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Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 2:35pm

Out of Rhythm
The occurrence of atrial fibrillation quadrupled over the past 50 years, according to recent studies. A-fib occurs when electrical signals in the upper chambers of the heart—the atria—misfire, causing an irregular heartbeat. People with the condition experience shortness of breath and tiredness. It can result in strokes if left untreated. But up to a quarter of cases go undiagnosed, according to recent research.

Cause and effect: Doctors are more on the lookout for the condition, which is partially responsible for the rising rates. Also people are living longer, and longer life comes with more health complications like heart disease and cancer. Last November leading medical groups issued new guidelines for preventing and treating A-fib, calling on doctors to encourage heart-healthy habits and early, more aggressive efforts to control heart rhythms.

 Some groups, including women and those in underserved communities, can go undiagnosed. “It's a disease that requires monitoring and detection,” says cardiologist Jared Magnani of the University of Pittsburgh. “And then it requires access to medical care, with a partner in making decisions about things like [medication], and finally more advanced therapies and treatment.”

Part 1

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:46am

Trees struggle to 'breathe' as climate warms, researchers find

Trees are struggling to sequester heat-trapping carbon dioxide (CO₂) in warmer, drier climates, meaning that they may no longer serve as a solution for offsetting humanity's carbon footprint as the planet continues to warm, according to a new study by researchers.

They  found that trees in warmer, drier climates are essentially coughing instead of breathing. They are sending CO₂ right back into the atmosphere far more than trees in cooler, wetter conditions.

Through the process of photosynthesis, trees remove CO₂ from the atmosphere to produce new growth. Yet, under stressful conditions, trees release CO₂ back to the atmosphere, a process called photorespiration. With an analysis of a global dataset of tree tissue, the research team demonstrated that the rate of photorespiration is up to two times higher in warmer climates, especially when water is limited.

They found the threshold for this response in subtropical climates begins to be crossed when average daytime temperatures exceed roughly 68 degrees Fahrenheit and worsens as temperatures rise further.

The results complicate a widespread belief about the role of plants in helping to draw down—or use—carbon from the atmosphere, providing new insight into how plants could adapt to climate change. Importantly, the researchers noted that as the climate warms, their findings demonstrate that plants could be less able to draw CO₂ out of the atmosphere and assimilate the carbon necessary to help the planet cool down.

Max K. Lloyd et al, Isotopic clumping in wood as a proxy for photorespiration in trees, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2306736120

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:41am

Surgeons' choice of skin disinfectant impacts infection risk, Canadian-American study shows

Does the type of solution used by surgeons to disinfect skin before surgery impact the risk of surgical site infection? According to new research from an international trial jointly led by McMaster University and the University of Maryland School of Medicine—yes, it does!

Researchers of the PREPARE trial, which enrolled nearly 8,500 participants at 25 hospitals in Canada and the United States, found the use of iodine povacrylex in alcohol to disinfect a patient's skin could prevent surgical site infection in thousands of patients undergoing surgery for a closed fracture each year. The findings, published in The New England Journal of Medicine, are poised to have many hospitals consider a policy change to the use of iodine povacrylex in alcohol for fracture surgeries.

The trial included 6,785 patients undergoing surgery to treat a closed lower extremity or pelvic fracture and 1,700 patients undergoing surgery to treat an open fracture. Closed fractures occur when the bone is broken, but the skin is intact. Open fractures have an exceptionally high risk of infection due to the open wound and bone being exposed to environmental bacteria for hours before surgery. Researchers compared the two most commonly used antiseptic products in the United States and Canada. Patients with closed fractures randomized to receive 0.7% iodine povacrylex in 74% isopropyl alcohol for skin antisepsis experienced fewer post-operative surgical site infections than those randomized to receive 2% chlorhexidine gluconate in 70% isopropyl alcohol. In patients with open fractures, the risk of infection was similar between the two different antiseptic skin preparation solutions.

These results suggest that the use of iodine povacrylex in alcohol as preoperative skin antisepsis could prevent surgical-site infection in thousands of patients with closed fractures each year.

Skin Antisepsis before Surgical Fixation of Extremity Fractures, New England Journal of Medicine (2024). DOI: 10.1056/NEJMoa2307679

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:37am

Study finds 1 in 10 veterans diagnosed with dementia may instead have cognitive decline from cirrhosis

As many as 10% of older U.S. veterans diagnosed with dementia may suffer instead from reversible cognitive decline caused by advanced liver disease, according to an analysis from the Virginia Commonwealth University's School of Medicine and the Richmond VA Medical Center.

It can be difficult for physicians to differentiate dementia from the cognitive decline caused by cirrhosis, called hepatic encephalopathy. If undetected, patients may not receive appropriate treatment that can reverse or halt the impairment. The study, published in the journal JAMA Network Open, sought to learn more about the prevalence and risk factors of undiagnosed cirrhosis and potential encephalopathy in veterans with dementia. The findings suggest that physicians treating veterans with dementia, even without a cirrhosis diagnosis, should consider assessing their patients for liver disease. Identifying cirrhosis early on may unveil reversible causes of cognitive impairment, potentially improving the lives of these patients.

Hepatic encephalopathy is a nervous system disorder brought on by cirrhosis, an advanced form of liver disease in which patients experience severe scarring of the liver. When the liver doesn't work properly, toxins build up in the blood. These toxins can travel to the brain and affect brain function, leaving patients confused or delirious. Widely available medications can readily rid the body of toxins and reverse this condition, but without treatment, patients can lapse into coma or die.

Undiagnosed Cirrhosis and Hepatic Encephalopathy in a National Cohort of Veterans With Dementia, JAMA Network Open (2024). DOI: 10.1001/jamanetworkopen.2023.53965

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:24am

How synthetic biology is helping us: Researchers engineer viruses to kill deadly pathogens

Researchers have successfully coaxed a deadly pathogen to destroy itself from the inside out.

In a new study, researchers modified DNA from a bacteriophage or "phage," a type of virus that infects and replicates inside of bacteria. Then, the research team put the DNA inside Pseudomonas aeruginosa (P. aeruginosa), a deadly bacterium that is also highly resistant to antibiotics. Once inside the bacterium, the DNA bypassed the pathogen's defense mechanisms to assemble into virions, which sliced through the bacterium's cell to kill it.

Building on a growing interest in "phage therapies," the experimental work represents a critical step toward engineering designer viruses as new therapeutics to kill antibiotic-resistant bacteria. It also reveals vital information about the inner workings of phages, a little-studied area of biology.

The study, "A synthetic biology approach to assemble and reboot clinically relevant Pseudomonas aeruginosa tailed phages," was published in the journal Microbiology Spectrum.

Not only did the phage kill the bacteria, the bacteria also ejected billions more phages. These phages can then be used to kill other bacteria, like those causing an infection.

A synthetic biology approach to assemble and reboot clinically relevant Pseudomonas aeruginosa tailed phages, Microbiology Spectrum (2024). DOI: 10.1128/spectrum.02897-23

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:16am

Brain changes behind pain sensitivity may affect older women more

A new study has found that the brain system enabling us to inhibit our own pain changes with age, and that gender-based differences in those changes may lead females to be more sensitive to moderate pain than males as older adults.

Researchers used fMRI scans to examine brain responses in men and women who had rated the intensity and unpleasantness of pain during exposure to increasing levels of heat. The results suggested that established gender differences in pain perception could likely be traced at least in part to this brain network, and offered new evidence that those gender differences may become more disparate with age.

Michelle D. Failla et al, Gender Differences in Pain Threshold, Unpleasantness, and Descending Pain Modulatory Activation Across the Adult Life Span: A Cross Sectional Study, The Journal of Pain (2023). DOI: 10.1016/j.jpain.2023.10.027

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:13am

Scientists pinpoint growth of brain's cerebellum as key to evolution of bird flight

Evolutionary biologists  report they have combined PET scans of modern pigeons along with studies of dinosaur fossils to help answer an enduring question in biology: How did the brains of birds evolve to enable them to fly?

The answer, they say, appears to be an adaptive increase in the size of the cerebellum in some fossil vertebrates. The cerebellum is a brain region responsible for movement and motor control.

The research findings are published in the Jan. 31 issue of the Proceedings of the Royal Society B.

The researchers performed positron emission tomography, or PET, imaging scans, the same technology commonly used on humans, to compare activity in 26 regions of the brain when the bird was at rest and immediately after it flew for 10 minutes from one perch to another. They scanned eight birds on different days. PET scans use a compound similar to glucose that can be tracked to where it's most absorbed by brain cells, indicating increased use of energy and thus activity. The tracker degrades and gets excreted from the body within a day or two. Of the 26 regions, one area—the cerebellum—had statistically significant increases in activity levels between resting and flying in all eight birds. Overall, the level of activity increase in the cerebellum differed by more than two standard statistical deviations, compared with other areas of the brain. The researchers also detected increased brain activity in the so-called optic flow pathways, a network of brain cells that connect the retina in the eye to the cerebellum. These pathways process movement across the visual field.

What was new in this research was linking the cerebellum findings of flight-enabled brains in modern birds to the fossil record that showed how the brains of birdlike dinosaurs began to develop brain conditions for powered flight.

Quantitative functional imaging of the pigeon brain: implications for the evolution of avian powered flight, Proceedings of the Royal Society B: Biological Sciences (2024). DOI: 10.1098/rspb.2023.2172. royalsocietypublishing.org/doi … .1098/rspb.2023.2172

Comment by Dr. Krishna Kumari Challa on February 1, 2024 at 7:05am

Neanderthals and humans lived side by side in Northern Europe 45,000 years ago, genetic analysis finds

A genetic analysis of bone fragments unearthed at an archaeological site in central Germany shows conclusively that modern humans—Homo sapiens—had already reached Northern Europe 45,000 years ago, overlapping with Neanderthals for several thousand years before the latter went extinct.

The findings establish that the site near Ranis, Germany, which is known for its finely flaked, leaf-shaped stone tool blades, is among the oldest confirmed sites of modern human Stone Age culture in north central and northwestern Europe.

The evidence that Homo sapiens and Homo neanderthalensis lived side by side is consistent with genomic evidence that the two species occasionally interbred. It also feeds the suspicion that the invasion of Europe and Asia by modern humans some 50,000 years ago helped drive Neanderthals, which had occupied the area for more than 500,000 years, to extinction.

The genetic analysis, along with an archaeological and isotopic analysis and radiocarbon dating of the Ranis site, are detailed in a trio of papers appearing in the journals Nature and Nature Ecology and Evolution.

Jean-Jacques Hublin, Homo sapiens reached the higher latitudes of Europe by 45,000 years ago, Nature (2024). DOI: 10.1038/s41586-023-06923-7. www.nature.com/articles/s41586-023-06923-7

Stable isotopes show Homo sapiens dispersed into cold steppes ~45,000 years ago at Ilsenhöhle in Ranis, Germany, Nature (2024). DOI: 10.1038/s41559-023-02318-z , www.nature.com/articles/s41559-023-02318-z

The ecology, subsistence and diet of ~45,000-year-old Homo sapiens at Ilsenhöhle in Ranis, Germany, Nature Ecology & Evolution (2024). DOI: 10.1038/s41559-023-02303-6 , www.nature.com/articles/s41559-023-02303-6

https://phys.org/news/2024-01-neanderthals-humans-side-northern-eur...

Comment by Dr. Krishna Kumari Challa on January 31, 2024 at 12:13pm

Study finds gut microbiota influence severity of respiratory viral infection

The composition of microbiota found in the gut influences how susceptible mice are to respiratory virus infections and the severity of these infections, according to new research by researchers.

The findings, published in the journal Cell Host & Microbe, report that segmented filamentous bacteria, a bacterial species found in the intestines, protected mice against influenza virus infection when these bacteria were either naturally acquired or administered.

This protection against infection also applied to respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. To maintain this protection, the study noted that segmented filamentous bacteria required immune cells in the lungs called basally resident alveolar macrophages.

In this study, the researchers investigated how differences in specific microbial species can impact outcomes of respiratory virus infections and how they might do so, which hasn't been well defined previously. They studied mice with discrete microbiome differences and mice differing in only the presence or absence of segmented filamentous bacteria. Viral titers in the lung were measured several days after infection and varied significantly depending on the nature of the microbiome of the different animal groups.

These findings uncover complex interactions that mechanistically link the intestinal microbiota with the functionality of basally resident alveolar macrophages and severity of respiratory virus infection.

Intestinal microbiota programming of alveolar macrophages influences severity of respiratory viral infection, Cell Host & Microbe (2024). DOI: 10.1016/j.chom.2024.01.002. www.cell.com/cell-host-microbe … 1931-3128(24)00006-4

Comment by Dr. Krishna Kumari Challa on January 31, 2024 at 12:06pm

DNA particles that mimic viruses hold promise as vaccines

Using a virus-like delivery particle made from DNA, researchers have created a vaccine that can induce a strong antibody response against SARS-CoV-2.

The vaccine, which has been tested in mice, consists of a DNA scaffold that carries many copies of a viral antigen. This type of vaccine, known as a particulate vaccine, mimics the structure of a virus. Most previous work on particulate vaccines has relied on protein scaffolds, but the proteins used in those vaccines tend to generate an unnecessary immune response that can distract the immune system from the target.

In the mouse study, the researchers found that the DNA scaffold does not induce an immune response, allowing the immune system to focus its antibody response on the target antigen.

This approach, which strongly stimulates B cells (the cells that produce antibodies), could make it easier to develop vaccines against viruses that have been difficult to target, including HIV and influenza, as well as SARS-CoV-2, the researchers say. Unlike T cells, which are stimulated by other types of vaccines, these B cells can persist for decades, offering long-term protection.

Enhancing antibody responses by multivalent antigen display on thymusindependent DNA origami scaffolds, Nature Communications (2024). DOI: 10.1038/s41467-024-44869-0

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