PNAS

Repeat After Me: Cold Does Not Increase Odds of Catching Cold

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Great article by Aaron Carroll in the New York Times on the myths behind the rhinovirus.

 

 

 

I’ve become somewhat known for medical myth-busting (having been a co-author of three books on the subject), so a fairly large number of emails sent to me are from people with articles or studies that they think prove me wrong.

This week, as a few of us sniffle with summer colds, the emails are all about a new study that they think proves that cold weather makes you more likely to catch a cold.

I’m sorry to say that this continues to be a myth. Research doesn’t support it.

This latest study, published in the Proceedings of the National Academy of Sciences, is complicated research of cells in laboratory conditions. The researchers showed that cells kept at 37 degrees Celsius were more likely to undergoapoptosis (basically, cell suicide) than cells kept at 33 degrees Celsius. Apoptosis is a way that we protect ourselves from infection. If the infected cells kill themselves, then there’s fewer chances for replication of the viruses that infect them.

I’m sorry to say that this continues to be a myth. Research doesn’t support it.

Read at NYT

‘Earth’s First Animal’ May be Simple Sea Sponge

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The first animal to appear on Earth was very likely the simple sea sponge.

New genetic analyses led by MIT researchers confirm that sea sponges are the source of a curious molecule found in rocks that are 640 million years old. These rocks significantly predate the Cambrian explosion — the period in which most animal groups took over the planet, 540 million years ago — suggesting that sea sponges may have been the first animals to inhabit the Earth.

“We brought together paleontological and genetic evidence to make a pretty strong case that this really is a molecular fossil of sponges,” said David Gold, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “This is some of the oldest evidence for animal life.”

The results are published today in the Proceedings of the National Academy of Sciences. Gold is the lead author on the paper, along with senior author and EAPS Professor Roger Summons.

 

Link to article

The Brain Forgets Things In Order To Conserve Energy, Lund University Study

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Our brains not only contain learning mechanisms but also forgetting mechanisms that erase “unnecessary” learning. A research group at Lund University in Sweden has now been able to describe one of these mechanisms at the cellular level.

The group’s results, published in the international journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), explain a theoretical learning phenomenon which has so far been difficult to understand.

The premise is that human or animal subjects can learn to associate a certain tone or light signal with a puff of air to the eye. The air puff makes the subject blink, and eventually they blink as soon as they hear the tone or see the light signal. The strange thing, however, is that if the tone and the light are presented together (and with the air puff), the learning does not improve, but gets worse.

 

Link to BioSpace article

Evolution of Kin Discrimination

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A bacterium’s ability to distinguish self from non-self can arise spontaneously, a study shows, reigniting questions of whether the trait can be considered an adaptation

 

Kin discrimination, in which an organism favors genetically related individuals over non-related individuals in social behaviors, can emerge among related bacterial strains that evolved from a common ancestor and were cultured under different laboratory conditions, according to a study on the social bacterium Myxococcus xanthus published today (July 6) in PNAS.

“Often when we see these kinds of social incompatibilities, or greater cooperation between close relatives than between strangers, it’s interpreted in the context of kin selection theory, which posits that cooperation—at least within species—will evolve when there’s preferential interactions that occur between relatives that share genes for cooperation,” said Gregory Velicer of ETH Zürich, who led the work. “[We have found that] reduced cooperation between different types can arise not because of any selection for incompatibility, per se, but rather simply because you had these different complex social systems evolving independently of one another.”

 

Full Article Link

Increased brain connectivity eases teenage impatience

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As many adults can attest, teenage behavior is often characterized by impulsivity and impatience. From a psychological perspective, this behavior can result either from disregard for future outcomes or from an over-emphasis on immediate rewards. Prior to the publication of a new study in PNAS, it wasn’t entirely clear which of these two components underlies developmental changes. This new paper examines impatience in teens and finds that it’s mostly a result of teens’ disregard for future outcomes. In their conclusions, the researchers state that increased control and increased integration of future-oriented thought are direct contributors to the changes in behavior that (hopefully) occur as we age.

 

 

Link to full article on Ars Technica

New way of using sound waves to find rare cancer cells

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The cancer cells that circulate in many patients’ bloodstreams are incredibly rare but potentially dangerous. They break off from existing tumors, traveling to new locations where they can grow into new tumors. Scientists have come up with a better way of looking for these cells—using invisible sound waves.

Existing ways to sort cancer cells out of blood are slow, and they can damage cells, rendering them useless for further tests. Sound waves, however, can gently nudge healthy and cancerous cells apart. Here’s how it works, as explained by MIT’s news office.

The researchers built microfluidic devices with two acoustic transducers, which produce sound waves, on either side of a microchannel. When the two waves meet, they combine to form a standing wave (a wave that remains in constant position). This wave produces pressure nodes, or lines of low pressure. Because the sound waves are tilted so they run across the microchannel at an angle, each cell encounters several pressure nodes as it flows through the channel. As cells encounter each node, they are pushed further to the side of the channel; the distance of cell movement depends on their size and other properties, such as compressibility.

Full Story

Gut’s Earliest Bacterial Colonizers

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Gut’s Earliest Bacterial Colonizers

The pace at which bacterial groups take root in the gastrointestinal tracts of premature infants is more tied to developmental age than time since birth.

Infants start out mostly microbe-free but quickly acquire gut bacteria, which take root in three successive groups. First, Bacilli dominate. Then Gammaproteobacteria surge, followed by Clostridia. But the pace at which these bacterial groups colonize the gastrointestinal tract depends on the time since the babies were conceived, not since when they were born. And time since conception appears to have more of an influence on the infant gut microbiome than other factors, such as exposure to antibiotics, whether babies were born vaginally or by cesarean section, and if they were breastfed. These are a few of the findings from a survey of 922 fecal samples collected from 58 premature babies, published today (August 11) in PNAS.

Full story at TheScientist