Where do the "wanderers" in the universe come from? It's related to this "tidal bridge" | Science and Technology Weekly

Compiled by Zhou Shuyi and Pingsheng

Aspirin may stop some cancers from metastasizing

Aspirin can prevent cancer metastasis by relieving immune suppression, a study published in Nature on March 6 shows. This discovery may help develop more effective anti-metastatic therapies.

Cancer metastasis refers to the spread of cancer cells from the primary site to distant organs, and is the culprit for 90% of cancer-related deaths worldwide. Metastatic cancer cells have escaped from the immunosuppressive microenvironment of the primary site. In theory, immune T cells should be able to more easily identify and eliminate these "lone" cancer cells. However, this is not the case in reality, and many types of cancer are still accompanied by an extremely high risk of metastasis.

New research has found that the "dereliction of duty" of T cells is actually related to seemingly irrelevant platelets. The thromboxane TXA2 secreted by platelets not only participates in the coagulation process, but also binds to the surface receptors of T cells, inhibiting their immune effects and hindering the immune system from attacking and eliminating metastatic cancer cells.

Mice with breast cancer develop metastatic foci in their lungs (dark spots on the left), while mice with unsuppressed T cells do not (right) | Jie Yang

On the other hand, aspirin itself is a cyclooxygenase (COX) inhibitor that can inhibit the activity of COX-1 and COX-2 enzymes, and COX-1 is an essential molecule for platelet production of TXA2. Therefore, the researchers speculated that aspirin can solve the problem of T cell function inhibition from the source. Subsequent animal experiments showed that compared with the control group, the level of TXB2 (a metabolite of TXA2) in the serum of mice that ingested aspirin was significantly reduced, and the number of cancer cell metastases in the lungs was less.

The researchers believe that these findings suggest that aspirin may be used as a low-cost adjuvant therapy and a powerful supplement to other immunotherapies. However, Harvey Roweth, a cancer biologist at the University of Reading in the UK, reminded that this study was only conducted in a mouse model, and the conditions of human patients are often more complex and variable. The specific effects need further evaluation, and patients should seek treatment from regular medical institutions. "We can't say that cancer patients should take aspirin - at least not yet."

Study shows surgery before holidays less effective

A new study confirms a long-standing concern: An analysis of nearly 430,000 patients found that surgery performed the day before a holiday was associated with poorer outcomes and higher rates of subsequent complications, readmissions, and mortality. The related paper was published on March 4 in JAMA Network Open.

Image source: CC0 Public Domain

The researchers analyzed data from 429,691 adult patients in Ontario, Canada, who underwent one of 25 common surgical procedures between 2007 and 2019. Patients were divided into two groups: those who underwent surgery the day before the weekend (Friday or before a holiday) and those who underwent surgery the day after the weekend (Monday or after a holiday). The study evaluated short-term (30 days), mid-term (90 days), and long-term (one year) outcomes after surgery, including mortality, readmission rate, complications, length of hospital stay, and duration of surgery.

The results showed that patients who underwent surgery before the weekend had longer hospital stays and were 5% more likely to die, have complications, and be readmitted within 30 days. The mortality rate was 9% higher within 30 days after surgery, and it increased over time: 10% higher after 90 days and 12% higher after one year.

The researchers said the poorer outcomes of surgeries before the holiday may be related to insufficient hospital staffing and differences in perioperative care processes before the holiday. Surgeons who performed surgeries on Fridays were younger (median age 47 years, 48 ​​years) and less experienced (median years of practice 14 years, 17 years) than those who performed surgeries on Mondays. In addition, although the researchers were careful not to mention it, doctors are also human and may be distracted from work by daydreaming about vacation plans before the holiday.

An American company has bred mammoth-like woolly mice and claims that it is "hopeful to revive mammoths in 2028"

On March 4, local time, Colossal Biosciences, a US start-up biotechnology company, announced that they had bred mice with "mammoth characteristics" in the laboratory - mice with thick long hair, taking a step towards the goal of "resurrecting" the extinct mammoth. The relevant paper was published in bioRxiv as a preprint on March 4, without peer review.

Colossal Biosciences was founded by renowned scientist George Church and others. It is the first company to apply CRISPR gene editing technology to species restoration, critically endangered species protection, and key ecosystem reconstruction. Since announcing its "De-Extinction" plan in 2021, the company has continued to attract attention from the scientific community.

"Hairy Mouse" | Colossal Biosciences

According to the information presented by the company, the genetically modified mice grew thick hair. A total of 8 genes were modified, 7 of which were related to hair growth and the other 1 was related to increased body fat percentage. Currently, the long-haired mice created by the research team are only a few months old, and they have not had much time to study whether and how these genetic modifications affect the long-term health of the mice, including fertility and cancer risk. The research team plans to further test whether these long-haired mice are better at dealing with the cold than other mice and study their hair development.

Colossal Biosciences said that the experiment of breeding "hairy mice" is aimed at verifying the feasibility of the technology. The next step is to turn to gene editing of embryos of Asian elephants, close relatives of mammoths. However, considering that Asian elephants are endangered species, subsequent research may face a lot of regulatory obstacles. Lynch, a biologist at the University at Buffalo, State University of New York, described this technology as "very cool." However, Preston, an expert at the University of Montana, questioned: "Changing the hair of Asian elephants or making them cold-resistant is not the same as resurrecting mammoths. This is just genetic modification of existing species."

The better the semen quality, the longer men live

The largest study of its kind, based on a 50-year follow-up survey of nearly 80,000 men, found that the better the quality of semen, the longer the male life expectancy. Compared with men with the worst semen quality, those with the best semen quality have an extra life expectancy of two to three years. The relevant paper was published in Human Reproduction on March 5.

The new study included data from 78,284 Danish men who underwent semen quality assessments between 1965 and 2015 due to marital infertility. Semen quality ranged from no sperm to very good. The assessment items included semen volume, sperm concentration, and the proportion of sperm that were motile and normally shaped. During the follow-up period, the researchers tracked the life expectancy of the participants using death data from the Danish National Register. The study also took into account education level as an indicator of socioeconomic status, as well as medical conditions in the decade before the participants provided semen samples.

The analysis showed that the higher the semen quality, the longer the life expectancy, and medical conditions and education levels could not explain this association. Men with a total sperm motility count (the number of sperm that can move or "swim") of more than 120 million/mL have a life expectancy of 88.3 years, and men with a total motility count of less than 5 million/mL have a life expectancy of 77.6 years, a difference of up to 2.7 years. The researchers believe that semen quality may be an indicator of other potential factors and is related to overall health. Therefore, assessing the semen quality of men may prevent problems before they occur and detect other long-term health risks early. The authors said that in the future, further research will be conducted to determine whether semen quality is related to premature death from specific causes such as cancer or heart disease, and attempts will be made to identify relevant biomarkers to determine which groups of men may be at risk of health risks.

Where do the universe's wanderers come from?

A new study proposes a new mechanism for the formation of rogue planet-mass objects (PMOs): these mysterious objects with masses between stars and planets are neither the products of traditional star formation processes nor expelled giant planets, but are directly formed through tidal interactions in the circumstellar disks of young stars.

PMOs are "wanderers" in the universe, with masses close to those of giant planets, but not bound by any star. Over the past 20 years, scientists have believed that PMOs may be extremely low-mass stars formed by the collapse of molecular clouds or giant planets ejected from their parent star systems. However, neither of these two theories can explain the abundance of PMOs, the complexity of multi-body systems, and their consistency with the motion characteristics of stars.

Through high-precision fluid dynamics simulations, the researchers found that when the circumstellar disks of two young stars meet closely at a specific angle and speed, the tidal force stretches and forms an elongated "tidal bridge". These bridge-like structures are further contracted into dense linear molecular clouds under the action of gravity, and eventually break and collapse into independent celestial bodies, forming PMOs.

An example of a three-dimensional fluid dynamics simulation of the formation of a "tidal bridge" between encountering circumstellar disks and the collapse to form a PMO binary.

Simulations show that this process is extremely efficient in dense star clusters. When the circumstellar disk passes by at a speed of 2 to 3 kilometers per second and a distance of 300 to 400 AU, the linear density of the "tidal bridge" exceeds the critical value of stability, and multiple PMOs can be produced simultaneously, and even a compact binary or triple star system can be formed. In the dense Trapezium cluster, stars encounter frequently, and the stellar velocity dispersion is just between 2 and 3 kilometers per second, thus forming a "cradle" for PMOs and nurturing the largest group of PMOs observed so far. However, PMOs are relatively rare in the IC 348 cluster, where the stellar motion velocity dispersion is very small. At the same time, extended gas disks are retained around these formed PMOs. This is highly consistent with the observational results, further verifying the reliability of the theory.

This mechanism can explain the abundance and properties of PMOs, suggesting that they may represent a new type of celestial body, providing a new idea for exploring the formation mechanism of rogue planets in the universe. PMOs may constitute a type of celestial body in the universe that is neither a star nor a planet, which is expected to help scientists study the boundary between star formation and planet formation. The relevant paper was published in Science Advances on February 27.

Light transformed into 'supersolid' for first time

Researchers have used lasers to create for the first time a strange solid that can flow like a fluid. Studying it will help scientists better understand the strange quantum states of matter. The related paper was published in Science on March 5.

Supersolids have both zero viscosity and a crystal-like structure with orderly atomic arrangements. These exotic materials have no counterparts outside the quantum realm. They have previously been created only in experiments that cool atoms to extremely low temperatures, where otherwise negligible quantum effects dominate.

But in this experiment, the researchers replaced the ultracold atoms with the semiconductor aluminum gallium arsenide and lasers. They shone the lasers on a small piece of the semiconductor with a narrow ridge pattern. The complex interaction between the light and the material ultimately formed a hybrid particle called a polariton. The ridge pattern confines the movement of these "quasiparticles" and their energy, allowing the polaritons to form a supersolid.

Daniele Sanvitto of Italy's National Research Council (CNR) said the team had to very precisely quantify the multiple properties of the trapped and converted light to prove that it was both a solid and an inviscid fluid. This was a challenge, he said, because scientists had never before created a supersolid made of light and evaluated it experimentally.

Alberto Bramati of the Sorbonne University in France said the new experiment helps physicists improve their overall understanding of how quantum matter changes state through phase transitions. He said the team clearly demonstrated that they had created a supersolid, but more measurements need to be made to understand its properties. (China Science Daily)

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