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Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 12:12pm

Strange Case : Kids Develop Coronavirus Antibodies Without Ever Testing Positive

From the early days of the coronavirus pandemic, scientists observed that children seemed to be less susceptible to developing COVID-19, although the exact reasons why remain unclear.
Now, an unusual case in Australia may provide unique insight into the mystery. In this family of five, the two parents became sick with COVID-19 after attending an interstate wedding without their children. However, the symptoms didn't show until days after they had returned from the trip.

Nonetheless, completely unbeknownst to them, they had brought SARS-CoV-2 into their home, and exposed their children to it. Once both the parents developed symptoms – including cough, congested nose, fever and headache – the entire family was tested for the virus. The parents' tests came back positive. The children's tests came back negative.
Healthcare workers asked the family to repeat the tests, but again the children's tests came back negative for SARS-CoV-2, even though two of the boys in the family (aged 9 and 7) had mild symptoms.
The youngest child, a 5-year-old daughter, remained asymptomatic throughout the entire episode, even though she was frequently sleeping in the same bed as the parents during their sickness (physical distancing precautions not feasible in the household during their quarantine).

Intrigued by the children's negative results while living in such close proximity to their infected parents, researchers asked the family to take part in a study, analysing samples of their blood, saliva, stools, and urine, and taking nose and throat swabs every two to three days.

Strangely enough, despite repeated polymerase chain reaction (PCR) tests showing the children were consistently SARS-CoV-2 PCR negative, the researchers found SARS-CoV-2 specific antibodies in saliva of all the family members, and in detailed serology testing.

In other words, the children never tested positive for the virus, but some level of exposure to the virus had nonetheless triggered an immune response inside them, and one seemingly capable of countering the infection.
The youngest child, who showed no symptoms at all, had the strongest antibody response. Despite the active immune cell response in all children, levels of cytokines, molecular messengers in the blood that can trigger an inflammatory reaction, remained low. This was consistent with their mild or no symptoms.
The fact these children were able to shut down the virus and without even showing a positive test result suggests they have some level of their immune system which is able to respond and deal effectively with the virus, without them ever becoming very unwell.
In effect, the researchers think that the children did actually become infected by the virus, but their immune systems were somehow able to mount an anti-virus response that was highly effective in restricting virus replication, unlike their parents.

That immune response was so effective, it could have brought the viral load so low, that it went under the sensitivity of the PCR testing, which is another issue that bears further examination, the team thinks.

"The discordance between the virological PCR results and clinical serological testing, despite an evident immune response, highlights limitations to the sensitivity of nasopharyngeal PCR and current diagnostic serology in children," the researchers write.
https://www.nature.com/articles/s41467-020-19545-8
https://www.sciencealert.com/everyone-in-this-family-has-coronaviru...

Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 10:06am

SCI-COM: Time for scientists to speak up and be heard

https://www.scidev.net/asia-pacific/governance/columns/time-for-sci...

Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 8:54am

A DNA-based nanogel for targeted chemotherapy

Current chemotherapy regimens slow cancer progression and save lives, but these powerful drugs affect both healthy and cancerous cells. 

Now, researchers reporting in ACS' Nano Letters have designed DNA-based nanogels that only break down and release their chemotherapeutic contents within cancer cells, minimizing the impacts on normal ones and potentially eliminating painful and uncomfortable side effects.

Once ingested or injected, chemotherapy medications move throughout the body, indiscriminately affecting healthy cells along with those that are responsible for disease. Since many of these drugs are toxic to all cells, the desired tumor shrinkage can be accompanied by undesirable side effects, such as hair loss, gastrointestinal issues and fatigue. Nanogels made of DNA are one way that these drugs could be delivered, but they would still enter all cells. Tianhu Li, Teck-Peng Loh and colleagues reasoned that biomarkers—proteins or other components that are present in differing amounts in cancer cells and their healthy counterparts—could play a role in breaking down a nanogel, causing it to release its contents only in those that are cancerous. A biomarker called FEN1, a repair enzyme that cuts certain types of DNA, is present in larger amounts in cancer cells compared with healthy ones. The researchers wanted to see whether they could design a DNA nanogel that would specifically be degraded in cancer cells by FEN1.

To make DNA nanogels, the researchers used special DNA structures that FEN1 could recognize and cut. With cell-free systems, the researchers observed that the DNA-based nanogels were broken down by FEN1 but not by other DNA repair enzymes or compounds. When live cells were incubated with the DNA-based nanogels, healthy ones did not have enough FEN1 to break them down, but cancer cells did. When the chemotherapeutic drugs doxorubicin and vinorelbine were incorporated into the nanogel, human breast cancer cells died at higher rates than normal, healthy breast cells.

These findings indicate DNA-based nanogels can introduce drugs into cancer cells with a high specificity, reducing the risk of side effects. The researchers say that the nanogels also could be used as probes for the biomarker enzyme, helping physicians more directly diagnose cancer compared with current methods.

Hao Zhang et al. Cancer Biomarker-Triggered Disintegrable DNA Nanogels for Intelligent Drug Delivery, Nano Letters (2020). DOI: 10.1021/acs.nanolett.0c03671

https://phys.org/news/2020-11-dna-based-nanogel-chemotherapy.html?u...

Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 8:32am

The magic of science: Making diamonds in minutes!

An international team of scientists has defied nature to make diamonds in minutes in a laboratory at room temperature—a process that normally requires billions of years, huge amounts of pressure and super-hot temperatures.

The scientific team made two types of diamonds: the kind found on an engagement ring and another type of diamond called Lonsdaleite, which is found in nature at the site of meteorite impacts such as Canyon Diablo in the US.

Natural diamonds are usually formed over billions of years, about 150 kilometres deep in the Earth where there are high pressures and temperatures above 1,000 degrees Celsius.

This new unexpected discovery shows both Lonsdaleite and regular diamond can also form at normal room temperatures by just applying high pressures—equivalent to 640 African elephants on the tip of a ballet shoe.

The twist in the story is how researchers  applied the pressure. As well as very high pressures, they allowed the carbon to also experience something called 'shear' - which is like a twisting or sliding force. This might allow the carbon atoms to move into place and form Lonsdaleite and regular diamond.

Dougal G. McCulloch et al. Investigation of Room Temperature Formation of the Ultra‐Hard Nanocarbons Diamond and Lonsdaleite, Small (2020). DOI: 10.1002/smll.202004695

https://phys.org/news/2020-11-scientists-insta-bling-room-temperatu...

Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 8:25am

How giant viruses fuel the evolution of algae

Viruses are tiny invaders that cause a wide range of disease. But viruses can do more than elicit sickness—and not all viruses are tiny.

Large viruses, especially those in the nucleo-cytoplasmic large DNA virus family, can integrate their genome into that of their host—dramatically changing the genetic makeup of that organism. This family of DNA viruses, otherwise known as "giant" viruses, has been known within scientific circles for quite some time, but the extent to which they affect eukaryotic organisms has been shrouded in mystery—till now.

Viruses play a central role in the evolution of life on Earth. One way that they shape the evolution of cellular life is through a process called endogenization, where they introduce new genomic material into their hosts. When a giant virus endogenizes into the genome of a host algae, it creates an enormous amount of raw material for evolution to work with.

Researchers discovered that 24 of the 65 genomes they analyzed had some kinds of viral signatures in their genomes, which originated from repeated endogenization of distinct viruses. In one algal organism, Tetrabaena socialis, researchers found that around 10 percent of its genes originated from a virus in the nucleo-cytoplasmic large DNA virus family.

Although the endogenization of viruses have been well studied, studies have mostly been limited to small RNA viruses, such as the human immunodeficiency virus (HIV), the retrovirus that is responsible for causing acquired immunodeficiency syndrome (AIDS).

Widespread endogenization of giant viruses shapes genomes of green algae, Nature (2020). DOI: 10.1038/s41586-020-2924-2 , www.nature.com/articles/s41586-020-2924-2

https://phys.org/news/2020-11-lurking-genomic-shadows-giant-viruses...

Comment by Dr. Krishna Kumari Challa on November 19, 2020 at 8:17am

Solar device can sterilize medical tools in off-grid areas without the need for electricity

Autoclaves, the devices used to sterilize medical tools in hospitals, clinics, and doctors' and dentists' offices, require a steady supply of pressurized steam at a temperature of about 125 degrees Celsius. This is usually provided by electrical or fuel-powered boilers, but in many rural areas, especially in the developing world, power can be unreliable or unavailable, and fuel is expensive.

Now, a team of researchers at MIT and the Indian Institute of Technology has come up with a way to generate the needed steam passively, using just the power of sunlight, with no need for fuel or electricity. The device, which would require a solar collector of about 2 square meters (or yards) to power a typical small-clinic autoclave, could maintain safe, sterile equipment at low cost in remote locations. A prototype was successfully tested in Mumbai, India.

The key to the new system is the use of optically transparent aerogel, a material developed over the last few years by Wang and her collaborators. The material is essentially a lightweight foam made of silica, the material of beach sand, and consists mostly of air. Light as it is, the material provides effective thermal insulation, reducing the rate of heat loss by tenfold.

This transparent insulating material is bonded onto the top of what is essentially off-the-shelf equipment for producing solar hot water, which consists of a copper plate with a heat-absorbing black coating, bonded to a set of pipes on the underside. As the sun heats the plate, water flowing through the pipes underneath picks up that heat. But with the addition of the transparent insulating layer on top, plus polished aluminum mirrors on each side of the plate to direct extra sunlight at the plate, the system can generate high-temperature steam instead of just hot water. The system uses gravity to feed water from a tank into the plate; the steam then rises to the top of the enclosure and is fed out through another pipe, which carries the pressurized steam to the autoclave. A steady supply of steam must be maintained for 30 minutes to achieve proper sterilization.

Joule, Zhao et al.: "A passive high-temperature high-pressure solar steam generator for medical sterilization" DOI: 10.1016/j.joule.2020.10.007,
www.cell.com/joule/fulltext/S2542-4351(20)30496-7

https://techxplore.com/news/2020-11-solar-device-sterilize-medical-...

Comment by Dr. Krishna Kumari Challa on November 18, 2020 at 10:46am

Why do people stop installing Indian style toilet?

Doctors have a solid explanation for this:

Orthopaedic surgeons are of the opinion that Indian habits of squatting for work in kitchen, sitting for various rituals, using Indian-style toilets are leading to increasing knee problems. This is largely among the rural population of India. Orthopaedic surgeons pointed out that the prevalence of the problem is high among the tribal population of Vidarbha due to frequent squatting for various jobs.

When a person tries to stand from squatting position, he puts seven times of his weight directly on his knees. Knees are not meant to bear all that pressure. It’s like more you use the knee, more prone are you to arthritis or any other problem related to the organs.

Stop squatting, avoid knee problems: Surgeons | Nagpur News - Times...

Comment by Dr. Krishna Kumari Challa on November 18, 2020 at 10:19am

Unexpectedly, The Universe Is Getting Hotter And Hotter as It Expands

The Universe is in a state of expansion and  the rate of expansion has been speeding up.

As this progresses, and the galaxy clusters and filaments of the Universe move farther apart, scientists theorize that the mean temperature of the Universe will gradually decline.

But according to new research led by the Center for Cosmology and AstroParticle Physics (CCAPP) at Ohio State University, it appears that the Universe is actually getting hotter as time goes on.

After probing the thermal history of the Universe over the last 10 billion years, the team concluded that the mean temperature of cosmic gas has increased more than 10 times and reached about 2.2 million K (~2.2 °C; 4 million °F) today.

Explanation by scientists for this heating:  As the Universe evolves, gravity pulls dark matter and gas in space together into galaxies and clusters of galaxies. The drag is violent - so violent that more and more gas is shocked and heated up.

https://iopscience.iop.org/article/10.3847/1538-4357/abb403

https://www.sciencealert.com/the-universe-is-getting-hotter-and-hot...

Comment by Dr. Krishna Kumari Challa on November 18, 2020 at 7:56am

New study could help predict which individuals are more susceptible to cancer-causing agents

New insights into the mechanisms behind how cancer-causing agents in the environment activate genetic recombination in DNA could help to explain some of the effects of exposure as well as predicting which individuals may be more susceptible to developing the disease, a new study has suggested.

Everyone is exposed to low levels of carcinogens (substances or radiation that promote the formation of cancer) in the environment. One of the most widely found is benzopyrene—a general chemical pollutant found in smoke from stoves such as wood burners, exhaust fumes and barbequed meat and fish. One active ingredient of benzopyrene, BPDE, directly damages the DNA sequence forming what is known as adducts which in turn promote cancer-causing mutations.

While models exist showing how BPDE causes these mutations, some of the pathways are still not understood. It is currently believed that a BPDE adducts cause mutations during DNA synthesis because they activate a process called translesion synthesis—where cells copy the DNA despite the presence of unrepaired damage to allow progression of the replication fork—and this induces mutations. However, evidence also suggests the involvement of another process called homologous recombination (HR) which works by copying other undamaged parts of the genome. HR proteins repair complex DNA damage such as breaks in the DNA strands and interstrand cross-links, and protect and recover stalled or broken replication forks.

This latest study treated human cell lines with BPDE before using molecular biology methods, such as microscopy, to characterize the homologous recombination pathway in detail. Results have offered new insights showing that HR proceeds by an unusual mechanism at BPDE adducts and the process can be activated even when there are no stalled or collapsed replication forks. Instead, it is activated at single-stranded gaps in the DNA that are generated by the re-priming activity of PrimPol—a protein encoded by the PRIMPOL gene in humans.

The findings also address longstanding questions by showing that at bulky DNA adducts, the exchanges between the sister chromatids (the identical copies formed by the DNA replication of a chromosome), products of HR that have been traditionally connected with replication fork collapse and DSB repair, are associated with the repair of post-replicative gaps. Furthermore, these post-replicative gaps are produced by PrimPol, shedding light on the function of PrimPol during DNA damage tolerance.

Ann Liza Piberger, Akhil Bowry, Richard D. W. Kelly, Alexandra K. Walker, Daniel González-Acosta, Laura J. Bailey, Aidan J. Doherty, Juan Méndez, Joanna R. Morris, Helen E. Bryant, Eva Petermann. PrimPol-dependent single-stranded gap formation mediates homologous recombination at bulky DNA adducts. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-19570-7

https://medicalxpress.com/news/2020-11-individuals-susceptible-canc...

Comment by Dr. Krishna Kumari Challa on November 17, 2020 at 9:41am

Cancer researchers discover new human salivary glands

Scientists Discover New Human Salivary Glands

The findings may have implications for radiotherapy, a cancer treatment that can cause damage to salivary glands and leave lasting complications.

https://www.the-scientist.com/news-opinion/scientists-discover-new-...

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