Culture

New Orleans, LA - A team of LSU Health New Orleans researchers reports for the first time that deleting one of the inhibitors of the RPE65 gene in a mouse model that carries a human disease mutation prevents degeneration of cone photoreceptors that are used for daytime high-resolution color vision. Their findings are published in PNAS available here.

More than 100 DNA variants in the RPE65 gene are reported as pathogenic mutations causing retinal degenerative diseases. They include a group of inherited childhood blinding diseases called Leber congenital amaurosis (LCA). While a new gene therapy may improve vision for some with RPE65 gene mutations, there is currently no effective therapy that arrests progressive retinal degeneration in LCA.

Previously, the researchers identified three inhibitors of RPE65. The one involved in the current study is called fatty acid transport protein 4 (FATP4). They found that the survival of cone photoreceptors is increased nearly 10-fold in the mouse model of LCA lacking FATP4 in the retina. They also discovered that partial reduction of FATP4 in the retina can improve the survival and visual function of cone photoreceptors. These findings establish FATP4 as a promising therapeutic target to preserve daytime color vision in patients.

"The role of FATP4 in disease progression of retinal dystrophies associated with RPE65 mutations was completely unknown," notes Nicolas Bazan, MD, PhD, Boyd Professor, Ernest and Yvette C. Villere Endowed Chair for Retinal Degenerative Diseases and Director of the Neuroscience Center of Excellence at LSU Health New Orleans School of Medicine. "This study is the first to uncover that FATP4 plays a pivotal role in photoreceptor survival and function in retinal dystrophies."

According to the National Institutes of Health, Leber congenital amaurosis primarily affects the retina, the specialized tissue at the back of the eye that detects light and color. Beginning in infancy, people with LCA typically have severe visual impairment. The National Library of Medicine says Leber congenital amaurosis occurs in 2 to 3 per 100,000 newborns. It is one of the most common causes of blindness in children.

"Our findings have allowed us to envision a strategy to mitigate the cone photoreceptor degeneration and vision loss in patients with RPE65 mutations as well as in other mutations," adds Minghao Jin, PhD, Professor of Neuroscience and Ophthalmology at LSU Health New Orleans School of Medicine.

DOAC (direct oral anticoagulant) pills are used in the treatment of atrial fibrillation by preventing blood clots. Even though blood clots are thought to contribute to complications from the new coronavirus infection, users of this class of drug do not seem to be protected against severe COVID-19, reports a large Swedish registry study from Karolinska Institutet published in The Journal of Internal Medicine.

Early during the ongoing pandemic, there were reports that many patients with severe COVID-19 had blood clots in their pulmonary arteries and other parts of the body.

"Our hypothesis was that blood clots per se could contribute to the severe functional deterioration of the lungs and other organs that is associated with COVID-19, so one would think that preventative treatment with anticoagulants would provide some protection," says Benjamin Flam, doctoral student at the Department of Physiology and Pharmacology, Karolinska Institutet, and specialist doctor in anaesthesiology and intensive care at Karolinska University Hospital.

To find out if this was the case, the team from KI conducted a registry based study of patients on anticoagulant medication for reasons other than COVID-19. The study included over 100,000 Swedes between the ages of 45 and 84 with atrial fibrillation being treated with DOACs. The control groups included over 350,000 individuals with cardiovascular disease who were not on such medication.

The researchers then examined the rates of hospitalisation, intensive care and fatality due to COVID-19 between 1 February and 31 May 2020, adjusting for such factors as age, sex, place of residence and other diseases and medication.

The results of the observational study show that DOAC use did not reduce the rate of hospitalisation, intensive care or fatality due to COVID-19.

"Our findings suggest that early DOAC treatment doesn't protect against severe COVID-19, but these should be treated with caution since there might remain differences between the groups that are difficult to measure," says Benjamin Flam. "Also, our study says nothing about whether other types of anticoagulants could be effective, but a good many clinical studies are being done around the world."

When pathogens enter a plant, infected cells set off an alarm before they die. They discharge methylsalicylic acid, which is later transformed into salicylic acid, triggering an immune response. Hence, salicylic acid is a stress signal in plants, but it also participates in regulating plant growth and development. In humans, salicylic acid proofed to be useful in a different way: Already in prehistoric times people realized that when they were drinking willow bark tea or taking other willow bark preparations, fever dropped and pain disappeared. Centuries later, scientists developed salicylic acid derivatives such as Aspirin and Ibuprofen. These so called non-steroidal anti-inflammatory drugs (NSAIDs) suppress the inflammatory response of mammalian cells, thereby making us feel better when we have a cold. But how do they affect plants?

Losing the sense of direction

"When I got the idea, I had a really serious toothache and I had some Ibuprofen at hands," explains Shutang Tan, who at that time was a postdoc at the Institute of Science and Technology (IST) Austria working in the group of Professor Ji?í Friml. "I simply used the tablets from the pharmacy and I took the same amount as in my previous experiments with salicylic acid. Then, I observed the effect of the Ibuprofen on Arabidopsis seedlings." The primary roots of the plant were significantly shorter and instead of growing downward, they were curling up, unable to respond to gravity. Furthermore, the plants developed fewer or no lateral roots at all.

Together with colleagues at the IST Austria and six other research institutions Shutang Tan looked at the effects of 20 different painkillers on Arabidopsis seedlings. "We found that all of the painkillers we tested, including Aspirin and Ibuprofen, were interfering with the auxin flow," explains Tan. The plant hormone auxin is essential for all developmental processes within a plant. It is especially responsible for a plants ability to stretch its leaves towards the sun and its roots towards the center of the earth. So called PIN proteins regulate the flow of auxin from one cell to the other, depending on which side of the cell they are sitting. If the PIN proteins are not at the right location within the cell, the flow of auxin is disturbed, leading to a faulty development of the plant. Hence, the painkillers seemed to interfere with the localization of the PIN proteins. But it didn't stop there.

Complex dynamics within plant cells

Looking closely, the scientists discovered that the effect is not limited to PIN proteins, but that the drugs interfere with the whole endomembrane system, suppressing the movement and trafficking of substances within the cells. The painkillers impair the dynamics of the cytoskeleton of the cells, a network of interlinking proteins, which among many other things gives the cell its shape and is involved in the uptake of extracellular material. Together with Markus Geisler's group at the University of Fribourg, Switzerland, the researchers at IST Austria uncovered that one group of painkillers, including the drugs Meclofenamic acid and Flufenamic acid, directly target an immunophilin-like protein, called TWISTED DWARF1, to realize these physiological and cellular activities.

Furthermore, the scientists were able to show, that NSAIDs have similar physiological and cell biological effects as auxin transport inhibitors - important chemical tools in cell biology, which interfere with the transport of auxin. "It would be very interesting to find out, if these auxin transport inhibitors can also be used as painkillers in animals. That is one big question we still need to answer" concludes Tan. Together with IST Professor Ji?í Friml, Shutang Tan, who is now establishing his own laboratory at the University of Science and Technology of China, wants to investigate which additional proteins within the plant are targeted by the painkillers and what pathways they use to do so.

Rates of soil erosion and alluvium accumulation in North America accelerated 10-fold after Europeans colonized the continent, according to new research carried out by scientists from China, Belgium and USA.

In a paper published today in Nature Communications, the researchers show how humans have altered the North American landscape at a rate far in excess of what nature alone can achieve. The results, they suggest, may have implications for instructing land management and restoration efforts.

Prof. David Kemp from China University of Geosciences in Wuhan said "On nearly every continent, humans are altering the natural landscape, and modifying the land to meet our needs for agriculture, energy and water security. One key consequence of our actions is an increase in sediment movement, particularly soil erosion.

"We knew already that when European colonizers started farming in North America there was an increase in erosion. This led to the deposition of large amounts of river and floodplain sediment, known as alluvium. Our study quantifies this increase across the continent as a whole, and reveals an order of magnitude jump in rates of alluvium deposition soon after Europeans arrived".

Prof. Veerle Vanacker, of Université catholique de Louvain, explained "When we use these data to quantify landscape change, we find that in the past century humans have moved as much sediment on North America as it would take natural processes to move in up to 3000 years."

She added "What these findings mean is that anthropogenic activities have unprecedented impact on sediment dynamics. Unsustainable land use practices entail large societal costs in terms of soil fertility decline, flooding and stream degradation and direct costs for soil and watershed restoration. The study improves our ability to set benchmarks for erosion monitoring and control. "

Prof. Peter Sadler of University of California, Riverside, added "To arrive at our conclusions, we compiled and analysed a large database of alluvium accumulation rates that extend back to a time well before the first Europeans lived on the continent.

"What really stood out in these data was the observation that for the past 40,000 years, rates of alluvium accumulation hardly changed at all and the landscape was quite stable. It was only in the last 200 years that the rates suddenly increased - right around the time that Europeans started intensive farming."

INDIANAPOLIS--Researchers at Indiana University School of Medicine have published their work about a specific type of childhood cancer in the peer-reviewed, international oncology journal, Cancers. This research involves a combination therapy that significantly slows tumor growth in models, which includes a model established from cells taken from tumors donated by Tyler Trent. This is the first published manuscript that includes Trent's tumor model.

Trent was a Purdue University student and sports superfan who died on January 1, 2019, after waging a long and valiant fight against an aggressive form of bone cancer known as osteosarcoma. In the publication's acknowledgments, the researchers dedicated the study to Trent's memory, saying they will always remember him for his courageous battle, his passion for cancer advocacy, and the generous donation of his tumor tissue for research.

"We are so proud to honor Tyler's legacy with this first publication, laying the foundation for future research to build upon," said Karen E. Pollok, PhD, who led the study. Pollok is an associate professor of pediatrics at IU School of Medicine. "We still have more work to do, but are hopeful that new therapies for osteosarcoma will be possible as we learn more about how to block different tumors from growing."

The Precision Genomics team at Riley Children's Health found a genetic variation in Trent's tumors (named after him as TT1 and TT2) known as the MYC-RAD21 signature, which has been found in tumors that tend to recur. Pollok said there are two drugs that can block its effects, a Chk1 inhibitor and a bromodomain inhibitor. Her team tested each drug individually, as well as in combination. They found that in models with the TT2 tumor, they could stop the tumors from growing by using one of the drugs individually, but using both drugs together blocked tumor growth substantially during a four-week treatment. The research team also determined that the combination treatment was well-tolerated.

"This research is allowing us to forge a path to improving outcomes for children, adolescents and young adults with a very aggressive bone cancer," said Jamie Renbarger, MD, another one of the lead researchers. Renbarger was one of Tyler's doctors and also leads the IU Precision Health Initiative pediatric sarcoma disease research team. She is also the Caroline Symmes Professor of Pediatric Cancer Research at IU School of Medicine. "We are hopeful that this program will lead the way in finding cures for more children."

The tumor started growing in the models again after stopping the therapy, leading researchers to consider next steps in their scientific process. Future research topics will include learning to understand how the tumors adapt to treatments and finding ways to optimize the combination therapy.

"The findings and research going on with Tyler's tumor models is incredibly encouraging and comforting to Tony and I," said Kelly Trent, who is Tyler Trent's mother. "It was at the core of who Tyler was to want to be used for good and to help at this capacity. We are so grateful for Dr. Pollok and Dr. Renbarger's work."

Trent was diagnosed with osteosarcoma for the first time when he was 15 years old. In the years that followed while he was a patient at Riley Hospital for Children at IU Health, he donated several tumor samples to cancer researchers at IU School of Medicine. He also encouraged other people to do the same, becoming a national advocate for cancer research. People have donated millions of dollars for cancer research in his name, including more than $189,000 for the Tyler Trent Cancer Research Endowment for Riley Hospital. The Trent family and Riley Children's Foundation worked together to create the endowment fund, which supports pediatric research being conducted by IU School of Medicine researchers.

HSE University scientists have for the first time in the world investigated the impact of delayed reinforcement signals in neurofeedback (NFB) training. They have experimentally proven that reducing the delay in feedback (decreasing feedback latency) can significantly increase the efficacy of training. This opens up new potential for the use of NFB for cognitive enhancement, self-regulation, and the treatment of a broad range of neurological disorders from anxeity and depression to epilepsy. The study was published in the Journal of Neural Engineering.

Neurofeedback (NFB) is a neuromodulation technology that allows a person to adjust the parameters of his or her own brain activity. Typically NFB uses electroencephalography (EEG) data reflecting changes in the potential of the electric field on the surface of the human head. EEG parameters are presented to the subject as, for example, a visual stimulus (column height on the screen, screen brightness) together with the task to change these parameters in the desired direction. By focusing on the NFB signal, the subject tries to remember the relationship between the parameter and their mental state. This allows a person to 'feel' the activity of their brain and learn how to control it. Often times such learning occurs subconsciously, i.e. without the use of any specific strategy.

Previous results from HSE University researchers have shown that in the majority of modern NFB systems the reinforcement signal lags behind the changes in neuronal activity, leading to ineffective learning and a wide dispersion of NFB therapy outcomes.
In order to provide access to the realm of small delays, the scientists developed a new mathematical method of filtering the EEG signal, allowing rapid estimation of the parameters of the rhythmic activity of the brain.

'This method gave us access to a previously unknown area of brain interaction with minimal latency in responses from the external system. It allows the brain to perceive an artificially created feedback loop as part of its own neural network. This is a qualitative leap that opens a new era in neurofeedback paradigm research,' says Alexey Ossadtchi, Director of the Centre for Bioelectric Interfaces at HSE University.

This development allowed the scientists to conduct a ground-breaking study on the impact of feedback latency on the efficacy of neurofeedback training. Forty subjects were trained to increase the power of their own parietal alpha rhythm based on a feedback signal displayed on a computer screen.

Participants in the experiment were divided into four groups. Those in the first group received a feedback signal with the shortest achievable delay at the time of the test, 240 ms. HSE University scientists have now managed to achieve a feedback loop reinforcing instantaneous narrow-band rhythm power with a total delay of less than 110 ms. Feedback signals for the subjects in the second and third groups were artificially delayed by 250 and 500 ms respectively, and for the subjects in the fourth group the feedback was not at all associated with their brain activity.

It turned out that the subjects from the group with the minimum delay achieved a certain level of alpha rhythm power after fewer training sessions compared with subjects from the other groups. Moreover, the analysis of alpha rhythm power after training showed that only the subjects from the group with the minimum delay displayed a sustained increase in rhythm power. This result is particularly important, as achieving sustainable changes is the main goal of the NFB therapy.

Researchers at the University of São Paulo (USP) in Brazil have demonstrated for the first time that in COVID-19 patients an immune mechanism known as the inflammasome participates in activation of the inflammatory process that can damage several organs and even lead to death.

An article reporting the findings of the study, which was supported by FAPESP, has just been published in the Journal of Experimental Medicine. According to the authors, the findings support the use of inflammasome activation both as a marker of disease prognosis, helping medical teams identify high-risk patients at an early stage, and as a potential therapeutic target in severe COVID-19.

“Drugs already approved for human use are capable of inhibiting inflammasome activation. These drugs can now be tested in the context of infection by SARS-CoV-2,” Dario Zamboni, a professor at USP’s Ribeirão Preto Medical School (FMRP-USP) and principal investigator for the study, told Agência FAPESP.

Almost all immune cells are equipped with the protein complex that constitutes the inflammasome, he explained. When one of these proteins identifies a sign of danger, such as a viral or bacterial particle, for example, the defense machinery is activated. As a result, the cell enters a process of programmed death (a type of inflammatory death called pyroptosis) and releases into the bloodstream signaling molecules called cytokines that attract to the site a veritable army of white blood cells. This is the onset of an inflammatory response that is ultimately designed to destruct the potential threat to the organism.

“The response to various pathogens involves inflammasome activation, and most of the time this blocks the infection and protects the organism. However, in some COVID-19 patients, the defense system appears to be overactivated, and we’re now trying to understand why this happens,” Zamboni said.

The involvement of this immune mechanism in the systemic inflammation that is characteristic of severe COVID-19 has been studied by scientists in several countries over the past few months. The Ribeirão Preto group is the first to demonstrate the activation of a specific type of inflammasome in response to infection by SARS-CoV-2 in patients.

“It’s important to recall that there’s more than one kind of inflammasome. What varies is the protein responsible for mediating activation of the protein complex,” Zamboni said. “We observed the presence of the inflammasome mediated by NLRP3, one of the most common and well-studied proteins. Other kinds may also participate in the response to SARS-CoV-2.”

Three angles of investigation

The conclusions presented in the article were based on three sets of experiments. The first involved immune cells from healthy donors infected with the novel coronavirus in the laboratory. The only white blood cells used in the experiment were monocytes.

“The viral dose administered to the culture is considered low, roughly one virus per cell. Even so, 75% of the monocytes died after 24 hours, evidencing the virus’s destructive potential,” Zamboni said.

The presence of lactate dehydrogenase (LDH) in the culture medium told the researchers that the cells were dying by pyroptosis: LDH is released when the cell membrane is breached and cellular contents escape into the bloodstream, a phenomenon typical of inflammatory cell death. The presence of cytokines IL-18 (interleukin-18) and IL-1β (interleukin-1 beta) suggested that this “serial cellular suicide” was associated with activation of the NLRP3 inflammasome, which was confirmed by analysis under the microscope.

“When this kind of inflammasome is activated, the proteins that form the complex, and are normally distributed throughout the cytoplasm, cluster together in what are called puncta, or specks, which can be observed under a microscope,” Zamboni said. “This, in turn, activates caspase-1, the enzyme that ‘processes’ the precursors of pro-inflammatory cytokines such as IL-18 and IL-1β so that they become ‘mature’ and active.”

The second set of experiments involved clinical samples from 124 patients undergoing treatment for moderate or severe COVID-19 between April and July at the general and teaching hospital (“Hospital de Clínicas”) run by FMRP-USP. The results were compared with data from patients hospitalized for other reasons, who served as a control group.

The researchers performed immunoenzymatic tests (based on antigen-antibody reactions) and used molecular probes to confirm that the white blood cells from COVID-19 patients had much larger amounts of IL-18 and active caspase-1 on average.

They observed under the microscope that puncta were more abundant in the immune cells of donors infected by SARS-CoV-2. Statistical analysis showed that the more evidence of inflammasome activation a patient displayed on admission to hospital, the worse the patient’s clinical progression and the higher the probability of death.

The third and last group of experiments used samples of lung tissue obtained during a minimally invasive autopsy procedure from five people who died after being infected by SARS-CoV-2. The analysis evidenced the presence of white blood cells infected by the virus, and puncta characteristic of the NLRP3 inflammasome inside the cells.

Next steps

The assays performed to date were supported by FAPESP via a Thematic Project and a Regular Research Grant awarded to Zamboni, who is also a member of the Center for Research on Inflammatory Diseases (CRID), a Research, Innovation and Dissemination Center (RIDC) funded by FAPESP and hosted by FMRP-USP.

The same group of more than 40 researchers is now working to find out whether other kinds of inflammasome are involved in the response to the novel coronavirus and why the pathogen activates this immune mechanism so intensely.

“We’re conducting experiments in which we compare inflammasome activation in response to SARS-CoV-2 and other viruses, such as the H1N1 flu virus,” Zamboni said.

Separately, the scientists are testing the use of a drug to inhibit the NLRP3 inflammasome in patients with severe COVID-19. Promising preliminary results have been published on medRxiv (read more at: agencia.fapesp.br/33958).

“We’re looking for other drugs capable of inhibiting the NLRP3 inflammasome for testing in a clinical trial,” Zamboni said. “As we discover more about inflammasome activation mechanisms in COVID-19, we can identify drugs that reduce the inflammatory process more effectively.”

Tissue oxygenation is a measure of the oxygen level in biological tissue and is a useful clinical biomarker for tissue viability. Abnormal levels may indicate the presence of conditions such as sepsis, diabetes, viral infection, or pulmonary disease, and effective monitoring is important for surgical guidance as well as medical care.

Several techniques exist for the measurement of tissue oxygenation, but they all have some limitations. For instance, pulse oximetry is robust and low-cost but cannot provide a localized measure of oxygenation. Near-infrared spectroscopy, on the other hand, is prone to noisy measurements due to pressure-sensitive contact probes. Spatial frequency domain imaging (SFDI) has emerged as a promising noncontact technique that maps tissue oxygen concentrations over a wide field of view. While simple to implement, SFDI has its own limitations: it requires a sequence of several images for its predictions to be accurate and is prone to errors when working with single snapshots.

In a new study published in the Journal of Biomedical Optics, researchers from Johns Hopkins University, Mason T. Chen and Nicholas J. Durr, have proposed an end-to-end technique for accurate calculation of tissue oxygenation from single snapshots, called OxyGAN. They developed this approach using a class of machine-learning framework called a conditional generative adversarial network (cGAN), which utilizes two neural networks -- a generator and a discriminator -- simultaneously on the same input data. The generator learns to produce realistic output images, while the discriminator learns to determine whether a given image pair forms a correct reconstruction for a given input.

Using conventional SDFI, the researchers obtained oxygenation maps for the human esophagus (ex vivo), hands and feet (in vivo), and a pig colon (in vivo) under illumination with two different wavelengths (659 and 851 nm). They trained OxyGAN with the feet and esophagus samples and saved the hand and colon samples to later test its performance. Further, they compared its performance with a single-snapshot technique based on a physical model and a two-step hybrid technique that consisted of a deep-learning model to predict optical properties and a physical model to calculate tissue oxygenation.

The researchers found that OxyGAN could measure oxygenation accurately, not only for the samples it had seen during training (human feet), but also for the samples it had not seen (human hand and pig colon), demonstrating the robustness of the model. It performed better than both the single-snapshot model and the hybrid model by 24.9% and 24.7%, respectively. Moreover, the scientists optimized OxyGAN to compute ~10 times faster than the hybrid model, enabling real-time mapping at a rate of 25 Hz. Frédéric Leblond, Associate Editor for the Journal of Biomedical Optics, comments, "Not only does this paper represent significant advances that can contribute to the practical clinical implementation of spatial frequency domain imaging, but it will also be part of a relatively small (although rapidly increasing in size) pool of robust published work using AI-type methods to deal with real biomedical optics data."

While the algorithm of OxyGAN could be optimized further, this approach holds promise as a novel technique to measure tissue oxygenation.

A team of zoologists and microbiologists from NUI Galway have published a new study showing that common house spiders carry bacteria susceptible to infect people, with the Noble False Widow spiders also carrying harmful strains resistant to common antibiotic treatments.

This new research, published in the international journal Scientific Reports, confirms a theory which has been debated among spider and healthcare specialists for many years, and explains a range of symptoms experienced by victims bitten by the invasive noble false widow spider in Ireland and Britain over the past decade.

Australian Black Widows or Funnel Web spiders are well known for their potentially deadly venom, but rare "skin-eating" conditions following seemingly harmless European and North American spider bites were thought to be the result of secondary infections caused by the victim scratching and probing the bite site with contaminated fingers. This new study shows that not only do spiders carry harmful bacteria, but those germs can be transmitted when a spider uses its fangs to bite.

Furthermore, many spiders have been shown to have venom with antibacterial activity and it is often debated as to whether the venom would neutralise bacteria at the bite site, but this also demonstrates, at least for the Noble False Widow, that the venom does not inhibit bacteria.

Dr Aoife Boyd, Director of the Pathogenic Mechanisms Group at NUI Galway's School of Natural Sciences, and senior author of the study, said: "The diversity of microbes never ceases to amaze me. The power to survive and thrive in every environment is shown here by the presence of antimicrobial resistance bacteria even in spider venom. Antimicrobial resistance (AMR) is an urgent and growing problem worldwide. A One Health approach interconnecting human, animal and environmental health is the only way to tackle the problem."

Dr John Dunbar, Zoologist at the Ryan Institute's Venom System Lab in NUI Galway, said: "About 10 species of spiders common in North-western Europe have fangs strong enough to pierce human skin and deliver venom, but only one of them, the recent invasive noble false widow spider, is considered of medical importance. Most of the time, a spider bite results in some redness and pain.

"In some cases, however, victims seem to develop long lasting infections for which strong antibiotic treatment - and sometimes a hospital stay - are necessary. It is this increasing range expansion and massive rise in dense populations of false widow spiders around urbanised areas across Ireland and Britain that has seen a rise in bites with some severe envenomation symptoms but also infections, which in some cases proved even difficult to treat with antibiotics."

Neyaz Kahn, co-lead author of the study and PhD student at the Pathogenic Mechanisms Group in NUI Galway's School of Natural Sciences, said: "Our study demonstrates that spiders are not just venomous but are also carriers of dangerous bacteria capable of producing severe infections. The biggest threat is that some of these bacteria are multi-drug resistant, making them particularly difficult to treat with regular medicine. This is something that health care professionals should consider from now on."

The onset of any physical exercise program causes muscle pain that can hinder movements as simple as getting up from a sofa. With time and a little persistence, the muscles become accustomed to the effort, developing more strength and endurance. Researchers affiliated with Harvard University in the United States and the University of São Paulo (USP) in Brazil describe the cellular mediator that makes this adaptation to exercise possible in the journal Cell.

The mediator is succinate, a metabolite hitherto known only for its participation in mitochondrial respiration. The authors of the article include Julio Cesar Batista Ferreira, a professor at USP's Biomedical Sciences Institute (ICB) and a member of the Center for Research on Redox Processes in Biomedicine (Redoxome), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP (São Paulo Research Foundation), and postdoctoral fellow Luiz Henrique Bozi, who conducted the investigation while he was a research intern at Harvard with FAPESP's support.

"Our results show that succinate leaves muscle cells during exercise and sends their neighbors signals that induce a process of muscle tissue remodeling," Ferreira explained to Agência FAPESP. "The motor neurons create new ramifications, the muscle fibers become more uniform to gain strength on contracting, and blood sugar uptake increases in all cells to produce ATP [adenosine triphosphate, the cellular fuel]. There's an increase in efficiency."

The findings reported in the article are based on a large number of experiments with animals and human volunteers. The first entailed comparisons of more than 500 metabolites present in mouse leg muscles before and after the mice ran on a treadmill until they were exhausted.

"Besides muscle fibers, muscle tissue also contains immune, nerve, and endothelial cells. If each one was a house, the streets between houses would be the interstitium or interstitial space. We isolated and analyzed each of the houses as well as the streets to find out what changes in the neighborhood after exercise, and observed a significant increase in succinate only in muscle fibers and interstitial spaces," Ferreira said.

A similar phenomenon was observed in healthy volunteers aged 25-35 during 60 minutes of intense exercise on a stationary bicycle. In this case, the researchers analyzed blood samples obtained via catheters in the femoral artery and vein and found that succinate levels rose substantially in venous blood exiting the muscle and fell rapidly during recovery.

At this point, the researchers were convinced that muscle cells released succinate in response to the stress caused by exercise, but they wanted to find out how, and above all why. Analysis of the volunteers' blood offered a clue: another compound that increased with exercise, in both venous and arterial blood, was lactate (the ionized form of lactic acid), a sign that the cells had activated their emergency energy generation system.

"Succinate is a metabolite that is normally unable to cross the cell membrane and leave the cell. Inside the cell, it participates in the Krebs cycle, a series of chemical reactions that occur in the mitochondria and result in ATP formation," Bozi explained. "But when energy demand increases sharply and the mitochondria can't keep up, an anaerobic system is activated, causing excess lactate formation and cell acidification. We found that this change in pH causes a change in the chemical structure of succinate such that it's able to get through the membrane and escape into the extracellular medium."

The transport protein that helps succinate exit the cell was identified by proteomics, an analysis of all the proteins in the membranes of mouse and human muscle cells. The results showed an increase in MCT1 in muscle tissue after exercise. MCT1 is a protein that specializes in transporting monocarboxylate out of the cell.

"The kind of molecule MCT1 transports is similar to succinate when it undergoes chemical modification in an acid medium. It ceases to be dicarboxylate and becomes monocarboxylate. We performed several in vitro experiments to confirm that this was the mechanism induced by exercise," Bozi said.

One of the experiments consisted of submitting cultured muscle cells to hypoxia (oxygen deprivation) in order to activate the anaerobic energy production mechanism and produce lactate. This was seen to be sufficient to induce succinate release into the interstitial space.

Another experiment involved germ cells (oocytes) from frogs genetically modified to express human MCT1. The researchers found that the oocytes released succinate only when they were placed in an acid medium.

"By this stage, we knew acidity makes succinate undergo protonation, a chemical process that enables it to bind to MCT1 and pass through the membrane into the extracellular medium, but we had yet to discover the significance of this accumulation of succinate in the interstitial space during exercise," Ferreira said.

Communication

The importance of communication between cells in the organism's adaptation to any kind of stress is well-established in the scientific literature. Signals are exchanged by means of molecules released into the interstitial space to bind to proteins in the membranes of nearby cells. Activation of these membrane receptors triggers processes that lead to structural and functional tissue modifications.

"Our hypothesis was that succinate performed this role of regulation in muscles, by binding to a protein called SUCNR1 [succinate receptor 1] that's highly expressed in the membranes of motor neurons, for example," Bozi said.

To test the theory, they conducted experiments with mice that had been genetically modified not to express SUCNR1. The mice were allowed to run freely on a resistance wheel for three weeks, considered long enough for morphological and functional changes to occur in muscle tissue.

"The muscle fibers were expected to become more uniform and stronger, but they didn't," Ferreira said. "In addition, exercise didn't promote motor neuron ramification, which is crucial to enhance contraction efficiency. We also observed that cellular glucose uptake didn't increase and that insulin sensitivity was lower than in the wild mice that served as controls. In other words, exercise-induced remodeling didn't happen without the succinate receptor."

According to Ferreira, the study is the first to show the paracrine action of succinate in muscle tissue, i.e. its role in cell-to-cell signaling to alert nearby cells that they must modify their internal processes to adapt to a "new normal".

"The next step is to find out whether this mechanism is disrupted in other diseases characterized by energy metabolism alterations and cell acidification, such as neurodegenerative diseases, in which astrocyte-neuron communication is critical to disease progression," he said.

COLUMBIA, Mo. -- After Jo-Ana Chase heard her mother had successful heart surgery, she was relieved when her mom was finally discharged from the hospital and sent home to be cared for by her brother. However, Chase quickly learned from her brother that he felt lost on the best ways to care for their mom due to confusing discharge instructions from the hospital and logistical challenges related to home health care services like wound care and medication management.

Motivated by her own family's struggles navigating the often complicated American health care system, Chase, an associate professor in the University of Missouri's Sinclair School of Nursing, is working with clinicians and health care providers to better engage family caregivers in providing coordinated care after a loved one is discharged home from the hospital. In a recent study, she sought to better understand the resources family caregivers currently use to help health care providers identify gaps in coverage and recommend resources to assist overburdened caregivers and ultimately improve and better coordinate care.

"The American health care system has been very patient-focused; however, we also need to remember that patients often rely on family for help with their care," Chase said. "Now that we are starting to recognize how impactful the work is that family caregivers provide, my goal is to better engage these family caregivers and help them access the resources they need to better support the loved ones they care for."

In her study, Chase interviewed family caregivers about the medical and nursing tasks they completed for a loved one after a hospital-to-home transition, such as treating wounds or giving medication. She found that family caregivers often struggle with these tasks and in navigating the complex health care system; and resources like home health care nurses or aides can serve as a central point-of-contact to improve coordinated care.

"After a patient is discharged from the hospital, a home health care nurse will often come to the patient's home periodically to check in, make sure the medications are right, evaluate the home for safety, check the patient's vital signs and assess wounds," Chase said. "This is an excellent opportunity for the clinicians to work with caregivers to address any questions, challenges, or concerns family caregivers may be having."

Chase added that while caregivers may receive discharge instructions for providing care after a patient leaves the hospital, the instructions may fail to consider caregivers' preparedness and various environmental factors, such as what equipment is needed, or which room in a house is best for administering a specific task like changing a bandage. In addition to home health care nurses, primary care providers, social workers, nearby community centers and respite services can also help support and take the load off of overburdened caregivers.

"At some point in our lives, most of us will become a caregiver for someone, whether it is a child, spouse, parent or relative," Chase said. "So, encouraging the health care system to effectively engage caregivers benefits us all. I hope one day when I am sick and someone has to take care of me, my caregiver doesn't experience the same challenges my brother did caring for my mom."

The COVID-19 pandemic has sparked heightened awareness of cleaning and disinfecting procedures in many industries. Health care facilities have long been familiar with protocols for disinfecting tools and equipment, and now, scientists are studying methods to improve these procedures, making them safer and more efficient for patients and health care workers.

At Johns Hopkins, biomedical engineer Jeff Siewerdsen and radiologist Mahadevappa Mahesh are investigating the use of UV light to disinfect the inner bore of CT scanning machines, a cramped space that is exposed to exhaled particles from patients and is difficult to reach by manually wiping it down.

The UV light being studied is not the typical beam of sunshine that falls to the earth. Those rays are mostly UVA rays, which tend to cause skin cancer and other problems. Siewerdsen and Mahesh are studying UVC rays, which can eliminate a high proportion of SARS-CoV-2 virus from hard surfaces.

They attached a UVC lamp to the bed inside the bore of a CT scanner and found that the UV light wiped out 99.9999% of SARS-CoV-2 virus particles in three to five minutes. A summary of the results was published Nov. 18, along with a video abstract, in the Journal of Applied Clinical Medical Physics.

The lamp used in the study cost $105; however, they did not study the longevity of the lamp. The researchers also note that there may be crevices in the CT scanner that are not reachable with the UV light.

If the UVC procedure for CT scanners proves useful, the process could be used in addition to the manual wipe down of CT scanners, improve the safety of personnel and patients, and applicable to many health care facilities around the globe.

Note: Exposure to UVC light could harm health. UVC lamps should not be used without proper training and safety precautions. Read more information from the FDA.

DOES PROLONGED COVID-19 DETECTION IDENTIFY PEOPLE WHO ARE INFECTIOUS LONG TERM?

Media Contact: Michael E. Newman, mnewma25@jhmi.edu

Repeated testing for SARS-CoV-2, the virus that causes COVID-19, has become common practice during the ongoing pandemic, especially when there is a strong suspicion that a person is infected with, or has been exposed to, the pathogen. Molecular diagnostics are the standard means for detecting the presence of SARS-CoV-2 genetic material (RNA), with negative assays from two consecutively collected respiratory specimens more than 24 hours apart and no symptoms being the benchmark for when a patient can end quarantine and return to normal activities.

However, recent research has shown that while SARS-CoV-2 RNA can be detectable with molecular testing for weeks after the onset of symptoms, it doesn't necessarily denote the presence of infectious virus particles. In a medical records study looking at results from nearly 30,000 COVID-19 tests over a two-month period, a team led by researchers at Johns Hopkins Medicine and the Johns Hopkins Bloomberg School of Public Health gained significant insight into when virus detection also may indicate contagiousness.

The findings were published online Oct. 27 in the journal Clinical Infectious Diseases.

From March 11 to May 11, 2020, the researchers evaluated the results of repeated polymerase chain reaction (PCR) diagnostic tests for SARS-CoV-2 RNA in 29,686 nasopharyngeal swabs. The PCR assay is very specific and detects the viral RNA by accumulation of a fluorescent signal. The number of times it takes to get a positive signal is called the cycle threshold (Ct), with a low Ct score indicating a large amount of SARS-CoV-2 RNA and a high one just the opposite.

"We also placed a portion of the specimens in cell cultures to see whether or not live virus particles would grow," says Heba Mostafa, M.B.B.Ch., Ph.D., assistant professor of pathology at the Johns Hopkins University School of Medicine and co-senior author of the study. "In that way, we could compare the Ct values with actual virus recovery in the lab to see when detected virus also was infectious virus."

The researchers found that the average Ct value associated with cell culture growth of SARS-CoV-2 was 18.8. They also observed viral growth from specimens collected up to 20 days after the first positive result, mostly in patients who were symptomatic for COVID-19 at the time of specimen sampling. Sequencing of the entire genome from RNAs collected in the first and subsequent tests provided evidence that the same virus was seen throughout. Positive tests following negative ones had Ct values higher than 29.5 and were not associated with observed virus growth in culture.

"Our findings support the theory that low Ct values in SARS-CoV-2 diagnostic tests are associated with recoverable virus, and that RNA detection in repeated tests may indicate someone who continues to be infectious with persistent symptoms," Mostafa says. "However, additional studies are needed to truly determine if Ct values and cell cultures can be used together to make clinical decisions, develop diagnostic strategies and identify those most likely to spread SARS-CoV-2."

"Defining the window of time in which a COVID-19 patient can transmit the virus can help drive more effective isolation practices," adds Andrew Pekosz, Ph.D., professor of microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health and co-senior author of the study.

CLEVELAND--A team of researchers at the Case Western Reserve University School of Medicine has taken a major step toward understanding the mechanisms involved in the formation of large clumps of tau protein, a hallmark of Alzheimer's disease and several other neurodegenerative disorders.

Their findings may help to better understand the pathological process and possibly lead to developing medications to treat such devastating brain diseases.

The study, "Regulatory mechanisms of tau protein fibrillation under the conditions of liquid-liquid phase separation," was published this week in the journal Proceedings of the National Academy of Sciences.

The senior author of the study is Witold Surewicz, a professor of physiology and biophysics at the School of Medicine. Solomiia Boyko, a graduate student, and Krystyna Surewicz, a senior research associate, co-authored the study, which was supported by the National Institute on Aging.

Alzheimer's disease is characterized by the death of nerve cells in the brain, resulting in progressive memory loss and cognitive decline. More than 5 million people in the United States suffer from Alzheimer's, and this number is projected to triple by 2050, according to the Alzheimer's Association. There is no cure for this devastating disease.

In Alzheimer's disease, clumps of a tau protein begin to form inside nerve cells in the brain. Brain accumulation of these aggregates are known as "neurofibrillary tangles."

Similar tangles of tau, which spread among nerve cells, are also associated with a host of other neurodegenerative diseases, collectively known as "tauopathies." These include Pick's disease, frontotemporal dementia, progressive supranuclear palsy and chronic traumatic encephalopathy.

Recent studies have demonstrated that, like some other proteins, tau can undergo liquid-liquid phase separation, a process resulting in formation of liquid-like droplets containing highly concentrated protein. This phenomenon, similar to how oil and water separate when mixed, is believed to be important for normal functions of cells. However, under certain conditions, this separation within cells may also have pathological consequences.

The new study establishes a critical link between these two phenomena--tau liquid-liquid phase separation and tangle formation--demonstrating that the environment of liquid droplets greatly facilitates aggregation of tau into fibrillar structures similar to those found in the brain of someone with Alzheimer's disease.

The researchers also describe the mechanism by which this liquid-liquid phase separation regulates clumping when different variants of tau protein are present. In particular, the authors show that, because of the unique properties of liquid droplets, the presence of a shorter, slowly aggregating tau variant inhibits clumping of a longer, normally fast aggregating variant, slowing down the overall process of tangle formation.

This novel regulatory mechanism may play a major role in determining the clinical outcome of the disease, as the ratio of these two tau variants in brain varies substantially in different tauopathies.

For example, Alzheimer's disease is usually characterized by an equal proportion of both tau isoforms, whereas fibrillary tangles in progressive supranuclear palsy and Pick's disease consist largely of the longer and shorter variant, respectively.

"While the present results provide exciting new insights into formation of pathological clumps of tau protein," Surewicz said, "our study was limited to experiments with purified proteins in the test tube. The next step is to verify these findings in cell and animal models of the disease."

UNIVERSITY PARK, Pa. -- Imagine changing the TV channel with a wave of your hand or turning on the car radio with a twist of your wrist.

Freehand gesture-based interfaces in interactive systems are becoming more common, but what if your preferred way to gesture a command - say, changing the TV to channel 10 - significantly differed from that of a user from another culture? Would the system recognize your command?

Researchers from the Penn State College of Information Sciences and Technology and their collaborators explored this question and found that some gesture choices are significantly influenced by the cultural backgrounds of participants.

"Certain cultures may prefer particular gestures and we may see a difference, but there is common ground between cultures choosing some gestures for the same kind of purposes and actions," said Xiaolong "Luke" Zhang, associate professor of information sciences and technology and principal investigator of the study. "So we wanted to find out what can be shared among the different cultures, and what the differences are among different cultures to design better products."

In their study, the researchers asked American and Chinese participants to perform their preferred gestures for different commands in three separate settings: answering a phone call in the car, rotating an object in a virtual reality environment, and muting the television.

The team found that while many preferred commands were similar among both cultural groups, there were some gesture choices that differed significantly between the groups. For example, most American participants used a thumbs up gesture to confirm a task in the virtual reality environment, while Chinese participants preferred to make an OK sign with their fingers. To reject a phone call in the car, most American participants made a horizontal movement across their neck with a flat hand, similar to a "cut" motion, while Chinese participants waved a hand back and forth to reject the call. Additionally, in Chinese culture, one hand can represent digits above five, while in American culture an individual can only represent numbers one to five using one hand.

"This project is one of the first kind of research to study the existence of cultural influence and the use of preferences of hand gestures," said Zhang. "We provide empirical evidence to show indeed that we should be aware of the existence of this matter."

On the other hand, Zhang said, from the perspective of design, the study shows that certain gestures can be common across multiple cultures, while other gestures can be very different.

"Designers have to be careful when delivering products to different markets," he said. "(This work could inform companies) to enable users customize the gesture commands, rather than have them pick something that is unnatural to learn from the perspective of the culture."

As time goes by, the tips of your chromosomes--called telomeres--become shorter. This process has long been viewed as an unwanted side-effect of aging, but a recent study shows it is in fact good for you.

"Telomeres protect the genetic material," says Titia de Lange, Leon Hess Professor at Rockefeller. "The DNA in telomeres shortens when cells divide, eventually halting cell division when the telomere reserve is depleted."

New results from de Lange's lab provide the first evidence that telomere shortening helps prevent cancer in humans, likely because of its power to curtail cell division. Published in eLife, the findings were obtained by analyzing mutations in families with exceptional cancer histories, and they present the answer to a decades-old question about the relationship between telomeres and cancer.

A longstanding controversy

In stem cells, including those that generate eggs and sperm, telomeres are maintained by telomerase, an enzyme that adds telomeric DNA to the ends of chromosomes. Telomerase is not present in normal human cells, however, which is why their telomeres wither away. This telomere shortening program limits the number of divisions of normal human cells to about 50.

The idea that telomere shortening could be part of the body's defense against cancer was first proposed decades ago. Once an early-stage tumor cell has divided 50 times, scientists imagined, depletion of the telomere reserve would block further cancer development. Only those cancers that manage to activate telomerase would break through this barrier.

Clinical observations seemed to support this hypothesis. "Most clinically detectable cancers have re-activated telomerase, often through mutations," de Lange says. Moreover, mouse experiments showed that shortening telomeres can indeed protect against cancer. Nonetheless, evidence for the telomere tumor suppressor system remained elusive for the past two decades, and its existence in humans remained controversial.

The solution to a decades-old problem

The telomere tumor suppressor pathway can only work if we are born with telomeres of the right length; if the telomeres are too long, the telomere reserve would not run out in time to stop cancer development. Longer telomeres will afford cancer cells additional divisions during which mutations can creep into the genetic code, including mutations that activate telomerase.

For decades, de Lange's lab has been studying the complex process by which telomeres are regulated. She and others identified a set of proteins that can limit telomere length in cultured human cells, among them a protein called TIN2. When TIN2 is inhibited, telomerase runs wild and over-elongates telomeres. But it was not known whether TIN2 also regulated telomere length at birth.

The stalemate on the telomere tumor suppressor continued until physicians at the Radboud University Medical Center in Holland reached out to de Lange about several cancer-prone families.  The doctors found that these families had mutations in TINF2, the gene that encodes the TIN2 protein instrumental to controlling telomere length. That's when they asked de Lange to step in.

Isabelle Schmutz, a Women&Science postdoctoral fellow in the de Lange lab, used CRISPR gene-editing technology to engineer cells with precisely the same mutations as those seen in the Dutch families and examined the resulting mutant cells. She found that the mutant cells had fully functional telomeres and no genomic instability. They were, for all intents and purposes, normal healthy cells.

But there was one thing wrong with the cells. "Their telomeres became too long, " de Lange says.  Similarly, the patient's telomeres were unusually long. "These patients have telomeres that are far above the 99th percentile," de Lange says.

"The data show that if you're born with long telomeres, you are at greater risk of getting cancer, " says de Lange. "We are seeing how the loss of the telomere tumor suppressor pathway in these families leads to breast cancer, colorectal cancer, melanoma, and thyroid cancers. These cancers would normally have been blocked by telomere shortening. The broad spectrum of cancers in these families shows the power of the telomere tumor suppressor pathway."

The study is demonstration of the power of basic science to transform our understanding of medicine. "How telomeres are regulated is a fundamental problem," de Lange says. "And by working on a fundamental problem, we were eventually able to understand the origins of a human disease."