A newly discovered genetic variant protects against a particularly devastating form of early Alzheimer’s disease, raising scientists’ hopes of finding treatments that can prevent or slow the progression of this and other forms of the disease. The discovery is only the second gene variant reported to protect against autosomal dominant Alzheimer’s disease (ADAD), a form of Alzheimer’s caused by an inherited genetic mutation. People with ADAD begin to show signs of dementia in their mid-40s and rarely survive past the age of 60, study co-author Dr. Joseph Arboleda-Velasquez, a biomedical researcher at Harvard University, told Live Science.

The patient at the heart of the new study was a male member of a Colombian family that researchers have been following for a long time because they’re known carriers of the genetic mutation that causes ADAD. This man carried that gene, but instead of succumbing to early dementia, he remained healthy into his late sixties and developed only mild Alzheimer’s disease by age 72. He died at 73 years old of non-dementia-related causes.

“It was just really remarkable that he made it that far, despite the odds,” Arboleda-Velasquez said.

To find out how, Arboleda-Velasquez and his colleagues sequenced the man’s genes and came up with a list of genetic variants, or specific versions of genes, that might have been protective. One gene, RELN, popped out as intriguing because the protein it codes for binds to the same cellular receptors as the protein made by a well-known gene called APOE. One variant of the APOE gene raises the risk of Alzheimer’s by partially driving the formation of amyloid plaques, clusters of misfolded proteins considered to be a hallmark of Alzheimer’s.

The researchers studied the effects of the RELN gene in cells in lab dishes and in mice and discovered that the variant the man carried actually made the protein that RELN codes for bind more tightly to its receptor. This effect seems to help the RELN protein stabilize the protein tau, which can form tangles in the brain that serve as another tell-tale sign of Alzheimer’s.

The patient had reduced tau tangles in many parts of his brain compared to other Alzheimer’s patients, but some portions still showed tau pathology. Delving deeper into the gene variant and how it protects against early-onset Alzheimer’s is the crucial next step, said Dr. Kenneth Kosik, a neurologist at UC Santa Barbara who studies ADAD but who was not involved in the current research.

Source: https://www.livescience.com/

A team of scientists is calling for greater research into how sunlight inactivates SARS-CoV-2 after realizing there’s a glaring discrepancy between the most recent theory and experimental results. UC Santa Barbara mechanical engineer Paolo Luzzatto-Fegiz and colleagues noticed the virus was inactivated as much as eight times faster in experiments than the most recent theoretical model predicted.

“The theory assumes that inactivation works by having UVB hit the RNA of the virus, damaging it,” explained Luzzatto-Fegiz.

But the discrepancy suggests there’s something more going on than that, and figuring out what this is may be helpful for managing the virus.

UV light, or the ultraviolet part of the spectrum, is easily absorbed by certain nucleic acid bases in DNA and RNA, which can cause them to bond in ways that are hard to fix.

But not all UV light is the same. Longer UV waves, called UVA, don’t have quite enough energy to cause problems. It’s the mid-range UVB waves in sunlight that are primarily responsible for killing microbes and putting our own cells at risk of Sun damage.

Short-wave UVC radiation has been shown to be effective against viruses such as SARS-CoV-2, even while it’s still safely enveloped in human fluids.

But this type of UV doesn’t usually come into contact with Earth’s surface, thanks to the ozone layer.

“UVC is great for hospitals,” said co-author and Oregon State University toxicologist Julie McMurry. “But in other environments – for instance, kitchens or subways – UVC would interact with the particulates to produce harmful ozone.”

In July 2020, an experimental study tested the effects of UV light on SARS-CoV-2 in simulated saliva. They recorded the virus was inactivated when exposed to simulated sunlight for between 10-20 minutes.

“Natural sunlight may be effective as a disinfectant for contaminated nonporous materials,” Wood and colleagues concluded in the paper.

Luzzatto-Feigiz and team compared those results with a theory about how sunlight achieved this, which was published just a month later, and saw the math didn’t add up. his study found the SARS-CoV-2 virus was three times more sensitive to the UV in sunlight than influenza A, with 90 percent of the coronavirus‘s particles being inactivated after just half an hour of exposure to midday sunlight in summer.

By comparison, in winter light infectious particles could remain intact for days.

Source: https://www.news.ucsb.edu/
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https://www.sciencealert.com/

Researchers in UC Santa Barbara/Google scientist John Martinis’ group have made good on their claim to quantum supremacy. Using 53 entangled quantum bits (“qubits”), their Sycamore computer has taken on — and solved — a problem considered intractable for classical computers.

“A computation that would take 10,000 years on a classical supercomputer took 200 seconds on our quantum computer,” said Brooks Foxen, a graduate student researcher in the Martinis Group. “It is likely that the classical simulation time, currently estimated at 10,000 years, will be reduced by improved classical hardware and algorithms, but, since we are currently 1.5 billion times faster, we feel comfortable laying claim to this achievement.”

The feat is outlined in a paper in the journal Nature.

The milestone comes after roughly two decades of quantum computing research conducted by Martinis and his group, from the development of a single superconducting qubit to systems including architectures of 72 and, with Sycamore, 54 qubits (one didn’t perform) that take advantage of the both awe-inspiring and bizarre properties of quantum mechanics.

“The algorithm was chosen to emphasize the strengths of the quantum computer by leveraging the natural dynamics of the device,” said Ben Chiaro, another graduate student researcher in the Martinis Group. That is, the researchers wanted to test the computer’s ability to hold and rapidly manipulate a vast amount of complex, unstructured data.

“We basically wanted to produce an entangled state involving all of our qubits as quickly as we can,” Foxen said, “and so we settled on a sequence of operations that produced a complicated superposition state that, when measured, returned output (“bitstring”) with a probability determined by the specific sequence of operations used to prepare that particular superposition.” The exercise, which was to verify that the circuit’s output correspond to the sequence used to prepare the state, sampled the quantum circuit a million times in just a few minutes, exploring all possibilities — before the system could lose its quantum coherence. “We performed a fixed set of operations that entangles 53 qubits into a complex superposition state,” Chiaro explained. “This superposition state encodes the probability distribution. For the quantum computer, preparing this superposition state is accomplished by applying a sequence of tens of control pulses to each qubit in a matter of microseconds. We can prepare and then sample from this distribution by measuring the qubits a million times in 200 seconds.” “For classical computers, it is much more difficult to compute the outcome of these operations because it requires computing the probability of being in any one of the 2^53 possible states, where the 53 comes from the number of qubits — the exponential scaling is why people are interested in quantum computing to begin with,” Foxen said. “This is done by matrix multiplication, which is expensive for classical computers as the matrices become large.”

According to the new paper, the researchers used a method called cross-entropy benchmarking to compare the quantum circuit’s bitstring to its “corresponding ideal probability computed via simulation on a classical computer” to ascertain that the quantum computer was working correctly. “We made a lot of design choices in the development of our processor that are really advantageous,” said Chiaro. Among these advantages, he said, are the ability to experimentally tune the parameters of the individual qubits as well as their interactions.

Source: https://www.news.ucsb.edu/
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https://www.nature.com/