming. Depending on its speed or visibility there is still some risk when I cross a road. The negative predictive value of looking both ways isn’t as high as the positive predictive value. So do I bother to look both ways knowing it’s not 100% reliable?  Of course I do.  But I also do other things. I listen, I assess for visibility, I may look for a crosswalk or an overpass. Just like in drug development I understand the predictive value of my risk assessment and run more than one assessment.

The ignored statistics in Bailey’s papers on the prediction rates of animal research. PPV: positive predictive value, NPV: negative predictive value.

Unlike animal activists, biomedical scientists don’t have an agenda to limit the scope of research. We use the experimental systems that allow us to address the questions at hand to develop treatments that improve the lives of both humans and animals.  The models we are using are the ones that are the most successful. Animals are one type of model employed in biomedical research, but are by no means the only models.  Animal models are expensive and time consuming, and scientists recognize the emotional and ethical issues associated with animal research.  We are human and many of us have our own pets.  We bond with the animals we work with.  There is no incentive for us to employ an animal model that may negatively impact animal well-being if another model that does not negatively impact well-being works just as well.  The FDA requires animal data prior to clinical trials in humans, because they are also scientists and have come to the same conclusion — animal models provide essential data in predicting safety and efficacy of new therapies.

Part II Drug Development Without Animals

As discussed in a previous post, animal models are an important component of the development process for drugs and other medical treatments. But they are not the only method of research that is used.  Drug development is an iterative process.  Each study builds on data from other studies.  The process involves computer modeling, benchtop chemistry, a wide range of in vitro models to evaluate absorption, metabolism, distribution, receptor binding, gene expression, and even some aspects of toxicity. We use non-animal methods so much that over 90% of drug candidates are eliminated from consideration using in vitro assays before they even reach the phase of pre-clinical animal studies.

If animal activists groups or well-meaning scientists want to see more non-animal research methods developed and put into use, there is a process for this. The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) under the National Toxicology Program evaluates data to validate non-animal models for drug development in the US. There is a list of approved methods on their website. All of these methods were funded by the same research institutions that use animal models.  If activist groups wanted to make a significant impact on animal use in research, they might consider funding alternative research.  It is usually more effective to work on a problem rather than just talk about it.  The fact that we are still using animals isn’t because of a lack of trying, it is the limitation in our scientific knowledge. To build a model, you have to know a lot about the system you are modeling. In fact, it is possible there will never be a complete replacement of animal models in research. By the time we know everything to create the perfect model, we will have answered all of the research questions that can be asked.

The final stage of drug development involves clinical testing in human patients.  In vivo studies in animal models eliminate 90% of drug candidates from the development process before beginning clinical trials in humans, demonstrating their utility in de-risking the testing process in humans.. Over 1 million patients to enroll in clinical trials each year, yet there are few reports of serious adverse events relative to the number of patients in these trials.  When drugs fail during the clinical trial phase, the reasons are more often related to economics or strategy than they are to safety.  The testing in animals served an important purpose.

If society chooses to take more risk in the patient population, it has the power to do so. However, based on the data regarding predictive value of non animal models, this would mean that 70% of the time someone in a clinical trial would be likely to experience toxicity from a drug about which little is known because the nature of it was not first characterized in animal models. This means the physicians would not know how to treat it or the prognosis. It is already a challenge to enroll the number of patients needed for clinical trials even when providing them a significant amount of information so they can make an informed decision to consent to enroll. Having even less information would not likely help with this.

Laboratory mouse.

It is also not clear that humans are a better model for testing drugs than are animal models. It is extremely difficult to control variability in a human test population, due to diet, lifestyle, and genetics, which reduces the statistical power of a given study population compared to a well-controlled animal study. Clinical trials in humans enroll thousands of patients, whereas animal studies use fewer than 100 animals in many studies to achieve similar statistical power.  Humans also have a long lifespan and studying the chronic effects of a drug is difficult in a clinical trial.  In contrast, in 2 years, a rodent undergoes all life stages, allowing assessment of the effects of chronic drug administration. Finally, it would be very unlikely that humans would consent to participate in studies evaluating fetal toxicity, and even if they did, the long duration of human pregnancy and low reproductive rate (1 offspring every 9 months) reduces the power of detection relative to a rodent model that produces 10 offspring in 3 weeks.

It is true that all of these issues will be considerations in patients after a drug is in general use. There is some inherent level of risk in medicine. However, the development and approval process using both animal and non-animal studies is the best that science can currently offer.

Part III The Big Picture of Animal Use

We can argue over the scientific merits of the use of laboratory vs animal vs human testing in drug development, and we can pontificate about the ethics of the decisions we make, but ultimately, we humans have choices to make.  Are we content with our level of health and well-being?  What sacrifices are we willing to make to consider the needs of animals?  The impacts we have on animals go far beyond what level of medical care we choose.  Animals serve as food sources, they work for and with us, and they provide for aesthetics and companionship.  How much of that will we give up to reduce our impacts on them?  If we go that far, we are still competing with them for food and shelter.  Is it possible to not impact animals?  I contend that the ethics of our society show a considerable level of care for animals.  The fact that we worry at all about their welfare is something that to the best of my knowledge, no other species on the planet would do given the same choices we have.

Working with animals in research is not a one-way street.  Animals benefit from veterinary treatments developed through the same research process as for human treatments, and the animals we work with in the research environment benefit from the high level of care and attention to their well-being that is provided to them. People care about them and for them. They experience medicine as part of their lives as do we all. If they were living outside of the research environment they would still experience medical issues as a normal part of life, but particularly in the case of non-companion species, would not necessarily have anyone to care for them.

I believe that the arguments proffered to discredit work with animals in research are largely based on biased and misleading interpretation of data.  Where there are valid data to use alternatives, these alternatives are already being used.  It is appropriate scientifically and ethically to continue to develop and validate new approaches for predicting drug safety and efficacy in the patient population, both animal and non-animal.  Animals are used humanely and also receive benefits from biomedical research.  Ultimately, there is a balance being struck between the needs of humans and of animals.  There is room for constructive dialog on where this balance should be, but I personally do not believe that this should occur using the regulatory and legal systems as a venue.  Science is too intricate and complex to be able to effectively address in this way.  There is a process in place at all research institutions (the IACUC) to ensure ethical and scientific review occurs on each experiment.  Those seeking to drive alternatives would do better to develop the science to validate these alternatives rather than manipulate public emotion and ultimately public policy or law.

~Dale M. Cooper, DVM, MS, Diplomate, American College of Laboratory Animal Medicine.

 

 

Asthma and Animal Research: A Public Health Perspective

As a public health researcher with a focus on behavior change and complex interventions, I am more interested in studying how to get children to adhere to their asthma medication regimen rather than the mechanisms of inflammatory asthma. I am currently studying the risk factors associated with asthma attacks in children, which include among others, sub-optimal medication use, poverty, and access to healthcare. The aim of this research is to understand what risk factors for severe exacerbations – such as asthma attacks that send children to the emergency room – exist, thereby enabling healthcare and public health professionals to mitigate the risks of these ‘at-risk’ children.

My interests have nearly always been in applied in nature, however I understand that basic research underpins everything thing that we do in public health. Animal research is foundational to what we do as public health professionals. Without animal research, we would not be able to mitigate the risk factors these children have as we would not have the asthma medications we do today.

It seems that the sphere of public health shies away from discussing and supporting animal research; I’ve had colleagues tell me to be careful of talking too openly about my experiences in animal research outreach, for fear of alienating others – and potentially hindering my career. However, I strongly believe that public health professionals should be more open to discussing and supporting animal research. It is imperative to the continuation of both public health research and its application.

To illustrate this point, let’s use asthma as an example. The most effective medications for managing asthma are aptly named preventer and reliever medications. Preventer medications contain glucocorticosteriods and they work to prevent symptoms by reducing swelling, sensitivity, and inflammation in the airways. On the other hand, Reliever medications, or bronchodilators, work to open the airways and rapidly relieve symptoms.

Animal research has played an important role in the discovery of both glucocorticosteriods and bronchodilators. Glucocorticosteriods were developed using mouse models and the derived biomedical pathways. Bronchodilators were developed the 1960s, as a result of Otto Loewi’s research on adrenaline and other neurotransmitters.  Loewi used two beating frog hearts, aligned near each other, to demonstrated that slowing the pulse of the one heart and then circulating that perfusate through the other heart that it caused the other unaltered heart to also slow. He found that the same was true when he repeated the experiment, this time increasing the heart rate. This discovery proved that nerve cell communication is chemical rather than electrical, which led to the discovery of the neurotransmitter acetylcholine, and provided the foundation for future neurotransmitter research.

Glucocorticosteroids were developed using mouse models.

In relation to asthma, bronchodilators (beta2 agonists in particular) mimic the sympathetic nervous system discovered through Loewi’s famous experiment and allow health professionals to synthetically relieve the symptoms of asthma. Other studies using mice models have also elucidated the biomolecular mechanisms of airway hyperresponsiveness in asthma. Without Loewi’s initial experiment relying animal animal research, we would not be able to treat asthma as well as we do today. Without animal research, asthma management would likely rely on alternative medications that offer little in the way in relief; without effective treatment applied asthma research would focus only on prevention.

One of the reasons I was drawn towards public health and applied research was the focus on environmental, cultural, and large system-level factors that influence health, but this can come at the expense of ignoring the wealth of basic research that allows us to study these upper-level factors. When we forget the foundational work that lets us pursue our passions, everyone suffers. Public health professionals, at the very least, need to acknowledge–if not actively advocate for—the value animal research has in improving the health of the broader public and  should actively advocate for.

In writing this post, I had to research on how asthma medications came into being. Skimming through the biomedical literature was daunting (and confusing at times), but there are great resources already created to help clarify points for the those less familiar with biomedical research, such as myself – Understanding Animal Research, Animal Research.Info, and this website, Speaking of Research are great resources. I encourage public health professionals to educate themselves in how animal research allows them to do the work they do today. Then share that knowledge, – be that over Twitter, a blog, an email to colleagues, the options are endless. Support well-evidenced and humane animal research, because our work depends on it.

Audrey Buelo, M.P.H.

Of mice and mint: Animal research uncovers a previously unknown role for menthol in tobacco addiction

Cigarette addiction remains one of the common forms of drug addiction, worldwide; it is associated with remarkably elevated risk for heart disease, stroke and multiple types of cancer, explaining why nearly half a million Americans die each year from complications of smoking. A recent study by Brandon Henderson and his colleagues at the California Institute of Technology (Caltech) have revealed a startling new finding – that one of the most common flavorants added to some cigarettes may actually accelerate tobacco addiction. Dr. Henderson, now an Assistant Professor at Marshall University, answered some questions from Speaking of Research about his most recent discoveries.

 

What is menthol and why is it important to study its effects?

Menthol is the most popular flavor additive in tobacco products and the only non-banned flavor in traditional cigarettes (not e-cigarettes) sold in the US. Over time, reports have indicated that smokers of menthol cigarettes quit smoking at lower rates than those that smoke non-menthol cigarettes. Therefore, we are trying to identify the changes in the brain that occur with menthol that may indicate if menthol increases the addictive potential of nicotine (the primary addictive component in tobacco products). As an aside, menthol cigarettes are heavily used by African American smokers (75 – 90%). As a black scientist, this was another reason why I was attracted to studying menthol.

pure-menthol-e-liquid-1_1024x1024

Menthol is a naturally occurring chemical found in a number of plants, including mints

 

Can you give us a thumbnail sketch of your study and your findings?

Our goal was to examine well-known effects of nicotine on the brain and determine if they are enhanced by menthol. Two of the ‘well-known’ effects of nicotine are an increase in the number of nicotinic receptors (the proteins that bind nicotine) and an increase in the activity of neurons that release the neurotransmitter dopamine. These two events typically occur following long-term exposure (7 – 10 days) to nicotine, contributing directly to nicotine addiction.

Neuroscientists have known that nicotine, by itself, alters the brain to release more dopamine and that is one of the reasons why it is addictive. In this study, we focused on dopamine neurons of the ventral tegmental area, a part of the brain stem. The dopamine neurons that originate in this region are part of the mesolimbic dopamine system. This region is well-characterized for its importance in mediating the rewarding effects of drugs.

When we examined the combination of menthol with nicotine, we found that the combination increases the number of nicotinic receptors to a level that is significantly greater than is produced by nicotine alone. We also found that the combination of menthol and nicotine increased the activity of dopamine neurons to a degree that was significantly greater than what we observed with nicotine alone.

Since we observed that menthol promotes the pro-addictive effects of nicotine in the brain, we believe this may provide part of an answer to why smokers of menthol cigarettes have a much harder time quitting.

 

Mice were involved in your studies. In what ways are they similar and/or dissimilar from human smokers?

The mesolimbic dopamine system of mice is very similar to humans. Like humans, mice will self-administer (voluntarily consume) many drugs of abuse, including cocaine, opioids, and nicotine. Given that mice experience drug reward, similar to humans, they make an excellent model for studying addiction. Two experimental methods are commonly used in rodent models: intravenous self-administration and conditioned place preference, both of which reveal the degree to which nicotine is rewarding in the animal.

One hurdle associated with using mice to study drugs of abuse is that their bodies break down many drugs much more rapidly than humans. Therefore, proper dosing becomes a big concern so that our studies are relevant to humans. For nicotine, the guidelines for dosing were established long before I started science so this was a great benefit to my work with mice.

 

What are the medical or societal implications of your results?

Years ago, the FDA issued a request of information regarding menthol to determine if it should be banned similarly to other flavors that were banned following the Family Smoking Prevention and Tobacco Control Act (2009). This, and other scientific reports, will hopefully be examined by the FDA in determining the future regulations of menthol in cigarettes and e-cigarettes.

 

You just started a new lab as an Assistant Professor at Marshall University. Can you tell us about your future plans for your research and career?

I will continue to study menthol for a few more years because there is still much we need to understand. In the tristate area of Kentucky, West Virginia, and Ohio (where I am originally from), there is a large opioid addiction problem. Most opiate addicts (~80%) also are heavy smokers. I intend to begin studying how opioids and tobacco act together in the brain to promote addictive behaviors.

Henderson_Brandon_Marshall-headshot

Dr. Brian Henderson is an Assistant Professor in the Joan C. Edwards School of Medicine within Marshall University in Huntington, West Virginia

Dr. Brandon Henderson can be found on Twitter at @Dr_BHenderson and on the web at https://www.hendersonlab.org/