Culture

The link between drawing and seeing in the brain

image: Brain activation patterns during object recognition and production.

Image: 
Fan et al., JNeurosci 2019.

Drawing an object and naming it engages the brain in similar ways, according to research recently published in JNeurosci. The finding demonstrates the importance of the visual processing system for producing drawings of an object.

In a study by Fan et al., healthy adults performed two tasks while the researchers recorded brain activity using functional magnetic resonance imaging: they identified pieces of furniture in pictures and produced drawings of those pieces of furniture. The researchers used machine learning to discover similar patterns of brain activity across both tasks within the occipital cortex, an area of the brain important for visual processing. This means people recruit the same neural representation of an object whether they are drawing it or seeing it.

As the participants drew each object multiple times, the activity patterns in occipital cortex remained unchanged, but the connection between occipital cortex and parietal cortex, an area involved in motor planning, grew more distinct. This suggests that drawing practice enhances how the brain shares information about an object between different regions over time.

Credit: 
Society for Neuroscience

Obesity is a risk factor for cardiotoxicity in chemotherapy-treated patients with breast cancer

image: Obesity is associated with a three-fold increased risk of cardiotoxicity in chemotherapy-treated patients with early-stage breast cancer, regardless of other predictors of cardiotoxicity.

Image: 
OpenClipart-Vectors, Pixabay

Anthracyclines remain a cornerstone of breast cancer therapy in combination with new-generation targeted drugs such as trastuzumab. Both types of drugs are major culprits in chemotherapy-induced heart disease. A recent study showed that being overweight or obese was a risk factor for cardiotoxicity in chemotherapy-treated patients with breast cancer, but it did not take into account related cardiac risk factors or other classic risk factors of cardiotoxicity produced by anthracycline and trastuzumab (e.g., older age, concomitant chemotherapy or previous radiation therapy, smoking, high blood pressure, or diabetes).

In a study published December 23 in the open-access journal PLOS Medicine, Elisé Kaboré of Centre Georges-François Leclerc and Charles Guenancia of University Hospital, Dijon, France, and colleagues address this gap in knowledge. They provide evidence that obesity is associated with a three-fold increased risk of cardiotoxicity in chemotherapy-treated patients with early-stage breast cancer, regardless of other predictors of cardiotoxicity. As noted by the authors, the results suggest that overweight and obese patients may benefit from careful cardiac screening and follow-up during and after chemotherapy.

The authors examined the association of body mass index and cardiotoxicity using prospective data collected from 2012 to 2014 in the French national breast CANcer TOxicity study (CANTO) of 26 cancer centers. The study included 929 patients with stage I to III breast cancer who were treated with anthracycline and/or trastuzumab.

At baseline, nearly half of the study population was overweight or obese. During a mean follow-up period of 22 months following chemotherapy, cardiotoxicity occurred in 29 patients (3.2%). Compared to the normal-weight group, the obese group was more prone to cardiotoxicity (8/466 vs. 9/171; p=0.01), regardless of other predictors of cardiotoxicity. In addition, cardiotoxicity was independently associated with obesity (OR, 3.02; 95%CI, 1.10-8.25; p=0.03) and trastuzumab administration (OR, 12.12; 51 95%CI, 3.6-40.4; p

Credit: 
PLOS

Barring nonmedical exemptions increases vaccination rates, study finds

The first rigorously controlled study of a 2016 California law that aimed to increase childhood vaccination rates by eliminating nonmedical exemptions has found the law worked as intended, although the researchers noted a small increase in the number of medical exemptions.

The study provides definitive evidence on the success of the California law, as policymakers across the United States and around the world debate similarly strict vaccine requirements.

"Vaccine hesitancy and the recent decline in vaccination rates is an increasing threat to public health and our patients," said Nathan C. Lo, MD, PhD, a medical resident at UC San Francisco and senior author of the study, published Monday, Dec. 23, 2019, in PLOS Medicine. "Our study shows that government policy has a role to address this, and that eliminating nonmedical exemptions is an effective way of increasing vaccination coverage."

The researchers estimated how many California children would have received a key vaccine -- measles, mumps and rubella, or MMR -- if the law had not gone into effect, and compared that to how many children actually were vaccinated following the law's enactment. The comparison group was created synthetically with data from 44 other states, so that it resembled California's demographics and trends.

The researchers did something similar at the county level, comparing overall vaccine coverage in California counties to vaccine coverage in similar counties from 16 other states. The state data covered the years 2011 to 2017 and the county data covered 2010 to 2017.

"The big strength of our study over previous analyses is that we designed a quasi-experimental study with control groups, to adjust for ongoing trends in vaccination," said Sindiso Nyathi, a PhD candidate in the Department of Epidemiology and Population Health at Stanford University School of Medicine, who was one of the first authors on the new paper. "This makes our results more reliable."

Both analyses showed that vaccination rates went up following the law's enactment. MMR coverage across the state increased 3.3 percent, compared to the "synthetic" state control; nonmedical exemptions decreased by 2.4 percent; and medical exemptions increased 0.4 percent.

In the county-level analysis, overall vaccination coverage went up on average 4.3 percent, nonmedical exemptions went down 3.9 percent and medical exemptions went up 2.4 percent. The averages masked much larger changes in vaccination coverage in some counties, which ranged from a 6 percent decrease to a 26 percent increase, with the largest increases happening in counties that had the lowest vaccine coverage before the law took effect.

"We did see an increase in medical exemptions, but in absolute terms the numbers remain small -- 1 to 2 percent, driven largely by a few counties -- and we can expect them to remain of similar magnitude in the near term," Lo said. "Overall vaccine coverage increased by 10 to 20 percent in the high-risk counties, far more than the increase in medical exemptions."

These changes were enough to bring the vaccination rate to 95 percent in almost all California counties, which is high enough coverage to create so-called herd immunity, which can prevent disease from spreading among vulnerable groups, like newborns and older children who cannot receive vaccinations for various medical reasons.

"The implication of our study is the law brought about protection through herd immunity," said Hannah Karpel, a student at New York University School of Medicine, and a first author of the paper. "Even small average increases can have a big effect."

Credit: 
University of California - San Francisco

NASA analyzes Tropical Cyclone Phanfone's water vapor concentration

image: NASA's Aqua satellite passed over Tropical Cyclone Phanfone in the Northwestern Pacific Ocean on Dec. 22 at 0445 UTC (Dec. 21 at 11:45 p.m. EST) and the highest concentrations of water vapor (brown) and coldest cloud top temperatures were around the center.

Image: 
NASA/NRL

When NASA's Aqua satellite passed over the Northwestern Pacific Ocean, water vapor data provided information about the intensity of Tropical Cyclone Phanfone. In the Philippines, the storm is known locally as Ursula.

Tropical Depression 30W formed early on Dec. 22 and strengthened into a tropical storm. By 4 a.m. EST (0900 UTC), the storm was renamed Phanfone.

NASA's Aqua satellite passed over Tropical Cyclone on Dec. 22 at 0445 UTC (Dec. 21 at 11:45 p.m. EST) and the Moderate Resolution Imaging Spectroradiometer or MODIS instrument gathered water vapor content and temperature information. The MODIS image showed highest concentrations of water vapor and coldest cloud top temperatures were around the center of circulation.

MODIS data also showed coldest cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in those storms. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and the stronger the storms.

On Dec. 23 at 4 a.m. EST (0900 UTC), Tropical Storm Phanfone (Philippines designation Ursula) was located near latitude 9.8 degrees north and longitude 132.2 degrees east, about 717 nautical miles east-southeast of Manila, Philippines. Phanfone is moving to the west-northwest and had maximum sustained winds near 40 knots (46 mph/74 kph).

On Dec. 23 at 10 a.m. EST (1500 UTC), the GMI or Microwave Imager sensor aboard NASA and the Japan Aerospace Exploration Agency's Global Precipitation Measurement mission or GPM core satellite, showed an eye was developing in Phanfone's center.

Forecasters at the Joint Typhoon Warning Center expect Phanfone will move west-northwest toward and through the central Philippine archipelago and the Visayas and Mindanao regions on Dec. 24 and 25.

NASA's Aqua satellite is one in a fleet of NASA satellites that provide data for hurricane research.

Typhoons and hurricanes are the most powerful weather event on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

Credit: 
NASA/Goddard Space Flight Center

Scientists learn what women know -- and don't know -- about breast density and cancer risk

LEBANON, NH - Breast density is an important risk factor for breast cancer but no study had asked women what they know or think about breast density in relation to screening they have had. A number of states do have notification laws about breast density, but these laws vary. In a new qualitative study, a team of scientists at Dartmouth and Dartmouth-Hitchcock's Norris Cotton Cancer Center and the Breast Cancer Surveillance Consortium led by Karen Schifferdecker, PhD, MPH, and Anna Tosteson, ScD, sought to explore women's knowledge and perceptions of breast density and experiences of breast cancer screening across three states with and without notification laws.

The focus group study found that women from all states had varying knowledge about their own breast density and breast density in general. A number of women were aware of the difficulty of detecting cancer with dense breasts, but only one woman knew that density increased breast cancer risk. "We found that very few women received information about breast density during healthcare visits although some were encouraged to get supplemental imaging or to pay for new types of mammography such as breast tomosynthesis," says Schifferdecker. "Women who were offered more imaging or different technology usually thought these were 'better,' even though they were given little information about the effectiveness or harms."

The study also found, importantly, that women from all states expressed a strong desire for more information about breast density. All of these results are in the article, "Knowledge and Perception of Breast Density, Screening Mammography, and Supplemental Screening: in Search of 'Informed'" newly published in the Journal of General Internal Medicine. "The findings in this paper are exciting because no research on dense breasts has explored women's knowledge and experiences in their own words and compared this across different states," says Schifferdecker. "We partnered with the national Breast Cancer Surveillance Consortium to identify and recruit women who had a recent screening and also had dense breasts. In this way, we knew all women had dense breasts and could explore what they knew or did not know, including their own personal breast density."

The conclusions also identify opportunities for improvements in educating women so they may make informed decisions related to mammography and supplemental screening. "Women want--and deserve--more usable information about breast cancer risk, "says Schifferdecker. "More research needs to be done to understand how the medical community can better assist women in making informed decisions related to breast density and screening."

Credit: 
Dartmouth Health

'Tweezer clock' may help tell time more precisely

image: Adam Shaw, Ivaylo Madjarov and Manuel Endres work on their laser-based apparatus at Caltech.

Image: 
Caltech

Atomic clocks are used around the world to precisely tell time. Each "tick" of the clock depends on atomic vibrations and their effects on surrounding electromagnetic fields. Standard atomic clocks in use today, based on the atom cesium, tell time by "counting" radio frequencies. These clocks can measure time to a precision of one second per every hundreds of millions of years. Newer atomic clocks that measure optical frequencies of light are even more precise, and may eventually replace the radio-based ones.

Now, researchers at Caltech and the Jet Propulsion Laboratory (JPL), which is managed by Caltech for NASA, have come up with a new design for an optical atomic clock that holds promise to be the most accurate and precise yet (accuracy refers to the ability of the clock to correctly pin down the time, and precision refers to its ability to tell time in fine detail). Nicknamed the "tweezer clock," it employs technology in which so-called laser tweezers are used to manipulate individual atoms.

"One of the goals of physicists is to be able to tell time as precisely as possible," says Manuel Endres, an assistant professor of physics at Caltech who led a new paper describing the results in the journal Physical Review X. Endres explains that while the ultra-precise clocks may not be needed for everyday purposes of counting time, they could lead to advances in fundamental physics research as well as new technologies that are yet to be imagined.

The new clock design builds upon two types of optical atomic clocks already in use. The first type is based on a single trapped charged atom, or ion, while the second uses thousands of neutral atoms trapped in what is called an optical lattice. In the trapped-ion approach, only one atom (the ion) needs to be precisely isolated and controlled, and this improves the accuracy of the clock. On the other hand, the optical lattice approach benefits from having multiple atoms--with more atoms there are fewer uncertainties that arise due to random quantum fluctuations of individual atoms.

The atomic clock design from Endres' group essentially combines the advantages of the two designs, reaping the benefits of both. Instead of using a collection of many atoms, as is the case with the optical lattice approach, the new design uses 40 atoms--and those atoms are precisely controlled with laser tweezers. In this regard, the new design benefits not only from having multiple atoms but also by allowing researchers to control those atoms.

"This approach bridges two branches of physics--single-atom control techniques and precision measurement," says Ivaylo Madjarov, a Caltech graduate student and lead author of the new study. "We're pioneering a new platform for atomic clocks."

Madjarov explains that, in general, the atoms in atomic clocks act like tuning forks to help stabilize the electromagnetic frequencies, or laser light. "The oscillations of our laser light act as a pendulum that counts the passage of time. The atoms are a very reliable reference that makes sure that pendulum swings at a constant rate."

The team says that the new system is ideally suited for future research into quantum technologies. The atoms in these systems can become entangled, or globally connected, and this entangled state can further stabilize the clock. "Our approach can also build a bridge to quantum computation and communication architectures," says Endres. "By merging different techniques in physics, we've entered a new frontier."

Credit: 
California Institute of Technology

Resurrected protein reveals structure of important enzyme

image: This illustration shows the phylogenetic tree of FMO enzymes. The ancestral enzymes proved to be stable enough to study and revealed how FMOs metabolize toxic substances. This made it possible to reconstruct the effect of disease-causing mutations in FMO genes, like the mutation causing fish odour syndrome.

Image: 
Fraaije lab, University of Groningen

To disarm toxic substances, many organisms - including humans - possess enzymes called flavin-containing monooxygenases (FMOs). Despite their importance, the structure of the enzymes has not been resolved, as the protein is too unstable to study in detail. University of Groningen enzyme engineer Marco Fraaije and colleagues from Italy and Argentina reconstructed the ancestral genetic sequences for three FMO genes and subsequently studied the enzymes. The ancestral enzymes proved to be stable enough to study and revealed how FMOs metabolize toxic substances. The results were published on 23 December in Nature Structural & Molecular Biology.

FMOs are present in animals, plants and bacteria. In humans, our five different FMOs are not only involved in metabolizing toxic substances but also in drug activation, while mutations in FMO genes may cause illnesses. 'These enzymes are studied in detail by pharmaceutical companies but we still had no detailed structure available,' says Fraaije. Human FMOs are membrane-bound proteins, which proved to be impossible to crystallize for standard structural analysis by X-ray diffraction. 'My group published the structure of a bacterial FMO, some fifteen years ago, but this was not a membrane-bound protein.'

Phylogenetic tree

Several developments prompted Fraaije and his co-workers to have another go at the structure: 'Over the last couple of years, the gene sequences for a large number of different FMOs were published. This allows you to build a phylogenetic tree, but also to reconstruct ancestral gene sequences for the FMOs.' These gene sequences are used to create artificial DNA, which is then translated to proteins in bacterial systems. 'Previous work has shown that such ancestral proteins are generally more stable than the modern ones,' says Fraaije.

Colleagues from the Universidad Nacional de San Luis in Argentina reconstructed the DNA sequences, the University of Groningen group produced and characterized the proteins, while scientists at the University of Pavia in Italy determined the structures. The international team managed to analyse the ancestral forms of three of the five human FMOs.

Tunnel

'The results are fascinating,' says Fraaije. 'The membrane-bound part of the enzyme forms a kind of tunnel through which substances can be transported to the active site.' Many toxic compounds are fatty substances that will accumulate in the fatty cell membrane. 'The FMO enzymes can take them from the membrane and oxidize them.' This makes the toxins more hydrophilic, which makes it easier for the cell to excrete them. Whereas the active site is the same in the three FMOs, they have slightly different tunnels, probably suited to different classes of toxic compounds. 'We knew that different FMOs metabolize different substances and now we can explain why this is so.'

The approach using reconstructed ancestral genes has paid off. 'The amino acid sequence of ancestral proteins and contemporary proteins are 90 percent identical, while their functions are completely identical,' says Fraaije. Scientists and pharmaceutical companies are now finally able to see how the FMOs work. 'This could help in the design of drugs that are activated by these enzymes. And the observation that the ancestral protein is more stable is also of interest. Understanding why this is the case could help us to design more stable enzymes for industrial use.'

Fish odour syndrome

Finally, it is now possible to reconstruct the effect of disease-causing mutations in FMO genes. One of those mutations causes fish odour syndrome, where a mutation in FMO3 results in the inability to metabolize the substance trimethylamine. This substance, which has a strong fish odour, consequently builds up in the body and is released in sweat, urine and breath, among other things. Fraaije: 'This was a high-risk project, as we didn't know if the ancestral protein would be stable enough. But it has paid off.'

Credit: 
University of Groningen

Gone fishin' -- for proteins

image: HeLa cell expressing the proximity interaction probe BirA*-Flag-active RAC1. Actin filaments are in green and biotinylated proteins are in magenta.

Image: 
Amélie Robert (IRCM)

Using a new microscopic "fishing" technique, scientists at the Montreal Clinical Research Institute (IRCM) and Université de Montréal have successfully snagged thousands of proteins key to the formation of the cell skeleton.

Led by UdeM cell biologist Jean-François Côté, the team threw 56 "baits" into human cells they were incubating in their laboratory, catching more than 9,000 proteins in the process. The results are published today in the journal Nature Cell Biology.

The goal was to identify the proteins that attach to those of the Rho family, famous in the cell biology world since the discovery in the early 1990s that they dictate how pieces of the cell skeleton -- the "cytoskeleton" -- are assembled.

In humans, the 20 members of the Rho family are scattered on the inner surface of cell membranes and act like small switches. When a signal from outside or inside the cell activates them, they stimulate other proteins to force the cytoskeleton to add or remove parts to its framework.

Out of all these proteins, only three, to date, have been thoroughly studied by researchers: Cdc42, Rac1 and RhoA. Cdc42 acts as the lead protein: it indicates the path that white blood cells must take to find a site of infection. Rac1 activates the engines that drive a non-muscular cell forward. RhoA stimulates the formation of fibres that allow cells to contract or form resistant tissues as they come together to produce, for example, the wall of a blood vessel.

But what are the other proteins doing? And what other proteins do they interact with? To find out, Coté and his team went fishing for answers.

Two-headed proteins

Into human cells growing in incubators in their lab, they cast their baited lines, forcing these cells to produce proteins with two heads, one containing a single side of a protein in the Rho family, the other a "biotin ligase" enzyme. The latter acts like an elite sniper in the cell, luring and labelling every passing protein with the help of its partner, a member of the Rho family. Every protein that approached the bait was thus labeled with biotin. Next, Côté and his team had to shred the cells to identify, one by one, each labelled protein.

Using 28 two-headed proteins and presenting the GTPases - a superfamily of enzymes that function as 'molecular switches' and are involved in regulating many cellular processes - in both active and inactive configurations, the team caught a total of 9,939 proteins. Some were already known to the scientists, including the GTPases' activators and deactivators. But the researchers also discovered hundreds of individual proteins with yet-to-be-defined roles.

These discoveries include the missing link of the cytoskelton Rho process identified in the early '90s. Back then, researchers noticed that the RhoA protein indirectly activates another protein, ERM, causing it to stabilize the cytoskeleton. But they didn't know the precise mechanism behind this process. On their "fishing expedition," Côté and his team found the answer: what forges the link between RhoA and ERM is a protein called SLK.

In their study, the IRCM team also looked at other proteins that, until now, were virtually unknown to biologists, namely GARRE and PLEKHG3. The scientists demonstrated that these proteins naturally attach to the active forms of Rac1 and RhoG, respectively. What's left to understand is the exact function of these associations. To accelerate the process, the team revealed characteristics of other molecules they caught in their experiments -- enough to give raw material to dozens of laboratories worldwide.

Through their research, Côté and his team have not only cleared up a whole area of cell biology, but have also demonstrated the effectiveness of their unique "fishing" method. Côté now plans to use it to better understand how other molecular switches work, especially those in the Ras family, proteins that lie at the centre of many types of cancer.

Credit: 
University of Montreal

Climate change is not the only threat to vulnerable species, habitat loss also matters

image: A new analysis by an international team shows that climate change is not the only threat to endangered species. Habitat degradation and fragmentation, overharvesting, overhunting, invasive species and pollution also play a role.

Image: 
Andrea Baden/Hunter College

AMHERST, Mass. ¬ - Though climate change is becoming one of the greatest threats to the Earth's already stressed ecosystems, it may not be the most severe threat today for all species, say authors of a new report on the effects of deforestation on two lemur species in Madagascar.

Writing in the current issue of Nature Climate Change, Toni Lyn Morelli at the U.S. Geological Survey's Northeast Climate Adaptation Science Center at University of Massachusetts Amherst and her international team of co-authors point out that species across the globe now face concurrent pressures on many fronts. These include habitat degradation and fragmentation, overharvesting, overhunting, invasive species and pollution in addition to climate change - though the latter receives special attention because of its "global reach, ability to reshape entire ecosystems and potential to impact areas that are otherwise 'protected.'"

To understand these threats, they modeled the effects of deforestation and climate change on the two critically endangered ruffed lemur species in the genus Varecia over the next century. "Because of their essential role as some of Madagascar's last large-bodied seed dispersers and their sensitivity to habitat loss, ruffed lemurs serve as critical indicators of rainforest health," says co-author Andrea Baden of Hunter College CUNY, New York. "Ruffed lemurs and rainforests rely on each other. Remove one and the system collapses."

Undertaking what Morelli calls "a massive effort," she and her 21 colleagues combined 88 years of data to report on how deforestation will affect ruffed lemurs. Morelli, who did her doctoral work in Madagascar, says team members conducted research at thousands of sites on this island off the southeast coast of Africa with a wide range of government, foundation and academic support.

They estimate that suitable rainforest habitat could be reduced by as much as 59 % from deforestation, as much as 75 % from climate change alone, and almost entirely lost from both before 2080. Thus, protecting protected areas is a key conservation strategy, research ecologist Morelli says. She and co-authors write, "Maintaining and enhancing the integrity of protected areas, where rates of forest loss are lower, will be essential for ensuring persistence of the diversity of the rapidly-diminishing Malagasy rainforests."

Morelli adds, "Madagascar is facing devastating rates of forest loss, and lemurs are only found there and nowhere else. At this rate, even without climate change we're going to lose the rainforest and its lemurs, but with climate change we'll lose them even faster. If we can slow the deforestation, we can save some of them. Not all of them, but some of them."

Morelli adds, "This is not just about Madagascar, though it's a really special place, recognized as one of the world's biodiversity hotspots, and people really care about it. But there is a broader message. This research reminds us that there are other threats to biodiversity. We show that deforestation continues to be an imminent threat to conservation."

Baden says that the problem is not that people have not been trying to preserve habitat to save the lemurs. "There are already protected areas," she says. "If we want to save habitat and species, in the face of climate change, we have to do a better job of enforcement. But even with well-enforced protected areas, the outlook is pretty grim." The authors also discuss the likelihood that climate change will alter local residents' ability to grow and gather food, perhaps forcing further encroachment on protected lands.

Overall, "We challenge the conservation community to contemplate what should be done if nearly all of Madagascar's rainforest habitat were to be lost," they write. "To date, most conservation on the island has focused on establishment of protected areas, but even these are being eroded, albeit at a slower rate. If protected areas are not able to serve their intended purpose, how can we ensure that the perpetuation of the richness of Madagascar's biodiversity?"

Journal

Nature Climate Change

Credit: 
University of Massachusetts Amherst

Injection of virus-delivered gene silencer blocks ALS degeneration, saves motor function

image: Martin Marsala, MD, is a professor in the Department of Anesthesiology at UC San Diego School of Medicine.

Image: 
UC San Diego Health Sciences

Writing in Nature Medicine, an international team headed by researchers at University of California San Diego School of Medicine describe a new way to effectively deliver a gene-silencing vector to adult amyotrophic lateral sclerosis (ALS) mice, resulting in long-term suppression of the degenerative motor neuron disorder if treatment vector is delivered prior to disease onset, and blockage of disease progression in adult animals if treatment is initiated when symptoms have already appeared.

The findings are published in the December 23, 2019 online issue of the journal Nature Medicine. Martin Marsala, MD, professor in the Department of Anesthesiology at UC San Diego School of Medicine and a member of the Sanford Consortium for Regenerative Medicine, is senior author of the study.

ALS is a neurodegenerative disease that affects nerve cells in the brain and spinal cord. Motor neurons responsible for communicating movement are specifically harmed, with subsequent, progressive loss of muscle control affecting the ability to speak, eat, move and breathe. More than 5,000 Americans are diagnosed with ALS each year, with an estimated 30,000 persons currently living with the disease. While there are symptomatic treatments for ALS, there is currently no cure. The majority of patients succumb to the disease two to five years after diagnosis.

There are two types of ALS, sporadic and familial. Sporadic is the most common form, accounting for 90 to 95 percent of all cases. It may affect anyone. Familial ALS accounts for 5 to 10 percent of all cases in the United States, and is inherited. Previous studies show that at least 200 mutations of a gene called SOD1 are linked to ALS.

The SOD1 gene normally serves to provide instructions for making an enzyme called superoxide dismutase, which is widely used to break down superoxide radicals -- toxic oxygen molecules produced as a byproduct of normal cell processes. Previous research has suggested that SOD1 gene mutations may result in ineffective removal of superoxide radicals or create other toxicities that cause motor neuron cell death, resulting in ALS.

The new approach involves injecting shRNA -- an artificial RNA molecule capable of silencing or turning off a targeted gene -- that is delivered to cells via a harmless adeno-associated virus. In the new research, single injections of the shRNA-carrying virus were placed at two sites in the spinal cord of adult mice expressing an ALS-causing mutation of the SOD1 gene, either just before disease onset or when the animals had begun showing symptoms.

Earlier efforts elsewhere had involved introducing the silencing vector intravenously or into cerebrospinal fluid in early symptomatic mice, but disease progression, while delayed, continued and the mice soon died. In the new study, the single subpial injection (delivered below the pia matter, the delicate innermost membrane enveloping the brain and spinal cord) markedly mitigated neurodegeneration in pre-symptomatic mice, which displayed normal neurological function with no detectable disease onset. The functional effect corresponded with near-complete protection of motor neurons and other cells, including the junctions between neurons and muscle fibers.

In adult mice already displaying ALS-like symptoms, the injection effectively blocked further disease progression and degeneration of motor neurons.

In both approaches, the affected mice lived without negative side effects for the length of the study.

"At present, this therapeutic approach provides the most potent therapy ever demonstrated in mouse models of mutated SOD1 gene-linked ALS," said senior author Martin Marsala, MD, professor in the Department of Anesthesiology at UC San Diego School of Medicine.

"In addition, effective spinal cord delivery of AAV9 vector in adult animals suggests that the use of this new delivery method will likely be effective in treatment of other hereditary forms of ALS or other spinal neurodegenerative disorders that require spinal parenchymal delivery of therapeutic gene(s) or mutated-gene silencing machinery, such as in C9orf72 gene mutation-linked ALS or in some forms of lysosomal storage disease."

The research team also tested the injection approach in adult pigs, whose spinal cord dimensions are similar to humans, for safety and efficacy. Using an injection device developed for use in adult humans, they found the procedure could be performed reliably and without surgical complications.

Marsala said next steps involve additional safety studies with a large animal model to determine the optimal, safe dosage of treatment vector. "While no detectable side effects related to treatment were seen in mice more than one year after treatment, the definition of safety in large animal species more similar to humans is a critical step in advancing this treatment approach toward clinical testing."

Credit: 
University of California - San Diego

Measuring mutations in sperm may reveal risk for autism in future children

image: In this illustration of sperm mosaicism, mutated sperm are depicted in red.

Image: 
UC San Diego Health Sciences

The causes of autism spectrum disorder or ASD are not fully understood; researchers believe both genetics and environment play a role. In some cases, the disorder is linked to de novo mutations that appear only in the child and are not inherited from either parent's DNA.

In a study published December 23, 2019 in Nature Medicine, an international team of scientists, led by researchers at University of California San Diego School of Medicine, describe a method to measure disease-causing mutations found only in the sperm of the father, providing a more accurate assessment of ASD risk in future children.

"Autism afflicts 1 in 59 children and we know that a significant portion is caused by these de novo DNA mutations, yet we are still blind to when and where these mutations will occur," said co-senior author Jonathan Sebat, PhD, professor and chief of the Beyster Center for Molecular Genomics of Neuropsychiatric Diseases at UC San Diego School of Medicine. "With our new study, we can trace some of these mutations back to the father, and we can directly assess the risk of these same mutations occurring again in future children."

Recent studies suggest gene-damaging de novo mutations are involved in at least 10 to 30 percent of ASD cases, with the number of mutations rising with the father's age at time of conception. De novo mutations occur spontaneously in parents' sperm or eggs or during fertilization. The mutation is then present in each cell as the fertilized egg divides. Studies now point to male sperm as a particularly important source of these mutations, with the chance of the mutation recurring within the same family generally estimated at 1 to 3 percent.

"However, such estimates are not based on actual knowledge of the risk in an individual family, but instead are based on frequencies in the general population," said co-senior study author Joseph Gleeson, MD, Rady Professor of Neuroscience at UC San Diego School of Medicine and director of neuroscience research at the Rady Children's Institute for Genomic Medicine. "When a disease-causing mutation occurs for the first time in a family, the probability that it could happen again in future offspring is not known. Thus families must make a decision with a great deal of uncertainty."

For their study, Gleeson, Sebat and colleagues analyzed the sperm of eight fathers who were already parents of children with ASD. The goal was to look for the presence of multiple, genetically different material in cells in the same person, a phenomenon called mosaicism. Using deep whole genome sequencing, they found variants in offspring that were matched only in the fathers' sperm.

"While medical textbooks teach us that every cell in the body has an identical copy of DNA, this is fundamentally not correct. Mutations occur every time a cell divides, so no two cells in the body are genetically identical," said first author Martin Breuss, PhD, an assistant project scientist in Gleeson's lab.

"Mosaicism can cause cancer or can be silent in the body. If a mutation occurs early in development, then it will be shared by many cells within the body. But if a mutation happens just in sperm, then it can show up in a future child but not cause any disease in the father."

The researchers determined that disease-causing mutations were present in up to 15 percent of the fathers' sperm cells, information that could not be determined through other means, such as blood samples.

"My laboratory has a long-standing interest in understanding the origins of pediatric brain disease, and how mutations contributes to disease in a child," said Gleeson. "We previously showed that mosaicism in a child can lead to diseases like epilepsy. Here, we show that mosaicism in one of parents is at least as important when thinking about genetic counseling."

If developed into a clinical test, the researchers said fathers could have their sperm studied to determine their precise risk of recurrence in future children. The methods might also be applied to men that haven't had children yet, but who want to know the risk of having a child with a disease.

Credit: 
University of California - San Diego

EMBL co-develops new method that could facilitate cancer diagnosis

"Our new method to study genetic variations in individual cells could transform the field of mutation detection," highlights Ashley Sanders, one of the lead authors of the study, working at EMBL Heidelberg, Germany. The method she and her colleagues developed - termed scTRIP (single cell tri-channel processing) - allows them to study genetic variations within the DNA of a single cell and measure genetic variations directly as they form in new cells. In contrast to existing methods that were able to detect only large-scale changes in the genome, scTRIP can detect small-scale changes, along with many types of genetic variations that were invisible using other single cell methods.

The researchers tested their method in studying patient-derived leukaemia cells. In their sample, the team found four times more variants in the patient than were detected by standard clinical diagnostics. These included a missed clinically relevant translocation that drove the overexpression of a cancer-causing gene. They also observed a catastrophic chromosome rearrangement that was missed in the initial leukaemia diagnosis. It probably occurred when a single chromosome shattered and was then glued back together in a rearranged order.

"These first results show that our method is outperforming existing ones significantly. Our method is much faster and cheaper than methods currently in use to uncover genetic variants in single cells. This might be very useful for clinical applications," summarises Tobias Marschall, from the Center for Bioinformatics at Saarland University and the Max Planck Institute for Informatics. The team has begun to expand their use of the method to analyse different forms of leukaemia and evaluate its potential clinical utility.

As the heterogeneity of a sample can best be studied at a single-cell level, researchers all over the world - including several groups at EMBL - are working on the development of technologies to improve the information received. "While existing techniques show how different cells can behave or respond to manipulation or treatment, research and application have so far centred on measuring the RNA within a cell. However, measuring the DNA in a single cell has so far received much less attention," explains Tobias Marschall. As it is expected that looking at the DNA will provide a new level of understanding in how these genetic changes drive different cell behaviours, the new method addresses the needs of both researchers and medical doctors.

scTRIP is based on a technology Ashley Sanders co-developed during her PhD in Vancouver. "scTRIP combines signals from three distinct channels of information from within the genomic code of the individual cell," explains Jan Korbel, group leader at EMBL Heidelberg. "Doing so, our method allows us to uncover the full spectrum of DNA rearrangements in individual cells."

Now, using scTRIP, the researchers are continuing their research on a very basic question: How much does one cell in the body differ from any other cell, in the context of cancer as well as in normal cells? Until now, they were unable to address this question because they lacked the technology to do so. "Using scTRIP we can now directly measure the mutational processes that act in cells to generate new genetically distinct populations," says Ashley Sanders. For the next steps in their research, the team plans to study mutational processes in different human cell types, and to assess the consequences these differences have in terms of human diseases.

Credit: 
European Molecular Biology Laboratory

Benefits of electrification don't accrue equally for women, finds survey of homes in India

image: Household ownership of male vs. female-used appliances for number of years the household has received electricity.

Image: 
<i>Nature Sustainability</i>

Increasing access to clean and affordable energy and improving gender equality are two major sustainable development goals (SDGs) that are believed to be strongly linked. With electricity access, less time and effort in the developing world is needed for tasks related to cooking, water collection, and other housework, which are typically undertaken by women.

"The prevailing view with electricity access is that if households receive a grid connection, it should especially benefit women," said Daniel Armanios, assistant professor of Engineering and Public Policy (EPP) at Carnegie Mellon University.

A new study published in Nature Sustainability, however, shows that the linkages between these goals can be more complex than anticipated. "It's not enough to just look at access, because that does not adequately consider the local social context and household power dynamics," said Armanios, the study's corresponding author. "You have to look at whether the use (of that electricity) is equitable as well." The research team also includes fellow CMU EPP professor, Paulina Jaramillo, as well as first-author Meital Rosenberg and Michaël Aklin, a professor of political science, both from the University of Pittsburgh.

Using data collected from electrified areas of rural India, the team shows that as households gain access to basic levels of electricity, men in the households tend to dominate electricity use patterns, which could in turn suggest men benefit more than women from such access.

The researchers employed a two-part mixed-methods approach to understand how electrified households use energy. First, Rosenberg traveled to Gujarat, India, where she conducted detailed interviews with over 30 women in electrified households. These interviews revealed what appliances were in each household and, importantly, who typically used them.

The study categorized common appliances according to typical use patterns as more male-used, more female-used, or neutral. Households tended to have more male-used appliances than neutral, and more neutral than female-used appliances. Some of this disparity the researchers attribute to the specialty nature of some appliances that are more female-used, like sewing machines, mixers, and grinders. However, the gender gap of electricity use existed even for the least expensive appliances, such as fans and light bulbs. While the poorest households in the survey had multiple bulbs and fans, they were rarely found in kitchen spaces, despite interviewees saying that this location would make their household duties easier and free up time for other activities.

Through the interviews, the team learned that only about a quarter of the women felt that electricity had granted them added time to pursue activities that they wanted to do outside of housework. Many of the women interviewed reported explicitly that the appliances purchased in their house were used predominantly by their children and husband. For these electrified households in Gujarat, where resources are scarce, male use of electricity is prioritized.

"Other researchers have shown that electricity access can provide important benefits for poorer households and improve female well-being," said Jaramillo. "However, we suggest that dynamics within the households can affect the way household members use electricity and thereby maintain or exacerbate unequal gender relationships."

The results from the field interviews in Gujarat provided a rubric for the team to assess whether their findings generalized across a much wider swath of India. In a previous study, Aklin and colleagues surveyed thousands of households in six energy-poor Indian states. Respondents identified what appliances their household used upon being connected to the grid.

Combining Aklin's survey with Rosenberg's insights from Gujarat, the team found that the same patterns of gender inequality within households persisted in this larger dataset: households had more male-used appliances compared to more female-used appliances, even when controlling for household income. However, in female-led households, these patterns of electricity use did not hold: in some cases, female-led households were more likely to have light bulbs and fans in the kitchen, unlike male-led households. These results show that women will choose to use electricity differently than is typical in male-led households, and how male-female power differences in this context influence electricity use patterns.

This gender electricity use gap persists for years, too; households continued to have more male-used appliances than female-used appliances a decade after first receiving electricity, even for households higher on the socioeconomic scale. "Access to electricity is a necessary precondition to achieving many development goals," said Jaramillo, "but it is not a sufficient one to help developing countries overcome social norms that can drive who benefits from development." Social contexts ultimately shape how sustainable development interventions unfold.

"India has the largest unelectrified population of any country," said Armanios, "and so the lessons we learn about electricity access have a lot to do with what happens there." Beyond understanding the linkage between energy access and gender equality in India, the study also provides a useful framework for considering sustainable development interventions and research going forward. "When people study sustainable development goals, they tend to look at them in isolation," he said. "Our study advocates for more analysis as to their interactions and develops a framework for which to do that."

Credit: 
College of Engineering, Carnegie Mellon University

3D atlas of the bone marrow -- in single cell resolution

Stem cells located in the bone marrow generate and control the production of blood and immune cells. Researchers from EMBL, DKFZ and HI-STEM have now developed new methods to reveal the three-dimensional organization of the bone marrow at the single cell level. Using this approach the teams have identified previously unknown cell types that create specific local environments required for blood generation from stem cells. The study, published in Nature Cell Biology, reveals an unexpected complexity of the bone marrow and its microdomains at an unprecedented resolution and provides a novel scientific basis to study blood diseases such as leukemias.

In the published study researchers from European Molecular Biology Laboratory (EMBL), the German Cancer Research Center (DKFZ) and the Heidelberg Institute for Stem Cell Technology and Experimental Medicine* (HI-STEM gGmbH) present new methods permitting the characterisation of complex organs. The team focused their research on the murine bone marrow, as it harbours blood stem cells that are responsible for life-long blood production. Because of the ability to influence stem cells and to sustain blood production, there is a growing interest in exploiting the bone marrow environment, also called niche, as a target for novel leukaemia treatments. "So far, very little was known about how different cells are organised within the bone marrow and how they interact to maintain blood stem cells," explains Chiara Baccin, post-doc in the Steinmetz Group at EMBL. "Our approach unveils the cellular composition, the three-dimensional organisation and the intercellular communication in the bone marrow, a tissue that has thus far been difficult to study using conventional methods," further explains Jude Al-Sabah, PhD student in the Haas Group at HI-STEM and DKFZ.

In order to understand which cells can be found in the bone marrow, where they are localised and how they might impact on stem cells, the researchers combined single-cell and spatial transcriptomics with novel computational methods. By analysing the RNA content of individual bone marrow cells, the team identified 32 different cell types, including extremely rare and previously unknown cell types. "We believe that these rare 'niche cells' establish unique environments in the bone marrow that are required for stem cell function and production of new blood and immune cells," explains Simon Haas, group leader at the DKFZ and HI-STEM, and one of the initiators of the study.

Using novel computational methods, the researchers were not only able to determine the organisation of the different cell types in the bone marrow in 3D, but could also predict their cellular interactions and communication. "It's the first evidence that spatial interactions in a tissue can be deduced computationally on the basis of genomic data," explains Lars Velten, staff scientist in the Steinmetz Group.

"Our dataset is publicly accessible to any laboratory in the world and it could be instrumental in refining in vivo studies," says Lars Steinmetz, group leader and director of the Life Science Alliance at EMBL Heidelberg. The data, which is now already used by different teams all over the world, is accessible via a user-friendly web app.

The developed methods can in principle be used to analyse the 3D organisation of any organ at the single cell level. "Our approach is widely applicable and could also be used to study the complex pathology of human diseases such as anemia or leukemia" highlights Andreas Trumpp, managing director of HI-STEM and division head at DKFZ.

Credit: 
German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ)

New nano-barrier for composites could strengthen spacecraft payloads

The University of Surrey has developed a robust multi-layed nano-barrier for ultra-lightweight and stable carbon fibre reinforced polymers (CFRPs) that could be used to build high precision instrument structures for future space missions.

CFRP is used in current space missions, but its applications are limited because the material absorbs moisture. This is often released as gas during a mission, causing the material to expand and affect the stability and integrity of the structure. Engineers try to minimise this problem with CFRP by performing long, expensive procedures such as drying, recalibrations and bake-out- all of which may not completely resolve the issue.

In a paper published by the journal Nature Materials, scientists and engineers from Surrey and Airbus Defence and Space detail how they have developed a multi-layered nano-barrier that bonds with the CFRP and eliminates the need for multiple bake-out stages and the controlled storage required in its unprotected state.

Surrey engineers have shown that their thin nano-barrier - measuring only sub-micrometers in thickness, compared to the tens of micrometers of current space mission coatings - is less susceptible to stress and contamination at the surface, keeping its integrity even after multiple thermal cycles.

Professor Ravi Silva, Director of the Advanced Technology Institute at the University of Surrey, said: "We are confident that the reinforced composite we have reported is a significant improvement over similar methods and materials already on the market. These encouraging results suggest that our barrier could eliminate the considerable costs and dangers associated with using carbon fibre reinforced polymers in space missions."

Christian Wilhelmi, Head of Mechanical Subsystems and Research and Technology Friedrichshafen at Airbus Defence and Space, said: "We have been using carbon-fibre composites on our spacecraft and instrument structures for many years, but the newly developed nano-barrier together with our ultra-high-modulus CFRP manufacturing capability will enable us to create the next generation of non-outgassing CFRP materials with much more dimensional stability for optics and payload support. Reaching this milestone gives us the confidence to look at instrument-scale manufacturing to fully prove the technology."

Professor David Sampson, Vice-Provost Research and Innovation at the University of Surrey, said: "This research project continues the University of Surrey's long and close partnership with Airbus. Advanced materials for spacecraft is a further excellent example of how Surrey supports the Space Sector. We have been doing so for decades, and we are fully committed to strengthening our support for the sector going forwards. I look forward to more brilliant advances from the Surrey-Airbus relationship in years to come."

Credit: 
University of Surrey