Fragile X: preclinical portfolio for PI3k drug strategy

An alternative drug strategy for fragile X is gathering strength. Lots of data on behavior and biochemistry from mouse Read more

Stem cells driven into selective suicide

The term “stem cell” is increasingly stretchy. This is one way to get rid of a particular Read more

The blue spot: where seeds of destruction begin

Learn more about the locus coeruleus, a "canary in the coal Read more

Department of Pediatrics

Bile acid uptake inhibitor prevents NASH/fatty liver in mice

Drugs that interfere with bile acid recycling can prevent several aspects of NASH (nonalcoholic steatohepatitis) in mice fed a high-fat diet, scientists from Emory University School of Medicine and Children’s Healthcare of Atlanta have shown.

The findings suggest that these drugs, known as ASBT inhibitors, could be a viable clinical strategy to address NASH, an increasingly common liver disease. The results were published in Science Translational Medicine on September 21, 2016.

“By targeting a process that takes place in the intestine, we can improve liver function and reduce insulin resistance in a mouse model of NASH,” says senior author Saul Karpen, MD, PhD. “We can even get fat levels in the liver down to what we see in mice fed a regular diet. These are promising results that need additional confirmation in human clinical trials.”

Karpen is Raymond F. Schinazi distinguished professor of pediatrics at Emory University School of Medicine and chief of the Division of Pediatric Gastroenterology, Hepatology and Nutrition at Children’s Healthcare of Atlanta. He and Paul Dawson, PhD, Emory professor of pediatrics, jointly run a lab that investigates the role of bile acids in liver disease.

Saul Karpen, MD, PhD

Saul Karpen, MD, PhD

Many people in developed countries have non-alcoholic fatty liver disease, an accumulation of fat in the liver that is linked to diet and obesity. Fatty liver disease confers an elevated risk of type II diabetes and heart disease. NASH is a more severe inflammation of the liver that can progress to cirrhosis, and is a rising indication for liver transplant. Besides diet and exercise, there are no medical treatments for NASH, which affects an estimated 2 to 5 percent of Americans. Read more

Posted on by Quinn Eastman in Uncategorized Leave a comment

Cardiac ‘disease in a dish’ models advance arrhythmia research

New research illustrates how “disease in a dish” stem cell technology can advance cardiology.

Scientists led by Chunhui Xu, PhD derived cardiac muscle cells from a teenaged boy with an inherited heart arrhythmia, and used them to study how his cells respond to drugs. They did this not through a cardiac biopsy, but by converting some of the boy’s skin cells into induced pluripotent stem cells, and then into cardiac muscle cells.

Xu, director of the Cardiomyocyte Stem Cell Lab in Emory’s Department of Pediatrics, says this approach has been helpful in the study of other inherited arrhythmias and cardiomyopathies (example: 2011 Nature paper on long QT syndrome). In addition, Xu says, human-derived cardiac muscle cells could be used for toxicology testing for new drugs, since the molecules that regulate human cardiac muscle cells functions are distinct from those in animal models.

The findings were published on September 7 in Disease Models & Mechanisms.

The boy who provided the cells has CPVT (catecholaminergic polymorphic ventricular tachycardia), as do some of his relatives. CPVT, which occurs in about 1 in 10,000 people, is a major cause of sudden cardiac death in people younger than 40.

CPVT_arrhythmia smaller

In the patient whose cells are described in the paper, the drug flecainide could suppress arrhythmias that would otherwise appear during exercise. Electrocardiography from Preininger et al, Disease Models & Mechanisms (2016) via Creative Commons.

Arrhythmias in CPVT are almost exclusively brought on by activities that generate high levels of epinephrine, also known as adrenaline: heavy exertion, sports or emotional stress. Thus, affected individuals need to take medication regularly and usually should avoid competitive sports. The boy in the study also had an implanted cardiac defibrillator.

CPVT is generally treatable with beta-blockers, but about 25 percent of patients – including the boy in the study — are inadequately protected from arrhythmias by beta-blockers. Taking the drug flecainide, also used to treat atrial fibrillation, provides him an additional level of control.

Xu and her colleagues could duplicate those effects with his cardiac muscle cells in culture, by observing the ability of the drugs to suppress aberrant “calcium sparks.”

“We were able to recapitulate in a petri dish what we had seen in the patient,” says co-author Peter Fischbach, MD, chief academic officer at Children’s Healthcare of Atlanta’s Sibley Heart Center and associate professor of pediatrics at Emory University School of Medicine. “The hope is that in the future, we will be able to do that in reverse order.” Read more

Posted on by Quinn Eastman in Heart Leave a comment

Microgravity means more cardiac muscle cells

Cardiac muscle cells derived from stem cells could eventually be used to treat heart diseases in children or adults, reshaping hearts with congenital defects or repairing damaged tissue.

srep30956-f2

Cardiomyocytes produced with the help of simulated microgravity. Red represents the cardiac muscle marker troponin, and green is cadherin, which helps cells stick to each other. Blue = cell nuclei. From Jha et al SciRep (2016).

Using the right growth factors and conditions, it is possible to direct pluripotent stem cells into becoming cardiac muscle cells, which form spheres that beat spontaneously. Researchers led by Chunhui Xu, PhD, director of the Cardiomyocyte Stem Cell Laboratory in Emory’s Department of Pediatrics, are figuring out how to grow lots of these muscle cells and keep them healthy and adaptable.

As part of this effort, Xu and her team discovered that growing stem cells under “simulated microgravity” for a few days stimulates the production of cardiac muscle cells, several times more effectively than regular conditions. The results were published on Friday, Aug. 5 in Scientific Reports. The first author of the paper is postdoctoral fellow Rajneesh Jha, PhD. Read more

Posted on by Quinn Eastman in Heart Leave a comment

How Zika infects the placenta

Zika virus can infect and replicate in immune cells from the placenta, without killing them, scientists have discovered. The finding may explain how the virus can pass through the placenta of a pregnant woman, on its way to infect developing brain cells in her fetus.

Zika_in_vitro_smaller

Infected placental macrophages. Zika antigens visible in red. From Quicke et al (2016).

The results were published in Cell Host & Microbe.

“Our results substantiate the limited evidence from pathology case reports,” says senior author Mehul Suthar, PhD, assistant professor of pediatrics at Emory University School of Medicine. “It was known that the virus was getting into the placenta. But little was known about where the virus was replicating and in what cell type.”

Scientists led by Suthar and Emory pediatric infectious disease specialist Rana Chakraborty, MD, found that Zika virus could infect placental macrophages, called Hofbauer cells, in cell culture. The virus could also infect another type of placental cell, called cytotrophoblasts, but only after a couple days delay and not as readily. Other researchers recently reported that syncytiotrophoblasts, a more differentiated type of placental cell than cytotrophoblasts, are resistant to Zika infection.

The cells for the experiments were derived from full-term placentae, obtained from healthy volunteers who delivered by Cesarean section. The level of viral replication varied markedly from donor to donor, which hints that some women’s placentae may be more susceptible to viral infection than others. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Manipulating motivation in mice

Emory researchers have identified molecular mechanisms that regulate motivation and persistence in mice. Their findings could have implications for intervention in conditions characterized by behavioral inflexibility, such as drug abuse and depression.

Scientists showed that by manipulating a particular growth factor in one region of the brain, they could tune up or down a mouse’s tendency to persist in seeking a reward. In humans, this region of the brain is located just behind the eyes and is called the medial orbitofrontal cortex or mOFC.

“When we make decisions, we often need to gauge the value of a reward before we can see it — for example, will lunch at a certain restaurant be better than lunch at another, or worth the cost,” says Shannon Gourley, PhD, assistant professor of pediatrics and psychiatry at Emory University School of Medicine. “We think the mOFC is important for calculating value, particularly when we have to imagine the reward, as opposed to having it right in front of us.”

The results were published Wednesday in Journal of Neuroscience.

Shannon Gourley, PhD

Being able to appropriately determine the value of a perceived reward is critical in goal-directed decision making, a component of drug-seeking and addiction-related behaviors. While scientists already suspected that the medial orbitofrontal cortex was important for this type of learning and decision-making, the specific genes and growth factors were not as well-understood.

The researchers focused on brain-derived neurotrophic factor (BDNF), a protein that supports the survival and growth of neurons in the brain. BDNF is known to play key roles in long-term potentiation and neuronal remodeling, both important in learning and memory tasks. Variations in the human gene that encodes BDNF have been linked with several psychiatric disorders.

Read more

Posted on by Quinn Eastman in Neuro Leave a comment

The unsweetened option

Pediatric hepatologist Miriam Vos is starting a new study testing the effects of a low-sugar diet in children with NAFLD (non-alcoholic fatty liver disease). The study is supported by the Nutrition Science Initiative and conducted in a partnership with UCSD/Rady Children’s Hospital, San Diego. See below for more on NUSI.

While there are no medications approved for NAFLD – a healthy diet and exercise are the standard of care – plenty of drugs are under development, as a recent article from Mitch Leslie in Science illustrates. As a reality check and benchmark, the NUSI study will address whether the low-tech intervention of altering diet can be effective.

Lab Land has delved into NAFLD and its increasing prevalence in previous posts. Plenty of correlational data shows that sugar intake is linked to NAFLD (a recent paper from the Framingham Heart Study), but Vos points out that there are no studies showing that reducing sugar is sufficient to drive improvement in the disease.

Diet is a challenge to examine in humans rigorously. In observational studies, investigators are always bumping up against the limits of memory and accurate reporting. In an interventional study with adults, it’s possible to provide them a completely defined menu for a short time in a closed environment, but that’s less practical for longer periods or with children.

The press release announcing the NUSI study says: half of the families will eat and drink what they normally do while the rest will be put on sugar-free meals and snacks, all of which will be provided for the participants and their families for eight weeks.

Miriam Vos, MD

I was curious about how this would work, especially for boys aged 11 to 16 (the participants in her study), so I asked Vos more about it for Lab Land.

“We try to provide them a diet that is otherwise similar to what the family is used to,” she says. “For example, if they’re accustomed to home-cooked meals, our team of nutritionists will work with them to find different recipes.” Read more

Posted on by Quinn Eastman in Uncategorized Leave a comment

HIV virions attached to cell membrane

The third winner of the Best Image contest from the Postdoctoral Research Symposium, from postdoc Joshua Strauss in electron microscopist Elizabeth Wright’s lab.

Strauss explains:

Tetherin is a host cell factor that mechanically links HIV-1 to the plasma membrane. This is the first time anyone has imaged tethered HIV-1 by cryo-electron tomography. In doing so, we were able to learn about the length and arrangement of the tethers.

Note: Tetherin also studied by Paul Spearman + colleagues.Joshua_Strauss_OPE_Image

Cryo-electron tomography is an imaging technique which enables scientists to look at biological specimens in a “native-like” (frozen hydrated) state, without the chemical fixatives or heavy metal stains typically used for conventional electron microscopy.

The 3D reconstruction was manually segmented to highlight the different viral and cellular components: HIV-1 virions (lavender), mature conical-cores (aqua blue), immature Gag lattice (pink), plasma membrane (peach), rod-like tethers (sea green).

Posted on by Quinn Eastman in Immunology Leave a comment

All about Saccharomyces boulardii

Pediatric infectious disease specialist Tracey Lamb earned recognition this week for her NIH New Innovator award. The goal of Lamb’s project is to develop a probiotic yeast as a platform for inexpensive oral vaccines.

“We have a long way to go to develop this vaccine Magliette Calcio A Poco Prezzo delivery system to the point where it is ready for testing in the clinic,” she says. “Now my lab can undertake more intensive research on this project to demonstrate that our design is effective in protecting against infection.”

Three points:

1. The probiotic yeast Lamb is planning to develop as a vaccine platform is Saccharomyces boulardii, which has been tested in clinical trials as a treatment for gastrointestinal disorders such as Clostridium dificile infection and several forms of diarrhea. It was originally isolated in the 1920s from fruit in Southeast Asia.

2. Saccharomyces boulardii is very close to standard baker’s yeast, Saccharomyces cerevisiae, and is actually considered a subspecies of S. cerevisiae. Genomic differences that http://www.magliettedacalcioit.com contribute to its probiotic properties are under investigation.

3. The New Innovator program, running since 2007, is one of the ways the National Institutes of Health seeks to reward especially creative or potentially transformative research proposals. The New Innovator awards, up to $1.5 million over five years, are meant for newly independent researchers building their careers. Lamb managed to snag Emory’s first.

Posted on by Quinn Eastman in Immunology Leave a comment

Americans cutting sugar – but it’s still not enough

In America’s battle against obesity, there is some good news. According to a study conducted by Emory researchers, Americans consumed nearly a quarter less added sugars in 2008 than they did 10 years earlier.

The study, published in the American Journal of Clinical Nutrition in July 2011, found that the consumption of added sugars, such as those found in sodas, sports drinks, juices and sweetened dairy products, decreased among all age groups over a decade. The largest decrease came in the consumption of sodas, traditionally the largest contributor to added sugar consumption, according to Jean Welsh, MPH, PhD, RN, study author and post-doctoral fellow in pediatric nutrition at Emory University School of Medicine.

“While we were hopeful this would be the case, we were surprised when our research showed such a substantial reduction in the amount of added sugar Americans are consuming,” said Welsh. “We’re hopeful this trend will continue.”

So, why the change? One of Welsh’s partners in the study, Miriam Vos, MD, MSPH, an assistant professor of pediatrics in the Emory University School of Medicine, and a physician on staff at Children’s Healthcare of Atlanta, attributes much of the shift to public education.

“Over the past decade, there has been a lot of public health awareness about obesity and nutrition, and I think people are starting to get the message about sugar,” says Vos. “We’re not trying to send a message that sugar is inherently bad. It’s more that the large amounts of sugar we consume are having negative effects on our health, including increasing our risk of obesity, diabetes and cardiovascular disease.”

The study interpreted data of 40,000 people’s diets collected by the Centers for Disease Control and Prevention (CDC) over 10 years.  From the surveys, researchers were able to calculate how much added sugar – that is sugar that is not originally part of a food – that Americans are consuming. In 1999-2000, the typical person’s daily diet included approximately 100 grams of added sugar, a number that had dropped to 77 grams by 2007 and 2008.

While the study shows that the amount of added sugar Americans are consuming is lower, it doesn’t mean the amount is low enough.

“The American Heart Association recommends that we get about five percent of our calories from added sugars,” says Vos. “In 1999 to 2000, people were consuming about 18 percent of their calories from added sugars. Over 10 years, that amount decreased to 14.5 percent of our daily calories, which is much better. But, clearly, 14.5 percent is still three times more than what is considered a healthy amount. We’re on the right track, but we still have room for improvement.”

Posted on by Kerry Ludlam in Uncategorized Leave a comment

A milestone in treating hemophilia

Hematologist Pete Lollar has devoted his career to developing treatments for hemophilia A, which is caused by a lack of blood clotting factor VIII. Lollar is a professor of pediatrics in Emory School of Medicine and director of hemostasis research at Children’s Healthcare of Atlanta. Last week, Lollar was honored by Emory’s Office of Technology Transfer for setting in motion research that has progressed to a phase III clinical trial of a new product, OBI-1, a special form of factor VIII.

John "Pete" Lollar, MD

Along with this milestone came a dramatic story, described by OTT’s assistant director Cale Lennon. The first patient to enroll in the clinical trial did so in November 2010 because of what appeared to be acquired hemophilia, which led to severe uncontrolled hemorrhaging. As a result of treatment with OBI-1, developed by Lollar and his research team at Emory, the patient’s bleeding was brought under control and it saved his life. He was treated at Indiana Hemophilia and Thrombosis Center in Indianapolis.

Acquired hemophilia is a challenge for doctors to deal with because it is such a surprise. Unlike people with inherited hemophilia, those with acquired hemophilia do not have a personal or family history of bleeding episodes. Their immune systems are somehow provoked into making antibodies against their own clotting factor VIII. These antibodies also appear over time in about 30 percent of patients with inherited hemophilia who take standard clotting factors.

OBI-1, a special form of clotting factor VIII, is less of a red flag to the immune system. This allows treatment of patients who cannot benefit from standard clotting factor VIII, because of the presence of auto-antibodies.

Emory originally licensed OBI-1 to Octagen Corporation, a “homegrown” startup company founded in 1997. Octagen sublicensed the OBI-1 technology to a French biotechnology firm, Ipsen Biopharm in 1998. Over the next decade, Octagen and Ipsen pursued preclinical and initial clinical studies and completed a phase II clinical trial in 2006. Ipsen purchased the OBI-1 program outright in May 2008.

In January 2010, Ipsen developed a partnership agreement with Inspiration Biopharmaceuticals, which was founded by two businessmen whose children have hemophilia. Under the agreement’s terms, Inspiration licensed OBI-1 from Ipsen and is responsible for its clinical development, regulatory approval and commercialization.

Posted on by Quinn Eastman in Uncategorized Leave a comment
« Previous   1 2 3