Probing the brain’s earliest development, with a detour into rare childhood cancers

In early brain development there is an increase in ribosomes, contained in these nucleoli
Nucleoli, the structures in the cell nucleus that manufacture ribosomes, are enlarged in very early brain development, indicating an increase in ribosome production. Here, a 3D reconstruction of individual nucleoli. (Kevin Chau, Boston Children’s Hospital)

In our early days as embryos, before we had brains, we had a neural fold, bathed in amniotic fluid. Sometime in the early-to-mid first trimester, the fold closed to form a tube, capturing some of the fluid inside as cerebrospinal fluid. Only then did our brains begin to form.

In 2015, a team led by Maria Lehtinen, PhD, Kevin Chau, PhD and Hanno Steen, PhD, at Boston Children’s Hospital, showed that the profile of proteins in the fluid changes during this time. They further showed that these proteins “talk” to the neural stem cells that form the brain.

In new research just published in the online journal eLife, Lehtinen and Chau shed more light on this little-known early stage of brain development.

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Scientists find link between increases in local temperature and antibiotic resistance

Image representing the rise of antibiotic resistance
Illustration by Fawn Gracey

Over-prescribing has long been thought to increase antibiotic resistance in bacteria. But could much bigger environmental pressures be at play?

While studying the role of climate on the distribution of antibiotic resistance across the geography of the U.S., a multidisciplinary team of epidemiologists from Boston Children’s Hospital found that higher local temperatures and population densities correlate with higher antibiotic resistance in common bacterial strains. Their findings were published today in Nature Climate Change.

“The effects of climate are increasingly being recognized in a variety of infectious diseases, but so far as we know this is the first time it has been implicated in the distribution of antibiotic resistance over geographies,” says the study’s lead author, Derek MacFadden, MD, an infectious disease specialist and research fellow at Boston Children’s Hospital. “We also found a signal that the associations between antibiotic resistance and temperature could be increasing over time.”

During their study, the team assembled a large database of U.S. antibiotic resistance in E. coli, K. pneumoniae and S. aureus, pulling from hospital, laboratory and disease surveillance data documented between 2013 and 2015. Altogether, their database comprised more than 1.6 million bacterial specimens from 602 unique records across 223 facilities and 41 states.

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Elusive epilepsy mutations begin to yield up their secrets

mosaic epilepsy mutations concept
Fawn Gracey illustration

Anti-seizure drugs don’t work in about a third of people with epilepsy. But for people with focal epilepsy, whose seizures originate in a discrete area of the brain, surgery is sometimes an option. The diseased brain tissue that’s removed also offers a rare opportunity to discover epilepsy-related genes.

Many mutations causing epilepsy have been discovered by testing DNA taken from the blood. But it’s becoming clear that not all epilepsy mutations show up on blood tests. So-called somatic mutations can arise directly in tissues like the brain during early prenatal development. Even within the brain, these mutations may affect only a fraction of the cells — those descended from the original mutated cell. This can create a “mosaic” pattern, with affected and unaffected cells sometimes intermingling.

One of the first such mutations to be described, by Ann Poduri, MD, MPH, and colleagues at Boston Children’s Hospital in 2012, was in Dante, a young boy who was having relentless daily seizures. The entire right side of Dante’s brain was malformed and enlarged, and he underwent a drastic operation, hemispherectomy, to remove it. Only later, studying brain samples from Dante and similar children, did Poduri find the genetic cause: a mutation in the gene AKT3. It affected only about a third of Dante’s brain cells. 

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How well do gluten-free diets eliminate gluten, and is home gluten testing a good thing?

gluten testing could help predict intestinal health in patients with celiac disease

For patients with celiac disease, following a gluten-free diet is complicated and often challenging.

“Our patients are navigating a gluten-free diet without any feedback to guide them,” says Jocelyn Silvester, MD, PhD, director of research at the Celiac Disease Program at Boston Children’s Hospital. “Symptoms are not a reliable indicator of gluten exposure. Many patients may not have any symptoms at all.”

For clinicians, assessing how well patients are doing on a gluten-free diet can be equally difficult. “There are no good measures of how well the gluten-free-diet is working or how well patients are following the diet,” Silvester says.

Moreover, tolerance to gluten can vary in celiac disease. Some children have symptoms despite being (apparently) on a gluten-free diet. Others have no symptoms after a gluten exposure, yet show severe atrophy of the nutrient-absorbing villi on intestinal biopsy. Villous atrophy poses a risk for complications, such as poor growth, anemia and osteoporosis.

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Trial shows chemotherapy is helping kids live with pulmonary vein stenosis

Magnification of pulmonary vein tissue showing signs of pulmonary vein stenosis (plump abnormal cells stained dark magenta).
Magnification of pulmonary vein tissue showing signs of pulmonary vein stenosis (plump abnormal cells stained dark magenta). Credit: Boston Children’s Hospital Department of Pathology

Pulmonary vein stenosis (PVS) is a rare disease in which abnormal cells build up inside the veins responsible for carrying oxygen-rich blood from the lungs to the heart. It restricts blood flow through these vessels, eventually sealing them off entirely if left untreated. Typically affecting young children, the most severe form of PVS progresses very quickly and can cause death within a matter of months after diagnosis.

Until recently, treatment options have been limited to keeping the pulmonary veins open through catheterization or surgery. Yet this approach only removes the cells but does nothing to prevent their regrowth. Now, a clinical trial shows that adding chemotherapy to a treatment regimen including catheterization and surgery can deter abnormal cellular growth and finally give children with PVS a chance to grow up.

Results of the trial, run by the Boston Children’s Hospital Pulmonary Vein Stenosis Program, were recently published in the Journal of Pediatrics.

“Through this approach, we’ve created the first-ever population of survivors who are living with severe PVS,” says Christina Ireland, RN, MS, FNP, who has managed enrolling patients in the trial and treating new patients since the trial ended. “We’ve changed this disease from an acute killer to a chronic, manageable condition.”

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Science Seen: An intestinal toxin’s trick, a potential cancer fighter

Crystal structure of the C. difficile toxin bound to its receptor, causing intestinal damage
Adapted from Science May 11, 2018. DOI: 10.1126/science.aar1999

Clostridium difficile, also called “C. diff,” causes severe gastrointestinal tract infections and tops the CDC’s list of urgent drug-resistant threats. In work published in Nature in 2016, Min Dong, PhD, and colleagues found the elusive portal that enables a key C. diff toxin, toxin B, to enter the intestines’ outer cells and break down the intestinal barrier (above right).

Interestingly, the same portal, known as the Frizzled receptor, also receives signals that maintain the intestine’s stem cells. When toxin B docks, it blocks these signals, carried by a molecule known as Wnt. But exactly how it all works remained a puzzle — until new research published today in Science.

Liang Tao, PhD in Dong’s lab, working with the labs of Rongsheng Jin, PhD, at UC-Irvine, and Xi He, PhD, at Boston Children’s, captured the crystal structure of a fragment of toxin B (in orange above) as it joined to the Frizzled receptor (in green). The structure revealed lipid molecules within the Frizzled receptor (in yellow and red) that play a central role. Normally, when Wnt binds to Frizzled, it nudges these lipids aside. But the team showed that when the toxin fragment binds to Frizzled, it locks these lipids in place, preventing Wnt from engaging with the cell.

Just as stem cells rely on Wnt signaling for growth and regeneration, so do many cancers. Now that its mechanism is known, Dong thinks this toxin B fragment, which by itself isn’t toxic, could be a useful anti-cancer therapeutic. They’re currently developing a new generation of Wnt signaling modulators and testing them in animal models of cancer. (For further information, contact Rajinder.Khunkun@childrens.harvard.edu of Boston Children’s Technology & Innovation Development Office.)

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Very-low-carb diet can safely curb blood sugar in type 1 diabetes, study suggests

very-low-carb diet shows promise in type 1 diabetes

David Ludwig, MD, PhD, an endocrinologist at Boston Children’s Hospital, has written popular books espousing a low-glycemic, low-carbohydrate diet for weight control. He has argued that high-glycemic diets are contributing to the epidemic of type 2 diabetes.  But he hadn’t given much thought to carbohydrate restriction for type 1 diabetes until 2016.

At a conference, Ludwig met a surgeon with type 1 diabetes who maintains normal hemoglobin A1c levels (indicating high blood sugar control) on a very-low-carbohydrate diet. This surprised and impressed him: he had never seen any patient with type 1 diabetes able to completely normalize their hemoglobin A1cs. Moreover, most diabetes experts discourage very-low-carb diets, believing they pose a risk for hypoglycemia, or a dangerous drop in blood sugar.

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Stick-on respiratory monitor allows early detection of breathing problems

Toddler wearing ExSpiron respiratory monitor
A mock-up of the ExSpiron monitoring a toddler’s breathing

Children can be at risk for compromised breathing after surgery or from conditions like asthma, congestive heart failure or sleep apnea. Opioid therapy and sedation for medical procedures can also depress breathing. Unless a child is sick enough to have a breathing tube, respiratory problems can be difficult to detect early. Yet early detection can mean the difference between life and death.

“There is currently no real-time objective measure,” says Viviane Nasr, MD, an anesthesiologist with Boston Children’s Hospital’s Division of Cardiac Anesthesia. “Instead, respiratory assessment relies on oximetry data, a late indicator of respiratory decline, and on subjective clinical assessment.”

A new device, recently cleared by the FDA for children 1 year and older in medical settings, provides an easy, noninvasive way to tell how much air the lungs are receiving in real time. It can signal problems as much as 15-30 minutes before standard pulse oximetry picks up low blood oxygenation, according to one study.

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Viral discussion: Epidemics experts sound off on the future of infection control

Image of flu virus, which experts think will eventually lead to future epidemics
Is the next flu pandemic around the corner?

During the 1918 influenza pandemic, the average life expectancy in the U.S. dropped below 40 years old. Today, public health and medical professionals need to be actively preparing for the next great pandemic, according to leaders of the Massachusetts Medical Society, The New England Journal of Medicine and Microsoft founder Bill Gates, who delivered the keynote address at a Boston-based meeting on April 27 called Epidemics Going Viral: Innovation vs. Nature. Here’s recap of what we heard from various panelists.

The five key drivers of epidemics are population growth/urbanization, travel, animals, environmental/climate changes and conflicts/natural disasters, according to Harvey Fineberg, MD, PhD, President of the Gordon and Betty Moore Foundation and former president of the Institute of Medicine. When it comes to predicting and preventing the next epidemic, Fineberg believes that data from a social media platform like Twitter isn’t going to help identify the next big outbreak.

But John Brownstein, PhD, an epidemiologist and Chief Innovation Officer at Boston Children’s Hospital, disagreed with that idea.

“I believe it’s possible for Twitter to find the next microbe,” Brownstein said. “This information comes in real time and at global scale.” Attendees who were live tweeting with the hashtag #epidemicsgoviral were quick to highlight this difference of opinion.

Uber flu shot, “a cool millennial thing to do”

Anne Schuchat, MD, deputy director of the Centers of Disease Control, busted the myth that non-vaccination rates are rising. She explained that media stories about anti-vaccination supporters can make it seem as though vaccination rates are falling when they actually aren’t.

“Less than one percent of kids aren’t vaccinated in the U.S.,” Schuchat said.

But some vaccinations, like the annual flu shot, still have big gaps to close. Brownstein described how a partnership with Uber — dispatching flu vaccines and nurses to people’s homes — was able to influence people to get their first-ever flu shot.

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Diagnosing autism in infants? EEG algorithms make accurate predictions

autism EEGs
EEG nets are easily slipped over an infant’s head and cause no discomfort. (Credit: Nelson Lab)

The earlier autism can be diagnosed, the more effective interventions typically are. But the signs are often subtle or can be misinterpreted at young ages. As a result, many children aren’t diagnosed until age 2 or even older. Now, a study shows that electroencephalograms (EEGs), which measure the brain’s electrical activity, can accurately predict or rule out autism spectrum disorder (ASD) in babies as young as 3 months old. It appears today in Scientific Reports.

The beauty of EEG is that it’s already used in many pediatric neurology or developmental pediatric settings. “EEGs are low-cost, non-invasive and relatively easy to incorporate into well-baby checkups,” says study co-author Charles Nelson, PhD, director of the Laboratories of Cognitive Neuroscience at Boston Children’s Hospital. “Their reliability in predicting whether a child will develop autism raises the possibility of intervening very early, well before clear behavioral symptoms emerge.”

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