Culture

Rotavirus is a major cause of diarrhea and vomiting, especially in children, that results in approximately 128,000 deaths annually. The virus triggers the disease by infecting enterocyte cells in the small intestine, but only a fraction of the susceptible cells has the virus. In the mid-90s, scientists proposed that the small portion of infected cells promotes severe disease by sending out signals that disrupt the normal function of neighboring uninfected cells, but the nature of the signal has remained a mystery.

In the current study published in the journal Science, a team led by researchers at Baylor College of Medicine discovered that rotavirus-infected cells release signaling molecules, identified as adenosine diphosphate (ADP), which binds its cellular receptor P2Y1 on neighboring cells. Activating P2Y1 by ADP results in signals called intercellular calcium waves in these uninfected cells. Disrupting ADP binding to its receptor reduced the severity of diarrhea in a mouse model of the disease, suggesting that targeting the P2Y1 may be an effective strategy to control viral diarrhea in human populations.

"In our previous studies using fluorescent calcium sensors and time-lapse imaging, we discovered that rotavirus-infected cells display aberrant calcium signals that we can visualize as bright pulses of intercellular calcium waves that radiate from the infected cells," said corresponding author Dr. Joseph Hyser, assistant professor of virology and microbiology and member of the Alkek Center for Metagenomic and Microbiome Research at Baylor. "Calcium signaling was known to be associated with various aspects of rotavirus infection and our work revealed the dynamic nature of the alterations induced by rotavirus."

In the current study, the researchers conducted the experiments using a lower dose of the virus and noticed that it was not just the virus-infected cells that showed dynamic calcium signaling, but also the adjacent uninfected cells surrounding the infected cells produced pulses of calcium waves that were coordinated with those of the infected cells. This observation suggested that the infected cells could be triggering intercellular calcium waves in the uninfected cells.

The researchers connected their observation to a concept proposed in the mid-90s suggesting that rotavirus-infected cells send signals to neighboring uninfected cells that disrupt their function, promoting diarrhea and vomiting.

"Our videos of live fluorescent microscopy showing intercellular calcium wave signaling in both rotavirus-infected and uninfected cells provided an unprecedented means to investigate the nature of the proposed signal, which had not been identified," said first author Dr. Alexandra L. Chang-Graham, an M.D./Ph.D. student in the Medical Scientist Training Program who completed her Ph.D. thesis working in the Hyser lab.

Finding the signal

Chang-Graham, Hyser and their colleagues worked with three different laboratory models to identify the signal that triggers intercellular calcium waves on uninfected cells. They used a monkey kidney cell line commonly used to study rotavirus. They also worked with human intestinal enteroids, a cultivation system that recapitulates many of the characteristics of the human infection and a neonatal mouse model of rotavirus infection and diarrhea.
Their studies showed that suspected triggers of calcium waves, such as prostaglandin E2 and nitric oxide, did not elicit a calcium response. Then they tested ATP and ADP, known mediators of calcium signaling that had not been previously associated with rotavirus infection. They found that rotavirus-infected cells triggered intercellular calcium waves by releasing ADP that binds to its receptor, P2Y1, on uninfected neighboring cells. Knocking out the P2Y1 gene, which prevents ADP from signaling, reduced intercellular calcium waves.

"Across the three model systems we consistently found evidence that rotavirus-infected cells signal uninfected cells with ADP and that this contributes to the severity of the disease," Chang-Graham said. "We consider it paradigm shifting that the actual signal, ADP, was not even on the radar before."

ADP signaling is involved in triggering severe rotavirus symptoms

Further studies revealed previously unknown roles of ADP on rotavirus infection and replication, shining a spotlight on ADP as an important trigger of the multiple factors involved in severe diarrhea and vomiting caused by rotavirus. For instance, the researchers found evidence that ADP signaling increases rotavirus infection, the expression of inflammatory cytokine IL1-alpha and the secretion of serotonin, an inducer of diarrhea. ADP signaling also increases the expression of enzymes that produce prostaglandin and nitric oxide, potentially causing the increases in those compounds observed in rotavirus infection. Preventing ADP signaling and intercellular calcium waves reduced the production of the compounds mentioned above.

"Finally, we determined that inhibiting the P2Y1 receptor reduced the severity of rotavirus-induced diarrhea in a mouse model," Chang-Graham said. "Using intercellular calcium waves, rotavirus amplifies its ability to cause disease beyond the cells it directly infects. This is the first virus identified to activate ADP-mediated intercellular calcium waves. This may be a strategy that other viruses also use to cause disease in their hosts."

"Our findings add a new and very potent signaling pathway into the causative mechanisms of rotavirus diarrhea," Hyser said. "In terms of treatment, this is exciting because currently some drugs targeting P2Y1 are undergoing preclinical testing as anticlotting drugs. It's possible that such drugs could be repurposed, if proven to be safe for children, to be used to treat diarrhea caused by rotavirus infection."

Predicting preterm birth can be difficult, especially for women who have not given birth. It has long been known that the best predictor of preterm birth is someone who has had a prior preterm birth; however, this information is helpful only in second and subsequent pregnancies. For women in their first pregnancy, it is a challenge for obstetricians and midwives to advise them on their risks. To address this issue, researchers at Baylor College of Medicine and Texas Children's Hospital studied how family history can predict preterm birth. Their findings were published in the American Journal of Obstetrics & Gynecology.

"This is a retrospective study of prospective data," said Dr. Kjersti Aagaard, professor of obstetrics and gynecology at Baylor and Texas Children's Hospital. "We developed a biobank and data repository called PeriBank where we consistently asked our pregnant patients a set of questions about their familial history. We were able to take that detailed data and determine if that specific woman's family history did or did not predict her delivering preterm."

Once familial information was gathered, the research team was able to answer questions to quantify estimates of risk for preterm birth based on the pregnant patient's family history of preterm birth in herself, her sister(s), her mother, grandmothers and aunts and great-aunts. Their findings showed scenarios for women who have previously given birth (multiparous), as well as women who have never given birth (nulliparous). If a nulliparous woman herself was born preterm, her relative risk for delivering preterm was 1.75-fold higher. If her sister delivered preterm, her relative risk was 2.25-fold higher. If her grandmother or aunt delivered preterm, there was no significant increase of risk. If a multiparous mother with no prior preterm births was born preterm herself, her risk was 1.84-fold higher. However, if her sister, grandmother or aunt delivered preterm, there was no significant increase.

"We've managed over the years to collect data from a very large population of pregnant women that reflect Houston. There was considerable diversity by race, ethnicity, culture and socioeconomic status. This was a key strength of our study. With this breadth and depth of data reflective of the diversity of Houston, we were able to ask some good questions, which gave us really important information about 'heritability' of risk," Aagaard said.

The research team showed that preterm births cannot be fully attributed to genetics, Aagaard said. Family members may share DNA or genetic code, but the same generation of family members are more likely to share social determinants or have experienced systemic racism and bias. This was best demonstrated by their finding that a history of preterm birth in the pregnant woman or her sister was significantly associated with preterm birth, while a grandmother or aunt was not. These same-generation predictors are generally thought to reflect more about common environmental or social exposures (or a combination of limited genetics plus common exposures) than genetic linkages.

"We know that for the majority of women who deliver a baby preterm, we cannot say that the cause of that preterm birth was in whole or in part genetics. Rather, this study provides subtle but important clues that it is more likely the shared familial background and its exposures that render risk," Aagaard said. "We hope others will similarly be mindful of those subtle characteristics when looking at heritability and risk. We remain committed to finding the underlying true causal and driving factors. In the meantime, we provide for the first time some reliable risk estimates for first time moms based on their and their family history of preterm birth."

URBANA, Ill. - College students are significantly less likely to be food insecure than non-students in the same age group, according to a new study from the University of Illinois.

"College hunger" has been widely reported in the media, and several studies found very high food insecurity rates among college students, sometimes up to 50 or 60%. "That did not make sense to those of us doing research on food insecurity, so I wanted to check those findings," says Craig Gundersen, agricultural economist at U of I.

Gundersen, who conducts research on food insecurity measures, notes many of those studies used small, non-representative samples with low response rates. To provide more accurate results, he analyzed data from the 2014 to 2018 Current Population Survey (CPS), a national survey covering about 50,000 households. CPS is the official data source for food insecurity measures in the U.S.

His findings were clear.

"No matter how you look at it, college students have far lower rates of food insecurity than both non-college students of similar ages and the general population," he says.

According to his study, 9.9% of full-time college students ages 18 to 25 are food insecure, compared to 16.8% for non-students of the same age group. In the general population, about 12.5% were food insecure during the study's time frame.

Gundersen found the same trend for 26- to 30-year-olds (where just 7% are full-time students) though the gap is smaller than for the younger age group.

Only for part-time students, especially in the 26- to 30-year old group, are food insecurity rates almost equivalent to those of non-students.

Because CPS collects data per household, parents may be responding for adult children living at home. To account for this, Gundersen compared data from young people living on their own and those living with parents. The overall trend was similar, but the difference was even starker ¬¬- 9.1% of students versus 18.4% of non-students were food insecure according to parent responses.

The pattern holds true across demographic groups, except for disabled students, where the food insecurity rate is closer to that of non-students.

This doesn't mean college hunger is a myth. Gundersen emphasizes one in 10 college students is still food insecure.

However, the problem is much more serious for non-students in the same age groups, and that has implications for food aid relief and intervention policies.

"The main conclusion from this study is that full-time college students have food insecurity rates that are far below those of non-college students of similar ages, and quite a bit below those of the general population," he concludes. "Therefore, in thinking about who we should be especially concerned about with respect to policy and other interventions are those who are not in college, in the age group from 18 to 25, rather than college students."

In a new publication from Cardiovascular Innovations and Applications; DOI https://doi.org/10.15212/CVIA.2019.0596, Diyu Cui, Yimeng Liao, Jianlin Du and Yunqing Chen from The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China consider major complications between traditional pacemakers and leadless pacemakers.

Leadless pacemakers, which are increasingly used in clinical practice, have several advantages compared with traditional pacemakers in avoiding pocket- and lead-related complications. However, the clinical effect of leadless pacemakers remains controversial.

The authors meta-analysis of the material appears to favour leadless pacemakers over traditional pacemakers with regard to major complications. This indicates that leadless pacemakers have potential for future clinical applications. However, the application of a leadless pacemaker is still controversial, and more randomized controlled studies are warranted to explore safety and practicality.

WASHINGTON, DC and SAN DIEGO, CA - Nov. 19, 2020 - More than 1.1 million Medicare patients could die over the next decade because they cannot afford to pay for their prescription medications, according to a new study released today by the West Health Policy Center, a nonprofit and nonpartisan policy research group and Xcenda, the research arm of the drug distributor AmerisourceBergen.

If current drug pricing trends continue, researchers estimate cost-related non-adherence to drug therapy will result in the premature deaths of 112,000 beneficiaries a year, making it a leading cause of death in the U.S., ahead of diabetes, influenza, pneumonia, and kidney disease. Millions more will suffer worsening health conditions and run up medical expenses that will cost Medicare an additional $177.4 billion by 2030 or $18 billion a year for the next 10 years.

Researchers also modeled what would happen if Medicare was allowed to bring down drug prices for its beneficiaries through direct negotiation with drug companies, as described in H.R. 3, the Elijah E. Cummings Lower Drug Costs Now Act, passed by the U.S. House of Representatives last year. They found Medicare negotiation could result in 94,000 fewer deaths annually. Additionally, the model found that the policy would reduce Medicare spending by $475.9 billion by 2030.

"One of the biggest contributors to poor health, hospital admissions, higher healthcare costs and preventable death is patients failing to take their medications as prescribed," said Timothy Lash, President, West Health Policy Center. "Cost-related nonadherence is a significant and growing issue that is direct result of runaway drug prices and a failure to implement policies and regulations that make drugs more affordable."

The price of prescription medications has skyrocketed in recent years. Between 2007 and 2018, list prices for branded pharmaceutical products increased by 159% and there are few signs of it slowing. According to the Centers for Medicare & Medicaid Services (CMS), spending on prescription drugs will grow faster than any other major medical good or service over the next several years.

Under Medicare, beneficiaries must pay 25% of the cost of generic and brand-name medications. For many people with multiple chronic conditions, this could add up to thousands of dollars a year in out-of-pocket costs.

"The costs of doing nothing about high drug prices are too high especially when policy changes such as allowing Medicare to negotiate drug prices would result in saving millions of lives and billions of dollars," said Sean Dickson, Director of Health Policy at West Health Policy Center and Chair of the Council for Informed Drug Spending Analysis (CIDSA), an independent group of experts on drug spending from leading academic institutions.

For the study, researchers developed a 10-year model representative of the majority of Medicare beneficiaries with chronic conditions. The model allows users to estimate how different levels of price reductions would lower the number of premature deaths and decrease Medicare spending on a sliding scale. The interactive tool and the complete technical report can be found on the CIDSA website.

Afro-Caribbean people with end stage kidney disease (ESKD) are more likely to be hospitalised with COVID-19 than other ethnicities, a study has found.

Research published today in Nephrology by King's College London and Guy's and St Thomas' NHS Foundation Trust investigated the link between ethnicity and ESKD. They found patients of Afro-Caribbean ethnicity have a four-fold increased risk of being hospitalised with COVID-19 when compared to kidney transplant patients attending for routine care.

The study examined 39 people with diabetes related ESKD hospitalised with COVID-19 at Guy's and St Thomas' between March and April 2020. Of the hospitalised cohort, 73% of patients with a kidney transplant and 54% of haemodialysis patients were of Afro-Caribbean ethnicity. By comparison in patients attending hospital for routine care 18% of kidney transplant patients and 42% of haemodialysis patients are of Afro-Caribbean ethnicity.

The study concluded that ESKD is associated with a high mortality rate of 36% among severely ill patients hospitalised with COVID-19.

First author of the study, Dr Antonella Corcillo from the School of Cardiovascular Medicine and Sciences at King's College London said: "There is very little information on the clinical features and outcomes in patients with ESKD admitted with COVID-19 in the UK. Patients with ESKD are at high risk of severe COVID-19 and often have a poor prognosis. The mortality rate of patients hospitalised, as they had very severe COVID-19, was high at 36% and similar to other recent studies internationally. We observed a disproportionately high prevalence of people of Afro-Caribbean ethnicity being hospitalised. We also saw that low blood glucose levels (hypoglycaemia) were common during hospitalisation in this high-risk population and that adjustment of diabetes treatment was frequently required."

Senior author, Dr Janaka Karalliedde from King's College London, said: "People with ESKD are a high-risk group and are vulnerable to severe COVID-19 infection. When we compared the prevalence of Afro-Caribbean ethnicity in kidney transplant patients admitted with severe COVID-19 to the population of transplant patients attending for routine care at our hospital we observed a more than a four-fold increase in patients of Afro-Caribbean origin being admitted with COVID-19. Further studies and research are urgently required to understand and explain this observation of disproportionate risk in patients of Afro-Caribbean origin. Our data also confirm that the management of diabetes in the setting of severe COVID-19 infection is very challenging and reinforce the importance of integrated multidisciplinary care and teamwork for patients with diabetes hospitalized with COVID-19."

Limitations of this study include its relatively small sample size and that, as it is a cross-sectional study, it is unable to identify causal relationships between ethnicity and severe COVID-19 outcomes.

Feeding truffles to wallabies may sound like a madcap whim of the jet-setting elite, but it may give researchers clues to preserving remnant forest systems.

Dr Melissa Danks from Edith Cowan University in Western Australia led an investigation into how swamp wallabies spread truffle spores around the environment. Results demonstrate the importance of these animals to the survival of the forest.

"There are thousands of truffle species in Australia and they play a critical role in helping our trees and woody plants to survive," she said.

"Truffles live in a mutually beneficial relationship with these plants, helping them to uptake water and nutrients and defence against disease.

"Unlike mushrooms where spores are dispersed through wind and water from their caps, truffles are found underground with the spores inside an enclosed ball - they need to be eaten by an animal to move their spores."

Dr Danks and colleagues at the University of New England investigated the role of swamp wallabies in dispersing these spores.

"Wallabies are browsing animals that will munch on ferns and leaves as well as a wide array of mushrooms and truffles," she said.

"This has helped them to be more resilient to changes in the environment than smaller mammals with specialist diets like potoroos.

"We were interested in finding out whether swamp wallabies have become increasingly important in truffle dispersal with the loss of these other mammals."

Conservation by poo tracking

The team fed truffles to wallabies and timed how long it would take for the spores to appear in the animals' poo. Most spores appeared within 51 hours, with some taking up to three days.

Armed with this information, the researchers attached temporary GPS trackers to wallabies to map how far they move over a three-day period.

Results showed the wallabies could move hundreds of metres, and occasionally more than 1200 metres, from the original truffle source before the spores appeared in their poo, which makes them a very effective at dispersing truffles around the forest.

Dr Danks said this research had wide ranging conservation implications for Australian forests.

"As forest systems become more fragmented and increasingly under pressure, understanding spore dispersal systems is really key to forest survival," Dr Danks said.

"Many of our bushland plants have a partnership with truffles for survival and so it is really critical to understand the role of animals in dispersing these truffle spores.

"Our research on swamp wallabies has demonstrated a simple method to predict how far an animal disperses fungal spores in a variety of landscapes."

Research into Alzheimer's disease has long focused on understanding the role of two key proteins, beta amyloid and the tau protein. Found in tangles in patients' brain tissue, a pathological form of the tau protein contributes to propagating the disease in the brain.

In new research from their joint laboratory, Judith Steen, PhD, and Hanno Steen, PhD show for the first time that this pathological tau protein changes its forms over time, which could mean it will take multiple drugs to target it effectively.

For years, pharmaceutical companies have largely focused with very limited success on developing Alzheimer's drugs against beta amyloid. More recently, drug discovery has shifted to drugs against tau. This new tau discovery may help prevent the same fate for drugs now in development against tau because it shows that the protein may present with one set of targets at early stages, with other targets at later stages in the disease process.

"The tau protein in Alzheimer's disease looks different at every stage," says lead investigator Judith Steen. "We discovered that tau undergoes a series of chemical modifications in a stepwise process that correlates with disease severity. This suggests that we need to have different diagnostics and treatments for every stage of disease."

Published in a paper in Cell, this research represents years of work in the Steen lab funded by the Tau Consortium. Its mission is to accelerate discoveries of new treatments for Alzheimer's and other disease related to "tauopathies" -- abnormalities of the tau protein.

Tau changes according to dementia stage

The Steen lab team looked at tau aggregates in tissues of two areas of the human brain, the frontal gyrus and the angular gyrus, from 49 patients with AD and 42 age-matched individuals without known Alzheimer's or dementia. They found that the chemistry of the tau protein changed in Alzheimer's patients. The tau had several modifications not found on normal tau, known as post-translational chemical modifications or PTMs. The specific chemically modified forms of tau correlated with dementia stage.

Stepwise chemical modifications

As we age, tau tangles accumulate in our brains, even if we don't develop dementia. "But these aggregates are not as abundant and don't look like the tau aggregates in patients who have severe Alzheimer's disease," says Steen. She believes that tau undergoes chemical changes after it's first made in the body. Their team revealed 95 PTMs of the tau protein; about one-third of them were not described before.

"Chemical processing by a variety of enzymes introduces modifications to the original tau protein," says Steen. Examples included addition of phosphate, methyl, acetyl, and ubiquitin groups, and others. The first step of disease appears to start with adding phosphate, with other changes following in a step-wise process. "We were able to see precisely what those modifications were, the extent of the changes, and we also could map it to a precise area of the tau protein," Steen says.

More than one drug likely needed

The team's discovery has immediate implications for the future of Alzheimer's treatment.

"It is likely that to successfully target tau protein with an antibody or small molecule, you may need more than one to clear it," explains Steen. "Early intervention may need different therapeutics compared with late stage Alzheimer's because of the distinct PTM profiles associated with each stage of disease."

The team is hopeful that exploring some these crucial chemical modifications may help explain how Alzheimer's develops and progresses as well as further reveal the chemistry of the tau protein in its earliest stages.

FLEXITau technology platform

Key to the study was use of a novel mass spectrometry technique developed within the lab to measure proteins. Called FLEXITau, and first described in a paper in 2016, it can sequence and quantify tau's makeup with unprecedented accuracy. FLEXITau utilizes biochemistry, mass spectrometry and data analysis to provide information on chemical modifications of tau in brain tissue.

The Steen lab leveraged the platform to study brain tissues collected by NIH-funded brain banks from patients with neurodegenerative diseases, using it to analyze thousands of proteins from these tissues.

The FLEXITau approach provides a deeper understanding of tau pathology that the team believes may lead to novel therapeutics. It may also be useful for developing better diagnostic tools to identify biomarkers of Alzheimer's and other tau-associated diseases.

Implicit racial attitudes within a community can effectively explain racial disparities seen in rates of COVID-19 in the United States, according to a new study published this week in the open-access journal PLOS ONE by George Cunningham and Lisa Wigfall of Texas A&M University, USA.

There is a growing body of evidence showing that racial and ethnic minorities are more affected by severe illness, and more likely to be hospitalized, from COVID-19 compared to white people. This disparity can be only partially explained by the disproportionate rates of underlying medical conditions, such as asthma, diabetes, and obesity, seen among Black/African American people.

In the new study, researchers collected data from a variety of publicly available sources for 817 counties (26% of all counties) in the United States. The data included information on cumulative COVID-19 deaths and cases from January 22 to August 31, 2020 as well as explicit and implicit racial attitudes--collected through Harvard University's Project Implicit. The researchers also obtained a wide spectrum of demographic and economic information for these communities so that they could control for these factors.

The percent of Black residents in a county was positively associated with COVID-19 cases (r=0.47) and deaths (r=0.32) in the county. Moreover, both explicit and implicit racial attitudes were positively associated with COVID-19 (r=0.72). The results demonstrated that the relationship between race and COVID-19 cases was strongest when either explicit or implicit racial attitudes were highest. There was also an effect of implicit racial attitudes on COVID-19 deaths among the Black population. The authors conclude that implicit racial attitudes in a community can help explain racial disparities in COVID-19 rates.

The authors add: "These findings show that, even beyond the impact of county demographics, implicit and explicit racial attitudes impact the rates of COVID-19. Racial attitudes captured at the county level represent the bias of crowds and reflect deeper biases that are embedded into systems within society. These biases can negatively affect county residents, including their health and wellbeing."

Inspired by muscle-powered acceleration in biological jumpers, scientists have designed an elastic-driven strong contractile hydrogel that works by storing and releasing elastic potential energy in a polymer network.

By reversibly forming and breaking chemical bonds in hydrogel networks, the hydrogel designed by Prof. ZHOU Feng's group from the Lanzhou Institute of Chemical Physics (LICP) of the Chinese Academy of Sciences and Prof. HE Ximin's group from the University of California, Los Angeles (UCLA) can store and release elastic energy, thus performing swift and powerful motions.

The newly designed hydrogel can generate high contractile force rapidly at ultrahigh work density, outperforming current hydrogels and even matching biological muscles.

Environment-sensitive hydrogels, also called "stimuli-responsive" or "smart" hydrogels, are attractive because they have a large degree of deformability. However, they suffer mechanical weakness or slow response when used as "artificial muscles" in actuators, robots and medical devices.

In contrast, the results of this study show that the mechanism of the current hydrogel solves the longstanding dilemma of "high speed + large force simultaneously." It is thus able to break the material energy density limit while maintaining high water content.

In addition, it enables controllable multistable deformation in a fully reversible and programmable manner, which for the first time realizes "reversible elasticity-plasticity switchability," as well as anisotropic or isotropic deformation. This universal modular material design can be broadly applied to create unlimited powerful active polymers.

"With the high-power density and programmability via this customizable modular design, these hydrogels demonstrate potential for broad applications in artificial muscles, contractile wound dressing, and high-power actuators," said Prof. ZHOU.

Results have been published online in Science Advances in an article entitled "Bioinspired high-power-density strong contractile hydrogel by programmable elastic recoil."

Researchers at Washington University School of Medicine in St. Louis have identified a molecule that protects mice from brain infections caused by Venezuelan equine encephalitis virus (VEEV), a mosquito-borne virus notorious for causing fast-spreading, deadly outbreaks in Mexico, Central America and northern South America. As the climate changes, the virus is likely to expand its range and threaten more countries in the Americas, including the U.S.

Public health officials have struggled to contain such outbreaks in the absence of effective drugs and vaccines. As a potential drug, the molecule -- described in a paper published Nov. 18 in the journal Nature -- could serve as a much needed tool to control the deadly virus.

"This virus can infect many species of wild mammals, and every few years it jumps from animals to humans via mosquitoes and causes thousands of infections and many deaths," said senior author Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine and a professor of molecular microbiology, and of pathology and immunology. "There's concern that with global warming and population growth, we'll get more outbreaks."

Once injected under the skin by mosquitoes, the virus homes in on neurons. People start experiencing symptoms such as headache, muscle pain, fatigue, vomiting, nausea, diarrhea, sore throat and fever within a week. In the most serious cases, the virus gets past the blood-brain barrier, causing encephalitis -- brain inflammation that can be fatal in up to a quarter of patients.

To find the potential drug, Diamond and colleagues -- including first authors Hongming Ma, PhD, an instructor in medicine, and Arthur S. Kim, PhD, a postdoctoral researcher -- began by searching for the protein "handle" on the surface of animal cells that the virus attaches to and uses to get inside cells. A drug that stops the virus from grabbing that handle, the scientists reasoned, could stymie infection and prevent disease.

But first they had to make a form of the virus they could work easily with. During the Cold War, the U.S. and the Soviet Union attempted to weaponize the virus, and it is still classified as a select agent, meaning only certain high-security labs are allowed to work with it. So instead, the researchers and their colleagues took Sindbis virus, a related virus that causes mild fever and rash, and swapped out some of its genes for some from VEEV. The resulting hybrid virus, called Sindbis-VEEV, infects cells like authentic VEEV but is unable to cause severe disease.

Using a genetic engineering technique known as genome-wide CRISPR screening, the researchers deleted genes in mouse neuronal cells until they found one -- called Ldlrad3 -- whose absence kept Sindbis-VEEV from infecting cells. The missing gene codes for a little-studied surface protein.

Further experiments verified the importance of Ldlrad3. Adding the gene back to neuronal cells restored the virus's ability to infect cells. The human LDLRAD3 gene is almost identical to its mouse equivalent, and knocking out the human gene also reduced infection in multiple cell lines. When the researchers added Ldlrad3 to a different cell type that is normally resistant to infection, the virus was able to infect the cell. Co-author William Klimstra, PhD, at the University of Pittsburgh, separately replicated the findings using authentic, highly virulent VEEV.

Ldlrad3 doesn't appear to be the only way the virus gets inside cells, since a small amount of virus is able to infect cells lacking the protein. But it is clearly the primary way in. Since Ldlrad3 is naturally on our cells and can't be removed, the scientists decided to create a decoy handle using a piece of the Ldlrad3 protein. Any virus particles that mistakenly latch onto the decoy handle would fail to infect cells and instead would get destroyed by the immune system.

To test their decoy in a living animal, the researchers injected mice with authentic virulent VEEV in two different ways: under the skin to mimic a mosquito bite, or directly into the brain. They gave the mice the decoy handle or a placebo molecule for comparison, either six hours before or 24 hours after infection. In all experiments, all of the mice that received the placebo died within a week. In most cases, all of the mice that received the decoy molecule survived, although in the most stringent experiment -- in which the virus was injected into the brain -- two of the 10 mice died despite receiving the decoy.

"In an outbreak situation, you may be able to use a drug like this as a countermeasure to prevent transmission and further spread," Diamond said.

A major advantage to an antiviral drug based on a human -- rather than a viral -- protein is that it is unlikely the virus could evolve resistance to it. Any mutation that enables the virus to avoid the decoy probably would make it unable to attach to cells, too, the researchers said.

Skoltech researchers and their colleagues from Russia, the US, and Sweden have described an unusual RNA polymerase that helps a poorly studied crAss-like bacteriophage transcribe its genes. They "caught" this enzyme by a tiny -- less than 3% of its size -- portion of the amino acid sequence that was similar to other RNA polymerases. The paper detailing the discovery has been published in the journal Nature.

CrAss-like phages get their name from one recently discovered virus, crAssphage. The name means "cross-assembly phage", in honor of the method used for genome assembly. This virus was found when researchers were analyzing publicly available human fecal metagenomes (that is, indiscriminate genetic sequences of everything that was found in a sample). Surprisingly, crAssphage found only in 2014, turned out to be the most abundant phage in the human gut. Later scientists, including the team of this paper's coauthor, Eugene Koonin, found more of these viruses, none of which had been studied in a lab before.

"Since crAss-like phages are the most abundant viruses in the human gut, understanding how they infect their host cells will allow controlling the composition of the human microbiome, which in turn is important for human health and disease. We also became interested in studying crAss-like phages because it was predicted that these viruses use highly unusual RNA polymerases (enzymes that make RNA from a DNA template) to transcribe their genes," Maria Sokolova, assistant professor at the Skoltech Center of Life Sciences, says.

Sokolova and her colleagues took phi14:2, a crAss-like phage that preys on Cellulophaga baltica, a bacterium commonly found on beaches. This virus turned out to be a convenient model for lab research, and the team studied its putative RNA polymerase gp66, a rather large protein with a previously unknown function. By looking at its amino acid sequence, the researchers spotted a snippet that looked like a part of cellular multisubunit RNA polymerases. Researches first purified gp66 and demonstrated its RNA polymerase activity in vitro.

"The crAss-like phage RNA polymerase turned out to be inactive in a standard test for RNA polymerase activity, which works well for all other RNA polymerases. We knew that viral enzymes may have unusual features, and thus we continued to seek the activity in other tests -- and found it. We were very happy to find it eventually because before that moment, we were concerned whether the bioinformatics prediction was valid, since the similarity of gp66 to known enzymes was too low," Sokolova notes.

In vitro experiments showed that rifampicin, an antibiotic, shut down C. baltica's own RNA polymerase but did not affect gp66. And when the researchers looked at what phi14:2 genes ended up transcribed in an infected cell dosed with rifampicin, they found a lot of so-called early genes, ones that encode the machinery a virus needs to overtake the host cell at the early stages of an infection, but the fewer middle and late genes, active at later stages. This implies that phi14:2 is a Bring Your Own RNA Polymerase virus, relying on gp66 to work at the start of an infection before it can utilize the polymerase of the host cell.

The scientists managed to solve the crystal structure of the gp66 protein and discovered that most of its structural elements have no known counterparts, and their functions are unknown. However, the core of gp66 turned out to be very similar to an RNA polymerase that in higher organisms is involved in a process of RNA interference, which allows to silence the function of some genes. According to Konstantin Severinov, a coauthor of the paper, "this is a startling result that suggests that enzymes of RNA interference, a process that was thought to be specific for cells of higher organisms (eukaryotes), have originated, at least partially, from a phage, in other words, were "borrowed" from a bacterial virus, an ancestor of current crAss-like phages, sometime early in evolution. This discovery shows that the evolution of higher cells was a complex process that involved multiple acquisitions of bacterial and even phage enzymes by ancestral cells. Another textbook example of this is the acquisition of whole bacteria by an ancestral eukaryotic cell, that now became mitochondria."

Researchers also found that, in the crystal structure of gp66, its catalytic site is in an inactive conformation that has never been seen in any RNA polymerase. They suggested that prior to the packaging into the phage particle, gp66 is in a self-inhibited form.

"To this end, this enzyme possesses properties common to proteins that form virus shells (e.g. hemagglutinin, flavi- and alphavirus glycoproteins). These proteins undergo assembly-dependent maturation that is required for activity. CrAss-like phage RNA polymerase undergoes such maturation upon incorporation into the virus particle or upon translocation through the tail channel," notes Petr Leiman of the Sealy Center for Structural Biology and Molecular Biophysics at the University of Texas Medical Branch, a co-author of the paper.

Maria Sokolova says that this is the first study that addresses the function of crAss-like viruses at the molecular and atomic level of detail. "Our work paves a way to the regulation of crAss-like phage infection which in its turn may inform new approaches for manipulating the composition of the human gut microbiome," she adds.

BOSTON (Nov. 18, 2020, 2:00 p.m. ET)--Researchers at Tufts University School of Medicine have discovered a molecular mechanism that causes a "traffic jam" of enzymes traveling up and down neuronal axons, leading to the accumulation of amyloid beta - a key feature and cause of Alzheimer's disease. The enzyme, BACE1, gets backed up, causing the axons to clog and swell because of the increased production of the toxic amyloid protein.

The study, published today in Science Translational Medicine, reports that a human mutation more prevalent in African American patients with late onset Alzheimer's triggers a traffic jam of BACE1 in axons. Identifying this mutation is a key step in understanding the underlying molecular mechanisms of the disease and provides a possible strategy for early diagnosis and targeted treatments.

"In individuals with Alzheimer's disease, the onset of symptoms happens about 20 years after the first changes start to develop in the brain, making therapeutic intervention extremely difficult," said Giuseppina Tesco, professor of neuroscience at Tufts University School of Medicine and senior and corresponding author on the study. "So, we wanted to identify the mechanisms leading to the swelling of axons during the pre-symptomatic phase of Alzheimer's disease, which could in turn provide a way to detect the disease early and possibly treat it more effectively."

Tufts researchers previously identified a gene, Gga3, which helps regulate the traffic of BACE1, or beta-site APP-cleaving enzyme 1, along the axon. In the new study, the researchers found that when the Gga3 gene is mutated or missing in mice, their brains present the same distinctive traffic jam of BACE1 in swelling axons that are found in the postmortem brains of early stage patients with Alzheimer's disease. The researchers found that by disrupting the Gga3 gene, the traffic of BACE1 and other proteins along the axon is slowed or shut down. They also noted that a mutated or missing Gga3 leads to a severe accumulation of BACE1 in the axon, which results in axonal swellings both in cultured neurons and in a mouse model of Alzheimer's disease prior to amyloid deposition.

In multiple clinical trials, BACE inhibitors administered to patients with advanced disease who already had significant accumulation of amyloid beta protein and neuronal damage have been unsuccessful. The researchers asked whether application of the inhibitors at the earliest stages of disease might be more effective. They found that the inhibitors prevented swelling of axons in mice and even improved the two-way flow of BACE1. Their results suggest that earlier application of BACE1 inhibitors could be more effective at slowing the accumulation of amyloid beta protein.

Using datasets from the National Institutes of Health's National Institute of Mental Health and the Alzheimer's Disease Neuroimaging Initiative, the researchers discovered that mutations in Gga3 were more common among African Americans diagnosed with Alzheimer's disease than other populations. Although the sample size was small, the researchers believe this finding may provide a case for identifying early stage interventions and treatments for this group of patients.

"Our study provides a possible molecular explanation for the prevalence of axonopathy during the early stages of Alzheimer's disease, before the formation of amyloid plaques," said Tesco. "The mutation allowed us to determine that axonal alterations can be caused by accumulation of BACE1. Now an area of focus could be inhibiting BACE1 to prevent early axonal damage and perhaps this could also slow the development of amyloid plaques leading to disease."

The researchers note that the presence of neurofilament light chain (NfL) in blood plasma is a marker for axonal damage, and could be used to identify the best timing for use of BACE inhibitors to prevent or slow the progression of Alzheimer's disease during its early pre-symptomatic stages.

A high concentration of salt or sugar in the environment will dehydrate microorganisms and stop them from growing. To counter this, bacteria can increase their internal solute concentration. Scientists from the University of Groningen elucidated the structure of a transport protein OpuA, that imports glycine betaine to counter osmotic stress. The protein belongs to the well-known family of ABC transporters, but it has a unique structure and working mechanism. The results were published in Science Advances on 18 November.

Food preservatives are designed to make life difficult for microorganisms. Salt and sugar are well-known preservatives; they increase the electrolyte concentration to above that inside bacteria. The result is that water flows out of these bacteria until concentrations are approximately equal, leaving behind shrivelled cells that can no longer grow.

ABC transporter

'However, some bacteria have evolved defences against such preservatives,' says Bert Poolman, Professor of Biochemistry at the University of Groningen. Around 20 years ago, a food producer asked him to find ways to defeat those defences. It led to the discovery of OpuA, a transport protein that is triggered by dehydration and responds by importing a substance called glycine betaine. 'This increases the osmolyte concentration inside the cells without compromising the structure of proteins. The result is that the cells absorb more water and start to grow again,' explains Poolman.

OpuA belongs to a well-known class of proteins called ABC (ATP-binding cassette) transporters. This protein family is one of the largest known in biology. Humans have around 50 of these transporters, some plants have hundreds of them and bacteria have a number somewhere in between. OpuA is special because it can import glycine betaine in huge amounts, leading to a very high internal osmolyte concentration. That is why Poolman was intrigued to find out how it worked. 'I have worked on this problem, on and off, ever since.'

Breakthrough

The problem was elucidating the structure of the protein. Until a few years ago, the standard method was to grow crystals from proteins and investigate those using X-ray diffraction. It is very difficult to grow crystals from proteins that are embedded in the cell membrane and for OpuA, it turned out to be impossible. Based on the amino acid sequence and the structure of other ABC transporters, the scientist compiled a model of the structure, but this could not explain the way that OpuA functioned.

The breakthrough came with the introduction of cryo-electron microscopy, together with the work of PhD student Hendrik Sikkema and the collaboration with the research group of University of Groningen assistant professor of Cryo-EM Cristina Paulino. A large number of single proteins were scanned in an electron microscope at a very low temperature, after which all the images were combined to provide a direct view of the structure. The results showed not one but five different structures. 'The protein is a dynamic structure, as it changes conformation to suit the function, but the different parts also vibrate on their own,' explains Poolman. 'This means that one protein exists in many variant structures. And you cannot grow crystals amidst such diversity.'

Beautiful

The first conclusion from the cryo-EM studies was that most of what they thought they knew about the structure of OpuA was incorrect. 'For example, parts that we believed to be on the inside of the cell membrane sat on the outside.' The real structure was beautiful, according to Poolman. The second conclusion was that OpuA is in part regulated by cyclic di-AMP, a second messenger molecule that was only recently discovered. 'The protein primarily responds to ionic strength, which varies as a function of osmotic stress, but it uses cyclic di-AMP as a second brake to completely stop importing glycine betaine and prevent the cell from exploding under non-stress conditions.'

The ionic strength sensor of the OpuA protein carries a positive charge while the membrane has a negative charge. When water is drawn from the cells, the concentration of salts, such as potassium chloride, increases. 'This disrupts the interaction of the ionic strength sensor with the membrane, which activates the pumping mechanism.' Once the glycine betaine concentration is high enough to make the cell swell to its normal proportions, the protein-membrane interaction is normalized. 'However, the pump does not shut down completely, so it continues to import some glycine betaine. This will increase the pressure inside the cell and eventually cause it to pop.' That is why cyclic di-AMP is used to fully shut down the pump.

The paper describes the different structures and provides functional data on the transport protein. This combination gives a good insight into the workings of OpuA: a satisfying result for Poolman. 'It is the accumulation of twenty years of research, which has produced seven or eight PhD theses.' The results show how the resistance of bacteria to preservatives, such as salt or sugar, could be overcome. 'Furthermore, we are part of a consortium that is trying to construct a synthetic cell. OpuA is an important part of the design; it is meant to regulate the cell's internal pressure.'

For many years, investigators have been trying to pin down the tantalizing connection between vitamin D and cancer. Epidemiological studies have found that people who live near the equator, where exposure to sunlight produces more vitamin D, have lower incidence and death rates from certain cancers. In cancer cells in the lab and in mouse models, vitamin D has also been found to slow cancer progression. But the results of randomized clinical trials in humans haven't yielded a clear answer. The Vitamin D and Omega-3 Trial (VITAL), which concluded in 2018, found that vitamin D did not reduce overall incidence of cancer, but hinted at a decreased risk of cancer deaths. Now, in a secondary analysis of VITAL, a team led by investigators at Brigham and Women's Hospital has narrowed in on the connection between taking vitamin D supplements and risk of metastatic or fatal cancer. In a paper published in JAMA Network Open, the team reports that vitamin D was associated with an overall 17 percent risk reduction for advanced cancer. When the team looked at only participants with a normal body mass index (BMI), they found a 38 percent risk reduction, suggesting that body mass may influence the relationship between vitamin D and decreased risk of advanced cancer.

"These findings suggest that vitamin D may reduce the risk of developing advanced cancers," said corresponding author Paulette Chandler, MD, MPH, a primary care physician and epidemiologist in the Brigham's Division of Preventive Medicine. "Vitamin D is a supplement that's readily available, cheap and has been used and studied for decades. Our findings, especially the strong risk reduction seen in individuals with normal weight, provide new information about the relationship between vitamin D and advanced cancer."

The VITAL study was a rigorous, placebo-controlled study that took place over a span of more than five years. The VITAL study population included men who were 50 or older and women 55 or older who did not have cancer when the trial began. The study population was racially and ethnically diverse. VITAL was designed to test the independent effects of vitamin D and omega-3 supplements as well as to test for synergy between the two. Participants were divided into four groups: vitamin D (2000 IU/day) plus omega-3s; vitamin D plus placebo; omega-3s plus placebo; and placebos for both. Primary endpoints were major adverse cardiovascular events and incidence of cancer. VITAL did not find a statistical difference in overall cancer rates, but researchers did observe a reduction in cancer-related deaths.

In their secondary analysis, Chandler and colleagues followed up on the possible reduction in cancer deaths with an evaluation of advanced (metastatic or fatal) cancer among participants who did or did not take vitamin D supplements during the trial. They also examined the possible modifying effect of BMI.

Among the more than 25,000 participants in the VITAL study, 1,617 were diagnosed with invasive cancer over the next five years. This included a broad mix of cancers (breast, prostate, colorectal, lung and more). Of the almost 13,000 participants who received vitamin D, 226 were diagnosed with advanced cancer compared to 274 who received the placebo. Of the 7,843 participants with a normal body mass index (BMI less than 25) taking vitamin D, only 58 were diagnosed with advanced cancer compared with 96 taking the placebo.

While the team's findings on BMI could be due to chance, there is previous evidence that body mass may affect vitamin D action. Obesity and associated inflammation may decrease the effectiveness of vitamin D, possibly by reducing vitamin D receptor sensitivity or altering vitamin D signaling. In addition, randomized trials of vitamin D and type 2 diabetes have found greater benefits of vitamin D in people with normal weights and no benefit among those with obesity.

Vitamin D deficiency is common among cancer patients, with one study reporting rates of vitamin D deficiency as high as 72 percent among cancer patients. There is also evidence that higher amounts of body fat are associated with increased risk for several cancers.

"Our findings, along with results from previous studies, support the ongoing evaluation of vitamin D supplementation for preventing metastatic cancer -- a connection that is biologically plausible," said Chandler. "Additional studies focusing on cancer patients and investigating the role of BMI are warranted."