ANTIBIOTICS GIVE RISE TO NEW COMMUNITIES OF HARMFUL BACTERIA

Most people have taken an antibiotic to treat a bacterial infection. Now researchers from the University of North Carolina at Chapel Hill and the University of San Diego, La Jolla, reveal that the way we often think about antibiotics -- as straightforward killing machines -- needs to be revised.

 The work, led by Elizabeth Shank, an assistant professor of biology in the UNC-Chapel Hill College of Arts and Sciences as well as microbiology and immunology in the UNC-Chapel Hill School of Medicine, and Rachel Bleich, a graduate student in the UNC-Chapel Hill Eshelman School of Pharmacy, not only adds a new dimension to how we treat infections, but also might change our understanding of why bacteria produce antibiotics in the first place.

"For a long time we've thought that bacteria make antibiotics for the same reasons that we love them -- because they kill other bacteria," said Shank, whose work appears in the February 23 Early Edition of the Proceedings of the National Academy of Sciences. "However, we've also known that antibiotics can sometimes have pesky side-effects, like stimulating biofilm formation."

Shank and her team now show that this side-effect -- the production of biofilms -- is not a side-effect after all, suggesting that bacteria may have evolved to produce antibiotics in order to produce biofilms and not only for their killing abilities.

Biofilms are communities of bacteria that form on surfaces, a phenomenon dentists usually refer to as plaque. Biofilms are everywhere. In many cases, biofilms can be beneficial, such as when they protect plant roots from pathogens. But they can also harm, for instance when they form on medical catheters or feeding tubes in patients, causing disease.

"It was never that surprising that many bacteria form biofilms in response to antibiotics: it helps them survive an attack. But it's always been thought that this was a general stress response, a kind of non-specific side-effect of antibiotics. Our findings indicate that this isn't true. We've discovered an antibiotic that very specifically activates biofilm formation, and does so in a way that has nothing to do with its ability to kill."

Shank and her team previously reported that the soil bacterium Bacillus cereus could stimulate the bacterium Bacillus subtilis to form a biofilm in response to an unknown secreted signal. B. subtilis is found in soil and the gastrointestinal tract of humans.

Using imaging mass spectrometry, they subsequently identified the signaling compound that induced biofilm production as thiocillin, a member of a class of antibiotics called thiazolyl peptide antibiotics, which are produced by a range of bacteria.

At that point, Shank and her colleagues knew thiocillin had two very specific and different functions, but they didn't know why -- and wanted to know how it worked. That's when they modified thiocillin's structure in a way that eliminated thiocillin's antibiotic activity, but did not halt biofilm production.

"That suggests that antibiotics can independently and simultaneously induce potentially dangerous biofilm formation in other bacteria and that these activities may be acting through specific signaling pathways," said Shank. "It has generated further discussion about the evolution of antibiotic activity, and the fact that some antibiotics being used therapeutically may induce biofilm formation in a strong and specific way, which has broad implications for human health."

PLEASURE OF LEARNING NEW WORDS

From our very first years, we are intrinsically motivated to learn new words and their meanings. First language acquisition occurs within a permanent emotional interaction between parents and children. However, the exact mechanism behind the human drive to acquire communicative linguistic skills is yet to be established.

In a study published in the journal Current Biology, researchers from the University of Barcelona (UB), the Bellvitge Biomedical Research Institute (IDIBELL) and the Otto von Guericke University Magdeburg (Germany) have experimentally proved that human adult word learning exhibit activation not only of cortical language regions but also of the ventral striatum, a core region of reward processing. Results confirm that the motivation to learn is preserved throughout the lifespan, helping adults to acquire a second language.

Researchers determined that the reward region that is activated is the same that answers to a wide range of stimuli, including food, sex, drugs or game. "The main objective of the study was to know to what extent language learning activates subcortical reward and motivational systems," explains Pablo Ripollés, PhD student at UB-IDIBELL and first author of the article. "Moreover, the fact that language could be favoured by this type of circuitries is an interesting hypothesis from an evolutionary point of view," points out the expert.

According to Antoni Rodríguez Fornells, UB lecturer and ICREA researcher at IDIBELL, "the language region has been traditionally located at an apparently encapsulated cortical structure which has never been related to reward circuitries, which are considered much older from an evolutionary perspective." "The study -- he adds -- questions whether language only comes from cortical evolution or structured mechanisms and suggests that emotions may influence language acquisition processes."

Subcortical areas are closely related to those that help to store information. Therefore, those facts or pieces of information that awake an emotion are more easily to remember and learn.

Motivation for learning a second language

By using diffusion tensor imaging, UB-IDIBELL researchers reconstructed the white matter pathways that link brain regions in each participant. Experts were able to correlate the number of new words learnt by each person during the experiment with a low myelin index, a measure of structure integrity. Results proved that subjects who presented higher myelin concentrations in the structures that carry information to the ventral striatum -- in other words, those that are best connected to the reward area -- were able to learn more words.

"Results provide a neural substrate of the influence that reward and motivation circuitries may have in learning words from context," affirms Josep Marco Pallarès, UB-IDIBELL researcher. The activation of these circuitries during word learning suggests future research lines aimed at stimulating reward regions to improve language learning in patients with linguistic problems.

The fact that non-linguistic subcortical mechanisms, which are much older from an evolutionary perspective, work together with language cortical regions -- which appeared latter -- suggests new language theories trying to explain how reward mechanisms have influenced and supported one of our primal urges: the desire to acquire language and to communicate.

Experiment with words and gambling

Researchers carried out an experiment with thirty-six adults who participated in two magnetic resonance sessions. On the first one, functional magnetic resonance was used to measure participants' brain activity while they perform two different tasks. This technique enables to detect accurately what brain regions are active while a person is performing a certain activity. In the first task, participants must learn the meaning of some new words from context in two different sentences. For instance, subjects saw on a screen the sentences: "Every Sunday the grandmother went to the jedin" and "The man was buried in the jedin." Considering both sentences, participants could learn that the word jedin means "graveyard." Then, participants completed two runs of a standard-event-related money gambling task.

The experiment revealed that when subjects inferred and memorized the meaning of a new word, brain activity in the ventral striatum was increased. Indeed, the same ventral striatum activation was observed when earning money in gambling. Therefore, to learn the meaning of a new word activates reward and motivational circuitries like in gambling activities. Moreover, it was observed that word learning produce an increase of brain activity synchronization between the ventral striatum and cortical language regions.

SMARTPHONE APP THAT CHECKS FOR JAUNDICE IN NEW BORNS

   Researchers, including one of Indian-origin, have developed a smartphone app that checks for jaundice in newborns and can deliver results to parents and pediatricians within minutes.

Jaundice is a common condition in babies less than a week old. Skin that turns yellow can be a sure sign that a newborn is jaundiced and isn't adequately eliminating the chemical bilirubin.

However, that discolouration is sometimes hard to see, and severe jaundice left untreated can harm a baby.

The new app, developed by the University of Washington engineers and physicians, could serve as a screening tool to determine whether a baby needs a blood test - the gold standard for detecting high levels of bilirubin.

"Virtually every baby gets jaundiced, and we're sending them home from the hospital even before bilirubin levels reach their peak," said James Taylor, a UW professor of pediatrics and medical director of the newborn nursery at UW Medical Center.

"This smartphone test is really for babies in the first few days after they go home. A parent or health care provider can get an accurate picture of bilirubin to bridge the gap after leaving the hospital," Taylor said.

The app, called BiliCam, uses a smartphone's camera and flash and a colour calibration card.

A parent or health care professional would download the app, place the card on her baby's belly, then take a picture with the card in view. The card calibrates and accounts for different lighting conditions and skin tones.

Data from the photo are sent to the cloud and are analysed by machine-learning algorithms, and a report on the newborn's bilirubin levels is sent almost instantly to the parent's phone.

"This is a way to provide peace of mind for the parents of newborns," said Shwetak Patel, a UW associate professor of computer science and engineering and of electrical engineering.

A noninvasive jaundice screening tool is available in some hospitals, but the instrument costs several thousand dollars and isn't feasible for home use, researchers said.

Currently, both doctors and parents assess jaundice by looking for the yellow colour in a newborn's skin, but this visual assessment is only moderately accurate.

The UW team developed BiliCam to be easy to use and affordable for both clinicians and parents, especially during the first several days after birth when it's crucial to check for jaundice.

The team ran a clinical study with 100 newborns and their families at UW Medical Center.

They used a blood test, the current screening tool used in hospitals, and BiliCam to test the babies when they were between two and five days old.

They found that BiliCam performed as well as or better than the current screening tool. Though it wouldn't replace a blood test, BiliCam could let parents know if they should take that next step, researchers said.