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Comment by Dr. Krishna Kumari Challa on August 1, 2020 at 5:16am

How human sperm really swim: New research challenges centuries-old assumption

A breakthrough in fertility science by researchers from Bristol and Mexico has shattered the universally accepted view of how sperm 'swim'.

More than three hundred years after Antonie van Leeuwenhoek used one of the earliest microscopes to describe human sperm as having a "tail, which, when swimming, lashes with a snakelike movement, like eels in water", scientists have revealed this is an optical illusion.

Using state-of-the-art 3-D microscopy and mathematics, now scientists

have pioneered the reconstruction of the true movement of the sperm tail in 3-D.

Using a high-speed camera capable of recording over 55,000 frames in one second, and a microscope stage with a piezoelectric device to move the sample up and down at an incredibly high rate, they were able to scan the sperm swimming freely in 3-D.

The ground-breaking study, published in the journal Science Advances, reveals the sperm tail is in fact wonky and only wiggles on one side. While this should mean the sperm's one-sided stroke would have it swimming in circles, sperm have found a clever way to adapt and swim forwards. Human sperm figured out if they roll as they swim, much like playful otters corkscrewing through water, their one-sided stoke would average itself out, and they would swim forwards. The sperms' rapid and highly synchronized spinning causes an illusion when seen from above with 2-D microscopes—the tail appears to have a side-to-side symmetric movement, "like eels in water", as described by Leeuwenhoek in the 17th century.

The present discovery shows sperm have developed a swimming technique to compensate for their lop-sidedness and in doing so have ingeniously solved a mathematical puzzle at a microscopic scale: by creating symmetry out of asymmetry. The otter-like spinning of human sperm is however complex: the sperm head spins at the same time that the sperm tail rotates around the swimming direction. This is known in physics as precession, much like when the orbits of Earth and Mars precess around the sun.

This discovery will revolutionize our understanding of sperm motility and its impact on natural fertilization. So little is known about the intricate environment inside the female reproductive tract and how sperm swimming impinge on fertilization. These new tools open our eyes to the amazing capabilities sperm have.

"Human sperm uses asymmetric and anisotropic flagellar controls to regulate swimming symmetry and cell steering" Science Advances (2020). DOI: 10.1126/sciadv.aba5168

https://phys.org/news/2020-07-human-sperm-centuries-old-assumption....

 

Comment by Dr. Krishna Kumari Challa on August 1, 2020 at 5:04am

Scientists test a 'bispecific' antibody that helps T cells zero in on treatment-resistant cancers

Although immunotherapy has achieved increasing prominence in the panoply of innovative cancer treatments, it remains an imperfect tool—too many tumors simply do not respond.

To the rescue is an evolving class of engineered proteins that go by the unusual name of bispecific antibodies. As their name implies, these proteins have dual recognition capability: They are engineered to home in on a T cell surface receptor as well as bind to the surface antigen of a cancer cell itself. The aim is to bring the two types of cells together and to activate the tumor annihilating capability of T cells.

Regeneron's anticancer innovation has grown out of a sobering reality: Certain cancers have developed deceptive strategies allowing them to resist immunotherapy. Resistance among cancers is as daunting a concern as infections caused by drug-resistant bacteria.

Several common cancers have a noteworthy history of thwarting checkpoint blockade immunotherapy, a treatment that relies on the strength of T cells to kill tumors. The investigational bispecific antibodies are designed to help overcome cancer-cell resistance.

Checkpoint blockade immunotherapy is itself an innovative form of cancer therapy that relies on drugs known as immune checkpoint inhibitors. This class of therapeutics is designed to treat multiple forms of cancer by engaging the body's immune system—its T cells—to recognize and attack malignant cells. Keytruda, a medication that helped revolutionize the treatment of non-small-cell lung cancer, is a checkpoint inhibitor.

All checkpoint inhibitors are based on a deceptively simple principle: Cancer cells possess a protein dubbed PD-L1. T cells have a surface protein called PD1. Tricky cancer cells use their PD-L1 proteins to elude T cells, to get past the guards—the checkpoints—an activity that allows tumors to proliferate and spread.

Multiple cancers that range from Hodgkins lymphoma to lung, bladder, ovarian and kidney cancers may initially respond to checkpoint inhibitors, but soon develop resistance. The Regeneron team studied two bispecific antibodies that each target a T cell protein dubbed CD28. At the same time, they analyzed two tumor-specific antigens. The bispecific antibodies attracted both T cells and the cancer antigens, enhancing the potential of cancer cell death by T cells.

Waite and colleagues found that bispecific antibodies enhanced the effectiveness of treating the anti-PD-1 checkpoint blockade in mouse models. The scientists also say the combination sensitized, previously resistant tumors to treatment. The bispecific antibodies showed few signs of toxicity and did not provoke dangerous systemic responses from T cells.

https://medicalxpress.com/news/2020-07-scientists-bispecific-antibo...

Janelle C. Waite et al. Tumor-targeted CD28 bispecific antibodies enhance the antitumor efficacy of PD-1 immunotherapy, Science Translational Medicine (2020). DOI: 10.1126/scitranslmed.aba2325

Comment by Dr. Krishna Kumari Challa on July 31, 2020 at 6:04am

Chemists craft molecular scalpels to clear unwanted proteins from cell surfaces

https://phys.org/news/2020-07-chemists-craft-molecular-scalpels-unw...

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https://medicalxpress.com/news/2020-07-stem-cells-optic-nerve-enabl...

Researchers discover stem cells in the optic nerve that enable preservation of vision

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https://phys.org/news/2020-07-nano-sponges-solid-acid-carbon-dioxid...

Nano-sponges of solid acid transform carbon dioxide to fuel and plastic waste to chemicals

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Comment by Dr. Krishna Kumari Challa on July 31, 2020 at 4:51am

Stay or leave? A tale of two virus strategies revealed by math

As small and relatively simple as they may be, even viruses have strategies. Now, researchers in Japan report that they can evaluate two of these strategies through a combination of biology and math, providing a new tool for insight into viruses that could be used to develop better treatments.

Unable to reproduce on their own, viruses replicate by infecting a living organism's cells and getting the cells to make copies of them. Two main options exist for copies of a virus's genetic structure made in the cell: stay in the cell as a template for making even more copies or get packaged as a new virus and leave in an attempt to infect other cells.

Each option comes with trade-offs, so an individual virus's strategy of how much weight to place on each one should directly influence the progression of an infection and any health problems it may cause.

"While such strategies are expected to be in play, showing the existence of the strategy itself has been difficult.

Mathematical model the behavior of two hepatitis C virus strains now provides a means to evaluate two such strategies.

While one of the studied virus strains causes severe and sudden symptoms, the other is a genetically modified version developed in the laboratory to increase virus production, which is important for creating stocks of viruses for the development of treatments and vaccines.

By finding the range of model parameters that reasonably reproduce the experimentally observed results, they could quantify differences in behavior between the two strains. In particular, they estimated that the fraction of replicated genetic code packaged by the lab-developed strain to make new viruses was three times that for the other strain, indicating the preference of a leave strategy for the former and a stay strategy for the latter.

"The stay strategy initially produces copies of the genetic code faster, while the leave strategy emphasizes newly infecting cells,

Such strategies may be common in other chronic virus infections, and understanding them could help us develop effective therapeutic methods to counter individual virus strategies

"Should a viral genome stay in the host cell or leave? A quantitative dynamics study of how hepatitis C virus deals with this dilemma," PLOS Biology (2020). DOI: 10.1371/journal.pbio.3000562

https://phys.org/news/2020-07-tale-virus-strategies-revealed-math.html

Comment by Dr. Krishna Kumari Challa on July 31, 2020 at 4:44am

Cosmic tango between the very small and the very large

While Einstein's theory of general relativity can explain a large array of fascinating astrophysical and cosmological phenomena, some aspects of the properties of the universe at the largest-scales remain a mystery. A new study using loop quantum cosmology—a theory that uses quantum mechanics to extend gravitational physics beyond Einstein's theory of general relativity—accounts for two major mysteries. While the differences in the theories occur at the tiniest of scales—much smaller than even a proton—they have consequences at the largest of accessible scales in the universe. The study, which appears online July 29 in the journal Physical Review Letters, also provides new predictions about the universe that future satellite missions could test.

While a zoomed-out picture of the universe looks fairly uniform, it does have a large-scale structure, for example because galaxies and dark matter are not uniformly distributed throughout the universe. The origin of this structure has been traced back to the tiny inhomogeneities observed in the Cosmic Microwave Background (CMB)—radiation that was emitted when the universe was 380 thousand years young that we can still see today. But the CMB itself has three puzzling features that are considered anomalies because they are difficult to explain using known physics.

"While seeing one of these anomalies may not be that statistically remarkable, seeing two or more together suggests we live in an exceptional universe.

A recent study in the journal Nature Astronomy proposed an explanation for one of these anomalies that raised so many additional concerns, they flagged a 'possible crisis in cosmology.' Using quantum loop cosmology, however, we have resolved two of these anomalies naturally, avoiding that potential crisis."

Research over the last three decades has greatly improved our understanding of the early universe, including how the inhomogeneities in the CMB were produced in the first place. These inhomogeneities are a result of inevitable quantum fluctuations in the early universe. During a highly accelerated phase of expansion at very early times—known as inflation—these primordial, miniscule fluctuations were stretched under gravity's influence and seeded the observed inhomogeneities in the CMB.

Abhay Ashtekar et al, Alleviating the Tension in the Cosmic Microwave Background using Planck-Scale Physics, Physical Review Letters (2020). DOI: 10.1103/PhysRevLett.125.051302

https://phys.org/news/2020-07-cosmic-tango-small-large.html?utm_sou...

Comment by Dr. Krishna Kumari Challa on July 31, 2020 at 4:34am

Ancient mountain formation and monsoons helped create a modern biodiversity hotspot

https://phys.org/news/2020-07-ancient-mountain-formation-monsoons-m...

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Origami microbots: Centuries-old artform guides cutting-edge advances in tiny machines

https://techxplore.com/news/2020-07-origami-microbots-centuries-old...

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Fear conditioning: Transcranial stimulation to prevent fear memories from returning

A research group from the University of Bologna has succeeded in modifying the negative effect of a returning memory that triggers fear, and developed a new non-invasive experimental protocol. The result of this study, published in the journal Current Biology, is an innovative protocol that combines fear conditioning—a stimulus associated with something unpleasant that induces a negative memory—and the neurostimulation of a specific site of the prefrontal cortex.

This process alters the perception of an unpleasant (aversive) event so that it will no longer induce fear. "This experimental protocol combining transcranial stimulation and memory reconsolidation allowed us to modify an aversive memory that the participants had learned the day before," explains Sara Borgomaneri, a researcher at the University of Bologna and first author of the study. "This result has relevant repercussions for understanding how memory works. It might even lead to the development of new therapies to deal with traumatic memories."

Borgomaneri et al., State-dependent TMS over prefrontal cortex disrupts fear memory reconsolidation and prevents the return of fear. Current Biology, (2020).

https://medicalxpress.com/news/2020-07-transcranial-memories.html?u...

Comment by Dr. Krishna Kumari Challa on July 30, 2020 at 5:41am

‘Keystone’ Species Key To Rebuilding Gut Microbiota After Antibiotics The discovery of gut bacteria critical to restoring gut health offers new insights into microbiome recovery after antibiotic treatment.

https://www.asianscientist.com/2020/07/in-the-lab/keystone-gut-micr...

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Some Uninfected People Have T-Cell Immunity To COVID-19 Researchers were surprised to find memory T-cells in people with no history of SARS, COVID-19, or contact with SARS or COVID-19 patients.

https://www.asianscientist.com/2020/07/health/memory-t-cell-immunit...

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New Report Identifies The 'Greatest Risk' to Human Health, And It's Not a Virus. It is air pollution!

https://www.sciencealert.com/air-pollution-greatest-risk-to-global-...

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Scientists Start Assembling The World's Largest Nuclear Fusion Experiment It'll be 10 times hotter than the Sun.

https://www.sciencealert.com/scientists-start-assembling-the-world-...

Comment by Dr. Krishna Kumari Challa on July 30, 2020 at 5:20am

Meta-Research: International authorship and collaboration across bioRxiv preprints

Preprints are becoming well established in the life sciences, but relatively little is known about the demographics of the researchers who post preprints and those who do not, or about the collaborations between preprint authors. Here, based on an analysis of 67,885 preprints posted on bioRxiv, it was found that some countries, notably the United States and the United Kingdom, are overrepresented on bioRxiv relative to their overall scientific output, while other countries (including China, Russia, and Turkey) show lower levels of bioRxiv adoption. This research also describes a set of ‘contributor countries’ (including Uganda, Croatia and Thailand): researchers from these countries appear almost exclusively as non-senior authors on international collaborations. They also found multiple journals that publish a disproportionate number of preprints from some countries, a dynamic that almost always benefits manuscripts from the US.

https://elifesciences.org/articles/58496?utm_source=content_alert&a...

Comment by Dr. Krishna Kumari Challa on July 30, 2020 at 5:12am

Research team exactly solves experimental puzzle in high temperature superconductivity

https://phys.org/news/2020-07-team-experimental-puzzle-high-tempera...

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https://phys.org/news/2020-07-simulating-quantum-butterfly-effect-r...

Simulating quantum 'time travel' disproves butterfly effect in quantum realm

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Microbes revived after 100 million years

Scientists have managed to wake up microbes that have been buried deep beneath the sea floor — apparently in a dormant state — since dinosaurs walked on Earth

https://www.nature.com/articles/s41467-020-17330-1?utm_source=Natur...

Comment by Dr. Krishna Kumari Challa on July 30, 2020 at 5:08am

Gold nanosensor spots difference between dengue, Zika

A new class of nanosensor developed in Brazil could more accurately identify dengue and Zika infections, a task that is complicated by their genetic similarities and which can result in misdiagnosis. The technique uses gold nanoparticles and can "observe" viruses at the atomic level.

Dengue is a disease that kills—and can do so quickly if the right diagnosis is not made. As for Zika, it offers risks for fetuses to develop microcephaly, and we can't let pregnant women spend seven or eight months wondering whether they have the virus or not

Belonging to the Flavivirus genus in the Flaviviridae family, Zika and dengue viruses share more than 50 percent similarity in their amino acid sequence. Both viruses are spread by mosquitos and can have long-term side effects. The Flaviviridae virus family was named after the yellow fever virus and comes from the Latin word for golden, or yellow, in color.

Diagnosing dengue virus infections is a high priority in countries affected by annual epidemics of dengue fever. The correct diagnostic is essential for patient managing and prognostic as there are no specific antiviral drugs to treat the infection.

It is almost impossible to differentiate between dengue and Zika viruses.

A serologic test that detects antibodies against dengue also captures Zika-generated antibodies. Scientists call this 'cross-reactivity'. 

There is also no specific antiviral treatment for Zika and the search for a vaccine is ongoing.

Virus differentiation is important to accurately measure the real impact of both diseases on public health. The most widely used blood test, the enzyme-linked immunosorbent assay (ELISA), is limited in its ability to tell the difference between the viruses.

As dengue has four variations, known as serotypes, the team created four different nanoparticles and covered each of them with a different dengue protein. They applied ELISA serum and a blood sample. The researchers found that sample antibodies bound with the viruses' proteins, changing the pattern of electrons on the gold nanoparticle surface.

The researchers  could see this change by applying certain frequencies of light on the nanoparticle's surface. Dengue proteins absorbed light—Zika ones did not.

The study argues that the gold nanoparticle-based test is more precise than other blood antibody tests because of its high sensitivity and capacity to identify which virus has been detected. The fact that this test doesn't require reagents and uses ELISA equipment, which is widely available and low cost.

Alice F. Versiani et al. Nanosensors based on LSPR are able to serologically differentiate dengue from Zika infections, Scientific Reports (2020). DOI: 10.1038/s41598-020-68357-9

https://phys.org/news/2020-07-gold-nanosensor-difference-dengue-zik...

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