Connect with us

Bioengineer

Research suggests our galaxy’s brightest gamma-ray binary system may be powered by a magnetar star

Credit: Kavli IPMU A team of researchers led by members of the Kavli Institute for the Physics and Mathematics of

Published

on

A team of researchers led by members of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) has analyzed previously collected data to infer the true nature of a compact object–found to be a rotating magnetar, a type of neutron star with an extremely strong magnetic field–orbiting within LS 5039, the brightest gamma-ray binary system in the Galaxy.

Including former graduate student Hiroki Yoneda, Senior Scientist Kazuo Makishima and Principal Investigator Tadayuki Takahashi at the Kavli IMPU, the team also suggest that the particle acceleration process known to occur within LS 5039 is caused by interactions between the dense stellar winds of its primary massive star, and ultra-strong magnetic fields of the rotating magnetar.

Gamma-ray binaries are a system of massive stars and compact stars. They were discovered only recently, in 2004, when observations of very-high-energy gamma-rays in the teraelectronvolt (TeV) band from large enough regions of the sky became possible. When viewed with visible light, gamma-ray binaries appear as bright bluish-white stars, and are indistinguishable from any other binary system hosting a massive star.

However, when observed with X-rays and gamma-rays, their properties are dramatically different from those of other binaries. In these energy bands, ordinary binary systems are completely invisible, but gamma-ray binaries produce intense non-thermal emission, and their intensity appears to increase and decrease according to their orbital periods of several days to several years.

Once the gamma-ray binaries were established as a new astrophysical class, it was quickly recognized that an extremely efficient acceleration mechanism should operate in them. While the acceleration of TeV particles requires tens of years in supernova remnants, which are renowned cosmic accelerators, gamma-ray binaries boost electron energy beyond 1 TeV in just tens of seconds. Gamma-ray binaries can thus be considered one of the most efficient particle accelerators in the Universe.

In addition, some gamma-ray binaries are known to emit strong gamma-rays with energies of several megaelectron volts (MeV). Gamma-rays in this band are currently difficult to observe; they were detected from only around 30 celestial bodies in the whole sky. But the fact that such binaries emit strong radiation even in this energy band greatly adds to the mystery surrounding them, and indicates an extremely effective particle acceleration process going on within them.

Around 10 gamma-ray binaries have been found in the Galaxy thus far–compared to more than 300 X-ray binaries that are known to exist. Why gamma-ray binaries are so rare is unknown, and, indeed, what the true nature of their acceleration mechanism is, has been a mystery–until now.

Through previous studies, it was already clear that a gamma-ray binary is generally made of a massive primary star that weighs 20-30 times the mass of the Sun, and a companion star that must be a compact star, but it was not clear, in many cases, whether the compact star is a black hole or a neutron star. The research team started their attempt by figuring out which is generally the case.

One of the most direct pieces of evidence for the presence of a neutron star is the detection of periodic fast pulsations, which are related to the neutron star rotation. Detection of such pulsation from a gamma-ray binary almost undoubtedly discards the black hole scenario.

In this project, the team focused on LS 5039, which was discovered in 2005, and still keeps its position as the brightest gamma-ray binary in the X-ray and gamma-ray range. Indeed, this gamma-ray binary was thought to contain a neutron star because of its stable X-ray and TeV gamma-ray radiation.

However, until now, attempts to detect such pulses had been conducted with radio waves and soft X-rays–and because radio waves and soft X-rays are affected by the primary star’s stellar winds, detection of such periodical pulses had not been successful.

This time, for the first time, the team focused on the hard X-ray band (>10 keV) and observation data from LS 5039 gathered by the hard X-ray detector (HXD) on board the space-based telescopes Suzaku (between September 9 and 15, 2007) and NuSTAR (between September 1 and 5, 2016)–indeed, the six-day Suzaku observation period was the longest yet using hard X-rays.

Both observations, while separated by nine years, provided evidence of a neutron star at the core of LS 5039: the periodic signal from Suzaku with a period of about 9 seconds. The probability that this signal arises from statistical fluctuations is only 0.1 percent. NuSTAR also showed a very similar pulse signal, though the pulse significance was lower–the NuSTAR data, for instance, was only tentative. By combining these results, it was also inferred that the spin period is increasing by 0.001 s every year.

Based on the derived spin period and the rate of its increase, the team ruled out the rotation-powered and accretion-powered scenarios, and found that the magnetic energy of the neutron star is the sole energy source that can power LS 5039. The required magnetic field reaches 10^{11} T, which is 3 orders of magnitude higher than those of typical neutron stars.

This value is found among so-called magnetars, a subclass of neutron stars which have such an extremely strong magnetic field. The pulse period of 9 seconds is typical of magnetars, and this strong magnetic field prevents the stellar wind of the primary star from being captured by a neutron star, which can explain why LS 5039 does not exhibit properties similar to X-ray pulsars (X-ray pulsars usually occur in X-ray binary systems, where the stellar winds are captured by its companion star).

Interestingly, the 30 magnetars that have been found so far have all been found as isolated stars, so their existence in gamma-ray binaries was not considered a mainstream idea. Besides this new hypothesis, the team suggests a source that powers the non-thermal emission inside LS 5039–they propose that the emission is caused by an interaction between the magnetar’s magnetic fields and dense stellar winds.

Indeed, their calculations suggest that gamma-rays with energies of several megaelectronvolts, which has been unclear, can be strongly emitted if they are produced in a region of an extremely strong magnetic field, close to a magnetar.

These results potentially settle the mystery as to the nature of the compact object within LS 5039, and the underlying mechanism powering the binary system. However, further observations and refining of their research is needed to shed new light on their findings.

###

Authors: Hiroki Yoneda (1,2,3), Kazuo Makishima (1,2), Teruaki Enoto (4), Dmitry Khangulyan (5), Takahiro Matsumoto (1), Tadayuki Takahashi (1,2)

Author affiliation:

1. Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan

2. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8583, Japan

3. RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

4. Extreme Natural Phenomena RIKEN Hakubi Research Team, Cluster for Pioneering Research, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan

5. Department of Physics, Rikkyo University, 3-34-1 Nishi Ikebukuro, Toshima, Tokyo 171-8501, Japan

Source: https://bioengineer.org/research-suggests-our-galaxys-brightest-gamma-ray-binary-system-may-be-powered-by-a-magnetar-star/

research-suggests-our-galaxy’s-brightest-gamma-ray-binary-system-may-be-powered-by-a-magnetar-star

Bioengineer

Physical activity reduces cardiovascular risk in rheumatic patients

People with diseases such as rheumatoid arthritis and lupus are more likely to have heart attacks, angina, and strokes. A

Published

on

People with diseases such as rheumatoid arthritis and lupus are more likely to have heart attacks, angina, and strokes. A review of the scientific literature on the subject shows that regular exercise improves vascular function in these patients

The risk of developing atherosclerosis – a narrowing of the arteries as cholesterol plaque builds up, leading to obstruction of blood flow – is higher for people with autoimmune rheumatic diseases than for the general population. As a result, they are more likely to have heart attacks and other cardiovascular disorders.

The good news, according to a new study published in Rheumatology, is that regular exercise is a powerful weapon against vascular dysfunction in these patients.

In the article, researchers working in Brazil and the United Kingdom report the results of a systematic review of the scientific literature on the subject. The review, which was supported by FAPESP, covered ten studies involving 355 volunteers with various diseases, such as rheumatoid arthritis, lupus, and spondyloarthritis (inflammation of the spine). The subjects took exercise programs such as walking in a park or on a treadmill, stationary cycling, high-intensity interval training, and muscle building. Most of the programs lasted 12 weeks.

“Our analysis of the results showed that exercise improved small and large vessel endothelial function to a clinically significant extent. Accordingly, we suggested that exercise can be considered ‘medication’ for these patients because of its potential to reduce the incidence of cardiovascular events,” said Tiago Peçanha, first author of the article. Peçanha is a postdoctoral fellow at the University of São Paulo’s Medical School (FM-USP) in Brazil.

These rheumatic diseases, he explained, are the result of an imbalance in the immune system that leads to the production of antibodies against the subject’s own organism, especially joints, muscles, ligaments and tendons. While there is no definitive cure for these diseases, they can be controlled by treatment with anti-inflammatory drugs, immunosuppressants, and biologics (drugs from living sources).

“Treatment doesn’t prevent patients from developing certain co-morbidities. Cardiovascular disease is the most worrisome,” Peçanha said. “The risk of heart attack is twice as high for people with rheumatoid arthritis as for healthy people. For people with lupus or psoriatic arthritis, the incidence of ischemic events [heart attack, angina and stroke] is between twice and five times as high.”

Atherosclerosis develops rapidly in these patients owing to the chronic inflammation associated with rheumatic disease and continuous use of anti-inflammatory drugs. “It all begins with changes in blood vessel structure and function,” Peçanha said. “The arteries gradually harden and stop being able to dilate when necessary. Changes occur above all in the endothelium [the layer of cells lining the interior surface of blood vessels]. Alterations in vascular function, especially endothelial function, are considered initial markers of atherosclerosis for this reason.”

The systematic review showed that exercise improved small and large vessel vascular function in patients with autoimmune rheumatic diseases. However, the authors note that given the small number of studies reviewed the evidence is not sufficient to state categorically that exercise also promotes a structural recovery of damaged arteries.

“This area [physical activity in rheumatology] is still new, so more research is needed to identify the best exercise protocols and investigate such aspects as safety and adherence,” Peçanha said. “In any event, the data in our study underlines the importance of regular exercise to prevent and treat cardiovascular disease in these patients.”

For people with rheumatic disease, as indeed for everyone else, Peçanha recommends at least 150 minutes of moderate to vigorous exercise per week. Aerobic exercise should predominate and be complemented by activities that foster strength and balance.

###

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

In the article, researchers working in Brazil and the United Kingdom report the results of a systematic review of the scientific literature on the subject. The review, which was supported by FAPESP, covered ten studies involving 355 volunteers with various diseases, such as rheumatoid arthritis, lupus, and spondyloarthritis (inflammation of the spine). The subjects took exercise programs such as walking in a park or on a treadmill, stationary cycling, high-intensity interval training, and muscle building. Most of the programs lasted 12 weeks.

Source: https://bioengineer.org/physical-activity-reduces-cardiovascular-risk-in-rheumatic-patients/

physical-activity-reduces-cardiovascular-risk-in-rheumatic-patients

Continue Reading

Bioengineer

An atlas of HIV’s favorite targets in the blood of infected individuals

Gladstone researchers have identified the blood cells most likely to be targeted by HIV during a real-life infectionCredit: Photo: Gladstone

Published

on

Gladstone researchers have identified the blood cells most likely to be targeted by HIV during a real-life infection

SAN FRANCISCO, CA–April 27, 2021–In the 40-some years since the beginning of the HIV/AIDS epidemic, scientists have learned a lot about the virus, the disease, and ways to treat it. But one thing they still don’t completely understand is which exact cells are most susceptible to HIV infection.

Without this knowledge, it is difficult to envision targeting these cells to protect the millions of people who encounter the virus for the first time every year, or the infected people in which infection will likely rebound if they go off therapy.

Scientists have known for a long time that the virus homes in on so-called memory CD4+ T cells, a type of cell that helps the human body build lasting immunity against pathogens. But that is still too broad a category to target for therapy.

“CD4+ T cells orchestrate the immune response against all kinds of pathogens, so you can’t just eliminate them to prevent HIV infections,” says Gladstone Associate Investigator Nadia Roan, PhD. “But if you can find the more specific subsets of CD4+ T cells that are highly susceptible to HIV infection, you may be able to specifically target those cells without detrimental side effects.”

Much knowledge about HIV infection comes from in vitro experiments (in a petri dish), where scientists expose CD4+ T cells cultured in the lab to the virus. These cell cultures are not a perfect model for the human body’s complex ecosystems in which infection normally takes place. Might in vitro infection yield a skewed view of the virus’s preference?

To answer this question, Roan and her team compared CD4+ T cells infected in vitro to the CD4+ T cells circulating in the blood of 11 individuals at various stages of infection. Some blood samples were taken before the donors had started treatment with antiretroviral therapy, some after. Yet others came from individuals who had stopped their treatment and were experiencing new rounds of infection.

Using technology they have honed over the years, the researchers established a detailed atlas of the CD4+ T cells in individuals not on antiretroviral treatment, which they have now published in the scientific journal Cell Reports.

“Our work affords novel insight into the basics of how HIV behaves in the human body, rather than just in a lab dish,” says Roan, who is also an associate professor of urology at UC San Francisco. “It informs our understanding of what really happens during an active infection, which is interesting in its own right. Moreover, we know that some infected cells become reservoirs of latent virus, so our work could help us better understand how the reservoir forms during an infection.”

The technology Roan and her team deployed, called CyTOF/PP-SLIDE, distinguishes cells with exquisite precision based on the proteins they contain or carry on their surface. With this information, the scientists can classify CD4+ T cells into myriad subsets, and then determine whether some subsets are more susceptible to infection than others.

A crucial perk of this technology is that it can trace infected cells back to their original state prior to infection.

“That’s important,” says Guorui Xie, PhD, a postdoctoral researcher in Roan’s lab and the first author of the study. “We know that when HIV infects cells, it remodels the cells such that they no longer contain the exact same levels of proteins as they did before infection. With CyTOF/PP-SLIDE, we can identify the uninfected cells that most closely match the infected ones in the same patient. These uninfected cells can give us important information about what the cells targeted by HIV resembled before the virus remodeled them.”

Roan’s team found that remodeling was indeed extensive in blood CD4+ T cells infected in vivo (in people) as well as in vitro. In the process, they made a surprising finding about one of HIV’s preferred targets. Prior studies have suggested that HIV prefers to infect a subtype of CD4+ T cells, called Tfh, and Roan’s team confirmed these cells to be susceptible to HIV. However, they also discovered that the virus can infect non-Tfh cells and remodel them such that they adopt features of Tfh cells.

“This result strikes a cautionary note in our field,” says Roan. “You really can’t tell which cells HIV prefers to target simply by looking at infected cells. You need to know what the cells looked like before remodeling.”

The scientists also found that remodeling causes infected blood cells to alter their surface in ways that may change how they move through the body. Roan prudently speculates that this might help the virus steer infected cells toward sites where it can infect even more cells.

“Whatever its exact purpose, remodeling is probably not just a chance event,” adds Roan. “A virus as small as HIV depends crucially on the resources provided by its host to grow and spread. It’s likely that nothing the virus does to its host cell is an accident.”

The profile of HIV’s favorite cells differed somewhat between in vitro and in vivo infections. Nevertheless, the researchers found one subset of cells that was preferentially infected in both cases, and could become a useful model for further lab studies.

The team also confirmed that not all CD4+ T cells are equally susceptible to HIV infection in vivo, which gives them hope that the most susceptible cells could eventually become targets of preventive interventions.

Xie and Roan are now planning to obtain blood samples from more donors to see whether HIV’s targets differ between a first infection and the return of the virus after a lapse in therapy, or between men and women. Ultimately, they would also like to look at in vivo-infected cells from mucosal tissues such as the gut and genital tract, where most HIV infections begin. But these samples are much harder to procure.

In the meantime, the researchers are making public the atlas of all the cells they have analyzed, along with the dozens of proteins they found to be affected in these cells after HIV infection, which they hope will be a valuable resource for the HIV research community.

“There is still much to discover in this atlas that may help uncover new insights into HIV infection and how it develops, and perhaps lead to the identification of new approaches for HIV/AIDS prevention,” says Roan.

###

About the Study

The paper “Characterization of HIV-induced remodeling reveals differences in infection susceptibility of memory CD4+ T cell subsets in vivo” was published in Cell Reports on April 27, 2021: https://www.cell.com/cell-reports/fulltext/S2211-1247(21)00354-5.

Other authors include Xiaoyu Luo, Tongcui Ma, Julie Frouard, Jason Neidleman, and Warner C. Greene from Gladstone Institutes; and Rebecca Hoh and Steven G. Deeks from UC San Francisco.

This work was supported by the National Institutes of Health (R01AI127219, R01AI147777, P01AI131374, and S10-RR028962), the amfAR Institute for HIV Cure Research (109301), the UCSF-Gladstone Center for AIDS Research (P30AI027763), and the James B. Pendleton Charitable Trust.

About Gladstone Institutes

To ensure our work does the greatest good, Gladstone Institutes (https://gladstone.org) focuses on conditions with profound medical, economic, and social impact–unsolved diseases. Gladstone is an independent, nonprofit life science research organization that uses visionary science and technology to overcome disease. It has an academic affiliation with the University of California, San Francisco.

https://gladstone.org/news/atlas-hivs-favorite-targets-blood-infected-individuals

Source: https://bioengineer.org/an-atlas-of-hivs-favorite-targets-in-the-blood-of-infected-individuals/

an-atlas-of-hiv’s-favorite-targets-in-the-blood-of-infected-individuals

Continue Reading

Bioengineer

Trial of existing antibiotic for treating Staphylococcus aureus Bacteremia begins

NIH-supported trial will test Dalbavancin in hospitalized adultsCredit: NIAID A clinical trial to test the antibiotic dalbavancin for safety and

Published

on

A clinical trial to test the antibiotic dalbavancin for safety and efficacy in treating complicated Staphylococcus aureus (S. aureus) bacteremia has begun. The trial will enroll 200 adults hospitalized with complicated S. aureus infection at approximately 20 trial sites around the United States. The trial is being sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

S. aureus is a leading cause of antibiotic-resistant infection. S. aureus infections led to nearly 20,000 deaths in 2017 in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC). This bacterium is of particular concern in healthcare-associated infections. S. aureus bacteremia–an infection of the blood–often requires inserting a central intravenous (IV) catheter to deliver long courses of antibiotics, an invasive procedure that can involve long-term care in healthcare facilities.

“As antibiotic-resistant infections become more widespread, better and easier treatment regimens are needed to ease the burden on both healthcare providers and patients,” said NIAID Director Anthony S. Fauci, M.D. “By investigating existing antibiotics for their action on a broader array of bacterial infections, we may be able to generate new treatment regimens more efficiently.”

The antibiotic dalbavancin has strong activity against gram-positive bacteria, including methicillin-resistant S. aureus, which suggests it could be an effective treatment for S. aureus bacteremia. Dalbavancin is currently FDA-approved in the United States for treating acute bacterial skin and skin structure infections, including those caused by S. aureus. If the two-dose regimen being tested in this trial proves effective, it could lead to a shorter, less invasive treatment for S. aureus bacteremia that does not require an indwelling IV access for daily therapy.

The Phase 2b trial is being conducted by the NIAID-funded Antibacterial Resistance Leadership Group (ARLG) under the leadership of Thomas Holland, M.D., of Duke University (Durham, North Carolina.) It is called the “Dalbavancin as an Option for Treatment of S. aureus Bacteremia (DOTS)” trial. Patients who have stabilized after initial treatment of their bacteremia will be eligible for enrollment in this study.

“Dalbavancin is appealing as a potential option for treatment of these serious S. aureus infections, and we need high quality data to find out if it works,” said Dr. Holland, “This trial will provide clinicians and patients with that data.”

One hundred participants will be randomized to receive the standard of care for complicated infections, including appropriate antibiotics, and 100 participants will receive two doses of dalbavancin intravenously. The doses will be given one week apart. Most participants receiving dalbavancin will be given 1500 milligrams (mg) per dose. Participants with signs of kidney dysfunction will be given 1125 mg per dose. All participants will be followed for approximately 70 days after enrollment, and up to six months if they have vertebral osteomyelitis, an infection of the vertebrae.

At the end of the trial, multiple patient outcomes will be assessed: survival; additional complications (such as relapse) or clinical failures; drug-related adverse events; and overall quality of life. The therapeutic regimen will have met the primary endpoint of the trial if participants who received dalbavancin fare better on these metrics than those who received the current standard of care. This trial could validate a dalbavancin regimen of only one dose a week for two weeks, compared to daily doses administered intravenously for four to six weeks with the current standard of care.

###

The ARLG is a clinical research consortium working to reduce the impact of antimicrobial resistance. It is funded through NIH grant UM1AI104681. For more information about this trial, visit ClinicalTrials.gov and search identifiers NCT04775953.

###

NIAID conducts and supports research–at NIH, throughout the United States, and worldwide–to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.

NIH…Turning Discovery Into Health®

Source: https://bioengineer.org/trial-of-existing-antibiotic-for-treating-staphylococcus-aureus-bacteremia-begins/

trial-of-existing-antibiotic-for-treating-staphylococcus-aureus-bacteremia-begins

Continue Reading

Title

ZDNET5 hours ago

Apple releases emergency update for older iPhones and iPads

If you're running iOS 12, this is an update for you.

Crunchbase8 hours ago

Macrometa Locks Down $20M To Be The Amazon Prime Of Edge Computing

Palo Alto, California-based edge compute company Macrometa closed a $20 million Series A less than eight months after announcing its...

Cointelegraph11 hours ago

Crypto miners eye cheap power in Texas, but fears aired over impact on the grid

Can Texas meet the electricity demands of migrating Chinese Bitcoin miners?

Coinpedia21 hours ago

Bitcoin Cash Price Prediction, Will BCH Hit Incredible Surges At $1000?

According to Coinpedia's formulated Bitcoin Cash price prediction, the coin's price may strike a maximum of $1417.33 by the year...

Blockchain news1 day ago

US Space Force Makes its Foray into the NFT Metaverse

The United States Space Force is launching an NFT series named after Neil Armstrong.

Reuters1 day ago

EXCLUSIVE Galp to hold off on LNG investment until Mozambique ensures security

Portugal's Galp Energia (GALP.LS), a partner in an Exxon Mobil-led gas consortium in Mozambique, will not invest in onshore plants...

Techcrunch1 day ago

Golden Gate Ventures forecasts a record number of exits in Southeast Asia – TechCrunch

Despite the pandemic’s economic impact, Southeast Asia’s startup ecosystem has proven to be very resilient. In fact, a new report...

Bioengineer1 day ago

Physical activity reduces cardiovascular risk in rheumatic patients

People with diseases such as rheumatoid arthritis and lupus are more likely to have heart attacks, angina, and strokes. A

Bioengineer2 days ago

An atlas of HIV’s favorite targets in the blood of infected individuals

Gladstone researchers have identified the blood cells most likely to be targeted by HIV during a real-life infectionCredit: Photo: Gladstone

ZDNET2 days ago

SSD market to reach $51.5 billion in revenue by 2025: IDC

The IDC is predicting that SSD unit shipments will increase with a CAGR of 7.8% in coming years.

Review

    Select language

    Trending